KR20100032664A - Apparatus for producing dry sludge for use in thermal power station - Google Patents

Abstract

PURPOSE: An apparatus for producing sludge coal for mixed combustion in a thermal power plant is provided to decompose and dry bound water and capillary water at a low temperature of about 105°C for a short time of about 30 minutes. CONSTITUTION: An apparatus for producing sludge coal for mixed combustion in a thermal power plant includes a microwave dryer. The microwave dryer comprises a wet sludge feed unit(2-1), a discharge unit(2-2), a microwave application unit, an inner container(2-11), and an outer container(2-12). The microwave application unit is attached to the outer container and produces dry sludge coal by applying microwave to wet sludge. A screw blade embedded in the inner container carries the dry sludge coal to the discharge unit while turning the wet sludge at specific speed.

Description

Apparatus for producing dry sludge for use in thermal power station

The present invention relates to an apparatus using microwaves to dry sewage sludge from sewage wet sludge to produce sewage sludge coal for thermal power plant mixed combustion.

Around 80% of global energy demand depends on fossil fuels, and about 50% of fossil fuels depend on coal. In Korea, about 30% of the total electricity production is expected to remain coal.

Environmental problems are with injuries as a major theme of the 21st century, emissions of harmful air pollutants caused by burning of fossil fuels is a problem which the regulation has been gradually strengthened recently been subject to enhanced regulation on SO ₂ and NOx, and CO ₂ Regulations will also take effect from 2013.

Biomass is the third most abundant energy source in the world after coal and oil. It accounts for about 1,250 million TOE, or about 14% of the world's energy.In developing countries, about 35% of the total energy is supplied as biomass, and in developed countries, it is an important energy source. One million TOE, in Europe, varies from country to country, but biomass supplies about 20-40 million TOE. Biomass includes traditional agricultural by-products and energy crops, including sludge and waste, except fossil fuels.

In particular, in the United States, DOE and EPRI were conducted on sewage sludge, which is a domestic waste, and in the sludge mixed combustion study in Europe, it was concluded that it is not only effective for power plants but also environmentally effective when applied to large-scale pulverized coal plants. It became. In Korea, sludge from discharge facilities over a certain scale has been banned from landfill since July 2001. Recently, due to the strengthening of the sludge treatment regulations, the wastes to be disposed of are being recycled as resources using sludge properties that contain a large amount of flammable organic substances, and are also called biosolids instead of sludge. Therefore, the government aims to supply renewable energy, including sewage sludge fueling, in 2011, with 5% of primary energy and 7% of electricity production. Under the agreement ('05 .7.25), the company is investing in renewable energy with a goal of KRW 1.1 trillion by 2008. In particular, power generation companies are planning to build RDF and sewage sludge fuel power plants by 2011, and are conducting joint research with KEPCO to apply coal-fired power plant sites for sewage sludge coal fueling. However, most of organic sludge, mainly sewage and wastewater sludge, generated about 6.5 million tons annually in Korea, has a water content of 70 to 80% and cannot be used as a fuel immediately. As it is about 4,000 kcal / kg, its self-extinction is inferior, and its combustion characteristics are completely different from those of conventional solid fossil fuels. Therefore, in order to use it as a fuel in a combustion furnace that uses an independent fuel and uses existing fossil fuels, it is necessary to reinforce the calorific value and maintain it at 4,500 kcal / kg or more, and correct the combustion characteristics similar to that of bituminous coal or anthracite coal. I need to give.

Table 1 below summarizes the various sewage sludge moisture contents by drying and the applicable aftertreatment processes.

Table 1 Various sewage sludge moisture content by drying and applicable aftertreatment process

Water content Post-processing example 60 to 65% Applicable fluidized bed incinerator 45 to 35% Can be incinerated with general waste 25-15% Incineration molten fuel, cement waste incineration and molten fuel in cement kilns, composting below 10 Coal-fired Power Plant Combustion Fuel

As can be seen from Table 1 above, the water content must be lowered below 10%, especially for fueling sewage sludge coal-fired power plants.

However, the moisture in the sludge is divided into free water, internal water (gap water), surface water, and bonded water as shown in FIG. The major part of the sludge moisture is the free and surface water adhering to the sludge surface. Internal water is the water present between the molecules of the sludge and the bond water is chemically bonded to the sludge molecules. Sewage sludge free water and surface water are dried at 100 ㅁ 5 ℃, but internal and combined water are destroyed and dried at about 400 ℃, so it is difficult to maintain this high temperature up to the inside of the sludge by conventional drying methods.

As described above, in the case of sewage sludge, free water and surface adhesion water outside the sludge solids dried in the range of 105 W5 ° C. exist, whereas pore water chemically bonded inside the sludge solids should be dried for at least 1 hour at a temperature of 400 ° C. or higher. , Capillary water and internal holding water are decomposed and dried. However, there is a problem in that the combustion fuel value decreases due to the devolatilization of volatiles when drying at 400 ° C. or higher, and the consumption of unnecessary calories in the drying process is high.

The present invention is to solve the above problems, an object of the present invention is to use the sewage sludge as a mixed fuel of coal-fired power plants, such as sludge having a moisture content of more than 80% through a microwave heat source 300 ℃ than the conventional 400 ℃ It is to provide a device using microwaves to produce sewage sludge for the combined combustion of coal-fired power plants by drying the sludge coal from the sewage wet sludge, which is dried to a temperature lower than 105 ℃ to meet the conditions as a mixed fuel of the pulverized coal power plant. .

According to the present invention, there is provided an apparatus for producing wet sludge from sludge coal for combined combustion of a thermal power plant. The apparatus includes a wet sludge supply inlet receiving the wet sludge, a discharge section for discharging the dried sludge coal, and microwaves including microwave applying means for generating dry sludge coal by applying microwaves to the wet sludge. And a drying device, wherein the microwave drying device includes a cylindrical inner cylinder having screw blades for sending the dried sludge coal to be discharged while rotating the supplied wet sludge at a predetermined speed, and the microwave in the wet sludge. The outer cylinder is equipped with the microwave application means for applying the, the wet sludge supply inlet is located on one end side of the cylindrical inner cylinder, the discharge portion may be located on the other end side of the inner cylinder opposite.

According to an embodiment of the present invention, a wet sludge conveying conveyor for transferring the wet sludge to the wet sludge supply unit; And a gun sludge coal pulverizer for receiving and crushing the dried gun sludge coal. The apparatus may further include a pulverized sludge coal storage hopper for storing the gun sludge coal transported through the pulverizer for crushing the gun sludge coal.

According to an embodiment of the present invention, the microwave application means includes a magnetron for supplying microwaves to the wet sludge supply inlet and another magnetron on the side of the gun sludge coal discharge, and these magnetrons irradiate each other. The direction can be configured to irradiate half direction about the axis of rotation of the screw vanes.

According to an exemplary embodiment of the present invention, the outer cylinder may be made of a material having a high microwave transmittance resistance, and the inner cylinder may be made of a material having a high microwave transmittance.

According to an embodiment of the present invention, the outer cylinder is made of aluminum, the inner cylinder may be made of Teflon material.

According to an embodiment of the present invention, the screw rotary blade may be made of a material having a high microwave transmittance.

According to an embodiment of the present invention, the screw rotary blade may be made of Teflon material.

According to a preferred embodiment of the present invention, it may further comprise a stainless steel shielded thermocouple thermometer for controlling the microwave output by measuring the temperature in the inner cylinder.

According to a preferred embodiment of the present invention, it may further include an aluminum leakage preventing choke for blocking the external leakage of the microwave irradiated to the inner cylinder.

According to a preferred embodiment of the present invention, the screw rotary blade may be rotated by a motor.

According to a preferred embodiment of the present invention, the wet sludge contains 80% water content, the microwave can be applied for 30 minutes to the temperature of the inner cylinder to 105 ℃.

In the apparatus for producing wet sludge according to the present invention as a sludge coal for combined combustion of a thermal power plant, at least 80% of the wet sludge coal can be utilized for the production of dry sludge coal, which can be utilized for 30 minutes at a low temperature of 105 ° C. Can dry in time.

The present invention for improving the above-mentioned conventional problem solves the conventional problem by applying a microwave heat source in the heat source application technology during extraction is not a direct or indirect heating method such as heating furnace and electric furnace.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Figure 2 shows a schematic diagram of producing sewage sludge coal for thermal power plant mixed combustion as a raw material sewage sludge constructed according to a preferred embodiment of the present invention. As shown in FIG. 2, the apparatus for producing sewage sludge coal for combined combustion of a thermal power plant according to the present invention is a wet sludge conveying conveyor (1), a screw type microwave drying apparatus (2), and a dry sludge coal crushing mill (3). And a pulverized dry sludge coal transport device 4 and a pulverized sludge coal storage hopper 5.

The sludge coal production apparatus of the present invention for drying sewage sludge having a water content of 80% or more, such as sewage sludge coal for thermal combustion-fired mixed combustion having a moisture content of 10% or less, is decomposed and dried at 400 ° C. or higher through the application of a microwave heat source. It is an apparatus adapted to dry hardly decomposable moisture such as pore water, capillary coupling water, internal retention water, and the like at 105 ° C or lower.

As shown in FIG. 2, in the sewage sludge drying through the microwave heat source application, the free water and the surface attachment water outside the sludge solids dried in the range of 105 ㅁ 5 ° C. and the inside of the dried water at 400 ° C. or more are combined. It is characterized in that the pore water, the capillary coupling water, and the internal holding water are made within 105 ° C in a short time. The detailed operation flow is as follows.

In the drying by microwaves according to the present invention, a wet sludge conveying conveyor (1) for supplying wet sewage sludge containing 80% or more of water to a screw type microwave drying device (2) and a screw type microwave drying device (2), The conveyed wet sludge is dried after being discharged to sludge coal of 10% or less of moisture through a drying process by a rotational speed of the screw type microwave drying apparatus 2, and these components may be referred to as sludge drying unit together.

Sewage sludge coal dried and manufactured in the microwave drying device (2) of the sludge drying unit is transferred, and the dry sludge coal crushing mill (3) and the crushed sludge coal for pulverizing into a 200-mesh powder passing through a thermal power plant is a storage hopper. The pulverized dry sludge coal conveying apparatus 4 for conveying to (5) is provided, and these may be called sludge coal processing part.

Next, the microwave drying apparatus 2 is described in more detail in the sludge drying unit.

Microwave is a kind of electromagnetic wave (300MHz ~ 300GHz) which is located between far infrared rays and radio waves (high frequency) in the spectrum. The biggest feature of microwave is that the heating method uses friction force by molecular rotation or rearrangement as much as speed corresponding to the frequency of electromagnetic wave, so that the temperature can be raised faster than conventional thermal conductive heating. In addition, microwave energy has low energy that does not damage chemical bonds, and thus does not alter or destroy molecular structure. Because of the rapid temperature rise and chemical stability, microwave technology has already been applied in various chemical fields. In addition, the principle of the microwave is a material having a low dielectric constant (permeability) transmits microwaves, but in the case of the combined moisture such as water, a polar solvent having high transmittance, it is used as a heating source. On the other hand, materials such as sludge organic materials have the property of transmitting microwaves. Therefore, in the case of microwave drying equipment, the material properties and the physicochemical properties of the sludge to be dried should be considered.

3 is a side sectional view of a microwave drying apparatus 2 which is a main component of the present invention. In the microwave drying apparatus 2, a cavity 2-6 is installed to protect the magnetrons 2-7 and 2-8 that supply microwaves, and wet sludge is supplied into the microwave drying apparatus 2. The moist sludge supply inlet 2-1 is provided.

The injected wet sludge is provided with a rotary motor 2-5 to give a rotational force to move through the screw blades 2-3 and to adjust the residence time in the microwave drying apparatus 2. In FIG. 3, reference numerals 2-4 denote rotation axes. That is, the injected wet sludge is arranged so that a plurality of screw blades are successively arranged at regular intervals in a rotational axis direction in the cylindrical inner cylinder to rotate, so that the sludge supplied from the upstream side of the inner cylinder is directed toward the discharge portion downstream of the inner cylinder.

A discharge part 2-2 is provided to discharge the dried sludge coal to the bottom. In addition, the wet sludge supply input part 2-1 and the gun sludge coal discharge part 2-2 are leak-proof chokes made of aluminum to block external leakage of microwaves irradiated therein (2-9, 2-10). Are respectively provided.

Material of screw blade (2-3) to be absorbed by moist sludge through Teflon inner cylinder (2-11) and Teflon inner cylinder (2-11) of low permittivity for the purpose of permeation of supplied microwave Also referred to as Teflon, the rotation shaft (2-4) is based on a stainless material that reflects microwaves.

Also provided is a stainless steel shielded thermocouple thermometer 2-13 as a temperature sensor which measures the temperature inside the screw-type microwave drying apparatus 2 and controls the microwave output.

The outer cylinder (2-12) of the screw-type microwave drying apparatus, which is the main part of the present invention, is made of an aluminum material having a high microwave transmission resistance to block external leakage of microwaves.

The inner cylinder 2-11 of the screw type microwave drying device 2 is preferably made of Teflon material having a high microwave transmittance to smoothly penetrate the inside of the microwave and prevent erosion of the reactor.

4 is a cross-sectional view of the screw-type microwave drying apparatus 2 shown in side cross-sectional view in FIG. 3. As shown in Fig. 4, a magnetron 2-7 for supplying microwaves to the wet sludge supply inlet 2-1 and another magnetron 2-8 on the side of the dry sludge coal discharge unit 2-2. As shown by the arrow in FIG. 4, it is comprised so that irradiation direction may mutually irradiate the half direction about the rotating shaft 2-4. Specifically, the wet sludge supply inlet 2-1 is located on one end side of the cylindrical inner cylinder, and the dry sludge coal discharge part 2-2 is located on the other opposite side of the inner cylinder.

The microwaves are irradiated to the inner cylinder (2-11), the wet sludge absorbs the microwaves, is thermally decomposed through molecular rotation of water molecules, and the microwaves passing through the wet sludge are reflected and refracted by the aluminum outer cylinder (2-12). It is configured to irradiate wet sludge on the opposite side, and the magnetron (2-7) on the inlet side and the magnetron (2-8) on the outlet side are installed on the opposite side for protecting the magnetron and uniform irradiation. Configure the installation location.

According to the present invention, an experimental example of a device using microwaves for drying sewage sludge from sewage wet sludge to produce sewage sludge for coal-fired power plants is described below.

The following specific numerical values are examples and the present invention is not limited to these numerical values, and it should be noted that various values may be selected by those skilled in the art according to design.

The micronetron for supplying microwaves is 2.45GHz, 2kW, 220V, single phase, and the volume of the microwave drying device 2 is 2ℓ. The inner cylinder diameter is 30cm, the outer cylinder diameter is 40cm and the length is 80cm. Rotational speed of 1 ~ 5rpm, thermometer (2-13) using a stainless steel shielded thermocouple, wet sludge raw material feed inlet (2-1) and outlet (2-2) diameter of 2 inches, The diameter of the installation portion of the thermometer (2-13) was composed of 1cm, the shape and configuration of the equipment was as shown in FIG. Experimental conditions and results are as follows.

Experimental condition:

The wet sewage sludge used in the experiment is shown in Table 2 below.

Table 2. Characteristics of Wet Sewage Sludge

Kinds Calorie (Kcal / Kg) V.M. (%) F.C (%) Ash (%) Water (%) Remarks Daejeon Sewage Sludge 3,660 10.85 2.02 7.14 79.99

☞ Calorific Value: Dry base

In case of sewage sludge, the moisture content is about 79.99 (about 80)%, and the heat content is dry base 3,660Kcal / kg, which is similar to anthracite coal. Could confirm. On the other hand, the experimental conditions were 15 kg / hr of charged sewage sludge with a water content of about 80%, and microwave heat source drying reaction was performed for 30 minutes at 105 ° C.

Experiment result:

As a result of drying sewage sludge using microwave heat source, the water content is very low below 8% as shown in the following Table 3, and the calorific value is 4,450Kcal / kg, which is much higher than raw sewage sludge.

Table 3. Dry sewage sludge coal properties

Kinds Calorie (Kcal / Kg) V.M. (%) F.C (%) Ash (%) Water (%) Remarks Dry sewage sludge 4,450 49.95 9.31 32.90 7.84

The dry sewage sludge coal thus obtained was found to be suitable as a mixed fuel for coal-fired power plants as follows.

Figure 5 (a) is a SEM photograph of the sewage sludge coal, Figure 5 (b) shows the XRD analysis results. As can be seen from the figure, sewage sludge coal appeared to be composed of amorphous (Amorphous Phase) fixed carbon as the main component, and the crystalline form showed the aggregated particles.

On the other hand, in the case of metal materials, as shown in FIG. 6 showing the results of EDS analysis of sewage sludge coal, coal ash components of various minerals (Si, Al, Mg, Na, Fe, etc.) in addition to the fixed carbon in the crystal phase are used as It was confirmed that it is the same as the constitution and confirmed that it is suitable as a mixed fuel of coal-fired power plant.

In addition, as shown in Figure 7 showing the heat loss curve experiment results of sewage sludge coal, as a result of the heat loss curve analysis of sewage sludge coal, the dehydration of free moisture is made within the range of 10% around 90 ℃ similar to bituminous coal, The devolatilization reaction occurs with a loss of 35% in the temperature range of 220-400 ℃ and the complete combustion reaction of fixed carbon in the range of 420-500 ℃, which is the same tendency as the bituminous coal or anthracite in terms of combustion kinetics.

In microwave drying equipment, Teflon material with low permittivity is transmitted through microwave drying device, and sewage sludge is composed of high polar solvent absorbing microwaves, pore water, combined moisture, and internal holding water. Due to exothermic reaction in the water itself, it is possible to decompose and dry the combined water and the capillary bound water even at a low temperature below 105 ° C. According to the present invention, in preparing dry sludge coal, which can utilize wet sewage sludge, 105 ° C. It can be dried in a short time at a low temperature of about 30 minutes.

1 is a view showing a water bond form of sewage sludge.

Figure 2 is a schematic system diagram for producing sewage sludge coal for thermal power plant mixed combustion as a raw material sewage sludge constructed in accordance with a preferred embodiment of the present invention.

Figure 3 is a side cross-sectional view of a microwave drying apparatus as a main component of the present invention.

4 is a cross-sectional view of the screw-type microwave drying device shown in side cross-sectional view in FIG.

Figure 5 (a) is a SEM photograph of the sewage sludge coal, Figure 5 (b) is a view showing the XRD analysis results.

6 is a view showing an EDS analysis result of sewage sludge coal.

Figure 7 shows the heat loss curve test results of sewage sludge coal.

-Explanation of the symbols for the main parts of the drawings-

One; Conveyor 2 for wet sludge transport; microwave drying device

3; Grinder 4 for dry sludge coal grinding; Grinding Dry Sludge Coal Feeder

5; Storage hopper 2-1; wet sludge feed input

2-2; Outlet 2-3; Screw wing

2-4; 2-5; Rotary motor

2-6; Pupils 2-7, 2-8; magnetron

2-9, 2-10; Leak-proof choke 2-11; Inner tube

2-12; External

Claims (11)

Apparatus for producing wet sludge from sludge coal for combined combustion of a thermal power plant, A microwave drying apparatus including a wet sludge supply inlet receiving the wet sludge and an outlet for discharging the dried sludge coal, and microwave applying means for generating dry sludge coal by applying microwaves to the wet sludge; Including, The microwave drying apparatus includes a cylindrical inner cylinder having a screw blade configured to send dry sludge coal to be dried while rotating the supplied wet sludge at a predetermined speed, and the microwave for applying microwaves to the wet sludge. Sludge for thermal power plant mixing and combustion, having an outer cylinder equipped with an application means, wherein the wet sludge supply inlet is located on one end side of the cylindrical inner cylinder, and the discharge part is located on the other end side of the inner cylinder. Shot manufacturing equipment. The method of claim 1, further comprising: a wet sludge conveying conveyor for transferring the wet sludge to the wet sludge supply inlet; And A gun sludge coal mill for crushing the dried gun sludge coal; Further comprising a pulverized sludge coal storage hopper for storing the gun sludge coal transported through the gun sludge coal crushing mill, apparatus for producing combustion sludge coal for thermal power plant. The method according to claim 1, wherein the microwave application means includes a magnetron for supplying microwaves to the wet sludge supply inlet and another magnetron on the side of the gun sludge coal discharge, and these magnetrons are screw vanes of each other in the irradiation direction. The apparatus for producing sludge coal for combined combustion of a thermal power plant, configured to irradiate half direction about a rotation axis of the thermal power plant. The apparatus of claim 1, wherein the outer cylinder is made of a material having a high microwave transmittance resistance, and the inner cylinder is made of a material having a high microwave transmittance. The apparatus of claim 4, wherein the outer cylinder is made of aluminum and the inner cylinder is made of Teflon. The apparatus of claim 1, wherein the screw rotary blade is made of a material having a high microwave transmittance. The apparatus of claim 6, wherein the screw rotary blade is made of Teflon material. The apparatus of claim 1, further comprising a stainless steel shielded thermocouple thermometer for controlling the microwave output by measuring the temperature in the inner cylinder. The apparatus of claim 1, further comprising an aluminum leakage preventing choke for blocking external leakage of microwaves irradiated to the inner cylinder. The apparatus of claim 1, wherein the screw rotary blade is rotated by a motor. The apparatus of claim 1, wherein the moist sludge contains 80% of water and is subjected to microwaves for 30 minutes so that the temperature of the inner cylinder is 105 ° C.

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