CN110686758A - Sound velocity nozzle gas flow standard device capable of switching pressure sources and control method thereof - Google Patents
Sound velocity nozzle gas flow standard device capable of switching pressure sources and control method thereof Download PDFInfo
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- CN110686758A CN110686758A CN201910918657.9A CN201910918657A CN110686758A CN 110686758 A CN110686758 A CN 110686758A CN 201910918657 A CN201910918657 A CN 201910918657A CN 110686758 A CN110686758 A CN 110686758A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
- G01F25/10—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters
- G01F25/15—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters specially adapted for gas meters
Abstract
The invention belongs to the technical field of gas flow, and relates to a sound velocity nozzle gas flow standard device capable of switching pressure sources and a control method thereof. The problem of require high, the flowmeter of a plurality of pressure test points to pressure and conventional wide range flowmeter can not carry out the calibration on a set of equipment is solved. The device comprises a mechanical pipeline part and an electric control unit; the mechanical pipeline part comprises a sonic nozzle group, n paths of negative pressure method verification pipelines, one path of positive pressure method verification pipeline, a negative pressure method power source and a positive pressure method power source which are arranged in parallel. The sonic nozzle gas flow standard device adopts a negative pressure method in a default state, can realize the flow meters with large measuring range and large caliber, simultaneously can switch the same device into a positive pressure method for output through a corresponding computer control method in an electric control unit, is convenient, quick and accurate to switch, can realize the verification of the flow meters with higher pressure requirements and a plurality of pressure points, and has high verification precision and wide range.
Description
Technical Field
The invention belongs to the technical field of gas flow, and relates to a sound velocity nozzle gas flow standard device capable of switching a pressure source into positive pressure or negative pressure and a calibration method thereof.
Background
The gas flow device is a main device for realizing verification and calibration of the gas flowmeter, and the gas flow device adopting the sonic nozzle as the standard meter has the advantages that: the gas flowmeter has the advantages of simple structure, stable performance, good repeatability, high precision, convenient maintenance and the like, and is widely used for detecting and calibrating various gas flowmeters at present.
The existing sonic nozzle gas flow device can be divided into a negative pressure method and a positive pressure method according to the difference of pressure sources, the negative pressure method takes atmospheric pressure as stagnation pressure, a vacuum pump as a power source, the pressure of a gas source is stable, the system is simple, the technology is relatively mature, the manufacturing cost and the operating cost are low, the upstream stagnation pressure and the temperature of a sonic nozzle are relatively stable, the critical flow function changes little under normal temperature and normal pressure, and the negative pressure method is adopted as the pressure source of the sonic nozzle gas flow device in most of the existing equipment. However, the negative pressure method also has the problems that the air source pressure is fixed and can not be adjusted, the pressure loss is large, and the realized flow range is small. And the conventional flowmeter with large measuring range and large caliber can only be detected by the negative pressure method at present.
Compared with the negative pressure method, the positive pressure method has high requirement on the stability of the air source, and in order to realize higher flow stability, the positive pressure method needs a complex pressure stabilizing and regulating temperature control system, and the system is complex. But the positive pressure method can realize good flow stability, and the air compressor is used as a pressure source to adjust the upstream pressure of the detected meter at any time, thereby reducing pressure loss, and realizing the verification of the flow meter with higher pressure requirement and a plurality of pressure points, which can not be realized by the negative pressure method. However, the normal pressure method cannot be used for calibrating the conventional large-range and large-caliber flow meter.
At present, each metering mechanism is basically a negative pressure sonic nozzle gas flow standard device, a flowmeter with high precision and high pressure requirements cannot be verified and calibrated, and the flowmeter can only be sent to other units with the positive pressure sonic nozzle gas flow standard devices, so that the verification and calibration process is complex and the cost is high.
Disclosure of Invention
The invention provides a sound velocity nozzle gas flow standard device capable of switching a pressure source and a control method thereof, aiming at solving the problems that the pressure requirement is high, and a flowmeter with a plurality of pressure test points and a conventional wide-range flowmeter cannot be calibrated on one set of equipment.
The technical scheme adopted by the invention is to provide a sound velocity nozzle gas flow standard device capable of switching pressure sources, which is characterized in that: comprises a mechanical pipeline part and an electric control unit;
the mechanical pipeline part comprises a sonic nozzle group, n paths of negative pressure method verification pipelines, one path of positive pressure method verification pipeline, a negative pressure method power source and a positive pressure method power source which are arranged in parallel; wherein n is a positive integer greater than or equal to 1;
the sonic nozzle group comprises a plurality of groups of sonic nozzles with different throat diameters which are connected in parallel, and also comprises a high-pressure switch valve VH-01 and a high-pressure switch valve VH-02, wherein the high-pressure switch valve VH-01 and the high-pressure switch valve VH-02 are respectively arranged at the inlet end and the outlet end of two groups of sonic nozzles which are connected in parallel, and the sonic nozzle group is divided into a first section of sonic nozzle group and a second section of sonic nozzle group;
defining n paths of negative pressure method verification pipelines into two types, wherein n-1 paths of negative pressure method verification pipelines are defined as a first type of negative pressure method verification pipelines, and the rest paths of negative pressure method verification pipelines are defined as a second type of negative pressure method verification pipelines;
the first type of negative pressure method verification pipeline comprises a pipe orifice silencer a, a pressure transmitter a, a temperature transmitter a and a switch valve VB-01, wherein the pipe orifice silencer a, the pressure transmitter a, the temperature transmitter a and the switch valve VB-01 are arranged on the negative pressure method pipeline; the pressure transmitter a and the temperature transmitter a are used for installing a detected flowmeter; the switch valve VB-01 is connected with one end of the first section of sonic nozzle group, and the other end of the first section of sonic nozzle group is connected to a negative pressure method power source through a pipeline; the negative pressure method power source comprises a high-pressure switch valve VH-04, a vacuum buffer tank, a pump switch valve and a vacuum pump which are connected in sequence;
the second type of negative pressure method verification pipeline comprises a pipe orifice silencer b, a switch valve VB-03, a pressure transmitter b, a temperature transmitter b and a switch valve VB-04, wherein the pipe orifice silencer b, the switch valve VB-03, the pressure transmitter b, the temperature transmitter b and the switch valve VB-04 are arranged on the negative pressure method pipeline; the pressure transmitter b and the temperature transmitter b are used for installing a detected flowmeter; the switch valve VB-04 is connected with one end of the second section of sonic nozzle group and is simultaneously connected with the high-pressure switch valve VH-01;
the positive pressure method verification pipeline comprises a pressure transmitter c, a pressure regulating valve VB-05, a high-pressure switch valve VH-03 and a pipeline silencer c; the positive pressure method power source comprises an air storage tank and a compressor which are connected in sequence; one end of the pressure transmitter c is connected between the switch valve VB-03 and the pressure transmitter b, and the other end of the pressure transmitter c is connected with the gas holder through the pressure regulating valve VB-05; the high-pressure switch valve VH-03 is connected with the pipeline silencer c and then connected to the other end of the second section of sonic nozzle group, and the high-pressure switch valve VH-03 and the high-pressure switch valve VH-02 are connected simultaneously;
the electric control unit comprises an industrial personal computer, an analog signal acquisition board card, an input/output board card and an IO module, wherein the analog signal acquisition board card, the input/output board card and the IO module are respectively communicated with the industrial personal computer; the analog signal acquisition board card is used for acquiring pressure and temperature information of the detected flowmeter, frequency and pulse output signals of the detected flowmeter and outputting the signals to the industrial personal computer; the input and output board card is used for starting and stopping the vacuum pump and the compressor and transmitting a working state signal of an air source to the industrial personal computer through the PCI bus; the IO module is used for controlling the corresponding valve according to the selected sonic nozzle and transmitting the opening and closing state of the valve back to the industrial personal computer; the industrial personal computer is used for controlling the analog signal acquisition board card, the input/output board card and the IO module and processing the received data to realize calibration.
Further, in order to realize calibration of flowmeters with different calibers, the calibers of the to-be-detected flowmeters which can be installed in the pipeline are different through n-path negative pressure method verification.
Further, in order to accurately adjust the pressure and temperature by the positive pressure method, the opening degree of the pressure-adjusting valve VB-05 is calculated according to the following formula:
wherein q ismFor measuring the flow of sonic nozzle, V is the volume flow and P is the pressureT is temperature and R is gas constant.
The invention also provides a calibration method of the sound velocity nozzle gas flow standard device by utilizing the switchable pressure source, which comprises the following steps:
step one, selecting a working mode, if the working mode is a negative pressure method, executing a process a, and if the working mode is a positive pressure method, executing a process b;
a. firstly, an industrial personal computer sends a control command to an IO module, a pressure regulating valve VB-05 and a high-voltage switch valve VH-03 are closed through the IO module, the switch valve VB-03, the high-voltage switch valve VH-01 and the high-voltage switch valve VH-02 are opened, and the corresponding switch valve in a pipeline where a detected flowmeter is installed is opened;
then, the industrial personal computer sends a control instruction to the input and output board card, and the vacuum pump is started through the input and output board card; the analog signal acquisition board card acquires pressure and temperature information of the detected flowmeter, and frequency and pulse output signals of the detected flowmeter, and uploads the acquired signals to the industrial personal computer through the PCI bus, so that verification and calibration of the flowmeter are realized;
b. firstly, an industrial personal computer sends a control command to an IO module, a switching valve VB-03, a high-voltage switching valve VH-01 and a high-voltage switching valve VH-02 are closed through the IO module, and a pressure regulating valve VB-05 and the high-voltage switching valve VH-03 are opened; then, the industrial personal computer sends a control instruction to the input and output board card, the air compressor is started through the input and output board card, and the air compressor compresses air and sends high-pressure air into the high-pressure air storage tank; the analog signal acquisition board card feeds back the acquired upstream and downstream pressure temperature values to the industrial personal computer, and the following formula is utilized to calculate the opening degree of the pressure regulating valve VB-05
Wherein q ismFor the measured sonic nozzle flow, V is the volumetric flow, P is the pressure, T is the temperature, and R is the gas constant;
controlling the opening degree of the pressure regulating valve VB-05 through an IO module according to the opening degree value; and then, an analog signal acquisition board card is used for acquiring pressure and temperature signals, frequency and pulse output signals of the upstream and downstream of the detected flowmeter, so that the flowmeter is detected.
The invention has the beneficial effects that:
1. the sonic nozzle gas flow standard device adopts a negative pressure method in a default state, can realize the verification and calibration of a flowmeter with a large range and a large caliber, such as a DN300 caliber gas flowmeter, and has high precision; meanwhile, the sound velocity nozzle gas flow standard device can be switched to be output by a positive pressure method through a corresponding computer control method, the device is convenient to switch, fast and accurate, the flow meters with high pressure requirements and multiple pressure points can be calibrated, the calibration precision is high, and the range is wide;
2. the invention innovatively utilizes the positive pressure regulating valve and the control method to be combined to realize the accurate work of the positive pressure method temperature and pressure system, and improves the reliability and the accuracy of the positive pressure method sonic nozzle gas flow device.
Drawings
FIG. 1 is an overall block diagram of the present invention;
FIG. 2 is an overall block diagram of an embodiment of the invention;
FIG. 3 is a schematic diagram of the electrical control portion of an embodiment of the present invention;
FIG. 4 is a flow chart of a pressure regulation fitting method of the positive pressure method according to an embodiment of the invention;
FIG. 5 is a flow chart of a control method of an embodiment of the invention;
wherein the reference numerals are: 01-pipe orifice silencer a, 02-pressure transmitter a, 04-temperature transmitter a, 05-switch valve;
1-pipeline I pipe orifice silencer, 2-pipeline I pressure transmitter, 3-pipeline I detected flowmeter, 4-pipeline I temperature transmitter, 5-pipeline I switch valve VB-01, 6-sonic nozzle group, 7-high pressure switch valve VH-04, 8-vacuum buffer tank, 9-pump switch valve and 10-vacuum pump;
11-pipeline II orifice silencer, 12-pipeline II pressure transmitter, 13-pipeline II detected flowmeter, 14-pipeline II temperature transmitter and 15-pipeline II switching valve VB-02;
16-pipe orifice silencer b, 17-switching valves VB-03, 18-pressure transmitters b, 19-pipeline III detected flow meter, 20-temperature transmitters b, 21-switching valves VB-04, 22-high-pressure switching valves VH-01, 23-high-pressure switching valves VH-02;
24-pressure transmitter c, 25-pressure regulating valve VB-05, 26-gas holder, 27-compressor, 28-high pressure switch valve VH-03, 29-pipeline silencer c;
30-analog signal acquisition board card, 31-industrial personal computer, 32-input/output board card and 33-IO module.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
The invention provides a sound velocity nozzle gas flow standard device capable of switching a pressure source into positive pressure or negative pressure.
The mechanical pipeline comprises a plurality of paths of negative pressure method verification pipelines and positive pressure method verification pipelines which are arranged in parallel, and is shown in figure 1. The system comprises a sonic nozzle group 6, n paths of negative pressure method verification pipelines, one path of positive pressure method verification pipeline, a negative pressure method power source and a positive pressure method power source which are arranged in parallel; wherein n is a positive integer greater than or equal to 1; the sonic nozzle group 6 comprises a plurality of groups of sonic nozzles with different throat diameters in parallel connection, and also comprises a high-pressure switch valve VH-0122 and a high-pressure switch valve VH-0223, wherein the high-pressure switch valve VH-0122 and the high-pressure switch valve VH-0223 are respectively arranged at the inlet ends and the outlet ends of two groups of sonic nozzles in parallel connection, and the sonic nozzle group is divided into a first section of sonic nozzle group 61 and a second section of sonic nozzle group 62; defining n paths of negative pressure method verification pipelines into two types, wherein n-1 paths of negative pressure method verification pipelines are defined as a first type of negative pressure method verification pipelines, and the rest paths of negative pressure method verification pipelines are defined as a second type of negative pressure method verification pipelines; the first type of negative pressure method verification pipeline comprises a pipe orifice silencer a01, a pressure transmitter a02, a temperature transmitter a04 and a switch valve VB-0105, wherein the pipe orifice silencer a01, the pressure transmitter a02, the temperature transmitter a04 and the switch valve VB-0105 are arranged on the negative pressure method pipeline; the pressure transmitter a02 and the temperature transmitter a04 are used for installing the detected flowmeter; the switch valve VB-0105 is connected with one end of the first section of sonic nozzle group 61, and the other end of the first section of sonic nozzle group 61 is connected to a negative pressure method power source through a pipeline; the negative pressure method power source comprises a high-pressure switch valve VH-047, a vacuum buffer tank 8, a pump switch valve 9 and a vacuum pump 10 which are connected in sequence; the second type of negative pressure method verification pipeline comprises a pipe orifice silencer b16, a switch valve VB-0317, a pressure transmitter b18, a temperature transmitter b20 and a switch valve VB-0421, wherein the pipe orifice silencer b16, the switch valve VB-0317, the pressure transmitter b18 and the temperature transmitter b20 are arranged on the negative pressure method pipeline; a tested flowmeter is arranged between the pressure transmitter b18 and the temperature transmitter b 20; the switch valve VB-0421 is connected with one end of the second section of sonic nozzle group 62 and is simultaneously connected with the high-pressure switch valve VH-0122; the positive pressure method power source comprises an air storage tank 26 and a compressor 27 which are connected in sequence; one end of the pressure transmitter c24 is connected between the switch valve VB-0317 and the pressure transmitter b18, and the other end of the pressure transmitter c24 is connected with the air storage tank 26 through the pressure regulating valve VB-0525; the high pressure switching valve VH-0328 is connected to the pipeline silencer c29 and then connected to the other end of the second sonic nozzle set 62, and the high pressure switching valve VH-0328 and the high pressure switching valve VH-0223 are also connected.
The electric control unit comprises an industrial personal computer 31, an analog signal acquisition board card 30, an input/output board card 32 and an IO module 33, wherein the analog signal acquisition board card 30, the input/output board card and the IO module are respectively communicated with the industrial personal computer 31; the analog signal acquisition board card 30 is used for acquiring pressure and temperature information of the detected flowmeter, frequency of the detected flowmeter and pulse output signals and outputting the signals to the industrial personal computer 31; the input/output board card 32 is used for turning on/off the vacuum pump 10 and the compressor 27, and transmitting a working state signal of an air source to the industrial personal computer 31 through the PCI bus; the IO module 33 is used for controlling the corresponding valve according to the selected sonic nozzle and transmitting the opening and closing state of the valve back to the industrial personal computer 31; the industrial personal computer 31 is used for controlling the analog signal acquisition board card 30, the input/output board card 32 and the IO module 33 and processing the received data to realize calibration.
When the physical examination is carried out, the following processes can be carried out:
step one, selecting a working mode, if the working mode is a negative pressure method, executing a process a, and if the working mode is a positive pressure method, executing a process b;
a. firstly, an industrial personal computer sends a control command to an IO module, a pressure regulating valve VB-05 and a high-voltage switch valve VH-03 are closed through the IO module, the switch valve VB-03, the high-voltage switch valve VH-01 and the high-voltage switch valve VH-02 are opened, and the corresponding switch valve in a pipeline where a detected flowmeter is installed is opened;
then, the industrial personal computer sends a control instruction to the input and output board card, and the vacuum pump is started through the input and output board card; the analog signal acquisition board card acquires pressure and temperature information of the detected flowmeter, and frequency and pulse output signals of the detected flowmeter, and uploads the acquired signals to the industrial personal computer through the PCI bus, so that verification and calibration of the flowmeter are realized;
b. firstly, an industrial personal computer sends a control command to an IO module, a switching valve VB-03, a high-voltage switching valve VH-01 and a high-voltage switching valve VH-02 are closed through the IO module, and a pressure regulating valve VB-05 and the high-voltage switching valve VH-03 are opened; then, the industrial personal computer sends a control instruction to the input and output board card, the air compressor is started through the input and output board card, and the air compressor compresses air and sends high-pressure air into the high-pressure air storage tank; the analog signal acquisition board card feeds back the acquired upstream and downstream pressure temperature values to the industrial personal computer, and the following formula is utilized to calculate the opening degree of the pressure regulating valve VB-05
Wherein q ismFor the measured sonic nozzle flow, V is the volumetric flow, P is the pressure, T is the temperature, and R is the gas constant; controlling the opening degree of the pressure regulating valve VB-05 through an IO module according to the opening degree value; and then, an analog signal acquisition board card is used for acquiring pressure and temperature signals, frequency and pulse output signals of the upstream and downstream of the detected flowmeter, so that the flowmeter is detected.
Examples
In this embodiment, a three-way negative pressure method verification pipeline and a one-way positive pressure method verification pipeline are taken as examples for explanation:
as can be seen from fig. 2, the mechanical pipeline portion of the present embodiment includes a first negative pressure method verification pipeline, a second negative pressure method verification pipeline, a third negative pressure method verification pipeline, a positive pressure method verification pipeline, and a sonic nozzle set 6. The sonic nozzle group 6 comprises a plurality of groups of sonic nozzles which are connected in parallel and have different throat diameters, and further comprises a high-pressure switch valve VH-0122 and a high-pressure switch valve VH-0223 which are respectively arranged between the inlet ends and the outlet ends of the two parallel sonic nozzles, and the sonic nozzle group 6 is divided into two parts, namely a first section of sonic nozzle group 61 and a second section of sonic nozzle group 62, through the high-pressure switch valve VH-0122 and the high-pressure switch valve VH-0223. The first negative pressure method verification pipeline, the second negative pressure method verification pipeline and the third negative pressure method verification pipeline share one negative pressure method power source.
The first way negative pressure method verification pipeline comprises a pipeline I pipe orifice silencer 1, a pipeline I pressure transmitter 2, a pipeline I detected flowmeter 3, a pipeline I temperature transmitter 4 and a pipeline I switch valve 5 which are sequentially connected through a pipeline I, the pipeline I switch valve 5 is connected with a first section of sonic nozzle group 61, the first section of sonic nozzle group 61 is connected to a negative pressure method power source through a pipeline, and the negative pressure method power source comprises a high-pressure switch valve VH-047, a vacuum buffer tank 8, a pump switch valve 9 and a power source water ring vacuum pump 10 which are sequentially connected.
The second negative pressure method is used for detecting that a silencer 11 at the pipe orifice of a pipeline II in the pipeline is connected with a pressure transmitter 12 of the pipeline II, the pressure transmitter 12 of the pipeline II is connected with a detected flowmeter 13 of the pipeline II, the other end of the detected flowmeter of the pipeline II is connected with a temperature transmitter 14 of the pipeline II, the detected flowmeter of the pipeline II is connected with a first section of sonic nozzle group 61 through a switch valve 15 of the pipeline 11, the first section of sonic nozzle group 61 is connected to a high-pressure switch valve VH-047 through a pipeline, the high-pressure switch valve VH-047 and a vacuum buffer tank 8 are sequentially connected and then lead to a pump switch valve 9, and the pump switch valve 9 is connected with.
The third negative pressure method is used for detecting the pipe orifice silencer b16 in the pipeline and is firstly connected with one end of a switch valve VB-0317, the other end of the switch valve VB-0317 is connected with a pressure transmitter b18, the pressure transmitter b18 and the pipeline III are detected by a flow meter 19, a temperature transmitter b20 and a switch valve VB-0421 are sequentially connected, the other end of the switch valve VB-0421 is connected with part of nozzles of the second section of sonic nozzle group 62 and is simultaneously connected with a high-pressure switch valve VH-0122, and the high-pressure switch valve VH-0122 and the high-pressure switch valve VH-0223 are connected with two parts of the sonic nozzle group 6. Meanwhile, the high-pressure switching valve VH-0223 is connected with the high-pressure switching valve VH-0328 and the line muffler c29 in sequence. Meanwhile, the switch valve VB-0317 is connected with a pressure transmitter c24, the other end of the pressure transmitter c24 is connected with a pressure regulating valve VB-0525, the opening of the pipeline of the air storage tank 26 is controlled by the pressure regulating valve VB-0525, and the other end of the air storage tank 26 is connected with the compressor 27 through the pipeline.
As can be seen from fig. 3, the pipeline control portion of this embodiment includes an industrial personal computer 31, an analog signal acquisition board 30, an input/output board 32 and an IO module 33, which are respectively in communication with the industrial personal computer 31, the analog signal acquisition board 30 is connected to the industrial personal computer 31 through a PCI bus, the input/output board 32 is also connected to the industrial personal computer 31 through a PCI bus, and the IO module 33 is connected to the industrial personal computer 31 through a PCI bus.
The industrial personal computer 31 is used as a control core of the whole device to realize data transmission and processing, and the analog signal acquisition board acquires pressure and temperature information of the detected flowmeter and output signals such as frequency and pulse of the detected flowmeter and uploads the acquired signals to the industrial personal computer 31 through the PCI bus; the IO module 33 mainly controls the corresponding valve according to the selected sonic nozzle, returns the on-off state of the valve, and also completes the function of switching the air sources of the positive pressure method and the negative pressure method. The input/output board card 32 controls the on/off of the air sources of the positive pressure method and the negative pressure method, i.e., the water ring vacuum pump 10 and the compressor 27, and transmits the working state signals of the air sources to the industrial personal computer 31 via the PCI bus.
The working process of the invention is as follows:
referring to fig. 2, in a system initialization state, a default is that a sonic nozzle gas flow standard device works in a negative pressure method state, firstly, a to-be-detected flowmeter is installed on a corresponding pipeline according to the caliber of the to-be-detected flowmeter, three stations including a pipeline I to-be-detected flowmeter 3, a pipeline II to-be-detected flowmeter 13 and a pipeline III to-be-detected flowmeter 19 are arranged at installation positions, after the to-be-detected flowmeter is installed on the corresponding station, a vacuum pump 10 works, the to-be-detected flowmeter is output after a vacuum buffer tank 8 is stabilized, critical conditions are manufactured for a sonic nozzle group 6, sonic nozzles with different throat diameters of the sonic nozzle group 6 can be opened successively when various flow ranges of the flowmeter are to be detected, air enters a selected sonic nozzle after negative pressure is formed, and if the to-be-detected flowmeter is installed on a pipeline I, the air passes through a pipeline, And after the pressure transmitter 2 of the pipeline I is discharged through a silencer at the pipe orifice of the pipeline I, the working methods of the pipeline II and the pipeline III are consistent with those of the pipeline I.
When the gas flow standard device of the sonic nozzle needs to carry out positive pressure method detection, the high-pressure switch valve VH-047, the high-pressure switch valve VH-0122, the high-pressure switch valve VH-0223 and the switch valve VB-0317 are closed, the pressure regulating valve VB-0525 and the high-pressure switch valve VH-0328 are opened, the compressor 27 works, high-pressure compressed air generated by the work of the compressor 27 enters the gas storage tank 26 after being stabilized, the corresponding sonic nozzle is opened after the proper sonic nozzle is selected according to the type of a detected meter, the high-pressure air enters an experimental pipeline after being regulated by the pipeline IV pressure stabilizing valve, and is discharged by the pipeline silencer c29 after passing through the pressure transmitter c24, the pipeline III detected flow meter, the temperature transmitter b20 and the high-pressure switch valve VH-0328.
As shown in fig. 4, when the sonic nozzle gas flow rate calibration device works in the positive pressure method, since the pressure regulation in the positive pressure method is regulated by the pressure regulating valve VB-0525, the valve opening regulation process is directly related to the temperature and pressure variation process of the downstream pipeline and the stagnation container, and the opening variation is reflected on the valve flow rate variation, so that the calculation formula for obtaining the flow rate is important for the temperature and pressure stability prediction process. Firstly, the system is pressurized by using a screw compressor 27, the air pressure of the high-pressure air storage tank 26 is monitored in real time by using a pressure transmitter b18, and if the air pressure does not reach a preset maximum value, pressurization is continued; when the maximum value is reached, the pressure value of the device is adjusted to a certain constant value by using the pressure regulating valve VB-0525, the nozzle is opened to work, the pressure transmitter b18 and the temperature transmitter b20 collect the current pressure temperature value, after the collected value is stable, the opening degree of the pressure regulating valve VB-0525 is calculated by using the current value, and the calculation formula is as follows:
wherein q ismFor the measured sonic nozzle flow, V is the volumetric flow, P is the pressure, T is the temperature, and R is the gas constant. Therefore, a fitting equation of the valve opening is obtained, and a mathematical basis is realized for accurately adjusting the pressure and the temperature.
As shown in fig. 5, the industrial personal computer stores a computer program for controlling the operation of the analog signal acquisition board 30, the input/output board 32 and the IO module 33, and when the computer program runs in the processor, the following processes are implemented:
selecting a working mode, if the working mode is a negative pressure method, sending a control instruction to an IO module 33, closing a pressure regulating valve VB-0525 and a high-pressure switch valve VH-0328 through the IO module 33, opening a switch valve VB-0317, a high-pressure switch valve VH-0122 and a high-pressure switch valve VH-0223, selecting a corresponding pipeline according to the caliber size of the detected flowmeter, and opening one of a switch valve VB-015 of a pipeline I, a switch valve VB-0215 of a pipeline II and a switch valve VB-0421; sending a control instruction to the input and output board card 32, and starting the water ring vacuum pump 10 as an upstream pressure source through the input and output board card 32 to perform negative pressure treatment on the system; the analog signal acquisition board card 30 acquires pressure and temperature information of the flow meter to be detected and output signals such as frequency and pulse of the flow meter to be detected, and uploads the acquired signals to the industrial personal computer 31 through the PCI bus, so that verification and calibration of the flow meter are realized.
When the positive pressure method is selected, a control instruction is sent to the IO module 33, the switching valves VB-0317, the high-pressure switching valves VH-0122 and the high-pressure switching valves VH-0223 need to be closed through the IO module 33, and the pressure regulating valves VB-0525 and the high-pressure switching valves VH-0328 are opened; then, a control instruction is sent to the input/output board card 32, the screw air compressor 27 is started through the input/output board card 32, and after the air compressor compresses the air, the high-pressure air is sent to the high-pressure air storage tank 26; the analog signal acquisition board card 30 feeds back the acquired upstream and downstream pressure temperature values to the industrial personal computer, and the opening value of the valve is obtained after the currently measured temperature and pressure values are brought in by using the obtained opening equation of the pipeline IV pressure regulating valve; the opening degree of the pressure regulating valve VB-0525 is controlled through the IO module 33 according to the opening degree value, the system is precisely regulated, the precision of the positive-pressure method sonic nozzle gas flow device is guaranteed, and the upstream and downstream pressure temperature signals, the frequency and the pulse output signals of the detected flowmeter are collected through the analog signal collecting board card 30, so that the flowmeter is detected.
Claims (4)
1. A sound velocity nozzle gas flow standard device capable of switching pressure sources is characterized in that: comprises a mechanical pipeline part and an electric control unit;
the mechanical pipeline part comprises a sonic nozzle group (6), n paths of negative pressure method verification pipelines, one path of positive pressure method verification pipeline, a negative pressure method power source and a positive pressure method power source which are arranged in parallel; wherein n is a positive integer greater than or equal to 1;
the sonic nozzle group (6) comprises a plurality of groups of sonic nozzles with different throat diameters in parallel connection, and also comprises a high-pressure switch valve VH-01(22) and a high-pressure switch valve VH-02(23), wherein the high-pressure switch valve VH-01(22) and the high-pressure switch valve VH-02(23) are respectively arranged at the inlet end and the outlet end of two groups of sonic nozzles in parallel connection, and the sonic nozzle group is divided into a first section of sonic nozzle group (61) and a second section of sonic nozzle group (62);
defining n paths of negative pressure method verification pipelines into two types, wherein n-1 paths of negative pressure method verification pipelines are defined as a first type of negative pressure method verification pipelines, and the rest paths of negative pressure method verification pipelines are defined as a second type of negative pressure method verification pipelines;
the first type of negative pressure method verification pipeline comprises a pipe orifice silencer a (01), a pressure transmitter a (02), a temperature transmitter a (04) and a switch valve VB-01(05), wherein the pipe orifice silencer a (01), the pressure transmitter a (02), the temperature transmitter a (04) and the switch valve VB-01 are arranged on the negative pressure method pipeline; the pressure transmitter a (02) and the temperature transmitter a (04) are used for installing the detected flowmeter; the switch valve VB-01(05) is connected with one end of the first section of sonic nozzle group (61), and the other end of the first section of sonic nozzle group (61) is connected to a negative pressure method power source through a pipeline; the negative pressure method power source comprises a high-pressure switch valve VH-04(7), a vacuum buffer tank (8), a pump switch valve (9) and a vacuum pump (10) which are connected in sequence;
the second type of negative pressure method verification pipeline comprises a pipe orifice silencer b (16), a switch valve VB-03(17), a pressure transmitter b (18), a temperature transmitter b (20) and a switch valve VB-04(21), wherein the pipe orifice silencer b (16), the switch valve VB-03(17), the pressure transmitter b (18) and the switch valve VB-04 are arranged on the negative pressure method pipeline; the pressure transmitter b (18) and the temperature transmitter b (20) are used for installing the detected flowmeter; a switch valve VB-04(21) is connected with one end of the second section of the sonic nozzle group (62) and is also connected with a high-pressure switch valve VH-01 (22);
the positive pressure method verification pipeline comprises a pressure transmitter c (24), a pressure regulating valve VB-05(25), a high-pressure switch valve VH-03(28) and a pipeline silencer c (29); the positive pressure method power source comprises an air storage tank (26) and a compressor (27) which are connected in sequence; one end of the pressure transmitter c (24) is connected between the switch valve VB-03(17) and the pressure transmitter b (18), and the other end of the pressure transmitter c (24) is connected with the air storage tank (26) through the pressure regulating valve VB-05 (25); the high-pressure switch valve VH-03(28) is connected with the pipeline silencer c (29) and then connected to the other end of the second section of sonic nozzle group (62), and the high-pressure switch valve VH-03(28) and the high-pressure switch valve VH-02(23) are connected simultaneously;
the electric control unit comprises an industrial personal computer (31), an analog signal acquisition board card (30), an input/output board card (32) and an IO module (33), wherein the analog signal acquisition board card and the input/output board card are respectively communicated with the industrial personal computer (31); the analog signal acquisition board card (30) is used for acquiring pressure and temperature information of the detected flowmeter, frequency of the detected flowmeter and pulse output signals and outputting the signals to the industrial personal computer (31); the input and output board card (32) is used for starting and stopping the vacuum pump (10) and the compressor (27) and transmitting a working state signal of an air source to the industrial personal computer (31) through the PCI bus; the IO module (33) is used for controlling the corresponding valve according to the selected sonic nozzle and transmitting the opening and closing state of the valve back to the industrial personal computer (31); the industrial personal computer (31) is used for controlling the analog signal acquisition board card (30), the input/output board card (32) and the IO module (33) and processing received data to realize calibration.
2. The sonic nozzle gas flow calibration apparatus of claim 1, wherein: the n negative pressure methods are used for detecting that the calibers of the to-be-detected flow meters which can be installed in the pipelines are different.
3. The sonic nozzle gas flow calibration apparatus of claim 1, wherein: the opening degree of the pressure regulating valve VB-05(25) is calculated according to the following formula:
wherein q ismFor the measured sonic nozzle flow, V is the volumetric flow, P is the pressure, T is the temperature, and R is the gas constant.
4. A method of controlling the sonic nozzle gas flow calibration apparatus of claim 1, comprising the steps of:
step one, selecting a working mode, if the working mode is a negative pressure method, executing a process a, and if the working mode is a positive pressure method, executing a process b;
a. firstly, the industrial personal computer sends a control command to an IO module (33), the pressure regulating valve VB-05(25) and the high-pressure switch valve VH-03(28) are closed through the IO module (33), the switch valve VB-03(17), the high-pressure switch valve VH-01(22) and the high-pressure switch valve VH-02(23) are opened, and the corresponding switch valve (05) in the pipeline where the detected flowmeter is installed is opened;
then, the industrial personal computer sends a control instruction to the input and output board card (32), and the vacuum pump (10) is started through the input and output board card (32); the analog signal acquisition board card (30) acquires pressure and temperature information of the detected flowmeter and frequency and pulse output signals of the detected flowmeter, and uploads the acquired signals to the industrial personal computer (31) through the PCI bus to realize the verification and calibration of the flowmeter;
b. firstly, an industrial personal computer (31) sends a control command to an IO module (33), the switching valve VB-03(17), the high-voltage switching valve VH-01(22) and the high-voltage switching valve VH-02(23) are closed through the IO module (33), and the pressure regulating valve VB-05(25) and the high-voltage switching valve VH-03(28) are opened; then, the industrial personal computer (31) sends a control instruction to the input and output board card (32), the air compressor (27) is started through the input and output board card (32), and after the air compressor compresses air, the high-pressure air is sent to the high-pressure air storage tank (26); the analog signal acquisition board card (30) feeds back the acquired upstream and downstream pressure temperature values to the industrial personal computer (31), and the opening degree of the pressure regulating valve VB-05(25) is calculated by using the following formula
Wherein q ismFor the measured sonic nozzle flow, V is the volumetric flow, P is the pressure, T is the temperature, and R is the gas constant;
controlling the opening degree of the pressure regulating valve VB-05(25) through an IO module (33) according to the opening degree value; and then, an analog signal acquisition board card (30) is used for acquiring the upstream and downstream pressure and temperature signals, the frequency and the pulse output signals of the detected flowmeter, so that the flowmeter can be calibrated.
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