CN115047918A - Micro-flow gas mass flow controller and control method - Google Patents
Micro-flow gas mass flow controller and control method Download PDFInfo
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- CN115047918A CN115047918A CN202210616603.9A CN202210616603A CN115047918A CN 115047918 A CN115047918 A CN 115047918A CN 202210616603 A CN202210616603 A CN 202210616603A CN 115047918 A CN115047918 A CN 115047918A
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- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
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- G05D7/06—Control of flow characterised by the use of electric means
- G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
- G05D7/0629—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the type of regulator means
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Abstract
The invention belongs to the technical field of gas flow control, and relates to a micro-flow gas mass flow controller.A micropore flow limiting plate is fixedly arranged at the middle position of a controller pipe body, a flow limiting hole is arranged at the central position of the micropore flow limiting plate, two outer sides of the micropore flow limiting plate are respectively and fixedly connected with a gas circuit channel, a differential pressure sensor is fixedly arranged on the inner wall of the gas circuit channel at two sides of the micropore flow limiting plate, a pressure sensor is fixedly arranged on the inner wall of the gas circuit channel close to an upstream gas inlet, a temperature sensor is fixedly arranged on the inner wall of the gas circuit channel close to a downstream gas outlet, and an electronic pressure controller is respectively and fixedly arranged at the gas inlet end and the gas outlet end of the gas circuit channel; also comprises a central control unit. The invention also relates to a micro-flow gas mass flow controller method. The invention realizes the accurate control of the mass flow of the micro-flow gas through the mutual matching of the micropore flow limiting plate, the pressure sensor, the differential pressure sensor, the temperature sensor and the electronic pressure controller.
Description
Technical Field
The invention belongs to the technical field of gas flow control, and particularly relates to a micro-flow gas mass flow controller and a control method.
Background
The gas mass flow controller is an instrument for measuring and controlling the mass flow of gas in a pipeline, and is widely applied to the fields of environment, chemical industry, medicine, national defense and the like.
Conventional gas mass flow controllers include thermal mass flow controllers, coriolis mass flow controllers, laminar mass flow controllers, and the like, which are typically applied to flow specifications (in N @) 2 Measured) 100- 2 Meter) 1-100SCCM, the above devices often have problems of large error, poor linearity, drift, etc.
In many application scenarios, such as flow calibration platform, chemical process experiment, mechanical dynamic test system, vacuum test system, semiconductor process gas control, etc., it is usually necessary to measure the micro flow (in terms of N) 2 Meter, flow range 1-100SCCM) gas, and the aforementioned devices are not able to meet the requirements of the above application scenarios.
In order to realize the mass flow control of micro-flow gas, CN10691910B in the prior art discloses a micro-flow gas mass flow controller, in which a valve core and a valve sleeve are matched by a hole shaft, and throttle control is realized by a circular seam, so that the regulation range is wide, and the flow output of the controller under specific pressure can be accurately regulated.
Based on the above analysis, how to improve the control precision of the mass flow of the micro-flow gas, improve the automation degree of the equipment, and simplify the equipment structure is a technical problem to be solved in the field.
Disclosure of Invention
The present invention is directed to a mass flow controller for micro flow gas and a control method thereof. The technical scheme adopted by the invention is as follows:
a micro-flow gas mass flow controller comprises a controller pipe body and a central control unit, wherein a micropore flow limiting plate is fixedly arranged at the middle position of the controller pipe body, a flow limiting hole is formed in the central position of the micropore flow limiting plate, gas path channels are fixedly connected to the two outer sides of the micropore flow limiting plate respectively, the peripheries of the micropore flow limiting plate and the gas path channels are attached to the inner wall of the controller pipe body, differential pressure sensors are fixedly arranged on the inner walls of the gas path channels at the two sides of the micropore flow limiting plate, a pressure sensor is fixedly arranged on the inner wall of the gas path channel close to an upstream gas inlet, a temperature sensor is fixedly arranged on the inner wall of the gas path channel close to a downstream gas outlet, and electronic pressure controllers are fixedly arranged at the gas inlet end and the gas outlet end of the gas path channel respectively; the central control unit is electrically connected with the differential pressure sensor, the electronic pressure controller and the temperature sensor respectively, and is used for realizing the system control of the micro-flow gas mass flow controller.
A micro flow gas mass flow controller method is applied to the micro flow gas mass flow controller and comprises the following steps:
step 1, a central control unit collects various real-time data of a differential pressure sensor, a pressure sensor and a temperature sensor;
and 5, adjusting and controlling the upstream and downstream electronic pressure controllers by the central control unit to achieve the calculated pressure difference value delta P.
The invention has the beneficial effects that:
the micro-flow gas mass flow controller realizes the accurate control of the micro-flow gas mass flow through the mutual matching of the micro-hole flow limiting plate, the pressure sensor, the differential pressure sensor, the temperature sensor and the electronic pressure controller, has a simple structure and high automation degree, and has wide application prospect.
Drawings
FIG. 1 is a schematic structural view of a micro flow gas mass flow controller according to the present invention;
FIG. 2 is a schematic diagram of the central control unit 10 according to the present invention;
in the figure, 1 is a controller tube, 2 is an air passage, 3 is a micropore restrictor, 4 is a gasket, 5 is a fastening ring, 6 is a differential pressure sensor, 7 is a pressure sensor, 8 is an electronic pressure controller, 9 is a temperature sensor, and 10 is a central control unit.
Detailed Description
The technical scheme of the invention is described below by combining the drawings in the specification. Fig. 1 shows a micro flow gas mass flow controller according to the present invention, as shown in fig. 1, the micro flow gas mass flow controller includes a controller tube 1, a micro-hole restrictor plate 3 is fixedly disposed at a middle position of the controller tube 1, a small-diameter restrictor hole is disposed at a center position of the micro-hole restrictor plate 3, a diameter of the restrictor hole is significantly smaller than a diameter of a gas path channel 2, and the restrictor hole is used for controlling a gas flow; gaskets 4 are fixedly arranged on two sides of the microporous flow limiting plate 3 respectively, the gaskets 4 are used for fixing the microporous flow limiting plate 3, a gasket through hole is formed in the center of each gasket 4, and the diameter of the gasket through hole of each gasket 4 is larger than that of a flow limiting hole of the microporous flow limiting plate 3; fastening rings 5 are fixedly arranged on two outer sides of the gasket 4, the fastening rings 5 are used for fastening and connecting the microporous restrictor plate 3 and the gasket 4 to the inner wall of the controller pipe body 1, tapered holes are symmetrically formed in the center positions of the two fastening rings 5, one small-diameter ends of the tapered holes are close to the gasket 4, the minimum diameter of the tapered holes of the fastening rings 5 is equal to the diameter of gasket through holes of the gasket 4, the diameter of a large passage of the gas pipeline 2 is reduced to be slightly larger than that of the microporous restrictor plate 3 through the tapered holes of the fastening rings 5, and the peripheries of the microporous restrictor plate 3, the gasket 4 and the fastening rings 5 are attached to the inner wall of the controller pipe body 1; two outer sides of the fastening ring 5 are respectively and fixedly connected with an air channel 2, the end part of an air outlet and the end part of an air inlet of the air channel 2 extend out of the controller tube body 1, and the periphery of the air channel 2 is attached to the inner wall of the controller tube body 1; a differential pressure sensor 6 is fixedly arranged on the inner wall of the gas path channel 2 at two sides of the fastening ring 5, and the differential pressure sensor 6 is used for measuring the pressure difference between the upstream and the downstream of the micropore flow limiting plate 3; a pressure sensor 7 is fixedly arranged on the inner wall of the gas path channel 2 close to the upstream air inlet, and the pressure sensor 7 is used for measuring the pressure of gas entering the gas path channel 2; a temperature sensor 9 is fixedly arranged on the inner wall of the gas path channel 2 close to the downstream gas outlet, and the temperature sensor 9 is used for measuring the temperature of the gas in the gas path channel 2; an electronic pressure controller 8 is fixedly arranged at the air inlet end and the air outlet end of the air channel 2 respectively, and the electronic pressure controller 8 is used for adjusting the gas pressure at the upstream and the downstream of the micropore flow-limiting plate 3 according to the target gas mass flow; the micro flow gas mass flow controller also comprises a central control unit 10, wherein the central control unit 10 is respectively electrically connected with the differential pressure sensor 6, the pressure sensor 7, the electronic pressure controller 8 and the temperature sensor 9, and the central control unit 10 is used for realizing the system control of the micro flow gas mass flow controller.
The controller pipe body 1 is of a double-layer structure formed by an inner layer and an outer layer and made of corrosion-resistant stainless steel materials, and the double-layer structure facilitates installation and fixation of all parts inside the controller pipe body 1. The periphery of micropore current-limiting plate 3 and gasket 4 and the outer inner wall laminating of controller body 1, the periphery of gas pipeline 2 and gasket 4 and the inlayer inner wall laminating of controller body 1 to the inlayer inner wall diameter of controller body 1 of gasket 4 department is greater than the inlayer inner wall diameter of controller body 1 of gas pipeline 2 department. Fastening bolts are arranged at the two sections of gas pipelines 2 in a threaded manner, and the end parts of the fastening bolts penetrate through the double-layer structure of the controller pipe body 1 and abut against the gas pipelines 2, so that the fastening effect is enhanced; the periphery of tighrening ring 5 is equipped with the external screw thread, and the inner wall of corresponding controller body 1 is equipped with corresponding internal thread, is convenient for install and fixed.
The diameter of the air path channel 2 is D, and the air path channel is used for air circulation.
The micropore restriction plate 3 is a round thin plate processed by a precious metal material, and further, the micropore restriction plate 3 is processed by a pure gold material, and the precious metal material or the pure gold material has stable physical and chemical properties, so that the long-term stable operation of the device is ensured. The micropore restriction plate 3 is provided with a restriction hole with the diameter d, and the gas flow is controlled through the restriction hole.
The gasket 4 is a circular sheet processed by a low-activity metal material, and the low-activity metal material has good compatibility with a precious metal material used by the micropore flow-limiting plate 3; the low activity metallic material may be silver (Ag), platinum (Pt), gold (Au), rhenium (Re), ruthenium (Ru), tantalum (Ta), rhodium (Rh), or the like; a gasket through hole is formed in the gasket 4, and the diameter of the gasket through hole is slightly larger than that of the flow limiting hole; the fastening ring 5 arranged on the outer side of the gasket 4 is made of high-strength corrosion-resistant materials.
The differential pressure sensor 6 is of a type commonly used in the art for measuring the pressure difference ap upstream and downstream of the microporous restrictor plate 3. The probe of the differential pressure sensor 6 is fixedly arranged on the controller pipe body 1 and the gas pipeline 2 through a probe mounting position on the controller pipe body 1 and a mounting hole on the inner wall of the gas pipeline 2, and the probe extends into the gas pipeline 2 to measure the pressure difference of gas.
The pressure sensor 7 is a pressure sensor of a type commonly used in the art, and is used for measuring the pressure of the gas entering the gas path channel 2. The probe of the pressure sensor 7 is fixedly arranged on the controller pipe body 1 and the gas pipeline 2 through a probe mounting position on the controller pipe body 1 and a mounting hole on the inner wall of the gas pipeline 2, and the probe extends into the gas pipeline 2 to measure the pressure of gas.
The electronic pressure controller 8 is of a type commonly used in the art for regulating the pressure upstream and downstream of the microporous restrictor plate 3.
The temperature sensor 9 is a temperature sensor of a general type in the prior art, and is configured to measure a temperature of the gas inside the gas pipeline 2 in an actual state, so as to calculate a gas density ρ in the gas path channel in the actual state by combining with the pressure data. The probe of the temperature sensor 9 is fixedly arranged on the controller pipe body 1 and the gas pipeline 2 through a probe mounting position on the controller pipe body 1 and a mounting hole on the inner wall of the gas pipeline 2, and the probe extends into the gas pipeline 2 to measure the temperature of the gas.
As shown in fig. 2, the central control unit 10 includes: the device comprises an input module, a data acquisition module, a storage module, a calculation module and a control module; the data acquisition module is used for acquiring various real-time data of the differential pressure sensor 6, the pressure sensor 7 and the temperature sensor 9 and storing the acquired data in the storage module; the calculation module has an operation processing function, the storage module transmits the acquired data to the calculation module for calculating the gas mass flow, and the required pressure difference is inversely calculated according to a target gas mass flow value input by a user; the control module sends out a control signal to control the electronic pressure controller 8 based on the information fed back by the calculation module, and the pressure difference between the upstream and the downstream of the micropore flow limiting plate 3 is adjusted to a target value.
A method for controlling the mass flow of micro-flow gas is realized by applying the micro-flow gas mass flow controller, and comprises the following steps:
step 1, a central control unit 10 collects various real-time data of a differential pressure sensor 6, a pressure sensor 7 and a temperature sensor 9;
the meaning of the parameters is as follows:
ρ: gas density in the gas path channel in an actual state;
ρ 0 : density at gas standard condition, being a fixed constant;
p: the pressure of the gas in the actual state is measured by the pressure sensor 7;
P 0 : pressure at standard conditions of gas, being a fixed constant;
t: the temperature of the gas in the actual state is measured by a temperature sensor 9;
T 0 : the temperature under standard gas conditions is a fixed constant.
And 3, inputting a target gas mass flow Q by a user through the central control unit 10, wherein the target gas mass flow Q is a target value which the user wants to finally obtain through the micro-flow gas mass flow controller.
And 4, the central control unit 10 calculates to obtain a pressure difference Δ P between the upstream and downstream sides of the microporous throttling plate 3, where Δ P is a value to which a target value of the gas mass flow Q previously input by the user and the pressure difference between the upstream and downstream sides of the microporous throttling plate 3 should be obtained. During operation, a user inputs a target gas mass flow rate Q through an input module of the central control unit 10.Δ P is calculated inversely by the following equation:
the meaning of the parameters is as follows:
q: a gas mass flow rate;
d: the diameter of the flow limiting hole is obtained through measurement;
d: the diameter of the gas path channel 2 is obtained by measurement;
Δ P: calculating the pressure difference between the upstream and the downstream of the micropore flow limiting plate 3;
c: an efflux coefficient;
epsilon: the coefficient of thermal expansion of the gas is obtained by looking up a table according to Matheson gas data handbook;
ρ: calculating the gas density in the gas path channel 2 in an actual state;
the gas outflow coefficient C is measured through a gas flow test device, the gas flow test device establishes a functional relation between the measured actual flow and the ideal flow, the slope of the functional relation is the outflow coefficient C, and the outflow coefficient C is input into the central control unit 10 of the micro-flow gas mass flow controller; the gas flow test device is a common test device in the field, preferably adopts an LQH-100 type piston gas flow test device, and a manufacturer is Hangzhou Tianma measurement science and technology company Limited.
And 5, the central control unit 10 adjusts and controls the upstream and downstream electronic pressure controllers 8 according to the calculated pressure difference delta P between the upstream and downstream of the microporous throttling plate 3 so as to achieve the calculated pressure difference delta P.
The central control unit 10 will calculate the pressure difference ap upstream and downstream of the micro-porous restrictor plate 3 in reverse based on the above formula, because this value is a difference value, and needs to adjust the actual pressure of the electronic pressure controllers 8 controlling the upstream and downstream according to the readings of the differential pressure sensor 6 and the pressure sensor 7.
For example, a gas mass flow Q is input, and Δ P is obtained by calculating the formula in reverse, where the pressure reading P of the pressure sensor 7 is 1 Is the upstream actual pressure, the central control unit 10 will issue a control command to adjust the downstream electronic pressure controller 8 until the differential pressure sensor 6 reads Δ P, at which time the downstream actual pressure P 2 ＝P 1 + Δ P. When P appears 2 Under the limitation of precision, specification and the like, the pressure difference sensor 6 is difficult to adjust to the special condition that the reading is delta P, and P can also be adjusted by the electronic pressure controller 8 which sends out a control command and adjusts the upstream by the central control unit 10 1 。
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. Micro flow gas mass flow controller, including controller body (1) and central control unit (10), its characterized in that: a micropore flow-limiting plate (3) is fixedly arranged in the middle of a controller pipe body (1), a flow-limiting hole is formed in the center of the micropore flow-limiting plate (3), gas channel channels (2) are fixedly connected to two outer sides of the micropore flow-limiting plate (3) respectively, the peripheries of the micropore flow-limiting plate (3) and the gas channel channels (2) are attached to the inner wall of the controller pipe body (1), a pressure difference sensor (6) is fixedly arranged on the inner wall of the gas channel (2) on two sides of the micropore flow-limiting plate (3), a pressure sensor (7) is fixedly arranged on the inner wall of the gas channel (2) close to an upstream air inlet, a temperature sensor (9) is fixedly arranged on the inner wall of the gas channel (2) close to a downstream air outlet, and electronic pressure controllers (8) are fixedly arranged at the air inlet end and the air outlet end of the gas channel (2) respectively; the central control unit (10) is electrically connected with the differential pressure sensor (6), the pressure sensor (7), the electronic pressure controller (8) and the temperature sensor (9) respectively, and the central control unit (10) is used for realizing the system control of the micro-flow gas mass flow controller.
2. A micro flow gas mass flow controller as claimed in claim 1, wherein: the central control unit (10) comprises: the device comprises an input module, a data acquisition module, a storage module, a calculation module and a control module; the data acquisition module is used for acquiring various real-time data of the differential pressure sensor (6), the pressure sensor (7) and the temperature sensor (9) and storing the acquired data in the storage module; the calculation module has an operation processing function, the storage module transmits the acquired data to the calculation module for calculating the gas mass flow, and the required pressure difference is inversely calculated according to a target gas mass flow value input by a user; the control module sends out a control signal to control the electronic pressure controller (8) based on the information fed back by the calculation module, and the pressure difference between the upstream and the downstream of the micropore flow limiting plate (3) is adjusted to a target value.
3. A micro flow gas mass flow controller as claimed in claim 1, wherein: gaskets (4) are fixedly arranged on two sides of the micropore throttling plate (3) respectively, a gasket through hole is formed in the center of each gasket (4), and the diameter of each gasket through hole is larger than that of each throttling hole; the controller is characterized in that fastening rings (5) are fixedly arranged on two outer sides of the gasket (4), tapered holes are symmetrically formed in the center positions of the two fastening rings (5), one small-diameter end of each tapered hole is close to the gasket (4), and the peripheries of the gasket (4) and the fastening rings (5) are attached to the inner wall of the controller pipe body (1).
4. A micro flow gas mass flow controller as claimed in claim 2, wherein: the controller pipe body (1) is of a double-layer structure consisting of an inner layer and an outer layer and is made of corrosion-resistant stainless steel materials.
5. A micro flow gas mass flow controller as claimed in claim 4, wherein: the periphery of tighrening ring (5) is equipped with the external screw thread, and the inner wall of corresponding controller body (1) is equipped with corresponding internal thread.
6. A micro flow gas mass flow controller as claimed in claim 5, wherein: the micropore flow limiting plate (3) is a round sheet processed from a noble metal material, the gasket (4) is a round sheet processed from a low-activity metal material, and the fastening ring (5) is prepared from a high-strength corrosion-resistant material.
7. A micro flow gas mass flow controller as claimed in claim 1, wherein: probes of the differential pressure sensor (6), the pressure sensor (7) and the temperature sensor (9) are fixedly installed on the controller pipe body (1) and the gas pipeline (2) through probe installation positions on the controller pipe body (1) and installation holes in the inner wall of the gas pipeline (2), and the probes stretch into the gas pipeline (2).
8. The method for controlling the mass flow of the micro-flow gas is characterized by comprising the following steps: use of a micro flow gas mass flow controller according to claim 1, comprising the steps of:
step 1, a central control unit (10) collects various real-time data of a differential pressure sensor (6), a pressure sensor (7) and a temperature sensor (9);
step 2, the central control unit (10) calculates and obtains the gas density rho in the gas channel (2) in the actual state;
step 3, inputting a target gas mass flow Q by a user through a central control unit (10);
step 4, the central control unit (10) calculates to obtain the pressure difference delta P between the upstream and the downstream of the microporous flow restriction plate (3);
and 5, adjusting and controlling the upstream and downstream electronic pressure controllers (8) by the central control unit (10) to achieve the calculated pressure difference delta P.
9. A method of controlling a micro flow gas mass flow as in claim 8, wherein: the gas density rho in the gas path channel (2) in the actual state is based on the gas temperature measured by the temperature sensor (9), and is obtained by calculation by combining pressure data, and the calculation formula is as follows:
the meaning of the parameters is as follows:
ρ: gas density in the gas path channel in an actual state;
ρ 0 : density at gas standard condition, being a fixed constant;
p: the pressure of the gas in the actual state is measured by a pressure sensor (7);
P 0 : pressure at standard conditions of gas, being a fixed constant;
t: the temperature of the gas in the actual state is measured by a temperature sensor (9);
T 0 : gas standard conditionIs a fixed constant.
10. A method of controlling a mass flow of a micro flow gas as set forth in claim 8, wherein: Δ P is calculated inversely by the following equation:
the meaning of the parameters is as follows:
q: a gas mass flow rate;
d: the diameter of the flow limiting hole is obtained through measurement;
d: the diameter of the gas path channel (2) is obtained by measurement;
Δ P: the pressure difference between the upstream and the downstream of the micropore flow limiting plate (3) is obtained by calculation;
c: an efflux coefficient;
epsilon: the coefficient of thermal expansion of the gas is obtained by looking up a table in Matheson gas data handbook;
ρ: calculating the gas density in the gas path channel (2) in an actual state;
the gas outflow coefficient C was experimentally measured by a gas flow rate test apparatus.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117148877A (en) * | 2023-11-01 | 2023-12-01 | 苏芯物联技术(南京)有限公司 | High-precision pipeline flow measurement control device and design method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117148877A (en) * | 2023-11-01 | 2023-12-01 | 苏芯物联技术(南京)有限公司 | High-precision pipeline flow measurement control device and design method |
| CN117148877B (en) * | 2023-11-01 | 2024-01-02 | 苏芯物联技术(南京)有限公司 | High-precision pipeline flow measurement control device and design method |
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