CN201628569U

CN201628569U - High-pressure back-blowing bell-type gas flow standard apparatus

Info

Publication number: CN201628569U
Application number: CN2010201227749U
Authority: CN
Inventors: 黄涛; 李旭; 李宏伟; 臧立新; 王振; 王福贵; 刘方; 韩聪; 张文美; 孙丽华; 庄涛; 陆科
Original assignee: Liaoning Institute of Metrology
Current assignee: Liaoning Institute of Metrology
Priority date: 2010-03-04
Filing date: 2010-03-04
Publication date: 2010-11-10
Anticipated expiration: 2020-03-04

Abstract

A high-pressure back-blowing bell-type gas flow standard apparatus belongs to the field of flow measurement, relates to a high-pressure gas flow standard apparatus capable of utilizing a positive pressure mode to complete determination of critical flow sonic nozzles, and is used for positive pressure determination for critical sonic nozzles with higher pressure loss. The gas flow standard apparatus comprises a bell type flow standard apparatus connected with a stagnation container, and a computer for acquiring data is connected with the bell type flow standard apparatus and the stagnation container which is provided with a pressure sensor, a temperature sensor and a humidity sensor. The flow standard apparatus is structurally characterized in that the stagnation container is connected with a standard gas intake device.

Description

High pressure backblowing bell-jar gas flow standard equipment

Technical field:

The utility model belongs to the flow metering field, relates to a kind of gases at high pressure flow standard set-up that can adopt the malleation mode to finish the calibrating of critical flow sonic nozzle.

Background technology:

Sonic nozzle is widely used in gas flow standard device as topmost a kind of gas flow standard device, also can directly apply to industrial flow measurement.

Real stream calibrating for sonic nozzle with Venturi nozzle and secondary device, is installed on the gas flow standard device on request, surveys out the gas mass flow that flows through Venturi nozzle, goes out efflux coefficient by the computing formula inverse.In the calibrating engineering, when Venturi nozzle reached critical flow, under the condition that upstream parameters remains unchanged, its flow was not subjected to the influence of disturbances.So, inlet at volumetric standard is loaded onto Venturi nozzle, can Control Flow remain unchanged, and its condition is an elevated pressure in the volumetric standard, do not destroy the critical flow condition of Venturi nozzle, promptly do not allow the back pressure ratio greater than the maximum of critical flow venturi nozzle with the upstream pressure ratio.

The at present negative pressure PVTt method gas flow standard devices that adopt of China, its structure as shown in Figure 1 more.The principle of work of negative pressure PVTt method gas flow standard device is: before the calibrating, start vacuum pump, open vacuum valve, extract the air in the volumetric standard out, close vacuum valve and vacuum pump then.Temperature, pressure in the measurement standard container.Open switch valve, begin calibrating.When switch valve began to move, the photoelectricity signalling generator sent signal, started the timer timing.When switch valve was opened, because atmospheric pressure is higher than the pressure in the volumetric standard, ambient air began to flow into from the import of device, through tested flowmeter, critical flow venturi nozzle, switch valve, enter volumetric standard.When examining and determine appropriate time, the off switch valve makes air stop to flow.When switch valve arrived full close position, the photoelectricity signalling generator sent signal, stops the timer timing.Readout time from the timer.After treating the interior temperature stabilization of volumetric standard, measure its temperature, pressure, calculate its gross flow thus, and then can get the efflux coefficient of delivery nozzle.Because in the verification process, its gaseous state is a negative pressure, can not simulate the duty of sonic nozzle when using under positive pressure, so there is certain limitation in application of negative pressure PVTt subtraction unit.

At present, degassing method bell jar gas flow meter is comparatively commonly used, this method is relatively more classical, the verification result data are credible, the uncertainty of bell-jar gas flow meter is generally 0.1%～0.5%, and pressure is in 1000Pa～5000Pa scope, and pressure surge is at 10Pa～50Pa, because its value directly is traceable to length, pressure, temperature and time, is original method gas flow meter.Characteristics such as the bell-jar gas flow meter has pressure stability, stability of flow, good reproducibility, be easy to trace to the source, easy to operate can realize the calibration to the low pressure loss flowmeter, therefore in the world all with the national benchmark of bell jar as low-pressure gas low discharge device.

Because xsect is relevant in distance that standard volume only descends with bell jar and the bell jar, Correlative Influence Factors is less, so the uncertainty of standard volume is very little.On principle, factors such as repeatability that bell jar repeatability is only measured with bell jar movement velocity, optoelectronic switch and variation of ambient temperature are relevant, and these influence factors are all very little, so its good reproducibility.Because bell jar is a closed container that is suspended in above the liquid, downward the making a concerted effort that the effect by buoyancy compensation mechanism makes bell jar be subjected to is a constant power.Therefore, the pressure of gas remains at a stable status in the bell jar.This plays crucial effects to reducing the measurement result uncertainty.Because flow value is the product of cross-sectional area in bell jar travelling speed and the bell jar, press in the bell jar and stablize, therefore can flow be reached and be stabilized in and set on the flow point.But for the bigger flowmeter of the pressure loss, as: sonic nozzles etc., degassing method bell jar gas flow meter can't be carried out calibrating.

Summary of the invention:

The utility model is exactly at the problems referred to above, and a kind of high pressure backblowing bell-jar gas flow standard equipment that can carry out the malleation calibrating to the bigger critical flow sonic nozzle of the pressure loss is provided.

For achieving the above object, the utility model adopts following technical scheme, the utility model comprises bell-jar flow standard device, bell-jar flow standard device links to each other with the stagnation container, the computing machine of image data is respectively with bell-jar flow standard device, stagnation container with pressure transducer, temperature sensor, humidity sensor links to each other, and its structural feature stagnation container links to each other with admission gear.

The beneficial effects of the utility model:

This device is standard with the bell-jar gas flow standard equipment, adopt the air inlet method, make through supercooling, dry, voltage stabilizing, the gas of the high pressure of constant temperature, enter bell jar behind the stagnation of the flowing through container, volume increased after bell jar rose, flow through the volume of bell jar gas by measurement, temperature, pressure, and the front and back force value of measuring sonic nozzle, calculate the efflux coefficient of sonic nozzle, can carry out the purpose that the malleation calibrating detects sonic nozzle to the bigger critical flow sonic nozzle of the pressure loss thereby reach, the utility model can adopt the malleation mode to detect the pick-up unit of the gas meter of other elevated pressures loss simultaneously.

Description of drawings:

Fig. 1 is a structural representation of the present utility model.

Embodiment:

The utility model comprises bell-jar flow standard device 15, bell-jar flow standard device 15 links to each other with stagnation container 10, the computing machine 16 of image data is respectively with bell-jar flow standard device 15, stagnation container 10 with pressure transducer 11, temperature sensor 12, humidity sensor 13 links to each other, and stagnation container 10 links to each other with the standard admission gear.

Satisfy the malleation mode and detect the air inlet requirement for making through the high pressure gas of supercooling, drying, voltage stabilizing, the constant temperature body of calming the anger, the standard admission gear can be by constituting with lower device: be by air compressor 1, cooling tank 2, filtrator 3, exsiccator 4, the exit has the one-level buffer tank 5 of first class pressure variable valve 6, the exit has the secondary buffer tank 7 of secondary pressure variable valve 8, and constent temperature heater 9 connects and composes successively.

Stagnation container 10 physical dimensions are pressed related request design among the ISO 9300.The device that the utility model adopted all is to purchase from market.

A course of action of the present utility model:

Air compressor 1 starts and brings into operation, and produces the pressure-air of 0.8Mpa, and the air of compression can increase because of the heat absorption temperature.Cool through cooling tank 2.Process filter 3 filters out You Heshui wherein.Owing to the humidity of air can increase along with the rising of pressure, need exsiccator 4 to carry out dried.Drying is handled the back pressure-air and is entered 5 voltage stabilizings of one-level buffer tank, behind first class pressure variable valve 6, enter secondary buffer tank 7, behind secondary pressure variable valve 8, enter constent temperature heater 9, temperature is heated to 20 ℃ laboratory temperature, the pressure-air of this moment enters the stagnation container 10 that tested sonic nozzle has been installed through pipeline, the pressure of the upstream and downstream of the tested sonic nozzle of this moment will reach suitable back pressure ratio, pressure-air is behind pressure equilibrium variable valve 14, enter bell-type flow standard device 15, the temperature sensor 12 of bell-type flow standard device 15, on the data acquisition end of the signal output computing machine 16 of pressure transducer 11, the control output end of computing machine 16 is connected with the control input end of pressure equilibrium variable valve 14, the pressure transducer 11 of the stagnation container 10 of tested sonic nozzle upstream, temperature sensor 12, the signal output part of humidity sensor 13 (passing through signal wire) is connected to the data acquisition end of computing machine 16, computing machine 16 is gathered various process signals like this, digital filtering by computer-internal hardware and software realization, functions such as flow rate calculation are finally finished the data processing of tested sonic nozzle efflux coefficient, report output and printing.

Claims

1. high pressure backblowing bell-jar gas flow standard equipment, comprise bell-jar flow standard device (15), bell-jar flow standard device (15) links to each other with stagnation container (10), the computing machine of image data (16) is respectively with bell-jar flow standard device (15), stagnation container (10) with pressure transducer (11), temperature sensor (12), humidity sensor (13) links to each other, and it is characterized in that stagnation container (10) links to each other with the standard admission gear.

2. high pressure backblowing bell-jar gas flow standard equipment according to claim 1, it is characterized in that the standard admission gear is by constituting with lower device: be by air compressor (1), cooling tank (2), filtrator (3), exsiccator (4), the exit has the one-level buffer tank (5) of first class pressure variable valve (6), the exit has the secondary buffer tank (7) of secondary pressure variable valve (8), and constent temperature heater (9) connects and composes successively.