System for recycling waste heat of power plant condensate

Abstract

The present invention relates to the technical field of waste heat recycling. Disclosed is a system for recycling waste heat of power plant condensate, comprising an absorption heat pump loop, which comprises an evaporator and an absorber. The absorption heat pump loop is connected to a low-parameter extracted steam loop and a high-parameter extracted steam loop by means of the evaporator, and the absorption heat pump loop is connected to a heating network circulating water loop by means of the absorber. In multi-unit heating, the heat grade of high-parameter extracted steam is used for driving the absorption heat pump loop, so as to realize the effective utilization of high-grade heat and reduce exergy losses of large-temperature-difference heat transfer. Furthermore, condensate formed after low-parameter and high-parameter steams are cooled in a basic heating network heater, a peak heating network heater, and a generator enters the evaporator, and a low-pressure solvent evaporation process is used for further deep recycling of waste heat of the condensate. In addition, the temperature of heating network water is increased by means of staged heating, thereby improving the temperature difference uniformity throughout a heat transfer process and reducing irreversible losses during heat transfer.

Description

A power plant waste heat recovery system Technical Field

[0001] This invention relates to the technical field of waste heat recovery, and more particularly to a waste heat recovery and utilization system for power plant condensate drains. Background Technology

[0002] To further reduce the consumption of fossil fuels such as coal and contribute to achieving carbon peaking and carbon neutrality goals, a new round of transformation has begun in the energy sector. In the heating sector, centralized heating and long-distance heating are conducive to improving the utilization rate of large-scale combined heat and power (CHP) units and reducing fossil fuel consumption and carbon emissions caused by decentralized boiler heating, showing broad application prospects. In recent years, Shanxi, Shandong, Hebei, Inner Mongolia and other regions have launched projects related to long-distance heating and centralized heating, and some projects have been put into operation, realizing the comprehensive utilization of large-scale CHP units under the centralized heating model.

[0003] Centralized heating typically originates from large-scale thermal power plants within a given region. These plants usually contain multiple combined heat and power (CHP) units with varying capacities and extraction steam for heating. Therefore, the extraction steam from these plants is generally categorized into low-parameter and high-parameter steam. Low-parameter steam typically operates at around 0.1 MPa and 120°C, while high-parameter steam can reach 0.7 MPa and 250°C. Due to these parameter differences, low-parameter steam is typically used in the basic heaters, while high-parameter steam is used in the peak heaters. The return water from the heating network passes through both the basic and peak heaters, undergoing a sequential heating process. Both types of steam are cooled to approximately 70°C in the heaters, resulting in condensate.

[0004] The existing technologies described above have the following problems:

[0005] 1. High-parameter steam is used directly for heating. Due to the large temperature difference in heat transfer, the energy quality loss is large, which reduces the energy utilization efficiency and heating economy.

[0006] 2. In long-distance heating, since the return water temperature of the long-distance pipeline is around 70℃, the outlet temperature of the condensate of the heating network heater is around 70℃. The condensate still has a certain amount of heat, which has not been effectively utilized.

[0007] Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention is proposed.

[0009] Therefore, the purpose of this invention is to provide a power plant hydrophobic waste heat recovery and utilization system.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a power plant condensate waste heat recovery and utilization system, comprising,

[0011] An absorption heat pump circuit includes an evaporator and an absorber;

[0012] The absorption heat pump circuit is connected to a low-parameter extraction steam circuit and a high-parameter extraction steam circuit through the evaporator, and the absorption heat pump circuit is connected to a heating network circulating water circuit through the absorber.

[0013] As a preferred embodiment of the power plant condensate waste heat recovery and utilization system of the present invention, the high-parameter extraction steam circuit includes a high-parameter extraction steam first circuit and a high-parameter extraction steam second circuit.

[0014] As a preferred embodiment of the power plant hydrophobic waste heat recovery and utilization system of the present invention, the absorption heat pump circuit includes an absorption heat pump solution circuit and an absorption heat pump solvent circuit.

[0015] As a preferred embodiment of the power plant condensate waste heat recovery and utilization system of the present invention, the heat network circulating water circuit includes a basic heat network heater, an absorber connected to the outside of the basic heat network heater, a condenser connected to the outside of the absorber, and a peak heat network heater connected to the outside of the condenser.

[0016] As a preferred embodiment of the power plant condensate waste heat recovery and utilization system of the present invention, the low-parameter extraction steam circuit includes a low-parameter extraction steam unit, a basic heat network heater connected to the outside of the low-parameter extraction steam unit, an evaporator connected to the outside of the basic heat network heater, and a condensate collector connected to the outside of the evaporator.

[0017] As a preferred embodiment of the power plant condensate waste heat recovery and utilization system of the present invention, the high-parameter extraction steam first loop includes a high-parameter extraction steam unit, a generator connected to the outside of the high-parameter extraction steam unit, an evaporator connected to the outside of the generator, and a condensate collector connected to the outside of the evaporator.

[0018] As a preferred embodiment of the power plant condensate waste heat recovery and utilization system of the present invention, the high-parameter extraction steam second loop includes the high-parameter extraction steam unit, the peak heat network heater connected to the outside of the high-parameter extraction steam unit, the evaporator connected to the outside of the peak heat network heater, and the condensate collector connected to the outside of the evaporator.

[0019] As a preferred embodiment of the power plant hydrophobic waste heat recovery and utilization system of the present invention, the absorption heat pump solution circuit includes the generator, a solution heat exchanger connected to the outside of the generator, a solution expansion valve connected to the outside of the solution heat exchanger, an absorber connected to the outside of the solution expansion valve, and a solution pump connected to the outside of the absorber.

[0020] As a preferred embodiment of the power plant hydrophobic waste heat recovery and utilization system of the present invention, the absorption heat pump solvent circuit includes the generator, the condenser connected to the outside of the generator, the solvent throttling valve connected to the outside of the condenser, the evaporator connected to the outside of the solvent throttling valve, and the absorber connected to the outside of the evaporator.

[0021] As a preferred embodiment of the power plant hydrophobic waste heat recovery and utilization system of the present invention, wherein: the absorber and the solution heat exchanger are connected through two channels, one channel is equipped with the solution expansion valve, and the other channel is equipped with the solution pump, and the solution flows in opposite directions inside the two channels;

[0022] The generator is connected to the solution heat exchanger through two channels, with the solution flowing in opposite directions inside the two channels.

[0023] The beneficial effects of this invention are as follows: In multi-unit heating, the heat quality of high-parameter extracted steam drives the absorption heat pump circuit, realizing the effective utilization of high-grade heat and reducing the effective energy loss of heat transfer with large temperature difference. Furthermore, the condensate formed after the low-parameter steam and high-parameter steam are cooled in the basic heating network heater, peak heating network heater, and generator enters the evaporator. The waste heat of the condensate is further recovered and utilized through the low-pressure solvent evaporation process. In addition, the temperature of the heating network water is increased through staged heating, which improves the temperature difference uniformity throughout the heat transfer process and reduces irreversible losses in the heat transfer process. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0025] Figure 1 is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0028] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0029] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0030] Example 1

[0031] Referring to Figure 1, which illustrates the first embodiment of the present invention, a power plant waste heat recovery and utilization system is provided, comprising:

[0032] An absorption heat pump circuit D includes an evaporator 108 and an absorber 109;

[0033] The absorption heat pump circuit D is connected to the low-parameter extraction steam circuit B and the high-parameter extraction steam circuit C through the evaporator 108, and the absorption heat pump circuit D is connected to the heating network circulating water circuit A through the absorber 109.

[0034] Specifically, the high-parameter extraction steam circuit C includes the first high-parameter extraction steam circuit C-1 and the second high-parameter extraction steam circuit C-2.

[0035] Furthermore, the absorption heat pump circuit D includes an absorption heat pump solution circuit D-1 and an absorption heat pump solvent circuit D-2.

[0036] Furthermore, the heating network circulating water circuit A includes a basic heating network heater 103, an absorber 109 connected to the outside of the basic heating network heater 103, a condenser 107 connected to the outside of the absorber 109, and a peak heating network heater 104 connected to the outside of the condenser 107.

[0037] In the circulating water loop A of the heating network, the heating network water passes through the basic heating network heater 103, absorber 109, condenser 107, and peak heating network heater 104 in sequence.

[0038] After the hot water flows out from the peak hot water heater 104, it is used for hot water supply. The purpose of this system is to recover and utilize the waste heat of the power plant condensate, that is, to use the waste heat of the power plant condensate to increase the temperature of the hot water, so that the temperature of the hot water used for hot water supply is increased.

[0039] Example 2

[0040] Referring to Figure 1, this is the second embodiment of the present invention, which differs from the first embodiment in that it provides the working process of the low-parameter extraction steam circuit B and the high-parameter extraction steam circuit C.

[0041] Furthermore, the low-parameter extraction steam circuit B includes a low-parameter extraction steam unit 101, a basic heat network heater 103 connected to the outside of the low-parameter extraction steam unit 101, an evaporator 108 connected to the outside of the basic heat network heater 103, and a condensate collector 105 connected to the outside of the evaporator 108.

[0042] Furthermore, the high-parameter extraction steam first loop C-1 includes a high-parameter extraction steam unit 102, a generator 106 connected to the outside of the high-parameter extraction steam unit 102, an evaporator 108 connected to the outside of the generator 106, and a condensate collector 105 connected to the outside of the evaporator 108.

[0043] Specifically, the high-parameter extraction steam second loop C-2 includes a high-parameter extraction steam unit 102, a peak heat network heater 104 connected to the outside of the high-parameter extraction steam unit 102, an evaporator 108 connected to the outside of the peak heat network heater 104, and a condensate collector 105 connected to the outside of the evaporator 108.

[0044] In existing technologies, conventional measures for utilizing waste heat from power plant condensates are as follows:

[0045] The low-parameter extraction steam circuit consists of a low-parameter extraction steam unit 101, a basic heating network heater 103, and a condensate collector 105.

[0046] The low-parameter extraction steam from the low-parameter extraction steam unit 101 first enters the basic heating network heater 103. In the basic heating network heater 103, heat exchange occurs between the steam and the heating network circulating water in the heating network circulating water loop A. This cools the relatively high-temperature low-parameter extraction steam to approximately 70°C as condensate, while simultaneously raising the temperature of the heating network water. The condensate then directly enters the condensate collector 105, ending the waste heat recovery process. During this process, the condensate entering the condensate collector 105 is at approximately 70°C, meaning some heat remains unrecovered.

[0047] The high-parameter extraction steam circuit consists of a high-parameter extraction steam unit 102, a peak heat network heater 104, and a condensate collector 105.

[0048] The high-parameter extraction steam from the high-parameter extraction steam unit 102 first enters the peak heat network heater 104. In the peak heat network heater 104, heat exchange occurs between the high-parameter extraction steam and the heat network circulating water in the heat network circulating water loop A. This cools the high-temperature low-parameter extraction steam to a lower-temperature condensate, raising the temperature of the heat network water. The condensate then directly enters the condensate collector 105, ending the condensate waste heat recovery process. During this process, some heat remains in the condensate entering the condensate collector 105 that is not recovered.

[0049] This system improves upon both the low-parameter extraction steam circuit B and the high-parameter extraction steam circuit C.

[0050] The components of the low-parameter extraction steam circuit B are: low-parameter extraction steam unit 101, basic heat network heater 103, evaporator 108, and condensate collector 105.

[0051] The low-parameter extraction steam from the low-parameter extraction steam unit 101 first enters the basic heating network heater 103. In the basic heating network heater 103, heat exchange occurs between the basic heating network heater and the heating network circulating water in the heating network circulating water circuit A. This causes the high-temperature low-parameter extraction steam to be cooled to about 70°C by the heating network water, and the temperature of the heating network water is increased. Then, the condensate enters the evaporator 108 in the absorption heat pump circuit D. In the evaporator 108, the condensate undergoes heat exchange with the solvent inside the evaporator 108, which further cools the condensate to about 40°C. Then, it enters the condensate collector 105.

[0052] The high-parameter extraction steam second loop C-2 consists of a high-parameter extraction steam unit 102, a peak heat network heater 104, an evaporator 108, and a condensate collector 105.

[0053] The high-parameter extraction steam from the high-parameter extraction steam unit 102 is divided into two parts. One part enters the peak heat network heater 104, where it exchanges heat with the heat network water in the heat network circulating water circuit A. This cools the high-temperature low-parameter extraction steam to a lower-temperature condensate, raising the temperature of the heat network water. The condensate, along with the condensate from the basic heat network heater 103, then enters the evaporator 108 in the absorption heat pump circuit D. In the evaporator 108, the condensate exchanges heat with the solvent inside the evaporator 108, further cooling it to about 40°C before entering the condensate collector 105.

[0054] In the high-parameter extraction steam first loop C-1, its components are a high-parameter extraction steam unit 102, a generator 106, an evaporator 108, and a condensate collector 105.

[0055] Two portions of high-parameter extraction steam from the high-parameter extraction steam unit 102 are fed into the generator 106 in the absorption heat pump circuit D. The high-parameter extraction steam exchanges heat with the solution inside the generator 106, cooling the high-parameter extraction steam to a lower temperature condensate. This condensate, along with condensates from the basic heating network heater 103 and the peak heating network heater 104, enters the evaporator 108 in the absorption heat pump circuit D. The condensate exchanges heat with the solvent inside the evaporator 108, further cooling the condensate to about 40°C, and then enters the condensate collector 105.

[0056] In summary, in the above system, our invention introduces an absorption heat pump circuit D into the low-parameter extraction circuit B and the high-parameter extraction circuit C, which allows the originally high-temperature condensate to be further cooled, thereby improving the utilization rate of condensate waste heat.

[0057] Example 3

[0058] Referring to Figure 1, this is the third embodiment of the present invention, which differs from the second embodiment in that it provides the working process of the absorption heat pump circuit D.

[0059] Furthermore, the absorption heat pump solution loop D-1 includes a generator 106, a solution heat exchanger 110 connected to the outside of the generator 106, a solution expansion valve 111 connected to the outside of the solution heat exchanger 110, an absorber 109 connected to the outside of the solution expansion valve 111, and a solution pump 112 connected to the outside of the absorber 109.

[0060] Furthermore, the absorption heat pump solvent circuit D-2 includes a generator 106, a condenser 107 connected to the outside of the generator 106, a solvent throttling valve 113 connected to the outside of the condenser 107, an evaporator 108 connected to the outside of the solvent throttling valve 113, and an absorber 109 connected to the outside of the evaporator 108.

[0061] Specifically, the absorber 109 is connected to the solution heat exchanger 110 through two channels. One channel is equipped with a solution expansion valve 111, and the other channel is equipped with a solution pump 112. The solutions flow in opposite directions inside the two channels.

[0062] The generator 106 is connected to the solution heat exchanger 110 through two channels, and the solution flows in opposite directions inside the two channels.

[0063] The waste heat from the outlet of the basic heating network heater 103, the peak heating network heater 104, and the generator 106 is deeply recovered and utilized through the absorption heat pump circuit D. The utilization principle is as follows:

[0064] The driving heat source for generator 106 is high-temperature high-parameter extraction steam from high-parameter extraction steam unit 102. The solution in generator 106 absorbs the heat from the high-parameter extraction steam, and the solvent in the solution absorbs heat and evaporates, increasing the concentration of the original solution in generator 106. The evaporated gaseous solvent enters condenser 107.

[0065] In the condenser 107, the gaseous solvent exchanges heat with the heating network water in the heating network circulating water circuit A. The gaseous solvent is condensed into a liquid state and enters the evaporator 108 after being depressurized by the solvent throttling valve 113. In the evaporator 108, the solvent absorbs hydrophobic heat from the basic heating network heater 103, the peak heating network heater 104, and the generator 106 and is evaporated again. The evaporated solvent enters the absorber 109 from the evaporator 108.

[0066] After the concentrated solution in generator 106 absorbs heat from the high-parameter extraction steam and its temperature rises, it first enters solution heat exchanger 110 to exchange heat with the dilute solution from absorber 109.

[0067] After heat exchange, the concentrated solution is throttled and depressurized by the solution expansion valve 111, and then enters the absorber 109 to absorb the solvent from the evaporator 108, release heat, and become a dilute solution. It is then pressurized by the solution pump 112 and enters the solution heat exchanger 110. This provides the dilute solution for the concentrated solution to exchange heat with the dilute solution from the absorber 109 in the solution heat exchanger 110 during the above process.

[0068] The dilute solution exchanges heat with the concentrated solution in the solution heat exchanger 110 to recover the heat of the concentrated solution, and then enters the generator 106 to complete the solution circulation.

[0069] After the above process, the condensate temperature at the outlet of the basic heating network heater 103, the peak heating network heater 104, and the generator 106 can all be reduced to about 40°C, thereby achieving deep utilization of heat.

[0070] The return water from the heating network first enters the basic heating network heater 103, absorbing the heat released by the low-parameter extraction steam. Then it enters the absorber 109, absorbing the heat released when the concentrated solution absorbs the solvent. Next, it enters the condenser 107, absorbing the heat released by the condensation of the gaseous solvent. Finally, it enters the peak heating network heater 104, absorbing the heat released by the high-parameter extraction steam. The outlet temperature of the heating network water in the peak heating network heater 104 meets the requirements for hot water supply, thus realizing the heating function of this system.

[0071] In summary, in multi-unit heating systems, the high-parameter extracted steam is used to drive the absorption heat pump circuit D, achieving effective utilization of high-grade heat and reducing energy loss during large temperature difference heat transfer. Furthermore, the condensate formed after the low-parameter and high-parameter steam are cooled in the basic heating network heater 103, the peak heating network heater 104, and the generator 106 all enter the evaporator 108. The low-pressure solvent evaporation process further enables deep recovery and utilization of the condensate waste heat. In addition, the temperature of the heating network water is increased through staged heating, improving the temperature difference uniformity throughout the heat transfer process and reducing irreversible losses in the heat transfer process.

[0072] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0073] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the currently considered best mode for carrying out the invention, or those features that are not relevant to implementing the invention) may be omitted.

[0074] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A power plant waste heat recovery and utilization system, characterized in that: include, An absorption heat pump circuit (D) includes an evaporator (108) and an absorber (109); The absorption heat pump circuit (D) is connected to a low-parameter extraction circuit (B) and a high-parameter extraction circuit (C) through the evaporator (108), and the absorption heat pump circuit (D) is connected to a heating network circulating water circuit (A) through the absorber (109).

2. The power plant waste heat recovery and utilization system according to claim 1, characterized in that: The high-parameter extraction circuit (C) includes a high-parameter extraction first circuit (C-1) and a high-parameter extraction second circuit (C-2).

3. The power plant condensate waste heat recovery and utilization system according to claim 2, characterized in that: The absorption heat pump circuit (D) includes an absorption heat pump solution circuit (D-1) and an absorption heat pump solvent circuit (D-2).

4. The power plant condensate waste heat recovery and utilization system according to claim 3, characterized in that: The heating network circulating water circuit (A) includes a basic heating network heater (103), an absorber (109) connected to the outside of the basic heating network heater (103), a condenser (107) connected to the outside of the absorber (109), and a peak heating network heater (104) connected to the outside of the condenser (107).

5. The power plant condensate waste heat recovery and utilization system according to claim 4, characterized in that: The low-parameter extraction steam circuit (B) includes a low-parameter extraction steam unit (101), a basic heat network heater (103) connected to the outside of the low-parameter extraction steam unit (101), an evaporator (108) connected to the outside of the basic heat network heater (103), and a condensate collector (105) connected to the outside of the evaporator (108).

6. The power plant condensate waste heat recovery and utilization system according to claim 5, characterized in that: The high-parameter extraction steam first loop (C-1) includes a high-parameter extraction steam unit (102), a generator (106) connected to the outside of the high-parameter extraction steam unit (102), an evaporator (108) connected to the outside of the generator (106), and a condensate collector (105) connected to the outside of the evaporator (108).

7. The power plant condensate waste heat recovery and utilization system according to claim 6, characterized in that: The high-parameter extraction steam second loop (C-2) includes the high-parameter extraction steam unit (102), the peak heat network heater (104) connected to the outside of the high-parameter extraction steam unit (102), the evaporator (108) connected to the outside of the peak heat network heater (104), and the condensate collector (105) connected to the outside of the evaporator (108).

8. The power plant condensate waste heat recovery and utilization system according to claim 7, characterized in that: The absorption heat pump solution circuit (D-1) includes the generator (106), a solution heat exchanger (110) connected to the outside of the generator (106), a solution expansion valve (111) connected to the outside of the solution heat exchanger (110), an absorber (109) connected to the outside of the solution expansion valve (111), and a solution pump (112) connected to the outside of the absorber (109).

9. The power plant condensate waste heat recovery and utilization system according to claim 8, characterized in that: The absorption heat pump solvent circuit (D-2) includes the generator (106), the condenser (107) connected to the outside of the generator (106), the solvent throttling valve (113) connected to the outside of the condenser (107), the evaporator (108) connected to the outside of the solvent throttling valve (113), and the absorber (109) connected to the outside of the evaporator (108).

10. The power plant condensate waste heat recovery and utilization system according to claim 9, characterized in that: The absorber (109) and the solution heat exchanger (110) are connected by two channels. One channel is equipped with the solution expansion valve (111), and the other channel is equipped with the solution pump (112). The solutions flow in opposite directions inside the two channels. The generator (106) and the solution heat exchanger (110) are connected by two channels, and the solutions inside the two channels flow in opposite directions.

Images