JP6952020B2 - Reduction of environmental pollution and pollution caused by coal combustion - Google Patents

Description

This application is valid US application No. 1 filed on March 14, 2014. 14/210, 909 Priority and Provisional US Application No. filed on March 15, 2013. Claims 61 / 788,442 interests, the entire disclosure of which is incorporated by reference.

The present invention provides compositions and methods that reduce the levels of mercury, nitrogen oxides and / or sulfur oxides emitted into the atmosphere during combustion of mercury-containing fuels such as coal. In particular, the present invention provides the addition of various halogens and other adsorbents to the coal combustion system during combustion. The use of adsorbents reduces pollutant emissions and prevents contamination of the furnace.

There are significant coal sources around the world that can meet most of the world's energy needs in the next two centuries. High-sulfur coal is abundant, but requires a purification process to prevent excess sulfur from being released into the atmosphere during combustion. In the United States, low-sulfur coal exists in the form of low-BTU coal in the Powder River Basin in Wyoming and Montana, in lignite deposits in the north-central north and south Dakota, and in lignite deposits in Texas. .. However, even when coal contains low sulfur, they still contain non-negligible levels of elemental mercury and mercury oxide and / or other heavy metals.

Unfortunately, mercury volatilizes at least partially during coal combustion. As a result, mercury does not tend to stay in the ash, but rather becomes a component of combustion emissions. Without purification, mercury tends to be released into the atmosphere from coal combustion facilities. Currently, some mercury is captured by equipment, for example in wet scrubbers and SCR control systems. However, most mercury is not captured and is therefore released through the exhaust stack.

Mercury release into the atmosphere in the United States is about 50 tons per year. A significant fraction of the emissions are those from coal combustion facilities (eg, utility facilities). Mercury is a known environmental pollution and leads to health problems for both humans and non-human animals. To protect public health and to protect the environment, the utility industry continues to develop, test, and implement systems to reduce mercury emission levels from its factories. In the combustion of carbonaceous materials, there is a need for a method in which mercury and other unwanted compounds are trapped and retained after the combustion phase so that they are not released into the atmosphere.

Other pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx) are released during coal combustion. These exacerbate environmental problems such as smog and acid rain. Moreover, industry continues to actively seek ways to reduce these pollutants.

The owners of certain coal facilities are eligible for tax deductions for efforts to reduce the release of these pollutants under Section 45 of the IRS Regulation. Under certain circumstances, these owners have seen unwanted furnace pollution. For example, when burning low-sulfur subbituminous coal as fuel, deposits tend to form on the surface of the boiler tube, which results in a decrease in heat exchange efficiency and an increase in operating costs.

Therefore, management needs an adsorbent composition and a method of use that can achieve the desired reduction in air pollution without reducing thermal efficiency.

In particular, the adsorbent used with subbituminous coal and lignite must contain low levels of alkali. Conventional adsorbents with high alkaline levels can result in fouling of the furnace that burns them. By reducing the alkalinity of the adsorbent, management can minimize the sodium and potassium used for unnecessary reactions in the gas phase that lead to the formation of deposits on the boiler surface and other parts.

Adsorbents can be used to prepare refined coal that can be burned to reduce the release of one or more mercury, nitrogen (as NOx) and sulfur (as SOx). A method for producing refined coal comprises mixing subbituminous coal (or lignite) with an adsorbent composition. In one embodiment, the adsorbent is 0.001 to 1% by weight of liquid adsorbent and 0.1 to 10% by weight of powder adsorbent, wherein the proportion is based on the total weight of refined coal. It is the weight. The liquid adsorbent contains a bromine compound, the powder adsorbent contains calcium, silica, alumina, and further contains less than 1% by weight of Na ₂ O and less than 1% by weight of K ₂ O, where the powder adsorbent is It further contains less than 0.1% by weight of chlorine.

In one aspect, the powder adsorbent comprises cement kiln dust (CKD), which is useful for reducing NOx emissions, and if the CKD contains a high concentration of alkali, with improvement of this, some CKD may have total alkali content. Is replaced by a lower alkaline substance to achieve specifications of less than 2% or less than 1%. In various embodiments, the powder adsorbent also meets the low chlorine specifications to reduce fouling in subbituminous and lignite.

In various embodiments, the present invention provides compositions and methods that reduce the release of mercury, nitrogen oxides (NOx) and sulfur oxides (SOx) resulting from the combustion of mercury-containing fuels such as coal. A commercially valuable embodiment is the use of the present invention to reduce the emission of nitrogen, sulfur and / or mercury from coal combustion facilities in order to protect the environment and comply with government regulations and treaty obligations. Improvements to the powder adsorbent provide better practice by reducing fouling of the coal-burning furnace, while at the same time not having a detrimental effect on the removal of environmental pollutants such as NOx and SOx.

In various embodiments, the methods of the invention prevent mercury release from point sources such as coal fuel facilities into the atmosphere by capturing mercury in the ash while minimizing reactor fouling that can reduce the efficiency of the furnace. do. In addition, the method prevents mercury and other heavy metals from being released into the natural environment due to leaching from solid waste such as coal ash produced by the combustion of mercury-containing coal. Both of these methods prevent mercury from entering the body of water. Therefore, prevention or reduction of mercury emissions from facilities such as coal combustion facilities can vary, including less air pollution, less water pollution, and less hazardous waste production, and the resulting less soil pollution. Lead to environmental benefits. For convenience, but not limited to, an advantageous feature of the present invention is described as preventing air, water, and soil contamination by mercury or other heavy metals.

In one embodiment, there is provided a method of burning coal in a furnace to reduce the release of NOx and at least one SOx and mercury. The method involves burning refined coal in a furnace. The refined coal is, in that order, a mixture of subbituminous coal, a bromine compound and a powder adsorbent. The powder adsorbent contains calcium, silica, alumina, and based on the weight of the powder adsorbent, with a low alkalinity value of _{less than 1% by weight Na 2} O and less than 1% by weight K _{2 O, and preferably less than 1% by weight.} It is further characterized by low chlorine values of less than 0.5%, less than 0.3%, or less than 0.1%. In various embodiments, the treatment level of the bromine compound is 0.001 to 1.0% by weight, while the treatment level of the usual powder adsorbent is 0.1 to 10% by weight based on the weight of coal. In various embodiments, the powder adsorbent comprises a CKD or a mixture of CKD and other low alkaline powders described herein. The powder adsorbent may also include aluminosilicate clays such as kaolin or metakaolin.

In another embodiment, there is provided a method of generating energy by combustion of mercury containing subbituminous coal in a furnace of a coal combustion facility. The method first comprises administering the first adsorbent composition to the coal and transporting the coal containing the administered first adsorbent to a furnace. At the same time as transporting the coal containing the added first adsorbent, the second adsorbent is added to the furnace. Then, in the presence of the first and second adsorbents, coal is burned in the furnace to generate thermal energy and ash. The first adsorbent comprises a bromine compound, a second adsorbent more than 40% by weight CaO, 10 wt% more _SiO 2, 2 to 10% of _Al 2 _O 3, 1 to 5% of _Fe 2 O _3, and a 1-5% MgO, 1% by weight less than _Na 2 O, and Ka ₂ O components of less than 1%. In embodiments, the second adsorbent has less than 0.5% chlorine.

In another embodiment, a method for producing refined charcoal is provided. The refined coal contains subbituminous coal and contains an added adsorbent component. The method comprises adding and mixing coal, a liquid adsorbent (eg 0.001-1 wt% relative to coal) and a powder adsorbent (eg 0.1-10 wt% relative to coal). The liquid adsorbent comprises a bromine compound and a powder adsorbent, wherein the powder adsorbent contains more than 40% CaO, more than 10% SiO ₂ , 2-10% Al ₂ O ₃ , 1 to. It contains 5% Fe ₂ O ₃ , 1-5% Mg _{O, less than 1% Na 2} O, and less than 1% K _{2 O.} In various embodiments, the powder adsorbent is further characterized as having less than 0.5% chlorine or less than 0.1% chlorine.

The use of powder adsorbents mentioned to be advantageous, especially compositions with low total alkali content, low chlorine or low in both, is used in furnaces that burn subbituminous or lignite coals such as powder river basin (PRB) coal. It was found to be effective in reducing fouling. The use of the improved adsorbents described herein allows the reactor operator to qualify for certain tax deductions under US IRS regulations in accordance with environmental regulations, while at the same time undesired pollution of the furnace and related facilities. Can be avoided.

Further examples of each limited embodiment are described below. It should be understood that the various components and method steps described herein can be combined and adapted to provide other embodiments not literally described or exemplified. The embodiments allow one of ordinary skill in the art to carry out the invention and provide notable environmental and operational benefits.

Various to process coal before combustion and / or to ensure a finished form of refractory structure that produces various advantages in the method, preferably at the lowest temperature, for addition to the flame or downstream of the flame. Use in combination with adsorbent components. If the component is added to coal prior to combustion, the product is refined coal, the use of this refined coal may reduce environmental pollution and qualify for certain tax deductions in the United States.

The adsorbent composition comprises calcium, alumina, silica and halogen. When burning subbituminous coal or lignite such as powder river basin coal, the adsorbent K ₂ O is maintained at a maximum of 1% and the adsorbent Na ₂ O is maintained at a maximum of 1% to reduce pollution. % Is based on the weight of the powder adsorbent containing calcium, alumina, silica and other components. In embodiments, Na ₂ O and K ₂ O are less than 0.5% or less than 0.1%, respectively. Furthermore, in various embodiments, it has also been found advantageous to supply a powder adsorbent having a low chlorine value (eg, <0.5%, <0.3% or <0.1%).

Calcium is supplied by addition to a powder adsorbent mixture or a composition having a non-negligible amount of calcium. For example, many alkaline powders contain 20% or more calcium based on CaO. Examples are limestone, lime, calcium oxide, calcium hydroxide (slaked lime), Portland cement and other industrial or process by-products, and calcium-containing aluminosilicate minerals. The content of silica and alumina is based on the equivalents of _{SiO 2} and Al ₂ O ₃ , even though it is understood that silica and alumina are often present in more complex chemical or molecular forms.

In various embodiments, it is advantageous that the powder adsorbent comprises an effective amount of cement kiln dust (CKD) that is believed to result in NOx reduction from the coal combustion facility. Some CKD have a relatively high chlorine content (as high as 10%). When using CKD, depending on the CKD source and its original content of alkali and chlorine, the powder obtained when burning subbituminous or lignite can result in too high an alkali and / or chlorine for best results. If so, mix some CKD with other ingredients low in sodium and potassium, preferably <1% Na ₂ O and <1% K ₂ O specifications, or <0.5. It is advantageous to achieve the specifications of% Na ₂ O and <0.5% K _{2 O.} Such low alkalinity materials are ground cement kiln clinker (cement kiln clinker that may or may not meet the specifications of the cement product, and then cement kiln clinker that is ground to mix with CKD); kiln feed. (Supply flow introduced into cement kilns, including all components that make cement such as Ca, Mg, Si, Al, Fe); Convertible cement (to create space for introducing certain new cement products) Cement products in emptied silos); dry clinker (clinker collected and stored in crushed area prior to CKD addition); storage CKD (CKD from storage location or waste storage); and limestone include. Further environmental benefits are achieved by their use of the adsorbents described herein to the extent that any of these materials represent waste products that must be discarded or landfilled.

In various embodiments, the components together: reduce the release of mercury, nitrogen oxides, and sulfur oxides;
-Reduces the release of mercury elements and mercury oxide;
・ Improve the efficiency of coal combustion process through de-slugging of boiler pipes;
・ Prevents contamination of the furnace with unwanted deposits;
-Increased levels of Hg, As, Pb, and / or Cl in coal ash;
-Reduce the level of leachable heavy metals (eg Hg) in the ash to levels preferably below the detection limit; and-produce advanced cementum ash products.

Unless otherwise specified as used herein, all% are based on weight. It should be noted that the various materials of the chemical compositions described herein are represented by samples calculated from elemental analysis, usually determined by X-ray fluorescence techniques. Although various simple oxides may and are present in materials, in more complex compounds, oxide analysis is a useful method for expressing compound concentrations for individual compositions.

In a typical coal burning facility, coal leads to railcars. Coal is refined coal if the adsorbent has already been administered. If the adsorbent has not yet been administered, the coal is raw coal. In a typical exemplary embodiment, the coal is transported to a belt receiver, which guides the coal to the mixer. After the mixer, the coal is unloaded on the supply belt and placed in the coal storage area. Coal storage areas usually have grate and vessels; from which coal is transported by belt to open storage areas, sometimes called bunkers. Coal from the bunker or crusher can be supplied to the stoker furnace. In a furnace that burns pulverized coal, the coal is transported by belt or other means to a crusher such as a crusher and finally to a pulverizer. In the storage system, coal is pulverized and transported by air or gas to a dust collector, and the pulverized coal is transported to a storage container and supplied to a furnace as needed. In a direct fuel system, coal is pulverized and transported directly to the furnace. In a semi-direct system, coal is introduced from the pulverizer to the cyclone dust collector. Coal is supplied directly to the furnace from the cyclone dust collector.

During operation, coal is supplied into the furnace and burned in the presence of oxygen. With high btu fuels, typical flame temperatures range from 2700 ° F (about 1480 ° C) to about 3000 ° F (about 1640 ° C) or higher in the combustion chamber [eg 3300 ° F (about 1815 ° C) to 3600 ° F. It is on the order of (about 1982 ° C).

Refined coal is produced by adding an adsorbent to coal before combustion. Adsorbents can be added by the coal producer, transported to the furnace by the operator, or refined coal can be produced at or near the operator's property. In the case of refined charcoal, all adsorbent compositions are supplied to the furnace for combustion.

In various other embodiments, the adsorbent composition according to the invention is added to the raw coal or various parts of the furnace during combustion. In a mixer, in a belt receiver or feed belt, in a coal storage area, in a dust collector, before or during pulverization in an unrestricted manner and / or while being transported from the pulverizer to a furnace for combustion. In the storage container, in the cyclone dust collector, in the crusher, the adsorbent is added to the coal. Conveniently, in various embodiments, an adsorbent is added to the coal during the step of mixing the coal, such as in a mixer or mill.

Alternatively or additionally, the adsorbent composition is added to the coal combustion system by injecting the composition into the furnace during fuel combustion. In a preferred embodiment, the composition is injected into or near a fireball (eg, the temperature is greater than 2000 ° F. or greater than 2300 ° F. or greater than 2700 ° F.). Efficiently add the adsorbent to the flame, with the overfire air, with the overfire air, etc., along with the fuel, along with the main combustion air, according to the burner and furnace operating parameter design. Also, depending on the design and operation of the furnace, the adsorbent is injected from one or more surfaces of the furnace and / or from one or more corners of the furnace. The addition of the adsorbent composition and the adsorbent component is such that the injection temperature is high enough and / or the aerodynamics of the set burner and furnace ensure that the powder adsorbent is well mixed with the fuel and / or combustion products. It tends to be the most efficient when guiding. Alternatively or additionally, the adsorbent is added to the flame and the convection path downstream of the furnace. In various embodiments, the optimum injection or dosing point of the adsorbent is the parameters (injection rate, injection position,) that form the furnace and result in the best mixing of the adsorbent, coal and the desired resulting combustion product. It is found by selecting the distance above the flame, the distance of the wall, the method of powder injection, etc.).

In a coal combustion system, hot combustion gas and air move by convection away from the flame through a downstream convection path (ie, downstream associated with the fireball). The convective path of the facility includes multiple regions characterized by the temperature of the gas and combustion products in each region. Normally, the temperature of the combustion gas drops as it moves downstream from the fireball. Fly ash and combustion gas are in a region where the temperature of the coal in one embodiment is constantly lowered from the furnace where the coal is burned at a temperature of about 2700 ° F to 3600 ° F (about 1480 ° C to 1650 ° C) through the downstream of the convection path. Moving. For example, downstream of a fireball is a temperature range below 2700 ° F. Further downstream, it reaches a position where the temperature is cooled to about 1500 ° F. Between the two positions is a region having a temperature of about 1500 ° F to about 2700 ° F. Further downstream, it reaches a region of less than 1500 ° F. Further along the convection flow path, the gas and fly ash pass through a low temperature region before the gas is discharged from the exhaust stack before reaching a bag house or electrostatic precipitator, which typically has a temperature of about 300 ° F. ..

Combustion gases include carbon dioxide as well as various undesired gases including sulfur, nitrogen and mercury. The convection channel is also filled with various ash carried with the hot gas. A particulate removal system is used to remove the ash before it is released into the atmosphere. Such various removal systems, such as electrostatic precipitators and bug houses, are usually placed in convection channels. In addition, the chemical cleaning device can be placed in the convection channel. In addition, various devices may be provided for monitoring gas components such as sulfur (as SOx), nitrogen (as NOx) and mercury.

Thus, in various embodiments, the method of the present invention directs the adsorbent to the furnace during combustion (addition of "co-firing");
Directly to fuels such as coal before burning (addition of "pre-combustion" for the production of refined coal);
After fueling in a temperature range above 500 ° C and preferably above 800 ° C, administration directly to the gas stream (“post-combustion” addition); or a combination of pre-combustion, co-firing, and post-combustion additions. I need.

Administration of the adsorbent is carried out "to the coal combustion system" by any method or any combination of pre-combustion, co-firing or post-combustion. When an adsorbent is added to a coal combustion system, the coal or other fuel is believed to be burned "in the presence" of various adsorbents, adsorbent compositions or adsorbent components.

In a preferred embodiment, the downstream addition is carried out at a temperature of about 1500 ° F (815.5 ° C) to about 2700 ° F (1482.2 ° C). In some embodiments, the cutoff point or division between "to the furnace", "to the fireball" and "to the convection channel" is rather arbitrary, depending on the details of the furnace design and the placement of the convection channel. could be. At some point, the combustion gas clearly separates from what is the combustion chamber or furnace and flows into the convection flow path of the downstream gas apparently in the fuel or furnace. However, many of the furnaces are very large, so it is possible to add an adsorbent to the furnace at a considerable distance to supply fuel and air to form a fireball. For example, some furnaces have overfire air inlets designed to supply more oxygen to the upper position of the fireball, especially to achieve more complete combustion and / or emission control such as nitrogen oxides. Has. The overfire vent can be 20 feet or more above the fuel injection. In various embodiments, a fireball with coal supplied above the coal supply, above or below the overfire air vent, or higher in the combustion chamber (just below the furnace opening or furnace opening). Inject the adsorbent component or composition directly into it. Each of these positions is characterized by temperature and turbulence conditions that result in mixing of the adsorbent with the fuel and / or combustion products (eg fly ash). In embodiments, with respect to administering the adsorbent composition to the furnace or downstream of the furnace, the administration has a temperature above about 1500 ° F, preferably above about 2000 ° F, more preferably above about 2300 ° F, and More preferably, the temperature is above about 2700 ° F.

In the various embodiments described herein, adsorbent compositions that tend to reduce or modify the emission of mercury, nitrogen and / or sulfur from coal combustion facilities also burn high concentrations of cementum fuel. Has the beneficial effect of giving the ash produced by. As a result, the ash can be commercially used as a partial or complete substitute for Portland cement in various cement and concrete products.

In various embodiments, burning coal with the adsorbent composition described in the present invention produces ash with elevated levels of heavy metals as compared to coal burned without the adsorbent, but to it. Nevertheless, it contains lower levels of leachable heavy metals than the ash produced without the use of adsorbents. As a result, the ash is safe to handle and also safe to sell commercially, for example as a cement mixture.

To obtain the ash product, the carbonaceous fuel is burned to generate thermal energy from the combustion of the carbonaceous material. Non-combustible raw materials and particle combustion products form ash, and some ash is collected at the bottom of the furnace, but most of the ash is used as fly ash from fuel by a dust collector or filter (for example, a bug house in a coal combustion facility). Collected. The contents of bottom ash and fly ash depend on the chemical composition of the coal and the amount and composition of the adsorbent component added to the coal combustion facility during combustion.

In various embodiments, mercury emissions from coal combustion facilities are monitored. Monitor the release of elemental mercury, mercury oxide, or both. The elemental mercury means mercury in the ground state or zero oxidation state, while mercury oxide means mercury in the +1 or +2 oxidation state. Depending on the mercury level in the fuel gas before discharge from the plant, the amount of adsorbent composition added in pre-combustion, co-firing, and / or post-combustion is increased, reduced or maintained unchanged. In general, it is desirable to remove high levels of mercury as high as practical levels. In embodiments, at least 40% to 90% or less and more mercury removal can be achieved based on the total amount of mercury in the coal. This amount indicates mercury removed from the fuel gas, so mercury is not released into the atmosphere through the exhaust stack. In this aspect, the amount corresponds to a percentage of the amount of reduced mercury emission from the facility as compared to coal combustion without an adsorbent. Removal of mercury from fuel gas usually leads to elevated levels of mercury in the ash. Minimize the amount of adsorbent added to the coal combustion process to reduce the total amount of ash produced in the furnace. For this reason, in many embodiments, it is desirable to measure the amount of mercury released to adjust the rate of addition of the adsorbent composition to achieve the desired mercury reduction without adding excess material to the system.

In various embodiments of burning coal or other fuels with the adsorbent component to be added, mercury and other heavy metals in coal such as arsenic, antimony, lead and other metals are recorded in the baghouse or electrostatic collector. And become part of the total ash content in coal combustion plants; or in addition, mercury and heavy metals are found in the ash bottom. In this way, the emission of mercury and other heavy metals from the facility is reduced.

Mercury and other heavy metals in ash are generally present, even though they tend to be present in the ash at higher levels compared to the ash produced by burning coal without the adsorbent components described herein. Durable to leaching under acidic conditions. Advantageously, the heavy metals in the ash do not exude above regulatory levels; in fact, the ash is usually produced by burning with an adsorbent, even if it contains higher absolute values of heavy metals. A reduction in the concentration of leachable heavy metals is observed in the ash on a ppm basis. This is because combustion ash (coal ash), in addition to the cementum properties of ash, is worth marketing and using, for example, as a cementitious material for the production of Portland cement and concrete products and ready mixes. ..

In a preferred embodiment, heavy metal leaching is monitored or periodically or continuously during combustion. The US Environmental Protection Agency's TCLP method is a commonly used method. The amount of the adsorbent, in particular the amount of sorbent components with Si (SiO ₂ or equivalent) and / or Al (Al ₂ O ₃ or equivalent) is the analysis result to maintain the leaching in a desired range Adjusted based on.

In one embodiment, a coal burning method for reducing the amount of mercury released into the atmosphere is provided. The method comprises administering an adsorbent composition comprising a halogen compound to a system that burns coal. The halogen compound is preferably a bromine compound; in a preferred embodiment, the adsorbent is free of alkali metal compounds to avoid corrosion by boiler tubes or other furnace components. Coal is burned in a furnace to produce ash and combustion gases. Combustion gas contains mercury, sulfur and other components. In order to limit the release into the atmosphere and to achieve the desired mercury reduction in the combustion gas, the mercury level in the combustion gas is preferably monitored, for example by concentration analytical measurements. In a preferred embodiment, the amount of adsorbent composition administered is adjusted (ie, increased, decreased, or in some cases it, depending on the mercury level value measured in the combustion gas. Adjust by deciding to keep it unchanged). In a preferred embodiment, the pre-combustion of coal is added to the system by administering an adsorbent and then the coal containing the adsorbent is transported into the furnace for combustion.

In another embodiment, an adsorbent component containing a halogen (preferably bromine or iodine, and more preferably bromine) compound and at least one aluminosilicate material is administered to the coal combustion system. The components are added to the adsorbent composition alone or separately from the composition and, if necessary, to the in-combustion furnace in the pre-combustion of coal or to the combustion gas downstream of the furnace at a suitable temperature. In a preferred embodiment, the component is added to the pre-combustion of the coal, and then the coal containing the adsorbent is transported to the furnace for combustion. As already mentioned, mercury is preferably monitored in the fuel gas and the adsorbent dosing rate is adjusted according to the measured mercury level value. Halogen results in reduced mercury release levels, while aluminosilicates result in non-leaching of mercury trapped in the ash.

In a related embodiment, in a coal combustion system or incinerator, a method of reducing the leaching of mercury and / or other heavy metals from the ash produced by the combustion of coal or other fuels is a method of reducing the leachation of mercury and / or other heavy metals in the in-combustion incinerator or coal combustion system. Introducing an adsorbent containing silica and alumina into the ash, measuring the leachate of mercury and / or other heavy metals from the resulting ash, and adjusting the levels of silica and alumina added according to the measured leachate of heavy metals. including. When the leaching amount is larger than the desired amount, the administration rate of the adsorbent can be increased in order to reduce the leaching amount to a desired range. In a preferred embodiment, the adsorbent further comprises a halogen (eg, bromine) compound to increase the amount of mercury trapped in the ash. Advantageously, the adsorbent containing silica and alumina is added to the powder composition containing _{<1% Na 2} O and <1% K _{2 O to reduce or remove fouling.}

In one embodiment, the present invention provides a method for producing a cement-based ash product while reducing the amount of mercury oxide in a fuel gas generated by combustion of a mercury-containing carbonaceous fuel such as coal. The method comprises burning the fuel in the presence of an alkaline powder adsorbent comprising the powder adsorbent containing calcium, silica and alumina. The alkaline powder is added to the pre-combustion of coal, injected into the in-combustion furnace, administered to the fuel gas downstream of the furnace (preferably at a temperature of 1500 ° F. or higher), or applied in any combination. The powder is an alkali characterized by a pH of about 7, preferably about 8 and preferably about 9, when mixed with water. Advantageously, the adsorbent contains less than 1% by weight of each, less than 0.5% by weight of each, or less than 0.1% by weight of each alkali (eg, Na ₂ O and K ₂ O). In various embodiments, the adsorbent further comprises iron and magnesium. In various embodiments, the alumina content in the adsorbent is greater than the alumina content of Portland cement, preferably greater than about 5%, or greater than about 7%.

During fuel combustion, the concentration of mercury (mercury oxide, elemental mercury, or both) in the downstream fuel gas from the furnace is measured to monitor the release. The measured mercury concentration is compared with the target concentration, and if the measured concentration exceeds the target concentration, the amount of powder adsorbent added is increased relative to the amount of fuel to be burned. Alternatively, if the measured concentration is at or below the target concentration, the rate of addition of the adsorbent can be reduced or maintained unchanged.

In another embodiment, the powder composition is an adsorbent composition comprising an alkaline calcium component and significant amounts of silica and alumina. In a non-leaching embodiment, the powder composition comprises an alkaline powder comprising 2-50% by weight aluminosilicate material and 50-98% by weight calcium. In a preferred embodiment, the alkaline powder comprises one or more lime, calcium oxide, Portland cement, cement kiln dust, lime kiln dust, and sugar beet lime, while the aluminosilicate material comprises calcium montmorillonite, sodium montmorillonite, and. Includes one or more selected from the group consisting of kaolin. In certain embodiments, the powder adsorbent comprises CKD and other materials to meet low alkaline and / or low chlorine specifications.

The powder composition is added to the coal at a rate of about 0.1 to about 10% based on the amount of coal processed with the adsorbent in the batch step or the percentage of coal consumed by combustion in the continuous step. In embodiments, the proportions are 0.1 to 5% by weight, 0.1 to 2% by weight, 0.1 to 1.5% by weight, 0.1 to 1% by weight, 1 to 8% by weight in embodiments. , 2-8% by weight, 4-8% by weight, 4-6% by weight, or about 6% by weight. In certain embodiments, the powder composition is injected into a fireball or furnace during combustion and / or administered to coal under ambient conditions prior to coal combustion. The temperature at the injection site is preferably at least about 1000 ° F or higher. For some low-cost fuels, this corresponds to injection into or near the fireball.

In a further embodiment, a method of reducing mercury and / or sulfur released into the natural environment during coal combustion in a coal combustion system comprises an adsorbent component comprising bromine, calcium, silica and alumina in the coal combustion system. It includes adding and burning coal in the presence of an adsorbent component to generate combustion gas and fly ash. The amount of mercury in the combustion gas is measured, and the concentration of the component containing bromine added to the system is adjusted according to the mercury value measured in the combustion gas.

In various embodiments, the four components (calcium, silica, alumina and bromine), together or separately, for pre-combustion of coal, in a furnace, and / or at suitable temperatures as described herein. Add to combustion gas. The adsorbent containing the component preferably contains up to less than 1% by weight Na ₂ O and up to less than 1% by weight K ₂ O. Preferably bromine is present at a level for efficiently trapping at least 20%, at least 40%, at least 80% or at least 90% mercury in coal in ash, and silica and alumina are 0.2 ppm. It is present at an efficient level to generate fly ash with a leachate value of less than (200 ppb), preferably less than 100 ppb, less than 50 ppb, and even more preferably less than 2 ppb. The concentration of 2 ppb is lower than the current detection limit in the TCLP test for mercury leaching.

In certain embodiments, the method supplies coal ash and / or fly ash containing mercury at a concentration corresponding to the capture of ash originally containing at least 40% or at least 90% mercury in pre-combustion coal. In some embodiments, the mercury concentration is higher than known fly ash due to the capture of mercury in the ash rather than the release of mercury into the atmosphere. The fly ash generated by this method contains 200 ppm or less of mercury or a higher concentration of mercury, and in some embodiments, the mercury content in the fly ash is about 250 ppm. Since the volume of ash is usually increased by the use of an adsorbent (in the usual embodiment, about twice the volume of ash), the increased and measured mercury concentration is released into the natural environment in the absence of the adsorbent. Represents greater capture than mercury-containing ash. The content of mercury and other heavy metals such as lead, chromium, arsenic and cadmium in fly ash is usually higher than in fly ash resulting from burning coal without the addition of adsorbents or adsorbent components.

Preferably, the mercury in coal ash is toxic index leaching method (TCLP), 40CFR260.11. As incorporated by reference in the chapter, "Methods for assessing solid waste, physical / chemical methods" EPA Publishing SW-846-3rd Publishing, when testing using Test Method 1311, it is 0. Shows a mercury concentration of less than 2 ppm. The total mercury content of the ash generated from the adsorbents that process coal is more than two factors higher than the content in the ash produced by combustion without the adsorbent, but the combustion of coal with the adsorbents described herein. It is usually observed that the ash produced by the ash has less leachate mercury than the ash generated from coal combustion without an adsorbent. For example, normal ash from burning PRB coal contains about 100-125 ppm mercury; in various embodiments, it is generated by burning PRB coal with about 6% by weight of the adsorbent described herein. The ash has about 200-250 ppm mercury or more.

In another embodiment, the present invention provides a hydraulic cement product containing 0.1% by weight to 99% by weight of Portland cement based on the total amount of coal ash or the cement products of the ash described above. do. In a further embodiment, the invention provides a pozzolan product comprising 0.01% to 99% by weight of pozzolan, based on the total amount of the ash pozzolan product described above.

In a further embodiment, the invention provides a pozzolan product comprising 0.01% to 99% by weight of pozzolan, based on the total amount of the ash pozzolan product described above.

The present invention also provides a cement mixture containing a hydraulic cement product.

Furthermore, the present invention provides a concrete ready mix product containing an aggregate cement product and a hydraulic cement product.

In another embodiment, the cement mixture comprises the coal ash described herein as the sole cement composition; in these embodiments, the ash can substitute all of the usual cements such as Portland cement. The cement mixture comprises cement and optionally aggregates, fillers and / or other mixtures. Cement mixtures are usually mixed with water and used for concrete, mortar, grout, fluid fillers, stabilizers and other applications.

Therefore, the method of the present invention includes burning coal and an adsorbent to be added in order to generate heat generation or power generation energy. The ash is then recovered and used to form a cement mixture containing cement, mortar and grout.

In a preferred embodiment, the powder adsorbent composition described herein comprises one or more alkaline powders containing calcium, along with one or more lower levels of aluminosilicate material. The halogen component is added as an additional alkaline powder component, as needed, or separately as part of a liquid or powder composition. Advantageously, the use of adsorbents leads to a reduction in the release or emission of sulfur, nitrogen, mercury, other heavy metals (eg lead and arsenic) and / or chlorine from the coal combustion system.

The adsorbent composition used above and in various embodiments of the invention described herein comprises a component that results in calcium, silica and / or alumina, preferably in the form of an alkaline powder. In various embodiments, the composition also comprises iron oxide, in the non-limiting embodiment, the powder composition is greater than about 2 to 10 wt% of _Al 2 _O 3, 40% (e.g., about 40 to 70 % CaO in),> 10 wt% of SiO _2, about 1-5% _Fe 2 _{O 3,} as well as <2%, such as sodium oxide and potassium oxide, preferably a total alkali content of less than 1%. Ingredients containing calcium, silica and alumina and other elements, if any, are mixed together as components in the fuel combustion system in a single composition or added separately or in any combination. In a preferred embodiment, the use of an adsorbent leads to a reduction in the amount of NOx, SOx, and / or mercury released into the atmosphere.

Advantageously, the adsorbent component contains suitable high levels of alumina and silica. The presence of alumina and / or silica leads to some of the advantages found in the use of adsorbents. For example, the presence of alumina and / or silica and / or the balance of calcium, iron and other components with silica / alumina has been observed in ash generated by coal or other fuels containing mercury in the presence of adsorbents. It results in low acidity leaching of mercury and / or other heavy metals.

As described above, the components that provide calcium, silica and / or alumina are preferably supplied as alkaline powders. Without being limited by theory, the alkalinity of the adsorbent component is believed to at least partially lead to the desired properties described above. For example, the alkalinity of the powder is thought to lead to a reduction in sulfur pitting corrosion. It is believed that after neutralization the geopolymer ash is formed in the presence of the adsorbent and combines with the silica and alumina present in the adsorbent to form a matrix-like ceramic reported as a stabilized ash. Stabilized ash is characterized by significantly reducing the leaching of mercury and other heavy metals. In some embodiments, mercury leaching is below the detection limit. However, for some ashes, the high alkalinity in the adsorbent component tends to result in undesired fouling. Therefore, the teachings of the present invention use less alkaline and / or lower chlorine adsorbents (as measured by the content of _{Na 2} O and K ₂ O), especially in the use of subbituminous coal and lignite. Describe how to overcome the shortcomings of this.

Calcium sources for the adsorbent compositions of the present invention include, but are not limited to, calcium powders such as calcium carbonate, limestone, white cloud stone, calcium oxide, calcium hydroxide, calcium phosphate and other calcium salts. Industrial products such as limestone, lime and slaked lime give the majority of such calcium salts. As such, they are suitable components for the adsorbent composition of the present invention.

Other sources of calcium include various industrial products. Such products are commercially available, and some of them are sold as waste or by-products of other industrial methods. In a preferred embodiment, the product imparts silica, alumina, or both to the composition of the invention. Unlimited examples of industrial products containing silica and / or alumina in addition to calcium include Portland cement, cement kiln dust, lime kiln dust, sugar beet lime, slag (eg steel slag, stainless steel slag and blast furnace slag), paper. Includes deinked sludge ash, cupola cementel filtered cake, and cupola furnace dust.

These materials and, if necessary, other materials may be combined to give an alkaline powder or a mixture of alkaline powders containing calcium and preferably also containing silica and alumina. Other alkaline powders containing calcium, silica and alumina include pozzolanic materials, wood ash, rice husk ash, class C fly ash, and class F fly ash. In various embodiments, the materials and similar materials, compositions, in particular obtained, 2-10 wt% of _Al 2 _O 3, 40 wt% more CaO, 10 wt% more SiO _2, about When they are contained as components that fall within the preferred range of 1-5% Fe ₂ O ₃ and less than about 2% by weight of total alkali, they are suitable components of the adsorbent composition. A mixture of materials is also used. Examples include, but are not limited to, a mixture of Portland cement and lime, and a mixture containing cement kiln dust (eg, cement kiln dust and lime kiln dust).

Sugar beet lime is a solid waste material obtained from the production of sugar from sugar beet. It has a high calcium content and contains various impurities that precipitate in the rimming procedures performed on sugar beets. It is a commercial product and is usually sold as a soil conditioner to landscape architects, farmers and the like.

Cement kiln dust (CKD) usually indicates a by-product produced in a cement kiln or associated processing equipment during the production of Portland cement.

CKD typically comprises a combination of different particles produced in different regions of the kiln, pretreatment equipment, and / or material handling system, such as clinker dust, partially fully calcined material dust, and Includes raw material (hydrate and dehydrated) dust. The composition of CKD will vary depending on the raw materials and fuel used, manufacturing and processing conditions, and the location of the CKD collection point in the cement manufacturing process. CKD may include dust or particulate matter collected from kiln effluent (ie, effluent) streams, clinker cooler effluents, pre-fired effluents, air pollution control devices, and the like. Commercially available CKD depends on its source, but has an alkaline range. In some embodiments, the use of low alkaline CKD makes it possible to meet the low alkaline powder adsorbents described herein. If only high alkaline CKD is used, it may be necessary to mix with the low alkaline materials described above or to substitute some of the high alkaline CKD products with the alkaline materials.

Although the CKD composition varies with respect to different kilns, CKD usually has at least some cementum and / or pozzolanic properties due to the presence of clinker and calcining material dust. Typical CKD compositions are silicon-containing compounds such as silicates containing tricalcium silicate, dicalcium silicate; aluminum-containing compounds such as aluminates containing tricalcium aluminate; and iron-containing compounds such as alumino. Ferrite Containing ferrite containing tetracalcium. CKD usually comprises calcium oxide (CaO). An exemplary CKD composition comprises from about 10 to about 60% by weight, optionally from about 25 to about 50% by weight, and optionally from about 30 to about 45% by weight calcium oxide. In some embodiments, CKD is about 1 to about 10% free lime (available for hydration with water), optionally about 1 to about 5%, and in some embodiments. , Contain at a concentration of about 3 to about 5%. Further, in certain embodiments, CKD comprises, in particular, compounds containing alkali metals, alkaline earth metals, and sulfur.

Other exemplary sources of alkaline powders containing calcium, and preferably further containing silica and alumina, include various cement-related by-products (in addition to the Portland cement and CKD described above). include. Mixed cement products are a good example of such sources. These mixed cement products generally include a mixture of Portland cement and / or its clinker in combination with slag and / or pozzolan (eg, fly ash, silica fume, calcined shale). Pozzolan is usually not cementitious in itself, but is a silicon material that exhibits hydraulic cement properties when reacted with free lime (free CaO) and water. Other sources are Masonry cement and / or hydraulic lime, which include Portland cement and / or a mixture of its clinker with lime or limestone. Other suitable sources are alumina cement, which include limestone and bauxite (one or more aluminum hydroxide minerals, and silica, iron oxide, titania, aluminum silicate, and small or small amounts). A water-hard cement produced by burning a mixture of (naturally occurring non-uniform materials) containing various mixtures of the impurities of. Yet another example is pozzolan cement, which is a mixed cement containing a substantial concentration of pozzolan. Normally, pozzolan cement contains calcium oxide, but substantially no Portland cement. Common examples of widely used pozzolans include natural pozzolans (eg, certain volcanic ash or tuff, certain diatomaceous earth, calcined clay and fly ash) and synthetic pozzolans (eg, silica fume and fly ash).

Lime kiln dust (LKD) is a by-product of the production of lime. LKD is a dust or particulate matter collected from a lime kiln or related processing equipment. The lime produced can be classified as high calcium content lime or dolomite lime, and LKD varies depending on the method of forming it. Lime is often produced by a calcining reaction carried out by heating a calcite raw material, such as calcium carbonate (CaCO ₃ ), to form free lime CaO and carbon dioxide (CO _2). Calcium-rich lime has several impurities, including high concentrations of calcium oxide and usually aluminum-containing and iron-containing compounds. Calcium-rich lime is usually formed from high-purity calcium carbonate (purity of about 95% or higher). The typical calcium oxide content in the LKD product obtained from the calcium-rich lime processing is about 75% by weight or more, optionally about 85% by weight or more, and in some cases about 90% by weight or more. In some lime production methods, dolomite (CaCO _3- MgCO ₃ ) is decomposed by heating to mainly produce calcium oxide (CaO) and magnesium oxide (MgO). What is formed by this is known as dolomite lime. In the LKD produced by dolomite lime processing, calcium oxide may be present in an amount of about 45% by weight or more, optionally more than about 50% by weight, and, in certain embodiments, more than about 55% by weight. LKD varies depending on the type of lime method used, but usually has a relatively high concentration of free lime. The typical amount of free lime in LKD is from about 10 to about 50% and optionally from about 20 to about 40%, depending on the relative concentration of calcium oxide present in the lime product produced. ..

Slag is usually a by-product compound produced by metal production and processing. The term "slag" includes a wide variety of by-product compounds and typically comprises the majority of non-metallic by-products in the production and processing of iron and / or steel. Generally, slag is considered to be a mixture of various metal oxides, but they often contain metal sulfides and metal atoms in elemental form.

Various examples of slag by-products useful in certain embodiments of the invention include those produced in iron slag, such as blast furnaces (also known as cupola furnaces), such as air-cooled blast furnace slag (also known as cupola furnaces). ACBFS), expansion or foaming blast furnace slag, pelletized blast furnace slag, granular blast furnace slag (GBFS) and the like. Steel slag can be produced from a basic oxygen steelmaking furnace (BOS / BOF) or an electric arc furnace (EAF). Many slags are recognized to have cementitious and / or pozzolanic properties, but as will be appreciated by those skilled in the art, to the extent that slags have these properties, their respective compositions and It depends on how they are derived. A typical slag comprises a calcium-containing compound, a silicon-containing compound, an aluminum-containing compound, a magnesium-containing compound, an iron-containing compound, a manganese-containing compound and / or a sulfur-containing compound. In certain embodiments, the slag comprises calcium oxide in an amount of about 25 to about 60% by weight, optionally from about 30 to about 50% by weight, and optionally from about 30 to about 45% by weight. An example of a suitable slag that usually has cementitious properties is pulverized granular blast furnace slag (GGBFS).

As mentioned above, other suitable examples include blast furnace (cupola) furnace dust (eg, cupola arrester filter cake) collected from air pollution control devices mounted on the blast furnace. Another suitable source of industrial by-products is paper deink sludge ash. As will be appreciated by those skilled in the art, there are many different manufacturing / industrial process by-products that are suitable as calcium sources for the alkaline powders that form the adsorbent compositions of the present invention. Similarly, many of these well-known by-products include alumina and / or silica. Some, such as lime kiln dust, contain large amounts of CaO and relatively small amounts of silica and alumina. Also, any combination of typical industrial products and / or industrial by-products is also intended for use as alkaline powders in certain embodiments of the present invention.

In various embodiments, the desired treatment level of silica and / or alumina is obtained by adding materials such as Portland cement, cement kiln dust, lime kiln dust, and / or sugar beet lime. Thus, such materials can be supplemented with aluminosilicate materials, such as, but not limited to, clays (eg, montmorillonite, kaolin, etc.), if necessary to provide favorable silica and alumina levels. In various embodiments, the supplemental aluminosilicate material comprises at least about 2% by weight, and preferably at least about 5% by weight, of the various adsorbent components added to the coal combustion system. In general, there is no technical upper limit as long as adequate levels of calcium are maintained. However, from a cost standpoint, it is usually desirable to limit the proportion of more expensive aluminosilicate materials. Thus, the adsorbent component comprises preferably about 2-50% by weight, preferably 2-20% by weight, and more preferably about 2-10% by weight of the aluminosilicate material (eg, typical clay). Become. Non-limiting examples of adsorbents are about 93% by weight CKD and LKD blends (eg, 50:50 blends or mixtures) and about 7% by weight aluminosilicate clays.

In various embodiments, the alkaline powder adsorbent composition comprises one or more calcium-containing powders (eg, Portland cement, cement kiln dust, lime kiln dust, various slags, and sugar beet lime) and aluminosilicate clays (eg, eg). , But not limited to montmorillonite or kaolin). The adsorbent composition is used to form a fire resistant mixture with calcium sulphate produced by burning sulfur-containing coal in the presence of the CaO adsorbent component, preferably such that calcium sulphate is handled by the particle control system; It also contains _{sufficient SiO 2} and Al ₂ O ₃ to form a fire resistant mixture with mercury and other heavy metals so that mercury and other heavy metals do not leach out of the ash under acidic conditions. In a preferred embodiment, the calcium-containing powder adsorbent contains at least 10% by weight silica and at least 2-10% by weight alumina. Preferably, the alumina concentration is higher than that found in Portland cement, which is higher than about 5% by weight, preferably higher than about 6% by weight, based on _{Al 2} O _3.

In various embodiments, the adsorbent component of the alkaline powder adsorbent composition works with optionally added halogen (eg, bromine) compounds or compounds to remove chlorides and mercury, lead, arsenic, and other heavy metals in the ash. It captures, makes heavy metals non-leaching under acidic conditions, and improves the cementic properties of the resulting ash. As a result, the release of harmful elements is mitigated, reduced or eliminated, and valuable cementitious materials are produced as by-products of coal combustion.

Suitable aluminosilicate materials include a wide variety of inorganic minerals and materials. For example, many minerals, natural and synthetic materials can be any other cation (eg, but not limited to Na, K, Be, Mg, Ca, Zr, V, Zn, Fe, Mn) and / or It contains silicon and aluminum associated with the oxy environment, along with any hydrated water, along with other anions (eg hydroxide ions, sulfate ions, chloride ions, carbonate ions). As used herein, such natural and synthetic materials refer to aluminosilicate materials, and an example, but not limited to, is the clays shown above.

In aluminosilicate materials, silicon tends to exist as a tetrahedron, while aluminum exists as a tetrahedron, octahedron, or a combination of both. Chain or reticulated aluminosilicates are assembled in such materials by sharing one, two or three oxygen atoms between silicon and an aluminum tetrahedron or octahedron. Such minerals follow various names such as silica, alumina, aluminosilicates, geopolymers, silicates, and aluminates. However, the presented aluminum and / or silicon-containing compounds tend to produce silica and alumina when exposed to the high temperatures of combustion in the presence of oxygen.

In one embodiment, the aluminosilicate material comprises a polymorphic SiO _2- Al ₂ O ₃ . For example, the silicate contains a silica octahedron and alumina that is finally split between the tetrahedron and the octahedron. Kyanite is based on silica tetrahedrons and alumina octahedrons. Andalusite is another polymorph, SiO ₂ , Al ₂ O ₃ .

In another embodiment, the silicate chain imparts silicon (as silica) and / or aluminum (as alumina) to the composition of the invention. Kay Sanshiokusari include, but are not limited to, the pyroxene and semi pyroxene silicate composed of infinite chains of SiO ₄ tetrahedra linked by sharing the oxygen atoms.

Other suitable aluminosilicate materials include sheet materials such as, but not limited to, mica, clay, chrysotile (eg asbestos), talc, soapstone, pyrophyllite, and kaolinite. Such materials are characterized by having a layered structure in which silica and alumina octahedrons and tetrahedra share two oxygen atoms. Layered aluminosilicates include clays such as chlorite, glauconite, illite, parigolskite, pyrophyllite, soconite, vermiculite, kaolilite, calcium montmorillonite, sodium montmorillonite, and bentonite. Other examples include mica and talc.

Suitable aluminosilicate materials include synthetic and natural zeolites such as, but not limited to, analcime, sodalite, chabazite, sodalite, phillipsite, and mordenite groups. Other zeolite minerals include heulandite, brewer boiled stone, exfoliated boiled stone, stilbite, yagawaralite, muddy boiled stone, bittersweet boiled stone, polling boiled stone, and clinoptilolite. The zeolite is a mineral or synthetic material characterized by an aluminosilicate tetrahedral skeleton, ion exchange "giant cations" (eg Na, K, Ca, Ba, and Sr) and loosely retained water molecules.

In other embodiments, skeletons or 3D silicates, aluminates, and aluminosilicates are used. The skeletal aluminosilicate is _{characterized by a structure in which SiO 4} tetrahedron, AlO ₄ tetrahedron, and / or AlO ₆ octahedron are three-dimensionally bonded. Non-limiting examples of skeletal silicates containing both silica and alumina include plagioclase, such as albite, anorthite, neutral plagioclase, subash anorthite, albite, microcline, sanidine and orthoclase. Be done.

In one embodiment, the adsorbent powder compositions are such that they contain a large amount of calcium, preferably more than 20% by weight or more than 40% by weight of calcium based on calcium oxide, and further, they are commercially available. It is characterized by containing higher levels of silica and / or alumina than those found in (eg, Portland cement). In a preferred embodiment, the adsorbent composition comprises more than 5% by weight of alumina, preferably more than 6% by weight of alumina, preferably more than 7% by weight of alumina, and preferably more than about 8% by weight of alumina. Contains.

Coal or other fuels are treated with an adsorbent component in a ratio effective in controlling the amount of nitrogen, sulfur and / or mercury released into the atmosphere upon combustion. In various embodiments, the total treatment level of the adsorbent component is based on the weight of coal treated or the proportion of coal consumed by combustion when the adsorbent is a powder adsorbent containing calcium, silica and alumina. It is in the range of about 0.1% by weight to about 20% by weight. When the adsorbent components are combined into a single composition, the component treatment level corresponds to the adsorbent treatment level. Thus a single adsorbent composition can be provided and weighed, or otherwise measured, with respect to the addition to the coal combustion system. In general, it is desirable to use the lowest amount of adsorbent so that the system is not overloaded by excess ash, while providing the desired effect on sulfur and / or mercury release. Thus, in various embodiments, the treatment level of the adsorbent ranges from about 0.1% to about 10% by weight, and in some embodiments from about 1 or 2% to about 10% by weight. For many coals, a 6 wt% powder adsorbent addition rate was found to be acceptable.

The adsorbent composition comprising a halogen compound contains one or more organic or inorganic compounds containing a halogen. Halogen includes chlorine, bromine, and iodine. Preferred halogens are bromine and iodine. Halogen compounds are halogen (particularly bromine and iodine) sources. Halogen sources for bromine include various inorganic salts of bromine, including bromide, bromate and hypobromite. In various embodiments, organobromine compounds are less preferred due to their cost or availability. However, bromine organic sources that adequately contain high levels of bromine are considered to be within the scope of the present invention. Non-limiting examples of organic bromine compounds include methylene bromide, ethyl bromide, bromoform, and carbon tetrabromide. Examples of the iodine inorganic source include, but are not limited to, hypoiodous acid salt, iodate, and iodide, and iodide is preferable. Organoiodine compounds can also be used.

When the halogen compound is an inorganic substituent, it is preferably a salt of a bromine or iodine-containing alkaline earth element. Typical alkaline earth elements include beryllium, magnesium, and calcium. Among the halogen compounds, bromides and iodides of alkaline earth metals (for example, calcium) are particularly preferable. Alkali metal bromine and iodine compounds such as bromide and iodide are effective in reducing mercury release. However, in some embodiments, they are less preferred as they tend to cause corrosion of the boiler tubing and other steel surfaces and / or contribute to tubing degradation and / or refractory brick degradation. In various embodiments, it has been found desirable to avoid halogen potassium salts in order to avoid furnace problems.

In various embodiments, the use of alkaline earth salts (eg calcium) has been found to tend to avoid such problems with sodium and / or potassium. Thus, in various embodiments, the adsorbent added to the coal combustion system is essentially free of alkali metal-containing bromine or iodine compounds, or more specifically sodium- or potassium-containing bromine or iodine compounds. Not contained in.

In various embodiments, halogen-containing adsorbent compositions are provided in the form of liquid or solid compositions. In various embodiments, the halogen-containing composition is administered to the coal prior to combustion, added to the furnace during combustion, and / or administered into the fuel gas downstream of the furnace. When the halogen composition is solid, it can further contain the calcium, silica and alumina components described herein as powder adsorbents. Alternatively, the solid halogen composition is administered onto coal and / or, in other cases, separately into the combustion system from the adsorbent component comprising calcium, silica and alumina. If the composition is a liquid composition, it is usually administered separately.

In various embodiments, the liquid mercury adsorbent comprises a solution containing 5-60% by weight of a bromine or iodine-containing soluble salt. Non-limiting examples of preferred bromine and iodine salts include calcium bromide and calcium iodide. In various embodiments, the liquid adsorbent contains 5-60% by weight calcium bromide and / or calcium iodide. For the efficiency of coal addition before combustion, it is preferable to add a mercury adsorbent with as high a level of bromine or iodine compound as possible in various embodiments. In an embodiment that is not limited, the liquid adsorbent contains 50% by weight or more of a halogen compound, such as calcium bromide or calcium iodide.

In various embodiments, the adsorbent composition containing the halogen compound further comprises a nitrate compound, a nitrite compound, or a combination of the nitrate compound and the nitrite compound. Preferred nitrate and nitrite compounds include those of magnesium and calcium, preferably calcium.

As a further example, one embodiment of the present invention comprises adding a liquid mercury adsorbent directly to raw or ground coal prior to combustion. For example, a mercury adsorbent is added to the coal in the coal feeder. The addition of the liquid mercury adsorbent is in the range of 0.01-5%. In various embodiments, the treatment is less than 5%, less than 4%, less than 3%, or less than 2%, less than 1%, less than 0.5% and less than 0.2%, where all% are Based on the amount of coal processed or the rate of coal consumption by combustion. Higher processing levels are possible, but tend to waste material and no further benefits are achieved. A preferred treatment level is 0.025 to 2.5% by weight on a wet basis. The amount of solid bromide or iodide salt added by the liquid adsorbent is, of course, reduced by its weight fraction in the adsorbent. In a typical embodiment, the addition of bromide or iodide compound is 0.01% to 1% by weight based on low levels, eg solids. Therefore, when using a 50% by weight solution, the adsorbent is added in a ratio of 0.02% to 2% in order to achieve low levels of addition. For example, in a preferred embodiment, coal is in a proportion of 0.02-1% by weight, preferably 0.02-0.5% by weight, calculated assuming that calcium bromide is an adsorbent of about 50% by weight. Treat with a liquid adsorbent. In a typical embodiment, a liquid adsorbent containing 50% calcium bromide is applied at about 1%, 0.5%, or 0.25% (where% is based on the weight of coal) before combustion. Add on coal. In a preferred embodiment, the initial treatment is started at a low level (eg 0.01% to 0.1%) and gradually until the desired (low) level of mercury release is achieved based on emission monitoring. To increase. When halogen is added as a solid or as a multi-component composition with other components (eg calcium, silica, alumina, iron oxide, etc.), similar treatment levels of halogen are used.

When used, the liquid adsorbent is sprayed, dropped, or otherwise supplied onto the coal or otherwise into the coal combustion system. In various embodiments, the addition is made to coal or other fuel under ambient conditions prior to charging the fuel / adsorbent composition into the furnace. For example, the adsorbent is added onto the powdered coal prior to its injection into the furnace. Alternatively or additionally, a liquid adsorbent is added into the furnace during combustion and / or into the fuel gas downstream of the furnace. The addition of halogens containing the mercury adsorbent composition is often accompanied by a measured reduction in mercury levels in the fuel gas for one or several minutes. In various embodiments, the reduction of mercury occurs in addition to the reduction achieved by the use of alkaline powder adsorbents based on calcium, silica and alumina.

In another embodiment, the invention comprises adding a halogen component (eg, a calcium bromide solution) directly into the furnace during combustion. In another embodiment, the invention is described above, into a gas stream downstream of the furnace in a region characterized by temperatures in the range of 2700 ° F to 1500 ° F, preferably 2200 ° F to 1500 ° F. Provided is the addition of a calcium bromide solution as discussed. In various embodiments, the treatment level of the bromine compound (eg, calcium bromide) is divided into arbitrary proportions of addition between co-firing, pre-combustion and post-combustion.

In one embodiment, in order to produce so-called refined coal, various adsorbent components are added onto the coal prior to its combustion. The coal to which the adsorbent is administered is preferably granular coal and, if necessary, pulverized or pulverized according to conventional procedures. In a non-limiting example, coal is ground so that 75% by weight particles pass through a 200 mesh screen, which has a pore size of 75 μm. In various embodiments, the adsorbent component is added onto the coal as a solid or as a combination of liquid and solid. Usually, the solid adsorbent composition is in powder form. When the adsorbent is added as a liquid (eg, one or more bromine or iodine salt solutions in water), in one embodiment the coal remains moist when fed into the burner. In various embodiments, the adsorbent composition is continuously added onto the coal by spraying or mixing onto the coal on a conveyor, screw extrusion, or other supply device at a coal combustion facility. In addition or / or the adsorbent composition is mixed separately with the coal at the coal combustion facility or at the coal producing area. In a preferred embodiment, the adsorbent composition is added to the coal as a liquid or powder when fed into the burner. For example, in a preferred commercial embodiment, the adsorbent is administered into a crusher that grinds the coal prior to injection. If desired, the rate of addition of the adsorbent composition is varied to achieve the desired mercury release level. In one embodiment, the mercury level in the flue gas is monitored and adjusted to increase or decrease the adsorbent addition level as required to maintain the desired mercury level.

In a preferred embodiment, nitrogen, mercury and sulfur are monitored using industrial standard methods, such as those published by the American Society for Testing and Materials (ASTM) or international standards published by the International Organization for Standardization (ISO). .. The device, including the analytical instrument, is preferably located in the convection path downstream of the mercury and sulfur adsorbent addition points. In a preferred embodiment, the mercury monitoring device is placed on the clean side of the particle control system. Alternatively or additionally, the fuel gas is sampled at the appropriate location in the convection flow path, without the installation of equipment or monitoring devices. In various embodiments, pumps, solenoids, atomizers, and others that are operated or controlled to adjust the rate of addition of the adsorbent composition into the coal combustion system using the measured levels of mercury or sulfur. Gives a feedback signal to the device. Alternatively or additionally, the adsorbent addition rate can be adjusted by a human operator based on the observed levels of mercury and / or sulfur.

In various embodiments, the ash produced by burning coal in the presence of the adsorbents described herein is a cementum that, when combined with water, hardens and exhibits strength. Ash tends to self-harden due to its relatively high calcium levels. Ash, alone or in combination with Portland cement, is useful as a hydraulic cement suitable for formulation into various cementitious mixtures (eg, mortar, concrete, and grout).

The cementitious properties of the produced ash described herein are shown, taking into account, for example, the strength activity index of ash or, more precisely, the cementum mixture containing ash. As described in ASTM C311-05, the measurement of strength activity index shows the hardening behavior and characteristic development of 100% Portland cement concrete and test concrete in which 20% Portland cement is replaced with an equivalent amount of test cement. Made by comparison. In a standard test, the intensities are compared at 7 and 28 days. If the strength of the test concrete is 75% or more of the strength of Portland cement concrete, it is considered "passed". In various embodiments, the ash of the present invention exhibits 100% to 150% intensity activity in the ASTM test, which strongly indicates a "pass". Similar high values are observed when the test is performed with a test mixture that has a non-80:20 blend of Portland cement and ash. In various embodiments, a strength activity index of 100% to 150% is achieved with a blend of 85: 15-50: 50, where the first number of ratios is Portland cement and the second of the ratios. The value of is the ash produced according to the present invention. In certain embodiments, the strength development of the all-ash test cementitious mixture (ie, where the ash represents 100% of the cement in the test mixture) exceeds 50% of the control strength of all Portland cement, and is preferred. Is more than 75%, and more preferably 100% or more, for example 100-150%. Such results indicate the high cementitious properties of the ash produced by burning coal or other fuels in the presence of the adsorbent components described herein.

The ash obtained from the combustion of coal according to the present invention contains non-leaching form of mercury and can be put on the market. Unrestricted use of used or waste fly ash or bottom ash includes its use as an ingredient in cement products (eg Portland cement). In various embodiments, the cement product contains coal ash produced by burning the compositions of the invention from about 0.1% to about 99% by weight. In one aspect, the non-leaching properties of mercury and other heavy metals in coal ash make coal ash suitable for all known coal ash industrial applications.

The coal ash according to the present invention, especially the fly ash collected by a particle control system (bug house, electrostatic precipitator, etc.), is used in Portland cement concrete (PCC) as a partial or complete replacement of Portland cement. In various embodiments, the ash is used as a mineral mixture or as a component of a mixed cement. As a mixture, the ash can be a total or partial substitution of Portland cement and can be added directly into readymix concrete in a batch plant. Alternatively, or in addition, the ash is embedded in cement clinker or blended with Portland cement to produce mixed cement.

Class F and Class C fly ash are defined, for example, in the US standard ASTM C 618. The ASTM standard serves as a specification for fly ash when it is used as a partial replacement for Portland cement. Coal ash produced by the methods described herein tends to have a higher calcium content and lower silica and alumina content than those described in the ASTM C 618 Class F and Class C fly ash specifications. It should be noted that there is. Typical values for fly ash of the present invention are> 50% by weight CaO and <25% by weight SiO ₂ / Al ₂ O ₃ / Fe ₂ O ₃ . In various embodiments, the ash is the sum of 51-80% by weight CaO and about 2-2 to about 25% silica, alumina and iron oxide. It has been observed that fly ash according to the present invention is highly cementitious and makes it possible to replace or reduce Portland cement used in such cementitious materials and cementum materials by 50% or more. There is. In various applications, the coal ash obtained from burning coal with the adsorbents described herein is sufficient to be a complete (100%) substitution of Portland cement in such compositions. It is cementum.

As a further example, the American Concrete Institute (ACI) recommends that Class F fly ash replace 15-25% Portland cement and Class C fly ash replace 20-35% Portland cement. There is. Coal ash produced according to the methods described herein replaces up to 50% Portland cement while maintaining 28-day strength expression equivalent to that expressed in products using 100% Portland cement. It turned out to be sufficiently cementum. That is, in various embodiments, the ash is not eligible due to its chemical composition as Class C or Class F ash according to ASTM C 618, but nevertheless it is useful for formulation into high strength concrete products. be.

Coal ash produced in accordance with the present invention can also be used as a component in the production of fluid fills, which are also referred to as controlled low-strength materials or CLSM. CLSM is used as a self-smoothing self-compressing backfill material in place of compressed embankments or other fills. The ash described herein is used in various embodiments as a 100% substitution of Portland cement in such CLSM materials. Such compositions are formulated with water, cement, and agglomerates to provide the desired fluidity and ultimate strength development. For example, the ultimate strength of the fluid fill should not exceed 1035 kPa (150 lbs / square inch) if the removability of the cured material is required. A jack hammer may be required for removal when prescribed to achieve higher ultimate strength. However, if it is desirable to formulate a fluid fill mixture for use in higher load bearing applications, it is possible to design a mixture containing a higher range of compressive strength upon curing.

Also, coal ash produced according to the methods described herein is useful as a component of stabilized base and sub base mixtures. Since the 1950s, numerous variants of basic lime / fly ash / aggregate formulations have been used as stabilizing base mixtures. Stabilization-based use cases are those used as stabilized road infrastructure. For example, the gravel road can be reused instead of using the ash from the composition. The existing road surface is crushed and placed in its original position. For example, the ash produced by the methods described herein is spread and mixed into the ground road material. After compression, the seal coat surface is placed on the road. The ash according to the present invention is useful for such applications. This is because ash does not contain heavy metals that leach out beyond regulatory requirements. Rather, the ash produced by the methods of the invention is less leachate mercury and less leachate other heavy metals than coal ash produced by burning coal without the adsorbents described herein. Contains (eg, arsenic and lead).

Accordingly, the present invention provides various methods that eliminate the need to reclaim coal ash or fly ash resulting from the combustion of coal containing high levels of mercury. Instead of costly disposal, the material can be sold or otherwise used as a raw material.

In a preferred embodiment, the use of an adsorbent results in cementum ash that can replace Portland cement in whole or in part in various applications. Reuse of cementum products avoids the production of at least some Portland cement, saves the energy required to produce cement, and releases significant amounts of carbon dioxide from cement production. can avoid. Other savings in carbon dioxide emissions come from reducing the need for lime or calcium carbonate in desulfurized scrubbers. Accordingly, the present invention provides, in various embodiments, methods of saving energy and reducing emissions of greenhouse gases (eg, carbon dioxide). Further details of various embodiments of this aspect of the invention are described below.

Example 1
The required specifications of powder adsorbents and halogen-based adsorbents for the use of refined coal products using subbituminous coal are shown below.

１．ハード限界７％のＳＯ_３に加えて、ＣａＯとＳＯ_３の割合は６：１以下に低下させず、好ましくは８：１よりも大きく維持すべきである。これにより添加する硫黄を吸収するために十分なＣａＯを確保する。
２．実際に、粉末吸着剤のＨｇ含量は処理される石炭含量と同じ又はより少なく維持すべきである。
酸化分析の許容試験方法は以下である：
ASTM D3682 石炭利用工程からの燃焼残留物中での多量及び微量元素に関す
る標準試験方法
ASTM C114 水硬性セメントの化学的分析に関する標準試験方法
水銀含量に関する許容試験方法
ASTM D6414 酸抽出又は湿式酸化／冷蒸気原子吸光による石炭及び石炭燃焼
残留物中の水銀総量に関する標準試験方法
ASTM D6722 直接燃焼分析による石炭及び石炭燃焼残留物中の総水銀に関す
る標準試験方法
EPA 7473 固体又は半固体廃棄物中の水銀（冷蒸気技術の手引き）

1. 1. _{In addition to SO 3} with a hard limit of 7%, the ratio of CaO to SO ₃ should not be reduced below 6: 1 and preferably maintained above 8: 1. This ensures sufficient CaO to absorb the added sulfur.
2. In fact, the Hg content of the powder adsorbent should be kept equal to or less than the coal content being processed.
The acceptable test method for oxidation analysis is:
ASTM D3682 Concerning large and trace elements in combustion residues from coal utilization processes
Standard test method
ASTM C114 Standard Test Method for Chemical Analysis of Hydraulic Cement
Tolerance test method for mercury content
ASTM D6414 Coal and coal combustion by acid extraction or wet oxidation / cold vapor atomic absorption
Standard test method for total mercury in residue
ASTM D6722 on total mercury in coal and coal combustion residues from direct combustion analysis
Standard test method
EPA 7473 Mercury in solid or semi-solid waste (Cold Steam Technology Guide)

Example 2
A series of tests were conducted at the Energy and Environmental Research Center (EERC) Combustion Test Facility (CTF) to measure the effect of adsorbents on NOx and Hg emissions during the combustion of powder river basin (PRB) subbituminous coal. I was broken. The test was conducted to support an attempt to confirm that the method of use was to produce "refined coal" as defined in Article 45 of the Internal Revenue Code. Article 45 (c) (7) (A) defines refined coal containing fuel, which is rational to 1) solid fuel produced from coal and 2) to use it for steam production purposes. Sold by a predictive taxpayer, and 3) (if used for steam production) "certified for emission reduction", the taxpayer is qualified.
In Article 45 (c) (7) (B), the term "certification of emission reduction" is the NOx released when burning refined coal compared to the amount released when burning the supplied coal raw material. It is defined to mean a reduction of at least 20% of release and at _{least 40% of either SO 2 release or Hg release.}

<Description of equipment and procedures>
CTFs are used to broadly investigate the transfer of toxic trace metals (Hg, As and Pb) during SOx and NOx emissions and combustion of coal and other fuels or waste materials. CTFs are capable of producing gas and particle samples that are typical of samples produced in industrial and full-scale pulverized coal (pc) combustion boilers. The test facility includes an electrostatic precipitator (ESP) or a fibrous filter baghouse for particle control, a selective catalytic reduction (SCR) column for NOx control, and a wet scrubber for controlling sulfur emissions. It has several pollution control devices that can be used to reduce it. The CTF was designed to reproduce almost every type and shape of a full-scale US PC combustion boiler used by US GAAP facilities to generate electricity from steam. For example, the CTF can burn pc at a rate of Btu / hr of 550,000-750,000, depending on the desired operating conditions. The CTF is adjusted for simulated experiments under the conditions of a full-scale pc combustion boiler, but since there are many changes that can affect the combustion effect in a commercially available boiler, it is observed in normal actual operation. Cannot be reproduced accurately. Combustion rate typically has indicators of coalification with low coalification burned at the lowest level of the range and high coalification degree burned at the middle or maximum level of the indicated range. The CTF furnace is lined with refractory and the combustion rate is set based on the combustion chamber outlet temperature (FEGT) desired to reproduce the particular boiler used in the coal combustion power plant. For subbituminous coals, generally at a combustion rate of 550,000 to 600,000 BTU / hr, a FEGT of 2100 ° F to 2200 ° F is produced, which is the combustion of many coals that burn subbituminous coals such as the coal tested in the present invention. It is typical in a plant.

Combustion air of CTF is supplied by a forced ventilator in this balanced ventilation system. The ventilator installed at the rear of the system maintains a slight vacuum in the combustion region and discharges the combustion fuel gas to the exhaust stack. Combustion air is typically preheated using an electric heater and split into primary air, secondary air, and overfire air (OFA).

Combustion gas analysis can be performed in two positions; the furnace outlet used to monitor and maintain certain excess air levels throughout the test, and the emissions detected later in the system can correct the dilution caused by the leak. As such, it is provided by a continuous discharge monitor (CEM) at the outlet of the particle control device used to access any possible air leaks. For this series of tests, combustion gas analysis was obtained from the ESP outlet conduit. Each CEM rack contains 5 modules for _{O 2} , CO ₂ , CO, SO _{2 and NOx measurements.} With the _{exception of SO 2} , each module was made by Ametek. Each analyzer uses a combustion gas regulator to remove water from the gas stream prior to analysis. All data reported herein are dry gas standards. All gas analyzes are continuously monitored and recorded by the CTF data acquisition system. The National Instrument has provided both hardware and software (LabView) used to collect all the data present herein.

In CEM analysis, each test performed in CTF is pre-calibrated individually. Nitrogen is used as the zero gas, but some span gas is used to calibrate each device over the range used during the test. Generally, O ₂ is measured in the range of 0% to 10%, CO ₂ is measured in the range of 0% to 20%, CO is measured in the range of 0 to 500 ppm, and NOx is measured in the range of 0 to 1000 ppm. taking measurement. SO ₂ measurements are made in various ranges depending on the sulfur content of the coal being tested. During this series of tests, the SO ₂ measuring device was calibrated in the range 0-1000 ppm, which is appropriate for the sulfur content in the PRB subbituminous coal tested herein.

Fuel gas mercury (Hg) measurements were obtained separately on a continuous Hg monitor (CMM) manufactured by Tekran® Instruments Corporation. The system draws a gas sample from the fuel gas conduit at the outlet of the particle controller. Moisture is removed from the gas stream prior to analysis. The fuel gas that regulates the system state uses a 10% NaOH solution to remove _{CO 2} and SO ₂ in order to accurately measure the Hg concentration of the fuel gas and to prevent adverse effects due to the performance of the analyzer. do. Since all mercury analyzers ^{can only measure elemental mercury (Hg 0} ), the overall mercury (Hg _(T) ^{) concentration is Hg 2+ of} mercury oxide with a 10% NaOH solution containing tin (II) chloride. Obtained by reducing the portion. The Tekran device collects ^{Hg 0} from an inspected sample on a cartridge containing an ultra-purity gold adsorbent. The merged Hg is then thermally desorbed and inspected using atomic fluorescence spectroscopy. The dual cartridge design then allows for additional sampling and displacement resulting from continuous measurement of the sample stream. Similar to the CEM scale correction described above, the CMM is also set to zero prior to the test, spanned and checked at the end of the test. No drift was observed during the tests performed and reported herein. The CTF configurations utilized during these tests included only ESP for particle control, along with both Hg and NOx measurements obtained from the ESP outlet conduit. At the end of the feedstock and refined coal test period, fuel and fly ash samples were collected and submitted for analysis. The samples collected during the test will be described in the discussion below.

<Fuel preparation and analysis>
The test subbituminous coal was a sample obtained from a coal pile. The coal is a PRB subbituminous coal with a total calorific value in the range of about 8500 to 10,000 Btu / Ib, depending on the water content, which is taken from several mines in Wyoming.

The allowable coal was received as needed, and the surface moisture was examined after floor drying. Air-dried samples were crushed to a maximum size of 1/4 inch and fed to a hammermill crusher to create a particle size distribution of approximately 70% passing through 200 mesh for use during testing (many coal combustion power plants). Typical coal processing achieved in). This particle size distribution, at best, is typical of the particle size distribution achieved by pulverization of full-scale commercial boilers. The refined coal sample used during this series of tests is made by EERC and is considered to be comparable to the refined coal produced at the facilities in 45 areas. The adsorbent used to prepare the refined coal was administered to the milled fuel as shown below. This is different from the full-scale application in which the adsorbent is recovered from the storage at the coal yard, mixed, crushed and then sent to a pulverizer. The main reason for administering the adsorbent to the pc used in the pilot scale test is the potential loss of material in the dust collecting duct device used during the milling of the fuel sample. All pilot-scale fuel samples are crushed and pulverized in any amount before use. By preparing the refined fuel from the pc sample, the potential loss of adsorbent in the dust collection system is avoided, and as a result it is the best simulated experiment to occur on a full scale.

The milled fuel was divided into two parts; a feedstock sample and a second coal sample processed into refined coal. Refined coal was prepared by arranging each measured amount (about 500 lb) on the floor of the coal preparation facility. The weighed halogen-based adsorbent and powder adsorbent were carefully administered to the coal, and the coal was mixed periodically while the adsorbent was being administered. The powder adsorbent was hand-distributed and over the amount of coal pile, after each route, several routes were created to mix the fuel. A halogen-based adsorbent was placed in a slightly compressed metal spray can so that the spray tube mouth produced mist applied to the exposed surface of the pile. Treatment was required in several routes to completely distribute the adsorbent. After each path, a rake is used to replace the pile, exposing a new surface for the next processing path. In each case, a small amount of adsorbent was dispensed onto the coal pile and mixed until a particular treatment ratio reached 0.008 wt% halogen adsorbent and 0.25 wt% powder adsorbent. ..

Each sample (coal feedstock and refined coal) was transported to the storage hopper used in the pilot scale test described below. During the test, these storage hoppers are placed directly on the coal supply hopper. A rotary valve is used to move coal and refined coal from the storage hopper to the supply hopper, respectively. After each test, the storage hopper and supply hopper are washed with a diluent acid solution to remove trace amounts of treated fuel.

<Fuel analysis>
During each test period, coal samples are transported from the storage hopper through a canal that penetrates the side wall of the supply device at a 70% angle, with an opening located just below the rotary valve between the storage hopper and the supply hopper. This roubaix catches a small amount of fuel along the way each time the supply hopper is filled. This method provides an accurate combustion sample of the fuel. Due to the weight of the coal sample, it falls into a sample bag attached to the end of the sample tube. A new bag is attached to the sample tube prior to the next test period, separately from the feedstock and the fuel sample representing the refined coal test period.

Combustion coal is continuously sampled and the emission baseline from the combustion of the coal feedstock and similarly the emission from the combustion of refined coal is measured. Coal feedstock and refined coal were provided separately for approximate and elemental analysis, calorific value, inorganic element oxide analysis (by X-ray fluorescence), and measurement of chlorine and mercury content. The results of this analysis are shown in Table 1. The fuel sample has undergone several processing steps that tend to allow evaporation of a small amount of allowable water content. The maximum reduction occurs during fuel milling. Hammer mill pulverizers generate attracted ventilation that tends to slightly dry the exposed surfaces of the pulverized coal particles resulting from the pulverization. The resulting dryness is primarily the effect of ambient atmospheric conditions (temperature and relative humidity) during fuel preparation. As a result, the combustion composition is analyzed for easy comparison between coal feedstock and refined coal.

The coal feedstock (test AF-CTS-461) was measured with a water content of 20.03 wt% and a calorific value of 9621 Btu / lb. Moisture-free calorific value and ash content were measured at 12,031 Btu / lb and 4.91% by weight, respectively. The sulfur content of the coal feedstock was measured on an anhydrous basis by 0.37 wt% (0.624 lbSO _{2 / MMBtu).} The powder adsorbent and the liquid halogen-based adsorbent have no calorific value, and the liquid halogen-based adsorbent introduces additional water into the refined coal due to the water content of the liquid. Therefore, the reduction of the calorific value (Btu / lb) of the refined coal is usually expected by comparing with the Btu / lb of the coal supply raw material. Ash analysis of the inorganic material contained in the fuel, indicate to the coal feedstock, purified coal rich in CaO, and SO _3, that deplete the SiO _2, A _{2 O 3,} and _Fe 2 _{O 3} .. Mercury content was measured at 0.0570 μg / g (5.924 lcb / TBtu, anhydrous base) and 0.0556 μg / g (5.908 lcb / TBtu, anhydrous base), respectively, in the feedstock and refined charcoal samples. The chlorine contents of the feedstock and refined coal samples were measured at 19.4 and 30.0 μg / g, respectively.

A dry sieve analysis of feedstock and refined coal samples collected during each test is shown in the Table of Example 2. Results for coal feedstock show that 84.3% by weight passes through 200 mesh and 69.2% by weight passes through 325 mesh, while for refined coal samples 87.1% by weight passes through 200 mesh, 73. 1% by weight passes through the 325 mesh.

Example 2
The coal supply raw material is PRB coal. The refined coal is obtained by adding 0.008% by weight of a halogen-based adsorbent and 0.25% of a powder adsorbent to the PRB coal supply raw material. The powder adsorbent is 15% CKD and 85% pulverized cement kiln clinker. The halogen-based adsorbent is derived from Example 1. NOx and Hg emissions were measured for feedstock and refined coal.

^＊適用不可

^* Not applicable

The mercury concentration was 0.558 μg / g in the ash of the coal feedstock and 0.833 μg / g in the ash of the refined coal.

Example 3-Subbituminous coal in central America The raw material for supplying coal is PRB coal. The refined coal is obtained by adding 0.005% by weight of a halogen-based adsorbent and 0.25% of a powder adsorbent to the PRB coal feedstock. The powder adsorbent is 15% CKD and 85% ground cement kiln clinker. The halogen-based adsorbent is derived from Example 1. NOx and Hg emissions were measured for feedstock and refined coal.

The morning was used to establish a combustion emission baseline for coal feedstocks burned at an average rate of 60.28 lb / hr to reach a FEGT of about 2139 ° F. Simulate NOx control at the furnace outlet Along with OFA utilized at 15.13%, excess oxygen was controlled to 3.05% at the furnace outlet (approximately 16.98% excess air).

Refined coal is burned at a rate of 58.91 lb / hr, with OFA maintained at 15.18%, FEGT at 2139 ° Fat at the furnace outlet, excess oxygen 3.1% (excess air about 17.33%). Achieved. The obtained emission reductions are shown in the table below.

* 適用不可

* Not applicable

Claims (27)

A method of burning coal in a furnace to reduce the release of NOx and at least one SOx and mercury, comprising burning refined coal in a furnace, wherein the refined coal is subbitum or brown coal, bromine. comprise compounds and mixtures of powder sorbent, the powder sorbent is calcium oxide, silica, alumina, and ground cement kiln clinker kiln feed, will transform the cement, and include one or more dry clinker over, Further, based on the weight of the powder adsorbent _{, it contained less than 1% by weight of Na 2} O and less than 1% by weight of K ₂ O, compared to coal combustion without the bromine compound and the powder adsorbent. A method of reducing mercury emissions from a coal combustion facility by 40% or more, and reducing NOx emissions from a coal combustion facility by 20% or more as compared to coal combustion without the bromine compound and the powder adsorbent. The method of claim 1, wherein the powder adsorbent comprises less than 0.5% Na ₂ O and less than 0.5% K _{2 O.} The method of claim 1, wherein the coal is powder river basin coal. The method according to claim 1, wherein the refined coal contains 0.001 to 1.0% by weight of a bromine compound and 0.1 to 10% by weight of a powder adsorbent. The method according to claim 4, wherein the refined coal contains 0.002 to 1.0% by weight of a bromine compound and 0.1 to 2.0% by weight of a powder adsorbent. The method of claim 1, wherein the powder adsorbent comprises cement kiln dust (CKD). The powder adsorbent contains more than 40% CaO, more than 10% SiO ₂ , 2-10% Al ₂ O ₃ , 1-5% Fe ₂ O ₃ , and 1-5% MgO. The method according to claim 1, wherein the ratio is a weight based on the weight of the powder adsorbent. The method of claim 1, wherein the powder adsorbent comprises CKD and a ground cement kiln clinker. The method of claim 1, wherein the powder adsorbent comprises CKD and an aluminosilicate clay. The method of claim 1, wherein the powder adsorbent comprises CKD and kaolin. The method according to claim 1, wherein the powder adsorbent contains less than 0.5% chlorine. It is a method of generating energy by burning subbituminous coal containing mercury in the furnace of a coal combustion facility;
Administering the first adsorbent composition to coal;
Transporting the administered coal containing the first adsorbent to the furnace;
At the same time as transporting the coal, adding a second adsorbent to the furnace; and burning the coal in the furnace in the presence of the first and second adsorbents to generate thermal energy and ash. And
Wherein said first adsorbent comprises a bromine compound, the second adsorbent calcium oxide, silica, alumina, and ground cement kiln clinker kiln feed, conversion cement, and one or more dry clinker over It contains less than 1% by weight of Na ₂ O and less than 1% by weight of K ₂ O based on the weight of the second adsorbent, and uses the first and second adsorbents. Compared with non-coal combustion, mercury emission from coal combustion facility is reduced by 40% or more, and NOx emission from coal combustion facility is reduced as compared with coal combustion without the first adsorbent and the second adsorbent. The method for reducing by 20% or more. The method of claim 12, wherein the second adsorbent comprises less than 0.5% Na ₂ O and less than 0.5% K _{2 O.} The method according to claim 12, wherein the first adsorbent is an aqueous solution of calcium bromide. The method according to claim 12, wherein calcium bromide is added at a ratio of 0.001 to 0.5% based on the amount of coal to be burned. The method of claim 12, wherein the coal is powder river basin (PRB) coal. The method of claim 12, wherein the second adsorbent comprises CKD. The method according to claim 12, wherein the second adsorbent is added at a ratio of 0.1 to 10% by weight based on the weight of coal consumed. A method for preparing purified charcoal used by the method according to claim 1, which comprises mixing subbitum or brown charcoal, a bromine compound and a powder adsorbent, wherein the powder adsorbent is calcium oxide , silica. , alumina, and ground cement kiln clinker kiln feed, conversion cement, and comprises one or more drying clinker over, further the powder, based on the weight of the adsorbent, less than 1 wt% Na 2 _O and 1 A method comprising less than% by weight K _{2 O.} 19. The method of claim 19, which is performed by a batch process. 19. The method of claim 19, which is performed as a continuous process. 19. The method of claim 19, wherein the bromine compound is calcium bromide. 19. The method of claim 19, wherein the powder adsorbent comprises less than 0.5% Na ₂ O and less than 0.5% K _{2 O.} 19. The method of claim 19, wherein the powder adsorbent comprises CKD, limestone and aluminosilicate clay. 19. The method of claim 19, wherein the powder adsorbent comprises kaolin. 19. The method of claim 19, wherein the powder adsorbent comprises metakaolin. 19. The method of claim 19, wherein the coal is PRB coal.