Black water flash evaporation waste heat recovery system

Abstract

The invention relates to the technical field of coal gasification and oil gasification black water systems, and discloses a black water flash evaporation waste heat recovery system and method.The waste heat recovery system comprises a high-pressure evaporation hot water tower, a low-pressure evaporation hot water tower arranged on the downstream portion of the high-pressure evaporation hot water tower and a vacuum flash evaporator arranged on the downstream portion of the low-pressure evaporation hot water tower, a first-stage flash steam outlet positioned at the top end of the high-pressure evaporation hot water tower is directly connected with a second lower tower positioned at the bottom of the low-pressure evaporation hot water tower so as to increase the temperature of circulating grey water in the high-pressure evaporation hot water tower and the low-pressure evaporation hot water tower; and a first-stage black water outlet positioned at the bottom end of the high-pressure evaporation hot water tower is communicated with a second lower tower positioned at the bottom of the low-pressure evaporation hot water tower. According to the scheme, the heat of the flash steam is better utilized, a black water flash evaporation waste heat recovery system is further optimized, meanwhile, the flash steam subjected to high-pressure flash evaporation does not need to be cooled and subjected to liquid separation through a water cooler and a liquid separation tank, and the equipment cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of coal gasification and oil gasification black water systems, and in particular to a black water flash evaporation waste heat recovery system. Background Art

[0002] At present, black water in the field of coal gasification and oil gasification is mainly treated by two-stage or three-stage flash evaporation. The flash gas is condensed by the heat exchanger and the condensate is recovered to enter the next stage of flash evaporation. Finally, the non-condensed steam is discharged. The black water after flash evaporation is reused after sedimentation. In this process, a large amount of heat is generated by the high-temperature and high-pressure black water pressure reduction flash evaporation. In addition to being used to heat the gray water temperature, part of the heat is absorbed by the water cooler and cannot be effectively utilized. At the same time, the flash gas after high-pressure flash evaporation also needs a water cooler and a liquid separator to cool and separate the liquid, which has a high equipment cost. Summary of the invention

[0003] The technical problem to be solved by the present invention is that the prior art black water flash evaporation waste heat recovery system does not effectively recover and utilize the flash steam heat of the high-pressure evaporation hot water tower.

[0004] In order to achieve the above-mentioned purpose, the present invention provides a black water flash evaporation waste heat recovery system, which comprises a high-pressure evaporation hot water tower, a low-pressure evaporation hot water tower arranged downstream of the high-pressure evaporation hot water tower, and a vacuum flash evaporator arranged downstream of the low-pressure evaporation hot water tower, wherein the high-pressure evaporation hot water tower, the low-pressure evaporation hot water tower, and the vacuum flash evaporator are used to perform primary flash evaporation, secondary flash evaporation, and tertiary flash evaporation on high-pressure black water in sequence, and the primary flash gas outlet located at the top of the high-pressure evaporation hot water tower is directly connected to the second lower tower located at the bottom of the low-pressure evaporation hot water tower to increase the temperature of the circulating gray water in the high-pressure evaporation hot water tower and the low-pressure evaporation hot water tower, and the primary black water outlet located at the bottom of the high-pressure evaporation hot water tower is connected to the second lower tower located at the bottom of the low-pressure evaporation hot water tower.

[0005] In some embodiments, the secondary flash gas outlet at the top of the low-pressure evaporation hot water tower is connected to an acid gas separator to separate a first gas phase and a first liquid phase, the secondary black water outlet at the bottom of the low-pressure evaporation hot water tower is connected to the vacuum flash evaporator, and the tertiary flash gas outlet at the top of the vacuum flash evaporator is connected to a vacuum flash separator to separate a second gas phase and a second liquid phase.

[0006] In some embodiments, the circulating grey water can be circulated through the second upper tower located at the top of the low-pressure evaporative hot water tower and the first upper tower located at the top of the high-pressure evaporative hot water tower by a grey water circulation pump.

[0007] In some embodiments, the tertiary black water outlet at the bottom of the vacuum flash evaporator is connected to the clarification tank through a vacuum flash substrate pump.

[0008] In some embodiments, an acid gas condenser is further provided between the secondary flash gas outlet and the acid gas separator, and the first liquid phase outlet of the acid gas separator is connected to the vacuum flash evaporator.

[0009] In some embodiments, a vacuum flash condenser is further provided between the tertiary flash gas outlet and the vacuum flash separator, and the second liquid phase outlet of the vacuum flash separator is connected to the gray water tank via a vacuum flash separator bottom pump.

[0010] In some embodiments, the second gas phase outlet of the vacuum flash separator is connected to a vacuum pump separator via a vacuum pump, and the third liquid phase outlet of the vacuum pump separator is connected to the gray water tank.

[0011] In some embodiments, a first pressure control valve is provided between the primary flash gas outlet and the second lower tower, and a first angle valve is provided between the black water outlet and the second lower tower.

[0012] In some embodiments, a second angle valve is provided between the secondary black water outlet and the vacuum flash evaporator.

[0013] In some embodiments, a second pressure control valve is disposed at the first gas phase outlet.

[0014] Through the above technical solution, the first-stage flash steam outlet at the top of the high-pressure evaporation hot water tower is directly connected to the second lower tower at the bottom of the low-pressure evaporation hot water tower, so that the heat of the first-stage flash steam can be recovered and used to heat the gray water in the low-pressure evaporation hot water tower. Since the low-pressure evaporation hot water tower is connected to the high-pressure evaporation hot water tower, the temperature of the circulating gray water in the high-pressure evaporation hot water tower and the low-pressure evaporation hot water tower is simultaneously increased. This solution makes better use of the heat of the flash steam, further optimizes the black water flash evaporation waste heat recovery system, and at the same time, the flash steam after the high-pressure flash evaporation does not need a water cooler and a liquid separator to cool and separate, greatly reducing the equipment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0016] Figure 1 is a schematic diagram of a black water flash waste heat recovery system of the prior art;

[0017] Figure 2 It is a schematic diagram of a black water flash waste heat recovery system according to an embodiment of the present invention.

[0018] Description of Reference Numerals

[0019] 1. High-pressure evaporation hot water tower; 101. First-stage flash gas outlet; 102. First-stage black water outlet; 103. First lower tower; 104. First upper tower; 2. Low-pressure evaporation hot water tower; 201. Second-stage flash gas outlet; 202. Second-stage black water outlet; 203. Second lower tower; 204. Second upper tower; 3. Vacuum flash evaporator; 301. Third-stage flash gas outlet; 302. Third-stage black water outlet; 4. First pressure control valve; 5. Second pressure control valve; 6. First angle valve; 7. Acid gas condenser; 8. , acid gas separator; 801, first gas phase outlet; 802, first liquid phase outlet; 9, gray water circulation pump; 10, vacuum flash bottom pump; 11, clarification tank; 12, vacuum flash condenser; 13, vacuum flash separator; 1301, second gas phase outlet; 1302, second liquid phase outlet; 14, vacuum flash separator bottom pump; 15, vacuum pump; 16, vacuum pump separator; 1601, third gas phase outlet; 1602, third liquid phase outlet; 17, gray water tank; 18, second angle valve. DETAILED DESCRIPTION

[0020] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention. The present invention can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0021] The present invention provides these embodiments to make the present invention thorough and complete, and fully express the scope of the present invention to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of materials, numerical expressions and numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, rather than as limiting.

[0022] It should be noted that, in the description of the present invention, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0023] In addition, the words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" is not strictly perpendicular, but is within the tolerance range. "Parallel" is not strictly parallel, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0024] It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0025] All terms used in the present invention have the same meanings as those understood by ordinary technicians in the field to which the present invention belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, such as general dictionaries, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0026] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0027] In order to solve the problem that the existing black water flash evaporation waste heat recovery system does not effectively recover and utilize the flash steam heat of the high-pressure evaporation hot water tower, the present invention provides a black water flash evaporation waste heat recovery system, such as Figure 2 As shown, in a specific embodiment, the waste heat recovery system includes a high-pressure evaporation hot water tower 1, a low-pressure evaporation hot water tower 2 arranged downstream of the high-pressure evaporation hot water tower 1, and a vacuum flash evaporator 3 arranged downstream of the low-pressure evaporation hot water tower 2, wherein the high-pressure evaporation hot water tower 1, the low-pressure evaporation hot water tower 2, and the vacuum flash evaporator 3 are used to sequentially perform primary flash evaporation, secondary flash evaporation, and tertiary flash evaporation on high-pressure black water, and the primary flash gas outlet 101 located at the top of the high-pressure evaporation hot water tower 1 is directly connected to the second lower tower 203 located at the bottom of the low-pressure evaporation hot water tower 2 to increase the temperature of the circulating gray water in the high-pressure evaporation hot water tower 1 and the low-pressure evaporation hot water tower 2, and the primary black water outlet 102 located at the bottom of the high-pressure evaporation hot water tower 1 is connected to the second lower tower 203 located at the bottom of the low-pressure evaporation hot water tower 2.

[0028] like Figure 2 As shown, the black water flash evaporation waste heat recovery system of the present invention performs three-stage flash evaporation treatment on the high-pressure black water flowing into the system. Specifically, a high-pressure evaporation hot water tower 1 performs a first-stage flash evaporation, and discharges the first-stage flash gas and the concentrated first-stage black water from the top and bottom outlets thereof, respectively; a low-pressure evaporation hot water tower 2 performs a second-stage flash evaporation, and discharges the second-stage flash gas and the concentrated second-stage black water from the top and bottom outlets thereof, respectively; a vacuum flash evaporator 3 performs a third-stage flash evaporation, and discharges the third-stage flash gas and the concentrated third-stage black water from the top and bottom outlets thereof, respectively.

[0029] like Figure 1 As shown, the existing waste heat recovery system condenses the first-stage flash gas at the outlet of the high-pressure evaporation hot water tower through an acid gas condenser and separates it through an acid gas separator. The separated gas phase is directly discharged from the system, and the separated liquid phase is passed into a vacuum flash evaporator for three-stage flash evaporation. The above process causes the heat of the first-stage flash gas to be taken away by the circulating water cooling and cannot be effectively utilized. In the present invention, the first-stage flash gas at the first-stage flash gas outlet 101 of the high-pressure evaporation hot water tower 1 is connected to the second lower tower 203 of the low-pressure evaporation hot water tower 2. Since the first-stage flash gas still has a relatively high heat, this part of the heat can be used to increase the temperature of the circulating gray water pumped into the second upper tower 204 in the low-pressure evaporation hot water tower 2. Since the entire water system in the black water flash evaporation waste heat recovery system is connected, the washing water temperature in the two hot water towers is increased, so that the temperature of the washed crude synthesis gas is increased, the water-gas ratio is increased, and the steam replenishment amount in the conversion stage can be effectively reduced.

[0030] Experiments have shown that the use of the black water flash evaporation waste heat recovery system can increase the gray water temperature by 3-4°C and make the water-gas ratio of the crude synthesis gas reach above 0.9. At the same time, the invention eliminates the need for cooling and separation of the flash gas after high-pressure flash evaporation by a water cooler and a liquid separator, greatly reducing the equipment cost.

[0031] In some embodiments, the secondary flash gas outlet 201 located at the top of the low-pressure evaporation hot water tower 2 is connected to the acid gas separator 8 to separate the first gas phase and the first liquid phase, the secondary black water outlet 202 located at the bottom of the low-pressure evaporation hot water tower 2 is connected to the vacuum flash evaporator 3, and the tertiary flash gas outlet 301 located at the top of the vacuum flash evaporator 3 is connected to the vacuum flash separator 13 to separate the second gas phase and the second liquid phase.

[0032] like Figure 2As shown, the first gas phase separated by the acid gas separator 8 can be sent to the acid gas flare for centralized treatment, and the first liquid phase condensate separated by the acid gas separator 8 can be passed into the vacuum flash evaporator 3 for three-stage flash evaporation treatment together with the secondary black water discharged from the low-pressure evaporation hot water tower 2. The second liquid phase separated by the vacuum flash separator 13 flows into the gray water tank 17, and the separated second gas phase is passed into the subsequent vacuum pump separator 16 for further separation.

[0033] In some embodiments, the circulating grey water can be circulated through the second upper tower 204 located at the top of the low-pressure evaporative hot water tower 2 and the first upper tower 104 located at the top of the high-pressure evaporative hot water tower 1 by the grey water circulation pump 9. The primary and secondary flash steam need to be washed in the first upper tower 104 and the second upper tower 204, respectively, and the washing water mainly includes the circulating grey water pumped by the grey water circulation pump 9 and the circulating grey water after settling from outside the system. Figure 2 As shown, after the circulating grey water is sent into the system from the outside, it first passes into the second upper tower 204 of the low-pressure evaporative hot water tower 2, and exchanges heat with the secondary flash steam on the tower plate of the second upper tower 204 to increase the temperature of the circulating grey water. The circulating grey water is then pumped to the first upper tower 104 of the high-pressure evaporative hot water tower 1 by the grey water circulation pump 9, thereby increasing the temperature of the washing water in the first upper tower 104 of the high-pressure evaporative hot water tower 1. Since the washing water is used to wash the crude synthesis gas in the previous system, the temperature of the washed crude synthesis gas is increased and the water-gas ratio is increased.

[0034] In some embodiments, the tertiary black water outlet 302 at the bottom of the vacuum flash evaporator 3 is connected to the clarification tank 11 through the vacuum flash substrate pump 10. Figure 2 As shown, the concentrated tertiary black water can be sent to the clarification tank 11 through the vacuum flash substrate pump 10. The clarification tank 11 can discharge and filter the fine residue precipitated in the tertiary black water from the outlet of the clarification tank 11. The filtered fine residue can be discharged to the slag yard, and the filtered liquid phase can be reused as circulating gray water.

[0035] In some embodiments, an acid gas condenser 7 is further provided between the secondary flash gas outlet 201 and the acid gas separator 8, and the first liquid phase outlet 802 of the acid gas separator 8 is connected to the vacuum flash evaporator 3. Figure 2 As shown, the acid gas condenser 7 can make the secondary flash gas discharged from the secondary flash gas outlet 201 quickly condense into liquid and release heat to the outside, wherein the part that can be condensed into liquid is in the acid gas separator 8 as the first liquid phase and then flows into the vacuum flash evaporator 3, and the part that cannot be condensed into liquid is in the acid gas separator 8 as the first gas phase and sent to the outside.

[0036] In some embodiments, a vacuum flash condenser 12 is further provided between the third-stage flash gas outlet 301 and the vacuum flash separator 13, and the second liquid phase outlet 1302 of the vacuum flash separator 13 is connected to the gray water tank 17 via the vacuum flash separator bottom pump 14. Figure 2 As shown, the vacuum flash condenser 12 can make the third-stage flash gas discharged from the third-stage flash gas outlet 301 quickly condense into liquid and release heat to the outside, wherein the part that can be condensed into liquid flows into the gray water tank 17 as the second liquid phase in the vacuum flash separator 13, and the part that cannot be condensed into liquid is sent to the vacuum pump separator 16 as the second gas phase in the vacuum flash separator 13 for further separation.

[0037] In some embodiments, the second gas phase outlet 1301 of the vacuum flash separator 13 is connected to the vacuum pump separator 16 through the vacuum pump 15, and the third liquid phase outlet 1602 of the vacuum pump separator 16 is connected to the gray water tank 17. The vacuum pump separator 16 can fully separate and filter the liquid remaining in the second gas phase pumped by the vacuum pump 15, and automatically discharge and recycle the liquid. Specifically, the non-condensable gas in the second gas phase is pumped as the third gas phase by the vacuum pump 15 and sent to the outside of the system, and the condensate at the bottom of the vacuum pump separator 16 can be sent to the gray water tank 17 as the third liquid phase.

[0038] In some embodiments, a first pressure control valve 4 is provided between the primary flash gas outlet 101 and the second lower tower 203, and a first angle valve 6 is provided between the black water outlet 102 and the second lower tower 203. Figure 2 As shown, the first pressure control valve 4 can control and adjust the pressure of the first flash steam passing from the high-pressure evaporative hot water tower 1 into the low-pressure evaporative hot water tower 2 to maintain a stable pressure in the pipeline; the first angle valve 6 can reduce the pressure of the first black water passing from the high-pressure evaporative hot water tower 1 into the low-pressure evaporative hot water tower 2.

[0039] In some embodiments, a second angle valve 18 is provided between the secondary black water outlet 202 and the vacuum flash evaporator 3. Figure 2 As shown, the second angle valve 18 can reduce the pressure of the second black water passing from the low-pressure evaporation hot water tower 2 into the vacuum flash evaporator 3 .

[0040] In some embodiments, a second pressure control valve 5 is provided at the first gas phase outlet 801. Figure 2 As shown, the second pressure control valve 5 can control and adjust the pressure of the first gas phase introduced from the acid gas separator 8 to the outside of the system so that the first gas phase can be smoothly sent to the acid gas flare for subsequent treatment.

[0041] So far, various embodiments of the present invention have been described in detail. In order to avoid obscuring the concept of the present invention, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0042] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A black water flash evaporation waste heat recovery system, It is characterized in that The waste heat recovery system comprises a high-pressure evaporation hot water tower (1), a low-pressure evaporation hot water tower (2) arranged downstream of the high-pressure evaporation hot water tower (1), and a vacuum flash evaporator (3) arranged downstream of the low-pressure evaporation hot water tower (2), wherein the high-pressure evaporation hot water tower (1), the low-pressure evaporation hot water tower (2), and the vacuum flash evaporator (3) are used to sequentially perform primary flash evaporation, secondary flash evaporation, and tertiary flash evaporation on high-pressure black water, a primary flash gas outlet (101) located at the top of the high-pressure evaporation hot water tower (1) is directly connected to a second lower tower (203) located at the bottom of the low-pressure evaporation hot water tower (2) to increase the temperature of circulating gray water in the high-pressure evaporation hot water tower (1) and the low-pressure evaporation hot water tower (2), and a primary black water outlet (102) located at the bottom of the high-pressure evaporation hot water tower (1) is connected to the second lower tower (203) located at the bottom of the low-pressure evaporation hot water tower (2).

2. The black water flash evaporation waste heat recovery system according to claim 1, It is characterized in that The secondary flash gas outlet (201) located at the top of the low-pressure evaporation hot water tower (2) is connected to the acid gas separator (8) to separate the first gas phase and the first liquid phase, the secondary black water outlet (202) located at the bottom of the low-pressure evaporation hot water tower (2) is connected to the vacuum flash evaporator (3), and the tertiary flash gas outlet (301) located at the top of the vacuum flash evaporator (3) is connected to the vacuum flash separator (13) to separate the second gas phase and the second liquid phase.

3. The black water flash evaporation waste heat recovery system according to claim 2, It is characterized in that The circulating grey water can flow through the second upper tower (204) located at the top of the low-pressure evaporative hot water tower (2) and the first upper tower (104) located at the top of the high-pressure evaporative hot water tower (1) via a grey water circulation pump (9).

4. The black water flash evaporation waste heat recovery system according to claim 3, It is characterized in that The tertiary black water outlet (302) located at the bottom end of the vacuum flash evaporator (3) is connected to the clarification tank (11) via a vacuum flash substrate pump (10).

5. The black water flash evaporation waste heat recovery system according to claim 4, It is characterized in that An acid gas condenser (7) is also provided between the secondary flash gas outlet (201) and the acid gas separator (8), and the first liquid phase outlet (802) of the acid gas separator (8) is connected to the vacuum flash evaporator (3).

6. The black water flash evaporation waste heat recovery system according to claim 5, It is characterized in that A vacuum flash condenser (12) is also provided between the third-stage flash gas outlet (301) and the vacuum flash separator (13), and the second liquid phase outlet (1302) of the vacuum flash separator (13) is connected to the gray water tank (17) via the vacuum flash separator bottom pump (14).

7. The black water flash evaporation waste heat recovery system according to claim 6, It is characterized in that The second gas phase outlet (1301) of the vacuum flash separator (13) is connected to the vacuum pump separator (16) via a vacuum pump (15), and the third liquid phase outlet (1602) of the vacuum pump separator (16) is connected to the gray water tank (17).

8. The black water flash evaporation waste heat recovery system according to claim 7, It is characterized in that A first pressure control valve (4) is provided between the first-stage flash gas outlet (101) and the second lower tower (203), and a first angle valve (6) is provided between the first-stage black water outlet (102) and the second lower tower (203).

9. The black water flash evaporation waste heat recovery system according to claim 8, It is characterized in that A second angle valve (18) is provided between the secondary black water outlet (202) and the vacuum flash evaporator (3).

10. The black water flash evaporation waste heat recovery system according to claim 9, It is characterized in that A second pressure control valve (5) is provided at the first gas phase outlet (801).

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