A black water heat recovery device

Abstract

This utility model provides a blackwater waste heat recovery device, belonging to the field of chemical technology. Specifically, the blackwater from the gasifier is flashed sequentially through a high-pressure flash tank, a low-pressure flash tank, and a vacuum flash tank before finally reaching a sedimentation tank. An additional process pipeline is added upstream of the blackwater regulating valve at the bottom of the high-pressure flash tank. This process pipeline is connected in parallel to the shell side of a high-pressure carbon dioxide heat exchanger, where it exchanges heat with the tube side of the high-pressure carbon dioxide heat exchanger. After heat exchange, the temperature is increased and the blackwater is delivered to users. The blackwater from the high-pressure flash tank is cooled after heat exchange in the high-pressure CO2 heat exchanger. The flow rate to the low-pressure flash tank is controlled by adjusting the downstream blackwater flow regulating valve, indirectly reducing the heat load of the low-pressure flash tank. The flow rate to the vacuum flash tank is controlled by the downstream blackwater regulating valve, further reducing the heat load of the vacuum flash tank. The vacuum pump of the vacuum flash tank is reduced or shut down based on the vacuum flash pressure, achieving energy savings. The waste heat from the high-pressure flash blackwater replaces low-pressure steam, indirectly reducing the vacuum flash load.

Description

Technical Field

[0001] This utility model relates to the field of chemical technology, specifically a black water waste heat recovery device. Background Technology

[0002] Generally speaking, this utility model addresses the shortcomings of existing technologies by providing a reasonably designed and efficient method for recovering waste heat from black water.

[0003] The black water from the gasifier, at an outlet temperature of 202°C and 4.1 MPa, enters a high-pressure flash tank for flash evaporation at a pressure of 0.5 MPa and a temperature of 155°C. The bottom black water is then sent to a low-pressure flash tank for flash evaporation at a temperature of 133°C and 0.2 MPa. The flash vapor from the top of the low-pressure flash tank is sent to a deaerator for deoxygenation of ash water, conversion of low-temperature condensate, and replenishment of demineralized water for system replenishment. The black water after low-pressure flash evaporation then enters a vacuum flash tank for further flash evaporation at a temperature of 92°C and -0.02 MPa. After condensation in a vacuum flash condenser, the flash vapor enters a vacuum flash separator. The separated water flows by gravity to a settling tank, while non-condensable gases are discharged to the atmosphere by a vacuum pump. The true flash pressure is affected by the low flash pressure and the black water temperature. During normal production, it is regulated by a vacuum pump. When pressure fluctuations are large, additional vacuum pumps need to be used to control the pressure, increasing power consumption and making operation uneconomical. Summary of the Invention

[0004] The technical objective of this invention is to address the shortcomings of existing technologies and provide a black water waste heat recovery device.

[0005] The technical solution of this utility model is implemented in the following way: A black water waste heat recovery device of this utility model is characterized by the following method:

[0006] The black water from the gasifier is flashed sequentially through a high-pressure flash tank, a low-pressure flash tank, and a vacuum flash tank before finally reaching the sedimentation tank.

[0007] An additional process pipeline is added upstream of the black water pipeline regulating valve at the bottom of the high-pressure flash tank. This process pipeline is connected in parallel to the shell side of the high-pressure carbon dioxide heat exchanger, where it exchanges heat with the tube side of the high-pressure carbon dioxide heat exchanger. After heat exchange, the temperature is increased, and the water is then supplied to various users. Specifically:

[0008] The downstream branch of the process pipeline is connected to the black water inlet pipeline of the high-pressure CO2 heat exchanger. The black water inlet pipeline of the high-pressure CO2 heat exchanger is connected to the shell side of the high-pressure CO2 heat exchanger. The black water pipeline exiting the shell side after heat exchange is connected to the downstream of the black water pipeline regulating valve at the bottom of the high-pressure flash tank.

[0009] The high-pressure CO2 tank is connected to the CO2 inlet pipeline of the high-pressure CO2 heat exchanger. The CO2 inlet pipeline runs through the tube side of the high-pressure CO2 heat exchanger, with the inlet at the bottom and the outlet at the top. The CO2 outlet pipeline of the outlet tube side is connected to the CO2 pipelines to each user.

[0010] The low-pressure steam downstream branch is connected to the low-pressure steam inlet pipeline of the high-pressure CO2 heat exchanger. The low-pressure steam inlet pipeline is connected to the shell side of the high-pressure CO2 heat exchanger, and a condensate outlet pipeline is configured at the bottom of the shell side.

[0011] The downstream of the black water pipe regulating valve at the bottom of the high-pressure flash tank is connected to the low-pressure flash tank. The black water pipe at the bottom of the low-pressure flash tank is connected to the vacuum flash tank. The black water pipe at the bottom of the vacuum flash tank is connected to the sedimentation tank.

[0012] The black water from the high-pressure flash tank is cooled down after passing through the high-pressure CO2 heat exchanger. The flow rate to the low-pressure flash tank is controlled by adjusting the downstream black water flow regulating valve, which indirectly reduces the heat load of the low-pressure flash tank. The flow rate to the vacuum flash tank is controlled by the downstream black water regulating valve, which reduces the heat load of the vacuum flash tank. The vacuum pump of the vacuum flash tank is reduced or stopped according to the vacuum flash pressure to achieve energy saving.

[0013] The black water inlet pipeline of the high-pressure CO2 heat exchanger, the shell side of the high-pressure CO2 heat exchanger, and the black water outlet pipeline constitute the black water waste heat release route.

[0014] as well as,

[0015] The CO2 inlet pipeline, the tube side of the high-pressure CO2 heat exchanger, and the CO2 outlet pipeline of the tube side constitute the temperature rise path of the high-pressure CO2.

[0016] Waste heat from blackwater is used to supply high-pressure CO2 for heating;

[0017] The low-pressure steam inlet pipeline, the shell side of the high-pressure CO2 heat exchanger, and the condensate outlet pipeline together form the heat replenishment route.

[0018] The above configuration is set up in two sets, that is, each pipeline and high-pressure CO2 heat exchanger is configured with two sets in parallel, one in operation and one on standby, which can be switched at any time.

[0019] The process pipeline is equipped with temperature monitors, pressure monitors, flow monitors, temperature regulating valves, and black water shut-off valves.

[0020] Manual valves and backflow preventers are installed on each inlet and outlet pipe of the high-pressure CO2 heat exchanger for online system cleaning.

[0021] Each outlet pipe of the high-pressure CO2 heat exchanger is equipped with flow, temperature, and pressure gauges. The outlet temperature is automatically interlocked with the black water pipe regulating valve to adjust the inlet flow rate according to the temperature, thereby maintaining a stable carbon dioxide temperature at the heat exchanger outlet.

[0022] The shell side of the high-pressure CO2 heat exchanger is equipped with a pressure gauge and a drain. When the black water side pressure exceeds the standard, the black water shut-off valve is interlocked to prevent high pressure from passing through to low pressure.

[0023] Manual valves and drains are installed on the black water inlet and outlet pipes of the high-pressure flash tank. When the pressure difference across the heat exchanger is high, the standby heat exchanger is switched off and the system is cleaned online before being put into standby mode.

[0024] The present invention relates to a black water waste heat recovery device, the structure of which is as described above.

[0025] The application of the black water waste heat recovery device in the downstream waste heat recovery process of the gasifier.

[0026] The application of the black water waste heat recovery device in the downstream waste heat recovery process of the gasifier.

[0027] The working principle of this utility model:

[0028] Black water from the gasifier quench chamber, ash separator, and bottom of the washing tower is depressurized and sent to a high-pressure flash tank for flash evaporation. The flash steam from the top after flash evaporation enters a flash steam scrubber, where it exchanges heat countercurrently with deoxygenated water from the deoxygenated water pump under the action of the trays. Then, it enters a flash steam cooler for condensation and then enters a high-pressure flash separator. The separated condensate can be sent to an ash water tank or a settling tank. The flash steam from the top of the high-pressure flash separator is sent to the flare device for complete combustion and discharge after pressure regulation during start-up, shutdown, or accidents. The ash water discharged from the bottom of the flash steam scrubber is pressurized by a high-pressure ash water pump and sent to the washing tower and slag lock hopper for pressurization and indirect use.

[0029] Black water from the bottom of the high-pressure flash tank is sent to the low-pressure flash tank for flash evaporation. Flash vapor from the top of the low-pressure flash tank is sent to the deaerator for deoxygenation of grey water, conversion of low-temperature condensate, and replenishment of demineralized water. The black water after low-pressure flash evaporation then enters the vacuum flash tank for further flash evaporation. The flash vapor is condensed by the vacuum flash condenser and then enters the vacuum flash separator. The separated water flows by gravity to the settling tank, while non-condensable gases are discharged to the atmosphere by a vacuum pump. The liquid and solid mixture at the bottom of the vacuum flash tank flows by gravity into the settling tank. Water pumped from the slag pool is sent to the vacuum flash tank for treatment.

[0030] High-pressure carbon dioxide is mainly used in pulverized coal pressurization and conveying systems, flame detector purging protection, gasifier annular space purging protection, start-up burner fuel gas pipeline purging, and pulverized coal burner pulverized coal pipeline purging. During normal production, carbon dioxide is pressurized to 6.5 MPa and 93 degrees Celsius by the carbon dioxide generator. One path enters the pulverized coal pressurization carbon dioxide buffer tank for pulverized coal pressurization, while the other path enters the pulverized coal conveying carbon dioxide buffer tank. Low-pressure steam (2 tons / hour) is used to heat the carbon dioxide heat exchanger to 105 degrees Celsius for use as the pulverized coal conveying medium, which is then delivered to the gasifier burners and various protective gases.

[0031] The beneficial effects of this utility model compared with the prior art are:

[0032] This utility model discloses a blackwater waste heat recovery device that utilizes the waste heat from the bottom of the high-flash blackwater to heat pulverized coal and transport high-pressure carbon dioxide gas. This allows the waste heat from the blackwater to replace the low-pressure steam in the high-pressure carbon dioxide heat exchanger, simultaneously reducing the temperature of the high-flash blackwater flowing to the low-flash zone and decreasing the heat transferred from the low-flash zone to the true flash zone. This enables the vacuum pump to be shut down, and the true flash pressure to be controlled, achieving energy conservation and consumption reduction. The high-flash blackwater waste heat replaces the low-pressure steam, indirectly reducing the true flash load and disabling the vacuum pump.

[0033] This invention adds a heating pipeline for the high-flash bottom black water to the high-pressure carbon dioxide heat exchanger. The black water exchanges heat with the high-pressure carbon dioxide, replacing the low-pressure steam. The black water after heat exchange goes to the low-flash tank, and the low-flash black water goes to the true flash tank. This indirectly reduces the load on the low-flash and true flash tanks, and allows the true flash pressure to be controlled after the vacuum pump is shut down, thus achieving the goal of cost reduction and efficiency improvement.

[0034] This utility model can achieve the following:

[0035] 1. Black water waste heat recovery and utilization can save 2 tons of steam per hour.

[0036] 2. Two high-pressure carbon dioxide heat exchangers are installed in parallel to enable online cleaning and ensure long-term operation.

[0037] 3. After the true flash heat load is reduced, the vacuum pump is stopped, resulting in significant energy savings.

[0038] 4. Cost-effective investment, significant energy-saving effect, and reduced production costs.

[0039] 5. It is equipped with interlocking, which provides a high safety factor, simple structure, easy operation, and convenient maintenance.

[0040] This invention aims to ensure safety, energy conservation, and environmental protection by using waste heat from black water to replace low-pressure steam at the outlet temperature of a high-pressure carbon dioxide heat exchanger, thereby saving energy. Simultaneously, it reduces the flash heat load, disables the vacuum pump, saves electricity, and lowers production costs.

[0041] The black water waste heat recovery device of this utility model is reasonably designed, simple in structure, safe and reliable, easy to use and easy to maintain, and has great value for promotion and application. Attached Figure Description

[0042] Appendix Figure 1 This is a schematic diagram of the structure of this utility model.

[0043] The markings in the attached diagram represent:

[0044] 1. Black water pipeline from the gasifier,

[0045] 2. High-pressure flash tank; 3. Low-pressure flash tank; 4. Vacuum flash tank; 5. Sedimentation tank.

[0046] 6. Black water pipeline regulating valve; 7. Process pipeline;

[0047] 8. High-pressure carbon dioxide heat exchanger,

[0048] 9. Shell side of the high-pressure carbon dioxide heat exchanger.

[0049] 10. Tube side of high-pressure carbon dioxide heat exchanger,

[0050] 11. Black water inlet pipeline of high-pressure CO2 heat exchanger

[0051] 12. Black water pipeline at the outlet.

[0052] 13. High-pressure CO2 tank

[0053] 14. CO2 inlet pipeline of the high-pressure CO2 heat exchanger; 15. CO2 outlet pipeline of the tube side.

[0054] 16. CO2 is delivered to the pipelines of each user.

[0055] 17. Low-pressure steam,

[0056] 18. Low-pressure steam inlet pipeline of high-pressure CO2 heat exchanger; 19. Condensate outlet pipeline.

[0057] 20. Black water shut-off valve. Detailed Implementation

[0058] The following is a detailed description of a black water waste heat recovery device according to the present invention, with reference to the accompanying drawings.

[0059] As shown in the attached drawings, this utility model discloses a black water waste heat recovery device, comprising a high-pressure flash tank (hereinafter referred to as high flash), a low-pressure flash tank (hereinafter referred to as low flash), and a vacuum flash tank (hereinafter referred to as true flash).

[0060] Specific implementation:

[0061] This invention, while ensuring the safe and stable operation of the system, enables online cleaning of the heat exchanger. Two heat exchangers are connected in parallel, one in operation and one on standby, and can be switched off at any time.

[0062] A DN200 pipeline is added before the regulating valve in the high-flash bottom black water pipeline (pressure 0.5MPa, temperature 155°C) and connected to the shell side of the high-pressure carbon dioxide heat exchanger. It exchanges heat with the high-pressure carbon dioxide in the tube side (pressure 5.1MPa, temperature 93°C). After heat exchange, the temperature is raised to 105°C and delivered to users. A new DN200 manual valve is added to the high-flash bottom black water pipeline. A branch line is connected to the heat exchanger inlet pipeline before the DN200 manual valve. This pipeline is equipped with temperature, pressure, flow, electric valves, and a shut-off valve. The DN200 pipeline at the heat exchanger outlet connects to the regulating valve before the newly added manual valve in the high-flash bottom black water pipeline. The flow rate of the black water after heat exchange to the low-flash tank is controlled by the regulating valve. Both the black water inlet and outlet pipelines are equipped with manual valves and drain lines. Pressure, temperature, flow, and differential pressure gauges are installed on these pipelines. The carbon dioxide heat exchanger's inlet and outlet pipes are equipped with manual valves and backflow preventers for easy online cleaning after system shutdown. The outlet pipe is equipped with flow, temperature, and pressure gauges. The outlet temperature and black water regulating valve are automatically adjusted, regulating the inlet flow rate to maintain a stable carbon dioxide temperature at the heat exchanger outlet. The black water temperature after heat exchange drops from 155°C to 130°C, controlled by the black water regulating valve to manage the flow to the low-flash tank. The heat exchanger shell side is equipped with a pressure gauge and backflow preventers. When the black water side pressure exceeds the limit, the black water shut-off valve is interlocked and closed to prevent high pressure from crossing into low pressure. Both the high-flash black water inlet and outlet pipes are equipped with manual valves and backflow preventers. When the pressure difference across the heat exchanger is high, the standby heat exchanger is switched off and can be used after online cleaning of the system.

[0063] After the high flash black water heat exchange, the temperature drops to about 130 degrees Celsius. The flow rate to the low flash tank is controlled by adjusting the black water flow regulating valve, which indirectly reduces the low flash heat load (temperature 108 degrees Celsius). The flow rate to the true flash tank is controlled by the black water regulating valve, which reduces the true flash heat load (temperature 68 degrees Celsius). The vacuum pump (75KW.H) is reduced or stopped according to the true flash pressure to achieve energy saving.

[0064] This utility model:

[0065] 1. Add a new black water pipeline to the heat exchanger, and set the electric regulating valve and heat exchanger outlet temperature for automatic control to achieve automatic temperature control.

[0066] 2. The newly added black water pipeline inlet and outlet lines are equipped with differential pressure gauges and a backup heat exchanger, enabling online cleaning.

[0067] 3. When the shell-side pressure of the heat exchanger exceeds the standard, the black water inlet pipeline shut-off valve will be interlocked to ensure safety.

[0068] 4. This utility model has low investment cost, significant energy-saving effect and high safety factor.

Claims

1. A black water heat recovery device, characterized by Its structure is: The black water from the gasifier is flashed sequentially through a high-pressure flash tank, a low-pressure flash tank, and a vacuum flash tank before finally reaching the sedimentation tank. Add a process pipeline upstream of the black water pipeline regulating valve at the bottom of the high-pressure flash tank. The process pipeline is connected to the shell side of the high-pressure carbon dioxide heat exchanger and exchanges heat with the tube side of the high-pressure carbon dioxide heat exchanger. After heat exchange, the temperature is increased and the water is delivered to each user. Specifically: The downstream branch of the process pipeline is connected to the black water inlet pipeline of the high-pressure CO2 heat exchanger. The black water inlet pipeline of the high-pressure CO2 heat exchanger is connected to the shell side of the high-pressure CO2 heat exchanger. The black water pipeline exiting the shell side after heat exchange is connected to the downstream of the black water pipeline regulating valve at the bottom of the high-pressure flash tank. The high-pressure CO2 tank is connected to the CO2 inlet pipeline of the high-pressure CO2 heat exchanger. The CO2 inlet pipeline runs through the tube side of the high-pressure CO2 heat exchanger, with the inlet at the bottom and the outlet at the top. The CO2 outlet pipeline of the outlet tube side is connected to the CO2 pipelines to each user. The low-pressure steam downstream branch is connected to the low-pressure steam inlet pipeline of the high-pressure CO2 heat exchanger. The low-pressure steam inlet pipeline is connected to the shell side of the high-pressure CO2 heat exchanger, and a condensate outlet pipeline is configured at the bottom of the shell side. The downstream of the black water pipe regulating valve at the bottom of the high-pressure flash tank is connected to the low-pressure flash tank. The black water pipe at the bottom of the low-pressure flash tank is connected to the vacuum flash tank. The black water pipe at the bottom of the vacuum flash tank is connected to the sedimentation tank. The black water from the high-pressure flash tank is cooled down after passing through the high-pressure CO2 heat exchanger. The flow rate to the low-pressure flash tank is controlled by adjusting the downstream black water flow regulating valve, which indirectly reduces the heat load of the low-pressure flash tank. The flow rate to the vacuum flash tank is controlled by the downstream black water regulating valve, which reduces the heat load of the vacuum flash tank. The vacuum pump of the vacuum flash tank is reduced or stopped according to the vacuum flash pressure to achieve energy saving.

2. The black water waste heat recovery device according to claim 1, characterized in that: The black water inlet pipeline of the high-pressure CO2 heat exchanger, the shell side of the high-pressure CO2 heat exchanger, and the black water outlet pipeline constitute the black water waste heat release route. as well as, The CO2 inlet pipeline, the tube side of the high-pressure CO2 heat exchanger, and the CO2 outlet pipeline of the tube side constitute the temperature rise path of the high-pressure CO2. Waste heat from blackwater is used to supply high-pressure CO2 for heating; The low-pressure steam inlet pipeline, the shell side of the high-pressure CO2 heat exchanger, and the condensate outlet pipeline together form the heat replenishment route. The above configuration is set up in two sets, that is, each pipeline and high-pressure CO2 heat exchanger is configured with two sets in parallel, one in operation and one on standby, which can be switched at any time.

3. The black water waste heat recovery device according to claim 1, characterized in that: The process pipeline is equipped with temperature monitors, pressure monitors, flow monitors, temperature regulating valves, and black water shut-off valves.

4. A black water waste heat recovery device according to claim 3, characterized in that: Manual valves and backflow preventers are installed on each inlet and outlet pipe of the high-pressure CO2 heat exchanger for online system cleaning. Each outlet pipe of the high-pressure CO2 heat exchanger is equipped with flow, temperature, and pressure gauges. The outlet temperature is automatically interlocked with the black water pipe regulating valve to adjust the inlet flow rate according to the temperature, thereby maintaining a stable carbon dioxide temperature at the heat exchanger outlet.

5. A black water waste heat recovery device according to claim 4, characterized in that: The shell side of the high-pressure CO2 heat exchanger is equipped with a pressure gauge and a drain. When the black water side pressure exceeds the standard, the black water shut-off valve is interlocked to prevent high pressure from passing through to low pressure. Manual valves and drains are installed on the black water inlet and outlet pipes of the high-pressure flash tank. When the pressure difference across the heat exchanger is high, the standby heat exchanger is switched off and the system is cleaned online before being put into standby mode.

Images