CN108636098A - A kind of the minimum discharge purifier and its method of burning city domestic garbage flue gas - Google Patents

Abstract

The invention discloses an ultra-low emission purification device for flue gas incineration of municipal domestic waste. The device includes a flue gas backflow device, an SNCR denitrification device, a semi-dry reaction tower, a lime slurry preparation and atomization spraying device, activated carbon and slaked lime dry powder spraying Equipment, bag filter, wet deacidification tower, 1# flue gas/flue gas heat exchanger, 2# flue gas/flue gas heat exchanger (2#GGH), steam/flue gas heat exchanger (SGH), SCR denitration device, induced draft fan and chimney. After being heated by 1#GGH, 2#GGH, and SGH, it enters the SCR reactor to further remove residual NO _x and dioxins in the flue gas. The pollutant concentration is finally better than the EU 2000 emission standard, achieving ultra-low emission.

Description

An ultra-low emission purification device and method for flue gas from municipal solid waste incineration

technical field

The invention relates to an ultra-low emission purification device and method for incinerating flue gas of municipal domestic garbage.

Background technique

In recent years, municipal solid waste incineration has developed rapidly, and many waste incineration power plants have been built in China. Waste incineration power generation is an effective way to deal with urban domestic waste. It not only processes domestic waste, but also recovers the heat energy in the waste. However, in the process of waste incineration, it is accompanied by the generation of flue gas, which contains a large amount of pollutants. These pollutants mainly include heavy metals (Cd, Pb, etc.), acid gases (HF, HCl, SO _x , NO _x , etc.) Pollution. Therefore, the flue gas produced during the incineration of municipal solid waste must be treated by a purification device to meet the emission standard before it can be discharged.

A large amount of NO _{x will be produced in the process of waste incineration, and the amount of NO x generated} is mainly related to the combustion temperature in the furnace and the chemical composition of waste. The _NOx produced by combustion can be divided into two types: one is thermal _NOx ; the other is fuel-type _NOx , and the majority of _NOx is formed by the nitrogen contained in garbage. At present, in addition to combustion control of _NOx and flue gas return, waste incineration power plants mainly use SNCR and SCR or a combination of the two. As far as the removal effect of _NOx is concerned, the removal rate of SCR to _NOx has reached more than 85%; while the removal rate of SNCR to _NOx can also reach about 60%; the removal rate of flue gas backflow to _NOx can also reach 20%. %about.

The acid gases produced by domestic waste incineration are mainly SO _x , HCl, and HF. At present, the deacidification process mainly includes dry method, wet method, semi-dry method and so on. A single deacidification process cannot meet the requirements. The commonly used deacidification process combination in China is "semi-dry + dry method". This combination can achieve good deacidification efficiency and can meet the current national emission standards.

Lignite activated carbon is commonly used as activated carbon. The activated carbon powder can absorb heavy metals such as Hg, Cd, and Pb in flue gas, as well as pollutants such as dioxins and furans in flue gas.

Bag filter, electrostatic precipitator and Venturi scrubber are the main methods for dust removal in flue gas of domestic waste incineration. With the rapid development of material science, the service life of the filter material has been greatly extended, making the bag filter a dominant position in the treatment of waste incineration flue gas. The dust entrained in the flue gas enters the bag filter, where the acid gas in the flue gas continues to react with the slaked lime, and the activated carbon continues to adsorb heavy metals and dioxins in the flue gas. Various particles (including soot in the flue gas, condensed heavy metals, reaction products, reactants, and activated carbon after adsorption) adhere to the surface of the filter bag of the dust collector, and are blown back by compressed air into the dust hopper of the dust collector, and pass through the dust collector. The scraper conveyor is sent to the public scraper conveyor, and then enters the fly ash storage bin after passing through the bucket elevator and the screw conveyor on the top of the fly ash bin.

Due to the complex and diverse harmful components in the flue gas produced by waste incineration, a single process cannot meet the treatment requirements, and a combination of multiple processes is required. Combined process is not a simple superposition of multiple processes. It needs to consider the operating conditions of each process. Reasonable layout can reduce energy consumption and achieve the highest treatment effect.

At present, the waste incineration flue gas purification system basically adopts two or more flue gas combination processes, such as semi-dry method + dry deacidification, activated carbon injection adsorption of dioxins, and bag filter dust removal. Due to the simple combination of each process, the pollutant removal effect is limited, and the treated flue gas is difficult to meet the emission standards ("Standards for the Control of Pollutants in Domestic Waste Incineration" (GB18485-2014)) and "EU (2000/76/EC) ", especially "EU (2000/76/EC)" requires that the dust content is less than 10mg/m ³ , sulfur dioxide is less than 50mg/m ³ , hydrogen chloride is less than 10mg/m ³ , hydrogen fluoride is less than 1mg/m ³ , and dioxins are less than 0.1ngTEQ /m ³ (The above emission limits are daily average values converted from the reference value of dry flue gas containing 11% O ₂ under standard conditions).

Contents of the invention

The purpose of the invention is to realize ultra-low emission under the condition of the lowest treatment cost. The flue gas purification system in the project adopts "SNCR (selective non-catalytic reduction denitrification) + rotary spray semi-dry method + dry deacidification + activated carbon jet adsorption + bag filter + flue gas return device + wet deacidification + 1# Flue gas/flue gas heat exchanger (1#GGH)+2# flue gas/flue gas heat exchanger (2#GGH)+steam/flue gas heat exchanger (SGH)+SCR (selective catalytic reduction denitrification)” technology. After the flue gas at the outlet of the waste heat boiler is treated by this system, the concentration of pollutants in the flue gas is better than the limit value of the flue gas emission index in the "EU (2000/76/EC)", achieving ultra-low emission.

The technical principle of the invention patent

In the waste heat boiler flue, a reducing agent with a certain concentration is sprayed into the furnace to react with _NOx under high temperature conditions, and convert _NOx into nitrogen to complete the first step of denitrification. After the flue gas passes through the outlet of the economizer (190-220°C), it enters the top of the semi-dry reaction tower from the upper part. The rotary atomizer is located at the upper part of the spray reactor. The lime slurry from the lime slurry preparation system enters the rotary atomizer. Due to the high-speed rotation of the atomizer, the lime slurry is atomized into tiny droplets, which form a countercurrent flow with the flue gas moving downward in a spiral shape, and are entrained by the huge flue gas flow to move downward. In the process, the lime slurry reacts with the acid gases HCl, HF, SO ₂ in the flue gas, and the reaction products fall into the reactor cone, part of the reaction products are discharged from the bottom of the cone, and the other part is contained in the fly ash. And all kinds of dust in the flue gas, with the flue gas into the next processing device. This cooling process also causes condensation of dioxins, furans and heavy metals.

After the flue gas comes out of the semi-dry reaction tower, it directly injects activated carbon powder and slaked lime powder into the flue. Slaked lime powder reacts with acid gases such as HCl, SO _x and HF, which can effectively further remove the residual acid gases in the flue gas after semi-dry treatment. Activated carbon powder can absorb heavy metals such as Hg in flue gas and organic pollutants such as dioxins and furans in flue gas.

The flue gas carries fly ash and various dusts into the bag filter, and the acid gas in the flue gas continues to react with the slaked lime on the filter bag of the bag filter, and the activated carbon continues to adsorb heavy metals and dioxins in the flue gas. Various particles (including soot in the flue gas, condensed heavy metals, reaction products, reactants, and activated carbon after adsorption) adhere to the surface of the filter bag of the dust collector, and are discharged into the ash hopper of the dust collector by compressed air blowback. The conveying system transports to the ash silo.

The outlet temperature of the bag filter is about 150 ℃ flue gas, part of the flue gas enters the waste heat boiler for flue gas circulation, and the other part of the flue gas enters the 1# flue gas/flue gas heat exchanger from the lower entrance, and the original flue gas is cooled by heat exchange through the tube pass Finally, it comes out from the lower outlet of the heat exchanger and enters the flue gas inlet in the lower half of the washing tower, and runs upward in the tower. The washing tower is composed of the cooling part at the lower part and the absorbing and dehumidifying part at the upper part. The cooling liquid circulation pump sends the cooling liquid at the bottom of the tower to the nozzle above the cooling part, and sprays it downward to fully contact with the countercurrent flue gas. After cooling, the caustic soda solution passes through The caustic soda delivery pump is sent to the cooling liquid circulation pipeline to maintain the pH value of the cooling liquid at a weakly acidic condition. At the same time, during this process, the caustic soda solution reacts with part of the _acid gas HCl, SO2, etc. in the flue gas to absorb the acid gas in the solution. In addition, a salt concentration indicator alarm is installed on the coolant circulation pipeline to adjust the discharge of coolant discharged from the bottom of the wet scrubber to ensure that the salinity remains stable.

The clean flue gas washed by the wet deacidification tower is heated through the 1# flue gas-flue gas heat exchanger, the 2# flue gas-flue gas heat exchanger and the steam/flue gas heat exchanger in turn, and after being heated to the appropriate temperature of the catalyst Enter the SCR reaction tower. In the SCR reaction tower, the _NOx in the flue gas reacts with the reducing agent under the action of the low-temperature catalyst to further remove the residual _NOx , and the flue gas after denitrification and purification enters into the Induced fan, and then to the chimney into the atmosphere.

Technical scheme of the present invention

An ultra-low emission purification device for municipal solid waste incineration flue gas, including flue gas return device, SNCR denitrification device, semi-dry reaction tower, lime slurry preparation and atomization injection device, activated carbon and slaked lime dry powder injection device, bag filter , wet deacidification tower, 1# flue gas/flue gas heat exchanger (1#GGH), 2# flue gas/flue gas heat exchanger (2#GGH), steam/flue gas heat exchanger (SGH), SCR Denitration device, induced draft fan and chimney, among which flue gas return device, SNCR denitrification device, semi-dry reaction tower, activated carbon and lime dry powder injection device and bag filter can effectively remove pollutants in the flue gas, and the flue gas passes through the above The concentration of pollutants after treatment by the device can basically meet the pollutant emission standards of EU 2000. By adding wet deacidification towers and SCR devices, the acid gases, NOx, dust and dioxins in the flue gas are further reduced to achieve ultra-low emissions.

In the above-mentioned ultra-low emission purification device for flue gas incineration of municipal solid waste, the upper part of the semi-dry reaction tower is provided with a flue gas inlet, the side wall is provided with a flue gas outlet, and the bottom is provided with a fly ash discharge port;

A slaked lime injection device and an activated carbon injection device are installed on the flue between the flue gas outlet of the semi-dry reaction tower and the flue gas inlet of the bag filter;

The flue gas inlet of the bag filter is set at the lower part of the dust collector, and the flue gas outlet is set at the upper part of the dust collector. There is a flue gas return device on the flue before the 1#GGH original flue gas inlet, and a discharge exhaust device is installed at the bottom of the bag filter. Ash device;

The original flue gas outlet on the side wall of 1#GGH is connected to the flue gas inlet on the side wall of the wet deacidification tower, and a bypass is connected to the fan. There is a flue gas outlet on the top of the wet deacidification tower, which is connected to the net flue gas inlet on the top of 1#GGH;

The outlet of the 1#GGH net flue gas passes through the pipe valve Ⅰ and then connects with the original flue gas inlet at the bottom of the 2#GGH, and the outlet of the other 1#GGH connects with the inlet of the induced draft fan through the pipe through the pipe valve Ⅲ;

The original flue gas outlet at the bottom of 2#GGH is connected to the lower inlet of SGH, the upper part of SGH is equipped with a flue gas outlet, and the flue gas outlet is connected to the top inlet of the SCR reaction tower;

There is a flue gas outlet at the bottom of the SCR reaction tower, which is connected to the net flue gas inlet of 2#GGH, and the bottom outlet of 2#GGH is connected to the induced draft fan through the valve II, and the outlet of the induced draft fan is connected to the flue gas.

There is a branch on the pipeline between the net flue gas outlet of 1#GGH and valve Ⅰ, and passes through valve Ⅲ. The back of valve Ⅲ is connected to the pipeline at the outlet of valve Ⅱ at the bottom of 2#GGH and enters the induced draft fan together. Its main function is that when 2#GGH, SGH and SCR reactors fail and need to be shut down, the flue gas can be directly connected to the induced draft fan from the outlet of 1#GGH, and then discharged through the chimney.

In the semi-dry reaction tower, the top channel is provided with a guide plate, which can make the flue gas move downward in a spiral shape. The rotary atomizer is located on the upper part of the spray reactor. The lime slurry from the lime slurry preparation system enters the rotary atomizer. Due to the high-speed rotation of the atomizer, the lime slurry is atomized into tiny droplets, which are in a spiral direction The flue gas moving downward forms a countercurrent and is carried downward by the huge flue gas flow. During this process, the lime slurry reacts with the acid gas in the flue gas. In the first stage of the reaction process, a neutralization reaction occurs by gas-liquid contact, the water in the lime slurry droplets is evaporated, and the flue gas is cooled at the same time; in the second stage, the gas-solid contact is further neutralized and a dry solid reactant is obtained , the reaction product falls into the reactor cone and is discharged from the bottom of the cone. This cooling process also produces condensation of dioxins and heavy metals.

The activated carbon injection device and the slaked lime dry powder injection device, the activated carbon and the slaked lime are transported from outside the factory by tank trucks, and the tank trucks have their own compressors to send them into the storage bin through the storage bin feed pipe. There is a dust collector on the top of the activated carbon and slaked lime silo, which collects the slaked lime dust and discharges the conveying air entering the silo. Arch breaking and air fluidization devices are installed at the bottom of the silo to prevent material bridging and maintain the fluidity of slaked lime. There is a metering device at the bottom, which is transported to the injection device by Roots blower and sprayed into the flue. The injected activated carbon and slaked lime are The flue begins to adsorb pollutants such as acid gas, dioxin, and heavy metals. The adsorption of activated carbon in the flue is not saturated, and the slaked lime and acid gas do not fully react. Then they enter the bag filter together with the flue gas and are adsorbed on the filter bag. On the surface, it is in full contact with the flue gas passing through the surface of the filter bag, and finally achieves the purpose of removing acid gases, dioxins and heavy metals in the flue gas.

The bag filter can not only remove particulate matter, but also can improve the desulfurization efficiency and the removal rate of heavy metals and dioxins. The bag filter adopts a low-pressure long-bag pulse structure, and the filter material is made of pure PTFE+PTFE-coated filter bags. In order to prevent condensation and ash sticking in the ash hopper, the ash hopper adopts an electric heating system.

The wet deacidification tower system is mainly composed of a wet deacidification tower, a dehumidification water tank, a dehumidification liquid heat exchanger, a wet deacidification tower supplementary water tank, a caustic soda storage tank, a sodium hydroxide dilution tank, a pump and control instruments, etc. . The washing tower is composed of the cooling part at the lower part and the absorbing and dehumidifying part at the upper part. The cooling liquid circulation pump sends the cooling liquid at the bottom of the tower to the nozzle above the cooling part, and sprays it downward to fully contact with the countercurrent flue gas, gradually reducing the temperature of the flue gas. reduce. The 20% caustic soda solution is sent to the cooling liquid circulation pipeline through the caustic soda delivery pump to maintain the pH value of the cooling liquid at a weak acid. At the same time, during this process, the caustic soda solution reacts with part of the _acid gas HCl, SO2, etc. in the flue gas. In order to maintain the concentration of salt in the cooling liquid, a salt concentration indicator alarm is installed on the cooling liquid circulation pipeline to adjust the temperature from the wet degassing Coolant discharge from the bottom of the acid tower.

The 1#GGH, 2#GGH, and SGH are all tubular heat exchangers.

The SCR reactor sprays a certain concentration of reducing agent into the mixed flue gas into the SCR reactor, and reacts with the nitrogen oxides in the flue gas under the action of the catalyst to generate harmless nitrogen and water vapor, which are then released by the SCR The tail of the reactor enters the inlet of the induced draft fan.

The purification method of the above-mentioned ultra-low emission purification device for flue gas incineration of municipal solid waste is as follows:

The SNCR system sprays the reducing agent into the waste heat boiler flue to complete the first step of denitrification, and the flue gas enters the semi-dry reaction tower from the upper part after passing through the economizer, and reacts with the atomized lime slurry to complete the first step of deacidification; After the gas comes out of the semi-dry reaction tower, activated carbon powder and slaked lime powder are directly sprayed into the flue to initially absorb and absorb acid gases, dioxins and heavy metal ions in the flue gas, and then the dust entrained by the flue gas enters the bag filter. Further deacidification is completed in the bag filter, and pollutants such as heavy metals and dioxins are removed. A small part of the flue gas from the bag filter enters the flue gas recirculation to reduce the generation of NOx; the other part enters 1#GGH The heat exchanger cools down. After cooling, the flue gas enters the wet deacidification tower to further remove the residual acid gas. After deacidification, the flue gas enters 1#GGH, 2#GGH, and SGH to heat up, and the heated flue gas enters the SCR reaction. The residual NO _x is removed by the device, and the purified flue gas enters 2#GGH, and the flue gas is discharged into the atmosphere through the induced draft fan and the chimney after heating up.

Beneficial effects of the present invention

An ultra-low emission purification device for municipal solid waste incineration flue gas of the present invention adopts flue gas backflow device, SNCR denitrification device, semi-dry reaction tower, lime slurry preparation and atomization spraying device, activated carbon and slaked lime dry powder spraying device, Bag filter, wet deacidification tower, 1# flue gas/flue gas heater, 2# flue gas/flue gas heater steam heater, SCR denitrification device, and multi-stage treatment devices for various pollutants, so It has greater advantages in desulfurization and denitrification, and removal of pollutants such as dioxins. First, reduce the amount of NO _x generated in the flue gas reflux device, and further use the SNCR device to remove NO _x in the flue gas. After passing through the economizer, the flue gas enters the semi-dry reaction tower from the upper part, and adopts rotary atomization Lime slurry is sprayed into the device, and the acid gas in the flue gas and the lime slurry complete the first step of deacidification; after the first step of deacidification is completed, the flue gas comes out of the semi-dry reaction tower, and is adsorbed by spraying activated carbon powder and slaked lime powder. And absorb the acid gas, dioxin and heavy metal ions in the flue gas, the slaked lime and activated carbon powder after the absorption and adsorption are fully reacted in the bag filter, and the dust is separated by the dust collector to further remove the acid gas, dioxin and Heavy metal ions, acid gas and dust remaining in the flue gas enter the wet deacidification tower to absorb and remove again. After the flue gas passes through the wet scrubber, the temperature drops. In order to ensure the treatment efficiency of the SCR reactor, 1#GGH and 2#GGH , SGH heating, and then into the SCR reactor to further remove residual NO _x and dioxins in the flue gas.

An ultra-low emission purification device for flue gas from municipal solid waste incineration of the present invention is used for purifying flue gas from municipal solid waste incineration, and the exhausted flue gas contains 5 mg/Nm ³ of smoke, 10 mg/Nm ³ of HCl, and 1 mg/Nm of HF ³ , SO ₂ 10mg/Nm ³ , NOx50mg/Nm ³ , CO10mg/Nm ³ , Hg0.02mg/Nm ³ , dioxin 0.02ng-TEQ/Nm ³ The dry flue gas of 11% O ₂ is the daily average value converted from the reference value), which meets the emission standards of the European Union 2000/76/EC, and the emission values of smoke, SO ₂ , NOx, CO, Hg, and dioxins are all better than those of the European Union 2000/76/EC emission limits, to achieve ultra-low emissions.

Description of drawings

Fig. 1 is a schematic structural view of the flue gas integrated purification treatment device of the present invention.

Fig. 2 is an enlarged view of part A of Fig. 1 .

Fig. 3 is an enlarged view of part B of Fig. 1 .

Detailed ways

The patent of the present invention will be further elaborated below through specific implementation examples and in conjunction with the accompanying drawings, but the present invention is not limited.

Example 1

An ultra-low emission purification device for municipal solid waste incineration flue gas, its structural schematic diagram is shown in Figure 1, including flue gas backflow device 7, SNCR denitrification device (not shown in the schematic diagram, belonging to furnace denitrification), semi-dry method Reaction tower 1 (lime slurry preparation and atomization injection device), activated carbon injection device 3, slaked lime dry powder injection device 4, bag filter 5, 1# flue gas/flue gas heat exchanger 8 (GGH), wet deacidification tower 9. 2# flue gas/flue gas heat exchanger 11 (GGH), steam/flue gas heat exchanger 12 (SGH), SCR denitrification device 13, reducing agent storage device 14, induced draft fan 15 and chimney 16.

The upper part of the semi-dry reaction tower 1 is provided with a flue gas inlet, the side wall is provided with a flue gas outlet, and the bottom is provided with a fly ash outlet 2; between the semi-dry reaction tower 1 flue gas outlet and the bag filter 5 flue gas inlet A slaked lime injection device 3 and an activated carbon injection device 4 are provided on the flue between them;

The flue gas inlet of the bag filter 5 is set at the lower part of the dust collector, the flue gas outlet is set at the upper part of the dust collector, and a flue gas return device is installed on the flue before the original flue gas inlet of the 1# flue gas/flue gas heat exchanger 8 7. There is an ash discharge device 6 at the bottom of the bag filter 5;

The original flue gas outlet provided on the side wall of 1#GGH8 is connected with the flue gas inlet provided on the side wall of the wet deacidification tower 9 , and a bypass is provided to connect the fan 15 . The top of the wet deacidification tower 9 is provided with a flue gas outlet, which is connected to the net flue gas inlet at the top of 1#GGH8;

The outlet of 1#GGH8 clean flue gas passes through the pipeline valve Ⅰ (17) and connects with the original flue gas inlet at the bottom of 2#GGH11, and the other way 1#GGH8 clean flue gas outlet passes through the pipeline through the pipeline valve Ⅲ(18) and the induced draft fan The original flue gas outlet at the top of 2#GGH11 is connected with the lower inlet of SGH12, the upper part of SGH12 is provided with a flue gas outlet, and the flue gas outlet is connected with the top inlet of SCR reaction tower 13; the bottom of SCR reaction tower 13 is provided with a flue gas outlet connected to To the top net flue gas inlet of 2#GGH11, the bottom net flue gas outlet of 2#GGH11 is connected to the induced draft fan 15 through the valve II (19), and the outlet of the induced draft fan is connected to the chimney 16;

There is a branch on the pipeline between the net flue gas outlet of 1#GGH8 and the valve Ⅰ (17) and passes through the valve Ⅲ (18), behind the valve Ⅲ (18) and the net flue gas outlet of the bottom valve Ⅱ (19) of 2#GGH11 The pipes are connected and enter the induced draft fan together. Its main function is that when 2#GGH11, SGH12 and SCR reactors fail and need to be shut down, the flue gas can be directly connected to the induced draft fan 15 from the net flue gas outlet of 1#GGH8, and then discharged through the chimney 16.

The above-mentioned ultra-low emission purification device for flue gas incineration of municipal solid waste has the following working route:

The SNCR system sprays the reducing agent into the flue of the waste heat boiler to complete the first step of denitrification, and the flue gas enters the semi-dry reaction tower 1 from the upper part after passing through the economizer, and reacts with the atomized lime slurry to complete the first step of deacidification; After the flue gas comes out of the semi-dry reaction tower 1, it enters the bag filter 5, and directly sprays activated carbon powder and slaked lime powder into the flue gas through the activated carbon injection device 3 and the slaked lime injection device 4, and initially absorbs and absorbs the acid gas in the flue gas. , dioxin and heavy metal ions, and then the flue gas entrained dust enters the bag filter 5, further removes the acid gas in the bag filter 5, and removes pollutants such as heavy metals and dioxins, and the ash is transported through the scraper machine to the ash bin; a small part of the flue gas from the bag filter 5 enters the flue gas return device 7 to reduce the generation of NOx, and the other part enters 1#GGH8 to cool down. After cooling, the flue gas enters the wet deacidification tower 9 for deacidification again. In addition to the residual acid gas, the flue gas after deacidification enters 2#GGH11 and SGH12 to raise the temperature, and the flue gas after heating enters the SCR reactor 13, and passes through the catalytic reaction of three layers of catalysts to further complete the denitrification and removal of dioxins, purification The final flue gas enters 2#GGH11, and the flue gas is discharged into the atmosphere through the induced draft fan 15 through the chimney 16 after being heated.

When 2#GGH11, SGH12 and SCR reactor 13 fail and need to be shut down, close valve Ⅰ (17) and valve Ⅱ (19), open valve Ⅲ (18), and the flue gas can be directly connected to the outlet of 1#GGH8. Fan 15 is discharged through chimney 16 again.

Application Example 1

Utilize the ultra-low emission purification device of a kind of municipal solid waste incineration flue gas described in embodiment 1 to process the municipal solid waste incineration flue gas, and its working route is as follows:

The SNCR system sprays the reducing agent into the flue of the waste heat boiler to complete the first step of denitrification. After passing through the economizer, the flue gas enters the semi-dry reaction tower 1 from the upper part, and the acid gas in the flue gas is neutralized with the atomized lime slurry reaction, removing a large part of the acid gas;

The flue gas comes out from the side of the semi-dry reaction tower 2 and enters the bag filter 5. The activated carbon injection device 3 and the slaked lime injection device 4 directly spray activated carbon powder and slaked lime powder into the flue gas to initially absorb and absorb the acidity in the flue gas. Gas, dioxin and heavy metal ions, and then the dust entrained by the flue gas enters the bag filter 5, and a filter layer is formed on the surface of the filter bag of the bag filter 5, and the slaked lime reacts with the acid gas to further remove the acid gas, and remove the heavy metal and Pollutants such as dioxin are separated together with the activated carbon, and the ash is transported to the ash bin through the scraper machine;

A small part of the flue gas from the bag filter 5 enters the flue gas return device 7 to reduce the amount of NOx produced, and the other part enters 1#GGH8 to cool down. After cooling, the flue gas enters the wet deacidification tower 9, and the lye flows from top to bottom Spraying, the flue gas and the lye are fully contacted and absorbed, and then the residual acid gas in the flue gas is further removed, and a part of the residual particulate matter is removed at the same time;

The deacidified flue gas enters 1#GGH8, 2#GGH11, and SGH12 to heat up, and the heated flue gas enters the SCR reactor 13, and passes through three layers of catalysts to further complete denitrification and dioxin removal. The flue gas enters 2#GGH11, and after being heated up, the flue gas is discharged into the atmosphere through the induced draft fan 15 and the chimney 16, so as to realize the ultra-low emission purification treatment of the flue gas.

After the above-mentioned ultra-low emission purification device for flue gas from municipal solid waste incineration is used for the purification treatment of flue gas from municipal solid waste incineration, the exhausted flue gas contains 5 mg/Nm ³ of smoke, 10 mg/Nm ³ of HCl, and 1 mg/Nm of HF ³ , SO ₂ 10mg/Nm ³ , NOx50mg/Nm ³ , CO10mg/Nm ³ , Hg0.02mg/Nm ³ , dioxin 0.02ng-TEQ/Nm ³ The dry flue gas of 11% O ₂ is the daily average value converted from the reference value), which meets the emission standards of the European Union 2000/76/EC, and the emission values of smoke, SO ₂ , NOx, CO, Hg, and dioxins are all better than those of the European Union 2000/76/EC emission limits, to achieve ultra-low emissions.

Comparative Example 1

That is, the combined flue gas treatment process of the existing technology "SNCR+semi-dry deacidification+activated carbon adsorption of dioxin+dry deacidification+bag filter" is adopted, the pollutant emission concentration meets the emission requirements, and the dust in the flue gas is 10mg /Nm ³ , HCl10mg/Nm ³ , HF1mg/Nm ³ , SO ₂ 50mg/Nm ³ , NOx150mg/Nm ³ , Hg0.05mg/Nm ³ , dioxin 0.1ng-TEQ/Nm ³ (the above emission values , all take the dry flue gas containing 11% _O2 under the standard state as the daily average value converted from the reference value), basically meeting the EU 2000/76/EC emission standard.

By comparing the above-mentioned Application Example 1 with Comparative Example 1, it can be seen that after the above-mentioned ultra-low emission purification device for municipal solid waste incineration flue gas is used for purification treatment of municipal solid waste incineration flue gas, in The soot content, sulfur dioxide content, nitrogen oxides, tribute content, dioxin content and other indicators are significantly lower than the existing technology, and the soot content and sulfur dioxide content are reduced to 1/2 and 1/5 of the prior art. The mercury content is 2/5 of the prior art, and the dioxin content is only 1/5 of the prior art, which shows that the flue gas purification treatment device of the present invention has obvious advantages in the removal of flue gas pollutants. Advantages, can achieve ultra-low emissions.

The above content is only a basic description of the concept of the present invention, and any equivalent transformation made according to the technical solution of the present invention belongs to the protection scope of the present invention.

Claims (4)

1. An ultra-low emission purification device for municipal solid waste incineration flue gas, characterized in that it includes flue gas backflow device, SNCR denitrification device, semi-dry reaction tower, lime slurry preparation and atomization injection device, activated carbon and slaked lime dry powder Injection device, bag filter, wet deacidification tower, 1# flue gas/flue gas heat exchanger (1#GGH), 2# flue gas/flue gas heat exchanger (2#GGH), steam/flue gas exchanger Heater (SGH), SCR denitrification device, induced draft fan and chimney, which are characterized in that ultra-low emissions are achieved after multi-process combination, and two-stage GGH is used to recover heat energy and reduce energy consumption; The upper part of the semi-dry reaction tower is equipped with a flue gas inlet, the side wall is equipped with a flue gas outlet, and the bottom is equipped with a fly ash outlet; A slaked lime injection device and an activated carbon injection device are installed on the flue between the flue gas outlet of the semi-dry reaction tower and the flue gas inlet of the bag filter; The flue gas inlet of the bag filter is set at the lower part of the dust collector, the flue gas outlet is set at the upper part of the dust collector, and the bottom of the bag filter is equipped with an ash discharge device; There is a flue gas return device on the flue before the original flue gas inlet of 1#GGH, and a bypass is connected to the induced draft fan; The raw flue gas outlet on the side wall of 1#GGH is connected to the flue gas inlet on the side wall of the wet deacidification tower, and the flue gas outlet on the top of the wet deacidification tower is connected to the net flue gas inlet on the top of 1#GGH; The outlet of 1#GGH net flue gas is connected to the inlet of raw flue gas at the bottom of 2#GGH through pipeline valve Ⅰ, and another bypass is connected to the inlet of induced draft fan through pipeline valve Ⅲ; The original flue gas outlet at the bottom of 2#GGH is connected to the lower inlet of SGH, and the upper part of SGH is equipped with a flue gas outlet, and the flue gas outlet is connected to the top inlet of the SCR reaction tower; There is a flue gas outlet at the bottom of the SCR reaction tower, which is connected to the net flue gas inlet of 2#GGH, and the bottom outlet of 2#GGH is connected to the induced draft fan through the valve II, and the outlet of the induced draft fan is connected to the flue gas; There is a bypass on the pipe between the net flue gas outlet of 1#GGH and valve Ⅰ, which is connected to the pipe at the outlet of valve Ⅱ at the bottom of 2#GGH through the back of valve Ⅲ and enters the induced draft fan together. 2. A kind of ultra-low emission purification device for municipal solid waste incineration flue gas as described in right 1, is characterized in that, simultaneously adopts flue gas backflow device, SNCR denitrification device, semi-dry method reaction tower, lime slurry preparation and atomization Injection device, activated carbon and slaked lime dry powder injection device, bag filter, wet deacidification tower, SCR denitrification device, reasonable arrangement of reactors, so that the efficiency of the device can be optimized, and pollutants can be treated by multi-level treatment devices to achieve ultra-low emissions. 3. A kind of ultra-low emission purification device for municipal solid waste incineration flue gas as claimed in right 1, characterized in that, it is recovered by 1# flue gas/flue gas heat exchanger and 2# flue gas/flue gas heat exchanger heat energy of the flue gas. 4. A method for purifying ultra-low emissions of flue gas from municipal solid waste incineration, characterized in that the generation of NO _x is reduced in a flue gas recirculation device, and the NO _x in the flue gas is further removed by the SNCR device, and the flue gas passes through the province After the coal burner, it enters the semi-dry reaction tower from the upper part, and the lime slurry is sprayed into the top of the tower with a rotary atomizer, and the acid gas in the flue gas and the lime slurry complete the first step of deacidification; After the method reaction tower comes out, the acid gas, dioxin and heavy metal ions in the flue gas are adsorbed and absorbed by spraying activated carbon powder and hydrated lime powder, and the absorbed and adsorbed hydrated lime and activated carbon powder are fully reacted in the bag filter and passed through The dust collector separates the dust, and further removes acid gas, dioxin and heavy metal ions. The acid gas and dust remaining in the flue gas enter the wet deacidification tower for absorption and removal again, and the temperature of the flue gas after washing decreases.