Three-section type efficient negative pressure flash evaporation device and working method

Abstract

The invention discloses a three-section type efficient negative pressure flash evaporation device and a working method, which can separate non-condensed gas in slurry in advance, and also can recycle water vapor carried by the non-condensed gas. According to the technical scheme, the tower comprises an upper-section tower body, a middle-section tower body and a lower-section tower body which are sequentially arranged from top to bottom; a primary spraying layer is arranged in the middle-section tower body, and a secondary spraying layer is arranged in the lower-section tower body; a first demister, a second demister and a third demister are respectively arranged in the upper-section tower body, the middle-section tower body and the lower-section tower body; a condensate water recovery device and a non-condensable gas condenser are arranged between the first demister and the second demister; a primary spraying layer is further arranged in the middle-section tower body, a slurry collecting device is arranged in the center of the third demister, and a secondary spraying layer is arranged at the lower end of the slurry channel; a dead steam outlet and a slurry inlet are further formed in the side wall of the middle-section tower body, and a slurry outlet and a vortex breaking device are arranged at the bottom of the lower-section tower body.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial waste heat recovery, and particularly relates to a three-stage high-efficiency negative pressure flash evaporation device and a working method thereof. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] As one of the core technologies in the field of industrial waste heat recovery, flash evaporation technology is currently widely used in industries such as chemical engineering, pharmaceuticals, electric power, and metallurgy. The flash evaporation liquid contains CO 2 , N 2 , O 2 and other non-condensable gases. If these non-condensable gases are not removed, they will seriously affect the quality of the flash-evaporated exhaust steam, resulting in problems such as poor heat transfer effect and large heat exchange equipment selection. For example, the flash evaporation devices used in the field of wet flue gas desulfurization waste heat recovery are mostly single-stage tank designs. This design causes the non-condensable gases in the slurry to be unable to be effectively separated from the exhaust steam, resulting in poor heat transfer coefficient of the exhaust steam and over-sizing of the heat pump selection. Summary of the Invention

[0004] In view of the above problems, the present invention provides a three-stage high-efficiency negative pressure flash evaporation device and a working method thereof, which can separate the non-condensable gases in the slurry in advance, improve the heat transfer coefficient of the exhaust steam, and can also recover and utilize the water vapor carried by the non-condensable gases during the flash evaporation process to increase the flash evaporation temperature of the slurry.

[0005] To achieve the above object, the present invention is realized through the following technical solutions:

[0006] In a first aspect, the present invention provides a three-stage high-efficiency negative pressure flash evaporation device, including: an upper tower body, a middle tower body, and a lower tower body arranged in sequence from top to bottom; a primary spray layer is provided in the middle tower body, and a secondary spray layer is provided in the lower tower body; a first demister is provided at the top of the upper tower body, a second demister is provided between the upper tower body and the middle tower body, and a third demister is provided between the lower tower body and the middle tower body; a condensate recovery device and a non-condensable gas condenser are provided between the first demister and the second demister, and the non-condensable gas condenser is arranged above the condensate recovery device; a primary spray layer is also provided in the middle tower body, a slurry collection device is provided at the central position of the third demister, the upper half of the slurry collection device is funnel-shaped, the lower half is a slurry channel, a vortex breaker is provided in the slurry channel, the lower end of the slurry channel is provided with a secondary spray layer, and the slurry channel is communicated with the secondary slurry spray layer;

[0007] The slurry inlet of the primary spray layer is arranged on the side wall of the middle section tower body. The flash liquid is sprayed through the primary spray layer. A waste steam outlet is also arranged on the side wall of the middle section tower body. A slurry outlet is arranged at the bottom of the lower section tower body, and a vortex breaker is also arranged at the slurry outlet.

[0008] Furthermore, the non-condensable gas condenser is of the tube heat exchanger type. The medium of the non-condensable gas condenser is low-temperature cooling water at 10°C - 20°C, which is used to condense the non-condensable gas carrying water vapor.

[0009] Furthermore, the nozzles of the primary spray layer are large-diameter drip nozzles.

[0010] Furthermore, the pressure inside the middle section tower body is controlled between 8 - 15 kPa by a vacuum pump, and the pressure inside the lower section tower body is controlled between 5 - 7 kPa by a vacuum pump.

[0011] Furthermore, the condensate recovery device is of a horizontal panel structure. Air lifting holes are evenly arranged on the horizontal panel. An air vent pipe is arranged at the air lifting hole. The lower end of the air vent pipe is hermetically connected to the horizontal panel, and an air lifting cap is arranged at the top of the air vent pipe.

[0012] Furthermore, the edge of the horizontal panel is hermetically connected to the side wall of the upper section tower body, and a condensate outlet is arranged on the side wall of the upper section tower body near the upper surface of the horizontal panel.

[0013] Furthermore, the vortex breaker is composed of a circular pipe and two mutually perpendicular rectangular plates arranged inside the circular pipe. The two mutually perpendicular rectangular plates are in a "cross" structure.

[0014] Furthermore, the primary spray layer and the secondary spray layer have the same structure, both being a central radiation type spray layer structure.

[0015] In a second aspect, the present invention also provides a working method of a three-stage high-efficiency negative pressure flash evaporation device, including the following steps:

[0016] S1. The flash liquid enters from the flash liquid inlet of the middle section tower body and is sprayed through the large-diameter drip nozzles of the primary spray layer; the vacuum pump controls the pressure of the middle section tower body between 8 - 15 kPa. The non-condensable gas in the flash liquid is rapidly released due to the sudden pressure drop, and at the same time carries part of the water vapor, making the flash liquid in a slightly boiling state;

[0017] S2. The non-condensable gas carrying water vapor is demisted by the demister in the middle section of the tower body, and then enters the upper section of the tower body through the riser cap. In the upper section of the tower body, the non-condensable gas enters the non-condensable gas condenser and exchanges heat with the low-temperature cooling water tube side at 10°C - 20°C. The water vapor is condensed into condensate, which falls into the upper section of the tower body through the riser cap, is collected and discharged from the condensate outlet, and the clean non-condensable gas is discharged from the non-condensable gas outlet at the top of the upper section of the tower body;

[0018] S3. The flashed liquid after releasing the non-condensable gas falls into the slurry collection device below the middle section of the tower body. The vacuum pump controls the pressure of the lower section of the tower body at 5 - 7 kPa. Under the action of gravity and pressure difference, the flashed liquid enters the secondary spray layer for spraying;

[0019] S4. The flashed liquid entering the lower section of the tower body undergoes negative pressure flashing in an environment with an absolute pressure of 5 - 7 kPa. The exhausted steam after flashing is demisted by the demister in the lower section of the tower body and then discharged from the exhausted steam outlet. The cooled flashed liquid is discharged from the slurry outlet at the lower part of the lower section of the tower body.

[0020] Furthermore, during the discharging process in S3, when the flashed liquid enters the secondary spray layer in the slurry collection device, it needs to pass through the vortex breaker in the slurry channel to break the vortex and prevent entraining air bubbles;

[0021] In S4, when the cooled flashed liquid is discharged from the slurry outlet at the lower part of the lower section of the tower body, it also needs to pass through the vortex breaker at the slurry outlet to break the vortex and prevent entraining air bubbles into the subsequent process equipment to avoid equipment cavitation.

[0022] Compared with the prior art, the advantages and positive effects of the present invention are:

[0023] The present invention realizes three functions of separating non-condensable gas from flashed liquid, flashing of flashed liquid, and cooling of non-condensable gas through a three-stage design, reduces the number of equipment, and lowers the equipment investment cost; The first demister, the second demister, and the third demister can efficiently and deeply remove the water vapor carried by the non-condensable gas and the exhausted steam; The design of the vortex breaker prevents the slurry from carrying non-condensable gas into the next process during low-level operation, and prevents the flashed liquid from entraining air bubbles into the lower section of the tower body or subsequent process equipment, ensuring the safe and stable operation of the equipment and avoiding equipment cavitation.

[0024] The condensate recovery device of the present invention adopts a horizontal panel structure and related designs, so that the condensate will not fall into the slurry in the middle section tower body, causing the temperature of the slurry to drop, thus ensuring that the flashing effect is not affected; the pressure in the middle section tower body and the lower section tower body is accurately controlled by a vacuum pump, providing good conditions for flashing and gas separation; the non-condensable gas condenser adopts a tubular heat exchanger type, and the non-condensable gas carrying water vapor is condensed by low-temperature cooling water at 10°C - 20°C, improving the condensation efficiency; the primary spray layer and the secondary spray layer adopt a central radiation type spray layer structure, and the nozzles of the primary spray layer are large-diameter drip nozzles, which is beneficial to the spraying and subsequent treatment of the flashing liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0026] Figure 1 It is the internal structure diagram of the three-stage high-efficiency negative pressure flashing device of the present invention;

[0027] Figure 2 It is the structure diagram of the vortex breaker of the present invention;

[0028] Figure 3 It is the structure diagram of the spray layer of the present invention.

[0029] In the figure: 1, upper section tower body; 2, middle section tower body; 3, lower section tower body; 4, primary spray layer; 5, secondary spray layer; 6, first demister; 7, second demister; 8, third demister; 9, slurry collection device; 10, vortex breaker; 101, circular pipe; 102, rectangular plate; 11, slurry outlet; 12, horizontal panel; 13, ventilation pipe; 14, riser cap; 15, non-condensable gas condenser; 16, non-condensable gas outlet; 17, exhaust steam outlet; 18, cooling water inlet; 19, cooling water outlet; 20, slurry inlet; 21, condensate outlet; 22, nozzle. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the present invention clearly states otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof;

[0032] This embodiment provides a three-stage high-efficiency negative pressure flash evaporation device, which realizes three functions of separating non-condensable gas from flash liquid, flash evaporation of flash liquid, and cooling of non-condensable gas through a three-stage design. It has high performance, small floor area, and low equipment investment; as Figures 1-3 shown, it includes: an upper tower body 1, a middle tower body 2, and a lower tower body 3 arranged in sequence from top to bottom; a primary spray layer 4 is provided in the middle tower body 2, and a secondary spray layer 5 is provided in the lower tower body 3; a first demister 6 is provided at the top of the upper tower body 1, a second demister 7 is provided between the upper tower body 1 and the middle tower body 2, and a third demister 8 is provided between the lower tower body 3 and the middle tower body 2; a condensate recovery device and a non-condensable gas condenser 15 are provided between the first demister 6 and the second demister 7, and the non-condensable gas condenser 15 is arranged above the condensate recovery device; a primary spray layer 4 is also provided in the middle tower body 2, a slurry collection device 9 is provided at the central position of the third demister 8, the upper half of the slurry collection device 9 is funnel-shaped, the lower half is a slurry channel, a vortex breaker 10 is provided in the slurry channel, a secondary spray layer 5 is provided at the lower end of the slurry channel, and the slurry channel is communicated with the secondary slurry spray layer 5; the first demister 6, the second demister 7, and the third demister 8 can efficiently and deeply remove the non-condensable gas and the water vapor carried by the exhaust steam.

[0033] A non-condensable gas outlet 16 is further provided at the top of the upper tower body 1, the non-condensable gas outlet 16 is arranged above the first demister 6, and the non-condensable gas outlet 16 is used to discharge the gas that has not been condensed by the non-condensable gas condenser 15; the slurry inlet 20 of the primary spray layer 4 is provided on the side wall of the middle tower body 2, the flash liquid is sprayed through the primary spray layer 4, a steam outlet 17 is also provided on the side wall of the middle tower body 2, a slurry outlet 11 is provided at the bottom of the lower tower body 3, and a vortex breaker 10 is also provided at the slurry outlet 11. The design of the vortex breaker 10 can prevent the slurry from carrying non-condensable gas into the next process during low-level operation, affecting the safe operation of the equipment.

[0034] Both ends of the non-condensable gas condenser 15 are respectively provided with a cooling water inlet 18 and a cooling water outlet 19; the non-condensable gas condenser 15 is of a tubular heat exchanger type, and the medium of the non-condensable gas condenser 15 is low-temperature cooling water at 10°C - 20°C, which is used to condense the non-condensable gas carrying water vapor.

[0035] The nozzles 22 of the primary spray layer 4 are large-diameter drip nozzles 22.

[0036] The pressure inside the middle tower body 2 is controlled between 8 - 15 kPa by a vacuum pump, and the pressure inside the lower tower body 3 is controlled between 5 - 7 kPa by a vacuum pump.

[0037] The condensate recovery device is of a horizontal panel 12 structure. The horizontal panel 12 is uniformly provided with air-lifting holes, and ventilation pipes 13 are arranged at the air-lifting holes. The lower ends of the ventilation pipes 13 are hermetically connected to the horizontal panel 12, and air-lifting caps 14 are arranged at the tops of the ventilation pipes 13; the water vapor carried by the non-condensable gas is condensed in the non-condensable gas condenser 15 in the upper tower body 1, and the condensed condensate is collected in the condensate recovery device in the upper tower body 1, and will not fall into the slurry in the middle tower body 2 of the three-stage high-efficiency negative pressure flash evaporation device to cause the slurry temperature to drop and affect the flash evaporation effect.

[0038] The edge of the horizontal panel 12 is hermetically connected to the side wall of the upper tower body 1, and a condensate outlet is arranged on the side wall of the upper tower body 1 near the upper surface of the horizontal panel 12.

[0039] The vortex breaker 10 is composed of a circular pipe 101 and two mutually perpendicular rectangular plates 102 arranged inside the circular pipe 101, and the two mutually perpendicular rectangular plates 102 are in a "cross" structure. The vortex breaker 10 in the middle tower body 2 is used to break the vortex to prevent the flash evaporation liquid from carrying bubbles into the lower tower body 3, and the vortex breaker 10 in the lower tower body 3 is used to break the vortex during the slurry discharge process to prevent the flash evaporation liquid from carrying bubbles into the subsequent process equipment.

[0040] The primary spray layer 4 and the secondary spray layer 5 have the same structure, and both are central radiation type spray layer structures.

[0041] The present invention also provides a working method of a three-stage high-efficiency negative pressure flash evaporation device, including the following steps:

[0042] S1. The flash evaporation liquid enters from the flash evaporation liquid inlet of the middle tower body 2 and is sprayed by the large-diameter drip nozzles 21 of the primary spray layer 4; the vacuum pump controls the pressure of the middle tower body 2 between 8 - 15 kPa, and the non-condensable gas in the flash evaporation liquid is rapidly released due to the sudden drop in pressure, and at the same time carries part of the water vapor, making the flash evaporation liquid in a slightly boiling state;

[0043] S2. The non-condensable gas carrying water vapor is demisted by the demister in the middle tower body 2, and then enters the upper tower body 1 through the riser cap 14. In the upper tower body 1, the non-condensable gas enters the non-condensable gas condenser 15 and exchanges heat with the low-temperature cooling water tube side at 10°C - 20°C. The water vapor is condensed into condensate, which falls into the condensate recovery device through the riser cap 14, is collected and discharged from the condensate outlet 21, and the clean non-condensable gas is discharged from the non-condensable gas outlet 16 at the top of the upper tower body 1;

[0044] S3. The flashed liquid after releasing the non-condensable gas falls into the slurry collection device 9 below the middle tower body 2. The vacuum pump controls the pressure in the lower tower body 3 at 5 - 7 kPa. Under the action of gravity and pressure difference, the flashed liquid enters the secondary spray layer 5 for spraying;

[0045] S4. The flashed liquid entering the lower tower body 3 undergoes negative pressure flashing in an environment with an absolute pressure of 5 - 7 kPa. The exhausted steam after flashing is demisted by the demister in the lower tower body 3 and then discharged from the exhausted steam outlet 17, and the cooled flashed liquid is discharged from the slurry outlet 11 at the lower part of the lower tower body 3.

[0046] During the discharging process in S3, when the flashed liquid enters the secondary spray layer 5 in the slurry collection device 9, it needs to pass through the vortex breaker 10 in the slurry channel to break the vortex and prevent entraining air bubbles;

[0047] In S4, when the cooled flashed liquid is discharged from the slurry outlet 11 at the lower part of the lower tower body 3, it also needs to pass through the vortex breaker 10 at the slurry outlet 11 to break the vortex and prevent entraining air bubbles into the subsequent process equipment to avoid equipment cavitation.

[0048] Although the specific implementation manners of the present invention are described above in conjunction with the drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A three-stage high-efficiency negative pressure flash evaporation device, characterized in that: It comprises an upper tower body, a middle tower body and a lower tower body which are arranged in sequence from top to bottom; a primary spray layer is arranged in the middle tower body, and a secondary spray layer is arranged in the lower tower body; a first demister is arranged on the top of the upper tower body, a second demister is arranged between the upper tower body and the middle tower body, and a third demister is arranged between the lower tower body and the middle tower body; a condensate recovery device and a non-condensable gas condenser are arranged between the first demister and the second demister, and the non-condensable gas condenser is arranged above the condensate recovery device; a primary spray layer is also arranged in the middle tower body, and a slurry collecting device is arranged at the center position of the third demister, the upper half of the slurry collecting device is funnel-shaped, and the lower half is a slurry channel, a vortex breaker is arranged in the slurry channel, a secondary spray layer is arranged at the lower end of the slurry channel, and the slurry channel is connected to the slurry secondary spray layer; The slurry inlet of the primary spray layer is arranged on the side wall of the middle tower body, and the flash liquid is sprayed through the primary spray layer. A waste steam outlet is also arranged on the side wall of the middle tower body. A slurry outlet is arranged at the bottom of the lower tower body, and a vortex breaker is also arranged at the slurry outlet.

2. A three-stage high-efficiency negative pressure flash evaporation device as claimed in claim 1, characterized in that: The non-condensable gas condenser is a tubular heat exchanger type, and the medium of the non-condensable gas condenser is low-temperature cooling water of 10° C.-20° C., which is used to condense the non-condensable gas carrying water vapor.

3. A three-stage high-efficiency negative pressure flash evaporation device as claimed in claim 1, characterized in that: The nozzle of the primary spray layer is a large-caliber drip nozzle.

4. A three-stage high-efficiency negative pressure flash evaporation device as claimed in claim 1, characterized in that: The pressure in the middle tower body is controlled between 8-15 kPa by a vacuum pump, and the pressure in the lower tower body is controlled between 5-7 kPa by a vacuum pump.

5. A three-stage high-efficiency negative pressure flash evaporation device as claimed in claim 1, characterized in that: The condensate recovery device is a horizontal panel structure, the horizontal panel is evenly provided with air rise holes, the air rise holes are provided with ventilation pipes, the lower end of the ventilation pipe is sealed and connected to the horizontal panel, and the top of the ventilation pipe is provided with an air rise cap.

6. A three-stage high-efficiency negative pressure flash evaporation device as claimed in claim 5, characterized in that: The edge of the horizontal panel is sealed and connected to the side wall of the upper tower body, and a condensed water outlet is arranged on the side wall of the upper tower body near the upper surface of the horizontal panel.

7. A three-stage high-efficiency negative pressure flash evaporation device as claimed in claim 1, characterized in that: The vortex breaker consists of a circular pipe and two mutually perpendicular rectangular plates arranged in the circular pipe, and the two mutually perpendicular rectangular plates are in a "cross" structure.

8. A three-stage high-efficiency negative pressure flash evaporation device as claimed in claim 1, characterized in that: The primary spray layer and the secondary spray layer have the same structure, both of which are central radiation spray layer structures.

9. A working method of a three-stage high-efficiency negative pressure flash evaporation device according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Flash liquid enters from the flash liquid inlet of the middle tower body and is sprayed through the large-diameter drip nozzle of the primary spray layer; the vacuum pump controls the pressure of the middle tower body at 8-15kPa, and the non-condensable gas in the flash liquid is rapidly released due to the sudden pressure drop, while carrying part of the water vapor, making the flash liquid slightly boiling; S2. The non-condensable gas carrying water vapor passes through the middle tower body demister for defogger, and then enters the upper tower body through the gas lift cap; in the upper tower body, the non-condensable gas enters the non-condensable gas condenser, exchanges heat with the low-temperature cooling water pipe of 10℃-20℃, and the water vapor is condensed into condensed water, which falls into the upper tower body through the gas lift cap, is collected and discharged from the condensed water outlet, and the clean non-condensable gas is discharged from the non-condensable gas outlet at the top of the upper tower body; S3. After releasing the non-condensable gas, the flash liquid falls into the slurry collection device below the middle tower body. The vacuum pump controls the pressure of the lower tower body at 5-7kPa. Under the action of gravity and pressure difference, the flash liquid enters the secondary spray layer for spraying; S4. The flash liquid entering the lower tower body is flashed at negative pressure under an absolute pressure of 5-7 kPa. The exhaust steam after flashing is defogged by the demister of the lower tower body and then discharged from the exhaust steam outlet. The flash liquid after cooling is discharged from the slurry outlet at the lower part of the lower tower body.

10. The steam waste heat recovery method according to claim 9, characterized in that: During the discharge process in S3, the flash liquid needs to pass through the vortex breaker in the slurry channel to break the vortex when entering the secondary spray layer in the slurry collection device to prevent air bubbles from being entrained; In S4, when the cooled flash liquid is discharged from the slurry outlet at the lower part of the lower tower body, it also needs to pass through the vortex breaker at the slurry outlet to break the vortex to prevent air bubbles from entering the subsequent process equipment and avoid equipment cavitation.

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