CN112629602A - Condenser and vacuum system air leakage flow measuring method - Google Patents
Condenser and vacuum system air leakage flow measuring method Download PDFInfo
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- G01—MEASURING; TESTING
- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
The invention relates to a condenser and a method for measuring air leakage flow of a vacuum system, comprising S1, when a vacuumizing device corresponding to the condenser is in an off-state and the condenser is in a constant operating state, respectively leaking air into the condenser through a plurality of groups of pore plates with different apertures; s2, acquiring multiple groups of condenser vacuum pressure reduction rate data corresponding to multiple groups of pore plates in the condenser respectively; s3, acquiring air leakage flow data corresponding to the multiple groups of pore plates respectively; s4, fitting condenser vacuum pressure reduction rate data and pore plate air leakage flow data corresponding to a plurality of groups of pore plates respectively to obtain a fitting function of the condenser vacuum pressure reduction rate and the pore plate air leakage flow; and S5, acquiring the air leakage flow of the vacuum system of the condenser according to the fitting function. The invention can conveniently measure the flow of air leaked into the condenser and the vacuum system, has high accuracy of the measurement result and has little influence on the whole turbo generator set.
Description
Technical Field
The invention relates to the technical field of air leakage flow measurement, in particular to a condenser and a method for measuring air leakage flow of a vacuum system.
Background
The American heat transfer Association (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 given by the HEI method is only used as a basis for the type selection of the vacuum pumping equipment, and cannot be used for calculating the leakage flow under the actual operation condition of the condenser.
The standard DL/T932-.
In the traditional measurement method, an air flow meter is arranged on a suction pipeline or a discharge pipeline of the air extraction equipment for direct measurement, the measurement result is influenced by gas state parameters, and the installation of the air flow meter improves the pipeline resistance and influences the operation of the condenser. In some improved measurement methods, the air leakage rate of the condenser is calculated by the vacuum reduction rate of the condenser after the operation of the vacuum pumping equipment is stopped, but the formula construction process has subjectivity, and the error of the measured air leakage rate of the condenser is large.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a condenser and a method for measuring an air leakage flow rate of a vacuum system, aiming at some technical defects in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: a method for measuring air leakage flow of a condenser and a vacuum system is constructed, and comprises the following steps: s1, respectively leaking air into the condenser through a plurality of groups of pore plates with different apertures when the vacuum pumping equipment corresponding to the vacuum system of the condenser is in an off state and the condenser is not in a constant operating state;
s2, acquiring multiple groups of condenser vacuum pressure reduction rate data corresponding to the multiple groups of pore plates in the condenser respectively;
s3, acquiring air flow rates of the pore plates respectively corresponding to the multiple groups of pore plates so as to acquire air leakage flow data respectively corresponding to the multiple groups of pore plates according to the air flow rates;
s4, fitting condenser vacuum pressure reduction rate data and pore plate air leakage flow data which correspond to the multiple groups of pore plates respectively to obtain a fitting function of the condenser vacuum pressure reduction rate and the pore plate air leakage flow;
and S5, obtaining the air leakage flow of the vacuum system of the condenser according to the fitting function.
Preferably, in the step S3, the acquiring air flow rates of the orifice plates respectively corresponding to the plurality of sets of orifice plates to acquire air leakage flow data respectively corresponding to the plurality of sets of orifice plates according to the air flow rates includes:
respectively acquiring air critical flow velocity data and air critical density data at the minimum section of each orifice plate, acquiring air flow velocity data and air density data at the minimum section of the orifice plate according to the air critical flow velocity data and the air critical density data, and acquiring air leakage flow data at the minimum section of the orifice plate as the air leakage flow data of the orifice plate according to the air flow velocity data and the air density data at the minimum section.
Preferably, the obtaining of the air leakage flow data at the minimum section of the orifice plate according to the air critical flow data and the air critical density data comprises obtaining the air leakage flow data at the minimum section of the orifice plate according to a formula
Acquiring air leakage flow data at the minimum section of the orifice plate, wherein d is the diameter of the minimum section of the orifice plate; v. ofcrIs the critical flow rate of air at the smallest cross section of the orifice plate; rhocrIs the critical density of air at the smallest cross section of the orifice plate; q. q.siIs 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 critical flow rate data of air at the minimum section of the orifice plate;
according to the formula
Acquiring air critical density data at the minimum 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; and P' is the atmospheric pressure corresponding to the condenser.
Preferably, the K value is 1.4, and the R value is 287.05J/kg.K.
Preferably, the method for measuring the air leakage flow of the condenser and the vacuum system further comprises the following steps:
s31, determining 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 data of the leakage flow rate of air of the orifice plate to update the data of the leakage flow rate of air of the orifice plate includes:
according to a correction formula
qc＝α·qi
Correcting the 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, q is a flow correction coefficient of the orifice platecThe updated orifice plate air leakage flow data.
Preferably, in step S4, the fitting the condenser vacuum pressure reduction rate data and the orifice plate air leakage flow rate data corresponding to the multiple sets of orifice plates respectively to obtain a fitting function of the condenser vacuum pressure reduction rate and the orifice plate air leakage flow rate includes: fitting condenser vacuum pressure reduction rate data and air leakage flow data respectively corresponding to the multiple 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＝k1·q+k2
wherein H is the vacuum pressure reduction rate of the condenser; k is a radical of1And k2Is a constant, q is the air leakage flow of the orifice plate;
in the step S5, the vacuum system air leakage flow of the condenser is obtained according to the fitting function; including according to the formula
Obtaining the air leakage flow of the vacuum system of the condenser, wherein G0The air leakage flow rate of the vacuum system of the condenser.
Preferably, in step S2, the acquiring multiple sets of condenser vacuum pressure reduction rate data corresponding to the multiple sets of perforated plates in the condenser 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 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.
Preferably, the plurality of sets of orifice plates comprises at least 3 sets of orifice plates.
The condenser and the method for measuring the air leakage flow of the vacuum system have the following beneficial effects that: 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 flowchart illustrating an embodiment of a method for measuring an air leakage flow of a condenser and a vacuum system according to the present invention;
FIG. 2 is a flowchart of another embodiment of the method for measuring air leakage flow of a condenser and a vacuum system according to the present invention;
fig. 3 is a schematic diagram of a fitting function in the method for measuring the air leakage flow of the condenser and the vacuum system according to the present invention.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
As shown in fig. 1, a first embodiment of a method for measuring an air leakage flow rate of a condenser and a vacuum system according to the present invention includes:
s1, when the vacuum pumping equipment corresponding to the vacuum system of the condenser is in an off state and the condenser is not in a constant operating state, respectively leaking air into the condenser through a plurality of groups of pore plates with different pore diameters;
s2, acquiring multiple groups of condenser vacuum pressure reduction rate data corresponding to multiple groups of pore plates in the condenser respectively; specifically, air can leak into the condenser through the pore plate communicated with the throat of the condenser, and vacuum pressure reduction rate data of the condenser is acquired in the air leakage process. Before the process of air leakage, the vacuumizing equipment of the vacuum system of the condenser is stopped, namely, the vacuumizing equipment of the vacuum system of the condenser is in a stopped state in the measuring process. In the measuring process, a plurality of groups of pore plates with different apertures are required to leak air respectively so as to obtain condenser vacuum pressure reduction rate data corresponding to the plurality of groups of pore plates with different apertures. Wherein the pore diameter of each pore plate is a known value. It can be understood that the vacuum pressure reduction rate data corresponding to the condenser can be obtained through the pressure detection equipment arranged in the condenser tube bundle area. In order to ensure the accuracy of the vacuum pressure reduction rate data, the method can detect the multipoint pressure of the condenser tube bundle area and perform data processing to obtain the detection data which can actually reflect the vacuum pressure reduction rate of the condenser tube bundle area finally.
S3, acquiring air flow rates of the pore plates corresponding to the multiple groups of pore plates respectively to acquire air leakage flow data corresponding to the multiple groups of pore plates respectively according to the air flow rates; specifically, the process of air flowing through the orifice plate and leaking into the condenser can be regarded as a model of a contracted nozzle pipe flowing from a large space to a limited container, and the air flow rate in the orifice plate depends on the pressure of an outlet (according to the direction of air leaking into the condenser) of the orifice plate and the pressure of an inlet of the orifice plate. According to the aerodynamic theory, the flow velocity of the air in the orifice plate is gradually increased when the pressure ratio of the outlet to the inlet of the orifice plate is gradually reduced. When the air flow velocity at the minimum section in the orifice plate reaches the local sonic velocity, the air flow in the orifice plate reaches a critical state, wherein the pressure ratio of the outlet to the inlet of the orifice plate at the moment is a critical pressure ratio. When the pressure ratio of the outlet to the inlet of the orifice plate is continuously reduced, the air flow speed at the minimum section of the orifice plate is not continuously increased, and the orifice plate is in a flow blocking state. Therefore, when the vacuum pressure of the condenser is lower than a specific value, the air flow rate at the minimum section of the pore plate reaches the local sound speed, the pore plate generates blocking flow when the vacuum pressure of the condenser is continuously reduced, and the flow rate at the minimum section of the pore plate is not increased along with the reduction of the vacuum pressure of the condenser, so that air leakage flow data of the pore plate can be obtained correspondingly based on the air flow rate of the pore plate. The specific value may be a critical pressure value calculated based on the ambient atmospheric pressure, which is usually 100kPa, and the characteristic value is appropriately changed since the atmospheric pressure at different latitudes is slightly different.
S4, fitting condenser vacuum pressure reduction rate data and pore plate air leakage flow data corresponding to a plurality of groups of pore plates respectively to obtain a fitting function of the condenser vacuum pressure reduction rate and the pore plate air leakage flow;
and S5, acquiring the air leakage flow of the vacuum system of the condenser according to the fitting function. Specifically, after condenser vacuum pressure reduction rate data and orifice plate air leakage flow data corresponding to a plurality of groups of orifice plates respectively are obtained, data fitting is performed based on the plurality of groups of condenser vacuum pressure reduction rate data and the orifice plate air leakage flow data, and a fitting function of the condenser vacuum pressure reduction rate and the orifice plate air leakage flow is obtained through a common fitting mode, so that a functional relation between the condenser vacuum pressure reduction rate and the orifice plate air leakage flow is obtained. And obtaining the air leakage flow of the vacuum system of the leakage condenser according to the functional relation.
Optionally, in step S3, obtaining the air flow rates of the orifice plates respectively corresponding to the multiple sets of orifice plates to obtain the air leakage flow data respectively corresponding to the multiple sets of orifice plates according to the air flow rates includes: respectively acquiring air critical flow speed data and air critical density data at the minimum section of each orifice plate, acquiring air flow speed data and air density data at the minimum section of the orifice plate according to the air critical flow speed data and the air critical density data, and acquiring air leakage flow data at the minimum section of the orifice plate as air leakage flow data of the orifice plate according to the air flow speed data and the air density data at the minimum section. Specifically, the method for acquiring the leakage flow data of the orifice plate can acquire the air leakage flow data at the minimum section of the orifice plate through the air critical flow speed data and the air critical density data at the minimum section of the orifice plate according to the principle that the orifice plate generates the blocking flow. Wherein the air leakage flow data at the minimum cross-section of the orifice plate may be taken as the air leakage flow data of the orifice plate.
Optionally, obtaining air leakage flow data at the minimum cross section of the orifice plate according to the air critical flow data and the air critical density data, including according to a formula
Acquiring air leakage flow data at the minimum section of the orifice plate, wherein d is the diameter of the minimum section of the orifice plate; v. ofcrIs the critical flow rate of air at the smallest cross section of the orifice plate; rhocrIs the critical density of air at the smallest cross section of the orifice plate; q. q.siIs the air leakage flow data at the smallest cross section of the orifice plate. Specifically, the pore plate is not completely the same in pore size along the flow direction due to mechanical manufacturing, and some pore plates are contracted, some expanded, or expanded after being contracted. The minimum of the aperture is taken as the section of the study in the calculation. Thus, wherein qiCan represent air leakage flow data at the minimum cross section corresponding to the orifice plates with different apertures, wherein i can take values of 0, 1 and 2 … … which represent different orifice plate numbers, d is the diameter of the minimum cross section of the orifice plate corresponding to the orifice plate, and the diameter unit is mm, vcrIs the critical flow velocity of air at the smallest cross section of the orifice plate, which is expressed in m/s; rhocrIs the critical density of air at the smallest cross section of the orifice plate, and has a unit of kg/m3. It can be understood that the air leakage flow amount data q at the minimum section of the orifice plate obtained based on this formulaiThe unit is kg/h, and the mass flow rate of the unit air leakage, namely the mass of the air leakage in the unit time can be understood. In some scenarios, the air leakage flow rate can also be converted into what volume of air leakage per unit time.
Optionally, acquiring air critical flow rate data and air critical density data at the minimum cross section of each orifice plate includes:
according to the formula
Acquiring critical flow rate data of air at the minimum section of the orifice plate;
according to the formula
Acquiring air critical density data at the minimum 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; and P' is the atmospheric pressure corresponding to the condenser. Specifically, the air critical flow rate data and the air critical density data can be calculated according to the above formula, where k is an adiabatic index of air, which is a constant and usually takes a value of 1.4; r is the gas constant of air, and is usually 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 region where the condenser is located, and the unit of P' corresponds to Pa. The air critical flow velocity data and the air critical density data at the minimum section of the orifice plate are obtained according to the formula respectively. The values of K and R can be properly adjusted according to different precision requirements.
As shown in fig. 2, in an embodiment of the present invention, the method for measuring an air leakage flow rate of a condenser and a vacuum system further includes: s31, determining whether the orifice plate is a standard orifice plate, if so, executing a step S4, otherwise, executing a 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. Specifically, the air leakage flow data of the orifice plate is acquired based on the orifice plate as a standard orifice plate, the standard orifice plate is an orifice plate manufactured according to the specified requirements of the national standard, and the nonstandard orifice plate is an orifice plate which is specially designed and is inconsistent with the national standard. The medium flow of the non-standard orifice plate may have a larger entrance and exit with the same type of standard orifice plate, and the obtained 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, the correcting the data of the air leakage flow rate of the orifice plate to update the data of the air leakage flow rate of the orifice plate includes:
according to a correction formula
qc＝α·qi
Correcting the 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, qcThe updated orifice plate air leakage flow data. Specifically, when the orifice plate is a non-standard orifice plate, the obtained air leakage flow data can be corrected by the flow correction coefficient of the orifice plate. Wherein the flow correction factor for the orifice plate is obtained from flow calibration data for a non-standard orifice plate.
Optionally, in step S4, fitting condenser vacuum pressure reduction rate data and orifice plate air leakage flow data corresponding to multiple sets of orifice plates respectively to obtain a fitting function of the condenser vacuum pressure reduction rate and the orifice plate air leakage flow, including: fitting condenser vacuum pressure reduction rate data and air leakage flow 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＝k1·q+k2
wherein H is the vacuum pressure reduction rate of the condenser, and the unit of H is Pa/s; k is a radical of1And k2Is a constant, q is the air leakage flow of the orifice plate, and the unit is kg/h;
in step S5, acquiring a vacuum system air leakage flow rate of the condenser according to the fitting function; including according to the formula
Obtaining the air leakage flow of the vacuum system of the condenser, wherein G0The unit of the air leakage flow of the vacuum system of the condenser is kg/h.
Specifically, fitting process of condenser vacuum pressure reduction rate data and pore plate air leakage flow data respectively corresponding to multiple groups of obtained pore plates can be fitted by adopting a common fitting mode, in the embodiment, in order to simplify the fitting process while ensuring accuracy of test results, fitting can be carried out by adopting a linear regression analysis method to obtain a linear fitting function corresponding to the condenser vacuum pressure reduction rate and the pore plate air leakage flow, wherein the condenser vacuum pressure reduction rate H and the pore plate air leakage flow q are variables, and k is k1And k2The linear coefficient obtained by fitting by linear regression analysis is a constant. According to the fitting function, the relation between the vacuum pressure reduction rate H of the condenser and the orifice plate air leakage flow q can be easily obtained, namely, the vacuum pressure reduction rate H of the condenser is actually generated by the whole leakage flow of the condenser, when air leaks into the condenser through orifice plates with different apertures, the whole leakage flow of the condenser comprises the sum of the orifice plate air leakage flow and the vacuum system air leakage flow, and the vacuum system air leakage flow is a constant when the operation state of the condenser is stable. It can be understood that when the air leakage of the orifice plate is zero, the value of the vacuum pressure drop rate of the corresponding condenser is k2The vacuum pressure reduction rate is generated completely by the vacuum system air leakage flow of the condenser and is based on the linear coefficient k of the vacuum pressure reduction rate H and the orifice plate air leakage flow of the system condenser1Obtaining a linear coefficient k between the vacuum pressure reduction rate H of the condenser and the whole leakage flow of the condenser1When the obtained orifice plate air leakage flow q is zero, the value according to the vacuum pressure reduction rate of the corresponding condenser is k2And a linear coefficient k1Vacuum system air leakage flow G of condenser0I.e. by
Optionally, in step S2, obtaining multiple sets of condenser vacuum pressure drop rate data corresponding to the multiple sets of hole plates in the condenser 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; and 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 vacuum pressure reduction rate data according to the change value and the corresponding air leakage duration. Specifically, on the premise that the operating state of the condenser is stable, the time that the external air flows 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 plurality of sets of orifice plates comprises at least 3 sets of orifice plates. Specifically, in order to ensure the accuracy of the fitting function, the data corresponding to the well plate may be 3 sets or more.
The specific implementation case is as follows:
an air leakage flow test is performed on a condenser of a 170-ten-thousand kilowatt-level turbine unit of a nuclear power plant as an example. During the test, the external temperature of the condenser was 34 ℃ and the external atmospheric pressure was 101 kPa. The hole diameters of the holes installed before the test are 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. Considering that the efficiency of the steam turbine is reduced due to too large pressure rise, and the operation of the whole steam turbine generator unit is affected, the pressure rise is preferably within the range of 2-4 kPa, and the value is 2.5 kPa. The orifice plate air leakage flow rates for each aperture obtained according to the above process are shown in table 1,
TABLE 1 orifice plate air leakage flow
As shown in fig. 3, a linear regression analysis method is used to fit the relationship between the vacuum pressure drop rate and the orifice plate leakage flow rate to the data in table 1 as follows:
H＝0.0429·q+1.4253
the air leakage flow of the condenser can be further calculated as follows:
G0＝33.2kg/h
it is to be understood that the foregoing examples, while indicating the preferred embodiments of the invention, are given by way of illustration and description, and are not to be construed as limiting the scope of the invention; it should be noted that, for those skilled in the art, the above technical features can be freely combined, and several changes and modifications can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention; therefore, all equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.
Claims (10)
1. A method for measuring air leakage flow of a condenser and a vacuum system is characterized by comprising the following steps:
s1, respectively leaking air into the condenser through a plurality of groups of pore plates with different apertures when the vacuum pumping equipment corresponding to the vacuum system of the condenser is in an off state and the condenser is not in a constant operating state;
s2, acquiring multiple groups of condenser vacuum pressure reduction rate data corresponding to the multiple groups of pore plates in the condenser respectively;
s3, acquiring air flow rates of the pore plates respectively corresponding to the multiple groups of pore plates so as to acquire air leakage flow data respectively corresponding to the multiple groups of pore plates according to the air flow rates;
s4, fitting condenser vacuum pressure reduction rate data and pore plate air leakage flow data which correspond to the multiple groups of pore plates respectively to obtain a fitting function of the condenser vacuum pressure reduction rate and the pore plate air leakage flow;
and S5, obtaining the air leakage flow of the vacuum system of the condenser according to the fitting function.
2. The method for measuring the air leakage flow rate of a condenser and a vacuum system according to claim 1, wherein in the step S3, the 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 comprises:
respectively acquiring air critical flow velocity data and air critical density data at the minimum section of each orifice plate, acquiring air flow velocity data and air density data at the minimum section of the orifice plate according to the air critical flow velocity data and the air critical density data, and acquiring air leakage flow data at the minimum section of the orifice plate as the air leakage flow data of the orifice 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 step of obtaining the air leakage flow data at the minimum cross section of the orifice plate according to the air critical flow data and the air critical density data comprises obtaining the air leakage flow data at the minimum cross section of the orifice plate according to a formula
Acquiring air leakage flow data at the minimum section of the orifice plate, wherein d is the diameter of the minimum section of the orifice plate; v. ofcrIs the critical flow rate of air at the smallest cross section of the orifice plate; rhocrIs the critical density of air at the smallest cross section of the orifice plate; q. q.siIs the air leakage flow data at the smallest cross section of the orifice plate.
4. The method according to claim 3, wherein the obtaining of the critical flow rate data and the critical density data of the air at the minimum cross section of each orifice plate comprises:
according to the formula
Acquiring critical flow rate data of air at the minimum section of the orifice plate;
according to the formula
Acquiring air critical density data at the minimum 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; and P' is the atmospheric pressure corresponding to the condenser.
5. The method for measuring the air leakage flow of the condenser and the vacuum system as claimed in claim 4, wherein the K value is 1.4, and the R value is 287.05J/kg-K.
6. A condenser and vacuum system air leakage flow measurement method according to claim 3, further comprising:
s31, determining 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 the step S32 of correcting the data of the air leakage flow rate of the orifice plate to update the data of the air leakage flow rate of the orifice plate comprises:
according to a correction formula
qc＝α·qi
Correcting the 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, q is a flow correction coefficient of the orifice platecThe updated orifice plate air leakage flow data.
8. The method according to claim 1, wherein in step S4, the fitting the condenser vacuum pressure drop rate data and the orifice plate air leakage flow rate data corresponding to the plurality of sets of orifice plates 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 reduction rate data and air leakage flow data respectively corresponding to the multiple 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＝k1·q+k2
wherein H is the vacuum pressure reduction rate of the condenser; k is a radical of1And k2Is a constant, q is the air leakage flow of the orifice plate;
in the step S5, the vacuum system air leakage flow of the condenser is obtained according to the fitting function; including according to the formula
Obtaining the air leakage flow of the vacuum system of the condenser, wherein G0The air leakage flow rate of the vacuum system of the condenser.
9. The method according to claim 1, wherein the step S2 of obtaining multiple sets of condenser vacuum pressure drop rate data corresponding to the multiple sets of perforated plates in the condenser comprises:
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.
10. The method of measuring air leakage flow of a condenser and vacuum system of claim 1, wherein the plurality of sets of perforated plates comprises at least 3 sets of perforated plates.
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| CN113569497A (en) * | 2021-07-07 | 2021-10-29 | 浙江浙能嘉华发电有限公司 | Soft measurement method for cooling water flow of condenser |
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| CN113569497B (en) * | 2021-07-07 | 2024-04-02 | 浙江浙能嘉华发电有限公司 | Soft measurement method for condenser cooling water flow |
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