CN210885723U

CN210885723U - Nearly zero release processing system of incineration plant's leachate

Info

Publication number: CN210885723U
Application number: CN201921925800.9U
Authority: CN
Inventors: 董健; 张爱军; 吴靖宇; 戴小东
Original assignee: Beijing Capital Environment Technology Co Ltd
Current assignee: Beijing Capital Environment Technology Co Ltd
Priority date: 2019-11-08
Filing date: 2019-11-08
Publication date: 2020-06-30
Anticipated expiration: 2029-11-08

Abstract

The utility model relates to a burn nearly zero release processing system of factory's filtration liquid, include the preprocessing unit, the anaerobism unit that communicate in proper order through the pipeline, nitrify the denitrification reactor, ultrafiltration unit, soften ultrafiltration unit, reverse osmosis unit, heat exchanger, humidification dehumidification evaporator and centrifugal dehydrator, the utility model discloses show with the help of softening ultrafiltration unit and reduced filtration liquid hardness, be favorable to reverse osmosis unit's steady operation, improve reverse osmosis unit's water yield, simultaneously, humidification dehumidification evaporation is ordinary pressure low temperature evaporation, effectively improves the problem that the equipment scale deposit leads to the unable steady operation of equipment, and the operation is stable, and investment and running cost are lower relatively.

Description

Nearly zero release processing system of incineration plant's leachate

Technical Field

The utility model belongs to the technical field of filtration liquid treatment, specifically speaking relates to a nearly zero release processing system of incineration plant filtration liquid.

Background

The leachate of a waste incineration plant is generally subjected to pretreatment, anaerobism, MBR (nitrification-denitrification, ultrafiltration), NF and RO, and the amount of the generated concentrated solution is generally 30-40%. In order to reduce the amount of concentrate produced, the back end typically adds a DTRO unit to re-concentrate the concentrate to reduce the amount of final concentrate to a level of 20% or less, with the final remaining concentrate typically being used in lime pulping or back-spray incinerators. However, the concentrated solution has high COD concentration, high alkalinity, high hardness and high salinity, which greatly affects the flue gas deacidification treatment equipment after pulping, and when the incineration scale is large and the incineration operation management is not fine, 20% of the concentrated solution is difficult to be completely consumed by pulping.

In order to solve the treatment problem of the concentrated solution, evaporation equipment is added in some incineration plants, so that near zero emission of leachate is realized. However, the evaporation equipment adopted in the industry at present has respective defects. If the MVR process which is the most widely used is used, the operation stability is poor, even if a hardness removing facility is added at the front end, the operation is not stable enough, and the cleaning frequency is high; the operation stability of the submerged combustion process is superior to that of MVR, but the investment and operation cost is high, the investment per ton is 15-18 ten thousand yuan, and only natural gas in the operation cost needs 60-70 square/ton concentrated solution, so that a treatment device with stable operation and relatively low investment and operation cost needs to be developed.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems, a near zero emission treatment system for leachate from an incineration plant is proposed.

In order to achieve the above object, the utility model provides a following technical scheme:

a near-zero emission treatment system for percolate in an incineration plant comprises a pretreatment unit, an anaerobic unit, a nitrification and denitrification reactor, an ultrafiltration unit, a softening ultrafiltration unit, a reverse osmosis unit, a heat exchanger, a humidifying and dehumidifying evaporator and a centrifugal dehydrator which are sequentially communicated through pipelines;

the device comprises a humidifying and dehumidifying evaporator, a reverse osmosis unit, a centrifugal dehydrator, a nitrification and denitrification reactor, a pipeline, a centrifugal dehydrator, a pipeline, a nitrification and denitrification reactor and a condensate evaporating system, wherein the condensate evaporating system generated by the humidifying and dehumidifying evaporator is connected with the reverse osmosis unit through the pipeline, the clear dehydrated liquid generated by the centrifugal dehydrator is communicated with the humidifying and dehumidifying evaporator through the pipeline, and the reflux generated by the ultrafiltration unit is communicated with the nitrification.

Furthermore, the softening ultrafiltration unit adopts a two-stage reaction precipitation structure and comprises a first-stage reaction tank, a first-stage precipitation tank, a second-stage reaction tank and a second-stage precipitation tank which are sequentially communicated through pipelines.

Further, the pH values of the first-stage reaction tank and the second-stage reaction tank are controlled to be 10-11, and the effective hydraulic retention time is 0.5 h.

Furthermore, the effective hydraulic retention time of the first-stage sedimentation tank and the second-stage sedimentation tank is 0.5-1h, and the bottoms of the first-stage sedimentation tank and the second-stage sedimentation tank are both conical.

Furthermore, the softening ultrafiltration unit also comprises a tubular ultrafiltration unit, the design flux of the tubular ultrafiltration unit is 200-300LMH, and the flow rate of the membrane passing is 3-4 m/s.

Furthermore, the designed recovery rate of the reverse osmosis unit is more than or equal to 75%, and the designed flux is 12-15 LMH.

Further, humidification dehumidification evaporimeter includes former cask, heat exchange assemblies, humidification tower, dense water bucket and the dehumidification tower that communicate in proper order through the pipeline, the evaporation concentrate that humidification tower produced passes through in the pipeline flows into the dense water bucket, the evaporation condensate that the dehumidification tower produced passes through the pipeline and flows into the product cask, and the product cask passes through pipeline and reverse osmosis unit intercommunication, former cask and reverse osmosis unit's output intercommunication.

Furthermore, the heat exchange assembly adopts a three-level heat exchange structure and comprises a first-level heat exchanger, a second-level heat exchanger and a third-level heat exchanger which are sequentially communicated through pipelines.

Further, the humidifying tower and the dehumidifying tower are filled with fillers, and the fillers are made of polypropylene.

The utility model has the advantages that:

the softening ultrafiltration unit obviously reduces the hardness of the percolate, is beneficial to the stable operation of the reverse osmosis unit, improves the water yield of the reverse osmosis unit, effectively solves the problem that the equipment cannot stably operate due to scaling of the equipment because the humidifying dehumidification evaporation is normal-pressure low-temperature evaporation, and has stable operation and relatively low investment and operation cost.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention;

fig. 2 is a schematic view of the structure of a humidification dehumidification evaporator.

In the drawings: 1-pretreatment unit, 2-anaerobic unit, 3-nitrification and denitrification reactor, 4-ultrafiltration unit, 5-softening ultrafiltration unit, 6-reverse osmosis unit, 7-heat exchanger, 8-humidifying dehumidification evaporator, 9-centrifugal dehydrator, 10-raw water bucket, 11-first-level heat exchanger, 12-second-level heat exchanger, 13-third-level heat exchanger, 14-humidifying tower, 15-dehumidifying tower, 16-concentrated water bucket, 17-water producing bucket, 18-spray head and 19-fan.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following description, together with the drawings of the present invention, clearly and completely describes the technical solution of the present invention, and based on the embodiments in the present application, other similar embodiments obtained by those skilled in the art without creative efforts shall all belong to the protection scope of the present application. In addition, directional terms such as "upper", "lower", "left", "right", etc. in the following embodiments are directions with reference to the drawings only, and thus, the directional terms are used for illustration and not for limitation of the present invention.

The first embodiment is as follows:

as shown in fig. 1-2, a near-zero emission treatment system for leachate from incineration plants comprises a pretreatment unit 1, an anaerobic unit 2, a nitrification-denitrification reactor 3, an ultrafiltration unit 4, a softening ultrafiltration unit 5, a reverse osmosis unit 6, a heat exchanger 7, a humidifying and dehumidifying evaporator 8 and a centrifugal dehydrator 9 which are sequentially communicated through pipelines. Wherein, the evaporation condensate that humidification dehumidification evaporimeter 8 produced passes through the pipeline and is connected with reverse osmosis unit 6, the dehydration clear liquid that centrifugal dehydrator 9 produced passes through the pipeline and communicates with humidification dehumidification evaporimeter 8, the backwash liquid that ultrafiltration unit 4 produced passes through the pipeline and nitrifies the denitrification the dehydration clear liquid that centrifugal dehydrator 9 produced passes through the pipeline and communicates reactor 3 with humidification dehumidification evaporimeter 8 intercommunication reactor.

Specifically, the softening ultrafiltration unit 5 adopts a two-stage reaction precipitation structure, and comprises a first-stage reaction tank, a first-stage precipitation tank, a second-stage reaction tank and a second-stage precipitation tank which are sequentially communicated through pipelines. The pH values of the first-stage reaction tank and the second-stage reaction tank are controlled to be 10-11, and the effective hydraulic retention time is 0.5 h. The effective hydraulic retention time of the first-stage sedimentation tank and the second-stage sedimentation tank is 0.5-1h, and the bottoms of the first-stage sedimentation tank and the second-stage sedimentation tank are both conical. The softening ultrafiltration unit 5 also comprises a tubular ultrafiltration unit, the design flux of the tubular ultrafiltration unit is 200-300LMH, and the flow rate of the membrane is 3-4 m/s. The designed recovery rate of the reverse osmosis unit 6 is more than or equal to 75%, and the designed flux is 12-15 LMH.

The humidifying and dehumidifying evaporator 8 adopts normal-pressure low-temperature evaporation, the evaporation temperature is 70-90 ℃, the water making ratio (GOR) is more than or equal to 5%, and the solid content in the concentrated residual liquid is more than or equal to 25%. Specifically, the humidifying and dehumidifying evaporator 8 comprises a raw water barrel 10, a heat exchange assembly, a humidifying tower 14, a concentrated water barrel 16 and a dehumidifying tower 15 which are sequentially communicated through pipelines. Spray heads 18 are arranged at the tops of the humidifying tower 14 and the dehumidifying tower 15, fillers are filled in the humidifying tower and the dehumidifying tower, the fillers are made of polypropylene, and meanwhile, a fan 19 is communicated between the humidifying tower 14 and the dehumidifying tower 15 to achieve gas circulation. The evaporation condensate generated by the humidifying tower 14 flows into a concentrated water barrel 16 through a pipeline, the evaporation condensate generated by the dehumidifying tower 15 flows into a water producing barrel 17 through a pipeline, the water producing barrel 17 is communicated with the reverse osmosis unit 6 through a pipeline, and the raw water barrel 10 is communicated with the output end of the reverse osmosis unit 6. Meanwhile, the water production barrel 17 is communicated with the centrifugal dehydrator 9 through a pipeline, and the dehydrated clear liquid generated by the centrifugal dehydrator 9 flows back to the dehumidifying tower 15 through the pipeline. In this embodiment, the heat exchange assembly adopts a three-stage heat exchange structure to realize stage-by-stage heat exchange, and includes a first-stage heat exchanger 11, a second-stage heat exchanger 12 and a third-stage heat exchanger 13 which are sequentially communicated through a pipeline.

During operation, leachate firstly passes through the pretreatment unit 1, and large-particle-size substances such as Suspended Solids (SS) and the like are removed in a physical filtration mode, equipment such as a rear-end water pump and the like are protected, then the leachate is pumped to the anaerobic unit 2, and macromolecular organic matters are degraded into large-particle-size substances in the anaerobic unit 2Small molecular organic substance, CH₄Water and carbon dioxide, the water produced by the anaerobic unit 2 automatically flows into a nitrification-denitrification reactor 3 to denitrify through the action of nitrifying bacteria and denitrifying bacteria, and further degrade organic matters, the produced water is conveyed to an ultrafiltration unit 4 through a pump to realize sludge-water separation, the produced concentrated solution flows back to the front nitrification-denitrification reactor 3, the produced clear solution is conveyed to a softening ultrafiltration unit 5 through the pump, the softening ultrafiltration unit 5 removes the hardness in the percolate through the modes of adding medicaments firstly and then separating membranes, the hardness of the percolate is reduced to be below 30mg/L, the produced water is conveyed to a reverse osmosis unit 6 through the pump, the produced water of the reverse osmosis unit 6 reaches the supplement water standard of an open type circulating cooling water system in the urban sewage recycling industrial water quality (GB/T19923-2005), enters a burning plant and is recycled to a cooling tower of the burning plant, the concentrated solution of the reverse osmosis unit 6 utilizes steam of the burning plant, the water is heated to 80 ℃ by the heat exchanger 7 and then enters the humidifying and dehumidifying evaporator 8, the evaporation concentrated liquid generated by the humidifying tower 14 flows into the concentrated water barrel 16 through a pipeline for other treatment, the evaporation condensed liquid generated by the dehumidifying tower 15 flows into the produced water barrel 17 through a pipeline, the produced water barrel 17 is communicated with the reverse osmosis unit 6 through a pipeline for retreatment, and simultaneously, the produced water of the softening and ultrafiltration unit 5 can be diluted, thereby being beneficial to the operation of the reverse osmosis unit 6. When the solid content of the hyperconcentration liquid of the humidifying and dehumidifying evaporator 8 reaches more than 25%, discharging, pumping to a centrifugal dehydrator 9 for dehydration, returning the generated clear liquid to a dehumidifying tower 15 for reprocessing, and bagging the generated salty mud to an incinerator for incineration.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the scope of the invention, i.e. the present invention is intended to cover all equivalent variations and modifications within the scope of the present invention.

Claims

1. A near-zero emission treatment system for percolate in an incineration plant is characterized by comprising a pretreatment unit, an anaerobic unit, a nitrification-denitrification reactor, an ultrafiltration unit, a softening ultrafiltration unit, a reverse osmosis unit, a heat exchanger, a humidifying and dehumidifying evaporator and a centrifugal dehydrator which are sequentially communicated through a pipeline;

2. The near-zero emission treatment system of the leachate from the incineration plant of claim 1, wherein the softening ultrafiltration unit adopts a two-stage reaction precipitation structure, which comprises a primary reaction tank, a primary precipitation tank, a secondary reaction tank and a secondary precipitation tank, which are sequentially communicated through a pipeline.

3. The near-zero emission treatment system for leachate of incineration plant of claim 2, wherein the pH of the primary reaction tank and the secondary reaction tank is controlled to be 10-11, and the effective hydraulic retention time is 0.5 h.

4. The near-zero emission treatment system for leachate of incineration plant of claim 3, wherein the effective hydraulic retention time of the primary settling tank and the secondary settling tank is 0.5-1h, and the bottoms of the primary settling tank and the secondary settling tank are both tapered.

5. The system as claimed in claim 4, wherein the softening ultrafiltration unit further comprises a tubular ultrafiltration unit, the design flux of the tubular ultrafiltration unit is 200 and 300LMH, and the flow rate of the membrane is 3-4 m/s.

6. The near-zero emission treatment system for leachate of an incineration plant of claim 1, wherein the designed recovery rate of the reverse osmosis unit is not less than 75%, and the designed flux is 12-15 LMH.

7. The near-zero emission treatment system for the percolate of the incineration plant as claimed in any one of claims 2 to 6, wherein the humidification and dehumidification evaporator comprises a raw water barrel, a heat exchange assembly, a humidification tower, a concentrated water barrel and a dehumidification tower which are sequentially communicated through a pipeline, the evaporation concentrate generated by the humidification tower flows into the concentrated water barrel through the pipeline, the evaporation condensate generated by the dehumidification tower flows into the water production barrel through the pipeline, the water production barrel is communicated with the reverse osmosis unit through the pipeline, and the raw water barrel is communicated with the output end of the reverse osmosis unit.

8. The near-zero emission treatment system for leachate of an incineration plant of claim 7, wherein the heat exchange assembly adopts a three-stage heat exchange structure, which comprises a primary heat exchanger, a secondary heat exchanger and a tertiary heat exchanger, which are sequentially communicated through a pipeline.

9. The near-zero emission treatment system of leachate from an incineration plant of claim 8, wherein the humidifying tower and the dehumidifying tower are filled with fillers, and the fillers are made of polypropylene.