CN114906895A - Salt-containing wastewater crystallization treatment device and treatment method - Google Patents
Salt-containing wastewater crystallization treatment device and treatment method Download PDFInfo
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- CN114906895A CN114906895A CN202210711895.4A CN202210711895A CN114906895A CN 114906895 A CN114906895 A CN 114906895A CN 202210711895 A CN202210711895 A CN 202210711895A CN 114906895 A CN114906895 A CN 114906895A
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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
- C02F1/041—Treatment of water, waste water, or sewage by heating by distillation or evaporation by means of vapour compression
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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
- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/30—Wastewater or sewage treatment systems using renewable energies
- Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy
Abstract
The invention relates to a salt-containing wastewater crystallization treatment device and a treatment method. The salt-containing wastewater crystallization treatment device comprises a preheating module, an MVR evaporation module and an evaporation crystallization module; the preheating module is used for heating the primary wastewater, the preheating module comprises a first heat exchanger and a second heat exchanger, a cold source inlet of the first heat exchanger is used for allowing the primary wastewater to flow in, and a cold source outlet of the first heat exchanger is communicated with a cold source inlet of the second heat exchanger; a water inlet of the MVR evaporation module is communicated with a cold source outlet of the second heat exchanger, and a heat source inlet of the second heat exchanger is communicated with an air outlet of the MVR evaporation module; the water inlet of the evaporation crystallization module is communicated with the first water outlet of the MVR evaporation module, and the heat source inlet of the first heat exchanger is communicated with the gas outlet of the evaporation crystallization module. This contain salt effluent crystallization processing apparatus sets up the steam heat of preheating module make full use of evaporation crystallization module and MVR evaporation module, has realized the cyclic utilization of heat energy, has effectively reduced the treatment cost who contains salt effluent.
Description
Technical Field
The invention relates to the technical field of wastewater treatment processes, in particular to a salt-containing wastewater crystallization treatment device and a salt-containing wastewater crystallization treatment method.
Background
With the increasing strictness of sewage discharge standards, the discharge indexes of sewage become stricter. The development of some chemical enterprises is limited by the strictness of the sewage discharge standard, for example, some rare earth enterprises have high content of sewage salt, total nitrogen and ammonia nitrogen because a large amount of nitric acid and ammonium salt are used in the process. Before the total nitrogen emission index requirement is not met, the sewage is directly discharged as assumed clean sewage after ammonia liquor is recovered by adopting a stripping process. Now, the high-nitrate sewage needs to be separately treated to reach a new discharge standard.
A common nitrate treatment process is a biological denitrification process, but for high-nitrate wastewater such as rare earth wastewater, the salt content is 3% -5%, and the total nitrogen concentration is 4000-8000 mg/L. The conductivity exceeds the tolerance limit of microorganisms, and biochemical treatment can be carried out only after the salt content is diluted, so that the treatment scale and the occupied area are multiplied; the nitrate concentration is high, a large amount of external carbon sources need to be added, the cost of the carbon sources can reach dozens of yuan per ton of water, even hundreds of yuan per ton of water, and the treatment cost is very high. The organic matters in the sewage are basically process extraction agents, almost cannot be biodegraded, and can reach the discharge standard only by adopting an advanced oxidation process, and the cost of the process is high.
Evaporative concentration crystallization is a method for treating salt-containing wastewater, and the wastewater is heated to a boiling state in a heat exchange mode, so that most of water in the wastewater is vaporized, condensed and recycled, and the concentration of inorganic salts in the wastewater is increased to crystallize out from the wastewater.
An MVR evaporation concentrator and a multi-effect evaporator are generally adopted to carry out evaporation treatment on the high-concentration salt-containing wastewater. However, evaporative crystallization of inorganic salts in wastewater often requires a large amount of heat to heat the evaporator, resulting in high wastewater treatment cost.
Disclosure of Invention
Therefore, it is necessary to provide a salt-containing wastewater crystallization treatment apparatus and a treatment method, which aim at the problem of high inorganic salt treatment cost in wastewater.
A salt-containing wastewater crystallization treatment device comprises:
the preheating module is used for heating primary wastewater, the preheating module comprises a first heat exchanger and a second heat exchanger, a cold source inlet of the first heat exchanger is used for allowing the primary wastewater to flow in, and a cold source outlet of the first heat exchanger is communicated with a cold source inlet of the second heat exchanger;
the MVR evaporation module is used for evaporating and concentrating the primary wastewater and generating concentrated wastewater, a water inlet of the MVR evaporation module is communicated with a cold source outlet of the second heat exchanger, an air inlet of the MVR evaporation module is used for allowing boiler steam to flow in, and a heat source inlet of the second heat exchanger is communicated with an air outlet of the MVR evaporation module;
the evaporative crystallization module is used for carrying out evaporative crystallization on the concentrated wastewater and generating a solid-liquid mixture, a water inlet of the evaporative crystallization module is communicated with a first water outlet of the MVR evaporative module, so that the concentrated wastewater flows into the evaporative crystallization module, and a heat source inlet of the first heat exchanger is communicated with a gas outlet of the evaporative crystallization module.
Foretell contain salt effluent crystal treatment plant, at first MVR evaporation module carries out evaporative concentration to elementary waste water through boiler steam, obtains the concentrated waste water that contains high concentration inorganic salt, then carries out further evaporative crystallization to concentrated waste water through evaporation crystallization module, obtains the solid-liquid mixture that contains solid-state crystallization salt, realizes the recycle to the inorganic salt in the salt effluent. Because the evaporation crystallization module adopts low-pressure evaporation crystallization, the boiling temperature of the concentrated wastewater under low pressure is lower than that of the concentrated wastewater under normal pressure, the evaporation crystallization module needs less heat for heating the concentrated wastewater, and the temperature of steam generated by the evaporation crystallization module is lower. And the preheating module is also arranged, so that the water vapor generated by the evaporation crystallization module and the MVR evaporation module sequentially passes through the first heat exchanger and the second heat exchanger to exchange heat with primary wastewater, the primary wastewater is preheated, the temperature of the water vapor is fully utilized, and the heat requirement of the MVR evaporation module on the steam of an external boiler is reduced. Consequently, this contain salt waste water crystallization processing apparatus supports the environment through setting up at the evaporation crystallization module and reduces the required heat of evaporation crystallization to the setting preheats the steam heat of module make full use of evaporation crystallization module and MVR evaporation module, has realized the cyclic utilization of heat energy, has effectively reduced the treatment cost who contains salt waste water.
In one embodiment, the MVR evaporation module includes a first evaporator and a vapor compressor, a cold source outlet of the second heat exchanger is communicated with a water inlet of the first evaporator, a first water outlet of the first evaporator is communicated with a water inlet of the evaporation crystallization module, a gas outlet of the first evaporator is communicated with a gas inlet of the vapor compressor, and a gas outlet of the vapor compressor is communicated with a heat source inlet of the second heat exchanger.
In one embodiment, the MVR evaporation module further includes a first reflux pump and a third heat exchanger, the second water outlet of the first evaporator is communicated with the inlet of the first reflux pump, the outlet of the first reflux pump is communicated with the cold source inlet of the third heat exchanger, the cold source outlet of the third heat exchanger is communicated with the water inlet of the first evaporator, the air outlet of the vapor compressor is communicated with the heat source inlet of the third heat exchanger, and the heat source outlet of the third heat exchanger is communicated with the heat source inlet of the second heat exchanger.
In one embodiment, the MVR evaporation module further includes a first liquid storage tank, the preheating module further includes a fourth heat exchanger, a heat source outlet of the second heat exchanger and a heat source outlet of the third heat exchanger are both communicated with a water inlet of the first liquid storage tank, a water outlet of the first liquid storage tank is communicated with a heat source inlet of the fourth heat exchanger, a part of the primary wastewater flows into a cold source inlet of the fourth heat exchanger, another part of the primary wastewater flows into a cold source inlet of the first heat exchanger, and a cold source outlet of the fourth heat exchanger and a cold source outlet of the first heat exchanger are both communicated with a cold source inlet of the second heat exchanger.
In one embodiment, the evaporative crystallization module comprises a second evaporator, the second evaporator is used for carrying out evaporative crystallization on the concentrated wastewater and generating the solid-liquid mixture, a water inlet of the second evaporator is communicated with a first water outlet of the MVR evaporation module, an outlet of the second evaporator is used for discharging the solid-liquid mixture, and a gas outlet of the second evaporator is communicated with a heat source inlet of the first heat exchanger.
In one of them embodiment, the evaporation crystallization module still includes heat medium heater, the second evaporimeter is the evaporimeter, be equipped with crystallization chamber and heating chamber in the second evaporimeter, the heating chamber centers on the crystallization chamber sets up, the heating intracavity is equipped with the heat medium, the heat medium is used for right the crystallization chamber heating, the water inlet of crystallization chamber with MVR evaporation module's first delivery port intercommunication, the export of crystallization chamber is used for discharging solid-liquid mixture, the gas outlet of crystallization chamber with the heat source entry intercommunication of first heat exchanger, the export of heating chamber with the entry intercommunication of heat medium heater, the export of heat medium heater with the entry intercommunication of heating chamber.
In one embodiment, the evaporative crystallization module further comprises a vacuum pump, wherein the vacuum pump is communicated with the crystallization cavity, so that the pressure of the crystallization cavity is 18.16kPa-19.94 kPa.
In one embodiment, the evaporative crystallization module further comprises a solid-liquid separator, the solid-liquid separator is used for separating liquid and solid crystalline salt in the solid-liquid mixture, an inlet of the solid-liquid separator is communicated with an outlet of the second evaporator, a water outlet of the solid-liquid separator is communicated with a water inlet of the second evaporator, and a solid outlet of the solid-liquid separator is used for discharging the solid crystalline salt.
In one embodiment, the evaporative crystallization module further comprises a second liquid storage tank and a second reflux pump, the water outlet of the solid-liquid separator is communicated with the water inlet of the second liquid storage tank, the water outlet of the second liquid storage tank is communicated with the inlet of the second reflux pump, and the outlet of the second reflux pump is communicated with the water inlet of the second evaporator.
A method for crystallizing and treating salt-containing wastewater by using the salt-containing wastewater treatment device comprises the following steps:
the preheating module heats the primary wastewater;
the MVR evaporation concentration module is used for carrying out evaporation concentration on the preheated primary wastewater and generating concentrated wastewater, wherein the salt mass concentration of the concentrated wastewater is 50-52%;
and the evaporative crystallization module carries out evaporative crystallization on the concentrated wastewater in a low-pressure environment and generates a solid-liquid mixture, wherein the salt mass concentration of the solid-liquid mixture is 90-95%.
Drawings
FIG. 1 is a schematic structural diagram of a salt-containing wastewater crystallization treatment device in one embodiment.
Reference numerals: 100. a salt-containing wastewater crystallization treatment device; 10. a preheating module; 11. a first heat exchanger; 12. a second heat exchanger; 13. a fourth heat exchanger; 14. a first liquid storage tank; 15. a third liquid storage tank; 16. a first lift pump; 17. a second lift pump; 18. a third lift pump; 19. a vacuum pump; 20. an MVR evaporation module; 21. a first evaporator; 22. a third heat exchanger; 23. a vapor compressor; 24. a first reflux pump; 25. a concentration pump; 30. an evaporative crystallization module; 31. a second evaporator; 32. a circulation pump; 33. a heating medium heater; 34. a solid-liquid separator; 35. a second liquid storage tank; 36. a second reflux pump.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
The saline wastewater crystallization treatment device 100 and the saline wastewater crystallization treatment method in some embodiments are described in detail below with reference to the accompanying drawings.
As shown in fig. 1, in one embodiment, there is provided a salt-containing wastewater crystallization treatment apparatus 100, which comprises a preheating module 10, an MVR evaporation module 20 and an evaporation crystallization module 30;
the MVR evaporator is short for English mechanical vapor compression and is a mechanical vapor evaporator.
The preheating module 10 is used for heating primary wastewater, the preheating module 10 comprises a first heat exchanger 11 and a second heat exchanger 12, a cold source inlet of the first heat exchanger 11 is used for allowing the primary wastewater to flow in, and a cold source outlet of the first heat exchanger 11 is communicated with a cold source inlet of the second heat exchanger 12;
the MVR evaporation module 20 is used for evaporating and concentrating the primary wastewater and generating concentrated wastewater, a water inlet of the MVR evaporation module 20 is communicated with a cold source outlet of the second heat exchanger 12, an air inlet of the MVR evaporation module 20 is used for allowing boiler steam to flow in, and a heat source inlet of the second heat exchanger 12 is communicated with an air outlet of the MVR evaporation module 20;
meanwhile, the evaporative crystallization module 30 is used for carrying out evaporative crystallization on the concentrated wastewater and generating a solid-liquid mixture, a water inlet of the evaporative crystallization module 30 is communicated with a first water outlet of the MVR evaporative module 20, so that the concentrated wastewater flows into the evaporative crystallization module 30, and a heat source inlet of the first heat exchanger 11 is communicated with a gas outlet of the evaporative crystallization module 30.
In the salt-containing wastewater crystallization treatment device 100, firstly, the MVR evaporation module 20 evaporates and concentrates the primary wastewater through boiler steam to obtain concentrated wastewater containing high-concentration inorganic salts, and then the concentrated wastewater is further evaporated and crystallized through the evaporation and crystallization module 30 to obtain a solid-liquid mixture containing solid crystalline salts, so that the inorganic salts in the salt-containing wastewater are recycled. Because the evaporation crystallization module 30 adopts low-pressure evaporation crystallization, the boiling temperature of the concentrated wastewater under low pressure is lower than that of the concentrated wastewater under normal pressure, the evaporation crystallization module 30 needs less heat for heating the concentrated wastewater, and the temperature of steam generated by the evaporation crystallization module 30 is lower. And the preheating module 10 is also arranged, so that water vapor generated by the evaporation crystallization module 30 and the MVR evaporation module 20 sequentially passes through the first heat exchanger 11 and the second heat exchanger 12 to exchange heat with primary wastewater, the primary wastewater is preheated, the temperature of the water vapor is fully utilized, and the heat requirement of the MVR evaporation module 20 on steam of an external boiler is reduced. Therefore, this contain salt effluent crystal treatment plant 100 through set up the required heat of low pressure environment reduction evaporative crystallization at evaporative crystallization module 30 to the setting preheats the steam heat of module 10 make full use of evaporative crystallization module 30 and MVR evaporation module 20, has realized the cyclic utilization of heat energy, has effectively reduced the treatment cost who contains salt effluent.
Specifically, as shown in fig. 1, in an embodiment, the MVR evaporation module 20 includes a first evaporator 21 and a vapor compressor 23, a cold source outlet of the second heat exchanger 12 is communicated with a water inlet of the first evaporator 21, a first water outlet of the first evaporator 21 is communicated with a water inlet of the evaporation crystallization module 30, a gas outlet of the first evaporator 21 is communicated with a gas inlet of the vapor compressor 23, and a gas outlet of the vapor compressor 23 is communicated with a heat source inlet of the second heat exchanger 12. The steam generated by the first evaporator 21 is pressurized and heated by the steam compressor 23, and the pressurized and heated steam enters the second heat exchanger 12 to exchange heat with the primary wastewater, so that the temperature of the primary wastewater is increased, and the pressure in the first evaporator 21 is increased.
In this embodiment, the pressure of the first evaporator 21 is higher than the saturated vapor pressure of the primary wastewater at a certain temperature (108-110 ℃), so that when the temperature of the primary wastewater reaches 108-110 ℃, the primary wastewater is flashed in the first evaporator 21, so that the moisture in the primary wastewater is evaporated to form high-temperature vapor, and the temperature of the vapor generated in the first evaporator 21 is 95-100 ℃.
Specifically, as shown in fig. 1, in an embodiment, the MVR evaporation module 20 further includes a first backflow pump 24 and a third heat exchanger 22, a second water outlet of the first evaporator 21 is communicated with an inlet of the first backflow pump 24, an outlet of the first backflow pump 24 is communicated with a cold source inlet of the third heat exchanger 22, a cold source outlet of the third heat exchanger 22 is communicated with a water inlet of the first evaporator 21, an air outlet of the vapor compressor 23 is communicated with a heat source inlet of the third heat exchanger 22, and a heat source outlet of the third heat exchanger 22 is communicated with a heat source inlet of the second heat exchanger 12. The first reflux pump 24 and the third heat exchanger 22 are used for heating and refluxing the primary wastewater with the salt concentration lower than that of the concentrated wastewater in the first evaporator 21, so that the moisture in the primary wastewater is further evaporated until the concentrated wastewater with the higher salt concentration is obtained. Wherein the salt solution concentration of the concentrated wastewater is generally set to be 50-52%.
In this embodiment, the air outlet of the first evaporator 21 is disposed at the top of the first evaporator 21, the water inlet and the air inlet of the first evaporator 21 are disposed at the sides of the first evaporator 21, respectively, the first water outlet of the first evaporator 21 is used for concentrated wastewater to flow into the evaporative crystallization module 30, and the second water outlet of the first evaporator 21 is used for primary wastewater to heat and flow back. The first water outlet of the first evaporator 21 is generally disposed at the bottom of the first evaporator 21 so that the concentrated waste water with higher concentration flows out, and the second water outlet of the first evaporator 21 is flush with the liquid level of the first evaporator 21 so that the supernatant liquid with lower concentration flows back.
Specifically, as shown in fig. 1, in an embodiment, the MVR evaporation module 20 further includes a first liquid storage tank 14, the preheating module 10 further includes a fourth heat exchanger 13, a heat source outlet of the second heat exchanger 12 and a heat source outlet of the third heat exchanger 22 are both communicated with a water inlet of the first liquid storage tank 14, a water outlet of the first liquid storage tank 14 is communicated with a heat source inlet of the fourth heat exchanger 13, a part of the primary wastewater flows into a cold source inlet of the fourth heat exchanger 13, another part of the primary wastewater flows into a cold source inlet of the first heat exchanger 11, and a cold source outlet of the fourth heat exchanger 13 and a cold source outlet of the first heat exchanger 11 are both communicated with a cold source inlet of the second heat exchanger 12.
Moreover, the air outlet of the first liquid storage tank 14 is communicated with the air inlet of the first evaporator 21, so that the uncondensed steam in the part of the first liquid storage tank 14 flows back to the first evaporator 21, and the heat required by evaporation is provided for the first evaporator 21.
A first lift pump 16 is arranged between the water outlet of the first liquid storage tank 14 and the heat source inlet of the fourth heat exchanger 13, and the first lift pump 16 provides power for the liquid in the first liquid storage tank 14 to flow into the fourth heat exchanger 13. The salt-containing wastewater crystallization treatment device 100 is further provided with a second lifting pump 17, an inlet of the second lifting pump 17 is used for primary wastewater to flow in, an outlet of the second lifting pump 17 is communicated with a cold source inlet of the first heat exchanger 11 and a cold source inlet of the fourth heat exchanger 13, and the second lifting pump 17 is used for providing power for the primary wastewater to flow in the preheating module 10.
In this embodiment, the cold source pipelines and the heat source pipelines of the first heat exchanger 11, the second heat exchanger 12, the third heat exchanger 22 and the fourth heat exchanger 13 are arranged independently, that is, the temperature of the primary wastewater is increased and the components are unchanged after the primary wastewater is subjected to heat exchange by the first heat exchanger 11, the second heat exchanger 12, the third heat exchanger 22 and the fourth heat exchanger 13.
Specifically, as shown in fig. 1, in an embodiment, the evaporative crystallization module 30 includes a second evaporator 31, the second evaporator 31 is used for performing evaporative crystallization on the concentrated wastewater and generating a solid-liquid mixture, a water inlet of the second evaporator 31 is communicated with a first water outlet of the MVR evaporation module 20, an outlet of the second evaporator 31 is used for discharging the solid-liquid mixture, and a gas outlet of the second evaporator 31 is communicated with a heat source inlet of the first heat exchanger 11.
Specifically, as shown in fig. 1, in an embodiment, the evaporative crystallization module 30 further includes a heat medium heater 33, the second evaporator 31 is an evaporation kettle, a crystallization cavity and a heating cavity are arranged in the second evaporator 31, the heating cavity is arranged around the crystallization cavity, a heat medium is arranged in the heating cavity, the heat medium is used for heating the crystallization cavity, a water inlet of the crystallization cavity is communicated with a first water outlet of the MVR evaporation module 20, an outlet of the crystallization cavity is used for discharging a solid-liquid mixture, an air outlet of the crystallization cavity is communicated with a heat source inlet of the first heat exchanger 11, an outlet of the heating cavity is communicated with an inlet of the heat medium heater 33, and an outlet of the heat medium heater 33 is communicated with an inlet of the heating cavity.
In this embodiment, a circulation pump 32 is provided between the outlet of the heating chamber and the inlet of the heat medium heater 33, so that the heat medium circulates in the heat medium heater 33 and the heating chamber, and the heat medium can continuously provide heat for the crystallization chamber, so that the moisture in the concentrated wastewater is further evaporated.
Specifically, as shown in FIG. 1, in one embodiment, the evaporative crystallization module 30 further comprises a vacuum pump 19, and the vacuum pump 19 is in communication with the crystallization chamber such that the pressure of the crystallization chamber is 18.16kPa to 19.94 kPa. The inlet of the vacuum pump 19 is communicated with the heat source inlet of the first heat exchanger 11, and the heat source inlet of the first heat exchanger 11 is communicated with the air outlet of the second evaporator 31, so that the pressure inside the crystallization cavity can be controlled by the vacuum pump 19, and wastewater with preset salt concentration can be obtained.
Specifically, as shown in fig. 1, in an embodiment, the evaporative crystallization module 30 further includes a solid-liquid separator 34, the solid-liquid separator 34 is used for separating liquid and solid crystallized salt in the solid-liquid mixture, an inlet of the solid-liquid separator 34 is communicated with an outlet of the second evaporator 31, so that the solid-liquid mixture flows into the solid-liquid separator 34, a water outlet of the solid-liquid separator 34 is communicated with a water inlet of the second evaporator 31, and a solid outlet of the solid-liquid separator 34 is used for discharging the solid crystallized salt.
Specifically, the solid-liquid separator 34 is a centrifuge that separates liquid and solid crystalline salts in a solid-liquid mixture by centrifugal force.
Specifically, as shown in fig. 1, in an embodiment, the evaporation and crystallization module 30 further includes a second liquid storage tank 35 and a second reflux pump 36, a water outlet of the solid-liquid separator 34 is communicated with a water inlet of the second liquid storage tank 35, a water outlet of the second liquid storage tank 35 is communicated with an inlet of the second reflux pump 36, and an outlet of the second reflux pump 36 is communicated with a water inlet of the second evaporator 31. The second reflux pump 36 can reflux the liquid in the solid-liquid mixture to the second evaporator 31, and further evaporate and crystallize the liquid.
Specifically, as shown in fig. 1, in an embodiment, the preheating module 10 further includes a third liquid storage tank 15 and a third lift pump 18, the heat source outlet of the first heat exchanger 11 is communicated with the water inlet of the third liquid storage tank 15, the water outlet of the third liquid storage tank 15 is communicated with the inlet of the third lift pump 18, and the outlet of the third lift pump 18 is used for discharging distilled water. Meanwhile, the third liquid storage tank 15 is also provided with a gas outlet communicated with the heat source inlet of the first heat exchanger 11, and the gas outlet of the third liquid storage tank 15 enables uncondensed steam in the third liquid storage tank to further enter the first heat exchanger 11 for heat exchange, so that the heat of the steam is fully utilized, and the waste water treatment cost is saved.
It is noted that the salt in the primary wastewater may be at least one of nitrate and sodium salt.
In this embodiment, the primary wastewater contains sodium nitrate and has an initial temperature of 25-30 ℃. One part of primary wastewater is heated by the first heat exchanger 11, the other part of primary wastewater is heated by the fourth heat exchanger 13, the primary wastewater is converged together after passing through the first heat exchanger 11 and the fourth heat exchanger 13, and then passes through the second heat exchanger 12 for heat exchange, and the temperature of the primary wastewater is 92-94 ℃.
The boiling temperature of the 50-52% sodium nitrate solution is 108-110 ℃ under 101 kPa. In order to obtain concentrated wastewater with the mass concentration of sodium nitrate of 50-52%, the pressure of the first evaporator 21 is set to be 101kPa, the primary wastewater is further heated by the first backflow pump 24 and the third heat exchanger 22 until the temperature of the primary wastewater reaches 108-110 ℃, the primary wastewater is subjected to flash evaporation in the first evaporator 21, so that the concentrated wastewater with the mass concentration of sodium nitrate of 50-52% is obtained by the first evaporator 21, and the temperature of steam generated by the first evaporator 21 is 95-100 ℃.
Under the pressure of 18.16kPa-19.94kPa, the boiling temperature of the 90% -95% sodium nitrate solution is 84 ℃ -86 ℃. Therefore, in order to obtain 90 to 95 percent of solid-liquid mixture, the pressure of the second evaporator 31 is set to be 18.16 to 19.94kPa, the temperature of the concentrated wastewater is 84 to 86 ℃, and the temperature of the steam generated by the second evaporator 31 is 58 to 60 ℃.
In one embodiment, a salt-containing wastewater crystallization treatment method is provided, wherein a salt-containing wastewater treatment device is used, and comprises the following steps:
the preheating module 10 heats the primary wastewater;
the MVR evaporation concentration module is used for carrying out evaporation concentration on the preheated primary wastewater and generating concentrated wastewater, wherein the salt mass concentration of the concentrated wastewater is 50-52%;
the evaporative crystallization module 30 performs evaporative crystallization on the concentrated wastewater in a low-pressure environment, and generates a solid-liquid mixture, wherein the salt mass concentration of the solid-liquid mixture is 90% -95%.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the second feature or the first and second features may be indirectly contacting each other through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The utility model provides a contain salt waste water crystallization processing apparatus which characterized in that includes:
the preheating module is used for heating primary wastewater, the preheating module comprises a first heat exchanger and a second heat exchanger, a cold source inlet of the first heat exchanger is used for allowing the primary wastewater to flow in, and a cold source outlet of the first heat exchanger is communicated with a cold source inlet of the second heat exchanger;
the MVR evaporation module is used for evaporating and concentrating the primary wastewater and generating concentrated wastewater, a water inlet of the MVR evaporation module is communicated with a cold source outlet of the second heat exchanger, an air inlet of the MVR evaporation module is used for allowing boiler steam to flow in, and a heat source inlet of the second heat exchanger is communicated with an air outlet of the MVR evaporation module;
the evaporative crystallization module is used for carrying out low-pressure evaporative crystallization on the concentrated wastewater and generating a solid-liquid mixture, a water inlet of the evaporative crystallization module is communicated with a first water outlet of the MVR evaporative module, so that the concentrated wastewater flows into the evaporative crystallization module, and a heat source inlet of the first heat exchanger is communicated with a gas outlet of the evaporative crystallization module.
2. The salt-containing wastewater crystallization treatment device of claim 1, wherein the MVR evaporation module comprises a first evaporator and a vapor compressor, a cold source outlet of the second heat exchanger is communicated with a water inlet of the first evaporator, a first water outlet of the first evaporator is communicated with a water inlet of the evaporation crystallization module, a gas outlet of the first evaporator is communicated with a gas inlet of the vapor compressor, and a gas outlet of the vapor compressor is communicated with a heat source inlet of the second heat exchanger.
3. The salt-containing wastewater crystallization treatment device according to claim 2, wherein the MVR evaporation module further comprises a first reflux pump and a third heat exchanger, the second water outlet of the first evaporator is communicated with the inlet of the first reflux pump, the outlet of the first reflux pump is communicated with the cold source inlet of the third heat exchanger, the cold source outlet of the third heat exchanger is communicated with the water inlet of the first evaporator, the air outlet of the steam compressor is communicated with the heat source inlet of the third heat exchanger, and the heat source outlet of the third heat exchanger is communicated with the heat source inlet of the second heat exchanger.
4. The saline wastewater crystallization treatment device of claim 3, wherein the MVR evaporation module further comprises a first liquid storage tank, the preheating module further comprises a fourth heat exchanger, a heat source outlet of the second heat exchanger and a heat source outlet of the third heat exchanger are both communicated with a water inlet of the first liquid storage tank, a water outlet of the first liquid storage tank is communicated with a heat source inlet of the fourth heat exchanger, a part of the primary wastewater flows into a cold source inlet of the fourth heat exchanger, another part of the primary wastewater flows into a cold source inlet of the first heat exchanger, and a cold source outlet of the fourth heat exchanger and a cold source outlet of the first heat exchanger are both communicated with a cold source inlet of the second heat exchanger.
5. The salt-containing wastewater crystallization treatment device of claim 1, wherein the evaporative crystallization module comprises a second evaporator, the second evaporator is used for carrying out evaporative crystallization on the concentrated wastewater and generating the solid-liquid mixture, a water inlet of the second evaporator is communicated with a first water outlet of the MVR evaporation module, an outlet of the second evaporator is used for discharging the solid-liquid mixture, and a gas outlet of the second evaporator is communicated with a heat source inlet of the first heat exchanger.
6. The brine wastewater crystallization treatment device according to claim 5, wherein the evaporation crystallization module further comprises a heat medium heater, the second evaporator is an evaporation kettle, a crystallization cavity and a heating cavity are arranged in the second evaporator, the heating cavity is arranged around the crystallization cavity, a heat medium is arranged in the heating cavity, the heat medium is used for heating the crystallization cavity, a water inlet of the crystallization cavity is communicated with the first water outlet of the MVR evaporation module, an outlet of the crystallization cavity is used for discharging the solid-liquid mixture, a gas outlet of the crystallization cavity is communicated with the heat source inlet of the first heat exchanger, an outlet of the heating cavity is communicated with an inlet of the heat medium heater, and an outlet of the heat medium heater is communicated with an inlet of the heating cavity.
7. The saline wastewater crystallization treatment device according to claim 6, characterized in that the evaporation and crystallization module further comprises a vacuum pump, and the vacuum pump is communicated with the crystallization cavity, so that the pressure of the crystallization cavity is 18.16kPa-19.94 kPa.
8. The salt-containing wastewater crystallization treatment device according to claim 5, wherein the evaporative crystallization module further comprises a solid-liquid separator for separating liquid and solid crystallized salt in the solid-liquid mixture, an inlet of the solid-liquid separator is communicated with an outlet of the second evaporator, a water outlet of the solid-liquid separator is communicated with a water inlet of the second evaporator, and a solid outlet of the solid-liquid separator is used for discharging the solid crystallized salt.
9. The saline wastewater crystallization treatment device of claim 8, wherein the evaporative crystallization module further comprises a second liquid storage tank and a second reflux pump, the water outlet of the solid-liquid separator is communicated with the water inlet of the second liquid storage tank, the water outlet of the second liquid storage tank is communicated with the inlet of the second reflux pump, and the outlet of the second reflux pump is communicated with the water inlet of the second evaporator.
10. A method for treating salt-containing wastewater by crystallization, which is characterized by using the salt-containing wastewater treatment device of any one of claims 1 to 9, and comprises the following steps:
the preheating module heats the primary wastewater;
the MVR evaporation concentration module is used for carrying out evaporation concentration on the preheated primary wastewater and generating concentrated wastewater, wherein the salt mass concentration of the concentrated wastewater is 50-52%;
and the evaporative crystallization module carries out evaporative crystallization on the concentrated wastewater in a low-pressure environment and generates a solid-liquid mixture, wherein the salt mass concentration of the solid-liquid mixture is 90-95%.
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| CN214971877U (en) * | 2021-04-29 | 2021-12-03 | 温州联康蒸发器有限公司 | Vacuum heat pump evaporation crystallizer |
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