CN105000612B - Mechanical vapor recompression system of concentrated organic waste water and method - Google Patents

Abstract

A mechanical vapor recompression system for concentrating low-concentration organic wastewater and an application method thereof relate to the technical field of energy saving and emission reduction. The present invention adds a secondary evaporation unit to the outside of the heat exchange tube of the existing MVR evaporator, uses an external heat source to exchange heat again for the evaporator, further increases the alcohol concentration of the concentrated liquid after MVR concentration, improves energy utilization efficiency, and reduces Wastewater volume and energy consumption in the reconcentration process. The rectification tower and condensing device added in the invention not only make full use of the utilization efficiency of the external heat source, but also can reduce the concentration of alcohol in the steam, which provides convenience for the waste water to meet the discharge requirements. The process used in the invention is simple, the operation is convenient, and the cooling water system can be omitted.

Description

A mechanical vapor recompression system and method for concentrating organic wastewater

technical field

The invention belongs to the field of chemical industry, and in particular relates to a system and method for concentrating low-concentration organic wastewater by mechanical steam recompression.

Background technique

Organic wastewater contains a large amount of organic matter such as carbohydrates, fat, protein, cellulose, etc. If it is discharged directly, it will reduce the dissolved oxygen in the water and affect the growth of fish and other aquatic organisms. Water-soluble organic substances, such as low-molecular-weight organic alcohols, especially glycols, are often used as good freezing point depressants for deicing, anti-icing, and anti-freezing of vehicles and equipment, and may produce a large amount of low-concentration organic compounds in a short period of time. Alcohol-containing wastewater, the average COD of this type of wastewater exceeds 20,000mg/L. Organic wastewater containing low concentrations of organic matter will seriously endanger the ecological environment if it is discharged directly.

In order to protect the existing ecological environment, a lot of research has been done on how to deal with this kind of low-concentration organic wastewater at home and abroad, and now there are mainly biochemical methods and concentration methods. Due to the large fluctuation of COD in wastewater, it has a great influence on the activity of aerobic bacteria, thus restricting the application of biochemical methods. However, the previous physical or chemical means to improve the biodegradability of difficult-to-biochemical organic wastewater often required the addition of a large amount of reagents, or the input of a large amount of energy, the reaction time was long, and the effect was not significant, resulting in difficulties in reducing COD and deteriorating water environment. . By evaporating and concentrating low-concentration organic wastewater, the concentration method that evaporates most of the water and can recover useful substances is an effective organic wastewater treatment method.

The traditional multi-effect distillation evaporation concentration method can realize the recovery of organic matter, but due to the shortcomings of low steam use efficiency and high operating costs, a large amount of energy is consumed when treating low-concentration organic wastewater, and the process is complicated.

Mechanical vapor recompression is to use a mechanically driven compressor to compress the low-temperature steam generated by the evaporator, so that the temperature of the steam is increased into high-temperature steam, and then returned to the original evaporator, making full use of the latent heat of high-temperature steam, replacing external steam as a heat source , so as to achieve the purpose of energy saving, it is widely used in the treatment of salty wastewater, seawater desalination and other industries.

In order to save energy consumption in the evaporation process, a mechanical vapor recompression (MVR) system can be used to evaporate and concentrate low-concentration organic wastewater to increase the concentration of organic matter in the wastewater. However, due to the wastewater containing water-soluble organic matter, the water-soluble organic matter contained in it can lead to an increase in the boiling point of the wastewater solution. The vapor recompression (MVR) system performs evaporation and concentration on low-concentration alcohol-containing wastewater to increase the concentration of alcohol in the wastewater. However, due to the large difference in the boiling point of alcohol-containing wastewater after concentration, considering comprehensive consideration of energy consumption and investment costs, a single MVR system can only obtain an alcohol solution with an alcohol concentration of about 60%, and because the glycol may be evaporated during the evaporation process. The water vapor is taken out together, so that the condensed water produced by the system contains a relatively high concentration of alcohol, which cannot meet the emission requirements.

CN 203483884U relates to a caprolactam aqueous solution concentration device combining mechanical vapor recompression and multi-effect evaporation, which consists of MVR evaporation and multi-effect evaporation. The device adopts MVR technology to remove a large amount of water in the solution, concentrates the caprolactam to a certain concentration, and then enters the second-effect or three-effect evaporation process to realize the re-concentration of the caprolactam. The secondary steam is used as the heating steam of the next effect, which improves the heat utilization efficiency, saves energy consumption, and reduces the consumption of steam and cooling water. Although the device can increase the concentration of caprolactam, in the MVR system, the concentration of caprolactam can only reach 50% to 55%, and the subsequent multi-effect evaporation still requires high energy consumption.

CN 103224260A relates to a method for treating and recovering low-concentration DMAc and DMF wastewater by adopting the MVR concentration plus rectification method. Firstly, the waste water enters the concentration tower, pressurizes the secondary steam at the top of the concentration tower through a mechanical steam compressor, and then uses the evaporator of the concentration tower to heat the bottom of the concentration tower, so as to realize the DMAc and DMF concentration of the waste water in the concentration tower . Although this method solves the problems of difficult degradation of low-concentration DMAc and DMF wastewater, solvent loss, and high energy consumption for recovery, and realizes zero discharge of wastewater and recovery of raw materials for production, it can only concentrate DMAc and DMF in wastewater after MVR treatment. 30% to 50%, the subsequent rectification operation also needs to evaporate 50% to 70% of water, and the energy consumption required by the rectification operation is relatively high.

CN 203577339U provides a mechanical vapor recompression type evaporation concentration device, including an evaporation tank for flash evaporation, a steam compressor and a heat exchanger, the steam outlet of the evaporation tank is connected with the steam inlet of the compressor through a pipeline, and the steam compressor The steam outlet of the first heat exchanger and the steam inlet of the first heat exchanger are connected by pipelines. In this device, since the first heat exchanger is at the low position of the evaporation tank, the pressure of the treatment liquid in the first heat exchanger is greater than the pressure of the treatment liquid in the evaporation tank, and the pressure of the treatment liquid after being transported from the first heat exchanger to the evaporation tank changes Small, the evaporation temperature is lowered, thereby realizing flash evaporation. Although the device uses a power supply to achieve the concentration of waste water and does not need to use Freon and other heat transfer media, which reduces the cost, it is mainly used for the treatment of saline organic waste water, and it is not effective for the treatment of organic waste water that is easily carried out with steam.

Although the mechanical vapor recompression system has the advantages of reducing energy consumption and reducing the amount of fresh steam, its operating cost and energy consumption are closely related to the boiling point of the material, especially when concentrating low-concentration alcohol-containing wastewater, due to the high boiling point of alcohol-containing wastewater , the temperature difference loss is large, which will lead to a decrease in the evaporation concentration ratio of the MVR system, which is not conducive to increasing the alcohol concentration in the system concentrate. At the same time, since the dihydric alcohol in the wastewater is easily taken out by water vapor during the process of evaporating alcohol-containing chemical wastewater, the condensed water after evaporation contains more dihydric alcohol, so it cannot meet the discharge requirements. On the basis of retaining the original advantages of the existing MVR system, the present invention further increases the concentration of organic matter in the concentrated liquid, greatly reduces the concentration of organic matter in the condensed water, and can also use other heat sources to supplement heat for the system, which is beneficial to reduce energy consumption .

Contents of the invention

The purpose of the present invention is to provide a system and method for concentrating organic wastewater by using mechanical vapor recompression technology. Concentration of organic matter in condensate. In the wastewater evaporation process, the invention uses the secondary steam generated by the MVR evaporation process and an external heat source to heat and evaporate the organic wastewater, thereby increasing the evaporation amount and the concentration of organic matter in the concentrated solution, reducing the energy consumption in the reconcentration process, and improving wastewater treatment. efficiency.

To achieve the above object, the technical scheme adopted in the present invention is as follows:

A mechanical vapor recompression system for concentrating organic wastewater, including an evaporator 4, a gas-liquid separator 7, a rectification tower 8, a steam compressor 10, a wastewater inlet 1, a lift pump A2, a lift pump B11, and a discharge through pump 12 , heat exchanger 3, described evaporator 4 is made up of two independent primary evaporation units 5 and secondary evaporation unit 6, and described primary evaporation unit is adjacent to the outlet of steam compressor through pipeline, and secondary evaporation unit Connect an external heat source; the top of the gas-liquid separator is connected to the rectification tower 8, and the top of the rectification tower 8 is provided with a condensation device 9, and the condensation device is connected to the top of the rectification tower and a steam compressor respectively; the bottom of the gas-liquid separator They are respectively connected to the lift pump B11 and the discharge pump 12, the other end of the discharge pump is connected to the concentrated liquid storage tank 13, and the other end of the lift pump B11 is connected to the inlet of the first-stage evaporation unit; the waste water inlet 1 is connected to one end of the heat exchanger through the lift pump A2 The other end of the heat exchanger is connected to the inlet of the primary evaporation unit; the secondary evaporation unit is connected to the gas-liquid separator, and the primary evaporation unit is connected to the heat exchanger.

Further, the heat exchanger in the mechanical vapor recompression system for concentrated organic wastewater can be a shell-and-tube heat exchanger, a plate heat exchanger, a coil heat exchanger, preferably a shell-and-tube heat exchanger.

Further, the tube side of the secondary evaporation unit in the mechanical vapor recompression system for concentrating organic wastewater is connected, and the shell side is independent.

The present invention also provides an application method of a mechanical vapor recompression system for concentrating organic wastewater, comprising the steps of:

S1. In the heat exchanger 3, the initial organic wastewater is exchanged with the high-temperature condensed water generated after the heat exchange of the first-stage evaporation unit 5 of the evaporator, and the temperature of the initial organic wastewater before entering the evaporator is increased, and the high-temperature condensed water is exchanged. After heating, it becomes primary condensed water;

S2. The organic waste water after the heat exchange of the high-temperature condensed water in step S1 and the concentrated liquid containing high-concentration organic matter from the gas-liquid separator enter the evaporator including two evaporation units from the top of the evaporator 4, and first evaporate in the first stage. The unit 5 exchanges heat with the secondary steam generated by the steam compressor 10, and then exchanges heat with an external heat source in the secondary evaporation unit 6, and the gas-liquid mixture after heat exchange enters the gas-liquid separator 7 for gas-liquid separation. Separate the primary steam containing some organic matter and the concentrated liquid containing high-concentration organic matter, part of the concentrated liquid containing high-concentration organic matter flows back to the top of the evaporator and mixes with the liquid to be treated before entering the evaporator, and the remaining concentrated liquid containing high-concentration organic matter enters the evaporator In the concentrate storage tank 13;

S3. The primary steam separated by the gas-liquid separator passes through the rectification tower 8 and is partially condensed and refluxed by the condensing device 9 at the top of the rectification tower. Part of the organic matter in the primary steam becomes liquid and returns to the gas-liquid separator. The steam enters the steam compressor 10, and becomes secondary steam after being heated up by the mechanical steam compressor. The secondary steam returns to the first-stage evaporation unit of the evaporator to exchange heat with the initial organic wastewater entering the evaporator and then becomes high-temperature condensed water. The high-temperature condensed water becomes primary condensed water after heat exchange with the initial organic wastewater.

Further, the initial organic wastewater in S1 enters the heat exchanger through lift pump A2; part of the concentrated liquid containing high concentration of organic matter in S3 returns to the top of the evaporator through lift pump B11.

Further, the medium of the external heat source and the steam compressed by the steam compressor will not be mixed in the evaporator; after the organic matter in the primary steam is separated in the rectification tower, the steam is condensed by the condensate at the top of the rectification tower Part of the device is condensed and refluxed, and the concentration of organic matter in the primary steam is reduced, and then enters the steam compressor.

Further, the condensing device includes a condenser, or through cooling water, organic wastewater to be treated or other low-temperature liquids, the heat in the primary steam is taken away, and part of the primary steam is turned into a liquid and returned to the rectification tower.

Further, the condensing device condenses the primary steam by spraying the organic wastewater to be treated into the primary steam at the top of the rectification tower.

Furthermore, the tube side of the secondary evaporation unit is connected, and the shell side is independent. The organic wastewater enters the tube side for evaporation, and the secondary steam and external heat source respectively enter the shell side as heat sources for the evaporation of wastewater.

Further, the temperature of the heating medium provided by the external heat source in the secondary evaporation unit is 1°C higher than the temperature of the wastewater entering the secondary evaporation unit.

Further, the temperature generated by the heating medium is preferably 2-12°C higher than the temperature of the wastewater entering the secondary evaporation unit, more preferably 5-10°C higher.

Further, the water-soluble organic matter contained in the organic wastewater can cause the boiling point of its aqueous solution to rise.

Further, the water-soluble organic substances contained in the initial organic wastewater include but are not limited to ethylene glycol, propylene glycol, diethylene glycol, water-soluble alcohols, formamides, and alcohol amines.

Further, the concentration of organic matter in the initial organic wastewater is 1-20%, preferably 5-15%.

Further, the concentration of organic matter in the concentrated solution containing high concentration of organic matter is 45%-85%, preferably 55-75%.

The present invention has the following advantages:

1. The present invention has compact equipment, small footprint, simple process and convenient operation.

2. In the present invention, a secondary evaporation unit is set in the evaporator. In addition to the latent heat of the secondary steam generated by the MVR in the primary evaporation unit, the external heat source also continues to heat the low-concentration organic wastewater in the secondary evaporation unit. The concentration of organic matter in the concentrated liquid produced after the evaporation of waste water is increased from 40-50% to 60-75%, which reduces the amount of waste water and energy consumption in the subsequent re-concentration process; by setting the secondary evaporation unit in the MVR evaporator, it can Using waste heat from other channels to supplement heat for the system is beneficial to saving energy consumption.

3. The present invention adds a rectifying section and a condensing device to the existing MVR gas-liquid separator, reducing the concentration of organic matter in the condensed water produced by the MVR system.

4. The present invention can also condense the primary steam by adding initial organic waste water at the top of the rectification section, which not only reduces the concentration of alcohol in the primary steam, improves the efficiency of waste water treatment, but also does not need to consume cooling water, which is beneficial to reduce energy consumption.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

In the figure: 1: waste water inlet; 2, lift pump A; 3, heat exchanger; 4, evaporator; 5, primary evaporation unit; 6, secondary evaporation unit; 7, gas-liquid separator; 8, rectification Tower 9, condensing device; 10, steam compressor; 11, lifting pump B; 12, discharge through the pump; 13, concentrated liquid storage tank.

detailed description

In order to better illustrate the present invention, the present invention can be explained in more detail through the following examples. The present invention is not limited to the following examples.

In conjunction with a kind of mechanical vapor recompression system of concentrated low-concentration chemical waste water described in accompanying drawing 1,

A mechanical vapor recompression system for concentrating organic wastewater, including an evaporator 4, a gas-liquid separator 7, a rectification tower 8, a steam compressor 10, a wastewater inlet 1, a lift pump A2, a lift pump B11, and a discharge through pump 12 , heat exchanger 3, described evaporator 4 is made up of two independent primary evaporation units 5 and secondary evaporation unit 6, and described primary evaporation unit is adjacent to the outlet of steam compressor through pipeline, and secondary evaporation unit Connect an external heat source; the top of the gas-liquid separator is connected to the rectification tower 8, and the top of the rectification tower 8 is provided with a condensation device 9, and the condensation device is connected to the top of the rectification tower and a steam compressor respectively; the bottom of the gas-liquid separator They are respectively connected to the lift pump B11 and the discharge pump 12, the other end of the discharge pump is connected to the concentrated liquid storage tank 13, and the other end of the lift pump B11 is connected to the inlet of the first-stage evaporation unit; the waste water inlet 1 is connected to one end of the heat exchanger through the lift pump A2 The other end of the heat exchanger is connected to the inlet of the primary evaporation unit; the secondary evaporation unit is connected to the gas-liquid separator, the primary evaporation unit is connected to the heat exchanger, and the initial organic wastewater enters the heat exchanger through the lift pump A2; Concentrate containing high concentration of organic matter is returned to the top of the evaporator through the lift pump B11.

Further, the heat exchanger in Fig. 1 may be a shell-and-tube heat exchanger, a plate heat exchanger, a coil heat exchanger, preferably a shell-and-tube heat exchanger.

Further, the tube side of the secondary evaporation unit described in Fig. 1 is connected, the shell side is independent, the organic wastewater enters the tube side for evaporation, and the secondary steam and external heat source respectively enter the shell side as the heat source for wastewater evaporation.

Further, the medium of the external heat source and the steam compressed by the steam compressor will not be mixed in the evaporator; after the organic matter in the primary steam is separated in the rectification tower, the steam is condensed by the condensate at the top of the rectification tower Part of the device is condensed and refluxed, and the concentration of organic matter in the primary steam is reduced, and then enters the steam compressor.

Further, the condensing device can include a condenser, and can also take away the heat in the primary steam through cooling water, organic wastewater to be treated or other low-temperature liquids, so that part of the primary steam can be turned into liquid and returned to the rectification tower; The primary steam is condensed by sprinkling the organic waste water to be treated into the primary steam at the top of the rectification tower.

In conjunction with the mechanical vapor recompression system of a kind of concentrated low-concentration chemical waste water described in accompanying drawing 1, described method comprises the following steps when processing low-concentration propylene glycol waste water:

In the first step, the propylene glycol wastewater to be treated with a concentration of 5% enters the heat exchanger 3 and high-temperature condensed water through the lift pump A2 for heat exchange;

In the second step, the waste water after the heat exchange is mixed with the concentrated waste water containing high-concentration propylene glycol from the gas-liquid separator 7 and then enters the primary evaporation unit 5 of the evaporator 4. In the primary evaporation unit 5, it is combined with the steam compressor The secondary steam generated in 10 is evaporated after heat exchange, and the gas-liquid mixed liquid with a concentration of propylene glycol of about 30-60% is produced. The gas-liquid mixed liquid is further evaporated and concentrated after exchanging heat with an external heat source in the secondary evaporation unit 6. The gas-liquid mixture enters the gas-liquid separator 7 for gas-liquid separation, and separates the concentrated liquid with a propylene glycol concentration of 45% to 80% and the primary steam with a propylene glycol concentration of 1% to 13%, and part of the concentrated liquid is returned to the evaporator through the lift pump B11. The top of the device enters the evaporator after being mixed with the liquid to be treated, and the remaining concentrated liquid enters the concentrated liquid storage tank 13 through the pump 12 through the discharge;

In the third step, after the primary steam with a propylene glycol concentration of 1% to 13% is separated by the rectifying tower 8 and condensed and refluxed by the condensing device 9, most of the propylene glycol in the steam becomes liquid and returns to the gas-liquid separator, and the remaining primary steam Medium propylene glycol concentration can be reduced to 1%, enters steam compressor 10, becomes secondary steam after mechanical steam compressor does work and heats up, and secondary steam returns to primary evaporation unit 4 of evaporator to enter the propylene glycol waste water in evaporator Heat exchange, the wastewater is evaporated, the secondary steam becomes high-temperature condensed water, and the high-temperature condensed water is converted into primary condensed water after heat exchange with the initial propylene glycol wastewater to be treated.

In conjunction with the mechanical vapor recompression system of a kind of concentrated low-concentration chemical waste water described in accompanying drawing 1, described method comprises the following steps when processing low-concentration diethylene glycol waste water:

In the first step, the diethylene glycol wastewater to be treated with a concentration of 15% enters the heat exchanger 3 through the lift pump A2 to exchange heat with high-temperature condensed water;

In the second step, the waste water after the heat exchange is mixed with the concentrated waste water containing high-concentration diethylene glycol from the gas-liquid separator 7 and then enters the primary evaporation unit 5 of the evaporator 4, and is mixed with steam in the primary evaporation unit 5. The secondary steam generated by the compressor 10 is evaporated after heat exchange to produce a gas-liquid mixture with a diethylene glycol concentration of about 45%-55%. The gas-liquid mixture is further evaporated and concentrated in the secondary evaporation unit 6 after exchanging heat with an external heat source , the gas-liquid mixture produced after evaporation enters the gas-liquid separator 7 for gas-liquid separation, and the concentrated liquid with a diethylene glycol concentration of 65% to 80% and the primary steam with a diethylene glycol concentration of 5% to 13% are separated, partly The concentrated liquid flows back to the top of the evaporator through the lift pump B11 and mixes with the liquid to be treated before entering the evaporator, and the remaining concentrated liquid enters the concentrated liquid storage tank 13 through the discharge pump 12;

In the third step, after the primary steam with a diethylene glycol concentration of 5% to 13% is separated by the rectifying tower 8 and condensed and refluxed by the condensing device 9, most of the diethylene glycol in the steam becomes liquid and returns to the gas-liquid separator. The diethylene glycol concentration in the remaining primary steam can be reduced to 1%, enters the steam compressor 10, and becomes secondary steam after the mechanical steam compressor works and heats up, and the secondary steam returns to the primary evaporation unit 4 of the evaporator to enter the evaporation The diethylene glycol wastewater in the device is exchanged for heat to evaporate the wastewater, the secondary steam becomes high-temperature condensed water, and the high-temperature condensed water becomes primary condensed water after heat exchange with the initial diethylene glycol wastewater to be treated.

In conjunction with the mechanical vapor recompression system of a kind of concentrated low-concentration chemical waste water described in accompanying drawing 1, described method comprises the following steps when processing low-concentration ethylene glycol waste water:

In the first step, the ethylene glycol wastewater to be treated with a concentration of 20% enters the heat exchanger 3 through the lift pump A2 to exchange heat with high-temperature condensed water;

In the second step, the waste water after the heat exchange is mixed with the concentrated waste water containing high-concentration ethylene glycol from the gas-liquid separator 7 and then enters the primary evaporation unit 5 of the evaporator 4, and is mixed with steam in the primary evaporation unit 5. The secondary steam generated by the compressor 10 is evaporated after heat exchange to produce a gas-liquid mixture with an ethylene glycol concentration of about 40%-60%. The gas-liquid mixture is further evaporated and concentrated in the secondary evaporation unit 6 after exchanging heat with an external heat source , the gas-liquid mixture produced after evaporation enters the gas-liquid separator 7 for gas-liquid separation, and separates the concentrated liquid with a glycol concentration of 55% to 75% and the primary steam with a glycol concentration of 4% to 10%. The concentrated liquid flows back to the top of the evaporator through the lift pump B11 and mixes with the liquid to be treated before entering the evaporator, and the remaining concentrated liquid enters the concentrated liquid storage tank 13 through the discharge pump 12;

In the third step, after the primary steam with an ethylene glycol concentration of 4% to 10% is separated by the rectification tower 8 and condensed and refluxed by the condensing device 9, most of the ethylene glycol in the steam becomes liquid and returns to the gas-liquid separator. The concentration of ethylene glycol in the remaining primary steam can be reduced to 1%, enter the steam compressor 10, and become secondary steam after the mechanical steam compressor works and heats up, and the secondary steam returns to the primary evaporation unit 4 of the evaporator to enter the evaporation The ethylene glycol wastewater in the tank is exchanged for heat to evaporate the wastewater, the secondary steam becomes high-temperature condensed water, and the high-temperature condensed water becomes primary condensed water after heat exchange with the initial ethylene glycol wastewater to be treated.

The unspecified parts of the present invention are the same as the prior art or can be realized by adopting the prior art.

The patent of the present invention is not limited to the above-mentioned disclosed embodiments, and all changes and improvements of the embodiments within the concept and scope of the present invention are within the protection scope of the present invention.

Claims (13)

1. it is a kind of concentration organic wastewater function of mechanical steam recompression systematic difference method, it is characterised in that：The concentration is organic The function of mechanical steam recompression system of waste water include evaporimeter (4), gas-liquid separator (7), rectifying column (8), vapour compression machine (10), , by pump (12), heat exchanger (3), the evaporimeter (4) is by two for waterwater entrance (1), elevator pump A (2), elevator pump B (11), discharging Individual independent one-level evaporation element (5) and dual evaporation unit (6) are constituted, and the one-level evaporation element goes out with vapour compression machine Mouth is connected by pipeline, and dual evaporation unit connects external thermal source；The gas-liquid separator top is connected with rectifying column (8), essence Evaporate tower (8) top and be provided with condensing unit (9), condensing unit is connected respectively with rectifying column top and vapour compression machine；The gas Liquid/gas separator bottom is connected respectively with elevator pump B (11) and discharging by pump, and discharging is by pump other end connection concentration liquid storage tank (13), elevator pump B (11) other end connection one-level evaporation element entrance；Waterwater entrance (1) is by elevator pump A (2) and heat exchanger One end is connected, heat exchanger other end connection one-level evaporation element entrance；The dual evaporation unit is connected with gas-liquid separator, and one Level evaporation element is connected with heat exchanger；

The application process comprises the steps：

S1, by initial organic wastewater in heat exchanger (3) with through evaporimeter one-level evaporation element (5) heat exchange after produce high temperature Condensed water is exchanged heat, and improves the wastewater temperature that initial organic wastewater is entered before evaporimeter, and high-temperature condensation water becomes after being exchanged heat Into a condensed water；

S2, step S1 high-temperature condensation water heat exchange after organic wastewater with contain high-enriched organics from the part of gas-liquid separator Concentrate enter in the evaporimeter comprising two evaporation elements from evaporimeter (4) top, first in one-level evaporation element (5) The indirect steam heat exchange produced with vapour compression machine (10), then exchanged heat with external thermal source in dual evaporation unit (6), change Gas-liquid mixture after heat is entered in gas-liquid separator (7) and carries out gas-liquid separation, isolates the once steaming containing partial organic substances Vapour and the concentrate containing high-enriched organics, partly the concentrate containing high-enriched organics be back to evaporimeter top and treat Evaporimeter is entered after treatment fluid mixing, the remaining concentrate containing high-enriched organics is entered in concentration liquid storage tank (13)；

The primary steam that S3, gas-liquid separator separates go out is condensed device (9) partial condensation Jing after rectifying column (8) in rectifying tower top Backflow, the partial organic substances in primary steam are changed into liquid and return in gas-liquid separator, and remaining primary steam enters steam Compressor (10), Jing after Mechanical Vapor Compression acting heats up indirect steam is become, and indirect steam returns to the one-level of evaporimeter Evaporation element becomes high-temperature condensation water after exchanging heat to the initial organic wastewater into evaporimeter, high-temperature condensation water has with initially Machine waste water becomes a condensed water after being exchanged heat.

2. the function of mechanical steam recompression systematic difference method of a kind of concentration organic wastewater as claimed in claim 1, its feature It is：The heat exchanger is shell-and-tube heat exchanger, plate type heat exchanger or coil exchanger.

3. the function of mechanical steam recompression systematic difference method of a kind of concentration organic wastewater as claimed in claim 1, its feature It is：Initial organic wastewater enters heat exchanger by elevator pump A (2) in S1；Concentration of the part containing high-enriched organics in S3 Liquid is back to evaporimeter top by elevator pump B (11).

4. the function of mechanical steam recompression systematic difference method of a kind of concentration organic wastewater as claimed in claim 1, its feature It is：The medium of the external thermal source with compressed by vapour compression machine after steam will not mix in evaporimeter；It is described once After organic matter in steam is separated in rectifying column, steam be distillated tower top condensing unit partial condensation backflow, once steam After organic concentration in vapour is reduced, into vapour compression machine.

5. the function of mechanical steam recompression systematic difference method of a kind of concentration organic wastewater as claimed in claim 4, its feature It is：Condensing unit includes condenser, or by cooling water, pending organic wastewater or other cryogenic liquids, takes away and once steam Heat in vapour, allows part primary steam to be changed into liquid, in returning to rectifying column.

6. the function of mechanical steam recompression systematic difference method of a kind of concentration organic wastewater as claimed in claim 4, its feature It is：Condensing unit to condense by way of the pending organic wastewater of spread in the primary steam at the top of rectifying column once steaming Vapour.

7. the function of mechanical steam recompression systematic difference method of a kind of concentration organic wastewater as claimed in claim 1, its feature It is：The tube side of dual evaporation unit is connection, and shell side is independent, and organic wastewater is evaporated into tube side, secondary steaming Vapour and external thermal source respectively enter thermal source when shell side evaporates as waste water.

8. the function of mechanical steam recompression systematic difference method of a kind of concentration organic wastewater as claimed in claim 7, its feature It is：The temperature that described external thermal source is provided in dual evaporation unit plus thermal medium is produced, than into dual evaporation list The wastewater temperature of unit is high more than 1 DEG C.

9. the function of mechanical steam recompression systematic difference method of a kind of concentration organic wastewater as claimed in claim 8, its feature It is：The temperature that described plus thermal medium is produced is higher 2～12 DEG C than the wastewater temperature into dual evaporation unit.

10. the function of mechanical steam recompression systematic difference side of a kind of concentration organic wastewater as described in one of claim 1～9 Method, it is characterised in that：Contained water soluble organic substance can cause its aqueous solution elevation of boiling point in described initial organic wastewater.

A kind of 11. function of mechanical steam recompression systematic difference methods of concentration organic wastewater as claimed in claim 10, it is special Levy and be：Contained water soluble organic substance is including but not limited to ethylene glycol, propane diols, second two in described initial organic wastewater The water-soluble alcohols material of alcohols, benzamide type, alcamines material.

A kind of function of mechanical steam recompression systematic difference side of the 12. concentration organic wastewaters as described in one of claim 1～9 Method, it is characterised in that：The concentration of described initial organic waste Organic substance in water is 1～20%.

A kind of 13. function of mechanical steam recompression systematic difference methods of concentration organic wastewater as claimed in claim 12, it is special Levy and be：The concentration of organic matter is 45%～85% in the concentrate containing high-enriched organics.