CN106629936B - Process and system for treating wastewater - Google Patents
Process and system for treating wastewater Download PDFInfo
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- CN106629936B CN106629936B CN201510729878.3A CN201510729878A CN106629936B CN 106629936 B CN106629936 B CN 106629936B CN 201510729878 A CN201510729878 A CN 201510729878A CN 106629936 B CN106629936 B CN 106629936B
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Abstract
The invention provides a process and a system for treating wastewater. The invention also provides a process for treating wastewater by using the system, and the wastewater treatment process and the system have the advantages of safety, reliability, simple equipment, low operation cost, obvious energy-saving effect and the like, and can realize 50-95% of water resource recycling.
Description
Technical Field
The invention relates to the technical field of environmental protection and energy conservation, in particular to a method and a device for concentrating and treating wastewater containing salt and high molecular organic matters.
Background
The high-salt-content wastewater refers to wastewater with the total salt content TDS being more than or equal to 1 percent and generally belongs to refractory wastewater. The common high salinity wastewater mainly comes from wastewater discharged by replacing seawater, industrial production wastewater and the like. The desalting treatment process of the high-salt-content wastewater mainly comprises an electrodialysis method, a reverse osmosis method, an ion exchange method and an evaporation method. The organic wastewater mainly comes from the fields of chemical industry, road deicing, food processing and the like, and also comprises printing and dyeing wastewater, petroleum exploitation and processing wastewater, papermaking wastewater, pesticide industry wastewater and the like. The total amount of high-salt organic wastewater is huge and increasing year by year. If the wastewater is not treated before being discharged, high-concentration soluble inorganic salts and refractory toxic organic matters in the wastewater can cause serious environmental pollution and damage to soil, surface water and underground water. Therefore, in the present day when water resources are in short supply, research and development of effective high-salt organic wastewater treatment technology are necessary.
In recent years, the treatment of recycled wastewater by mechanical vapor recompression evaporation technology has been proposed abroad. The mechanical vapor recompression technology is an advanced energy-saving technology for reducing the demand on external energy. The energy-saving principle is as follows: the secondary steam generated in the system is compressed by the compressor, so that the pressure, the temperature and the enthalpy value of the secondary steam are increased, an external heat source which is required to be adopted in the original system is replaced, and the latent heat of the secondary steam is fully utilized, thereby achieving the purpose of saving energy in the technical process. At present, the mechanical vapor recompression system is mainly applied to the recovery and treatment of wastewater containing salt, oilfield reinjection water, pharmaceutical wastewater and the like.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a process and a system for treating wastewater, and the process and the system for treating wastewater have the advantages of safety, reliability, simple equipment, low operation cost, obvious energy-saving effect and the like.
The invention provides a system for treating wastewater, which comprises a wastewater preheater, a first-effect evaporator, a second-effect evaporator, a steam compressor, a condensed water collector and a non-condensable gas compressor, wherein the first-effect evaporator is connected with the second-effect evaporator; wherein the waste water feed line is connected with the waste water inlet of the first-effect evaporator through the waste water preheater, the steam outlet of the first-effect evaporator is connected with the inlet of the steam compressor, the outlet of the steam compressor is connected with the heat source steam inlet of the second-effect evaporator, the gas phase outlet of the second-effect evaporator is connected with the heat source steam inlet of the first-effect evaporator, the non-condensable gas outlet of the first-effect evaporator is connected with the auxiliary steam inlet of the second-effect evaporator through the non-condensable gas compressor, the concentrated solution discharge port at the bottom of the first-effect evaporator is connected with the feed inlet of the second-effect evaporator through a pipeline, the concentrated solution outlet at the bottom of the second-effect evaporator is connected with the waste water preheater through a pipeline, the condensed water discharge port of the first-effect evaporator and the condensed water discharge port of the second-effect evaporator are.
In the system for treating wastewater, a steam supplementing pipeline is arranged on a connecting pipeline between the steam outlet of the first-effect evaporator and the inlet of the steam compressor.
In the system for treating wastewater, a non-condensable gas supplementing pipeline is arranged on a connecting pipeline between a non-condensable gas outlet of the first-effect evaporator and an inlet of the non-condensable gas compressor.
In the system for treating wastewater of the present invention, the non-condensable gas compressor may be a displacement compressor, a turbine compressor or a thermal compressor.
In the system for treating wastewater, the vapor compressor can adopt any one of a centrifugal compressor, a screw compressor, a reciprocating compressor and a high-pressure centrifugal fan; the compression ratio of the steam compressor is 1.3-2.0, preferably 1.4-1.7.
In the system for treating wastewater, the wastewater preheater can adopt a shell-and-tube heat exchanger, a heat pipe type heat exchanger, a plate type heat exchanger or a plate-and-shell type heat exchanger, and preferably adopts a plate type heat exchanger.
In the system for treating wastewater, the one-effect evaporator can adopt any one of a climbing-film evaporator, a falling-film evaporator, a horizontal tube evaporator and a plate evaporator.
In the system for treating wastewater, the specific structure of the double-effect evaporator is as follows, the double-effect evaporator comprises an upper end enclosure, a shell and a lower end enclosure, the upper end enclosure is provided with a gas outlet, the lower end enclosure is provided with a concentrated solution outlet, and the shell comprises a gas-liquid separation section, a material distribution section, an evaporation section and a liquid storage section according to the flowing direction of liquid-phase materials; the material distribution section comprises a shell, and is characterized in that a feed inlet is formed in the shell above the material distribution section, the evaporation section comprises an upper tube plate, an evaporation tube, a lower tube plate and a support plate, the upper tube plate and the lower tube plate are fixed on the inner wall of the shell, the evaporation tube penetrates through the upper tube plate and the lower tube plate, the evaporation tube is vertically arranged in the evaporation section, the support plate is arranged below the lower tube plate, the lower tube plate is fixedly connected with the support plate, a heating steam inlet and a condensate outlet are formed in the shell of the evaporation section, and an auxiliary steam inlet is formed in the shell of the liquid storage.
In the above-mentioned two-effect evaporator, be equipped with the defogging facility in the gas-liquid separation section, specifically can be any one of wire mesh defroster, fibre defroster and baffling board defroster.
In the above two-effect evaporator, the feed inlet is connected with a feed pipe, the feed pipe is connected with a feed distributor, and the feed distributor can be a pipe type, a double-layer calandria type, a groove type, a disc type, an impact type, a nozzle type, a tower type, a lotus seed type, a combined type and the like.
In the above two-effect evaporator, the evaporation tube is filled with a filler, which may be a ceramic material or a metal material, preferably a ceramic material; the shape of the filler can be Raschig ring, pall ring, ladder ring, honeycomb or wolf tooth rod.
In the above-mentioned two-effect evaporator, evaporation zone and stock solution section fixed connection specifically can adopt flange joint, the backup pad is located in the middle of the flange joint.
In the above two-effect evaporator, the support plate is provided with a plurality of holes, the diameter of the holes is smaller than that of the filler in the evaporation tube, and the diameter of the holes is 2 mm-5 mm.
In the above-mentioned two-effect evaporator, backup pad and the lower tube sheet fixed connection of evaporation zone lean on the flange in close contact with of evaporation zone and stock solution section, through dismantling the flange of evaporation zone and stock solution section, can loosen backup pad and lower tube sheet to convenient to dismantle and change and pack.
In the above-mentioned two-effect evaporator, the described material distribution section is equipped with filling material, and the described filling material can be identical to filling material in the evaporation tube.
In the above-mentioned two-effect evaporator, the auxiliary steam may be air, nitrogen, steam, etc., preferably steam.
In the double-effect evaporator, the height of the material distribution section is 1-1.5 times of the diameter of the material distribution section.
In the double-effect evaporator, the height of the gas-liquid separation section is 1-1.5 times of the diameter of the gas-liquid separation section.
In the above-mentioned two-effect evaporator, the height of stock solution section is 1~2 times of stock solution section diameter.
In the double-effect evaporator, non-condensable gas enters the double-effect evaporator from the auxiliary steam inlet of the double-effect evaporator, flows through the evaporation tube in the double-effect evaporator, and is subjected to mass and heat transfer with waste water from top to bottom, and meanwhile, the updating speed of the waste water on the filler is increased under the disturbance of the non-condensable gas in the evaporation tube, so that a liquid film is formed to flow, and the heat transfer speed of the evaporation tube is increased. The steam generated by evaporation in the evaporation tube and the non-condensable gas are discharged from a gas outlet at the top of the double-effect evaporator together. Heating steam enters the double-effect evaporator through the steam inlet, is condensed into condensed water on the outer side of the evaporation pipe and is discharged out of the double-effect evaporator through the condensate outlet. And the wastewater enters the double-effect evaporator from a feed liquid inlet at the upper part of the double-effect evaporator, and the concentrated solution is discharged from a feed liquid outlet at the bottom of the double-effect evaporator.
The invention also provides a process for treating wastewater, which adopts the device and comprises the following steps:
the method comprises the following steps of (1) using a waste water preheater for treating raw material waste water, condensed water and concentrated solution of a stripping tower, wherein the raw material waste water, the condensed water and the concentrated solution of the stripping tower exchange heat in the waste water preheater to obtain preheated raw material waste water, cooled condensed water and cooled concentrated solution;
using a one-effect evaporator for treating raw material wastewater preheated by a wastewater preheater to obtain a 1 st material flow of a gas phase, a 2 nd material flow of a liquid phase, non-condensable gas and condensed water;
using a vapor compressor for treating the 1 st stream from the one-effect evaporator to obtain a 3 rd stream in a vapor phase;
using a non-condensable gas compressor, treating the non-condensable gas from the first-effect evaporator to obtain a 4 th material flow of a gas phase;
using a second effect evaporator for treating a 2 nd stream from the first effect evaporator, a 3 rd stream from the vapor compressor, and a 4 th stream from the non-condensable gas compressor to obtain a 5 th stream in a vapor phase, a 6 th stream in a liquid phase, and condensed water;
a condensate collector is used for receiving condensate from the first effect evaporator and the second effect evaporator.
In the process for treating the wastewater, the raw material wastewater enters a first-effect evaporator after being subjected to heat exchange with condensed water and concentrated solution in a wastewater preheater to reach a temperature close to saturation temperature, the raw material wastewater is evaporated in the first-effect evaporator, the obtained steam is compressed by a steam compressor, the latent heat of the steam is increased, and the compressed steam is used as a heat evaporation source of a second-effect evaporator. Concentrated solution at the bottom of the first-effect evaporator enters a second-effect evaporator to be evaporated, and non-condensable gas is introduced into the second-effect evaporator to serve as auxiliary steam, so that the mass and heat transfer efficiency of the second-effect evaporator is improved. The steam evaporated in the secondary evaporator and the introduced non-condensable gas are mixed and enter the primary evaporator to serve as a heating source of the primary evaporator, the steam is condensed into condensed water, the non-condensable gas enters the non-condensable gas compressor from a non-condensable gas outlet of the primary evaporator to be compressed, and the compressed non-condensable gas circularly enters the secondary evaporator. Concentrated solution at the bottom of the second-effect evaporator enters a waste water preheater to exchange heat with waste water to recover heat.
In the process for treating the wastewater, the raw material wastewater is preheated to 90-102 ℃, preferably 95-100 ℃ in a wastewater preheater and then enters a one-effect evaporator.
In the process for treating wastewater, the logarithmic heat exchange temperature difference between steam and wastewater in the first-effect evaporator and the second-effect evaporator is 3-10 ℃, preferably 4-8 ℃, and meanwhile, the vaporization rate of wastewater evaporation in the first-effect evaporator and the second-effect evaporator is 5-50%, preferably 10-40%.
In the process for treating the wastewater, when a system is started, steam outside the system is required to be used as a heat source for starting the system, and the steam can be introduced into the system through a steam supplementing pipeline; if the steam generated in the system during the operation process can not maintain the steam quantity consumed by the system heat, the steam can be introduced through a steam replenishing pipeline; if the steam generated during operation of the system is greater than the amount of steam consumed to maintain system heat, the excess steam may be removed from the system via a make-up steam line.
In the process for treating the wastewater, the non-condensable gas outside the system is required to be used as an evaporation heat source of the double-effect evaporator during the system starting. The non-condensable gas may be air, nitrogen, oxygen, or the like.
In the wastewater treatment process, the one-effect evaporator can be any one of a rising-film evaporator, a falling-film evaporator, a horizontal tube evaporator and a plate evaporator.
In the process for treating wastewater, the double-effect evaporator has the specific structure that the double-effect evaporator comprises an upper end enclosure, a shell and a lower end enclosure, wherein the upper end enclosure is provided with a gas outlet, the lower end enclosure is provided with a concentrated solution outlet, and the shell comprises a gas-liquid separation section, a material distribution section, an evaporation section and a liquid storage section according to the flowing direction of liquid-phase materials; the material distribution section comprises a shell, and is characterized in that a feed inlet is formed in the shell above the material distribution section, the evaporation section comprises an upper tube plate, an evaporation tube, a lower tube plate and a support plate, the upper tube plate and the lower tube plate are fixed on the inner wall of the shell, the evaporation tube penetrates through the upper tube plate and the lower tube plate, the evaporation tube is vertically arranged in the evaporation section, the support plate is arranged below the lower tube plate, the lower tube plate is fixedly connected with the support plate, a heating steam inlet and a condensate outlet are formed in the shell of the evaporation section, and an auxiliary steam inlet is formed in the shell of the liquid storage.
In the above-mentioned two-effect evaporator, be equipped with the defogging facility in the gas-liquid separation section, specifically can be any one of wire mesh defroster, fibre defroster and baffling board defroster.
In the above two-effect evaporator, the feed inlet is connected with a feed pipe, the feed pipe is connected with a feed distributor, and the feed distributor can be a pipe type, a double-layer calandria type, a groove type, a disc type, an impact type, a nozzle type, a tower type, a lotus seed type, a combined type and the like.
In the above two-effect evaporator, the evaporation tube is filled with a filler, which may be a ceramic material or a metal material, preferably a ceramic material; the shape of the filler can be Raschig ring, pall ring, ladder ring, honeycomb or wolf tooth rod.
In the above-mentioned two-effect evaporator, evaporation zone and stock solution section fixed connection specifically can adopt flange joint, the backup pad is located in the middle of the flange joint.
In the above two-effect evaporator, the support plate is provided with a plurality of holes, the diameter of the holes is smaller than that of the filler in the evaporation tube, and the diameter of the holes is 2 mm-5 mm.
In the above-mentioned two-effect evaporator, backup pad and the lower tube sheet fixed connection of evaporation zone lean on the flange in close contact with of evaporation zone and stock solution section, through dismantling the flange of evaporation zone and stock solution section, can loosen backup pad and lower tube sheet to convenient to dismantle and change and pack.
In the above-mentioned two-effect evaporator, the described material distribution section is equipped with filling material, and the described filling material can be identical to filling material in the evaporation tube.
In the above-mentioned two-effect evaporator, the auxiliary steam may be air, nitrogen, steam, etc., preferably steam.
In the double-effect evaporator, the height of the material distribution section is 1-1.5 times of the diameter of the material distribution section.
In the double-effect evaporator, the height of the gas-liquid separation section is 1-1.5 times of the diameter of the gas-liquid separation section.
In the above-mentioned two-effect evaporator, the height of stock solution section is 1~2 times of stock solution section diameter.
In the double-effect evaporator, non-condensable gas enters the evaporator from the auxiliary steam inlet at the lower part of the double-effect evaporator, flows through the evaporation pipe in the evaporator, and is subjected to mass and heat transfer with waste water from top to bottom, and meanwhile, under the disturbance of auxiliary steam in the evaporation pipe, the updating speed of the waste water on the filler is increased, so that a liquid film is formed to flow, and the heat transfer speed of the evaporation pipe is increased. The steam generated by evaporation in the evaporation tube and the non-condensable gas are discharged from a gas outlet at the top of the evaporator together. The heating steam enters the evaporator through the steam inlet, is condensed into condensed water outside the evaporation pipe and is discharged out of the evaporator through the condensed liquid outlet. The waste water enters the evaporator through a feed liquid inlet at the upper part of the evaporator, and the concentrated solution is discharged from a feed liquid outlet at the bottom of the evaporator.
In the wastewater treatment process, the vapor compressor can adopt any one of a centrifugal compressor, a screw compressor, a reciprocating compressor and a high-pressure centrifugal fan; the compression ratio of the compressor is 1.3-2.0, preferably 1.4-1.7.
Other techniques in the process of the present invention for treating wastewater, such as water pumping, heat exchange, condensate collection, etc., are well known to those skilled in the art.
Compared with the prior art, the process and the system for treating the wastewater have the following advantages:
1. in the process and the system for treating the wastewater, the wastewater is evaporated, concentrated and recovered by adopting a double-effect steam mechanical recompression process, so that 50-95% of water resources can be recycled.
2. In the process and the system for treating the wastewater, the compressed noncondensable gas is introduced into the evaporation pipe of the two-effect evaporator, so that the evaporation heat transfer coefficient in the evaporation pipe is improved, the heat transfer of an evaporation system is facilitated, the effective heat exchange area of the two-effect evaporator is reduced, and the equipment investment is saved.
3. In the process and the system for treating the wastewater, the filler is added in the evaporation tube in the double-effect evaporator, so that the heat transfer area between the wastewater in the evaporation tube and the heating steam outside the evaporation tube is increased, the turbulent boiling degree of the wastewater in the evaporation tube is increased under the impact of the countercurrent non-condensable gas, and the mass transfer and heat transfer of an evaporation system are promoted.
4. In the process and the system for treating the wastewater, the concentration ratio of the wastewater in the first-effect evaporator is controlled, the wastewater is prevented from scaling in the first-effect evaporator, the concentrated solution is further concentrated in the second-effect evaporator, auxiliary steam and filler are introduced into the evaporation pipe of the second-effect evaporator, and the scaling on the inner wall of the evaporation pipe can be reduced to influence heat transfer in the concentration process of the wastewater in the second-effect evaporator, so that the scaling is generated on the filler, and meanwhile, the filler can be detached, and the scaling of the evaporation system is convenient to clean.
5. The process and the system for treating the wastewater have the characteristics of safety, reliability, simple equipment, low investment and the like.
Drawings
FIG. 1 is a schematic diagram of a process and system for treating wastewater in accordance with the present invention.
FIG. 2 is a schematic diagram of a dual effect evaporator for use with the present invention.
Detailed Description
The following examples further illustrate specific aspects of the present invention, but are not limited to the following examples.
As shown in fig. 1, the system for treating wastewater according to the present invention comprises a wastewater preheater 2, a one-effect evaporator 5, a two-effect evaporator 11, a vapor compressor 8, a condensed water collector 20 and a non-condensable gas compressor 14; wherein the wastewater feeding pipeline is connected with the wastewater inlet of the first-effect evaporator 5 through the wastewater preheater 2, the steam outlet of the first-effect evaporator 5 is connected with the inlet of the steam compressor 8, the steam outlet of the first-effect evaporator is connected with the inlet connecting pipeline of the steam compressor through a steam replenishing pipeline, the outlet of the steam compressor 8 is connected with the heat source steam inlet of the second-effect evaporator 11, the gas phase outlet of the second-effect evaporator 11 is connected with the heat source steam inlet of the first-effect evaporator 5, the non-condensable gas outlet of the first-effect evaporator 5 is connected with the auxiliary steam inlet of the second-effect evaporator 11 through the non-condensable gas compressor 14, the non-condensable gas replenishing pipeline 23 is arranged on the non-condensable gas outlet of the first-effect evaporator 5 and the inlet connecting pipeline of the non-condensable gas compressor 14, the concentrated solution discharge outlet at the bottom of the first-effect evaporator 5 is connected with the feed inlet of the second-effect evaporator 11 through a pipeline, and the concentrated, the condensed water discharge port of the first-effect evaporator 5 and the condensed water discharge port of the second-effect evaporator 11 are connected with a condensed water collector 20 through pipelines, and the discharge port of the condensed water collector 20 is connected with the waste water preheater 2.
The invention also provides a process for treating wastewater, which adopts the device and comprises the following steps:
using a waste water preheater 2 for treating raw material waste water 1, condensed water 21 and a double-effect evaporator concentrated solution 15, wherein the raw material waste water 1, the condensed water 21 and the double-effect evaporator concentrated solution 15 exchange heat in the waste water preheater 2 to obtain preheated raw material waste water 3, cooled condensed water 22 and a cooled concentrated solution 17;
using a one-effect evaporator 5 for treating raw wastewater 3 preheated by a wastewater preheater 2 to obtain a 1 st material flow 6 in a gas phase, a 2 nd material flow 10 in a liquid phase, a non-condensable gas 13 and condensed water 18;
using a vapor compressor 8 for treating the 1 st stream 6 from the one-effect evaporator to obtain a 3 rd stream 9 in the vapor phase;
using a non-condensable gas compressor 14 for treating the non-condensable gas 13 from the first effect evaporator to obtain a 4 th stream 16 in the gas phase;
using a second effect evaporator 11 for treating a 2 nd stream 10 from the first effect evaporator, a 3 rd stream 9 from the vapor compressor, and a 4 th stream 16 from the non-condensable gas compressor, resulting in a 5 th stream 12 in the vapor phase, a 6 th stream 15 in the liquid phase, and condensed water 19 after treatment;
a condensate collector 20 is used for receiving the condensate 18 of the first effect evaporator and the condensate 19 of the second effect evaporator, and mixed condensate 21 is obtained after collection.
In the process for treating the wastewater, when a system is started, steam and non-condensable gas outside the system are required to be used as a heat source for starting the system, and the steam 7 can be introduced into the system through a steam supplementing pipeline; if the steam generated in the system during the operation process can not maintain the steam quantity consumed by the system heat, the steam 7 can be introduced through a steam replenishing pipeline; if the steam generated during operation of the system is greater than the amount of steam consumed to maintain system heat, the excess steam may be removed from the system via a make-up steam line. The desired non-condensable gasses 4 may be introduced into the system by a non-condensable gas make-up line.
In the process, raw material wastewater 1 enters a first-effect evaporator 5 after exchanging heat with condensed water 21 and concentrated solution 15 in a wastewater preheater 2 to reach a temperature close to saturation temperature, the raw material wastewater is evaporated in the first-effect evaporator 5, the obtained steam 6 is compressed by a steam compressor 8, the latent heat of the steam is increased, and the compressed steam 9 is used as an evaporation heat source of a second-effect evaporator 11. Concentrated solution 10 at the bottom of the first-effect evaporator 5 enters a second-effect evaporator 11 for evaporation, and non-condensable gas is introduced into the second-effect evaporator 11, so that the mass and heat transfer efficiency of the second-effect evaporator 11 is improved. The mixed gas 12 of steam and non-condensable gas evaporated in the secondary evaporator 11 enters the primary evaporator 5 to be used as a heating source of the primary evaporator 5, the steam is condensed into condensed water 18, the non-condensable gas 13 enters a non-condensable gas compressor 14 from a non-condensable gas outlet of the primary evaporator 5 for compression, and the compressed non-condensable gas circularly enters the secondary evaporator 11. Concentrated solution at the bottom of the second-effect evaporator 11 enters a waste water preheater 2 to exchange heat with waste water to recover heat.
As shown in fig. 2, the two-effect evaporator has a structure that the two-effect evaporator comprises an upper end enclosure 1, a shell 2 and a lower end enclosure 3, wherein the upper end enclosure 1 is provided with a gas outlet 4, the lower end enclosure 3 is provided with a concentrated solution outlet 5, and the shell 2 comprises a gas-liquid separation section 6, a material distribution section 7, an evaporation section 8 and a liquid storage section 9 according to the flowing direction of liquid-phase materials; the gas-liquid separation section 6 is provided with a fiber demister 20, a feed inlet 16 is arranged on the shell above the material distribution section 7, the feed inlet is connected with a feed pipe 17, the feed pipe 17 is connected with a feed distributor 19, the evaporation section 8 comprises an upper tube plate 10, evaporation tubes 11 and a lower tube plate 12, the upper tube plate 10 and the lower tube plate 12 are fixed on the inner wall of the shell, the evaporation tubes 11 penetrate through the upper tube plate 10 and the lower tube plate 12, the evaporation tubes 11 are vertically arranged in the evaporation section 8, the evaporation tubes 11 are filled with filling materials, the filling materials are ceramic materials, the filling materials are pall rings, a support plate 18 is arranged below the lower tube plate 12, a plurality of holes are formed in the support plate 18, the diameter of each hole is smaller than that of the filling materials in the evaporation tubes 11, and the diameter of each hole is 3 mm. Be equipped with heating steam entry 13 and condensate outlet 14 on evaporation zone 8's the casing, be equipped with auxiliary steam entry 15 on the liquid storage section 9 casing, evaporation zone 8 adopts flange fixed connection with liquid storage section 9, backup pad 18 is located in the middle of the flange joint, backup pad 18 leans on evaporation zone 8 and liquid storage section 9's flange in close contact with evaporation zone 8's lower tube sheet 12, through dismantling the flange of evaporation zone 8 with liquid storage section 9, can loosen backup pad 18 and lower tube sheet 12 to it packs to be convenient for dismantle the change. The material distribution section 7 is internally provided with a filler, and the filler can be uniformly filled in the evaporation tube 11. The height of the material distribution section 7 is 1.5 times of the diameter of the material distribution section 7. The height of the gas-liquid separation section 6 is 1.5 times of the diameter of the gas-liquid separation section 6. The height of the liquid storage section 9 is 2 times of the diameter of the liquid storage section 9.
Example 1
The system of figure 1 is adopted, the structure of figure 2 is adopted in the double-effect evaporator, the used wastewater is ammonium sulfate wastewater, the concentration of the raw material wastewater is 20wt%, the treatment capacity of the raw material wastewater is 15t/h, the normal temperature wastewater is preheated to 99 ℃ through the preheater 2 and enters the single-effect evaporator 5, the compression ratio of the steam compressor 8 is 1.5, and air is used as non-condensable gas. The concentration of the concentrated solution 10 discharged from the bottom of the first-effect evaporator 5 is 32wt%, and the concentration of the concentrated solution 15 discharged after the concentrated solution 10 is evaporated and concentrated by the second-effect evaporator is 45 wt%. The temperature of the condensed water 21 after heat recovery is about 45 ℃, and the recovery amount of the condensed water is 8.3 t/h.
Claims (35)
1. A system for treating wastewater, the system comprising a wastewater preheater, a first effect evaporator, a second effect evaporator, a vapor compressor, a condensate collector and a non-condensable gas compressor; wherein the wastewater feeding pipeline is connected with the wastewater inlet of the first-effect evaporator through the wastewater preheater, the steam outlet of the first-effect evaporator is connected with the inlet of the steam compressor, the outlet of the steam compressor is connected with the heat source steam inlet of the second-effect evaporator, the gas phase outlet of the second-effect evaporator is connected with the heat source steam inlet of the first-effect evaporator, the non-condensable gas outlet of the first-effect evaporator is connected with the auxiliary steam inlet of the second-effect evaporator through the non-condensable gas compressor, the concentrated solution discharge outlet at the bottom of the first-effect evaporator is connected with the feed inlet of the second-effect evaporator through a pipeline, the concentrated solution outlet at the bottom of the second-effect evaporator is connected with the wastewater preheater through a pipeline, the condensed water discharge outlet of the first-effect evaporator and the condensed water discharge outlet of the second-effect evaporator are connected with the condensed water collector through pipelines, the discharge outlet of the, the double-effect evaporator comprises an upper end enclosure, a shell and a lower end enclosure, wherein the upper end enclosure is provided with a gas outlet, the lower end enclosure is provided with a concentrated solution outlet, and the shell comprises a gas-liquid separation section, a material distribution section, an evaporation section and a liquid storage section according to the flowing direction of liquid-phase materials; the material distribution section is characterized in that a feed inlet is formed in the shell above the material distribution section, the evaporation section comprises an upper tube plate, an evaporation tube, a lower tube plate and a support plate, a heat source steam inlet and a condensate outlet are formed in the shell of the evaporation section, and an auxiliary steam inlet is formed in the shell of the liquid storage section.
2. The system of claim 1, wherein: and a steam supplementing pipeline is arranged on a connecting pipeline between the steam outlet of the first-effect evaporator and the inlet of the steam compressor.
3. The system of claim 1, wherein: and a non-condensable gas supplementing pipeline is arranged on a non-condensable gas outlet of the first-effect evaporator and an inlet connecting pipeline of the non-condensable gas compressor.
4. The system of claim 1, wherein: the non-condensable gas compressor is a volume type compressor, a turbine type compressor or a thermal type compressor.
5. The system of claim 1, wherein: the vapor compressor adopts any one of a centrifugal compressor, a screw compressor, a reciprocating compressor and a high-pressure centrifugal fan.
6. The system of claim 5, wherein: the compression ratio of the steam compressor is 1.3-2.0.
7. The system of claim 1, wherein: the waste water preheater adopts a shell-and-tube heat exchanger, a heat pipe type heat exchanger, a plate type heat exchanger or a plate-and-shell type heat exchanger.
8. The system of claim 1, wherein: the first-effect evaporator adopts any one of a climbing film evaporator, a falling film evaporator, a horizontal tube evaporator and a plate evaporator.
9. The system of claim 1, wherein: the upper tube plate and the lower tube plate are fixed on the inner wall of the shell, the evaporation tubes penetrate through the upper tube plate and the lower tube plate, the evaporation tubes are vertically arranged in the evaporation section, the supporting plate is arranged below the lower tube plate, and the lower tube plate is fixedly connected with the supporting plate.
10. The system of claim 1, wherein: and a demisting facility is arranged in the vapor-liquid separation section, and the demisting facility is any one of a wire mesh demister, a fiber demister and a baffle plate demister.
11. The system of claim 1, wherein: the feed inlet is connected with the inlet pipe, be connected with the feeding distributor on the inlet pipe.
12. The system of claim 9, wherein: the evaporation tube is filled with a filler, and the filler is made of ceramic materials or metal materials.
13. The system of claim 12, wherein: the filler is in the shape of a Raschig ring, a pall ring, a stepped ring, a honeycomb or a wolf tooth rod.
14. The system of claim 9, wherein: the evaporation section is fixedly connected with the liquid storage section through a flange, and the support plate is located in the middle of the flange.
15. The system of claim 9, wherein: the support plate is provided with a plurality of holes, and the diameter of each hole is smaller than that of the filler in the evaporation tube.
16. The system of claim 9, wherein: and the material distribution section is internally provided with a filler, and the filler is consistent with the filler in the evaporation tube.
17. The system of claim 1, wherein: the height of the material distribution section is 1-1.5 times of the diameter of the material distribution section, the height of the vapor-liquid separation section is 1-1.5 times of the diameter of the vapor-liquid separation section, and the height of the liquid storage section is 1-2 times of the diameter of the liquid storage section.
18. A process for treating wastewater using the system of any one of claims 1-17, the process comprising:
the method comprises the following steps of (1) using a waste water preheater for treating raw material waste water, condensed water and a concentrated solution of a double-effect evaporator, wherein the raw material waste water, the condensed water and the concentrated solution of the double-effect evaporator exchange heat in the waste water preheater to obtain the preheated raw material waste water, the cooled condensed water and the cooled concentrated solution;
using a one-effect evaporator for treating raw material wastewater preheated by a wastewater preheater to obtain a 1 st material flow of a gas phase, a 2 nd material flow of a liquid phase, non-condensable gas and condensed water;
using a vapor compressor for treating the 1 st stream from the one-effect evaporator to obtain a 3 rd stream in a vapor phase;
using a non-condensable gas compressor, treating the non-condensable gas from the first-effect evaporator to obtain a 4 th material flow of a gas phase;
using a second effect evaporator for treating a 2 nd stream from the first effect evaporator, a 3 rd stream from the vapor compressor, and a 4 th stream from the non-condensable gas compressor to obtain a 5 th stream in a vapor phase, a 6 th stream in a liquid phase, and condensed water;
a condensate collector is used for receiving condensate from the first effect evaporator and the second effect evaporator.
19. The process of claim 18, wherein: the raw material wastewater enters a one-effect evaporator after heat exchange in a wastewater preheater to 90-102 ℃.
20. The process of claim 18, wherein: the logarithmic heat exchange temperature difference between the steam and the wastewater in the first-effect evaporator and the second-effect evaporator is 3-10 ℃.
21. The process of claim 20, wherein: the logarithmic heat exchange temperature difference between the steam and the wastewater in the first-effect evaporator and the second-effect evaporator is 4-8 ℃.
22. The process of claim 18, wherein: the vaporization rate of the waste water in the first-effect evaporator and the second-effect evaporator is 5-50%.
23. The process of claim 18, wherein: when the system is started, steam outside the system is used as a heat source for starting the system, and the steam is introduced into the system through a steam supplementing pipeline; if the steam generated in the system in the operation process can not maintain the steam quantity consumed by the system heat, introducing the steam through a steam replenishing pipeline; if the steam generated during operation of the system is greater than the amount of steam consumed to maintain the system heat, the excess steam is removed from the system via the make-up steam line.
24. The process of claim 18, wherein: when the system is started, non-condensable gas outside the system is required to be used as an evaporation heat source of the two-effect evaporator.
25. The process of claim 24, wherein: the non-condensable gas is air, nitrogen or oxygen.
26. The process of claim 18, wherein: the first-effect evaporator adopts any one of a climbing film evaporator, a falling film evaporator, a horizontal tube evaporator and a plate evaporator.
27. The process of claim 18, wherein: the double-effect evaporator has the following specific structure that the double-effect evaporator comprises an upper end enclosure, a shell and a lower end enclosure, wherein the upper end enclosure is provided with a gas outlet, the lower end enclosure is provided with a concentrated solution outlet, and the shell comprises a gas-liquid separation section, a material distribution section, an evaporation section and a liquid storage section according to the flowing direction of liquid-phase materials; the material distribution section comprises a shell, and is characterized in that a feed inlet is formed in the shell above the material distribution section, the evaporation section comprises an upper tube plate, an evaporation tube, a lower tube plate and a support plate, the upper tube plate and the lower tube plate are fixed on the inner wall of the shell, the evaporation tube penetrates through the upper tube plate and the lower tube plate, the evaporation tube is vertically arranged in the evaporation section, the support plate is arranged below the lower tube plate, the lower tube plate is fixedly connected with the support plate, a heating steam inlet and a condensate outlet are formed in the shell of the evaporation section, and an auxiliary steam inlet is formed in the shell of the liquid storage.
28. The process of claim 27, wherein: and a demisting facility is arranged in the vapor-liquid separation section, and the demisting facility is any one of a wire mesh demister, a fiber demister and a baffle plate demister.
29. The process of claim 27, wherein: the feed inlet is connected with the inlet pipe, be connected with the feeding distributor on the inlet pipe.
30. The process of claim 27, wherein: the evaporation tube is filled with a filler, and the filler is made of ceramic materials or metal materials.
31. The process of claim 30, wherein: the filler is in the shape of a Raschig ring, a pall ring, a stepped ring, a honeycomb or a wolf tooth rod.
32. The process of claim 27, wherein: the evaporation section is fixedly connected with the liquid storage section through a flange, and the support plate is located in the middle of the flange.
33. The process of claim 27, wherein: the support plate is provided with a plurality of holes, and the diameter of each hole is smaller than that of the filler in the evaporation tube.
34. The process of claim 27, wherein: and the material distribution section is internally provided with a filler, and the filler is consistent with the filler in the evaporation tube.
35. The process of claim 27, wherein: the height of the material distribution section is 1-1.5 times of the diameter of the material distribution section, the height of the vapor-liquid separation section is 1-1.5 times of the diameter of the vapor-liquid separation section, and the height of the liquid storage section is 1-2 times of the diameter of the liquid storage section.
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