CN100590406C - Intelligent gas leakage detector for introducing refernece flow - Google Patents

Abstract

The invention belongs to the energy conservation field of the pneumatic system, and realizes a parallel connection access type smart gas leakage detector for introducing a datum flow. When in measurement, a gas supply for an object to be detected is stopped. A detection device is connected in parallel to an idle interface of a gas supply pipeline of the object to be detected. In order to obtain the difficultly measured volume of a pneumatic loop of a device to be detected, the datum flow is introduced, and the volume is calculated through the change of the rate of pressure decline. At the sametime, in order to be adapted to the characteristic that high range ratio is required because the leakage flow can not be estimated in the field, the method adopts the smart switching technology of multi-segment datum flow, the automatic matching of the datum flow and the leakage flow are conducted, thereby realizing the range ratio of 200 required for the field measurement. Compared with the traditional leakage detection method, the method of the invention has the advantages of simple use, high range ratio and wide application in the energy field of pneumatic system.

Description

Import the intelligent gas leakage detector of standard flow

The invention belongs to energy-saving field of pneumatic, relate to a kind of intelligent gas leakage detector that imports the access type in parallel of standard flow.

Background technology

The gas Leak Detection is the gordian technique of energy-saving field of pneumatic.Pneumatic system is because advantages such as cost is low, pollution-free, easy care are being brought into play important effect in industries such as automobile production, semiconductor manufacturing.But reveal seriously in the pneumatic system, amount of leakage accounts for the 10-50% of total air demand, and in today that energy problem becomes increasingly conspicuous, the energy-conservation of pneumatic system has great significance in China.

Domestic existing equipment or pipe arrangement net leakage measuring instrumentation all need flowmeter series connection is inserted pipeline, take supply air line apart or cut metallic conduit and carry out complex installation after stopping air feed.Leakage flow is measured the less demanding characteristics of accuracy of measurement at pneumatic in energy-conservation, the present invention proposes the intelligent gas leakage detection method that imports standard flow, end during measurement to the measurand air feed, the pick-up unit idle interface that inserts the measurand supply air line in parallel, do not need external source of the gas, easy to use.

Summary of the invention

The objective of the invention is: provide a kind of and insert conveniently, simple to operate, range ratio is high, satisfy the gas leakage measuring instrumentation instrument of energy-conservation requirement.

Technical scheme of the present invention is: import standard flow and infer the measurand volume; Adopt the multistage standard flow to mate automatically and reveal flow to improve the measurement range ratio.Surveying instrument constitutes (referring to Fig. 1) by multistage standard flow generation loop, Pressure/Temperature measurement loop, controller.

1. the multistage standard flow produces the loop, it is characterized in that:

Two above benchmark throttle orifices 1 are inserted measure loops, each throttle orifice upper reaches is by the logical of electromagnetic switch valve 2 control loops and close, and flows to atmosphere opening under each throttle orifice.By control electromagnetic switch valve 1, can produce standard flow more than two sections.

2. Pressure/Temperature is measured the loop, it is characterized in that:

A pressure transducer 3 and temperature sensor 4 are inserted the measurement loop.The measuring-signal of pressure transducer 3 and temperature sensor 4 is delivered to processor 6 via A/D converter 5.

3. controller is characterized in that:

Controller by A/D converter 5, processor 6, electromagnetic switch valve drive loop 7, measuring process and as a result display panel 8 constitute.Begin behind the stop valve before closing measurand to measure, the pressure that controller is only caused by leakage flow when the measuring basis flow does not produce at first respectively changes, leakage flow added that the pressure that standard flow causes changes when tentative standard flow produced.Then, the ratio according to these two variations mates final standard flow.Pressure when at last, measuring final standard flow and produce changes the leakage flow of finding the solution measurand and shows measurement results at display panel 8.This a series of process is all finished by controller.

Advantage of the present invention is: compare with the flowmeter that traditional leak detection is used, detector of the present invention need not connected and be inserted the measurand supply air line, and the idle interface of supply air line that inserts in parallel gets final product, and does not need to connect source of the gas in addition, and fitting operation is simple; Simultaneously, make the range ratio of this detector can reach 200 (traditional range ratio all is lower than 30), satisfy on-the-spot energy-conservation Testing requirement based on the design of multistage standard flow.

Description of drawings

Fig. 1 is the formation block diagram of detector of the present invention.

Embodiment

Below the present invention is further illustrated.

1. leakage flow measuring principle

The purpose that imports standard flow is to fall to be difficult to the directly volume of the measurand pneumatic circuit of measurement in order to disappear, and the measuring process of revealing flow is as follows:

(a) close stop valve on the supply air line, cause owing to leak that pressure begins slow decline in the loop at this moment;

(b) electromagnetic switch valve that the control standard flow is produced is in closed condition, gaging pressure P ₀, find the solution pressure differential value dP ₀/ dt;

(c) open the electromagnetic switch valve that the control standard flow produces, gaging pressure P ₁, find the solution pressure differential value dP ₁/ dt;

Based on above measured value, calculate the leakage flow G of measurand _lWherein, V is measurand and the total measurement (volume) that detects the loop, and R is the air gas constant, T _aBe atmosphere absolute temperature, G _sBe standard flow.

When standard flow did not take place, the leakage flow of gas was:

$G_l=\frac{V}{\mathrm{RT}}\·\frac{{\mathrm{dP}}_0}{\mathrm{dt}}$ (formula 1)

When standard flow took place, the leakage flow of gas added that standard flow equals:

$G_l+G_s=\frac{V}{{\mathrm{RT}}_a}\&CenterDot;\frac{{\mathrm{<figure-callout\; id="1"\; label="dP"\; filenames="C2007101200120006H1.png"\; state="\{\{state\}\}">dP</figure-callout>}}_1}{\mathrm{dt}}$ (formula 2)

Divided by (formula 1) cancellation total measurement (volume) V, the leakage flow that can obtain measurand is with (formula 2):

$G_l=\frac{1}{\frac{{\mathrm{<figure-callout\; id="1"\; label="dP"\; filenames="C2007101200120006H1.png"\; state="\{\{state\}\}">dP</figure-callout>}}_1/\mathrm{dt}}{{\mathrm{dP}}_0/\mathrm{dt}}-1}\&CenterDot;G_s$ (formula 3)

Keep off zero for the denominator of dependable flow formula, it is too big that the standard flow of generation and leakage flow can not differ.Producing the multistage standard flow with a plurality of benchmark throttle orifices among the present invention mates automatically with leakage flow.

2. the hardware of detector (referring to Fig. 1)

The generation that electromagnetic switch valve 1 is used to control standard flow whether.

Benchmark throttle orifice 2 is used to produce standard flow.

Pressure transducer 3 is gathered the force value of measuring the loop in real time.

Temperature sensor 4 is gathered the temperature compensation that the temperature value of measuring the loop is used for standard flow in real time.

A/D converter 5 is used for analog signal conversion with pressure transducer 3 and becomes digital signal to offer processor 6 to carry out computing.

Processor 6 is by the external crystal starting of oscillation, and the real time record Measuring Time is come the calculating pressure differential value according to the digital signal that A/D converter 5 obtains, and controlled electromagnetic switch valve 1 according to the variation of force value, opens standard flow the loop takes place.

Electromagnetic switch valve drives the switch controlling signal of loop 7 being exported by processor 6 and carries out power amplification, drives electromagnetic switch valve 1 and produces standard flow.

Display panel 8 is used for showing measurement progress information and measurement result.

Claims (2)

1, a kind ofly imports the method that standard flow is measured the measurand leakage flow indirectly, it is characterized in that: insert the idle interface of measurand supply air line to produce the multistage standard flow with a plurality of benchmark throttle orifices parallel connections, each benchmark throttle orifice upper reaches is by the logical of an electromagnetic switch valve control loop and close, and flows to atmosphere opening under each benchmark throttle orifice; The pressure that is only caused by leakage flow when the measuring basis flow does not produce changes dP ₀Leakage flow added that the pressure that standard flow causes changes dP when/dt and standard flow produced ₁/ dt; When standard flow does not produce, the leakage flow G of measurand ₁For: $G_1=\frac{V}{{\mathrm{RT}}_a}\&CenterDot;\frac{d{P}_0}{\mathrm{dt}};$ When standard flow produces, the leakage flow G of measurand ₁Add standard flow G _sEqual: $G_1+G_s=\frac{V}{{\mathrm{RT}}_a}\&CenterDot;\frac{{\mathrm{dP}}_1}{\mathrm{dt}};$ Above two formulas are divided by, when promptly not producing by standard flow and the ratio that changes of the pressure of standard flow when producing come volume V and air gas constant R and atmosphere absolute temperature T in the cancellation computing formula _aThereby, the leakage flow G that finds the solution measurand ₁For: $G_1=\frac{1}{\frac{{\mathrm{dP}}_1/\mathrm{dt}-1}{{\mathrm{dP}}_0/\mathrm{dt}}}\&CenterDot;G_s.$

2, importing standard flow according to claim 1 is measured the method for measurand leakage flow indirectly, it is characterized in that: adopt the multistage standard flow to mate leakage flow automatically and measure range ratio to improve, intelligence is switched the multistage standard flow to mate with leakage flow, and realization can be satisfied the high range ratio of in-site measurement requirement.

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