CN217921522U

CN217921522U - Waste water evaporation and concentration equipment

Info

Publication number: CN217921522U
Application number: CN202221625421.XU
Authority: CN
Inventors: 邓方平; 邓梁
Original assignee: Changsha Zoomlion Environmental Industry Co Ltd
Current assignee: Changsha Zoomlion Environmental Industry Co Ltd
Priority date: 2022-06-27
Filing date: 2022-06-27
Publication date: 2022-11-29
Anticipated expiration: 2032-06-27

Abstract

The utility model discloses a waste water evaporation concentration equipment, include: the system comprises a first evaporation device, a second evaporation device, a wastewater circulating heat exchange loop, a wastewater re-evaporation loop, a first steam loop and a second steam loop. The input end of the waste water circulating heat exchange loop is respectively communicated with the first evaporation plant and a waste water source for supplying waste water from the outside, and the opposite output end of the waste water circulating heat exchange loop is communicated with the first evaporation plant. And two ends of the first steam loop are respectively communicated with the first evaporation plant and the wastewater circulating heat exchange loop. Two ends of the waste water re-evaporation loop are respectively communicated with the first evaporation device and the second evaporation device. The input end of the second steam loop is communicated with the second evaporation device, and the opposite output ends of the second steam loop are respectively communicated with the wastewater circulating heat exchange loop and the second evaporation device. The utility model discloses a waste water evaporation concentration equipment makes heat transfer device's the difficult scale deposit of heat transfer surface, does not influence system's heat exchange and evaporation effect, and the long, the do not need washing of system steady operation duration, and can realize "zero release".

Description

Waste water evaporation and concentration equipment

Technical Field

The utility model relates to a sewage treatment technical field especially relates to a waste water evaporation concentration equipment.

Background

The landfill leachate is typical high-concentration wastewater, has the characteristics of high pollution, high harm, difficult disposal and the like, contains various organic matters which are listed as key control lists of environmental protection departments at home and abroad, and the harmless treatment of the landfill leachate is an important subject of the global environmental protection field. In order to realize zero emission of the landfill leachate, evaporation treatment gradually becomes a better process of the landfill leachate, but the existing evaporation equipment has the problems of different degrees in actual use, and how to better perform evaporation, improve the system efficiency and prolong the cleaning period is still to be perfected.

At present, when the method is used for evaporation treatment of landfill leachate and industrial wastewater, the method mainly comprises the following steps: MVR evaporation equipment, reation kettle evaporation equipment, film heating evaporation equipment.

Wherein, MVR evaporation equipment: because the boiling point rises during the evaporation of the sewage, the liquid phase temperature in the evaporation process is higher than the gas phase temperature of the secondary steam, and the current compression temperature rise of the steam compressor is limited, so that the heating temperature difference between the secondary steam and the evaporated liquid in the heat exchanger is also limited, the concentration multiple of the evaporation of the sewage is not high, the recovery rate of the water is about 85 percent generally, and other equipment is required to be matched for realizing 'zero emission'.

Wherein, reation kettle evaporation equipment: the liquid flow is limited, the inner wall of the cylinder body is easy to scale or pollute, and the heat transfer of the wall surface is blocked, so that the heat exchange efficiency of the system is low, and the steam energy consumption is high; the equipment is vertically installed, the discharge flow is difficult to control, the evaporated slag liquid needs to be discharged once during actual evaporation, and then the material can be fed again, so that the effective working time is shortened, and the evaporation efficiency is lower; influenced by heat exchange efficiency, the same evaporation capacity needs larger (longer) equipment or more equipment, and the matched machine frame and plant are complex, inconvenient to install and high in cost.

Wherein, film heating evaporation equipment: compared with reaction kettle equipment, single equipment is larger (longer) and poorer in installation performance; in addition, because the equipment needs to be heated into a film shape, if the equipment is in trouble or the medium is changed, the film distribution is not uniform, even the film is broken and the dry heat is generated, so that the heat exchange efficiency is greatly reduced.

And calcium, magnesium ions, organic matters and the like in the process of concentrating the landfill leachate and the industrial wastewater are continuously concentrated, and because the solubility of calcium sulfate, calcium carbonate, magnesium hydroxide, organic scales and the like is extremely low, the calcium sulfate, the calcium carbonate, the magnesium hydroxide, the organic scales and the like can not be suspended in the solution but adhered to the heat transfer surface of the heat exchanger after the material concentration reaches supersaturation and is separated out, so that the heat exchange and evaporation effects of the system are influenced, even an overflowing channel is blocked, the system is failed, and the cleaning is difficult, and the production is seriously influenced.

SUMMERY OF THE UTILITY MODEL

The utility model provides a waste water evaporation concentration equipment to thereby solve the not high, the heat exchange efficiency of the concentration multiple of the sewage evaporation that current evaporation equipment exists, steam energy consumption is high, evaporation efficiency is lower, the precipitate easily blocks up the difficult abluent technical problem of passageway that overflows.

The utility model adopts the technical scheme as follows:

an evaporative concentration apparatus for wastewater, comprising: the system comprises a first evaporation device for carrying out first boiling point reduction evaporation on the wastewater, a second evaporation device for carrying out second boiling point reduction evaporation on the wastewater, a wastewater circulating heat exchange loop, a wastewater re-evaporation loop, a first steam loop and a second steam loop; the input end of the waste water circulation heat exchange loop is respectively communicated with a first evaporation device and a waste water source for supplying waste water from the outside, and the opposite output end of the waste water circulation heat exchange loop is communicated with the first evaporation device, so that the waste water in the first evaporation device and the external waste water exchange heat with steam and then flow into the first evaporation device in a circulation mode; two ends of the first steam loop are respectively communicated with the first evaporation device and the wastewater circulating heat exchange loop so as to enable the steam generated by the first evaporation device to heat the wastewater in the wastewater circulating heat exchange loop and then discharge the heated wastewater; two ends of the waste water re-evaporation loop are respectively communicated with the first evaporation device and the second evaporation device so as to guide unsaturated concentrated waste water generated after evaporation in the first evaporation device into the second evaporation device for re-evaporation; the input end of the second steam loop is communicated with the second evaporation device, and the opposite output ends of the second steam loop are respectively communicated with the wastewater circulating heat exchange loop and the second evaporation device, so that the steam generated by the second evaporation device is used for heating the wastewater in the wastewater circulating heat exchange loop and reheating the concentrated wastewater in the second evaporation device.

Further, the first evaporation device comprises a first evaporation tank and a first compressor; the first steam loop comprises a first steam pipe, the input end of the first steam pipe is communicated with the top of the first evaporation tank, the opposite output end of the first steam pipe is communicated with the wastewater circulating heat exchange loop, and the first compressor is connected in a pipeline of the first steam pipe.

Furthermore, the wastewater circulating heat exchange loop comprises a wastewater input pipe, a circulating conveying pipe, a circulating pump and a steam heat exchanger; two ends of the circulating conveying pipe are respectively communicated with the side wall of the first evaporating pot, the circulating pump and the steam heat exchanger are sequentially connected in a pipeline of the circulating conveying pipe, and output ends of the first steam loop and the second steam loop are respectively connected with the steam heat exchanger; the input end of the waste water input pipe is communicated with a waste water source, and the opposite output end of the waste water input pipe is communicated with a circulating delivery pipe at the front end of the circulating pump.

Further, the wastewater circulating heat exchange loop also comprises a distilled water heat exchanger; the front end of the waste water input pipe and the rear end of the first steam pipe after penetrating the steam heat exchanger are respectively connected with the distilled water heat exchanger.

Further, the second evaporation device comprises a second evaporation tank and a second compressor; the input end of the second steam loop is communicated with the second evaporation tank, and the opposite output ends of the second steam loop are respectively communicated with the first steam pipe and the second evaporation tank.

Further, the waste water re-evaporation loop comprises a waste water output pipe and a feeding pump; two ends of the wastewater output pipe are respectively communicated with the first evaporating tank and the second evaporating tank; the feeding pump is connected to the pipeline of the waste water output pipe.

Further, the second steam loop comprises a steam main pipe, a first steam branch pipe, a second steam branch pipe, a first valve and a second valve; the input end of the steam main pipe is communicated with the top of the second evaporation tank, the opposite output ends of the steam main pipe are respectively communicated with the input ends of the first steam branch pipe and the second steam branch pipe, the output end of the first steam branch pipe is communicated with the first steam pipe, and the output end of the second steam branch pipe is communicated with the side wall of the second evaporation tank; the second compressor is connected in the pipeline of the steam main, the first valve is connected in the pipeline of the first steam branch pipe, and the second valve is connected in the pipeline of the second steam branch pipe.

Further, the output end of the second steam branch pipe is communicated with the side wall of the bottom end of the second evaporation tank.

Further, the second evaporating pot comprises a hollow and hermetically arranged pot body and a scraper arranged in the pot body; the scraper rotates along the circumferential direction of the axis of the second evaporating pot so as to prevent the evaporated and precipitated substances from being adhered to the inner wall surface of the pot body.

Further, waste water evaporation concentration equipment still includes concentrate discharge loop, and the input intercommunication second evaporating pot's of concentrate discharge loop bottom, its relative output intercommunication are used for the device of splendid attire concentrate.

The utility model discloses following beneficial effect has:

the utility model discloses a waste water evaporation concentration equipment, through setting up first evaporation plant and second evaporation plant, divide into two sections evaporation with waste water, the first section evaporation concentration multiple of first evaporation plant is lower, calcium sulfate, calcium carbonate, magnesium hydroxide, organic dirt etc. in the waste water are not concentrated and are reached the saturation, or the saturation is not high, and the precipitate is less to make the heat transfer surface of the heat transfer device in the waste water circulation heat transfer loop be difficult for the scale deposit, and then do not influence system's heat exchange and evaporation effect; the second section of evaporation of the second evaporation device adopts the heating crystallization of the mode that high-temperature steam generated during the operation directly contacts with concentrated wastewater in the second evaporation device to heat, and no heat exchange surface and no scale are generated in the heating process, so that the system has long stable operation time and does not need to be cleaned; after the low-temperature steam generated by the second-stage evaporation is heated and pressurized through the second evaporation device, one part supplies heat to the wastewater of the first-stage evaporation for heating evaporation, and the other part supplies heat to the wastewater of the second-stage evaporation for heating evaporation, so that all the heat in the two-stage evaporation is recycled, and the system is efficient and energy-saving in operation.

In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be described in further detail with reference to the drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:

FIG. 1 is a schematic structural view of an evaporative concentration apparatus for wastewater according to a preferred embodiment of the present invention.

Description of the drawings

10. A first evaporation device; 11. a first evaporator tank; 12. a first compressor; 20. a second evaporation device; 21. a second evaporator tank; 211. a tank body; 212. a scraper; 22. a second compressor; 30. a wastewater circulating heat exchange loop; 31. a wastewater input pipe; 32. a circulating delivery pipe; 33. a circulation pump; 34. a steam heat exchanger; 35. a distilled water heat exchanger; 40. a wastewater re-evaporation loop; 41. a waste water output pipe; 42. a feed pump; 50. a first steam circuit; 51. a first steam pipe; 60. a second steam circuit; 61. a steam main pipe; 62. a first steam branch pipe; 63. a second steam branch pipe; 64. a first valve; 65. a second valve; 70. concentrate exits the circuit.

Detailed Description

The embodiments of the invention will be described in detail hereinafter with reference to the drawings, but the invention can be implemented in many different ways, which will be defined and covered hereinafter.

Referring to fig. 1, a preferred embodiment of the present invention provides a wastewater evaporative concentration apparatus, including: the system comprises a first evaporation device 10 for carrying out first boiling point reduction evaporation on the wastewater, a second evaporation device 20 for carrying out second boiling point reduction evaporation on the wastewater, a wastewater circulating heat exchange loop 30, a wastewater re-evaporation loop 40, a first steam loop 50 and a second steam loop 60. The input end of the waste water circulation heat exchange loop 30 is respectively communicated with the first evaporation device 10 and a waste water source for supplying waste water from the outside, and the opposite output end is communicated with the first evaporation device 10, so that the waste water in the first evaporation device 10 and the external waste water are recycled to flow into the first evaporation device 10 after exchanging heat with steam. Two ends of the first steam loop 50 are respectively communicated with the first evaporation device 10 and the wastewater circulating heat exchange loop 30, so that the steam generated by the first evaporation device 10 heats the wastewater in the wastewater circulating heat exchange loop 30 and then is discharged. Two ends of the waste water re-evaporation loop 40 are respectively communicated with the first evaporation device 10 and the second evaporation device 20, so that the unsaturated concentrated waste water generated after evaporation in the first evaporation device 10 is guided into the second evaporation device 20 for re-evaporation. The input end of the second steam loop 60 is communicated with the second evaporation device 20, and the opposite output ends thereof are respectively communicated with the wastewater circulating heat exchange loop 30 and the second evaporation device 20, so that the steam generated by the second evaporation device 20 is used for heating the wastewater in the wastewater circulating heat exchange loop 30 and reheating the concentrated wastewater in the second evaporation device 20.

The utility model discloses a waste water evaporation concentration equipment during operation, at first pass through waste water circulation heat transfer circuit 30 with the waste water source waste water of treating the evaporation and heat exchange behind the steam heat exchange that first evaporation plant 10 and second evaporation plant 20 produced, get into in the first evaporation plant 10, then restart waste water circulation heat transfer circuit 30, make the waste water of first evaporation plant 10 circulate constantly to flow between waste water circulation heat transfer circuit 30 and first evaporation plant 10, reopen first evaporation plant 10 and take out into the negative pressure in it, thereby make boiling behind the waste water boiling point reduction in the first evaporation plant 10 and produce low temperature low pressure vapor, and vapor becomes high temperature high pressure vapor after the pressurization through first evaporation plant 10 effect intensification, high temperature high pressure vapor carries out the heat exchange through first vapor circuit 50 and the waste water of flowing through waste water circulation heat transfer circuit 30, carry out the flash distillation in first evaporation plant 10 after waste water intensifies, and high temperature high pressure vapor is discharged outside again after becoming distilled water through cooling condensation behind the heat transfer.

When the wastewater in the first evaporation device 10 reaches a certain concentration, the concentrated wastewater is discharged into the second evaporation device 20 through the wastewater re-evaporation loop 40 for further concentration, and at the same time, the second evaporation device 20 is started to be pumped into negative pressure, so that the boiling point of the concentrated wastewater in the second evaporation device 20 is reduced and then boiled to generate low-temperature and low-pressure steam, the steam is heated and pressurized to become high-temperature and high-pressure steam through the action of the second evaporation device 20, a part of the high-temperature and high-pressure steam directly flows back to the second evaporation device 20 through the second steam loop 60 to provide heat for the concentrated wastewater in the second evaporation device 20 to be heated and evaporated to form low-temperature and low-pressure steam, and the other part of the high-temperature and high-pressure steam provides heat for the wastewater in the wastewater circulation heat exchange loop 30 to be heated and evaporated through the second steam loop 60.

The utility model discloses a waste water evaporative concentration equipment through setting up first evaporation plant 10 and second evaporation plant 20, divide into two sections evaporation with waste water, and the first section evaporative concentration multiple of first evaporation plant 10 is lower, and calcium sulfate, calcium carbonate, magnesium hydroxide, organic dirt etc. in the waste water are not concentrated and are reached the saturation, or the saturation degree is not high, and the precipitate is less to make the heat transfer surface of the heat transfer device in waste water circulation heat transfer loop 30 be difficult for the scale deposit, and then do not influence system heat exchange and evaporation effect; the second section of evaporation of the second evaporation device 20 adopts the heating crystallization of the high-temperature steam generated during the operation and the concentrated wastewater in the high-temperature steam in the heating mode by direct contact, and the heating process has no heat exchange surface and no scale, so that the system has long stable operation time and does not need to be cleaned, and the evaporation concentration multiple of the second evaporation device 20 is high, and can be directly concentrated to the required concentration multiple, thereby realizing zero emission; after the low-temperature steam generated by the second-stage evaporation is heated and pressurized through the second evaporation device 20, one part of the low-temperature steam provides heat for the waste water of the first-stage evaporation to carry out heating evaporation, and the other part of the low-temperature steam provides heat for the waste water of the second-stage evaporation to carry out heating evaporation, so that all the heat in the two-stage evaporation is recycled, and the system is efficient and energy-saving in operation.

Alternatively, as shown in fig. 1, the first evaporation device 10 includes a first evaporation tank 11 and a first compressor 12, and the structural arrangement is simple. The first steam circuit 50 includes a first steam pipe 51, an input end of the first steam pipe 51 communicates with the top of the first evaporation tank 11, an opposite output end thereof communicates with the wastewater circulating heat exchange circuit 30, and the first compressor 12 is connected in a pipe line of the first steam pipe 51. In operation, steam generated by evaporation in the first evaporation tank 11 enters the wastewater circulating heat exchange loop 30 through the first steam pipe 51 for heat exchange.

Optionally, as shown in fig. 1, the wastewater recycling heat exchange loop 30 includes a wastewater input pipe 31, a recycling delivery pipe 32, a recycling pump 33, and a steam heat exchanger 34. Two ends of the circulation conveying pipe 32 are respectively communicated with the side wall of the first evaporating pot 11, the circulation pump 33 and the steam heat exchanger 34 are sequentially connected in the pipeline of the circulation conveying pipe 32, and the output ends of the first steam loop 50 and the second steam loop 60 are respectively connected with the steam heat exchanger 34. An input end of the waste water input pipe 31 is communicated with a waste water source, and an opposite output end thereof is communicated with a circulating delivery pipe 32 at the front end of a circulating pump 33.

Further, as shown in fig. 1, the wastewater recycling heat exchange loop 30 further includes a distilled water heat exchanger 35. The front end of the wastewater input pipe 31 and the rear end of the first steam pipe 51 after penetrating the steam heat exchanger 34 are connected to the distilled water heat exchanger 35, respectively.

When the device works, waste water supplied by a waste water source is heated to a certain temperature by methods of generating steam by an external steam or a steam generator or electrically heating, and then the waste water to be evaporated enters the first evaporation tank 11 after being subjected to heat exchange with the steam supplied by the first steam pipe 51 through the steam heat exchanger 34 and the circulating conveying pipe 32; then, the circulating pump 33 is started to enable the wastewater in the first evaporation tank 11 to continuously flow in the wastewater circulating heat exchange loop 30 between the steam heat exchanger 34 and the first evaporation tank 11 under the action of the circulating conveying pipe 32; and then, starting the first compressor 12 to pump the waste water in the first evaporation tank 11 into negative pressure, so that the boiling point of the waste water in the first evaporation tank 11 is reduced and then boiled to generate low-temperature and low-pressure water vapor, the water vapor is heated and pressurized by the first compressor 12 to become high-temperature and high-pressure water vapor, the high-temperature and high-pressure water vapor exchanges heat with the waste water flowing through the steam heat exchanger 34, the waste water is heated and then flashed in the first evaporation tank 11, the high-temperature and high-pressure water vapor is cooled and condensed by the steam heat exchanger 34 to become distilled water, and then the distilled water heat exchanger 35 further releases heat to finish treatment and discharge. The evaporation concentration multiple of the section is low, calcium sulfate, calcium carbonate, magnesium hydroxide, organic scale and the like in the wastewater are not concentrated to reach saturation, or the saturation degree is low, and precipitates are few, so that the heat transfer surface of the steam heat exchanger 34 is not easy to scale, and the heat exchange and evaporation effects of a system are not influenced.

Alternatively, as shown in fig. 1, the second evaporation device 20 includes a second evaporation tank 21 and a second compressor 22, and the structural arrangement is simple. The second steam circuit 60 has an input end communicating with the second evaporation tank 21 and opposite output ends communicating with the first steam pipe 51 and the second evaporation tank 21, respectively.

Alternatively, as shown in FIG. 1, the wastewater re-evaporation loop 40 includes a wastewater output pipe 41 and a feed pump 42. Two ends of the waste water output pipe 41 are respectively communicated with the first evaporating pot 11 and the second evaporating pot 21. A feed pump 42 is connected to the piping of the waste water outlet pipe 41. By arranging the waste water output pipe 41, the concentrated waste water generated after evaporation in the first evaporation tank 11 enters the second evaporation tank 21 again for re-evaporation.

Alternatively, as shown in FIG. 1, the second steam circuit 60 includes a steam header 61, a first steam branch 62, a second steam branch 63, a first valve 64, and a second valve 65. The input end of the steam header 61 is communicated with the top of the second evaporation pot 21, the opposite output ends thereof are respectively communicated with the input ends of the first steam branch pipe 62 and the second steam branch pipe 63, the output end of the first steam branch pipe 62 is communicated with the first steam pipe 51, and the output end of the second steam branch pipe 63 is communicated with the side wall of the second evaporation pot 21. The second compressor 22 is connected in the line of the steam header 61, and the first valve 64 is connected in the line of the first steam branch 62, and the second valve 65 is connected in the line of the second steam branch 63.

When the system works, when the wastewater in the first evaporation tank 11 reaches a certain concentration, the concentrated wastewater is discharged into the second evaporation tank 21 for further concentration through the action of the wastewater output pipe 41 and the feeding pump 42, the second compressor 22 is started at the same time, negative pressure is pumped in the second evaporation tank 21, so that the boiling point of the concentrated wastewater in the second evaporation tank 21 is reduced and then boiled to generate low-temperature low-pressure steam, the steam is heated and pressurized by the second compressor 22 to become high-temperature high-pressure steam, one part of the high-temperature high-pressure steam directly enters the second evaporation tank 21 through the second steam branch pipe 63 to heat and evaporate the concentrated wastewater in the second evaporation tank 21 to form low-temperature low-pressure steam, the other part of the high-temperature high-pressure steam enters the steam heat exchanger 34 through the first steam branch pipe 62 and the first steam pipe 51, heat supplied by the steam heat exchanger 34 to heat and evaporate the wastewater in the first evaporation tank 11, so that all heat is recycled, the system is efficient and energy-saving in operation, and the steam amount of the steam heat exchanger 21 and the steam heat generated by the second evaporation tank 34 are adjusted through controlling the opening degree of the first valve 64 and the second valve 65. The section of evaporation adopts the heating crystallization of the direct contact heating form of high-temperature steam and concentrated wastewater in the second evaporation tank 21, the heating process has no heat exchange surface and no scale, the stable operation time of the system is long, the system does not need to be cleaned, and the evaporation concentration multiple is high, so that the zero emission can be realized by directly concentrating to the required concentration multiple; the low-temperature steam generated by the evaporation of the section is heated and pressurized by the second compressor 22, one part of the low-temperature steam provides heat for the wastewater of the first-section evaporation to be heated and evaporated, the other part of the low-temperature steam provides heat for the wastewater of the second-section evaporation to be heated and evaporated, all the heat is recycled, and the system is efficient and energy-saving in operation.

Preferably, as shown in fig. 1, the output end of the second steam branch pipe 63 is communicated with the side wall of the bottom end of the second evaporation tank 21, so that the high-temperature steam is introduced into the second evaporation tank 21 from the bottom of the second evaporation tank 21.

Preferably, as shown in fig. 1, the second evaporation tank 21 includes a hollow and hermetically disposed tank body 211, and a scraper 212 disposed in the tank body 211. The scraper 212 rotates circumferentially along the axis of the second evaporation tank 21 for preventing the evaporated and precipitated substances from adhering to the inner wall surface of the tank body 211. In this preferred scheme, during this section evaporation concentration process, high temperature steam bubbles in second evaporating pot 21 bottom to scraper 212 in second evaporating pot 21 is constantly rotatory, makes the difficult bonding of the material that separates out after the waste water concentration on second evaporating pot 21 inner wall.

Optionally, as shown in fig. 1, the wastewater evaporative concentration apparatus further comprises a concentrated solution discharge circuit 70, wherein an input end of the concentrated solution discharge circuit 70 is communicated with the bottom end of the second evaporation tank 21, and an opposite output end thereof is communicated with the device for containing the concentrated solution. In this alternative, the concentrated solution discharge loop 70 includes the concentrated solution discharge pipe, and the input of concentrated solution discharge pipe communicates the bottom of second evaporating pot 21, and its relative output communicates the outside device that is used for splendid attire concentrate to the concentrated solution after the completion of second evaporating pot 21 concentration is outwards discharged from the bottom of second evaporating pot 21, and it is effectual to discharge.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An evaporative concentration apparatus for waste water, comprising:

the system comprises a first evaporation device (10) for carrying out first boiling point reduction evaporation on the wastewater, a second evaporation device (20) for carrying out second boiling point reduction evaporation on the wastewater, a wastewater circulating heat exchange loop (30), a wastewater re-evaporation loop (40), a first steam loop (50) and a second steam loop (60);

the input end of the wastewater circulating heat exchange loop (30) is respectively communicated with the first evaporation device (10) and a wastewater source for supplying wastewater from the outside, and the opposite output end of the wastewater circulating heat exchange loop is communicated with the first evaporation device (10), so that the wastewater in the first evaporation device (10) and the external wastewater exchange heat with steam and then flow into the first evaporation device (10) in a circulating manner;

two ends of the first steam loop (50) are respectively communicated with the first evaporation device (10) and the wastewater circulating heat exchange loop (30) so that the steam generated by the first evaporation device (10) heats the wastewater in the wastewater circulating heat exchange loop (30) and then is discharged;

two ends of the waste water re-evaporation loop (40) are respectively communicated with the first evaporation device (10) and the second evaporation device (20) so as to guide unsaturated concentrated waste water generated after evaporation in the first evaporation device (10) into the second evaporation device (20) for re-evaporation;

the input end of the second steam loop (60) is communicated with the second evaporation device (20), and the opposite output ends of the second steam loop are respectively communicated with the wastewater circulating heat exchange loop (30) and the second evaporation device (20), so that the steam generated by the second evaporation device (20) is used for heating the wastewater in the wastewater circulating heat exchange loop (30) and reheating the concentrated wastewater in the second evaporation device (20).

2. The wastewater evaporative concentration apparatus as set forth in claim 1,

the first evaporation device (10) comprises a first evaporation tank (11) and a first compressor (12);

the first steam loop (50) comprises a first steam pipe (51), the input end of the first steam pipe (51) is communicated with the top of the first evaporation tank (11), the opposite output end of the first steam pipe is communicated with the wastewater circulating heat exchange loop (30), and the first compressor (12) is connected in a pipeline of the first steam pipe (51).

3. The wastewater evaporative concentration apparatus according to claim 2,

the waste water circulating heat exchange loop (30) comprises a waste water input pipe (31), a circulating conveying pipe (32), a circulating pump (33) and a steam heat exchanger (34);

two ends of the circulating conveying pipe (32) are respectively communicated with the side wall of the first evaporating pot (11), the circulating pump (33) and the steam heat exchanger (34) are sequentially connected into a pipeline of the circulating conveying pipe (32), and output ends of the first steam loop (50) and the second steam loop (60) are respectively connected with the steam heat exchanger (34);

the input end of the waste water input pipe (31) is communicated with the waste water source, and the opposite output end of the waste water input pipe is communicated with the circulating conveying pipe (32) at the front end of the circulating pump (33).

4. The wastewater evaporative concentration apparatus according to claim 3,

the wastewater circulating heat exchange loop (30) also comprises a distilled water heat exchanger (35);

the front end of the waste water input pipe (31) and the rear end of the first steam pipe (51) after penetrating the steam heat exchanger (34) are respectively connected with the distilled water heat exchanger (35).

5. The wastewater evaporative concentration apparatus as set forth in claim 2,

the second evaporation device (20) comprises a second evaporation tank (21) and a second compressor (22);

the input end of the second steam loop (60) is communicated with the second evaporation tank (21), and the opposite output ends of the second steam loop are respectively communicated with the first steam pipe (51) and the second evaporation tank (21).

6. The wastewater evaporative concentration apparatus as set forth in claim 5,

the waste water re-evaporation loop (40) comprises a waste water output pipe (41) and a feeding pump (42);

two ends of the wastewater output pipe (41) are respectively communicated with the first evaporation tank (11) and the second evaporation tank (21);

the feeding pump (42) is connected to the pipeline of the waste water output pipe (41).

7. The wastewater evaporative concentration apparatus as set forth in claim 5,

the second steam loop (60) comprises a steam main (61), a first steam branch pipe (62), a second steam branch pipe (63), a first valve (64) and a second valve (65);

the input end of the steam header pipe (61) is communicated with the top of the second evaporation tank (21), the opposite output ends of the steam header pipe are respectively communicated with the input ends of the first steam branch pipe (62) and the second steam branch pipe (63), the output end of the first steam branch pipe (62) is communicated with the first steam pipe (51), and the output end of the second steam branch pipe (63) is communicated with the side wall of the second evaporation tank (21);

the second compressor (22) is connected to the pipeline of the steam header pipe (61), the first valve (64) is connected to the pipeline of the first steam branch pipe (62), and the second valve (65) is connected to the pipeline of the second steam branch pipe (63).

8. The wastewater evaporative concentration apparatus as set forth in claim 7,

the output end of the second steam branch pipe (63) is communicated with the side wall of the bottom end of the second evaporation tank (21).

9. The wastewater evaporative concentration apparatus as set forth in claim 5,

the second evaporating pot (21) comprises a hollow and sealed pot body (211) and a scraper (212) arranged in the pot body (211);

the scraper (212) rotates along the circumferential direction of the axis of the second evaporation tank (21) so as to prevent evaporated and precipitated substances from adhering to the inner wall surface of the tank body (211).

10. The wastewater evaporative concentration apparatus as set forth in claim 5,

the waste water evaporation and concentration equipment further comprises a concentrated solution discharge loop (70), wherein the input end of the concentrated solution discharge loop (70) is communicated with the bottom end of the second evaporation tank (21), and the opposite output end of the concentrated solution discharge loop is communicated with a device for containing concentrated solution.