A low-pressure waste heat boiler blowdown water waste heat utilization system
By using plate heat exchangers in the waste heat utilization system of low-pressure waste heat boiler wastewater, the problem of unutilized waste heat in wastewater is solved, achieving efficient energy utilization and safe and stable operation of equipment, and reducing the operating cost of deaerator.
Patent Information
- Application Number
- CN202521772430.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-20
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-08-20
AI Technical Summary
In existing technologies, the waste heat from the wastewater discharged by low-pressure waste heat boilers is not effectively utilized, leading to energy waste, safety hazards, and thermal pollution problems.
A waste heat utilization system for wastewater from a low-pressure waste heat boiler was designed. The wastewater is exchanged with the deaerator feedwater through a plate heat exchanger. The heat of the wastewater is used to raise the temperature of the deaerator feedwater and lower the temperature of the wastewater. The condensate is collected and discharged into the sewer well. Combined with flexible valve control, the system can be ensured to operate normally under different working conditions.
It improves energy efficiency, eliminates energy waste and safety hazards, reduces deaerator operating costs, avoids thermal pollution, and ensures stable equipment operation.
Smart Images
Figure CN224680754U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the category of waste heat utilization systems, specifically relating to a waste heat utilization system for wastewater from a low-pressure waste heat boiler. Background Technology
[0002] The waste heat boiler continuously discharges wastewater, periodically discharges wastewater, and header wastewater through pipelines to a blowdown expansion tank. The wastewater temperature is 140℃. After the wastewater expands and cools in the blowdown expansion tank, the condensate is discharged into the sewer well. The secondary steam generated by "flash evaporation" is directly discharged into the atmosphere through the vent pipe at the top of the blowdown expansion tank. The escape of high-temperature condensate and secondary steam in the blowdown expansion tank area not only wastes energy but also poses a safety hazard due to low visibility in this area, and direct discharge causes thermal pollution. The thermal deaerator removes dissolved oxygen from the water by heating a mixture of steam and demineralized water, requiring the demineralized water to be heated from 20℃ to 104℃. Utility Model Content
[0003] This utility model provides a waste heat utilization system for low-pressure waste heat boiler wastewater, with the aim of utilizing the waste heat from boiler wastewater to improve energy utilization efficiency.
[0004] Therefore, the present invention adopts the following technical solution: A waste heat utilization system for wastewater from a low-pressure waste heat boiler includes a wastewater expander, a deaerator, a plate heat exchanger, and a waste heat boiler. It also includes the deaerator water supply pipeline, the deaerator water supply pipeline bypass pipeline, and the deaerator water supply pipeline bypass shut-off valve installed on the bypass pipeline; Wastewater discharge pipe and bypass pipe of waste heat boiler, with a wastewater bypass shut-off valve installed on the bypass pipe, and a plate heat exchanger, characterized in that... Install a plate heat exchanger heat source inlet shut-off valve on the plate heat exchanger heat source inlet pipe and a plate heat exchanger heat source outlet shut-off valve on the plate heat exchanger heat source outlet pipe; install a plate heat exchanger cold source inlet shut-off valve on the plate heat exchanger cold source inlet pipe and a plate heat exchanger cold source outlet shut-off valve on the plate heat exchanger cold source outlet pipe. A U-shaped condensate pipe leads out from the outlet condensate pipe of the blowdown expander, along with a shut-off valve for the main condensate line. The U-shaped condensate pipe and the shut-off valve for the main condensate line run parallel to each other. The plate heat exchanger is installed on the inlet wastewater pipe of the blowdown expander.
[0005] Furthermore, shut-off valves are installed on the heat source inlet and outlet pipes of the plate heat exchanger, and shut-off valves are installed on the intermediate pipes of the branch pipes leading out of the main sewage pipe.
[0006] Furthermore, shut-off valves are installed on the inlet and outlet pipes of the cold source of the plate heat exchanger, and shut-off valves are installed on the intermediate pipes of the branch pipes leading out of the deaerator feed water pipe.
[0007] Furthermore, a shut-off valve is installed on the intermediate pipe of the branch pipe from the condensate pipe.
[0008] The beneficial effects of this utility model are as follows: The wastewater waste heat utilization system and process of this utility model involves closing the shut-off valve on the intermediate pipe of the wastewater main branch pipe during boiler operation, opening the inlet and outlet shut-off valves of the heat source entering the plate heat exchanger, closing the shut-off valve on the intermediate pipe of the deaerator feedwater branch pipe, opening the inlet and outlet shut-off valves of the cold source entering the plate heat exchanger, and closing the shut-off valve on the intermediate pipe of the condensate branch pipe. During use, the wastewater first enters the plate heat exchanger for heat transfer and cooling before being discharged into the wastewater expansion tank. The deaerator feedwater first enters the plate heat exchanger for heat transfer and heating before entering the deaerator. The condensate, after being collected in the wastewater expansion tank, reaches a liquid level greater than or equal to the height of the "U"-shaped bend before being discharged into the sewer well. The wastewater temperature drops from 140℃ to about 10℃, and the deaerator feedwater temperature increases from 20℃ to 50℃. The increased feedwater temperature entering the deaerator reduces the amount of heating steam in the deaerator tower by 938 kg / h. In case of plate heat exchanger failure, close the inlet and outlet valves of the cold and heat sources of the plate heat exchanger, open the shut-off valve on the intermediate pipe of the branch pipe leading from the main wastewater pipe, and open the shut-off valve on the intermediate pipe of the branch pipe leading from the deaerator feedwater pipe. The wastewater is discharged into the wastewater expansion tank through the original pipeline, and the deaerator feedwater enters the deaerator through the original pipeline. If the deaerator feedwater flow is too low, resulting in escaping steam in the wastewater expansion tank area, to prevent the wastewater from entering the plate heat exchanger and causing insufficient cooling for a long time, which would accelerate the aging of the plate heat exchanger seals, the inlet and outlet valves of the heat source of the plate heat exchanger can be closed, and the wastewater is discharged into the wastewater expansion tank through the original pipeline. This system can be flexibly switched during operation without affecting equipment operation and production. It completely eliminates the escaping steam on site, thereby eliminating potential safety hazards, energy waste, and thermal pollution, and reducing the operating cost of the deaerator. Attached Figure Description
[0009] Figure 1 This is a flowchart illustrating the present invention. In the diagram: 1. Sewage expansion tank; 2. Deaerator; 3. Plate heat exchanger; 4. Deaerator feedwater bypass valve; 5. Plate heat exchanger cold source outlet valve; 6. Plate heat exchanger cold source inlet valve; 7. Plate heat exchanger heat source outlet valve; 8. Plate heat exchanger heat source inlet valve; 9. Sewage discharge bypass valve; 10. Condensate main pipeline valve; 11. Sewer well; 12. Deaerator feedwater pipeline; 13. Sewage discharge pipeline; 14. Sewage discharge expansion tank outlet valve. 15. Deaerator feedwater bypass pipeline; 16. Wastewater bypass pipeline; 17. Plate heat exchanger cold source inlet pipeline; 18. Plate heat exchanger heat source inlet pipeline; 19. Plate heat exchanger heat source outlet pipeline; 20. Plate heat exchanger heat source outlet pipeline; 21. Waste heat boiler; 22. Steam drum periodic blowdown pipeline; 23. Steam drum continuous blowdown pipeline; 24. Manifold blowdown collection pipeline; 25. Blowdown expansion tank venting pipeline; 26. Condensate pipeline. Detailed Implementation
[0010] The present invention will be further described below with reference to the accompanying drawings and specific embodiments: like Figure 1 As shown, a waste heat utilization system for wastewater from a low-pressure waste heat boiler includes a branch pipe, namely a plate heat exchanger cold source inlet pipe 17, which is led out from the deaerator feed water pipe 12 and connected to the plate heat exchanger cold source inlet. A plate heat exchanger cold source inlet shut-off valve is installed. During normal production operation, the deaerator feed water pipe bypass shut-off valve 4 is closed, and the plate heat exchanger cold source outlet shut-off valve 5 and the plate heat exchanger cold source inlet shut-off valve 6 are opened. The deaerator feed water enters the plate heat exchanger 3 through the plate heat exchanger cold source inlet pipe 19 and exchanges heat with the wastewater. The water then enters the thermal deaerator 2 through the plate heat exchanger heat source outlet pipe 19.
[0011] The periodic steam water from the waste heat boiler 21 flows along the periodic steam drum blowdown pipe 22, the continuous steam drum blowdown water flows along the continuous steam drum blowdown pipe 23, and the header blowdown water flows along the header blowdown collection pipe 24, all converging into the blowdown pipe 13. During normal operation, the bypass shut-off valve 9 of the blowdown pipe is closed, and the heat source inlet shut-off valve 8 and the heat source outlet shut-off valve 7 of the plate heat exchanger are opened. The blowdown water enters the plate heat exchanger 3 from the heat source inlet pipe 18 and undergoes heat exchange with the deaerator feedwater before being discharged from the heat source outlet pipe 20 into the blowdown expansion tank 1. During operation, the condensate main pipeline shut-off valve 10 is closed. The blowdown condensate entering the blowdown expansion tank 1 is discharged from the condensate pipeline 26 through the "U"-shaped condensate pipeline at the outlet of the blowdown expansion tank into the sewer well 11. In the event of a plate heat exchanger malfunction, the heat source inlet shut-off valve 8 and the heat source outlet shut-off valve 7 of the plate heat exchanger are closed. Stop valve 7, open sewage bypass shut-off valve 9, sewage enters sewage expansion tank 1 through sewage bypass pipe 16, condensate is discharged from condensate pipe 26 through the "U" shaped pipe of condensate pipe at the outlet of sewage expansion tank into sewer well 11, the generated secondary steam is discharged into the atmosphere through sewage expansion tank vent pipe 25, at the same time close plate heat exchanger cold source outlet shut-off valve 5 and plate heat exchanger cold source inlet shut-off valve 6, open deaerator feed water bypass shut-off valve 4, deaerator feed water enters thermal deaerator 2 through deaerator feed water bypass pipe 15, after the plate heat exchanger 3 fault is resolved, open plate heat exchanger cold source inlet shut-off valve 6, plate heat exchanger cold source outlet shut-off valve 5, plate heat exchanger heat source inlet shut-off valve 8, plate heat exchanger heat source outlet shut-off valve 7 in sequence, close deaerator feed water bypass shut-off valve 4 and sewage bypass shut-off valve 9. When the deaerator feedwater flow rate is too low, open the bypass shut-off valve 9 of the sewage discharge pipeline, and close the heat source inlet shut-off valve 8 and the heat source outlet shut-off valve 7 of the plate heat exchanger to ensure that the sealing strip of the plate heat exchanger 3 will age faster due to insufficient cooling capacity at low flow rates.
Claims
1. A waste heat utilization system for wastewater from a low-pressure waste heat boiler, comprising a wastewater expander (1), a deaerator (2), a plate heat exchanger (3), and a waste heat boiler (21). It also includes a deaerator water supply pipeline (12), a deaerator water supply pipeline bypass pipeline (15), and a deaerator water supply pipeline bypass shut-off valve (4) installed on the bypass pipeline. Waste heat boiler (21) sewage discharge pipe (13) and sewage discharge pipe bypass pipe (16), sewage discharge pipe bypass pipe (16) is equipped with sewage discharge pipe bypass shut-off valve (9), plate heat exchanger (3), characterized in that, Install a plate heat exchanger heat source inlet shut-off valve (8) on the plate heat exchanger heat source inlet pipe (18), and install a plate heat exchanger heat source outlet shut-off valve (7) on the plate heat exchanger heat source outlet pipe (20); install a plate heat exchanger cold source inlet shut-off valve (6) on the plate heat exchanger cold source inlet pipe (17), and install a plate heat exchanger cold source outlet shut-off valve (5) on the plate heat exchanger cold source outlet pipe (19). A U-shaped pipe (14) and a condensate main pipeline shut-off valve (10) are led out from the outlet condensate pipe (26) of the sewage expander (1), and the outlet condensate pipe (26) and the condensate main pipeline shut-off valve (10) are led out side by side.
2. The waste heat utilization system for wastewater from a low-pressure waste heat boiler according to claim 1, characterized in that, The plate heat exchanger (3) is installed on the sewage pipe at the inlet of the sewage expansion unit (1).