An emergency water replenishment system for a flash evaporation system

Abstract

The present invention provides an emergency water replenishment system for a flash evaporation system, which includes an evaporation hot water tower and a high-temperature hot water storage tank. The evaporation hot water tower includes an evaporation chamber and a hot water chamber. The hot water chamber is connected to the high-temperature hot water storage tank through a first connection pipeline. The hot water chamber is connected to a first ash water pipeline, and the high-temperature hot water storage tank is connected to a second ash water pipeline. The first ash water pipeline and the second ash water pipeline are aggregated and then connected to the ash water main pipeline. A ash water regulating valve is provided on the first ash water pipeline, and a water replenishment flow regulating valve is provided on the second ash water pipeline. Through the water replenishment system of the high-temperature hot water storage tank, the present invention achieves the water system balance of the gasification device, avoids the problem that the water storage capacity of the high-temperature hot water storage tank is reduced due to water entrainment caused by scale formation on the trays of the evaporation hot water tower, ensures the stable operation of the gasification device, and reduces the parking loss; it solves the safety hazards such as the full level of the acid gas separation tank caused by water entrainment in the evaporation hot water tower and the ash water flowing into the flare system, resulting in flare water hammer.

Description

Technical Field

[0001] The invention relates to an emergency water replenishment system for a flash evaporation system, belonging to the field of flash evaporation systems for gasification devices. Background Art

[0002] The flash evaporation system of the gasification device includes evaporation hot water tower, low-pressure flash tank, vacuum flash tank and other equipment. The evaporation hot water tower is the core equipment of the entire flash evaporation system. The evaporation hot water tower consists of two parts: evaporation chamber and hot water chamber. The evaporation chamber and hot water chamber of the evaporation hot water tower work together to achieve the process goals: recover the heat of black water, heat up the hot water returning to the system, recover part of the black water (steam) by evaporation, and supplement the returned gray water flow to desorb the acid gas and non-condensable gas dissolved in the black water.

[0003] The three streams of washed black water from the gasifier, cyclone separator and water washing tower are regulated and controlled and decompressed before being sent to the evaporation chamber of the evaporation hot water tower. The decompressed black water flashes under reduced pressure in the evaporation chamber of the evaporation hot water tower, and the water vapor and some of the acid gases (CO2, H2S) dissolved in the black water are quickly flashed out, and enter the upper hot water chamber of the evaporation hot water tower through the riser, and directly contact and exchange heat with the gray water delivered by the low-pressure gray water pump, the deoxygenated water delivered by the deoxygenation water pump, and the low-temperature conversion condensate delivered by the conversion system, and then flow into the high-temperature hot water tank.

[0004] The hot water chamber of the evaporative hot water tower generally has 7 layers of tower plates. After a cycle of use, the tower plates will be scaled, resulting in a larger pressure difference between the hot water chamber and the evaporation chamber of the evaporative hot water tower. When the flash steam passes through the tower plates, the flow rate increases, and water or mist entrainment occurs. Most of the water is carried away by the gas phase, which can easily cause the acid gas separation tank to be full, and the gray water will leak into the flare system and cause the flare water hammer phenomenon; only a small part of the hot water after heat exchange with the flash steam enters the high-temperature hot water storage tank. Due to the water carried by the evaporative hot water tower, the water in the high-temperature hot water storage tank is reduced, which can easily cause the entire gasification system to be unbalanced, the synthesis gas temperature of the water washing tower to be high and the washing capacity to deteriorate, and the liquid level of the water washing tower to be reduced, which in turn leads to the risk of reducing the load or stopping the gasifier, posing a safety hazard. Summary of the invention

[0005] In order to solve the above technical problems, an emergency water replenishment system for a flash evaporation system is proposed. The technical solution is as follows:

[0006] An emergency water replenishment system for a flash evaporation system comprises an evaporative hot water tower and a high-temperature hot water storage tank, wherein the evaporative hot water tower comprises an evaporation chamber and a hot water chamber, wherein the hot water chamber is connected to the high-temperature hot water storage tank via a first connecting pipeline, wherein the hot water chamber is connected to a first gray water pipeline, wherein the high-temperature hot water storage tank is connected to a second gray water pipeline, wherein the first gray water pipeline and the second gray water pipeline are combined and connected to a gray water main, wherein a gray water regulating valve is arranged on the first gray water pipeline, and a water replenishment flow regulating valve is arranged on the second gray water pipeline.

[0007] Preferably, the evaporation chamber is connected to the black water pipeline of the gasifier, the black water pipeline of the cyclone separator, and the black water pipeline of the water washing tower, and the hot water chamber is connected to the deoxidized water pipeline and the conversion condensate pipeline.

[0008] Preferably, the hot water chamber is connected to the conversion stripping tower and the sour gas heat exchanger through a second connecting pipeline, and the sour gas heat exchanger is connected to the sour gas separation tank through a third connecting pipeline.

[0009] Preferably, the high-temperature hot water storage tank is connected to the high-temperature hot water pump through a fourth connecting pipeline, and the high-temperature hot water pump is connected to the water washing tower pipeline.

[0010] Preferably, a liquid level gauge is provided on the high-temperature hot water storage tank.

[0011] Preferably, the liquid level gauge, the grey water regulating valve, and the make-up water flow regulating valve are electrically connected to the PLC controller respectively.

[0012] The present invention achieves the water system balance of the gasification device through the make-up water system of the high-temperature hot water storage tank, avoids the problem that the trays of the evaporation hot water tower are water-carrying due to scaling, reducing the water storage capacity of the high-temperature hot water storage tank, ensures the stable operation of the gasification device, and reduces the parking loss; solves the safety hazards such as the liquid level of the sour gas separation tank being full due to water-carrying in the evaporation hot water tower, and the grey water flowing into the flare system, causing flare water hammer. Description of the Drawings

[0013] Figure 1 is a schematic structural diagram of an emergency make-up water system of a flash evaporation system of the present invention.

[0014] In the figure: 1. Evaporation hot water tower; 2. High-temperature hot water storage tank; 3. Evaporation chamber; 4. Hot water chamber; 5. First connecting pipeline; 6. First grey water pipeline; 7. Second grey water pipeline; 8. Grey water main pipeline; 9. Grey water regulating valve; 10. Make-up water flow regulating valve; 11. Gasifier black water pipeline; 12. Cyclone separator black water pipeline; 13. Water washing tower black water pipeline; 14. Deoxidized water pipeline; 15. Conversion condensate pipeline; 16. Second connecting pipeline; 17. Sour gas heat exchanger; 18. Third connecting pipeline; 19. Sour gas separation tank; 20. Fourth connecting pipeline; 21. High-temperature hot water pump; 22. Water washing tower pipeline; 23. Liquid level gauge. Detailed Embodiments

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0016] When the pressure difference between the evaporation chamber 3 and the hot water chamber 4 of the evaporation hot water tower 1 due to tray fouling ≥ 50 kPa, the evaporation hot water tower 1 shows a water-carrying phenomenon. Most of the three streams of water, namely deoxygenated water, conversion condensate, and ash water, entering the hot water chamber 4 are carried by the flash steam flashed in the hot water chamber 4 to the acid gas separation tank 19, resulting in a full liquid level in the acid gas separation tank 19; a small part of the water flows by gravity to the high-temperature hot water storage tank 2 after heat exchange through the trays in the hot water chamber 4. The water in the high-temperature hot water storage tank 2 is pressurized and transported to the water washing tower by the high-temperature hot water pump 21, and the water volume cannot meet the washing requirements of the water washing tower, which is likely to cause a high temperature of the synthesis gas and a poor washing capacity, and the liquid level of the water washing tower decreases, leading to the shutdown of the gasification unit.

[0017] To solve the above problems, the present invention proposes an emergency water replenishment system for a flash evaporation system, as Figure 1 shown, which includes an evaporation hot water tower 1 and a high-temperature hot water storage tank 2. The evaporation hot water tower 1 includes an evaporation chamber 3 and a hot water chamber 4. The hot water chamber 4 is connected to the high-temperature hot water storage tank 2 through a first connection pipeline 5. The hot water chamber 4 is connected to a first ash water pipeline 6, and the high-temperature hot water storage tank 2 is connected to a second ash water pipeline 7. The first ash water pipeline 6 and the second ash water pipeline 7 are aggregated and then connected to the ash water main pipeline 8. A ash water regulating valve 9 is provided on the first ash water pipeline 6, and a water replenishment flow regulating valve 10 is provided on the second ash water pipeline 7. The evaporation chamber 3 is connected to the gasification furnace black water pipeline 11, the cyclone separator black water pipeline 12, and the water washing tower black water pipeline 13. The hot water chamber 4 is connected to a deoxygenated water pipeline 14 and a conversion condensate pipeline 15. The hot water chamber 4 is connected to a conversion stripping tower and an acid gas heat exchanger 17 through a second connection pipeline 16. The acid gas heat exchanger 17 is connected to the acid gas separation tank 19 through a third connection pipeline 18. The gas-phase flash steam in the hot water chamber 4 at the top of the evaporation hot water tower 1 is divided into: one way goes to the conversion stripping tower to replace the low-pressure steam; one way goes to the acid gas heat exchanger 17 for condensation. After the acid gas is condensed, it enters the acid gas separation tank 19 for gas-liquid separation. The acid gas passes through a pressure regulating valve and goes to sulfur recovery, or according to the production conditions, the acid gas is discharged to the flare for combustion; the acid condensate at the bottom of the acid gas separation tank 19 is sent to the ash water tank for reuse. These two ways are selectively used according to the production unit situation. If the conversion stripping tower does not use the flash steam, all the flash steam in the hot water chamber 4 goes to the acid heat exchanger 17 for use. The high-temperature hot water storage tank 2 is connected to the high-temperature hot water pump 21 through a fourth connection pipeline 20, and the high-temperature hot water pump 21 is connected to the water washing tower pipeline 22. A liquid level gauge 23 is provided on the high-temperature hot water storage tank 2, and the liquid level gauge 23, the ash water regulating valve 9, and the water replenishment flow regulating valve 10 are respectively electrically connected to the PLC controller.

[0018] The present invention mainly replenishes water to the high-temperature hot water storage tank of the evaporation hot water tower. By replenishing water through the second ash water pipeline 7, the liquid level of the high-temperature hot water storage tank 2 is ensured, the water system of the gasification unit is balanced, and the hidden danger of water hammer in the flare system is avoided.

[0019] Generally, the amount of ash water accounts for about 50-70% of the total water volume entering the evaporation hot water tower 1. A second ash water pipeline 7 is added and the ash water flow regulating valve 10 is used to control the amount of ash water entering the high-temperature hot water storage tank 2 to ensure the liquid level. The specific operation is as follows: When the evaporation hot water tower 1 causes water entrainment due to tray fouling and the liquid level of the high-temperature hot water storage tank 2 ≤ 30%, the ash water flow regulating valve 10 is interlocked with the liquid level of the high-temperature hot water storage tank 2. The PLC controller controls the ash water flow regulating valve 10 to open and replenish water to the high-temperature hot water storage tank 2. At the same time, the ash water regulating valve 9 is controlled to slowly close, aiming to always keep the total amount of ash water unchanged and prevent the ash water pump from tripping due to sudden increase in flow rate resulting in pump overcurrent; when the liquid level of the high-temperature hot water storage tank 2 > 30%, the PLC controller controls the ash water flow regulating valve 10 to slowly close as the liquid level rises, and at the same time controls the ash water regulating valve 9 to slowly open. This not only ensures that the liquid level of the high-temperature hot water storage tank 2 is controlled within the normal range, but also stabilizes the safe operation of the unit. During the process of replenishing water to the high-temperature hot water storage tank 2, since the total amount of ash water remains unchanged, the amount of ash water entering the hot water chamber 4 relatively decreases, and at the same time the amount of water entrainment decreases, ensuring the normal liquid level of the acid gas separation tank 19.

[0020] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An emergency water replenishment system for a flash evaporation system, characterized in that: It includes an evaporation hot water tower and a high-temperature hot water storage tank. The evaporation hot water tower includes an evaporation chamber and a hot water chamber. The hot water chamber is connected to the high-temperature hot water storage tank through a first connection pipeline. The hot water chamber is connected to a first ash water pipeline. The high-temperature hot water storage tank is connected to a second ash water pipeline. The first ash water pipeline and the second ash water pipeline are aggregated and then connected to the ash water main pipeline. A ash water regulating valve is provided on the first ash water pipeline, and a make-up water flow regulating valve is provided on the second ash water pipeline; The evaporation chamber is connected to the gasifier black water pipeline, the cyclone separator black water pipeline and the water washing tower black water pipeline. The hot water chamber is connected to the deoxidized water pipeline and the conversion condensate pipeline; The hot water chamber is connected to the acid gas heat exchanger through a second connection pipeline. The acid gas heat exchanger is connected to the acid gas separation tank through a third connection pipeline.

2. The emergency water replenishment system of a flash evaporation system according to claim 1, characterized in that: The high-temperature hot water storage tank is connected to a high-temperature hot water pump through a fourth connection pipeline. The high-temperature hot water pump is connected to the water washing tower pipeline.

3. The emergency water replenishment system of a flash evaporation system according to claim 1, characterized in that: A liquid level gauge is provided on the high-temperature hot water storage tank.

4. The emergency water replenishment system of a flash evaporation system according to claim 3, characterized in that: The liquid level gauge, the ash water regulating valve and the make-up water flow regulating valve are respectively electrically connected to a PLC controller.

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