Precision Early Warning System and Method for Centrifugal Compressor Based on Function Fitting Curve

Abstract

The present application discloses a precise warning system and method for a centrifugal compressor based on a function fitting curve. Through the intake temperature, inlet differential pressure, exhaust temperature, real-time exhaust pressure and environmental data of the centrifugal compressor, according to the detection data of the intake temperature and differential pressure and the exhaust temperature and exhaust pressure, the real-time operating inlet volume flow rate of the centrifugal compressor is calculated. The pressure value corrected by the environmental condition parameters in combination with the exhaust pressure value detected by the exhaust pressure sensor is used as the operating point and fitted in the pressure-flow operating coordinate diagram. The pressure-flow operating coordinate diagram is fitted and combined by a linear function and a quadratic function and used as the coordinate diagram of the operating point. The minimum pressure protection value of the centrifugal compressor is fitted as a constant function diagram, so as to calculate and protect the operating point of the centrifugal compressor to always operate in the safe area through their respective function values, ensuring the safe operation of the whole machine. The present invention solves the problem of inaccurate warning protection of the existing centrifugal compressor.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal compressors, and particularly to a precise early warning system and method for a centrifugal compressor based on a function fitting curve. Background Art

[0002] Centrifugal compressors are widely used, and the operating conditions are complex, and they need to be suitable for the operating conditions of various industries. The price of centrifugal compressors is slightly higher than that of other general machinery, and more early warning and protection are required during use. The existing centrifugal compressors are not particularly precise in controlling surge and pre-surge. In many cases, the centrifugal compressor has already operated in the pre-surge area but there is no corresponding prompt or early warning function, while sometimes the prompt has already started before reaching the relevant area. Such situations cause a great degree of misjudgment to users, thus bringing unnecessary losses to users. Summary of the Invention

[0003] In order to overcome the defects of the prior art, a precise early warning system and method for a centrifugal compressor based on a function fitting curve are provided to solve the problem of inaccurate early warning and protection of existing centrifugal compressors.

[0004] To achieve the above object, a precise early warning method for a centrifugal compressor based on a function fitting curve is provided, including the following steps:

[0005] Obtain the theoretical power of the centrifugal compressor and collect the real-time power of the centrifugal compressor to calculate and obtain a power correction coefficient;

[0006] Calculate and obtain a corrected power based on the power correction coefficient and the real-time power;

[0007] Collect the differential pressure and intake temperature at the intake port of the centrifugal compressor, the real-time exhaust pressure at the outlet port of the centrifugal compressor, the ambient temperature, the atmospheric humidity, and the atmospheric pressure;

[0008] Calculate and obtain the air density through the ideal gas state equation based on the ambient temperature, the atmospheric humidity, and the atmospheric pressure;

[0009] Correct the real-time exhaust pressure based on the relationship between the atmospheric pressure and the air density to obtain a corrected exhaust pressure;

[0010] Calculate the real-time volume flow rate at the intake port of the centrifugal compressor through the Bernoulli equation based on the corrected power and the corrected exhaust pressure;

[0011] Construct a pressure-flow operation coordinate diagram of the centrifugal compressor;

[0012] Fitting a pressure-flow curve in the pressure-flow operation coordinate diagram based on a plurality of real-time volume flows and corrected exhaust pressures within the operating range from the highest pressure to the lowest pressure of the centrifugal compressor;

[0013] Based on the real-time exhaust pressure at different high rotational speeds of the centrifugal compressor and the volume flow rate at the air outlet, fitting a surge shutdown line and a surge warning line in the pressure-flow operation coordinate diagram;

[0014] The pressure-flow curve, the surge warning line, and the lowest pressure protection line of the centrifugal compressor enclose a safety region;

[0015] Fitting the real-time exhaust pressure and the real-time volume flow rate in the pressure-flow operation coordinate diagram to form an operating point;

[0016] Monitoring whether the operating point is within the safety region, and when the operating point exceeds the safety region, generating a corresponding alarm signal based on the relative position of the operating point with respect to the safety region.

[0017] Further, when the operating point enters the area between the surge shutdown line and the surge warning line, generating a surge warning alarm signal.

[0018] Further, when the operating point enters the side of the surge shutdown line that is far from the surge warning line, generating a surge shutdown alarm signal.

[0019] Further, when the real-time exhaust pressure and the real-time volume flow rate of the operating point are respectively greater than the exhaust pressure and the volume flow rate of the rated operating point of the centrifugal compressor, generating an overpressure warning alarm signal.

[0020] Further, when the real-time exhaust pressure of the operating point is greater than the exhaust pressure of the rated operating point and the real-time volume flow rate of the operating point is less than the volume flow rate of the rated operating point, generating an over-flow warning alarm signal.

[0021] Further, when the real-time exhaust pressure of the operating point is lower than the lowest pressure line of the centrifugal compressor, generating a low-pressure warning or shutdown alarm signal.

[0022] The present invention provides a precise warning system for a centrifugal compressor based on a function-fitted curve, including:

[0023] A temperature detection module for detecting the intake temperature of the air inlet of the centrifugal compressor;

[0024] A differential pressure detection module for detecting the differential pressure at the air inlet;

[0025] A pressure detection module, configured to detect the real-time exhaust pressure at the air outlet of the centrifugal compressor;

[0026] An environment monitoring module, configured to detect the ambient temperature, atmospheric humidity, and atmospheric pressure of the working environment of the centrifugal compressor;

[0027] A power detection module, configured to detect the real-time power of the centrifugal compressor;

[0028] A processor, signal-connected to the temperature detection module, the pressure difference detection module, the pressure detection module, the environment monitoring module, and the power detection module;

[0029] A memory, connected to the processor, and the memory stores a computer program executable by the processor. The computer program is executed by the processor to cause the processor to execute a precise warning method for the centrifugal compressor based on a function fitting curve.

[0030] The beneficial effect of the present invention is that the precise warning system for the centrifugal compressor based on the function fitting curve of the present invention monitors the running / stopping state and fault diagnosis of the centrifugal compressor through the operation of the processor. The temperature sensor detects the intake temperature of the centrifugal compressor, the pressure difference sensor detects the inlet pressure difference at the air inlet of the centrifugal compressor, the temperature sensor detects the exhaust temperature of the centrifugal compressor, and the pressure sensor detects the real-time exhaust pressure of the centrifugal compressor. When the centrifugal compressor is running, the processor calculates the real-time running inlet volume flow rate of the centrifugal compressor according to the detection data of the intake temperature sensor, the pressure difference sensor, the exhaust temperature sensor, and the exhaust pressure sensor, and combines the pressure value after correction of the exhaust pressure value detected by the exhaust pressure sensor by the environmental condition parameters as the operating point to be fitted in the pressure-flow operating coordinate diagram. The pressure-flow operating coordinate diagram is fitted and combined by a linear function and a quadratic function as the coordinate diagram of the operating point. The lowest pressure protection value of the centrifugal compressor is fitted as a constant function diagram, so as to calculate and protect the operating point of the centrifugal compressor to always operate in the safe area through their respective function values, and to give a precise warning to ensure the safe operation of the centrifugal compressor. Description of the Drawings

[0031] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objects, and advantages of the present application will become more obvious:

[0032] Figure 1 It is the pressure-flow operating coordinate diagram of the embodiment of the present invention.

[0033] Figure 2 It is the structural schematic diagram of the precise warning system for the centrifugal compressor based on the function fitting curve of the embodiment of the present invention. Detailed Embodiments

[0034] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. Additionally, it should be noted that for the convenience of description, only the parts related to the invention are shown in the drawings.

[0035] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0036] Referring Figure 1 and Figure 2 as shown, the present invention provides a precise early warning method for a centrifugal compressor based on a function fitting curve, including the following steps:

[0037] S1. Obtain the theoretical power of the centrifugal compressor and collect the real-time power of the centrifugal compressor to calculate and obtain a power correction coefficient.

[0038] S2. Calculate and obtain a corrected power based on the power correction coefficient and the real-time power.

[0039] S3. Collect the pressure difference and intake temperature at the intake port of the centrifugal compressor, the real-time exhaust pressure at the outlet of the centrifugal compressor, the ambient temperature, the atmospheric humidity, and the atmospheric pressure.

[0040] S4. Calculate and obtain the air density based on the ambient temperature, the atmospheric humidity, and the atmospheric pressure through the ideal gas state equation.

[0041] S5. Correct the real-time exhaust pressure based on the relationship between the atmospheric pressure and the air density to obtain a corrected exhaust pressure.

[0042] S6. Calculate the real-time volume flow rate at the intake port of the centrifugal compressor through the Bernoulli equation based on the corrected power and the corrected exhaust pressure.

[0043] S7. Construct a pressure-flow operation coordinate diagram of the centrifugal compressor.

[0044] S8. Fit a pressure and flow curve C in the pressure-flow operation coordinate diagram based on multiple real-time volume flow rates and corrected exhaust pressures within the operating range from the highest pressure to the lowest pressure of the centrifugal compressor.

[0045] S9. Fit a surge shutdown line B and a surge early warning line A in the pressure-flow operation coordinate diagram based on the real-time exhaust pressure and the volume flow rate at the outlet of the centrifugal compressor at different high speeds.

[0046] S10. A safety region is enclosed by the pressure and flow curve, the surge early warning line, and the lowest pressure protection line of the centrifugal compressor.

[0047] S11. Fit the real-time exhaust pressure and real-time volume flow rate in a pressure-flow operating coordinate diagram to form an operating point.

[0048] S12. Monitor whether the operating point m is in the safe area, and when the operating point exceeds the safe area, generate a corresponding alarm signal based on the relative position of the operating point with respect to the safe area.

[0049] When the operating point is within the safe area, no alarm signal is generated.

[0050] When the operating point enters the area between the surge shutdown line and the surge warning line, generate a surge warning alarm signal.

[0051] When the operating point enters the side of the surge shutdown line far from the surge warning line, generate a surge shutdown alarm signal.

[0052] When the real-time exhaust pressure and real-time volume flow rate of the operating point are respectively greater than the exhaust pressure and volume flow rate of the rated operating point of the centrifugal compressor, generate an overpressure warning alarm signal.

[0053] When the real-time exhaust pressure of the operating point is greater than the exhaust pressure of the rated operating point N and the real-time volume flow rate of the operating point is less than the volume flow rate of the rated operating point, generate an over-flow warning alarm signal.

[0054] When the real-time exhaust pressure of the operating point is lower than the minimum pressure line of the centrifugal compressor, generate a low-pressure warning or shutdown alarm signal.

[0055] The present invention provides a precise warning system for a centrifugal compressor based on a function-fitting curve, including: a temperature detection module 1, a differential pressure detection module 2, a pressure detection module 3, an environmental monitoring module 4, a processor 5, and a memory 6.

[0056] The temperature detection module 1 is used to detect the intake temperature of the intake port of the centrifugal compressor. In this embodiment, the temperature detection module is a temperature sensor.

[0057] The differential pressure detection module 2 is used to detect the differential pressure at the intake port. In this embodiment, the differential pressure detection module is a differential pressure sensor.

[0058] The pressure detection module 3 is used to detect the real-time exhaust pressure at the outlet of the centrifugal compressor. In this embodiment, the pressure detection module is a pressure sensor.

[0059] The environmental monitoring module 4 is used to detect the environmental temperature, atmospheric humidity, and atmospheric pressure of the working environment of the centrifugal compressor. In this embodiment, the environmental monitoring module is an environmental detection triad meter (temperature-humidity-atmospheric pressure gauge).

[0060] The power detection module is used to detect the real-time power of the centrifugal compressor. In this embodiment, the power detection module is a power recorder.

[0061] The processor 5 is signal-connected to a temperature detection module, a differential pressure detection module, a pressure detection module, an environmental monitoring module, and a power detection module.

[0062] The memory 6 is connected to the processor. The memory stores a computer program executable by the processor, and the computer program is executed by the processor to cause the processor to execute an accurate early warning method for a centrifugal compressor based on a function fitting curve.

[0063] In this embodiment, the processor may be a central processing unit, a network processor, a hardware chip, or any combination thereof. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof.

[0064] As a non-transitory computer-readable storage medium, the memory can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as program instructions / modules corresponding to the accurate early warning method for a centrifugal compressor based on a function fitting curve in the embodiments of the present application. By running the non-transitory software programs, instructions, and modules stored in the memory, the processor can implement the accurate early warning method for a centrifugal compressor based on a function fitting curve in any one of the following method embodiments.

[0065] The memory may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as read-only memory, flash memory, a hard disk, or a solid-state drive; the memory may further include a combination of the above types of memory.

[0066] The present invention also provides a computer-readable storage medium storing computer instructions for causing the processor 5 to implement an accurate early warning method for a centrifugal compressor based on a function fitting curve when executed.

[0067] It can be understood from the above that the accurate early warning method for a centrifugal compressor based on a function fitting curve provided by the embodiments of the present application can be implemented by various types of electronic devices with processing capabilities, such as being executed by the processor of an electronic device or being executed by other devices with computing and processing capabilities. Other devices with computing and processing capabilities may be intelligent terminals or servers communicatively connected to the electronic device, etc.

[0068] The precise warning system of the centrifugal compressor based on the function fitting curve of the present invention monitors the running / stopping state and fault diagnosis of the centrifugal compressor through the operation of the processor. The temperature sensor detects the intake temperature of the centrifugal compressor, the differential pressure sensor detects the inlet differential pressure at the inlet of the centrifugal compressor, the temperature sensor detects the exhaust temperature of the centrifugal compressor, and the pressure sensor detects the real-time exhaust pressure of the centrifugal compressor. When the centrifugal compressor is running, the processor calculates the real-time running inlet volume flow rate of the centrifugal compressor according to the detection data of the intake temperature sensor, differential pressure sensor, exhaust temperature sensor and exhaust pressure sensor, and combines the pressure value corrected by the environmental condition parameters detected by the exhaust pressure sensor as the operating point and fits it in the pressure-flow operating coordinate diagram. The pressure-flow operating coordinate diagram is fitted and combined by a linear function and a quadratic function, and is used as the coordinate diagram of the operating point. The lowest pressure protection value of the centrifugal compressor is fitted as a constant function diagram, so as to calculate and protect the operating point of the centrifugal compressor to always operate in the safe area through their respective function values, ensuring the safe operation of the whole machine.

[0069] The precise warning method of the centrifugal compressor based on the function fitting curve of the present invention will be described in detail with reference to the accompanying drawings and the following embodiments.

[0070] The precise warning method of the centrifugal compressor based on the function fitting curve of the present invention is realized through the following steps:

[0071] a. The processor obtains the theoretical power data of the centrifugal compressor at 100% - 80% of each rotational speed collected and the real-time power data at the corresponding rotational speed collected by the power recorder, records the respective data and fits them into a linear function, calculates the ratio of the slopes of the two linear functions, and sets it as the correction coefficient of the real-time power and inputs it into the processor.

[0072] b. The environmental triple meter detects the temperature data, atmospheric pressure data and humidity data of the current environment, obtains the corresponding real-time pressure value, and inputs the temperature data, atmospheric pressure data and humidity data into the processor.

[0073] c. Calculate the real-time inlet volume flow rate value of the centrifugal compressor by using the corrected real-time power value and the real-time exhaust pressure value. A total of 12 points of DP1 - DP12 are measured (DP1 - DP12 are 12 points measured at the corresponding flow rate values when the centrifugal compressor evenly divides the pressure within the operating range from the highest pressure to the lowest pressure, and the data is recorded), calculate the actual values of the 12 points, simulate the 12 points into a pressure and flow curve C and make appropriate corrections, and finally generate a quadratic function of the pressure and flow curve C and write it into the processor.

[0074] Specifically, the actually measured environmental temperature, atmospheric humidity, and atmospheric pressure values are used to calculate the air density under the current environment according to the ideal gas state equation. The volume flow rate at the inlet is calculated through the Bernoulli equation, and then the exhaust pressure is calculated and corrected based on the relationship between the atmospheric pressure and air density at the altitude, so as to obtain the real-time volume flow rate value at the inlet and the exhaust pressure under the current operating environment in the theoretical performance data of the centrifugal compressor (20°C, RH65%, 101.325 KPa).

[0075] Specifically, the calculation and correction of the exhaust pressure based on the relationship between the atmospheric pressure and air density at the altitude are carried out through the following formula:

[0076] ρ2 = ρ1(1 - H / 44300) 5.256 ,

[0077] where ρ1 is the density based on 20°C, RH65%, 101.325 KPa, ρ2 is the density calculated based on the data measured by the three-in-one meter, and H is the altitude, that is, the converted value of the atmospheric pressure in the three-in-one meter. The formula is as follows: P = P0×(1 - L×H / T) (g×M / R×L) ,

[0078] P: Atmospheric pressure value at altitude;

[0079] P0: Standard atmospheric pressure 101.325 KPa;

[0080] L: Temperature gradient of temperature varying with altitude, usually 10 -3 K / m; H: Altitude;

[0081] T: Temperature at altitude, expressed in Kelvin temperature;

[0082] g: Acceleration due to gravity, constant;

[0083] M: Average molecular weight of air, constant.

[0084] R: Gas constant, constant d. The real-time exhaust pressure value and the real-time inlet volume flow rate value are fitted into the real-time coordinate point m(x, y) in the operation diagram.

[0085] e. Rated operating point N(X, Y) of the centrifugal compressor.

[0086] The rated operating point of the centrifugal compressor is the designed operating point of the centrifugal compressor.

[0087] f. The real-time coordinate points in step d are the real-time operating points of the centrifugal compressor. The following protections are carried out based on the real-time operating points to ensure that the real-time operating points are always within the normal operating range. When they exceed the operating range, surge warnings, surge shutdowns, overpressure shutdowns, over-flow shutdowns, low-pressure shutdowns, etc. will be carried out. The specific methods are as follows:

[0088] Based on the theoretical surge warning data of the centrifugal compressor, calculate the real-time surge warning data. Similarly, correct the surge warning data and fit it into a real-time surge warning linear function: y1 = m1x1 + b1. x1 and y1 are the coordinates of any point on the linear function, where m1 and b1 are constant coefficients.

[0089] Specifically, the theoretical surge warning data of the centrifugal compressor is based on 20°C, RH65%, 101.325 KPa, and the real-time surge warning data is calculated based on the environmental parameters measured by the three-in-one.

[0090] Correcting the surge warning data is to slightly adjust the real-time surge data to make the resulting linear function a smooth and continuous straight line to obtain A.

[0091] Similarly, the real-time surge shutdown linear function: y2 = m2x2 + b2. x2 and y2 are the coordinates of any point on the linear function, where m2 and b2 are constant coefficients. The real-time surge shutdown linear function is obtained by offsetting the corrected pre-surge data to get B.

[0092] Judgment method: For the operating point m(x, y), y = y1 = y2, and then calculate the value of x1. Similarly, calculate the value of x2.

[0093] When x2 < x < x3 (at this time, the value of x3 comes from y = y3, calculated from the calculated value), it is the normal operating range;

[0094] When x2 < x < x1, send a surge warning alarm signal;

[0095] When x < x2, send a surge shutdown alarm signal;

[0096] Similarly, the real-time performance curve quadratic function: The rated operating point N(X, Y) of the centrifugal compressor is located on this quadratic function. a, b, and c are constant coefficients. x3 and y3 are the real-time operating coordinates.

[0097] Judgment method: For the operating point m(x, y), y = y3, and then calculate the value of x3. At this time, x3 = x.

[0098] When x > X and y > Y, send an overpressure warning alarm signal;

[0099] When x > X and y < Y, an over - traffic warning alarm signal is issued;

[0100] Similarly, the real - time pressure constant function: y4 = y (this value is set as a parameter in the processor, and the function graph is not shown in the figure). y is the real - time pressure value, which is detected and collected by the processor.

[0101] Judgment method: operating point m(x, y)

[0102] When y < y4, a low - pressure warning or shutdown alarm signal is issued.

[0103] The above description is only the preferred embodiment of the present application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by the specific combination of the above - mentioned technical features, but also covers other technical solutions formed by any combination of the above - mentioned technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above - mentioned features with the (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A centrifugal compressor accurate early warning method based on function fitting curve, characterized in that: The following steps are involved: Acquiring the theoretical power of the centrifugal compressor and collecting the real-time power of the centrifugal compressor to calculate the power correction coefficient; Based on the power correction coefficient and the real-time power, a corrected power is calculated; Collecting the pressure difference and intake temperature of the air inlet of the centrifugal compressor, the real-time exhaust pressure, ambient temperature, atmospheric humidity and atmospheric pressure of the air outlet of the centrifugal compressor; Based on the ambient temperature, the atmospheric humidity and the atmospheric pressure, the air density is calculated by using an ideal gas state equation; Based on the relationship between the atmospheric pressure and the air density, correcting the real-time exhaust pressure to obtain a corrected exhaust pressure; Calculating a real-time volume flow rate of an air inlet of the centrifugal compressor by using a Bernoulli equation based on the corrected power and the corrected exhaust pressure; Constructing a pressure-flow operation coordinate diagram of the centrifugal compressor; Fitting a pressure-flow curve in the pressure-flow operation coordinate diagram based on a plurality of real-time volume flow rates and corrected exhaust pressures within the highest pressure to lowest pressure operation range of the centrifugal compressor; Based on the real-time exhaust pressure of the centrifugal compressor at different high speeds and the volume flow rate of the air outlet, a surge shutdown line and a surge warning line are formed by fitting in the pressure-flow operation coordinate diagram; The pressure and flow curve, the surge warning line and the minimum pressure protection line of the centrifugal compressor form a safety area; Fitting the real-time exhaust pressure and the real-time volume flow rate in the pressure-flow rate operation coordinate diagram to form an operation point; Monitor whether the operating point is in the safety area, and when the operating point exceeds the safety area, generate a corresponding alarm signal based on the relative position of the operating point with respect to the safety area.

2. The centrifugal compressor precise early warning method based on function fitting curve according to claim 1 is characterized in that: When the operating point enters between the surge shutdown line and the surge warning line, a surge warning alarm signal is generated.

3. The centrifugal compressor precise early warning method based on function fitting curve according to claim 1 is characterized in that: When the operating point enters a side of the surge shutdown line away from the surge warning line, a surge shutdown alarm signal is generated.

4. The centrifugal compressor precise early warning method based on function fitting curve according to claim 1 is characterized in that: When the real-time exhaust pressure and the real-time volume flow rate at the operating point are respectively greater than the exhaust pressure and the volume flow rate at the rated operating point of the centrifugal compressor, an overpressure early warning alarm signal is generated.

5. The centrifugal compressor precise early warning method based on function fitting curve according to claim 4 is characterized in that: When the real-time exhaust pressure at the operating point is greater than the exhaust pressure at the rated operating point and the real-time volume flow at the operating point is less than the volume flow at the rated operating point, an overflow early warning alarm signal is generated.

6. The centrifugal compressor precise early warning method based on function fitting curve according to claim 1 is characterized in that: When the real-time exhaust pressure at the operating point is lower than the lowest pressure line of the centrifugal compressor, a low pressure early warning or shutdown alarm signal is generated.

7. A centrifugal compressor precision early warning system based on function fitting curve, characterized in that: include: A temperature detection module, used to detect the intake air temperature of the air inlet of the centrifugal compressor; A pressure difference detection module, used for detecting the pressure difference of the air inlet; A pressure detection module, used to detect the real-time exhaust pressure of the air outlet of the centrifugal compressor; An environmental monitoring module, used to detect the ambient temperature, atmospheric humidity and atmospheric pressure of the working environment of the centrifugal compressor; A power detection module, used to detect the real-time power of the centrifugal compressor; A processor, signal-connected to the temperature detection module, the pressure difference detection module, the pressure detection module, the environment monitoring module and the power detection module; A memory connected to the processor, wherein the memory stores a computer program executable by the processor, wherein the computer program is executed by the processor to enable the processor to execute the centrifugal compressor precise early warning method based on the function fitting curve as described in any one of claims 1 to 6.

Images