CN115947400A - Two-stage MVR evaporative crystallization process for landfill leachate - Google Patents
Two-stage MVR evaporative crystallization process for landfill leachate Download PDFInfo
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Abstract
The invention discloses a two-stage MVR evaporation crystallization process for landfill leachate, which comprises the following steps: s100, preheating and warming; s200, heating for the first stage; s300, first-stage gas washing compression; s400, circularly evaporating and concentrating; s500, heating in a secondary heating mode; s600, secondary scrubbing compression; s700, circulating evaporation and crystallization; and S800, carrying out solid-liquid separation treatment. This landfill leachate doublestage MVR evaporation crystallization process utilizes the condensate water and the noncondensable gas that form behind the live steam heat transfer to preheat landfill leachate in proper order, and the heat of make full use of live steam, noncondensable gas and condensate water has shortened landfill leachate's intensification time, has reduced the quantity of live steam when promoting efficiency, has reduced energy consumption and treatment cost.
Description
Technical Field
The invention relates to the technical field of evaporative crystallization of landfill leachate, in particular to a two-stage MVR evaporative crystallization process of landfill leachate.
Background
With the rapid development of industry, the variety and quantity of wastewater are rapidly increased, and the pollution to water bodies is also becoming wide and serious day by day, threatening the health and safety of human beings. The landfill leachate is high-concentration organic wastewater with complex components generated in industrial production activities and has the following characteristics: 1. the water quality is complex and the hazard is large; 2. the COD and BOD concentration is high; 3. the ammonia nitrogen content is high; 4. the water quality changes greatly; 5. high metal content, etc. The garbage leachate has high COD and TDS content and cannot be biochemically treated. How to reach the standard or reduce the discharge of the landfill leachate and realize the recycling of water resources as much as possible becomes a big problem which troubles industrial enterprises.
In the prior art, for example, chinese patent application publication No. CN114772671A discloses a two-stage MVR single-effect forced circulation evaporation treatment method for salt-containing wastewater, which adopts an MVR mechanical recompression evaporation crystallization system, and introduces saturated steam into an evaporation crystallizer at one time, and compresses secondary steam after the feed liquid is boiled by using an MVR technology for recycling, so that the saturated steam is not used any more, and energy consumption can be greatly saved.
Before the waste liquid is evaporated and concentrated, the waste liquid is firstly introduced into a two-stage preheater, a heat medium source of the two-stage preheater mainly derives from condensed water formed after raw steam and secondary steam heat the waste liquid, although the temperature of the condensed water is higher than that of the waste liquid before evaporation, the heat exchange effect of the condensed water formed by adopting steam condensation on the waste liquid is limited, the waste liquid is slowly heated, the heating and concentrating time is prolonged, the waste water treatment efficiency is reduced, the amount of the introduced raw steam is increased, and the energy consumption and the treatment cost of using the method are increased; in addition, in the process of evaporating and crystallizing the waste liquid, the waste liquid is concentrated to separate out crystals, and meanwhile scales are formed in the processing device, so that the heat exchange efficiency with steam is influenced, the use amount of the steam is increased, the heat exchange time is prolonged, and similarly, the heat exchange between the waste liquid and the steam is also influenced by bubbles contained in the waste liquid; moreover, in the process of evaporation and concentration of the waste liquid, liquid drops are mixed in secondary steam generated by boiling of the waste liquid, and when the secondary steam mixed with the liquid drops is introduced into a compressor for compression treatment by the method, the power consumption of the operation of the compressor is increased due to the existence of the liquid drops, and finally, the cost for treating the waste liquid is increased.
Therefore, there is a need for improvement of the evaporative crystallization process of landfill leachate in the prior art.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a two-stage MVR evaporative crystallization process for landfill leachate, which can improve the treatment efficiency and reduce the consumption of raw steam so as to reduce the energy consumption and the operation cost.
In order to realize the technical effect, the technical scheme of the invention is a two-stage MVR evaporative crystallization process of landfill leachate, which comprises the following steps of:
s100, preheating and temperature rising treatment: the landfill leachate sequentially passes through a first preheater, a second preheater and a third preheater, raw steam is introduced into the third preheater for heat exchange, non-condensable gas formed after heat exchange of the raw steam is introduced into the second preheater, and condensed water is introduced into a primary condensed water tank and then introduced into a primary preheater;
s200, primary heating and temperature rising: pushing the landfill leachate to circularly flow between the primary heater and the primary separator, introducing raw steam into the primary heater for heat exchange, introducing non-condensable gas and condensed water formed by heat exchange into the second preheater and the primary condensed water tank respectively, and stopping introducing the raw steam after the landfill leachate generates mixed gas consisting of secondary steam and liquid drops in the primary separator;
s300, first-stage gas washing compression: extracting condensed water in a primary condensed water tank to wash the mixed gas obtained in the step S200 to separate secondary steam and liquid drops, compressing the secondary steam to form heating steam, and introducing the heating steam into a primary separator after the liquid drops are accumulated;
s400, circulating evaporation and concentration: introducing the heating steam obtained in the step S300 into a third preheater and a first heater for heat exchange to concentrate the landfill leachate to a set value, and introducing non-condensable gas and condensed water formed by secondary steam heat exchange into a second preheater and a primary condensed water tank respectively;
s500, secondary heating and temperature rising: pushing the concentrated landfill leachate to circularly flow among the secondary separator, the first secondary separator and the second secondary separator, introducing raw steam into the first secondary separator and the second secondary separator for heat exchange, discharging non-condensable gas formed by the heat exchange out of a system, introducing condensed water into a secondary condensed water tank and then introducing the condensed water into a primary preheater, and stopping introducing the raw steam after the landfill leachate boils in the secondary separator to generate mixed gas consisting of secondary steam and liquid drops;
s600, secondary scrubbing compression: extracting condensed water in a secondary condensed water tank to wash the mixed gas obtained in the step S500 to separate secondary steam and liquid drops, compressing the secondary steam to form heating steam, and introducing the heating steam into a secondary separator after the liquid drops are accumulated;
s700, circulating evaporation and crystallization: introducing the heating steam obtained in the step S600 into a first secondary heater and a second secondary heater to separate out crystals from the landfill leachate and obtain mother liquor, and introducing condensed water formed by secondary steam heat exchange into a secondary condensed water tank;
s800, solid-liquid separation treatment: discharging the crystals and the mother liquor out of the secondary separator, performing solid-liquid separation, returning one part of the obtained mother liquor into the secondary separator, performing solidification treatment on the other part of the obtained mother liquor, and performing landfill or incineration harmless treatment on the solidified dry solids and the crystals obtained by solid-liquid separation.
Preferably, in order to eliminate bubbles in the landfill leachate and simultaneously avoid scaling on the inner wall of the treatment device in the process of evaporation and concentration of the landfill leachate, the heat exchange efficiency is affected, the temperature rise time is prolonged, and the treatment cost is increased, the step S100 further comprises the steps of S00, defoaming, scale inhibition and purification: continuously adding a defoaming agent and a scale inhibitor into the landfill leachate.
Preferably, in order to enable the concentrated landfill leachate to rapidly increase the temperature and boil in the secondary separator so as to achieve the effect of evaporative crystallization, a concentration preheating treatment is further included between step S400 and step S500: and (4) introducing the landfill leachate obtained in the step (S400) into a fourth preheater, simultaneously introducing raw steam into the fourth preheater to exchange heat with the landfill leachate, discharging noncondensable gas formed after the raw steam exchanges heat out of a system, and introducing condensed water into a secondary condensed water tank.
Preferably, in order to collect condensed water generated during the gas washing, in step S300, accumulated water generated during the gas washing of the mixed gas by the condensed water is introduced into the primary condensed water tank.
Preferably, in order to collect the moisture in the secondary steam before the secondary steam enters the primary compressor and introduce the secondary steam into the primary condensate tank, so as to perform a heat exchange treatment on the landfill leachate flowing into the primary preheater, in step 300, condensed water is generated after the secondary steam is compressed, and the condensed water is introduced into the primary condensate tank.
Preferably, when in order to separate out crystals conveniently, the inside of the secondary separator is prevented from being blocked, the bottom of the secondary separator is provided with a salt leg, a secondary discharge hole is formed in the salt leg, a secondary circulation inlet is formed in the secondary separator, and the secondary discharge hole is communicated with the secondary circulation inlet.
Preferably, in order to separate the mother liquor from the crystals, in step S800, the crystals and the mother liquor sequentially pass through a thickener and a centrifuge for solid-liquid separation, and the separated mother liquor enters a mother liquor tank and then flows back a part of the mother liquor to the secondary separator.
Preferably, in order to conveniently introduce the separated mother liquor part into the secondary separator, the secondary separator is provided with a secondary separation inlet and a secondary separation outlet, the secondary separation outlet is communicated with the secondary separation inlet through the first secondary heater and the second secondary heater in sequence, and the mother liquor tank is communicated with the secondary separator through the second secondary heater.
Preferably, in order to ensure that the pressure inside the second-stage heater is consistent with the pressure inside the second-stage condensate water tank, so that condensate water in the second-stage heater can smoothly flow into the second-stage condensate water tank, a second-stage balance interface is arranged on the second-stage heater, and the second-stage balance interface is communicated with the second-stage condensate water tank.
Preferably, in order to improve the heat exchange efficiency of the landfill leachate, reduce heat loss and reduce the evaporation and concentration cost of the landfill leachate, the primary heater is a plate heater.
In conclusion, compared with the prior art, the two-stage MVR evaporative crystallization process for the landfill leachate has the advantages that the landfill leachate is sequentially preheated by using the condensed water and the non-condensable gas formed after heat exchange of the raw steam, the heat of the raw steam, the non-condensable gas and the condensed water is fully utilized, the heating time of the landfill leachate is shortened, the consumption of the raw steam is reduced while the efficiency is improved, and the energy consumption and the treatment cost are reduced.
Drawings
FIG. 1 is a schematic flow diagram of the present invention;
FIG. 2 is a schematic diagram of a process apparatus for using the present invention;
FIG. 3 is a schematic view showing the structure of an apparatus for performing the preheating step according to the present invention;
FIG. 4 is a schematic diagram of the structure of the apparatus for performing the first heating step of the present invention;
FIG. 5 is a schematic diagram of the configuration of the apparatus used to perform the first stage of the scrubbing compression step of the present invention;
FIG. 6 is a schematic view showing the structure of an apparatus for performing the cyclic evaporative concentration step of the present invention;
FIG. 7 is a schematic diagram of the structure of the apparatus for performing the two-stage heating step according to the present invention;
FIG. 8 is a schematic diagram of the structure of the apparatus for performing the two-stage purge compression step of the present invention;
FIG. 9 is a schematic view showing the structure of an apparatus for performing the cyclic evaporative crystallization step of the present invention;
FIG. 10 is a schematic view showing the construction of an apparatus for carrying out the solid-liquid separation treatment step of the present invention;
in the figure: 100. a first stage separator; 101. a primary separation inlet; 102. a first-stage separation outlet; 103. a primary secondary steam outlet; 104. a primary return port; 200. a primary heater; 300. a first-stage circulating pump; 400. a primary discharge pump; 500. a first-stage scrubber; 501. a primary secondary steam inlet; 502. a primary air outlet; 503. a primary scrubbing inlet; 504. a first-stage return outlet; 505. a primary water outlet; 600. a first stage compressor; 601. a first-stage compression inlet; 602. a first stage compression air outlet; 603. a first-stage compressed water outlet; 700. a secondary separator; 701. a secondary separation inlet; 702. a secondary separation outlet; 703. a secondary steam outlet; 704. a secondary return port; 705. salt leg; 706. a secondary circulation outlet; 707. a secondary discharge hole; 708. a secondary circulation inlet; 800. a second-stage circulating pump; 900. a first secondary heater; 901. a first secondary heating inlet; 902. a first secondary heating outlet; 903. a first secondary raw steam inlet; 904. a first secondary heating steam inlet; 905. a first secondary condensed water outlet; 906. a non-condensable gas outlet on the first level; 907. a first secondary lower non-condensable gas outlet; 110. a second secondary heater; 111. a second stage heating inlet; 112. a second secondary heating outlet; 113. a second stage raw steam inlet; 114. a second stage heating steam inlet; 115. a second secondary condensed water outlet; 116. a noncondensable gas outlet on the second level; 117. a second-level lower non-condensable gas outlet; 118. a second level of balance interface; 120. a secondary scrubber; 121. a secondary steam inlet; 122. a secondary air outlet; 123. a secondary scrubbing gas inlet; 124. a secondary reflux outlet; 125. a secondary water outlet; 130. a secondary compressor; 140. a primary condensate tank; 150. a first-stage condensate pump; 160. a first preheater; 170. a second preheater; 180. a third preheater; 190. a steam-water separator; 191. a steam-water separation inlet; 192. a steam-water separation air outlet; 193. a steam-water separation water outlet; 210. a vacuum pump; 220. a feed pump; 230. a primary spray pump; 240. a defoamer box; 250. a defoamer pump; 260. a scale inhibitor medicine chest; 270. a scale inhibitor drug pump; 280. a secondary condensate tank; 290. a second-stage condensate pump; 310. a thickener; 311. a thick inlet; 312. a slurry outlet; 313. a clear liquid overflow port; 320. a centrifuge; 321. a centrifugal inlet; 322. a centrifugal liquid outlet; 323. a centrifugal solids outlet; 330. a mother liquor tank; 340. a mother liquor pump; 350. a fourth preheater; 360. a first-stage air washing pump; 370. a first-stage water outlet pump; 380. a second-stage air washing pump; 390. a secondary water outlet pump; 410. a first volute water tank; 420. a first volute water pump; 430. a second volute water tank; 440. a second volute water pump; 450. a second-stage discharge pump.
Detailed Description
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, the two-stage MVR evaporative crystallization process for landfill leachate of the present invention comprises the following steps:
s000, defoaming, scale inhibition and purification: continuously adding a defoaming agent and a scale inhibitor into the landfill leachate;
s100, preheating and temperature rising treatment: the landfill leachate sequentially passes through a first preheater 160, a second preheater 170 and a third preheater 180, meanwhile, raw steam is introduced into the third preheater 180 for heat exchange, non-condensable gas formed after heat exchange of the raw steam is introduced into the second preheater 170, and condensed water is introduced into a primary condensed water tank 140 and then is introduced into a primary preheater;
s200, primary heating and temperature rising: pushing the landfill leachate to circularly flow between the primary heater 200 and the primary separator 100, introducing raw steam into the primary heater 200 for heat exchange, introducing non-condensable gas and condensed water formed by heat exchange into the second preheater 170 and the primary condensed water tank 140 respectively, and stopping introducing the raw steam after the landfill leachate generates mixed gas consisting of secondary steam and liquid drops in the primary separator 100;
s300, first-stage gas washing compression: the condensed water in the primary condensed water tank 140 is extracted to wash the mixed gas obtained in the step S200 to separate secondary steam and liquid droplets, the secondary steam is compressed to form heating steam, and the heating steam is introduced into the primary separator 100 after the liquid droplets are accumulated;
s400, circulating evaporation and concentration: introducing the heating steam obtained in the step S300 into the third preheater 180 and the first heater 200 for heat exchange to concentrate the landfill leachate to a set value, and introducing non-condensable gas and condensed water formed by secondary steam heat exchange into the second preheater 170 and the primary condensed water tank 140 respectively;
s450, concentration preheating treatment: introducing the landfill leachate obtained in the step S400 into a fourth preheater 350, introducing raw steam into the fourth preheater 350 to exchange heat with the landfill leachate, discharging noncondensable gas formed after the raw steam exchanges heat out of a system, and introducing condensed water into a secondary condensed water tank 280;
s500, secondary heating and temperature rising: pushing the concentrated landfill leachate to circularly flow among the secondary separator 700, the first secondary separator 700 and the second secondary separator 700, introducing raw steam into the first secondary separator 700 and the second secondary separator 700 for heat exchange, discharging non-condensable gas formed by the heat exchange out of a system, introducing condensed water into the secondary condensed water tank 280 and then introducing the condensed water into the primary preheater, and stopping introducing the raw steam after the landfill leachate boils in the secondary separator 700 to generate mixed gas consisting of secondary steam and liquid drops;
s600, secondary scrubbing compression: the condensed water in the secondary condensed water tank 280 is extracted to wash the mixed gas obtained in the step S500 to separate secondary steam and liquid droplets, the secondary steam is compressed to form heating steam, and the heating steam is introduced into the secondary separator 700 after the liquid droplets are accumulated;
s700, circulating evaporation and crystallization: introducing the heating steam obtained in the step S600 into a first secondary heater 900 and a second secondary heater 110 to separate out crystals from the landfill leachate and obtain mother liquor, and introducing condensed water formed by secondary steam heat exchange into a secondary condensed water tank 280;
s800, solid-liquid separation treatment: discharging the crystals and the mother liquor out of the secondary separator 700, performing solid-liquid separation, returning one part of the obtained mother liquor to the secondary separator 700, performing solidification treatment on the other part of the obtained mother liquor, and performing landfill or incineration harmless treatment on the dried solid obtained by solidification and the crystals obtained by solid-liquid separation.
Based on the two-stage MVR evaporative crystallization process of the landfill leachate, the invention also discloses a two-stage MVR evaporative crystallization device of the landfill leachate, which is shown in figure 2.
When the two-stage MVR evaporative crystallization process of landfill leachate of the present invention is in operation, step S000 is performed first, defoaming, scale inhibiting and purification (specifically, defoaming agent and scale inhibitor are continuously added into the landfill leachate), specifically, as shown in fig. 3, in the two-stage MVR evaporative crystallization apparatus of landfill leachate of the present invention (hereinafter, referred to as "evaporative crystallization apparatus"), an output end of the feed pump 220 is communicated with a material inlet of the first preheater 160, a material inlet of the first preheater 160 is connected with a waste liquid purification assembly, the waste liquid purification assembly includes a defoaming agent medicine box 240, a defoaming agent medicine pump 250, a scale inhibitor medicine box 260 and a scale inhibitor medicine pump 270, the defoaming agent medicine box 240 is communicated with the material inlet of the first preheater 160 through the defoaming agent medicine pump 250, and the scale inhibitor medicine box 260 is communicated with the material inlet of the first preheater 160 through the scale inhibitor medicine pump 270.
Garbage percolate to be evaporated and crystallized is continuously extracted from a garbage percolate source through a feeding pump 220 and is conveyed to an evaporation and crystallization device for crystallization treatment, defoaming agents in a defoaming agent medicine box 240 are conveyed into waste liquid through a defoaming agent medicine pump 250 before preheating, so that air bubbles in the waste liquid are eliminated, the problem that the heat exchange effect of the waste liquid and condensed water, noncondensable gas and generated steam is influenced by the bubbles in the waste liquid is avoided, and a scale inhibitor in a scale inhibitor medicine box 260 is conveyed into the waste liquid through a scale inhibitor medicine pump 270, so that scale is prevented from being formed on the pipe wall of a pipeline and the inner walls of a primary separator 100 and a secondary separator 700 after the waste liquid is evaporated, the heat absorption of the waste liquid is hindered, the energy consumption required by evaporating the waste liquid is increased, and therefore, the energy consumption is saved.
After defoaming and scale inhibition purification, preheating and heating treatment in step S100 is performed, specifically, as shown in fig. 3, the evaporative crystallization apparatus further includes a second preheater 170, a third preheater 180, a primary condensed water tank 140, a primary condensed water pump 150, a steam-water separator 190 and a vacuum pump 210; the steam-water separator 190 is provided with a steam-water separation inlet 191, a steam-water separation outlet 192 and a steam-water separation outlet 193.
Wherein the material outlet of the primary preheater 160, the material inlet of the second preheater 170, the material outlet of the second preheater 170, the material inlet of the third preheater 180 and the material outlet of the third preheater 180 are communicated in sequence. A heat medium inlet of the third preheater 170 is used for being connected with a raw steam source, a heat medium outlet of the third preheater 170 is communicated with a primary condensate water tank 140, the primary condensate water tank 140 is communicated with a heat medium inlet of the first preheater 160 through a primary condensate water pump 150, and a heat medium outlet of the first preheater 160 is communicated with the outside; the primary condensed water pump tank 140 is communicated with a heat medium inlet of the second preheater 180, a heat medium outlet of the second preheater 180 is communicated with a steam-water separation inlet 191, a steam-water separation air outlet 191 is communicated with the outside through a vacuum pump 210, and a steam-water separation water outlet 193 is communicated with the primary condensed water pump 140.
When the two-stage MVR evaporative crystallization process of the landfill leachate operates, raw steam is introduced into the third preheater 180 and then exchanges heat with the landfill leachate, the raw steam is condensed to form condensed water and non-condensable gas, and the temperatures of the landfill leachate, the condensed water and the non-condensable gas are sequentially increased, so the condensed water and the non-condensable gas are introduced into the primary condensed water tank 140, the condensed water and the non-condensable gas are contained in the primary condensed water tank 140, and the initial temperature of the landfill leachate, the temperature of the condensed water, the temperature of the non-condensable gas and the temperature of the raw steam are sequentially increased, so the condensed water is introduced into the first preheater 160 through the temperature difference of the four, the non-condensable gas is introduced into the second preheater 170, the raw steam is introduced into the third preheater 180, the landfill leachate is preheated by sequentially and respectively utilizing the condensed water, the non-condensable gas and the raw steam, and the heat of the landfill leachate can be utilized reasonably and preheated for multiple times before evaporative concentration, so as to achieve the purpose of saving energy and reducing consumption.
Specifically, under the action of the first-stage condensate pump 150, the condensate water is introduced into the heat medium inlet of the first preheater 160 from the first-stage condensate water tank 140, flows in the first preheater 160, and preheats the landfill leachate for the first time, so that after the temperature of the landfill leachate is raised, biochemical treatment is performed from the heat medium outlet discharge system of the first preheater 160.
After being discharged from the material outlet of the first preheater 160, the landfill leachate enters the second preheater 170 through the material inlet of the second preheater 170, the non-condensable gas in the primary condensate water tank 140 enters the second preheater 170 from the heat medium inlet of the second preheater 170, and exchanges heat with the landfill leachate, so that after the temperature of the landfill leachate is raised, the landfill leachate is discharged from the material outlet of the second preheater 170, the non-condensable gas after heat exchange enters the steam-water separator 190 through the steam-water separation inlet 191, gas and liquid are separated in the steam-water separator 190, the gas is discharged from the steam-water separation gas outlet 192, the gas is discharged from the system under the action of the vacuum pump 210 to carry out tail gas removal treatment, and the separated liquid forms condensed water and enters the primary condensate water tank 140.
Landfill leachate after heat exchange with noncondensable gas enters into in third preheater 180 from the material import of third preheater 180, and live steam enters into in third preheater 180 through the heat medium import of third preheater 180, live steam and landfill leachate carry out the heat exchange, make landfill leachate after the intensification, from material export discharge port, and the live steam temperature after the heat exchange descends, after the condensation becomes the comdenstion water, enter into one-level condensate water pitcher 140, thus, the cubic preheating treatment to landfill leachate has been realized, and make full use of the heat of live steam preheats many times, in the time of energy-concerving and environment-protective, the intensification effect to landfill leachate has been improved, so that landfill leachate boils in one-level separator 100 fast evaporation, realize concentrated effect.
After preheating and temperature rising treatment, primary heating and temperature rising are carried out on the landfill leachate. Specifically, as shown in fig. 4, the evaporative crystallization apparatus of the present invention further includes a primary heater 200, a primary separator 100 and a primary circulation pump 300, the primary separator 100 is provided with a primary separation inlet 101, a primary separation outlet 102, a primary secondary steam outlet 103 and a primary return port 104, and the primary heater 200 is preferably a plate heater, so as to ensure good heat transfer efficiency, reduce heat loss, and reduce energy consumption of evaporative concentration, thereby saving cost.
A heat medium inlet of the primary heater 200 is connected with a raw steam source, a heat medium outlet of the primary heater 200 is connected with the primary condensed water tank 140, a material inlet of the primary heater 200 is communicated with a material outlet of the third preheater 180, a material outlet of the primary heater 200 is communicated with the primary separation inlet 101, and the primary separation outlet 102 is communicated with the material inlet of the primary heater 200 through the primary circulating pump 300.
After the three times of preheating treatment, the landfill leachate enters the primary heater 200 through the material inlet of the primary heater 200, while flowing in the primary heater 200, a heating medium is introduced into the heat medium inlet of the primary heater 200, the heating medium is steam, namely the heat medium inlet is connected with a raw steam source, the landfill leachate is heated through the raw steam, after the temperature of the landfill leachate is raised, the landfill leachate is conveyed into the primary separator 100 through the primary separation inlet 101, and the landfill leachate is heated in the primary separator 100 so as to achieve the purpose of evaporation and concentration; the landfill leachate in the primary separator 100 is discharged from the primary separation outlet 102, under the pushing action of the primary circulating pump 300, the landfill leachate enters the primary heater 200 again through the material inlet of the primary heater 200, the landfill leachate exchanges heat with the raw steam heat medium flowing in the primary heater 200, so that the temperature of the landfill leachate rises and then enters the primary separator 100, the circulation is performed in such a way, the landfill leachate circularly flows in the primary separator 100 and the primary heater 200, the temperature rises in the primary separator 200 to generate secondary steam, liquid drops are mixed with the secondary steam, the formed mixed gas is discharged from the primary secondary steam outlet 103, and at the moment, the raw steam heat source is stopped being introduced into the primary heater 200.
When the garbage leachate exchanges heat with raw steam through the primary heater 200, the raw steam heats the garbage leachate which is about to enter the primary separator 100 in the primary heater 200, after the garbage leachate is heated, the temperature of the raw steam is reduced, the raw steam is condensed to form condensed water and non-condensable gas, the initial temperature of the garbage leachate, the temperature of the condensed water and the temperature of the non-condensable gas are sequentially increased, therefore, after the condensed water is introduced into the primary condensed water tank 140, the primary condensed water pump 150 extracts the condensed water in the primary condensed water tank 140 and conveys the condensed water to the first preheater 160 to preheat the material, and the condensed water after heat exchange is discharged out of the system to be biochemically processed; after the non-condensable gas enters the primary condensate water tank 140, the non-condensable gas passes through the second preheater 170, the landfill leachate heated by condensed water is heated in the second preheater 170, after the heating, the temperature of the landfill leachate rises again, the non-condensable gas after heat exchange enters the steam-water separator 190, gas-liquid separation is performed through the steam-water separator 190, the separated gas is discharged out of the system under the pushing action of the vacuum pump 210 to be subjected to tail gas removal treatment, the separated liquid forms condensed water and flows into the primary condensate water tank 140, so that the primary condensate water pump 150 is pumped and introduced into the first preheater 160 to perform primary preheating treatment on the landfill leachate.
After adopting above-mentioned mode, the system flows at primary separator 100 and primary heater 200 inner loop through control landfill leachate to let in raw steam to primary heater 200 and carry out the heat transfer, the noncondensable gas and the comdenstion water of formation carry out the heat transfer to landfill leachate respectively, thereby make full use of raw steam's heat, further improve landfill leachate's preheating effect, when reducing the raw steam quantity, realize energy-concerving and environment-protective, reduce the energy consumption.
After the mixed gas of the secondary steam and the liquid droplets is generated in the first-stage separator 200, the introduction of the raw steam into the first-stage heater 200 is stopped, and at this time, step S300 of first-stage gas washing compression is executed, specifically, as shown in fig. 5, the evaporative crystallization device further includes a first-stage gas washing tower 500, a first-stage compressor 600, a first-stage spray pump 230, a first-stage gas washing pump 360, a first-stage water outlet pump 370, a first volute water tank 410, a first volute water pump 420, a second volute water tank 420, and a second volute water pump 430.
The primary scrubbing tower 500 is provided with a primary scrubbing inlet 501, a primary air outlet 502, a primary reflux inlet 503, a primary reflux outlet 504 and a primary water outlet 505; the first-stage compressor 600 is provided with a first-stage compression inlet 601, a first-stage compression water outlet 603 and a first-stage compression air outlet 602.
The primary secondary steam outlet 103 is communicated with a primary washing gas inlet 501, the primary gas outlet 502 is communicated with a primary compression inlet 601, the primary condensed water pump 140 is communicated with a primary backflow inlet 503 through a primary spray pump 230, the primary backflow outlet 504 is communicated with the primary washing gas inlet 501 through a primary washing gas pump 360, the primary water outlet 505 is communicated with the primary backflow port 104 through a primary water outlet pump 360, the primary gas outlet 502 is also communicated with a first volute water tank 410, and the first volute water tank 410 is communicated with the primary condensed water tank 140 through a first volute water pump 420; the first-stage compression air outlet 602 is communicated with the heat medium inlet of the first-stage heater 200, the first-stage compression water outlet 603 is communicated with the second volute water tank 430, and the second volute water tank 430 is communicated with the first-stage condensate water tank 140 through the second volute water pump 440.
When landfill leachate evaporative concentration in one-level separator 100, contain the liquid drop in the generated secondary steam, form the mist, when the mist enters into one-level scrubbing tower 500, carry the comdenstion water from one-level condensation water pitcher 140 to one-level scrubbing tower 500 through one-level spray pump 230, and spray in one-level scrubbing tower 500, thereby reach the effect of washing gas, wash the liquid drop in the purification secondary steam, so that pure secondary steam enters into one-level compressor 600 and carries out compression treatment, form high temperature steam, carry high temperature steam to in one-level heater 200 again, heat the landfill leachate of flow in one-level heater 200, so, reduce the quantity of live steam, reach energy-conserving effect.
Specifically, when the primary scrubber tower 500 is in operation, the primary scrubber inlet 501 receives a mixed gas composed of secondary steam and liquid droplets discharged from the primary secondary steam outlet 103 of the primary separator 100, after scrubbing treatment, the scrubbed and purified secondary steam is discharged from the primary gas outlet 502, the condensed water at the bottom in the primary scrubber tower 500 contains a part of landfill leachate, after being discharged from the primary reflux outlet 504, the condensed water enters the primary scrubber tower 500 again from the primary scrubber inlet 501 under the action of the primary scrubber pump 360, and is scrubbed, when the concentration of the landfill leachate in the condensed water in the primary scrubber tower 500 is increased to a certain degree, the condensed water is discharged from the primary water outlet 505, and returns to the primary separator 100 through the primary reflux outlet 104 under the action of the primary water pump 370 to enter evaporation and concentration treatment.
After washing and purification, the secondary steam in the primary scrubber tower 500 is discharged through the primary gas outlet 502, and enters the primary compressor 600 through the primary compression inlet 601, the primary compressor 600 performs compression work on the secondary steam, the pressure and temperature of the secondary steam are increased to form heating steam, the heating steam is discharged from the primary compression gas outlet 602, and enters the primary heater 200 from the heat medium inlet of the primary heater 200, the heating steam flowing in the primary heater 200 exchanges heat with the landfill leachate material to be introduced into the primary separator 100, so that the landfill leachate temperature is increased and enters the primary separator 100, the heating steam forms condensate water and non-condensable gas after heat exchange, the non-condensable gas is introduced into the secondary preheater 170 to perform secondary preheating treatment on the landfill leachate, the condensate water enters the primary condensate water tank 140, the condensate water stored in the primary condensate water tank 140 can be fed into the first preheater 160 to perform primary preheating on the landfill leachate under the action of the primary spray pump 150, and can be fed into the primary gas scrubber tower 500 from the primary reflux inlet 503 to perform mixed gas scrubber treatment under the action of the primary spray pump 230. After adopting above-mentioned mode, utilize the secondary steam who produces to compress the work, form the heating steam that can carry out the heat transfer with landfill leachate, so, avoided lasting letting in raw steam in to primary heater 200 to reduce raw steam's quantity, when having reached energy-conserving this effect of reducing, promoted landfill leachate in primary separator 100 quick evaporation concentrated efficiency.
The primary scrubber tower 500 is used for washing and purifying secondary steam and liquid drops, condensed water in the primary scrubber tower 500 enters the first volute water tank 410, the first volute water pump 420 is started, the condensed water in the first volute water tank 410 is extracted and conveyed to the primary condensed water tank 140, and therefore the condensed water in the primary condensed water tank 140 is conveyed to the first preheater 160 to preheat the landfill leachate for the first time or conveyed to the primary scrubber tower 500 to perform scrubbing treatment on mixed gas.
And after the primary compressor 600 compresses the secondary steam to do work, condensed water is generated and is discharged from the primary compression water outlet 603, and enters the second volute water tank 430, the second volute water pump 440 is started to pump and convey the condensed water in the second volute water tank 430 into the primary condensed water tank 140, so as to preheat the landfill leachate for the first time or carry out scrubbing treatment on the mixed gas.
After the mode is adopted, the condensate water is formed by utilizing the heat exchange of the raw steam and the heat exchange of the secondary steam generated by the evaporation of the landfill leachate, so that the cooling water does not need to be additionally added in the use process of the device, the water consumption is reduced, and the operation cost of the device is reduced.
After compressing the secondary steam to do work, heating steam is formed, and when the heating steam is introduced into the first heater 200, the operation of circulating evaporation and concentration in step S400 is performed, as shown in fig. 6, the primary separation inlet 102 is connected with the primary discharge pump 400, and the input end of the primary discharge pump 400 is communicated with the primary separation inlet 102.
Heating steam is used for carrying out the heat transfer to the landfill leachate that flows in first heater 200, the noncondensable gas that the condensation of heating steam formed lets in second preheater 170, so that preheat the landfill leachate that gets into second preheater 170, and the comdenstion water that the condensation of heating steam formed lets in one-level condensate water pitcher 140, under the effect of one-level condensate water pump 150, let in first preheater 160, preheat the landfill leachate through first preheater 160, and under the effect of spray pump 230, let in gas washing tower 500, the mist that constitutes of liquid drop and secondary steam among the gas washing tower 500 inhales and handles, thus, the useless additional comdenstion water that uses, the water consumption has been reduced.
Meanwhile, the landfill leachate circulates in the primary separator 100 and the primary heater 200, so that the temperature of the landfill leachate gradually rises, the landfill leachate is evaporated and concentrated, when the landfill leachate is evaporated and concentrated to a concentration set value (the set value is specifically set and controlled by an operator), the primary discharge pump 400 is started, and the leachate after evaporation and concentration is discharged out of the MVR evaporation concentrator and is composed of the primary separator 100 and the primary heater 200.
After the concentrated landfill leachate is discharged, the operation of concentration preheating treatment in step S450 is performed, the landfill leachate obtained in step S400 is introduced into the fourth preheater 350, meanwhile, raw steam is introduced into the fourth preheater 350 to exchange heat with the landfill leachate, non-condensable gas formed after the heat exchange of the raw steam is discharged out of the system, and condensed water is introduced into the secondary condensed water tank 280.
Specifically, as shown in fig. 2 and 7, a fourth preheater 350 is disposed at an output end of the first-stage discharge pump 400, a material inlet of the fourth preheater 350 is communicated with the output end of the first-stage discharge pump 400, a material outlet of the fourth preheater 350 is communicated with the second-stage separator 700, a heat medium inlet of the fourth preheater 350 is used for connecting a raw steam source, a heat medium outlet of the fourth preheater 350 is communicated with a second condensed water tank 280, and the second condensed water tank 280 is communicated with a heat medium inlet of the first preheater 160 through a second condensed water pump 290.
More specifically, the landfill leachate after evaporation concentration is conveyed to the fourth preheater 350 by the primary discharge pump 260, meanwhile, the raw steam with higher temperature is conveyed to the fourth preheater 350 by the raw steam source through a heat medium inlet of the fourth preheater 350, after the raw steam exchanges heat with the concentrated landfill leachate, the concentrated landfill leachate enters the secondary separator 700 through the secondary separation inlet 701 to be subjected to evaporation crystallization treatment, the temperature of the raw steam after heat exchange is reduced, condensed water is formed by condensation and then enters the secondary condensation water tank 280, the condensed water in the secondary condensation water tank 280 is conveyed to the first preheater 160 under the action of the secondary condensation water pump 290, so that heat exchange is performed with the landfill leachate passing through the first preheater 280, and the first preheating treatment is realized. By adopting the above mode, the landfill leachate enters the secondary separator 700 through heat exchange with the raw steam after evaporation and concentration, so that the concentrated landfill leachate can be rapidly heated in the secondary separator 700, the technical effect of evaporation and crystallization can be achieved, and the evaporation and crystallization efficiency can be improved.
After preheating the concentrated landfill leachate, executing a secondary heating temperature rise operation in step S500, pushing the concentrated landfill leachate to circularly flow among the secondary separator 700, the first secondary separator 700 and the second secondary separator 700, introducing the generated steam into the first secondary separator 700 and the second secondary separator 700 for heat exchange, discharging the non-condensable gas formed by the heat exchange out of the system, introducing the condensed water into the secondary condensed water tank 280 and then into the primary preheater, and stopping introducing the generated steam after the landfill leachate boils in the secondary separator 700 to generate mixed gas consisting of secondary steam and liquid drops.
Specifically, as shown in fig. 7, the concentration and crystallization apparatus further includes a second separator 700, a first secondary heater 900, a second secondary heater 110, and a secondary circulation pump 800, wherein a salt leg 705 is disposed at the bottom of the second separator 700, a secondary separation inlet 702 is disposed at the bottom of the salt leg 705, a secondary discharge port 707 is disposed on the sidewall of the salt leg 705, and a secondary separation inlet 701, a secondary steam outlet 703, a secondary reflux port 704, a secondary circulation outlet 706, and a secondary circulation inlet are disposed on the second separator 700; the first secondary heater 900 is provided with a first secondary heating inlet 901, a first secondary heating outlet 902, a first secondary steam generating inlet 903, a first secondary heating steam inlet 904, a first secondary condensate outlet 905, a first secondary upper non-condensable gas outlet 906 and a first secondary lower non-condensable gas outlet 907; the second secondary heater 110 is provided with a second secondary heating inlet 111, a second secondary heating outlet 112, a second secondary steam inlet 113, a second secondary heating steam inlet 114, a second secondary condensed water outlet 115, a second secondary upper non-condensable gas outlet 116, a second secondary lower non-condensable gas outlet 117 and a second secondary balance interface 118.
The second-stage separation inlet 701 is communicated with a material outlet of the fourth preheater 350, the second-stage separation outlet 702 is communicated with the second-stage circulation outlet 706, both the second-stage separation outlet 702 and the second-stage circulation outlet 706 are communicated with a first second-stage heating inlet 901 of the first second-stage heater 900, the first second-stage heating outlet 902 is communicated with the second-stage heating inlet 111 through the second-stage circulation pump 800, and the second-stage heating outlet 112 is communicated with the second-stage separation inlet 701; the first secondary steam generating inlet 903 and the second secondary steam generating inlet 113 are both connected with a steam generating source, the first secondary condensate outlet 905 and the second secondary condensate outlet 115 are both communicated with the secondary condensate water tank 280, and the first secondary upper non-condensable gas outlet 906, the second secondary lower non-condensable gas outlet 117, the second secondary upper non-condensable gas outlet 116 and the second secondary lower non-condensable gas outlet 117 are all communicated with the outside; the second secondary equalization interface 118 is in communication with a secondary condensate tank 280.
After being preheated by the fourth preheater 350, the landfill leachate enters the secondary separator 700 through the secondary separation inlet 701, is discharged from the secondary separation outlet 702 and the secondary circulation outlet 706, enters the first secondary heater 900 through the first secondary heating inlet 901, is discharged, enters the second secondary heater 110 from the second secondary heating inlet 111 under the driving action of the secondary circulation pump 800, is discharged from the second secondary heating outlet 112, and enters the secondary separator 700 through the secondary separation inlet 701, so that the concentrated landfill leachate circularly flows among the secondary separator 700, the first secondary heater 900 and the second secondary heater 110.
In the process of the above circular flow of the landfill leachate, raw steam is respectively introduced into the first secondary heater 900 and the second secondary heater 110 through the first secondary raw steam inlet 903 and the second secondary raw steam inlet 113 by a raw steam source, the raw steam exchanges heat with the landfill leachate, so that the temperature of the landfill leachate gradually rises until secondary steam is generated in the secondary separator 700, and liquid drops mixed with the secondary steam are discharged from the secondary steam outlet 703.
The raw steam forms condensed water and non-condensable gas after heat exchange, the condensed water is discharged from a first secondary condensed water outlet 905 and a second secondary condensed water outlet 115 and enters a secondary condensed water tank 280, the condensed water in the secondary condensed water tank 280 is extracted by a secondary condensed water pump 290 and is conveyed into the first preheater 160 through a heat medium inlet of the first preheater 160 so as to exchange heat with waste liquid before entering the primary separator 100, then the condensed water is discharged outside for biochemical treatment, and a second secondary balance interface 118 is communicated with the secondary condensed water tank 280, so that the condensed water in the second secondary heater 110 can smoothly flow into the secondary condensed water tank 280; the non-condensable gas is discharged out of the system from a first-level upper non-condensable gas outlet 906, a first-level lower non-condensable gas outlet 907, a second-level upper non-condensable gas outlet 116 and a second-level lower non-condensable gas outlet 117 respectively to be subjected to tail gas removal treatment.
After the landfill leachate in the secondary separator 700 generates mixed gas consisting of secondary steam and liquid drops, the operation of S600 secondary scrubbing compression is performed: the condensed water in the secondary condensed water tank 280 is extracted to wash the mixed gas obtained in the step S500 to separate secondary steam and liquid droplets, the secondary steam is compressed to form heating steam, and the heating steam is introduced into the secondary separator 700 after the liquid droplets are accumulated.
Specifically, as shown in fig. 8, the evaporative crystallization apparatus further includes a secondary scrubber 120, a secondary compressor 130, a secondary scrubber pump 380, and a secondary water outlet pump 390. The second-stage scrubber tower 120 is provided with a second-stage scrubber inlet 121, a second-stage gas outlet 122, a second-stage reflux inlet 123, a second-stage reflux outlet 124 and a second-stage water outlet 125. The secondary washing gas inlet 121 is communicated with a secondary steam outlet 703, the secondary air outlet 122 is connected with the input end of the secondary compressor 130, the secondary return outlet 124 is communicated with the secondary washing gas inlet 121 through a secondary washing gas pump 380, the secondary return inlet 123 is connected with the output end of a secondary condensate pump 290, and the secondary water outlet 125 is communicated with a secondary return outlet 704 through a secondary water outlet pump 390.
Wherein, the secondary washing inlet 121 is used for introducing mixed gas (i.e. secondary steam mixed with liquid drops) generated by evaporative crystallization of landfill leachate into the secondary washing tower 120 through the secondary air suction inlet 121 when the secondary separator 700 is in operation, the secondary air outlet 122 is used for discharging washed secondary steam, so that the secondary steam enters the secondary compressor 130, heating steam with increased temperature and pressure is formed in a compression work-doing manner, the secondary reflux inlet 123 is used for introducing condensed water into the secondary washing tower 120 to wash and purify the secondary steam, and the secondary reflux outlet 124 is used for discharging washed condensed water; in the washing gas process, because comdenstion water and secondary steam contact for contain landfill leachate composition in the comdenstion water, and along with going on of washing gas, landfill leachate concentration increases, conveniently discharges the higher comdenstion water of landfill leachate concentration through second grade delivery port 125 this moment, in so that carry this comdenstion water to second grade separator 700 through second grade backward flow mouth 704, continue to carry out the evaporation crystallization treatment.
Specifically, when the landfill leachate in the secondary separator 700 is evaporated and crystallized, a mixed gas composed of secondary steam and liquid drops is generated, the mixed gas enters the secondary gas washing tower 120 through the secondary gas washing inlet 121 after being discharged from the secondary steam outlet 703 of the mixed gas, the condensed water in the secondary condensed water tank 280 is extracted by the secondary condensed water pump 290 and is conveyed into the secondary gas washing tower 120 through the secondary reflux inlet 123 for spraying, so as to achieve the effects of washing and purifying the secondary steam and separating gas from liquid, the condensed water is deposited in the secondary gas washing tower 120 after gas washing, at this time, the condensed water in the secondary condensed water tank 280 does not need to be extracted by the secondary condensed water pump 290, the condensed water is extracted from the secondary reflux outlet 124 by the secondary gas washing pump 380, and is conveyed into the secondary gas washing tower 120 through the secondary gas washing inlet 121 for continuous spray gas washing treatment.
In the process of gas washing, pure secondary steam is formed, the secondary steam enters the secondary compressor 130 after being discharged from the secondary gas outlet 122, and is compressed by the secondary compressor 130 to do work, so that the temperature and the pressure of the steam are increased to form heating steam.
After the secondary steam is subjected to the gas washing and compression treatment, heating steam is formed, and the operation of step S700 of circulating evaporative crystallization is performed: s700, circulating evaporation and crystallization: and (4) introducing the heating steam obtained in the step (S600) into a first secondary heater and a second secondary heater to separate out crystals from the landfill leachate and obtain mother liquor, and introducing condensed water formed by secondary steam heat exchange into a secondary condensed water tank 280.
Specifically, as shown in fig. 9, the output end of the secondary compressor 130 is communicated with a first secondary heating steam inlet 904 and a second secondary heating steam inlet 905, and a secondary discharge port 707 is connected with a secondary circulation inlet 708 through a secondary discharge pump 450.
The temperature and the pressure of the heating steam are increased compared with the secondary steam discharged from the secondary separator 700, at this time, the heating steam can replace the raw steam of a raw steam source to heat the landfill leachate, specifically, the heating steam enters the first secondary heater 900 and the second secondary heater 110 through the first secondary heating steam inlet 904 and the second secondary heating steam inlet 114 respectively, the heating steam exchanges heat with the landfill leachate which flows circularly, so that the landfill leachate in the system is continuously boiled, the temperature of the heating steam is reduced after the landfill leachate is heated, condensed water and non-condensable gas are formed by condensation, the condensed water is discharged from the first secondary condensed water outlet 905 and the second secondary condensed water outlet 115, enters the secondary condensed water tank 280, the condensed water in the secondary condensed water 280 is extracted by the secondary condensed water pump 290, and is conveyed into the first pre-heater 160 through the heat medium inlet of the first pre-heater 160 so as to exchange heat with the landfill leachate before entering the primary separator 100, the condensed water discharge system carries out biochemical treatment, the second secondary condensed water balance interface 118 is communicated with the secondary condensed water tank 280, so that the condensed water in the second secondary heater 110 can smoothly flow to the secondary condensed water tank 280; the non-condensable gas is respectively discharged from a first-level upper non-condensable gas outlet 906, a first-level lower non-condensable gas outlet 907, a second-level upper non-condensable gas outlet 116 and a second-level lower non-condensable gas outlet 117 and then collected, and the discharged gas is discharged to a tail gas treatment system.
Along with the continuous rise of the temperature of the landfill leachate, the landfill leachate is close to the secondary separator 700 after boiling and evaporation, crystals are separated out and settle at the bottom of the salt leg 705, and the secondary separation outlet 702 and the secondary circulation outlet 706 are communicated with each other, so that the crystals are prevented from being blocked at the bottom of the secondary separator 700; in the process of evaporative crystallization, the secondary discharge pump 450 pumps the mother liquor in the salt leg 705, and the mother liquor is conveyed into the secondary separator 700 through the secondary circulation inlet 708, so that the mother liquor is subjected to evaporative crystallization again, and crystals are separated from the mother liquor and settle at the bottom of the salt leg 705. When the crystal concentration reaches a certain degree, the secondary discharge pump 450 discharges the mixture of the mother liquor and the crystals out of the secondary separator 700 for subsequent solid-liquid separation treatment.
Step S800 solid-liquid separation treatment: discharging the crystals and the mother liquor out of the secondary separator 700, performing solid-liquid separation, returning one part of the obtained mother liquor to the secondary separator 700, performing solidification treatment on the other part of the obtained mother liquor, and performing landfill or incineration harmless treatment on the dried solid obtained by solidification and the crystals obtained by solid-liquid separation. In the above steps, the crystals and the mother liquor sequentially pass through the thickener 310 and the centrifuge 320 for solid-liquid separation, the separated mother liquor enters the mother liquor tank 330, and then part of the mother liquor flows back to the secondary separator 700, and the mother liquor tank 330 is communicated with the secondary separator 700 through the second secondary heater 110.
Specifically, as shown in fig. 10, the evaporative crystallization apparatus further includes a thickener 310, a centrifuge 320, a mother liquor tank 330 and a mother liquor pump 340, the thickener 310 is provided with a thick inlet 311, a slurry outlet 312 and a clear liquor overflow port 313, the thick inlet 311 is communicated with the output end of the secondary discharge pump 450, the slurry outlet 312 is communicated with the mother liquor tank 330 through the centrifuge 320, the clear liquor outlet is communicated with the mother liquor tank 330, and the mother liquor tank 330 is communicated with the secondary separation inlet 701 of the secondary separator 700 through the mother liquor pump 340.
Specifically, the top of the thickener 310 is provided with a thick inlet 311, the side wall is provided with a clear liquid overflow port 313, and the bottom is provided with a slurry outlet 312; the centrifuge 320 is provided with a centrifugal inlet 321, a centrifugal liquid outlet 322 and a centrifugal solid outlet 323; the thick inlet 311 is connected with the output end of the secondary discharging pump 450, the clear liquid overflow port 313 is communicated with the mother liquor tank 330, the slurry outlet 312 is communicated with the centrifugal inlet 321, the centrifugal solid outlet 323 is communicated with the outside, the centrifugal liquid outlet 322 is communicated with the mother liquor tank 330, and the output end of the mother liquor pump 340 is communicated with the second secondary heating inlet 111.
During solid-liquid separation, the discharging pump 450 conveys the mixture of the crystals and the mother liquor into the thickener 310 through the thick inlet 311, the crystals of the solid particles are settled at the bottom of the thickener 310 in the thickener 310, so that the liquid level of the clear liquid in the thickener 310 gradually rises, the clear liquid overflows from the clear liquid overflow port 313 along with the gradual rise of the liquid level and enters the mother liquor tank 330, the slurry mixture formed by mixing the crystals and part of the mother liquor is discharged from the slurry outlet 312 at the bottom and then enters the centrifuge 320 through the centrifugal inlet 321, the slurry is subjected to solid-liquid separation through the centrifuge 320, the centrifuged solid is subjected to slurry drying, the dried centrifuged solid is discharged to the outside through the centrifuged solid outlet 323 to be landfilled or incinerated for harmless treatment, and the separated mother liquor flows into the mother liquor tank 330 from the centrifuged liquid outlet 322. The mother liquor pump 340 pumps the mother liquor in the mother liquor tank 330, the mother liquor is divided into two parts for treatment, wherein one part of the mother liquor is conveyed to the second secondary heating inlet 111 through the mother liquor pump 340, so that the part of the mother liquor is heated by the second secondary heater 110 and then returns to the secondary separator 700 for continuous evaporation and crystallization, while the other part of the mother liquor is conveyed to an external blade dryer for drying treatment through the mother liquor pump 340, so as to realize solidification, and the solidified dry solid is treated in a landfill or incineration harmless treatment mode.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A two-stage MVR evaporation crystallization process for landfill leachate is characterized by comprising the following steps:
s100, preheating and temperature rising treatment: the landfill leachate sequentially passes through a first preheater, a second preheater and a third preheater, raw steam is introduced into the third preheater for heat exchange, non-condensable gas formed after heat exchange of the raw steam is introduced into the second preheater, and condensed water is introduced into a primary condensed water tank and then introduced into a primary preheater;
s200, primary heating and temperature rising: pushing the landfill leachate to circularly flow between the primary heater and the primary separator, introducing raw steam into the primary heater for heat exchange, introducing non-condensable gas and condensed water formed by heat exchange into the second preheater and the primary condensed water tank respectively, and stopping introducing the raw steam after the landfill leachate generates mixed gas consisting of secondary steam and liquid drops in the primary separator;
s300, first-stage gas washing compression: extracting condensed water in a primary condensed water tank to wash the mixed gas obtained in the step S200 to separate secondary steam and liquid drops, compressing the secondary steam to form heating steam, and introducing the heating steam into a primary separator after the liquid drops are accumulated;
s400, circulating evaporation and concentration: introducing the heating steam obtained in the step S300 into a third preheater and a first heater for heat exchange to concentrate the landfill leachate to a set value, and introducing non-condensable gas and condensed water formed by secondary steam heat exchange into a second preheater and a primary condensed water tank respectively;
s500, secondary heating and temperature rising: pushing the concentrated landfill leachate to circularly flow among the secondary separator, the first secondary separator and the second secondary separator, introducing raw steam into the first secondary separator and the second secondary separator for heat exchange, discharging non-condensable gas formed by the heat exchange out of a system, introducing condensed water into a secondary condensed water tank and then introducing the condensed water into a primary preheater, and stopping introducing the raw steam after the landfill leachate boils in the secondary separator to generate mixed gas consisting of secondary steam and liquid drops;
s600, secondary air washing compression: extracting condensed water in a secondary condensed water tank to wash the mixed gas obtained in the step S500 to separate secondary steam and liquid drops, compressing the secondary steam to form heating steam, and introducing the heating steam into a secondary separator after the liquid drops are accumulated;
s700, circulating evaporation and crystallization: introducing the heating steam obtained in the step S600 into a first secondary heater and a second secondary heater to separate out crystals from the landfill leachate and obtain mother liquor, and introducing condensed water formed by secondary steam heat exchange into a secondary condensed water tank;
s800, solid-liquid separation treatment: discharging the crystals and the mother liquor out of the secondary separator, performing solid-liquid separation, returning one part of the obtained mother liquor to the secondary separator, performing solidification treatment on the other part of the obtained mother liquor, and performing landfill or incineration harmless treatment on the dried solid obtained by solidification and the crystals obtained by solid-liquid separation.
2. The landfill leachate two-stage MVR evaporative crystallization process of claim 1, wherein: step S000, defoaming, scale inhibition and purification are also included before the step S100: continuously adding a defoaming agent and a scale inhibitor into the landfill leachate.
3. The landfill leachate two-stage MVR evaporative crystallization process of claim 1, wherein: the method also comprises a step S410 and a concentration preheating treatment between the step S400 and the step S500: and (4) introducing the landfill leachate obtained in the step (S400) into a fourth preheater, simultaneously introducing raw steam into the fourth preheater to exchange heat with the landfill leachate, discharging noncondensable gas formed after the raw steam exchanges heat out of a system, and introducing condensed water into a secondary condensed water tank.
4. The landfill leachate two-stage MVR evaporative crystallization process of claim 1, wherein: in step S300, the water accumulated during the gas washing of the mixed gas by the condensed water is introduced into the primary condensed water tank.
5. The two-stage MVR evaporative crystallization process of landfill leachate according to claim 1, characterized in that: in the step 300, condensed water is generated after the secondary steam is compressed, and the condensed water is introduced into the primary condensed water tank.
6. The landfill leachate two-stage MVR evaporative crystallization process of claim 1, wherein: the bottom of the secondary separator is provided with a salt leg, a secondary discharge hole is formed in the salt leg, a secondary circulation inlet is formed in the secondary separator, and the secondary discharge hole is communicated with the secondary circulation inlet.
7. The two-stage MVR evaporative crystallization process of landfill leachate according to claim 1, characterized in that: in the step S800, the crystals and the mother liquor sequentially pass through the thickener and the centrifuge for solid-liquid separation, and the separated mother liquor enters the mother liquor tank and then flows back part of the mother liquor to the secondary separator.
8. The landfill leachate two-stage MVR evaporative crystallization process of claim 7, wherein: and the secondary separator is provided with a secondary separation inlet and a secondary separation outlet, the secondary separation outlet is communicated with the secondary separation inlet sequentially through the first secondary heater and the second secondary heater, and the mother liquor tank is communicated with the secondary separator through the second secondary heater.
9. The landfill leachate two-stage MVR evaporative crystallization process of claim 1, wherein: and a second secondary balance interface is arranged on the second secondary heater and is communicated with a secondary condensed water tank.
10. The landfill leachate two-stage MVR evaporative crystallization process of claim 1, wherein: the primary heater is a plate heater.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104803535A (en) * | 2015-05-06 | 2015-07-29 | 广州新普利节能环保科技有限公司 | Recycling system and recycling process for recycling salt from desulfurization waste water |
| CN111115735A (en) * | 2020-02-26 | 2020-05-08 | 大连广泰源环保科技有限公司 | Two-stage forced circulation evaporation system and process for landfill leachate |
| CN216549700U (en) * | 2021-12-01 | 2022-05-17 | 江阴市江中设备制造有限公司 | Potassium perchlorate effluent evaporation plant |
| CN216997745U (en) * | 2022-04-07 | 2022-07-19 | 中洁蓝环保科技有限公司 | Salt system is divided in industrial waste water salt washing |
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- 2022-12-26 CN CN202211671615.8A patent/CN115947400A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104803535A (en) * | 2015-05-06 | 2015-07-29 | 广州新普利节能环保科技有限公司 | Recycling system and recycling process for recycling salt from desulfurization waste water |
| CN111115735A (en) * | 2020-02-26 | 2020-05-08 | 大连广泰源环保科技有限公司 | Two-stage forced circulation evaporation system and process for landfill leachate |
| CN216549700U (en) * | 2021-12-01 | 2022-05-17 | 江阴市江中设备制造有限公司 | Potassium perchlorate effluent evaporation plant |
| CN216997745U (en) * | 2022-04-07 | 2022-07-19 | 中洁蓝环保科技有限公司 | Salt system is divided in industrial waste water salt washing |
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