Waste heat power generation system of thermal power unit with organic rankine cycle with phase change energy storage

Abstract

The utility model discloses a kind of organic rankine cycle's thermal power generating unit waste heat power generation systems with phase change energy storage, including thermal power generating unit low-temperature waste heat power generation module, phase change heat storage waste heat cascade utilization system, waste water waste heat recovery system, waste gas waste heat recovery system, the thermal power generating unit low-temperature waste heat power generation module includes hot water loop, cold water loop, organic working medium loop and cold source, the hot water loop includes steam generator, the hot side of the steam generator is equipped with hot water inlet and hot water outlet respectively, in this way, phase change heat storage waste heat cascade utilization system is linked with hot water loop by first heat exchange structure, when waste heat is sufficient, high-temperature working medium in hot water loop passes first heat exchange structure and heat is transferred to phase change heat storage tank, is stored by phase change material;When waste heat is insufficient, heat storage tank releases heat, hot water loop working medium is heated by first heat exchange structure, maintain the stable phase change of organic working medium loop, avoid steam turbine shutdown due to working medium parameter imbalance.

Description

Technical Field

[0001] This utility model relates to the field of waste heat power generation systems, and in particular to a waste heat power generation system for thermal power units with organic Rankine cycle phase change energy storage. Background Technology

[0002] The heat loss directly released into the atmosphere during the power generation process of thermal power units accounts for a considerable proportion of primary energy consumption. A large amount of low-temperature, low-grade heat is released in a concentrated manner, resulting in a huge waste of energy resources. In order to maximize the comprehensive energy utilization efficiency of thermal power units, how to rationally recover and utilize the above-mentioned waste heat has become a key technical focus.

[0003] The operating load of thermal power units needs to be adjusted in real time according to the grid dispatch (such as full load operation during peak hours and low load operation during off-peak hours), which causes the waste heat parameters (temperature, flow rate, heat) released by their heating surfaces (such as boiler tail flue, turbine exhaust pipe, etc.) to fluctuate significantly: at full load, the waste heat temperature of the heating surface can reach 150-200℃, the flow rate is stable and the heat is sufficient; at low load or during start-up and shutdown, the waste heat temperature may drop sharply to 80-120℃, the flow rate fluctuates by 30%-50%, and even a short-term waste heat interruption may occur.

[0004] The core components of traditional organic Rankine cycle systems (such as steam generators, turbines, and organic working fluid loops) are mostly fixed designs, and parameters such as working fluid flow rate and heat exchange area cannot be dynamically adjusted according to waste heat fluctuations.

[0005] When the waste heat temperature drops sharply, the organic working fluid cannot undergo a complete phase change (the liquid working fluid is difficult to completely evaporate into a gaseous state), resulting in insufficient input power to the steam turbine, reduced power generation efficiency, and even triggering shutdown protection due to excessively low pressure. When the waste heat flow rate increases sharply, the excess heat cannot be effectively absorbed (the heat exchange capacity of the steam generator is saturated), resulting in the direct discharge of a large amount of high-temperature waste heat and increased heat loss.

[0006] Therefore, a new technical solution needs to be researched to address the above problems. Utility Model Content

[0007] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide a waste heat power generation system for thermal power units with organic Rankine cycle and phase change energy storage. This system utilizes a phase change energy storage waste heat cascade utilization system, which is linked to the hot water loop via a first heat exchange structure. When waste heat is sufficient (e.g., at full unit load), the high-temperature working fluid in the hot water loop transfers heat to the phase change energy storage tank through the first heat exchange structure, where it is stored by a phase change material (e.g., molten salt, paraffin). When waste heat is insufficient (e.g., at low unit load or during start-up / shutdown), the storage tank releases heat, which is then used to heat the working fluid in the hot water loop through the first heat exchange structure, maintaining a stable phase change in the organic working fluid loop. This mitigates waste heat temperature fluctuations and prevents turbine shutdowns due to working fluid parameter imbalances.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An organic Rankine cycle waste heat power generation system for thermal power units with phase change energy storage includes at least one low-temperature waste heat power generation module for thermal power units, with each low-temperature waste heat power generation module connected in series. Each low-temperature waste heat power generation module includes a housing, a hot water loop, a cold water loop, an organic working fluid loop, and a cold source. The hot water loop, the cold water loop, and the organic working fluid loop are all housed within the housing. The hot water loop is connected to the heating surface of the thermal power unit, the cold water loop is connected to the cold source, and the organic working fluid loop is connected to both the hot water loop and the cold water loop. The hot water loop includes a steam generator, with a hot water inlet and a hot water outlet on its hot side, both of which are connected to the heating surface of the thermal power unit.

[0010] It also includes a phase change thermal storage waste heat cascade utilization system, a wastewater waste heat recovery system, and a waste gas waste heat recovery system;

[0011] The phase change thermal storage waste heat cascade utilization system includes a phase change thermal storage tank and a first heat exchange structure. The phase change thermal storage tank is connected to a hot water loop through the first heat exchange structure. The phase change thermal storage tank is equipped with a phase change material. The hot water loop can transfer heat to the phase change thermal storage tank through the first heat exchange structure, or the phase change thermal storage tank can release heat to the hot water loop through the first heat exchange structure.

[0012] The wastewater waste heat recovery system includes a wastewater heat exchanger, the hot side of which is used to introduce wastewater from the thermal power unit, and the cold side of which is connected to the cold water loop.

[0013] The waste heat recovery system includes a waste heat exchanger. The hot side of the waste heat exchanger is used to introduce waste gas from the thermal power unit, and the cold side of the waste heat exchanger is connected to a pipe in the organic working fluid loop near the inlet of the steam generator.

[0014] As a preferred embodiment, the phase change thermal energy storage waste heat cascade utilization system also includes a cascade heat exchange interface for connecting with auxiliary facilities of a thermal power plant. The cascade heat exchange interface is connected to a hot water loop or a phase change thermal energy storage tank, which can directly supply medium and low temperature waste heat (such as below 100℃) to auxiliary facilities of the thermal power plant (such as heating systems and deaerators), realizing the cascade utilization of high temperature waste heat for power generation and medium and low temperature waste heat for heating / auxiliary energy use: avoiding the waste of low-grade waste heat in traditional systems due to low power generation efficiency, and improving the overall energy utilization efficiency.

[0015] As a preferred embodiment, the first heat exchange structure is a coil heat exchanger, one end of which is connected to the pipe before the hot water inlet of the steam generator in the hot water loop, and the other end is connected to the pipe after the hot water outlet of the steam generator in the hot water loop.

[0016] As a preferred embodiment, the phase change material in the phase change heat storage tank includes a high-temperature phase change material and a medium-low temperature phase change material, with the high-temperature phase change material positioned close to the first heat exchange structure.

[0017] As a preferred embodiment, both the wastewater heat exchanger and the waste gas heat exchanger are shell-and-tube heat exchangers.

[0018] As a preferred embodiment, the cold water loop includes a condenser, a cold water inlet disposed on the condenser, and a cold water outlet disposed on the condenser. Both the cold water inlet and the cold water outlet are connected to a cold source, and both the cold water inlet and the cold water outlet are connected to the cold side of the condenser.

[0019] Compared with the prior art, this utility model has significant advantages and beneficial effects. Specifically, as can be seen from the above technical solution, it mainly utilizes the structural design of a phase change thermal storage waste heat cascade utilization system, a wastewater waste heat recovery system, and a waste gas waste heat recovery system. The phase change thermal storage waste heat cascade utilization system is linked to the hot water loop through a first heat exchange structure. When the waste heat is sufficient (such as when the unit is at full load), the high-temperature working fluid in the hot water loop transfers heat to the phase change thermal storage tank through the first heat exchange structure, where it is stored by phase change materials (such as molten salt or paraffin). When the waste heat is insufficient (such as when the unit is at low load or during start-up and shutdown), the thermal storage tank releases heat, which heats the working fluid in the hot water loop through the first heat exchange structure, maintaining a stable phase change in the organic working fluid loop. This mitigates the fluctuation range of waste heat temperature and prevents the turbine from shutting down due to imbalance of working fluid parameters.

[0020] Secondly, the wastewater waste heat recovery system uses a wastewater heat exchanger to transfer the waste heat in the wastewater (such as desulfurization wastewater) of the thermal power unit to the cold water loop. The wastewater releases heat as it flows through the hot side of the heat exchanger, and the working fluid (such as circulating water) in the cold water loop absorbs heat and rises in temperature on the cold side before entering the condenser, reducing the heat load of the condenser and indirectly improving the condensation efficiency of the organic working fluid, thus recovering the waste heat from the wastewater.

[0021] Next, the waste heat recovery system utilizes the waste heat of the flue gas at the tail end of the boiler through a waste heat exchanger. The flue gas flows through the hot side of the heat exchanger and releases heat. The low-temperature working medium in the organic working medium loop before entering the steam generator absorbs heat and preheats on the cold side, increasing its initial temperature when entering the steam generator, increasing the driving force of the organic working medium phase change, and improving the work capacity of the steam turbine.

[0022] To more clearly illustrate the structural features and effects of this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the control flow of an embodiment of the present utility model;

[0024] Figure 2 This is a control block diagram of an embodiment of the present utility model.

[0025] Explanation of reference numerals in the attached diagram:

[0026] 10. Low-temperature waste heat power generation module for thermal power units; 11. Hot water loop.

[0027] 12. Cold water loop 13. Cold source

[0028] 14. Heating surface 15. Steam turbine

[0029] 16. Generator

[0030] 111. Steam generator 1111. Hot water inlet

[0031] 1112. Hot water outlet

[0032] 121. Condenser 1211. Cold water inlet

[0033] 1212, Cold water outlet

[0034] 20. Phase change thermal energy storage waste heat cascade utilization system 21. Phase change thermal energy storage tank

[0035] 22. First heat exchange structure

[0036] 30. Wastewater waste heat recovery system 31. Wastewater heat exchanger

[0037] 40. Waste gas heat recovery system 41. Waste gas heat exchanger. Detailed Implementation

[0038] Please refer to Figures 1 to 2 As shown, it illustrates the specific structure of an embodiment of the present invention.

[0039] In the description of this utility model, it should be noted that the directional terms such as "up", "down", "front", "back", "left", and "right" indicate the orientation and positional relationship based on the accompanying drawings or the orientation or positional relationship shown when wearing and using the device normally. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this utility model.

[0040] An organic Rankine cycle waste heat power generation system for thermal power units with phase change energy storage includes at least one low-temperature waste heat power generation module 10 for thermal power units.

[0041] Each thermal power unit's low-temperature waste heat power generation module 10 is connected in series; each thermal power unit's low-temperature waste heat power generation module 10 includes a housing, a hot water loop 11, a cold water loop 12, an organic working fluid loop, and a cold source 13. The hot water loop 11, the cold water loop 12, and the organic working fluid loop are all located in the housing. The hot water loop 11 is connected to the heating surface 14 of the thermal power unit, the cold water loop 12 is connected to the cold source 13, and the organic working fluid loop is connected to the hot water loop 11 and the cold water loop 12.

[0042] The hot water loop 11 includes a steam generator 111. The hot side of the steam generator 111 is provided with a hot water inlet 1111 and a hot water outlet 1112. Both the hot water inlet 1111 and the hot water outlet 1112 are connected to the heating surface 14 of the thermal power unit.

[0043] Hot water working fluid flows in through hot water inlet 1111, passes through the hot side of steam generator 111, releases heat, and is absorbed by the hot side of steam generator 111, causing the temperature of hot water working fluid to drop. It then flows out through hot water outlet 1112 and returns to the heating surface 14 of the thermal power unit to continue being heated, completing one cycle.

[0044] The organic working fluid loop is the working loop for completing the organic Rankine cycle: the steam turbine 15 is connected to the generator 16 via its main shaft, the cold side of the steam generator 111 is connected to the steam turbine 15, the steam turbine 15 is connected to the hot side of the condenser 121, the hot side of the condenser 121 is connected to the working fluid pump, and the working fluid pump is connected to the cold side of the steam generator 111, forming an organic working fluid loop; due to the presence of the hot water loop 11, the steam generator 111 is heated, and the organic liquid working fluid in the organic working fluid loop flows into the cold side of the steam generator 111, absorbs heat and undergoes a phase change to obtain an organic gaseous working fluid. The organic gaseous working fluid flows into the steam turbine 15 to perform work, thereby driving the generator 16 to generate electricity, completing the conversion of thermal energy into electrical energy; the exhaust steam from the steam turbine 15 flows into the hot side of the condenser 121, releases heat and condenses to obtain an organic liquid working fluid, which flows back to the cold side of the steam generator 111 under the drive of the working fluid pump, completing one organic Rankine cycle.

[0045] Preferably, the cold water loop 12 includes a condenser 121, a cold water inlet 1211 disposed on the condenser 121, and a cold water outlet 1212 disposed on the condenser 121. Both the cold water inlet 1211 and the cold water outlet 1212 are connected to the cold source 13, and both the cold water inlet 1211 and the cold water outlet 1212 are connected to the cold side of the condenser 121.

[0046] The cooling water working fluid flows into the condenser 121 through the cold water inlet 1211. After passing through the cold side of the condenser 121, the cooling water absorbs heat, and the temperature of the condenser 121 decreases, causing the organic gaseous working fluid to condense. The cooling water then flows out through the cold water outlet 1212 and returns to the cold source 13, completing one cycle.

[0047] It also includes a phase change thermal storage waste heat cascade utilization system 20, a wastewater waste heat recovery system 30, and a waste gas waste heat recovery system 40.

[0048] The phase change thermal energy storage waste heat cascade utilization system 20 includes a phase change thermal energy storage tank 21 and a first heat exchange structure 22. The phase change thermal energy storage tank 21 is connected to a hot water loop 11 through the first heat exchange structure 22. The phase change thermal energy storage tank 21 is equipped with a phase change material. The hot water loop 11 can transfer heat to the phase change thermal energy storage tank 21 through the first heat exchange structure 22, or the phase change thermal energy storage tank 21 can release heat to the hot water loop 11 through the first heat exchange structure 22.

[0049] Preferably, the phase change thermal energy storage waste heat cascade utilization system 20 further includes a cascade heat exchange interface for connecting with auxiliary facilities of a thermal power plant. The cascade heat exchange interface is connected to the hot water loop 11 or the phase change thermal energy storage tank 21, which can directly supply medium and low temperature waste heat (such as below 100℃) to auxiliary facilities of the thermal power plant (such as heating system, deaerator), realizing the cascade utilization of high temperature waste heat for power generation and medium and low temperature waste heat for heating / auxiliary energy use: avoiding the waste of low-grade waste heat in traditional systems due to low power generation efficiency, and improving the overall energy utilization efficiency.

[0050] Preferably, the first heat exchange structure 22 is a coil heat exchanger. One end of the coil heat exchanger is connected to the pipe before the hot water inlet 1111 of the steam generator 111 in the hot water loop 11, and the other end is connected to the pipe after the hot water outlet 1112 of the steam generator 111 in the hot water loop 11. This ensures that the heat storage / release process does not interfere with the main flow of the hot water loop 11 and avoids affecting the stable operation of the steam generator 111. In this embodiment, the coil heat exchanger and the shell-and-tube heat exchanger are both heat exchanger structures known in the art.

[0051] Preferably, the phase change material in the phase change storage tank 21 includes a high-temperature phase change material and a medium-low temperature phase change material, with the high-temperature phase change material disposed close to the first heat exchange structure 22. The high-temperature phase change material is disposed at the upper part of the phase change storage tank 21 and close to the first heat exchange structure 22, while the medium-low temperature phase change material is disposed at the lower part of the phase change storage tank 21.

[0052] In this way, the high-temperature section material directly receives the high-temperature waste heat of 150-200℃ transferred by the first heat exchange structure 22, avoiding temperature loss caused by mixing with the medium and low temperature materials, thus improving the heat storage efficiency; the medium and low temperature section material stores the medium and low temperature waste heat of 80-150℃ after heat exchange in the high-temperature section, which matches the energy demand of the auxiliary facilities of the thermal power plant (such as heating requiring 60-80℃), reduces heat exchange loss during cascade utilization, and improves the utilization rate of medium and low temperature waste heat;

[0053] Preferably, the high-temperature section uses a eutectic salt composed of potassium nitrate and sodium nitrate, and the medium-low temperature section uses paraffin wax.

[0054] The wastewater heat recovery system 30 includes a wastewater heat exchanger 31. The hot side of the wastewater heat exchanger 31 is used to introduce wastewater from the thermal power unit, and the cold side of the wastewater heat exchanger 31 is connected to the cold water loop 12. Preferably, both the wastewater heat exchanger 31 and the waste gas heat exchanger 41 are shell-and-tube heat exchangers. The shell-and-tube heat exchanger includes a shell, a tube bundle, a tube sheet, and end caps disposed within the shell. The two ends of the tube bundle are fixed to the tube sheet, and the end caps are sealed to the tube sheet to form a fluid chamber.

[0055] The waste heat recovery system 40 includes a waste heat exchanger 41. The hot side of the waste heat exchanger 41 is used to introduce waste gas from the thermal power unit, and the cold side of the waste heat exchanger 41 is connected to a pipe in the organic working fluid loop near the inlet of the steam generator 111.

[0056] The general working process of each system in this embodiment is described in detail below:

[0057] The phase change thermal energy storage waste heat cascade utilization system 20 has a thermal energy storage mode and a thermal energy release mode, for example:

[0058] Thermal storage mode: When the residual heat of the heating surface 14 of the thermal power unit is sufficient (such as when the unit is operating at high load) and the hot water temperature in the hot water loop 11 is high, some of the heat is transferred to the phase change heat storage tank 21 through the first heat exchange structure 22. The phase change material (such as paraffin, molten salt, etc.) in the tank absorbs the heat and undergoes a phase change (from solid to liquid) to store the heat.

[0059] Heat release mode: When the residual heat of the heating surface 14 of the thermal power unit is insufficient (such as when the unit is operating at low load), the temperature of the hot water loop 11 drops, and the phase change material in the phase change heat storage tank 21 releases heat (from liquid to solid), which is repeatedly supplied to the hot water loop 11 through the first heat exchange structure 22 to ensure a stable heat source for the steam generator 111 and avoid fluctuations in the efficiency of the organic Rankine cycle.

[0060] Wastewater waste heat recovery system 30: Low-temperature wastewater (such as circulating water drainage, condensate, etc.) generated by thermal power units is fed into the hot side of wastewater heat exchanger 31, and cold water from cold water loop 12 flows through the cold side of the heat exchanger. Through heat exchange, the waste heat of the wastewater is absorbed and the originally discarded wastewater waste heat is recovered to cold water loop 12, thereby improving the energy utilization efficiency when cold water enters condenser 121 (indirectly reducing the energy loss in the cooling process of organic working fluid).

[0061] Waste heat recovery system 40: Low-temperature waste gas from the thermal power unit is introduced into the hot side of the waste gas heat exchanger 41. Before entering the steam generator 111, the organic working fluid flows through the cold side of the heat exchanger to absorb the waste heat of the waste gas, preheating the organic working fluid in advance and reducing the heat it needs to absorb in the steam generator 111 (reducing the heat load of the hot water loop 11), thereby improving the heat absorption efficiency of the entire cycle. Through the hot water loop 11 (waste heat from the heating surface 14), the waste gas heat exchanger 41 (waste gas waste heat), and the waste water heat exchanger 31 (waste water waste heat), waste heat from different temperatures and sources is recovered in layers (high-temperature waste heat is given priority to the steam generator 111, and medium and low-temperature waste heat is used for preheating the working fluid or auxiliary heating), maximizing the utilization rate of waste heat.

[0062] Organic Rankine cycle, for example:

[0063] Working fluid preheating: After being pressurized by the working fluid pump, the liquid organic working fluid first enters the waste gas heat exchanger 41 (cold side) to absorb the waste heat of the thermal power unit's waste gas (waste gas to organic working fluid heat transfer), and the temperature rises.

[0064] Working fluid heating: The preheated organic working fluid enters the steam generator 111, absorbs the waste heat of the hot water loop 11 (hot water to organic working fluid heat transfer), and is heated into a high temperature and high pressure gaseous state.

[0065] Power generation: The gaseous working fluid enters the steam turbine, drives its rotation, and drives the generator 16 to generate electricity (mechanical energy is converted into electrical energy).

[0066] Working fluid cooling: The low-pressure gaseous working fluid after doing work enters the condenser 121 and releases heat to the cold water loop 12 (the organic working fluid converts into cold water for heat transfer), condenses into a liquid state, and completes the cycle.

[0067] The key design feature of this invention lies in its structural design of a phase change thermal storage waste heat cascade utilization system, a wastewater waste heat recovery system, and a waste gas waste heat recovery system. The phase change thermal storage waste heat cascade utilization system is linked to the hot water loop through a first heat exchange structure. When waste heat is sufficient (e.g., when the unit is at full load), the high-temperature working fluid in the hot water loop transfers heat to the phase change thermal storage tank through the first heat exchange structure, where it is stored by a phase change material (e.g., molten salt, paraffin). When waste heat is insufficient (e.g., when the unit is at low load or during start-up and shutdown), the thermal storage tank releases heat, which heats the working fluid in the hot water loop through the first heat exchange structure, maintaining a stable phase change in the organic working fluid loop. This mitigates the fluctuations in waste heat temperature and prevents the turbine from shutting down due to imbalances in working fluid parameters.

[0068] Secondly, the wastewater waste heat recovery system uses a wastewater heat exchanger to transfer the waste heat in the wastewater (such as desulfurization wastewater) of the thermal power unit to the cold water loop. The wastewater releases heat as it flows through the hot side of the heat exchanger, and the working fluid (such as circulating water) in the cold water loop absorbs heat and rises in temperature on the cold side before entering the condenser, reducing the heat load of the condenser and indirectly improving the condensation efficiency of the organic working fluid, thus recovering the waste heat from the wastewater.

[0069] Next, the waste heat recovery system utilizes the waste heat of the flue gas at the tail end of the boiler through a waste heat exchanger. The flue gas flows through the hot side of the heat exchanger and releases heat. The low-temperature working medium in the organic working medium loop before entering the steam generator absorbs heat and preheats on the cold side, increasing its initial temperature when entering the steam generator, increasing the driving force of the organic working medium phase change, and improving the work capacity of the steam turbine.

[0070] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A waste heat power generation system for thermal power units with organic Rankine cycle and phase change energy storage, comprising at least one low-temperature waste heat power generation module for thermal power units, wherein the low-temperature waste heat power generation modules of each thermal power unit are connected in series; the low-temperature waste heat power generation module of the thermal power unit comprises a housing, a hot water loop, a cold water loop, an organic working fluid loop, and a cold source, wherein the hot water loop, the cold water loop, and the organic working fluid loop are all disposed in the housing, the hot water loop is connected to the heating surface of the thermal power unit, the cold water loop is connected to the cold source, and the organic working fluid loop is connected to the hot water loop and the cold water loop; The hot water loop includes a steam generator, the hot side of which is provided with a hot water inlet and a hot water outlet, both of which are connected to the heating surface of the thermal power unit; characterized in that: It also includes a phase change thermal storage waste heat cascade utilization system, a wastewater waste heat recovery system, and a waste gas waste heat recovery system; The phase change thermal storage waste heat cascade utilization system includes a phase change thermal storage tank and a first heat exchange structure. The phase change thermal storage tank is connected to a hot water loop through the first heat exchange structure. The phase change thermal storage tank is equipped with a phase change material. The hot water loop can transfer heat to the phase change thermal storage tank through the first heat exchange structure, or the phase change thermal storage tank can release heat to the hot water loop through the first heat exchange structure. The wastewater waste heat recovery system includes a wastewater heat exchanger, the hot side of which is used to introduce wastewater from the thermal power unit, and the cold side of which is connected to the cold water loop. The waste heat recovery system includes a waste heat exchanger. The hot side of the waste heat exchanger is used to introduce waste gas from the thermal power unit, and the cold side of the waste heat exchanger is connected to a pipe in the organic working fluid loop near the inlet of the steam generator.

2. The waste heat power generation system of a thermal power unit with organic Rankine cycle and phase change energy storage as described in claim 1, characterized in that: The phase change thermal energy storage waste heat cascade utilization system also includes a cascade heat exchange interface for connecting with auxiliary facilities of a thermal power plant, and the cascade heat exchange interface is connected to a hot water loop or a phase change thermal energy storage tank.

3. The waste heat power generation system of a thermal power unit with organic Rankine cycle and phase change energy storage as described in claim 1, characterized in that: The first heat exchange structure is a coil heat exchanger. One end of the coil heat exchanger is connected to the pipe before the hot water inlet of the steam generator in the hot water loop, and the other end is connected to the pipe after the hot water outlet of the steam generator in the hot water loop.

4. The waste heat power generation system of a thermal power unit with organic Rankine cycle and phase change energy storage as described in claim 1, characterized in that: The phase change material in the phase change heat storage tank includes a high-temperature phase change material and a medium-low temperature phase change material, with the high-temperature phase change material positioned close to the first heat exchange structure.

5. The waste heat power generation system of a thermal power unit with organic Rankine cycle and phase change energy storage as described in claim 1, characterized in that: Both the wastewater heat exchanger and the waste gas heat exchanger are shell-and-tube heat exchangers.

6. The waste heat power generation system of a thermal power unit with organic Rankine cycle and phase change energy storage as described in claim 1, characterized in that: The cold water loop includes a condenser, a cold water inlet disposed on the condenser, and a cold water outlet disposed on the condenser. Both the cold water inlet and the cold water outlet are connected to a cold source, and both the cold water inlet and the cold water outlet are connected to the cold side of the condenser.

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