Exhaust gas treatment device and exhaust gas treatment method
By adding coal combustion ash as an adsorbent to the combustion gas process, the problems of easy oxidation of PPS filter cloth and difficulty in injecting activated carbon in the existing technology are solved, achieving low-cost and high-efficiency NO2 removal.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SUMITOMO HEAVY IND LTD
- Filing Date
- 2019-07-25
- Publication Date
- 2026-05-20
AI Technical Summary
In existing technologies, filter cloths made of sulfur-based materials such as PPS are prone to oxidation and degradation when treating combustion gases containing NO2. Activated carbon is expensive and difficult to inject into CFB boilers, while zeolite is expensive and requires complex equipment, making it difficult to remove NO2 economically and effectively.
By adding coal combustion ash as an adsorbent to the combustion gas process, it reacts with NO2 at high temperature to reduce the NO2 concentration. The coal combustion ash can be directly recovered from the PC boiler without additional treatment after being filtered by PPS filter cloth.
It achieves low-cost and efficient removal of NO2 in existing equipment, reduces the oxidative degradation of PPS filter cloth, and lowers operating costs and equipment investment.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to an exhaust gas treatment apparatus and an exhaust gas treatment method capable of reforming combustion gases generated in a combustion furnace. [Background technology]
[0002] In recent years, in order to secure fuel, there has been a growing demand for power generation using construction waste wood materials, biomass fuels other than wood materials, and waste fuels such as waste tires and waste plastics. One example of such power generation mechanisms is a boiler that is connected to a combustion furnace that burns the material to be combusted and generates saturated steam, and uses the combustion gas generated in the combustion furnace to superheat the saturated steam produced in the combustion furnace and use it to drive a turbine for power generation. Another example of such technology is a circulating fluidized bed boiler (hereinafter sometimes referred to as a "CFB boiler") equipped with a fluidized bed.
[0003] In boiler-based equipment, filtration methods (dust collection methods) such as bag filters are used to remove harmful substances from the combustion gas when it is discharged outside the equipment. Regarding bag filters, for example, techniques have been proposed to form a filtration chamber on the surface of the bag filter using zeolite or the like to collect dust, and techniques to provide a duct section with a constricted section so that the dust in the exhaust gas and the adsorbent are uniformly mixed (see, for example, Patent Documents 1 and 2 below). [Prior art documents] [Patent Documents]
[0004] [Patent Document 1] Japanese Patent Application Publication No. 06-343821 [Patent Document 2] Japanese Patent Publication No. 2000-262842 [Overview of the project] [Problems that the invention aims to solve]
[0005] Bag filters are equipped with a "filter cloth" for dust collection, and such filter cloths are often made of materials such as polyphenylene sulfide resin (hereinafter sometimes referred to as "PPS") or polytetrafluoroethylene (PTFE).
[0006] On the other hand, when biomass fuel is burned, NO x It is known that this is prone to occurring. In particular, combustion gases from biomass fuels contain a large amount of NO2. However, sulfur-based materials such as PPS are known as suitable materials for filter cloths in terms of the balance between running costs and performance. However, when NO2 is present in the combustion gas, sulfur-based materials such as PPS tend to oxidize and degrade easily, so various methods are employed to remove NO2 from the combustion gas. For example, to remove NO2 from the combustion gas, techniques for adding activated carbon or zeolite to the combustion gas are known. However, activated carbon is highly flammable, and it is difficult to inject activated carbon into the combustion gas in the process from the combustion furnace to the bag filter in a CFB boiler. In addition, zeolite requires costs for its manufacture and procurement, as well as the cost of equipment to supply it to the combustion furnace.
[0007] The present invention aims to solve the above-mentioned problems by providing an exhaust gas treatment device and an exhaust gas treatment method that can be easily installed in existing equipment and can purify combustion gases at low cost. [Means for solving the problem]
[0008] In other words, the present invention is as follows: <1> An exhaust gas treatment device for reforming combustion gas produced in a combustion furnace that exclusively burns biomass fuel, comprising a particle supply device for supplying coal combustion ash into the combustion gas. <2> The temperature of the combustion gas is over 600°C. <1> Exhaust gas treatment device as described above. <3> The particle supply device supplies the coal combustion ash into the combustion furnace. <1> or <2> Exhaust gas treatment device as described above. <4> The particle supply device supplies the coal combustion ash into the combustion gas in the combustion gas flow path downstream of the combustion furnace. <1> ~the aforementioned <3> An exhaust gas treatment device as described in any one of the following. <5> A bag filter is provided downstream of the combustion furnace, and the particle supply device supplies the coal combustion ash into the combustion gas upstream of the bag filter. <1> ~the aforementioned <4> An exhaust gas treatment device as described in any one of the following. <6> The bag filter comprises a filter cloth made of polyphenylene sulfide resin. <5> Exhaust gas treatment device as described above. <7> An exhaust gas treatment method for reforming combustion gas produced in a combustion furnace that exclusively burns biomass fuel, the method comprising the step of supplying coal combustion ash to the combustion gas. <8> The temperature of the combustion gas is over 600°C. <7> The exhaust gas treatment method described above. <9> The coal combustion ash is supplied into the combustion furnace. <7> or the above <8> The exhaust gas treatment method described above. <10> The coal combustion ash is supplied into the combustion gas downstream of the combustion furnace. <7> ~the aforementioned <9> The exhaust gas treatment method described in any one of the following. <11> A bag filter is provided downstream of the combustion furnace, and the coal combustion ash is supplied to the combustion gas upstream of the bag filter. <7> ~the aforementioned <10> The exhaust gas treatment method described in any one of the following. <12> The bag filter comprises a filter cloth made of polyphenylene sulfide resin. <11> The exhaust gas treatment method described above. [Effects of the Invention]
[0009] According to the present invention, it is possible to provide an exhaust gas treatment device and an exhaust gas treatment method that can be easily installed in existing facilities and can purify combustion gases at low cost. [Brief explanation of the drawing]
[0010] [Figure 1] This is a schematic diagram showing a combustion equipment according to the first embodiment of the present invention. [Figure 2] It is a schematic diagram showing the combustion equipment of the second embodiment of the present invention. [Figure 3] It is a graph showing the relationship between the temperature of the combustion gas into which coal combustion ash is introduced and the NO2 removal rate.
Embodiments for Carrying Out the Invention
[0011] Hereinafter, with reference to the drawings, embodiments for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. However, the following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of its gist. The same elements are denoted by the same reference numerals, and overlapping descriptions are omitted. Also, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios.
[0012] (First Embodiment) The combustion equipment provided with the exhaust gas treatment device of the first embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing the combustion equipment of the first embodiment of the present invention.
[0013] As shown in FIG. 1, the combustion equipment 10 includes a combustion furnace 20 to which biomass fuel as a combustion target is supplied and the biomass fuel is solely burned in the furnace, and a heat recovery unit 30 that recovers the heat of the combustion gas generated in the combustion furnace 20. Further, the combustion equipment 10 includes a bag filter 40 downstream of the combustion furnace 20 and the heat recovery unit 30 to remove harmful substances in the combustion gas discharged from the heat recovery unit 30. In addition, a biomass fuel feeder 22 for supplying biomass fuel into the furnace and a particle supply device 50 for supplying coal combustion ash into the combustion gas are installed in the combustion furnace 20. In the present embodiment, the particle supply device 50 serves as an exhaust gas treatment device. In FIG. 1, the thick arrow indicates the flow direction of the combustion gas.
[0014] The combustion equipment 10 is not particularly limited, but a so-called boiler that superheats steam by heat exchange between the combustion gas generated in the combustion furnace 20 and heat exchangers such as superheaters and economizers installed in the heat recovery section 30 and uses it for power generation can be cited as an example. Further, the combustion equipment 10 is not particularly limited, but in addition to once-through boilers, circulating boilers, and waste heat recovery boilers mainly used for thermal power generation business, circulating fluidized bed boilers (CFB), bubbling fluidized bed boilers (BFB), etc. used industrially may be used.
[0015] As shown in FIG. 1, the combustion furnace 20 is, for example, configured in a vertically long cylindrical shape, and burns the biomass fuel supplied from the biomass fuel feeder 22 in the furnace.
[0016] When the biomass fuel supplied from the biomass fuel feeder 22 to the combustion furnace 20 is burned, combustion gas is generated in the furnace. Although not shown, water pipes can be installed on the furnace wall of the combustion furnace 20, and saturated steam can be generated by exposing the water pipes to the combustion gas in the combustion furnace 20. The combustion gas contains NOx (nitrogen oxides) such as NO and NO2 generated by the combustion of biomass fuel. The combustion gas also contains low-melting-point molten salts such as KCl and NaCl generated by the combustion of biomass fuel and solid particles such as ash generated by combustion. The furnace temperature is not particularly limited, but is approximately 800 to 1000 °C. The combustion gas generated in the combustion furnace 20 is supplied to the heat recovery section 30 while containing these nitrogen oxides, molten salts, and ash. X The combustion gas contains NOx (nitrogen oxides) such as NO and NO2 generated by the combustion of biomass fuel. The combustion gas also contains low-melting-point molten salts such as KCl and NaCl generated by the combustion of biomass fuel and solid particles such as ash generated by combustion. The furnace temperature is not particularly limited, but is approximately 800 to 1000 °C. The combustion gas generated in the combustion furnace 20 is supplied to the heat recovery section 30 while containing these nitrogen oxides, molten salts, and ash.
[0017] As shown in Figure 1, the combustion equipment 10 is equipped with a particle supply device 50 that supplies coal combustion ash into the combustion gas. When coal combustion ash is introduced into the combustion gas, it can reduce the NOx (especially NO2) concentration in the combustion gas. There are no particular limitations on how the coal combustion ash can be obtained, but for example, clinker ash (bottom ash, furnace bottom ash), fly ash, etc., generated from pulverized coal boilers (PC boilers) or other boilers (e.g., fluidized bed boilers, etc.) can be used. Ash recovered from PC boilers is sometimes called PC ash. The coal combustion ash used in this embodiment can be used as is, without any special pretreatment, from coal combustion ash recovered as waste from PC boilers, etc., outside the system.
[0018] While there are no particular limitations on the type of coal combustion ash, it is preferable that its melting point is higher than the temperature of the supplied combustion gas, for example, higher than 800-1000°C. Furthermore, the coal combustion ash is preferably composed of particles with an average particle size of 10 to 20 μm.
[0019] Furthermore, coal combustion ash is less combustible than activated carbon. For this reason, the combustion equipment 10 can be configured to introduce the ash into the combustion gas at any stage in the process from the combustion furnace 20 to the bag filter 40. For example, although Figure 1 shows that the combustion furnace 20 is equipped with a particle supply device 50, the installation location and number of such devices are not limited to this, and they may be installed in any location, such as the combustion gas flow path (flue) connecting the combustion furnace 20 and the heat recovery unit 30, a device such as a cyclone (indicated by arrow A in Figure 1), the heat recovery unit 30 (for example, indicated by arrow B in Figure 1), and the flue connecting the heat recovery unit 30 and the bag filter 40 (for example, indicated by arrow C in Figure 1). Note that when coal combustion ash is introduced into combustion gas at over 600°C, the effect of reducing the NOx (especially NO2) concentration of the coal combustion ash (purification effect) is improved. From this viewpoint, although not particularly limited, it is preferable that the coal combustion ash be introduced into a part of the combustion equipment 10 where the temperature of the combustion gas exceeds 600°C (preferably 610 to 900°C, more preferably 650 to 900°C). Furthermore, as in this embodiment, it is preferable that the particle supply device 50 be installed upstream of the bag filter 40 (especially a bag filter equipped with a PPS filter cloth).
[0020] Furthermore, since there are no particular restrictions on the means and conditions for introducing coal combustion ash, there is no need to install new special equipment to introduce coal combustion ash. For this reason, for example, in existing equipment, a particle supply device 50 can be installed so that coal combustion ash can be supplied from a supply port in the combustion furnace 20 that supplies sand and additives.
[0021] Furthermore, the particle supply device 50 can be electrically coupled to a control unit (not shown) to control the timing and amount of coal combustion ash supplied.
[0022] The heat recovery unit 30 is supplied with combustion gas discharged from the combustion furnace 20. A flue is provided within the heat recovery unit 30, which serves as a flow path for the combustion gas, and the heat recovery unit 30 is configured to recover heat from the combustion gas passing through the flue. A superheater, economizer, gas air heater, etc., can be installed in the flue, and steam pipes (not shown in the figure) are installed in these superheaters and economizers. Saturated steam generated by the heat of the combustion furnace 20 flows through the steam pipes, and the saturated steam is superheated by heat exchange between the combustion gas passing through the flue and the superheater, etc. The combustion gas discharged from the heat recovery unit 30 is discharged to a bag filter 40 installed downstream of the heat recovery unit 30. The saturated steam superheated by the heat recovery unit 30 can be used, for example, to drive a power generation turbine.
[0023] The bag filter 40 is a device that collects and purifies molten salts, solid particles, and other contaminants in the combustion gas before discharging it outside the combustion equipment 10. A filter cloth is installed inside the bag filter 40 as a dust collection means. As mentioned above, filter cloths made of PSS or PTFE can be used, but from the viewpoint of balancing running costs and performance, it is preferable to use a filter cloth made of sulfur-based material such as PSS. Known materials can be appropriately selected and used as the bag filter and filter cloth.
[0024] The combustion gases discharged from the bag filter are sent to downstream equipment as exhaust gases as needed, and then discharged outside the facility.
[0025] As described above, in this embodiment, biomass fuel is burned in a combustion furnace 20 exclusively for burning biomass fuel, and coal combustion ash is supplied to the combustion gas produced by the combustion of the biomass fuel, thereby reforming the combustion gas (NOx). x This allows for a reduction in concentration and purification of combustion gases. Furthermore, the coal combustion ash used in this embodiment can be used directly from waste materials recovered from PC boilers, etc., without any special pretreatment. Therefore, raw material costs can be kept low. Furthermore, as described above, there are no particular restrictions on the means and conditions for introducing coal combustion ash in this embodiment. For example, the particle supply device 50 can be installed using the supply ports already installed in existing equipment. Therefore, there is no need to install new special equipment, and equipment costs (e.g., initial installation costs) can be kept low.
[0026] In this embodiment, the system can be configured to supply coal combustion ash to a combustion gas at a temperature exceeding 600°C. When the temperature of the combustion gas to which the coal combustion ash is supplied exceeds 600°C, the amount of NO produced by the coal combustion ash is higher compared to when the coal combustion ash is supplied to a combustion gas at a temperature of 600°C or lower. x The removal effect can be improved. Furthermore, when the particle supply device 50 is installed to supply coal combustion ash into the combustion furnace 20, the combustion gas temperature inside the combustion furnace 20 is normally over 600°C, so there is no need to introduce special equipment to raise the combustion gas temperature above 600°C. For this reason, the combustion equipment 10 can effectively improve the effect of reducing NOx concentration by coal combustion ash.
[0027] Furthermore, although Figure 1 shows coal combustion ash being supplied into the combustion furnace 20, this embodiment is not limited to this configuration. As described above, the particle supply device 50 may be installed in place of or in addition to the combustion furnace 20, in a location other than the combustion furnace 20 (a combustion gas flow path downstream of the combustion furnace), to supply coal combustion ash into the combustion gas. For example, if the particle supply device 50 is installed to supply coal combustion ash to the combustion gas flow path (indicated by arrows A to C in Figure 1) from the combustion gas discharged from the combustion furnace 20 to the bag filter, coal combustion ash can be supplied to the combustion gas without hindering the combustion of biomass fuel in the combustion furnace 20. Also, in locations other than the combustion furnace 20, the pressure in the combustion gas flow path is lower than in the furnace, so coal combustion ash can be supplied to the combustion gas more easily than when it is introduced into the combustion furnace 20.
[0028] In this embodiment, a bag filter 40 is provided downstream of the combustion furnace 20. In this embodiment, a particle supply device 50 is installed to supply coal fuel into the combustion gas in the combustion gas flow path upstream of the bag filter 40. Therefore, since the NOx concentration in the combustion gas supplied to the bag filter 40 is sufficiently reduced by coal combustion ash, a filter cloth made of PPS (polyphenylene sulfide resin), which is susceptible to oxidative degradation by NO2 in the combustion gas, can be used in the bag filter 40. Sulfur-based materials such as PPS offer an excellent balance between running costs and performance among filter cloth materials. For this reason, by using a PPS filter cloth in the bag filter 40, the running costs of the combustion equipment 10 can be reduced while maintaining exhaust gas purification performance.
[0029] (Second Embodiment) A combustion system equipped with an exhaust gas treatment device according to the second embodiment will be described with reference to Figure 2. Figure 2 is a schematic diagram showing a combustion system according to the second embodiment of the present invention. In this embodiment, a combustion system equipped with a circulating fluidized bed boiler (CFB) as the combustion furnace will be described as an example.
[0030] As shown in Figure 2, the combustion equipment 100 includes a combustion furnace 120 that is supplied with biomass fuel and exclusively burns the biomass fuel inside the furnace, a cyclone 125 that separates solids from the combustion gas produced by burning the biomass fuel, and a heat recovery unit 130 that recovers heat from the combustion gas. Furthermore, the combustion equipment 100 is equipped with a bag filter 140 downstream of the combustion furnace 120 and the heat recovery unit 130 to remove harmful substances from the combustion gas discharged from the heat recovery unit 130. The combustion furnace 120 is also equipped with a fuel supply unit 122 that supplies biomass fuel into the furnace and a particle supply unit 150 that supplies coal combustion ash into the furnace. In this embodiment, the particle supply unit 150 acts as an exhaust gas treatment device.
[0031] The combustion furnace 120 is configured as a vertically elongated cylindrical shape and burns biomass fuel supplied from the fuel supply unit 122 inside the furnace. The combustion furnace 120 is a fluidized bed furnace that burns biomass fuel while it is fluidized in a fluidized bed 120A. Furthermore, as will be described later, the combustion furnace 120 is a circulating fluidized bed furnace in which solid matter of a predetermined particle size or larger is returned by a cyclone 125. The temperature inside the combustion furnace 120 is not particularly limited, but the temperature of the combustion gas can be set to approximately 800 to 1000°C.
[0032] When the biomass fuel supplied from the fuel supplier 122 to the combustion furnace 120 is burned, combustion gas is generated. As described above, the combustion gas contains low-melting-point molten salt and solid particles such as ash produced by combustion, and the combustion gas generated in the combustion furnace 120 is sent to the cyclone 125 while still containing these molten salts and ash.
[0033] As shown in Figure 2, the combustion furnace 120 is equipped with a particle supply device 150 that supplies coal combustion ash into the combustion gas. As the coal combustion ash, PC ash recovered from an external PC boiler can be used. In this embodiment, the particle supply device 150 is installed to supply coal combustion ash from the same supply port used to supply sand and additives used in the fluidized bed 120A. Furthermore, the particle supply device 150 is electrically coupled to a control unit (not shown) to control the timing and amount of coal combustion ash supply. The supply of coal combustion ash reduces NO in the combustion gas. x The concentration is reduced.
[0034] Cyclone 125 is a solid-gas separation device that separates solid particles larger than a predetermined particle size discharged from the combustion furnace 120 from the combustion gas and returns them to the combustion furnace 120. Cyclone 125 separates solid particles larger than a predetermined particle size from the combustion gas and returns them to the combustion furnace 120, and also sends the combustion gas from which these solid particles have been separated to the downstream heat recovery unit 130. The particle size of the solid particles separated by Cyclone 125 is not particularly limited, but can be set to, for example, about 20 μm. The coal combustion ash supplied into the combustion furnace 120 by the particle supply device 150 is discharged together with the combustion gas to the heat recovery unit 130 located downstream.
[0035] As described above, the combustion gas discharged from the cyclone 125 is sent to the heat recovery unit 130. Similar to the first embodiment, the heat recovery unit 130 is equipped with a flue (not shown) that serves as a flow path for the combustion gas, as well as a superheater, economizer, gas air heater, etc., and is configured to recover heat from the combustion gas passing through the flue. Similarly, steam pipes (not shown) are installed in the superheater and economizer. Saturated steam generated by the heat of the combustion furnace 120 flows through the steam pipes, and the saturated steam is superheated through heat exchange between the combustion gas and the superheater, etc. The combustion gas discharged from the heat recovery unit 130 is discharged to a bag filter 140 located downstream of the heat recovery unit 130. The saturated steam superheated by the heat recovery unit 130 can be used, for example, to drive a power generation turbine.
[0036] The bag filter 140 is a device that collects and purifies molten salts, solid particles, and other contaminants in the combustion gas before discharging it outside the combustion equipment 100. A filter cloth made of PSS is installed inside the bag filter 40 as a dust collection means. In this embodiment, the NOx concentration in the combustion gas supplied to the bag filter 140 is sufficiently reduced, so the oxidative degradation of the PPS filter cloth can be suppressed.
[0037] The combustion gases discharged from the bag filter are sent to downstream equipment as exhaust gases as needed, and then discharged outside the facility.
[0038] As described above, in this embodiment, biomass fuel is burned in a combustion furnace 120 dedicated to burning biomass fuel, and coal combustion ash is supplied to the combustion gas produced by the combustion of the biomass fuel, thereby reforming the combustion gas (NOx). xThe concentration can be reduced, and the combustion gas can be purified. Furthermore, the coal combustion ash used in this embodiment can be used as is, recovered as waste from PC boilers, etc., without any special pretreatment, thus keeping raw material costs low. Moreover, the combustion furnace in this embodiment is a circulating fluidized bed boiler, and the exhaust gas treatment device (particle supply device 150) of this embodiment is installed so that coal combustion ash can be supplied to the supply port to which sand and additives used in the fluidized bed 120A are supplied. For this reason, there is no need to install any new special equipment, and equipment costs can be kept low.
[0039] Furthermore, in this embodiment, coal combustion ash is supplied to the combustion furnace 120 where the combustion gas temperature exceeds 600°C, which is particularly effective in reducing NOx concentration. In addition, this embodiment is equipped with a bag filter 140 made of PPS filter cloth. Since the NOx concentration of the combustion gas supplied to the bag filter 140 is sufficiently reduced by the coal combustion ash supplied to the combustion furnace 120, in this embodiment, the PPS filter cloth is less susceptible to oxidative degradation, resulting in excellent running costs for the combustion equipment 10.
[0040] In this embodiment, a particle supply device 150 is installed so that coal combustion ash can be supplied into the combustion furnace 120 from a supply port through which sand and additives used in the fluidized bed 120A are supplied. However, as described above, the supply location of coal combustion ash is not limited to this location. For example, a new supply port may be provided in the connection part (flue) between the cyclone 125 and the combustion furnace 120, and coal combustion ash may be supplied from this supply port. Alternatively, a supply port may be provided in the cyclone 125, the heat recovery unit 130, or the connection part between these devices, and the particle supply device 150 may be installed to supply coal combustion ash from this supply port.
[0041] The embodiments of the invention described above can be used in appropriate combinations, modifications, or improvements depending on the application. Furthermore, the present invention is not limited to the embodiments described above. [Examples]
[0042] Hereinafter, the cleaning effect (NOx concentration reduction effect) of the present invention will be described using examples. However, the aspects of the present invention are not limited to the following examples.
[0043] A combustion experiment of biomass fuel was conducted on a CFB boiler prototype, and the concentrations of NO, NO, and NO2 in the combustion gas were measured when coal combustion ash was added / not added. The measured values are shown in the following table. PKS (imported coconut shells) was used as the biomass fuel, and PC ash recovered from a PC boiler was used as the coal combustion ash. The coal combustion ash was added so as to be 2 g / m with respect to the combustion gas. Also, the temperature of the combustion gas was 160°C. As shown in the following table, when coal combustion ash was added, it can be seen that NO2 in NO decreased compared to the case where no coal combustion ash was added. x 、NO、NO2の濃度を測定した。下記表に測定値を示す。バイオマス燃料としてはPKS(輸入ヤシ殻)を用い、石炭燃焼灰としてはPCボイラーから回収したPC灰を用いた。石炭燃焼灰は、燃焼ガスに対して2g / m 3 となるように投入した。また、燃焼ガスの温度は160℃であった。下記表に示すように、石炭燃焼灰を投入した際には、石炭燃焼灰を投入しない場合に比べて、NO X 中のNO2が減少していることがわかる。
[0044]
Table 1
[0045] In addition, the relationship between the temperature of the combustion gas to which coal combustion ash is added and the NO2 removal rate is shown in FIG. 3. In FIG. 3, the NO2 removal rates when 50 g of PC ash is supplied into the combustion gas in the furnace for each of the furnaces with furnace temperatures of 149°C, 610°C, and 850°C are shown. The NO2 removal rate was calculated taking into account the NO2 removal rate when no PC ash was supplied, which was calculated from the results of the blank experiment. As a result, the NO2 removal rate was 40% at a furnace temperature of 149°C, 42% at a furnace temperature of 610°C, and 91% at a furnace temperature of 850°C. In this test, the furnace temperature can be regarded as the temperature of the combustion gas. As shown in FIG. 3, it can be seen that the NO2 removal rate of the sample with a furnace temperature of 850°C is significantly improved compared to the samples with a furnace temperature of 600°C or lower.
Explanation of symbols
[0046] 10,100... Combustion equipment, 20,120... Combustion furnace, 22,122... Biomass fuel supply unit, 30,130... Heat recovery unit, 40,140... Bag filter, 50,150... Particle supply unit, 125... Cyclone
Claims
1. An exhaust gas treatment device for reforming combustion gases produced in a combustion furnace that exclusively burns biomass fuel, The system includes a particle supply device that supplies coal combustion ash into the combustion gas, The temperature of the combustion gas to which the coal combustion ash is supplied is between 610°C and 900°C. The particle supply device is provided in the combustion gas flow path downstream of the combustion furnace, and supplies the coal combustion ash into the combustion gas downstream of the combustion furnace, and A bag filter is provided downstream of the combustion furnace, and the particle supply device supplies the coal combustion ash into the combustion gas upstream of the bag filter. An exhaust gas treatment device that modifies the aforementioned combustion gas to suppress oxidative degradation of sulfur-based materials.
2. The exhaust gas treatment apparatus according to claim 1, wherein the bag filter comprises a filter cloth made of polyphenylene sulfide resin.
3. A method for treating exhaust gases that are modified from combustion gases produced in a combustion furnace that exclusively burns biomass fuel, The process includes supplying coal combustion ash into the combustion gas, The temperature of the combustion gas to which the coal combustion ash is supplied is above 610°C and below 900°C. The aforementioned coal combustion ash is supplied into the combustion gas downstream of the combustion furnace, and A bag filter is provided downstream of the combustion furnace, and the coal combustion ash is supplied to the combustion gas upstream of the bag filter. An exhaust gas treatment method for suppressing oxidative degradation of sulfur-based materials by modifying the aforementioned combustion gas.
4. The exhaust gas treatment method according to claim 3, wherein the bag filter comprises a filter cloth made of polyphenylene sulfide resin.
5. The exhaust gas treatment apparatus according to claim 1 or 2, wherein the combustion furnace is a circulating fluidized bed boiler.
6. The exhaust gas treatment apparatus according to claim 1 or 2, wherein the combustion furnace is a bubbling fluidized bed boiler.