CN109574113B - Treatment device and method for landfill leachate - Google Patents
Treatment device and method for landfill leachate Download PDFInfo
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- CN109574113B CN109574113B CN201811592284.2A CN201811592284A CN109574113B CN 109574113 B CN109574113 B CN 109574113B CN 201811592284 A CN201811592284 A CN 201811592284A CN 109574113 B CN109574113 B CN 109574113B
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- 239000000149 chemical water pollutant Substances 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000001704 evaporation Methods 0.000 claims abstract description 158
- 230000008020 evaporation Effects 0.000 claims abstract description 147
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 63
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 35
- 238000009833 condensation Methods 0.000 claims abstract description 8
- 230000005494 condensation Effects 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims description 18
- 239000012141 concentrate Substances 0.000 claims description 11
- 239000002253 acid Substances 0.000 claims description 9
- 230000008676 import Effects 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims 1
- 230000007797 corrosion Effects 0.000 abstract description 7
- 238000005260 corrosion Methods 0.000 abstract description 7
- 230000002035 prolonged effect Effects 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 238000004134 energy conservation Methods 0.000 abstract description 2
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 238000007738 vacuum evaporation Methods 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 34
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 16
- 230000008569 process Effects 0.000 description 12
- 238000002485 combustion reaction Methods 0.000 description 11
- 238000012423 maintenance Methods 0.000 description 11
- 239000000047 product Substances 0.000 description 10
- 239000007859 condensation product Substances 0.000 description 8
- 239000002585 base Substances 0.000 description 7
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 4
- 235000011130 ammonium sulphate Nutrition 0.000 description 4
- 238000009835 boiling Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000012528 membrane Substances 0.000 description 4
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 3
- 230000005611 electricity Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000006260 foam Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000011550 stock solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 101100298225 Caenorhabditis elegans pot-2 gene Proteins 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000003211 malignant effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000010815 organic waste Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 230000001932 seasonal effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/043—Details
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/042—Prevention of deposits
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/048—Purification of waste water by evaporation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/06—Contaminated groundwater or leachate
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/06—Pressure conditions
- C02F2301/063—Underpressure, vacuum
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
Abstract
The invention provides a treatment device for landfill leachate, which comprises a pretreatment system, a first evaporation tank, a second evaporation tank, a first heat exchanger, a second heat exchanger, a neutralization tank and a condensation water tank, wherein an outlet of the pretreatment system is connected with an inlet of the first evaporation tank, a steam outlet of the first evaporation tank is connected with an inlet of the first heat exchanger, an outlet of the first heat exchanger is connected with an inlet of the neutralization tank, an outlet of the neutralization tank is connected with an inlet of the second evaporation tank, a steam outlet of the second evaporation tank is connected with an inlet of the second heat exchanger, an outlet of the second heat exchanger is connected with the condensation water tank, and the second heat exchanger is arranged near the first evaporation tank. Because the low-temperature vacuum evaporation is adopted, the scaling tendency of the evaporator is reduced, pretreatment is not needed, the corrosion tendency of equipment is reduced, the service life of the equipment is prolonged, and the low-cost energy source is fully utilized. The method for treating the landfill leachate is simple in flow and high in practicability, accords with the principles of environmental protection, energy conservation and high-efficiency utilization, and is beneficial to popularization and use.
Description
Technical Field
The invention belongs to solution treatment equipment, and particularly relates to a treatment device and method for landfill leachate.
Background
The landfill leachate is waste water generated in the landfill or temporary stacking process, the water quality of the landfill leachate has the characteristics of high COD (chemical oxygen demand ), high salinity, high ammonia nitrogen, high heavy metal and the like, and the landfill leachate can change along with landfill components, seasonal climate and service life of a landfill, so that the landfill leachate is relatively difficult to treat high-concentration organic waste water. At present, the country goes out of the table and related emission standards for garbage leachate treatment are also put out, related engineering design guidelines are also put out, according to engineering practice for many years, two process paths are mainly adopted at present, one process is a two-stage DTRO process, the other process is a biochemical+membrane bioreactor (MBR+NF+RO) process, and in certain areas, under the condition that the concentration of the leachate is particularly high, even the processes cannot be processed and operated, the evaporation concentration or the incineration method is directly adopted.
Because of the use of membrane technology in both of the first two processes, approximately 20-30% of the membrane concentrate needs further processing, and in general, recharging is most used in landfill sites. However, if the recharging of the concentrated solution of the percolate is not standard, or the concentrated solution of the recharging is possibly caused to flow back to the percolate regulating tank in rainy season, so that the COD and the salt concentration of the percolate are increased, the operating pressure of the membrane equipment is increased, the recovery rate is reduced, the washing is frequent, or the biochemical system cannot operate and the malignant cycle is caused. There is therefore a strong market need for further reduction or further concentration of existing percolate concentrates, or even for zero drainage of the concentrate.
At present, for the reduction treatment of the percolate film concentrate, multi-effect evaporation equipment, MVR process equipment and submerged combustion process equipment are used in the market, but certain defects exist in the multi-effect evaporation equipment, the MVR process equipment and the submerged combustion process equipment, so that the system cannot run continuously and stably in practice, the running cost is high, and secondary pollution is generated. For example, the MVR processes mentioned in the CN108314115a and CN202744415U et al patents. The MVR process is to utilize an electrically driven vapor compressor to evaporate in a manner that provides energy for evaporation, which is relatively energy efficient, but has several problems in the art as follows: 1) The evaporation temperature is high, and the scale formation of the heat exchanger is easy to cause, so that pretreatment is needed for removing hardness, and the chemical hardness removal cost is high; 2) The foam is easy to generate due to high evaporation temperature of percolate, and the foam easily enters the vapor compressor, so that the compressor is in fault, and the service life is shortened; 3) The evaporation temperature is high, the generated ammonia gas and non-condensable gas need to be further treated, and otherwise secondary pollution exists; 4) Because of high salt content and high evaporating temperature, the material requirement on equipment is high. For the submerged combustion process, a mode of directly combusting combustible gas (such as methane or natural gas) in an evaporator to form thermal energy for evaporation is adopted, and the submerged combustion process has the advantages that the concentration of the directly-transmitted heat which can be evaporated is higher, but the submerged combustion process is influenced by an energy supply mode, the submerged combustion process can only be implemented under the condition of the combustible gas, and the energy consumption of the natural gas can be extremely high under the condition of no stable methane supply. Therefore, it is one of the problems to be solved that a method and a device for evaporating and concentrating landfill leachate, which recycle heat energy and do not need to use MVR technology, are provided.
Disclosure of Invention
Aiming at the problems that the heat exchanger in the MVR technology is easy to scale, foam is easy to generate, the steam compressor is easy to damage, and the generated volatile ammonia gas and noncondensable gas need to be further treated, so that the requirement on equipment materials is high; the invention provides a treatment device for landfill leachate, which comprises a pretreatment system, a first evaporation tank, a second evaporation tank, a first heat exchanger, a second heat exchanger, a neutralization tank and a condensation water tank, wherein the pretreatment system comprises a pretreatment system outlet; the first evaporation tank is provided with a first evaporation tank inlet, a first evaporation tank steam outlet and a first evaporator concentrated solution outlet; the second evaporation tank is provided with a second evaporation tank inlet, a second evaporation tank steam outlet and a second evaporator concentrated solution outlet; the first heat exchanger is provided with a first heat exchanger inlet and a first heat exchanger outlet; the second heat exchanger is provided with a second heat exchanger inlet and a second heat exchanger outlet; the neutralization tank is provided with a neutralization tank inlet and a neutralization tank outlet; wherein the pretreatment systems export links to each other with first evaporation tank import, and first evaporation tank steam outlet links to each other with first heat exchanger import, and first heat exchanger export links to each other with neutralization tank import, and neutralization tank export links to each other with second evaporation tank import, and second evaporation tank steam outlet links to each other with second heat exchanger import, and second heat exchanger export links to each other with the condensate tank, and the second heat exchanger is set up in the vicinity of first evaporation tank.
Preferably, the first evaporator has a vacuum of 40-50mbar and the second evaporator has a vacuum of 110-120mbar. The boiling point of the solution in the first evaporating pot and the second evaporating pot can be reduced by setting different vacuum degrees, energy is saved, potential corrosion hazard and scaling trend are reduced, and equipment is not required to be subjected to hard removal pretreatment and later maintenance.
Preferably, an acid or base is added to the neutralization tank to adjust the pH of the resulting product. To obtain a useful product such as an ammonium sulfate solution, and this product can be further recycled by evaporation or directly discharged meeting discharge standards.
Preferably, the device further comprises a first storage tank and a second storage tank, wherein the first storage tank comprises a first storage tank inlet, the second storage tank comprises a second storage tank inlet, a first evaporation tank concentrated solution outlet is connected with the first storage tank inlet, and a second evaporation tank concentrated solution outlet is connected with the second storage tank inlet. The final concentrated solution in the first storage tank can be circularly evaporated and concentrated or further reasonably treated, and the product in the second storage tank can be further evaporated and recycled or directly discharged after meeting the discharge standard.
Preferably, the evaporator further comprises a heat source and a third heat exchanger, wherein the third heat exchanger is arranged in the second evaporation tank and is connected with the heat source, and the heat source comprises hot water or a heat pump. The heat source can supply heat through the methane combustion of the landfill site or the heat pump driven by pure electricity, and the low-grade steam can fully utilize the low-cost energy.
Preferably, the second heat exchanger is in heat exchange with the first evaporator tank to provide the first evaporator tank with the heat required for evaporation. Therefore, the first evaporation tank does not need to additionally provide a heat source, and the heat in the second heat exchanger is recycled, so that energy sources are saved, and equipment cost and energy source cost are reduced.
Preferably, the first heat exchanger and the second heat exchanger comprise tube-in-tube heat exchangers or plate heat exchangers, and the third heat exchanger comprises a coil heat exchanger. The tube type heat exchanger or the plate type heat exchanger has the advantages of simple and compact structure, convenient maintenance, high efficiency and energy saving of the coil heat exchanger and good heat exchange effect.
Preferably, the cooling tower is further included, the condensed water tank is provided with a condensed water tank inlet and a condensed water tank outlet, and the condensed water tank outlet is connected with the cooling tower. The condensed water tank supplies condensed water to the cooling tower, and the cooling tower further transmits the condensed water and exchanges heat with the first heat exchanger to condense steam in the first heat exchanger.
Preferably, the cooling tower is arranged in the vicinity of the first heat exchanger. The condensed water of the cooling tower exchanges heat with the first heat exchanger to condense the steam in the first heat exchanger, so as to achieve the effect of saving energy.
Preferably, the device further comprises a first circulating pump, a first vacuum pump and a second vacuum pump, wherein the first circulating pump is arranged between the second heat exchanger and the first evaporation tank and used for internally circulating liquid in the first evaporation tank and entering the second heat exchanger for heat exchange, the first vacuum pump is arranged on the neutralization tank and used for forming vacuum in the neutralization tank and the first evaporation tank, and the second vacuum pump is arranged on the condensation water tank and used for forming vacuum in the condensation water tank and the second evaporation tank. The first vacuum pump and the second vacuum pump form vacuum through condensation products, the steam of the evaporator is not directly extracted, and the moving parts of the equipment are fewer, so that the maintenance cost is reduced.
The invention also provides a treatment method for landfill leachate, which comprises the following steps:
s1: introducing percolate into a first evaporation tank with a first vacuum degree for evaporation, and introducing generated steam into a first heat exchanger for condensation to obtain first condensate water;
s2: adjusting the pH value of the first condensed water, and introducing the first condensed water into a second evaporation tank with a second vacuum degree so as to evaporate the first condensed water;
s3: and carrying out heat exchange on the steam generated in the second evaporation tank and the second heat exchanger to obtain second condensed water.
In a further embodiment, step S3 further comprises collecting the second condensate water and exchanging heat between the second condensate water and the first heat exchanger. The steam in the first heat exchanger is condensed to achieve the effect of saving energy.
In a further embodiment, step S3 further comprises providing a heat source for the second evaporation tank. The heat source comprises hot water or a heat pump, can be a methane-burning or pure-electric heat pump in a landfill, can supply heat through low-grade steam, and fully utilizes low-cost energy.
In a further embodiment, the first vacuum and the second vacuum are 40-50mbar and 110-120mbar, respectively. The boiling point of the solution in the first evaporating pot and the second evaporating pot can be reduced by setting different vacuum degrees, energy is saved, potential corrosion hazard and scaling trend are reduced, and equipment is not required to be subjected to hard removal pretreatment and later maintenance.
In a further embodiment, the evaporator further comprises a second heat exchanger in heat exchange with the first evaporator tank to provide heat required for evaporation to the first evaporator tank. Therefore, the first evaporation tank does not need to additionally provide a heat source, and the heat in the second heat exchanger is recycled, so that energy sources are saved, and equipment cost and energy source cost are reduced.
The invention discloses a treatment device for landfill leachate, which adopts two-stage high-vacuum low-pressure low-temperature evaporation, a heat source can be a heat pump driven by methane combustion or pure electricity in a landfill, and can also supply heat through low-grade steam so as to generate hot water at the temperature of about 80-90 ℃, and low-cost energy sources are fully utilized. And the heat source input is directly evaporating the condensation product in the second evaporation tank, and the condensation product is not easy to scale, so that maintenance problems are not required to be worried. Vapor evaporated in the second evaporation tank heats percolate in the first evaporation tank through a second heat exchanger arranged outside, and vapor in the first evaporation tank further exchanges heat through the first heat exchanger to obtain condensation products, and the condensation products enter the neutralization tank to recycle heat, so that unnecessary heat source cost is reduced. The first heat exchanger and the second heat exchanger belong to a tube array heat exchanger or a plate heat exchanger, and are convenient to maintain. The pH value of the steam generated by evaporation is regulated and concentrated after the steam is condensed, so that high-concentration useful products can be obtained for recycling, and the evaporated steam condensate can meet the discharge standard and be directly discharged. The evaporation temperature is low, so that the scaling tendency is reduced, pretreatment is not needed, the corrosion tendency of equipment is reduced, lower-grade materials can be adopted, the equipment investment is reduced, and the service life of the equipment is prolonged. The main moving parts of the device are a water pump and a vacuum pump, the vacuum pump forms vacuum through the condensed water tank, steam in the evaporation tank is not directly extracted, the moving parts of the equipment are fewer, and the maintenance cost is reduced.
Drawings
The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain the principles of the invention. Many of the intended advantages of other embodiments and embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.
FIG. 1 is a flow diagram of an apparatus for a landfill leachate treatment device according to an embodiment of the present invention;
fig. 2 is a flow chart of a method of treatment for landfill leachate according to an embodiment of the present invention.
Reference numerals illustrate: the pretreatment system 1, the first evaporation tank 2, the second evaporation tank 3, the first heat exchanger 4, the second heat exchanger 5, the neutralization tank 6, the condensate tank 7, the first storage tank 8, the second storage tank 9, the heat source 10, the third heat exchanger 11, the cooling tower 12, the first circulation pump 13, the first vacuum pump 14, the second vacuum pump 15, the acid pump or the base pump 16, the second circulation pump 17, the acid tank or the base tank 18.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention will be described in detail with reference to fig. 1, and the invention provides a treatment device for landfill leachate, which comprises a pretreatment system 1, a first evaporation tank 2, a second evaporation tank 3, a first heat exchanger 4, a second heat exchanger 5, a neutralization tank 6 and a condensate water tank 7. The pretreatment system 1 includes a pretreatment system 1 outlet. The first evaporation tank 2 is provided with a first evaporation tank inlet, a first evaporation tank steam outlet and a first evaporator concentrated solution outlet. The second evaporation tank 3 is provided with a second evaporation tank inlet, a second evaporation tank steam outlet and a second evaporator concentrated solution outlet. The first heat exchanger 4 is provided with a first heat exchanger inlet and a first heat exchanger outlet. The second heat exchanger 5 is provided with a second heat exchanger inlet and a second heat exchanger outlet. The neutralization tank 6 is provided with a neutralization tank inlet and a neutralization tank outlet. Wherein the outlet of the pretreatment system is connected with the inlet of a first evaporation tank, the steam outlet of the first evaporation tank is connected with the inlet of a first heat exchanger, the outlet of the first heat exchanger is connected with the inlet of a neutralization tank, the outlet of the neutralization tank is connected with the inlet of a second evaporation tank, the steam outlet of the second evaporation tank is connected with the inlet of a second heat exchanger, the outlet of the second heat exchanger is connected with a condensate tank 7,
the second heat exchanger 5 is disposed in the vicinity of the first evaporator tank 2.
In a preferred embodiment, the pretreatment system 1 and the first evaporation tank 2 may be landfill leachate stock solution or concentrated solution of landfill leachate after RO/NF treatment, and may be other solutions. When the solution in the pretreatment system 1 and the first evaporation tank 2 is concentrated solution obtained by RO/NF treatment of landfill leachate, the vacuum degree of the first evaporation tank 2 is 40-50mbar, the evaporation temperature is about 45-50 ℃, the generated steam is output through defoaming and defoaming at the top of the first evaporation tank 2, and then condensed into condensed water containing ammonia nitrogen through the first heat exchanger 4, wherein more than about 95% of ammonia nitrogen is brought into the steam. The RO/NF concentrate is concentrated by cyclic evaporation to a solids content of 30-40% or more and is periodically discharged through the equipment bottom valve of the first evaporator tank 2. The second evaporation tank 3 is an ammonium sulfate salt solution, the vacuum degree of the second evaporation tank 3 is 110-120mbar, the evaporation temperature is about 60-65 ℃, the sulfate solution with a certain concentration is circularly evaporated and discharged for storage, and the vapor formed by evaporation is introduced into the second heat exchanger 5 to exchange heat with RO/NF concentrated solution. The first evaporation tank 2 and the second evaporation tank 3 are provided with different vacuum degrees, so that the boiling point of the solution in the first evaporation tank 2 and the solution in the second evaporation tank 3 can be reduced, energy is saved, potential corrosion hazard and scaling trend are reduced, and equipment is not required to be subjected to hard removal pretreatment and later maintenance. When the solutions in the pretreatment system 1 and the first evaporation tank 2 are other solutions, the vacuum degree and the evaporation temperature of the first evaporation tank 2 and the second evaporation tank 3 may be selected to other suitable values.
An acid or base is added in the neutralization tank 6 to adjust the pH of the obtained product. In a preferred embodiment, the landfill leachate stock solution or the concentrated solution of the landfill leachate after RO/NF treatment in the first evaporation tank 2 is evaporated and condensed to obtain ammonia-containing condensate, a proper amount of sulfuric acid is added in the neutralization tank 6 to adjust the pH value to obtain an ammonium sulfate solution, the ammonium sulfate solution is further evaporated and concentrated in the second evaporation tank 3 to recycle the concentrated ammonium sulfate solution, the evaporated steam in the second evaporation tank 3 is ammonia-free condensate water, and the condensate water can be directly discharged or further subjected to heat exchange recycling after meeting the discharge standard.
Also included are a first storage tank 8, a second storage tank 9, a heat source 10, a third heat exchanger 11, a cooling tower 12, a first circulation pump 13, a first vacuum pump 14, a second vacuum pump 15, an acid pump or an alkali pump 16. The first storage tank 8 comprises a first storage tank inlet, the second storage tank 9 comprises a second storage tank inlet, the first evaporation tank concentrate outlet is connected with the first storage tank inlet, and the second evaporation tank concentrate outlet is connected with the second storage tank inlet. The final concentrated solution in the first storage tank 8 can be further recycled, evaporated and concentrated or reasonably treated, and the product in the second storage tank 9 can be further evaporated, recycled or directly discharged after meeting the discharge standard. In a preferred embodiment, the final concentrate in the first tank 8 is a re-concentrated RO/NF concentrate and the product in the second tank 9 is a concentrated ammonium sulphate solution.
The third heat exchanger 11 is provided in the second evaporator tank 3 and is connected to a heat source 10, the heat source 10 comprising hot water or a heat pump. In a preferred embodiment, the heat source 10 is at a temperature of about 80-90 ℃, and heat can be supplied by low grade steam by landfill biogas combustion or a purely electric heat pump. The second heat exchanger 5 exchanges heat with the first evaporation tank 2 to supply heat required for evaporation to the first evaporation tank 2. Therefore, the first evaporation tank 2 does not need to provide a heat source additionally, and the heat of the steam in the second heat exchanger 5 is recycled, so that energy sources are saved, and equipment cost and energy source cost are reduced.
The condensed water tank 7 is provided with a condensed water tank inlet and a condensed water tank outlet, and the condensed water tank outlet is connected with the cooling tower. The condensed water tank 7 supplies condensed water to the cooling tower 12, a second circulating pump 17 is arranged between the cooling tower 12 and the first heat exchanger 4, the second circulating pump 17 is used for internally circulating the condensed water in the cooling tower 12, and the condensed water is further transmitted and exchanges heat with the first heat exchanger 4 to condense the steam in the first heat exchanger 4. The cooling tower 12 is thus arranged in the vicinity of the first heat exchanger 4. In a preferred embodiment, the cooling tower 12 is disposed at the back of the first heat exchanger 4, so that the condensed water of the cooling tower 12 exchanges heat with the first heat exchanger 4 to condense the steam in the first heat exchanger 4, thereby achieving the effect of saving energy.
The first circulation pump 13 is arranged between the second heat exchanger 5 and the first evaporation tank 2, is used for internally circulating the liquid in the first evaporation tank 2 and entering the second heat exchanger 5 for heat exchange, so that the first evaporation tank 2 obtains heat required by evaporation, the first vacuum pump 14 is arranged on the neutralization tank 6, and is used for forming vacuum in the neutralization tank 6 and the first evaporation tank 2, and the second vacuum pump 15 is arranged on the condensed water tank 7, and is used for forming vacuum in the condensed water tank 7 and the second evaporation tank 3. The first vacuum pump 14 and the second vacuum pump 15 form vacuum through condensation products, the steam of the evaporator is not directly extracted, and the equipment has fewer moving parts, so that the maintenance cost is reduced. An acid or base pump 16 is installed above the neutralization tank 6 and is provided with an acid or base tank 18 to control the addition amount of acid or base.
In a preferred embodiment, the first heat exchanger 4 and the second heat exchanger 5 comprise tube array heat exchangers or plate heat exchangers, which are relatively simple, compact and easy to maintain. The third heat exchanger 11 comprises a coil heat exchanger, and the coil heat exchanger is efficient and energy-saving and has good heat exchange effect.
The invention also discloses a treatment method for landfill leachate, which is shown in fig. 2 and comprises the following steps:
s1: introducing percolate into a first evaporation tank 2 with a first vacuum degree for evaporation, and introducing generated steam into a first heat exchanger 4 for condensation to obtain first condensate water;
s2: adjusting the pH value of the first condensed water, and introducing the first condensed water into a second evaporation tank 3 with a second vacuum degree to evaporate the first condensed water;
s3: the steam generated in the second evaporation tank 3 is heat-exchanged with the second heat exchanger 5 to obtain second condensate water.
In a preferred embodiment, step S3 further comprises collecting the second condensate water and heat exchanging the second condensate water with the first heat exchanger 4. The steam in the first heat exchanger 4 is condensed to achieve the effect of saving energy.
In a preferred embodiment, step S3 further comprises providing a heat source 10 for the second evaporation tank 3. The heat source 10 comprises hot water or a heat pump, can be a heat pump driven by methane combustion or pure electricity in a landfill, can supply heat through low-grade steam, and fully utilizes low-cost energy.
In a preferred embodiment, when the solution in the first evaporation tank 2 is a concentrate of landfill leachate after RO/NF treatment, the first vacuum level and the second vacuum level are 40-50mbar and 110-120mbar, respectively, provided by the first vacuum pump 14 and the second vacuum pump 15, respectively. The boiling points of the solutions in the first evaporating pot 2 and the second evaporating pot 3 can be reduced by setting different vacuum degrees, so that energy is saved, potential corrosion hazard and scaling trend are reduced, and equipment does not need hard removal pretreatment and later maintenance. When the solution in the first evaporation tank 2 is other solution, the vacuum degree and evaporation temperature of the first evaporation tank 2 and the second evaporation tank 3 may be selected to other suitable values.
The invention discloses a treatment device for landfill leachate, which adopts two-stage high-vacuum low-pressure low-temperature evaporation, a heat source 10 can supply heat through methane combustion in a landfill site or a pure electric heat pump, and also can supply heat through low-grade steam to generate hot water at the temperature of about 80-90 ℃, so that low-cost energy sources are fully utilized. And the heat source 10 is used for directly evaporating the condensed product in the second evaporation tank 3, and the condensed product is not easy to scale, so that maintenance problems are not required. The vapor evaporated in the second evaporation tank 3 heats the percolate in the first evaporation tank 2 through the second heat exchanger 5 arranged outside, the vapor in the first evaporation tank 2 further exchanges heat through the first heat exchanger 4 to obtain condensation products, and the condensation products enter the neutralization tank 6 to recycle heat, so that unnecessary heat source cost is reduced. The first heat exchanger 4 and the second heat exchanger 5 belong to a tube-in-tube heat exchanger or a plate heat exchanger, and are convenient to maintain. The evaporation temperature is low, so that the scaling tendency is reduced, pretreatment is not needed, the corrosion tendency of equipment is reduced, and the service life of the equipment is prolonged. The main moving parts of the device are a circulating pump and a vacuum pump, the steam in the evaporating pot is not directly pumped, the moving parts of the equipment are fewer, and the maintenance cost is reduced. Meanwhile, a treatment method for landfill leachate is provided, and the method is simple in flow and strong in practicability, accords with the principles of environmental protection, energy conservation and high-efficiency utilization, and is beneficial to popularization and use.
While the principles of the invention have been described in detail in connection with the preferred embodiments thereof, it should be understood by those skilled in the art that the foregoing embodiments are merely illustrative of the implementations of the invention and are not intended to limit the scope of the invention. The details of the embodiments are not to be taken as limiting the scope of the invention, and any obvious modifications based on equivalent changes, simple substitutions, etc. of the technical solution of the invention fall within the scope of the invention without departing from the spirit and scope of the invention.
Claims (11)
1. A treatment device for landfill leachate comprises a pretreatment system, a first evaporation tank, a second evaporation tank, a first heat exchanger, a second heat exchanger, a first storage tank, a second storage tank, a neutralization tank, a condensate water tank, a first circulating pump, a first vacuum pump and a second vacuum pump, and is characterized in that,
the pretreatment system comprises a pretreatment system outlet;
the first evaporation tank is provided with a first evaporation tank inlet, a first evaporation tank steam outlet and a first evaporator concentrated solution outlet;
the second evaporation tank is provided with a second evaporation tank inlet, a second evaporation tank steam outlet and a second evaporator concentrated solution outlet;
the first heat exchanger is provided with a first heat exchanger inlet and a first heat exchanger outlet;
the second heat exchanger is provided with a second heat exchanger inlet and a second heat exchanger outlet, the second heat exchanger exchanges heat with the first evaporation tank to provide heat required by evaporation for the first evaporation tank, and the first heat exchanger and the second heat exchanger comprise tube-in-tube heat exchangers or plate heat exchangers;
the first storage tank comprises a first storage tank inlet, and the second storage tank comprises a second storage tank inlet;
the neutralization tank is provided with a neutralization tank inlet and a neutralization tank outlet; wherein the method comprises the steps of
The pretreatment system outlet is connected with a first evaporation tank inlet, a first evaporation tank steam outlet is connected with a first heat exchanger inlet, a first heat exchanger outlet is connected with a neutralization tank inlet, the neutralization tank outlet is connected with a second evaporation tank inlet, a second evaporation tank steam outlet is connected with a second heat exchanger inlet, a second heat exchanger outlet is connected with a condensate tank, a second heat exchanger is arranged near the first evaporation tank, a first evaporation tank concentrate outlet is connected with a first storage tank inlet, the second evaporation tank concentrated solution outlet with the second storage tank import links to each other, first circulating pump sets up second heat exchanger with between the first evaporation tank for the liquid in the first evaporation tank of inner loop and get into the second heat exchanger heat transfer, first vacuum pump sets up on the neutralization jar, be used for making the neutralization jar with form the vacuum in the first evaporation tank, the second vacuum pump sets up on the condensate water jar, be used for making the condensate water jar with form the vacuum in the second evaporation tank.
2. The apparatus according to claim 1, wherein the first evaporation tank has a vacuum of 40-50mbar and the second evaporation tank has a vacuum of 110-120mbar.
3. The treatment device for landfill leachate according to claim 1, wherein an acid or a base is added in the neutralization tank to adjust the pH value of the obtained product.
4. The apparatus for treating landfill leachate according to claim 1, further comprising a heat source and a third heat exchanger, the third heat exchanger being provided in the second evaporation tank and connected to the heat source, the heat source comprising hot water or a heat pump.
5. The apparatus for treating landfill leachate according to claim 4, wherein the third heat exchanger comprises a coil heat exchanger.
6. The apparatus according to claim 1, further comprising a cooling tower, wherein the condensate tank is provided with a condensate tank inlet and a condensate tank outlet, the condensate tank outlet being connected to the cooling tower.
7. The apparatus for treating landfill leachate according to claim 6, wherein the cooling tower is disposed in the vicinity of the first heat exchanger.
8. A method for treating landfill leachate, characterized in that the method uses the treatment device according to any one of claims 1 to 7 to treat landfill leachate, comprising the steps of:
s1: introducing percolate into a first evaporation tank with a first vacuum degree for evaporation, and introducing generated steam into a first heat exchanger for condensation to obtain first condensate water;
s2: adjusting the pH value of the first condensed water, and introducing the first condensed water into a second evaporation tank with a second vacuum degree so as to evaporate the first condensed water;
s3: and carrying out heat exchange on the steam generated in the second evaporation tank and the second heat exchanger to obtain second condensed water.
9. The method for treating landfill leachate according to claim 8, wherein step S3 further comprises collecting the second condensed water and exchanging heat of the second condensed water with the first heat exchanger.
10. The method of claim 8, wherein step S3 further comprises providing a heat source for heating the second evaporation tank.
11. The method of claim 8, further comprising exchanging heat with a first evaporator tank, wherein the heat required for evaporation is provided to the first evaporator tank.
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| CN102838244A (en) * | 2012-08-16 | 2012-12-26 | 广州新普利节能环保科技有限公司 | Landfill leachate treatment process and device |
| KR101421386B1 (en) * | 2013-12-26 | 2014-07-18 | 현대건설주식회사 | Seawater Desalination System |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN209618920U (en) * | 2018-12-25 | 2019-11-12 | 厦门嘉戎技术股份有限公司 | A kind of processing unit for landfill leachate |
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| CN102838244A (en) * | 2012-08-16 | 2012-12-26 | 广州新普利节能环保科技有限公司 | Landfill leachate treatment process and device |
| KR101421386B1 (en) * | 2013-12-26 | 2014-07-18 | 현대건설주식회사 | Seawater Desalination System |
| CN104368166A (en) * | 2014-10-28 | 2015-02-25 | 南通京通石墨设备有限公司 | Two-effect titanium liquid concentration device and concentration process |
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