CN1233748A - Method for continuous back-flushing cleaning in differntial pressure type flow measuring system - Google Patents

Abstract

The present invention relates to he continuous back-flushing cleaning method for differential pressure flow measuring system, it includes the following steps: 1. the filtered clean fluid is sent to constant pressure unit; 2. the constant pressure unit outputs two paths of clean fluid which are equal in flow and pressure but the pressure is higher than that of detected fluid; 3. the two path clean fluid are respectively blown into the positive and negative pressure guiding tubes of measuring system with zero pressure difference but not influence the measuring accuracy, finally flow into the non clean fluid pipe and carried away by the non clean fluid. The advantages of present invention include: to realize continuous back flushing cleaning of differential pressure flow measuring of non clean fluid, eliminate the blocking of pressure guiding tube pore, raises the accuracy of measuring system, low in maintaining cost.

Description

Continuous blowback cleaning method in the differential pressure method Flow Measuring System

The present invention relates to be applicable in the differential pressure method Flow Measuring System of non-clean fluid that the positive negative pressure connecting pipe of differential pressure signal that stops non-clean fluid to enter in the system stops up pore, and the continuous blowback cleaning method that adopts.

Non-clean fluid comprises the fluid of dust, silt and other solid particle, the differential pressure method of non-clean fluid is measured as adopts even speed tube, orifice plate, nozzle, Venturi tube, skin to take off the method general name that flow sensor such as pipe is measured flows.In the non-clean fluid differential pressure method of the prior art flow measurement, most flow systems still allow non-clean fluid enter the positive and negative connecting pipe of differential pressure signal, treat that pore stops up laggard row cleaning or replacing, this method is cleaned or is changed after need stopping to measure, and work efficiency is reduced.In a small amount of Flow Measuring System, design has the batch (-type) back-blowing device in the prior art, promptly aligns the negative pressure connecting pipe and does regularly or irregularly to purge.There is following problem in this intermission type artificial back-blowing device:

1. must stop the instrument operation during blowback, stopwatch then causes the interruption of flow measurement.

2. intermission type artificial blowback, the pore that can not eliminate positive negative pressure catheter stops up, and can only reduce obstruction.

3. batch (-type) blowback must manually get involved, and increases maintenance load.

4. intermission type artificial blowback will damage differential pressure transmitter as careless manipulation.

The objective of the invention is to overcome the deficiency of intermission type artificial blowback method and device existence, and a kind of positive negative pressure connecting pipe obstruction of effectively eliminating is provided, guarantee the accurate metering of non-clean fluid Flow Measuring System and the continuous blowback cleaning method in the continuous differential pressure method Flow Measuring System that moves.

Continuous blowback cleaning method in the differential pressure method Flow Measuring System that provides of the present invention comprises following several steps:

1). with clean fluid, send into pressurestat after filtering as pure air or clean water;

2). pressurestat is exported the clean fluid that two-way flow at least, pressure equate to the Apparatus for spraying and jetting particulate materials constant voltage, and its pressure is greater than the pressure in the tested non-clean fluid conveyance conduit;

3) the equal clean fluid of every two-way flow and pressure, by Apparatus for spraying and jetting particulate materials respectively in Flow Measuring System sampling side jets positive and negative pressure connecting pipe in measuring system in the opposite direction, form that a pair of pressure reduction equals zero and the fluid that do not influence measuring accuracy, flow in the tested non-clean fluid conveyance conduit by positive and negative connecting pipe, take away by non-clean fluid.Further specify below by the equipment of accompanying drawing said method of the present invention and employing thereof.

The present invention has following accompanying drawing:

Accompanying drawing 1 is the theory diagram of the continuous back-blowing device of the present invention;

Schematic diagram is blown in anti-continuously cleaning among the accompanying drawing 2 integrated even speed tube Flow Measuring System FGQB;

Accompanying drawing 3 is the continuous blowback cleaning schematic diagram of the DBCK of pore plate flow measurement system.

Referring to accompanying drawing 1: this device that the present invention relates to comprises filtrator GL, pressurestat HP, at least two Apparatus for spraying and jetting particulate materials PCA and Apparatus for spraying and jetting particulate materials PCB.

Referring to accompanying drawing 2, accompanying drawing 3, the continuous blowback cleaning method of the differential pressure method Flow Measuring System that provides of the present invention mainly comprises following several steps:

1). with clean fluid JN, send into pressurestat HP after filtering as pure air or clean water;

2). pressurestat is exported the clean fluid that two-way flow at least, pressure equate, pressure P 1, P2 that this pressure P produces in positive negative pressure connecting pipe greater than non-clean fluid to be measured to the Apparatus for spraying and jetting particulate materials constant voltage;

3). the clean fluid that every two-way flow and pressure equate, by Apparatus for spraying and jetting particulate materials respectively Zi jetting in the opposite direction in the positive and negative pressure connecting pipe in measuring system with Flow Measuring System sampling side, form that a pair of pressure reduction equals zero and the fluid that do not influence measuring accuracy, flow in the non-clean fluid conveyance conduit to be measured by positive and negative connecting pipe, take away by non-clean fluid.

Differential pressure (Δ P) expression formula of general Flow Measuring System is:

ΔP=P1-P2 (1)

The Flow Measuring System differential pressure of band blowback clearing apparatus of the present invention (Δ P) expression formula is:

ΔP=(P+P1)-(P+P2)=P1-P2 (2)

(1) every physical significance and in (2) formula:

Square differential pressure signal that is directly proportional of Δ P-and detected fluid flow;

The malleation wall pressure of P1-flow sensor, i.e. normal pressure;

The suction side pressure of P2-flow sensor, i.e. negative pressure;

Pressurestat top hole pressure in the P-back-blowing device, i.e. jetting pressure.Spray into positive negative pressure pilot

Pipe is same pressure P

Contrast as seen by (1) formula and (2) formula, after positive negative pressure connecting pipe is blown into clean fluid, do not influence flow measurement and measuring accuracy by back-blowing device.

In device of the present invention, clean fluid JN is provided by the outside.Filtrator GL does final the filtration with blowback with clean fluid, stops oil, water and dust to enter pressurestat HP, Apparatus for spraying and jetting particulate materials PCA and PCB, influences the back-blowing device operate as normal.

Pressurestat HP is constant in a certain setting value with the clean fluid pressure P with blowback, for Apparatus for spraying and jetting particulate materials PCA and PCB.Two Apparatus for spraying and jetting particulate materials are communicated with non-clean fluid conveyance conduit by the positive and negative pressure connecting pipe in the measuring system respectively, and lay respectively at the positive and negative pressure measuring junction of flow sensor.

Apparatus for spraying and jetting particulate materials PCA and PCB are blown into the positive negative pressure connecting pipe of flowmeter with the clean fluid after the constant voltage, stop non-clean fluid to enter positive negative pressure connecting pipe and stop up pore.

The principle of work of blowback clearing apparatus in the non-clean fluid flow measurement of differential pressure method is so continuously:

The blowback clean fluid that provides by the outside, after filter GL filtration, pressurestat HP constant voltage, divide two-way to be blown into the positive negative pressure connecting pipe of flowmeter respectively, flow into non-clean fluid conveyance conduit from positive negative pressure connecting pipe, take away by ducted non-clean fluid, stop non-clean fluid to enter the positive negative pressure connecting pipe of flowmeter, also just eliminated the obstruction of pore.

The present invention has the following advantages:

1. realize the continuous blowback cleaning of the differential pressure method flow measurement of non-clean fluid.

2. stop non-clean fluid to enter flowmeter positive/negative-pressure connecting pipe, eliminated positive/negative-pressure pilot pore Stop up.

3. accuracy, the reliability and stability of differential pressure method Flow Measuring System have been improved.

4. maintenance cost is low, maintenance load is little.

Claims (1)

1. the continuous blowback cleaning method in the differential pressure method Flow Measuring System is characterized in that comprising following several steps:

1). send into pressurestat HP after clean fluid JN filtered;

2). pressurestat is exported the clean fluid that two-way flow at least, pressure equate to the Apparatus for spraying and jetting particulate materials constant voltage, and its pressure P is greater than the pressure P 1, the P2 that treat that fluid measured produces in the positive and negative pressure connecting pipe of measuring system;

3). the clean fluid that every two-way flow and pressure equate, by Apparatus for spraying and jetting particulate materials by its nozzle respectively from Flow Measuring System sampling side jet in the opposite direction to the positive and negative pressure connecting pipe in, form in measuring system that a pair of pressure reduction equals zero and the fluid that do not influence measuring accuracy, flow in the tested non-clean fluid conveyance conduit by positive and negative connecting pipe, take away by non-clean fluid.

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