Preparation method and production system of fly ash sintered ceramsite

Abstract

The invention belongs to the technical field of waste incineration fly ash resource utilization, and relates to a fly ash sintered ceramsite preparation method which comprises the steps that S10, household waste is conveyed to a waste incineration system to be incinerated, generated flue gas is divided into two paths, and one path is conveyed to a flue gas treatment system; s20, flue gas generated after treatment of the flue gas treatment system is discharged through a chimney, and generated fly ash is conveyed to a mixing and stirring tank, mixed with other raw materials and then subjected to granulation and sintering to prepare fly ash sintered ceramsite; s30, the sintering flue gas is sequentially conveyed to a cooling system and a cloth bag dust removal system to be treated, the treated sintering flue gas is conveyed to a flue gas treatment system to be treated, meanwhile, generated secondary fly ash is conveyed to an ash washing system to be treated, and formed plaster is conveyed to a mixing and stirring tank to serve as one of raw materials for sintering ceramsite through the fly ash; and S40, the other path of flue gas in the step S10 is conveyed to a sintering system. By combining the waste incineration fly ash with the ceramsite sintering technology, energy conservation and consumption reduction are achieved.

Description

Technical Field

[0001] This invention relates to the field of waste incineration fly ash resource utilization technology, specifically to a method and production system for preparing fly ash sintered ceramsite. Background Technology

[0002] Currently, most fly ash from waste incineration is solidified and stabilized before being sent to municipal solid waste landfills. Solidifying and stabilizing fly ash for landfilling consumes a large amount of land resources, and the stability of chelated fly ash is easily compromised after many years, posing a risk of secondary pollution to the environment. It is ultimately just a stopgap measure and difficult to achieve long-term development. Near-zero landfilling and high-value utilization of fly ash are urgently needed at present.

[0003] Existing fly ash resource utilization technologies mainly include fly ash water washing cement kiln co-processing technology and fly ash high-temperature sintering technology. The fly ash water washing cement kiln co-processing technology is limited by the geographical location of cement kilns and affected by cement kiln shutdown policies. The fly ash high-temperature sintering process has high energy consumption and is not economically viable. Summary of the Invention

[0004] The purpose of this invention is to provide a method and production system for preparing fly ash sintered ceramsite, which combines waste incineration fly ash with ceramsite sintering technology to achieve energy conservation and consumption reduction.

[0005] To achieve this objective, the present invention adopts the following technical solution: On one hand, the present invention provides a method for preparing fly ash sintered ceramsite, comprising the following steps: S10. The municipal solid waste is transported to the waste incineration system for incineration. The resulting flue gas is divided into two paths, one of which is transported to the flue gas treatment system. S20. The flue gas generated after being treated by the flue gas treatment system is discharged through the chimney, and the fly ash generated is transported to the mixing tank, mixed with other raw materials, and then granulated and sintered to obtain fly ash sintered ceramsite. S30. The sintering flue gas generated during the sintering process is sequentially transported to the cooling system and the bag filter dust removal system for treatment. The treated sintering flue gas is then transported to the flue gas treatment system for further treatment. At the same time, the secondary fly ash generated after treatment is transported to the ash washing system for treatment. The resulting sludge is then transported to the mixing tank as one of the raw materials for fly ash sintered ceramsite. S40. The other flue gas from step S10 is delivered to the sintering system to supplement the heat of the sintering system.

[0006] This invention achieves energy conservation and emission reduction by synergistically combining fly ash and flue gas from waste incineration. This method effectively promotes the inherent unity and mutual reinforcement of socio-economic and ecological benefits in fly ash treatment technology, while contributing to China's early achievement of "carbon peaking and carbon neutrality."

[0007] On the other hand, the present invention provides a production system for implementing the aforementioned method for preparing fly ash sintered ceramsite, comprising: Waste incineration systems are used to incinerate municipal solid waste; The flue gas treatment system and the chimney, the flue gas outlet of the waste incineration system are connected to two branches, one of which is connected to the flue gas inlet of the flue gas treatment system, and the flue gas outlet of the flue gas treatment system is connected to the flue gas inlet of the chimney through an induced draft fan. A mixing tank is used to mix and stir fly ash and other raw materials generated by a flue gas treatment system to form a mixed slurry; A granulation system used to form pellets from a mixed slurry; The sintering system is used to sinter the green particles to form fly ash sintered ceramsite. The flue gas outlet of the waste incineration system is connected to the sintering system through another branch. The cooling system and the bag filter dust collection system are connected in sequence. The sintering flue gas outlet of the sintering system is connected to the cooling system and the bag filter dust collection system. The sintering flue gas outlet of the bag filter dust collection system is connected to the flue gas treatment system. The ash washing system is used to wash the secondary fly ash after it has been treated by the bag filter dust collection system. The ash sludge outlet of the ash washing system is connected to the mixing tank.

[0008] The beneficial effects of this invention are: This invention combines waste incineration flue gas co-processing technology, significantly reducing energy consumption in traditional sintering processes. Utilizing a high-temperature fly ash sintering process, complete decomposition of dioxins in fly ash can be achieved.

[0009] This invention first sinters the original fly ash, and the non-volatile heavy metals in the fly ash are completely solidified by the sintered body. Then, water washing technology is used to dechlorinate and remove heavy metals from a small amount of secondary fly ash (about 30% of the original fly ash) that is rich in salt and volatile heavy metals, which greatly reduces the energy consumption of water washing and the cost of water washing liquid treatment and evaporation.

[0010] In this invention, the flue gas generated during the high-temperature sintering of fly ash is incorporated into the main flue gas treatment system of waste incineration for co-processing, which greatly reduces the cost of fly ash resource utilization and disposal, while not affecting the emission requirements of the main flue gas of waste incineration. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the fly ash sintered ceramsite production system of the present invention; Figure 2 This is a schematic diagram of the ash washing system of the present invention; Figure 3 This is a schematic diagram of the fly ash sintered ceramsite production system of Comparative Example 2; Figure 4 This is a schematic diagram of the ash washing system in Comparative Example 2. Detailed Implementation

[0012] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0013] The preparation method of fly ash sintered ceramsite in this embodiment includes the following steps: S10. The municipal solid waste is transported to the waste incineration system for incineration. The resulting flue gas is divided into two paths, one of which is transported to the flue gas treatment system. S20. The flue gas generated after being treated by the flue gas treatment system is discharged through the chimney, and the fly ash generated is transported to the mixing tank, mixed with other raw materials, and then granulated and sintered to obtain fly ash sintered ceramsite. S30. The sintering flue gas generated during the sintering process is sequentially transported to the cooling system and the bag filter dust removal system for treatment. The treated sintering flue gas is then transported to the flue gas treatment system for further treatment. At the same time, the secondary fly ash generated after treatment is transported to the ash washing system for treatment. The resulting sludge is then transported to the mixing tank as one of the raw materials for fly ash sintered ceramsite. S40. The other flue gas from step S10 is delivered to the sintering system to supplement the heat of the sintering system.

[0014] As a further embodiment of the method for preparing fly ash sintered ceramsite, the ash washing system in step S30 includes a pre-dissolving tank and a three-stage countercurrent water washing mechanism connected in series with the pre-dissolving tank. The secondary fly ash in step S30 is transported to the pre-dissolving tank and dissolved using the secondary water washing filtrate in the three-stage countercurrent water washing mechanism to form a mixed slurry. The sludge produced after treatment by the three-stage countercurrent water washing mechanism is transported to a mixing tank.

[0015] In other embodiments, in step S10, the domestic waste may first be stored in a waste storage pit, and then the domestic waste in the waste storage pit may be transported to a waste incineration system for incineration.

[0016] In step S20, the fly ash generated after being treated by the flue gas treatment system can be temporarily stored in a buffer tank, mixed with other raw materials in other raw material silos, and water and additives are added. After being fully mixed, it is then granulated and sintered to prepare fly ash sintered ceramic particles.

[0017] In step S40, the heat source for the sintering system comes from the high-temperature flue gas generated by the waste incineration system, as well as a small amount of natural gas or diesel added as needed. By introducing high-temperature flue gas into the sintering system, energy consumption can be effectively reduced.

[0018] As a further method for preparing fly ash sintered ceramsite, a mechanical stirrer is used in the pre-dissolving tank for stirring under the following conditions: 100-1000 r / min for 10-60 min, preferably 500 r / min for 30 min.

[0019] As a further embodiment of the method for preparing fly ash sintered ceramsite, the mixed slurry in the pre-dissolving tank is pumped to the primary washing tank for the first water washing and dechlorination by a slurry pump. Then, the slurry in the primary washing tank is pumped to the primary centrifuge for dewatering by a slurry pump. The resulting primary water washing filtrate enters the fly ash washing wastewater treatment and evaporation crystallization salt system. The dewatered sludge is pumped to the secondary washing tank for the second water washing and dechlorination by a sludge pump. Then, the slurry in the secondary washing tank is pumped to the secondary centrifuge for dewatering by a slurry pump. The resulting secondary water washing filtrate is reused in the pre-dissolving tank. The dewatered sludge is pumped to the tertiary washing tank for the third water washing and dechlorination by a sludge pump. Then, the slurry in the tertiary washing tank is pumped to the tertiary filter press for dewatering by a slurry pump. The resulting tertiary water washing filtrate is reused in the secondary washing tank. The dewatered sludge is pumped to the mixing tank by a sludge pump. The evaporation condensate generated by the fly ash washing wastewater treatment and evaporation crystallization salt system is pumped to the tertiary washing tank.

[0020] As a further embodiment of the method for preparing fly ash sintered ceramsite, the water-ash mass ratio in the three-stage ash washing tank is no greater than 2.5:1, preferably 2.0:1.

[0021] As a further embodiment of the method for preparing fly ash sintered ceramsite, the mass ratio of fly ash, sludge and other raw materials in the mixing tank is (5-30):(0.5-3):(67-94.5), preferably (5-15):(0.5-1.5):(83.5-94.5).

[0022] As a further method for preparing fly ash sintered ceramsite, the sintering conditions are 1000-1350℃, preferably 1200-1250℃.

[0023] As a further method for preparing fly ash sintered ceramsite, the sintering time is 10-60 min, preferably 30 min.

[0024] The particle size of the fly ash sintered ceramsite is 1-20mm, preferably 8-15mm.

[0025] On the other hand, a production system for implementing the aforementioned method for preparing fly ash sintered ceramsite (hereinafter referred to as a fly ash sintered ceramsite production system) is provided, such as... Figure 1 As shown, the fly ash sintered ceramsite production system includes: Waste incineration systems are used to incinerate municipal solid waste; The flue gas treatment system and the chimney, the flue gas outlet of the waste incineration system are connected to two branches, one of which is connected to the flue gas inlet of the flue gas treatment system, and the flue gas outlet of the flue gas treatment system is connected to the flue gas inlet of the chimney through an induced draft fan. A mixing tank is used to mix and stir fly ash and other raw materials generated by a flue gas treatment system to form a mixed slurry; A granulation system is used to granulate a mixed slurry to form ceramsite blanks; The sintering system is used to sinter the green particles to form fly ash sintered ceramsite. The flue gas outlet of the waste incineration system is connected to the sintering system through another branch. The cooling system and the bag filter dust collection system are connected in sequence. The sintering flue gas outlet of the sintering system is connected to the cooling system and the bag filter dust collection system. The sintering flue gas outlet of the bag filter dust collection system is connected to the flue gas treatment system. The ash washing system is used to wash the secondary fly ash after it has been treated by the bag filter dust collection system. The ash sludge outlet of the ash washing system is connected to the mixing tank.

[0026] Furthermore, the fly ash sintered ceramsite production system also includes a waste storage pit for storing municipal solid waste.

[0027] Furthermore, the fly ash sintered ceramsite production system also includes buffer tanks for buffering fly ash from the flue gas treatment system and other raw material silos for storing other raw materials (excluding sludge). Specifically, the other raw material silos are used to store raw materials other than water, additives, fly ash, and sludge, including one or more of sludge, slag, fly ash, furnace slag, and clay.

[0028] The flue gas treatment system includes a waste heat boiler and an SNCR in the waste heat boiler, as well as a semi-dry reaction tower, a dry reaction tower, a bag filter, and a wet reaction tower connected in sequence by pipelines. The flue gas outlet of the waste heat boiler is connected to the flue gas inlet of the semi-dry reaction tower, and the flue gas outlet of the wet reaction tower is connected to the flue gas inlet of the chimney.

[0029] Furthermore, such as Figure 2 As shown, the ash washing system includes a pre-dissolving tank, a primary ash washing tank, a primary centrifuge, a secondary ash washing tank, a secondary centrifuge, a tertiary ash washing tank, and a tertiary centrifuge connected in series. The secondary fly ash outlet of the bag filter system and the secondary water washing filtrate outlet of the secondary centrifuge are connected to the pre-dissolving tank, and the tertiary water washing filtrate outlet of the tertiary filter press is connected to the secondary ash washing tank. The ash washing system also includes an ash washing wastewater treatment and evaporation crystallization salt system, a primary centrifuge and a water washing filtrate outlet connected to the ash washing wastewater treatment and evaporation crystallization salt system, and an evaporation condensate outlet connected to a tertiary ash washing tank.

[0030] The following specific embodiments and comparative examples based on the above-described fly ash sintered ceramsite production system further illustrate the preparation method of fly ash sintered ceramsite of the present invention.

[0031] Example 1 The domestic waste in the waste storage pit is transported to the waste incineration furnace of the waste incineration system for incineration. The generated flue gas is divided into two paths. One path is sent to the flue gas treatment system, and the other path is sent to the sintering system to supplement the heat of the sintering system. The flue gas treatment system includes a waste heat boiler and an SNCR in the waste heat boiler, as well as a semi-dry reaction tower, a dry reaction tower, a bag filter, and a wet reaction tower connected in sequence by pipelines. The flue gas outlet of the waste heat boiler is connected to the flue gas inlet of the semi-dry reaction tower, and the flue gas outlet of the wet reaction tower is connected to the flue gas inlet of the chimney. The generated fly ash is transported to a buffer tank, mixed with other raw materials in other raw material silos, and then granulated and sintered to obtain fly ash sintered ceramsite. The sintering flue gas generated during the sintering process is sequentially transported to the cooling system and the bag filter dust collection system for treatment. The treated sintering flue gas is then transported to the flue gas treatment system for further processing. Simultaneously, the secondary fly ash generated after treatment is transported to the pre-dissolving tank of the ash washing system, where secondary water washing filtrate from the secondary centrifuge is added and stirred to form a mixed slurry. The mixed slurry enters the primary ash washing tank for the first water washing and dechlorination. The slurry in the primary ash washing tank is pumped into the primary centrifuge for dewatering via an ash slurry pump. The primary water washing filtrate then enters the ash washing wastewater treatment and evaporation crystallization salt system. The dewatered sludge is pumped into the secondary washing tank and undergoes a second washing and dechlorination process using the same procedure. The slurry in the secondary washing tank is then pumped into a secondary centrifuge for dewatering. The secondary washing filtrate is recycled to the pre-dissolving tank. The dewatered sludge is then pumped into the tertiary washing tank and a metered amount of water (evaporation condensate + makeup water) is added at a water-to-sludge mass ratio of 2.5:1 for a third washing and dechlorination process. The stirring speed is 500 r / min, and the washing time is 30 min. The slurry in the tertiary washing tank is then pumped into a tertiary filter press for dewatering. The tertiary washing filtrate is recycled to the secondary washing tank. The dewatered sludge is then pumped into the mixing tank before the granulation system.

[0032] The output of the primary centrifuge and the washing liquid outlet are connected to the ash washing wastewater treatment and evaporation crystallization salt system.

[0033] The mass ratio of fly ash, sludge (sludge produced after washing in the ash washing system) to other raw materials is 15:1.5:83.5. The mixed raw materials are sent to the granulation system for granulation, with a particle size of 8-15mm. After granulation, the materials are sintered at high temperature in the sintering system. A vertical furnace is used for sintering at a sintering temperature of 1250℃ and a sintering residence time of 45 minutes to obtain fly ash sintered ceramsite.

[0034] The heat source for the sintering system comes from the high-temperature flue gas generated by the waste incineration system and a certain amount of natural gas. The natural gas consumption is 30 m³ / ton of fly ash.

[0035] The direct cost of fly ash treatment is 825 yuan / ton of fly ash.

[0036] Example 2 This embodiment is basically the same as Embodiment 1 above, except that: Add a measured amount of water (evaporated condensate + makeup water) at a water-cement ratio of 2.0:1 for the third water washing and dechlorination, with a stirring speed of 1000 r / min and washing for 15 min; The mass ratio of fly ash, sludge and other raw materials is 10:1:89; Granulation: The uniformly mixed raw materials are fed into the granulation system for granulation, with a particle size of 5-8 mm; After granulation, the sintering process is carried out in a sintering system at a high temperature of 1200℃ and a sintering residence time of 60 min to obtain fly ash sintered ceramsite. The heat source for the sintering system comes from the high-temperature flue gas generated by the waste incineration system and a certain amount of natural gas. The natural gas consumption is 35 m³ / ton of fly ash.

[0037] Example 3 This embodiment is basically the same as Embodiment 1 above, except that: Add a fixed amount of water (evaporated condensate + makeup water) at a total water-cement mass ratio of 2.3:1 for the third water washing and dechlorination, with a stirring speed of 800 r / min and washing for 20 min; The mass ratio of fly ash, sludge, and other raw materials is 5:0.5:94.5; Granulation: The uniformly mixed raw materials are fed into the granulation system for granulation, with a particle size of 15-18mm; After granulation, the sintering process is carried out in a sintering system at a high temperature of 1300℃ and a sintering residence time of 30 min to obtain fly ash sintered ceramsite. The heat source for the sintering system comes from the high-temperature flue gas generated by the waste incineration system and a certain amount of natural gas. The natural gas consumption is 25 m³ / ton of fly ash.

[0038] Comparative Example 1 The preparation method of the fly ash sintered ceramsite in this comparative example is basically the same as that in Example 1 above, except that the heat source of the sintering system is only natural gas, and the natural gas consumption is 108 m³ / ton of fly ash.

[0039] The direct cost of fly ash treatment is 1128 yuan / ton of fly ash.

[0040] Comparative Example 2 The fly ash sintered ceramsite in Comparative Example 2 was prepared using a process of first washing the fly ash with water and then sintering it. Figure 3 and Figure 4 As shown in the figure. In this case, the mass ratio of sludge, secondary fly ash and other raw materials in the mixing tank is 15:2.5:82.5, and other conditions are basically the same as in Example 1 above. The direct cost of fly ash treatment is 920 yuan / ton of fly ash.

[0041] The fly ash from the production systems in the above embodiments and comparative examples was tested in accordance with the "Technical Specification for Pollution Control of Fly Ash from Municipal Solid Waste Incineration (Trial)" (HJ1134-2020). The chloride ions, dioxins, heavy metals, and other substances in the fly ash treatment products all met the relevant requirements of the "Technical Specification for Pollution Control of Fly Ash from Municipal Solid Waste Incineration (Trial)" (HJ1134-2020).

[0042] The above embodiments are only used to illustrate the detailed method of the present invention. The present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing fly ash sintered ceramsite, characterized in that, Includes the following steps: S10. The municipal solid waste is transported to the waste incineration system for incineration. The resulting flue gas is divided into two paths, one of which is transported to the flue gas treatment system. S20. The flue gas generated after being treated by the flue gas treatment system is discharged through the chimney, and the fly ash generated is transported to the mixing tank, mixed with other raw materials, and then granulated and sintered to obtain fly ash sintered ceramsite. S30. The sintering flue gas generated during the sintering process is sequentially transported to the cooling system and the bag filter dust removal system for treatment. The treated sintering flue gas is then transported to the flue gas treatment system for further treatment. At the same time, the secondary fly ash generated after treatment is transported to the ash washing system for treatment. The resulting sludge is then transported to the mixing tank as one of the raw materials for fly ash sintered ceramsite. S40. The other flue gas from step S10 is sent to the sintering system to supplement the heat of the sintering system.

2. The method for preparing fly ash sintered ceramsite according to claim 1, characterized in that, The ash washing system in step S30 includes a pre-dissolving tank and a three-stage countercurrent water washing mechanism connected in series with the pre-dissolving tank. The secondary fly ash in step S30 is transported to the pre-dissolving tank and dissolved using the secondary water washing filtrate in the three-stage countercurrent water washing mechanism to form a mixed slurry. The sludge produced after treatment by the three-stage countercurrent water washing mechanism is transported to a mixing tank.

3. The method for preparing fly ash sintered ceramsite according to claim 2, characterized in that, The pre-dissolving tank is stirred using a mechanical stirrer under the following conditions: 100-1000 r / min for 10-60 min, preferably 500 r / min for 30 min.

4. The method for preparing fly ash sintered ceramsite according to claim 2, characterized in that, The mixed slurry in the pre-dissolving tank is pumped to the primary washing tank for the first water washing and dechlorination. Then, the slurry in the primary washing tank is pumped to the primary centrifuge for dewatering. The resulting primary water washing filtrate enters the washing wastewater treatment and evaporation crystallization salt system. The dewatered sludge is pumped to the secondary washing tank for the second water washing and dechlorination. Then, the slurry in the secondary washing tank is pumped to the secondary centrifuge for dewatering. The resulting secondary water washing filtrate is reused in the pre-dissolving tank. The dewatered sludge is pumped to the tertiary washing tank for the third water washing and dechlorination. Then, the slurry in the tertiary washing tank is pumped to the tertiary filter press for dewatering. The resulting tertiary water washing filtrate is reused in the secondary washing tank. The dewatered sludge is pumped to the mixing tank. The evaporation condensate generated by the washing wastewater treatment and evaporation crystallization salt system is pumped to the tertiary washing tank.

5. The method for preparing fly ash sintered ceramsite according to claim 4, characterized in that, The water-to-ash ratio in the three-stage ash washing tank should not exceed 2.5:1, and is preferably 2.0:

1.

6. The method for preparing fly ash sintered ceramsite according to claim 1, characterized in that, The mass ratio of fly ash, sludge and other raw materials in the mixing tank is (5-30):(0.5-3):(67-94.5), preferably (5-15):(0.5-1.5):(83.5-94.5).

7. The method for preparing fly ash sintered ceramsite according to any one of claims 1 to 5, characterized in that, The sintering temperature is 1000-1350℃, preferably 1200-1250℃.

8. The method for preparing fly ash sintered ceramsite according to any one of claims 1 to 5, characterized in that, The sintering time is 10-60 min, preferably 30 min.

9. A production system for implementing the method for preparing fly ash sintered ceramsite according to any one of claims 1 to 8, characterized in that, include: Waste incineration systems are used to incinerate municipal solid waste; The flue gas treatment system and the chimney, the flue gas outlet of the waste incineration system are connected to two branches, one of which is connected to the flue gas inlet of the flue gas treatment system, and the flue gas outlet of the flue gas treatment system is connected to the flue gas inlet of the chimney through an induced draft fan. A mixing tank is used to mix and stir fly ash and other raw materials generated by a flue gas treatment system to form a mixed slurry; A granulation system used to form pellets from a mixed slurry; The sintering system is used to sinter the green particles to form fly ash sintered ceramsite. The flue gas outlet of the waste incineration system is connected to the sintering system through another branch. The cooling system and the bag filter dust collection system are connected in sequence. The sintering flue gas outlet of the sintering system is connected to the cooling system and the bag filter dust collection system. The sintering flue gas outlet of the bag filter dust collection system is connected to the flue gas treatment system. The ash washing system is used to wash the secondary fly ash after it has been treated by the bag filter dust collection system. The ash sludge outlet of the ash washing system is connected to the mixing tank.

10. The production system according to claim 9, characterized in that, The ash washing system includes a pre-dissolving tank, a primary ash washing tank, a primary centrifuge, a secondary ash washing tank, a secondary centrifuge, a tertiary ash washing tank, and a tertiary filter press connected in series. The secondary fly ash outlet of the bag filter system and the secondary water washing filtrate outlet of the secondary centrifuge are connected to the pre-dissolving tank, and the tertiary water washing filtrate outlet of the tertiary filter press is connected to the secondary ash washing tank. The ash washing system also includes an ash washing wastewater treatment and evaporation crystallization salt system. The primary water washing filtrate outlet of the primary centrifuge is connected to the ash washing wastewater treatment and evaporation crystallization salt system, and the evaporation condensate outlet of the ash washing wastewater treatment and evaporation crystallization salt system is connected to the tertiary ash washing tank.

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