CN2239016Y - Mass flowmeter - Google Patents

Abstract

The utility model relates to a mass flowmeter with changeable components, which comprises a transmitter (1) with pressure difference, a three valve group (3), a signal leading block (5), a probe (8) and a measuring pipeline (9). The utility model is characterized in that a piezoelectric crystal element is embedded in the probe (8), and a vortex generating body (10) is arranged facing to a fluid direction; a longitudinal center slotted hole (12) of the vortex generating body (10) is communicated with a transverse hole (11) which is arranged at one side of the vortex generating body (10) to form a uniform velocity tube; the vortex generating body (10) is a triangular column. The utility model can send out two flow signals, namely, a vortex street flow frequency signal and a throttle pressure difference simulating signal, by using one flowmeter. The utility model has the advantages of simple structure, convenient and accurate measure and flexible regulation.

Description

Mass flowmeter

The utility model is the improvement invention about flowmeter, particularly becomes the invention of component flow mass flowmeter.

In the prior art, the liquid phase of the dry gas of petroleum refining factory or tail gas oil liquefied gas or gas phase, and rock gas etc., these fluids normal flow flowmeter measurement, generally can only record volumetric flow rate, promptly use temperature, pressure compensation method can not record mass rate, the flowmeter of known technology, when fluid passes through, can only provide a flow signal, i.e. a frequency signal or a simulating signal, when flowmeter puts into operation, instrumentation person can not affirm the authenticity of flow signal, at this moment needs other with reference to measuring the accuracy of judging signal, is very inconvenient.

In view of the problem that known technology exists, the purpose of this utility model aim to provide a kind of simple in structure, measure flowmeter convenient, that adjust flexibly and can obtain simultaneously two real quality flows.

The utility model is finished as follows: whole change constituent mass flowmeter includes differential pressure transmitter, three valve groups, signal and draws piece, probe and measuring channel, buries piezolectric crystal unit in the probe underground.Of the present utility model being characterised in that: be provided with triangulo column in face of flow direction, be drilled with slotted hole, communicate with the cross-drilled hole of triangular prism one side and become even speed tube in the longitudinal center of triangulo column.

Principle of the present utility model is the flowmeter of the combined measurement of vortex street frequency measurement and differential pressure measurement, when entering the display instrument with computing function, differential pressure signal and frequency signal just can demonstrate instantaneous mass flow, the density value under mass accumulation flow and the work condition state.

The utility model is compared with known technology: have simple in structure, measure convenient, adjust flexibly and can long-term operation.

The utility model has following accompanying drawing

Fig. 1 is a mechanical assembly drawing of the present utility model

Fig. 2 is an eddy generator installation diagram of the present utility model

Fig. 3 is the enlarged drawing of eddy generator

Fig. 3 A is that eddy generator is along the A-A sectional view

The back produces frequency to Fig. 4 and the flow velocity whirlpool concerns synoptic diagram for triangular prism inserts

Fig. 5 is the probe installation location synoptic diagram

Accompanying drawing has been represented basic structure of the present utility model and embodiment, further describes each relevant details and principle of work thereof of embodiment below again.One of flow sensor theoretical foundation that at first need to prove change constituent mass flowmeter is " Karman vortex street " principle, the main element of vortex shedding flow meter is that eddy generator is a triangular prism, it has produced strong vortex row under the condition of turbulent flow, position, trequetrous plane faces the flow direction such as Fig. 3 of fluid, it has certain throttling action, but throttling action a little less than, being that differential pressure signal is less adds the even speed tube effect, differential pressure signal is strengthened, and make differential pressure value more stable, utilized an eddy generator like this, both obtained frequency signal, the differential pressure signal of having got back, these two kinds of detected amplifiers of signals while detect delivers to the display that has computing function, just obtain instantaneous mass flow, mass accumulation flow and density of medium, this flowmeter fluid by the time can provide two flow signals simultaneously, one is that (pulse signal) is frequency signal, another is a simulating signal, it is differential pressure signal, the volumetric flow rate that these two signals draw respectively is same, and whether operate as normal is in normal condition therefore just to judge instrument, further specifies flux of vortex street measuring principle and differential pressure measurement principle below respectively; Set forth the flux of vortex street measuring principle earlier, one of flow sensor theoretical foundation is the Karman vortex street principle, when in fluid, inserting a columnar object, will alternately produce whirlpool clocklike from the columnar object both sides, the frequency that whirlpool separates is directly proportional with flow velocity, be inversely proportional to the width of column, can represent with following formula: f=st.v/d

F-whirlpool cross frequence in the formula; St-coefficient (Sr); The v-flow velocity; The d-column width, this shows, just can calculate instantaneous delivery by the cross frequence of measuring the toll bar whirlpool, adopt piezolectric crystal unit to detect the whirlpool cross frequence, two surveys produce pressure fluctuation because whirlpool is at the cylinder rear portion, and the probe that is installed in the cylinder rear portion will be experienced an alternating force, are embedded in the inner piezolectric crystal unit of probe and are subjected to the effect of this alternating force and produce the alternation electric charge, amplifier signal is handled after testing, reaches testing goal.(see figure 5), put off until some time later bright differential pressure measurement principle below, vortex flow sensors is a triangular prism in face of the cylinder of fluid, it not only produces stable vortex row, can also produce the resistance element of differential pressure, at its place, plane in face of fluid, the circulation duct cross section is divided into two crescent, the ratio m=0.6456 that its actual internal area is long-pending with pipeline section, quite the diameter of orifice plate has had parameter beta just can be write as the throttling flow formula than β=0.8 $Q=\mathrm{\&pi;}/4D^{2}a\sqrt{\mathrm{\&Delta;P}/P}{----\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="Y9520804800061.png,Y9520804800071.png"\; state="\{\{state\}\}">m</figure-callout>}}^3/s$ The first diameter m of D-runner pipe in the formula; The a-coefficient of flow is made by experiment; The differential pressure ρ a that the p-triangular prism produces; The density kg/m of ρ detected fluid ³, in order to enlarge effective differential pressure and to make differential pressure more stable as far as possible, be drilled with a blind hole, and communicate with four cross-drilled holes of triangular prism one side in trequetrous longitudinal center, as even speed tube, its effect is quite obvious, this design motif just of the present utility model.

Claims (2)

1, a kind of change constituent mass flowmeter, include differential pressure transmitter (1), three valve groups (3), signal and draw piece (5), probe (8), measuring channel (9), probe (8) inside are buried piezolectric crystal unit underground, it is characterized in that: be provided with eddy generator (10) in face of flow direction, longitudinal center's slotted hole (12) of this eddy generator (10) communicates with the cross-drilled hole (11) of eddy generator (10) one sides.

2, change constituent mass flowmeter as claimed in claim 1 is characterized in that: eddy generator (10) is a triangular prism.

Images