Compact supercritical CO2 power cycle power generation system for ship waste heat recovery

Abstract

The invention discloses a compact supercritical CO2 power cycle power generation system for ship waste heat recovery. The compact supercritical CO2 power cycle power generation system comprises a compressor, a power generator, a turbine, a flue gas heat exchanger, a heat regenerator, a cooler and a storage tank. The turbine, the generator and the compressor are sequentially and coaxially designed, the turbine can drive the compressor while directly driving the generator, and the generator runs in a motor mode at the initial stage of system starting so as to synchronously start the turbine and the compressor; supercritical CO2 exhausted by the turbine is sequentially cooled through the heat regenerator and the cooler and then input into the compressor to recover to high pressure, supercritical CO2 output by the compressor sequentially passes through the heat regenerator and the flue gas heat exchanger to be heated and then enters the turbine to do work, circulating cooling water in the ship serves as a cold source of the cooler, and flue gas of a main engine of the ship serves as a heat source of the flue gas heat exchanger. And the storage tank can be used for filling and emergently discharging the working medium, controlling the filling amount of the main cycle working medium in the system and safely recovering the main cycle working medium in the system. The system utilizes waste heat of the ship and can be installed in the ship.

Description

Technical Field

[0001] The present invention relates to ship waste heat recovery and thermal energy power generation, and in particular to a compact supercritical CO2 power cycle power generation system for ship waste heat recovery. Background Art

[0002] When the temperature and pressure of CO2 are both above its critical point (temperature greater than 31.1°C and pressure greater than 7.38 MPa), CO2 enters the supercritical state. The supercritical CO2 power cycle, using supercritical CO2 as the heat transfer medium, optimizes the system's flow and heat transfer processes due to its high density, low viscosity, and high specific heat capacity. The regenerative design and phase-change-free operation significantly reduce the system's irreversible losses, resulting in high thermodynamic efficiency. Furthermore, due to its adaptability to a wide range of heat source temperatures, it has shown broad application prospects in a variety of heat source scenarios.

[0003] Currently, the feasibility of supercritical CO2 power cycles has been demonstrated in terrestrial scenarios through experiments using coal-fired boilers, solar thermal energy, and industrial waste heat as heat sources. However, these applications primarily target large, fixed environments, where system footprint and overall size are not the primary limiting factors. Consequently, relatively little attention has been paid to system compactness and modular design, making it difficult to meet the needs of space-constrained environments.

[0004] Ships are typical space-constrained scenarios. Designing and deploying ship main engine flue gas waste heat recovery systems within limited spaces has become the key to improving energy efficiency, reducing fuel consumption and lowering emissions. Summary of the Invention

[0005] In response to the demand for ship waste heat recovery and the problem of insufficient compactness of existing supercritical CO2 power cycles, the purpose of the present invention is to provide a compact supercritical CO2 power cycle power generation system for ship waste heat recovery. The system effectively utilizes the ship's waste heat, adopts a compact design, and can be installed in ships with limited space.

[0006] The technical solution adopted in the present invention is: A compact supercritical CO2 power cycle power generation system for ship waste heat recovery includes a compressor, a generator, a turbine, a flue gas heat exchanger, a regenerator, a cooler and a storage tank; the turbine, the generator and the compressor are coaxially designed and integrated into an integrated unit, the turbine is used to convert the input medium energy into mechanical energy and directly drive the generator to output electrical power to the outside while driving the compressor to operate. At the initial start-up of the system, the generator runs in motor mode to synchronously start the turbine and compressor; during operation, the medium-temperature, low-pressure supercritical CO2 discharged by the turbine The supercritical CO2 is cooled to low temperature and low pressure through the regenerator and cooler in turn, and then input into the compressor to restore to high pressure. The low temperature and high pressure supercritical CO2 output by the compressor is heated to high temperature and high pressure through the regenerator and flue gas heat exchanger in turn, and then enters the turbine to perform work and is reduced to medium temperature and low pressure. The cooler uses the circulating cooling water in the ship as the cold source, and the flue gas heat exchanger uses the flue gas of the ship's main engine as the heat source; a single storage tank is used, and the storage tank uses supercritical CO2 as the working fluid and can be filled and discharged in an emergency, control the filling amount of the main circulation working fluid in the system, and safely recover the main circulation working fluid in the system.

[0007] Preferably, manual valves for operation during maintenance are provided on the pipelines between adjacent devices in the system.

[0008] Preferably, a control valve 1 is provided on the pipeline between the compressor inlet and the cooler, and the control valve 1 is used to adjust the compressor inlet pressure to avoid overpressure on the compressor inlet side; a control valve 2 is provided on the pipeline between the compressor outlet and the regenerator, and the control valve 2 is used to adjust the compressor back pressure to quickly establish the system pressure difference at the initial stage of system startup; a control valve 3 is provided on the pipeline between the turbine inlet and the flue gas heat exchanger, and the control valve 3 is used to quickly adjust the turbine output power to avoid the shaft speed soaring phenomenon; the turbine is connected in parallel with a bypass pipeline and a control valve 4 is provided on the bypass pipeline, and the control valve 4 is used to adjust the operating flow of the turbine.

[0009] Preferably, the storage tank is provided with a working fluid input interface, a working fluid output interface, a working fluid safety recovery interface, and a working fluid filling and emergency discharge interface; the working fluid input interface is connected to the compressor outlet and a control valve five is provided on the connecting pipe, and the control valve five is used to reduce the filling amount of the main circulation working fluid in the system; the working fluid output interface is connected to the compressor inlet and a control valve six is provided on the connecting pipe, and the control valve six is used to increase the filling amount of the main circulation working fluid in the system; the working fluid safety recovery interface is connected to the pipe between the compressor outlet and the regenerator and a control valve seven is provided on the connecting pipe, and the control valve seven is used to safely recover the working fluid in the main circulation of the system into the storage tank; the filling and emergency discharge interface is connected to the parallel filling pipe and the emergency discharge pipe, and a control valve eight is provided on the filling pipe, and the control valve eight fills the working fluid into the storage tank, and a control valve nine is provided on the emergency discharge pipe, and the control valve nine is used to emergency discharge the working fluid in the storage tank.

[0010] Preferably, all control valves are air-controlled shut-off valves.

[0011] Preferably, the middle of the storage tank is a cylindrical cylinder and the two ends are arc-shaped heads; the working fluid safety recovery interface is arranged at the top of the upper head, the working fluid filling and emergency discharge interface is arranged at the bottom of the lower head, the working fluid input interface is arranged at the lower part of one side of the cylinder, and the working fluid output interface is arranged at the upper part of the other side of the cylinder. The working fluid safety recovery interface, working fluid filling and emergency discharge interface, working fluid input interface, and working fluid output interface all adopt a forged pipe and flange installation structure; the upper head is provided with a safety valve interface for installing a safety valve and a pressure sensor interface for installing a pressure sensor, and the cylinder is provided with a temperature sensor interface for installing a temperature sensor. The safety valve interface, pressure sensor interface, and temperature sensor interface all adopt an internal thread interface installation structure.

[0012] Preferably, the turbine and the compressor adopt a back-to-back radial impeller design, and the generator adopts a high-speed permanent magnet synchronous motor design.

[0013] Preferably, the cold side flow channel and hot side flow channel of the cooler and regenerator both adopt a printed circuit board structure; the cold side flow channel of the flue gas heat exchanger adopts a printed circuit board structure, and the hot side flow channel adopts a fin structure, and two flue gas heat exchangers are connected in parallel.

[0014] Preferably, the generator outputs electric power through a bidirectional frequency converter. The bidirectional frequency converter can convert the input machine-side AC power into AC power that meets the requirements in terms of frequency, voltage and phase, and then transmit it to the grid side. The system adopts a system variable operating condition control strategy based on shaft speed control. Under the active regulation of the shaft speed, the operating pressure ratio and isentropic efficiency of the turbine and compressor change rapidly, synchronously affecting the operating flow and pressure of the system, thereby effectively controlling the operating conditions of the system.

[0015] Preferably, the compressor, generator, turbine, regenerator, cooler and storage tank, as well as the pipes and valves between the equipment are skid-mounted together, and the flue gas heat exchanger and electrical equipment are set separately; the integrated unit of the turbine, generator and compressor and the manual valve are set on the first skid level, and the regenerator, cooler and storage tank are set on the second skid level; the pipeline adopts a bent or U-shaped design along the way.

[0016] The beneficial effects of the present invention are: After the storage tank is filled with CO2, at the initial stage of system startup, the generator runs in motor mode to synchronously start the turbine and compressor. Then, as the heat input from the heat source continues to increase, and the storage tank control system adjusts the main cycle working fluid to reach the appropriate filling amount, the turbine shaft power continues to increase until it exceeds the power consumption of the compressor. The generator switches to power generation mode, and then the system is fully started and circulated. The low-temperature, high-pressure supercritical CO2 output by the compressor first passes through the regenerator to be preheated by the medium-temperature, low-pressure supercritical CO2 discharged by the turbine, and then passes through the flue gas heat exchanger to exchange heat with the flue gas of the ship's main engine. The temperature is increased twice to become high-temperature, high-pressure supercritical CO2, and then enters the turbine to perform work. The turbine will output The input heat energy is converted into mechanical energy and drives the compressor to operate while directly driving the generator to output electrical power to the outside. After working, the temperature and pressure of the supercritical CO2 are reduced to become medium-temperature, low-pressure supercritical CO2. The medium-temperature, low-pressure supercritical CO2 discharged from the turbine first passes through the regenerator to preheat the low-temperature, high-pressure supercritical CO2 output by the compressor, and then passes through the cooler to exchange heat with the circulating cooling water in the ship. After two coolings, it becomes low-temperature, low-pressure supercritical CO2, and then enters the compressor to restore to high pressure. During the circulation operation, the storage tank adjusts the filling amount of the main circulation working fluid as needed, safely recovers the main circulation working fluid in the system in emergency situations such as system overpressure, and discharges the working fluid in the storage tank in an emergency. The system effectively utilizes the waste heat of the ship, and in order to be installed in a space-constrained ship, it adopts a compact design guided by the optimization of occupied space: it is designed based on a regenerative supercritical CO2 power cycle, with low system complexity, which means reduced space occupancy; the motor that drives the compressor is eliminated, which improves the integration of rotating machinery, which means reduced space occupancy; similar systems usually require three storage tanks (inventory control tank, filling tank and safety recovery tank), and this system uses a single storage tank to reduce the overall volume while ensuring functionality, which means reduced space occupancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a schematic diagram of the compact supercritical CO2 power cycle power generation system for ship waste heat recovery in the present invention.

[0019] Figure 2 It is a structural schematic diagram of the storage tank in the present invention.

[0020] Figure 3 It is a structural schematic diagram of the integrated unit of turbine, generator and compressor in the present invention.

[0021] Figure 4 It is a schematic diagram of each heat exchange device in the present invention.

[0022] Figure 5 It is a skid-mounted schematic diagram of a compact supercritical CO2 power cycle power generation system for ship waste heat recovery in the present invention.

[0023] In the picture: A-compressor; B-generator; C-turbine; D-flue gas heat exchanger; E-regenerator; F-cooler; G-storage tank; 1-Control valve 1; 2-Control valve 2; 3-Control valve 3; 4-Control valve 4; 5-Control valve 5; 6-Control valve 6; 7-Control valve 7; 8-Control valve 8; 9-Control valve 9; 10-Flange; 11-Forged pipe; 12-End; 13-Cylinder; 14-Nameplate; 15-Support; 16-Internal thread interface; a-working fluid safety recovery interface; b-safety valve interface; c-pressure sensor interface; d1-working fluid output interface; d2-working fluid input interface; e-working fluid filling and emergency discharge interface; f-temperature sensor interface; g-spare interface; ①- Skid-mounted equipment on the first floor; ②- Skid-mounted equipment on the second floor. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0027] In addition, the terms "control valve one", "control valve two", ..., "control valve nine", etc. are only used to distinguish the descriptions and should not be understood as indicating or implying relative importance.

[0028] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0029] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0030] Example 1 This embodiment discloses a compact supercritical CO2 power cycle power generation system for ship waste heat recovery, such as Figure 1 As shown, it includes compressor A, generator B, turbine C, flue gas heat exchanger D, regenerator E, cooler F and storage tank G; among them, Figure 1 and Figure 3 As shown, the turbine C, generator B and compressor A are coaxially designed and integrated into an integrated unit. The turbine C is used to convert the input medium energy into mechanical energy and drive the compressor A to operate while directly driving the generator B to output electrical power. At the initial start-up of the system, the generator B operates in motor mode to synchronously start the turbine C and compressor A. During operation, the medium-temperature, low-pressure supercritical CO2 discharged from the turbine C passes through the regenerator E and the cooler F in turn to be cooled to low temperature and low pressure, and then is input into the compressor A to restore to high pressure. The low-temperature, high-pressure supercritical CO2 output by the compressor A passes through the regenerator E and the flue gas heat exchanger D in turn to be heated to high temperature and high pressure, and then enters the turbine C to perform work and is reduced to medium temperature and low pressure. The cooler F uses the circulating cooling water in the ship as the cold source, and the flue gas heat exchanger D uses the flue gas of the ship's main engine as the heat source. Figure 1 As shown, a single storage tank G is used. The storage tank G uses supercritical CO2 as the working fluid and can be filled and discharged in an emergency, control the filling amount of the main circulation working fluid in the system, and safely recover the main circulation working fluid in the system.

[0031] The working process of the above system is as follows: after the storage tank G is filled with CO2, at the initial stage of system startup, the generator B operates in motor mode to synchronously start the turbine C and compressor A. As the heat input from the heat source continues to increase, and the control system of the storage tank G synchronously regulates the main cycle working fluid to reach the appropriate filling amount, the shaft power of the turbine C continues to increase until it exceeds the power consumption of the compressor A. The generator B switches to the power generation mode, and then the system is fully started and circulated. The low-temperature and high-pressure supercritical CO2 output by the compressor A first passes through the regenerator E to be preheated by the medium-temperature and low-pressure supercritical CO2 discharged by the turbine C, and then passes through the flue gas heat exchanger D to exchange heat with the flue gas of the ship's main engine. After two heatings, it becomes high-temperature and high-pressure supercritical CO2, and then enters the turbine C to perform work. C converts the input thermal energy into mechanical energy and drives the compressor A to operate while directly driving the generator B to output electrical work to the outside. After working, the temperature and pressure of the supercritical CO2 are reduced to become medium-temperature, low-pressure supercritical CO2. The medium-temperature, low-pressure supercritical CO2 discharged from the turbine C first passes through the regenerator E to preheat the low-temperature, high-pressure supercritical CO2 output by the compressor A, and then passes through the cooler F to exchange heat with the circulating cooling water in the ship. After two coolings, it becomes low-temperature, low-pressure supercritical CO2, and then enters the compressor A to restore to high pressure, and the cycle is repeated. During the cycle operation, the storage tank G can adjust the filling amount of the main cycle working fluid as needed, safely recover the main cycle working fluid in the system in emergency situations such as system overpressure, and discharge the working fluid in the storage tank G in an emergency.

[0032] The system effectively utilizes the waste heat of the ship, and in order to be installed in a space-constrained ship, it adopts a compact design guided by the optimization of occupied space: it is designed based on a regenerative supercritical CO2 power cycle, with low system complexity, which means reduced space occupancy; the motor that drives the compressor A is eliminated, which improves the integration of rotating machinery, which means reduced space occupancy; similar systems usually require three storage tanks (inventory control tank, filling tank and safety recovery tank), and this system uses a single storage tank G to reduce the overall volume while ensuring functionality, which means reduced space occupancy.

[0033] In this embodiment, preferably: manual valves for maintenance operations are provided on the pipelines between adjacent devices in the system. When maintenance is required, the manual valves upstream and downstream of the corresponding devices can be disconnected in the shutdown state to carry out maintenance.

[0034] In this embodiment, preferably: Figure 1As shown, a control valve 1 is installed on the pipeline between the inlet of compressor A and cooler F. This valve regulates the inlet pressure of compressor A to prevent overpressure on the inlet side of compressor A. A control valve 2 is installed on the pipeline between the outlet of compressor A and regenerator E. This valve regulates the back pressure of compressor A to quickly establish a system pressure differential during initial system startup. A control valve 3 is installed on the pipeline between the inlet of turbine C and flue gas heat exchanger D. This valve quickly regulates the output power of turbine C to prevent shaft speed spikes. A bypass pipeline is connected in parallel to turbine C, and this bypass pipeline is equipped with a control valve 4, which regulates the operating flow of turbine C. Control valves 1 through 4 are distributed in the main working fluid circulation pipeline, regulating the operating conditions of compressor A and turbine C, ensuring rapid system startup and stable operation. Control valves 1 through 4 can be pneumatically controlled shut-off valves for rapid on / off switching.

[0035] In this embodiment, preferably: Figure 1As shown, the storage tank G is provided with a working fluid input interface d2, a working fluid output interface d1, a working fluid safety recovery interface a, and a working fluid filling and emergency discharge interface e; the working fluid input interface d2 is connected to the outlet of the compressor A and a control valve five 5 is provided on the connecting pipeline, and the control valve five 5 is used to reduce the filling amount of the main circulation working fluid in the system; the working fluid output interface d1 is connected to the inlet of the compressor a and a control valve six 6 is provided on the connecting pipeline, and the control valve six 6 is used to increase the filling amount of the main circulation working fluid in the system; the working fluid safety recovery interface a is connected to the pipeline between the outlet of the compressor A and the regenerator E and a control valve seven 7 is provided on the connecting pipeline, and the control valve seven 7 is used to safely recover the working fluid in the main circulation of the system to the storage tank G; the filling and emergency discharge interface e is connected to the parallel filling pipeline and the emergency discharge pipeline, and a control valve eight 8 is provided on the filling pipeline, and the control valve eight 8 fills the working fluid into the storage tank G. The emergency discharge pipeline is provided with a control valve nine 9, and the control valve nine 9 is used to emergency discharge the working fluid in the storage tank G. Control valves five 5 to nine 9 are distributed on the connecting pipelines of the storage tank G, and cooperate with the various interfaces on the storage tank G to enable a single storage tank G to be used as an inventory control tank, a filling tank and a safety recovery tank at the same time; when used as an inventory control tank, the control valve five 5 and the control valve six 6 are opened, and the working fluid input interface d2 and the working fluid output interface d1 are connected to the outlet end of the compressor A and the inlet end of the compressor A respectively, and the high and low pressure differential of the system is used to realize the working fluid flow in and out between the working fluid in the storage tank G and the main circulation of the system, thereby regulating the filling amount of the working fluid in the main circulation; When used as a filling tank, when refrigerant needs to be added during initial operation or replenished during operation, control valve 8 opens, connecting the filling pipeline to tank G, allowing refrigerant to be added to tank G. In an emergency, during cold shutdown, control valve 9 opens, connecting the emergency discharge pipeline to tank G, allowing the refrigerant in tank G to be discharged. When used as a safety recovery tank, control valve 7 opens, bypassing the pipeline between the compressor A outlet and the regenerator E to tank G, allowing the refrigerant in the main circulation to be discharged to tank G. Control valves 55 through 99 can be pneumatically controlled shutoff valves for rapid on / off switching.

[0036] In this embodiment, preferably: Figure 2As shown, the middle of the storage tank G is a cylindrical barrel 13, and the two ends are arc-shaped heads 12; the working fluid safety recovery interface a is provided at the top of the upper head 12, the working fluid filling and emergency discharge interface e is provided at the bottom of the lower head 12, the working fluid input interface d2 is provided at the lower part of one side of the barrel 13, and the working fluid output interface d1 is provided at the upper part of the other side of the barrel 13. The working fluid safety recovery interface a, the working fluid filling and emergency discharge interface e, the working fluid input interface d2, and the working fluid output interface d1 all adopt the installation structure of the forged pipe 11 and the flange 10; the upper head 12 is provided with a safety valve interface b for installing a safety valve and a pressure sensor interface c for installing a pressure sensor, and the barrel 13 is provided with a temperature sensor interface f for installing a temperature sensor, and the safety valve interface b, the pressure sensor interface c, and the temperature sensor interface f all adopt the installation structure of the internal thread interface 16. The storage tank G adopts a combination of a cylinder 13 and a head 12, which is simple to process and avoids internal stress concentration; the working fluid safety recovery interface a and the working fluid filling and emergency discharge interface e are located at the top and bottom respectively, which can quickly and safely recover the working fluid and discharge the working fluid in an emergency. The working fluid input interface d2 and the working fluid output interface d1 are located at the lower and upper parts of both sides of the cylinder 13 respectively, making inventory control more stable; the working fluid-related interfaces adopt the installation structure of forged pipes 11 and flanges 10, which have strong bearing capacity and are convenient for external piping. The remaining interfaces adopt the installation structure of internal threaded interfaces 16, which is convenient for installing attachments on the storage tank G; a safety valve and a pressure sensor are installed on the upper head 12, which can display a more accurate internal pressure and automatically relieve pressure when the internal pressure is over-pressured. A temperature sensor is installed on the cylinder 13 to obtain a more accurate internal temperature. In addition, a nameplate 14 can be set on the cylinder 13 to facilitate on-site identification and understanding of the main parameters. Supports 15 can be provided on both sides of the cylinder 13 to facilitate the installation and fixation of the storage tank G. A spare interface g can be set on the cylinder 13 to facilitate external connection of other attachments. The spare interface g can also adopt an installation structure of an internal threaded interface 16.

[0037] In this embodiment, preferably: Figure 3 As shown, turbine C and compressor A adopt back-to-back radial impeller design, compressor A has axial air intake and radial air exhaust, turbine C has radial air intake and axial air exhaust, and generator B adopts high-speed permanent magnet synchronous motor design, and generator B can switch between motor mode and power generation mode.

[0038] In this embodiment, preferably: Figure 4As shown, the cold-side and hot-side flow channels of cooler F and regenerator E both adopt a printed circuit board structure. The flue gas heat exchanger's cold-side flow channel adopts a printed circuit board structure, while the hot-side flow channel adopts a fin structure. Two flue gas heat exchangers D are connected in parallel. Cooler F, regenerator E, and flue gas heat exchanger D all feature compact microchannels, making the equipment more compact and reducing space usage. Furthermore, to prevent impurities in the flue gas from clogging the heat exchange flow channel and reducing equipment life, the hot-side flow channel (flue gas side flow channel) of flue gas heat exchanger D adopts a fin structure to ensure a sufficient flue gas flow path. Furthermore, the parallel connection of the two flue gas heat exchangers D makes the equipment layout more flexible, shortens the flue gas flow path, increases the flue gas flow path, and further prevents flue gas blockage.

[0039] Example 2 This embodiment discloses another compact supercritical CO2 power cycle power generation system for ship waste heat recovery, which adopts a different system variable operating condition control strategy: generator B outputs electric power to the outside through a bidirectional variable frequency converter. The bidirectional variable frequency converter can convert the input machine-side AC power into AC power that meets the requirements in frequency, voltage and phase and then transmit it to the grid side. The system adopts a system variable operating condition control strategy based on shaft speed control. Under the active regulation of the shaft speed, the operating pressure ratio and isentropic efficiency of the turbine C and compressor A both change rapidly, synchronously affecting the operating flow and pressure of the system, thereby effectively controlling the operating condition of the system. The bidirectional variable frequency converter can stabilize the grid-side frequency while actively controlling the machine-side frequency. Therefore, this system has the ability to regulate the shaft speed. Compared with the control strategy based on valves, the shaft speed control scheme has the characteristic of no additional pressure drop, which can improve the operating efficiency of the system under non-design conditions. Compared with the working fluid filling quantity control strategy based on tank G, the shaft speed control scheme has the additional characteristics of fast response speed and good maneuverability. Therefore, the control strategy of this system improves the system's variable load response speed and adaptability to different working conditions, and reduces the number of control valves required by the system, ensuring the low complexity of the control system.

[0040] Example 3 This embodiment discloses a third compact supercritical CO2 power cycle power generation system for ship waste heat recovery, which adds a skid-mounted structure based on the first embodiment. Figure 5As shown: compressor A, generator B, turbine C, regenerator E, cooler F and storage tank G, as well as the pipelines and valves between the equipment are skid-mounted together, while flue gas heat exchanger D and electrical equipment are separately installed; the integrated unit of turbine C, generator B and compressor A, as well as the manual valves are installed on the first skid level, while the regenerator E, cooler F and storage tank G are installed on the second skid level; the pipelines are designed with bends or U-shapes along the way. The system adopts a double-layer skid-mounted structure and optimizes the layout of pipelines and valves, which improves the overall compactness of the system and adaptability to the cabin space: all components except the flue gas heat exchanger D and electrical equipment are integrated into a skid-mounted design, which is convenient for moving the entire system to a container ship after land-based commissioning. This ensures efficient commissioning and maintenance of the system while facilitating lifting and movement between land and ship; the integrated unit of turbine C, generator B and compressor A and manual valves are installed on the first skid-mounted floor for easy operation and maintenance; the regenerator E, cooler F and storage tank G are installed on the second skid-mounted floor, which rationally utilizes the second-floor space and reduces the overall skid-mounted area; the pipeline adopts a bend or U-shaped design along the line to avoid long sections of pipelines. The pipeline's own deformation can be used to overcome thermal deformation, reduce the number of expansion joints, and minimize pipeline length.

[0041] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A compact supercritical CO2 power cycle power generation system for ship waste heat recovery, characterized by: It includes a compressor, generator, turbine, flue gas heat exchanger, regenerator, cooler and storage tank; the turbine, generator and compressor are coaxially designed and integrated into an integrated unit. The turbine is used to convert the input medium energy into mechanical energy and drive the compressor while directly driving the generator to output electrical power. At the initial start-up of the system, the generator operates in motor mode to synchronously start the turbine and compressor; during operation, the medium-temperature, low-pressure supercritical CO2 discharged by the turbine is cooled to low temperature and low pressure through the regenerator and cooler in turn, and then input into the compressor to restore it to high pressure. The low-temperature, high-pressure supercritical CO2 output by the compressor is heated to high temperature and high pressure through the regenerator and flue gas heat exchanger in turn, and then enters the turbine to perform work and is reduced to medium temperature and low pressure. The cooler uses the circulating cooling water in the ship as the cold source, and the flue gas heat exchanger uses the flue gas of the ship's main engine as the heat source; a single storage tank is used, which uses supercritical CO2 as the working fluid and can be filled with and discharge the working fluid in an emergency, control the filling amount of the main circulation working fluid in the system, and safely recover the working fluid in the main circulation system.

2. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 1, characterized in that: Manual valves are installed on the pipes between adjacent equipment in the system for maintenance operations.

3. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 1, characterized in that: A control valve 1 is provided on the pipe between the compressor inlet and the cooler, and is used to adjust the compressor inlet pressure to avoid overpressure on the compressor inlet side; a control valve 2 is provided on the pipe between the compressor outlet and the regenerator, and is used to adjust the compressor back pressure to quickly establish the system pressure difference at the initial stage of system startup; a control valve 3 is provided on the pipe between the turbine inlet and the flue gas heat exchanger, and is used to quickly adjust the turbine output power to avoid the phenomenon of rapid increase in shaft speed; a bypass pipe is connected in parallel to the turbine and a control valve 4 is provided on the bypass pipe, and is used to adjust the operating flow of the turbine.

4. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 1 is characterized in that: The storage tank is provided with a working fluid input interface, a working fluid output interface, a working fluid safety recovery interface, and a working fluid filling and emergency discharge interface; the working fluid input interface is connected to the compressor outlet and a control valve five is provided on the connecting pipe, and the control valve five is used to reduce the filling amount of the main circulation working fluid in the system; the working fluid output interface is connected to the compressor inlet and a control valve six is provided on the connecting pipe, and the control valve six is used to increase the filling amount of the main circulation working fluid in the system; the working fluid safety recovery interface is connected to the pipe between the compressor outlet and the regenerator and a control valve seven is provided on the connecting pipe, and the control valve seven is used to safely recover the working fluid in the main circulation of the system into the storage tank; the filling and emergency discharge interface is connected to the parallel filling pipe and the emergency discharge pipe, and a control valve eight is provided on the filling pipe, and the control valve eight fills the working fluid into the storage tank, and a control valve nine is provided on the emergency discharge pipe, and the control valve nine is used to emergency discharge the working fluid in the storage tank.

5. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 3 or 4, characterized in that: All control valves are air-operated shut-off valves.

6. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 4, characterized in that: The middle of the storage tank is a cylindrical cylinder, and both ends are arc-shaped heads; the working fluid safety recovery interface is located at the top of the upper head, the working fluid filling and emergency discharge interface is located at the bottom of the lower head, the working fluid input interface is located at the lower part of one side of the cylinder, and the working fluid output interface is located at the upper part of the other side of the cylinder. The working fluid safety recovery interface, working fluid filling and emergency discharge interface, working fluid input interface, and working fluid output interface all adopt a forged pipe and flange installation structure; the upper head is provided with a safety valve interface for installing a safety valve and a pressure sensor interface for installing a pressure sensor, and the cylinder is provided with a temperature sensor interface for installing a temperature sensor. The safety valve interface, pressure sensor interface, and temperature sensor interface all adopt an internal thread interface installation structure.

7. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 1, characterized in that: The turbine and compressor adopt back-to-back radial impeller design, and the generator adopts high-speed permanent magnet synchronous motor design.

8. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 1, characterized in that: The cold side flow channel and hot side flow channel of the cooler and regenerator both adopt a printed circuit board structure; the cold side flow channel of the flue gas heat exchanger adopts a printed circuit board structure, and the hot side flow channel adopts a fin structure, and two flue gas heat exchangers are connected in parallel.

9. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 1, characterized in that: The generator outputs electric power through a bidirectional variable frequency converter. The bidirectional variable frequency converter can convert the input machine-side AC power into AC power that meets the requirements in terms of frequency, voltage and phase, and then transmit it to the grid side. The system adopts a system variable operating condition control strategy based on shaft speed control. Under the active regulation of the shaft speed, the operating pressure ratio and isentropic efficiency of the turbine and compressor change rapidly, synchronously affecting the operating flow and pressure of the system, thereby effectively controlling the operating conditions of the system.

10. The compact supercritical CO2 power cycle power generation system for ship waste heat recovery according to claim 1, characterized in that: The compressor, generator, turbine, regenerator, cooler and storage tank, as well as the pipes and valves between the equipment are skid-mounted together, while the flue gas heat exchanger and electrical equipment are set up separately; the integrated unit of turbine, generator and compressor and the manual valve are installed on the first skid level, and the regenerator, cooler and storage tank are installed on the second skid level; the pipeline adopts a bent or U-shaped design along the way.

Images