Sludge incineration process and system

Abstract

The present application relates to a kind of sludge incineration process and system, the sludge incineration system includes incinerator, SNCR denitration reactor, high-temperature pulse bag-type dust collector, flue gas heat exchanger, sludge drying tower, medium-low temperature sludge catcher, water washing tower, alkali washing tower and absorption-desorption tower;By optimizing process, shorten the process flow, and all process flow is closed operation, eliminate the possibility of sludge and atmosphere contact in the process of equipment operation, fundamentally solve the problem of odor overflow;Using gas, sludge mixed injection direct combustion process, overcome the low calorific value of sludge, improve the combustion efficiency, make sludge completely burn, and completely solve the problem of circulating ash superposition;System operation is stable, while reducing operation, maintenance cost and equipment cost, conducive to large-scale popularization and application;Denitration process sets special reaction vessel, improves the treatment efficiency of flue gas NOx and odor pollutants, to ensure that reach emission standard.

Description

Technical Field

[0001] This invention relates to the field of sludge harmless treatment technology, and in particular to a sludge incineration process and system. Background Technology

[0002] Sludge incineration is a treatment technology that converts organic matter in sludge into carbon dioxide, water, and ash through high-temperature combustion. This treatment can effectively reduce sludge volume, kill pathogens, and recover energy. The main processes of sludge incineration include: (1) Pretreatment: reducing the water content of sludge through dewatering (usually to below 80%) and further reducing moisture through drying to improve combustion efficiency. (2) Incineration: burning sludge at high temperatures to decompose organic matter and using the heat generated by incineration to generate electricity or heat to recover energy. (3) Tail gas treatment: removing particulate matter from flue gas through dust removal, reducing sulfur oxides and nitrogen oxides emissions through desulfurization and denitrification, and treating harmful substances (including heavy metals and dioxins) through activated carbon adsorption and other methods. (4) Ash treatment: collecting the ash produced after incineration for landfilling or use as building materials.

[0003] Currently, the main processes of conventional sludge direct drying and incineration are as follows:

[0004] 1) Sludge Treatment Path: Sludge is pumped to a sludge drying tower, where it is atomized by a two-fluid spray gun and then dried. Part of the dried sludge is discharged from the bottom of the drying tower to a scraper conveyor, while the other part is discharged with the flue gas from the drying tower and enters a sludge separator and a primary bag filter. The sludge separator and the primary bag filter intercept the sludge and discharge it into the scraper conveyor. The scraper conveyor sends the sludge discharged from the drying tower, sludge separator, and primary bag filter to a rotary kiln for incineration. The slag produced by the rotary kiln incineration is discharged from the kiln tail, and the generated ash enters the flue gas side of the flue gas system.

[0005] 2) Flue gas treatment path: Air drawn from each storage tank and odor removal point is sent to the rotary kiln by a primary blower to participate in the combustion process (temperature about 650℃) as a combustion-supporting gas. The flue gas generated by the rotary kiln enters the secondary combustion chamber and is heated to above 850℃ by natural gas combustion support, with a residence time of not less than 2 seconds to decompose any dioxins that may be generated. The flue gas at the outlet of the secondary combustion chamber is mixed with cold flue gas drawn from the chimney to cool it down to below 650℃ and then enters the drying tower, where it exchanges heat with the sludge atomized by the dual-fluid spray gun, and the temperature drops to below 110℃. The flue gas discharged from the drying tower enters the sludge remover, the primary bag filter (equipped with activated carbon), the secondary bag filter (equipped with ozone), and the induced draft fan in sequence. After the tertiary acid removal (stage 1 water washing + stage 2 alkaline washing) and whitening (air cooling + mixing), it is discharged through the chimney.

[0006] The main problems with the above-mentioned direct sludge drying and incineration process are:

[0007] 1) The process system is equipped with scraper conveyors, chutes and other equipment, which causes materials to be exposed and generate odors in the plant;

[0008] 2) The rotary kiln has low combustion efficiency, and the sludge cannot fully contact the air, resulting in incomplete combustion of the sludge and a high loss on ignition rate of the ash.

[0009] 3) There is a problem of ash accumulation. The fly ash produced by combustion is captured by the dust collector and then sent to the rotary kiln for secondary combustion. After combustion, it enters the flue gas system again. This cycle repeats itself, accumulating more and more, eventually causing the combustion system to be overwhelmed, the regulation system to become disordered, and combustion to be unable to proceed smoothly.

[0010] 4) The flue gas temperature after drying is much lower than the acid dew point, so acid corrosion needs to be considered. The drying tower and dust collector need to use corrosion-resistant steel such as 2205 steel, and a release agent needs to be added in the rotary kiln, resulting in high operating costs, maintenance costs and equipment costs.

[0011] 5) After direct drying, the flue gas carries VOCs, nitrogen oxides, etc., which need to be deodorized and denitrified. Deodorization and denitrification are generally carried out by direct pipeline injection without reaction containers, which leads to uneven reaction, high escape rate of deodorizing and denitrifying agents, and difficulty in meeting emission standards after purification. The odor outside the factory area is strong, which causes complaints from nearby residents. Summary of the Invention

[0012] This invention provides a sludge incineration process and system. By optimizing the process, the process flow is shortened, and the entire process operates in a closed loop, eliminating the possibility of sludge contact with the atmosphere during equipment operation and fundamentally solving the problem of odor leakage. The invention employs a direct combustion process involving a mixture of fuel gas and sludge, overcoming the disadvantage of low calorific value in sludge, improving combustion efficiency, ensuring complete combustion of the sludge, and thoroughly resolving the problem of ash accumulation. The system operates stably, while reducing operating and maintenance costs and equipment costs, facilitating large-scale application. A dedicated reaction vessel is used in the denitrification process to improve the efficiency of NOx and odor pollutant treatment in flue gas, ensuring compliance with emission standards.

[0013] To achieve the above objectives, the present invention employs the following technical solution:

[0014] A sludge incineration process includes the following steps:

[0015] 1) Sludge treatment process: Sludge is sent to the upper part of the sludge drying tower, atomized by a dual-fluid spray gun, and dehydrated after contact with the hot flue gas at the inlet of the sludge drying tower; part of the dried sludge falls to the bottom of the sludge drying tower, and the other part is discharged from the sludge drying tower with the cold flue gas and enters the medium and low temperature sludge capture device; the sludge intercepted by the medium and low temperature sludge capture device and the sludge collected by the sludge drying tower are respectively sent to the burner at the top of the incinerator through the sludge pneumatic conveying device, and then mixed with natural gas and hot air for incineration; the slag produced by incineration is discharged from the bottom of the furnace, and the fly ash produced by incineration is denitrified by the SNCR denitrification reactor and then enters the high temperature pulse bag dust collector; the intercepted fly ash falls into the bottom ash hopper;

[0016] 2) Odor-laden air treatment process: Cold air drawn from each odor removal point is heated by exchanging heat with hot flue gas from the incinerator after dust removal through a flue gas heat exchanger. The hot air enters the desorption zone of the absorption-desorption tower to desorb the odor-laden gas containing VOCs absorbed in the absorption zone. After desorption, the hot air is sent to the burner of the incinerator by a primary air fan, where it is mixed with natural gas and dry sludge and burned to form hot flue gas.

[0017] 3) Flue gas treatment process: After the dry sludge is incinerated in the incinerator, hot flue gas above 850°C is generated. The hot flue gas stays in the incinerator for more than 2 seconds before entering the SNCR denitrification reactor, where it reacts with ammonia water to remove most of the NOx. Then it enters a high-temperature pulse bag filter for dust removal, becoming clean hot flue gas. The clean hot flue gas enters the flue gas heat exchanger, where it exchanges heat with cold air and cold flue gas successively. Then it enters the sludge drying tower to exchange heat with the sludge atomized by the dual-fluid spray gun. The clean hot flue gas instantly dries the sludge into dirty wet flue gas carrying a large amount of water vapor and some fine sludge particles. The temperature of the dirty and wet flue gas is below 180℃. After being discharged from the sludge drying tower, the dirty and wet flue gas enters the medium-low temperature sludge capture device, where the sludge is captured and becomes clean and wet flue gas. The clean and wet flue gas first enters the water washing tower, where the water vapor is separated after rapid cooling, and then enters the alkaline washing tower for washing and deacidification. The deacidified clean and wet flue gas returns to the flue gas heat exchanger, where it is heated up after heat exchange and becomes clean flue gas. The clean flue gas enters the absorption zone of the absorption-desorption tower, where pollutants, including VOCs, heavy metals, and dioxins, are adsorbed and removed from the flue gas. Finally, it is sent to the chimney for emission by the induced draft fan.

[0018] 4) Ash and slag conveying process: The ash and slag collected by the incinerator and the high-temperature pulse bag filter are respectively sent to the ash and slag silo through the ash and slag pneumatic conveying device.

[0019] The incinerator has an insulated furnace chamber made of refractory material. Two sets of burners are installed along the height of the lower part of the incinerator. The burners are dual-fuel burners. The bottom of the incinerator is conical, and the ash and slag are cooled naturally.

[0020] The SNCR denitrification reactor consists of two groups, which are respectively arranged at the center above the furnace of the incinerator and at the descending vertical pipe of the high-temperature flue gas conveying pipeline at the outlet of the incinerator; the SNCR spray gun in the SNCR denitrification reactor is arranged at the hot flue gas inlet of the SNCR denitrification reactor and sprays ammonia water obliquely inward and downward in the countercurrent with the hot flue gas.

[0021] The high-temperature pulse bag filter is either a ceramic high-temperature pulse bag filter or a metal fiber high-temperature pulse bag filter.

[0022] The flue gas heat exchanger is a two-stage heat exchanger, one stage is used to heat cold air, and the other stage is used to heat the clean, wet flue gas after acid removal. The temperature of the clean flue gas at the outlet of the flue gas heat exchanger is below 700℃.

[0023] The sludge drying tower adopts a direct-injection sludge drying process. The sludge is atomized by a dual-fluid spray gun and sprayed into the tower, where it is directly exposed to the inlet hot flue gas and dries instantly. The sludge drying tower is lined with refractory insulation material or constructed of refractory materials, and the bottom of the tower is conical.

[0024] The medium-low temperature sludge capture device adopts a low temperature bag filter, and the inlet cold and humid flue gas temperature is below 200℃.

[0025] The water washing tower sprays water mist as a cooling medium, and the temperature of the flue gas after water washing drops to below 40°C.

[0026] The absorption-desorption tower integrates absorption and desorption functions, with absorption and desorption zones on both sides. The absorption zone uses porous active media to adsorb VOCs, heavy metals, and dioxins from clean flue gas. A rotor is installed in the middle of the absorption-desorption tower, and the absorption and desorption zones at the top and bottom of the rotor are separated by partitions. Adsorbent is placed on the rotor, and as the rotor rotates, the adsorbent alternately passes through the adsorption zone to contact clean flue gas and through the desorption zone to contact hot air. In the absorption zone, VOCs, heavy metals, and dioxins in the clean flue gas are adsorbed by the adsorbent. In the desorption zone, the VOCs and dioxins adsorbed by the adsorbent are desorbed by heating with hot air and sent to the incinerator for combustion by a primary air fan.

[0027] A sludge incineration system includes an incinerator, an SNCR denitrification reactor, a high-temperature pulse bag filter, a flue gas heat exchanger, a sludge drying tower, a medium-low temperature sludge trap, a water washing tower, an alkaline washing tower, and an absorption-desorption tower. The incinerator has a burner at the bottom, a hot flue gas outlet at the top, and a conical bottom with an ash outlet. The hot flue gas outlet is connected to a flue gas inlet on one side of the lower part of the high-temperature pulse bag filter via a hot flue gas conveying pipe. SNCR denitrification reactors are installed in the rising vertical pipe near the hot flue gas outlet and in the descending vertical pipe of the hot flue gas conveying pipe, respectively. The high-temperature pulse bag filter has a clean hot flue gas outlet at the top and an ash hopper at the bottom, with an ash outlet. The ash outlet has two outlets: one for ash and one for clean hot flue gas. The ash outlets are connected to the ash bins via corresponding pneumatic conveying devices. The clean hot flue gas outlet is connected to the clean hot flue gas inlet of the flue gas heat exchanger via a clean hot flue gas pipeline. The flue gas heat exchanger has a two-stage heat exchange structure. The first stage heat exchange structure has a cold air inlet and a hot air outlet opposite each other, and the second stage heat exchange structure has a cold wet flue gas inlet and a clean flue gas outlet opposite each other. The end of the flue gas heat exchanger opposite to the clean hot flue gas outlet is connected to the top of the sludge drying tower via an inlet hot flue gas pipeline. The upper part of the sludge drying tower is equipped with a dual-fluid spray gun. The material inlet end of the dual-fluid spray gun is connected to the sludge conveying pipeline, and the spray end of the dual-fluid spray gun faces the upper part of the sludge drying tower. The lower part of the sludge drying tower is equipped with a dirty wet flue gas outlet, and the bottom is equipped with a sludge discharge outlet. One outlet is for the dirty, wet flue gas; the dirty, wet flue gas outlet is connected to the flue gas inlet of the medium-low temperature sludge collector via a dirty, wet flue gas pipe; the medium-low temperature sludge collector has a sludge discharge outlet at the bottom and a clean, wet flue gas outlet at the top; sludge discharge outlet one and sludge discharge outlet two are respectively connected to the sludge inlet of the burner via corresponding sludge pneumatic conveying devices; the clean, wet flue gas outlet is connected to the flue gas inlet at the top of the water washing tower via a clean, wet flue gas pipe, the flue gas outlet at the bottom of the water washing tower is connected to the flue gas inlet at the top of the alkaline washing tower via a flue gas pipe, and the bottom of the water washing tower has a drain outlet connected to a drainage trough; the clean, wet flue gas outlet at the bottom of the alkaline washing tower is connected to the cold, wet flue gas inlet of the flue gas heat exchanger via a clean, wet flue gas pipe; the absorption-desorption tower has an absorption zone and a desorption zone on both sides, the absorption zone... A porous active medium is used; a rotor is installed in the middle of the absorption-desorption tower, and the absorption and desorption zones at the top and bottom of the rotor are separated by partitions; an adsorbent is placed on the rotor; the clean flue gas outlet of the flue gas heat exchanger is connected to the clean flue gas inlet at the top of the absorption zone in the absorption-desorption tower through a clean flue gas pipeline; the hot air outlet of the flue gas heat exchanger is connected to the hot air inlet at the top of the desorption zone in the absorption-desorption tower through a hot air pipeline; a clean flue gas outlet is located at the bottom of the absorption zone and is connected to the chimney through a clean flue gas pipeline, and an induced draft fan is installed on the clean flue gas pipeline; a hot air outlet is located at the bottom of the desorption zone and is connected to the hot air inlet of the burner through a hot air return pipeline, and the fuel inlet of the burner is separately connected to a natural gas pipeline, and a primary air fan is installed on the hot air return pipeline.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1) The process flow is short, the system consists of fewer equipment, has a low failure rate, and is easy to operate.

[0030] 2) It adopts a closed-loop operation with good sealing performance. There are no mechanical open or semi-open equipment. All materials are transported through pipelines, which eliminates the possibility of sludge odor overflow and has a small impact on the environment.

[0031] 3) Incinerators are used instead of rotary kilns. Incinerators have high combustion efficiency (thermal efficiency exceeding 90%). They adopt a direct combustion process of mixed gas and sludge injection to overcome the disadvantage of low calorific value of sludge, improve combustion efficiency, and enable sludge to be completely burned.

[0032] 4) The system has good operational safety. The furnace maintains open flame combustion. When the sludge is injected into the furnace, it mixes with the gas and begins to burn. It does not form a large enclosed space where sludge dust mixes with air, thus eliminating the possibility of dust explosion.

[0033] 5) Incineration fly ash no longer enters the low-temperature bag filter, eliminating circulating ash and completely solving the problem of circulating ash accumulation, thus ensuring stable system operation.

[0034] 6) More environmentally friendly; sludge pretreatment requires no chemicals, no added Cl, and contains no dioxin precursors. Sludge is stably incinerated at temperatures around 850℃, and native dioxins in the sludge can be decomposed in just over 2 seconds; the sludge drying process is equivalent to rapid cooling, with no temperature conditions for dioxin regeneration, thus completely solving the dioxin problem in flue gas.

[0035] 7) The desulfurization system is simple, does not require the addition of CaO to the incinerator to reduce the sulfur content of the flue gas, has a simple system composition, is stable and reliable in operation, and has a low investment cost.

[0036] 8) A dedicated reaction vessel is set up for the denitrification process to improve the efficiency of NOx and odor pollutant treatment in flue gas and ensure that emission standards are met.

[0037] 9) The incinerator adopts a suspension combustion method, which eliminates the need for additional incineration equipment such as rotary kilns, resulting in lower investment and a lower failure rate.

[0038] 9) The drying tower, heat exchanger, etc. are all lined with refractory materials, eliminating the need for expensive stainless steel materials. They have good heat resistance (can withstand temperatures above 800℃), resulting in higher drying temperatures. The insulated furnace has a longer operating time and lower maintenance costs. The high-temperature pulse bag filter uses either ceramic or metal fiber high-temperature pulse bag filters, which are heat-resistant, have a long service life, and low maintenance costs. The incineration system has no pressure components and uses non-pressure vessels, making operation easier and less expensive. No chemicals are needed for sludge, eliminating the cost of chemicals and investment in dosing equipment. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of a sludge incineration system according to the present invention.

[0040] In the diagram: 1. Incinerator; 1-1. Burner; 1-2. Furnace bottom; 2. SNCR denitrification reactor; 2-1. SNCR spray gun; 3. High-temperature pulse bag filter; 3-1. Ash hopper; 4. Flue gas heat exchanger; 5. Sludge drying tower; 5-1. Dual-fluid spray gun; 6. Medium-low temperature sludge trap; 7. Water washing tower; 8. Alkali washing tower; 9. Absorption-desorption tower; 9-1. Absorption zone; 9-2. Desorption zone; 9-3. Baffle; 9-4. Rotary impeller; 10. Exhaust fan; 11. Chimney; 12-1. Sludge pneumatic conveying device; 12-2. Ash pneumatic conveying device; 13. Primary air fan; 14. Ash bin. Detailed Implementation

[0041] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0042] like Figure 1 As shown, the sludge incineration process of the present invention includes the following steps:

[0043] 1) Sludge treatment process: The sludge is sent to the upper part of the sludge drying tower 5, atomized by the dual-fluid spray gun 5-1, and dehydrated after contacting the hot flue gas at the inlet of the sludge drying tower 5. Part of the dried sludge falls to the bottom of the sludge drying tower 5, and the other part is discharged from the sludge drying tower 5 with the cold flue gas and enters the medium and low temperature sludge capture device 6. The sludge intercepted by the medium and low temperature sludge capture device 6 and the sludge collected by the sludge drying tower 5 are respectively sent to the burner 1-1 at the top of the incinerator 1 through the sludge pneumatic conveying device 12-1, and then mixed with natural gas and hot air for incineration. The slag produced by incineration is discharged from the bottom of the furnace 1-2, and the fly ash produced by incineration is denitrified by the SNCR denitrification reactor 2 and then enters the high temperature pulse bag dust collector 3. The intercepted fly ash falls into the bottom ash hopper 3-1.

[0044] 2) Odor-laden air treatment process: Cold air drawn from each odor removal point is heated by exchanging heat with hot flue gas from incinerator 1 after dust removal through flue gas heat exchanger 4 to become hot air. The hot air enters the desorption zone 9-2 of absorption-desorption tower 9 to desorb the odor-laden gas containing VOCs absorbed in absorption zone 9-1. The hot air after desorption is sent to burner 1-1 of incinerator 1 by primary air fan 13, where it is mixed with natural gas and dry sludge and burned to form hot flue gas.

[0045] 3) Flue gas treatment process: After the dry sludge is incinerated in incinerator 1, hot flue gas above 850°C is generated. The hot flue gas stays in incinerator 1 for more than 2 seconds and then enters SNCR denitrification reactor 2, where it reacts with ammonia water to remove most of the NOx. Then it enters high-temperature pulse bag filter 3 for dust removal and becomes hot and clean flue gas. The hot and clean flue gas enters flue gas heat exchanger 4, where it exchanges heat with cold air and cold flue gas successively. Then it enters sludge drying tower 5 to exchange heat with sludge atomized by dual-fluid spray gun 5-1. The hot and clean flue gas instantly dries the sludge into dirty and wet flue gas carrying a large amount of water vapor and some fine sludge particles. The temperature of the dirty wet flue gas is below 180℃. After being discharged from the sludge drying tower 5, the dirty wet flue gas enters the medium-low temperature sludge capture device 6, where the sludge is captured and becomes clean wet flue gas. The clean wet flue gas first enters the water washing tower 7, where the water vapor is released after rapid cooling, and then enters the alkaline washing tower 8 for washing and deacidification. The deacidified clean wet flue gas returns to the flue gas heat exchanger 4, where it is heated by heat exchange and becomes clean flue gas. The clean flue gas enters the absorption zone 9-1 in the absorption-desorption tower 9, where pollutants including VOCs, heavy metals, and dioxins are adsorbed and removed from the flue gas. Finally, it is sent to the chimney 11 for emission by the induced draft fan 10.

[0046] 4) Ash and slag conveying process: The ash and slag collected by the incinerator 1 and the high-temperature pulse bag filter 3 are respectively sent to the ash and slag silo 14 through the ash and slag pneumatic conveying device 12-2.

[0047] The incinerator 1 has an insulated furnace chamber made of refractory material. Two sets of burners 1-1 are installed along the height of the lower part of the incinerator 1. The burners 1-1 are dual-fuel burners. The furnace bottom 1-2 of the incinerator 1 is a conical bottom, and the ash and slag are cooled naturally.

[0048] The SNCR denitrification reactor 2 consists of two groups, which are respectively arranged at the center above the furnace of the incinerator 1 and at the descending vertical pipe of the high-temperature flue gas conveying pipeline at the outlet of the incinerator 1; the SNCR spray gun 2-1 in the SNCR denitrification reactor 2 is arranged at the hot flue gas inlet of the SNCR denitrification reactor 2, and sprays ammonia water obliquely inward and downward in the countercurrent with the hot flue gas.

[0049] The high-temperature pulse bag filter 3 is a ceramic high-temperature pulse bag filter or a metal fiber high-temperature pulse bag filter.

[0050] The flue gas heat exchanger 4 is a two-stage heat exchanger, one stage is used to heat cold air, and the other stage is used to heat the clean and wet flue gas after acid removal. The temperature of the hot clean flue gas at the outlet of the flue gas heat exchanger 4 is below 700℃.

[0051] The sludge drying tower 5 adopts a direct injection sludge drying process. The sludge is atomized by a dual-fluid spray gun 5-1 and sprayed into the tower, where it is directly exposed to the inlet hot flue gas and dries instantly. The sludge drying tower 5 is lined with refractory insulation material or constructed of refractory materials, and the bottom of the tower is conical.

[0052] The medium-low temperature sludge capture device 6 adopts a low temperature bag filter, and the inlet cold and humid flue gas temperature is below 200℃.

[0053] The water washing tower 7 sprays water mist as a cooling medium, and the temperature of the flue gas after water washing drops to below 40°C.

[0054] The absorption-desorption tower 9 integrates absorption and desorption functions, with absorption zone 9-1 and desorption zone 9-2 on both sides. Absorption zone 9-1 uses porous active media to adsorb VOCs, heavy metals, and dioxins from clean flue gas. A rotor 9-4 is located in the middle of the absorption-desorption tower 9, and the absorption zone 9-1 and desorption zone 9-2 above and below the rotor 9-4 are separated by a partition 9-3. Adsorbent is placed on the rotor 9-4. As the rotor 9-4 rotates, the adsorbent on it alternately passes through the adsorption zone 9-1 and contacts the clean flue gas, and passes through the desorption zone 9-2 and contacts the hot air. In the absorption zone 9-1, VOCs, heavy metals, and dioxins from the clean flue gas are adsorbed by the adsorbent. In the desorption zone 9-2, the VOCs and dioxins adsorbed by the adsorbent are desorbed by heating with hot air and sent to the incinerator 1 for incineration by the primary air fan 13.

[0055] The sludge incineration system of this invention includes an incinerator 1, an SNCR denitrification reactor 2, a high-temperature pulse bag filter 3, a flue gas heat exchanger 4, a sludge drying tower 5, a medium-low temperature sludge trap 6, a water washing tower 7, an alkaline washing tower 8, and an absorption-desorption tower 9. The incinerator 1 has a burner 1-1 at its lower part, a hot flue gas outlet at its top, and a conical bottom 1-2 with an ash outlet. The hot flue gas outlet is connected to the flue gas inlet on one side of the lower part of the high-temperature pulse bag filter 3 via a hot flue gas conveying pipe. The SNCR denitrification reactor 2 is installed in the rising vertical pipe near the hot flue gas outlet and in the descending vertical pipe of the hot flue gas conveying pipe. The high-temperature pulse bag filter 3 has a clean hot flue gas outlet at its top and an ash hopper 3-1 at its bottom. Ash hopper 3-1 is equipped with ash outlet 2; ash outlet 1 and ash outlet 2 are respectively connected to ash bin 14 via corresponding ash pneumatic conveying devices 12-2; clean hot flue gas outlet is connected to the clean hot flue gas inlet of flue gas heat exchanger 4 via a clean hot flue gas pipeline; the flue gas heat exchanger 4 has a two-stage heat exchange structure, the first stage heat exchange structure is provided with a cold air inlet and a hot air outlet, and the second stage heat exchange structure is provided with a cold humid flue gas inlet and a clean flue gas outlet; the end of the flue gas heat exchanger 4 opposite to the clean hot flue gas outlet is connected to the top of sludge drying tower 5 via an inlet hot flue gas pipeline; the upper part of sludge drying tower 5 is equipped with a dual-fluid spray gun 5-1, the material inlet end of the dual-fluid spray gun 5-1 is connected to the sludge conveying pipeline, and the spray end of the dual-fluid spray gun 5-1 faces the sludge drying tower 5. The upper part of the sludge drying tower 5 has a dirty and wet flue gas outlet at the bottom and a sludge discharge outlet at the bottom. The dirty and wet flue gas outlet is connected to the flue gas inlet of the medium and low temperature sludge capture device 6 through a dirty and wet flue gas pipeline. The medium and low temperature sludge capture device 6 has a sludge discharge outlet at the bottom and a clean and wet flue gas outlet at the top. The sludge discharge outlet 1 and the sludge discharge outlet 2 are respectively connected to the sludge inlet of the burner 1 through corresponding sludge pneumatic conveying devices 12-1. The clean and wet flue gas outlet is connected to the flue gas inlet at the top of the water washing tower 7 through a clean and wet flue gas pipeline. The flue gas outlet at the bottom of the water washing tower 7 is connected to the flue gas inlet at the top of the alkaline washing tower 8 through a flue gas pipeline. The bottom of the water washing tower 7 has a drain outlet connected to a drainage trough. The clean and wet flue gas outlet at the bottom of the alkaline washing tower 8 is connected to the cold and wet flue gas heat exchanger 4 through a clean and wet flue gas pipeline. The absorption-desorption tower 9 has an absorption zone 9-1 and a desorption zone 9-2 on its two sides, with a porous active medium in the absorption zone 9-1. A rotating wheel 9-4 is located in the middle of the absorption-desorption tower 9, with the absorption zone 9-1 and desorption zone 9-2 separated by a partition 9-3 at the top and bottom of the wheel 9-4. An adsorbent is placed on the rotating wheel 9-4. The clean flue gas outlet of the flue gas heat exchanger 4 is connected to the clean flue gas inlet at the top of the absorption zone 9-1 in the absorption-desorption tower 9 via a clean flue gas pipe. The hot air outlet of the flue gas heat exchanger 4 is connected to the hot air inlet at the top of the desorption zone 9-2 in the absorption-desorption tower 9 via a hot air pipe. A clean flue gas outlet is located at the bottom of the absorption zone 9-1 and is connected to a chimney 11 via a clean flue gas pipe. An induced draft fan 10 is installed on the clean flue gas pipe.A hot air outlet is located at the bottom of the analysis zone 9-2, which is connected to the hot air inlet of burner 1-1 via a hot air return pipe. The fuel inlet of burner 1-1 is also connected to a natural gas pipeline. A primary air fan 13 is installed on the hot air return pipe.

[0056] The sludge incineration process and system described in this invention adopts a fully enclosed structure and operates under negative pressure. The sludge is dehydrated through direct contact with flue gas. The dry sludge powder enters the furnace of the incinerator along with air and natural gas through the burner for combustion. The flue gas generated by combustion passes through high-temperature dust removal, medium- and low-temperature sludge capture, high-temperature flue gas-air heat exchange, water washing tower dehydration, and alkaline washing tower wet deacidification. After being heated by the flue gas heat exchanger, it enters the absorption-desorption tower to complete the adsorption and removal of VOCs and dioxins, etc. The adsorbent is regenerated using hot air.

[0057] Inside the water scrubbing tower, a large amount of water vapor is released from the cold, humid flue gas, while simultaneously dissolving a certain amount of acidic gases. Inside the alkaline scrubbing tower, an alkaline detergent (preferably 30% sodium hydroxide by mass) is used to remove the acidic gases from the clean, humid flue gas.

[0058] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0059]

Example

[0060] like Figure 1 As shown in the figure, the sludge incineration process in this embodiment is as follows:

[0061] 1) Sludge Treatment: Sludge is conveyed to sludge drying tower 5 via a conveying device. After being atomized by a dual-fluid spray gun 5-1, it comes into contact with the hot flue gas at the inlet of sludge drying tower 5 for dehydration and drying. Part of the dried sludge falls to the bottom of sludge drying tower 5, while the other part is discharged from sludge drying tower 5 with cold flue gas and enters medium-low temperature sludge capture device 6 (in this embodiment, a low-temperature bag filter is used). Sludge pneumatic conveying device 12-1 is used to send the sludge intercepted by medium-low temperature sludge capture device 6 and the sludge collected by sludge drying tower 5 to burner 1-1 on incinerator 1, where it is mixed with natural gas and hot air and then incinerated. The slag produced by incineration is discharged from the bottom 1-2 of incinerator 1. The fly ash produced by incineration enters high-temperature pulse bag filter 3 with the flue gas through SNCR denitrification reactor 2, where it is intercepted and falls into ash hopper 3-1 of high-temperature pulse bag filter 3.

[0062] 2) Odor-laden air treatment: Cold air drawn from each odor removal point is heated to hot air by flue gas heat exchanger 4. The hot air enters the desorption zone 9-2 of the absorption-desorption tower 9 to desorb the VOCs and odor gases absorbed by the absorption zone 9-1. The hot air after desorption is sent to the burner 1-1 on the incinerator 1 by the primary air fan 13, where it is mixed with natural gas and dry sludge and then incinerated.

[0063] 3) Flue Gas Treatment: The hot flue gas (approximately 850°C) generated from the incineration of dry sludge, after remaining in the incinerator 1 for 2 seconds, enters the SNCR denitrification reactor 2. After reacting with ammonia water, most of the NOx is removed. Then, it enters the high-temperature pulse bag filter 3 for dust removal, becoming clean hot flue gas. The clean hot flue gas enters the flue gas heat exchanger 4, where it exchanges heat with cold air and cold flue gas successively. It then enters the sludge drying tower 5 (in this embodiment, a spray drying tower is used), where it exchanges heat with the sludge atomized by the dual-fluid spray gun 5-1. The clean hot flue gas instantly dries the sludge into dirty, wet flue gas (approximately 180°C) carrying a large amount of water vapor and some fine sludge particles, which is discharged from the outlet of the sludge drying tower 5. The dirty, wet flue gas enters the medium-low temperature sludge capture device 6 (in this embodiment, a low-temperature bag filter is used) to capture the sludge, resulting in clean, wet flue gas. The clean, moist flue gas enters the water scrubbing tower 7 for rapid cooling, causing the water vapor in the flue gas to precipitate out. It then enters the deacidification tower 8 for washing and deacidification. The deacidified clean, moist flue gas returns to the flue gas heat exchanger 4, where it is heated to become clean flue gas. The clean flue gas then enters the absorption zone 9-1 of the absorption-desorption tower 9. The absorption zone 9-1 is used to adsorb residual VOCs, heavy metals, dioxins, and other pollutants in the flue gas. The purified flue gas is finally sent to the chimney 11 by the induced draft fan 10 for emission in compliance with standards.

[0064] This embodiment includes two sets of pneumatic conveying devices. One set is an ash pneumatic conveying device 12-2, which is responsible for conveying the ash collected by the incinerator 1 and the high-temperature pulse bag filter 3 to the ash silo 14; the other set is a sludge pneumatic conveying device 12-1, which is responsible for conveying the sludge collected by the spray drying tower and the low-temperature belt filter to the burner 1-1 on the incinerator 1.

[0065] In this embodiment, the incinerator 1 adopts an insulated furnace chamber, which is constructed of refractory materials and is equipped with two sets of dual-fuel burners, one above the other. The furnace bottom is conical, and the ash and slag are naturally cooled and pneumatically conveyed.

[0066] In this embodiment, the SNCR denitrification reactor 2 is arranged at the center of the hot flue gas outlet at the top of the furnace and at the descending vertical pipe of the hot flue gas conveying pipeline. The SNCR spray gun 2-1 is arranged at the hot flue gas outlet of the furnace and at the hot flue gas inlet of the descending vertical pipe, and both spray downwards against the direction of hot flue gas flow.

[0067] In this embodiment, the high-temperature pulse bag filter 3 is a ceramic high-temperature pulse dust collector.

[0068] In this embodiment, the flue gas heat exchanger 4 adopts a two-stage heat exchange structure. The first stage heat exchange structure is used to heat cold air, and the second stage heat exchange structure is used to heat the clean wet flue gas after acid removal. The temperature of the hot clean flue gas at the outlet of the flue gas heat exchanger 4 is about 700°C.

[0069] In this embodiment, the spray drying tower adopts a direct-injection sludge drying process. The sludge is atomized by a dual-fluid spray gun 5-1 and sprayed into the tower, directly contacting the dry flue gas and being dried instantly. The spray drying tower is lined with refractory insulation material, and the bottom of the tower is a cone. The sludge is conveyed pneumatically.

[0070] In this embodiment, the low-temperature sludge collector 6 adopts a low-temperature bag filter, the flue gas inlet temperature is about 200°C, and the sludge is conveyed by pneumatic conveying.

[0071] In this embodiment, water mist is sprayed into the water washing tower 7 as a cooling medium to reduce the flue gas temperature to about 40°C. At this time, a large amount of water vapor is released from the flue gas, and a certain amount of acidic gas is dissolved.

[0072] In this embodiment, the acid rinsing tower 8 uses sodium hydroxide with a mass concentration of 30% as a detergent to remove acidic gases from the clean, wet flue gas.

[0073] In this embodiment, the absorption zone 9-1 of the absorption-desorption tower 9 is equipped with a porous active medium for adsorbing VOCs, heavy metals, and dioxins from the clean flue gas. The absorption-desorption tower 9 has a cylindrical structure, with baffles 9-3 on both sides of the rotor 9-4 separating the absorption zone 9-1 and the desorption zone 9-2 into two independent areas. The rotor 9-4 is equipped with adsorbent, and the rotor 9-4 alternately passes through the adsorption zone 9-1 and the desorption zone 9-2, allowing the adsorbent to alternately contact the clean flue gas and hot air. The adsorbent adsorbs VOCs, heavy metals, and dioxins from the clean flue gas. After the hot air heats the adsorbent, the adsorbed VOCs and dioxins are desorbed and carried to the incinerator 1 for incineration.

[0074] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A sludge incineration process, characterized in that, The process includes the following: 1) Sludge treatment process: The sludge is sent to the upper part of the sludge drying tower, atomized by a dual-fluid spray gun, and then dehydrated and dried after contacting the hot flue gas at the inlet of the sludge drying tower. After drying, part of the sludge falls to the bottom of the sludge drying tower, while the other part is discharged from the sludge drying tower with the dirty and wet flue gas carrying water vapor and fine sludge particles, and enters the medium-low temperature sludge capture device. The sludge intercepted by the medium-low temperature sludge capture device and the sludge collected by the sludge drying tower are respectively sent to the burner at the top of the incinerator through the sludge pneumatic conveying device, where they are mixed with natural gas and hot air and then burned. The slag produced by incineration is discharged from the bottom of the furnace, and the fly ash produced by incineration is denitrified by the SNCR denitrification reactor and then enters the high temperature pulse bag dust collector. The intercepted fly ash falls into the bottom ash hopper. 2) Odor-laden air treatment process: Cold air drawn from each odor removal point is heated by exchanging heat with hot flue gas from the incinerator after dust removal through a flue gas heat exchanger. The hot air enters the desorption zone of the absorption-desorption tower to desorb the odor-laden gases containing VOCs absorbed in the absorption zone. After desorption, the hot air is sent to the burner of the incinerator by a primary air fan, where it is mixed with natural gas and dry sludge and burned to form hot flue gas. 3) Flue gas treatment process: After the dry sludge is burned in the incinerator, hot flue gas above 850°C is generated. The hot flue gas stays in the incinerator for more than 2 seconds and then enters the SNCR denitrification reactor. After reacting with ammonia water, most of the NOx is removed. Then it enters the high-temperature pulse bag filter for dust removal and becomes hot clean flue gas. The hot clean flue gas enters the flue gas heat exchanger and exchanges heat with cold air and clean wet flue gas that has been deacidified by water washing tower and alkali washing tower and returned to the flue gas heat exchanger. Then it enters the sludge drying tower and exchanges heat with sludge that has been atomized by dual fluid spray gun. The hot flue gas instantly dries the sludge into dirty wet flue gas carrying a large amount of water vapor and some fine sludge particles. The temperature of the dirty wet flue gas is below 180℃. After being discharged from the sludge drying tower, the dirty wet flue gas enters the medium-low temperature sludge capture device, where the sludge is captured and becomes clean wet flue gas. The clean wet flue gas first enters the water washing tower, where the water vapor is released after rapid cooling. Then it enters the alkaline washing tower for washing and deacidification. The deacidified clean wet flue gas returns to the flue gas heat exchanger, where it is heated up to become clean flue gas. The clean flue gas enters the absorption zone of the absorption-desorption tower, where pollutants, including VOCs, heavy metals, and dioxins, are adsorbed and removed from the flue gas. Finally, it is sent to the chimney for emission by the induced draft fan. 4) Ash and slag conveying process: The ash and slag collected by the incinerator and the high-temperature pulse bag filter are respectively sent to the ash and slag silo through the ash and slag pneumatic conveying device.

2. The sludge incineration process according to claim 1, characterized in that, The incinerator has an insulated furnace chamber made of refractory material. Two sets of burners are installed along the height of the lower part of the incinerator. The burners are dual-fuel burners. The bottom of the incinerator is conical, and the ash and slag are cooled naturally.

3. The sludge incineration process according to claim 1, characterized in that, The SNCR denitrification reactor consists of two groups, which are respectively arranged at the center above the furnace of the incinerator and at the descending vertical pipe of the high-temperature flue gas conveying pipeline at the outlet of the incinerator; the SNCR spray gun in the SNCR denitrification reactor is arranged at the hot flue gas inlet of the SNCR denitrification reactor and sprays ammonia water obliquely inward and downward in the countercurrent with the hot flue gas.

4. The sludge incineration process according to claim 1, characterized in that, The high-temperature pulse bag filter is either a ceramic high-temperature pulse bag filter or a metal fiber high-temperature pulse bag filter.

5. The sludge incineration process according to claim 1, characterized in that, The flue gas heat exchanger is a two-stage heat exchanger, one stage is used to heat cold air, and the other stage is used to heat the clean, wet flue gas after acid removal. The temperature of the clean flue gas at the outlet of the flue gas heat exchanger is below 700℃.

6. The sludge incineration process according to claim 1, characterized in that, The sludge drying tower adopts a direct-injection sludge drying process. The sludge is atomized by a dual-fluid spray gun and sprayed into the tower, where it is directly exposed to the inlet hot flue gas and dries instantly. The sludge drying tower is lined with refractory insulation material or constructed of refractory materials, and the bottom of the tower is conical.

7. The sludge incineration process according to claim 1, characterized in that, The medium-low temperature sludge capture device adopts a low temperature bag filter, and the inlet cold and humid flue gas temperature is below 200℃.

8. The sludge incineration process according to claim 1, characterized in that, The water washing tower sprays water mist as a cooling medium, and the temperature of the flue gas after water washing drops to below 40°C.

9. The sludge incineration process according to claim 1, characterized in that, The absorption-desorption tower integrates absorption and desorption functions, with absorption and desorption zones on both sides. The absorption zone uses a porous active medium to adsorb VOCs, heavy metals, and dioxins from the clean flue gas. A rotor is installed in the middle of the absorption-desorption tower, and the absorption zone and desorption zone are separated by partitions at the upper and lower parts of the rotor. Adsorbent is placed on the rotor, and as the rotor rotates, the adsorbent on it alternately passes through the adsorption zone and contacts the clean flue gas, and then passes through the desorption zone and contacts the hot air. In the absorption zone, VOCs, heavy metals, and dioxins from the clean flue gas are adsorbed by the adsorbent. In the desorption zone, VOCs and dioxins adsorbed by the adsorbent are desorbed by heating with hot air and then sent to the incinerator for incineration by a primary air fan.

10. A sludge incineration system for implementing the sludge incineration process as described in any one of claims 1 to 9, characterized in that, The system includes an incinerator, an SNCR denitrification reactor, a high-temperature pulse bag filter, a flue gas heat exchanger, a sludge drying tower, a medium-low temperature sludge trap, a water washing tower, an alkali washing tower, and an absorption-desorption tower. The incinerator has a burner at the bottom, a hot flue gas outlet at the top, and a conical bottom with an ash outlet. The hot flue gas outlet is connected to the flue gas inlet on one side of the lower part of the high-temperature pulse bag filter via a hot flue gas conveying pipe. SNCR denitrification reactors are installed in the rising vertical pipe and the descending vertical pipe of the hot flue gas conveying pipe, respectively, near the hot flue gas outlet. The high-temperature pulse bag filter has a clean hot flue gas outlet at the top and an ash hopper at the bottom, with an ash outlet. The ash outlets are divided into two sections. The ash silo is connected to the corresponding ash pneumatic conveying device; the clean hot flue gas outlet is connected to the clean hot flue gas inlet of the flue gas heat exchanger through a clean hot flue gas pipeline; the flue gas heat exchanger has a two-stage heat exchange structure, with a cold air inlet and a hot air outlet opposite each other in the first stage, and a cold wet flue gas inlet and a clean flue gas outlet opposite each other in the second stage; the end of the flue gas heat exchanger opposite to the clean hot flue gas outlet is connected to the top of the sludge drying tower through an inlet hot flue gas pipeline; a dual-fluid spray gun is installed at the top of the sludge drying tower, with the material inlet end of the dual-fluid spray gun connected to the sludge conveying pipeline, and the spray end of the dual-fluid spray gun facing the upper part of the sludge drying tower; a dirty wet flue gas outlet is installed at the bottom of the sludge drying tower, and a sludge discharge outlet is installed at the bottom. The dirty wet flue gas outlet is connected to the flue gas inlet of the medium-low temperature sludge collector via a dirty wet flue gas pipe; the medium-low temperature sludge collector has a second sludge discharge outlet at the bottom and a clean wet flue gas outlet at the top; the first and second sludge discharge outlets are respectively connected to the sludge inlet of the burner via corresponding sludge pneumatic conveying devices; the clean wet flue gas outlet is connected to the flue gas inlet at the top of the water washing tower via a clean wet flue gas pipe, and the flue gas outlet at the bottom of the water washing tower is connected to the flue gas inlet at the top of the alkaline washing tower via a flue gas pipe; the bottom of the water washing tower has a drain outlet connected to a drainage trough; the clean wet flue gas outlet at the bottom of the alkaline washing tower is connected to the cold wet flue gas inlet of the flue gas heat exchanger via a clean wet flue gas pipe; the absorption-desorption tower has an absorption zone and a desorption zone on both sides, and the absorption zone is equipped with... A porous active medium is used; a rotor is installed in the middle of the absorption-desorption tower, and the absorption and desorption zones at the top and bottom of the rotor are separated by partitions; an adsorbent is placed on the rotor; the clean flue gas outlet of the flue gas heat exchanger is connected to the clean flue gas inlet at the top of the absorption zone in the absorption-desorption tower through a clean flue gas pipeline; the hot air outlet of the flue gas heat exchanger is connected to the hot air inlet at the top of the desorption zone in the absorption-desorption tower through a hot air pipeline; a clean flue gas outlet is located at the bottom of the absorption zone and is connected to the chimney through a clean flue gas pipeline, and an induced draft fan is installed on the clean flue gas pipeline; a hot air outlet is located at the bottom of the desorption zone and is connected to the hot air inlet of the burner through a hot air return pipeline, the fuel inlet of the burner is also connected to a natural gas pipeline, and a primary air fan is installed on the hot air return pipeline.

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