JP6595547B2 - Reduction of environmental pollution and pollution caused by coal combustion - Google Patents

Description

  This application is a valid US application no. No. 14 / 210,909 and provisional US application no. Claims 61 / 788,442, the entire disclosure of which is incorporated by reference.

  The present invention provides compositions and methods for reducing the level of mercury, nitrogen oxides and / or sulfur oxides emitted into the atmosphere upon combustion of mercury-containing fuels such as coal. In particular, the present invention provides for the addition of various halogens and other adsorbents to the coal combustion system during combustion. Use adsorbents to reduce pollutant emissions and prevent furnace contamination.

  There are significant sources of coal around the world that can meet most of the world's energy needs in the next two centuries. Although high sulfur coal is abundant, it requires a purification process to prevent excess sulfur from being released into the atmosphere upon combustion. In the United States, low-sulfur coal is present in the form of low-BTU coal in powder river basins in Wyoming and Montana, in the lignite deposits in the north and north of North and South Dakota, and in the 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 is at least partially volatilized during coal combustion. As a result, mercury does not tend to stay in the ash, but rather becomes a component of the flue gas. Without purification, mercury tends to be released to the atmosphere from coal burning facilities. Currently, some of the mercury is captured by equipment, for example in wet scrubbers and SCR control systems. However, most of the mercury is not captured and is therefore released through the stack.

  Mercury emissions into the atmosphere in the United States are about 50 tons per year. A significant fraction of emissions are emissions from coal burning facilities (eg, electricity utilities). 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, a method is desired in which mercury and other undesired compounds are captured 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. In addition, industry continues to actively pursue ways to reduce these pollutants.

  Certain coal facility managers are eligible for tax credits for efforts to reduce the release of these pollutants under IRS regulation 45. Under certain circumstances, these managers have seen unwanted furnace fouling. For example, when burning low sulfur subbituminous coal as fuel, deposits tend to form on the boiler tube surface, which results in reduced heat exchange efficiency and increased operating costs.

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

  In particular, the adsorbent used with subbituminous and lignite is subject to low levels of alkali. Prior art adsorbents with high alkali levels can cause fouling of the furnace in which they are burned. By reducing the alkalinity of the adsorbent, managers can minimize sodium and potassium used for unnecessary reactions in the gas phase leading to deposit formation on the boiler surface and other parts.

Adsorbents can be used to condition purified coal that can be combusted to reduce one or more mercury, nitrogen (as NOx) and sulfur (as SOx) emissions. The manufacturing method of refined coal includes mixing subbituminous coal (or lignite) and an adsorbent composition. In one embodiment, the adsorbent is 0.001-1 wt% liquid adsorbent, and 0.1-10 wt% powder adsorbent, wherein the proportion is based on the total weight of the refined coal. It is weight. The liquid adsorbent includes a bromine compound, the powder adsorbent includes calcium, silica, alumina, and further includes less than 1 wt% Na ₂ O and less than 1 wt% K ₂ O, where the powder adsorbent is 0 Further comprising less than 1% by weight chlorine.

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

  In various embodiments, the present invention provides compositions and methods for reducing mercury, nitrogen oxide (NOx) and sulfur oxide (SOx) emissions resulting from combustion of mercury-containing fuels such as coal. A commercially valuable embodiment is the use of the present invention to reduce nitrogen, sulfur and / or mercury emissions from coal burning facilities in order to protect the environment and comply with government regulations and treaty obligations. Improvements to the powder adsorbent provide superior performance by reducing fouling of coal fired furnaces while at the same time detrimental to the removal of environmental pollutants such as NOx and SOx.

  In various embodiments, the method of the present invention prevents mercury emissions from a point source, such as a coal fuel facility, into the atmosphere by capturing mercury in ash while minimizing furnace fouling that can reduce furnace efficiency. To do. Furthermore, the process prevents mercury and other heavy metals from being released to the natural environment due to leaching from solid waste such as coal ash produced by the combustion of mercury-containing coal. Either of these methods prevents mercury from entering the body of water. Therefore, prevention or reduction of mercury emissions from facilities such as coal burning facilities can be achieved in a variety of ways, including less air pollution, less water pollution, and less hazardous waste production, and resulting less soil pollution. Lead environmental benefits. For convenience but not limitation, an advantageous feature of the invention is described as preventing air, water, and soil contamination by mercury or other heavy metals.

In one embodiment, a method is provided for burning coal in a furnace to reduce NOx and at least one SOx and mercury emissions. The method includes burning refined coal in a furnace. The refined coal is in turn a mixture of subbituminous coal, bromine compound and powder adsorbent. The powder adsorbent comprises calcium, silica, alumina, and preferably with a low alkalinity value of less than 1 wt% Na ₂ O and less than 1 wt% K ₂ O, based on the weight of the powder adsorbent, and preferably It is further characterized by a low chlorine value 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, whereas the treatment level of a conventional powder adsorbent is 0.1 to 10% by weight, based on the weight of the coal. In various embodiments, the powder adsorbent comprises CKD or a mixture of CKD and other low alkali powders described herein. The powder adsorbent may also include an aluminosilicate clay such as kaolin or metakaolin.

In another embodiment, a method is provided for generating energy by combustion of mercury containing subbituminous coal in a coal combustion facility furnace. The method includes first administering a first adsorbent composition to the coal and transporting the coal containing the administered first adsorbent to a furnace. Simultaneously with transporting the coal containing the added first adsorbent, the second adsorbent is added to the furnace. The coal is then burned in a furnace in the presence of the first and second adsorbents 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 an embodiment, the second adsorbent has less than 0.5% chlorine.

In another embodiment, a method for producing refined coal is provided. The refined coal includes subbituminous coal and includes added adsorbent components. The method includes admixing coal, a liquid adsorbent (eg, 0.001-1 wt% based on coal) and a powder adsorbent (eg, 0.1-10 wt% based on coal), where the liquid sorbent comprises bromine compound and powder sorbent, wherein the powder sorbent many _SiO 2 more CaO, 10% from 40%, 2-10% of _Al 2 _O 3,. 1 to 5% _Fe 2 _O 3, comprising _{K 2} O of less than 1-5% of MgO, less than _{1% Na 2 O, 1%} . In various embodiments, the powder adsorbent is further characterized as having less than 0.5% chlorine or less than 0.1% chlorine.

  Advantageously, the use of powder adsorbents, particularly low total alkali, low chlorine or low composition, is used in furnaces burning sub-bituminous or lignite, such as powder river basin (PRB) coal. It was found to be effective in reducing fouling. The use of the improved adsorbent described herein allows furnace operators to comply with environmental regulations and qualify for certain tax credits under US IRS regulations, while at the same time undesired fouling 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 that are not literally described or illustrated. The embodiments allow those skilled in the art to practice the invention and provide remarkable environmental and operational benefits.

  In order to ensure the complete form of the refractory structure for treating the coal before combustion and / or for adding it downstream of the flame or flame, preferably producing the various advantages in the process at the lowest temperature. Use in combination with adsorbent components. If the component is added to the coal before combustion, the product is refined coal, and the use of this refined coal can reduce environmental pollution and qualify for certain tax credits in the United States.

The adsorbent composition includes calcium, alumina, silica and halogen. When burning sub-bituminous or lignite, such as powder river basin coal, keep the adsorbent K ₂ O up to 1% and reduce the adsorbent Na ₂ O up to 1% to reduce pollution, % Is based on the weight of the powder adsorbent containing calcium, alumina, silica and other ingredients. In embodiments, Na ₂ O and K ₂ O are each less than 0.5% or less than 0.1% each. Furthermore, it has been found that in various embodiments, it is also advantageous to provide a powder adsorbent having a low chlorine value (eg <0.5%, <0.3% or <0.1%).

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

In various embodiments, it is advantageous for the powder adsorbent to include an effective amount of cement kiln dust (CKD) that is believed to provide NOx reduction from the coal burning facility. Some CKD have a relatively high chlorine content (as high as 10%). When using CKD, due to the original content of CKD source and its alkali and chlorine, the powder obtained when burning subbituminous or lignite can result in too high in alkali and / or chlorine for best results. If so, mix some CKD with other ingredients with low sodium and potassium content, 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 alkaline materials include ground CKD (cement kiln clinker that may or may not meet cement product specifications, and then cement kiln clinker that is ground to mix with CKD); kiln feeds (eg, Feed stream introduced into the cement kiln, including all components that produce cement such as Ca, Mg, Si, Al, Fe, etc .; conversion cement (empty to create space to introduce specific new cement products) Cement product in the silo); dry clinker (clinker collected and ground prior to addition of CKD); storage CKD (CKD from storage location or waste storage); and limestone. To the extent that any of these materials represent waste products that must be discarded or landfilled, further environmental benefits are achieved by their use of the adsorbents described herein.

In various embodiments, the components together reduce mercury, nitrogen oxide, and sulfur oxide emissions;
Reduce the emission of elemental mercury and mercury oxide;
-Improve the efficiency of the coal combustion process through boiler tube de-slagging;
Prevent contamination of the furnace with unwanted deposits;
Increasing the level of Hg, As, Pb, and / or Cl in the coal ash;
Reducing the level of leachable heavy metals (eg Hg) in the ash, preferably to a level below the detection limit; and producing a highly cementitious ash product.

  As used herein, all percentages are based on weight unless otherwise indicated. 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 can and do exist in materials, more complex compounds, oxide analysis is a useful method for expressing compound concentrations for individual compositions.

  In a typical coal burning facility, the coal reaches the railcar. If the adsorbent has already been administered, the coal is refined coal. If the adsorbent has not yet been administered, the coal is raw coal. In an exemplary illustrated embodiment, the coal is transported to a belt receiver that directs the coal to a mixer. After the mixer, the coal is lowered to a supply belt and placed in a coal storage area. There are usually grate and containers in the coal storage area; from there the coal is transported by belt to an open storage area, sometimes called a bunker. Coal from a bunker or crusher can be fed to the stoker furnace. In a furnace where pulverized coal is burned, the coal is transported to a crushing device such as a crusher and finally to a pulverizer by a belt or other means. In the storage system, the coal is finely pulverized and transported to the dust collector by air or gas, and the finely pulverized coal is transported to a storage container and supplied to the furnace as necessary. In a direct fuel system, coal is pulverized and transported directly to the furnace. In a semi-direct system, coal is introduced from a fine grinder into a cyclone dust collector. Coal is fed directly from the cyclone dust collector to the furnace.

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

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

  In other various embodiments, the sorbent composition according to the present invention is added to various parts of the raw coal or furnace during combustion. In a non-limiting manner, before or during pulverization and / or while transported from the pulverizer to the furnace for combustion, in a mixer, in a belt receiver or supply belt, in a coal storage area, in a dust collector, Add adsorbent to coal in storage container, cyclone dust collector, grinder. Conveniently, in various embodiments, the adsorbent is added to the coal during the process of mixing the coal, such as in a mixer or pulverizer.

  Alternatively or additionally, the sorbent composition is added to the coal combustion system during fuel combustion by injecting the composition into a furnace. In a preferred embodiment, the composition is injected at or near a fireball (eg, the temperature is greater than 2000 ° F., 2300 ° F. or 2700 ° F.). According to burner and furnace operating parameter design, adsorbent is added efficiently, such as with fuel, with main combustion air, over flame, overfire air, or overfire air. Also, depending on the furnace design and operation, the adsorbent is injected from one or more faces of the furnace and / or from one or more corners of the furnace. Addition of the adsorbent composition and adsorbent components is sufficient to ensure that the injection temperature is sufficiently high and / or the set burner and furnace aerodynamics provide sufficient mixing of the powder adsorbent with the fuel and / or combustion products. It tends to be most efficient when guiding. Alternatively or additionally, adsorbent is added to the convection path downstream of the flame and furnace. In various embodiments, the optimal injection or dosing point of the adsorbent is the parameters (injection speed, injection position, the result of forming the furnace and the best mixing of the adsorbent, coal and the desired combustion products. It is found by selecting the upper flame distance, wall distance, powder injection method, etc.

  In a coal combustion system, hot combustion gases and air travel by convection away from the flame through a downstream convection path (ie, downstream associated with the fireball). The facility convection path includes a plurality of regions characterized by the temperature of the gas and combustion products in each region. Usually, the temperature of the combustion gas decreases as it moves downstream from the fireball. Fly ash and combustion gases are in an area where the temperature always decreases through the downstream of the convection path from the furnace where the coal in one embodiment is burned at a temperature of about 2700 ° F to 3600 ° F (about 1480 ° C to 1650 ° C). Moving. For example, downstream of the fireball is a temperature region below 2700 ° F. Further downstream, a temperature is reached where the temperature is cooled to about 1500 ° F. Between the two locations is a region having a temperature of about 1500 ° F. to about 2700 ° F. Further downstream, it reaches an area of less than 1500 ° F. Further along the convection channel, gas and fly ash pass through the low temperature region before reaching the baghouse or electrostatic precipitator, which typically has a temperature of about 300 ° F., before the gas is released from the stack. .

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

Thus, in various embodiments, the method of the present invention directly adds the adsorbent to the furnace during combustion ("mixed firing"addition);
Directly to fuel such as coal before combustion ("pre-combustion" addition for the production of refined coal);
In the temperature range above 500 ° C. and preferably in the preferred temperature range above 800 ° C., administering directly to the gas stream (addition of “post-combustion”); I need.

  The adsorbent is administered “to the coal combustion system” by any method or any combination of pre-combustion, co-firing or post-combustion. When adsorbent is added to a coal combustion system, it is believed that the coal or other fuel is 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 cut-off point or section 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 arrangement of the convection channel. possible. At some point, the combustion gas is clearly separated from what is a combustion chamber or furnace and apparently enters the convection flow path of the downstream gas in the fuel or furnace. However, many of the furnaces are very large, so it is possible to add adsorbent to the furnace at a considerable distance to supply fuel and air to form a fireball. For example, some furnaces, such as overfire air inlets designed to supply additional oxygen to the upper location of the fireball, especially to achieve more complete combustion and / or emission control such as nitrogen oxides Have The overfire air port 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 port, or higher in the combustion chamber (at the furnace port or just below the furnace port). The adsorbent component or composition is injected directly into it. Each of these locations is characterized by temperature and turbulent conditions that result in mixing of the adsorbent with fuel and / or combustion products (eg, fly ash). In embodiments, with respect to administering the adsorbent composition downstream or downstream of the furnace, the administration is at a temperature above 1500 ° F, preferably above 2000 ° F, more preferably above 2300 ° F, and more preferably. Preferably, the temperature is above 2700 ° F.

  In various embodiments described herein, sorbent compositions that tend to reduce or modify mercury, nitrogen, and / or sulfur emissions from coal combustion facilities are also used to burn high concentrations of cementitious fuels. There is a beneficial effect to give ash produced by. As a result, the ash can be used commercially as a partial or complete replacement for Portland cement in various cement and concrete products.

  In various embodiments, burning coal with the adsorbent composition described in the present invention results in ash with increased levels of heavy metals compared to coal burned without using an adsorbent, however, Nevertheless, it contains lower levels of leachable heavy metals than ash produced without the use of adsorbents. As a result, the ash is safe to handle and 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 burning of the carbonaceous feedstock. Non-combustible raw materials and particulate combustion products form ash, with some ash collected at the bottom of the furnace, but most ash is collected as fly ash from fuel by a dust collector or filter (eg, a coal house baghouse). 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 components added to the coal burning facility during combustion.

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

  In various embodiments for burning coal or other fuels with adsorbent components added, mercury and other heavy metals in the coal such as arsenic, antimony, lead and other metals are recorded in the baghouse or electrostatic precipitator. And become part of the overall ash content in a coal-fired plant; or in addition, mercury and heavy metals are found in the ash bottom. In this way, mercury and other heavy metal emissions from the facility are reduced.

  In general, mercury and other heavy metals in ash, even if 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 against leaching under acidic conditions. Advantageously, heavy metals in ash do not leach above regulatory levels; in fact, even if ash is usually produced by burning with an adsorbent, it contains higher absolute heavy metals. Decrease in leachable heavy metal concentration is observed in ash on a ppm basis. Because, in addition to the cementitious properties of ash, combustion ash (coal ash) is worthy of being marketed and used as a cementitious material for producing, for example, Portland cement and concrete products and ready mixes. .

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

  In one embodiment, a coal combustion method for reducing mercury emissions into the atmosphere is provided. The method includes administering an adsorbent composition comprising a halogen compound to a system for burning 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, producing ash and combustion gases. Combustion gas contains mercury, sulfur and other components. In order to limit the release to the atmosphere, the mercury level in the combustion gas is preferably monitored, for example by concentration analysis measurements, in order to achieve the desired mercury reduction in the combustion gas. In preferred embodiments, the amount of adsorbent composition administered is adjusted (i.e., increasing it, reducing it, or in some cases, depending on the mercury level value measured in the combustion gas). Adjust by deciding to keep it unchanged). In a preferred embodiment, the adsorbent is added to the system by administering it to the pre-combustion of the coal, after which the coal containing the adsorbent is transported into the furnace for combustion.

  In another embodiment, an adsorbent component comprising 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 either alone or separately from the sorbent composition and, if necessary, to the pre-combustion coal, to the furnace during combustion, or to the combustion gas downstream of the furnace at the appropriate temperature. In a preferred embodiment, the components are 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, preferably mercury is monitored in the fuel gas and the adsorbent dosing rate is adjusted according to the measured mercury level value. Halogens lead to reduced mercury emission levels, while aluminosilicates lead to non-leaching of mercury trapped in ash.

In a related embodiment, a method for reducing leaching of mercury and / or other heavy metals from ash produced by combustion of coal or other fuel in a coal combustion system or incinerator is provided as an incinerator or coal combustion system during combustion. Introducing an adsorbent containing silica and alumina into the ash, measuring the leaching amount of mercury and / or other heavy metals from the resulting ash, adjusting the silica and alumina levels added according to the measured leaching of heavy metals including. If the leaching amount is greater than desired, the adsorbent dosage rate can be increased to reduce the leaching amount to the desired range. In a preferred embodiment, the adsorbent further comprises a halogen (eg bromine) compound to increase the amount of mercury captured in the ash. Advantageously, an adsorbent comprising silica and alumina is added to a powder composition comprising <1% Na ₂ O and <1% K ₂ O to reduce or eliminate fouling.

In one embodiment, the present invention provides a method for producing a cementitious ash product while simultaneously reducing the amount of mercury oxide in fuel gas resulting from combustion of a mercury-containing carbonaceous fuel such as coal. The method comprises burning the fuel in the presence of an alkaline powder adsorbent wherein the powder adsorbent comprises calcium, silica and alumina. Alkaline powder is added to the pre-combustion of coal, injected into the furnace during combustion, administered to fuel gas downstream of the furnace (preferably at a temperature of 1500 ° F. or higher), or applied in any combination. When mixed with water, the powder is an alkali characterized by a pH of about 7, preferably about 8, and preferably about 9. Advantageously, the adsorbents each comprise less than 1% by weight, each less than 0.5% by weight, or each less than 0.1% by weight 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% alumina.

  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 emissions. 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 burned. Alternatively, if the measured concentration is at or below the target concentration, the rate of adsorbent addition can be reduced or maintained unchanged.

  In another embodiment, the powder composition is an adsorbent composition comprising an alkali calcium component and significant amounts of silica and alumina. In a non-leaching embodiment, the powder composition comprises an alkaline powder comprising 2-50 wt% aluminosilicate material and 50-98 wt% 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 is calcium montmorillonite, sodium montmorillonite, and One or more selected from the group consisting of kaolins. In certain embodiments, the powder sorbent comprises CKD and other materials to meet low alkali 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 treated with the adsorbent in a batch process or the proportion of coal consumed by combustion in a continuous process. In embodiments, the proportions in embodiments are 0.1-5 wt%, 0.1-2 wt%, 0.1-1.5 wt%, 0.1-1 wt%, 1-8 wt%. 2-8 wt%, 4-8 wt%, 4-6 wt%, or about 6 wt%. In certain embodiments, the powder composition is injected into a fireball or furnace during combustion and / or administered to the 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 for reducing mercury and / or sulfur released into the natural environment during coal combustion in a coal combustion system includes adsorbent components comprising bromine, calcium, silica and alumina in the coal combustion system. Adding and combusting the coal in the presence of an adsorbent component to generate combustion gases 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, in the pre-combustion of coal, in the furnace and / or at a suitable temperature as described herein. Add to combustion gas. The adsorbent comprising the component preferably comprises a maximum of less than 1% by weight Na ₂ O and a maximum of less than 1% by weight K ₂ O. Preferably bromine is present at a level to efficiently capture at least 20%, at least 40%, at least 80% or at least 90% mercury in the coal in the ash, and silica and alumina at 0.2 ppm. It is present at an efficient level to generate fly ash having a leach value of less than (200 ppb) mercury, preferably less than 100 ppb mercury, less than 50 ppb, and more preferably less than 2 ppb. A concentration of 2 ppb indicates a lower concentration than the current detection limit in the TCLP test for mercury leaching.

  In certain embodiments, the method provides 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 the coal prior to combustion. In some embodiments, the mercury concentration is higher than known fly ash to capture mercury in the ash rather than mercury emissions into the atmosphere. The fly ash generated by the method contains 200 ppm or less of mercury or higher levels 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 adsorbents (in typical embodiments, about twice the volume of ash), the increased and measured mercury concentration is released to the natural environment without the presence 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 greater than in fly ash resulting from burning coal without the addition of adsorbent or adsorbent components.

  Preferably the mercury in the coal ash is toxicity index leaching (TCLP), 40 CFR 260.11. As incorporated by reference in the chapter, “Methods of Assessing Solid Waste, Physical / Chemical Methods” when tested using EPA Publication SW-846-3rd Publication, Test Method 1311, it is 0. Shows a mercury concentration of less than 2 ppm. The total mercury content of ash generated from the adsorbent treating coal is more than two factors than the content of ash generated by combustion without adsorbent, but the combustion of coal with the adsorbent described herein It is usually observed that fly ash from leaches has less leachable mercury than ash generated from coal combustion without adsorbent. For example, normal ash from combustion of PRB coal contains about 100-125 ppm mercury; in various embodiments, it is generated by combustion of PRB coal with about 6 wt% adsorbent as 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 wt% to 99 wt% Portland cement, based on the total amount of coal ash or ash cement product described above. To do. In a further embodiment, the present invention provides a pozzolanic product comprising 0.01 wt% to 99 wt% pozzolanic, based on the total amount of ash pozzolanic product described above.

  In a further embodiment, the present invention provides a pozzolanic product comprising 0.01 wt% to 99 wt% pozzolanic, based on the total amount of ash pozzolanic product described above.

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

  The present invention further provides a component ready concrete product comprising an aggregate cement product and a hydraulic cement product.

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

  Thus, the method of the present invention includes burning coal and adsorbent added to generate coal ash and 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 sorbent compositions described herein comprise one or more alkaline powders containing calcium, along with lower levels of one or more aluminosilicate materials. The halogen component is added as a further alkaline powder component, if desired, or separately as part of the liquid or powder composition. Advantageously, the use of adsorbents leads to reduced emissions or emissions of sulfur, nitrogen, mercury, other heavy metals (eg lead and arsenic) and / or chlorine from coal combustion systems.

The adsorbent compositions used in the various embodiments of the invention described above and herein include components that provide calcium, silica and / or alumina, preferably in the form of an alkaline powder. In various embodiments, the composition also includes iron oxide, and in a non-limiting embodiment, the powder composition is about 2-10 wt% Al ₂ O ₃ , greater than 40% (eg, about 40-70 %) CaO,> 10 wt% SiO ₂ , about 1-5% Fe ₂ O ₃ , and <2%, preferably less than 1% total alkalinity such as sodium and potassium oxides. Ingredients comprising calcium, silica and alumina and other elements, if present, are mixed together as a component 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 includes suitable high levels of alumina and silica. The presence of alumina and / or silica leads to several 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 is observed in ash generated by coal or other fuels containing mercury in the presence of adsorbents. Resulting in low acidity leaching of mercury and / or other heavy metals.

As mentioned above, the component providing calcium, silica and / or alumina is preferably supplied as an alkaline powder. Without being limited by theory, it is believed that the alkalinity of the adsorbent component leads at least in part to the desired properties described above. For example, the alkalinity of the powder is thought to lead to a reduction in sulfur pitting. It is believed that the post-neutralized 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 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, high alkalinity in the adsorbent component tends to cause unwanted fouling. Thus, the teachings of the present invention use lower alkaline and / or lower chlorine adsorbents (as measured by Na ₂ O and K ₂ O content), particularly when using subbituminous and lignite. Describes how to overcome the disadvantages of this.

  Calcium sources for the sorbent composition of the present invention include, but are not limited to calcium powders such as calcium carbonate, limestone, dolomite, calcium oxide, calcium hydroxide, calcium phosphate and other calcium salts. Industrial products such as limestone, lime and slaked lime provide the majority of such calcium salts. Thus, they are suitable ingredients for the adsorbent composition of the present invention.

  Other calcium sources include various industrial products. Such products are commercially available, and some are sold as waste or by-products of other industrial processes. In a preferred embodiment, the product provides silica, alumina, or both to the composition of the present invention. Non-limiting 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 Deinked sludge ash, cupola aretel filter cake, and cupola furnace dust.

These materials and optionally other materials are combined to provide an alkali powder or mixture of alkali 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 included as components that fall within the preferred range of 1-5% Fe ₂ O ₃ and less than about 2% total alkali, they are suitable components of the sorbent composition. Mixtures of materials are also used. Non-limiting examples include 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 is high in calcium and contains various impurities that precipitate in the rimming procedure performed on sugar beet. It is a commercial product and is usually sold as a soil conditioner to landscapers and farmers.

  Cement kiln dust (CKD) refers to by-products that are typically produced in cement kilns or related processing equipment during the manufacture of Portland cement.

  CKD typically comprises a combination of different particles produced in different areas of the kiln, pretreatment equipment, and / or material handling system, such as clinker dust, partially fully fired material dust, and Contains raw material (hydrate and dehydrate) dust. The composition of CKD varies depending on the raw materials and fuels used, the production and processing conditions, and the location of the CKD collection point in the cement production process. CKD may include dust or particulate matter collected from kiln effluent (ie, effluent) streams, clinker cooler effluents, pre-fired furnace 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 can satisfy the low alkaline specification powder adsorbents described herein. If only high alkali CKD is utilized, it may be necessary to mix with the low alkali material described above or substitute a portion of the high alkali CKD product with the alkali material.

  Although CKD compositions vary for different kilns, CKD usually has at least some cementitious and / or pozzolanic properties due to the presence of clinker and dust of fired material. Typical CKD compositions include silicon-containing compounds such as tricalcium silicate, silicates including dicalcium silicate; aluminum-containing compounds such as aluminates including tricalcium aluminate; and iron-containing compounds such as alumino. Ferrite containing ferrite including tetracalcium. CKD usually comprises calcium oxide (CaO). Exemplary CKD compositions comprise about 10 to about 60% by weight, optionally about 25 to about 50% by weight, and optionally about 30 to about 45% by weight calcium oxide. In some embodiments, CKD provides about 1 to about 10% free lime (available for hydration with water), optionally about 1 to about 5%, and in some embodiments In a concentration of about 3 to about 5%. Further, in certain embodiments, the CKD comprises, among others, compounds containing alkali metals, alkaline earth metals, and sulfur.

  Other exemplary sources of alkaline powders comprising calcium and preferably further comprising silica and alumina include various cement related by-products (in addition to the Portland cement and CKD described above). Including. A mixed cement product is a suitable example of such a source. These mixed cement products generally comprise a mixture of Portland cement and / or its clinker in combination with slag and / or pozzolans (eg, fly ash, silica fume, calcined shale). Pozzolans are usually siliceous materials that are not themselves cementum but exhibit hydraulic cement properties when reacted with free lime (free CaO) and water. Other sources are masonry cement and / or hydraulic lime, which includes a mixture of Portland cement and / or its clinker and lime or limestone. Other suitable sources are alumina cements, which include limestone and bauxite (one or more aluminum hydroxide minerals and silica, iron oxide, titania, aluminum silicate, and other minor or minor amounts). A hydraulic cement produced by burning a mixture of naturally occurring heterogeneous materials comprising various mixtures of impurities. Yet another example is a pozzolanic cement, which is a blended cement containing a substantial concentration of pozzolanic. Typically, pozzolanic cement comprises calcium oxide but is substantially free of Portland cement. Common examples of widely used pozzolans include natural pozzolans (eg certain volcanic ash or tuff, certain diatomaceous earth, calcined clay and shale) and synthetic pozzolans (eg silica fume and fly ash).

Lime kiln dust (LKD) is a by-product from the production of lime. LKD is dust or particulate material collected from lime kilns or related processing equipment. The lime produced can be classified as calcium rich lime or dolomite lime, and the LKD varies depending on the method of forming it. Lime is often produced by a calcination reaction carried out by heating calcite raw materials such as calcium carbonate (CaCO ₃ ) to form free lime CaO and carbon dioxide (CO ₂ ). High calcium content lime has a number of impurities including high concentrations of calcium oxide and usually aluminum and iron containing compounds. High calcium content lime is usually formed from high purity calcium carbonate (purity of about 95% or more). Typical calcium oxide content in LKD products obtained from high calcium content lime processing is about 75% or more, optionally about 85% or more, and in some cases about 90% or more. In some lime production methods, dolomite (CaCO ₃ —MgCO ₃ ) is decomposed by heating to produce mainly calcium oxide (CaO) and magnesium oxide (MgO). What is formed thereby is known as dolomite lime. In LKD produced by dolomite lime processing, calcium oxide may be present at about 45 wt% or more, optionally greater than about 50 wt%, and in certain embodiments, greater than about 55 wt%. LKD varies based on the type of lime method used, but usually has a relatively high concentration of free lime. A typical amount of free lime in LKD is about 10 to about 50%, and optionally about 20 to about 40%, depending on the relative concentration of calcium oxide present in the lime product produced. .

  Slag is a by-product compound that is usually produced by metal manufacturing and processing. The term “slag” encompasses a wide variety of by-product compounds and typically comprises most non-metallic by-products of the manufacture and processing of irons and / or steels. Usually, 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 present invention include iron slag, such as that produced in a blast furnace (also known as a cupola furnace), including air-cooled blast furnace slag ( ACBFS), expanded or foamed blast furnace slag, pelleted blast furnace slag, granular blast furnace slag (GBFS) and the like. Steel slag can be produced from a basic oxygen steel furnace (BOS / BOF) or an electric arc furnace (EAF). Many slags are recognized to have cementitious and / or pozzolanic properties, however, as will be appreciated by those skilled in the art, the degree to which slag has these properties is determined by their respective compositions and Depends on how they are derived. Typical slags comprise calcium-containing compounds, silicon-containing compounds, aluminum-containing compounds, magnesium-containing compounds, iron-containing compounds, manganese-containing compounds and / or sulfur-containing compounds. In certain embodiments, the slag comprises about 25 to about 60% by weight calcium oxide, optionally about 30 to about 50% by weight, and optionally about 30 to about 45% by weight. One example of a suitable slag that normally has cementitious properties is ground granular blast furnace slag (GGBFS).

  As noted above, other suitable examples include blast furnace (cupola) furnace dust (eg, cupola arrester filter cake) collected from an air pollution control device attached to the blast furnace. Another suitable industrial by-product source is paper deinked 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 sorbent compositions of the present invention. Similarly, many of these well-known by-products comprise 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 typical industrial product and / or industrial by-product combination is contemplated for use as an alkaline powder in certain embodiments of the invention.

  In various embodiments, the desired treatment level of silica and / or alumina is that obtained by adding materials (eg, 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.) as necessary to provide preferred 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, as long as an adequate level of calcium is maintained, there is no upper limit from a technical point of view. However, from a cost standpoint, it is usually desirable to limit the proportion of the more expensive aluminosilicate material. Thus, the adsorbent component preferably comprises about 2-50% by weight, preferably 2-20% by weight, and more preferably about 2-10% by weight of aluminosilicate material (eg, a typical clay). Become. Non-limiting examples of adsorbents are about 93% by weight CKD and LKD blend (eg, 50:50 blend or mixture) and about 7% by weight aluminosilicate clay.

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 an aluminosilicate clay (eg, , But not limited to, montmorillonite or kaolin). The adsorbent composition preferably forms a refractory mixture with calcium sulfate produced by combustion of sulfur-containing coal in the presence of a CaO adsorbent component such that the calcium sulfate is handled by the particle control system; And enough SiO ₂ and Al ₂ O ₃ to form a refractory 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 a minimum of 10 wt% silica and a minimum of 2-10 wt% 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 provide chloride in ash and mercury, lead, arsenic, and other heavy metals. Captures and renders heavy metals non-leachable under acidic conditions and improves the cementitious properties of the resulting ash. As a result, the release of harmful elements is mitigated, reduced or eliminated, and valuable cementitious material is produced as a by-product of coal combustion.

  Suitable aluminosilicate materials include a wide variety of inorganic minerals and materials. For example, many minerals, natural materials, and synthetic materials can have any other cation (eg, but not limited to Na, K, Be, Mg, Ca, Zr, V, Zn, Fe, Mn) and / or Contains silicon and aluminum associated with the oxy environment, along with other hydration waters, 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 a non-limiting example is the clay shown above.

  In aluminosilicate materials, silicon tends to exist as tetrahedra, while aluminum exists as tetrahedra, octahedra, or a combination of both. Chain or network aluminosilicates are assembled in such materials by sharing one, two or three oxygen atoms between the silicon and the aluminum tetrahedron or octahedron. Such minerals follow various names such as silica, alumina, aluminosilicate, geopolymer, silicate, and aluminate. However, the proposed 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 polymorphic SiO ₂ —Al ₂ O ₃ . For example, siliminate contains silica octahedron and alumina that is ultimately divided between tetrahedron and octahedron. Kyanite is based on silica tetrahedron and alumina octahedron. Andalsite is another polymorphic SiO ₂ .Al ₂ O ₃ .

In other embodiments, the silicate chain provides silicon (as silica) and / or aluminum (as alumina) to the composition of the present invention. Silicate chains include, but are not limited to, pyroxenes and semi-pyroxene silicates composed of infinite chains of SiO ₄ tetrahedra bonded by sharing oxygen atoms.

  Other suitable aluminosilicate materials include sheet materials such as, but not limited to, mica, clay, chrysotile (eg, asbestos), talc, soapstone, pyrophyllite, and kaorilite. Such materials are characterized in that the silica and alumina octahedrons and tetrahedrons have a layered structure sharing two oxygen atoms. Layered aluminosilicates include clays such as chlorite, sea chlorite, illite, palygorskite, pyrophyllite, saconite, vermiculite, kaorilite, calcium montmorillonite, sodium montmorillonite, and bentonite. Other examples include mica and talc.

  Suitable aluminosilicate materials also include synthetic and natural zeolites, such as, but not limited to, calcite, calcite, chabazite, soda fluorite, philipsite, and mordenite groups. Other zeolite minerals include pyroxenite, Brewsterite, chabazite, zeolitite, yagawaralite, diatomite, dolomite, polingite, and clinoptilolite. The zeolite is a mineral or synthetic material characterized by an aluminosilicate tetrahedral framework, ion-exchangeable “giant cations” (eg, Na, K, Ca, Ba, and Sr) and loosely held water molecules.

In other embodiments, frameworks or 3D silicates, aluminates, and aluminosilicates are used. Skeletal aluminosilicates are characterized by a structure in which SiO ₄ tetrahedra, AlO ₄ tetrahedra and / or AlO ₆ octahedra are bonded in three dimensions. Non-limiting examples of skeletal silicates containing both silica and alumina include plagioclase, such as anorthite, anorthite, neutral feldspar, hypochlorite, anorthite, fine plagioclase, sanidine and orthofeldspar. It is done.

  In one embodiment, the adsorbent powder compositions are such that they contain a large amount of calcium, preferably greater than 20% by weight or greater than 40% by weight calcium based on calcium oxide, and furthermore they are commercially available 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 wt% alumina, preferably more than 6 wt% alumina, preferably more than 7 wt% alumina, and preferably more than about 8 wt% alumina. Comprising.

  Coal or other fuels are treated with an adsorbent component in a ratio effective to control 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 being treated or the proportion of coal consumed by combustion when the adsorbent is a powder adsorbent containing calcium, silica and alumina. In the range of about 0.1 wt% to about 20 wt%. When adsorbent components are combined in a single composition, the component treatment level corresponds to the adsorbent treatment level. Thus, a single adsorbent composition can be provided and metered or otherwise measured for addition to a coal combustion system. In general, it is desirable to use a minimum amount of adsorbent so that the desired effect on sulfur and / or mercury emissions is sufficiently provided while the system is not overloaded with excess ash. Accordingly, in various embodiments, the adsorbent treatment level ranges from about 0.1 wt% to about 10 wt%, and in some embodiments, from about 1 or 2 wt% to about 10 wt%. For many coals, a 6 wt% powder adsorbent addition rate has been found to be acceptable.

  An adsorbent composition comprising a halogen compound contains one or more organic or inorganic compounds containing halogen. Halogen includes chlorine, bromine and iodine. Preferred halogens are bromine and iodine. Halogen compounds are halogen (especially 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 suitably contain high levels of bromine are considered within the scope of the present invention. Non-limiting examples of organic bromine compounds include methylene bromide, ethyl bromide, bromoform, and carbon tetrabromide. Non-limiting iodine inorganic sources include hypoiodite, iodate, and iodide, with iodide being preferred. Organic iodine compounds can also be used.

  When the halogen compound is an inorganic substituent, it is preferably a bromine or iodine-containing alkaline earth element salt. Typical alkaline earth elements include beryllium, magnesium, and calcium. Among the halogen compounds, alkaline earth metal (for example, calcium) bromide and iodide are particularly preferable. Alkali metal bromine and iodine compounds, such as bromide and iodide, are effective in reducing mercury emissions. However, in some embodiments they are less preferred because they tend to cause corrosion of boiler tubes and other steel surfaces and / or contribute to tube deterioration and / or refractory brick deterioration. In various embodiments, it has been found desirable to avoid potassium salts of halogens 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 particularly essentially sodium-containing or potassium-containing bromine or iodine compounds. Not contained in.

  In various embodiments, the sorbent composition containing halogen is provided in the form of a liquid or solid composition. 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 fuel gas downstream of the furnace. If the halogen composition is a solid, it can further contain the calcium, silica and alumina components described herein as powder adsorbents. Alternatively, the solid halogen composition is administered onto the coal and / or otherwise into the combustion system separately 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 bromine or iodine containing soluble salts. 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. Because of the efficiency of coal addition prior to combustion, in various embodiments, it is preferred to add a mercury adsorbent with as high a level of bromine or iodine compound as possible. In a non-limiting embodiment, the liquid adsorbent contains 50 wt% or more of a halogen compound such as calcium bromide or calcium iodide.

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

  As a further example, one embodiment of the present invention includes 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 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% , Based on the amount of coal processed or the rate of consumption of coal from 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 an exemplary embodiment, the addition of bromide or iodide compound is at a low level, for example 0.01% to 1% by weight based on solids. Thus, when using a 50 wt% solution, adsorbent is added in a ratio of 0.02% to 2% to achieve a low level of addition. For example, in a preferred embodiment, the coal has a ratio of 0.02-1% by weight, preferably 0.02-0.5% by weight calculated assuming calcium bromide is about 50% by weight adsorbent. Treat with liquid adsorbent. In typical embodiments, a liquid adsorbent containing 50% calcium bromide is about 1%, 0.5%, or 0.25% (where% is based on the weight of the coal) before combustion. Add on coal. In a preferred embodiment, the initial treatment is initiated at a low level (eg, 0.01% to 0.1%) and gradually until a desired (low) level of mercury emission is achieved based on emission monitoring. Increase to. When the halogen is added as a solid or as a multi-component composition with other components (eg, calcium, silica, alumina, iron oxide, etc.), similar processing levels of halogen are used.

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

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

  In one embodiment, various adsorbent components are added onto the coal before its combustion in order to produce so-called refined coal. The coal to which the adsorbent is administered is preferably granular coal and, if necessary, ground or pulverized according to conventional procedures. In a non-limiting example, the coal is ground so that 75% by weight of particles pass through a 200 mesh screen (a 200 mesh screen 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 the form of a powder. 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 wet when fed into the burner. In various embodiments, the sorbent composition is continuously added onto the coal by spraying or mixing on the coal on a conveyor, screw extrusion, or other feeder at a coal combustion facility. In addition or alternatively, the adsorbent composition is separately mixed into the coal at the coal combustion facility or at the coal production site. 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 in a pulverizer that pulverizes coal prior to injection. If desired, the rate of addition of the sorbent 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 preferred embodiments, nitrogen, mercury and sulfur are monitored using industry 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 containing the analytical instrument is preferably placed in the convection path downstream of the point of addition of mercury and sulfur adsorbent. 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 an appropriate location in the convection flow path without attaching an apparatus or monitoring device. In various embodiments, pumps, solenoids, atomizers, and others that are actuated or controlled to adjust the rate of addition of the adsorbent composition into the coal combustion system using the measured mercury or sulfur levels. Give a feedback signal to the device. Alternatively or additionally, the adsorbent addition rate can be adjusted by a human operator based on the observed mercury and / or sulfur levels.

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

  The cementitious properties of the resulting ash described herein are shown, for example, in view of the strength activity index of the ash or, more precisely, the cementitious mixture containing ash. As described in ASTM C311-05, the strength activity index is measured in terms of the hardening behavior and characteristic development of 100% Portland cement concrete and test concrete with 20% Portland cement replaced with an equivalent amount of test cement. This is done by comparing. In the standard test, the intensity is 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 “pass”. In various embodiments, the ash of the present invention exhibits 100% to 150% strength activity in the ASTM test, which is strongly “passed”. Similar high values are observed when testing is performed with test mixtures having other than an 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 to 50:50, where the first ratio value is Portland cement and the second ratio ratio. Is the ash produced according to the present invention. In certain embodiments, the strength development of the all ash test cementitious mixture (ie, where ash represents 100% of the cement in the test mixture) is all greater than 50% of the strength of the Portland cement control, and preferably Is more than 75%, and more preferably 100% or more, for example 100-150%. Such results are indicative of the high cementitious properties of ash produced by burning coal or other fuels in the presence of the adsorbent components described herein.

  The ash obtained from coal combustion according to the present invention contains non-leached form of mercury and can be marketed. Non-limiting use of spent or waste fly ash or bottom ash includes use as a component in a cement product (eg, Portland cement). In various embodiments, the cement product contains about 0.1% to about 99% by weight of coal ash produced by burning the composition of the present invention. In one aspect, the non-leaching characteristics of mercury and other heavy metals in coal ash make it suitable for all known coal ash industrial applications.

  The coal ash according to the invention, in particular fly ash collected by particle control systems (baghouses, electrostatic precipitators, etc.), is used in Portland cement concrete (PCC) as part of Portland cement or as a complete replacement. In various embodiments, ash is used as a mineral admixture or as a component of a mixed cement. As a blending agent, ash can be a total or partial replacement of Portland cement and can be added directly into ready-mix concrete in a batch plant. Alternatively or in addition, the ash is embedded in a cement clinker or blended with Portland cement to produce a mixed cement.

Class F and Class C fly ash are defined, for example, in US Standard ASTM C 618. The ASTM standard serves as a fly ash specification when fly ash 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 Class F and Class C fly ash specifications in ASTM C 618. It should be noted that there are. Typical values for the fly ash of the present invention are> 50 wt% CaO and <25 wt% SiO ₂ / Al ₂ O ₃ / Fe ₂ O ₃ . In various embodiments, the ash is a total of 51-80 wt% CaO and about 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 allows more than 50% replacement or reduction of such cementitious materials and Portland cement used in cementitious materials. Yes. In various applications, the coal ash resulting from burning coal with the adsorbents described herein is sufficient to be a complete (100%) replacement for Portland cement in such compositions. It is cementitious.

  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. Yes. Coal ash produced according to the methods described herein replaces up to 50% of Portland cement while maintaining 28 day strength development equivalent to that developed in products using 100% Portland cement. It was found to be sufficiently cementitious. That is, in various embodiments, the ash is not eligible for chemical composition as Class C or Class F ash according to ASTM C 618, but nevertheless it is useful for formulating high strength concrete products. is there.

  Also, coal ash produced according to the present invention can be used as a component in the production of flowable fills (also called controlled low strength materials or CLSM). CLSM is used as a self-smoothing self-compressing backfill material instead of compressed embankments or other fills. The ash described herein is used in various embodiments as a 100% replacement for 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 flowable fill should not exceed 1035 kPa (150 pounds per square inch) if the removal of the cured material is required. A jack hammer may be required for removal when formulated to achieve higher ultimate strength. However, if it is desirable to formulate a flowable fill mixture for use in higher load bearing applications, a mixture containing a higher range of compressive strength upon curing can be designed.

  Also, the coal ash produced according to the methods described herein is useful as a component of the stabilized base and sub-base mixture. Since the 1950s, numerous variations of basic lime / fly ash / aggregate formulations have been used as stabilizing base mixtures. A stabilization-based use example is one that is used as a stabilized road infrastructure. For example, gravel roads can be reused instead using ash from the composition. The existing road surface is crushed and placed in its original position. For example, the ash produced by the method 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 beyond regulatory requirements. Rather, the ash produced by the method of the present invention is less leachable mercury and less leachable other heavy metals than coal ash produced by burning coal without using the adsorbents described herein. (For example, arsenic and lead).

  Thus, the present invention provides various methods that eliminate the need to landfill 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 a cementitious ash that can replace the Portland cement in whole or in part in various applications. The reuse of cementitious products avoids the production of at least some Portland cement, saves the energy required to produce cement, and releases significant amounts of carbon dioxide resulting from cement production. can avoid. Other savings in carbon dioxide emissions result from the reduced need for lime or calcium carbonate in the desulfurization scrubber. Thus, the present invention provides, in various embodiments, a method for saving energy and reducing greenhouse gas (eg, carbon dioxide) emissions. Further details of various embodiments of this aspect of the invention are described below.

Example 1
The required specifications for 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. 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 should preferably be maintained above 8: 1. This ensures sufficient CaO to absorb the added sulfur.
2. Indeed, the Hg content of the powder adsorbent should be kept the same or less than the coal content being processed.
Acceptable test methods for oxidation analysis are as follows:
ASTM D3682 Concerning Large and Trace Elements in Combustion Residues from Coal Utilization Process
Standard test method
ASTM C114 Standard Test Method for Chemical Analysis of Hydraulic Cement
Acceptable test method for mercury content
ASTM D6414 Coal and coal combustion by acid extraction or wet oxidation / cold steam atomic absorption
Standard test method for total mercury in residue
ASTM D6722 Concerning total mercury in coal and coal combustion residues by 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 are conducted at the Combustion Test Facility (CTF) of the Energy and Environmental Research Center (EERC) to measure the effect of adsorbents on NOx and Hg emissions during the combustion of Powder River Basin (PRB) subbituminous coal. It was broken. Tests were conducted to support attempts to confirm that the method of use produced “refined coal” as defined in Article 45 of the Internal Revenue Code. Article 45 (c) (7) (A) defines refined coal containing fuel, which is reasonable: 1) solid fuel produced from coal and 2) use it for steam generation purposes Sold by forecasted taxpayers, and 3) (when used for steam generation), qualifies taxpayers with “Reduced Emission Reduction” certification.
In Article 45 (c) (7) (B), the term “reduction of emission” refers to NOx released when burning refined coal compared to the amount released when burning the supplied coal feedstock. It is defined to mean any of at least 40% reduction of at least 20% and SO ₂ release or Hg emissions release.

Equipment and Procedure Description CTF is used to extensively 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. CTF can produce gas and particle samples that are typical of samples produced in industrial and current size pulverized coal (pc) combustion boilers. The test facility has emissions including an electrostatic precipitator (ESP) or a fiber filter baghouse for particle control, a selective catalytic reduction (SCR) column for NOx control, and a wet scrubber to control sulfur emissions. Has several pollution control devices that can be used to reduce. The CTF was designed to reproduce almost all the full-scale US PC combustion boiler types and shapes used by US standard 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 to simulate a full-scale pc-fired boiler, but with commercial boilers there are many changes that can affect the combustion effect, so it can be observed in normal real machine operations. Cannot be reproduced accurately. The burn rate is typically an indicator of the degree of coalification with a low degree of coalification burned at the lowest level of the range and a high degree of coalification 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 desired combustion chamber outlet temperature (FEGT) to reproduce the specific boiler used in the coal combustion power plant. For subbituminous coal, a combustion rate of 550,000 to 600,000 BTU / hr generally results in a FEGT of 2100 ° F. to 2200 ° F., which burns a lot of sub-bituminous coal such as the coal tested in the present invention. Typical in a plant.

  CTF combustion air is supplied by a forced draft fan in this balanced ventilation system. The ventilator introduced at the rear of the system maintains a slight vacuum in the combustion zone and releases the combustion fuel gas into the exhaust stack. Combustion air is typically preheated using an electric heater and divided into primary air, secondary air, and overfire air (OFA).

Combustion gas analysis is in two locations; furnace outlets used to monitor and maintain specific excess air levels throughout the test, and emissions detected at the end of the system can correct dilution caused by leakage As provided by a continuous discharge monitor (CEM) at the outlet of the particle controller, which is 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 includes five modules for O ₂ , CO ₂ , CO, SO ₂ , and NOx measurements. Except for SO _2, each module was made Ametek. Each analyzer uses a combustion gas regulator to remove moisture from the gas stream prior to analysis. All data reported herein are on a dry gas basis. All gas analyzes are continuously monitored and recorded by the CTF data acquisition system. National Instrument provided both hardware and software (LabView) used to collect all the data present here.

In CEM analysis, each test performed on the CTF is individually calibrated in advance. Nitrogen is used as the zero gas, but some span gases are used to calibrate each device over the range used during the test. In general, 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 carried out in various ranges depending on the sulfur content of the coal to be tested. During this series of tests, SO ₂ measurement device is calibrated in the range of 0 to 1000 ppm, which is suitable is for the sulfur content in the PRB subbituminous tested herein.

Fuel gas mercury (Hg) measurements were obtained separately by a continuous Hg monitor (CMM) manufactured by Tekran® Instruments Corporation. The system draws a gas sample from a fuel gas conduit at the outlet of the particle controller. Moisture is removed from the gas stream before analysis. The fuel gas that adjusts the system condition uses a 10% NaOH solution to remove CO ₂ and SO ₂ to accurately measure the Hg concentration of the fuel gas and to prevent adverse effects due to the performance of the analyzer. To do. Since all mercury analyzers can only measure elemental mercury (Hg ⁰ ), the total mercury (Hg _(T) ) concentration can be determined with a 10% NaOH solution containing tin (II) chloride, Hg ^{2+ of} mercury oxide. It is obtained by reducing the part. The Tekran device collects Hg ⁰ from a tested sample on a cartridge containing ultra high purity gold adsorbent. The merged Hg is then thermally desorbed and examined using atomic fluorescence spectroscopy. The dual cartridge design then allows for additional sampling and despawning caused by continuous measurement of sample flow. Similar to the CEM scale correction described above, the CMM is also set to zero prior to testing, span measured, and checked at the end of the test. No drift was observed during the tests performed and reported herein. The CTF configuration 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 feed and refined coal testing period, fuel and fly ash samples were collected and submitted for analysis. Samples collected during the study are described in the following discussion.

The sub-bituminous coal for fuel preparation and analytical testing 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 8500-10,000 Btu / Ib, depending on water content, which is taken from several mines in Wyoming.

  The allowable coal was received as necessary, and the upper surface moisture of the floor dried was examined. Air-dried samples were crushed to a maximum size of ¼ inch and fed to a hammer mill and made into a particle size distribution where about 70% passed 200 mesh for use during testing (many coal burning power plants Typical coal treatment achieved in). This particle size distribution is at most representative of the particle size distribution achieved by fine milling of full-scale commercial boilers. The refined coal sample used during this series of tests is made by EERC and is believed to be comparable to refined coal produced in a 45 area facility. The adsorbent used to prepare the refined charcoal was administered to a finely ground fuel as shown below. This differs from real scale application in that the adsorbent is recovered from the stock in the coal yard, mixed, crushed and then sent to the pulverizer. The main reason for administering the adsorbent to the pc utilized in the pilot scale test is the potential loss of material in the dust collection duct device utilized during pulverization of the fuel sample. All pilot scale fuel samples are crushed and pulverized as little as possible before use. Preparing purified fuel from pc samples avoids potential loss of adsorbent in the dust collection system and results in the best simulation of what happens on a full scale.

  The finely pulverized fuel was divided into two parts; a feedstock sample and a second coal sample that was processed into refined coal. On the floor of the coal preparation facility, refined charcoal was prepared by placing each measured amount (about 500 lb). The weighed halogen-based adsorbent and powder adsorbent were carefully administered to the coal, and the coal was periodically mixed during the adsorbent administration. The powder adsorbent was distributed by hand, and several routes were made to mix the fuel after each route over the amount of coal pile. The 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. Processing was required in several ways to fully distribute the adsorbent. After each pass, a rake is used to replace the pile and a new surface is exposed for the next processing pass. In each case, a small amount of adsorbent was distributed on the coal pile and mixed until a specific treatment ratio reached 0.008 wt% halogen-based adsorbent and 0.25 wt% powder adsorbent. .

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

Fuel Analysis During each study period, the coal sample has an opening located directly below the rotary valve between the storage hopper and the feed hopper is transported from a storage hopper via a small tube extending through the sidewall of the feeder 70% of the angle . This louver catches a small amount of fuel along the way each time the supply hopper is filled. In this way, an accurate combustion sample of the fuel is obtained. The coal sample falls by weight into a sample bag attached to the end of the sample tube. Separate from the fuel sample representing the feedstock and refined coal test period, a new bag is attached to the sample tube prior to the next test period, respectively.

  Combustion coal is continuously collected and the emission baseline from the combustion of coal feedstock and the emission from the combustion of refined coal as well are measured. Coal feed and refined coal were provided separately for approximate analysis and elemental analysis, calorific value, inorganic elemental oxide analysis (by fluorescent X-rays), and chlorine and mercury content measurements. The analysis results are shown in Table 1. The fuel sample has undergone several processing steps that tend to allow evaporation of a small amount of acceptable moisture content. The greatest reduction occurs during fuel grinding. The hammer mill pulverizer generates an induced draft that tends to slightly dry the exposed surface of the pulverized coal particles resulting from the pulverization. The resulting dryness is mainly a function of ambient atmospheric conditions (temperature and relative humidity) during fuel preparation. As a result, the combustion composition is analyzed so that it can be easily compared between the coal feed and refined coal.

The coal feed (test AF-CTS-1461) was measured with a moisture content of 20.03 wt% and a combustion heat of 9621 Btu / lb. The calorific value and ash content without water were measured at 12,031 Btu / lb and 4.91% by weight, respectively. The sulfur content of the coal feed was measured by 0.37 wt% on an anhydrous basis (0.624 lbSO ₂ / MMBtu). Powder adsorbents and liquid halogen-based adsorbents do not generate heat, and liquid halogen-based adsorbents introduce additional moisture into the refined charcoal due to the water content of the liquid. For this reason, a reduction in the calorific value (Btu / lb) of refined coal is usually expected as compared to Btu / lb of coal feedstock. 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 lkb / TBtu, anhydrous base) and 0.0556 μg / g (5.908 lkb / TBtu, anhydrous base) in the feed and refined charcoal samples, respectively. The chlorine content of the feedstock and refined charcoal sample was measured at 19.4 and 30.0 μg / g, respectively.

  The dry sieving analysis of the feedstock and refined coal sample collected during each test is shown in the table of Example 2. The results for the coal feedstock are 84.3% by weight passing through 200 mesh and 69.2% by weight passing through 325 mesh, whereas for the refined coal sample, 87.1% by weight passes through 200 mesh and 73. 1% by weight passes through 325 mesh.

Example 2
The coal feedstock is PRB coal. Refined charcoal is a PRB coal feedstock with 0.008 wt% halogen-based adsorbent and 0.25% powder adsorbent. The powder adsorbent is 15% CKD and 85% ground CKD. The halogen-based adsorbent is derived from Example 1. NOx and Hg emissions were measured for the feedstock and refined coal.

^＊適用不可

^* Not applicable

  The mercury concentration was 0.558 μg / g in coal feed ash and 0.833 μg / g in refined coal ash.

Example 3 Central American Subbituminous Coal The coal feedstock is PRB coal. Refined coal is a PRB coal feedstock with 0.005 wt% halogen-based adsorbent and 0.25% powder adsorbent. The powder adsorbent has 15% CKD and 85% ground CKD. The halogen-based adsorbent is derived from Example 1. NOx and Hg emissions were measured for the feedstock and refined coal.

  In the morning, a release baseline was established by burning coal feedstock burned at an average rate of 60.28 lb / hr to reach a FEGT of about 2139 ° F. Excess oxygen was controlled to 3.05% at the furnace outlet (about 16.98% excess air), with OFA utilized at 15.13% to simulate NOx control at the furnace outlet.

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

* 適用不可

* Not applicable

Claims (12)

A method of burning coal in a furnace to reduce the emission of NOx and at least one SOx and mercury comprising burning refined coal in the furnace, the refined coal being sub-bituminous or lignite, 0 A mixture of 0.001 to 1.0 wt% bromine compound and 0.1 to 10 wt% powder adsorbent, the powder adsorbent comprising cement kiln dust (CKD), and further the powder adsorption based on the weight of the agent _Na 2 O of less than 0.1 wt%, _K 2 O of less than 0.1 wt%, and comprises chlorine less than 0.5 wt%, the bromine compound and the powder sorbent Compared with coal combustion not using coal, mercury emission from coal combustion facilities is reduced by 40% or more, and compared with coal combustion not using the bromine compound and powder adsorbent, NOx emissions from coal combustion facilities are reduced. 20% or more Reduce the method.   The process according to claim 1, wherein the refined charcoal comprises 0.002 to 1.0 wt% bromine compound and 0.1 to 2.0 wt% powder adsorbent.   The method of claim 1, wherein the powder adsorbent comprises CKD and one or more of ground CKD, kiln feed, conversion cement, dry clinker, storage CKD, and limestone.   The method of claim 1, wherein the powder adsorbent comprises CKD and ground CKD.   The method of claim 1, wherein the powder adsorbent comprises CKD and aluminosilicate clay.   The method of claim 1, wherein the powder adsorbent comprises CKD and kaolin. A method of generating energy by burning sub-bituminous coal containing mercury in a furnace of a coal combustion facility;
Administering a first adsorbent composition to the coal;
Transporting coal containing the administered first adsorbent to the furnace;
Adding a second adsorbent to the furnace simultaneously with transporting the coal; and burning the coal in the furnace in the presence of the first and second adsorbents to generate thermal energy and ash. And
Here, the first adsorbent comprises a bromine compound, and the second adsorbent is cement kiln dust, less than 0.1% Na ₂ O, less than 0.1% K ₂ O, and 0.5%. Less than chlorine, wherein the proportion is weight based on the total weight of the second adsorbent, compared to coal combustion without the first and second adsorbents, Wherein the mercury emissions are reduced by 40% or more, and NOx emissions from coal combustion facilities are reduced by 20% or more compared to coal combustion without using the first and second adsorbents.   The method of claim 7, wherein the first adsorbent is an aqueous calcium bromide solution.   8. A method according to claim 7, comprising adding calcium bromide in a proportion of 0.001 to 0.5%, based on the amount of coal to be burned.   The method of claim 7, wherein the second adsorbent comprises CKD and ground CKD.   8. The method of claim 7, wherein the second adsorbent comprises one or more of ground CKD, kiln feed, conversion cement, dry clinker, storage CKD, and limestone.   8. The method of claim 7, comprising adding the second adsorbent in a proportion of 0.1 to 10% by weight, based on the coal weight consumed.