Anti-surge methods, devices, electronic equipment, and media for centrifugal compressor systems

Abstract

In the anti-surge method, device, electronic equipment, and medium for centrifugal compressor systems provided in this application, a first flow coefficient calculated based on the surge parameters of the centrifugal compressor is used as the current candidate coefficient. The first time required for the inlet flow rate of the centrifugal compressor to change from the initial flow rate value to the lower limit flow rate value under the current candidate coefficient is calculated. By comparing the first time and a predetermined second time, it is confirmed whether the candidate coefficient meets the operating condition requirements. If the requirements are met, the current candidate coefficient is determined as the flow coefficient of the anti-surge valve. If the requirements are not met, the current candidate coefficient is adjusted until the requirements are met. In this way, the rationality of the determined anti-surge valve flow coefficient is ensured, thereby ensuring the anti-surge effect of the centrifugal compressor.

Description

Technical Field

[0001] This application relates to the field of anti-surge technology for centrifugal compressors, and in particular to an anti-surge method, device, electronic equipment, and medium for a centrifugal compressor system. Background Technology

[0002] Surge is a relatively dangerous operating condition for centrifugal compressors. To prevent surge, an anti-surge valve is usually installed in the anti-surge circuit of the centrifugal compressor. The anti-surge valve controls the flow rate in the anti-surge circuit, thereby regulating the inlet flow rate of the centrifugal compressor so that it can escape the surge condition. The flow coefficient determines the flow capacity of the anti-surge valve, therefore, the flow coefficient of the anti-surge valve directly affects the anti-surge effect of the centrifugal compressor.

[0003] In related technologies, the flow coefficient of anti-surge valves is usually determined based on experience. However, actual working conditions are more complex, and the centrifugal compressor's anti-surge effect often becomes poor due to the unreasonable selection of the anti-surge valve's flow coefficient. Summary of the Invention

[0004] This application provides a method, device, electronic equipment, and medium for preventing surge in a centrifugal compressor system, aiming to solve the problem of poor surge prevention effect in centrifugal compressors caused by unreasonable flow coefficient of the selected anti-surge valve.

[0005] In a first aspect, this application provides a method for preventing surge in a centrifugal compressor system. The centrifugal compressor system includes a centrifugal compressor, process equipment, connecting pipelines, and an anti-surge valve. The flow coefficient of the anti-surge valve is obtained through the anti-surge method of the centrifugal compressor system. The method includes: calculating a first flow coefficient based on the surge parameters of the centrifugal compressor, and using the first flow coefficient as a current candidate coefficient; calculating a first time corresponding to the current candidate coefficient, where the first time is the time required for the inlet flow rate of the centrifugal compressor to change from an initial flow rate value to a lower flow rate limit value; wherein the initial flow rate value is less than the lower flow rate limit value, and the lower flow rate limit value is greater than the surge flow rate corresponding to the centrifugal compressor; if the first time corresponding to the current candidate coefficient is not greater than a predetermined second time, then the current candidate coefficient is determined as the flow coefficient of the anti-surge valve; otherwise, the current candidate coefficient is adjusted, and the step of calculating the first time corresponding to the current candidate coefficient is performed again until the first time corresponding to the current candidate coefficient is not greater than the second time.

[0006] Optionally, the calculation of the first time corresponding to the current candidate coefficient includes: recording the current time as the first time, and setting the inlet flow rate of the centrifugal compressor at the current time as the initial flow rate value; for each second time after the first time, obtaining the inlet flow rate of the centrifugal compressor at the second time under the current candidate coefficient;

[0007] If the inlet flow rate of the centrifugal compressor at the second moment reaches the lower flow rate limit, then the duration between the first moment and the current second moment is calculated as the first time corresponding to the current candidate coefficient.

[0008] Optionally, obtaining the inlet flow rate of the centrifugal compressor at the second time step for each second time step after the first time step includes: for each second time step after the first time step, obtaining the system state parameters and the inlet pressure of each node at the current second time step based on the flow rate, inlet pressure, and system state parameters of each node of the centrifugal compressor system at the previous time step; establishing a functional relationship between flow rate and pressure difference at each node based on the inlet pressure, system state parameters, and attribute parameters of each node at the current second time step; wherein, the nodes of the centrifugal compressor system include components constituting the system path of the centrifugal compressor system, each component including the centrifugal compressor and the anti-surge valve, and the attribute parameters of the anti-surge valve being the current candidate coefficients; establishing a nonlinear homogeneous equation system based on the functional relationship corresponding to each node using the simultaneous equation method, and obtaining the inlet flow rate and pressure difference of each node at the second time step using the Newton-Raphson iteration method based on the nonlinear homogeneous equation system; wherein, the inlet flow rate of the node includes the inlet flow rate of the centrifugal compressor.

[0009] Optionally, before adjusting the current candidate coefficient, the method further includes: calculating a second flow coefficient based on the blockage parameters of the centrifugal compressor; and calculating a first time corresponding to the second flow coefficient; adjusting the current candidate coefficient includes: increasing the current candidate coefficient if the first time corresponding to the second flow coefficient is not greater than the second time; wherein the adjusted candidate coefficient is less than the second flow coefficient.

[0010] Optionally, the method further includes: if the first time corresponding to the second flow coefficient is greater than the second time, then the second flow coefficient is determined as the flow coefficient of the anti-surge valve, and a second circuit is added; wherein the flow coefficient of the quick-opening valve in the second circuit is greater than the first flow coefficient.

[0011] Secondly, this application provides an anti-surge device for a centrifugal compressor system. The centrifugal compressor system includes a centrifugal compressor, process equipment, connecting pipelines, and an anti-surge valve. The flow coefficient of the anti-surge valve is obtained through the anti-surge device of the centrifugal compressor system. The device includes: a calculation module, used to calculate a first flow coefficient based on the surge parameters of the centrifugal compressor, and use the first flow coefficient as a current candidate coefficient; the calculation module is also used to calculate a first time corresponding to the current candidate coefficient, the first time being the time required for the inlet flow rate of the centrifugal compressor to change from an initial flow rate value to a lower flow rate limit value; wherein the initial flow rate value is less than the lower flow rate limit value, and the lower flow rate limit value is greater than the surge flow rate corresponding to the centrifugal compressor; a processing module, used to determine the current candidate coefficient as the flow coefficient of the anti-surge valve if the first time corresponding to the current candidate coefficient is not greater than a predetermined second time; otherwise, to adjust the current candidate coefficient and repeat the step of calculating the first time corresponding to the current candidate coefficient until the first time corresponding to the current candidate coefficient is not greater than the second time.

[0012] Optionally, the calculation module includes: a recording unit, configured to record the current time as the first time and set the inlet flow rate of the centrifugal compressor at the current time as the initial flow rate value; a calculation unit, configured to obtain the inlet flow rate of the centrifugal compressor at the second time under the current candidate coefficient for each second time after the first time; the calculation unit is further configured to calculate the duration between the first time and the current second time if the inlet flow rate of the centrifugal compressor at the second time reaches the lower limit value of the flow rate, and use this duration as the first time corresponding to the current candidate coefficient.

[0013] Optionally, the calculation unit is specifically used to, for each second time after the first time, obtain the system state parameters and the inlet pressure of each node of the centrifugal compressor system at the current second time based on the inlet flow rate, inlet pressure, and system state parameters of each node at the previous time; the calculation unit is further used to establish a functional relationship between the inlet flow rate and pressure difference at each node based on the inlet pressure of each node at the current second time, the system state parameters, and the attribute parameters of each node; wherein, the nodes of the centrifugal compressor system include components constituting the system path of the centrifugal compressor system, the components include a centrifugal compressor and an anti-surge valve, and the attribute parameters of the anti-surge valve are the current candidate coefficients; the calculation unit is further used to establish a nonlinear homogeneous equation system based on the functional relationship corresponding to each node through the simultaneous equation method, and obtain the inlet flow rate and pressure difference of each node at the second time through the Newton-Raphson iteration method according to the nonlinear homogeneous equation system; wherein, the inlet flow rate of the node includes the inlet flow rate of the centrifugal compressor.

[0014] Optionally, the calculation module is further configured to calculate a second flow coefficient based on the blockage parameters of the centrifugal compressor before the processing module adjusts the current candidate coefficient; and to calculate a first time corresponding to the second flow coefficient; specifically, the processing module is configured to increase the current candidate coefficient if the first time corresponding to the second flow coefficient is not greater than the second time; wherein the adjusted candidate coefficient is less than the second flow coefficient.

[0015] Optionally, the processing module is further configured to determine the second flow coefficient as the flow coefficient of the anti-surge valve and add a second circuit if the first time corresponding to the second flow coefficient is greater than the second time; wherein the flow coefficient of the quick-opening valve in the second circuit is greater than the first flow coefficient.

[0016] Thirdly, this application provides an electronic device, including: a processor, and a memory communicatively connected to the processor.

[0017] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the method described above.

[0018] In the anti-surge method, apparatus, electronic device, and medium for centrifugal compressor systems provided in this application embodiment, a first flow coefficient calculated based on the surge parameters of the centrifugal compressor is used as the current candidate coefficient. The first time required for the inlet flow rate of the centrifugal compressor to change from the initial flow rate value to the lower limit flow rate value under the current candidate coefficient is calculated. By comparing the first time and a predetermined second time, it is confirmed whether the candidate coefficient meets the operating condition requirements. If the requirements are met, the current candidate coefficient is determined as the flow coefficient of the anti-surge valve. If the requirements are not met, the current candidate coefficient is adjusted until the requirements are met. In this way, the rationality of the determined anti-surge valve flow coefficient is ensured, thereby ensuring the anti-surge effect of the centrifugal compressor. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with those of this application and, together with the description, serve to explain the principles of the embodiments of this application.

[0020] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the embodiments of this application in any way, but rather to illustrate the concepts of the embodiments of this application to those skilled in the art through reference to specific embodiments.

[0021] Figure 1 This is a flow characteristic curve of a centrifugal compressor;

[0022] Figure 2 This is a schematic diagram of the centrifugal compressor system.

[0023] Figure 3 This is a schematic flowchart of an anti-surge method for a centrifugal compressor system provided in Embodiment 1 of this application;

[0024] Figure 4 A schematic flowchart illustrating another anti-surge method for a centrifugal compressor system provided in Embodiment 1 of this application;

[0025] Figure 5 This is another flow characteristic curve for a centrifugal compressor;

[0026] Figure 6 This is a schematic diagram of another centrifugal compressor system in Embodiment 1 of this application;

[0027] Figure 7 This is a schematic diagram of the anti-surge device for a centrifugal compressor system provided in Embodiment 2 of this application;

[0028] Figure 8 This is a schematic diagram of the anti-surge device for another centrifugal compressor system provided in Embodiment 2 of this application;

[0029] Figure 9 This is a schematic diagram of the structure of the electronic device provided in Embodiment 5 of this application.

[0030] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0031] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0032] The technical solutions of this application will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. In the description of this application, unless otherwise expressly specified and limited, the terms should be broadly understood within the art. The embodiments of this application will now be described with reference to the accompanying drawings.

[0033] Surge is a relatively dangerous operating condition for centrifugal compressors. To prevent surge from occurring in centrifugal compressors, an anti-surge valve is often installed in the anti-surge circuit of the centrifugal compressor. The anti-surge valve is used to control the flow rate in the anti-surge circuit, thereby regulating the inlet flow rate of the centrifugal compressor so that the centrifugal compressor can escape the surge condition.

[0034] Centrifugal compressors are devices used to increase gas pressure. They are characterized by large displacement, high efficiency, and long continuous operating cycles, and are widely used in the petrochemical industry. A centrifugal compressor consists of a main shaft and an impeller that rotates with the main shaft. Its working principle is to use the centrifugal force generated by the high-speed rotating impeller to do work on the gas, increasing its velocity and pressure. When the inlet flow rate of a centrifugal compressor decreases to a certain value, boundary layer separation occurs at the working surface of the impeller. This causes gas to rotate and detach at the impeller, and some of the gas is not used for work by the impeller, resulting in a decrease in the centrifugal compressor outlet pressure. If the inlet flow rate of the centrifugal compressor decreases further, the rotating gas mass at the impeller will block the impeller passage, and the centrifugal compressor outlet pressure will drop significantly until it falls below the outlet pipeline pressure. At this point, the gas in the outlet pipeline flows back into the centrifugal compressor, replenishing the insufficient flow rate inside the centrifugal compressor. The impeller resumes normal work on the gas, compressing the gas that has flowed back into the stage again. This causes the flow rate inside the impeller to decrease again, the outlet pressure to drop again, and the gas to flow back into the pipeline again. This cycle repeats continuously, resulting in periodic low-frequency, large-amplitude airflow oscillations throughout the centrifugal compressor system, a phenomenon known as surge. Surge is one of the worst and most dangerous operating conditions for a centrifugal compressor.

[0035] When the flow rate of a centrifugal compressor increases to a certain extent, the negative angle of attack of the airflow becomes large, all the work done by the blades is converted into energy loss, the pressure no longer increases, and it is only used to maintain the airflow at that flow rate, or the speed of sound appears at the minimum cross-section of the flow channel, the boundary layer separation zone expands rapidly, and the pressure cannot be increased, and the flow rate no longer increases. This is called the blockage condition reached by the centrifugal compressor.

[0036] Under certain conditions, a centrifugal compressor experiences surge when its flow rate falls below a certain value. This value is the minimum flow rate of the centrifugal compressor, also known as the surge flow rate. Similarly, a centrifugal compressor experiences blockage when its flow rate exceeds a certain value, known as the blockage flow rate. Therefore, the surge flow rate is the minimum flow rate at which a centrifugal compressor can operate normally, while the blockage flow rate is the maximum flow rate that a centrifugal compressor can withstand. Figure 1 The flow characteristic curve of a centrifugal compressor, such as Figure 1 As shown, the curves illustrating the relationship between inlet flow rate and outlet pressure of a centrifugal compressor at different speeds are illustrated. Using the figure as an example, the third curve represents the relationship at a speed of 7001 r / min. Specifically, at a speed of n = 7001 r / min, point a is the surge condition point, and the flow rate corresponding to point a is the surge flow rate; point b is the blockage condition point, and the flow rate corresponding to point b is the blockage flow rate.

[0037] Continue to refer to Figure 1The line connecting the surge points at different speeds is called the surge line. An anti-surge line is set to the right of the surge line as the reference curve for the anti-surge valve. The area between the anti-surge line and the surge line is called the control margin. The line connecting the blockage points at different speeds is called the blockage line. An anti-blockage line is set to the left of the blockage line. The area between the anti-surge line and the anti-blockage line is the safe zone. When the operating point of the centrifugal compressor exceeds the anti-surge line, the anti-surge valve is opened to shift the operating point to the right into the safe zone, thereby preventing surge.

[0038] Figure 2 This is a schematic diagram of the anti-surge circuit of a centrifugal compressor, as shown below. Figure 2 As shown, to prevent surge in the centrifugal compressor 21, an anti-surge circuit 23 is typically installed between the outlet and inlet pipes of the centrifugal compressor 21, and the anti-surge valve 22 is located on the anti-surge circuit 23. When the anti-surge valve 22 is activated, the flow in the outlet pipe is returned to the inlet pipe of the centrifugal compressor 21 through the anti-surge circuit 23, thereby increasing the inlet flow of the centrifugal compressor 21 and thus preventing surge in the centrifugal compressor.

[0039] The anti-surge valve in the anti-surge circuit can control the backflow flow, and the flow coefficient determines the flow capacity of the anti-surge valve. Therefore, the flow coefficient of the anti-surge valve directly affects the anti-surge effect of the centrifugal compressor.

[0040] In related technologies, a flow coefficient is calculated based on the surge parameters at the surge point. This flow coefficient is then multiplied by an empirical coefficient to obtain an empirical value, which is used as the valve's flow coefficient. The anti-surge valve is then selected based on this flow coefficient. However, the range of this empirical coefficient is quite wide, and its value significantly affects the valve's flow coefficient. If the empirical coefficient is too small, the anti-surge valve's flow coefficient is too low, resulting in weak backflow capability and an inability to quickly relieve the centrifugal compressor from surge. If the empirical coefficient is too large, the anti-surge valve's flow coefficient is too high, leading to lower adjustment accuracy. Therefore, the above approach struggles to guarantee the appropriateness of the selected anti-surge valve's flow coefficient, thus failing to ensure the centrifugal compressor's anti-surge effect.

[0041] Some aspects of the embodiments of this application relate to the above considerations. The following examples illustrate the solutions.

[0042] Example 1

[0043] Figure 3 This is a schematic flowchart of an anti-surge method for a centrifugal compressor system provided in Embodiment 1 of this application, as shown below. Figure 3As shown in this embodiment, a method for preventing surge in a centrifugal compressor system is provided. The centrifugal compressor system includes a centrifugal compressor, process equipment, connecting pipelines, and an anti-surge valve. The flow coefficient of the anti-surge valve is obtained through the anti-surge method of the centrifugal compressor system. The method includes:

[0044] S301: Calculate the first flow coefficient based on the surge parameters of the centrifugal compressor, and use the first flow coefficient as the current candidate coefficient;

[0045] S302: Calculate the first time corresponding to the current candidate coefficient, where the first time is the time required for the inlet flow rate of the centrifugal compressor to change from the initial flow rate value to the lower flow rate limit value; wherein, the initial flow rate value is less than the lower flow rate limit value, and the lower flow rate limit value is greater than the surge flow rate corresponding to the centrifugal compressor;

[0046] S303: If the first time corresponding to the current candidate coefficient is not greater than the predetermined second time, then the current candidate coefficient is determined as the flow coefficient of the anti-surge valve; otherwise, the current candidate coefficient is adjusted, and the step of calculating the first time corresponding to the current candidate coefficient is executed again until the first time corresponding to the current candidate coefficient is not greater than the second time.

[0047] In practical applications, to ensure the stable operation of the centrifugal compressor, the centrifugal compressor system includes a centrifugal compressor, process equipment, connecting pipelines, and anti-surge valves. The process equipment may include heat exchangers, separators, or shut-off valves, etc. The centrifugal compressor, process equipment, and anti-surge valves are connected by connecting pipelines.

[0048] In this embodiment, surge parameters refer to the parameters corresponding to the surge point. Generally, the parameters of the surge point at the rated speed are used as surge parameters. Of course, in some variable speed operating conditions, the parameters of the surge point at the maximum or minimum speed can also be used as surge parameters. Surge parameters may include: inlet flow rate, inlet pressure, outlet pressure, etc. at the surge point.

[0049] The flow coefficient characterizes the flow capacity of a valve, and its calculation formula is: CV = f(Q, ΔP, T1, P1), where CV is the inlet flow rate of the anti-surge valve. When the inlet flow of the centrifugal compressor is interrupted, the anti-surge valve opens completely instantaneously, and all the outlet flow of the centrifugal compressor flows back. ΔP is the pressure difference between the inlet and outlet of the anti-surge valve. T1 is the current inlet temperature of the anti-surge valve. P1 is the inlet pressure of the anti-surge valve.

[0050] It's worth noting that the flow coefficient obtained from the above formula refers to the flow capacity that the valve needs to achieve at a certain operating point, and the larger the inlet flow rate at the operating point, the larger the flow coefficient. The first flow coefficient, on the other hand, is the flow capacity that the valve needs to achieve at the surge point. It can be understood that the first flow coefficient is the minimum flow coefficient of the valve. Therefore, using the first flow coefficient as the current candidate coefficient can be considered as obtaining the minimum value of the current candidate coefficient.

[0051] After determining the candidate coefficients, an initial flow rate and a lower flow rate limit are set. The initial flow rate is less than the lower flow rate limit, and the lower flow rate limit is greater than the surge flow rate corresponding to the centrifugal compressor. In practical applications, the initial flow rate can be set between the surge line and the anti-surge line, and the lower flow rate limit can be set to be no less than the control flow rate corresponding to the anti-surge line. For example, the initial flow rate is set to the surge flow rate, the lower flow rate limit is set to the control flow rate, and the first time is the time required to adjust the inlet flow rate from the surge flow rate to the control flow rate. For the current candidate coefficients, the first time required for the centrifugal compressor's inlet flow rate to change from the initial flow rate to the lower flow rate limit is calculated.

[0052] The calculation process for the first time step will be illustrated below.

[0053] Figure 4 A schematic flowchart of another anti-surge method for a centrifugal compressor system provided in Embodiment 1 of this application is shown below. Figure 4 As shown, the calculation of the first time corresponding to the current candidate coefficient in S302 includes:

[0054] S401: Record the current time as the first time, and set the inlet flow rate of the centrifugal compressor at the current time as the initial flow rate value;

[0055] S402: For each second time after the first time, obtain the inlet flow rate of the centrifugal compressor at the second time under the current candidate coefficient;

[0056] S403: If the inlet flow rate of the centrifugal compressor at the second moment reaches the lower limit of the flow rate, then calculate the duration between the first moment and the current second moment, and use it as the first time corresponding to the current candidate coefficient.

[0057] In this example, the initial flow rate at the centrifugal compressor inlet at the first moment is recorded. This first moment can be understood as the moment the anti-surge valve begins to operate, and from this moment on, the inlet flow rate starts to increase. Then, the inlet flow rate of the centrifugal compressor at each second moment under the current candidate coefficients is obtained. The interval between any two adjacent second moments can be equal, and the length of the interval can be set according to specific circumstances. A longer interval results in faster calculations, while a shorter interval yields more accurate first-time values.

[0058] When the inbound traffic at the second moment reaches the set lower limit, the duration from the first moment to the current second moment is calculated, and this duration is taken as the first moment. For example, the first moment can be obtained by accumulating the intervals between all adjacent moments from the first moment to the current second moment.

[0059] Let's illustrate this with a specific example: Record the first moment as t0 and its corresponding initial flow rate as Q0, and set the lower limit of the flow rate as Q. m The interval between each adjacent time point is 0.2s. Calculate the inlet flow rate Q1 of the centrifugal compressor at the first second time point t1 under the current candidate coefficient, then calculate the inlet flow rate Q2 of the centrifugal compressor at the second second time point t2, and so on, until the inlet flow rate Q6 at the sixth second time point t6 is equal to Q. m By summing up the six intervals from t0 to t6, the first time is found to be 1.2s.

[0060] In this example, the inbound traffic is calculated for each second time point until the inbound traffic equals the lower limit of the traffic. The duration between the current second time point and the first time point is taken as the first time point. This solution provides a reliable way to calculate the first time point.

[0061] The following is an exemplary description of S402 in the above scheme. S402 includes:

[0062] For each second time after the first time, based on the flow rate, inlet pressure and system state parameters of each node of the centrifugal compressor system at the previous time, the system state parameters and the inlet pressure of each node at the current second time are obtained;

[0063] Based on the inlet pressure of each node at the current second moment, the system state parameters, and the attribute parameters of each node, a functional relationship between the flow rate and the inlet / outlet pressure difference at each node is established; wherein, the nodes of the centrifugal compressor system include the components constituting the system path of the centrifugal compressor system, the components include the centrifugal compressor and the anti-surge valve, and the attribute parameters of the anti-surge valve are the current candidate coefficients;

[0064] By using the simultaneous equations method, a nonlinear homogeneous system of equations is established based on the functional relationship corresponding to each node. Then, based on the nonlinear homogeneous system of equations, the flow rate and node pressure difference of each node at the second time moment are obtained by the Newton-Raphson iteration method. The flow rate of the node includes the inlet flow rate of the centrifugal compressor.

[0065] In this example, each component of the centrifugal compressor system can be considered a node. For example, a node may include the centrifugal compressor, anti-surge valve, connecting pipelines, heat exchanger, and separator. The number of nodes depends on the system configuration. Each node affects the gas flow in the entire compressor system due to its own characteristics. For instance, in the case of connecting pipelines, the gas flow within the pipelines is affected by frictional resistance or local resistance, thus impacting the system's flow rate. Therefore, this example considers the impact of each node on the entire centrifugal compressor system. Based on this, the inlet flow rate of the centrifugal compressor at the second time point is obtained, thereby improving the reasonableness and accuracy of the calculation results.

[0066] In practical applications, for each second time point after the first time point, the system state parameters and the inlet pressure of each node are obtained based on the flow rate, inlet pressure, and system state parameters of each node in the centrifugal compressor system at the previous time point. The system state parameters characterize the gas state within the system. For example, gas state parameters may include the enthalpy of the gas, temperature, and the amount of each component in the gas present in the node.

[0067] For example, regarding the method of obtaining the system state parameters and the inlet pressure of each node at the current second time step, the i-th second time step t... i Inlet pressure P at each node below i =P i-1 +ΔP i-1 (i≥1), where P i-1 For t i-1 The inlet pressure at the node at time ΔP i-1 For t i-1 Time to t i The change in inlet pressure at any given time. For each node, based on t i-1 By obtaining the flow rate through each node and the system state parameters at each moment, and solving the material and energy balance differential equations using the Euler method, dP can be obtained. i-1 / dt=f(P i-1 V, T i-1 Q i-1 H i-1 ), where V is the effective volume of each node, and T i-1 For t i-1 The temperature of the gas at that moment, Q i-1 For ti-1 The traffic flowing through the node at a given time, H i-1 For t i-1 The enthalpy of the gas at time t. For each node, ΔP can be obtained using the above formula. i-1 Then, t can be obtained. i The inlet pressure P at that moment i .

[0068] Regarding the system state parameters, according to the gas law, at t i The inlet pressure P at that moment i When the effective volume V of each node is known, then t can be obtained. i The system state parameters at a given time.

[0069] It is worth noting that at the first moment t0, all system state parameters, including the inlet pressure and flow rate of each node, are known.

[0070] Subsequently, based on the inlet pressure, system state parameters, and attribute parameters of each node at the current second time point, a functional relationship between flow rate and pressure difference is established for each node. The attribute parameters of a node are its own characteristics and parameters that affect the system. For example, for connecting pipelines, the attribute parameter is the resistance coefficient of the connecting pipeline. For valves, the attribute parameter is the flow coefficient; for anti-surge valves, the attribute parameter is the current candidate coefficient. For centrifugal compressors, the attribute parameter is their flow characteristic curve. The pressure difference of a node is the difference between the inlet pressure and the outlet pressure of the node.

[0071] The following example illustrates the establishment of the functional relationship between flow rate and pressure difference at each node, using specific application scenarios: In a centrifugal compressor system, for nodes such as connecting pipelines or heat exchangers, the functional relationship between flow rate and pressure difference is: Q = f(ζ, P1, T1, ΔP), where ζ is the resistance coefficient of the pipeline or heat exchanger, P1 is the inlet pressure at the current second moment, T1 is the gas temperature at the current second moment, Q is the flow rate through the pipeline or heat exchanger at the current second moment, and ΔP is the pressure difference of the node at the current second moment.

[0072] For valve-type nodes, such as anti-surge valves or check valves, the functional relationship between flow rate and pressure difference for these nodes is: Q = f(Cv, P1, T1, ΔP), where Cv is the flow coefficient of the valve (note that the flow coefficient of the anti-surge valve is a candidate coefficient), P1 is the inlet pressure at the current second moment, T1 is the gas temperature at the current second moment, Q is the flow rate through the valve at the current second moment, and Δp is the pressure difference of the node at the current second moment.

[0073] For a centrifugal compressor, the functional relationship between flow rate and pressure difference is: Q = f(Curve, P1, T1, ΔP), where P1 is the compressor inlet pressure at the current second moment, T1 is the compressor inlet gas temperature at the current second moment, Q is the flow rate through the compressor at the current second moment, and ΔP is the pressure difference at the node at the current second moment. Curve represents the performance curve of the centrifugal compressor. Figure 5 This is a performance curve for a centrifugal compressor; the curve can be referenced as follows: Figure 5 The curve shown is the characteristic curve of compression ratio versus inlet flow rate, where the compression ratio is the ratio of the centrifugal compressor's outlet pressure to its inlet pressure. At a constant rotational speed, the compressor's compression ratio decreases as the inlet flow rate increases. Given a known compression ratio, the corresponding compressor inlet flow rate can be obtained. This can be understood based on... Figure 5 The curve shown can be used to establish the functional relationship between the inlet flow rate and the pressure difference of the centrifugal compressor.

[0074] In practical applications, when the anti-surge valve is not open, there is a pressure difference between its inlet and outlet. After the anti-surge valve opens, the fluid in the anti-surge circuit begins to flow due to the pressure difference. As the fluid flows, the pressure difference at each node changes, and the change in pressure difference at each node affects the flow rate through each node at the next moment. Therefore, in the entire centrifugal compressor system, the pressure difference and flow rate at each node are iterative variables.

[0075] Therefore, by using the simultaneous equation method, a nonlinear homogeneous equation system is established based on the functional relationship corresponding to each node. Then, using the Newton-Raphson iteration method, the inlet flow rate and node pressure difference of each node at the second time step are obtained from the nonlinear homogeneous equation system. The inlet flow rate of each node includes the inlet flow rate of the centrifugal compressor.

[0076] In this example, when calculating the inlet flow rate at the second moment, the influence of the characteristics of each node on the entire system is considered. The calculation scenario is closer to the actual working conditions, making the obtained inlet flow rate at the second moment more accurate, improving the rationality of the flow coefficient, and thus improving the anti-surge effect of the centrifugal compressor system.

[0077] The following will further explain S303. After calculating the first time, the first time is compared with a predetermined second time. The predetermined second time can be set according to the stroke time requirements of the anti-surge valve as specified by industry standards, or it can be set according to the anti-surge capability of the centrifugal compressor itself. In practical applications, surge occurs very rapidly, with a surge cycle possibly lasting only about 1 second. Therefore, the anti-surge valve must operate quickly to ensure the safety of the centrifugal compressor system. Generally, the industry requires the anti-surge valve to remove the centrifugal compressor from the surge zone within 2 seconds. Therefore, for example, the second time can be set to 1.8 seconds.

[0078] Based on the above comparison results, if the first time is not greater than the second time, it can be understood that the current flow coefficient can enable the centrifugal compressor to escape surge within a predetermined time, and the current flow coefficient is determined as the flow coefficient of the anti-surge valve. If the first time corresponding to the current candidate coefficient is greater than the predetermined second time, it can be understood that the current candidate coefficient cannot enable the centrifugal compressor to escape surge within a predetermined time, and the current candidate coefficient needs to be adjusted, and the corresponding first time needs to be recalculated until the first time corresponding to the current candidate coefficient is not greater than the second time.

[0079] For the scenario where the current first time is less than the predetermined second time, before adjusting the current candidate coefficients, the following may also be included:

[0080] Based on the blockage parameters of the centrifugal compressor, a second flow coefficient is calculated; and a first time corresponding to the second flow coefficient is calculated.

[0081] The adjustment of the current candidate coefficients includes:

[0082] If the first time corresponding to the second flow coefficient is not greater than the second time, then the current candidate coefficient is increased; wherein the adjusted candidate coefficient is less than the second flow coefficient.

[0083] The blocking parameters are the parameters of the blocking point. In practical applications, the parameters of the blocking point at rated speed are generally used as the blocking parameters. These blocking parameters may include: inlet flow rate, inlet pressure, and outlet pressure at the blocking point, such as... Figure 1 In the diagram, the parameters corresponding to point b are used. Applying the flow coefficient calculation formula again: CV=f(Q,ΔP,T1,P1), based on the blocking parameters, the second flow coefficient is calculated. It can be understood that the second flow coefficient is the maximum flow coefficient of the anti-surge valve.

[0084] To illustrate with a practical application, the first time is calculated based on the second flow coefficient under the blocking parameters. If the first time is not greater than the second time, it can be understood that there must exist a relatively minimum flow coefficient that allows the centrifugal compressor to escape surge within a predetermined time. If the first time is still greater than the second time, it means that no matter how it is adjusted, a flow coefficient that allows the centrifugal compressor to escape surge within a predetermined time cannot be obtained. Therefore, this solution can avoid ineffective adjustments.

[0085] If the first time interval is not greater than the second time interval, starting from the first flow coefficient, the current candidate coefficient is gradually increased until the first time interval corresponding to the current candidate coefficient is not greater than the second time interval. This current candidate coefficient is then determined as the flow coefficient of the anti-surge valve. It can be understood that the candidate coefficient gradually increases from the first flow coefficient, so the finally determined flow coefficient is the minimum flow coefficient that can ensure the centrifugal compressor can escape surge. Therefore, the current candidate coefficient is the most reasonable flow coefficient for the anti-surge valve.

[0086] In this embodiment, before adjusting the candidate coefficient, it is first verified whether the requirement that the second largest flow coefficient does not exceed the second time is met. If the requirement is not met, no further adjustment is made. If the requirement is met, the current candidate coefficient is increased. Therefore, this solution avoids ineffective adjustment and finds the most reasonable flow coefficient by gradually increasing the adjustment method.

[0087] In the process of gradually increasing the current candidate coefficient, one approach is to adjust the current candidate coefficient in predetermined steps. For example, each time, the previous candidate coefficient is increased by 10, which becomes the current candidate coefficient. It is worth noting that, if this implementation method is adopted, after the first time is no greater than the second time, based on the current candidate coefficient, the valve whose flow coefficient is closest to the current candidate coefficient is selected as the final anti-surge valve from the valve product series list shown in Table 1.

[0088] Another approach is to directly adjust the current candidate coefficients based on the flow coefficients in the valve product series list shown in Table 1. For example, if the first flow coefficient is 830, adjust the candidate coefficients to use the flow coefficient of model 2 (980) as the candidate coefficient. If further adjustment is needed, use the flow coefficient of specification 3 (1200) as the current candidate coefficient. Using this implementation method, after the first time is no greater than the second time, the valve with the current candidate flow coefficient can be directly selected as the final valve.

[0089] Table 1 Valve Product Series

[0090] model CV Specification 1 830 DN300 2 980 DN350 3 1200 DN400 4 1480 DN450 5 1710 DN500 6 1900 DN550 ….. ….. …..

[0091] Furthermore, in scenarios where the first time corresponding to the second flow coefficient is greater than the second time, the second flow coefficient can be determined as the flow coefficient of the anti-surge valve, and a second circuit can be added; wherein, the flow coefficient of the quick-opening valve in the second circuit is greater than the first flow coefficient.

[0092] Figure 6 This is a schematic diagram of another anti-surge circuit for a centrifugal compressor in Embodiment 1 of this application, as shown below. Figure 6As shown, the centrifugal compressor 21 has a first separator 63 at its inlet and a heat exchanger 64 and a second separator 65 at its outlet. In cases where the anti-surge valve 22 cannot achieve the desired anti-surge effect, a second circuit 61 is added between the first separator 63 and the second separator 64. A quick-opening valve 62 is installed on the second circuit 61. The flow coefficient of the quick-opening valve 62 is greater than the first flow coefficient, which is then used as the flow coefficient of the anti-surge valve 22. When surge occurs in the centrifugal compressor, both the anti-surge valve 22 and the quick-opening valve 62 can be opened simultaneously. This allows the outlet flow of the centrifugal compressor 21 to quickly flow back to the inlet, increasing the inlet flow and enabling the centrifugal compressor 21 to quickly recover from surge, thus ensuring the safe operation of the centrifugal compressor 21.

[0093] The following will illustrate this embodiment with examples. Based on the surge parameters of the centrifugal compressor, the first flow coefficient is obtained as 825, and the initial flow rate is set to 45372 m³ / h. 3 / h, the lower limit of the flow rate is 54433.2m³ / h. 3 / h, the scheduled second time is 2s.

[0094] Record the first time point t0 and the initial flow rate 45372m. 3 / h. Using the first flow coefficient as the current candidate coefficient, the inlet flow rate at the 22nd second time step is calculated to be equal to the lower flow limit of 54433.2 m³ / h. 3 / h.

[0095] Calculate t0 to t 22 The duration is calculated as follows: the interval between each moment is 0.1s, and the first moment is calculated to be 2.2s.

[0096] Since the first time interval (2.2s) is greater than the second time interval (2s), and based on the blocking parameters of blockage point b, the second flow coefficient is calculated to be 1895. Using this second flow coefficient as the current candidate coefficient, the first time interval is calculated again using the method described above. That is, the inlet flow rate at the 12th second time interval t12 is equal to the lower flow limit of 54433.2 m³. 3 / h, the first time is calculated to be 1.2s.

[0097] The first time (1.2s) is less than the second time (2s). Based on the first flow coefficient of 825, the current candidate coefficient is gradually increased in steps of 10. Calculations show that when the candidate coefficient is 1465, the first time is less than the second time. Based on the candidate coefficient of 1465 and in conjunction with the valve product series table, the valve with a flow coefficient of 1480 is selected as the final anti-surge valve.

[0098] In the anti-surge method for a centrifugal compressor system provided in this embodiment, a first flow coefficient calculated based on the surge parameters of the centrifugal compressor is used as the current candidate coefficient. The first time required for the inlet flow rate of the centrifugal compressor to change from the initial flow rate value to the lower limit flow rate value under the current candidate coefficient is calculated. By comparing the first time and a predetermined second time, it is confirmed whether the candidate coefficient meets the operating requirements. If the requirements are met, the current candidate coefficient is determined as the flow coefficient of the anti-surge valve. If the requirements are not met, the current candidate coefficient is adjusted until the requirements are met. In this way, the rationality of the determined anti-surge valve flow coefficient is ensured, thereby ensuring the anti-surge effect of the centrifugal compressor.

[0099] Example 2

[0100] Figure 7 This is a schematic diagram of the anti-surge device for a centrifugal compressor system provided in Embodiment 2 of this application, as shown below. Figure 7 As shown in this embodiment, the anti-surge device for a centrifugal compressor system includes a centrifugal compressor, process equipment, connecting pipelines, and an anti-surge valve. The flow coefficient of the anti-surge valve is obtained through the anti-surge device of the centrifugal compressor system. The device includes:

[0101] Calculation module 71 is used to calculate a first flow coefficient based on the surge parameters of the centrifugal compressor, and use the first flow coefficient as the current candidate coefficient;

[0102] The calculation module 71 is also used to calculate the first time corresponding to the current candidate coefficient, wherein the first time is the time required for the inlet flow rate of the centrifugal compressor to change from the initial flow rate value to the lower flow rate limit value; wherein the initial flow rate value is less than the lower flow rate limit value, and the lower flow rate limit value is greater than the surge flow rate corresponding to the centrifugal compressor;

[0103] The processing module 72 is configured to determine the current candidate coefficient as the flow coefficient of the anti-surge valve if the first time corresponding to the current candidate coefficient is not greater than a predetermined second time; otherwise, adjust the current candidate coefficient and execute the step of calculating the first time corresponding to the current candidate coefficient again until the first time corresponding to the current candidate coefficient is not greater than the second time.

[0104] In practical applications, to ensure the stable operation of the centrifugal compressor, the centrifugal compressor system includes a centrifugal compressor, process equipment, connecting pipelines, and anti-surge valves. The process equipment may include heat exchangers, separators, or shut-off valves. The centrifugal compressor, process equipment, and anti-surge valves are connected by connecting pipelines.

[0105] In this embodiment, surge parameters refer to the parameters corresponding to the surge point. Generally, the parameters of the surge point at the rated speed are used as surge parameters. Of course, in some variable speed operating conditions, the parameters of the surge point at the maximum or minimum speed can also be used as surge parameters. Surge parameters may include: inlet flow rate, inlet pressure, outlet pressure, etc. at the surge point.

[0106] The flow coefficient characterizes the flow capacity of a valve, and its calculation formula is: CV = f(Q, ΔP, T1, P1), where CV is the inlet flow rate of the anti-surge valve. When the inlet flow of the centrifugal compressor is interrupted, the anti-surge valve opens completely instantaneously, and all the outlet flow of the centrifugal compressor flows back. ΔP is the pressure difference between the inlet and outlet of the anti-surge valve. T1 is the current inlet temperature of the anti-surge valve. P1 is the inlet pressure of the anti-surge valve.

[0107] It is worth noting that the flow coefficient obtained by calculation module 71 based on the above formula refers to the flow capacity that the valve needs to achieve at a certain operating point, and the larger the inlet flow rate corresponding to the operating point, the larger the flow coefficient. The first flow coefficient, on the other hand, is the flow capacity that the valve needs to achieve at the surge point. It can be understood that the first flow coefficient is the minimum flow coefficient of the valve. Therefore, using the first flow coefficient as the current candidate coefficient can be considered as obtaining the minimum value of the current candidate coefficient.

[0108] After determining the candidate coefficients, an initial flow rate and a lower flow rate limit are set. The initial flow rate is less than the lower flow rate limit, and the lower flow rate limit is greater than the surge flow rate corresponding to the centrifugal compressor. In practical applications, the initial flow rate can be set between the surge line and the anti-surge line, and the lower flow rate limit can be set to be no less than the control flow rate corresponding to the anti-surge line. For example, the initial flow rate is set to the surge flow rate, the lower flow rate limit is set to the control flow rate, and the first time is the time required to adjust the inlet flow rate from the surge flow rate to the control flow rate.

[0109] For the current candidate coefficients, the calculation module 71 calculates the first time required for the inlet flow rate of the centrifugal compressor to change from the initial flow rate value to the lower limit of the flow rate value.

[0110] The calculation module 71 will be described below as an example.

[0111] Figure 8 This is a schematic diagram of the anti-surge device for another centrifugal compressor system provided in Embodiment 2 of this application, as shown below. Figure 8 As shown, the calculation module 71 includes:

[0112] The recording unit 711 is used to record the current time as the first time and set the inlet flow rate of the centrifugal compressor at the current time as the initial flow rate value;

[0113] The calculation unit 712 is used to obtain the inlet flow rate of the centrifugal compressor at the second time for each second time after the first time;

[0114] The calculation unit 712 is further configured to calculate the duration between the first time and the current second time if the inlet flow rate of the centrifugal compressor at the second time reaches the lower flow rate limit, and use this duration as the first time corresponding to the current candidate coefficient.

[0115] In this example, the recording unit 711 first records the first moment and the initial flow rate value at the centrifugal compressor inlet corresponding to that moment. The first moment can be understood as the moment the anti-surge valve begins to operate; from that moment on, the inlet flow rate starts to increase. Then, the calculation unit 712 obtains the centrifugal compressor inlet flow rate for each second moment under the current candidate coefficients. The interval between any two adjacent second moments can be equal, and the length of the interval can be set according to specific circumstances. A longer interval results in faster calculations, while a shorter interval yields higher accuracy for the first moment.

[0116] When the inbound traffic at the second moment reaches the set lower limit, the duration from the first moment to the current second moment is calculated, and this duration is taken as the first moment. For example, the first moment can be obtained by accumulating the intervals between all adjacent moments from the first moment to the current second moment.

[0117] Let's illustrate this with a specific example: Record the first moment as t0 and its corresponding initial flow rate as Q0, and set the lower limit of the flow rate as Q. m The interval between each adjacent time point is 0.2s. Calculate the inlet flow rate Q1 of the centrifugal compressor at the first second time point t1 under the current candidate coefficient, then calculate the inlet flow rate Q1 of the centrifugal compressor at the second second time point t2, and so on, until the inlet flow rate Q6 at the sixth second time point t6 is equal to Q. m By summing up the six intervals from t0 to t6, the first time is found to be 1.2s.

[0118] In this example, the calculation unit 712 calculates the inbound flow at each second time point until the inbound flow equals the lower limit of the flow, and takes the duration between the current second time point and the first time point as the first time point. This solution provides a reliable way to calculate the first time point.

[0119] The calculation unit 712 in the above scheme will be described below as an example. In one example, the calculation unit 712 includes:

[0120] The calculation unit 712 is specifically used to obtain the system state parameters and the inlet pressure of each node at the current second moment for each second moment after the first moment, based on the inlet flow rate, inlet pressure and system state parameters of each node of the centrifugal compressor system at the previous moment.

[0121] The calculation unit 712 is further configured to establish a functional relationship between the inlet flow rate and the inlet / outlet pressure difference at each node based on the inlet pressure of each node at the current second time point, the system state parameters, and the attribute parameters of each node; wherein, the nodes of the centrifugal compressor system include components constituting the system path of the centrifugal compressor system, the components include a centrifugal compressor and an anti-surge valve, and the attribute parameters of the anti-surge valve are the current candidate coefficients;

[0122] The calculation unit 712 is further configured to establish a nonlinear homogeneous equation system based on the functional relationship corresponding to each node using the simultaneous equation method, and obtain the inlet flow rate and pressure difference of each node at the second time step using the Newton-Raphson iteration method based on the nonlinear homogeneous equation system; wherein, the inlet flow rate of the node includes the inlet flow rate of the centrifugal compressor.

[0123] In this example, each component of the centrifugal compressor system can be considered a node. For example, a node may include the centrifugal compressor, anti-surge valve, connecting pipelines, heat exchanger, and separator. The number of nodes depends on the system configuration. Each node affects the fluid flow in the entire compressor system due to its own characteristics. For instance, in the case of connecting pipelines, the flow of gas within the pipelines is affected by frictional resistance or local resistance, thus impacting the system's flow rate. Therefore, this example considers the impact of each node on the entire centrifugal compressor system. Based on this, the inlet flow rate of the centrifugal compressor at the second time point is obtained to improve the reasonableness and accuracy of the calculation results.

[0124] In practical applications, for each second moment after the first moment, the calculation unit 712 obtains the system state parameters and the inlet pressure of each node at the current second moment based on the flow rate, inlet pressure, and system state parameters of each node in the centrifugal compressor system at the previous moment. The system state parameters are parameters characterizing the gas state within the system. For example, gas state parameters may include the enthalpy of the gas, temperature, and the amount of each component in the gas present in the node.

[0125] For the method of obtaining the system state parameters and the inlet pressure of each node at the current second time step, for example, the current i-th second time step t i Inlet pressure P at each node below i =P i-1+ΔP i-1 (i≥1), where P i-1 For t i-1 The inlet pressure at the node at time ΔP i-1 For t i-1 Time to t i The change in inlet pressure at any given time. For each node, based on t i-1 By obtaining the flow rate through each node and the system state parameters at each moment, and solving the material and energy balance differential equations using the Euler method, dP can be obtained. i-1 / dt=f(P i-1 V, T i-1 Q i-1 H i-1 ), where V is the effective volume of each node, and T i-1 For t i-1 The temperature of the gas at that moment, Q i-1 For t i-1 The traffic flowing through the node at a given time, H i-1 For t i-1 The enthalpy of the gas at time t. For each node, ΔP can be obtained using the above formula. i-1 Then, t can be obtained. i The inlet pressure P at that moment i .

[0126] Regarding the system state parameters, according to the ideal gas law, at t i The inlet pressure P at that moment i When the effective volume V of each node is known, then t can be obtained. i The system state parameters at a given time.

[0127] It is worth noting that at the first moment t0, all system state parameters, including the inlet pressure and flow rate of each node, are known.

[0128] Subsequently, the calculation unit 712 establishes a functional relationship between flow rate and pressure difference for each node based on the inlet pressure, system state parameters, and attribute parameters of each node at the current second time point. The attribute parameters of a node are its own characteristics and parameters that affect the system. For example, for connecting pipelines, the attribute parameter is the resistance coefficient of the connecting pipeline. For valve components, the attribute parameter is the flow coefficient; for anti-surge valves, the attribute parameter is the current candidate coefficient. For centrifugal compressors, the attribute parameter is their flow characteristic curve. The pressure difference of a node is the difference between the inlet pressure and the outlet pressure of the node.

[0129] The following example illustrates the establishment of the functional relationship between flow rate and pressure difference at each node, using specific application scenarios: In a centrifugal compressor system, for nodes such as connecting pipelines or heat exchangers, the functional relationship between flow rate and pressure difference is: Q = f(ζ, P1, T1, ΔP), where ζ is the resistance coefficient of the pipeline or heat exchanger, P1 is the inlet pressure at the current second moment, T1 is the gas temperature at the current second moment, Q is the flow rate through the pipeline or heat exchanger at the current second moment, and ΔP is the pressure difference of the node at the current second moment.

[0130] For valve-type nodes, such as anti-surge valves or check valves, the functional relationship between flow rate and pressure difference for these nodes is: Q = f(Cv, P1, T1, ΔP), where Cv is the flow coefficient of the valve (note that the flow coefficient of the anti-surge valve is a candidate coefficient), P1 is the inlet pressure at the current second moment, T1 is the gas temperature at the current second moment, Q is the flow rate through the valve at the current second moment, and ΔP is the pressure difference of the node at the current second moment.

[0131] For a centrifugal compressor, the functional relationship between flow rate and pressure difference is: Q = f(Curve, T1, P1, ΔP), where P1 is the compressor inlet pressure at the current second moment, T1 is the compressor inlet gas temperature at the current second moment, Q is the flow rate through the compressor at the current second moment, and ΔP is the pressure difference at the node at the current second moment. Curve represents the performance curve of the centrifugal compressor. Figure 5 This is a performance curve for a centrifugal compressor; the curve can be referenced as follows: Figure 5 The curve shown is the characteristic curve of compression ratio versus inlet flow rate, where the compression ratio is the ratio of the centrifugal compressor's outlet pressure to its inlet pressure. At a constant rotational speed, the compressor's compression ratio decreases as the inlet flow rate increases. Given a known compression ratio, the corresponding compressor inlet flow rate can be obtained. This can be understood based on... Figure 5 The curve shown can be used to establish the functional relationship between the inlet flow rate and the pressure difference of the centrifugal compressor.

[0132] In practical applications, when the anti-surge valve is not open, there is a pressure difference between its inlet and outlet. After the anti-surge valve opens, the fluid in the anti-surge circuit begins to flow due to the pressure difference. As the fluid flows, the pressure difference at each node changes, where the pressure difference at each node is the difference between the inlet and outlet pressures of that node. The change in pressure difference at each node, in turn, affects the flow rate through each node. Therefore, in the entire centrifugal compressor system, the pressure difference and flow rate at each node are iterative variables.

[0133] Therefore, by using the simultaneous equation method, a nonlinear homogeneous equation system is established based on the functional relationship corresponding to each node. Then, using the Newton-Raphson iteration method, the inlet flow rate and node pressure difference of each node at the second time step are obtained from the nonlinear homogeneous equation system. The inlet flow rate of each node includes the inlet flow rate of the centrifugal compressor.

[0134] In this example, when calculating the inlet flow rate at the second moment, the computing unit considers the impact of the characteristics of each node on the entire system. The calculation scenario is closer to the actual working conditions, making the obtained inlet flow rate at the second moment more accurate, improving the rationality of the flow coefficient, and thus improving the anti-surge effect of the centrifugal compressor system.

[0135] The following will further explain the processing module 72. After the calculation module 71 calculates the first time, it compares the first time with a predetermined second time. The predetermined second time can be set according to the stroke time requirements of the anti-surge valve as specified in the industry, or it can be set according to the anti-surge capability of the centrifugal compressor itself. In practical applications, surge occurs very rapidly, and a surge cycle may only take about 1 second. Therefore, the anti-surge valve must act quickly to ensure the safety of the centrifugal compressor system. Generally, the industry requires the anti-surge valve to remove the centrifugal compressor from the surge zone within 2 seconds. Therefore, for example, the second time can be set to 1.8 seconds.

[0136] Based on the above comparison results, if the first time is not greater than the second time, it can be understood that the current flow coefficient can enable the centrifugal compressor to escape surge within a predetermined time, and the current flow coefficient is determined as the flow coefficient of the anti-surge valve. If the first time corresponding to the current candidate coefficient is greater than the predetermined second time, it can be understood that the current candidate coefficient cannot enable the centrifugal compressor to escape surge within a predetermined time, and the current candidate coefficient needs to be adjusted, and the corresponding first time needs to be recalculated until the first time corresponding to the current candidate coefficient is not greater than the second time.

[0137] In the scenario where the current first time is less than the predetermined second time, the calculation module 71 is further configured to calculate and obtain the second flow coefficient based on the blockage parameters of the centrifugal compressor before the processing module 72 adjusts the current candidate coefficient; and to calculate the first time corresponding to the second flow coefficient.

[0138] The processing module 72 is specifically used to increase the current candidate coefficient if the first time corresponding to the second flow coefficient is not greater than the second time; wherein the adjusted candidate coefficient is less than the second flow coefficient.

[0139] The blocking parameters are the parameters of the blocking point. In practical applications, the parameters of the blocking point at rated speed are generally used as the blocking parameters. These blocking parameters may include: inlet flow rate, inlet pressure, and outlet pressure at the blocking point, such as... Figure 1 In the middle, the parameters corresponding to point b. Applying the flow coefficient calculation formula again: CV=f(Q,ΔP,T1,P1), the calculation module 71 calculates the second flow coefficient based on the blocking parameters. It can be understood that the second flow coefficient is the maximum flow coefficient of the anti-surge valve.

[0140] To illustrate with a practical application, the calculation module 71 calculates the first time based on the second flow coefficient under the blocking parameters. If the first time is not greater than the second time, it can be understood that there must exist a relatively minimum flow coefficient that can allow the centrifugal compressor to escape surge within a predetermined time. If the first time is still greater than the second time, it means that no matter how it is adjusted, a flow coefficient that can allow the centrifugal compressor to escape surge within a predetermined time cannot be obtained. Therefore, this solution can avoid ineffective adjustments.

[0141] If the first time interval is not greater than the second time interval, the calculation module 71 starts from the first flow coefficient and gradually increases the current candidate coefficient until the first time interval corresponding to the current candidate coefficient is not greater than the second time interval. The current candidate coefficient is then determined as the flow coefficient of the anti-surge valve. It can be understood that the candidate coefficient gradually increases from the first flow coefficient, so the finally determined flow coefficient is the minimum flow coefficient that can ensure the centrifugal compressor can escape surge. Therefore, the current candidate coefficient is the most reasonable flow coefficient for the anti-surge valve.

[0142] In this embodiment, before adjusting the candidate coefficient, it is first verified whether the requirement that the second largest flow coefficient does not exceed the second time is met. If the requirement is not met, no further adjustment is made. If the requirement is met, the current candidate coefficient is increased. Therefore, this solution avoids ineffective adjustment and finds the most reasonable flow coefficient by gradually increasing the adjustment method.

[0143] In addition, the processing module 72 is also used to determine the second flow coefficient as the flow coefficient of the anti-surge valve in a scenario where the first time corresponding to the second flow coefficient is greater than the second time, and to add a second circuit; wherein the flow coefficient of the quick-opening valve in the second circuit is greater than the first flow coefficient.

[0144] Figure 6 This is a schematic diagram of another anti-surge circuit for a centrifugal compressor in Embodiment 1 of this application, as shown below. Figure 6As shown, the centrifugal compressor 21 has a first separator 63 at its inlet and a heat exchanger 64 and a second separator 65 at its outlet. In cases where the anti-surge valve 22 cannot achieve the desired anti-surge effect, a second circuit 61 is added between the first separator 63 and the second separator 64. A quick-opening valve 62 is installed on the second circuit 61. The flow coefficient of the quick-opening valve 62 is greater than the first flow coefficient, which is then used as the flow coefficient of the anti-surge valve 22. When surge occurs in the centrifugal compressor, both the anti-surge valve 22 and the quick-opening valve 62 can be opened simultaneously. This allows the outlet flow of the centrifugal compressor 21 to quickly flow back to the inlet, increasing the inlet flow and enabling the centrifugal compressor 21 to quickly recover from surge, thus ensuring the safe operation of the centrifugal compressor 21.

[0145] In the anti-surge device of the centrifugal compressor system provided in this embodiment, the calculation module uses the first flow coefficient obtained by calculating based on the surge parameters of the centrifugal compressor as the current candidate coefficient. Under the current candidate coefficient, the module calculates the first time required for the inlet flow of the centrifugal compressor to change from the initial flow value to the lower limit of the flow. The processing module compares the first time with a predetermined second time to confirm whether the candidate coefficient meets the operating requirements. If the requirements are met, the current candidate coefficient is determined as the flow coefficient of the anti-surge valve. If the requirements are not met, the current candidate coefficient is adjusted until the requirements are met. This ensures the rationality of the determined anti-surge valve flow coefficient, thereby ensuring the anti-surge effect of the centrifugal compressor.

[0146] Example 3

[0147] Figure 9 This is a schematic diagram of the structure of the electronic device provided in Embodiment 3 of this application, as shown below. Figure 9 As shown, the electronic device includes:

[0148] The electronic device includes a processor 291 and a memory 292; it may also include a communication interface 293 and a bus 294. The processor 291, memory 292, and communication interface 293 can communicate with each other via the bus 294. The communication interface 293 can be used for information transmission. The processor 291 can invoke logical instructions stored in the memory 292 to execute the methods of the above embodiments.

[0149] Furthermore, the logic instructions in the aforementioned memory 292 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium.

[0150] The memory 292, as a computer-readable storage medium, can be used to store software programs and computer-executable programs, such as the program instructions / modules corresponding to the method in this embodiment. The processor 291 executes functional applications and data processing by running the software programs, instructions, and modules stored in the memory 292, thereby implementing the method in the above-described method embodiment.

[0151] The memory 292 may include a program storage area and a data storage area. The program storage area may store the operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal device. Furthermore, the memory 292 may include high-speed random access memory and may also include non-volatile memory.

[0152] This embodiment also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the methods described in any embodiment.

[0153] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0154] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for preventing surge in a centrifugal compressor system, characterized in that, The centrifugal compressor system includes a centrifugal compressor, process equipment, connecting pipelines, and an anti-surge valve. The flow coefficient of the anti-surge valve is obtained through an anti-surge method for the centrifugal compressor system, the method comprising: Based on the surge parameters of the centrifugal compressor, the first flow coefficient is calculated and used as the current candidate coefficient. Calculate the first time corresponding to the current candidate coefficient, where the first time is the time required for the inlet flow rate of the centrifugal compressor to change from the initial flow rate value to the lower flow rate limit value; wherein, the initial flow rate value is less than the lower flow rate limit value, and the lower flow rate limit value is greater than the surge flow rate corresponding to the centrifugal compressor; If the first time corresponding to the current candidate coefficient is not greater than the predetermined second time, then the current candidate coefficient is determined as the flow coefficient of the anti-surge valve; otherwise, the current candidate coefficient is adjusted, and the step of calculating the first time corresponding to the current candidate coefficient is executed again until the first time corresponding to the current candidate coefficient is not greater than the predetermined second time. Before adjusting the current candidate coefficients, the following steps are also included: Based on the blockage parameters of the centrifugal compressor, a second flow coefficient is calculated; and a first time corresponding to the second flow coefficient is calculated. The adjustment of the current candidate coefficients includes: If the first time corresponding to the second flow coefficient is not greater than the predetermined second time, then the current candidate coefficient is increased; wherein the adjusted candidate coefficient is less than the second flow coefficient.

2. The method according to claim 1, characterized in that, The calculation of the first time corresponding to the current candidate coefficient includes: Record the current time as the first time, and set the inlet flow rate of the centrifugal compressor at the current time as the initial flow rate value; For each second time point after the first time point, obtain the inlet flow rate of the centrifugal compressor at the second time point under the current candidate coefficient; If the inlet flow rate of the centrifugal compressor at the second moment reaches the lower flow rate limit, then the duration between the first moment and the current second moment is calculated as the first time corresponding to the current candidate coefficient.

3. The method according to claim 2, characterized in that, The step of obtaining the inlet flow rate of the centrifugal compressor at the second time point under the current candidate coefficient for each second time point after the first time point includes: For each second time after the first time, based on the flow rate, inlet pressure and system state parameters of each node of the centrifugal compressor system at the previous time, the system state parameters and the inlet pressure of each node at the current second time are obtained; Based on the inlet pressure of each node at the current second time point, the system state parameters, and the attribute parameters of each node, a functional relationship between the flow rate and the inlet / outlet pressure difference at each node is established; wherein, the nodes of the centrifugal compressor system include the components constituting the system path of the centrifugal compressor system, the components include the centrifugal compressor and the anti-surge valve, and the attribute parameters of the anti-surge valve are the current candidate coefficients; By using the simultaneous equations method, a nonlinear homogeneous system of equations is established based on the functional relationship corresponding to each node. Then, based on the nonlinear homogeneous system of equations, the inlet flow rate and pressure difference of each node at the second time moment are obtained by the Newton-Raphson iteration method. The inlet flow rate of the node includes the inlet flow rate of the centrifugal compressor.

4. The method according to claim 1, characterized in that, The method further includes: If the first time corresponding to the second flow coefficient is greater than the predetermined second time, then the second flow coefficient is determined as the flow coefficient of the anti-surge valve, and a second circuit is added; wherein, the flow coefficient of the quick-opening valve in the second circuit is greater than the first flow coefficient.

5. An anti-surge device for a centrifugal compressor system, characterized in that, The centrifugal compressor system includes a centrifugal compressor, process equipment, connecting pipelines, and an anti-surge valve. The flow coefficient of the anti-surge valve is obtained through an anti-surge device in the centrifugal compressor system, the device comprising: The calculation module is used to calculate the first flow coefficient based on the surge parameters of the centrifugal compressor, and use the first flow coefficient as the current candidate coefficient. The calculation module is also used to calculate the first time corresponding to the current candidate coefficient, where the first time is the time required for the inlet flow rate of the centrifugal compressor to change from the initial flow rate value to the lower flow rate limit value; wherein the initial flow rate value is less than the lower flow rate limit value, and the lower flow rate limit value is greater than the surge flow rate corresponding to the centrifugal compressor; The processing module is configured to determine the current candidate coefficient as the flow coefficient of the anti-surge valve if the first time corresponding to the current candidate coefficient is not greater than a predetermined second time; otherwise, adjust the current candidate coefficient and execute the step of calculating the first time corresponding to the current candidate coefficient again until the first time corresponding to the current candidate coefficient is not greater than the predetermined second time. The calculation module is further configured to calculate a second flow coefficient based on the blockage parameters of the centrifugal compressor before the processing module adjusts the current candidate coefficient; and to calculate a first time corresponding to the second flow coefficient. The processing module is specifically configured to increase the current candidate coefficient if the first time corresponding to the second flow coefficient is not greater than the predetermined second time; wherein the adjusted candidate coefficient is less than the second flow coefficient.

6. The apparatus according to claim 5, characterized in that, The computing module includes: A recording unit is used to record the current time as the first time and set the inlet flow rate of the centrifugal compressor at the current time as the initial flow rate value; A calculation unit is configured to obtain the inlet flow rate of the centrifugal compressor at the second time step for each second time step following the first time step; The calculation unit is further configured to calculate the duration between the first moment and the current second moment if the inlet flow rate of the centrifugal compressor at the second moment reaches the lower flow rate limit, and use this duration as the first time corresponding to the current candidate coefficient.

7. The apparatus according to claim 6, characterized in that, The calculation unit is specifically used to obtain the system state parameters and the inlet pressure of each node at the current second moment for each second moment after the first moment, based on the inlet flow rate, inlet pressure and system state parameters of each node of the centrifugal compressor system at the previous moment. The calculation unit is further configured to establish a functional relationship between the inlet flow rate and the inlet / outlet pressure difference at each node based on the inlet pressure of each node at the current second time point, the system state parameters, and the attribute parameters of each node; wherein, the nodes of the centrifugal compressor system include components constituting the system path of the centrifugal compressor system, the components include a centrifugal compressor and an anti-surge valve, and the attribute parameters of the anti-surge valve are the current candidate coefficients; The computing unit is further configured to establish a nonlinear homogeneous equation system based on the functional relationship corresponding to each node using the simultaneous equation method, and obtain the inlet flow rate and pressure difference of each node at the second time step using the Newton-Raphson iteration method based on the nonlinear homogeneous equation system; wherein, the inlet flow rate of the node includes the inlet flow rate of the centrifugal compressor.

8. The apparatus according to claim 5, characterized in that, The processing module is further configured to determine the second flow coefficient as the flow coefficient of the anti-surge valve and add a second circuit if the first time corresponding to the second flow coefficient is greater than the predetermined second time; wherein the flow coefficient of the quick-opening valve in the second circuit is greater than the first flow coefficient.

9. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1-4.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1-4.

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