Low-level waste heat recovery system
By optimizing the low-level waste heat recovery system of the coal-water slurry gasification unit, the problem of low heat recovery efficiency in the ash water treatment section was solved, maximizing heat recovery and improving system stability, thus supporting the achievement of energy conservation, carbon reduction, and water conservation goals.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHAANXI WEIHE COAL CHEM GRP
- Filing Date
- 2025-04-18
- Publication Date
- 2026-04-21
AI Technical Summary
In existing coal-water slurry gasification units, the ash water treatment section suffers from low heat recovery efficiency, leading to increased energy consumption and system instability, and failing to effectively utilize surplus heat.
A low-level waste heat recovery system is adopted, which optimizes the process flow and makes reasonable use of excess heat through a heat exchange network composed of components such as high-pressure flash tank, low-pressure flash tank, demineralized water heater and gas-liquid separator, so as to achieve maximum heat recovery.
The increased demineralized water temperature reduced boiler deaerator steam consumption and circulating water usage, achieving energy conservation, carbon reduction, and water conservation, enhancing system stability, and supporting the achievement of "dual carbon targets".
Smart Images
Figure CN224151498U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of coal-water slurry gasification technology and relates to a low-level waste heat recovery system. Background Technology
[0002] Coal-water slurry gasification is a crucial step in modern coal chemical production. Its core function is to mix coal and water to create a coal-water slurry, which then reacts with oxygen under high temperature and pressure to produce syngas. During this process, the gasifier and carbon washing tower generate large quantities of black water characterized by high temperature, high pressure, high hardness, and high suspended solids. This black water needs to undergo cooling, slag removal, and heat recovery in an ash water treatment section to achieve water resource recycling and stable system operation.
[0003] Grey water treatment processes typically employ a four-stage flash evaporation process, releasing heat from black water as steam by progressively reducing pressure at each stage. This includes high-pressure flash evaporation, low-pressure flash evaporation, first-stage vacuum flash evaporation, and second-stage vacuum flash evaporation. This process not only recovers waste heat from black water but also concentrates solid slag and desorbs acidic gases. However, under design conditions, approximately 30% of the excess heat is carried away by circulating water, failing to be effectively utilized and resulting in wasted thermal energy. This phenomenon not only increases system energy consumption but also limits overall energy efficiency. To address this issue, some companies have added high-flash gas recovery systems to recover and utilize the excess heat in the high-flash gas, thereby improving thermal energy utilization and bringing significant economic benefits to the companies.
[0004] Furthermore, the ash water treatment section also faces problems such as scaling, corrosion, and flocculation, which can further affect the system's stability and heat recovery efficiency. Therefore, optimizing the ash water treatment process and improving heat recovery efficiency are important research directions in the current operation of coal-water slurry gasification units. Utility Model Content
[0005] The purpose of this invention is to provide a low-level waste heat recovery system, which solves the problem of low heat recovery efficiency in the existing technology.
[0006] The technical solution adopted in this utility model is a low-level waste heat recovery system, including a high-pressure flash tank. The top of the high-pressure flash tank is connected to a high-pressure ash water heater via a pipe. The high-pressure ash water heater is connected in sequence to a circulating water condenser, a gas-liquid separator, and a deaerator via pipes. The bottom of the high-pressure flash tank is connected to a low-pressure flash tank via a pipe. The low-pressure flash tank is also connected to a deaerator. The top of the high-pressure flash tank is connected to a demineralized water heater via a pipe. The demineralized water heater is connected in sequence to a gas-liquid separator and a deaerator via pipes.
[0007] The features of this utility model also include:
[0008] The side wall of the high-pressure flash tank is connected to the black water pipes of the gasification furnace and the carbon washing tower.
[0009] The top of the high-pressure flash tank is connected to a first high-pressure flash steam pipe. The end of the first high-pressure flash steam pipe away from the high-pressure flash tank is connected to a second high-pressure flash steam pipe and a third high-pressure flash steam pipe via a tee. The second high-pressure flash steam pipe is connected to the high-pressure ash water heater.
[0010] The third high-pressure flash steam pipeline is equipped with a valve and is connected to the demineralized water heater. The demineralized water heater is also connected to the fourth high-pressure flash steam pipeline, which is connected to the gas-liquid separator.
[0011] The demineralized water heater is also connected to a demineralized water inlet pipe and a demineralized water outlet pipe.
[0012] The top of the demineralized water heater is connected to a first flash steam vapor phase pipe, and the end of the first flash steam vapor phase pipe away from the demineralized water heater is connected to a second flash steam vapor phase pipe and a third flash steam vapor phase pipe via a tee.
[0013] The other end of the second flash vapor phase pipeline is connected to the low-pressure flash tank, and the other end of the third flash vapor phase pipeline is connected to the deaerator.
[0014] The bottom of the low-pressure flash tank is connected to a low-pressure flash condensate pipeline.
[0015] The top of the deaerator is connected to a deaerator gas phase pipeline.
[0016] The beneficial effects of this utility model are:
[0017] This novel low-level waste heat recovery system increases the temperature of demineralized water from the shift converter, reduces steam consumption (1.5 MPa, 200°C) in the boiler deaerator, and simultaneously reduces circulating water usage. By optimizing the heat exchange network pinch points, adjusting and optimizing the process flow, and rationally utilizing surplus heat, the system is rebalanced to maximize heat and condensate recovery, achieving the goals of reducing carbon emissions and saving energy and water. The system also provides greater operational flexibility, playing a crucial role in system stability. This process not only contributes to energy conservation and carbon reduction but also helps achieve the "dual carbon" goals (carbon reduction and emission reduction). Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the overall structure of the low-level waste heat recovery system of this utility model.
[0019] In the diagram: 1. Black water pipeline from the gasifier; 2. Black water pipeline from the carbon washing tower; 3. High-pressure flash tank; 4. First high-pressure flash steam pipeline; 5. Second high-pressure flash steam pipeline; 6. Third high-pressure flash steam pipeline; 7. Fourth high-pressure flash steam pipeline; 8. Demineralized water inlet pipeline; 9. Demineralized water heater; 10. Gas-liquid separator; 11. Demineralized water outlet pipeline; 12. First flash steam vapor phase pipeline; 13. Deaerator; 14. Low-pressure flash condensate pipeline; 15. Low-pressure flash tank; 16. Second flash steam vapor phase pipeline; 17. Third flash steam vapor phase pipeline; 18. Deaerator vapor phase pipeline; 19. High-pressure ash water heater; 20. Circulating water condenser; 21. Valve; 22. Gas-liquid separator. Detailed Implementation
[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0021] Low-level waste heat recovery systems, such as Figure 1 As shown, the system includes a high-pressure flash tank 3. The top of the high-pressure flash tank 3 is connected to a high-pressure ash water heater 19 via a pipe. The high-pressure ash water heater 19 is connected in sequence to a circulating water condenser 20, a gas-liquid separator 22, and a deaerator 13 via pipes. The bottom of the high-pressure flash tank 3 is connected to a low-pressure flash tank 15 via a pipe. The low-pressure flash tank 15 is also connected to the deaerator 13. The top of the high-pressure flash tank 3 is connected to a demineralized water heater 9 via a pipe. The demineralized water heater 9 is connected in sequence to a gas-liquid separator 10 and a deaerator 13 via pipes.
[0022] The side wall of the high-pressure flash tank 3 is connected to the gasifier black water pipe 1 and the carbon washing tower black water pipe 2. The top of the high-pressure flash tank 3 is connected to the first high-pressure flash steam pipe 4. The end of the first high-pressure flash steam pipe 4 away from the high-pressure flash tank 3 is connected to the second high-pressure flash steam pipe 5 and the third high-pressure flash steam pipe 6 through a tee. The second high-pressure flash steam pipe 5 is connected to the high-pressure ash water heater 19.
[0023] A valve 21 is installed on the third high-pressure flash steam pipe 6. The third high-pressure flash steam pipe 6 is connected to the demineralized water heater 9. The demineralized water heater 9 is also connected to the fourth high-pressure flash steam pipe 7. The fourth high-pressure flash steam pipe 7 is connected to the gas-liquid separator 10.
[0024] The demineralized water heater 9 is also connected to a demineralized water inlet pipe 8 and a demineralized water outlet pipe 11, and the heated demineralized water is sent to the boiler deaerator.
[0025] The top of the demineralized water heater 9 is connected to a first flash steam vapor phase pipe 12. The end of the first flash steam vapor phase pipe 12 away from the demineralized water heater 9 is connected to a second flash steam vapor phase pipe 16 and a third flash steam vapor phase pipe 17 via a tee.
[0026] The other end of the second flash vapor phase pipeline 16 is connected to the low-pressure flash tank 15, and the other end of the third flash vapor phase pipeline 17 is connected to the deaerator 13. The bottom of the low-pressure flash tank 15 is connected to the low-pressure flash condensate pipeline 14. The top of the deaerator 13 is connected to the deaerator vapor phase pipeline 18.
[0027] The process flow of the low-level waste heat recovery system of this utility model is as follows: the high-temperature and high-pressure black water from the gasifier enters the high-pressure flash tank 3 through the gasifier black water pipeline 1, and the high-temperature and high-pressure black water from the carbon washing tower enters the high-pressure flash tank 3 through the carbon washing tower black water pipeline 2. The high-pressure flash steam in the high-pressure flash tank 3 enters the first high-pressure flash steam pipeline 4 and is split into two. One path enters the high-pressure ash water heater 19 through the second high-pressure flash steam pipeline 5, and the other path enters the demineralized water heater 9 through the third high-pressure flash steam pipeline 6.
[0028] One stream of high-pressure flash steam enters the high-pressure ash water heater 19 to heat the high-pressure ash water. The high-pressure flash steam is then cooled and enters the circulating water condenser 20 bypass, where it is further cooled. After cooling, it enters the gas-liquid separator 22. The liquid phase from the gas-liquid separator 22 enters the deaerator 13 through the bottom pipe, while the gas phase enters the deaerator 13 through the top pipe. The remaining high-pressure flash steam is controlled by valve 21. Opening valve 21 allows another stream of high-pressure flash steam to enter the demineralized water heater 9 to heat the demineralized water from the shift converter. The heat is carried away by the demineralized water heater 9, achieving heat utilization and system balance. The demineralized water enters the demineralized water heater 9 via the demineralized water inlet pipe 8 and is discharged from the demineralized water heater 9 via the demineralized water outlet pipe 11 after heating. After the high-pressure flash steam enters the demineralized water heater 9, it is cooled. The cooled high-pressure flash steam enters the gas-liquid separator 10 through the fourth high-pressure flash steam pipeline 7. The gas phase generated by the gas-liquid separator 10 enters the first flash steam gas phase pipeline 12. The liquid phase generated by the gas-liquid separator 10 merges with the liquid phase of the gas-liquid separator 22 and enters the deaerator 13.
[0029] The liquid phase in the high-pressure flash tank 3 enters the low-pressure flash tank 15 for low-pressure flash evaporation. The condensate from the low-pressure flash evaporation in the low-pressure flash tank 15 enters the vacuum flash tank for further processing via the low-pressure flash condensate pipeline 14. The gas phase from the low-pressure flash evaporation in the low-pressure flash tank 15 passes through the second flash gas phase pipeline 16 and merges with the first flash gas phase pipeline 12 through a tee. It then enters the deaerator 13 via the third flash gas phase pipeline 17. The gas phase generated by the deaerator 13 is sent to the boiler or sulfur recovery section via the deaerator gas phase pipeline 18.
[0030] Example 1
[0031] Low-level waste heat recovery systems, such as Figure 1As shown, the system includes a high-pressure flash tank 3. The top of the high-pressure flash tank 3 is connected to a high-pressure ash water heater 19 via a pipe. The high-pressure ash water heater 19 is connected in sequence to a circulating water condenser 20, a gas-liquid separator 22, and a deaerator 13 via pipes. The bottom of the high-pressure flash tank 3 is connected to a low-pressure flash tank 15 via a pipe. The low-pressure flash tank 15 is also connected to the deaerator 13. The top of the high-pressure flash tank 3 is connected to a demineralized water heater 9 via a pipe. The demineralized water heater 9 is connected in sequence to a gas-liquid separator 10 and a deaerator 13 via pipes.
[0032] Example 2
[0033] Low-level waste heat recovery systems, such as Figure 1 As shown, the system includes a high-pressure flash tank 3. The top of the high-pressure flash tank 3 is connected to a high-pressure ash water heater 19 via a pipe. The high-pressure ash water heater 19 is connected in sequence to a circulating water condenser 20, a gas-liquid separator 22, and a deaerator 13 via pipes. The bottom of the high-pressure flash tank 3 is connected to a low-pressure flash tank 15 via a pipe. The low-pressure flash tank 15 is also connected to the deaerator 13. The top of the high-pressure flash tank 3 is connected to a demineralized water heater 9 via a pipe. The demineralized water heater 9 is connected in sequence to a gas-liquid separator 10 and a deaerator 13 via pipes.
[0034] The side wall of the high-pressure flash tank 3 is connected to the gasifier black water pipe 1 and the carbon washing tower black water pipe 2. The top of the high-pressure flash tank 3 is connected to the first high-pressure flash steam pipe 4. The end of the first high-pressure flash steam pipe 4 away from the high-pressure flash tank 3 is connected to the second high-pressure flash steam pipe 5 and the third high-pressure flash steam pipe 6 through a tee. The second high-pressure flash steam pipe 5 is connected to the high-pressure ash water heater 19.
[0035] Example 3
[0036] Low-level waste heat recovery systems, such as Figure 1 As shown, the system includes a high-pressure flash tank 3. The top of the high-pressure flash tank 3 is connected to a high-pressure ash water heater 19 via a pipe. The high-pressure ash water heater 19 is connected in sequence to a circulating water condenser 20, a gas-liquid separator 22, and a deaerator 13 via pipes. The bottom of the high-pressure flash tank 3 is connected to a low-pressure flash tank 15 via a pipe. The low-pressure flash tank 15 is also connected to the deaerator 13. The top of the high-pressure flash tank 3 is connected to a demineralized water heater 9 via a pipe. The demineralized water heater 9 is connected in sequence to a gas-liquid separator 10 and a deaerator 13 via pipes.
[0037] The side wall of the high-pressure flash tank 3 is connected to the gasifier black water pipe 1 and the carbon washing tower black water pipe 2. The top of the high-pressure flash tank 3 is connected to the first high-pressure flash steam pipe 4. The end of the first high-pressure flash steam pipe 4 away from the high-pressure flash tank 3 is connected to the second high-pressure flash steam pipe 5 and the third high-pressure flash steam pipe 6 through a tee. The second high-pressure flash steam pipe 5 is connected to the high-pressure ash water heater 19.
[0038] A valve 21 is installed on the third high-pressure flash steam pipe 6. The third high-pressure flash steam pipe 6 is connected to the demineralized water heater 9. The demineralized water heater 9 is also connected to the fourth high-pressure flash steam pipe 7. The fourth high-pressure flash steam pipe 7 is connected to the gas-liquid separator 10.
[0039] Example 4
[0040] Low-level waste heat recovery systems, such as Figure 1 As shown, the system includes a high-pressure flash tank 3. The top of the high-pressure flash tank 3 is connected to a high-pressure ash water heater 19 via a pipe. The high-pressure ash water heater 19 is connected in sequence to a circulating water condenser 20, a gas-liquid separator 22, and a deaerator 13 via pipes. The bottom of the high-pressure flash tank 3 is connected to a low-pressure flash tank 15 via a pipe. The low-pressure flash tank 15 is also connected to the deaerator 13. The top of the high-pressure flash tank 3 is connected to a demineralized water heater 9 via a pipe. The demineralized water heater 9 is connected in sequence to a gas-liquid separator 10 and a deaerator 13 via pipes.
[0041] The side wall of the high-pressure flash tank 3 is connected to the gasifier black water pipe 1 and the carbon washing tower black water pipe 2. The top of the high-pressure flash tank 3 is connected to the first high-pressure flash steam pipe 4. The end of the first high-pressure flash steam pipe 4 away from the high-pressure flash tank 3 is connected to the second high-pressure flash steam pipe 5 and the third high-pressure flash steam pipe 6 through a tee. The second high-pressure flash steam pipe 5 is connected to the high-pressure ash water heater 19.
[0042] A valve 21 is installed on the third high-pressure flash steam pipe 6. The third high-pressure flash steam pipe 6 is connected to the demineralized water heater 9. The demineralized water heater 9 is also connected to the fourth high-pressure flash steam pipe 7. The fourth high-pressure flash steam pipe 7 is connected to the gas-liquid separator 10.
[0043] The demineralized water heater 9 is also connected to a demineralized water inlet pipe 8 and a demineralized water outlet pipe 11.
[0044] Example 5
[0045] Low-level waste heat recovery systems, such as Figure 1 As shown, the system includes a high-pressure flash tank 3. The top of the high-pressure flash tank 3 is connected to a high-pressure ash water heater 19 via a pipe. The high-pressure ash water heater 19 is connected in sequence to a circulating water condenser 20, a gas-liquid separator 22, and a deaerator 13 via pipes. The bottom of the high-pressure flash tank 3 is connected to a low-pressure flash tank 15 via a pipe. The low-pressure flash tank 15 is also connected to the deaerator 13. The top of the high-pressure flash tank 3 is connected to a demineralized water heater 9 via a pipe. The demineralized water heater 9 is connected in sequence to a gas-liquid separator 10 and a deaerator 13 via pipes.
[0046] The side wall of the high-pressure flash tank 3 is connected to the gasifier black water pipe 1 and the carbon washing tower black water pipe 2. The top of the high-pressure flash tank 3 is connected to the first high-pressure flash steam pipe 4. The end of the first high-pressure flash steam pipe 4 away from the high-pressure flash tank 3 is connected to the second high-pressure flash steam pipe 5 and the third high-pressure flash steam pipe 6 through a tee. The second high-pressure flash steam pipe 5 is connected to the high-pressure ash water heater 19.
[0047] A valve 21 is installed on the third high-pressure flash steam pipe 6. The third high-pressure flash steam pipe 6 is connected to the demineralized water heater 9. The demineralized water heater 9 is also connected to the fourth high-pressure flash steam pipe 7. The fourth high-pressure flash steam pipe 7 is connected to the gas-liquid separator 10.
[0048] The demineralized water heater 9 is also connected to a demineralized water inlet pipe 8 and a demineralized water outlet pipe 11.
[0049] The top of the demineralized water heater 9 is connected to a first flash steam vapor phase pipe 12. The end of the first flash steam vapor phase pipe 12 away from the demineralized water heater 9 is connected to a second flash steam vapor phase pipe 16 and a third flash steam vapor phase pipe 17 via a tee.
[0050] Example 6
[0051] Low-level waste heat recovery systems, such as Figure 1 As shown, the system includes a high-pressure flash tank 3. The top of the high-pressure flash tank 3 is connected to a high-pressure ash water heater 19 via a pipe. The high-pressure ash water heater 19 is connected in sequence to a circulating water condenser 20, a gas-liquid separator 22, and a deaerator 13 via pipes. The bottom of the high-pressure flash tank 3 is connected to a low-pressure flash tank 15 via a pipe. The low-pressure flash tank 15 is also connected to the deaerator 13. The top of the high-pressure flash tank 3 is connected to a demineralized water heater 9 via a pipe. The demineralized water heater 9 is connected in sequence to a gas-liquid separator 10 and a deaerator 13 via pipes.
[0052] The side wall of the high-pressure flash tank 3 is connected to the gasifier black water pipe 1 and the carbon washing tower black water pipe 2. The top of the high-pressure flash tank 3 is connected to the first high-pressure flash steam pipe 4. The end of the first high-pressure flash steam pipe 4 away from the high-pressure flash tank 3 is connected to the second high-pressure flash steam pipe 5 and the third high-pressure flash steam pipe 6 through a tee. The second high-pressure flash steam pipe 5 is connected to the high-pressure ash water heater 19.
[0053] A valve 21 is installed on the third high-pressure flash steam pipe 6. The third high-pressure flash steam pipe 6 is connected to the demineralized water heater 9. The demineralized water heater 9 is also connected to the fourth high-pressure flash steam pipe 7. The fourth high-pressure flash steam pipe 7 is connected to the gas-liquid separator 10.
[0054] The demineralized water heater 9 is also connected to a demineralized water inlet pipe 8 and a demineralized water outlet pipe 11.
[0055] The top of the demineralized water heater 9 is connected to a first flash steam vapor phase pipe 12. The end of the first flash steam vapor phase pipe 12 away from the demineralized water heater 9 is connected to a second flash steam vapor phase pipe 16 and a third flash steam vapor phase pipe 17 via a tee.
[0056] The other end of the second flash vapor phase pipeline 16 is connected to the low-pressure flash tank 15, and the other end of the third flash vapor phase pipeline 17 is connected to the deaerator 13. The bottom of the low-pressure flash tank 15 is connected to the low-pressure flash condensate pipeline 14. The top of the deaerator 13 is connected to the deaerator vapor phase pipeline 18.
[0057] This utility model's low-level waste heat recovery system achieves an average external flow rate of 380 m³ / h. 3 With a demineralized water volume of [amount missing] / h and an average temperature rise of 11.5℃, the system was rebalanced by optimizing the heat exchanger network pinch points and making rational use of excess heat. This maximized the recovery of heat and condensate, achieving the goals of reducing carbon emissions and saving energy and water. Simultaneously, the process operation provides greater flexibility, playing a crucial role in system stability. This process not only achieves energy conservation and carbon reduction but also contributes to achieving the "dual carbon target."
Claims
1. A low level waste heat recovery system characterized by, The system includes a high-pressure flash tank (3), the top of which is connected to a high-pressure ash water heater (19) via a pipe. The high-pressure ash water heater (19) is connected in sequence to a circulating water condenser (20), a gas-liquid separator (22), and a deaerator (13) via pipes. The bottom of the high-pressure flash tank (3) is connected to a low-pressure flash tank (15) via a pipe. The low-pressure flash tank (15) is also connected to a deaerator (13). The top of the high-pressure flash tank (3) is connected to a demineralized water heater (9) via a pipe. The demineralized water heater (9) is connected in sequence to a gas-liquid separator (10) and a deaerator (13) via pipes.
2. The low level waste heat recovery system of claim 1, wherein, The high-pressure flash tank (3) is connected to the gasifier black water pipe (1) and the carbon washing tower black water pipe (2) on its side wall.
3. The low level waste heat recovery system of claim 1, wherein, The top of the high-pressure flash tank (3) is connected to a first high-pressure flash steam pipe (4). The end of the first high-pressure flash steam pipe (4) away from the high-pressure flash tank (3) is connected to a second high-pressure flash steam pipe (5) and a third high-pressure flash steam pipe (6) through a tee. The second high-pressure flash steam pipe (5) is connected to a high-pressure ash water heater (19).
4. The low level waste heat recovery system of claim 3, wherein, A valve (21) is provided on the third high-pressure flash steam pipe (6). The third high-pressure flash steam pipe (6) is connected to the demineralized water heater (9). The demineralized water heater (9) is also connected to a fourth high-pressure flash steam pipe (7). The fourth high-pressure flash steam pipe (7) is connected to the gas-liquid separator (10).
5. The low level waste heat recovery system of claim 1, wherein, The demineralized water heater (9) is also connected to a demineralized water inlet pipe (8) and a demineralized water outlet pipe (11).
6. The low level waste heat recovery system of claim 1, wherein, The top of the demineralized water heater (9) is connected to a first flash steam phase pipe (12), and the end of the first flash steam phase pipe (12) away from the demineralized water heater (9) is connected to a second flash steam phase pipe (16) and a third flash steam phase pipe (17) through a tee.
7. The low-level waste heat recovery system of claim 6, wherein, The other end of the second flash vapor phase pipeline (16) is connected to the low-pressure flash tank (15), and the other end of the third flash vapor phase pipeline (17) is connected to the deaerator (13).
8. The low level waste heat recovery system of claim 7, wherein, The bottom of the low-pressure flash tank (15) is connected to a low-pressure flash condensate pipe (14).
9. The low level waste heat recovery system of claim 1, wherein, The top of the deaerator (13) is connected to a deaerator gas phase pipe (18).