Black water waste heat utilization system for high-pressure flash tank of coal gasifier

Abstract

A black water waste heat utilization system for a high-pressure flash tank of a coal gasifier belongs to the technical field of coal gasification waste heat utilization, comprises a high-pressure flash tank, a vacuum flash tank and an S vortex flow channel black water special heat removal device, realizes quality-divided gradient heating of heated media of all hot spots, and can solve the problems of blockage, scaling and corrosion in black water waste heat utilization. And efficient heat extraction is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal gasification waste heat utilization, and in particular relates to a black water waste heat utilization system of a coal gasifier high-pressure flash tank. Background Art

[0002] With pulverized coal and water-coal slurry as raw materials, in the gasifier, coal, water vapor and oxygen generate crude synthesis gas such as CO, H2, CO2, CH4, H2S under high temperature and high pressure conditions, and produce a large amount of high-temperature and high-pressure black water at the same time. The black water enters the high-pressure flash tank (0.6MPa, 165℃) and the vacuum flash system, and is flashed by the vacuum flash system to reduce the temperature of the black water, release insoluble gases and concentrate the black water. The black water after flash evaporation is sent to the sedimentation tank for clarification, and the clarified water is recycled. There is a large amount of reusable low-grade waste heat in the whole operation process, while reducing the energy consumption and operating costs of the vacuum flash system.

[0003] Application No. CN202323454184.2 discloses a coal chemical gasification black water cooling and waste heat recovery system, the system comprises an evaporative hot water tower, a vacuum flash tank, a primary heat exchange unit, a secondary heat exchange unit and a heat user; the outlet of the evaporative hot water tower, the black water inlet of the primary heat exchange unit, the black water outlet of the primary heat exchange unit and the inlet of the vacuum flash tank are connected in sequence, and are used to cool down the heated black water through heat exchange between heat medium water and heated black water, and obtain cooled black water and heated heat medium water, so as to send the cooled black water into the vacuum flash tank; the heat medium water outlet of the primary heat exchange unit, the heat medium water inlet of the secondary heat exchange unit, the heat medium outlet of the secondary heat exchange unit and the heat user are connected in sequence, and are used to exchange heat between the heated heat medium water and the heat medium; However, the utilization efficiency of black water waste heat is not fully improved, and the comprehensive cascade utilization of waste heat cannot be achieved. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a system for utilizing the waste heat of black water in a high-pressure flash tank of a coal gasifier.

[0005] The present application proposes a system for utilizing waste heat of black water from a high-pressure flash tank of a coal gasifier, including a high-pressure flash tank, a vacuum flash tank, and a special heat extraction device for black water in an S-vortex flow channel, to achieve quality-differentiated stepwise heating of the heated medium at each hot spot; The S vortex flow channel black water special heat extraction device includes a primary black water side of a waste heat utilization system and a secondary side of the waste heat utilization system. The black water outlet pipe of the high-pressure flash tank is connected in sequence with the inlet and outlet of the black water side of the S vortex flow channel black water special heat extraction device and the black water inlet pipe of the vacuum flash tank, or the black water outlet pipe of the high-pressure flash tank is connected in sequence with the inlet and outlet of the black water side of the S vortex flow channel black water special heat extraction device and the inlet of the clarification tank.

[0006] Specifically, it also includes the intermediate hot water circulation system, which includes a two-stage detachable plate heat exchanger and a hot water circulation pump.

[0007] Specifically, the intermediate hot water is taken out from the secondary side outlet of the S-vortex flow channel black water dedicated heat extraction device, and is sequentially connected to a Class II lithium bromide steam heat pump unit, a lithium bromide heat pump refrigeration unit, a secondary detachable plate heat exchanger, a hot water circulation pump, and then connected to the secondary side inlet of the S-vortex flow channel black water dedicated heat extraction device to form secondary side system circulation heating.

[0008] Specifically, the S-vortex flow channel black water dedicated heat extraction device is provided in one or more units, and is connected in series or in parallel or in a combination of series and parallel according to the process.

[0009] Specifically, it also includes the intermediate hot water quality-differentiated and graded cascade utilization system, which includes producing intermediate hot water above 100-165°C through an S-vortex flow channel black water special heat extraction device, a Class II lithium bromide heat pump steam production unit, a lithium bromide heat pump refrigeration unit, an organic Rankine cycle ORC generator unit, a cooling water plate heat exchanger, a chemical water workshop raw water system, a boiler water supply system, a heating deaerator inlet water, a desalted water or cooling water system, and a municipal heating system.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The black water and intermediate hot water from the 0.6MPa, 165℃ high flash tank enter the S-vortex flow channel black water special heat extraction device for cross-countercurrent heat exchange. The heat of the black water is used to heat the intermediate hot water to above 160℃, solving the blockage, scaling and corrosion problems of black water waste heat utilization and achieving efficient heat extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0012] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] A system for utilizing waste heat from black water in a high-pressure flash tank of a coal gasifier, such as Figure 1 As shown, it includes a high-pressure flash tank, a vacuum flash tank, and an S-vortex flow channel black water special heat extraction device to achieve quality-differentiated step heating of the heated medium at each hot spot.

[0015] The S-vortex flow channel black water dedicated heat extraction device includes a primary black water side of the waste heat utilization system and a secondary side of the waste heat utilization system.

[0016] There are two connection methods for the primary black water side of the waste heat utilization system: 1. Method 1: The black water outlet pipe of the high-pressure flash tank is connected with the black water side inlet and outlet of the S-vortex flow channel black water special heat extraction device and the black water inlet pipe of the vacuum flash tank in sequence, and the heat of the black water above 100℃ is utilized; 2. Method 2: The black water outlet pipe of the high-pressure flash tank is connected to the black water side inlet and outlet of the S-vortex flow channel black water special heat extraction device and the clarification tank inlet in sequence, and all the black water heat is utilized; the black water flow can be connected arbitrarily or completely according to the heat demand.

[0017] The secondary side of the waste heat utilization system is divided into direct heating and indirect heating.

[0018] 1. Direct heating includes the S-vortex flow channel black water special heat extraction device, hot water circulation pump and the heated medium at each hot spot.

[0019] 2. Indirect heating includes: S-vortex flow channel black water special heat extraction device and intermediate hot water circulation system.

[0020] The intermediate hot water circulation system includes a two-stage detachable plate heat exchanger, a hot water circulation pump, etc.

[0021] The intermediate hot water is taken out from the secondary side outlet of the S-vortex flow channel black water dedicated heat extraction device, and is successively connected to the second-class lithium bromide steam heat pump unit, the lithium bromide heat pump refrigeration unit, the secondary detachable plate heat exchanger, the hot water circulation pump, and then connected to the secondary side inlet of the S-vortex flow channel black water dedicated heat extraction device to form secondary side system circulation heating.

[0022] The differentiated cascade heating media of each hot spot include, but are not limited to: hot water for Class II lithium bromide heat pump steam production units, hot water for lithium bromide heat pump refrigeration units, hot water for ORC organic Rankine cycle generator units, process desalted water such as deaerator and boiler inlet water, raw water from desalting stations, municipal heating hot water and circulating water cooling water, etc.

[0023] Specifically, the S-vortex flow channel black water dedicated heat extraction device described in this embodiment can be set up in one or more units, and can be connected in series or in parallel or in a combination of series and parallel according to the process.

[0024] Furthermore, the intermediate hot water quality-differentiated and graded cascade utilization system described in this embodiment includes: an S-vortex flow channel black water dedicated heat extraction device can produce intermediate hot water above 100-160°C, a Class II lithium bromide heat pump steam production unit, a lithium bromide heat pump refrigeration unit, an organic Rankine cycle ORC generator unit, a cooling water plate heat exchanger, a chemical water workshop raw water system, a boiler water supply system, a heating deaerator inlet, a desalted water or cooling water system, a municipal heating system, etc.

[0025] Furthermore, in the waste heat utilization system of this embodiment, the primary black water side: Method 1: The S-vortex flow channel black water special heat extraction device extracts heat from the black water on the primary side, including the black water outlet at the bottom of the high-pressure flash tank, and the black water exchanges heat with the S-vortex flow channel black water special heat extraction device. The black water is cooled and returned to the vacuum flash tank by heat exchange in the S-vortex flow channel black water special heat extraction device. This solution utilizes the heat of the high temperature range of 165-100℃ of black water, while reducing the operating load of the vacuum pump of the vacuum system, reducing the amount of circulating water, and reducing the operating cost of the circulating water pump.

[0026] Option 2: The black water outlet at the bottom of the high-pressure flash tank is connected to the black water special heat extraction device in the S-vortex flow channel for heat exchange. After the black water is cooled, it is directly returned to the sedimentation tank. This option uses the black water temperature of 165℃ to 60℃, and all the heat of the black water is utilized.

[0027] Secondary side of waste heat utilization system: 1. Direct heating: Use the hot spot heated medium to directly exchange heat with the S vortex flow channel black water special heat extraction device: 2. Indirect heating: Add an intermediate hot water circulation system to prevent black water from communicating with the heated medium and contaminating it, including: the intermediate hot water passes through a circulating water pump and enters the S-vortex flow channel black water dedicated heat extraction device to extract heat, and then enters the secondary detachable plate heat exchanger for secondary heat exchange. The 160°C hot water is used for multiple purposes. At the same time, the intermediate hot water is reduced to 55°C and enters the S-vortex flow channel black water dedicated heat extraction device for circulation and heat extraction.

[0028] Working process: (1) The bottom of the high-pressure flash tank is connected to the black water valve. The black water valve before entering the vacuum flash tank is closed, and the black water (0.6MPa, 165℃) enters the S-vortex flow channel black water dedicated heat extraction device to exchange heat with the heated heat medium. The heated medium is the desalted water entering the deaerator, and the temperature is heated from 90℃ to 135℃; or directly heats the raw water in the water treatment workshop, and the temperature is heated from 5℃ to 25℃; or directly heats the municipal heating hot water, and the temperature is heated from 50℃ to 110℃; or the hot water heated to above 90℃ enters the organic Rankine cycle ORC generator set for waste heat power generation. The heated heat medium can be one or more.

[0029] (2) After the black water has undergone heat exchange in the S-vortex flow channel black water dedicated heat extraction device, the black water temperature drops to 100°C and enters the vacuum flash tank for further flash evaporation to reduce the energy consumption of the flash evaporation system. Or after the black water has undergone heat exchange in the S-vortex flow channel black water dedicated heat extraction device, the black water temperature drops to 60°C and directly enters the clarification tank, and the vacuum flash evaporation system is completely shut down, completely replacing the vacuum flash evaporation system, reducing the emission of flash gas to the atmosphere, reducing the emission of CO2 and C0, and reducing the operating cost of the vacuum flash evaporation system.

[0030] (3) After the 165℃ high flash black water enters the S-vortex flow channel black water dedicated heat extraction device for heat exchange, it uses the intermediate hot water method and circulates heat exchange through the intermediate hot water circulation pump. The intermediate hot water is heated to 160℃ (the S-vortex flow channel black water dedicated heat extraction device can achieve 5℃-10℃ end difference heat exchange), and the secondary heat exchange is carried out through the secondary detachable plate heat exchanger. After the lithium bromide heat pump produces 0.6MPa and 165℃ saturated steam, the intermediate water temperature drops to 115℃ and enters the lithium bromide refrigerator for summer cooling. The intermediate water temperature drops to 55℃ and the intermediate water circulation is realized through the circulating water pump.

[0031] (4) Black water has the characteristics of high temperature, high hardness, high suspended matter, easy corrosion, easy clogging, and easy scaling. The S-vortex flow channel black water dedicated heat extraction device can solve the pain point of difficulty in recovering waste heat due to clogging, scaling, corrosion and other reasons caused by the black water quality.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coal gasifier high-pressure flash tank black water waste heat utilization system, characterized by: It includes high-pressure flash tank, vacuum flash tank and S-vortex flow channel black water special heat extraction device, which can realize the graded heating of the heated medium at each hot spot; The S vortex flow channel black water special heat extraction device includes a primary black water side of a waste heat utilization system and a secondary side of the waste heat utilization system. The black water outlet pipe of the high-pressure flash tank is connected in sequence with the inlet and outlet of the black water side of the S vortex flow channel black water special heat extraction device and the black water inlet pipe of the vacuum flash tank, or the black water outlet pipe of the high-pressure flash tank is connected in sequence with the inlet and outlet of the black water side of the S vortex flow channel black water special heat extraction device and the inlet of the clarification tank.

2. A coal gasifier high-pressure flash tank black water waste heat utilization system according to claim 1, characterized in that: It also includes the intermediate hot water circulation system, which includes a secondary detachable plate heat exchanger, a hot water circulation pump, and a heat user.

3. A coal gasifier high-pressure flash tank black water waste heat utilization system according to claim 2, characterized in that: The intermediate hot water is taken out from the secondary side outlet of the S-vortex flow channel black water dedicated heat extraction device, and is sequentially connected to the second-class lithium bromide steam heat pump unit, the lithium bromide heat pump refrigeration unit, the secondary detachable plate heat exchanger, the hot water circulation pump, and then connected to the secondary side inlet of the S-vortex flow channel black water dedicated heat extraction device to form secondary side system circulation heating.

4. A coal gasifier high-pressure flash tank black water waste heat utilization system according to claim 3, characterized in that: The S-vortex flow channel black water dedicated heat extraction device is provided in one or more units, and is connected in series or in parallel or in a combination of series and parallel according to the process.

5. The system for utilizing waste heat of black water from a high-pressure flash tank of a coal gasifier according to claim 1, characterized in that: It also includes the intermediate hot water quality-differentiated and graded cascade utilization system, which includes producing intermediate hot water above 100-160°C through an S-vortex flow channel black water special heat extraction device, a Class II lithium bromide heat pump steam production unit, a lithium bromide heat pump refrigeration unit, an organic Rankine cycle ORC generator unit, a cooling water plate heat exchanger, a chemical water workshop raw water system, a boiler water supply system, a heating deaerator inlet, a desalted water or cooling water system, and a municipal heating system.

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