Sludge incineration process and system

Abstract

The invention relates to a sludge incineration process and system. The sludge incineration system comprises an incinerator, an SNCR denitration reactor, a high-temperature pulse bag type dust collector, a flue gas heat exchanger, a sludge drying tower, a medium and low temperature sludge capturer, a water scrubbing tower, an alkaline washing tower and an absorption-desorption tower. By optimizing the process, the process flow is shortened, and the whole process flow is in closed operation, so that the possibility that sludge is in contact with the atmosphere in the operation process of equipment is eliminated, and the problem of odor overflow is fundamentally solved; a fuel gas and sludge mixed injection direct combustion process is adopted, so that the defect of low heat value of the sludge is overcome, the combustion efficiency is improved, the sludge is completely combusted, and the problem of superposition of circulating ash is thoroughly solved; the system is stable in operation, operation and maintenance cost and equipment cost are reduced, and large-scale popularization and application are facilitated; and a special reaction container is arranged in the denitration process, so that the treatment efficiency of NOx and peculiar smell pollutants in the flue gas is improved, and the emission standard is ensured to be reached.

Description

Technical Field

[0001] The present invention relates to the technical field of harmless sludge treatment, and particularly to a sludge incineration process and system. Background Art

[0002] Sludge incineration treatment is a treatment technology that converts organic matter in sludge into carbon dioxide, water, and ash through high-temperature combustion. Through this treatment, the sludge volume can be effectively reduced, pathogens can be killed, and energy can be recovered. The main processes of sludge incineration treatment include: (1) Pretreatment: The water content of the sludge is reduced through dehydration (usually reduced to less than 80%), and the moisture is further reduced through drying to improve the combustion efficiency. (2) Incineration: The sludge is incinerated at high temperature to decompose the organic matter, and the heat generated by the incineration is used to generate electricity or heat to recover energy. (3) Tail gas treatment: Particulate matter in the flue gas is removed through dust removal, sulfur oxides and nitrogen oxides emissions are reduced through desulfurization and denitrification, and harmful substances (including heavy metals and dioxins) are treated through methods such as activated carbon adsorption. (4) Ash and slag treatment: The ash and slag generated after incineration are collected and landfilled or used as building materials.

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

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

[0005] 2) Flue gas treatment path: The air extracted from each storage tank and odor removal point is sent to the rotary kiln by the primary fan and participates in the incineration process (temperature about 650°C) as the combustion-supporting gas. The flue gas generated by the rotary kiln enters the secondary combustion chamber and is heated to above 850°C by natural gas combustion support, and the residence time is not less than 2 s to decompose the possible dioxins; the flue gas at the outlet of the secondary combustion chamber is mixed with the cold flue gas extracted from the chimney and cooled to below 650°C and then enters the drying tower, where it exchanges heat with the sludge atomized by the two-fluid spray gun, and the temperature drops to below 110°C; the flue gas discharged from the drying tower successively enters the mud remover, the first-stage bag filter (equipped with activated carbon), the second-stage bag filter (equipped with ozone), and the induced draft fan, and after three-stage acid removal (1-stage water washing + 2-stage alkali washing) and dew point depression (air cooling + mixing), it is discharged through the chimney.

[0006] The main problems existing in the above direct sludge drying and incineration process are:

[0007] 1) The process system is equipped with equipment such as scraper conveyors and chutes, resulting in the exposure of materials and the generation of odors inside the factory;

[0008] 2) The combustion efficiency of the rotary kiln is low, and the sludge cannot come into complete contact with air, resulting in incomplete combustion of the sludge and a high heat loss rate of the ash residue;

[0009] 3) There is a problem of cyclic ash accumulation. The fly ash generated by combustion is captured by the dust collector and then sent back to the rotary kiln for secondary incineration. After incineration, it enters the flue gas system again. This cycle repeats, and the ash accumulates more and more. Eventually, the combustion system is overloaded, the regulation system is disordered, and incineration cannot proceed smoothly;

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

[0011] 5) The flue gas after direct drying carries VOCs, nitrogen oxides, etc. Deodorization and denitrification treatments are required. Deodorization and denitrification generally use the pipeline direct injection method without a reaction vessel, resulting in uneven reactions, high escape rates of deodorants and denitrification agents, and it is difficult for the purified gas to meet the emission standards, with a large odor outside the factory area and complaints from nearby residents. Summary of the Invention

[0012] The present invention provides a sludge incineration process and system. By optimizing the process, the process flow is shortened, and the entire process flow operates in a closed manner, eliminating the possibility of sludge coming into contact with the atmosphere during equipment operation, fundamentally solving the problem of odor overflow; adopting a gas - sludge mixed injection direct combustion process, overcoming the disadvantage of low sludge calorific value, improving the combustion efficiency, enabling complete combustion of the sludge, and completely solving the problem of cyclic ash accumulation; the system operates stably, while reducing operating, maintenance costs, and equipment construction costs, which is conducive to large - scale popularization and application; a special reaction vessel is set up during the denitrification process to improve the treatment efficiency of flue gas NOx and odor pollutants and ensure compliance with emission standards.

[0013] To achieve the above - mentioned objectives, the present invention is realized by adopting the following technical solutions:

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

[0015] 1) Sludge treatment process: The sludge is sent to the upper part of the sludge drying tower. After being atomized by a two-fluid spray gun, it contacts the hot flue gas at the inlet of the sludge drying tower and is dehydrated and dried. 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 catcher. The sludge intercepted by the medium and low temperature sludge catcher and the sludge collected by the sludge drying tower are respectively sent to the burner at the upper part of the incinerator through the sludge pneumatic conveying device, and are burned after being mixed with natural gas and hot air. The slag generated by the burning is discharged from the bottom of the furnace, and the fly ash generated by the burning enters the high-temperature pulse bag filter after denitrification by the SNCR denitrification reactor, and the intercepted fly ash falls into the bottom ash hopper.

[0016] 2) Odorous air treatment process: The cold air extracted from each odor removal point is heated and becomes hot air after heat exchange with the hot flue gas from the incinerator and passing through the dust collector in the flue gas heat exchanger. The hot air enters the desorption zone of the absorption-desorption tower to desorb the odor gas containing VOCs absorbed in the absorption zone. After the desorption is completed, the hot air is sent to the burner of the incinerator by the primary fan, and is burned after being mixed with natural gas and dry sludge to form hot flue gas.

[0017] 3) Flue gas treatment process: The hot flue gas above 850 °C is generated after the dry sludge is burned in the incinerator. The hot flue gas stays in the incinerator for more than 2 s and then enters the SNCR denitrification reactor, and most of the NOx is removed after reacting with ammonia water. 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, exchanges heat with the cold air and the cold flue gas successively, and then enters the sludge drying tower to exchange heat with the sludge atomized by the two-fluid spray gun. The hot clean flue gas instantly dries the sludge into dirty wet flue gas carrying a large amount of water vapor and some fine sludge particles, and the temperature of the dirty wet flue gas is lower than 180 °C. The dirty wet flue gas is discharged from the sludge drying tower and enters the medium and low temperature sludge catcher to capture the sludge in it and become clean wet flue gas. The clean wet flue gas first enters the water washing tower, and the water vapor in it is precipitated after rapid cooling, and then enters the alkali washing tower for acid washing and deacidification. The deacidified clean wet flue gas returns to the flue gas heat exchanger, is heated and becomes clean flue gas after heat exchange. The clean flue gas enters the absorption zone in the absorption-desorption tower to adsorb and remove the pollutants remaining in the flue gas, including VOCs, heavy metals, and dioxins, and finally 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 bin through the ash and slag pneumatic conveying device.

[0019] The incinerator adopts an adiabatic furnace lined with refractory materials. There are 2 groups of burners arranged vertically in the lower part of the incinerator, and the burners are dual-fuel burners. The bottom of the incinerator is a conical bottom, and the ash and slag are cooled naturally.

[0020] There are 2 sets of SNCR denitration reactors, which are respectively arranged at the central position above the incinerator furnace hearth and at the descending vertical pipe of the high-temperature flue gas conveying pipeline at the incinerator outlet; the SNCR spray guns in the SNCR denitration reactors are arranged at the hot flue gas inlet of the SNCR denitration reactors, and spray ammonia water obliquely inward and downward against the countercurrent of the hot flue gas.

[0021] The high-temperature pulse bag filter uses 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 purified wet flue gas after acid removal. The temperature of the hot purified flue gas at the outlet of the flue gas heat exchanger is below 700 °C.

[0023] The sludge drying tower adopts a direct injection type sludge drying process. The sludge is atomized by a two-fluid spray gun and then sprayed into the tower, and is instantly dried after directly contacting the inlet hot flue gas; the inner lining of the sludge drying tower is made of refractory heat-insulating material or is built with refractories, and the bottom of the tower is a conical bottom.

[0024] The medium and low temperature sludge catcher adopts a low-temperature bag filter, and the temperature of the inlet cold and wet flue gas is below 200 °C.

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

[0026] The absorption-desorption tower integrates the functions of absorption and desorption. The two sides are respectively an absorption zone and a desorption zone; the absorption zone uses a porous active medium to adsorb VOCs, heavy metals and dioxins in the clean flue gas; a rotating wheel is arranged in the middle of the absorption-desorption tower, and the absorption zones above and below the rotating wheel are separated from the desorption zone by a partition; an adsorbent is arranged on the rotating wheel. As the rotating wheel rotates, the adsorbent on it alternately passes through the absorption zone to contact the clean flue gas and passes through the desorption zone to contact the 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 incineration by a primary fan.

[0027] A sludge incineration system includes an incinerator, an SNCR denitration reactor, a high-temperature pulse bag filter, a flue gas heat exchanger, a sludge drying tower, a medium- and low-temperature sludge catcher, a water washing tower, an alkali washing tower, and an absorption-desorption tower. A burner is provided at the lower part of the incinerator, and a hot flue gas outlet is provided at the top. The furnace bottom is a conical bottom and is provided with a first ash slag 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 through a hot flue gas conveying pipeline. An SNCR denitration reactor is respectively provided in the rising vertical pipe of the hot flue gas conveying pipeline near the hot flue gas outlet and in the descending vertical pipe of the hot flue gas conveying pipeline. A clean hot flue gas outlet is provided at the top of the high-temperature pulse bag filter, and a hopper is provided at the bottom. The hopper is provided with a second ash slag outlet. The first ash slag outlet and the second ash slag outlet are respectively connected to an ash slag bin through corresponding ash slag pneumatic conveying devices. 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. The first-stage heat exchange structure is oppositely provided with a cold air inlet and a hot air outlet. The second-stage heat exchange structure is oppositely provided with a cold wet flue gas inlet and a clean flue gas outlet. One 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 two-fluid spray gun is provided at the upper part of the sludge drying tower. The material inlet end of the two-fluid spray gun is connected to a sludge conveying pipeline. The spraying end of the two-fluid spray gun faces the upper part inside the sludge drying tower. A dirty wet flue gas outlet is provided at the lower part of the sludge drying tower, and a first sludge discharge outlet is provided at the bottom. The dirty wet flue gas outlet is connected to the flue gas inlet of the medium- and low-temperature sludge catcher through a dirty wet flue gas pipeline. A second sludge discharge outlet is provided at the bottom of the medium- and low-temperature sludge catcher, and a clean wet flue gas outlet is provided at the top. The first sludge discharge outlet and the second sludge discharge outlet are respectively connected to the sludge inlet of the burner through 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 through a clean wet flue gas pipeline. The flue gas outlet at the lower part of the water washing tower is connected to the flue gas inlet at the top of the alkali washing tower through a flue gas pipeline. A drain port is provided at the bottom of the water washing tower and is connected to a drain tank. The clean wet flue gas outlet at the lower part of the alkali washing tower is connected to the cold wet flue gas inlet of the flue gas heat exchanger through a clean wet flue gas pipeline. The two sides of the absorption-desorption tower are respectively an absorption area and a desorption area. A porous active medium is provided in the absorption area. A runner is provided in the middle of the absorption-desorption tower. The absorption areas above and below the runner are separated from the desorption areas by partitions. An adsorbent is provided on the runner. 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 area 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 area in the absorption-desorption tower through a hot air pipeline. A clean flue gas outlet is provided at the bottom of the absorption area and is connected to a chimney through a clean flue gas pipeline. An induced draft fan is provided on the clean flue gas pipeline. A hot air outlet is provided at the bottom of the desorption area and is connected to the hot air inlet of the burner through a hot air return pipeline. The fuel inlet of the burner is additionally connected to a natural gas pipeline. A primary air fan is provided 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 devices, has a low failure rate, and is easy to operate.

[0030] 2) It adopts a closed operation, has good sealing performance, no mechanical open or semi-open devices, and all materials are transported through pipelines, eliminating the situation of sludge odor overflow and having little impact on the environment.

[0031] 3) It uses an incinerator instead of a rotary kiln. The incinerator has a high incineration efficiency (the thermal efficiency exceeds 90%), and adopts a direct combustion process of mixed injection of gas and sludge, overcoming the disadvantage of low sludge calorific value, improving the combustion efficiency, and enabling the complete combustion of sludge.

[0032] 4) The system operates with good safety. The furnace chamber maintains an open flame combustion. When the sludge is injected into the furnace chamber, it mixes with the gas and starts to burn immediately, without forming the mixing condition of sludge dust and air in a large closed space, eliminating the possible phenomenon of dust deflagration.

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

[0034] 6) It is more environmentally friendly; no chemicals need to be added for sludge pretreatment, no Cl is added, and there are no dioxin precursors. The sludge is stably incinerated in the temperature range near 850°C, and the original dioxin in the sludge can be decomposed in more than 2s; the sludge drying process is equivalent to rapid cooling, without the temperature conditions for dioxin regeneration, completely solving the dioxin problem in the flue gas.

[0035] 7) The desulfurization system is simple, there is no need to add CaO to the incinerator to reduce the sulfur content in the flue gas, the system composition is simple, the operation is stable and reliable, and the investment cost is low.

[0036] 8) A special reaction vessel is set for the denitrification process to improve the treatment efficiency of flue gas NOx and odor pollutants and ensure compliance with the emission standards.

[0037] 9) The incinerator adopts a suspension combustion method, without the need to set up additional incineration equipment such as a rotary kiln, with low investment and low failure rate.

[0038] 9) The drying tower, heat exchanger, etc. are all lined with refractory materials, without the need to use expensive stainless steel materials, having good heat resistance (able to withstand temperatures above 800°C), higher drying temperature, longer operation time of the adiabatic furnace chamber, and low maintenance cost; the high-temperature pulse bag filter is selected as a ceramic high-temperature pulse bag filter or a metal fiber high-temperature pulse bag filter, with high temperature resistance, long life, and low maintenance cost; there are no pressure components in the incineration system, using non-pressure vessels, with low operation and operation difficulty and low cost; no chemicals need to be added to the sludge, without chemical agent cost and investment in chemical dosing equipment. Description of the Drawings

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

[0040] In the figure: 1. Incinerator 1-1. Burner 1-2. Furnace bottom 2. SNCR denitration 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. Two-fluid spray gun 6. Medium- and low-temperature sludge catcher 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. Rotor 10. Induced draft fan 11. Chimney 12-1. Sludge pneumatic conveying device 12-2. Ash and slag pneumatic conveying device 13. Primary air fan 14. Ash and slag bin Specific embodiments

[0041] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings:

[0042] As Figure 1 shown, a sludge incineration process according to the present invention includes the following processes:

[0043] 1) Sludge treatment process: The sludge is sent to the upper part of the sludge drying tower 5, atomized by the two-fluid spray gun 5-1 and contacts with the hot flue gas at the inlet of the sludge drying tower 5 to be dehydrated and dried; a 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 catcher 6; the sludge intercepted by the medium- and low-temperature sludge catcher 6 and the sludge collected by the sludge drying tower 5 are respectively sent to the burner 1-1 at the upper part of the incinerator 1 through the sludge pneumatic conveying device 12-1, and burned after being mixed with natural gas and hot air; the slag generated by the burning is discharged from the furnace bottom 1-2, and the fly ash generated by the burning enters the high-temperature pulse bag filter 3 after denitration by the SNCR denitration reactor 2, and the intercepted fly ash falls into the bottom ash hopper 3-1;

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

[0045] 3) Flue gas treatment process: After the dry sludge is incinerated in the incinerator 1, hot flue gas above 850 °C is generated. The hot flue gas stays in the incinerator 1 for more than 2 s and then enters the SNCR denitration reactor 2, where it reacts with ammonia water to remove most of the NOx. Then it enters the high-temperature pulse bag filter 3 for dust removal and becomes hot clean flue gas. The hot clean flue gas enters the flue gas heat exchanger 4, where it exchanges heat with cold air and cold flue gas successively, and then enters the sludge drying tower 5 to exchange heat with the sludge atomized by the two-fluid spray gun 5-1. The hot clean flue gas instantly dries the sludge into dirty wet flue gas carrying a large amount of water vapor and some fine sludge particles, and the temperature of the dirty wet flue gas is lower than 180 °C. The dirty wet flue gas is discharged from the sludge drying tower 5 and enters the medium and low-temperature sludge catcher 6, where the sludge is captured to become clean wet flue gas. The clean wet flue gas first enters the water washing tower 7, where the water vapor is separated out after rapid cooling, and then enters the alkali washing tower 8 for washing and acid removal. The clean wet flue gas after acid removal returns to the flue gas heat exchanger 4, and after heat exchange and temperature rise, it becomes clean flue gas. The clean flue gas enters the absorption zone 9-1 in the absorption-desorption tower 9, where the pollutants remaining in the flue gas, including VOCs, heavy metals, and dioxins, are adsorbed and removed, and finally is sent to the chimney 11 for discharge through 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 bin 14 through the ash and slag pneumatic conveying device 12-2.

[0047] The incinerator 1 adopts a heat-insulating furnace chamber made of refractory materials. Two groups of burners 1-1 are arranged along the height direction at the lower part of the incinerator 1, and the burner 1-1 is a dual-fuel burner; the furnace bottom 1-2 of the incinerator 1 is a conical bottom, and the ash and slag are cooled naturally.

[0048] There are two groups of SNCR denitration reactors 2, which are respectively arranged at the central position above the furnace chamber 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 denitration reactor 2 is arranged at the hot flue gas inlet of the SNCR denitration reactor 2, and sprays ammonia water obliquely inward and downward against the flow of the hot flue gas.

[0049] The high-temperature pulse bag filter 3 adopts 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 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 °C.

[0051] The sludge drying tower 5 adopts a direct injection type sludge drying process. The sludge is atomized by the two-fluid spray gun 5-1 and sprayed into the tower, and is instantly dried after direct contact with the inlet hot flue gas; the inner lining of the sludge drying tower 5 is made of refractory heat-insulating materials or is built with refractories, and the tower bottom is a conical bottom.

[0052] The medium and low temperature sludge catcher 6 adopts a low temperature bag filter, and the temperature of the imported cold and wet flue gas is lower than 200°C.

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

[0054] The absorption and desorption tower 9 integrates the functions of absorption and desorption. The two sides are respectively an absorption zone 9-1 and a desorption zone 9-2; the absorption zone 9-1 uses a porous active medium to adsorb VOCs, heavy metals and dioxins in the clean flue gas; a rotating wheel 9-4 is arranged in the middle of the absorption and desorption tower 9, and the absorption zone 9-1 above and below the rotating wheel 9-4 is separated from the desorption zone 9-2 by a partition plate 9-3; an adsorbent is arranged on the rotating wheel 9-4. As the rotating wheel 9-4 rotates, the adsorbent on it alternately passes through the absorption zone 9-1 to contact the clean flue gas and passes through the desorption zone 9-2 to contact the hot air; in the absorption zone 9-1, VOCs, heavy metals and dioxins in 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 fan 13.

[0055] A sludge incineration system according to the present invention includes an incinerator 1, an SNCR denitration reactor 2, a high-temperature pulse bag filter 3, a flue gas heat exchanger 4, a sludge drying tower 5, a medium- and low-temperature sludge catcher 6, a water washing tower 7, an alkali washing tower 8, and an absorption-desorption tower 9; a burner 1-1 is provided at the lower part of the incinerator 1, a hot flue gas outlet is provided at the top, and the furnace bottom 1-2 is a conical bottom and is provided with a first ash slag 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 through a hot flue gas conveying pipeline; an SNCR denitration reactor 2 is respectively provided in the rising vertical pipe of the hot flue gas conveying pipeline near the hot flue gas outlet and in the descending vertical pipe of the hot flue gas conveying pipeline; a clean hot flue gas outlet is provided at the top of the high-temperature pulse bag filter 3, a hopper 3-1 is provided at the bottom, and the hopper 3-1 is provided with a second ash slag outlet; the first ash slag outlet and the second ash slag outlet are respectively connected to an ash slag bin 14 through corresponding ash slag pneumatic conveying devices 12-2; the clean hot flue gas outlet is connected to the clean hot flue gas inlet of the flue gas heat exchanger 4 through 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 oppositely provided with a cold air inlet and a hot air outlet, and the second-stage heat exchange structure is oppositely provided with a cold wet flue gas inlet and a clean flue gas outlet; one end of the flue gas heat exchanger 4 opposite to the clean hot flue gas outlet is connected to the top of the sludge drying tower 5 through an inlet hot flue gas pipeline; a two-fluid spray gun 5-1 is provided at the upper part of the sludge drying tower 5, the material inlet end of the two-fluid spray gun 5-1 is connected to a sludge conveying pipeline, and the spraying end of the two-fluid spray gun 5-1 faces the upper part inside the sludge drying tower 5; a dirty wet flue gas outlet is provided at the lower part of the sludge drying tower 5, and a first sludge discharge outlet is provided at the bottom; the dirty wet flue gas outlet is connected to the flue gas inlet of the medium- and low-temperature sludge catcher 6 through a dirty wet flue gas pipeline; a second sludge discharge outlet is provided at the bottom of the medium- and low-temperature sludge catcher 6, and a clean wet flue gas outlet is provided at the top; the first sludge discharge outlet and the second sludge discharge outlet are respectively connected to the sludge inlet of the burner 1 through corresponding sludge pneumatic conveying devices 12-1; the clean wet flue gas outlet is connected to the flue gas inlet at the top of the water washing tower 7 through a clean wet flue gas pipeline, the flue gas outlet at the lower part of the water washing tower 7 is connected to the flue gas inlet at the top of the alkali washing tower 8 through a flue gas pipeline, and a drain port at the bottom of the water washing tower 7 is connected to a drain trough; the clean wet flue gas outlet at the lower part of the alkali washing tower 8 is connected to the cold wet flue gas inlet of the flue gas heat exchanger 4 through a clean wet flue gas pipeline; on both sides of the absorption-desorption tower 9 are respectively an absorption zone 9-1 and a desorption zone 9-2, and a porous active medium is provided in the absorption zone 9-1; a runner 9-4 is provided in the middle of the absorption-desorption tower 9, and the absorption zone 9-1 above and below the runner 9-4 is separated from the desorption zone 9-2 by a partition plate 9-3; an adsorbent is provided on the runner 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 through a clean flue gas pipeline; 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 through a hot air pipeline; a clean flue gas outlet is provided at the bottom of the absorption zone 9-1 and is connected to a chimney 11 through a clean flue gas pipeline, and a draft fan 10 is provided on the clean flue gas pipeline;At the bottom of the analysis area 9-2, there is a hot air outlet, which is connected to the hot air inlet of the burner 1-1 through a hot air return pipeline. The fuel inlet of the burner 1-1 is additionally connected to a natural gas pipeline, and a primary air blower 13 is provided on the hot air return pipeline.

[0056] For the sludge incineration process and system of the present invention, a fully enclosed structure and negative pressure operation are adopted. The sludge is directly contacted with the flue gas for dehydration. The sludge dry powder enters the furnace of the incinerator together with air and natural gas through the burner and is incinerated. The flue gas generated by incineration passes through high-temperature dust removal, medium and low-temperature sludge capture, high-temperature flue gas-air heat exchange, dehydration in a water scrubber, and wet acid removal in an alkali scrubber, and then is heated up by a flue gas heat exchanger and enters an absorption - analysis tower to complete the adsorption and removal of VOCs, dioxins, etc. The adsorbent is regenerated by hot air.

[0057] In the water scrubber, a large amount of water vapor in the cold and wet flue gas is precipitated, and at the same time, a certain amount of acidic gas is dissolved. In the alkali scrubber, an alkaline detergent (preferably sodium hydroxide with a mass concentration of 30% as the detergent) is used to remove the acidic gas in the clean and wet flue gas.

[0058] To more intuitively reflect the present invention, the implementation mode of the present invention will be further described in combination with embodiments. The following embodiments are only the preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technical solution that can be obviously obtained by those skilled in the art within the technical scope disclosed by the present invention, including simple changes or equivalent replacements, is within the protection scope of the present invention.

[0059]

Embodiment

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

[0061] 1) Sludge treatment: The sludge is sent to the sludge drying tower 5 through a conveying device. After being atomized by a two-fluid spray gun 5-1, it contacts the hot flue gas at the inlet of the sludge drying tower 5 for dehydration and drying. 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 (in this embodiment, a low-temperature bag filter is used). The sludge intercepted by the medium and low-temperature sludge capture device 6 and the sludge collected by the sludge drying tower 5 are sent to the burner 1-1 on the incinerator 1 by a sludge pneumatic conveying device 12-1, and are incinerated after being mixed with natural gas and hot air. The slag generated by incineration is discharged from the bottom 1-2 of the incinerator 1. The fly ash generated by incineration enters the high-temperature pulse bag filter 3 with the flue gas through the SNCR denitration reactor 2, and the fly ash is intercepted and falls into the ash hopper 3-1 of the high-temperature pulse bag filter 3.

[0062] 2) Treatment of air with peculiar smell: The cold air extracted from each peculiar smell removal point is heated to hot air by the 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 peculiar smell gas absorbed in the absorption zone 9-1. After desorption, the hot air is sent to the burner 1-1 on the incinerator 1 by the primary fan 13 and burned after being mixed with natural gas and dry sludge.

[0063] 3) Flue gas treatment: The hot flue gas (temperature about 850°C) generated by the incineration of dry sludge stays in the incinerator 1 for 2 s and then enters the SNCR denitration reactor 2. After reacting with ammonia water, most of the NOx is removed, and then it enters the high-temperature pulse bag filter 3 for dust removal to become hot clean flue gas. The hot clean flue gas enters the flue gas heat exchanger 4, exchanges heat with cold air and cold flue gas in sequence, and then enters the sludge drying tower 5 (spray drying tower is adopted in this embodiment), and exchanges heat with the sludge atomized by the two-fluid spray gun 5-1. The hot clean flue gas instantly dries the sludge into dirty wet flue gas (temperature about 180°C) carrying a large amount of water vapor and some fine sludge particles and discharges from the outlet of the sludge drying tower 5. The dirty wet flue gas enters the medium and low temperature sludge catcher 6 (low-temperature bag filter is adopted in this embodiment) to capture the sludge in it and becomes clean wet flue gas. The clean wet flue gas enters the water washing tower 7 to quickly cool down, so that the water vapor in the clean wet flue gas precipitates, and then enters the acid removal tower 8 for washing and acid removal. The clean wet flue gas after acid removal returns to the flue gas heat exchanger 4 and becomes clean flue gas after being heated. The clean flue gas enters the absorption zone 9-1 of the absorption-desorption tower 9. The absorption zone 9-1 is used to adsorb pollutants such as residual VOCs, heavy metals, and dioxins in the flue gas. The clean flue gas after absorption and purification is finally sent to the chimney 11 by the induced draft fan 10 for up-to-standard discharge.

[0064] In this embodiment, two sets of pneumatic conveying devices are provided in total. One set is the ash and slag pneumatic conveying device 12-2, which is responsible for sending the ash and slag collected by the incinerator 1 and the high-temperature pulse bag filter 3 to the ash and slag bin 14; the other set is the sludge pneumatic conveying device 12-1, which is responsible for sending 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 adiabatic furnace chamber, which is built with refractory materials, is provided with two sets of dual-fuel burners up and down, the furnace bottom is a conical bottom, and the ash and slag are cooled naturally and conveyed pneumatically.

[0066] In this embodiment, the SNCR denitration reactor 2 is arranged at the center of the hot flue gas outlet at the top of the furnace chamber 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 chamber and at the hot flue gas inlet of the descending vertical pipe, and both are sprayed obliquely downward against the hot flue gas flow direction.

[0067] In this embodiment, the high-temperature pulse bag filter 3 adopts 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 purified wet flue gas after desulfurization. The temperature of the hot purified 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 type sludge drying process. The sludge is atomized by a two-fluid spray gun 5-1 and then sprayed into the tower, directly contacting the dry flue gas and being instantly dried. The inner lining of the spray drying tower is made of refractory heat-insulating material, and the bottom of the tower is a conical bottom. The sludge is pneumatically transported.

[0070] In this embodiment, the medium and low temperature sludge catcher 6 adopts a low-temperature bag filter. The inlet flue gas temperature is about 200°C, and the sludge is pneumatically transported.

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

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

[0073] In this embodiment, the absorption and desorption tower 9 is provided with a porous active medium in the absorption zone 9-1 for adsorbing VOCs, heavy metals, and dioxins in the clean flue gas. The absorption and desorption tower 9 is a cylindrical structure. In the middle, partitions 9-3 are provided on both sides of the rotating wheel 9-4 to separate the absorption zone 9-1 and the desorption zone 9-2 into two independent regions. An adsorbent is provided on the rotating wheel 9-4. The rotating wheel 9-4 alternately reciprocates through the absorption zone 9-1 and the desorption zone 9-2, and the adsorbent alternately reciprocates in contact with the clean flue gas and hot air. The adsorbent adsorbs VOCs, heavy metals, and dioxins in the clean flue gas. After the hot air heats the adsorbent, the VOCs and dioxins adsorbed by the adsorbent are desorbed and carried to the incinerator 1 by the hot air for incineration.

[0074] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A sludge incineration process, characterized in that, It includes the following processes: 1) Sludge treatment process: The sludge is sent to the upper part of the sludge drying tower, atomized by a two-fluid spray gun, and then contacts with the hot flue gas at the inlet of the sludge drying tower to dehydrate and dry. 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 catcher; the sludge intercepted by the medium and low temperature sludge catcher and the sludge collected by the sludge drying tower are respectively sent to the burner at the upper part of the incinerator through the sludge pneumatic conveying device, and burned after being mixed with natural gas and hot air; the slag generated by burning is discharged from the bottom of the furnace, and the fly ash generated by burning enters the high-temperature pulse bag filter after denitrification by the SNCR denitrification reactor, and the intercepted fly ash falls into the bottom ash hopper. 2) Odorous air treatment process: The cold air extracted from each odor removal point is heated and becomes hot air after heat exchange with the hot flue gas from the incinerator and passing through dust removal in the flue gas heat exchanger. The hot air enters the desorption zone of the absorption-desorption tower to desorb the odor gas containing VOCs absorbed in the absorption zone. After desorption, the hot air is sent to the burner of the incinerator by the primary fan, and burned after being mixed with natural gas and dry sludge to form hot flue gas. 3) Flue gas treatment process: The hot flue gas above 850 °C is generated after the dry sludge is burned in the incinerator. The hot flue gas stays in the incinerator for more than 2 s and then enters the SNCR denitrification reactor, and reacts with ammonia water to remove most of the NOx; then it enters the high-temperature pulse bag filter for dust removal and becomes clean hot flue gas; the clean hot flue gas enters the flue gas heat exchanger, exchanges heat with the cold air and cold flue gas in sequence, and then enters the sludge drying tower to exchange heat with the sludge atomized by the two-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, and the temperature of the dirty wet flue gas is lower than 180 °C; the dirty wet flue gas is discharged from the sludge drying tower and enters the medium and low temperature sludge catcher to capture the sludge in it to become clean wet flue gas; the clean wet flue gas first enters the water washing tower, the water vapor in it is precipitated after rapid cooling, and then enters the alkali washing tower for washing and acid removal; the clean wet flue gas after acid removal returns to the flue gas heat exchanger, is heated and becomes clean flue gas after heat exchange; the clean flue gas enters the absorption zone in the absorption-desorption tower to adsorb and remove the pollutants remaining in the flue gas including VOCs, heavy metals, and dioxins, and finally is sent to the chimney for emission through 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 bin through the ash and slag pneumatic conveying device.

2. The sludge incineration process according to claim 1, characterized in that, The incinerator adopts an adiabatic furnace lined with refractory materials. Two groups of burners are arranged along the height direction at the lower part of the incinerator, and the burners are dual-fuel burners; the bottom of the incinerator is a conical bottom, and the ash and slag are cooled naturally.

3. A sludge incineration process according to claim 1, characterized in that, There are 2 groups of SNCR denitrification reactors, which are respectively arranged at the center position above the furnace chamber 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 guns in the SNCR denitrification reactor are arranged at the hot flue gas inlet of the SNCR denitrification reactor, and spray ammonia water obliquely inward and downward against the flow of the hot flue gas.

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

5. A 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 purified wet flue gas after acid removal. The temperature of the hot purified flue gas at the outlet of the flue gas heat exchanger is below 700°C.

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 two-fluid spray gun and then sprayed into the tower, where it is instantaneously dried upon direct contact with the inlet hot flue gas. The inner lining of the sludge drying tower is made of refractory and heat-insulating materials or is built with refractories, and the bottom of the tower is a conical bottom.

7. A sludge incineration process according to claim 1, characterized in that, The medium and low temperature sludge catcher adopts a low-temperature bag filter, and the temperature of the inlet cold and wet flue gas is below 200°C.

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

9. A sludge incineration process according to claim 1, characterized in that, The absorption-desorption tower integrates the functions of absorption and desorption. The two sides are respectively an absorption zone and a desorption zone; the absorption zone uses a porous active medium to adsorb VOCs, heavy metals, and dioxins in the clean flue gas; a rotating wheel is arranged in the middle of the absorption-desorption tower, and the absorption zones above and below the rotating wheel are separated from the desorption zone by a partition; an adsorbent is arranged on the rotating wheel. As the rotating wheel rotates, the adsorbent on it alternately passes through the absorption zone to contact the clean flue gas and through the desorption zone to contact the hot air; in the absorption zone, the adsorbent adsorbs VOCs, heavy metals, and dioxins in the clean flue gas. 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 incineration by a primary fan.

10. A sludge incineration system for implementing the sludge incineration process according to any one of claims 1 to 9, characterized in that, It includes an incinerator, an SNCR denitration reactor, a high-temperature pulse bag filter, a flue gas heat exchanger, a sludge drying tower, a medium and low temperature sludge catcher, a water washing tower, an alkali washing tower, and an absorption-desorption tower; a burner is arranged at the lower part of the incinerator, a hot flue gas outlet is arranged at the top, the bottom of the furnace is a conical bottom and is provided with a slag outlet one; 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 through a hot flue gas conveying pipeline; an SNCR denitration reactor is respectively arranged in the rising vertical pipe and the falling vertical pipe of the hot flue gas conveying pipeline near the hot flue gas outlet; a net hot flue gas outlet is arranged at the top of the high-temperature pulse bag filter, a dust hopper is arranged at the bottom, and the dust hopper is provided with a slag outlet two; the slag outlet one and the slag outlet two are respectively connected to the slag bin through corresponding slag pneumatic conveying devices; the net hot flue gas outlet is connected to the net hot flue gas inlet of the flue gas heat exchanger through a net hot flue gas pipeline; the flue gas heat exchanger has a two-stage heat exchange structure. The first-stage heat exchange structure is relatively provided with a cold air inlet and a hot air outlet, and the second-stage heat exchange structure is relatively provided with a cold and wet flue gas inlet and a clean flue gas outlet; one end of the flue gas heat exchanger opposite to the net hot flue gas outlet is connected to the top of the sludge drying tower through an inlet hot flue gas pipeline; a two-fluid spray gun is arranged at the upper part of the sludge drying tower, the material inlet end of the two-fluid spray gun is connected to the sludge conveying pipeline, and the spraying end of the two-fluid spray gun faces the upper part inside the sludge drying tower; a dirty and wet flue gas outlet is arranged at the lower part of the sludge drying tower, and a sludge discharge outlet one is arranged at the bottom. The dirty and wet flue gas outlet is connected to the flue gas inlet of the medium and low temperature sludge catcher through a dirty and wet flue gas pipeline; a sludge discharge outlet II is provided at the bottom of the medium and low temperature sludge catcher, and a clean and wet flue gas outlet is provided at the top; the sludge discharge outlet I and the sludge discharge outlet II are respectively connected to the sludge inlet of the burner through corresponding sludge pneumatic conveying devices; the clean and wet flue gas outlet is connected to the flue gas inlet at the top of the water washing tower through a clean and wet flue gas pipeline, the flue gas outlet at the lower part of the water washing tower is connected to the flue gas inlet at the top of the alkali washing tower through a flue gas pipeline, and a drain outlet is provided at the bottom of the water washing tower and connected to a drain tank; the clean and wet flue gas outlet at the lower part of the alkali washing tower is connected to the cold and wet flue gas inlet of the flue gas heat exchanger through a clean and wet flue gas pipeline; on both sides of the absorption - desorption tower are respectively an absorption zone and a desorption zone, and a porous active medium is provided in the absorption zone; a runner is provided in the middle of the absorption - desorption tower, and the absorption zones above and below the runner are separated from the desorption zones by partition plates; an adsorbent is provided on the runner; 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 provided at the bottom of the absorption zone and connected to a chimney through a clean flue gas pipeline, and a draft fan is provided on the clean flue gas pipeline; a hot air outlet is provided at the bottom of the desorption zone and connected to the hot air inlet of the burner through a hot air return pipeline, the fuel inlet of the burner is additionally connected to a natural gas pipeline, and a primary air fan is provided on the hot air return pipeline.

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