Control protection system for expansion machine of supercritical carbon dioxide power generation device, expansion machine system and working method thereof

Abstract

The invention discloses a control and protection system for an expansion machine of a supercritical carbon dioxide power generation device, an expansion machine system and a working method, and the control and protection system comprises a dynamometer which is coaxially and rigidly connected with the expansion machine and is used for measuring a performance curve of the expansion machine; the performance curve of the expansion machine comprises an expansion machine rotating speed-dynamometer power change curve in the rotating speed increasing and decreasing process and an expansion machine rotating speed-dynamometer torque change curve in the rotating speed increasing and decreasing process. At least one of an expansion machine rotating speed-dynamometer power changing curve in the fixed rotating speed load increasing and decreasing process and an expansion machine rotating speed-dynamometer torque changing curve in the fixed rotating speed load increasing and decreasing process; the control subsystem is used for controlling the operation of the expansion machine; in the performance test stage, the control subsystem controls the dynamometer and the expansion machine to measure the performance curve of the expansion machine in a variable-speed operation mode or a variable-load operation mode. The device has the advantage that the performance curve of the expansion machine can be tested and verified.

Description

Technical Field

[0001] The present invention relates to the field of supercritical carbon dioxide power generation, and particularly to a control and protection system for an expander of a supercritical carbon dioxide power generation device, an expander system and a working method thereof. Background Art

[0002] Supercritical carbon dioxide power generation technology is a cutting-edge technology that has developed rapidly in recent years. Different from working fluids such as gas used in traditional thermal power systems, it uses carbon dioxide in a supercritical state with temperature and pressure above the critical point as the working fluid for doing work. Compared with the traditional steam Rankine cycle power generation technology, it can significantly improve the thermoelectric conversion efficiency, and at the same time, it can significantly reduce the volume and weight of equipment.

[0003] The supercritical carbon dioxide cycle power generation technology achieves a higher thermoelectric conversion efficiency than the traditional steam cycle by operating under conditions above the critical temperature and pressure. In this cycle, the expander, i.e., the turbine, serves to convert thermal energy into mechanical energy, and then drives the generator to generate electric energy. As one of the core components of the supercritical carbon dioxide cycle power generation technology, the performance of the expander directly affects the efficiency and stability of the entire power generation system. Therefore, it is necessary to ensure that the expander can operate stably and efficiently under various working conditions. However, at present, the control, protection and detection means for the expander are relatively limited, resulting in the inability to accurately evaluate, verify and protect the performance of the expander during actual operation, which to a certain extent restricts the technological progress and wide application in this field. For example, the existing control and testing means often focus on the performance of the expander at the design point, while the evaluation of its performance stability and reliability within the entire operating range is insufficient. Therefore, it is necessary to improve the equipment.

[0004] It can be understood that the above statements only provide background technology related to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0005] Based on the foregoing technical problems, the object of the present invention is to provide a control and protection system for an expander of a supercritical carbon dioxide power generation device, an expander system and a working method thereof. The control and protection system of the expander controls the operating modes of the dynamometer and the expander through a control subsystem, can achieve a full-range test and verification of the performance curve of the expander during the performance test stage, helps the staff to comprehensively understand the operating state of the expander in the actual operating conditions, helps to ensure the safety and stability of the expander during actual operation, and realizes the safety operation protection of the expander and the entire supercritical carbon dioxide power generation device.

[0006] To achieve the above object, the present invention is realized through the following technical solutions:

[0007] A control and protection system for an expander of a supercritical carbon dioxide power generation device, comprising:

[0008] A dynamometer, which is rigidly connected to the expander coaxially, and the dynamometer is used to measure the performance curve of the expander; wherein, the performance curve of the expander includes at least one of: the expander speed - dynamometer power change curve during the process of raising and lowering the speed, the expander speed - dynamometer torque change curve during the process of raising and lowering the speed, the expander speed - dynamometer power change curve during the process of raising and lowering the load at a constant speed, and the expander speed - dynamometer torque change curve during the process of raising and lowering the load at a constant speed;

[0009] A control subsystem, which is used to control the operation of the expander and the control and protection system; during the performance test stage, the control subsystem controls the dynamometer and the expander to measure the performance curve of the expander in a variable speed operation mode or a variable load operation mode.

[0010] Optionally, the variable speed operation mode includes:

[0011] The expander is in a speed control mode, and the dynamometer is in a power control mode. The control subsystem adjusts the opening of the high-pressure regulating valve of the expander to adjust the speed of the expander, so as to obtain the performance curve of the expander during the process of raising and lowering the speed;

[0012] The expander is in a power control mode, and the dynamometer is in a speed control mode. The control subsystem adjusts the torque of the dynamometer to adjust the speed of the dynamometer, so as to obtain the performance curve of the expander during the process of raising and lowering the speed.

[0013] Optionally, the variable load operation mode includes:

[0014] The expander is in a speed control mode, and the dynamometer is in a power control mode. Under the condition of constant speed, the control subsystem adjusts the torque of the dynamometer, and at the same time, the high-pressure regulating valve of the expander automatically controls its opening to maintain the current speed unchanged, so as to obtain the performance curve of the expander during the process of raising and lowering the load dominated by the dynamometer;

[0015] The expander is in a power control mode, and the dynamometer is in a speed control mode. Under the condition of constant speed, the control subsystem adjusts the opening of the high-pressure regulating valve of the expander, and at the same time, the dynamometer automatically controls the speed to maintain the current speed unchanged, so as to obtain the performance curve of the expander during the process of raising and lowering the load dominated by the expander.

[0016] Optionally, the dynamometer is a hydraulic dynamometer or an electric dynamometer.

[0017] Optionally, it further includes:

[0018] A dry gas seal subsystem, which is used to ensure the isolation of the gas inside the expander from the external atmospheric environment.

[0019] Optionally, it further includes:

[0020] A control valve subsystem and a servo-hydraulic subsystem, wherein the servo-hydraulic subsystem controls the opening degree of the gas valve of the expander through the control valve subsystem, and further controls the rotational speed and power of the expander.

[0021] Optionally, it further includes:

[0022] A lubricating oil subsystem, which is used to provide lubricating oil for the expander;

[0023] A barring gear subsystem, which is used to drive the rotor of the expander to rotate when the expander stops.

[0024] Optionally, an expander system for a supercritical carbon dioxide power generation device includes:

[0025] An expander;

[0026] The aforementioned control and protection system for the expander of the supercritical carbon dioxide power generation device, and the control and protection system is used to control the operation of the expander.

[0027] Optionally, a working method of the aforementioned control and protection system for the expander of the supercritical carbon dioxide power generation device includes:

[0028] Start the expander and the dynamometer;

[0029] The control subsystem controls the dynamometer and the expander to measure the performance curve of the expander in a variable speed operation mode or a variable load operation mode. Among them, the performance curve of the expander includes at least one of the expander speed-dynamometer power change curve during the process of raising and lowering the speed, the expander speed-dynamometer torque change curve during the process of raising and lowering the speed, the expander speed-dynamometer power change curve during the process of raising and lowering the load at a constant speed, and the expander speed-dynamometer torque change curve during the process of raising and lowering the load at a constant speed.

[0030] Optionally, the control and protection system of the expander includes a dry gas seal subsystem, and the working method of the control and protection system further includes:

[0031] Start the dry gas seal subsystem at a preset time before starting the expander and the dynamometer.

[0032] The present invention has the following advantages compared with the prior art:

[0033] In a control and protection system for an expander of a supercritical carbon dioxide power generation device, an expander system, and a working method thereof according to the present invention, the control and protection system controls the operating modes of a dynamometer and an expander through a control subsystem, and can achieve a comprehensive test and verification of the performance curve of the expander during the performance test stage, helping the staff to comprehensively understand the operating state of the expander in the actual operating conditions, contributing to ensuring the safety and stability of the expander in actual operation, and realizing the safety operation protection of the expander and the entire supercritical carbon dioxide power generation device.

[0034] Furthermore, the control and protection system further includes a dry gas seal subsystem to ensure the isolation of the gas inside the expander from the external atmospheric environment, which helps to ensure the stability of the carbon dioxide working medium during operation in the expander. Brief Description of the Drawings

[0035] In order to more clearly illustrate the technical solution of the present invention, the drawings required for description will be briefly introduced below. Obviously, the drawings in the following description are an embodiment of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts:

[0036] Figure 1 It is a schematic diagram of the brief relationship between a control and protection system and an expander of the present invention;

[0037] Figure 2 It is a curve of expander speed - dynamometer power change during the process of raising and lowering the speed of the present invention;

[0038] Figure 3 It is a curve of expander speed - dynamometer torque change during the process of raising and lowering the speed of the present invention;

[0039] Figure 4 It is a curve of expander speed - dynamometer power change during the process of reducing the load at a constant speed of the present invention;

[0040] Figure 5 It is a curve of expander speed - dynamometer torque change during the process of reducing the load at a constant speed of the present invention;

[0041] Figure 6 It is a schematic diagram of the start - up sequence control program for the preparation before the expander starts to rotate impulsively and the expander starts to rotate impulsively of the present invention. Detailed Embodiments

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] It should be noted that in this article, the terms "include", "comprise", "have", or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or terminal device. Without further limitation, the elements defined by the statement "comprising..." or "comprising..." do not exclude the presence of additional elements in the process, method, article, or terminal device comprising the said elements.

[0044] It should be noted that the accompanying drawings are all in very simplified forms and use non-precise ratios, only for the purpose of facilitating and clearly assisting in explaining the objectives of the embodiments of the present invention.

[0045] As can be seen from the foregoing, the expander is one of the core components of the supercritical carbon dioxide cycle power generation technology. The quality of its performance is directly related to the energy efficiency ratio and stability of the entire power generation system. Therefore, the control and protection of the expander is a very important link in the operation of the supercritical carbon dioxide power generation unit. The continuous research and improvement of the control and protection system of the expander is a very important and meaningful task, which is crucial for promoting the commercialization process of the supercritical carbon dioxide power generation technology.

[0046] Based on the above, the present invention provides a control and protection system for an expander of a supercritical carbon dioxide power generation device. The control and protection system includes a dynamometer and a control subsystem. Among them, the dynamometer is rigidly connected to the expander coaxially, so that the dynamometer and the expander have the same rotational speed. The dynamometer is used to measure the performance curve of the expander. In practical applications, the dynamometer is equivalent to a resistance device, which is used to accurately measure the power generated by the expander and consume this part of energy. When the dynamometer and the expander move coaxially, only the dynamometer is a work-consuming link, and the actual power of the dynamometer and the actual power of the expander are the same parameter. The control subsystem is used to control the operation of the expander and the control and protection system. During the performance test stage, the control subsystem controls the dynamometer and the expander to measure the performance curve of the expander in a variable rotational speed operation mode or a variable load operation mode. Among them, the performance curve of the expander includes at least one of the following: the expander rotational speed - dynamometer power change curve during the process of raising and lowering the rotational speed, the expander rotational speed - dynamometer torque change curve during the process of raising and lowering the rotational speed, the expander rotational speed - dynamometer power change curve during the process of raising and lowering the load at a constant rotational speed, and the expander rotational speed - dynamometer torque change curve during the process of raising and lowering the load at a constant rotational speed. Briefly speaking, the performance curve of the expander includes the rotational speed - torque change curve and the rotational speed - power change curve during the variable rotational speed and variable load processes. Among them, both the power and the torque are measured by the dynamometer, and the torque of the dynamometer and the load of the expander follow the formula T = 9550P / n.

[0047] As can be seen from the above, the control and protection system of the present invention controls the operation modes of the dynamometer and the expander through the control subsystem, and can realize the comprehensive test and verification of the performance curve of the expander during the performance test stage, helping the staff to comprehensively understand the operation state of the expander in the actual operation condition, contributing to ensuring the safety and stability of the expander in actual operation, realizing the safety operation protection of the expander and the entire supercritical carbon dioxide power generation device, and having very important significance for the safe operation of the unit of the supercritical carbon dioxide power generation device and the personal safety of the staff.

[0048] In this embodiment, the dynamometer is a hydraulic dynamometer. It can be understood that the type of the dynamometer is not limited to the above. In other embodiments, it can also be other types of devices, and the present invention does not limit this. For example, in another embodiment, the dynamometer is an electric dynamometer.

[0049] Further, in the variable speed operation mode, it includes the cases of expander-dominated variable speed and dynamometer-dominated variable speed. Among them, the expander-dominated variable speed of the variable speed operation mode includes: the expander is in the speed control mode, and the dynamometer is in the power control mode. The control subsystem adjusts the opening of the high-pressure regulating valve in front of the expander to adjust the speed of the expander, so as to achieve the variable speed operation of the expander (the speeds of the dynamometer and the expander are the same), in order to obtain the performance curve of the expander during the process of increasing and decreasing speed. Specifically, when the control subsystem adjusts and reduces the opening of the high-pressure regulating valve, the speed of the expander can be reduced; when the opening of the high-pressure regulating valve is increased, the speed of the expander can be increased. When the valve of the high-pressure regulating valve is fully open, the speed cannot be increased any more.

[0050] In practical applications, power, speed, and torque follow the formula: T = 9550P / n, where T is the torque of the expander and the dynamometer, P is the actual power of the expander and the dynamometer, and n is the actual speed of the dynamometer. When the expander reduces speed, the torque of the dynamometer remains unchanged (with a certain lag), the power will decrease, and there will be a deviation between the actual power of the expander and its power set value. Then the dynamometer will start to increase the torque to ensure that the actual power is consistent with the power set value, and the system reaches a new balance point.

[0051] If the target power of the expander, that is, its current power set value, is kept unchanged during the process of the expander-dominated reduction of speed, then the expansion ratio increases, and the high-pressure regulating valve needs to be opened wider, which is contrary to the control logic of the high-pressure regulating valve. Therefore, it cannot be assumed that the target power of the expander remains unchanged. So in this application, while the expander is dominated by variable speed, the target power of the dynamometer also needs to be variable.

[0052] To further illustrate the necessity of changing the target power of the dynamometer while the expander is dominated by variable speed, the following takes the process of the expander-dominated reduction of speed as an example for illustration. First, set the relationship between the power of the dynamometer and the speed, set the target speed of the expander, and reduce the opening of the high-pressure regulating valve to control the speed reduction. If the current power of the dynamometer is set as the target power and this target power remains unchanged during the process of the expander reducing speed, and the high-pressure regulating valve of the expander is adjusted to achieve speed reduction. The high-pressure regulating valve starts to close according to the set target speed, and the expander reduces speed (that is, n decreases). When the expander just starts to reduce speed, the instantaneous torque of the dynamometer remains unchanged (that is, T remains unchanged). When the dynamometer monitors that the expander reduces speed, its own speed also decreases. From the formula T = 9550P / n, it can be seen that the current actual power of the dynamometer deviates from its target power (that is, P decreases). In order to keep its current actual power at / close to the target power, the dynamometer will make an action to increase the torque, which will cause the expander to reduce speed faster (such as Figure 3 the red line in

[0053] If the target power of the dynamometer is reduced, i.e., its target power is set to a smaller value, when the dynamometer monitors that its current power is greater than the target power value, the dynamometer will tend to reduce the current power and perform a torque reduction action (i.e., T decreases first), and the load of the expander decreases. If the high-pressure regulating valve does not act or the action speed cannot compensate for the unloaded load (i.e., P remains unchanged or decreases slowly), according to the formula T = 9550P / n, there is a risk of a rapid increase in the expander speed (i.e., n will increase). Therefore, in actual operation, it is not allowed to set the target power of the dynamometer too small.

[0054] Based on the above, it can be seen that during the performance test stage, if the set value of the dynamometer target power is too large, the expander speed will drop sharply; if the set value of the dynamometer target power is too small, there is a risk of a rapid increase in the expander speed. Therefore, the target power of the dynamometer should be adjusted at any time according to different speeds to avoid the situation of too rapid a decrease in speed. Optionally, the target power of the dynamometer is within the operating power boundary range of the expander. As Figure 2 shown by the red line in, it is a curve of expander speed - dynamometer power during the process of the expander dominating the speed reduction. When measuring this curve, adjust the speed of the expander and measure the change in power at any time; as Figure 3 shown by the red line in, it is a curve of expander speed - dynamometer torque during the process of the expander dominating the speed reduction. Among them, Figure 2 the black solid line in represents the operating boundary of the dynamometer, the blue dotted line represents the inlet pressure of the expander design condition, that is, the operating boundary of the expander, and the blue solid line represents the allowable operating pressure of the expander ( Figures 3 to 5 the meaning of the same-color lines in is the same). The process of increasing the speed during the case of the expander dominating the variable speed is the reverse process of reducing the speed, which will not be elaborated here.

[0055] On the other hand, the dynamometer-dominated variable speed of the variable speed operation mode includes: the expander is in the power control mode, and the dynamometer is in the speed control mode. The control subsystem adjusts the torque of the dynamometer to adjust the speed of the dynamometer to obtain the performance curve of the expander during the process of increasing and decreasing the speed. In this case, keep the valve opening of the high-pressure regulating valve of the expander unchanged, and realize variable speed operation by adjusting the set speed of the dynamometer. During this process, when changing from the current stable condition to the next stable condition, a new target speed needs to be set first.

[0056] Figure 2 The green line in is a curve of expander speed - dynamometer power during the process of the dynamometer dominating the speed reduction, Figure 3The green line is the curve of the expander speed - dynamometer torque during the main speed reduction process of a dynamometer. The starting point is the rated condition state point. Keeping the opening of the high - lift valve of the expander unchanged under this state (i.e., P remains unchanged), when the dynamometer monitors that the current speed is greater than the set speed of the next stable condition, the dynamometer increases the torque (i.e., T increases). According to the formula T = 9550P / n, the speed decreases (i.e., n decreases). For the case where the pressure before the high - lift valve and the back pressure downstream of the expander outlet are basically stable, keeping the opening of the high - lift valve unchanged, the pressure ratio of the expander changes little, and the condition change is basically along an isobaric line. The speed - increase process in this case is the reverse process of the speed - reduction process and will not be elaborated here.

[0057] On the other hand, in the variable - load operation mode, there are cases including dynamometer - dominated variable load and expander - dominated variable load. Among them, the dynamometer - dominated variable load in the variable - load operation mode includes: when the expander is in the speed - control mode and the dynamometer is in the power - control mode, at a constant speed, the control subsystem adjusts the torque of the dynamometer, and at the same time, the high - lift valve of the expander automatically controls its opening to maintain the current speed unchanged, so as to obtain the expander performance curve during the dynamometer - dominated load - increase and load - decrease processes.

[0058] In this case, the high - lift valve of the expander automatically controls the speed. During the test, the control subsystem increases or decreases the load output by the dynamometer, that is, the torque. When the dynamometer reduces the load (reduces the torque), the speed of the expander has an upward trend. To maintain the current speed, the high - lift valve automatically controls to close the valve opening. When the dynamometer increases the load (increases the torque), the speed of the expander has a downward trend. To maintain the current speed, the high - lift valve automatically controls to increase the valve opening. When the high - lift valve is at the maximum opening, the expander is at the maximum power at the current speed. If the power of the dynamometer is increased further at this time, the expander will not be able to maintain the current speed and will decelerate. During this process, the power measured by the dynamometer will be transmitted as a signal to the control subsystem as the actual power of the expander (the actual powers of the two are the same). Figure 4 The orange line in the figure gives the curve of the expander speed - dynamometer power during the process of load reduction with a constant speed and dynamometer - dominated operation, Figure 5 The orange line in the figure gives the curve of the expander speed - dynamometer torque during the process of load reduction with a constant speed and dynamometer - dominated operation.

[0059] Furthermore, the expander - dominated variable load in the variable - load operation mode includes: the expander is in the power - control mode and the dynamometer is in the speed - control mode. At a constant speed, the control subsystem adjusts the opening of the high - lift valve of the expander, and at the same time, the dynamometer automatically controls the speed to maintain the current speed unchanged, so as to obtain the expander performance curve during the expander - dominated load - increase and load - decrease processes.

[0060] In this case, the dynamometer automatically controls the rotational speed. The control subsystem realizes variable load operation by adjusting the opening degree of the high-pressure regulating valve in front of the expander. When the opening degree of the high-pressure regulating valve decreases, the rotational speed of the expander tends to decrease. To maintain the current rotational speed, the dynamometer starts to reduce the torque. When the opening degree of the high-pressure regulating valve increases, the rotational speed of the expander tends to increase. To maintain the current rotational speed, the hydraulic dynamometer starts to increase the torque. The operating curves under the two variable load control modes are the same, as shown in the orange line in Figure 4 and Figure 5 . The load reduction at the rated rotational speed is shown in the figure, and other rotational speeds can be referred to for implementation. The load increase process in this case is the reverse process of the load reduction process, which will not be elaborated here.

[0061] On the other hand, the control and protection system of the expander further includes a dry gas seal subsystem, which is used to ensure the isolation of the gas inside the expander from the external atmospheric environment. Specifically, it can effectively isolate the high-parameter gas inside the cylinder of the expander from the external atmosphere during the operation of the unit, preventing air leakage.

[0062] Furthermore, the control and protection system of the expander also includes a lubricating oil subsystem, a barring gear subsystem, a servo hydraulic subsystem, and a control valve subsystem. Among them, the lubricating oil subsystem is used to provide lubricating oil for the expander to ensure the lubrication and cooling of all bearings of the expander; the barring gear subsystem is used to drive the rotor of the expander to rotate at a low speed when the expander stops, to prevent the rotor from generating flexible bending deformation. The control valve subsystem is also called the control oil subsystem. The servo hydraulic subsystem controls the opening degree of the gas valve of the expander through the control valve subsystem, and then controls the rotational speed and power of the expander. The gas valve of the expander includes a main steam valve and a high-pressure regulating valve. The oil motor of the control valve subsystem is directly connected to the gas valve of the expander through a mechanical connection assembly, and they are an integral mechanical connection structure (the valve stem of the gas valve is directly connected to the piston rod of the oil motor through a flange). In practical applications, the servo hydraulic subsystem controls the inlet and return oil of the oil motor to control / drive the opening or closing of the gas valve of the expander, thereby controlling the amount of gas entering the expander. The change in the amount of gas controls the rotational speed and / or power of the entire expander device. Each of the above subsystems has a separate startup program. In practical applications, the control subsystem controls the startup and shutdown of each subsystem, and the modular configuration method is convenient for operators to learn, study, and modify. Based on the above subsystems, the normal operation and shutdown of the expander can be ensured, and further the safety and reliability of the expander during actual operation can be ensured.

[0063] Further, to ensure the safe operation of the expander, in the event of an abnormal situation, the control subsystem needs to take rapid and effective measures for the expander to protect the operation of the unit of the supercritical carbon dioxide power generation device and the personal safety of the staff. The corresponding strategies of the control subsystem for abnormal situations include: 1) If the abnormality is detected when the unit of the expander is in a stationary state, it only needs to be retested after troubleshooting; 2) If the abnormality is detected when the unit of the expander is in an operating state, it is necessary to judge according to the specific scope and severity of the fault. According to the judgment result, a scheme of shutting down the unit for protection and then troubleshooting after shutdown or a scheme of not shutting down and retesting after troubleshooting can be adopted.

[0064] Based on the same inventive concept, the present invention also provides an expander system for a supercritical carbon dioxide power generation device. The expander system includes an expander and the aforementioned control and protection system of the expander. The control and protection system is used to control the operation of the expander. Based on the foregoing, the expander system can perform all-round testing on the performance curve of the expander in the actual operating conditions through the control and protection system for the expander, which helps the staff to adjust the expander in actual operation based on the test results, thereby ensuring the safety and stability of the operation of the expander. Applying the expander system to the supercritical carbon dioxide power generation device helps to ensure the safety and stability of the operation of the supercritical carbon dioxide power generation device.

[0065] Based on the same inventive concept, the present invention also provides a working method of the aforementioned control and protection system of the expander for a supercritical carbon dioxide power generation device. The working method of the control and protection system includes: starting the expander and the dynamometer; the control subsystem controls the dynamometer and the expander to measure the performance curve of the expander in a variable speed operation mode or a variable load operation mode, wherein the performance curve of the expander includes at least one of the expander speed-dynamometer power change curve during the process of raising and lowering the speed, the expander speed-dynamometer torque change curve during the process of raising and lowering the speed, the expander speed-dynamometer power change curve during the process of raising and lowering the load at a constant speed, and the expander speed-dynamometer torque change curve during the process of raising and lowering the load at a constant speed.

[0066] Optionally, the control and protection system of the expander includes a dry gas seal subsystem, and the working method of the control and protection system further includes: starting the dry gas seal subsystem at a preset time before starting the expander and the dynamometer. Optionally, the preset time is 1 hour. Of course, it can also be other time ranges, and the present invention does not limit this.

[0067] In the present invention, the modeling automation of the control and protection system means that the control subsystem can start and stop each subsystem (such as the dynamometer, lubricating oil subsystem, barring gear subsystem, and servo hydraulic subsystem, etc.) according to actual requirements, and adopt different control strategies according to different operating conditions of the system. In practical applications, each subsystem starts in sequence, the expander automatically speeds up to the standby speed, and finally speeds up to the rated speed in the recommended expander load control mode / dynamometer speed control mode, etc., to ensure the continuity before and after the system starts.

[0068] Based on the above, as shown in Table 1 and Table 2 below, the present invention also provides a start sequence control program for the preparation before the start-up and turning of the expander (see Figure 6 ). Among them, the preparation before the start-up and turning of the expander includes the step sequence of on-site inspection stage and the step sequence of system inspection stage. The step sequence of the system inspection stage includes: 1) manual / automatic system inspection; 2) start the control oil subsystem; 3) start the lubricating oil subsystem; 4) barring gear subsystem inspection; 5) start the barring gear subsystem; 6) barring gear running state inspection. The start-up and turning of the expander includes the inspection stage step sequence, the preparation step sequence before the start-up and turning, and the system start-up to standby stage. The preparation step sequence before the start-up and turning includes: 1) start the dry gas seal subsystem; 2) set the dynamometer power; 3) check the system status parameters. The system start-up to standby stage includes the following operations on the expander: 1) warm the valve; 2) start the turning; 3) turn to the rated speed. Based on the above start sequence control program, the expander can enter the performance test stage, and then measure the performance curve of the expander is realized. It should be noted that the signal representation forms in Table 1 and Table 2 are the signal symbols customized in a certain expander system in practical applications. Further, the "Logical STEP X step sequence" (X is an Arabic numeral) in the next column of each operation represents the control program commands used in the expander system for each operation. It can be understood that in practical applications, the signal symbols can also be represented in other forms, and the present invention does not limit this.

[0069] Table 1 Start Sequence Control Program for Preparation before Start-up and Turning of Expander

[0070]

[0071]

[0072]

[0073]

[0074] Table 2 Start Sequence Control Program for Start-up and Turning of Expander

[0075]

[0076]

[0077]

[0078]

[0079] In summary, in a control and protection system for an expander, an expander system and a working method thereof for a supercritical carbon dioxide power generation device, the control and protection system can achieve a comprehensive test and verification of the performance curve of the expander during the performance test stage by controlling the operating modes of the dynamometer and the expander, helping the staff to comprehensively understand the operating state of the expander in the actual operating conditions, contributing to ensuring the safety and stability of the expander during actual operation, and realizing the safety operation protection of the expander and the entire supercritical carbon dioxide power generation device.

[0080] Furthermore, the control and protection system further includes a dry gas seal subsystem to ensure the isolation of the gas inside the expander from the external atmospheric environment, contributing to ensuring the stability of the carbon dioxide working medium during operation in the expander.

[0081] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A control and protection system for an expander of a supercritical carbon dioxide power generation device, characterized in that, Comprising: A dynamometer, which is rigidly connected to the expander coaxially, and the dynamometer is used to measure the performance curve of the expander; wherein, the performance curve of the expander includes at least one of the expander speed-dynamometer power change curve during the process of raising and lowering the speed, the expander speed-dynamometer torque change curve during the process of raising and lowering the speed, the expander speed-dynamometer power change curve during the process of raising and lowering the load at a constant speed, and the expander speed-dynamometer torque change curve during the process of raising and lowering the load at a constant speed; A control subsystem, which is used to control the operation of the expander and the control protection system; during the performance test stage, the control subsystem controls the dynamometer and the expander to measure the performance curve of the expander in the variable speed operation mode or the variable load operation mode.

2. The control and protection system for the expander of the supercritical carbon dioxide power generation device according to claim 1, characterized in that, The variable speed operation mode includes: The expander is in the speed control mode, and the dynamometer is in the power control mode. The control subsystem adjusts the opening degree of the high-pressure regulating valve of the expander to adjust the speed of the expander, so as to obtain the performance curve of the expander during the process of raising and lowering the speed; The expander is in the power control mode, and the dynamometer is in the speed control mode. The control subsystem adjusts the torque of the dynamometer to adjust the speed of the dynamometer, so as to obtain the performance curve of the expander during the process of raising and lowering the speed.

3. The control and protection system for an expander used in a supercritical carbon dioxide power generation device according to claim 1, characterized in that, The variable load operation mode includes: The expander is in the speed control mode, and the dynamometer is in the power control mode. Under the condition of constant speed, the control subsystem adjusts the torque of the dynamometer, and at the same time the high-pressure regulating valve of the expander automatically controls its opening degree to maintain the current speed unchanged, so as to obtain the performance curve of the expander during the process of raising and lowering the load dominated by the dynamometer; The expander is in the power control mode, and the dynamometer is in the speed control mode. Under the condition of constant speed, the control subsystem adjusts the opening degree of the high-pressure regulating valve of the expander, and at the same time the dynamometer automatically controls the speed to maintain the current speed unchanged, so as to obtain the performance curve of the expander during the process of raising and lowering the load dominated by the expander.

4. The control protection system for the expander of the supercritical carbon dioxide power generation device according to claim 1, characterized in that The dynamometer is a hydraulic dynamometer or an electric dynamometer.

5. The control and protection system for the expander of a supercritical carbon dioxide power generation device according to claim 1, characterized in that, It further comprises: A dry gas seal subsystem, which is used to ensure the isolation of the gas inside the expander from the external atmospheric environment.

6. The control and protection system for the expander of a supercritical carbon dioxide power generation device according to claim 1, characterized in that, It further comprises: A control valve subsystem and a servo hydraulic subsystem. The servo hydraulic subsystem controls the opening degree of the gas valve of the expander through the control valve subsystem, and further controls the speed and power of the expander.

7. The control and protection system for an expander used in a supercritical carbon dioxide power generation device according to claim 1, characterized in that, It further comprises: A lubricating oil subsystem, which is used to provide lubricating oil for the expander; A barring gear subsystem, which is used to drive the rotor of the expander to rotate when the expander stops.

8. An expander system for a supercritical carbon dioxide power generation device, characterized in that, Comprising: An expander; The control protection system for the expander of the supercritical carbon dioxide power generation device according to any one of claims 1 to 7, and the control protection system is used to control the operation of the expander.

9. A working method of a control and protection system for an expander used in a supercritical carbon dioxide power generation device according to any one of claims 1 to 7, characterized in that, Comprising: Starting the expander and the dynamometer; The control subsystem controls the dynamometer and the expander to measure the performance curve of the expander in a variable speed operation mode or a variable load operation mode. Among them, the performance curve of the expander includes at least one of the expander speed-dynamometer power change curve during the process of increasing and decreasing speed, the expander speed-dynamometer torque change curve during the process of increasing and decreasing speed, the expander speed-dynamometer power change curve during the process of increasing and decreasing load at a constant speed, and the expander speed-dynamometer torque change curve during the process of increasing and decreasing load at a constant speed.

10. The working method of the control and protection system for the expander of the supercritical carbon dioxide power generation device according to claim 9, characterized in that, The control and protection system of the expander includes a dry gas seal subsystem, and the working method of the control and protection system further includes: Start the dry gas seal subsystem at a preset time before starting the expander and the dynamometer.

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