Power plant waste heat utilization system

Abstract

The utility model relates to the technical field of thermal power generation, in particular to a power plant waste heat utilization system which comprises an absorption refrigerator, an economizer and a controller, a hot water inlet of the absorption refrigerator is connected with a mixed flow pipe, and a temperature sensor is arranged in the mixed flow pipe. A low-temperature water outlet of the absorption refrigerator is provided with a backflow pipe, a first flow control valve is arranged in the backflow pipe, and the end, away from the absorption refrigerator, of the backflow pipe communicates with the end, away from the absorption refrigerator, of the flow mixing pipe. A water outlet of the economizer communicates with the end, away from the absorption refrigerator, of the mixed flow pipe. High-temperature water flowing out of the coal economizer and low-temperature water flowing out of the backflow pipe are mixed into mixed water in the flow mixing pipe, the mixed water flows into the absorption refrigerator, the first flow control valve can adjust the flow of the low-temperature water flowing into the flow mixing pipe, the water temperature of the mixed water is adjusted, and it is guaranteed that heat input of the absorption refrigerator is stable.

Description

Technical Field

[0001] The utility model relates to the technical field of thermal power generation, in particular to a waste heat utilization system of a power plant. Background Art

[0002] In a gas-steam combined cycle power plant, the heat of the high-temperature exhaust gas of the combustion engine is absorbed by the waste heat boiler and water vapor is generated. The water vapor enters the steam turbine to expand and do work to drive the generator to generate electricity. Heat absorption is achieved through multiple types of heat exchange tubes set in the waste heat boiler. The heat exchange tubes at the tail of the boiler are called economizers. After passing through the economizer, the exhaust gas is discharged to the atmosphere through the chimney. Generally, the exhaust temperature of the waste heat boiler is about 80℃ to 90℃. Considering the low-temperature corrosion of the tail, the exhaust temperature should not be lower than 60℃. Considering that the surplus can be controlled at 70℃, there is still a lot of heat in the flue gas that can be used, which can be used for refrigeration in the absorption chiller to produce chilled water for users, realizing the utilization of waste heat from power generation.

[0003] In the existing waste heat utilization system of power plants, the hot water flowing out of the economizer directly flows to the hot water inlet of the absorption chiller, resulting in unstable heat input of the absorption chiller and difficulty in accurately adjusting the cooling power of the absorption chiller. Utility Model Content

[0004] The technical problem to be solved by the utility model is that in the existing power plant waste heat utilization system, the heat input of the absorption refrigerator is unstable, resulting in unstable heat input of the absorption refrigerator.

[0005] In order to solve the above technical problems, the purpose of the utility model is to provide a power plant waste heat utilization system, comprising:

[0006] An absorption refrigerator, wherein a hot water inlet of the absorption refrigerator is connected to a mixing pipe, wherein a temperature sensor is disposed in the mixing pipe; a low-temperature water outlet of the absorption refrigerator is provided with a return pipe, wherein one end of the return pipe away from the absorption refrigerator is connected to one end of the mixing pipe away from the absorption refrigerator, wherein a first flow control valve is disposed in the return pipe;

[0007] An economizer, the economizer is used to recover the waste heat of the flue gas of the waste heat boiler, the water inlet of the economizer is connected to the low-temperature water outlet of the absorption refrigerator, and the water outlet of the economizer is connected to the end of the mixing pipe away from the absorption refrigerator;

[0008] The controller, the temperature sensor and the first flow control valve are both electrically connected to the controller.

[0009] As a preferred solution, the power plant waste heat utilization system includes a second flow control valve disposed on the mixing pipe, the second flow control valve is arranged between the temperature sensor and the absorption refrigerator, and the second flow control valve is electrically connected to the controller.

[0010] As a preferred solution, the power plant waste heat utilization system includes a shunt pipe, a first end of the shunt pipe is connected to the water outlet of the second flow control valve, and a second end of the shunt pipe is connected to the water inlet of the economizer.

[0011] As a preferred embodiment, the power plant waste heat utilization system includes a first pump body, the low-temperature water outlet of the absorption chiller and the second end of the diversion pipe are connected to the water inlet of the first pump body, and the water outlet of the first pump body is connected to the water inlet of the economizer and the end of the return pipe close to the absorption chiller.

[0012] As a preferred embodiment, the power plant waste heat utilization system includes a three-way regulating valve, one end of the mixing pipe close to the absorption chiller is connected to the first port of the three-way regulating valve, the hot water inlet of the absorption chiller is connected to the second port of the three-way regulating valve, and the first end of the diversion pipe is connected to the third port of the three-way regulating valve.

[0013] As a preferred solution, the power plant waste heat utilization system includes a second heat exchanger for heating natural gas, the water inlet of the second heat exchanger is connected to the water outlet of the economizer, and the water outlet of the second heat exchanger is connected to the water inlet of the economizer.

[0014] As a preferred solution, the power plant waste heat utilization system includes a second pump body, a water inlet of the second pump body is connected to a water outlet of the second heat exchanger, and a water outlet of the second pump body is connected to a water inlet of the economizer.

[0015] As a preferred solution, the power plant waste heat utilization system includes a third heat exchanger for absorbing the cold energy of the depressurized natural gas, the air inlet of the third heat exchanger is used to connect to the air outlet of the natural gas depressurization device, and the air outlet of the third heat exchanger is connected to the air inlet of the second heat exchanger;

[0016] The water inlet of the third heat exchanger is connected to a water supply pipe, and the water outlet of the third heat exchanger is used to connect to a cooling pipeline.

[0017] As a preferred solution, the cold water inlet of the absorption chiller is communicated with the water supply pipe, and the cold water outlet of the absorption chiller is communicated with the cooling pipe.

[0018] As a preferred embodiment, the power plant waste heat utilization system includes a third pump body, one end of the water supply pipe is connected to the water supply system, the other end of the water supply pipe is connected to the water inlet of the third pump body, and the water outlet of the third pump body is connected to the water inlet of the third heat exchanger.

[0019] Compared with the prior art, the beneficial effects of the utility model are:

[0020] The utility model of the waste heat utilization system of a power plant comprises an absorption refrigerator, an economizer and a controller. The hot water inlet of the absorption refrigerator is connected with a mixing pipe, in which a temperature sensor is arranged; the low-temperature water outlet of the absorption refrigerator is provided with a return pipe, in which a first flow control valve is arranged; an end of the return pipe away from the absorption refrigerator is connected with an end of the mixing pipe away from the absorption refrigerator; the economizer is used to recover the waste heat of the flue gas of the waste heat boiler; the water inlet of the economizer is connected with the low-temperature water outlet of the absorption refrigerator, and the water outlet of the economizer is connected with the end of the mixing pipe away from the absorption refrigerator; the temperature sensor and the first flow control valve are both electrically connected with the controller; the utility model In the utility model of the waste heat utilization system of a power plant, high-temperature water formed by heating the waste heat of flue gas in the economizer flows into the absorption refrigerator through a mixing pipe. The high-temperature water flowing into the absorption refrigerator is formed into low-temperature water after the absorption refrigerator absorbs heat. The low-temperature water can flow back to the mixing pipe through the return pipe and mix with the high-temperature water flowing into the mixing pipe to form mixed water. The water temperature of the mixed water can be obtained through a temperature sensor, and the flow rate of the low-temperature water flowing into the mixing pipe can be adjusted by a first flow control valve arranged in the return pipe, thereby realizing the adjustment of the water temperature of the mixed water. Thereby, the heat input of the absorption refrigerator is guaranteed to be stable, and the cooling power of the absorption refrigerator can be accurately adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the waste heat utilization system of a power plant of the utility model;

[0022] In the figure, 1, absorption refrigerator, 2, mixing flow pipe, 21, temperature sensor, 22, second flow control valve, 3, reflux pipe, 31, first flow control valve, 4, economizer, 5, diverter pipe, 61, first pump body, 62, three-way regulating valve, 71, second heat exchanger, 72, second pump body, 73, third heat exchanger, 8, water supply pipe, 81, third pump body, 9, cooling pipe. DETAILED DESCRIPTION

[0023] The following is a further detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0024] In the description of the present utility model, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. It should be understood that the terms "first", "second", etc. are used in the present utility model to describe various information, but such information should not be limited to these terms, which are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present utility model, the "first" information may also be referred to as the "second" information, and similarly, the "second" information may also be referred to as the "first" information.

[0025] like Figure 1 As shown, the preferred embodiment of the power plant waste heat utilization system of the utility model includes:

[0026] An absorption refrigerator 1, wherein a hot water inlet of the absorption refrigerator 1 is connected to a mixing pipe 2, in which a temperature sensor 21 is provided; a low-temperature water outlet of the absorption refrigerator 1 is provided with a return pipe 3, an end of the return pipe 3 away from the absorption refrigerator 1 is connected to an end of the mixing pipe 2 away from the absorption refrigerator 1, and a first flow control valve 31 is provided in the return pipe 3;

[0027] Economizer 4, economizer 4 is used to recover the waste heat of the flue gas of the waste heat boiler, the water inlet of economizer 4 is connected to the low-temperature water outlet of the absorption refrigerator 1, and the water outlet of economizer 4 is connected to the end of the mixing pipe 2 away from the absorption refrigerator 1;

[0028] The controller, the temperature sensor 21 and the first flow control valve 31 are all electrically connected to the controller.

[0029] Specifically, the high-temperature water formed by the waste heat of flue gas heated by the economizer 4 flows into the absorption refrigeration machine 1 through the mixing pipe 2. The high-temperature water flowing into the absorption refrigeration machine 1 is absorbed by the absorption refrigeration machine 1 to form low-temperature water. The low-temperature water can flow back to the mixing pipe 2 through the return pipe 3 and mix with the high-temperature water flowing into the mixing pipe 2 to form mixed water. The water temperature of the mixed water can be known by the temperature sensor 21. The flow rate of the low-temperature water flowing into the mixing pipe 2 can be adjusted by the first flow control valve 31 set in the return pipe 3, thereby realizing the adjustment of the water temperature of the mixed water. In this way, the heat input of the absorption refrigeration machine 1 is stable, and the refrigeration power of the absorption refrigeration machine 1 can be accurately adjusted. Among them, the absorption refrigeration machine 1 in the utility model is a lithium bromide refrigeration unit. In the process of converting the high-temperature water in the absorption refrigeration machine 1 into low-temperature water, the normal-temperature water in the absorption refrigeration machine 1 is cooled into cold water, and the cold water is input into the cooling pipe 9 to realize the cooling function of the refrigeration station.

[0030] In this embodiment, the power plant waste heat utilization system includes a second flow control valve 22 arranged on the mixing pipe 2, the second flow control valve 22 is arranged between the temperature sensor 21 and the absorption chiller 1, and the second flow control valve 22 is electrically connected to the controller. The second flow control valve 22 controls the mixed water flow in the mixing pipe 2 to meet the maximum flow demand of the refrigeration station. Among them, the second flow control valve 22 is an integrated control valve with flow detection and flow control. In other embodiments of the utility model, a split flow meter and a control valve can be set to realize the detection and control of the mixed water flow in the mixing pipe 2.

[0031] Since the cooling capacity required in the refrigeration station varies with the season and other working conditions, such as in summer, the cooling capacity required is large due to the large number of air conditioners put into operation, so the mixed water flow rate flowing into the absorption refrigeration machine 1 needs to be changed accordingly; in this embodiment, the setting value of the second flow control valve 22 is determined according to the maximum flow demand of the refrigeration station. During the operation of the power plant and the refrigeration station, the setting value of the second flow control valve 22 remains unchanged, so that the hot water circulation system formed by the economizer 4 and the absorption refrigeration machine 1 forms a closed cycle. In this embodiment, the power plant waste heat utilization system includes a shunt pipe 5, the first end of the shunt pipe 5 is connected to the water outlet of the second flow control valve 22, and the second end of the shunt pipe 5 is connected to the water inlet of the economizer 4. The sum of the mixed water flow rate in the shunt pipe 5 and the mixed water flow rate required by the absorption refrigeration machine 1 is equal to the mixed water flow rate in the mixing pipe 2. When the required mixed water volume of the absorption refrigeration machine 1 decreases, the water flow rate in the shunt pipe 5 is increased, and when the required mixed water volume of the absorption refrigeration machine 1 increases, the water flow rate in the shunt pipe 5 is reduced.

[0032] Specifically, in order to facilitate the mixing of water in the bypass pipe 5 and the return of the mixed water after being utilized by the absorption chiller 1 to the economizer 4, in this embodiment, the power plant waste heat utilization system includes a first pump body 61, and the low-temperature water outlet of the absorption chiller 1 and the second end of the bypass pipe 5 are both connected to the water inlet of the first pump body 61, and the water outlet of the first pump body 61 is connected to the water inlet of the economizer 4 and the end of the reflux pipe 3 close to the absorption chiller 1.

[0033] The power plant waste heat utilization system includes a three-way regulating valve 62, one end of the mixing pipe 2 close to the absorption chiller 1 is connected to the first port of the three-way regulating valve 62, the hot water inlet of the absorption chiller 1 is connected to the second port of the three-way regulating valve 62, and the first end of the diverter pipe 5 is connected to the third port of the three-way regulating valve 62. Specifically, the three-way regulating valve 62 is an integrated three-way valve with a flow regulating function. In other embodiments of the utility model, the three-way regulating valve 62 can be set as an ordinary three-way pipe, and the flow regulating function is realized by setting a flow regulating valve at the water outlet of the three-way pipe.

[0034] The power plant in this embodiment is a natural gas peaking power plant, and the natural gas banner power plant uses natural gas as energy to generate electricity. The power plant waste heat utilization system in this embodiment includes a second heat exchanger 71 for heating natural gas, and the water inlet of the second heat exchanger 71 is connected to the water outlet of the economizer 4, and the water outlet of the second heat exchanger 71 is connected to the water inlet of the economizer 4. The second heat exchanger 71 uses the hot water generated by the economizer 4 to heat the natural gas to the temperature required by the inlet of the gas turbine, thereby improving the thermal efficiency of the gas turbine.

[0035] Furthermore, in order to facilitate the water flowing out of the second heat exchanger 71 to flow back to the economizer 4, in this embodiment, the power plant waste heat utilization system includes a second pump body 72, the water inlet of the second pump body 72 is connected to the water outlet of the second heat exchanger 71, and the water outlet of the second pump body 72 is connected to the water inlet of the economizer 4.

[0036] In this embodiment, the power plant waste heat utilization system includes a third heat exchanger 73 for absorbing the cold energy of the natural gas after the pressure reduction. The air inlet of the third heat exchanger 73 is connected to the air outlet of the natural gas pressure reduction device, and the air outlet of the third heat exchanger 73 is connected to the air inlet of the second heat exchanger 71; the water inlet of the third heat exchanger 73 is connected to the water supply pipe 8, and the water outlet of the third heat exchanger 73 is connected to the cooling pipe 9.

[0037] Specifically, after the pressure is reduced, the natural gas at the pressure regulating station becomes low-temperature natural gas, and the temperature can be as low as below 0°C, which cannot meet the natural gas temperature requirement at the gas turbine inlet. In this embodiment, the third heat exchanger 73 is first used to absorb the cold energy of the natural gas, and the absorbed cold energy is used to cool the normal temperature water flowing into the third heat exchanger 73 from the water supply pipe 8, thereby cooling the normal temperature water into cold water, and realizing the effective use of the cold energy after the pressure reduction of the natural gas. The temperature of the natural gas flowing out of the third heat exchanger 73 is still lower than the required value of the natural gas temperature at the gas turbine inlet. Therefore, the natural gas flowing out of the third heat exchanger 73 enters the second heat exchanger 71 and reaches the gas turbine inlet temperature after being heated by the second heat exchanger 71.

[0038] In this embodiment, the cold water inlet of the absorption refrigeration machine 1 is connected to the water supply pipe 8, and the cold water outlet of the absorption refrigeration machine 1 is connected to the cooling pipe 9. The absorption refrigeration machine 1 and the third heat exchanger 73 jointly realize the refrigeration function of the refrigeration station.

[0039] To ensure that the make-up water smoothly enters the third heat exchanger 73, in this embodiment, the power plant waste heat utilization system includes a third pump body 81, one end of the make-up water pipe 8 is connected to the water supply system, the other end of the make-up water pipe 8 is connected to the water inlet of the third pump body 81, and the water outlet of the third pump body 81 is connected to the water inlet of the third heat exchanger 73.

[0040] In summary, the waste heat utilization system of a power plant of the utility model comprises an absorption refrigerator 1, an economizer 4 and a controller. The hot water inlet of the absorption refrigerator 1 is connected to a mixing pipe 2, in which a temperature sensor 21 is arranged; the low-temperature water outlet of the absorption refrigerator 1 is provided with a return pipe 3, in which a first flow control valve 31 is arranged; the end of the return pipe 3 away from the absorption refrigerator 1 is connected to the end of the mixing pipe 2 away from the absorption refrigerator 1; the economizer 4 is used to recover the waste heat of the flue gas of the waste heat boiler; the water inlet of the economizer 4 is connected to the low-temperature water outlet of the absorption refrigerator 1, and the water outlet of the economizer 4 is connected to the end of the mixing pipe 2 away from the absorption refrigerator 1; the temperature sensor 21 and the first flow control valve 31 are both connected to the controller The utility model is electrically connected to the power plant waste heat utilization system. The high-temperature water formed by the waste heat of flue gas heated by the economizer 4 flows into the absorption refrigerator 1 through the mixing pipe 2. The high-temperature water flowing into the absorption refrigerator 1 is absorbed by the absorption refrigerator 1 to form low-temperature water. The low-temperature water can flow back to the mixing pipe 2 through the return pipe 3 and mix with the high-temperature water flowing into the mixing pipe 2 to form mixed water. The water temperature of the mixed water can be known by the temperature sensor 21. The flow rate of the low-temperature water flowing into the mixing pipe 2 can be adjusted by the first flow control valve 31 set in the return pipe 3, thereby adjusting the water temperature of the mixed water. Thus, the heat input of the absorption refrigerator 1 is stable, and the cooling power of the absorption refrigerator 1 can be accurately adjusted. Moreover, the third heat exchanger 73 is set to realize the recycling of the cold capacity of the natural gas, and the natural gas is heated for the first time. The second heat exchanger 71 is used to realize the secondary heating of the natural gas, thereby improving the full utilization of the waste heat of the flue gas and the energy utilization efficiency of the power plant.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principle of the present invention. These improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A waste heat utilization system for a power plant, characterized in that: include: An absorption refrigerator (1), wherein a hot water inlet of the absorption refrigerator (1) is connected to a mixing pipe (2), wherein a temperature sensor (21) is provided in the mixing pipe (2); a low-temperature water outlet of the absorption refrigerator (1) is provided with a return pipe (3), wherein one end of the return pipe (3) away from the absorption refrigerator (1) is connected to one end of the mixing pipe (2) away from the absorption refrigerator (1), and a first flow control valve (31) is provided in the return pipe (3); an economizer (4), the economizer (4) being used to recover waste heat from flue gas of the waste heat boiler, the water inlet of the economizer (4) being connected to the low-temperature water outlet of the absorption refrigerator (1), and the water outlet of the economizer (4) being connected to an end of the mixing pipe (2) away from the absorption refrigerator (1); A controller, wherein the temperature sensor (21) and the first flow control valve (31) are both electrically connected to the controller.

2. The power plant waste heat utilization system according to claim 1, characterized in that: The power plant waste heat utilization system comprises a second flow control valve (22) arranged on the mixing pipe (2), the second flow control valve (22) is arranged between the temperature sensor (21) and the absorption refrigeration machine (1), and the second flow control valve (22) is electrically connected to the controller.

3. The power plant waste heat utilization system according to claim 2, characterized in that: The power plant waste heat utilization system comprises a shunt pipe (5), a first end of the shunt pipe (5) being connected to a water outlet of the second flow control valve (22), and a second end of the shunt pipe (5) being connected to a water inlet of the economizer (4).

4. The power plant waste heat utilization system according to claim 3, characterized in that: The power plant waste heat utilization system comprises a first pump body (61), the low-temperature water outlet of the absorption refrigeration machine (1) and the second end of the diverter pipe (5) are both connected to the water inlet of the first pump body (61), and the water outlet of the first pump body (61) is connected to the water inlet of the economizer (4) and one end of the return pipe (3) close to the absorption refrigeration machine (1).

5. The power plant waste heat utilization system according to claim 3, characterized in that: The power plant waste heat utilization system comprises a three-way regulating valve (62), one end of the mixing pipe (2) close to the absorption refrigeration machine (1) is connected to the first port of the three-way regulating valve (62), the hot water inlet of the absorption refrigeration machine (1) is connected to the second port of the three-way regulating valve (62), and the first end of the diverter pipe (5) is connected to the third port of the three-way regulating valve (62).

6. The power plant waste heat utilization system according to claim 1, characterized in that: The power plant waste heat utilization system comprises a second heat exchanger (71) for heating natural gas, wherein the water inlet of the second heat exchanger (71) is connected to the water outlet of the economizer (4), and the water outlet of the second heat exchanger (71) is connected to the water inlet of the economizer (4).

7. The power plant waste heat utilization system according to claim 6, characterized in that: The power plant waste heat utilization system comprises a second pump body (72), the water inlet of the second pump body (72) is connected to the water outlet of the second heat exchanger (71), and the water outlet of the second pump body (72) is connected to the water inlet of the economizer (4).

8. The power plant waste heat utilization system according to claim 6, characterized in that: The power plant waste heat utilization system comprises a third heat exchanger (73) for absorbing the cold energy of the natural gas after decompression, the air inlet of the third heat exchanger (73) is used to connect to the air outlet of the natural gas decompression device, and the air outlet of the third heat exchanger (73) is connected to the air inlet of the second heat exchanger (71); The water inlet of the third heat exchanger (73) is connected to a water supply pipe (8), and the water outlet of the third heat exchanger (73) is used to connect to a cooling pipe (9).

9. The power plant waste heat utilization system according to claim 8, characterized in that: The cold water inlet of the absorption refrigeration machine (1) is in communication with the water supply pipe (8), and the cold water outlet of the absorption refrigeration machine (1) is in communication with the cooling pipe (9).

10. The power plant waste heat utilization system according to claim 8, characterized in that: The power plant waste heat utilization system comprises a third pump body (81), one end of the water supply pipe (8) is connected to the water supply system, the other end of the water supply pipe (8) is connected to the water inlet of the third pump body (81), and the water outlet of the third pump body (81) is connected to the water inlet of the third heat exchanger (73).

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