CN114860006A - Concentration compensation method of gas flow control device - Google Patents
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Abstract
The utility model provides a concentration compensation method of a gas flow control device, which comprises the steps of obtaining the theoretical pressure difference of a differential pressure sensor and the initial opening value of a flow regulating unit according to the target flow, controlling the flow regulating unit based on the initial opening value, and obtaining the actual pressure difference of the differential pressure sensor; judging whether the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is greater than 0 and less than or equal to a threshold value, if not, correcting the initial opening value through the actual opening value to adjust the flow regulating unit; if so, comparing the actual pressure difference with the theoretical pressure difference, if the actual pressure difference is larger than the theoretical pressure difference, compensating the actually measured concentration of the output gas by adopting a first compensation coefficient, and if not, compensating the actually measured concentration of the output gas by adopting a second compensation coefficient. The technical problem of gas concentration change caused by the fact that the flow control device cannot reach the target flow due to slight deviation of uncorrectable pressure of the gas inlet end or small change of atmospheric pressure of the field environment is effectively solved.
Description
Technical Field
The disclosure relates to the technical field of gas analysis, in particular to a concentration compensation method of a gas flow control device.
Background
When the air inlet end or the air outlet end of the pressure type gas flow controller is changed, the flow can not be adjusted to the target flow value all the time. For example, when the air inlet end or the flow regulating unit has a half-blocking fault, the air inlet resistance is increased, so that the theoretical pressure difference can not be reached even when the flow regulating unit is fully opened, and the flow is small; or the service life of the flow regulating unit is reduced due to overlong service time, and the actual opening degree is larger than a theoretical opening degree control command issued by the single chip microcomputer, so that the flow is larger. On the other hand, the pressure at the gas outlet end is atmospheric pressure, and the change of the pressure at the gas outlet end with time is small under indoor conditions with good environment, but the pressure at the gas outlet end has small change under outdoor conditions with poor environment, for example, the pressure at the gas outlet end changes slightly within ± 2kpa, and the change of the pressure at the gas outlet end causes the output flow of the gas flow controller to be larger or smaller.
The concentration of the gas output from the gas flow controller is usually detected by a mass-type detector, and the concentration response value of the mass-type detector depends on the mass of the gas entering the detector in unit time, i.e. the mass flow is linearly related to the concentration, and the mass flow can be converted into volume flow, so the volume flow is linearly related to the gas concentration. Therefore, when the flow rate controller cannot reach the target flow rate due to an uncorrectable slight deviation of the pressure at the gas inlet end or a small change in the atmospheric pressure of the on-site environment, the measured output gas concentration of the pressure type gas flow controller changes.
Disclosure of Invention
In view of this, the present disclosure provides a concentration compensation method for a gas flow control device, which can effectively solve the problem in the prior art that the measured output gas concentration of the gas flow control device changes due to slight deviation of the pressure at the gas inlet end which cannot be corrected or small change of the atmospheric pressure of the field environment.
The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the disclosure. It should be understood that this summary is not an exhaustive overview of the disclosure. It is not intended to identify key or critical elements of the disclosure or to delineate the scope of the disclosure. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
According to a first aspect of the present disclosure, there is provided a concentration compensation method of a gas flow control apparatus, the gas flow control apparatus including a gas inlet, a flow regulating unit, a differential pressure sensor, a flow restrictor, and a gas outlet, the gas inlet being connected to an input of the flow regulating unit, an output of the flow regulating unit being connected to an input of the flow restrictor, an output of the flow restrictor being connected to the gas outlet, the differential pressure sensor being disposed between the flow regulating unit and the flow restrictor for detecting a pressure difference between the output of the flow regulating unit and the input of the flow restrictor, the concentration compensation method including:
the method comprises the following steps: acquiring theoretical differential pressure of the differential pressure sensor and an initial opening value of the flow regulating unit according to target flow;
step two: controlling the flow regulating unit based on the initial opening value, and acquiring the actual differential pressure of the differential pressure sensor;
step three: judging whether the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is greater than 0 and less than or equal to a threshold, if the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is greater than the threshold, calculating the actual opening value of the flow regulating unit based on the actual pressure difference, correcting the initial opening value according to the actual opening value, and returning to the second step; if the absolute value of the difference between the actual differential pressure and the theoretical differential pressure is greater than 0 and less than or equal to the threshold, if so, comparing the actual differential pressure with the theoretical differential pressure, if the actual differential pressure is greater than the theoretical differential pressure, compensating the actually measured concentration of the gas output by the gas flow control device by adopting a first compensation coefficient, and if the actual differential pressure is less than the theoretical differential pressure, compensating the actually measured concentration of the gas output by the gas flow control device by adopting a second compensation coefficient.
In some embodiments, obtaining a theoretical differential pressure of the differential pressure sensor from a target flow rate based on the following equation comprises:
PS 1 ＝Q*R-ΔPc
wherein, PS 1 And in the theoretical pressure difference of the differential pressure sensor, the delta Pc is the critical pressure difference at two ends of the flow restrictor, Q is the target flow rate, and R is the resistance of the flow restrictor.
In some embodiments, where the flow regulating unit is an adjustable speed pump, the initial opening value of the adjustable speed pump is obtained from the target flow based on the following formula:
D 1 ＝m*Q
wherein D is 1 The value is the initial opening value of the speed-adjustable pump, m is the opening parameter of the speed-adjustable pump, and Q is the target flow.
In some embodiments, the measured concentration of the gas output from the gas flow control device is compensated using a first compensation factor based on the following equation:
C′＝(1-k 1 *ΔPS)*C，
ΔPS＝PS 2 -PS 1
wherein C' is the compensated concentration of the output gas, k 1 Is a first concentration compensation factor, C is the measured concentration of the output gas, PS 2 For said actual pressure difference, PS 1 Δ PS is a positive number for the theoretical pressure difference.
In some embodiments, the first concentration compensation factor is
Where R is the resistance of the flow restrictor.
In some embodiments, the measured concentration of the gas output from the gas flow control device is compensated using a second compensation factor based on the following equation:
C′＝(1-k 2 *ΔPS)*C，
ΔPS＝PS 2 -PS 1 ；
wherein C' is the compensated concentration of the output gas, k 2 Is a second concentration compensation factor, C is the measured concentration of the output gas, PS 2 For said actual pressure difference, PS 1 Δ PS is a negative number for the theoretical pressure difference.
In some embodiments, the second concentration compensation factor is
Where R is the resistance of the flow restrictor.
In some embodiments, the threshold absolute value of the difference between the actual pressure differential and the theoretical pressure differential is 2.
According to the concentration compensation method of the gas flow control device, the actual pressure difference of the pressure difference sensor is obtained, the gas concentration measured at the output end is compensated based on the difference value of the actual pressure difference and the theoretical pressure difference, and the problem that the measured output gas concentration of the gas flow control device is changed when the gas flow control device cannot reach the target flow due to slight deviation which cannot be corrected or small change of the atmospheric pressure of the field environment caused by the pressure at the gas inlet end is effectively solved.
Drawings
The objects and advantages of the present disclosure will be understood by the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic structural diagram of a gas flow control device according to an embodiment of the present disclosure;
FIG. 2 is a flow chart illustrating a method for compensating concentration of a gas flow control device according to an embodiment of the present disclosure;
fig. 3 is a graph of the difference between the actual differential pressure and the theoretical differential pressure and the compensated gas concentration according to the embodiment of the disclosure.
Detailed Description
The technical solutions of the present disclosure will be described more clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only some, but not all embodiments of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.
In the description of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing and simplifying the present disclosure, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present disclosure. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present disclosure, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present disclosure can be understood in specific instances by those of ordinary skill in the art.
In addition, technical features involved in different embodiments of the present disclosure described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1, the present disclosure provides a gas flow control apparatus, including a gas inlet, a flow regulating unit, a differential pressure sensor, a flow restrictor, and a gas outlet, where the gas inlet is connected to an input of the flow regulating unit, an output of the flow regulating unit is connected to an input of the flow restrictor, an output of the flow restrictor is connected to the gas outlet, and the differential pressure sensor is disposed between the flow regulating unit and the flow restrictor and is used for detecting a pressure difference between the output of the flow regulating unit and the input of the flow restrictor. Wherein, the opening of the flow regulating unit can be regulated; the aperture of the flow restrictor is a fixed value, and the opening degree cannot be adjusted.
As shown in fig. 2, an embodiment of the present disclosure provides a concentration compensation method 200 applied to the gas flow rate control device, where the concentration compensation method specifically includes:
step 210: and acquiring the theoretical differential pressure of the differential pressure sensor and the initial opening value of the flow regulating unit according to the target flow.
In the embodiment of the present disclosure, the target flow is an output flow of the gas flow control device, and assuming that the target flow is Q, in an environment of constant temperature heating control, according to a poisson equation, a calculation method of the target flow Q is as follows:
Q＝(P 0 -P 2 )/R＝(P 0 -(P 1 -ΔPc))/R＝((P 0 -P 1 )+ΔPc)/R＝(PS 1 +ΔPc)/R
wherein, P 0 Is the pressure at the output of the flow regulating unit, P 2 Is the pressure at the output end of the current limiter, i.e. the pressure at the outlet end, P 1 Is the pressure at the input end of the flow restrictor, Δ Pc is the critical pressure difference across the flow restrictor, R is the resistance of the flow restrictor, PS 1 Is the theoretical pressure difference.
It should be noted that, in the above calculation formula provided in the embodiment of the present disclosure, the critical pressure difference Δ Pc between two ends of the current limiter is the pressure P at the input end of the current limiter 1 And pressure P at the output of the current limiter 2 The difference, i.e. Δ Pc ═ P 1 -P 2 (ii) a Theoretical differential pressure PS 1 For the pressure P at the output of the flow regulating unit 0 And the pressure P at the input of the current limiter 1 The difference, i.e. PS 1 ＝P 0 -P 1 。
In the embodiment of the disclosure, the theoretical differential pressure PS of the preset differential pressure sensor can be obtained by back-stepping through the calculation formula of the target flow 1 Q R- Δ Pc, wherein PS 1 The theoretical differential pressure of the differential pressure sensor, Δ Pc is the critical differential pressure across the flow restrictor, R is the resistance of the flow restrictor, and Q is the target flow.
In the embodiment of the present disclosure, the target flow rate may be set according to actual requirements, the resistance of the flow restrictor is a fixed value, and the critical pressure difference across the flow restrictor is a constant. Therefore, the theoretical differential pressure of the differential pressure sensor can be calculated after the set target flow is obtained based on the calculation formula of the theoretical differential pressure.
In the embodiment of the present disclosure, the flow rate adjusting unit may be an adjustable speed pump, and other devices capable of adjusting and controlling the flow rate are also within the scope of the present disclosure, and are not specifically limited herein.
In the embodiment of the present disclosure, in a case that the flow rate adjusting unit is a variable speed pump, the opening value of the flow rate adjusting unit may be obtained according to the target flow rate based on the following formula:
D 1 ＝m*Q
wherein D is 1 The opening value of the flow regulating unit, m is the opening parameter of the speed-adjustable pump, and Q is the target flow.
Step 220: and controlling the flow regulating unit based on the initial opening value, and acquiring the actual differential pressure of the differential pressure sensor.
In the embodiment of the present disclosure, after the initial opening value of the flow rate adjusting unit is obtained, the single chip microcomputer or the data processing unit is used to correspondingly control the flow rate adjusting unit, so that the actual differential pressure of the differential pressure sensor is obtained after the flow rate adjusting unit operates according to the initial opening value.
In the embodiment of the present disclosure, the actual differential pressure of the differential pressure sensor may be obtained every 8 seconds, but the embodiment of the present disclosure does not limit this period, and a person skilled in the art may set the period value according to actual requirements.
Step 230: judging whether the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is greater than 0 and less than or equal to a threshold, if the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is greater than the threshold, calculating the actual opening value of the flow regulating unit based on the actual pressure difference, correcting the initial opening value according to the actual opening value, and returning to the step 220; and if the absolute value of the difference between the actual differential pressure and the theoretical differential pressure is greater than 0 and less than or equal to the threshold value, comparing the actual differential pressure with the theoretical differential pressure, if the actual differential pressure is greater than the theoretical differential pressure, compensating the actually measured concentration of the gas output by the gas flow control device by adopting a first compensation coefficient, and if the actual differential pressure is less than the theoretical differential pressure, compensating the actually measured concentration of the gas output by the gas flow control device by adopting a second compensation coefficient.
In the embodiment of the present disclosure, when the absolute value of the difference between the actual differential pressure and the theoretical differential pressure is greater than the threshold, it is indicated that the actual differential pressure is not yet adjusted within a threshold range near the theoretical differential pressure, and at this time, the influence of the pressure change at the gas inlet end on the flow rate is great, and further the influence on the gas concentration is great, and the concentration compensation method provided by the present disclosure cannot be used to compensate the output gas concentration, but the actual opening value of the flow rate adjustment unit should be calculated according to the actual differential pressure, for example, when the flow rate adjustment unit is an adjustable speed pump, the actual opening value of the flow rate adjustment unit may be calculated according to the actual differential pressure based on the following formula:
e＝PS 1 -PS 2
wherein D is 2 Is the actual opening value of the flow regulating unit, D 1 For initial opening value of adjustable speed pump, PS 1 Is the theoretical differential pressure of a differential pressure sensor, PS 2 Is the actual differential pressure of the differential pressure sensor, K P To scale factor, K i To integrate the adjustment coefficient, t is the integration time.
And the single chip microcomputer feeds the actual opening value of the flow regulating unit back to the flow regulating unit, corrects the initial opening value of the flow regulating unit according to the actual opening value and returns to the step 220. In this embodiment, the initial opening value of the flow rate adjustment unit is corrected according to the actual opening value, specifically, the actual opening value is assigned to the initial opening value.
Based on the initial opening value after assignment, namely the actual opening value, the flow regulating unit is controlled to obtain new actual pressure difference, and the actual pressure difference and the theoretical pressure difference are judged to be large againAnd when the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is smaller than or equal to the threshold value, the flow regulating unit is controlled in a continuous circulation mode. In the above operation, based on the obtained actual pressure difference, the amount of intake air of the gas flow control device is changed by adjusting the opening value of the flow rate adjustment unit, thereby achieving a stable output end pressure P of the flow rate adjustment unit 0 And further stabilize the flow rate in a range.
In the embodiment of the present disclosure, under the condition that the absolute value of the difference between the actual differential pressure and the theoretical differential pressure is greater than 0 and less than or equal to a threshold, it is described that the actual differential pressure is adjusted within a threshold range near the theoretical differential pressure, and the influence of the pressure change at the gas inlet end on the flow rate is corrected by adjusting the opening degree of the flow rate adjusting unit, at this time, the deviation between the actual differential pressure and the theoretical differential pressure is mainly caused by a slight deviation that cannot be corrected occurring in the pressure at the gas inlet end or a small change in the atmospheric pressure of the field environment, and since the flow rate and the concentration are in a proportional relationship, the concentration compensation method provided subsequently by the present disclosure may be adopted to compensate the concentration of the output gas.
In the embodiment of the present disclosure, the threshold of the absolute value of the difference between the actual differential pressure and the theoretical differential pressure may be 2, but is not limited to this value, and a person skilled in the art may set the threshold of the absolute value of the difference between the actual differential pressure and the theoretical differential pressure according to actual situations.
In the embodiment of the present disclosure, when the absolute value of the difference between the actual differential pressure and the theoretical differential pressure is greater than 0 and less than or equal to a threshold, the actual differential pressure and the theoretical differential pressure are further compared.
When the actual differential pressure is greater than the theoretical differential pressure, a first compensation coefficient is used to compensate the measured concentration of the gas output by the gas flow control device, which may specifically be based on the following formula and using the first compensation coefficient to compensate the measured concentration of the gas output by the gas flow control device:
C′＝(1-k 1 *ΔPS)*C，
ΔPS＝PS 2 -PS 1
wherein C' is the compensated concentration of the output gas, k 1 Is a first concentration compensation factor, C is the measured concentration of the output gas, PS 2 For said actual pressure difference, PS 1 Δ PS is a positive number for the theoretical pressure difference. In the embodiment of the disclosure, when the actual differential pressure is greater than the theoretical differential pressure, it is described that the flow rate is increased, Δ PS is a positive number, and the concentration C' after compensation is smaller than the concentration C before compensation, so as to correct the problem of the concentration being too large due to the increased flow rate.
And under the condition that the actual pressure difference is smaller than the theoretical pressure difference, compensating the measured concentration of the gas output by the gas flow control device by using a second compensation coefficient, which may be specifically based on the following formula and by using a second compensation coefficient:
C′＝(1-k 2 *ΔPS)*C，
ΔPS＝PS 2 -PS 1 ；
wherein C' is the compensated concentration of the output gas, k 2 Is a second concentration compensation factor, C is the measured concentration of the output gas, PS 2 For said actual pressure difference, PS 1 Δ PS is a negative number for the theoretical pressure difference. In the embodiment of the disclosure, when the actual differential pressure is smaller than the theoretical differential pressure, it is indicated that the flow rate becomes smaller, Δ PS is a negative number, and subtracting a negative number equals adding a positive number, and at this time, the concentration C' after compensation is greater than the concentration C before compensation, so that the problem of concentration being smaller due to the smaller flow rate is corrected.
In the embodiment of the disclosure, the first concentration compensation coefficient may be
The second concentration compensation factor may be
Where R is the resistance of the flow restrictor. The calculation method of the first concentration compensation coefficient and the second concentration compensation coefficient comprises the following steps:
due to the pressure difference between the input and output of the current limiter, inAs the gas flows through the flow restrictor, its flow rate increases as the pressure differential increases. However, when the pressure difference exceeds the critical pressure difference, the flow rate of the gas passing through the restriction of the flow restrictor reaches the sonic velocity, and in this case, no matter how the pressure difference increases, as long as the pressure upstream of the flow restrictor remains constant, the flow rate through the flow restrictor will be maintained at a constant value and will not increase any more. The flow-limiting restrictor is used for limiting the flow rate and reducing the pressure of the fluid according to the principle. Where Δ Pc is a critical pressure difference between the input end and the output end of the current limiter, and Δ Pc ═ P 1 -P 2 ，P 1 Is the input pressure of the flow restrictor, P 2 The output end P is the pressure of the output end of the current limiter because the output end is in the atmospheric environment 2 Is at ambient atmospheric pressure.
In the first situation, the service life of the flow regulating unit is reduced due to overlong service time, and the actual opening is larger than the theoretical opening control command issued by the singlechip to cause P 1 Is slightly higher or when the ambient atmospheric pressure P 2 When it becomes smaller, P 1 -P 2 When the value of (A) exceeds the critical pressure difference DeltaPc, the flow velocity of the gas passing through the restriction of the flow restrictor reaches the sonic velocity, no matter P 1 At how much further, the flow rate will not increase, so Δ Pc is constant.
Based on the following formula
Target flow rate: q ═ PS 1 +ΔPc)/R，
Actual flow rate: q' ═ of (PS) 2 +ΔPc)/R，
Flow rate variation amount:
since Δ Pc is the critical pressure difference across the current limiter, which is a constant, PS 1 Is a fixed value for theoretical differential pressure, R is the resistance of the flow restrictor, is a constant, and only the actual differential pressure PS 2 When the pressure difference increases, the flow rate increases, and the change of the flow rate and the actual pressure difference PS are affected 2 Is the same, therefore, the variable PS is taken in the embodiment of the present disclosure 2 Is a first compensation coefficient
And due to the linear proportional relation between the flow rate and the concentration, the first compensation coefficient can be applied to the concentration compensation.
In the second case, P is caused by a half-block failure of the inlet or flow regulating unit 0 Or P 1 Slightly lower, or ambient, atmospheric pressure P 2 When the pressure difference between the front end and the rear end of the flow restrictor is larger, the pressure difference between the front end and the rear end of the flow restrictor is equal to P 1 -P 2 Will be below the critical pressure differential Δ Pc. Critical differential pressure Δ Pc ═ N × P 1 ＝N*(P 0 -PS 1 ) Wherein when the gas is saturated steam, N is 0.58; when the gas is superheated steam or polyatomic gas, N is 0.55; when the gas is air or a diatomic gas, N is 0.53. The pressure difference between the front end and the rear end of the flow restrictor is not equal to the critical pressure difference any more, but is Δ Pc ═ 0.5 × PS 2 . Target flow based on the following formula: q ═ s (PS) 1 +ΔPc)/R，
Actual flow rate: q' ═ of (PS) 2 +ΔPc′)/R，
ΔQ＝(PS 2 -PS 1 +0.5PS 2 -N*(P 0 -PS 1 ))/R
＝(1.5*PS 2 -PS 1 )/R-(N*(P 0 -PS 1 ))/R
Due to P 0 The pressure at the output end of the flow regulating unit is stabilized to a fixed value, PS, after the opening degree of the flow regulating unit is regulated 1 Is a theoretical pressure difference, and is a constant, PS 2 For actual pressure difference, R is the resistance of the flow restrictor and is a constant, therefore, the embodiment of the present disclosure takes the variable PS 2 Is the second compensation coefficient
And due to the linear proportional relation between the flow rate and the concentration, the second compensation coefficient can be applied to the concentration compensation.
Fig. 3 shows a relationship diagram between a difference between an actual pressure difference and a theoretical pressure difference and a compensated gas concentration when an actual measured concentration of an output gas is 100ppm, and it can be seen from the diagram that when the actual pressure difference is smaller than the theoretical pressure difference, the pressure difference becomes smaller to cause a flow rate to become smaller, and further the actual measured concentration is lower than the actual concentration of the gas, and at this time, the compensated gas concentration obtained by applying the concentration compensation method provided by the present disclosure is greater than the actual measured concentration by 100ppm, so that the smaller actual measured concentration is corrected; under the condition that the actual pressure difference is larger than the theoretical pressure difference, the pressure difference is increased to cause the flow to be increased, and further cause the actual concentration of the gas to be larger than the actual concentration of the gas, and at the moment, the compensated gas concentration obtained by applying the concentration compensation method provided by the disclosure is smaller than the actual concentration of the gas by 100ppm, so that the larger actual concentration is corrected.
According to the technical scheme, the output gas concentration error caused when the flow control device cannot reach the target flow is corrected through the concentration compensation control method, the technical problem that the concentration is changed due to slight change of the control flow caused by slight deviation of uncorrectable pressure at the air inlet end or small change of atmospheric pressure of the field environment is effectively solved, and therefore the environmental adaptability and the control precision of the flow control device are improved.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of this disclosure may be made without departing from the scope of the disclosure.
Claims (8)
1. A concentration compensation method of a gas flow control apparatus including a gas inlet, a flow rate adjustment unit, a differential pressure sensor, a flow restrictor, and a gas outlet, the gas inlet being connected to an input of the flow rate adjustment unit, an output of the flow rate adjustment unit being connected to an input of the flow restrictor, an output of the flow restrictor being connected to the gas outlet, the differential pressure sensor being disposed between the flow rate adjustment unit and the flow restrictor for detecting a pressure difference between the output of the flow rate adjustment unit and the input of the flow restrictor, the concentration compensation method comprising:
the method comprises the following steps: acquiring theoretical differential pressure of the differential pressure sensor and an initial opening value of the flow regulating unit according to target flow;
step two: controlling the flow regulating unit based on the initial opening value, and acquiring the actual differential pressure of the differential pressure sensor;
step three: judging whether the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is greater than 0 and less than or equal to a threshold, if the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is greater than the threshold, calculating the actual opening value of the flow regulating unit based on the actual pressure difference, correcting the initial opening value according to the actual opening value, and returning to the second step; and if the absolute value of the difference between the actual differential pressure and the theoretical differential pressure is greater than 0 and less than or equal to the threshold value, comparing the actual differential pressure with the theoretical differential pressure, if the actual differential pressure is greater than the theoretical differential pressure, compensating the actually measured concentration of the gas output by the gas flow control device by adopting a first compensation coefficient, and if the actual differential pressure is less than the theoretical differential pressure, compensating the actually measured concentration of the gas output by the gas flow control device by adopting a second compensation coefficient.
2. The concentration compensation method of a gas flow rate control device according to claim 1, wherein a theoretical differential pressure of the differential pressure sensor is obtained from a target flow rate based on the following formula:
PS 1 ＝Q*R-ΔPc
wherein, PS 1 The theoretical differential pressure of the differential pressure sensor, Δ Pc is the critical differential pressure across the flow restrictor, Q is the target flow, and R is the resistance of the flow restrictor.
3. The concentration compensation method of a gas flow control device according to claim 1, wherein in the case where the flow rate adjustment unit is an adjustable speed pump, an initial opening value of the adjustable speed pump is obtained from a target flow rate based on the following formula:
D 1 ＝m*Q
wherein D is 1 The initial opening value of the speed-adjustable pump, m is the opening parameter of the speed-adjustable pump, and Q is the target flow.
4. The method of claim 1, wherein the measured concentration of the output gas of the gas flow control device is compensated using a first compensation factor based on the following equation:
C′＝(1-k 1 *ΔPS)*C，
ΔPS＝PS 2 -PS 1
wherein C' is the compensated concentration of the output gas, k 1 Is a first concentration compensation factor, C is the measured concentration of the output gas, PS 2 For said actual pressure difference, PS 1 Δ PS is a positive number for the theoretical pressure difference.
5. A method of compensating for the concentration of a gas flow rate as in claim 1 or 4, wherein the first concentration compensation factor is
Where R is the resistance of the flow restrictor.
6. The method of claim 1, wherein the measured concentration of the gas output from the gas flow control device is compensated using a second compensation factor based on the following equation:
C′＝(1-k 2 *ΔPS)*C，
ΔPS＝PS 2 -PS 1 ；
wherein C' is the compensated concentration of the output gas, k 2 Is a second concentration compensation factor, C is the measured concentration of the output gas, PS 2 For said actual pressure difference, PS 1 Δ PS is a negative number for the theoretical pressure difference.
7. A gas according to claim 1 or 6The concentration compensation method of the fluid flow control device is characterized in that the second concentration compensation coefficient is
Where R is the resistance of the flow restrictor.
8. The concentration compensation method of a gas flow rate control device according to claim 1, wherein the threshold value of the absolute value of the difference between the actual pressure difference and the theoretical pressure difference is 2.
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| CN116929469A (en) * | 2023-09-18 | 2023-10-24 | 四川蜀谷仪表科技有限公司 | Differential pressure flowmeter high-low pressure conversion method and differential pressure flowmeter flow measuring method |
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| CN116929469A (en) * | 2023-09-18 | 2023-10-24 | 四川蜀谷仪表科技有限公司 | Differential pressure flowmeter high-low pressure conversion method and differential pressure flowmeter flow measuring method |
| CN116929469B (en) * | 2023-09-18 | 2024-01-30 | 四川蜀谷仪表科技有限公司 | Differential pressure flowmeter high-low pressure conversion method and differential pressure flowmeter flow measuring method |
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