Coal water slurry heating system

Abstract

The application discloses a coal water slurry heating system, which comprises a coal slurry system, a vaporization furnace connected to the coal slurry system through a connecting pipe, a scrubbing tower connected to the middle part of the vaporization furnace through a first exhaust pipe, a high-flash separator connected to the bottom of the vaporization furnace through a first liquid discharge pipe, the bottom of the scrubbing tower connected to the high-flash separator through a second liquid discharge pipe, the top of the high-flash separator connected to a high-flash separation tank through a second exhaust pipe, the bottom of the high-flash separator connected to a low-flash separator through a third liquid discharge pipe, the bottom of the high-flash separation tank connected to a gas-removing water tank through a fourth liquid discharge pipe, the top of the low-flash separator connected to the gas-removing water tank through a third exhaust pipe, and the gas-removing water tank connected to the coal slurry system through a circulating pipe. The application utilizes saturated steam heating and impact to wash the drum screen mesh, can recover low-pressure steam, and increase the heating efficiency of the system on the coal slurry.

Description

Technical Field

[0001] This invention belongs to the technical field of chemical coal slurry heating systems, specifically relating to coal-water slurry heating systems. Background Technology

[0002] The traditional flushing scheme for the mill drum screen in the coal slurry heating system involves adding flushing water through a pipeline between the top of the drum and the shell. The disadvantages of this scheme are that it cannot be operated for a long time and must rely on manual intervention for periodic flushing. At the same time, the use of water flushing affects the coal slurry concentration and reduces the gasification efficiency of the gasifier. When the flushing water temperature is low, it reduces the viscosity of the coal slurry, resulting in poor coal slurry pump flow and easy scaling of pipelines. In addition, during normal operation of the system, the deaerator directly discharges and non-condensable gas is directly vented, resulting in low coal slurry heating efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a coal-water slurry heating system that can recover low-pressure steam and increase the system's heating efficiency for coal slurry.

[0004] The technical solution adopted in this invention is: a coal-water slurry heating system, including a coal slurry system, a gasifier connected to the coal slurry system via a connecting pipe, a washing tower connected to the middle of the gasifier via a first exhaust pipe, a high flash separator connected to the bottom of the gasifier via a first drain pipe, a high flash separator connected to the bottom of the washing tower via a second drain pipe, a high flash separator connected to the top of the high flash separator via a second exhaust pipe, a low flash separator connected to the bottom of the high flash separator via a third drain pipe, a degassing water tank connected to the bottom of the high flash separator via a fourth drain pipe, a degassing water tank connected to the top of the low flash separator via a third exhaust pipe, and a degassing water tank connected to the coal slurry system via a circulation pipe.

[0005] The invention is further characterized in that,

[0006] The coal slurry system includes a coal mill, a small coal slurry tank connected to the coal mill, a low-pressure coal slurry pump connected to the side of the small coal slurry tank away from the coal mill, a water-coal slurry heater connected to the low-pressure coal slurry pump via a pipeline, a water-coal slurry heater connected to a circulation pipe, a large coal slurry tank connected to the water-coal slurry heater via a discharge pipe, a high-pressure coal slurry pump connected to the side of the large coal slurry tank away from the discharge pipe, and a connecting pipe connected to the high-pressure coal slurry pump.

[0007] The lower shell of the rotary drum screen of the coal mill is connected to a coal slurry collection plate, which is inclined. The lower shell of the rotary drum screen is also connected to a coil support block, which is located below the coal slurry collection plate. A serpentine heating plate is connected to the side of the coil support block away from the lower shell of the rotary drum screen. A baffle is connected to the lower shell of the rotary drum screen, which is located below the serpentine heating plate.

[0008] The coal slurry collection plate is installed at 3 / 4 of the length of the drum screen in the coal mill.

[0009] Steam nozzles are connected to the outer wall of the rotary screen in the coal mill. The steam nozzles are located at the top 1 / 4 arc of the return stroke of the rotary screen.

[0010] The beneficial effects of this invention are as follows: The coal-water slurry heating system of this invention utilizes the heating and impact of saturated steam to flush the mesh of the drum screen, increasing the temperature of the drum screen and the temperature inside the drum screen cavity, thereby increasing the temperature of the coal slurry without affecting the coal slurry concentration, reducing viscosity and increasing fluidity, and preventing mesh blockage. Heating of the coal-water slurry begins from the mill outlet, reducing the viscosity of the coal-water slurry and increasing its fluidity, preventing blockage of the entire coal slurry pipeline. Steam recovery and utilization are achieved without adding equipment. The two-stage heating method enhances the system's efficiency in heating the coal slurry and simultaneously increases the effective gas output of the gasifier. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the coal-water slurry heating system of the present invention;

[0012] Figure 2 This is a partial structural schematic diagram of the drum screen in the coal-water slurry heating system of the present invention;

[0013] Figure 3 This is a schematic diagram of the connection structure of the steam nozzle in the coal-water slurry heating system of the present invention.

[0014] In the diagram, 1. Rotary drum screen, 2. Coal slurry collection plate, 3. Serpentine heating plate, 4. Baffle, 5. Coil support block, 6. Lower shell of rotary drum screen, 7. Steam nozzle, 8. Coal mill, 9. Circulation pipe, 10. Connecting pipe, 11. First exhaust pipe, 12. First drain pipe, 13. Coal-water slurry heat exchanger, 15. Small coal slurry tank, 16. Low-pressure coal slurry pump, 17. Large coal slurry tank, 18. High-pressure coal slurry pump, 19. Gasifier, 20. Scrubber, 21. High flash separator, 22. High flash separator, 23. Low flash separator, 24. Degassing water tank, 25. Second drain pipe, 26. Second exhaust pipe, 27. Third exhaust pipe, 28. Fourth exhaust pipe, 29. Third exhaust pipe. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0016] This invention provides a water-coal slurry heating system, such as... Figure 1As shown, the system includes a coal slurry system. The coal slurry system is connected to a gasifier 19 via a connecting pipe 10. The central quench chamber of the gasifier 19 is connected to a scrubbing tower 20 via a first exhaust pipe 11. The bottom of the gasifier 19 is connected to a high-flash separator 21 via a first drain pipe 12. The bottom of the scrubbing tower 20 is connected to the high-flash separator 21 via a second drain pipe 25. The top of the high-flash separator 21 is connected to a high-flash separator tank 22 via a second exhaust pipe 26. The bottom of the high-flash separator 21 is connected to a low-flash separator 23 via a third drain pipe 27. The bottom of the high-flash separator tank 22 is connected to a degassing water tank 24 via a fourth drain pipe 28. The top of the low-flash separator 23 is connected to the degassing water tank 24 via a third exhaust pipe 29. The degassing water tank 24 is connected to the coal slurry system via a circulation pipe 9. The circulation pipe 9 recovers the low-pressure steam generated in the degassing water tank 24 and adds it to the coal slurry system, avoiding waste of heat resources and helping to improve heating efficiency. The ash water unit vents low-pressure steam to provide the heat required for heating the coal-water slurry, enabling phase-change-free heating. The low-pressure saturated steam temperature is 100℃-120℃, which heats the coal-water slurry to 70℃-90℃ without causing the slurry temperature to become too high and affecting the service life of the high-pressure coal slurry pump hose.

[0017] The coal slurry system includes a coal mill 8, which is connected to a small coal slurry tank 15. A low-pressure coal slurry pump 16 is connected to the side of the small coal slurry tank 15 away from the coal mill 8. The low-pressure coal slurry pump 16 is connected to a coal-water slurry heater 13 via a pipeline. The coal-water slurry heater 13 is connected to a circulation pipe 9. Low-pressure steam from the ash water section of the gasification process is recovered and reused to heat the coal slurry. The coal-water slurry heater 13 is connected to a large coal slurry tank 17 via a discharge pipe. The large coal slurry tank 17 is connected to a high-pressure coal slurry pump 18 on the side away from the discharge pipe. The high-pressure coal slurry pump 18 is connected to a connecting pipe 10. The coal slurry produced by the coal mill 8 flows into the small coal slurry tank 15, and is then pumped by the low-pressure coal slurry pump 16 to the coal-water slurry heater 13. The coal slurry is heated by the coal-water slurry heater 13 and then flows into the large coal slurry tank 17. Finally, it is pumped by the high-pressure coal slurry pump 18 to subsequent units for gasification separation.

[0018] like Figure 2As shown, the lower shell 6 of the rotary screen of the coal mill 8 is connected to a coal slurry collection plate 2, which is inclined. The lower shell 6 is also connected to a coil support block 5, which is located below the inclined side of the coal slurry collection plate 2 to facilitate the collection and diversion of coal slurry. A serpentine heating plate 3 is connected to the side of the coil support block 5 away from the lower shell 6. The lower shell 6 is connected to a baffle 4, which is located below the serpentine heating plate 3. The bottom of the baffle 4 is provided with a flow-limiting hole to promote the flow of coal slurry below the serpentine coil of the coal-water slurry, avoid slow flow or dead zones causing scaling, and also limit the flow to ensure that the coal slurry is fully heated. The size of the flow-limiting hole is calculated according to the amount of coal-water slurry. The coal slurry collection plate 2 collects the coal slurry in the rotary screen 1, and then diverts it to be heated by the serpentine heating plate 3, thus assisting the coal slurry heater 13 in heating and improving the heating efficiency. The slurry then flows out through the flow-limiting hole at the bottom of the baffle 4.

[0019] The coal slurry collection plate 2 is positioned at 3 / 4 of the length of the drum screen in the coal mill 8 to prevent the coal slurry pump from jamming due to the collection of overflowing coal slurry. The collected coal slurry flows through a ramp to the serpentine heating plate 3, where it is heated to increase fluidity and reduce viscosity. The height of the baffle 4 is higher than that of the serpentine heating plate 3, and a flow-limiting hole is opened between the bottom of the baffle 4 and the lower shell 6 of the drum screen to promote the flow of the bottom coal slurry and prevent coal slurry agglomeration, dead zones, and other phenomena. The main function of the baffle 4 is to prevent the coal slurry from flowing out too quickly and failing to be effectively heated.

[0020] like Figure 3 As shown, a steam nozzle 7 is connected to the outer wall of the drum screen 1 in the coal mill 8. The steam nozzle 7 is located at the top 1 / 4 arc of the return stroke of the drum screen. During normal operation, the coal slurry cannot reach the other end of the drum screen 1. Then, the saturated steam from the steam nozzle 7 heats and impacts the drum screen mesh, scouring it from the front. Low-pressure saturated steam is used because of its low moisture content, allowing for continuous operation without human intervention. The placement of the steam nozzle 7 in this section ensures maximum relative velocity between the steam and the drum screen 1, guaranteeing the unblocking of all mesh openings. Furthermore, this section of the drum screen has minimal coal slurry adhesion, making this location the optimal location for steam purging. The steam nozzle 7 uses 0.5 MPa-1.0 MPa steam to flush and heat the drum screen 1, using impact and viscosity reduction to unblock the mesh openings.

[0021] The working principle of the coal-water slurry heating system of this invention is as follows:

[0022] Coal slurry flows out from the drum screen 1. The coal slurry collection plate 2 collects the coal slurry in the drum screen 1, and then, after being guided, it is heated by the serpentine heating plate 3. Then, it flows out through the flow-limiting hole at the bottom of the baffle 4 into the small coal slurry tank 15. After being pumped by the low-pressure coal slurry pump 16 into the coal-water slurry heater 13 for heating, it flows into the large coal slurry tank 17. Then, it is pumped by the high-pressure coal slurry pump 18 into the gasifier 19. The gas phase coal slurry enters the washing tower 20, and the liquid phase coal slurry enters the high flash separator 21. At the same time, the liquid phase coal slurry washed in the washing tower 20 also enters the high flash separator 21. The high flash separator 22 and the low flash separator 23 operate on the same principle. Finally, it enters the degassing water tank 24. The low-pressure steam generated in the degassing water tank 21 enters the coal-water slurry heater 13 through the circulation pipe 9 to recover heat resources and avoid steam waste.

[0023] The steam injection principle of the drum screen in the coal-water slurry heating system of this invention:

[0024] The washing section is located above the return section of the drum screen, based on the analysis of the coal slurry flow pattern inside the drum screen. When the coal slurry concentration is 60%-63%, the density is 1.15t / m³-1.3t / m³. The coal-water slurry flows at half its maximum height within the drum screen. When the height reaches 3 / 4 of the drum screen, the coal slurry flows downwards due to its own weight or is thrown outwards by centrifugal force. There is virtually no coal slurry separation from the drum screen in the return section. The return section mainly relies on centrifugal force to throw the coal slurry off the mesh. When the washing water temperature is too low, the drum screen mesh is easily clogged and cannot be cleared. Especially in winter, due to the low air temperature and coal slurry temperature of around 25℃, its viscosity increases, making the return section of the drum screen prone to mesh clogging. This design allows for more accurate judgment of the coal slurry concentration and avoids slurry leakage problems.

[0025] This invention relates to a coal-water slurry heating system. Steam nozzles prevent clogging of the drum screen, and the heating coil at the bottom of the drum screen aims to increase the coal slurry temperature between the drum screen and the slurry heater section, thereby increasing the slurry's fluidity and preventing pipeline blockage. The coal-water slurry heater further increases the slurry temperature, improving fluidity, reducing the probability of pipeline blockage, lowering energy consumption of the high-pressure slurry pump, and increasing hose lifespan. This further increase in slurry temperature ultimately leads to improved carbon conversion rate, reduced oxygen consumption, and increased effective gas content within the gasifier.

Claims

1. A coal water slurry heating system, characterized by, The coal slurry system comprises a vaporization furnace (19) connected through a connecting pipe (10), a scrubbing tower (20) connected to the middle part of the vaporization furnace (19) through a first exhaust pipe (11), a high-flash separator (21) connected to the bottom of the vaporization furnace (19) through a first liquid discharge pipe (12), the bottom of the scrubbing tower (20) connected to the high-flash separator (21) through a second liquid discharge pipe (25), a high-flash separation tank (22) connected to the top of the high-flash separator (21) through a second exhaust pipe (26), a low-flash separator (23) connected to the bottom of the high-flash separator (21) through a third liquid discharge pipe (27), a gas removal water tank (24) connected to the bottom of the high-flash separation tank (22) through a fourth liquid discharge pipe (28), and the top of the low-flash separator (23) connected to the gas removal water tank (24) through a third exhaust pipe (29), wherein the gas removal water tank (24) is connected to the coal slurry system through a circulating pipe (9). The coal slurry system comprises a coal mill (8) connected to a small coal slurry tank (15), the small coal slurry tank (15) connected to a low-pressure coal slurry pump (16) on the side away from the coal mill (8), the low-pressure coal slurry pump (16) connected to a coal water slurry heater (13) through a pipeline, the coal water slurry heater (13) connected to the circulating pipe (9), the coal water slurry heater (13) connected to a large coal slurry tank (17) through a discharge pipe, the large coal slurry tank (17) connected to a high-pressure coal slurry pump (18) on the side away from the discharge pipe, and the high-pressure coal slurry pump (18) connected to the connecting pipe (10). The coal mill (8) is connected to a coal slurry collecting plate (2) on the lower shell of the roller screen (1), the coal slurry collecting plate (2) is arranged obliquely, the roller screen lower shell (6) is further connected to a coil pipe support block (5), the coil pipe support block (5) is arranged below the coal slurry collecting plate (2), the coil pipe support block (5) is connected to a serpentine heating coil (3) on the side away from the roller screen lower shell (6), the roller screen lower shell (6) is connected to a baffle (4), and the baffle (4) is arranged below the serpentine heating coil (3). The outer wall of the roller screen (1) in the coal mill (8) is connected to a steam nozzle (7).

2. The coal water slurry heating system as claimed in claim 1, wherein, The coal slurry collecting plate (2) is arranged at 3 / 4 of the length of the roller screen in the coal mill (8).

3. The coal water slurry heating system of claim 2, wherein, The steam nozzle (7) is arranged at 1 / 4 of the top arc of the return stroke of the roller screen.

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