Multi-stage waste heat recycling system

Abstract

The multi-stage waste heat recycling system comprises a gas turbine, a waste heat boiler, a steam turbine, an evaporator, an expansion machine, a heat exchanger, a compressor, a condenser, an expansion valve and a water tank. High-temperature exhaust gas generated by the gas turbine enters the high-temperature power generation loop, the waste heat boiler can recycle generated steam and send the steam to the steam turbine for power generation, and low-temperature exhaust gas participating in power generation enters the evaporator for heat exchange and cooling and returns to the waste heat boiler. Heat exchanged by the evaporator participates in the low-temperature power generation loop to push the expansion machine to do work and generate power, and exhaust gas generated after the expansion machine does work enters the heat exchanger to be cooled into liquid and returns to the evaporator for heat exchange; the heat exchanged by the heat exchanger exchanges heat with the condenser through the heat pump system, the condenser is in loop connection with the water tank, the heat of the condenser is transferred into the water tank, places such as domestic water are heated, multi-stage utilization of the heat is achieved, multi-stage utilization of a heat source can be achieved, and therefore the energy utilization rate is increased.

Description

Technical Field

[0001] The present application relates to the field of waste heat recovery, and in particular to a multi-stage waste heat recovery and utilization system. Background Art

[0002] Thermal power plants are usually factories that use combustibles (coal or gas) as fuel to produce electricity. Its basic production process is: when the fuel is burned, it heats water to generate steam, converting the chemical energy of the fuel into thermal energy, and the steam pressure drives the turbine to rotate, converting the thermal energy into mechanical energy, and then the turbine drives the generator to rotate, converting the mechanical energy into electrical energy.

[0003] At present, in order to improve the efficiency of power generation, most of the systems using gas-steam combined cycle power supply are a power generation method that combines gas turbines and steam turbines and operates them together. Its power generation principle is to use the high-temperature and high-pressure flue gas discharged by the gas turbine as the heat source of the boiler, convert the heat energy into water vapor through the steam generator, and then drive the steam turbine to generate electricity. Since the waste heat generated during the combustion process of the gas turbine is fully utilized, the thermal energy utilization efficiency is improved, while the emission of pollutants such as carbon dioxide and nitrogen oxides is reduced.

[0004] Although the steam-gas combined cycle power generation improves the efficiency of power generation, some low-temperature heat sources are not utilized in the process, resulting in a waste of heat sources. Utility Model Content

[0005] In view of this, the present application proposes a multi-stage waste heat recovery and utilization system, which can utilize the heat source at multiple levels, thereby improving energy utilization.

[0006] According to one aspect of the present application, a multi-stage waste heat recovery system is provided, comprising: a gas turbine, a waste heat boiler, a steam turbine, an evaporator, an expander, a heat exchanger, a compressor, a condenser, an expansion valve and a water tank.

[0007] The gas turbine is provided with an air inlet, and the outlet end of the gas turbine is connected to the inlet end of the waste heat boiler by a pipeline; the waste heat boiler, the steam turbine and the evaporator are connected in a loop to form a high-temperature power generation loop, the evaporator, the expander and the heat exchanger are connected in a loop to form a low-temperature power generation loop, the heat exchanger, the compressor, the condenser and the expansion valve are connected in a loop to form a condensation loop, and the water tank and the condenser are connected in a loop to form a recycling loop.

[0008] In one possible implementation, the outlet end of the waste heat boiler is connected to the inlet end of the steam turbine by a pipeline, the outlet end of the steam turbine is connected to the first inlet of the evaporator by a pipeline, and the first outlet of the evaporator is connected to the second inlet of the waste heat boiler by a pipeline.

[0009] In one possible implementation, the second outlet of the evaporator is connected to the inlet of the expander by a pipeline, the outlet of the expander is connected to the first inlet of the heat exchanger by a pipeline, and the first outlet of the heat exchanger is connected to the second inlet of the evaporator by a pipeline.

[0010] In one possible implementation, a pipeline is connected between the second outlet of the heat exchanger and the inlet of the compressor, a pipeline is connected between the outlet of the compressor and the first inlet of the condenser, a pipeline is connected between the first outlet of the condenser and the inlet of the expansion valve, and a pipeline is connected between the outlet of the expansion valve and the second inlet of the heat exchanger.

[0011] In a possible implementation, the second outlet of the condenser is connected to the inlet end of the water tank by a pipeline, and the outlet end of the water tank is connected to the second inlet of the condenser by a pipeline.

[0012] In a possible implementation, the outlet end of the gas turbine is connected to the first inlet of the waste heat boiler by a pipeline.

[0013] In one possible implementation, it also includes: a first circulating pump, which is arranged between the evaporator and the waste heat boiler, a first outlet of the evaporator is connected to the inlet end of the first circulating pump by a pipeline, and an outlet end of the first circulating pump is connected to the second inlet end of the waste heat boiler by a pipeline.

[0014] In one possible implementation, it also includes: a second circulation pump, which is arranged between the evaporator and the heat exchanger, a first outlet of the heat exchanger is connected to an inlet end of the second circulation pump by a pipeline, and an outlet end of the second circulation pump is connected to a second inlet end of the evaporator by a pipeline.

[0015] The beneficial effects of the present application are as follows: the high-temperature exhaust gas generated by the gas turbine enters the high-temperature power generation circuit, wherein the waste heat boiler can recover the generated steam and send it to the steam turbine for power generation, and the low-temperature exhaust gas after participating in power generation enters the evaporator for heat exchange and cooling, and returns to the waste heat boiler; the heat exchanged by the evaporator participates in the low-temperature power generation circuit, driving the expander to work and generate electricity, and the exhaust gas after the expander works enters the heat exchanger to be cooled into liquid and returns to the evaporator for heat exchange; the heat exchanged by the heat exchanger is exchanged with the condenser through the heat pump system, the condenser is connected to the water tank circuit, and the heat of the condenser is transferred to the water tank to heat domestic water and other places, thereby realizing multi-stage utilization of heat. According to a multi-stage waste heat recovery and utilization system of the present application, the heat source can be utilized at multiple levels, thereby improving energy utilization.

[0016] Other features and aspects of the present application will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the present application and, together with the description, serve to explain the principles of the present application.

[0018] Figure 1 A connection diagram of a multi-stage waste heat recovery system according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0019] Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0020] Among them, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application or simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0022] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0023] In addition, in order to better illustrate the present application, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present application.

[0024] As shown in the figure, the multi-stage waste heat recovery system includes: a gas turbine 100, a waste heat boiler 210, a steam turbine 220, an evaporator 300, an expander 410, a heat exchanger 500, a compressor 610, a condenser 700, an expansion valve 620 and a water tank 800.

[0025] The gas turbine 100 is provided with an air inlet, and the outlet end of the gas turbine 100 is connected to the inlet end of the waste heat boiler 210 by a pipeline; the waste heat boiler 210, the steam turbine 220 and the evaporator 300 are connected in a loop to form a high-temperature power generation loop a, the evaporator 300, the expander 410 and the heat exchanger 500 are connected in a loop to form a low-temperature power generation loop b, the heat exchanger 500, the compressor 610, the condenser 700 and the expansion valve 620 are connected in a loop to form a condensation loop c, and the water tank 800 and the condenser 700 are connected in a loop to form a recycling loop d.

[0026] When working, the gas turbine 100 mixes and burns compressed air with natural gas in the combustion chamber to generate high-temperature and high-pressure gas to drive the impeller to rotate, thereby doing work to drive the gas turbine generator to generate electricity. The tail of the gas turbine 100 will discharge high-temperature exhaust gas as it burns and introduce the flue gas into the waste heat boiler 210.

[0027] High-temperature power generation circuit a: The waste heat boiler 210 recovers the waste heat in the flue gas to generate steam, and then inputs the steam as a heat source into the steam turbine 220 to drive the steam turbine 220 generator to generate electricity. The exhaust gas generated by the steam turbine 220 enters the evaporator 300, and after the heat is absorbed, it is pumped into the waste heat boiler 210 by the first circulation pump 230 to complete a cycle.

[0028] Low-temperature power generation circuit b: The high-temperature power generation circuit a enters the evaporator 300 to exchange heat. Since the medium in the low-temperature power generation circuit b is an organic working fluid with a low boiling point, it can absorb heat from the low-temperature heat source even when the temperature of the waste heat source is not high, thereby generating organic steam, which drives the expander 410 to rotate and drive the generator to generate electricity. The exhaust gas after the expander 410 has done work enters the heat exchanger 500 and is cooled into liquid again, and is pumped into the evaporator 300 by the second circulation pump 420 to complete a cycle.

[0029] Condensation loop c and recycling loop d: In the process of low-temperature power generation loop b, when the exhaust gas after the work of the expander 410 enters the heat exchanger 500 and is cooled into liquid again, power plants often use cooling towers to complete the cooling process, but this causes part of the heat to be wasted. Therefore, a heat pump system is used to replace the cooling tower in the conventional mode. The refrigerant absorbs part of the heat to evaporate it into a gaseous refrigerant, and then enters the compressor 610. The compressor 610 compresses the refrigerant into a high-temperature and high-pressure gas, which enters the condenser 700 for heat exchange and heats the water in the water tank 800. The gaseous refrigerant releases heat and becomes liquid refrigerant. After passing through the expansion valve 620, it becomes a gas-liquid two-phase refrigerant and enters the heat exchanger 500 again to absorb heat and evaporate into gas, and the cycle repeats.

[0030] Among them, in the high-temperature power generation circuit a, the high-temperature flue gas of about 300℃-600℃ generated by the gas turbine 100 is sent to the waste heat boiler 210, and the remaining heat is used to prepare steam to drive the steam turbine 220 to generate electricity. Therefore, it combines the advantages of the gas turbine 100 and the steam turbine 220, and has the advantages of full energy utilization and increased power generation efficiency.

[0031] In the low-temperature power generation circuit b, namely, ORC (Organic Rankine Cycle) power generation, the organic working fluid absorbs the waste heat generated by the previous power generation in the evaporator 300 and turns into steam, and the steam enters the screw expander 410 to perform work, thereby driving the generator to generate electricity. The exhaust steam discharged therefrom releases heat in the heat exchanger 500, condenses into liquid, and finally returns to the evaporator 300 with the help of the second circulation pump 420, and the cycle continues in this way.

[0032] The refrigerant in the condensing circuit c absorbs heat in the heat exchanger 500 and becomes a gaseous refrigerant, which enters the compressor 610, and then becomes a high-temperature and high-pressure refrigerant, which enters the condenser 700 to release heat and transfer the heat to the water tank 800. The hot water in the water tank 800 can be used as a heat source for heating surrounding users or domestic hot water. The refrigerant after releasing heat becomes a liquid refrigerant, which becomes a gas-liquid two-phase refrigerant after passing through the expansion valve 620, and then enters the heat exchanger 500 and repeats the cycle.

[0033] In one possible implementation, the outlet end of the waste heat boiler 210 is connected to the inlet end of the steam turbine 220 by a pipeline, the outlet end of the steam turbine 220 is connected to the first inlet of the evaporator 300 by a pipeline, and the first outlet of the evaporator 300 is connected to the second inlet of the waste heat boiler 210 by a pipeline.

[0034] In one possible implementation, a pipeline is connected between the second outlet of the evaporator 300 and the inlet end of the expander 410, a pipeline is connected between the outlet end of the expander 410 and the first inlet of the heat exchanger 500, and a pipeline is connected between the first outlet of the heat exchanger 500 and the second inlet of the evaporator 300.

[0035] In one possible implementation, a pipeline is connected between the second outlet of the heat exchanger 500 and the inlet of the compressor 610, a pipeline is connected between the outlet of the compressor 610 and the first inlet of the condenser 700, a pipeline is connected between the first outlet of the condenser 700 and the inlet of the expansion valve 620, and a pipeline is connected between the outlet of the expansion valve 620 and the second inlet of the heat exchanger 500.

[0036] In a possible implementation, the second outlet of the condenser 700 is connected to the inlet end of the water tank 800 by a pipeline, and the outlet end of the water tank 800 is connected to the second inlet of the condenser 700 by a pipeline.

[0037] In a possible implementation, the outlet end of the gas turbine 100 is connected to the first inlet of the waste heat boiler 210 by a pipeline.

[0038] In one possible implementation, it also includes: a first circulation pump 230, which is arranged between the evaporator 300 and the waste heat boiler 210, a pipeline is connected between the first outlet of the evaporator 300 and the inlet end of the first circulation pump 230, and a pipeline is connected between the outlet end of the first circulation pump 230 and the second inlet end of the waste heat boiler 210.

[0039] In one possible implementation, it also includes: a second circulation pump 420, which is arranged between the evaporator 300 and the heat exchanger 500, and a pipeline is connected between the first outlet of the heat exchanger 500 and the inlet end of the second circulation pump 420, and a pipeline is connected between the outlet end of the second circulation pump 420 and the second inlet end of the evaporator 300.

[0040] It should be noted that although a multi-stage waste heat recovery system is introduced as an example in this application, those skilled in the art will understand that this application should not be limited thereto. In fact, users can flexibly set various parameters according to personal preferences and / or actual application scenarios, as long as the design is reasonable.

[0041] In this way, the high-temperature exhaust gas generated by the gas turbine enters the high-temperature power generation circuit, wherein the waste heat boiler can recover the heat of the flue gas to generate steam and send it to the steam turbine for power generation, and the low-temperature exhaust gas after participating in power generation enters the evaporator for heat exchange and cooling, and returns to the waste heat boiler; the heat exchanged by the evaporator participates in the low-temperature power generation circuit, driving the expander to work and generate electricity, and the exhaust gas after the expander works enters the heat exchanger to be cooled into liquid and returns to the evaporator for heat exchange; the heat exchanged by the heat exchanger is exchanged with the condenser through the heat pump system, the condenser is connected to the water tank circuit, and the heat of the condenser is transferred to the water tank to heat domestic water and other places, thereby realizing multi-stage utilization of heat. According to a multi-stage waste heat recovery and utilization system of the present application, the heat source can be utilized at multiple levels, thereby improving energy utilization.

[0042] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A multi-stage waste heat recovery system, characterized in that: include: Gas turbine, waste heat boiler, steam turbine, evaporator, expander, heat exchanger, compressor, condenser, expansion valve and water tank; The gas turbine is provided with an air inlet, and the outlet end of the gas turbine is connected to the inlet end of the waste heat boiler by a pipeline; The waste heat boiler, the steam turbine and the evaporator are connected in a loop to form a high-temperature power generation loop; the evaporator, the expander and the heat exchanger are connected in a loop to form a low-temperature power generation loop; the heat exchanger, the compressor, the condenser and the expansion valve are connected in a loop to form a condensation loop; the water tank and the condenser are connected in a loop to form a recycling loop.

2. The multi-stage waste heat recovery system according to claim 1, characterized in that: The outlet end of the waste heat boiler is connected to the inlet end of the steam turbine by a pipeline, the outlet end of the steam turbine is connected to the first inlet of the evaporator by a pipeline, and the first outlet of the evaporator is connected to the second inlet of the waste heat boiler by a pipeline.

3. The multi-stage waste heat recovery system according to claim 2, characterized in that: The second outlet of the evaporator is connected to the inlet of the expander by a pipeline, the outlet of the expander is connected to the first inlet of the heat exchanger by a pipeline, and the first outlet of the heat exchanger is connected to the second inlet of the evaporator by a pipeline.

4. The multi-stage waste heat recovery system according to claim 3 is characterized in that: The second outlet of the heat exchanger is connected to the inlet of the compressor by a pipeline, the outlet of the compressor is connected to the first inlet of the condenser by a pipeline, the first outlet of the condenser is connected to the inlet of the expansion valve by a pipeline, and the outlet of the expansion valve is connected to the second inlet of the heat exchanger by a pipeline.

5. The multi-stage waste heat recovery system according to claim 4 is characterized in that: The second outlet of the condenser is connected to the inlet end of the water tank by a pipeline, and the outlet end of the water tank is connected to the second inlet of the condenser by a pipeline.

6. The multi-stage waste heat recovery system according to claim 5, characterized in that: The outlet end of the gas turbine is connected to the first inlet of the waste heat boiler through a pipeline.

7. The multi-stage waste heat recovery system according to claim 2, characterized in that: Also includes: A first circulation pump, wherein the first circulation pump is arranged between the evaporator and the waste heat boiler, a first outlet of the evaporator is connected to an inlet of the first circulation pump by a pipeline, and an outlet of the first circulation pump is connected to a second inlet of the waste heat boiler by a pipeline.

8. The multi-stage waste heat recovery system according to claim 3, characterized in that: Also includes: A second circulation pump is provided between the evaporator and the heat exchanger, a first outlet of the heat exchanger is connected to an inlet of the second circulation pump by a pipeline, and an outlet of the second circulation pump is connected to a second inlet of the evaporator by a pipeline.

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