Supercritical carbon dioxide power cycle working fluid pressure regulation system

Abstract

The application provides a supercritical carbon dioxide power generation working medium pressure regulating system, and belongs to the technical field of working medium pressure regulation of power generation systems, and can at least partially solve the problems that in the existing unit start-stop and load regulation process, the system pressure will change greatly, the normal operation of the unit is affected, and there is no structure or system for controlling and regulating the pressure change, and the application comprises: a power generation module, the power generation module comprises a compressor and a regenerator connected with the compressor pipeline; and a gas storage buffer module, the application is provided with a gas storage tank, a part of carbon dioxide working medium is stored in the gas storage tank by using the differential pressure of the high and low pressure parts of the circulating system, the working quality of the circulating system is regulated, and the application has the characteristics of simple system and convenient operation.

Description

Technical Field

[0001] This invention belongs to the field of working fluid pressure regulation technology for power generation systems, and specifically relates to a supercritical carbon dioxide power generation working fluid pressure regulation system. Background Technology

[0002] Supercritical carbon dioxide cycle power generation systems are currently the most promising thermal power generation cycle systems, possessing advantages such as high efficiency and system simplicity. The supercritical carbon dioxide cycle is a closed-loop system without phase change; therefore, the pressure of the working fluid within the system is determined by the amount of working fluid charged and the operating temperature of each part of the system.

[0003] However, during the start-up, shutdown, and load regulation processes of the unit, the system pressure will change significantly, affecting the normal operation of the unit. Existing technologies lack structures or systems for controlling and regulating this pressure change. Therefore, we propose a supercritical carbon dioxide power generation working fluid pressure regulation system. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a supercritical carbon dioxide power generation working fluid pressure regulation system.

[0005] This invention provides a supercritical carbon dioxide power generation working fluid pressure regulation system, comprising:

[0006] A power generation module, comprising a compressor and a regenerator connected to the compressor via piping; and

[0007] A gas storage buffer module includes a gas storage tank connected to a venting pipeline and a filling pipeline. The venting pipeline is connected to the compressor to deliver carbon dioxide working fluid from the compressor to the gas storage tank during operation. The filling pipeline is connected to the hot-side outlet of the regenerator to deliver carbon dioxide working fluid from the gas storage tank to the hot-side outlet of the regenerator during operation.

[0008] Furthermore, the supercritical carbon dioxide power generation working fluid pressure regulation system also includes a gas replenishment module, which includes a heater connected to the gas storage tank pipeline, a delivery pump connected to the heater pipeline, and a liquid carbon dioxide storage tank connected to the delivery pump pipeline.

[0009] Specifically, the heater is an electric heater.

[0010] Specifically, the liquid carbon dioxide storage tank is an ambient temperature pressure storage tank equipped with a level gauge.

[0011] Preferably, the delivery pump is either a plunger pump or a centrifugal pump.

[0012] Specifically, the gas storage tank is a steel tank with an insulation layer on the outside, and a pressure gauge is installed inside the gas storage tank.

[0013] Furthermore, the power generation module also includes a turbine connected to the compressor pipeline, and a generator is connected to the turbine.

[0014] Furthermore, the hot-side outlet of the regenerator is connected to the cooler pipeline, and the cold-side outlet of the regenerator is connected to the heat exchanger pipeline.

[0015] Furthermore, the hot-side outlet of the heat exchanger is connected to the turbine piping, and the cooler is connected to the compressor piping.

[0016] Specifically, the discharge pipeline is equipped with a discharge regulating valve, and the opening degree of the discharge regulating valve is controlled by the estimated total amount of working fluid of the power generation module during operation. The filling pipeline is equipped with a filling regulating valve, and the opening degree of the filling regulating valve is controlled by the load increase command of the power generation module, the hot side outlet pressure of the regenerator, and the pressure of the gas storage tank during operation.

[0017] The beneficial effects of this invention are as follows:

[0018] This pressure regulation system is equipped with a gas storage tank. By utilizing the pressure difference between the high and low pressure sections of the circulation system, a portion of the carbon dioxide working fluid is stored in the gas storage tank, thereby achieving the regulation of the working fluid in the circulation system. It features a simple system and convenient operation. Attached Figure Description

[0019] Figure 1 This is a connection diagram of a supercritical carbon dioxide power generation working fluid pressure regulation system according to a specific embodiment of the present invention.

[0020] The system includes: 1. Gas storage tank; 2. Liquid carbon dioxide storage tank; 3. Transfer pump; 4. Heater; 5. Relief regulating valve; and 6. Filling regulating valve. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown in the figure, a supercritical carbon dioxide power generation working fluid pressure regulation system provided by a specific embodiment of the present invention includes:

[0023] The power generation module includes a compressor and a regenerator connected to the compressor via piping; and a gas storage buffer module includes a gas storage tank 1, which is connected to a venting pipe and a filling pipe. The venting pipe is connected to the compressor to deliver carbon dioxide working fluid from the compressor to the gas storage tank 1 during operation, and the filling pipe is connected to the hot-side outlet of the regenerator to deliver carbon dioxide working fluid from the gas storage tank 1 to the hot-side outlet of the regenerator during operation.

[0024] Specifically, the gas storage buffer module is used to regulate the working fluid inventory and pressure in the supercritical carbon dioxide power generation circuit; it achieves pressure and quality stabilization by charging the main circuit or collecting carbon dioxide from the main circuit, improves the system's load-carrying capacity, and provides buffering and recovery during start-up, shutdown, and abnormalities.

[0025] Furthermore, during load increase, the gas storage buffer module opens the filling valve according to the load increase command, the hot side outlet pressure of the regenerator, and the pressure of the gas storage tank 1, injecting the working fluid in the gas storage tank 1 into the circuit to quickly increase the average pressure and mass flow. During load reduction or standby, the gas storage buffer module opens the relief valve according to the estimated total amount of working fluid, introducing the working fluid from the compressor side into the gas storage tank 1 to reduce the system pressure and avoid triggering the safety valve.

[0026] Furthermore, during cold or hot startup, the gas storage buffer module is filled in stages to ensure the system reaches the target pressure smoothly; in the event of a shutdown or abnormal overpressure, the gas storage buffer module quickly collects the working fluid into the gas storage tank 1, reducing external discharge and cooperating with cooling to reduce pressure.

[0027] Based on the above basic implementation method, the supercritical carbon dioxide power generation working fluid pressure regulation system also includes a gas replenishment module. The gas replenishment module includes a heater 4 connected to the gas storage tank 1 via a pipeline, a delivery pump 3 connected to the heater 4 via a pipeline, and a liquid carbon dioxide storage tank 2 connected to the delivery pump 3 via a pipeline.

[0028] Specifically, the gas replenishment module uses liquid carbon dioxide as a source, and maintains a reasonable pressure and temperature in the gas storage tank by pressurizing it with a delivery pump and heating it with a heater, thus compensating for losses.

[0029] In one specific embodiment, heater 4 is an electric heater; liquid carbon dioxide storage tank 2 is a normal temperature pressure storage tank equipped with a level gauge; and transfer pump 3 is either a plunger pump or a centrifugal pump.

[0030] In this embodiment, the gas storage tank 1 is a steel storage tank with an insulation layer on the outside, and a pressure gauge is installed inside the gas storage tank 1.

[0031] Furthermore, the gas storage tank 1 adopts an insulated steel structure and is equipped with pressure monitoring for easy control and interlocking; the pump type of the delivery pump 3 can be selected according to the working conditions, with the plunger pump suitable for high pressure, low flow and accurate metering, and the centrifugal pump suitable for large flow and stable delivery.

[0032] In another specific embodiment, the power generation module further includes a turbine connected to the compressor pipeline, and a generator connected to the turbine; the hot-side outlet of the regenerator is connected to the cooler pipeline, and the cold-side outlet of the regenerator is connected to the heat exchanger pipeline.

[0033] Specifically, the hot-side outlet of the heat exchanger is connected to the turbine pipeline, and the cooler is connected to the compressor pipeline.

[0034] In one specific implementation, a discharge regulating valve 5 is provided on the discharge pipeline, and the opening degree of the discharge regulating valve 5 is controlled by the estimated total amount of working fluid of the power generation module during operation. A filling regulating valve 6 is provided on the filling pipeline, and the opening degree of the filling regulating valve 6 is controlled by the load increase command of the power generation module, the hot side outlet pressure of the regenerator, and the pressure of the gas storage tank during operation. The discharge regulating valve 5, the filling regulating valve 6, and each sensor are electrically connected to an external controller.

[0035] In this embodiment, the external controller estimates the total amount of working fluid in the system in real time and compares it with the target inventory. When the estimated value is higher than the target, a release command is issued to gradually open the release regulating valve 5 and introduce carbon dioxide from the compressor side into the storage tank 1. When the estimated value returns to within the target bandwidth, the valve reduces its opening or closes to achieve stable recovery.

[0036] Specifically, when a load increase command is received, the external controller adopts a feedforward plus feedback strategy: the feedforward provides the initial opening of the filling regulating valve 6 based on the power increase target; the feedback corrects the pressure difference between the hot side outlet pressure of the regenerator and the target pressure; the differential pressure between the pressure of the gas storage tank 1 and the hot side outlet pressure of the regenerator is monitored synchronously; when the tank pressure has a filling margin, the valve is opened and adjusted to inject the medium in the gas storage tank 1 into the hot side outlet; if the differential pressure is insufficient or the tank pressure is too low, the opening is limited and the gas replenishment module is linked to increase the tank pressure before filling.

[0037] In another specific embodiment, the pressure regulating system operates as follows:

[0038] When the working mass of the circulating system needs to be reduced due to load reduction or other reasons, the venting regulating valve 5 opens, and part of the high-pressure carbon dioxide at the compressor outlet is discharged into the gas storage tank 1 under the action of differential pressure; when the working mass of the circulating system needs to be increased, the filling regulating valve 6 opens, and the carbon dioxide in the gas storage tank 1 is filled into the hot side outlet of the regenerator under the action of differential pressure.

[0039] Furthermore, as the circulation system operates, leakage of carbon dioxide working fluid is inevitable. The supercritical carbon dioxide power generation working fluid pressure regulation system can replenish the working fluid in the circulation system. The liquid carbon dioxide in the liquid carbon dioxide storage tank 2 is heated and transported to the gas storage tank 1 by the action of the transfer pump 3 and the heater 4, maintaining the pressure of the gas storage tank 1 within a reasonable pressure range.

[0040] Furthermore, during normal shutdown, the relief regulating valve 5 is opened appropriately to recover some of the working fluid to the gas storage tank 1, reducing the system pressure to a safe shutdown value and reducing external venting; in case of tripping or overpressure, the relief regulating valve is opened quickly to prioritize the recovery of the working fluid to the gas storage tank 1, and the cooler is activated to reduce temperature and limit pressure; after the pressure drops, the shutdown or restart process is initiated.

[0041] To aid in a better understanding of the invention, a more comprehensive and specific embodiment is described, in which the invention provides a supercritical carbon dioxide power generation working fluid pressure regulation system, comprising:

[0042] The power generation module includes a compressor and a regenerator connected to the compressor via piping; and a gas storage buffer module includes a gas storage tank 1, which is connected to a venting pipe and a filling pipe. The venting pipe is connected to the compressor to deliver carbon dioxide working fluid from the compressor to the gas storage tank 1 during operation, and the filling pipe is connected to the hot-side outlet of the regenerator to deliver carbon dioxide working fluid from the gas storage tank 1 to the hot-side outlet of the regenerator during operation.

[0043] In this embodiment, the supercritical carbon dioxide power generation working fluid pressure regulation system further includes a gas replenishment module. The gas replenishment module includes a heater 4 connected to the gas storage tank 1 via a pipeline, a delivery pump 3 connected to the heater 4 via a pipeline, and a liquid carbon dioxide storage tank 2 connected to the delivery pump 3 via a pipeline. The heater 4 is an electric heater. The liquid carbon dioxide storage tank 2 is a normal temperature pressure storage tank equipped with a level gauge. The delivery pump 3 is either a plunger pump or a centrifugal pump. The gas storage tank 1 is a steel storage tank with an insulation layer on the outside, and a pressure gauge is installed inside the gas storage tank 1. The power generation module also includes a turbine connected to the compressor via a pipeline, and a generator is connected to the turbine. The hot-side outlet of the regenerator is connected to the cooler via a pipeline, and the cold-side outlet of the regenerator is connected to the heat exchanger via a pipeline. The hot-side outlet of the heat exchanger is connected to the turbine via a pipeline, and the cooler is connected to the compressor via a pipeline.

[0044] Furthermore, a discharge regulating valve 5 is installed on the discharge pipeline, and the opening degree of the discharge regulating valve 5 is controlled by the estimated total amount of working fluid of the power generation module during operation. A filling regulating valve 6 is installed on the filling pipeline, and the opening degree of the filling regulating valve 6 is controlled by the load increase command of the power generation module, the hot side outlet pressure of the regenerator, and the pressure of the gas storage tank 1 during operation.

[0045] In summary, the embodiments disclosed herein have at least the following technical effects:

[0046] By bidirectionally adjusting the working fluid between the main circuit and the gas storage tank 1 through the gas storage buffer module, the average pressure and critical node pressure of the system can be quickly and accurately adjusted, significantly reducing pressure fluctuations and overshoot during start-up, shutdown and load-following processes.

[0047] The filling valve is controlled in a closed loop by the load increase command and the hot side outlet pressure of the regenerator. When the gas storage tank 1 has a differential pressure margin, it quickly replenishes carbon dioxide to the high-pressure point on the hot side, increases the mass flow and system average pressure, shortens the power ramp-up time, and improves the load tracking capability and predictability.

[0048] During the startup phase, the working fluid is filled in stages, and the pressure is smoothly increased along the target pressure curve to avoid pressure jumps caused by low temperature and high density. During the shutdown phase, excess working fluid is recovered to storage tank 1 and the pressure is quickly reduced to a safe storage range to reduce external venting.

[0049] In case of abnormal overpressure or shutdown, the gas is preferentially recycled to the internal storage tank 1 to reduce the frequent operation of the safety valve and the risk of external discharge; the venting point is located on the compressor side, which helps to keep it away from the surge boundary and works with the cooler to achieve pressure limiting and cooling.

[0050] Closed-loop internal recovery and gas replenishment are linked to minimize working fluid loss and replenishment costs, thereby reducing carbon dioxide emissions; start-up and shutdown and operating mode switching are smoother, reducing energy consumption and operation and maintenance costs during non-power generation periods.

[0051] The discharge regulating valve 5 performs slow variable inventory offsetting based on the estimated total amount of working fluid, while the filling regulating valve 6 performs fast variable power response based on the load increase command and node pressure. The feedforward plus feedback hierarchical decoupling control reduces loop conflicts, the parameters are intuitive, and there is a large space for online optimization.

[0052] The gas storage tank 1 adopts an insulated steel structure and is equipped with a pressure gauge, making its status visible. The gas replenishment module consists of a normal temperature pressure liquid carbon dioxide tank, a pump, and an electric heater. The components are mature, the response is fast, and the maintenance is convenient. The pump type can be selected as plunger or centrifugal according to the working conditions, taking into account both high pressure metering and high flow rate delivery requirements.

[0053] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A supercritical carbon dioxide power generation working fluid pressure regulation system, characterized in that, include: A power generation module includes a compressor and a regenerator connected to the compressor via piping; the power generation module also includes a turbine connected to the compressor via piping, a generator connected to the turbine, the hot-side outlet of the regenerator being connected to a cooler via piping, the cold-side outlet of the regenerator being connected to a heat exchanger via piping, the hot-side outlet of the heat exchanger being connected to the turbine via piping, and the cooler being connected to the compressor via piping. A gas storage buffer module includes a gas storage tank connected to a venting pipeline and a filling pipeline. The venting pipeline is connected to the compressor to deliver carbon dioxide working fluid from the compressor to the gas storage tank during operation. The filling pipeline is connected to the hot-side outlet of the regenerator to deliver carbon dioxide working fluid from the gas storage tank to the hot-side outlet of the regenerator during operation. The venting pipeline is equipped with a venting regulating valve, the opening of which is controlled by an estimated total working fluid volume of the power generation module during operation. The filling pipeline is equipped with a filling regulating valve, the opening of which is controlled by the load increase command of the power generation module, the hot-side outlet pressure of the regenerator, and the pressure of the gas storage tank during operation. The gas replenishment module includes a heater connected to the gas storage tank pipeline, a delivery pump connected to the heater pipeline, and a liquid carbon dioxide storage tank connected to the delivery pump pipeline.

2. The supercritical carbon dioxide power generation working fluid pressure regulation system according to claim 1, characterized in that, The heater is an electric heater.

3. The supercritical carbon dioxide power generation working fluid pressure regulation system according to claim 1, characterized in that, The liquid carbon dioxide storage tank is an ambient temperature pressure storage tank equipped with a level gauge.

4. The supercritical carbon dioxide power generation working fluid pressure regulation system according to claim 1, characterized in that, The delivery pump is either a plunger pump or a centrifugal pump.

5. The supercritical carbon dioxide power generation working fluid pressure regulation system according to claim 1, characterized in that, The gas storage tank is a steel tank with an outer insulation layer, and a pressure gauge is installed inside the gas storage tank.

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