CN-121130640-B - Treatment system and method for waste incineration fly ash washing liquid and flue gas purification in cooperation

CN121130640BCN 121130640 BCN121130640 BCN 121130640BCN-121130640-B

Abstract

The invention discloses a treatment system and a method for waste incineration fly ash water washing liquid cooperated with flue gas purification, wherein the system comprises a semi-dry desulfurizing tower, a dust remover, an ash warehouse, a water washing tank, a buffer tank, a water supply preheater and a wet washing tower which are connected with a main flue of an incineration plant; spraying ash flying washing liquid by a wet method washing tower, recovering waste heat of tail flue gas, deeply removing residual acid gas in the flue gas, concentrating and reducing the washing liquid, controlling the spraying quantity to adjust the concentration multiplying power to realize precipitation of chloride salt and solid-liquid separation, introducing the concentrated washing liquid into a semi-dry desulfurizing tower, atomizing the washing liquid into fine liquid drops by a rotary atomizer, contacting with hot flue gas, evaporating to dryness, absorbing the acid gas in the flue gas, realizing zero emission of the washing liquid and purifying the flue gas in a synergic manner. The invention solves the problem of high energy consumption of the treatment of the fly ash washing liquid and improves the recycling utilization rate of the washing liquid.

Inventors

ZHAN LINGXIAO
LU SHENGYONG
PENG YAQI
WU YUJIA
TANG MINGHUI
YAN JIANHUA

Assignees

浙江大学

Dates

Publication Date: 20260512
Application Date: 20250926

Claims (10)

1. The utility model provides a processing system of msw incineration flying ash washing liquid concentration decrement cooperation flue gas purification which characterized in that, processing system includes: the washing tank is connected with the ash bin, and is connected with process water through a process water inlet and a medicament through a medicament inlet; the buffer tank is positioned between the water washing tank and the wet method washing tower and is used for storing the water washing liquid obtained by separation in the water washing tank; The wet method washing tower, the water washing liquid in the buffer tank enters the slurry pool in the wet method washing tower through the water inlet pump, the top of the wet method washing tower is provided with a demister, the middle part of the wet method washing tower is provided with a spraying device consisting of pressure nozzles, the water washing liquid in the slurry pool is conveyed into the pressure nozzles through the circulating pump to be sprayed and concentrated, and the concentrated fly ash water washing liquid enters the semi-dry desulfurization tower through the outlet pump; The flue gas enters the semi-dry desulfurization tower through an inlet flue, and concentrated fly ash water washing liquid in the wet scrubber enters the semi-dry desulfurization tower and then is mixed with desulfurization slurry and enters an atomizer to be atomized into fine droplets; The dust remover is connected with the semi-dry desulfurization outlet flue and is used for separating fly ash in the flue gas, the flue gas after the fly ash is separated enters from the lower part of the wet scrubber, is purified by spraying water washing liquid through a pressure nozzle in the middle part of the wet scrubber, and the purified flue gas flows out through a flue gas outlet at the top of the wet scrubber; and the ash bin is used for receiving the desulfurization ash from the semi-dry desulfurization tower and the fly ash obtained by separation of the dust remover.
2. The treatment system for the waste incineration fly ash water washing liquid concentration decrement collaborative flue gas purification according to claim 1, wherein a feed water preheater is further arranged between the buffer tank and the wet scrubber, and the feed water preheater is connected with hot water of the economizer to exchange heat with the water washing liquid from the buffer tank.
3. The treatment system for the waste incineration fly ash water washing liquid concentration decrement synergistic flue gas purification according to claim 1 is characterized in that a slurry pool at the bottom of the wet scrubber is provided with a conductivity meter and a liquid level meter, and a demister at the top of the wet scrubber is a silk-screen demister.
4. The treatment system for waste incineration fly ash water washing liquid concentration decrement cooperation flue gas purification according to claim 1, wherein the atomizer in the semi-dry desulfurization tower is a rotary atomizer.
5. The treatment system for the waste incineration fly ash water washing liquid concentration decrement cooperation flue gas purification according to claim 1 is characterized in that one or more groups of pressure nozzles of the spraying device are arranged, and the solid-liquid separation device is one or a combination of a cyclone, a centrifuge or a vacuum filter.
6. A method for treating waste incineration fly ash water washing liquid concentration decrement cooperated flue gas purification based on the system of any one of claims 1-5, which is characterized by comprising the following steps: The waste incineration fly ash collected by the semi-dry desulfurizing tower and the dust remover is transported to an ash warehouse for storage; Transferring the fly ash in the ash warehouse to a washing tank, mixing the fly ash with process water in the washing tank, adding a medicament, stirring and washing, and carrying out solid-liquid separation by adopting a solid-liquid separator in the washing tank to obtain a water washing liquid after impurity removal and softening and a desalted fly ash; The washing liquid is conveyed to a buffer tank and is conveyed to a slurry tank of a wet-process washing tower through an inlet pump, the washing liquid is taken as spray liquid in the wet-process washing tower, lifted to be sprayed downwards from the top of the wet-process washing tower through a circulating pump, and is in countercurrent contact with low-temperature flue gas in the tail part, and the water in the washing liquid is evaporated by utilizing the waste heat of the flue gas to realize concentration decrement; The concentrated water washing liquid is conveyed to a semi-dry desulfurization tower and is mixed with desulfurization slurry, the desulfurization slurry is atomized into liquid drops through a rotary atomizer, the liquid drops are contacted with high-temperature flue gas, moisture is rapidly evaporated, alkaline substances in the liquid drops and acid gases in the flue gas are subjected to absorption reaction, the evaporated solid product desulfurization ash falls into an ash bucket, the ash bucket and a dust remover are transported and collected, the flue gas further enters the dust remover to remove dust and separate fly ash, the fly ash enters an ash warehouse, and the flue gas after dust removal enters a wet scrubbing tower to realize zero discharge of wastewater.
7. The treatment method according to claim 6, wherein the chemical is one or a combination of calcium hydroxide, sodium carbonate and sodium sulfide, and the addition amount of the chemical is 5-10% of the mass of the fly ash.
8. The method according to claim 6, wherein the rotational speed of the atomizer is 10000-15000 rpm, the atomized liquid-gas ratio is 0.8-2.0L/Nm 3 , and the droplet size is 50-250 μm.
9. The treatment method according to claim 6, wherein the residence time of the flue gas in the wet scrubber is 10-20 seconds, the droplet size range of the atomized water washing liquid of the pressure nozzle is 500-2000 μm, and the total mass fraction of the concentrated alkaline liquid solids at the outlet is 40-60%.
10. The treatment method according to claim 6, wherein the concentrated water washing liquid has a solid mass fraction of 20% -45%, the concentrated water washing liquid is added as make-up water to the desulfurization slurry, and the total solid mass fraction in the desulfurization slurry after mixing is 15% -25%.

Description

Treatment system and method for waste incineration fly ash washing liquid and flue gas purification in cooperation Technical Field The invention belongs to the technical field of high-salt wastewater treatment, and particularly relates to a treatment system and a method for waste incineration fly ash water washing liquid and flue gas purification in cooperation. Background A large amount of waste incineration fly ash is generated in the waste incineration process, and the waste incineration fly ash contains high-concentration chlorine salt (the mass fraction is about 10-30%), alkaline earth metal and heavy metal, and is clearly classified as dangerous waste. The high chlorine content is a key factor for restricting the stabilization and recycling of the fly ash, and can lead to the reduction of the strength of a solidified product of the fly ash and promote the leaching of heavy metals, simultaneously aggravate the corrosion of high-temperature treatment equipment and increase the load of a flue gas purification system, limit the application of the fly ash to building materials, and the water washing can transfer the soluble substances in the fly ash to the water washing liquid, so that the chlorine element in the waste incineration fly ash can be effectively removed, and the stabilization and recycling treatment of the follow-up fly ash are facilitated. During the fly ash washing process, a large amount of high-salt wastewater is generated, namely, the fly ash washing liquid, and part of heavy metals are leached out along with the high-salt-content high-alkalinity fly ash washing liquid, and the fly ash washing liquid has the characteristics of high salt content, high alkalinity trace elements and the like, and the direct discharge of the fly ash washing liquid can cause serious harm to the ecological environment. The existing water washing liquid disposal technology mainly purifies and separates chlor-alkali in the water washing liquid through an evaporation crystallization process to obtain an industrial salt product. However, the evaporative crystallization method has complex equipment and high energy consumption, and meanwhile, calcium-magnesium ion ash in the water washing liquid causes scaling in the evaporative crystallizer, so that the comprehensive operation cost is high. In the existing flue gas purification of the mainstream waste incineration plant, pollutants in the flue gas are mainly removed through a combined process of SNCR, semi-dry desulfurization and cloth bag dust removal, wherein the semi-dry desulfurization is used for removing acid gases such as HCl, SO 2 and the like in the flue gas through spraying alkaline slurry such as Ca (OH) 2 and the like, and because the removal efficiency of the semi-dry desulfurization is lower than that of wet desulfurization, excessive lime milk is often required to be sprayed to ensure the flue gas purification effect, a large amount of alkaline substances such as Ca (OH) 2 and the like which are not completely reacted are enriched in the fly ash, SO that the whole alkalinity of the fly ash and the fly ash is improved, and the flue gas purification cost and the disposal difficulty of water washing liquid are further increased. Disclosure of Invention In order to solve at least one of the problems, the invention provides a treatment system and a method for waste incineration fly ash water washing liquid and flue gas purification in cooperation. The method is a high-efficiency and low-energy-consumption disposal method for the waste incineration ash flying washing liquid, and realizes the recycling zero emission of the washing liquid in cooperation with the in-plant flue gas purification device. In order to achieve the above purpose, the invention adopts the following technical means: The first aspect of the invention provides a treatment system for waste incineration fly ash water washing liquid concentration decrement cooperation flue gas purification, which comprises: the washing tank is connected with the ash bin, and is connected with process water through a process water inlet and a medicament through a medicament inlet; the buffer tank is positioned between the water washing tank and the wet method washing tower and is used for storing the water washing liquid obtained by separation in the water washing tank; The wet method washing tower, the water washing liquid in the buffer tank enters the slurry pool in the wet method washing tower through the water inlet pump, the top of the wet method washing tower is provided with a demister, the middle part of the wet method washing tower is provided with a spraying device consisting of pressure nozzles, the water washing liquid in the slurry pool is conveyed into the pressure nozzles through the circulating pump to be sprayed and concentrated, and the concentrated fly ash water washing liquid enters the semi-dry desulfurization tower through the outlet pump; The flue gas enters the semi-dry desulfurizatio