Refrigerating system and method for recovering waste heat of coking high-temperature condensed water and coupling steam to adjust temperature

Abstract

The invention relates to a refrigerating system and method for recovering coking high-temperature condensed water waste heat coupling steam temperature adjustment. The refrigerating system comprises a crude benzene distillation unit, an ammonium sulfate unit, an ammonia distillation unit, a three-section type gas primary cooler, a condensed water heat exchanger, a steam heat exchanger, a waste heat water type refrigerating machine and a condensed water recovery water tank. The problem that a refrigerating station needs to be provided with a waste heat water type refrigerating machine and a steam type refrigerating unit due to the fact that waste heat of waste heat water of the primary cooler is insufficient can be solved while waste heat of high-temperature condensed water of a coking plant is recycled, the temperature of the waste heat water is increased through the steam heat exchanger, and then the heat exchange efficiency of the refrigerating machine is improved; the total investment is reduced, and the operation cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of coking refrigeration, and in particular to a refrigeration system and method for recovering waste heat of coking high-temperature condensed water coupled with steam temperature regulation. Background Art

[0002] To achieve better temperature reduction, some equipment in the gas purification unit of a coking plant (such as the lower end of the gas primary cooler, pre-cooling tower, and desulfurization liquid cooler) uses low-temperature water (around 16°C) as a refrigerant, which is lower than conventional circulating water. This low-temperature water is typically produced using a lithium bromide absorption chiller. Lithium bromide absorption chillers are powered by a heat source, primarily using water as the refrigerant and lithium bromide solution as the absorbent to produce low-temperature water. Depending on the type of driving heat source, they are categorized as direct-fired, steam-fired, and hot water-fired.

[0003] At present, coking plants mostly use three-stage gas primary coolers to recover the waste heat of high-temperature raw gas (around 82°C) to produce waste hot water (supply water temperature 73°C, return water temperature 63°C), and use the waste hot water as the driving heat source to supply the refrigerator. However, the waste heat of high-temperature raw gas is limited and insufficient to meet the driving heat source needs of all refrigerators in the coking plant. Therefore, coking plants mostly prefer waste hot water type refrigerators, and then configure steam type refrigerators for the insufficient part. As a result, the refrigeration station needs to be equipped with two different models, which increases the complexity of operation and causes production inconvenience. In addition, because the initial temperature of high-temperature raw gas is only around 82°C, and the waste hot water temperature system of the primary cooler requires a supply water temperature of around 73°C and a return water temperature of around 63°C, the low waste hot water temperature is not conducive to heat exchange of the waste hot water type refrigerator, and the required heat exchanger area is large. Summary of the Invention

[0004] The present invention provides a refrigeration system and method for recovering waste heat from high-temperature condensate water in a coking plant coupled with steam temperature control. The system can recover the waste heat from the high-temperature condensate water in the coking plant while solving the problem that the refrigeration station needs to be equipped with two types of machines, namely, a waste hot water type refrigerator and a steam type refrigerator, due to insufficient waste heat of the waste hot water in the primary cooler. The waste hot water temperature is increased by the steam heat exchanger, thereby improving the heat exchange efficiency of the refrigerator, reducing the overall investment, and saving operating costs.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A refrigeration system for recovering waste heat of coking high-temperature condensate coupled with steam temperature control, comprising a crude benzene distillation unit, an ammonium sulphate unit, an ammonia distillation unit, a three-stage coal gas primary cooler, a condensate heat exchanger, a steam heat exchanger, a waste hot water type refrigerator and a condensate recovery water tank; the crude benzene distillation unit, the ammonium sulphate unit and the ammonia distillation unit are respectively connected to the high-temperature condensate inlet of the condensate heat exchanger through a high-temperature condensate recovery pipeline; the waste hot water inlet of the three-stage coal gas primary cooler is connected to the waste hot water outlet of the waste hot water type refrigerator through a waste hot water pipeline 1, the waste hot water outlet of the three-stage coal gas primary cooler is connected to the waste hot water inlet of the condensate heat exchanger through a waste hot water pipeline 2, the waste hot water outlet of the condensate heat exchanger is connected to the waste hot water inlet of the steam heat exchanger through a waste hot water pipeline 3; the steam inlet of the steam heat exchanger is connected to a low-pressure steam pipeline; the waste hot water outlet of the steam heat exchanger is connected to the waste hot water inlet of the waste hot water type refrigerator through a waste hot water pipeline 4; the condensate outlet of the condensate heat exchanger and the condensate outlet of the steam heat exchanger are connected to the condensate recovery water tank through a low-temperature condensate pipeline.

[0007] The low-pressure steam pipeline is provided with a steam regulating valve group; the waste hot water pipeline is provided with a thermometer; the steam regulating valve group and the thermometer are interlocked and controlled by a control system.

[0008] A waste hot water pressure pump is provided on the waste hot water pipeline.

[0009] The condensate recovery tank is connected to a condensate delivery pipeline, and a condensate pump is provided on the condensate delivery pipeline.

[0010] A refrigeration method for recovering waste heat from coking high-temperature condensate coupled with steam temperature control, comprising the following steps:

[0011] 1) Through the high-temperature condensate recovery pipeline, high-temperature condensate above 160°C from the crude benzene distillation unit, ammonium sulfate unit, and ammonia distillation unit in the coking plant is uniformly recovered and sent to the condensate heat exchanger to recover waste heat. After the waste heat is recovered, the low-temperature condensate with a temperature of 80-85°C is sent to the condensate recovery tank;

[0012] 2) High-temperature raw gas from the coke oven, exceeding 82°C, is cooled to below 21°C in a three-stage primary gas cooler and then sent to downstream processing for purification. In the three-stage primary gas cooler, the high-temperature raw gas exchanges heat with 60-63°C waste water from a waste water chiller, raising the waste water temperature to 70-73°C. The 70-73°C waste water then enters the condensate heat exchanger, where it exchanges heat with high-temperature condensate exceeding 160°C, raising its temperature to 74-75°C before entering the steam heat exchanger.

[0013] 3) The low-pressure steam with a pressure of 0.5-0.6 MPa delivered by the low-pressure steam pipeline enters the steam heat exchanger after passing through the steam regulating valve group and exchanges heat with the waste hot water at 74-75°C. The waste hot water at 74-75°C is heated to above 78°C by heat exchange and then sent to the waste hot water type refrigerator;

[0014] 4) Waste water above 78°C enters the waste water type refrigeration machine, where the temperature is reduced to below 63°C after work. It is then pressurized by the waste water booster pump and sent to the three-stage gas primary cooler to cool the high-temperature raw gas.

[0015] The above process is repeated;

[0016] 5) In the waste water type chiller, the low-temperature water of 20-23°C is cooled to below 16°C and sent to the low-temperature water users of the coking plant;

[0017] 6) The low-temperature condensate in the condensate recovery tank is pressurized by the condensate pump and then sent to the condensate users of the coking plant through the external condensate pipeline.

[0018] In the process 3), the opening degree of the steam regulating valve group is adjusted according to the temperature of the waste hot water at the waste hot water inlet of the waste hot water type refrigerator.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The condensate heat exchanger is used to recover the waste heat of high-temperature condensate, thereby recovering the waste heat of high-temperature condensate, increasing the water temperature of the waste water, and improving the heat exchange efficiency of the refrigerator;

[0021] 2) The heat of the waste water is regulated by the steam heat exchanger and steam regulating valve group, solving the problem of insufficient waste water heat in the primary cooler, which requires the refrigeration station to have both waste water type refrigeration units and steam type refrigeration units, thereby reducing overall investment and saving operating costs;

[0022] 3) Through the interlocking control of the steam regulating valve group and the four thermometers on the waste hot water pipeline, the inlet and outlet water temperatures of the waste hot water type chiller can be accurately controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the refrigeration system for recovering waste heat of coking high-temperature condensate coupled with steam temperature control according to the present invention.

[0024] Figure: 1. Crude benzene distillation unit 2. Ammonium sulfate unit 3. Ammonia distillation unit 4. High-temperature condensate recovery pipeline 5. Three-stage gas primary cooler 6. Waste water pipe 1 7. Waste water pipe 2 8. Condensate heat exchanger 9. Waste water pipe 3 10. Low-pressure steam pipe 11. Steam regulating valve group 12. Steam heat exchanger 13. Waste water pipe 4 14. Thermometer 15. Waste water chiller 16. Waste water booster pump 17. Low-temperature condensate pipe 18. Condensate recovery tank 19. Condensate pump 20. Condensate delivery pipeline DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0026] like Figure 1 As shown, the refrigeration system for recovering waste heat of high-temperature condensate from coking coupled with steam temperature control according to the present invention comprises a crude benzene distillation unit 1, an ammonium sulfate unit 2, an ammonia distillation unit 3, a three-stage coal gas primary cooler 5, a condensate heat exchanger 8, a steam heat exchanger 12, a waste hot water type refrigerator 15 and a condensate recovery water tank 18; the crude benzene distillation unit 1, the ammonium sulfate unit 2 and the ammonia distillation unit 3 are respectively connected to the high-temperature condensate inlet of the condensate heat exchanger 8 through a high-temperature condensate recovery pipe 4; the waste hot water inlet of the three-stage coal gas primary cooler 5 is connected to the waste hot water outlet of the waste hot water type refrigerator 15 through a waste hot water pipe 6 The waste hot water outlet of the three-stage gas primary cooler 5 is connected to the waste hot water inlet of the condensate heat exchanger 8 through the waste hot water pipe 2 7, and the waste hot water outlet of the condensate heat exchanger 8 is connected to the waste hot water inlet of the steam heat exchanger 12 through the waste hot water pipe 3 9; the steam inlet of the steam heat exchanger 12 is connected to the low-pressure steam pipe 10; the waste hot water outlet of the steam heat exchanger 12 is connected to the waste hot water inlet of the waste hot water type refrigerator 15 through the waste hot water pipe 4 13; the condensate outlet of the condensate heat exchanger 8 and the condensate outlet of the steam heat exchanger 12 are connected to the condensate recovery tank 18 through the low-temperature condensate pipe 17.

[0027] The low-pressure steam pipe 10 is provided with a steam regulating valve group 11; the waste hot water pipe 13 is provided with a thermometer 14; the steam regulating valve group 11 and the thermometer 14 are interlocked and controlled by a control system.

[0028] The waste hot water pipe 16 is provided with a waste hot water pressure pump 16.

[0029] The condensate recovery tank 18 is connected to a condensate delivery pipeline 20 , and a condensate pump 19 is provided on the condensate delivery pipeline 20 .

[0030] The present invention provides a refrigeration method for recovering waste heat from coking high-temperature condensate coupled with steam temperature control, comprising the following steps:

[0031] 1) High-temperature condensate above 160°C from the crude benzene distillation unit 1, ammonium sulfate unit 2, and ammonia distillation unit 3 in the coking plant is recovered through a high-temperature condensate recovery pipeline 4 and fed to a condensate heat exchanger 8 to recover waste heat. After waste heat recovery, the low-temperature condensate at a temperature of 80-85°C is fed to a condensate recovery tank 18;

[0032] 2) High-temperature raw gas from the coke oven, exceeding 82°C, is cooled to below 21°C in the three-stage primary gas cooler 5 and then sent to the downstream process for purification. In the three-stage primary gas cooler 5, the high-temperature raw gas exchanges heat with 60-63°C waste water from the waste water type chiller 15, raising the waste water temperature to 70-73°C. The 70-73°C waste water enters the condensate heat exchanger 8, where it exchanges heat with high-temperature condensate exceeding 160°C, raising its temperature to 74-75°C before entering the steam heat exchanger 12.

[0033] 3) Low-pressure steam at a pressure of 0.5-0.6 MPa, delivered by the low-pressure steam pipe 10, passes through the steam regulating valve group 11 and enters the steam heat exchanger 12 for heat exchange with the waste hot water at 74-75°C. The waste hot water at 74-75°C is heated to above 78°C by heat exchange and then sent to the waste hot water type refrigerator 15;

[0034] 4) Waste water above 78°C enters the waste water type refrigeration machine 15, where the temperature is reduced to below 63°C after work. It is then pressurized by the waste water booster pump 16 and sent to the three-stage gas primary cooler 5 to cool the high-temperature raw gas.

[0035] The above process is repeated;

[0036] 5) In the waste water type chiller 15, the low-temperature water of 20-23°C is cooled to below 16°C and sent to the low-temperature water users of the coking plant;

[0037] 6) The low-temperature condensate in the condensate recovery tank 18 is pressurized by the condensate pump 19 and then sent to the condensate users of the coking plant through the external condensate pipeline 20.

[0038] In the process 3), the opening degree of the steam regulating valve group 11 is adjusted according to the temperature of the waste hot water at the waste hot water inlet of the waste hot water type refrigerator 15.

[0039] In order to more intuitively embody the present invention, the embodiments of the present invention are further described in conjunction with examples. The following examples are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the present invention, including simple changes or equivalent replacements, is within the scope of protection of the present invention.

[0040] [Example]

[0041] like Figure 1As shown, in this embodiment, the refrigeration system for recovering the waste heat of the coking high-temperature condensate coupled with steam temperature control includes the crude benzene distillation unit 1, the ammonium sulfate unit 2 and the ammonia evaporation unit 3 of the coking plant, the high-temperature condensate recovery pipeline 4, the three-stage coal gas primary cooler 5, the waste hot water pipeline 1 6, the waste hot water pipeline 2 7, the condensate heat exchanger 8, the waste hot water pipeline 3 9, the low-pressure steam pipeline 10, the steam regulating valve group 11, the steam heat exchanger 12, the waste hot water pipeline 4 13, the thermometer 14, the waste hot water type refrigerator 15, the waste hot water booster pump 16, the low-temperature condensate pipeline 17, the condensate recovery water tank 18, the condensate pump 19, the external condensate pipeline 20, etc.

[0042] In this embodiment, the refrigeration process of recovering the waste heat of the coking high-temperature condensate coupled with steam temperature control is as follows:

[0043] High-temperature condensate (160°C or higher) from the crude benzene distillation unit 1, ammonium sulfate unit 2, and ammonia distillation unit 3 in the coking plant is recovered through high-temperature condensate recovery pipeline 4 and then fed to condensate heat exchanger 8 for waste heat recovery. After waste heat is recovered in condensate heat exchanger 8, the temperature of the high-temperature condensate (160°C or higher) is lowered to 85°C and then fed to condensate recovery tank 18 through low-temperature condensate pipeline 17.

[0044] The 82°C high-temperature raw gas from the coke oven passes through the three-stage gas primary cooler 5, is cooled to 21°C, and is sent to the downstream section for purification.

[0045] The 63°C waste hot water from the waste hot water type refrigerator 15 enters the three-stage gas primary cooler 5 through the waste hot water pipe 1 6, recovers the heat of the high-temperature raw gas, and then is heated to 73°C. It then enters the condensate heat exchanger 8 through the waste hot water pipe 2 7, exchanges heat with the high-temperature condensate above 160°C, and is heated to 74°C. It then enters the steam heat exchanger 12 through the waste hot water pipe 3 9.

[0046] The low-pressure steam with a pressure of 0.6 MPa delivered by the low-pressure steam pipe 10 enters the steam heat exchanger 12 after being regulated by the steam regulating valve group 11 (the steam regulating valve group is interlocked with the thermometer 14 set on the waste hot water pipe four) to exchange heat with the 74°C waste hot water. After the 74°C waste hot water is heated to 78°C, it enters the waste hot water type refrigerator 15 through the waste hot water pipe four 13. After doing work, the temperature is reduced to 63°C. It is then pressurized by the waste hot water booster pump 16 and sent to the three-stage gas primary cooler 5 through the waste hot water pipe one 6 for cooling the high-temperature raw gas.

[0047] The above process is repeated.

[0048] In the waste water type refrigeration machine 15, the low temperature water of 23°C is cooled to 16°C after being refrigerated, and the low temperature water of 16°C is sent to the low temperature water users of the coking plant.

[0049] The low-temperature condensate of 85°C in the condensate recovery tank 18 is pressurized by the condensate pump 19 and then sent to the condensate users of the coking plant (such as the riser vaporization station, flue gas waste heat boiler, etc.) through the external condensate pipeline 20.

[0050] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A refrigeration system for recovering waste heat from coking high-temperature condensed water coupled with steam temperature control, characterized in that: It includes a crude benzene distillation unit, an ammonium sulphate unit, an ammonia distillation unit, a three-stage gas primary cooler, a condensate heat exchanger, a steam heat exchanger, a waste hot water type refrigerator and a condensate recovery tank; the crude benzene distillation unit, the ammonium sulphate unit and the ammonia distillation unit are respectively connected to the high-temperature condensate inlet of the condensate heat exchanger through a high-temperature condensate recovery pipeline; the waste hot water inlet of the three-stage gas primary cooler is connected to the waste hot water outlet of the waste hot water type refrigerator through a waste hot water pipeline one, the waste hot water outlet of the three-stage gas primary cooler is connected to the waste hot water inlet of the condensate heat exchanger through a waste hot water pipeline two, the waste hot water outlet of the condensate heat exchanger is connected to the waste hot water inlet of the steam heat exchanger through a waste hot water pipeline three; the steam inlet of the steam heat exchanger is connected to a low-pressure steam pipeline; the waste hot water outlet of the steam heat exchanger is connected to the waste hot water inlet of the waste hot water type refrigerator through a waste hot water pipeline four; the condensate outlet of the condensate heat exchanger and the condensate outlet of the steam heat exchanger are connected to the condensate recovery tank through a low-temperature condensate pipeline.

2. A refrigeration system for recovering waste heat from coking high-temperature condensate coupled with steam temperature control according to claim 1, characterized in that: The low-pressure steam pipeline is provided with a steam regulating valve group; the waste hot water pipeline is provided with a thermometer; the steam regulating valve group and the thermometer are interlocked and controlled by a control system.

3. The refrigeration system for recovering waste heat from coking high-temperature condensate coupled with steam temperature control according to claim 1, characterized in that: A waste hot water pressure pump is provided on the waste hot water pipeline.

4. The refrigeration system for recovering waste heat from coking high-temperature condensate coupled with steam temperature control according to claim 1, characterized in that: The condensate recovery tank is connected to a condensate delivery pipeline, and a condensate pump is provided on the condensate delivery pipeline.

5. A refrigeration method for recovering waste heat from coking high-temperature condensate coupled with steam temperature control, which is implemented based on the refrigeration system for recovering waste heat from coking high-temperature condensate coupled with steam temperature control as described in any one of claims 1 to 4; characterized in that: The process includes the following: 1) Through the high-temperature condensate recovery pipeline, high-temperature condensate above 160°C from the crude benzene distillation unit, ammonium sulfate unit, and ammonia distillation unit in the coking plant is uniformly recovered and sent to the condensate heat exchanger to recover waste heat. After the waste heat is recovered, the low-temperature condensate with a temperature of 80-85°C is sent to the condensate recovery tank; 2) High-temperature raw gas from the coke oven, exceeding 82°C, is cooled to below 21°C in a three-stage primary gas cooler and then sent to downstream processing for purification. In the three-stage primary gas cooler, the high-temperature raw gas exchanges heat with 60-63°C waste water from a waste water chiller, raising the waste water temperature to 70-73°C. The 70-73°C waste water then enters the condensate heat exchanger, where it exchanges heat with high-temperature condensate exceeding 160°C, raising its temperature to 74-75°C before entering the steam heat exchanger. 3) The low-pressure steam with a pressure of 0.5-0.6 MPa delivered by the low-pressure steam pipeline enters the steam heat exchanger after passing through the steam regulating valve group and exchanges heat with the waste hot water at 74-75°C. The waste hot water at 74-75°C is heated to above 78°C by heat exchange and then sent to the waste hot water type refrigerator; 4) Waste water above 78°C enters the waste water type refrigeration machine, where the temperature is reduced to below 63°C after work. It is then pressurized by the waste water booster pump and sent to the three-stage gas primary cooler to cool the high-temperature raw gas. The above process is repeated; 5) In the waste water type chiller, the low-temperature water of 20-23°C is cooled to below 16°C and sent to the low-temperature water users of the coking plant; 6) The low-temperature condensate in the condensate recovery tank is pressurized by the condensate pump and then sent to the condensate users of the coking plant through the external condensate pipeline.

6. A refrigeration method for recovering waste heat from high-temperature coking condensate coupled with steam temperature control as described in claim 5, wherein in process 3), the opening of the steam regulating valve group is adjusted according to the waste hot water temperature at the waste hot water inlet of the waste hot water type refrigerator.

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