Coupling Control Method of Anti-surge and Inlet Superheat for Centrifugal Steam Compressors

Abstract

The present invention discloses a coupled control method for anti-surge and inlet superheat of a centrifugal steam compressor, comprising a centrifugal steam compressor and a return line, wherein one end of the return line is connected to the inlet of the centrifugal steam compressor and the other end is connected to the outlet of the centrifugal steam compressor; a working coordinate system is established, a surge region is set in the working coordinate system, the inlet pressure, outlet pressure and inlet flow of the centrifugal steam compressor are monitored, the operating point of the centrifugal steam compressor is obtained in the working coordinate system, and it is determined whether the operating point of the centrifugal steam compressor enters the surge region; an inlet superheat target value is set, and the minimum valve position of the return valve that meets the superheat requirement is calculated based on the inlet superheat target value. The present invention can simultaneously solve the problems of compressor surge and inlet steam carryover through a single loop line and return valve, without the need for an electric heating device, thereby reducing equipment cost and operating energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal steam compressors, and in particular to a coupling control method for anti-surge and inlet superheat of a centrifugal steam compressor. Background Art

[0002] Centrifugal steam compressors are widely used for steam recovery and energy conservation in the chemical, power, food, and pharmaceutical industries. However, they face two main operational challenges: first, they have a surge boundary, making them prone to surge during operation. This can cause severe vibration and even damage to the equipment; second, when the inlet is saturated steam, it may contain liquid droplets. These droplets can enter the steam compressor and easily impact the impeller, potentially damaging it over time.

[0003] Currently, the surge problem of steam compressors is generally avoided by leading part of the steam at the outlet of the compressor back to the inlet of the compressor, thereby increasing the inlet flow rate.

[0004] As for the problem of liquid carryover in steam at the inlet, a steam-water separator is generally installed at the inlet to remove most of the liquid droplets that may be carried in the incoming flow. However, this method cannot completely avoid the problem of liquid carryover in the inlet. The steam at the inlet will still contain a small amount of liquid droplets, which will have a greater impact on the operation of the steam compressor. When the operating requirements are higher, an additional electric heating device will be added to the inlet of the steam compressor to increase the heat of the steam at the inlet through the electric heating device to further reduce or eliminate the droplets in the steam.

[0005] However, in traditional technology, the compressor surge problem needs to be solved by a steam return pipeline device, and the complete solution to the steam liquid problem at the inlet end needs to be solved by adding an electric heating device at the inlet end. Therefore, if you want to solve the above two problems at the same time, you need two completely different sets of devices to achieve it, which will result in the following shortcomings: 1. The addition of a steam return pipeline device and an electric heating device at the same time will lead to a significant increase in the overall equipment cost; and the two sets of devices need to be controlled independently, which increases the complexity of control; 2. The introduction and use of the electric heating device increases the energy consumption during equipment operation and increases the operating cost of the equipment.

[0006] Therefore, there is an urgent need to provide a centrifugal steam compressor control method that can simultaneously solve the steam compressor surge problem and the inlet steam liquid problem and can effectively reduce the operating cost. Summary of the Invention

[0007] The object of the present invention is to solve the deficiencies in the prior art and to provide a coupled control method for anti-surge and inlet superheat of a centrifugal steam compressor.

[0008] The object of the present invention is achieved through the following technical solution: a coupled control method for anti-surge and inlet superheat of a centrifugal steam compressor, comprising a centrifugal steam compressor and a return line, wherein one end of the return line is connected to the inlet end of the centrifugal steam compressor, and the other end of the return line is connected to the outlet end of the centrifugal steam compressor; a return valve is provided on the return line;

[0009] Establish a working coordinate system with the inlet flow rate as the horizontal coordinate and the pressure ratio as the vertical coordinate, set a surge region in the working coordinate system, monitor the inlet pressure, outlet pressure and inlet flow rate of the centrifugal steam compressor, and calculate the pressure ratio, obtain the current operating point of the centrifugal steam compressor in the working coordinate system, and judge whether the operating point of the centrifugal steam compressor enters the surge region; if the operating point enters the surge region, increase the opening of the return valve to make the operating point leave the surge region;

[0010] An inlet superheat target value is set, and a minimum valve position of the return valve that meets the superheat requirement is calculated based on the inlet superheat target value; when the centrifugal steam compressor is operating, the valve position of the return valve is always not lower than the minimum valve position.

[0011] Preferably, the inlet end of the centrifugal steam compressor is provided with a compressor inlet flow meter, a compressor inlet temperature monitoring instrument and a compressor inlet pressure monitoring instrument, and the outlet end of the centrifugal steam compressor is provided with a compressor outlet pressure monitoring instrument and a compressor outlet temperature monitoring instrument.

[0012] As a preferred method, the method for determining the lowest valve position is as follows:

[0013] S1: Determine the specific heat capacity at constant pressure Cp1 and latent heat of vaporization r1 of the saturated steam at the inlet of the centrifugal steam compressor; and determine the dryness q1 of the saturated steam at the inlet;

[0014] S2: Given the inlet superheat target value, the heating amount dH1 required to heat the inlet saturated steam to the target superheat state is calculated based on the inlet superheat target value; and the inlet steam flow m1, inlet steam temperature T1, outlet steam pressure P2, and outlet steam temperature T2 are detected;

[0015] S3: Calculate the steam flow rate m_rc that needs to flow back from the outlet to the inlet based on the steam flow rate m1 at the inlet, the steam temperature T1 at the inlet, the steam temperature T2 at the outlet, the heating capacity dH1, the latent heat of vaporization r1, and the specific constant pressure heat capacity Cp1;

[0016] S4: Given the reference opening lref of the reflux valve during regulation, the design inlet pressure P of the centrifugal steam compressor is 1d and design outlet pressure P 2dAs a benchmark, calculate the flow rate m_ref when the reflux valve opening is lref;

[0017] S5: Calculate the minimum valve position lmin of the reflux valve using the following formula:

[0018] ;

[0019] Among them, K is the adjustment coefficient and R is the adjustable ratio of the reflux valve.

[0020] Preferably, in step S5, the initial value of the adjustment coefficient K is 1.0, and the adjustment coefficient K is adjusted within the range of 0.9-1.2 according to actual operating conditions.

[0021] Preferably, a steam-water separator is provided at the inlet end of the centrifugal steam compressor, and the dryness q1 of the saturated steam at the inlet end is 0.99.

[0022] Preferably, in step S2, the calculation method of the heating amount dH1 is as follows:

[0023] ;

[0024] In step S3, the steam flow rate m_rc flowing back from the outlet to the inlet is calculated as follows:

[0025] .

[0026] Preferably, during operation, the centrifugal steam compressor monitors the steam flow m1 at the inlet, the steam pressure P1 at the inlet, the steam pressure P2 at the outlet, the steam temperature T1 at the inlet, and the steam temperature T2 at the outlet in real time, and calculates and updates the minimum valve position lmin of the reflux valve in real time in the control system.

[0027] Preferably, in step S1, the method for determining the specific constant-pressure heat capacity Cp1 and the latent heat of vaporization r1 of the saturated steam at the inlet of the centrifugal steam compressor is as follows:

[0028] The steam pressure at the inlet of the centrifugal steam compressor is detected, and the specific constant-pressure heat capacity Cp1 of the saturated steam at the pressure and the latent heat of vaporization r1 are obtained from the steam property database according to the steam pressure P1 at the inlet.

[0029] As a preferred method, when the actual steam pressure at the inlet of the centrifugal steam compressor is equal to the design inlet pressure P 1d When the deviation is less than the set range, use the design inlet pressure value P 1dThe specific constant-pressure heat capacity Cp1 and latent heat of vaporization r1 of saturated steam at this pressure are obtained through the steam physical property database, and the heating amount dH1 required to heat the saturated steam at the inlet to the target superheat is calculated. The calculated heating amount dH1 is used as a constant and used in the calculations of subsequent steps.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention calculates the pressure ratio and determines the operating point by establishing a working coordinate system and monitoring the inlet pressure, outlet pressure and inlet flow in real time, thereby accurately judging whether the centrifugal steam compressor has entered the surge region. Once the operating point enters the surge region, increasing the opening of the return valve can timely make the operating point leave the surge region, thereby effectively avoiding the occurrence of surge, protecting the compressor equipment from damage and extending the service life of the equipment. By setting an inlet superheat target value and calculating the minimum valve position of the return valve based on the target value, it is ensured that regardless of the operating condition of the compressor and whether there is a risk of entering the surge region, the opening of the return valve will not fall below the minimum valve position value. In this way, a certain amount of high-grade steam can always be kept flowing back from the outlet to the inlet, heating the lower-grade steam at the inlet, so that the inlet of the steam compressor maintains a certain superheat, which is beneficial to improving the efficiency and stability of the compressor and preventing problems such as steam carryover from damaging the compressor.

[0032] 2. This invention combines anti-surge control with inlet superheat control to achieve coupled control, simultaneously achieving both control objectives through regulating the opening of the return valve. This coupled control method comprehensively considers various factors during compressor operation, enabling the compressor to operate under more optimal conditions, improving the performance and reliability of the entire system, avoiding the potential loss of balance that can occur with separate control methods, and achieving refined control of centrifugal steam compressors.

[0033] 3. The present invention can solve the problems of compressor surge and steam liquid at the inlet end at the same time through a loop pipeline and a return valve. The two problems are solved by a set of devices, the control complexity is greatly reduced, and there is no need to introduce an electric heating device, which reduces equipment cost and operating energy consumption.

[0034] 4. In the present invention, determining the minimum valve position significantly impacts the operation of the entire steam compressor system. If the minimum valve position is set too high, excessive steam will flow back from the outlet to the inlet, resulting in unnecessary steam backflow and reduced compressor efficiency. Conversely, if the minimum valve position is set too low, the inlet steam will not be sufficiently superheated, failing to completely resolve the issue of steam carryover. In the present invention, the minimum valve position is accurately calculated based on the actual operating parameters of the steam compressor, effectively resolving the issue of steam carryover at the inlet while fully ensuring the efficiency of the steam compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of the present invention.

[0036] In the figure: 1. Inlet pipeline, 2. Centrifugal steam compressor, 3. Outlet pipeline, 4. Return pipeline, 4a. Return valve, 5. Compressor inlet flow meter, 6. Compressor inlet pressure monitoring instrument, 7. Compressor outlet pressure monitoring instrument, 8. Compressor outlet temperature monitoring instrument, 9. Compressor inlet temperature monitoring instrument. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention are within the scope of protection of the present invention.

[0038] It should be understood by those skilled in the art that, in the disclosure of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0039] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the elements may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0040] like Figure 1 As shown, the coupled control method for anti-surge and inlet superheat of a centrifugal steam compressor includes a centrifugal steam compressor 2 and a return line 4, one end of the return line 4 is connected to the inlet end of the centrifugal steam compressor 2, and the other end of the return line 4 is connected to the outlet end of the centrifugal steam compressor 2; a return valve 4a is provided on the return line 4.

[0041] A working coordinate system is established with the inlet flow rate as the horizontal coordinate and the pressure ratio as the vertical coordinate, a surge area is set in the working coordinate system, the inlet pressure, outlet pressure and inlet flow rate of the centrifugal steam compressor 2 are monitored, and the pressure ratio is calculated. The current operating point of the centrifugal steam compressor 2 is obtained in the working coordinate system, and it is determined whether the operating point of the centrifugal steam compressor 2 enters the surge area; if the operating point enters the surge area, the opening of the return valve 4a is increased to make the operating point leave the surge area; an inlet superheat target value is set, and the minimum valve position of the return valve 4a that meets the superheat requirement is calculated based on the inlet superheat target value; when the centrifugal steam compressor 2 is running, the valve position of the return valve 4a is always not lower than the minimum valve position.

[0042] The present invention sets a minimum valve position for return valve 4a within the surge control logic. Regardless of the compressor's operating conditions or the risk of entering the surge zone, the opening of return valve 4a will never fall below this minimum position. This ensures that a certain amount of high-quality steam from the steam compressor outlet is always flowing back to the compressor inlet. This high-quality steam at the outlet heats the lower-quality steam at the inlet, maintaining a certain degree of superheat at the compressor inlet. Setting this minimum valve position does not require changing the aforementioned surge control logic and does not affect the determination of the compressor's operating point.

[0043] The present invention calculates the pressure ratio and determines the operating point by establishing a working coordinate system and monitoring the inlet pressure, outlet pressure and inlet flow in real time, thereby accurately judging whether the centrifugal steam compressor 2 has entered the surge region. Once the operating point enters the surge region, the measure of increasing the opening of the return valve 4a can timely make the operating point leave the surge region, thereby effectively avoiding the occurrence of the surge phenomenon, protecting the compressor equipment from damage and extending the service life of the equipment. By setting the inlet superheat target value, the minimum valve position of the return valve 4a is calculated based on this, ensuring that no matter what the operating condition of the compressor is and whether there is a risk of entering the surge region, the opening of the return valve 4a will not be lower than the minimum valve position value. In this way, a certain amount of high-grade steam can always be kept flowing back from the outlet to the inlet, and the lower-grade steam at the inlet can be heated, so that the inlet of the steam compressor maintains a certain superheat, which is beneficial to improving the efficiency and stability of the compressor and preventing problems such as steam carrying liquid from damaging the compressor.

[0044] The present invention combines anti-surge control with inlet superheat control to achieve coupled control, simultaneously achieving both control objectives by adjusting the opening of return valve 4a. This coupled control method comprehensively considers various factors during compressor operation, enabling the compressor to operate under more optimal conditions, improving the performance and reliability of the entire system, avoiding the potential loss of balance that can occur with separate control methods, and achieving refined control of centrifugal steam compressor 2.

[0045] The present invention can solve the problems of compressor surge and steam liquid carrying at the inlet end simultaneously through a loop pipeline and a return valve 4a. Two problems are solved by a set of devices, the control complexity is greatly reduced, and there is no need to introduce an electric heating device, which reduces equipment cost and operating energy consumption.

[0046] The inlet end of the centrifugal steam compressor 2 is provided with an inlet pipeline 1, and the outlet end of the centrifugal steam compressor 2 is provided with an outlet pipeline 3. One end of the return pipeline 4 is connected to the inlet pipeline 1, and the other end of the return pipeline 4 is connected to the outlet pipeline 3. Steam is input into the centrifugal steam compressor 2 through the inlet pipeline 1, and the steam is pressurized by the centrifugal steam compressor 2 and discharged from the outlet pipeline 3.

[0047] The inlet end of the centrifugal steam compressor 2 is provided with a compressor inlet flow meter 5, a compressor inlet temperature monitoring instrument 9 and a compressor inlet pressure monitoring instrument 6, and the outlet end of the centrifugal steam compressor 2 is provided with a compressor outlet pressure monitoring instrument 7 and a compressor outlet temperature monitoring instrument 8.

[0048] The compressor inlet flowmeter 5 is used to detect the steam flow at the compressor inlet, the compressor inlet temperature monitoring instrument 9 is used to detect the steam temperature at the compressor inlet, and the compressor inlet pressure monitoring instrument 6 is used to detect the steam pressure at the compressor inlet. The compressor outlet pressure monitoring instrument 7 is used to detect the steam pressure at the compressor outlet, and the compressor outlet temperature monitoring instrument 8 is used to detect the steam temperature at the compressor outlet.

[0049] Among them, the method for determining the lowest valve position is as follows:

[0050] S1: Determine the specific heat capacity at constant pressure Cp1 and latent heat of vaporization r1 of the saturated steam at the inlet of the centrifugal steam compressor; and determine the dryness q1 of the saturated steam at the inlet;

[0051] To improve the dryness of the saturated steam at the inlet, a steam separator is installed at the inlet of the centrifugal steam compressor. The separator is installed in the inlet pipeline and removes most of the liquid water droplets from the saturated steam at the inlet. The separator removes most of the liquid droplets from the saturated steam at the inlet, effectively improving the dryness of the saturated steam. After the steam passes through the separator, the dryness of the saturated steam is significantly improved. In this embodiment, the dryness of the saturated steam at the inlet, q1, is determined to be a constant, with a value of 0.99.

[0052] S2: given inlet superheat target value , and calculate the heating amount dH1 required to heat the inlet end saturated steam to the target superheat state according to the inlet superheat target value; and detect the inlet end steam flow m1, inlet end steam temperature T1, outlet end steam pressure P2, outlet end steam temperature T2;

[0053] In this step, the calculation method of the heating amount dH1 is as follows:

[0054] .

[0055] S3: Calculate the steam flow rate m_rc that needs to flow back from the outlet to the inlet based on the steam flow rate m1 at the inlet, the steam temperature T1 at the inlet, the steam temperature T2 at the outlet, the heating capacity dH1, the latent heat of vaporization r1, and the specific constant pressure heat capacity Cp1;

[0056] In this step, the calculation method of the steam flow rate m_rc flowing back from the outlet to the inlet is as follows:

[0057] .

[0058] S4: Given the reference opening lref of the reflux valve during regulation, the design inlet pressure P of the centrifugal steam compressor is 1d and design outlet pressure P 2d As a reference, the flow rate m_ref of the reflux valve when the opening is lref is calculated; in the present invention, the reference opening lref is set at 5-15%.

[0059] The flow rate m_ref can be calculated according to the flow-opening curve or the corresponding relationship of the reflux valve. When calculating, the flow rate under given conditions can be calculated based on the corresponding data provided by the valve manufacturer, including the rated flow coefficient kv, the relationship between the valve core stroke and the kv change, etc. For example, the valve nominal diameter is 100mm, the equal percentage characteristic, the rated kv is 160, and the compressor design outlet pressure P 2d is 0.7MPa, the temperature before the valve is 260℃, and the design inlet pressure P 1d is 0.35MPa, valve pressure drop (P 2d -P 1d ) is 0.35MPa. If lref is 10%, the valve manufacturer can calculate the flow rate at 10% opening according to the above conditions, that is, m_ref is 0.3t / h.

[0060] Parameter P 1d , P 2d , lref, m_ref, and R are all used as constants in subsequent calculations of the control system.

[0061] S5: Calculate the minimum valve position lmin of the reflux valve using the following formula:

[0062] .

[0063] Wherein, K is the adjustment coefficient, and R is the adjustable ratio of the reflux valve. In the present invention, the initial value of the adjustment coefficient K is 1.0, and the adjustment coefficient K is adjusted within the range of 0.9-1.2 according to the actual operating conditions.

[0064] In the present invention, determining the minimum valve position has a significant impact on the operation of the entire steam compressor system. If the minimum valve position is set too high, excessive steam will flow back from the outlet to the inlet, resulting in unnecessary steam backflow, which will reduce the operating efficiency of the steam compressor. Conversely, if the minimum valve position is set too low, the steam at the inlet will not have sufficient superheat, and the problem of steam carryover at the inlet cannot be completely solved. In the present invention, the minimum valve position is accurately calculated based on the actual operating parameters of the steam compressor, which can not only solve the problem of steam carryover at the inlet, but also fully ensure the operating efficiency of the steam compressor.

[0065] During operation, a centrifugal steam compressor monitors the inlet steam flow rate m1, inlet steam pressure P1, outlet steam pressure P2, inlet steam temperature T1, and outlet steam temperature T2 in real time. The control system also calculates and updates the minimum valve position (lmin) of the return valve in real time. Compressor operating conditions can change due to factors such as production demand. Real-time updates of the minimum valve position (lmin) allow the control system to adapt promptly to these changes. Regardless of fluctuations in flow, pressure, temperature, and other parameters, the real-time calculation and update of the minimum valve position (lmin) ensures that the entire equipment maintains proper operating conditions and ensures stable compressor operation.

[0066] In step S1, the method for determining the specific constant-pressure heat capacity Cp1 and the latent heat of vaporization r1 of the saturated steam at the inlet of the centrifugal steam compressor is as follows:

[0067] The steam pressure at the inlet of the centrifugal steam compressor is detected, and the specific constant-pressure heat capacity Cp1 of the saturated steam at the pressure and the latent heat of vaporization r1 are obtained from the steam property database in the control system according to the steam pressure P1 at the inlet.

[0068] Furthermore, when the actual steam pressure at the inlet of the centrifugal steam compressor is equal to the design inlet pressure P 1d When the deviation is less than the set range, use the design inlet pressure value P 1d The specific heat capacity at constant pressure (Cp1) and latent heat of vaporization (r1) of saturated steam at that pressure are then retrieved from the steam properties database. The heat required to heat the saturated steam at the inlet to the target superheat (dH1) is then calculated. This heat is used as a constant for subsequent calculations. In this process, the steam flow rate (m_rc) returning from the outlet to the inlet is calculated using only the monitored data (m1, T1, and T2). This formula then calculates the minimum valve position (lmin).

[0069] After the above simplification, when the actual steam pressure at the inlet of the centrifugal steam compressor is equal to the design inlet pressure P 1d When the deviation is less than the set range, there is no need to check the steam physical property database through the P1 monitoring value before performing subsequent calculations. After the heating value dH1 is determined as a constant, the calculation of subsequent results can be greatly facilitated. When performing real-time update calculations, the amount of calculation is greatly reduced, which facilitates real-time update of the minimum valve position value.

[0070] In the present invention, the actual steam pressure at the inlet of the centrifugal steam compressor is equal to the designed inlet pressure P 1d When the deviation is less than 8%, it can be calculated according to the simplified method above.

[0071] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A coupled control method for anti-surge and inlet superheat of a centrifugal steam compressor, characterized in that: The invention comprises a centrifugal steam compressor and a return line, wherein one end of the return line is connected to the inlet end of the centrifugal steam compressor, and the other end of the return line is connected to the outlet end of the centrifugal steam compressor; a return valve is provided on the return line; Establish a working coordinate system with the inlet flow rate as the horizontal coordinate and the pressure ratio as the vertical coordinate, set a surge region in the working coordinate system, monitor the inlet pressure, outlet pressure and inlet flow rate of the centrifugal steam compressor, and calculate the pressure ratio, obtain the current operating point of the centrifugal steam compressor in the working coordinate system, and determine whether the operating point of the centrifugal steam compressor enters the surge region; If the operating point enters the surge area, increase the opening of the return valve to make the operating point leave the surge area; A target inlet superheat value is set, and the minimum valve position of the return valve that meets the superheat requirement is calculated based on the target inlet superheat value; when the centrifugal steam compressor is running, the valve position of the return valve is always not lower than the minimum valve position; The method for determining the lowest valve position is as follows: S1: Determine the specific heat capacity at constant pressure Cp1 and latent heat of vaporization r1 of the saturated steam at the inlet of the centrifugal steam compressor; and determine the dryness q1 of the saturated steam at the inlet; S2: given inlet superheat target value , and calculate the heating amount dH1 required to heat the inlet saturated steam to the target superheat state based on the inlet superheat target value; and detect the inlet steam flow m1, inlet steam temperature T1, outlet steam pressure P2, and outlet steam temperature T2; the calculation method of the heating amount dH1 is as follows: ； S3: Calculate the steam flow rate m_rc required to flow back from the outlet to the inlet based on the steam flow rate m1 at the inlet, the steam temperature T1 at the inlet, the steam temperature T2 at the outlet, the heating capacity dH1, the latent heat of vaporization r1, and the specific constant-pressure heat capacity Cp1. The calculation method for the steam flow rate m_rc required to flow back from the outlet to the inlet is as follows: ； S4: Given the reference opening lref of the reflux valve during regulation, the design inlet pressure P of the centrifugal steam compressor is 1d and design outlet pressure P 2d As a benchmark, calculate the flow rate m_ref when the reflux valve opening is lref; S5: Calculate the minimum valve position lmin of the reflux valve using the following formula: ； Among them, K is the adjustment coefficient, R is the adjustable ratio of the reflux valve; During the operation of the centrifugal steam compressor, the steam flow m1 at the inlet, the steam pressure P1 at the inlet, the steam pressure P2 at the outlet, the steam temperature T1 at the inlet, and the steam temperature T2 at the outlet are monitored in real time, and the minimum valve position lmin of the reflux valve is calculated and updated in real time in the control system.

2. The method for coupling control of anti-surge and inlet superheat of a centrifugal steam compressor according to claim 1, characterized in that: The inlet end of the centrifugal steam compressor is provided with a compressor inlet flow meter, a compressor inlet temperature monitoring instrument and a compressor inlet pressure monitoring instrument, and the outlet end of the centrifugal steam compressor is provided with a compressor outlet pressure monitoring instrument and a compressor outlet temperature monitoring instrument.

3. The method for coupled control of anti-surge and inlet superheat of a centrifugal steam compressor according to claim 1, characterized in that: In step S5, the initial value of the adjustment coefficient K is 1.0, and the adjustment coefficient K is adjusted within the range of 0.9-1.2 according to actual operating conditions.

4. The method for coupled control of anti-surge and inlet superheat of a centrifugal steam compressor according to claim 1, characterized in that: A steam-water separator is provided at the inlet of the centrifugal steam compressor, and the dryness q1 of the saturated steam at the inlet is 0.

99.

5. The method for coupled control of anti-surge and inlet superheat of a centrifugal steam compressor according to claim 1, characterized in that: In step S1, the method for determining the specific constant-pressure heat capacity Cp1 and the latent heat of vaporization r1 of the saturated steam at the inlet of the centrifugal steam compressor is as follows: The steam pressure at the inlet of the centrifugal steam compressor is detected, and the specific constant-pressure heat capacity Cp1 of the saturated steam at the pressure and the latent heat of vaporization r1 are obtained from the steam property database according to the steam pressure P1 at the inlet.

6. The method for coupled control of anti-surge and inlet superheat of a centrifugal steam compressor according to claim 1, characterized in that: When the actual steam pressure at the inlet of the centrifugal steam compressor is equal to the design inlet pressure P 1d When the deviation is less than the set range, use the design inlet pressure value P 1d The specific constant-pressure heat capacity Cp1 and latent heat of vaporization r1 of saturated steam at this pressure are obtained through the steam physical property database, and the heating amount dH1 required to heat the saturated steam at the inlet to the target superheat is calculated. The calculated heating amount dH1 is used as a constant and used in the calculations of subsequent steps.

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