CN112629602B - Condenser and vacuum system air leakage flow measurement method - Google Patents
Condenser and vacuum system air leakage flow measurement method Download PDFInfo
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- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
- G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
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Abstract
The invention relates to a condenser and a method for measuring air leakage flow of a vacuum system, comprising the following steps that S1, when vacuum pumping equipment corresponding to the condenser is in a shutdown state and the running state of the condenser is unchanged, air leaks into the condenser through a plurality of groups of pore plates with different apertures; s2, acquiring a plurality of groups of condenser vacuum pressure drop rate data in the condenser, wherein the plurality of groups of condenser vacuum pressure drop rate data correspond to the plurality of groups of pore plates respectively; s3, acquiring air leakage flow data corresponding to the multiple groups of pore plates respectively; s4, fitting the vacuum pressure reduction rate data of the condenser and the orifice plate air leakage flow data which are respectively corresponding to the multiple groups of orifice plates so as to obtain a fitting function of the vacuum pressure reduction rate of the condenser and the orifice plate air leakage flow; s5, acquiring the air leakage flow of the vacuum system of the condenser according to the fitting function. By implementing the invention, the flow of air leaked into the condenser and the vacuum system can be conveniently measured, the accuracy of the measurement result is high, and the influence on the whole turbo generator set is small.
Description
Technical Field
The invention relates to the technical field of air leakage flow measurement, in particular to a condenser and a vacuum system air leakage flow measurement method.
Background
The American Heat transfer institute (HEI) surface condenser Standard gives the air leakage flow of the condenser, and a large number of practices show that the actual leakage flow of a general unit is far smaller than the air leakage flow given by the HEI method. The air leakage flow rate given by the HEI method is only used as the basis of the type selection of the vacuumizing equipment, and cannot be used for calculating the leakage flow rate under the actual operation working condition of the condenser.
The electric power industry standard DL/T932-2005 'condenser and vacuum system operation maintenance guide' gives an approximate calculation formula of air leakage flow, and the air leakage flow is calculated by adopting the formula, so that the equipment volume parameter in the vacuum state needs to be provided, but the volume parameter is related to the operation working condition of the steam turbine, and the equipment volume in the vacuum state is often uncertain.
The traditional measuring method is that an air flowmeter is arranged on a suction pipeline or a discharge pipeline of air extraction equipment to directly measure, the measuring result is influenced by gas state parameters, and the air flowmeter is arranged to improve pipeline resistance and influence on the operation of a condenser. In some improved measuring methods, the condenser air leakage quantity is calculated by the condenser vacuum dropping rate after the vacuum pumping equipment is stopped, but the method has subjectivity in the formula construction process, and the error of the measured condenser air leakage flow is larger.
Disclosure of Invention
The invention aims to solve the technical problems of the prior art and provides a condenser and a method for measuring air leakage flow of a vacuum system.
The technical scheme adopted for solving the technical problems is as follows: a condenser and a method for measuring air leakage flow of a vacuum system are constructed, comprising the following steps: s1, when vacuum pumping equipment corresponding to a vacuum system of the condenser is in a shutdown state and the running state of the condenser is unchanged, air leaks into the condenser through a plurality of groups of pore plates with different apertures;
s2, acquiring a plurality of groups of condenser vacuum pressure reduction rate data in the condenser, wherein the plurality of groups of condenser vacuum pressure reduction rate data correspond to the plurality of groups of pore plates respectively;
s3, acquiring air flow rates of the pore plates corresponding to the multiple groups of pore plates respectively so as to acquire air leakage flow data corresponding to the multiple groups of pore plates respectively according to the air flow rates;
s4, fitting the condenser vacuum pressure reduction rate data and the orifice plate air leakage flow rate data which are respectively corresponding to the multiple groups of orifice plates to obtain a fitting function of the condenser vacuum pressure reduction rate and the orifice plate air leakage flow rate;
s5, acquiring the air leakage flow of the vacuum system of the condenser according to the fitting function.
Preferably, in the step S3, the acquiring the air flow rates of the orifice plates corresponding to the multiple groups of orifice plates respectively to acquire the air leakage flow rate data corresponding to the multiple groups of orifice plates respectively according to the air flow rates includes:
and respectively acquiring air critical flow velocity data and air critical density data at the minimum section of each pore plate, and acquiring the air flow velocity data and the air density data at the minimum section of the pore plate according to the air critical flow velocity data and the air critical density data so as to obtain the air leakage flow velocity data at the minimum section of the pore plate as the air leakage flow velocity data of the pore plate according to the air flow velocity data and the air density data at the minimum section.
Preferably, the acquiring air leakage flow rate data at the smallest section of the orifice plate based on the air critical flow rate data and the air critical density data includes according to the formula
Acquiring air leakage flow data at the minimum section of the orifice plate, wherein d is the diameter at the minimum section of the orifice plate; v cr A critical flow rate of air at a minimum cross section of the orifice plate; ρ cr An air critical density at a minimum cross section of the orifice plate; q i Is the air leakage flow data at the smallest cross section of the orifice plate.
Preferably, the acquiring the air critical flow rate data and the air critical density data at the minimum cross section of each orifice plate includes:
according to the formula
Acquiring air critical flow velocity data at the minimum section of the orifice plate;
according to the formula
Acquiring air critical density data at the smallest section of the orifice plate;
wherein k is the adiabatic index of air; r is the gas constant of air; t' is the corresponding ambient temperature of the condenser; p' is the atmospheric pressure corresponding to the condenser.
Preferably, the K is 1.4, and the R is 287.05J/kg.K.
Preferably, the method for measuring the air leakage flow rate of the condenser and the vacuum system of the invention further comprises the following steps:
s31, confirming whether the pore plate is a standard pore plate, if so, executing the step S4, otherwise, executing the step S32;
s32, correcting the air leakage flow data of the orifice plate to update the air leakage flow data of the orifice plate, and executing the step S4.
Preferably, in the step S32, the correcting the air leakage flow rate data of the orifice plate to update the air leakage flow rate data of the orifice plate includes:
according to the correction formula
q c ＝α·q i
Correcting the air leakage flow data of the orifice plate to update the air leakage flow data of the orifice plate, wherein alpha is the flow correction coefficient of the orifice plate, and q c And (5) updating the air leakage flow data of the orifice plate.
Preferably, in the step S4, the fitting the condenser vacuum pressure drop rate data and the orifice plate air leakage flow rate data corresponding to the multiple groups of orifice plates respectively to obtain a fitting function of the condenser vacuum pressure drop rate and the orifice plate air leakage flow rate includes: fitting condenser vacuum pressure drop rate data and air leakage flow rate data respectively corresponding to the plurality of groups of pore plates by adopting a linear regression analysis method to obtain a linear fitting function, wherein the linear fitting function is as follows:
H＝k 1 ·q+k 2
wherein H is the vacuum pressure drop rate of the condenser; k (k) 1 And k 2 Q is the air leakage flow rate of the orifice plate;
in the step S5, the air leakage flow of the vacuum system of the condenser is obtained according to the fitting function; including according to the formula
Acquiring the air leakage flow of a vacuum system of the condenser, wherein G 0 And the air leakage flow rate of the vacuum system of the condenser.
Preferably, in the step S2, the obtaining a plurality of sets of condenser vacuum pressure drop rate data in the condenser, which correspond to the plurality of sets of pore plates respectively, includes:
s21, acquiring initial vacuum pressure in the condenser before air leaks into the condenser through a plurality of groups of pore plates with different apertures;
s22, monitoring real-time vacuum pressure in the condenser in the air leakage process to obtain a change value of the real-time vacuum pressure relative to the initial vacuum pressure, and obtaining the vacuum pressure reduction rate data according to the change value and the corresponding air leakage duration.
Preferably, the multiple sets of well plates comprise at least 3 sets of well plates.
The condenser and the method for measuring the air leakage flow rate of the vacuum system have the following beneficial effects: the flow of air leaked into the condenser and the vacuum system can be conveniently measured, the accuracy of a measurement result is high, and the influence on the whole turbo generator set is small.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a flow chart of a method for measuring air leakage flow rate of a condenser and a vacuum system according to an embodiment of the present invention;
FIG. 2 is a flow chart of a process of another embodiment of a method for measuring air leakage flow rate of a condenser and vacuum system according to the present invention;
FIG. 3 is a schematic diagram of a fitting function in a method for measuring air leakage flow of a condenser and a vacuum system according to the present invention.
Detailed Description
For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings.
As shown in fig. 1, in a first embodiment of the method for measuring air leakage flow rate of a condenser and a vacuum system according to the present invention, the method includes:
s1, when the vacuum pumping equipment corresponding to the vacuum system of the condenser is in a shutdown state and the running state of the condenser is unchanged, air leaks into the condenser through a plurality of groups of pore plates with different apertures;
s2, acquiring a plurality of groups of condenser vacuum pressure drop rate data in the condenser, wherein the plurality of groups of condenser vacuum pressure drop rate data correspond to the plurality of groups of pore plates respectively; specifically, air can leak into the condenser through a pore plate communicated with the throat part of the condenser, and vacuum pressure drop rate data of the condenser can be obtained in the air leak-in process. Before the process of leaking in air, the vacuum pumping equipment of the vacuum system of the condenser is stopped, namely, the vacuum pumping equipment of the vacuum system of the condenser is in a stopped state in the measurement process. In the measuring process, air needs to be leaked into by adopting a plurality of groups of pore plates with different apertures respectively, so that condenser vacuum pressure reduction rate data corresponding to the plurality of groups of pore plates with different apertures is obtained. Wherein the aperture of each well plate is a known value. It can be understood that the vacuum pressure drop rate data corresponding to the condenser can be obtained through the pressure detection equipment arranged in the tube bundle region of the condenser. In order to ensure the accuracy of the vacuum pressure drop rate data, the method can detect the multipoint pressure of the condenser tube bundle area and perform data processing to obtain detection data which can truly reflect the vacuum pressure drop rate of the condenser tube bundle area.
S3, acquiring air flow rates of the pore plates corresponding to the plurality of groups of pore plates respectively so as to acquire air leakage flow data corresponding to the plurality of groups of pore plates respectively according to the air flow rates; specifically, the process of leaking air through the orifice plate into the condenser can be regarded as a convergent nozzle model in which large space flows to a limited container, and the air flow rate in the orifice plate depends on the pressure of the outlet of the orifice plate (according to the direction of leaking air into the condenser) and the pressure of the inlet of the orifice plate. According to the aerodynamic theory, the flow rate of air in the orifice plate gradually increases as the pressure ratio of the outlet to the inlet of the orifice plate gradually decreases. When the air flow rate at the smallest section in the orifice plate reaches the local sonic velocity, the air flow in the orifice plate reaches a critical state, wherein the orifice plate outlet to inlet pressure ratio at this time is the critical pressure ratio. When the pressure ratio of the outlet to the inlet of the orifice plate is continuously reduced, the air flow rate at the smallest section of the orifice plate is not continuously increased, and the orifice plate is in a flow blocking state. Therefore, when the condenser vacuum pressure is lower than a specific value, the air flow rate at the smallest section of the orifice plate reaches the local sonic velocity, the orifice plate generates a blocking flow when the condenser vacuum pressure is continuously reduced, and the flow rate at the smallest section of the orifice plate is not increased along with the reduction of the condenser vacuum pressure, so that the air leakage flow data of the orifice plate can be obtained correspondingly based on the air flow rate of the orifice plate. The specific value may be a critical pressure value calculated based on the ambient atmospheric pressure, typically 100kPa, which is also suitably varied since the atmospheric pressure at different latitudes may vary slightly.
S4, fitting the vacuum pressure reduction rate data of the condenser and the orifice plate air leakage flow data which are respectively corresponding to the multiple groups of orifice plates so as to obtain a fitting function of the vacuum pressure reduction rate of the condenser and the orifice plate air leakage flow;
s5, acquiring the air leakage flow of the vacuum system of the condenser according to the fitting function. Specifically, after obtaining the condenser vacuum pressure drop rate data and the orifice plate air leakage flow rate data respectively corresponding to the multiple groups of orifice plates, performing data fitting based on the multiple groups of condenser vacuum pressure drop rate data and the orifice plate air leakage flow rate data, and obtaining a fitting function of the vacuum pressure drop rate of the condenser and the orifice plate air leakage flow rate through a common fitting mode so as to obtain a functional relation of the vacuum pressure drop rate of the condenser and the orifice plate air leakage flow rate. And obtaining the air leakage flow of the vacuum system of the leakage condenser according to the functional relation.
Optionally, in step S3, acquiring air flow rates of the orifice plates corresponding to the multiple groups of orifice plates respectively to acquire air leakage flow rate data corresponding to the multiple groups of orifice plates respectively according to the air flow rates includes: and respectively acquiring the air critical flow rate data and the air critical density data at the minimum section of each pore plate, and acquiring the air flow rate data and the air density data at the minimum section of the pore plate according to the air critical flow rate data and the air critical density data so as to obtain the air leakage flow rate data at the minimum section of the pore plate as the air leakage flow rate data of the pore plate according to the air flow rate data and the air density data at the minimum section. Specifically, the leakage flow data of the orifice plate can be obtained according to the principle that the orifice plate generates a blocking flow, and the air leakage flow data at the minimum section of the orifice plate can be obtained through the air critical flow velocity data and the air critical density data at the minimum section of the orifice plate. Wherein the air leakage flow rate data at the smallest cross section of the orifice plate can be taken as the air leakage flow rate data of the orifice plate.
Optionally, obtaining air leakage flow data at a minimum cross section of the orifice plate based on the air critical flow rate data and the air critical density data includes determining a flow rate of air leakage at the minimum cross section based on the formula
Acquiring air leakage flow data at the minimum section of the orifice plate, wherein d is the diameter at the minimum section of the orifice plate; v cr A critical flow rate of air at a minimum cross section of the orifice plate; ρ cr An air critical density at a minimum cross section of the orifice plate; q i Is the air leakage flow data at the smallest cross section of the orifice plate. In particular, the orifice plate is mechanically manufactured so that the aperture of the orifice plate follows the flowThe directions are not exactly the same, some orifice plates are contracted, some orifice plates are expanded, and some orifice plates are contracted and then expanded. The minimum of the pore diameter is taken as the cross section of the study during calculation. Thus, where q i Can represent the air leakage flow data at the minimum section corresponding to the orifice plate with different pore diameters, wherein i can take the values of 0, 1 and 2 … …, which represent the numbers of different orifice plates, d is the diameter of the minimum section of the orifice plate corresponding to the orifice plate, and the diameter unit is mm and v cr The critical flow rate of air at the smallest cross section of the orifice plate is given in m/s; ρ cr Is the critical density of air at the smallest section of the orifice plate in kg/m 3 . It can be appreciated that the air leakage flow rate data q at the minimum cross section of the orifice plate obtained based on this formula i In kg/h, which can understand the mass flow per air leakage, i.e. how much air leaks mass per time. In some scenarios, its air leakage flow rate may also be translated into how much air leakage volume per unit time.
Optionally, acquiring the air critical flow rate data and the air critical density data at the smallest cross section of each orifice plate includes:
according to the formula
Acquiring air critical flow velocity data at the minimum section of the orifice plate;
according to the formula
Acquiring air critical density data at the smallest section of the orifice plate;
wherein k is the adiabatic index of air; r is the gas constant of air; t' is the corresponding ambient temperature of the condenser; p' is the atmospheric pressure corresponding to the condenser. Specifically, the calculation of the air critical flow rate data and the air critical density data can be performed according to the above formula, k is the adiabatic index of air, which is a constant, and generally takes a value of 1.4; r is the gas constant of air, and is generally 287.05J/kg.K; t 'is the ambient temperature of the area where the condenser is located, and the unit of T' is K; p' is the atmospheric pressure of the area where the condenser is located, and the unit corresponds to Pa. The air critical flow velocity data and the air critical density data of the minimum section of the orifice plate are obtained according to the formula respectively. Wherein the values of K and R can be properly adjusted according to different precision requirements.
As shown in fig. 2, in an embodiment, the method for measuring air leakage flow of the condenser and the vacuum system according to the present invention further includes: s31, confirming whether the pore plate is a standard pore plate, if so, executing the step S4, otherwise, executing the step S32; s32, correcting the air leakage flow data of the orifice plate to update the air leakage flow data of the orifice plate, and executing step S4. Specifically, the acquisition of air leakage flow data of the orifice plate is based on the fact that the orifice plate is a standard orifice plate, the standard orifice plate is an orifice plate manufactured according to the specified requirements of the national standard, and the non-standard orifice plate is a specially designed orifice plate inconsistent with the national standard. The medium flow of the non-standard orifice plate may have larger access to the standard orifice plate of the same type, and the acquired air leakage flow data of the orifice plate needs to be corrected, and the fitting operation in step S4 is performed according to the corrected air leakage flow data of the orifice plate.
Optionally, in step S32, correcting the air leakage flow rate data of the orifice plate to update the air leakage flow rate data of the orifice plate includes:
according to the correction formula
q c ＝α·q i
Correcting air leakage flow data of the orifice plate to update the air leakage flow data of the orifice plate, wherein alpha is a flow correction coefficient of the orifice plate, and q c And (5) updating the air leakage flow data of the orifice plate. Specifically, when the orifice plate is a non-standard orifice plate, the flow correction coefficient of the orifice plate can be used for correcting the acquired air leakage flow data. Wherein the orifice plate flow correction factor is obtained from flow calibration data for a non-standard orifice plate.
Optionally, in step S4, fitting the condenser vacuum pressure drop rate data and the orifice plate air leakage flow rate data corresponding to the multiple groups of orifice plates respectively to obtain a fitting function of the condenser vacuum pressure drop rate and the orifice plate air leakage flow rate, including: fitting condenser vacuum pressure drop rate data and air leakage flow rate data respectively corresponding to a plurality of groups of pore plates by adopting a linear regression analysis method to obtain a linear fitting function, wherein the linear fitting function is as follows:
H＝k 1 ·q+k 2
h is the vacuum pressure drop rate of the condenser, and the unit is Pa/s; k (k) 1 And k 2 Q is the air leakage flow rate of the orifice plate and is given in kg/h;
in step S5, obtaining the air leakage flow of the vacuum system of the condenser according to the fitting function; including according to the formula
Acquiring air leakage flow of vacuum system of condenser, wherein G 0 The unit of the air leakage flow is kg/h of the vacuum system of the condenser.
Specifically, the fitting process of the obtained vacuum pressure drop rate data of the condenser and the pore plate air leakage flow rate data corresponding to the multiple groups of pore plates respectively can be fitted by adopting a common fitting mode, in this embodiment, in order to simplify the fitting process while ensuring accurate test results, a linear regression analysis method can be adopted for fitting so as to obtain a linear fitting function corresponding to the vacuum pressure drop rate of the condenser and the pore plate air leakage flow rate, wherein the vacuum pressure drop rate H of the condenser and the pore plate air leakage flow rate q are variables, and k 1 And k 2 The linear coefficient obtained by fitting by a linear regression analysis method is a constant. The relation between the vacuum pressure drop rate H of the condenser and the air leakage flow q of the pore plate can be easily obtained according to the fitting function, namely, it can be understood that the vacuum pressure drop rate H of the condenser is actually formed byThe whole leakage flow of the condenser is generated, when air leaks into the condenser through pore plates with different apertures, the whole leakage flow of the condenser comprises the sum of the pore plate air leakage flow and the vacuum system air leakage flow, and the vacuum system air leakage flow is a constant when the running state of the condenser is stable. It can be understood that when the air leakage amount of the orifice plate is zero, the vacuum pressure drop rate of the corresponding condenser is obtained to be k 2 The vacuum pressure drop rate is generated by the vacuum system air leakage flow of the condenser, and is based on the linear coefficient k of the vacuum pressure drop rate H of the system condenser and the orifice plate air leakage flow 1 The linear coefficient of the vacuum pressure drop rate H of the condenser and the whole leakage flow of the condenser is k 1 The value of the vacuum pressure drop rate according to the corresponding condenser is k when the air leakage flow q of the orifice plate is zero 2 And a linear coefficient k 1 Corresponding air leakage flow G of vacuum system of condenser 0 I.e.
Optionally, in step S2, acquiring multiple sets of condenser vacuum pressure drop rate data corresponding to multiple sets of pore plates in the condenser, including: s21, acquiring initial vacuum pressure in the condenser before air leaks into the condenser through a plurality of groups of pore plates with different apertures; s22, monitoring the real-time vacuum pressure in the condenser in the air leakage process to obtain a change value of the real-time vacuum pressure relative to the initial vacuum pressure, and obtaining the vacuum pressure reduction rate data according to the change value and the corresponding air leakage duration. Specifically, on the premise that the running state of the condenser is stable, the time of external air flowing into the condenser through the pore plate is controlled, the change value of the pressure of the condenser is recorded, and the pressure change rate of the condenser is finally obtained.
Optionally, the multiple sets of well plates comprise at least 3 sets of well plates. Specifically, in order to ensure accuracy of the fitting function, the data corresponding to the pore plate may be 3 groups or more.
The specific implementation cases are as follows:
taking an example of air leakage flow test on a condenser of a 170 kilowatt-level turbine unit of a nuclear power plant. The outside temperature of the condenser during the test is 34 ℃, and the outside atmospheric pressure is 101kPa. The pore diameter of the pore plate installed before the test is shown in Table 1, the air leakage stop valve is opened during the test, the air leakage stop valve is closed when the pressure of the condenser rises by 2.5kPa, and the time for the pressure to rise by 2.5kPa is recorded. In consideration of the fact that too high pressure rise causes the efficiency of the steam turbine to be reduced, the operation of the whole steam turbine generator unit is affected, the pressure rise is preferably in the range of 2-4 kPa, and therefore the pressure rise takes a value of 2.5kPa. The air leakage flow rates of the orifice plates for each aperture obtained according to the above procedure are shown in table 1,
TABLE 1 orifice plate air leakage flow
As shown in fig. 3, the relationship between the vacuum pressure drop rate and the orifice leakage flow rate is fitted to the data in table 1 by using a linear regression analysis method:
H＝0.0429·q+1.4253
the air leakage flow of the condenser can be further calculated as follows:
G 0 ＝33.2kg/h
it is to be understood that the above examples only represent preferred embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention; it should be noted that, for a person skilled in the art, the above technical features can be freely combined, and several variations and modifications can be made without departing from the scope of the invention; therefore, all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
Claims (8)
1. The utility model provides a condenser and vacuum system air leakage flow measurement method which is characterized in that the method comprises the following steps:
s1, when vacuum pumping equipment corresponding to a vacuum system of the condenser is in a shutdown state and the running state of the condenser is unchanged, air leaks into the condenser through a plurality of groups of pore plates with different apertures, wherein the plurality of groups of pore plates comprise at least 3 groups of pore plates;
s2, acquiring a plurality of groups of condenser vacuum pressure reduction rate data in the condenser, wherein the plurality of groups of condenser vacuum pressure reduction rate data correspond to the plurality of groups of pore plates respectively;
s3, acquiring air flow rates of the pore plates corresponding to the multiple groups of pore plates respectively so as to acquire air leakage flow data corresponding to the multiple groups of pore plates respectively according to the air flow rates;
s4, fitting the condenser vacuum pressure reduction rate data and the orifice plate air leakage flow rate data which are respectively corresponding to the multiple groups of orifice plates to obtain a fitting function of the condenser vacuum pressure reduction rate and the orifice plate air leakage flow rate;
s5, acquiring the air leakage flow of the vacuum system of the condenser according to the fitting function;
in the step S4, the fitting the condenser vacuum pressure drop rate data and the orifice plate air leakage flow rate data corresponding to the multiple groups of orifice plates respectively to obtain a fitting function of the condenser vacuum pressure drop rate and the orifice plate air leakage flow rate includes: fitting condenser vacuum pressure drop rate data and air leakage flow rate data respectively corresponding to the plurality of groups of pore plates by adopting a linear regression analysis method to obtain a linear fitting function, wherein the linear fitting function is as follows:
H＝k 1 ·q+k 2
wherein H is the vacuum pressure drop rate of the condenser; k (k) 1 And k 2 Q is a constant, the air leakage flow rate of the orifice plate;
in the step S5, the air leakage flow of the vacuum system of the condenser is obtained according to the fitting function; including according to the formula
Acquiring the air leakage flow of a vacuum system of the condenser, wherein G 0 And the air leakage flow rate of the vacuum system of the condenser.
2. The method according to claim 1, wherein in the step S3, the step of obtaining the air flow rates of the orifice plates corresponding to the plurality of sets of orifice plates respectively to obtain the air leakage flow rate data corresponding to the plurality of sets of orifice plates respectively according to the air flow rates includes:
and respectively acquiring air critical flow velocity data and air critical density data at the minimum section of each pore plate, and acquiring the air flow velocity data and the air density data at the minimum section of the pore plate according to the air critical flow velocity data and the air critical density data so as to obtain the air leakage flow velocity data at the minimum section of the pore plate as the air leakage flow velocity data of the pore plate according to the air flow velocity data and the air density data at the minimum section.
3. The method of claim 2, wherein the obtaining air leakage flow rate data at a minimum cross section of the orifice plate based on the air critical flow rate data and the air critical density data comprises according to a formula
Acquiring air leakage flow data at the minimum section of the orifice plate, wherein d is the diameter at the minimum section of the orifice plate; v cr A critical flow rate of air at a minimum cross section of the orifice plate; ρ cr An air critical density at a minimum cross section of the orifice plate; q i Is the air leakage flow data at the smallest cross section of the orifice plate.
4. The method for measuring air leakage flow rate of condenser and vacuum system according to claim 3, wherein said acquiring air critical flow rate data and air critical density data at the minimum cross section of each orifice plate comprises:
according to the formula
Acquiring air critical flow velocity data at the minimum section of the orifice plate;
according to the formula
Acquiring air critical density data at the smallest section of the orifice plate;
wherein k is the adiabatic index of air; r is the gas constant of air; t' is the corresponding ambient temperature of the condenser; p' is the atmospheric pressure corresponding to the condenser.
5. The method for measuring the air leakage flow rate of a condenser and a vacuum system according to claim 4, wherein the K value is 1.4, and the R value is 287.05J/kg.K.
6. The condenser and vacuum system air leakage flow measurement method according to claim 3, further comprising:
s31, confirming whether the pore plate is a standard pore plate, if so, executing the step S4, otherwise, executing the step S32;
s32, correcting the air leakage flow data of the orifice plate to update the air leakage flow data of the orifice plate, and executing the step S4.
7. The method according to claim 6, wherein in the step S32, the correcting the air leakage flow rate data of the orifice plate to update the air leakage flow rate data of the orifice plate includes:
according to the correction formula
q c ＝α·q i
Correcting the air leakage flow data of the orifice plate to update the air leakage flow data of the orifice plate, wherein alpha is the flow correction coefficient of the orifice plate, and q c And (5) updating the air leakage flow data of the orifice plate.
8. The method for measuring air leakage flow rate of a condenser and a vacuum system according to claim 1, wherein in the step S2, the obtaining a plurality of sets of condenser vacuum pressure drop rate data in the condenser, which correspond to the plurality of sets of orifice plates, respectively, includes:
s21, acquiring initial vacuum pressure in the condenser before air leaks into the condenser through a plurality of groups of pore plates with different apertures;
s22, monitoring real-time vacuum pressure in the condenser in the air leakage process to obtain a change value of the real-time vacuum pressure relative to the initial vacuum pressure, and obtaining the vacuum pressure reduction rate data according to the change value and the corresponding air leakage duration.
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