CN-122007117-A - System and method for separating salt by coupling percolate film concentrate with fly ash water washing

Abstract

The invention relates to a system and a method for separating salt by coupling percolate film concentrate with fly ash water washing, belonging to the technical field of collaborative treatment of percolate and household garbage incineration fly ash. The invention comprises a fly ash water-washing salt-separating system and a percolate film concentrated solution treatment system, wherein the percolate film concentrated solution is dried, granulated and screened, then is sent into a rotary kiln to burn and remove organic matters, high-temperature flue gas generated by the rotary kiln is mixed with air and is sent into a drying tower to be used as a drying heat source, then is dedusted by a deduster and is divided into two paths, one path enters a heat exchanger to exchange heat with the air, the heated air is used as combustion air of the rotary kiln, and the other path is led into a pulping tank and the fly ash water-washing system to regulate pH and solidify heavy metals. The invention realizes the treatment of waste by deeply coupling the treatment of the percolate film concentrated solution with the washing of the fly ash and the salt separation, and reduces the investment cost and the operation cost.

Inventors

• TAO YINGXIANG
• LI YU
• YU MINGRUI
• WU ZHONGYONG
• YU BENHONG
• PENG ZEJUN
• LIU MIN
• CHEN TAO
• CHEN NIAN

Assignees

• 重庆三峰卡万塔环境产业有限公司

Dates

Publication Date

20260512

Application Date

20260327

Claims (9)

1. 1. The system for coupling the percolate film concentrated solution with the fly ash water washing and salt separating comprises a fly ash water washing and salt separating system, wherein the fly ash water washing and salt separating system comprises a fly ash water washing system (10), a reaction tank (11), an ultrafiltration system (12), a nanofiltration system (13) and an MVR evaporation system (15) which are sequentially connected, and is characterized by further comprising a percolate film concentrated solution treatment system, wherein the percolate film concentrated solution treatment system comprises a drying tower (1), a dust remover (2), a granulating device (3), a screening machine (4) and a rotary kiln (5) which are sequentially connected, and the dust remover (2) is provided with a first flue gas outlet and a second flue gas outlet; the air side outlet of the heat exchanger (6) is connected to a combustion air supply port of the rotary kiln (5) through a pipeline, and the flue gas side outlet of the heat exchanger (6) is connected to a condensing system (7); the second flue gas outlet is divided into two paths, one path is connected with a fly ash washing system (10), the other path is connected with a pulping tank (8), a feed inlet of the pulping tank (8) receives incineration ash from a discharge port of the rotary kiln, and a water outlet of the pulping tank (8) is connected to a reaction tank (11).
2. 2. The system for separating salt by using the percolate film concentrate coupled with fly ash water according to claim 1, wherein a water outlet of the condensing system (7) is connected with the pulping tank (8) and the fly ash water washing system (10).
3. 3. The system for separating salt from fly ash water by coupling percolate film concentrate according to claim 1, wherein the sediment discharge ports of the reaction tank (11), the ultrafiltration system (12) and the nanofiltration system (13) are connected to the fly ash water washing system (10).
4. 4. The system of claim 1, wherein a filtrate outlet of the fly ash washing system (10) is connected to the reaction tank (11).
5. 5. The system for separating salt by coupling the percolate membrane concentrate with fly ash water according to claim 1, wherein the granulating device (3) is a rolling granulating device, and the fly ash water washing system (10) is a fly ash three-stage countercurrent water washing system.
6. 6. A method for separating salt by coupling a percolate film concentrate with fly ash water washing is characterized in that the system for separating salt by coupling the percolate film concentrate with the fly ash water washing based on any one of claims 1-5 comprises the following steps: s1, spraying the percolate film concentrated solution into a drying tower (1) after atomization, directly contacting with high-temperature flue gas obtained by mixing flue gas from a rotary kiln (5) with air, and drying to obtain dried ash; S2, enabling the flue gas carrying the dried ash to enter a dust remover (2) for gas-solid separation, and enabling the collected dried ash to enter a granulating device (3) for granulating, screening by a screening machine (4), and enabling qualified particles to enter a rotary kiln (5); S3, incinerating the granular dried ash in a rotary kiln (5) in a high-temperature environment provided by methane combustion to remove organic matters contained in the granular dried ash; S4, the burnt ash discharged from the rotary kiln (5) enters a pulping tank (8) for pulping, the flue gas at the outlet of the dust remover (2) is divided into two paths, wherein the first path of flue gas enters a heat exchanger (6) for exchanging heat with air, the heat-exchanged flue gas is discharged after passing through a condensing system (7), the heated air is used as combustion air of the rotary kiln (5), the second path of flue gas is introduced into the pulping tank (8) and a fly ash washing system (10) for adjusting pH and curing heavy metals, and the solution of the pulping tank (8) is sent into a reaction tank (11); S5, enabling the household garbage incineration fly ash to enter a fly ash washing system (10) for countercurrent washing, sending generated washing filtrate into a reaction tank (11), mixing the washing filtrate with a solution from a pulping tank (8), and adding a decalcification agent for decalcification reaction; S6, sequentially passing the effluent of the reaction tank (11) through an ultrafiltration system (12) and a nanofiltration system (13), removing suspended matters and divalent salt impurities, and enabling the solution to enter a water producing tank (14); S7, enabling the solution in the water producing pool (14) to enter an MVR evaporation system (15) for evaporation, crystallization and salt separation to obtain sodium chloride and potassium chloride products; Wherein, the sediment generated by the reaction tank (11), the ultrafiltration system (12) and the nanofiltration system (13) is returned to the fly ash washing system (10).
7. 7. The method for separating salt from the condensate liquid film concentrated solution by coupling fly ash water washing according to claim 6, wherein flue gas cooled by the heat exchanger (6) is deeply cooled by the condensing system (7) to generate condensed water, the condensed water generated by the condensing system (7) and the MVR evaporating system (19) is included as water supplementing sources of the fly ash water washing system (10) and the pulping tank (8), and industrial water, and redundant condensed water of the condensing system (7) is discharged to a percolate solution pool.
8. 8. The method for separating salt by coupling the percolate film concentrate with the fly ash water washing according to claim 6, wherein the fuel of the rotary kiln (5) is methane generated by anaerobic treatment of the landfill leachate, and the biogas is replaced by natural gas or liquefied petroleum gas when no biogas exists.
9. 9. The method for separating salt from fly ash by water through coupling of percolate film concentrate according to claim 6, wherein the temperature of flue gas at the outlet of the dust remover (2) is 100-110 ℃, the temperature of flue gas after heat exchange is 50-60 ℃, and the temperature of air after heating is 30-60 ℃.

Description

System and method for separating salt by coupling percolate film concentrate with fly ash water washing Technical Field The invention belongs to the technical field of leachate and household garbage incineration fly ash cooperative treatment, and relates to a system and a method for separating salt by coupling of leachate membrane concentrate and fly ash water washing. Background With the continuous increase of the domestic garbage treatment demands, the garbage incineration power generation has become a mainstream treatment mode, but the treatment problems of the associated wastes including garbage leachate membrane concentrate and domestic garbage incineration fly ash are increasingly prominent. The landfill leachate membrane concentrate is a concentrate which is obtained by passing through a Nanofiltration (NF) membrane or a Reverse Osmosis (RO) membrane after the landfill leachate stock is biodegraded by a Membrane Bioreactor (MBR), and the volume of the concentrate is usually 20% -30% of the stock, but the concentration of pollutants is extremely high. Unlike the stock solution of landfill leachate, most of the residual pollutants in the membrane concentrate are humus substances which are difficult to biodegrade, and meanwhile, the membrane concentrate has the characteristics of high salt content, complex metal ions and extremely low biodegradability, and is difficult to directly carry out biochemical treatment, and organic matters are removed by a recharging method, an advanced oxidation method, a drying incineration method and the like, wherein the drying incineration method can reduce the concentrated liquid volume to 2% -10% of the stock solution, but can generate a large amount of high-temperature flue gas, and the direct discharge not only causes heat energy waste, but also the obtained mixed salt mixture is generally classified as hazardous waste for landfill because of containing heavy metals, and has high disposal cost and environmental risk. Meanwhile, the fly ash from incineration of the household garbage is taken as an inevitable product in the incineration process, and the recycling utilization of the fly ash is strictly controlled. According to the technical specification of pollution control of household garbage incineration fly ash (trial) HJ1134-2020, the content of soluble chlorine should not exceed 2%, preferably not higher than 1%, the leaching concentration of heavy metal in the fly ash treatment product should not exceed the maximum allowable emission concentration limit value specified in GB 8978 according to the leaching solution prepared by HJ557, the total content of dioxin residues should not exceed 50ng-TEQ/kg (calculated by dry weight of fly ash) and the like, at present, three-stage countercurrent water washing is adopted to meet the requirements, and sodium chloride and potassium chloride in the fly ash are separated by an evaporation crystallization salt separation technology for recycling. However, the fly ash water washing system requires a large amount of water replenishment and generates a large amount of strong brine for further treatment, and at the same time, acid is added or acid gas (usually CO 2) is introduced to adjust the pH value so as to promote heavy metal precipitation and decalcification reaction, and the overall technical process is complex and the running cost is high. In view of the fact that a large amount of smoke and mixed salt mixtures are generated in the treatment process of the landfill leachate membrane concentrate by adopting a drying incineration method, the water washing treatment of the household garbage incineration fly ash requires acid gases such as CO 2, and the treatment method is also suitable for the treatment of the mixed salt mixtures after the drying incineration of the landfill leachate membrane concentrate. The method organically combines the two, on one hand, acidic flue gas (mainly CO 2) generated in the process of drying and incinerating the membrane concentrated solution is introduced to regulate the pH value of a fly ash washing system, promote heavy metal precipitation and decalcification reaction, and reduce the use of medicaments, and on the other hand, the fly ash washing system is used for separating salt from the dried and incinerated product of the membrane concentrated solution, so that the synergistic recovery of salt and the stabilization treatment of ash are finally realized. Therefore, an integrated system and an integrated method capable of realizing the collaborative treatment of percolate concentrate and fly ash, the energy cascade utilization and the efficient material recovery are developed, the material complementation and the energy synergy are realized, and an integrated process for treating waste by waste and recycling resources is formed, so that the integrated system and the integrated method become key directions of urgent breakthrough in the current environmental protection technical field, and hav