Secondary waste heat recovery system for circulating cooling water

Abstract

The utility model discloses a circulating cooling water two-stage waste heat recovery system which comprises a first-stage heat recovery heat exchanger, the first-stage heat recovery heat exchanger is connected with a second-stage heat recovery heat exchanger through a pipeline, and the second-stage heat recovery heat exchanger is connected with a circulating cooling water pump and a water cooling tower through pipelines. The secondary heat recovery heat exchanger is connected with a heat pump unit through a pipeline, the heat pump unit is connected with a heat pump circulating pump through a pipeline, the heat pump circulating pump is connected with a medium-temperature water tank through a pipeline, and the medium-temperature water tank is connected with medium-temperature equipment through a pipeline. The waste heat recycling system solves the problems of high waste heat recycling cost, low recycling rate, complex system and the like in the processes of cooling various products and discharging fluid containing low-temperature waste heat, is thorough in waste heat recycling, and fundamentally replaces the original circulating cooling water system. The problems of energy and water waste and environmental pollution caused by the fact that waste heat cannot be fully utilized in the waste heat utilization process are solved.

Description

Technical Field

[0001] The utility model relates to the field of waste heat recovery, and more specifically to a circulating cooling water secondary waste heat recovery system. Background Art

[0002] In actual production processes, there are many waste gases, waste water or gas and liquid materials with a temperature above 120°C that need to be cooled to room temperature or lower. The existing cooling system is basically a circulating water cooling system based on cooling towers to discharge heat into the atmosphere. The heat recovery of this type of system has no practical value because the temperature is too low, the heat recovery is small, the investment is large, and it causes thermal pollution to the environment and waste of water.

[0003] In many processes involving product cooling and fluid discharge containing medium and low temperature waste heat, most processes use an open circulating cooling water system to cool the materials and discharge the heat discharged by the materials into the atmosphere, which not only wastes energy but also increases the loss of circulating cooling water and causes thermal pollution. The reason is that the discharged waste heat is of low quality and difficult to recycle. Even if a waste heat recovery system is designed, it is rarely implemented due to its large investment, high operating cost and low economic value.

[0004] Therefore, it is necessary to propose a waste heat recovery system to solve the above problems. Utility Model Content

[0005] In view of the problems existing in the prior art, the purpose of the utility model is to provide a two-level waste heat recovery system for circulating cooling water to solve the problems of high cost, low recovery rate, complex system and so on of waste heat recovery and utilization in the cooling of various products and the discharge process of fluids containing low-temperature waste heat. It is a scientific graded recovery with thorough waste heat recovery, which can fundamentally replace the original circulating cooling water system and complete the recovery and utilization of all waste heat of process discharge materials at the same time, solving the problems of energy and water waste and environmental pollution caused by the inability to fully utilize the waste heat in the process of heat utilization.

[0006] To solve the above problems, the utility model adopts the following technical solutions.

[0007] A circulating cooling water secondary waste heat recovery system comprises a primary heat recovery heat exchanger, wherein the primary heat recovery heat exchanger is connected to a secondary heat recovery heat exchanger via a pipeline, the secondary heat recovery heat exchanger is connected to a circulating cooling water pump and a cooling tower via a pipeline, the secondary heat recovery heat exchanger is connected to a heat pump unit via a pipeline, the heat pump unit is connected to a heat pump circulating pump via a pipeline, the heat pump circulating pump is connected to a medium-temperature water tank via a pipeline, the medium-temperature water tank is connected to a medium-temperature device via a pipeline, and the medium-temperature device is connected to the heat pump unit via a pipeline.

[0008] Furthermore, the primary heat recovery heat exchanger is connected to a mixing heater and a hot water tank through a pipeline, the hot water tank is connected to a medium-temperature water tank through a pipeline, and the hot water tank is installed on one side of the primary heat recovery heat exchanger through a valve.

[0009] Furthermore, the hot water tank is connected to a high-temperature water circulation pump via a pipeline, the high-temperature water circulation pump is connected to a high-temperature water device via a pipeline, and the high-temperature water device is connected to a cold water tank via a pipeline.

[0010] Furthermore, the cold water tank is connected to a cold water circulation pump through a pipeline, and the cold water circulation pump is connected to a primary heat recovery heat exchanger and a heat pump unit through a pipeline.

[0011] Furthermore, the mixing heater is connected to a steam pipeline via a pipeline.

[0012] Furthermore, a water supply pipeline is installed on one side of the cold water tank.

[0013] Furthermore, one end of the secondary heat recovery heat exchanger is connected to a material discharge pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the overall structural pipeline connection of the utility model;

[0015] Figure 2 This is a schematic diagram of the pipeline connection of the heat pump unit of the utility model.

[0016] Description of the numbers in the figure:

[0017] 1. Primary heat recovery heat exchanger, 2. Secondary heat recovery heat exchanger, 3. Heat pump unit, 4. Heat pump circulating pump, 5. Cold water circulating pump, 6. Cold water tank, 7. High temperature water equipment, 8. High temperature water circulating pump, 9. Hot water tank, 10. Mixing heater, 11. Medium temperature water tank, 12. Medium temperature water equipment, 13. Circulating cooling water pump, 14. Cooling tower. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model; it is obvious that the described embodiments are only part of the embodiments of the utility model, rather than all of the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the utility model without making creative work are within the scope of protection of the utility model.

[0019] Example 1

[0020] See also Figure 1 and Figure 2A circulating cooling water secondary waste heat recovery system includes a primary heat recovery heat exchanger 1, the primary heat recovery heat exchanger 1 is connected to a secondary heat recovery heat exchanger 2 through a pipeline, the secondary heat recovery heat exchanger 2 is connected to a circulating cooling water pump 13 and a cooling tower 14 through a pipeline, the secondary heat recovery heat exchanger 2 is connected to a heat pump unit 3 through a pipeline, the heat pump unit 3 is connected to a heat pump circulating pump 4 through a pipeline, the heat pump circulating pump 4 is connected to a medium-temperature water tank 11 through a pipeline, the medium-temperature water tank 11 is connected to a medium-temperature device 12 through a pipeline, and the medium-temperature device 12 is connected to the heat pump unit 3 through a pipeline.

[0021] The primary heat recovery heat exchanger 1 is connected to a mixing heater 10 and a hot water tank 9 through a pipeline. The hot water tank 9 is connected to a medium-temperature water tank 11 through a pipeline. The two water tanks can supplement hot water with each other. The hot water tank 9 is installed on one side of the primary heat recovery heat exchanger 1 through a valve. The hot water tank 9 is connected to a high-temperature water circulation pump 8 through a pipeline. The high-temperature water circulation pump 8 is connected to a high-temperature water device 7 through a pipeline. The high-temperature water device 7 is connected to a cold water tank 6 through a pipeline. The cold water tank 6 is connected to a cold water circulation pump 5 through a pipeline. The cold water circulation pump 5 is connected to the primary heat recovery heat exchanger 1 and the heat pump unit 3 through a pipeline. The mixing heater 10 is connected to a steam pipeline through a pipeline. A water supply pipeline is installed on one side of the cold water tank 6. One end of the secondary heat recovery heat exchanger 2 is connected to a material discharge pipeline.

[0022] First, a primary heat recovery heat exchanger 1 is installed on the original waste heat discharge system to recover the waste heat in the materials or exhaust gas above 120°C, and reduce the temperature of the gas phase materials to an economic and allowable temperature below 60°C. The recovered heat is used to heat water from a low temperature of 20°C to above 80°C, of ​​which the hot water at 80°C can be directly used in the process system;

[0023] On the basis of the primary heat recovery heat exchanger 1, the heat exchanger of the original circulating water cooling system is used or a new heat exchanger is installed and replaced, and the temperature of the gas phase material is further reduced from 60°C to the temperature required by the process by a closed circulating cooling water system. The designed outlet water temperature of the closed circulating cooling water reaches above 35°C, and then the heat absorbed by the closed circulating cooling water is recovered and utilized by a specially designed heat pump unit 3 to make hot water above 60°C to enter the process. Generally, the designed inlet and outlet water temperatures of the closed circulating cooling water are 25°C and 45°C;

[0024] In order to ensure the coordination of the entire system, the heat pump unit 3 is specially designed. The evaporator and condenser of the heat pump unit 3 are designed as 30°C large temperature difference heat exchangers, and the inlet and outlet water temperatures of the evaporator and condenser can be independently controlled to ensure that the outlet water temperatures on the heat source side and the heating side always meet the process requirements;

[0025] In addition, the heat pump unit 3 is designed as one in use and one in standby to ensure the operational reliability of the waste heat recovery system. The original open circulating cooling water system is retained, and the two circulating cooling water systems can be switched in a planned manner according to the needs of the heat load. The system designed in the scheme will not have the event of emergency switching of the circulating cooling water system due to an accident of the heat pump unit. The system is designed to be equipped with a cold water tank 6, a hot water tank 9 and a medium-temperature water tank 11, which improves the operational reliability of the waste heat recovery system.

[0026] The above is only a preferred specific implementation of the utility model; however, the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and improved ideas of the utility model within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model.

Claims

1. A circulating cooling water secondary waste heat recovery system, comprising a primary heat recovery heat exchanger (1), characterized in that: The primary heat recovery heat exchanger (1) is connected to the secondary heat recovery heat exchanger (2) via a pipeline, the secondary heat recovery heat exchanger (2) is connected to a circulating cooling water pump (13) and a cooling tower (14) via a pipeline, the secondary heat recovery heat exchanger (2) is connected to a heat pump unit (3) via a pipeline, the heat pump unit (3) is connected to a heat pump circulating pump (4) via a pipeline, the heat pump circulating pump (4) is connected to a medium-temperature water tank (11) via a pipeline, the medium-temperature water tank (11) is connected to a medium-temperature device (12) via a pipeline, and the medium-temperature device (12) is connected to the heat pump unit (3) via a pipeline.

2. A circulating cooling water secondary waste heat recovery system according to claim 1, characterized in that: The primary heat recovery heat exchanger (1) is connected to a mixing heater (10) and a hot water tank (9) via a pipeline, the hot water tank (9) is connected to a medium-temperature water tank (11) via a pipeline, and the hot water tank (9) is installed on one side of the primary heat recovery heat exchanger (1) via a valve.

3. A circulating cooling water secondary waste heat recovery system according to claim 2, characterized in that: The hot water tank (9) is connected to a high-temperature water circulation pump (8) via a pipeline, the high-temperature water circulation pump (8) is connected to a high-temperature water device (7) via a pipeline, and the high-temperature water device (7) is connected to a cold water tank (6) via a pipeline.

4. A circulating cooling water secondary waste heat recovery system according to claim 3, characterized in that: The cold water tank (6) is connected to a cold water circulation pump (5) via a pipeline, and the cold water circulation pump (5) is connected to a primary heat recovery heat exchanger (1) and a heat pump unit (3) via a pipeline.

5. A circulating cooling water secondary waste heat recovery system according to claim 2, characterized in that: The mixing heater (10) is connected to a steam pipeline via a pipeline.

6. A circulating cooling water secondary waste heat recovery system according to claim 3, characterized in that: A water supply pipeline is installed on one side of the cold water tank (6).

7. The circulating cooling water secondary waste heat recovery system according to claim 1, characterized in that: One end of the secondary heat recovery heat exchanger (2) is connected to a material discharge pipeline.

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