Smoke treatment system and method for treating both mud and haze

Abstract

The invention discloses a flue gas treatment system and method for treating both mud and haze, and belongs to the technical field of flue gas treatment. Sludge treatment and flue gas dust removal and deacidification are organically combined, and a brand-new flue gas treatment system is constructed. The special adsorption effect of the sludge flue gas heat exchange reaction is utilized to remove more than 60% of PM2.5 and other pollutants in the flue gas, so that the load of atmospheric pollutants in the original flue gas is reduced by 40-45%, and the overall dust removal and deacidification efficiency of the flue gas is improved by more than 40%. Compared with the prior art, the concentration of flue gas pollutants is effectively reduced, the abrasion and corrosion of equipment are reduced, and the service life of dust removal and deacidification equipment is prolonged by at least one third. According to the invention, an innovative mode of treating waste with waste and treating mud and haze together is adopted, so that energy consumption and resource investment are reduced, the condition of pure consumption of flue gas treatment is changed, the flue gas treatment cost is reduced by 30-40%, heat value equivalent to 1,500 thousand tons per year of standard coal can be saved and generated, carbon dioxide emission is reduced by 1,200 thousand tons per year, and both environmental and economic benefits are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas treatment, and particularly relates to a flue gas treatment system and method for jointly treating mud and haze. Background Art

[0002] Investigation and research show that PM discharged into the atmospheric environment through flue gas emissions 2.5 is the main cause of haze, and haze is the main inducing factor for the increase in the incidence of lung cancer in the population. Therefore, creating a new flue gas treatment system to block the PM 2.5 emissions in flue gas is the fundamental way to effectively control haze.

[0003] A large amount of sludge with complex components and great environmental harm will be generated during the purification of urban sewage and industrial wastewater.

[0004] Through a large number of basic researches and engineering practices, the inventor uses the waste heat of flue gas at 100 - 200 °C discharged from thermal power plants, waste incineration plants, cement plants, and boilers as the heat source, and adopts the method of directly contacting wet sludge with hot flue gas to dry the sludge. The moisture content of the sludge is reduced from 80% to 30%, the volume is reduced to less than one-third, and more than 95% of the original calorific value is preserved. The dried sludge particles can be used as auxiliary fuels or raw materials for cement production, etc. It not only overcomes the "energy consumption bottleneck" of sludge thermal drying, enables the sludge to be completely harmless and resourcefully treated, but also the alkaline sludge with strong adhesion characteristics can adsorb more than 60% of the PM 2.5 and more than 43% of the PM 10 ( Figure 1 ) in the flue gas, absorb 22 - 25% of sulfur dioxide, about 30% of nitrogen oxides, and 10 - 15% of carbon dioxide in the flue gas, and convert them into sulfates, nitrates, and carbonates, which will not be released again during resource utilization. The analysis results also show that the contents of sulfur, nitrogen, carbon, and hydrogen in the sludge dried by flue gas waste heat increase several times. The contents of sulfur and hydrogen increase by 65.2 times and 81.3 times respectively compared with the original sludge (Table 1). In addition, the contents of (heavy) metal elements in the sludge are also significantly increased compared with the original sludge, fully indicating that the direct contact of wet sludge with hot flue gas for heat exchange reaction purifies the flue gas, not only removes about 40 - 45% of the air pollutants in the flue gas, but also reduces the acidity of the flue gas by about 30 - 40%, and the air pollutants are greatly reduced, creating a prerequisite for significantly improving the dust removal and desulfurization efficiency of the flue gas.

[0005] Table 1 Changes in the contents of S, C, N, and H in the sludge before and after drying with flue gas waste heat

[0006] Element Raw sludge (%) Sludge after drying (%) Multiplication factor Sulfur (S) 0.011 0.728 65.2 Carbon (C) 0.369 5.610 14.2 Nitrogen (N) 0.069 0.810 10.7 Hydrogen (H) 0.070 5.759 81.3 Summary of the Invention

[0007] The object of the present invention is to solve the deficiencies of the prior art and provide a flue gas treatment system and method for co-governing mud and haze. The present invention will utilize the process of drying sludge with the waste heat of flue gas, and apply the unique removal effect on fine particulate matter (PM 2.5 ) to flue gas treatment, and construct a new flue gas treatment system with dust removal, desulfurization and denitrification, thereby making up for the technical defects of the existing flue gas treatment system. It not only significantly improves the efficiency of dust removal, desulfurization and denitrification, ensures high-standard flue gas emission, but also can significantly reduce the flue gas treatment cost and extend the service life of dust removal and desulfurization equipment.

[0008] The specific technical solutions adopted by the present invention are as follows:

[0009] In the first aspect, the present invention provides a flue gas treatment system for co-governing mud and haze, including high-temperature denitrification, a first induced draft fan, a ventilation duct, and a sludge-flue gas heat exchange reactor;

[0010] The sludge-flue gas heat exchange reactor includes a secondary cylinder and a main cylinder, and the main cylinder is coaxially nested outside the secondary cylinder, and an annular cavity is formed between the two cylinders; a plurality of lifting plates arranged along the circumferential direction of the secondary cylinder are provided on the inner wall of the secondary cylinder; a plurality of second sludge movement guide plates are provided on the outer wall of the secondary cylinder, and each second sludge movement guide plate extends from the rear end to the front end of the outer wall of the secondary cylinder in a spiral form; a first air inlet and a sludge feed port are provided at the front end of the secondary cylinder, and a first discharge port communicating with the main cylinder is provided at the rear end; the first air inlet receives the flue gas to be treated from waste incineration or coal combustion through the ventilation duct, and the sludge feed port is communicated with the underground sludge storage bin through a screw conveyor and a double-screw metering feeder;

[0011] A plurality of first sludge movement guide plates are provided on the inner wall of the main cylinder, and each first sludge movement guide plate extends from the rear end to the front end of the inner wall of the main cylinder in a spiral form and corresponds to the second sludge movement guide plate on the outer wall of the secondary cylinder; a second air inlet and a second discharge port are provided at the front end of the main cylinder; the main cylinder and the secondary cylinder are communicated at the rear end and provided with an air outlet; the second air inlet receives the flue gas to be treated from waste incineration or coal combustion through the ventilation duct, and the second discharge port is communicated with the sludge finished product warehouse through a closed conveyor belt; the inlet of the ventilation duct is communicated with the upstream flue gas to be treated through the first induced draft fan; the air outlet is connected to the deacidification, dust removal or dust removal, deacidification equipment through a pipeline in sequence, and finally connected to the chimney through the second induced draft fan.

[0012] Preferably, the diameter of the main cylinder is 4-5 meters and the length is 12-15 meters; the diameter of the secondary cylinder is 2-3 meters and the length is 12-15 meters; the secondary cylinder and the main cylinder are fixed by a plurality of support bars; the secondary cylinder and the main cylinder are driven by a driving device to rotate synchronously.

[0013] Preferably, a sludge disperser for dispersing the sludge feed is further provided near the sludge feed port inside the secondary cylinder.

[0014] Further, the inlet of the first induced draft fan is connected to the flue gas discharged from the waste incineration, which has been treated by high-temperature denitrification, through a pipeline provided with an electric gate valve; the outlet is sequentially connected to a first deacidification tower, a bag filter, a flue gas heat exchanger, a second deacidification tower, and a steam heat exchanger through pipelines, and finally connected to a chimney through a second induced draft fan.

[0015] Further, the inlet of the first induced draft fan is communicated with a multi-tube cyclone; the inlet of the multi-tube cyclone is connected to the flue gas discharged from the coal combustion, which has been treated by high-temperature denitrification, through a pipeline provided with an electric gate valve; the outlet is sequentially connected to a bag filter and a second deacidification tower through pipelines, and finally connected to a chimney through a second induced draft fan.

[0016] In a second aspect, the present invention provides a treatment method for jointly controlling mud and haze by using the above flue gas treatment system, and the specific steps are as follows:

[0017] S1: Perform high-temperature denitrification treatment on the flue gas discharged from the waste incineration. In the 850-1100 °C area of the waste heat boiler flue, spray ammonia water with a concentration of 20% through multiple injection layers composed of several spray guns, and carry out a reduction reaction with nitrogen oxides in the flue gas to generate N 2 and H 2 O, and at the same time, partially reflux the exhaust gas to inhibit the generation of nitrogen oxides;

[0018] S2: Store the sewage treatment plant sludge with a water content of 80% or more in the buried sludge storage bin; the sewage treatment plant sludge is separated into blocks by a double-screw metering feeder, and then conveyed to the sludge feed port of the sludge flue gas heat exchange reactor through a screw conveyor;

[0019] S3: The flue gas treated in step S1 sequentially passes through an electric gate valve and a first induced draft fan and enters the ventilation pipeline, and enters the secondary cylinder and the main cylinder of the sludge flue gas heat exchange reactor through a first air inlet and a second air inlet respectively, and performs a heat exchange reaction with the sludge; the sludge absorbs heat from the flue gas to evaporate water, and fine particulate matter, hydrogen chloride, sulfur dioxide, nitrogen oxides, carbon dioxide, and heavy metal elements in the flue gas are adsorbed or absorbed by the sludge;

[0020] S4: The flue gas after the heat exchange reaction in step S3 enters the first deacidification tower, bag filter, flue gas heat exchanger, second deacidification tower, and steam heat exchanger in sequence through the air outlet. In the first deacidification tower, the flue gas is subjected to semi-dry deacidification by spraying lime slurry. Subsequently, in the flue leading to the bag filter, activated carbon is injected to adsorb heavy metals and dioxins in the flue gas. At the outlet of the bag filter, the flue gas heat exchanger adjusts the temperature of the flue gas to the temperature required for wet deacidification. In the second deacidification tower, wet deacidification is carried out to remove residual acidic gases and dust particles through gas-liquid reaction. The liquid water in the flue gas is evaporated into water vapor by the steam heat exchanger to eliminate white smoke.

[0021] S5: The flue gas after deacidification and dust removal in step S4 is discharged from the chimney through the second induced draft fan. The sludge particles with a water content reduced to 40% or less and a natural particle size of 2 - 8 mm are discharged from the second discharge port and enter the sludge finished product warehouse for cooling through a closed conveyor belt.

[0022] The present invention also provides a treatment method for jointly controlling mud and haze using the above flue gas treatment system, and the specific steps are as follows:

[0023] S1: The coal-fired flue gas is subjected to high-temperature denitrification treatment. In a furnace at 850 - 1100 °C, ammonia water with a concentration of 25% is sprayed through multiple injection layers composed of several spray guns to carry out a reduction reaction with nitrogen oxides in the flue gas to generate N 2 and H 2 O.

[0024] S2: Sewage treatment plant sludge with a water content of 80% or more is stored in the buried sludge storage bin. The sewage treatment plant sludge is divided into blocks by a double-screw metering feeder and then transported to the sludge feed port of the sludge flue gas heat exchanger through a screw conveyor.

[0025] S3: The flue gas after being treated in step S1 is controlled for flow rate by an electric gate valve and enters a multi-tube cyclone dust collector to remove particulate matter with a particle size ≥ PM 10 in the flue gas. The preliminarily dust-removed flue gas enters the ventilation duct through the first induced draft fan and enters the secondary cylinder and main cylinder of the sludge flue gas heat exchanger through the first air inlet and the second air inlet respectively to carry out a heat exchange reaction with the sludge. The sludge absorbs heat from the flue gas to evaporate water, and fine particulate matter, hydrogen chloride, sulfur dioxide, nitrogen oxides, carbon dioxide, and heavy metal elements in the flue gas are adsorbed or absorbed by the sludge.

[0026] S4: The flue gas after the heat exchange reaction in step S3 enters the bag filter through the air outlet. After the particulate matter in the flue gas is filtered out by the bag filter, it enters the second deacidification tower for wet deacidification, and residual acidic gases and dust particles are removed through gas-liquid reaction.

[0027] S5: The flue gas after acid removal and dust removal in step S4 passes through the second induced draft fan and is discharged from the chimney; the moisture content drops to 40% or less and sludge particles with a particle size of 2 - 8 mm are naturally formed and discharged from the second discharge port, and enter the sludge finished product warehouse for cooling through a closed conveyor belt.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention innovatively combines sludge treatment with flue gas acid removal and dust removal, adopts the strategy of "treating waste with waste and jointly controlling mud and haze", and realizes the harmless and resourceful treatment of sludge without consuming new resources and adding additional energy consumption. By pre-treating the flue gas through a sludge flue gas heat exchange reactor, more than 60% of PM in the flue gas can be removed 2.5 and other pollutants, significantly reducing the emission of air pollutants.

[0030] (2) The present invention optimizes the traditional flue gas treatment process, changing the original flue gas treatment mode of "SNCR (high-temperature denitrification) + acid removal + dust removal" or "SNCR + dust removal + acid removal" to the mode of SNCR + pre-treatment (sludge flue gas heat exchange) + acid removal + dust removal (or SNCR + pre-treatment + dust removal + acid removal). The sludge flue gas heat exchange, which is equivalent to the pre-treatment of the flue gas, can reduce the air pollutant load in the original flue gas by 40 - 45%, and improve the overall dust removal and acid removal efficiency of the flue gas by more than 40%, thus ensuring the up-to-standard discharge of various pollutants in the flue gas.

[0031] (3) Compared with the traditional flue gas treatment system, the present invention effectively reduces the concentration of flue gas pollutants, reduces equipment wear and corrosion, and extends the service life of the dust removal and acid removal equipment by at least one-third through optimizing the process and adding a pre-treatment link. At the same time, the innovative mode reduces energy consumption and resource input, not only reducing the flue gas treatment cost by 30% - 40%, but also reducing carbon dioxide emissions by 12.29 million tons / year, with both environmental and economic benefits. Description of the Drawings

[0032] Figure 1 Scanning electron microscope images before and after drying sludge with flue gas, where A is the original flue gas; B is the flue gas after drying sludge with a moisture content of 53%; C is the flue gas after drying sludge with a moisture content of 63%; D is the flue gas after drying sludge with a moisture content of 73%

[0033] Figure 2 Schematic diagram of a flue gas treatment system for jointly controlling mud and haze provided in Embodiment 1;

[0034] Figure 3 Schematic diagram of a flue gas treatment system for jointly controlling mud and haze provided in Embodiment 2;

[0035] In the figure: flue gas discharged from waste incineration 1, high-temperature denitrification 2, electric gate valve 3, first induced draft fan 4, first air inlet 5, ventilation duct 6, sludge feed inlet 7, second air inlet 8, secondary cylinder 9, main cylinder 10, sludge-gas heat exchange reactor 11, material lifting plate 12, sludge disperser 13, first sludge movement guiding plate 14, second sludge movement guiding plate 15, first discharge port 16, air outlet 17, first deacidification tower 18, bag filter 19, gas-gas heat exchanger 20, second deacidification tower 21, steam heat exchanger 22, second induced draft fan 23, screw conveyor 24, double-screw metering feeder 25, underground sludge storage bin 26, second discharge port 27, enclosed conveyor belt 28, sludge finished product warehouse 29, chimney 30, flue gas discharged from coal combustion 31, multi-tube cyclone dust collector 32. Detailed implementation mode

[0036] The present invention will be further described and illustrated below in conjunction with the accompanying drawings and the detailed implementation mode. The technical features of each implementation mode in the present invention can be combined correspondingly on the premise of not conflicting with each other.

[0037] Embodiment 1

[0038] As Figure 1 shown, this embodiment provides a flue gas treatment system for jointly controlling mud and haze. The flue gas treatment system includes flue gas discharged from waste incineration 1, high-temperature denitrification 2, electric gate valve 3, first induced draft fan 4, ventilation duct 6, sludge-gas heat exchange reactor 11, first deacidification tower 18, bag filter 19, gas-gas heat exchanger 20, second deacidification tower 21, steam heat exchanger 22, second induced draft fan 23, screw conveyor 24, double-screw metering feeder 25, underground sludge storage bin 26, enclosed conveyor belt 28, sludge finished product warehouse 29 and chimney 30. The sludge-gas heat exchange reactor 11 includes a secondary cylinder 9, a main cylinder 10, a material lifting plate 12, a sludge disperser 13, a first sludge movement guiding plate 14 and a second sludge movement guiding plate 15.

[0039] In the sludge-gas heat exchange reactor 11 provided in this embodiment, the main cylinder 10 is coaxially nested outside the secondary cylinder 9, and an annular cavity is formed between the two cylinders. The diameter of the main cylinder 10 is 5 meters and the length is 15 meters. The diameter of the secondary cylinder 9 is 3 meters and the length is 15 meters. The secondary cylinder 9 and the main cylinder 10 are fixed by a plurality of support bars. The secondary cylinder 9 and the main cylinder 10 are driven by a driving device to rotate synchronously.

[0040] On the inner wall of the secondary cylinder body 9, there are several material lifting plates 12 arranged along the circumferential direction of the secondary cylinder body 9. On the outer wall of the secondary cylinder body 9, several second sludge movement guiding plates 15 are provided, and each second sludge movement guiding plate 15 extends from the rear end to the front end of the outer wall of the secondary cylinder body 9 in a spiral form. At the front end of the secondary cylinder body 9, there are a first air inlet 5 and a sludge feed inlet 7, and at the rear end, there is a first discharge port 16 communicating with the main cylinder body 10. Near the sludge feed inlet 7 in the secondary cylinder body 9, there is also a sludge disperser 13 for dispersing the sludge feed. The first air inlet 5 receives the flue gas to be treated from the garbage incineration emission through a ventilation duct 6, and the sludge feed inlet 7 is communicated with the buried sludge storage bin 26 through a screw conveyor 24 and a double-screw metering feeder 25.

[0041] On the inner wall of the main cylinder body 10, several first sludge movement guiding plates 14 are provided, and each first sludge movement guiding plate 14 extends from the rear end to the front end of the inner wall of the main cylinder body 10 in a spiral form and corresponds to the second sludge movement guiding plate 15 on the outer wall of the secondary cylinder body 9. At the front end of the main cylinder body 10, there are a second air inlet 8 and a second discharge port 27. The main cylinder body 10 and the secondary cylinder body 9 are communicated at the rear end and are provided with an air outlet 17. The second air inlet 8 receives the flue gas to be treated from the garbage incineration emission through a ventilation duct 6, and the second discharge port 27 is communicated with the sludge finished product warehouse 29 through an enclosed conveyor belt 28.

[0042] In this embodiment, the inlet of the first induced draft fan 4 is connected through a pipeline provided with an electric gate valve 3 to the flue gas 1 from the garbage incineration emission after high-temperature denitrification 2 treatment. The air outlet 17 is sequentially connected through pipelines to a first deacidification tower 18, a bag filter 19, a flue gas heat exchanger 20, a second deacidification tower 21, a steam heat exchanger 22, and finally connected to a chimney 30 through a second induced draft fan 23.

[0043] This embodiment also provides a method for jointly treating mud and haze using the above flue gas treatment system, and the specific steps are as follows:

[0044] S1: Perform high-temperature denitrification 2 treatment on the flue gas 1 from the garbage incineration emission. In the 850 - 1100 °C area of the waste heat boiler flue, spray ammonia water with a concentration of 20% through multiple spraying layers composed of several spray guns, and perform a reduction reaction with the nitrogen oxides in the flue gas to generate N 2 and H 2 O, and at the same time, partially return the exhaust gas to inhibit the generation of nitrogen oxides.

[0045] S2: Store the sewage treatment plant sludge with a water content accounting for 80% of the total weight mass percentage in the buried sludge storage bin 26. After the sewage treatment plant sludge is separated into blocks by a double-screw metering feeder 25, it is then evenly and continuously conveyed to the sludge feed inlet 7 of the sludge flue gas heat exchange reactor 11 through a screw conveyor 24 and enters the secondary cylinder body 9.

[0046] S3: After the high-temperature denitrification 2 and flue gas recirculation denitrification treatment in step S1, the flue gas at 200 °C first passes through the electric gate valve 3, and the flue gas flow is controlled by adjusting the opening degree of the damper. Then it enters the ventilation duct 6 through the first induced draft fan 4. At the outlet of the ventilation duct 6, the flue gas enters the secondary cylinder 9 and the main cylinder 10 of the sludge flue gas heat exchange reactor 11 through the first air inlet 5 and the second air inlet 8 respectively, mixes with the sludge, and under the condition that the sludge input amount and the flue gas input amount are synchronously matched, a heat exchange reaction is carried out.

[0047] Driven by the driving device, the secondary cylinder 9 and the main cylinder 10 rotate clockwise continuously at a set speed. Inside the secondary cylinder 9, the sludge is dispersed into smaller lumps under the combined action of the sludge disperser 13 and the lifting plate 12, so that the wet sludge and the hot flue gas are in full contact. The sludge absorbs heat from the flue gas, evaporates water, and adsorbs 60.12% of PM 2.5 and 43.79% of PM 10 fine particulate matter in the flue gas, absorbs 37.8% of hydrogen chloride, 23.5% of sulfur dioxide, 30.2% of nitrogen oxides, 13.2% of carbon dioxide and other pollutants in the flue gas, and wraps them in the sludge particles.

[0048] Inside the secondary cylinder 9, the sludge moves gradually from the front end to the rear end. When the moisture content of the sludge drops to 61%, it enters the main cylinder 10 from the first discharge port 16 at the rear end. In the annular cavity between the main cylinder 10 and the secondary cylinder 9, the sludge falling from the secondary cylinder 9 is under the combined action of the first sludge movement guide plate 14 on the inner wall of the main cylinder 10 and the second sludge movement guide plate 15 on the outer wall of the secondary cylinder 9. During the process of moving from the rear end to the front end, it continues to carry out a heat exchange reaction with the hot flue gas. When the moisture content of the sludge drops to 40% and sludge particles with a particle size of 2 - 8 mm are naturally formed, they are output from the second discharge port 27 at the bottom of the front end and sent to the sludge finished product warehouse 29 by the closed conveyor belt 28 for self-cooling. When the sludge particles are cooled to room temperature, the moisture content drops to 30%, the volume is reduced to less than one-third of the original volume, and more than 95% of the original calorific value is preserved, and they are co-fired with garbage for power generation. Since the sulfur dioxide, nitrogen oxides and carbon dioxide absorbed in the sludge particles have been converted into sulfate, nitrate and carbonate respectively, they will not be released again during co-firing with garbage.

[0049] S4: After the heat exchange reaction in step S3, 43% of the pollutants in the flue gas are removed by the sludge. The flue gas passes through the air outlet 17 and then enters the first deacidification tower 18, bag filter 19, flue gas heat exchanger 20, second deacidification tower 21 and steam heat exchanger 22 in sequence. In the first deacidification tower 18, a chemical reaction is carried out between the sprayed lime slurry and sulfur dioxide in the flue gas to generate CaSO 4, after semi-dry desulfurization, 90% of the acidic gases in the flue gas are removed, and then dust removal treatment is carried out. Subsequently, the flue gas is sent into the flue of the bag filter 19, and activated carbon is injected to adsorb heavy metals and dioxins in the flue gas. After passing through the bag filter 19, more than 99% of the soot is filtered, and the temperature of the flue gas is adjusted to the temperature required for wet desulfurization through the flue gas heat exchanger 20 at the outlet of the bag filter 19. The temperature-adjusted flue gas enters the second desulfurization tower 21 from the lower part, and wet desulfurization is carried out in the second desulfurization tower 21. Inside the tower, a gas-liquid reaction is carried out with the wet limestone slurry to remove residual acidic gases and dust particles, not only making the pollutants in the flue gas meet the "Pollutant Control Standards for Municipal Solid Waste Incineration" (GB18485-2014), but also fully meeting the EU emission standards (EU2010 / 75 / EC). Finally, the liquid water in the flue gas is evaporated into water vapor through the steam heat exchanger 22 to eliminate white smoke.

[0050] S5: The flue gas after desulfurization and dust removal in step S4 passes through the second induced draft fan 23 and is discharged from the chimney 30.

[0051] Example 2

[0052] As Figure 2 shown, this embodiment provides a flue gas treatment system for jointly controlling mud and haze. The system includes coal-fired flue gas 31, high-temperature denitration 2, electric gate valve 3, first induced draft fan 4, ventilation duct 6, sludge flue gas heat exchange reactor 11, bag filter 19, second desulfurization tower 21, second induced draft fan 23, screw conveyor 24, double-screw metering feeder 25, underground sludge storage bin 26, enclosed conveyor belt 28, sludge finished product warehouse 29 and chimney 30, where the sludge flue gas heat exchange reactor 11 includes a secondary cylinder 9, a main cylinder 10, a material lifting plate 12, a sludge disperser 13, a first sludge moving guide plate 14 and a second sludge moving guide plate 15.

[0053] In the sludge flue gas heat exchange reactor 11 provided in this embodiment, the main cylinder 10 is coaxially nested outside the secondary cylinder 9, and an annular cavity is formed between the two cylinders. The diameter of the main cylinder 10 is 4.5 meters and the length is 14 meters. The diameter of the secondary cylinder 9 is 2.5 meters and the length is 14 meters. The secondary cylinder 9 and the main cylinder 10 are fixed by several support bars. The secondary cylinder 9 and the main cylinder 10 are driven by a driving device to rotate synchronously.

[0054] On the inner wall of the secondary cylinder 9, there are several material-lifting plates 12 arranged circumferentially along the secondary cylinder 9. On the outer wall of the secondary cylinder 9, there are several second sludge movement guiding plates 15, and each second sludge movement guiding plate 15 extends from the rear end to the front end of the outer wall of the secondary cylinder 9 in a spiral form. At the front end of the secondary cylinder 9, there are a first air inlet 5 and a sludge feed inlet 7, and at the rear end, there is a first discharge outlet 16 communicating with the main cylinder 10. Near the sludge feed inlet 7 in the secondary cylinder 9, there is also a sludge disperser 13 for dispersing the sludge feed. The first air inlet 5 receives the flue gas to be treated from coal combustion emissions through a ventilation duct 6, and the sludge feed inlet 7 is connected to the buried sludge storage bin 26 through a screw conveyor 24 and a double-screw metering feeder 25.

[0055] On the inner wall of the main cylinder 10, there are several first sludge movement guiding plates 14, and each first sludge movement guiding plate 14 extends from the rear end to the front end of the inner wall of the main cylinder 10 in a spiral form and corresponds to the second sludge movement guiding plate 15 on the outer wall of the secondary cylinder 9. At the front end of the main cylinder 10, there are a second air inlet 8 and a second discharge outlet 27. The main cylinder 10 and the secondary cylinder 9 are connected at the rear end and there is an air outlet 17. The second air inlet 8 receives the flue gas to be treated from coal combustion emissions through a ventilation duct 6, and the second discharge outlet 27 is connected to the sludge finished product warehouse 29 through an enclosed conveyor belt 28.

[0056] In this embodiment, the inlet of the first induced draft fan 4 is connected to a multi-tube cyclone dust collector 32. The inlet of the multi-tube cyclone dust collector 32 is connected to the coal combustion flue gas 31 after high-temperature denitrification 2 through a pipeline provided with an electric gate valve 3. The air outlet 17 is connected to a bag filter 19 and a second deacidification tower 21 in sequence through a pipeline, and finally is connected to a chimney 30 through a second induced draft fan 23.

[0057] This embodiment also provides a treatment method for jointly treating mud and haze using the above flue gas treatment system, and the specific steps are as follows:

[0058] S1: Perform high-temperature denitrification 2 on the coal combustion flue gas 31. In a furnace at 850 - 1100 °C, spray ammonia water with a concentration of 25% through multiple spraying layers composed of several spray guns into the flue gas, and perform a reduction reaction with nitrogen oxides in the flue gas to generate N 2 and H 2 O.

[0059] S2: Store the sewage treatment plant sludge with a water content accounting for 81% of the total weight mass percentage in the buried sludge storage bin 26. After the sewage treatment plant sludge is separated into blocks by a double-screw metering feeder 25, it is then evenly and continuously conveyed to the sludge feed inlet 7 of the sludge flue gas heat exchange reactor 11 through a screw conveyor 24 and enters the secondary cylinder 9.

[0060] S3: After the high-temperature denitrification treatment in step S1, the flue gas at 150 °C first passes through the electric gate valve 3, and the flue gas flow rate is controlled by adjusting the opening degree of the damper. Then, it passes through the multi-tube cyclone dust collector 32 to remove the particulate matter with a particle size ≥ PM 10 in the flue gas. Finally, it enters the ventilation duct 6 through the first induced draft fan 4. At the outlet of the ventilation duct 6, the flue gas enters the secondary cylinder 9 and the main cylinder 10 of the sludge flue gas heat exchange reactor 11 through the first air inlet 5 and the second air inlet 8 respectively, mixes with the sludge, and under the condition that the sludge input amount and the flue gas input amount are synchronously matched, a heat exchange reaction is carried out.

[0061] Driven by the driving device, the secondary cylinder 9 and the main cylinder 10 rotate continuously in the clockwise direction at a set speed. Inside the secondary cylinder 9, the sludge is dispersed into smaller blocks under the combined action of the sludge disperser 13 and the lifting plate 12, so that the wet sludge and the hot flue gas are in full contact. While the sludge absorbs heat from the flue gas to evaporate water, it adsorbs 60.16% of PM 2.5 and 43.99% of PM 10 fine particulate matter in the flue gas, absorbs 35.6% of hydrogen chloride, 25.2% of sulfur dioxide, 30.5% of nitrogen oxides, 15.1% of carbon dioxide and other pollutants in the flue gas, and wraps them in the sludge particles.

[0062] Inside the secondary cylinder 9, the sludge moves gradually from the front end to the rear end. When the water content of the sludge drops to 60%, it enters the main cylinder 10 from the first discharge port 16 at the rear end. In the annular cavity between the main cylinder 10 and the secondary cylinder 9, the sludge falling from the secondary cylinder 9 is under the combined action of the first sludge movement guide plate 14 on the inner wall of the main cylinder 10 and the second sludge movement guide plate 15 on the outer wall of the secondary cylinder 9. During the process of moving from the rear end to the front end, it continues to carry out a heat exchange reaction with the hot flue gas. When the water content of the sludge drops to 39% and sludge particles with a particle size of 2 - 8 mm are naturally formed, they are output from the second sludge discharge port 27 at the bottom of the front end and sent to the sludge finished product warehouse 29 by the closed conveyor belt 28 for self-cooling. When the sludge particles are cooled to room temperature, the water content drops to 29%, the volume is reduced to less than one-third of the original volume, and more than 95% of the original calorific value is preserved, which can be used as an auxiliary fuel for coal combustion (or can also be used as a raw material for cement production). Since the sulfur dioxide, nitrogen oxides and carbon dioxide absorbed in the sludge particles have been respectively converted into sulfates, nitrates and carbonates, they will not be released again when co-fired with coal.

[0063] S4: After the heat exchange reaction in step S3, 44% of the pollutants in the flue gas are removed by the sludge. The flue gas enters the bag filter 19 through the air outlet 17. After more than 99% of the soot in the flue gas is filtered, it enters the second deacidification tower 21 from the lower part for wet deacidification. Inside the second deacidification tower 21, sulfur dioxide reacts with the wet limestone slurry in a gas-liquid reaction to generate CaSO4 , removing acid gases and residual dust particles to make the pollutants in the flue gas meet the Emission Standard of Air Pollutants for Boilers (DB33 / 1415 - 2015).

[0064] S5: The flue gas after acid removal and dust removal in step S4 passes through the second induced draft fan 23 and is discharged from the chimney 30.

[0066] The above embodiments are only a preferred solution of the present invention, but they are not intended to limit the present invention. Those of ordinary skill in the relevant technical field can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A flue gas treatment system for controlling mud and haze, characterized in that: It comprises a high-temperature denitrification device (2), a first induced draft fan (4), a ventilation duct (6), and a sludge flue gas heat exchange reactor (11); The sludge flue gas heat exchange reactor (11) comprises a secondary cylinder (9) and a main cylinder (10), wherein the main cylinder (10) is coaxially nested outside the secondary cylinder (9), and an annular cavity is formed between the two cylinders; a plurality of lifting plates (12) arranged along the circumference of the secondary cylinder (9) are provided on the inner wall of the secondary cylinder (9); a plurality of second sludge moving guide plates (15) are provided on the outer wall of the secondary cylinder (9), and each second sludge moving guide plate (15) is spirally extended from the secondary cylinder to the outside of the secondary cylinder. (9) The rear end of the outer wall extends toward the front end; the front end of the secondary cylinder (9) is provided with a first air inlet (5) and a sludge feed port (7), and the rear end is provided with a first discharge port (16) connected to the main cylinder (10); the first air inlet (5) receives the flue gas to be treated from garbage incineration or coal combustion through a ventilation duct (6), and the sludge feed port (7) is connected to an underground sludge storage bin (26) through a screw conveyor (24) and a double screw quantitative feeder (25); The inner wall of the main cylinder (10) is provided with a plurality of first sludge moving guide plates (14), each of which extends in a spiral form from the rear end to the front end of the inner wall of the main cylinder (10) and corresponds to the second sludge moving guide plate (15) on the outer wall of the secondary cylinder (9); the front end of the main cylinder (10) is provided with a second air inlet (8) and a second material outlet (27); the rear ends of the main cylinder (10) and the secondary cylinder (9) are connected and are provided with an air outlet (17); The second air inlet (8) receives the flue gas to be treated emitted from garbage incineration or coal combustion through the ventilation duct (6), and the second discharge port (27) is connected to the sludge finished product warehouse (29) through a closed conveyor belt (28); the inlet of the ventilation duct (6) is connected to the flue gas to be treated through the first induced draft fan (4); the air outlet (17) is connected to the deacidification, dust removal or dust removal and deacidification equipment in sequence through the pipeline, and finally connected to the chimney (30) through the second induced draft fan (23).

2. The flue gas treatment system for mud and haze control according to claim 1 is characterized in that: The main cylinder (10) has a diameter of 4 to 5 meters and a length of 12 to 15 meters; the secondary cylinder (9) has a diameter of 2 to 3 meters and a length of 12 to 15 meters; the secondary cylinder (9) and the main cylinder (10) are fixed by a plurality of support bars; the secondary cylinder (9) and the main cylinder (10) are driven by a driving device and rotate synchronously.

3. The flue gas treatment system for mud and haze control according to claim 1 is characterized in that: A sludge disperser (13) for dispersing the sludge feed is also provided in the secondary cylinder (9) near the sludge feed port (7).

4. The flue gas treatment system for mud and haze control according to claim 1 is characterized in that: The inlet of the first induced draft fan (4) is connected to the waste incineration flue gas (1) after high-temperature denitration (2) treatment through a pipeline provided with an electric gate valve (3); the gas outlet (17) is connected to the first deacidification tower (18), the bag filter (19), the flue gas heat exchanger (20), the second deacidification tower (21), the steam heat exchanger (22) in sequence through pipelines, and is finally connected to the chimney (30) through the second induced draft fan (23).

5. The flue gas treatment system for mud and haze control according to claim 1 is characterized in that: The inlet of the first induced draft fan (4) is connected to the multi-cyclone dust collector (32); the inlet of the multi-cyclone dust collector (32) is connected to the coal-fired exhaust gas (31) after high-temperature denitration (2) treatment through a pipeline provided with an electric gate valve (3); the gas outlet (17) is connected to the bag filter (19) and the second deacidification tower (21) in sequence through a pipeline, and finally connected to the chimney (30) through the second induced draft fan (23).

6. A method for treating sludge and haze by using the flue gas treatment system according to claim 4, characterized in that: The specific steps are as follows: S1: subjecting waste incineration flue gas (1) to high-temperature denitrification (2): in the 850-1100°C region of the waste heat boiler flue, ammonia water with a concentration of 20% is sprayed through multiple spray layers consisting of a plurality of spray guns to react with nitrogen oxides in the flue gas to generate N2 and H2O, and at the same time, part of the exhaust gas is refluxed to inhibit the generation of nitrogen oxides; S2: The buried sludge storage bin (26) is filled with sludge from a sewage treatment plant having a moisture content of 80% or more; the sludge from the sewage treatment plant is separated into blocks by a double-screw quantitative feeder (25), and then transported to the sludge feed port (7) of the sludge-flue gas heat exchange reactor (11) by a screw conveyor (24); S3: The flue gas treated in step S1 passes through the electric gate valve (3) and the first induced draft fan (4) in sequence and then enters the ventilation duct (6), and respectively enters the secondary cylinder (9) and the main cylinder (10) of the sludge flue gas heat exchange reactor (11) through the first air inlet (5) and the second air inlet (8), and undergoes a heat exchange reaction with the sludge; the sludge absorbs heat from the flue gas to evaporate water, and the micro-particles, hydrogen chloride, sulfur dioxide, nitrogen oxides, carbon dioxide and heavy metal elements in the flue gas are adsorbed or absorbed by the sludge; S4: After the heat exchange reaction in step S3, the flue gas passes through the gas outlet (17) and enters the first deacidification tower (18), the bag filter (19), the flue gas heat exchanger (20), the second deacidification tower (21) and the steam heat exchanger (22) in sequence; in the first deacidification tower (18), the flue gas is semi-dry deacidified by spraying lime slurry; then the flue gas is sent to the flue of the bag filter (19), and activated carbon is sprayed to adsorb heavy metals and dioxins in the flue gas; at the outlet of the bag filter (19), the flue gas heat exchanger (20) adjusts the flue gas to the temperature required for wet deacidification; wet deacidification is carried out in the second deacidification tower (21), and residual acidic gases and dust particles are removed through gas-liquid reaction; liquid water in the flue gas is evaporated into water vapor through the steam heat exchanger (22) to eliminate white smoke; S5: After the deacidification and dust removal in step S4, the flue gas passes through the second induced draft fan (23) and is discharged from the chimney (30); the sludge particles with a moisture content of 40% or less and naturally formed into a particle size of 2-8 mm are discharged from the second discharge port (27) and enter the sludge finished product warehouse (29) for cooling through the closed conveyor belt (28).

7. A method for treating sludge and haze by using the flue gas treatment system according to claim 5, characterized in that: The specific steps are as follows: S1: subjecting the flue gas (31) emitted from coal combustion to high-temperature denitrification (2): in a furnace at 850-1100°C, ammonia water with a concentration of 25% is sprayed into the furnace through a plurality of spray layers consisting of a plurality of spray guns to react with nitrogen oxides in the flue gas to generate N2 and H2O; S2: The buried sludge storage bin (26) is filled with sludge from a sewage treatment plant having a moisture content of 80% or more; the sludge from the sewage treatment plant is separated into blocks by a double-screw quantitative feeder (25), and then transported to the sludge feed port (7) of the sludge-flue gas heat exchange reactor (11) by a screw conveyor (24); S3: The flue gas treated in step S1 is controlled by the electric gate valve (3) and enters the multi-cyclone dust collector (32) to remove particles ≥PM in the flue gas. 10 The flue gas after preliminary dust removal enters the ventilation duct (6) through the first induced draft fan (4), and enters the secondary cylinder (9) and the main cylinder (10) of the sludge flue gas heat exchange reactor (11) through the first air inlet (5) and the second air inlet (8) respectively, and undergoes a heat exchange reaction with the sludge; the sludge absorbs heat from the flue gas to evaporate water, and the micro-particles, hydrogen chloride, sulfur dioxide, nitrogen oxides, carbon dioxide and heavy metal elements in the flue gas are adsorbed or absorbed by the sludge; S4: The flue gas after the heat exchange reaction in step S3 passes through the gas outlet (17) and enters the bag filter (19). After the bag filter removes the particulate matter in the flue gas, it enters the second deacidification tower (21) for wet deacidification. The residual acid gas and dust particles are removed through gas-liquid reaction. S5: The flue gas after dust removal and deacidification in step S4 is discharged from the chimney (30) through the second induced draft fan (23); the sludge particles with a moisture content of 40% or less and naturally formed into particles with a diameter of 2-8 mm are discharged from the second discharge port (27) and enter the sludge finished product warehouse (29) for cooling through the closed conveyor belt (28).

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