Tail gas recovery system and method of multi-effect evaporator

Abstract

The invention provides a tail gas recovery system and method of a multi-effect evaporator. The system comprises a heat pump, a first end of the heat pump is sequentially provided with a tail gas inlet, a first exhaust port and a first water outlet from top to bottom; the second end of the heat pump is sequentially provided with a second water outlet and a water supplementing inlet from top to bottom. Wherein the first end and the second end are oppositely arranged; the gas recovery device is connected with the first exhaust port; the water recovery device is connected with the first water outlet; the first end of the flash evaporation device is connected with the second water outlet; the second end of the flash evaporation device is connected with the water replenishing inlet; the third end of the flash evaporation device is provided with a steam exhaust port, the third end of the flash evaporation device is the top end of the flash evaporation device, and the arrangement position of the first end of the flash evaporation device is higher than that of the second end. According to the system, multiple-effect evaporation tail steam is introduced into the heat pump, tail steam waste heat which is not prone to being recycled at the low temperature position is recycled, the utilization efficiency of energy is improved, and the production and operation cost is reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of waste heat recovery and utilization, and in particular to a tail steam recovery system and method for a multiple-effect evaporator. Background Art

[0002] A multiple-effect evaporator is a device that uses the heat of steam to evaporate liquids. Its operating principle is to circulate steam through multiple evaporators, allowing the steam from each effect to be utilized by subsequent effects, thereby significantly improving thermal energy utilization efficiency. Traditional multiple-effect evaporation systems typically generate large amounts of exhaust vapor when processing concentrated liquids. This exhaust vapor contains a large amount of latent heat of vaporization, and discharging this waste heat into the atmosphere would result in heat waste. Summary of the Invention

[0003] The embodiment of the present invention provides a tail steam recovery system and method for a multiple-effect evaporator, so as to solve the problem that the tail steam of the existing multiple-effect evaporator contains a large amount of latent heat of vaporization and the waste heat is discharged into the atmosphere, resulting in heat waste.

[0004] In order to solve the above-mentioned technical problems, the present invention is achieved as follows:

[0005] In a first aspect, an embodiment of the present invention provides a tail steam recovery system for a multiple-effect evaporator, comprising:

[0006] A heat pump, wherein a first end of the heat pump is provided with an exhaust steam inlet, a first exhaust port, and a first drain port in order from top to bottom; a second end of the heat pump is provided with a second drain port and a water supply inlet in order from top to bottom; wherein the first end and the second end are arranged opposite to each other;

[0007] a gas recovery device connected to the first exhaust port;

[0008] a water recovery device connected to the first drain outlet;

[0009] A flash evaporation device, wherein the first end of the flash evaporation device is connected to the second drain outlet; the second end of the flash evaporation device is connected to the water replenishment inlet; the third end of the flash evaporation device is provided with a steam exhaust outlet, the third end of the flash evaporation device is the top end of the flash evaporation device, and the first end of the flash evaporation device is provided at a position higher than the second end.

[0010] Optionally, the heat pump includes: an evaporator and a condenser; the evaporator and the condenser are connected;

[0011] The evaporator is located at the first end of the heat pump, and the exhaust steam inlet, the first exhaust port and the first drain port are arranged on a side of the evaporator away from the condenser;

[0012] The condenser is located at the second end of the heat pump, and the second drain port and the water replenishment inlet are arranged on a side of the condenser away from the evaporator.

[0013] Optionally, the gas recovery device includes a first pipe and a vacuum pump, the first end of the first pipe is connected to the first exhaust port, and the second end of the first pipe is connected to the vacuum pump.

[0014] Optionally, the water recovery device includes a second pipe and a water tank, the first end of the second pipe is connected to the first drain outlet, and the second end of the second pipe is connected to the water tank.

[0015] Optionally, the flash evaporation device includes a flash evaporation tank, a water replenishing device, a third pipeline and a fourth pipeline;

[0016] The first end of the flash tank is connected to the second drain outlet through the third pipe, the bottom end of the flash tank is connected to the first end of the fourth pipe, the second end of the fourth pipe is connected to the water replenishment inlet, and the third end of the fourth pipe is connected to the water replenishment device; a steam exhaust port is provided at the top of the flash tank.

[0017] Optionally, the flash evaporation device further includes a pipeline pump, which is arranged between the water replenishment device and the water replenishment inlet, and the pipeline pump is unidirectionally conducted from the water replenishment device to the water replenishment inlet.

[0018] In a second aspect, an embodiment of the present invention provides a method for recovering tail steam from a multiple-effect evaporator, using the tail steam recovery system of the multiple-effect evaporator as described in any one of the first aspects, the method comprising:

[0019] The tail steam of the multi-effect evaporator is input into the heat pump from the tail steam inlet;

[0020] The heat pump performs a first heat exchange, so that the tail steam of the multi-effect evaporator is condensed from a vapor state to a liquid state, thereby obtaining liquid tail steam and non-condensable gas;

[0021] Discharge the non-condensable gas from the first exhaust port to the gas recovery device; discharge the liquid tail gas from the first drain port to the water recovery device;

[0022] Desalted water is replenished to the water replenishment inlet through the second end of the flash evaporation device, and the heat pump performs a second heat exchange to heat the desalted water replenishment to obtain hot water, which is discharged back to the flash evaporation device from the second drain port 4, and the gas is flashed out through the flash evaporation device and discharged from the steam exhaust port at the third end of the flash evaporation device.

[0023] Optionally, the heat pump includes: an evaporator and a condenser; the evaporator and the condenser are connected;

[0024] The first heat exchange of the heat pump is achieved through the evaporator; and the second heat exchange of the heat pump is achieved through the condenser.

[0025] Optionally, also include:

[0026] The non-condensable gas is pumped from the first exhaust port to the gas recovery device through a vacuum pump in the gas recovery device.

[0027] Optionally, the pressure of water supplied to the water supply inlet by the pipeline pump in the flash evaporation device is set to be no less than 2 bar.

[0028] In the present invention, a heat pump is provided, wherein a tail steam inlet, a first exhaust port, and a first drain port are sequentially provided at the first end of the heat pump from top to bottom; a second drain port and a water supply inlet are sequentially provided at the second end of the heat pump from top to bottom; wherein the first end and the second end are arranged opposite to each other; a gas recovery device is connected to the first exhaust port; a water recovery device is connected to the first drain port; a flash device is connected to the first end and the second drain port; and the second end of the flash device is connected to the water supply inlet; a steam exhaust port is provided at the third end of the flash device, the third end of the flash device is the top end of the flash device, and the first end of the flash device is arranged at a higher position than the second end. In the present invention, by introducing the tail steam of the multi-effect evaporation into the heat pump, the waste heat of the tail steam that is difficult to recover at a low temperature is recovered, thereby improving the utilization efficiency of energy, reducing production and operation costs, and solving the problem that the tail steam of the existing multi-effect evaporator contains a large amount of latent heat of vaporization and the waste heat is discharged into the atmosphere, resulting in heat waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0030] Figure 1 This is a structural diagram of a tail steam recovery system of a multiple-effect evaporator provided in an embodiment of the present invention;

[0031] Figure 2 The present invention provides a flowchart of a method for recovering tail steam from a multiple-effect evaporator. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] Please refer to Figure 1 , an embodiment of the present invention provides a tail steam recovery system for a multiple-effect evaporator, comprising:

[0034] The heat pump 10 has a first end provided with an exhaust steam inlet 1, a first exhaust port 2, and a first drain port 3 from top to bottom; a second end provided with a second drain port 4 and a water supply inlet 5 from top to bottom; wherein the first end and the second end are arranged opposite to each other;

[0035] In the embodiment of the present invention, optionally, the heat pump 10 includes: an evaporator 101 and a condenser 102; the evaporator 101 and the condenser 102 are connected;

[0036] The evaporator 101 is located at the first end of the heat pump 10, and the exhaust gas inlet 1, the first exhaust port 2 and the first drain port 3 are arranged on the side of the evaporator 101 away from the condenser 102;

[0037] The condenser 102 is located at the second end of the heat pump 10 , and the second drain port 4 and the water replenishment inlet 5 are arranged on a side of the condenser 102 away from the evaporator 101 .

[0038] In an embodiment of the present invention, the tail steam A of the multi-effect evaporator at 55°C is input into the evaporator 101 of the heat pump 10 from the tail steam inlet 1, wherein the evaporator 101 can be designed to be 45°C according to actual conditions, so that there is a certain temperature difference between the evaporator 101 and the tail steam A of the multi-effect evaporator, thereby condensing the tail steam from a vapor state to a liquid state.

[0039] The first end of the heat pump 10 is provided with an exhaust steam inlet 1, a first exhaust port 2 and a first drain port 3 in sequence from top to bottom, so that the exhaust steam A of the multi-effect evaporator can be introduced from the top and discharged from the bottom. The reasonable exhaust gas flow design can optimize the airflow path, reduce the backflow of exhaust gas and improve the recovery efficiency.

[0040] A gas recovery device 20 connected to the first exhaust port 2;

[0041] In an embodiment of the present invention, optionally, the gas recovery device includes a first pipe 201 and a vacuum pump (not shown in the figure), the first end of the first pipe 201 is connected to the first exhaust port 2, and the second end of the first pipe 201 is connected to the vacuum pump.

[0042] In an embodiment of the present invention, after the tail steam A of the multi-effect evaporator passes through the evaporator 101 for heat exchange, the tail steam releases the latent heat of phase change, condenses from vapor to liquid, and enters the water recovery device 30, while the separated non-condensable gas B is extracted by a vacuum pump. By recovering the non-condensable gas B, it can be reused in the production process, reducing resource waste and improving the efficiency of raw material utilization. By optimizing the recovery and utilization of the gas, the efficiency of the overall production process can be improved, promoting a more stable production process.

[0043] A water recovery device 30 is connected to the first drain port 3;

[0044] In the embodiment of the present invention, optionally, the water recovery device includes a second pipe 301 and a water tank 302 , a first end of the second pipe 301 is connected to the first drain port 3 , and a second end of the second pipe 301 is connected to the water tank 302 .

[0045] In the embodiment of the present invention, after the tail steam A of the multi-effect evaporator passes through the evaporator 101 for heat exchange, the tail steam releases the latent heat of phase change, condenses from vapor to liquid, and enters the water recovery device 30. By condensing the tail steam A of the multi-effect evaporator into liquid water, the water generated during the evaporation process can be effectively recovered, the waste of water resources can be reduced, and the overall water utilization efficiency can be improved. In addition, the heat taken away by the tail steam A of the multi-effect evaporator during the evaporation process can be used to heat other liquids, thereby improving the thermal efficiency of the system and reducing energy consumption; and a certain liquid level is formed in the water tank 302 to act as a water seal, effectively preventing the tail steam A of the multi-effect evaporator from flowing back, thereby improving the heat exchange efficiency.

[0046] The flash evaporation device 40 has a first end 7 connected to the second drain outlet 4; a second end 8 of the flash evaporation device 40 is connected to the water replenishment inlet 5; a steam exhaust port 6 is provided at the third end of the flash evaporation device 40, and the third end of the flash evaporation device 40 is the top end of the flash evaporation device 40, and the first end 7 of the flash evaporation device 40 is provided at a position higher than the second end 8.

[0047] In the embodiment of the present invention, optionally, the flash evaporation device 40 includes a flash evaporation tank 401, a water replenishing device 402, a third pipeline 403 and a fourth pipeline 404;

[0048] The first end 7 of the flash tank 401 is connected to the second drain outlet 4 through the third pipe, the bottom end of the flash tank 401 is connected to the first end of the fourth pipe 404, the second end of the fourth pipe is connected to the water replenishment inlet 5, and the third end of the fourth pipe 404 is connected to the water replenishment device 402; a steam exhaust port 6 is provided at the top of the flash tank.

[0049] In the embodiment of the present invention, optionally, the flash evaporation device further includes a pipeline pump 405 , which is arranged between the water replenishment device 402 and the water replenishment inlet 5 , and the pipeline pump 405 is unidirectionally conducted from the water replenishment device 402 to the water replenishment inlet 5 .

[0050] In an embodiment of the present invention, the water replenishment device 402 replenishes desalted water to the tail steam recovery system of the multi-effect evaporator and replenishes it into the condenser 102 of the heat pump 10. The replenishment water pressure can be set to no less than 2 bar according to actual conditions, and circulates through the pipeline pump 405. Hot water with a maximum temperature of 120°C is generated through the condenser 102 of the heat pump 10. The hot water enters the flash tank 401, and the flashed steam is transported to the required occasion through the steam exhaust port 6 through the pipeline. The condensed water after flashing enters the condenser 102 of the heat pump 10 again through the pipeline pump 405 for heat extraction circulation. The steam generated by flash evaporation can be used for other process steps, such as driving a steam turbine generator, heating other liquids or gases, etc., further improving the energy efficiency of the system. By recovering the heat energy of the tail steam by flash evaporation, the overall energy efficiency of the multi-effect evaporator can be significantly improved, energy consumption can be reduced, and the flash evaporation process makes effective use of the heat of the tail steam, reduces resource waste, improves energy utilization efficiency, and thus reduces production and operation costs.

[0051] In an embodiment of the present invention, a heat pump is provided, wherein a tail steam inlet, a first exhaust port, and a first drain port are sequentially provided at the first end of the heat pump from top to bottom; a second drain port and a water supply inlet are sequentially provided at the second end of the heat pump from top to bottom; wherein the first end and the second end are arranged relative to each other; a gas recovery device is connected to the first exhaust port; a water recovery device is connected to the first drain port; a flash device is connected to the first end and the second drain port; the second end of the flash device is connected to the water supply inlet; a steam exhaust port is provided at the third end of the flash device, the third end of the flash device is the top end of the flash device, and the first end of the flash device is arranged at a higher position than the second end. In the present invention, by introducing the tail steam of the multi-effect evaporation into the heat pump, the waste heat of the tail steam that is difficult to recover at a low temperature is recovered, thereby improving the utilization efficiency of energy, reducing production and operation costs, and solving the problem that the tail steam of the existing multi-effect evaporator contains a large amount of latent heat of vaporization and the waste heat is discharged into the atmosphere, resulting in heat waste.

[0052] Please refer to Figure 2 The embodiment of the present invention provides a method for recovering tail steam from a multi-effect evaporator, which can be applied as follows: Figure 1 A tail steam recovery system for a multiple-effect evaporator, the method comprising:

[0053] Step 21: The tail steam A of the multi-effect evaporator is input into the heat pump from the tail steam inlet 1;

[0054] In the embodiment of the present invention, the first end of the heat pump 10 is provided with an exhaust steam inlet 1, a first exhaust port 2, and a first drain port 3 in sequence from top to bottom; the second end of the heat pump 10 is provided with a second drain port 4 and a water supply inlet 5 in sequence from top to bottom; wherein the first end and the second end are arranged opposite to each other;

[0055] In the embodiment of the present invention, optionally, the heat pump 10 includes: an evaporator 101 and a condenser 102; the evaporator 101 and the condenser 102 are connected;

[0056] The first heat exchange of the heat pump 10 is achieved through the evaporator 101 ; the second heat exchange of the heat pump 10 is achieved through the condenser 102 .

[0057] In an embodiment of the present invention, the evaporator 101 is located at the first end of the heat pump 10, and the exhaust steam inlet 1, the first exhaust port 2 and the first drain port 3 are arranged on the side of the evaporator 101 away from the condenser 102; the condenser 102 is located at the second end of the heat pump 10, and the second drain port 4 and the water supply inlet 5 are arranged on the side of the condenser 102 away from the evaporator 101.

[0058] Step 22: The heat pump 10 performs the first heat exchange, condensing the tail steam A of the multi-effect evaporator from a vapor state into a liquid state, thereby obtaining liquid tail steam and non-condensable gas;

[0059] In this embodiment of the present invention, exhaust vapor A from a multi-effect evaporator at 55°C is fed through exhaust vapor inlet 1 into evaporator 101 of heat pump 10. Evaporator 101 can be designed to be at 45°C, depending on practical needs, to create a certain temperature difference between evaporator 101 and the exhaust vapor A from the multi-effect evaporator, thereby condensing the exhaust vapor from a vapor state to a liquid state. The first end of heat pump 10 is provided with exhaust vapor inlet 1, first exhaust port 2, and first drain port 3, sequentially from top to bottom, allowing exhaust vapor A from the multi-effect evaporator to enter from the top and exit from the bottom. A rational exhaust gas flow design optimizes the airflow path, reduces exhaust gas backflow, and improves recovery efficiency.

[0060] Step 23: Discharge the non-condensable gas from the first exhaust port 2 to the gas recovery device 20; discharge the liquid tail gas from the first drain port 3 to the water recovery device 30;

[0061] In the embodiment of the present invention, optionally, the method further includes:

[0062] The non-condensable gas is drawn from the first exhaust port 2 to the gas recovery device 20 by a vacuum pump in the gas recovery device 20 .

[0063] In an embodiment of the present invention, the gas recovery device includes a first pipe 201 and a vacuum pump (not shown in the figure), the first end of the first pipe 201 is connected to the first exhaust port 2, and the second end of the first pipe 201 is connected to the vacuum pump; the water recovery device 30 includes a second pipe 301 and a water tank 302, the first end of the second pipe 301 is connected to the first drain port 3, and the second end of the second pipe 301 is connected to the water tank 302.

[0064] In an embodiment of the present invention, after the tail steam A of the multi-effect evaporator passes through the evaporator 101 for heat exchange, the tail steam releases the latent heat of phase change, condenses from vapor to liquid, and enters the water recovery device 30, and the separated non-condensable gas B is extracted by a vacuum pump. By recovering the non-condensable gas B, it can be reused in the production process, reducing resource waste and improving the utilization efficiency of raw materials. By optimizing the recovery and utilization of gas, the efficiency of the overall production process can be improved and a more stable production process can be promoted; by condensing the tail steam A of the multi-effect evaporator into liquid water, the moisture generated during the evaporation process can be effectively recovered, reducing the waste of water resources and improving the overall water utilization efficiency, and the heat taken away by the tail steam A of the multi-effect evaporator during the evaporation process can be used to heat other liquids, thereby improving the thermal efficiency of the system and reducing energy consumption; and a certain liquid level is formed in the water tank 302 to act as a water seal, effectively preventing the backflow of the tail steam A of the multi-effect evaporator, thereby improving the heat exchange efficiency.

[0065] Step 24: Desalted water is replenished to the water inlet 5 through the second end 8 of the flash evaporation device 40, and the heat pump 10 performs a second heat exchange to increase the temperature of the desalted water to obtain hot water, which is discharged back to the flash evaporation device 40 from the second drain port 4, and the gas is flashed out through the flash evaporation device 40 and discharged from the steam exhaust port 6 at the third end of the flash evaporation device 40.

[0066] In the embodiment of the present invention, optionally, the pressure of water supplied to the water supply inlet 5 by the pipeline pump 405 in the flash evaporation device is set to be no less than 2 bar.

[0067] In the embodiment of the present invention, the flash evaporation device 40 includes a flash evaporation tank 401, a water replenishing device 402, a third pipeline 403 and a fourth pipeline 404;

[0068] The first end 7 of the flash tank 401 is connected to the second drain outlet 4 through a third pipe, the bottom end of the flash tank 401 is connected to the first end of the fourth pipe 404, the second end of the fourth pipe is connected to the water replenishment inlet 5, and the third end of the fourth pipe 404 is connected to the water replenishment device 402; a steam exhaust port 6 is provided at the top of the flash tank; the flash device also includes a pipeline pump 405, which is provided between the water replenishment device 402 and the water replenishment inlet 5, and the pipeline pump 405 is unidirectionally conducted from the water replenishment device 402 to the water replenishment inlet 5.

[0069] In an embodiment of the present invention, the water replenishment device 402 replenishes desalted water to the tail steam recovery system of the multi-effect evaporator and replenishes it into the condenser 102 of the heat pump 10. The replenishment water pressure can be set to no less than 2 bar according to actual conditions, and circulates through the pipeline pump 405. Hot water with a maximum temperature of 120°C is generated through the condenser 102 of the heat pump 10. The hot water enters the flash tank 401, and the flashed steam is transported to the required occasion through the steam exhaust port 6 through the pipeline. The condensed water after flashing enters the condenser 102 of the heat pump 10 again through the pipeline pump 405 for heat extraction circulation. The steam generated by flash evaporation can be used for other process steps, such as driving a steam turbine generator, heating other liquids or gases, etc., further improving the energy efficiency of the system. By recovering the heat energy of the tail steam by flash evaporation, the overall energy efficiency of the multi-effect evaporator can be significantly improved, energy consumption can be reduced, and the flash evaporation process makes effective use of the heat of the tail steam, reduces resource waste, improves energy utilization efficiency, and thus reduces production and operation costs.

[0070] In an embodiment of the present invention, the tail steam of the multi-effect evaporator is combined with a heat pump system to effectively recover the heat in the tail steam, which is then reused after raising its temperature through the heat pump to generate new steam, thereby improving the overall energy efficiency of the system, reducing production costs, and improving resource utilization.

[0071] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0072] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0073] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A tail steam recovery system for a multiple-effect evaporator, characterized in that: include: A heat pump, wherein a first end of the heat pump is provided with an exhaust steam inlet, a first exhaust port, and a first drain port in order from top to bottom; a second end of the heat pump is provided with a second drain port and a water supply inlet in order from top to bottom; wherein the first end and the second end are arranged opposite to each other; a gas recovery device connected to the first exhaust port; a water recovery device connected to the first drain outlet; A flash evaporation device, wherein the first end of the flash evaporation device is connected to the second drain outlet; the second end of the flash evaporation device is connected to the water replenishment inlet; the third end of the flash evaporation device is provided with a steam exhaust outlet, the third end of the flash evaporation device is the top end of the flash evaporation device, and the first end of the flash evaporation device is provided at a position higher than the second end.

2. The tail steam recovery system of the multiple-effect evaporator according to claim 1, characterized in that: The heat pump comprises: an evaporator and a condenser; the evaporator and the condenser are connected; The evaporator is located at the first end of the heat pump, and the exhaust steam inlet, the first exhaust port and the first drain port are arranged on a side of the evaporator away from the condenser; The condenser is located at the second end of the heat pump, and the second drain port and the water replenishment inlet are arranged on a side of the condenser away from the evaporator.

3. The tail steam recovery system of the multiple-effect evaporator according to claim 1, characterized in that: The gas recovery device includes a first pipeline and a vacuum pump. The first end of the first pipeline is connected to the first exhaust port, and the second end of the first pipeline is connected to the vacuum pump.

4. The tail steam recovery system of the multiple-effect evaporator according to claim 1, characterized in that: The water recovery device includes a second pipe and a water tank, the first end of the second pipe is connected to the first drain port, and the second end of the second pipe is connected to the water tank.

5. The tail steam recovery system of the multiple-effect evaporator according to claim 1, characterized in that: The flash evaporation device includes a flash evaporation tank, a water replenishing device, a third pipeline and a fourth pipeline; The first end of the flash tank is connected to the second drain outlet through the third pipe, the bottom end of the flash tank is connected to the first end of the fourth pipe, the second end of the fourth pipe is connected to the water replenishment inlet, and the third end of the fourth pipe is connected to the water replenishment device; a steam exhaust port is provided at the top of the flash tank.

6. The tail steam recovery system of the multiple-effect evaporator according to claim 5, characterized in that: The flash evaporation device further includes a pipeline pump, which is arranged between the water replenishment device and the water replenishment inlet, and the pipeline pump is unidirectionally conducted from the water replenishment device to the water replenishment inlet.

7. A method for recovering tail steam from a multiple-effect evaporator, characterized in that: The tail steam recovery system of the multiple-effect evaporator according to any one of claims 1 to 6 is used, and the method comprises: The tail steam of the multi-effect evaporator is input into the heat pump from the tail steam inlet; The heat pump performs a first heat exchange, so that the tail steam of the multi-effect evaporator is condensed from a vapor state to a liquid state, thereby obtaining liquid tail steam and non-condensable gas; Discharge the non-condensable gas from the first exhaust port to the gas recovery device; discharge the liquid tail gas from the first drain port to the water recovery device; Desalted water is replenished to the water replenishment inlet through the second end of the flash evaporation device, and the heat pump performs a second heat exchange to heat the desalted water replenishment to obtain hot water, which is discharged back to the flash evaporation device from the second drain port 4, and the gas is flashed out through the flash evaporation device and discharged from the steam exhaust port at the third end of the flash evaporation device.

8. The tail steam recovery method of the multiple-effect evaporator according to claim 7, characterized in that: The heat pump comprises: an evaporator and a condenser; the evaporator and the condenser are connected; The first heat exchange of the heat pump is achieved through the evaporator; and the second heat exchange of the heat pump is achieved through the condenser.

9. The tail steam recovery method of the multiple-effect evaporator according to claim 7, characterized in that: Also includes: The non-condensable gas is pumped from the first exhaust port to the gas recovery device through a vacuum pump in the gas recovery device.

10. The tail steam recovery method of the multiple-effect evaporator according to claim 7, characterized in that: The pressure of water supplied to the water supply inlet by the pipeline pump in the flash evaporation device is set to be no less than 2 bar.

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