CN86207384U - Modular double-phase flowmeter consisting of orifice and venturi - Google Patents

Abstract

The utility model adopts an orifice and a venturi serving as a measuring element capable of simultaneously and exactly measuring the flow of each phase of the double-phase flow of gas (steam)-liquid, gas (steam)-solid and liquid-solid, which is suitable for the double-phase flow in low pressure, medium pressure and high voltage. The utility model has the advantages of simple structure and high reliability; each measured value can be processed by a microcomputer, automatically recorded and displayed.

Description

Modular double-phase flowmeter consisting of orifice and venturi

The utility model belongs to two phase fluid flow and dryness measurement instrument.

In fields such as power, chemical industry, oil, light industry, underground heat and nuclear energy, often run into vapour (gas)-liquid, gas-solid, the liquid-solid two phase fluid flow field problem that waits.In two phase fluid flowed, the flow size of each phase was an important parameter, therefore how accurately to measure simultaneously the flow of each phase fluid and was paid attention to by people always.In the two-phase flow two-parameter measurement, because of two unknown numbers are arranged, so people adopt the different measuring sensor of two specific characters to combine usually, to realize measuring simultaneously each phase flow rate.The method of this respect has at present: gamma-ray density meter and other conventional flow meter, and the instrument complex operation of this form is difficult to be extensive use of in industry; Orifice plate and gear meter make up this method and are only applicable to low pressure and full-bodied biphase gas and liquid flow; Two gardens lack well plate method, and this method error is big, average error 30%, and maximum error can reach 100%; Turbolator and Venturi tube combined method, because turbolator itself is difficult to realize yielding and fracture in standardization and the use, thereby not seen widespread use; This method of the box-like two-phase flow amount of restricting element one porous dynamic pressure probe groups drimeter (Chinese patent application number 86203508) has degree of precision to the measurement of vapour (gas)-liquid two-phase flow, but inapplicable to gas-solid and liquid-solid two-phase flow and high-viscosity fluid.In addition, it is gas-solid to adopt single orifice plate two-phase flowmeter (Chinese patent application number 85201644) can be used for, and solution-air and liquid-solid two-phase flow are measured, and higher precision is arranged, but this method enlarges markedly at high pressure two-phase flow time error, thereby use is restricted.The utility model proposes to adopt orifice plate and the combined method of Venturi tube at the problem of above-mentioned existence, can realize accurately measuring simultaneously each phase flow rate of the two-phase fluid under the various pressure.

Fig. 1 is orifice plate-Venturi tube combined type two-phase flow drimeter and measuring method synoptic diagram.(1) is orifice plate among the figure, (2) be orifice flange, (3) be the orifice plate pressure port, (4) be Venturi tube, (5) be the Venturi tube pressure port, (6) are tested tube, and (7), (8) are differential pressure transmitter, (9) be pressure unit, (10) are the joint flange of microcomputer (11) for Venturi tube and tested tube.

Fig. 2 is several different structure figure of orifice plate, and (12) are orifice plate German-style metal lensring one-piece construction figure among the figure, and (13) lack orifice plate for the garden, and (14) are segmental orifice plate, and (15) are the crescent orifice plate, and (16) are the arc orifice plate.

Fig. 3 is the Venturi tube structural drawing.

The utility model mainly is to adopt an orifice plate and a Venturi tube as measuring sensor; Orifice plate can be standard orifice plate or non-standard orifice plate, adopt orifice plate and German-style metal lensring one-piece construction (shown in Fig. 2 (12)) during high pressure, measure gas-solidly, the employing garden lacks shape, fan-shaped, crescent or arc orifice plate (shown in Fig. 2 (13), (14), (15), (16)) during liquid-solid or contaminative two-phase flow; The convergent of Venturi tube and flaring two parts, can be whole processing (as shown in Figure 3) or segmental machining after recombinant form.

The ways of measure pressure of orifice plate can be corner connection pressure or away from orifice plate pressure (10D or 30D etc., D is the tested pipeline internal diameter for 2.5D before orifice plate for example, 8D behind the orifice plate).Orifice plate and Venturi tube are made with brass or stainless steel usually.Measuring gas-solid or during liquid-solid two-phase flow, having on the measuring sensor inside surface that one deck is wear-resisting, a corrosion-resistant material (as silit etc.).

This flowmeter in use, should guarantee to be full of in the pressure guiding pipe single-phase liquid (when measuring gas-solid phase, should guarantee it is gas), concrete measuring process is: respectively with system pressure P in the measured pipe, pressure differential deltap Po imports microcomputer with Venturi tube pressure differential deltap Pv and can draw each flow value mutually before and after the orifice plate by pressure unit and differential pressure transmitter.Its principle is: orifice differential pressure Δ Po and Venturi tube pressure differential deltap Pv are tested each phase flow rate M ₁And M ₂Function, i.e. Δ Po=fo(M ₁, M ₂), Pv=fv(M ₁, M ₂), since orifice plate and Venturi tube structurally difference is very big, so Δ Po and Δ Pv have diverse functional form, so can obtain M according to two independent equations ₁And M ₂

The utility model, simple in structure, reliable operation, resistance is little, is applicable to the two-phase flow flow measurement under the various pressure; Each measured value can be handled and record, demonstration automatically with microcomputer.

Embodiment 1:

Use the utility model and measure vapour-liquid two-phase flow.67 millimeters of internal diameter of the pipeline, working pressure 127 atmospheric pressure adopt the combination of standard orifice plate and Venturi tube; Orifice plate corner connection pressure, perforate section ratio M ₀=0.1025, section ratio M=0.349 in Venturi tube aditus laryngis cross section and the tested pipeline.

According to following relationship formula (1), record Δ Po and Δ Pv and can mark two-phase flow total flow M, obtain mass dryness fraction X according to relational expression (2) then.

M＝ $\sqrt{{\mathrm{0.1\; △Pv-9.85\; \times \; 10}}^{\mathrm{-3}}\mathrm{(\; △Po)}}$ （1）

X＝0.3154（ $\sqrt{\mathrm{△Pv}}$ ／M）－0.9211 （2）

In the formula: M---two-phase flow total flow, ton/time;

X---two-phase flow mass dryness fraction;

Δ Po---orifice differential pressure, the millimeter of water;

Δ Pv---Venturi tube pressure reduction, the millimeter of water.

Embodiment 2:

Use the utility model and measure air-water mixt, working pressure is an atmospheric pressure, 25 millimeters of tested pipeline internal diameters, section ratio Mv=0.328 in the orifice plate perforate section ratio M=0.25, Venturi tube aditus laryngis cross section and tested pipeline.

According to following relationship formula (3), record Δ Po and Δ Pv and can calculate two-phase flow total flow M, obtain mass dryness fraction X according to relational expression (4) then.

M＝0.02419 $\sqrt{\mathrm{△Pv}}$ －0.01134 $\sqrt{\mathrm{△P\; o}}$ （3）

X＝3.171073×10 ^－4（ $\sqrt{\mathrm{△Pv}}$ ／M）－8.09 （4）

In the formula: M---two-phase flow total flow, Kilograms Per Second;

X---two-phase flow mass dryness fraction;

The pressure reduction of Δ Po---orifice plate, the millimeter of water;

The pressure reduction of Δ Pv---Venturi tube, the millimeter of water.

Claims (4)

1, a kind of combined type two-phase flowmeter is characterized in that being made of an orifice plate (1) and a Venturi tube (4).

2, according to the described orifice plate one Venturi tube combined type two-phase flowmeter of claim 1, it is characterized in that described orifice plate is a standard orifice plate, non-standard orifice plate, the garden lacks orifice plate (13), segmental orifice plate (14), crescent orifice plate (15), and arc orifice plate (16); Their all available brass or stainless steel are made.

3,, it is characterized in that described orifice plate adopts and German-style metal lensring one-piece construction (12) according to claim 1,2 described orifice plate one Venturi tube combined type two-phase flowmeters.

4, according to the described orifice plate one Venturi tube combined type two-phase flowmeter of claim 1, it is characterized in that described Venturi tube is whole workpiece or segmental machining subassembly.

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