CN1071008A - Line changeable range flowmeter - Google Patents

Abstract

The LINE CHANGEABLE RANGE FLOWMETER that fluid flow is used in a kind of measuring channel, constituted by flow sensor, pressure difference transmitter and secondary instrument, flow sensor is one to be connected in 90 ° of bend pipes that two ends on the fluid passage have straight length, on the tube wall of bend pipe, be provided with a wedge shape or trapezoidal resistance piece, on the tube wall before and after the resistance piece, be provided with and extraneous 3～4 pressure ports that communicate, measure the pressure differential between pressure port, by pressure difference transmitter and general analog or digital formula secondary instrument, both can demonstrate flow in the pipeline.Measurement of discharge broad quantum of the present invention, good measuring accuracy, sturdy and durable.

Description

LINE CHANGEABLE RANGE FLOWMETER

The present invention relates to a kind of LINE CHANGEABLE RANGE FLOWMETER that fluid flow is used in the pipeline that detects.

In having the industrial production facilities of line device, often to detect the flow in pipeline, to meet the needs of production the detection method of not interrupting fluid previously, mostly be that a throttling device such as orifice plate is installed in pipeline, the pressure differential of utilizing fluid to flow through and produced before and after the orifice plate is come calculated flow rate, this method, because restricting element immobilizes, its range is subjected to certain limitation, both is worn easily, and fluid pressure loss is also very big; Recently, produce a kind of orifice valve, this valve can flow not interrupting fluid, promptly under online situation, change different orifice plates, to enlarge its sensing range, but this will prepare the polylith orifice plate, structure more complicated, cost height, when changing orifice plate, sometimes because orifice plate is stuck in pipeline, corrosion is changed very difficult, and still can not solve the big problem of fluid pressure loss, so can not satisfy request for utilization.

The objective of the invention is to provide a kind of improved LINE CHANGEABLE RANGE FLOWMETER, it is simple in structure, and is sturdy and durable, and cost is low, can change parts when changing range, easy to use.

The object of the present invention is achieved like this: this LINE CHANGEABLE RANGE FLOWMETER, be to utilize fluid in the pipeline of bending during constricted flow, under the effect of centrifugal force and resistance piece, the flow difference, diverse location place at inner-walls of duct, the pressure that is born is also inequality, and following funtcional relationship is arranged between its flow and the two point pressure differences:

Q0.003999·SD ² $\sqrt{\frac{\mathrm{\Delta \rho }}{\rho }}$ In the formula

Q: flow m ³/ h; S: coefficient of flow, demarcate by actual measurement;

D: bend pipe internal diameter mm; ρ: fluid density kg/m ³;

△ P: the pressure differential Pa between 2 pressure points; 0.003999: the conversion factor that unit conversion produces;

Change the different pressure taps on the tube wall, and compare its pressure differential, can record the flow in maximum magnitude flow range inequality, thus the corresponding measuring accuracy that improved.

According to above-mentioned principle, this liquid flowmeter is made of flow sensor, pressure difference transmitter and secondary instrument, flow sensor is constituted by the square bend pipe that two ends are connected in straight-line segment, on the inwall of inboard, bend pipe corner, be provided with wedge shape or trapezoidal resistance to flow part, before and after resistance piece,, be provided with and the extraneous hydraulic pressure pressure port that is connected and has valve along on the tube wall of bend pipe; The input end of pressure difference transmitter has two pipe interfaces, can be connected with the pressure pipeline of two various combinations, and the output terminal of pressure difference transmitter is connected with secondary instrument with lead, and the pressure differential of two pressure port place liquid is sent to secondary instrument with electric signal; Secondary instrument is one with the electric signal of receiving, carries out data processing, and the microcomputer device that shows and print provides instantaneous, the integrated flux of liquid in the pipeline.

The present invention has the following advantages:

1) flow measurement range is wide, and is easy to use: because of need not to change measuring sensor, and the pressure port that only changes various combination can change the measurement range of flow, and its measuring range quantity ratio can reach 1: 7～and 9.

2) measuring accuracy height: because of the available different pressure ports that adapt with actual flow, combination makes pressure difference signal big mutually, and so the resolution height is the corresponding measuring accuracy that improved.

Fluid pressure loss is little when 3) measuring, and sensor construction is simple, and is sturdy and durable, easily maintenance.

Describe concrete structure of the present invention and working condition thereof for example in detail below in conjunction with accompanying drawing.

Fig. 1 is this flowmeter technological process reference view.

Fig. 2 is a flow sensor enlarged diagram in this flowmeter.

With reference to Fig. 1,2, fluid to flow sensor 6, on the inwall of the inboard, corner of sensor 6 bend pipes, is provided with wedge-shaped resistance spare 7 through pump 5 force feeds, on the tube wall of resistance piece 7 front and back, is provided with the pressure port 1,2,3,4 that has valve 8; Fluid by the pressure port outflow, through the last lower valve of sealing chamber 9,, do not make it enter pressure difference transmitter and rest in the pipeline with gas in the fluid or liquid and impurity discharge, three valve groups set pipe joint about in the of 10, be connected with pressure difference transmitter 11 and sealing chamber 9 respectively in twos, be provided with equalizing valve in the three valve groups 10, as required, different pressure ports can be connected, so that the zero point of verification pressure difference transmitter 11,12 is secondary instrument, and 13 is container.

During use, detailed process is as follows:

1) according to the approximate range of institute's measurement of discharge, selected a pair of pressure port, and with valve open on it;

When 2) measuring fluid flow, open the last valve of sealing chamber 9, close after gas in the pipeline is discharged;

3) no matter measure liquid or gas flow in the pipeline, all need open the lower valve of sealing chamber 9, the sediment and the impurity of liquid in the pipeline of flowing through are discharged, the liquid of gas is discharged in the pipeline of maybe will flowing through, and then closes;

4) open two valves and the equalizing valve (not drawing among the figure) that three valve groups are led to pressure difference transmitter, when the electric current of observation pressure difference transmitter 11 outputs is 4mA, show that zero point is normal, close equalizing valve, pressure difference transmitter 11 outputs and the corresponding electric signal of pressure reduction are to secondary instrument;

5) secondary instrument is general analog or digital formula instrument, changes into input signal instantaneous or integrated flow shows or be printed as literal.

Particular content is as follows in the present embodiment:

1) tested condition:

(1) measured medium: water

(2) Media density: 998kg/m ³

(3) working temperature: 20 ℃

(4) working pressure: 2MPa

(5) internal diameter of the pipeline: 50mm

(6) prediction maximum flow: 22t/h

2) adopt the flowmeter situation:

(1) flow sensor internal diameter: D=50mm

(2) select 1151 type condenser type pressure difference transmitters for use, range △ P=1 * 10 of dispatching from the factory ⁴Pa

(3) according to the spot pressure of flow and differential manometer range employing 2～4 pressure tappings, the flow coefficient k of this combination is demarcated according to test, is input in the computing machine.

(3) measured result

Flow value=22t/h

Pressure differential: 9460Pa

When taking the pressure point of various combination in the embodiment of the invention, it is as shown in the table that each group is measured range:

Pressure point group measurement range

Close mode △ Pmin Pa Qmin m ³/ h △ Pmax Pa Qmax m ³/ h

2～3 880 6.4 9500 21

2～4 5000 16 9460 22

1～3 3170 13 9920 23

1～4 3000 15 9720 27

2～1 2930 26 10000 48

As can be seen from the above table, when taking different pressure point array mode, its minimum flow is 6.4 with the maximum flow ratio: 48=1: 7.5.

Claims (1)

1, the LINE CHANGEABLE RANGE FLOWMETER that fluid flow is used in a kind of measuring channel, constituted by flow sensor, pressure difference transmitter and secondary instrument, it is characterized in that: flow sensor is connected with the square bend pipe of straight length by two ends, on the inwall of inboard, bend pipe corner, be provided with wedge shape or trapezoidal resistance to flow part, the front and back that resistance piece is arranged have 3～4 pressure ports that are connected with the external world.

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