Sludge pyrolysis combustible gas incineration flue gas treatment process

Abstract

The invention relates to the technical field of flue gas treatment, in particular to a sludge pyrolysis combustible gas incineration flue gas treatment process which comprises the following steps: S1, sludge pyrolysis: gasifying organic matters in sludge into combustible gas; s2, combustible gas incineration, wherein combustible gas is received, and efficient incineration is conducted on the combustible gas; s3, heat energy recovery, wherein heat energy generated by combustible gas incineration is recovered; s4, flue gas purification treatment: S41, SNCR denitration: reserving an SNCR in-furnace denitration system interface in a hot blast stove, and uniformly arranging an ammonia water solution preparation system through SNCR and SCR; s42, activated carbon spraying, wherein a pneumatic conveying process is adopted for the activated carbon, and powdery activated carbon is quantitatively conveyed into a flue between the waste heat boiler and a bag-type dust collector in a pneumatic conveying mode; s43, carrying out cloth bag dust removal; s44, wet desulphurization: SO2 and HCL in the flue gas are absorbed by water in the spraying slurry; s5, discharging flue gas; the sludge pyrolysis combustible gas treatment device has the effects that sludge pyrolysis combustible gas can be efficiently utilized and effectively treated.

Description

Technical Field

[0001] The present application relates to the technical field of flue gas treatment, and in particular to a flue gas treatment process for sludge pyrolysis combustible gas incineration. Background Art

[0002] With the acceleration of urbanization, sludge production has increased year by year, and sludge treatment has become an important issue in environmental protection. Traditional sludge treatment methods can no longer meet the requirements of environmental protection and sustainable development. For example, sludge landfill method occupies a large amount of land resources and is prone to cause secondary pollution to the environment, such as leachate leakage, odor diffusion, etc.; sludge composting method has a long treatment cycle, occupies a large area, and the quality of compost products is unstable, which is difficult to meet the needs of modern agriculture; although traditional sludge incineration technology can quickly reduce the volume of sludge, it will produce a large amount of dioxins, fly ash and other toxic and harmful substances, posing a serious threat to the environment and human health.

[0003] At present, a variety of methods are used in the existing technology to treat sludge. Common methods include biological treatment, chemical treatment and physical treatment. Biological treatment mainly decomposes organic matter in sludge through the action of microorganisms, but this requires a long time and a large site. Chemical treatment changes the properties of sludge by adding chemical agents to make it easier to handle, but this method may produce new pollutants. Physical treatment includes drying, pyrolysis, incineration and other methods. Among them, pyrolysis technology has attracted attention due to its high degree of resource utilization and low risk of secondary pollution. However, although pyrolysis technology can effectively convert organic matter in sludge into combustible gas, liquid fuel and solid slag to achieve resource recycling, it still faces some problems in practical applications.

[0004] With regard to the above-mentioned related technologies, the combustible gas generated by the existing sludge pyrolysis technology during the treatment process is often directly discharged, which not only wastes resources but also may pollute the environment. In addition, the combustion process of sludge pyrolysis combustible gas is prone to produce harmful substances such as nitrogen oxides, sulfides, carbon monoxide, dioxins and particulate matter. These problems seriously affect the environmental performance of the system. Therefore, a process is needed that can efficiently utilize the sludge pyrolysis combustible gas and effectively treat it. Summary of the invention

[0005] In order to overcome the above problems, the present application provides a sludge pyrolysis combustible gas incineration flue gas treatment process.

[0006] The present application provides a sludge pyrolysis combustible gas incineration flue gas treatment process adopts the following technical solution: A sludge pyrolysis combustible gas incineration flue gas treatment process, comprising S1: Sludge pyrolysis: gasify the organic matter in the sludge into combustible gas; S2: Combustion of combustible gas: receiving combustible gas and burning it efficiently; S3: Heat recovery: recover the heat energy generated by combusting combustible gas; S4: Flue gas purification S41: SNCR denitration: that is, selective non-catalytic reduction technology, with an SNCR furnace denitration system interface reserved in the hot blast furnace, and a unified ammonia solution preparation system for SNCR and SCR; S42: Activated carbon injection: The activated carbon is pneumatically conveyed to quantitatively deliver the powdered activated carbon into the flue between the waste heat boiler and the bag filter; S43: Bag filter: The flue gas is dusted by a bag filter; S44: Wet desulfurization: SO2 and HCL in the flue gas are absorbed by the water in the spray slurry and separated from the flue gas; S5: Smoke emission: The smoke is introduced into the chimney and discharged into the air.

[0007] By adopting the above technical scheme, efficient incineration of sludge pyrolysis combustible gas and multi-stage purification of flue gas are achieved; first, organic matter is gasified into combustible gas during sludge pyrolysis, which improves the utilization rate of resources; second, combustible gas is burned by an efficient incinerator to generate high-temperature flue gas, which not only reduces the emission of pollutants, but also provides conditions for subsequent heat recovery. Then, the flue gas is recovered through a heat exchanger for heat energy recovery, which improves energy utilization efficiency and reduces energy waste. In the flue gas purification stage, SNCR denitrification technology effectively reduces the NOx content in the flue gas without the need for a catalyst, while activated carbon injection further removes heavy metals and dioxins, and bag dust removal and wet desulfurization remove solid particles and sulfur dioxide in the flue gas, respectively, ensuring the cleanliness and environmental protection of the flue gas. Finally, the flue gas that has undergone multi-stage purification is introduced into the chimney through an induced draft fan and meets the environmental emission standards, thereby achieving efficient utilization of sludge pyrolysis combustible gas and effective treatment of it.

[0008] In a specific implementation scheme, step S41 includes S411: Ammonia reducing agent is uniformly sprayed into the appropriate flue gas temperature range, and is rapidly decomposed in the furnace to react with NOx in the flue gas to generate N2 and H2O. The SNCR process does not require a catalyst. When the reaction temperature is too high, the decomposition of ammonia will reduce the NOx reduction rate; when the reaction temperature is too low, the escape of ammonia will increase, which will also reduce the NOx reduction rate.

[0009] By adopting the above technical solution, the amino reducing agent can be evenly sprayed in the appropriate range of flue gas temperature, reacting with NOx in the flue gas to generate N2 and H2O, effectively reducing NOx emissions. The SNCR process does not require the use of catalysts, reducing costs. However, this solution has high requirements for the reaction temperature. When the reaction temperature is too high, the decomposition of ammonia will reduce the NOx reduction rate; when the reaction temperature is too low, the escape of ammonia increases, which will also cause the NOx reduction rate to decrease. This ensures that the NOx reduction rate remains at a high level under different operating conditions, improving the denitrification efficiency and environmental performance.

[0010] In a specific implementation scheme, in step S42, during the activated carbon bin feeding period, the air in the activated carbon bin is discharged to the outside through the filter bag and the exhaust pipe.

[0011] By adopting the above technical solution, the air in the activated carbon bin can be effectively removed during the feeding of the activated carbon bin, avoiding pressurization of the activated carbon bin and ensuring the normal operation of the activated carbon bin; this not only helps to maintain the stability and safety of the system, but also ensures the smooth progress of the subsequent activated carbon injection process, improves the removal efficiency of harmful substances in the flue gas, reduces the impact of dust on equipment and operators, and improves the stability and safety of the entire system.

[0012] In a specific feasible implementation scheme, in step S43, bag dust removal includes the dust-containing gas entering the ash hopper of each chamber, using compressed air pulse cleaning, and maintaining good filtering performance for a long time through hot filter bags.

[0013] By adopting the above technical solution, after the dust-laden gas enters the ash hopper of each chamber, the coarse dust particles settle to the bottom of the ash hopper, the fine dust is retained on the surface of the filter bag, and the purified gas is discharged through the filter bag port. The compressed air pulse cleaning method is adopted to regularly remove the particles attached to the filter bag, restore the filtering performance of the filter bag, and ensure long-term stable operation. The design of the hot filter bag can maintain good filtering performance at a higher temperature, avoid the influence of high temperature on the filter bag material, and extend the service life; the overall dust removal efficiency and system stability are improved.

[0014] In a specific implementation scheme, step S4 also includes S45: Flue gas supplementary combustion and heating: The flue gas temperature at the outlet of the gas heat exchanger needs to be heated from 175°C to 220°C.

[0015] By adopting the above technical solutions, it is ensured that the denitrification reaction is carried out within the optimal temperature range, thereby improving the denitrification efficiency, reducing nitrogen oxide emissions, and improving the overall environmental performance of flue gas treatment.

[0016] In a specific possible implementation scheme, in step S44, the absorption slurry is collected in the absorption tower slurry pool, and the tower bottom slurry is forcedly oxidized.

[0017] By adopting the above technical solutions, this process not only improves the desulfurization efficiency and ensures the effective removal of harmful substances in the flue gas, but also reduces the formation of by-products, which is beneficial to the safety of subsequent treatment and discharge. Forced oxidation can also prevent calcium sulfite from depositing in the slurry pool, maintain the fluidity of the slurry, and avoid blockage.

[0018] In a specific possible implementation scheme, in step S44, the gypsum generated after oxidation is discharged through the absorption tower slurry pump to remove the mist droplets in the outlet flue gas, and the limestone slurry is sprayed out from multiple nozzles on the main pipe in the absorption tower.

[0019] By adopting the above technical scheme, the effective treatment and discharge of gypsum generated after oxidation is achieved, ensuring the smooth discharge and subsequent treatment of gypsum. The effective removal of sulfur dioxide in flue gas is achieved, and the stable operation of the system is ensured. The specific effects are as follows: the gypsum generated after oxidation is discharged through the absorption tower slurry pump: this measure ensures that the gypsum generated by the oxidation reaction can be discharged from the system in time, avoiding the accumulation of gypsum in the absorption tower, thereby ensuring the normal operation of the system and efficient desulfurization; effectively removes the fog droplets in the flue gas, reduces the burden of subsequent treatment links, and improves the cleanliness and safety of the entire system; enables the limestone slurry to be evenly distributed in the flue gas, enhances the contact opportunity with sulfur dioxide in the flue gas, improves the desulfurization efficiency, and also helps to maintain the uniformity and stability of the slurry in the absorption tower.

[0020] In a specific possible implementation scheme, in step S3, flue gas heat exchange is adopted: the high-temperature flue gas transfers heat to the external medium.

[0021] By adopting the above technical solution, the heat recovery efficiency is significantly improved, energy waste is reduced, the energy utilization efficiency of the entire system is improved, and operating costs are reduced. In addition, this solution also helps reduce greenhouse gas emissions and meets environmental protection requirements.

[0022] In a specific implementation scheme, in step S3, the waste heat of the flue gas is utilized, and the waste heat boiler is connected to the combustible gas incinerator. The high-temperature flue gas generated after the combustible gas is incinerated in the hot blast furnace enters the waste heat boiler to generate steam for recovering the heat generated by the incineration.

[0023] By adopting the above technical solution, the energy utilization rate is improved, the energy waste is reduced, the effective recovery of heat in the flue gas is achieved, and the energy consumption of the overall process is reduced.

[0024] In summary, the present application includes at least one of the following beneficial technical effects: 1. The designed sludge pyrolysis combustible gas incineration flue gas treatment process realizes the efficient incineration of sludge pyrolysis combustible gas and the multi-stage purification of flue gas. The sludge pyrolysis combustible gas incineration flue gas treatment system of the present invention achieves efficient incineration, heat recovery and flue gas purification. The flue gas after multi-stage purification is introduced into the chimney through the induced draft fan and discharged, which meets the environmental emission standards, thereby helping to improve the overall treatment efficiency and environmental performance, not only realizing the efficient utilization of combustible gas generated by sludge pyrolysis, but also reducing environmental pollution, with significant economic and environmental benefits. At the same time, the automated control design of the system improves the system's operational stability and operational convenience.

[0025] 2. The designed sludge pyrolysis combustible gas incineration flue gas treatment process ensures that the NOx reduction rate remains at a high level under different working conditions, thereby improving the denitrification efficiency and environmental protection performance.

[0026] 3. The designed sludge pyrolysis combustible gas incineration flue gas treatment process ensures that the denitrification reaction is carried out within the optimal temperature range, thereby improving the denitrification efficiency, reducing nitrogen oxide emissions, and improving the overall environmental performance of flue gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process flow chart of the flue gas treatment process of sludge pyrolysis combustible gas incineration in the embodiment of the present application.

[0028] Figure 2 It is a flow chart of the flue gas purification process in this embodiment. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-2 This application is described in further detail.

[0030] The embodiment of the present application discloses a process for treating flue gas from the incineration of combustible gas by pyrolysis of sludge.

[0031] Reference Figure 1 and Figure 2 A sludge pyrolysis combustible gas incineration flue gas treatment process includes: S1: Sludge pyrolysis: The organic matter in the sludge is gasified into combustible gases with CO and H2 as the main components.

[0032] S2: Combustion of combustible gas: combustible gas is burned efficiently to produce high-temperature flue gas.

[0033] S3: Heat recovery S31: Flue gas heat exchange: The high-temperature flue gas transfers heat to the external medium through the heat exchanger arranged at the outlet of the incinerator. The heat exchanger includes a plurality of heat exchange tubes arranged in parallel. Each heat exchange tube is provided with a spiral spoiler inside to promote the heat transfer effect. The outer wall of the heat exchange tube is also provided with fins to increase the heat exchange area and further improve the heat transfer effect. These designs enable the heat in the high-temperature flue gas to be more effectively transferred to the external medium, thereby improving energy utilization and reducing energy waste; Utilization of flue gas waste heat: The waste heat boiler is connected to the combustible gas incinerator. The high-temperature flue gas generated after the combustible gas is incinerated in the hot blast furnace enters the waste heat boiler to generate steam, which is used to recover the heat generated by incineration and can be used for sludge drying, heating, etc.

[0034] S4: Flue gas purification S41: SNCR denitrification: It is a selective non-catalytic reduction technology. An interface for the SNCR furnace denitrification system is reserved in the hot blast furnace. Ammonia solution preparation system is uniformly set for SNCR and SCR. The injection can be carried out at a preset height layer in the hot blast furnace. When the furnace load changes, the selection of the injection layer is controlled by the automatic control system according to the furnace temperature.

[0035] S411: Without using a catalyst, the amino reducing agent is uniformly sprayed into the appropriate flue gas temperature range, and is rapidly decomposed in the furnace to react with NOx in the flue gas to generate N2 and H2O. The SNCR process does not require a catalyst, and the optimal reaction temperature is 850-1100°C. The reducing agent is ammonia water. When the reaction temperature is too high, the decomposition of ammonia will reduce the NOx reduction rate; when the reaction temperature is too low, the escape of ammonia will increase, which will also reduce the NOx reduction rate. The concentration of ammonia water as a reducing agent is 20% (wt). Ammonia water is transported to the mixer through the ammonia water metering pump delivery module and fully mixed with dilution water (deionized water). The ammonia water is diluted to a dilute solution of about 5% (wt). Then it passes through the distribution module and is distributed to each spray gun. It is sprayed into the furnace through the spray gun to remove NOx. The main reaction of ammonia water as a reducing agent is: 4NH3+4NO+O2→4N2+6H2O. However, when the temperature is too high, the following side reaction will also occur: 4NH3+5O2→4NO+6H2O.

[0036] S42: Activated carbon injection: During the feeding of the activated carbon silo, the air in the activated carbon silo is discharged to the outside through the filter bag and the exhaust pipe to avoid pressurizing the activated carbon silo. The dust collector on the top of the silo not only runs during the process of the activated carbon silo receiving the activated carbon, but also runs at regular intervals after receiving the activated carbon. An arch breaking device is installed in the silo. The activated carbon injection system needs to be equipped with a metering device. The required amount of activated carbon is given by the PLC, and the required amount is adjusted online in real time. The activated carbon is transported by air to the set point.

[0037] The activated carbon is pneumatically conveyed to deliver the powdered activated carbon into the flue between the waste heat boiler and the bag filter in a quantitative manner to further remove the heavy metal substances (Hg, Cd, Pb, other heavy metals) and dioxins in the flue gas, in order to ensure that the emission of various harmful substances meets the standards.

[0038] The activated carbon storage bin is equipped with high and low material level alarms, material level meter signals, and status button signals that first enter the local control box and then enter the PLC control system from the control box. The on-site control box completes the closed-loop control function of the on-site injection equipment. A loss-in-weight scale device is installed under the storage bin, and the servo controls the feeding amount to ensure uniform and stable material feeding.

[0039] Working air source: compressed air. The working air source margin is designed to be at least 120% of the maximum working air volume. The pressure margin is 150% of the maximum pressure loss. The injection device is made of corrosion-resistant materials and is designed to be an anti-blocking structure. The activated carbon metering injection dry powder conveying air duct is equipped with valves, pressure gauges, connectors, etc. The activated carbon injection system consists of three parts, namely, the activated carbon injection system module, the activated carbon adding system module, and the public system (compressed air, etc.) module, specifically including: activated carbon storage bin, screw feeder, feeding air duct, mixer, adsorbent spray gun, conveying pipeline fittings (Venturi), metering instruments, etc.

[0040] S43: Bag filter: Gas dust removal through bag filter; bag filter includes Dust collector body: The dust collector is made of carbon steel Q235. The dust-containing gas enters the ash hopper of each chamber from the main air inlet pipe through the air branch pipe. The coarse dust particles settle to the bottom of the ash hopper, and the fine dust is retained on the surface of the filter bag. The purified gas passes through the filter bag port, the air outlet, and the exhaust valve to the main air outlet pipe. An air distributor is installed in the air inlet of the dust collector to disperse the gas evenly after entering the dust collector, so that the gas will not be flushed to the bag. The air leakage rate of the main body is ≤2% and meets the dust removal requirements. The dust-containing gas enters the ash hopper of each chamber from the air inlet main pipe through the air distribution branch pipe. The coarse dust particles settle to the bottom of the ash hopper, and the fine dust is retained on the surface of the filter bag. The purified gas passes through the filter bag port and the air outlet through the exhaust valve to the air outlet main pipe. The dust collector is cleaned online to blow off the particles attached to the filter bag and restore the filtering function of the filter bag. The cleaning method is constant pressure cleaning or timed cleaning. When the pressure difference between the inlet and outlet of the dust collector reaches the set difference or the time reaches the set value, the PLC programmable electronic controller in the electric control cabinet will issue a command to perform pulse spray cleaning on the dust collector. Filter bag: Reliable long-term continuous operation allows flue gas temperature of 180 ~ 220 ℃, high temperature resistance of 240 ℃ (more than half an hour), filter bag material: 100% PTFE base cloth + 100% PTFE coating, and uses PTFE tape sealing technology, gram weight not less than 550g / m2.

[0041] Bag cage: The material of the bag cage is 20# steel. The cage body is treated with silicone spraying and baking anti-corrosion technology. The spraying thickness is not less than 60um. There are 6 ribs. The longitudinal ribs and anti-support rings of the bag cage are evenly distributed and have sufficient strength and rigidity to prevent damage and deformation. The specifications and quantity of the longitudinal ribs and the spacing of the anti-support rings are provided.

[0042] Flower plate: The flower plate of the dust collector is used to separate the clean air chamber and the filter chamber of the dust collector, and is used to hang the filter bag assembly. It also serves as an inspection platform for the filter bag assembly of the dust collector. Its strength is sufficient to hang all the filter bags and bag cages, and there is no deformation or distortion when 5kg of dust is hung on each filter bag in the filtering state. The wall thickness of the flower plate is 6mm, and the material is Q235-B primary flat plate.

[0043] Cleaning system: compressed air is used for cleaning; the diaphragm life of the electromagnetic pulse valve is guaranteed to be 5 years.

[0044] Ash hopper: The dust collector ash hopper is equipped with an ash poking hole. In order to avoid smoke short-circuiting, a baffle is installed in the ash hopper. Its lower part is far away from the ash discharge port. The angle between the inclined wall of the ash hopper and the horizontal plane is greater than 60 degrees. The inner side of the intersection of adjacent walls is made into an arc shape with a radius of 200mm to ensure the free flow of dust. Each ash hopper is equipped with a high material level indicator, and has an audible and visual alarm signal output, which can be displayed on the PLC. The level meter adopts a radio frequency admittance type with adjustable sensitivity.

[0045] Fly ash chelation system: The fly ash stabilization treatment adopts the fly ash stabilization process of "fly ash + chelating agent + water". The fly ash collected in the ash hopper of the bag filter is transported into the mixer through a screw conveyor and a fly ash scale. The agent used for fly ash chelation is prepared into a solution with water, and the chelating agent and fly ash are fully mixed in the mixer. That is, fly ash, chelating agent and water are added into the mixer in a certain proportion and fully stirred. After the fly ash is stabilized, it is handed over to a qualified enterprise for treatment.

[0046] GGH (flue gas / flue gas heat exchanger): Since the denitrification system is arranged after the desulfurization system, the flue gas temperature at the desulfurization outlet is about 50°C, so the denitrification system needs to be equipped with a flue gas GGH heat exchanger. After the desulfurization clean flue gas is heated by GGH, it is further heated by supplementary combustion to reach the denitrification flue gas temperature of 220°C. In the present invention, a flue gas / flue gas heat exchanger is respectively arranged before and after the absorption tower and before and after the denitrification reactor to fully utilize the heat in the system, and the desulfurization outlet flue gas temperature is heated from 50°C to about 175°C in two times, and at the same time, the denitrification outlet flue gas temperature is reduced from 220°C to about 150°C.

[0047] S44: Wet desulfurization: The chemical reaction of the desulfurization system mainly occurs in the absorption tower. SO2 and HCL in the flue gas are absorbed by the water in the spray slurry and separated from the flue gas. The oxidation and crystallization reactions occur in the absorption tower slurry pool. The pH value in the absorption tower slurry pool is controlled at about 5.3-5.7. The size of the absorption tower slurry pool ensures that sufficient slurry residence time can be provided to complete the oxidation of calcium sulfite to calcium sulfate and the crystallization of gypsum (CaSO4·2H2O).

[0048] (1) The entire reaction that occurs in the absorption tower is: SO2+CaCO3→CaSO3+CO2 SO3+CaCO3→CaSO4+CO2 (2) There are also many intermediate reactions that form calcium ions in the aqueous slurry.

[0049] CaCO3(s)→CaCO3(aq) CaCO3(aq)+H2O→Ca 2+ +HCO3 - +OH - (3) SO3 is formed at the flue gas / slurry interface in the absorption tower 2- Anion.

[0050] SO2(g)→SO2(aq) SO2(aq)+H2O→H2SO3→HSO3 - +H + HSO3 - →H + +SO3 2- (4) Gypsum is the main precipitate formed in a forced oxidation environment.

[0051] SO3 2- +1 / 2O2→SO4 2- Ca 2+ +SO4 2- +2H2O→CaSO4·2H2O(s) (5) Sulfite ions also combine with calcium ions to form calcium sulfite hemihydrate precipitate.

[0052] Ca 2+ +SO3 2- +1 / 2H2O→CaSO3·1 / 2H2O(s) (6) In addition to sulfur dioxide, the absorber also removes hydrogen chloride and hydrogen fluoride from the flue gas. Calcium carbonate reacts with these substances to form dissolved salts.

[0053] 2HCl+CaCO3→CaCl2+H2O+CO2 2HF+CaCO3→CaF2+H2O+CO2 The flue gas to be treated first passes through the desulfurization plate heat exchanger to exchange heat between the flue gas entering the absorption tower and the flue gas discharged from the absorption tower, thereby reducing the energy consumption of the flue gas reburning and heating at the rear end; the flue gas after cooling enters the absorption tower and contacts with the sprayed limestone slurry to remove SO2 in the flue gas. The absorption slurry is collected in the absorption tower slurry pool and returned to the nozzle for recycling through the slurry circulation pump. The slurry at the bottom of the tower is forced to be oxidized, and an oxidation fan is set. A stirrer is set in the oxidation slurry pool to ensure uniform mixing and prevent slurry precipitation; the limestone generated after oxidation The slurry is discharged through the absorption tower slurry pump, enters the gypsum cyclone and is discharged through a vacuum belt conveyor. The absorption tower chimney is equipped with a dust removal and demisting device to remove the mist droplets in the outlet flue gas. The limestone slurry is sprayed out from multiple nozzles arranged on the main pipe in the absorption tower, and after contacting with the flue gas to undergo a neutralization reaction to remove sulfur dioxide in the flue gas, it flows into the absorption tower slurry pool, absorbs HSO3- in the slurry, and is forced to be oxidized into SO42- by the air blown into the slurry pool, and finally reacts to form calcium sulfate dihydrate (CaSO4.2H2O) slurry, namely gypsum slurry.

[0054] The absorbent used in the absorption tower - limestone slurry is provided by the limestone slurry preparation system. The by-product gypsum generated by the reaction in the FGD system is dehydrated by the gypsum dehydration system. The desulfurization wastewater passes through the filtrate pool and is discharged into the comprehensive wastewater station in the plant.

[0055] S45: Flue gas supplementary combustion to increase temperature Because the temperature of flue gas after passing through the desulfurization plate heat exchanger before and after desulfurization and the denitrification plate heat exchanger before and after denitrification cannot fully meet the optimal reaction window of the denitrification catalyst, a flue gas heating device is added. The flue gas temperature at the outlet of the gas heat exchanger needs to be heated from 175℃ to 220℃, so that the operating temperature of the catalyst is controlled at about 220℃ to achieve the best denitrification efficiency. The high-temperature flue gas generated by the combustion of natural gas in the combustion furnace enters the main flue pipe, and is fully mixed with the flue gas to be treated in the main flue pipe. The flue gas reaching the process temperature is sent to the SCR denitrification reactor. By detecting the mixed flue gas temperature signal (the temperature entering the denitrification process requires 220℃), the temperature detection value and the set value are compared. After the PLC controller performs P, I, and D operations, it outputs the combustion load control signal (automatically increase or decrease) to the electric or pneumatic actuator to adjust the natural gas valve opening and the air damper opening to meet the user's load change needs. Stabilize the temperature of the flue gas to be denitrified at a target set value, not more than 2℃. The output of the supplementary combustion system is taken into account while taking into account the regular catalyst regeneration of the SCR system (the regeneration temperature is about 320°C and the regeneration time is tentatively set at once a week).

[0056] S5: Flue gas emissions S51: SCR adopts low-temperature SCR denitrification technology, the denitrification agent is 20% ammonia water, and the reaction temperature is 210-350℃ (the minimum continuous operating temperature is 210℃, and the maximum continuous operating temperature is 350℃). The flue gas temperature at the desulfurization outlet is about 50℃, so the denitrification system needs to be equipped with a flue gas GGH heat exchanger. After the desulfurization clean flue gas is heated by GGH, the denitrified flue gas that reaches 220℃ through reburning heating is mixed with the injected gas ammonia and enters the SCR denitrification reactor. The nitrogen oxides and ammonia in the flue gas undergo selective catalytic reduction reaction under the action of the catalyst to generate nitrogen and water. Under the action of the flue gas heat exchanger (GGH), the flue gas temperature at the outlet of the denitrification reactor is reduced from 220℃ to about 150℃, and is discharged to the chimney through the denitrification induced draft fan. The GGH absorbs the heat of the high-temperature section and heats the imported low-temperature flue gas; S52: The flue gas is introduced into the chimney through the induced draft fan and discharged into the air.

[0057] The implementation principle of a sludge pyrolysis combustible gas incineration flue gas treatment process in an embodiment of the present application is: when sludge treatment is required, first, the sludge is pyrolyzed to convert the organic matter in the sludge into combustible gas, and then the combustible gas is incinerated to recover the heat energy after the incineration of the combustible gas, and then the flue gas is subjected to multi-stage purification treatment through SNCR denitrification, activated carbon injection, bag dust removal and wet desulfurization. After the flue gas purification is completed, the flue gas is introduced into the chimney through the induced draft fan and discharged into the air.

[0058] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A sludge pyrolysis combustible gas incineration flue gas treatment process, characterized by: include S1: Sludge pyrolysis: gasify the organic matter in the sludge into combustible gas; S2: Combustion of combustible gas: receiving combustible gas and burning it efficiently; S3: Heat recovery: recover the heat energy generated by combusting combustible gas; S4: Flue gas purification S41: SNCR denitration: that is, selective non-catalytic reduction technology, with an SNCR furnace denitration system interface reserved in the hot blast furnace, and a unified ammonia solution preparation system for SNCR and SCR; S42: Activated carbon injection: The activated carbon is pneumatically conveyed to quantitatively deliver the powdered activated carbon into the flue between the waste heat boiler and the bag filter; S43: Bag filter: The flue gas is dusted by a bag filter; S44: Wet desulfurization: SO2 and HCL in the flue gas are absorbed by the water in the spray slurry and separated from the flue gas; S5: Smoke emission: The smoke is introduced into the chimney and discharged into the air.

2. A sludge pyrolysis combustible gas incineration flue gas treatment process according to claim 1, characterized in that: The step S41 includes S411: Ammonia reducing agent is uniformly sprayed into the appropriate flue gas temperature range, and is rapidly decomposed in the furnace to react with NOx in the flue gas to generate N2 and H2O. The SNCR process does not require a catalyst. When the reaction temperature is too high, the decomposition of ammonia will reduce the NOx reduction rate; when the reaction temperature is too low, the escape of ammonia will increase, which will also reduce the NOx reduction rate.

3. The process for treating flue gas from pyrolysis of sludge and combustion of combustible gas according to claim 1, characterized in that: In step S42, during the period of feeding into the activated carbon bin, the air in the activated carbon bin is discharged to the outside through the filter bag and the exhaust pipe.

4. A sludge pyrolysis combustible gas incineration flue gas treatment process according to claim 3, characterized in that: In step S43, bag dust removal includes dust-containing gas entering the ash hopper of each chamber, using compressed air pulse cleaning, and maintaining good filtering performance for a long time through hot filter bags.

5. The process for treating flue gas from pyrolysis of sludge and combustion of combustible gas according to claim 1, characterized in that: The step S4 also includes S45: Flue gas supplementary combustion and heating: The flue gas temperature at the outlet of the gas heat exchanger needs to be heated from 175°C to 220°C.

6. The process for treating flue gas from pyrolysis of sludge and combustion of combustible gas according to claim 1, characterized in that: In step S44, the absorption slurry is collected in the absorption tower slurry pool, and the slurry at the bottom of the tower is forcedly oxidized.

7. A sludge pyrolysis combustible gas incineration flue gas treatment process according to claim 6, characterized in that: In the step S44, the gypsum generated after oxidation is discharged through the slurry discharge pump of the absorption tower, the mist droplets in the outlet flue gas are removed, and the limestone slurry is sprayed out from multiple nozzles on the main pipe in the absorption tower.

8. The process for treating flue gas from pyrolysis of sludge and combustion of combustible gas according to claim 1, characterized in that: In step S3, flue gas heat exchange is adopted: the high-temperature flue gas transfers heat to the external medium.

9. The process for treating flue gas from pyrolysis of sludge and combustion of combustible gas according to claim 1, characterized in that: In step S3, the waste heat of the flue gas is utilized, and the waste heat boiler is connected to the combustible gas incinerator. The high-temperature flue gas generated after the combustible gas is incinerated by the hot blast furnace enters the waste heat boiler to generate steam for recovering the heat generated by the incineration.

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