CN101467009A - Multi-vortex flowmeter employing volume flow rate as switching point - Google Patents

Abstract

A multi-vortex flowmeter (1) includes a vortex flowmeter for measurement by volume flow rate and a thermal flowmeter for measurement by mass flow rate to selectively use the two flowmeters according to the flow rate of fluid to be measured flowing through a flow channel (13). The multi-vortex flowmeter (1) uses the mass flow rate for a switching point. In other words, the multi-vortex flowmeter (1) has the switching point of two flowmeters based on the mass flow rate. A mass flow rate Qm at the switching point in a range larger than the minimum flow rate of a vortex flowmeter and smaller than the maximum flow rate of a thermal flowmeter is determined by: Qm=K3* P, (where, P is a pressure of the flow channel (variable), K3 is a constant determined by the area and the vortex differential pressure of the channel (13) and a constant related to the vortex differential pressure, a density at 0 DEG C and 1 atm, and the pressure at 1 atm). Alternatively, a volume flow rate Q at the switching point in a range larger than the minimum flow rate of a vortex flowmeter and smaller than the maximum flow rate of a thermal flowmeter is determined by: Q=K1/ P, (where, P is a pressure of the channel (variable), K1 is a constant determined by the area and the vortex differential pressure of the flow channel (13) and a constant related to the density at 0 DEG C and 1 atm, and the pressure at 1 atm).

Description

With the multi-vortex flowmeter of volume flow as switching point

Technical field

The present invention relates to a kind of multi-vortex flowmeter, have with volume flow and carry out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use above two flowmeters corresponding to the flow of the determined fluid that in stream, flows, more specifically, the switching point that relates to two flowmeters.

Background technology

Vortex shedding flow meter and thermal flowmeter are used to the flow of instrumentation mobile determined fluid in the stream pipe.

Vortex shedding flow meter is the flowmeter that utilizes following principle as known in the art, when promptly in the flowing of fluid, disposing vortex generation body, in set reynolds number range, the Kaman's vortex number (eddy frequency) that produces in the unit interval from vortex generation body has nothing to do and proportional with flow with gas, liquid, and this proportionality constant is called as Strouhal number.As the vortex detection device, listed thermal sensor, strain transducer, optical sensor, pressure transducer, ultrasonic sensor etc., they are the sensors that can detect thermal distortion that vortex causes, lift variation etc.Vortex shedding flow meter be can not be subjected to determined fluid physical characteristics influence and measure the easy flowmeter of flow, be used to the flow metering (for example, with reference to No. 2869054 communique of special permission) of gas or fluid widely.

Thermal flowmeter constitute have the temperature-sensitive sensor (fluid temperature (F.T.) detecting sensor) and the heating temperature-sensitive sensor (heated side temperature sensor), the temperature that will have the heating temperature-sensitive sensor (flow sensor (well heater)) of the function of temperature sensor and heating sensor is controlled to be with respect to the temperature by temperature-sensitive sensor instrumentation and has certain temperature difference.This is for following purpose: because the heat of taking away from well heater when determined fluid is flowed through is relevant with mass rate, so can calculated mass flow (for example, opening the 2004-12220 communique with reference to the spy) by the heating electric weight to well heater.

Open in the 2006-29966 communique the spy, disclose the technology of multi-vortex flowmeter of the function of the function that has vortex shedding flow meter concurrently and thermal flowmeter.Multi-vortex flowmeter can both carry out instrumentation from tiny flow quantity accurately up to big flow, and it is excellent especially that this point is compared other flowmeters.

Multi-vortex flowmeter separately uses the function of vortex shedding flow meter and the function of thermal flowmeter according to the state that flows of the determined fluid that flows in the stream of stream pipe.That is, in tiny flow quantity territory or low discharge territory, carry out instrumentation, in the high flow capacity territory, carry out instrumentation by the function of vortex shedding flow meter by the function of thermal flowmeter.

Vortex shedding flow meter reduces and vortex differential pressure when reducing at flow, and the susceptibility of vortex detection device can be not enough, so in multi-vortex flowmeter, to control to the mode of thermal flowmeter handoff functionality under set lower limit flow.

In multi-vortex flowmeter in the past, about the switching of the function of the function of vortex shedding flow meter and thermal flowmeter, carrying out with the flow is the control that benchmark is judged.That is, in multi-vortex flowmeter in the past, control to arrive the mode that certain certain flow then switches.The present inventor thinks that wherein the problem of Cun Zaiing is the pressure of not considering fully in the stream pipe.Below, with reference to this problem points of description of drawings.

The present inventor finds following situation to occur: the vortex differential pressure uprises if the pressure in the stream pipe rises then even if flow reduces, lower limit flow as the judgment standard when switching the function of flowmeter reduces thus, and the present inventor considers that the result that will find is reflected on the multi-vortex flowmeter.The present inventor in order to effectively utilize the advantage of vortex shedding flow meter, considers to use the function of this vortex shedding flow meter to measure flow as best one can.

Among Fig. 7 (A), be in volume flow [L/min], the chart of transverse axis, with the minimum flow (dot-and-dash line) of curve representation vortex shedding flow meter for the pressure [Mpaabs] in the stream pipe at the longitudinal axis.Learn that by this chart vortex shedding flow meter is along with the pressure in the stream pipe rises, can instrumentation up to lower flow.This be because: the vortex differential pressure uprises if the pressure in the stream pipe rises then even if flow reduces, and vortex signal is stable.This is that the present inventor proposes.

But, in multi-vortex flowmeter in the past, as mentioned above, if arriving certain certain flow just switches, so if in chart, illustrate switching point, then as the heavy line of the horizontal straight line of Fig. 7 (b) shown in (curve that switching point is illustrated in the minimum flow (dot-and-dash line) than vortex shedding flow meter certainly more leans on last position).

Then, if consider and the switching point (heavy line) shown in such Fig. 7 (b) and the corresponding thermal flowmeter of minimum flow (dot-and-dash line) of vortex shedding flow meter, then selected corresponding with this, the maximum flow of thermal flowmeter must be chosen to be following flow: than the curve of the minimum flow (dot-and-dash line) of vortex shedding flow meter more by last and do not report to the leadship after accomplishing a task with switching point (heavy line), maximum flow shown in the curve (dotted line that the interval is narrow) of Fig. 6 (a).

But, in the thermal flowmeter of the maximum flow shown in the curve (narrow at interval dotted line) of Fig. 8 (a), though the flow measurement wide ranges following situation might occur but then: can't realize fully as the precision under multi-vortex flowmeter necessary tiny flow quantity territory and the low discharge territory.

Now, the heat type flow quantity of precision excellence is in respect of a lot.The present inventor thinks, as long as the selected wherein curve of maximum flow more approaches the thermal flowmeter of curve of the minimum flow (dot-and-dash line) of vortex shedding flow meter, just can provide a kind of multi-vortex flowmeter of excellence.But under the situation of having selected the good thermal flowmeter of precision, shown in Fig. 8 (b), the curve of maximum flow (big at interval dotted line) be reported to the leadship after accomplishing a task with switching point (heavy line) on the way therein, so consequently can produce the state that can't carry out instrumentation.

The present inventor thinks as follows.That is, switching point do not consider to flow in the pipe pressure this be the essential factor that can not use high-precision thermal flowmeter.The present inventor considers to provide a kind of high-precision thermal flowmeter and more excellent multi-vortex flowmeter of using.

In addition, the present inventor finds to have following possibility: even flow reduction then vortex differential pressure raising if the interior pressure of stream pipe rises, lower limit flow as the judgment standard when switching the function of flowmeter descends thus, and the present inventor considers that the result that will find is reflected in the multi-vortex flowmeter.The present inventor considers to use the function of this vortex shedding flow meter to measure flow as best one can in order to effectively utilize the advantage of vortex shedding flow meter.

Summary of the invention

The present invention proposes in view of above-mentioned situation, and its purpose is to provide a kind of mass rate is used as switching point and more excellent multi-vortex flowmeter.

In addition, the present invention proposes in view of above-mentioned situation, and purpose is to provide a kind of and re-recognizes switching point and can use the multi-vortex flowmeter of high-precision thermal flowmeter.

The multi-vortex flowmeter that mass rate is used as switching point of the present invention of technical scheme 1 record that proposes in order to solve above-mentioned problem, have with volume flow and carry out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use this two flowmeters according to the flow of the determined fluid that in stream, flows, it is characterized by, the switching point of above-mentioned two flowmeters determines according to above-mentioned mass rate, the switching point mass rate Qm of the scope big and littler than the maximum flow of above-mentioned thermal flowmeter than the minimum flow of above-mentioned vortex shedding flow meter by $\mathrm{Qm}=\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="A200780021899E00171.png,A200780021899E00191.png"\; state="\{\{state\}\}">K</figure-callout>}3*\sqrt{P}$ Determine (wherein, P: the pressure of stream (variable), K3: the definite constant of pressure during by the area of stream, vortex differential pressure, the constant relevant, the density of 1atm under 0 ℃ and 1atm) with the vortex differential pressure.

The multi-vortex flowmeter that mass rate is used as switching point of the present invention of technical scheme 2 records that propose in order to solve above-mentioned problem, have with volume flow and carry out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use this two flowmeters according to the flow of the determined fluid that in stream, flows, it is characterized by, the switching point of above-mentioned two flowmeters determines according to above-mentioned mass rate, the switching point mass rate Qm of the scope big and littler than the maximum flow of above-mentioned thermal flowmeter than the minimum flow of above-mentioned vortex shedding flow meter by $\mathrm{Qm}=\mathrm{<figure-callout\; id="4"\; label="K"\; filenames="A200780021899E00171.png"\; state="\{\{state\}\}">K</figure-callout>}4*\sqrt{(P/T)}$ Determine (wherein, P: the pressure of stream (variable), T: the absolute temperature of determined fluid (variable), K4: pressure during by the area of stream, vortex differential pressure, the constant relevant, density, the 1atm of 1atm under 0 ℃ and the definite constant of absolute temperature (273.15K) that is equivalent to 0 ℃) with the vortex differential pressure.

The multi-vortex flowmeter that volume flow is used as switching point of the present invention of technical scheme 3 records that propose in order to solve above-mentioned problem, have with volume flow and carry out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use this two flowmeters according to the flow of the determined fluid that in stream, flows, it is characterized by, the switching point of above-mentioned two flowmeters determines according to above-mentioned volume flow, the switching point volume flow Q of the scope big and littler than the maximum flow of above-mentioned thermal flowmeter than the minimum flow of above-mentioned vortex shedding flow meter by $Q=\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="A200780021899E00171.png"\; state="\{\{state\}\}">K</figure-callout>}1/\sqrt{P}$ Determine (wherein, P: the pressure of stream (variable), K1: the definite constant of pressure during by the area of stream, vortex differential pressure, the constant relevant, the density of 1atm under 0 ℃ and 1atm) with the vortex differential pressure.

The multi-vortex flowmeter that volume flow is used as switching point of the present invention of technical scheme 4 records that propose in order to solve above-mentioned problem, have with volume flow and carry out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use this two flowmeters according to the flow of the determined fluid that in stream, flows, it is characterized by, the switching point of above-mentioned two flowmeters is based on above-mentioned volume flow, the switching point volume flow Q of the scope big and littler than the maximum flow of above-mentioned thermal flowmeter than the minimum flow of above-mentioned vortex shedding flow meter by $Q=\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">K</figure-callout>}2/\sqrt{(P/T)}$ Determine (wherein, P: the pressure of stream (variable), T: the absolute temperature of determined fluid (variable), K2: pressure during by the area of stream, vortex differential pressure, the constant relevant, density, the 1atm of 1atm under 0 ℃ and the definite constant of absolute temperature (273.15K) that is equivalent to 0 ℃) with the vortex differential pressure.

The invention of being put down in writing according to the technical scheme 1 with such feature and technical scheme 2, by adding pressure factor or adding the pressure and temperature factor, carry out from the function of vortex shedding flow meter to the function of thermal flowmeter or from the switching of the function of thermal flowmeter to the function of vortex shedding flow meter.The present invention is conceived to following situation: the vortex differential pressure rose when pressure was high, and the susceptibility of vortex shedding flow meter rises and can measure up to low discharge as a result.By determining switching point in this wise, even pressure, temperature change also can carry out the switching of flowmeter with optimal (it is low to try one's best) flow (flow velocity) as the present invention.

In addition, the invention of being put down in writing according to the technical scheme 3 with such feature and technical scheme 4, by adding pressure factor or adding the pressure and temperature factor, can carry out from the function of vortex shedding flow meter to the function of thermal flowmeter or from the switching of the function of thermal flowmeter to the function of vortex shedding flow meter.According to the present invention, switching point changes corresponding to the pressure relevant with the minimum flow of vortex shedding flow meter (pressure and temperature).Therefore, can use the high precision thermal flowmeter, it has the curve with the approaching maximum flow of the curve of the minimum flow of vortex shedding flow meter.

Therefore, the invention according to technical scheme 1 and technical scheme 2 are put down in writing obtains following effect: can provide a kind of high-precision multi-vortex flowmeter that effectively utilizes the advantage of vortex shedding flow meter.Therefore, acquisition can provide the effect of the more excellent in the past vortex shedding flow meter of a kind of ratio.

In addition, according to the invention that technical scheme 3 and technical scheme 4 are put down in writing, re-recognize switching point, thereby can use high-precision thermal flowmeter.Therefore, acquisition can provide the effect of the more excellent in the past multi-vortex flowmeter of a kind of ratio.

Description of drawings

Fig. 1 is that expression is of the present invention with mass rate or the volume flow front view as an embodiment of the multi-vortex flowmeter of switching point.

Fig. 2 is the A-A line sectional view of Fig. 1.

Fig. 3 is the sectional view of flow converter.

Fig. 4 is the key diagram of switching point.

Fig. 5 is the key diagram of switching point.

Fig. 6 is the comparative descriptions figure of switching point.

Fig. 7 is the key diagram of switching point in the past.

Fig. 8 is the key diagram of switching point in the past.

Embodiment

Below, describe with reference to accompanying drawing.Fig. 1 is that expression is of the present invention with the front view of mass rate as an embodiment of the multi-vortex flowmeter of switching point.In addition, Fig. 2 is the A-A line sectional view of Fig. 1, and Fig. 3 is the sectional view of flow converter.And then Fig. 4 is the key diagram of switching point, and Fig. 5 is the comparative descriptions figure of switching point, and Fig. 6 is the key diagram of switching point.

In Fig. 1 and Fig. 2, Reference numeral 1 expression multi-vortex flowmeter of the present invention.This multi-vortex flowmeter 1 constitutes the function that has vortex shedding flow meter concurrently and the function of thermal flowmeter.In addition, multi-vortex flowmeter 1 constitutes as described below, determines the switching point of two flowmeters and switches the function of flowmeter based on this switching point of determining.Multi-vortex flowmeter 1 constitutes to have: whirlpool formula testing agency 7 has and measures with pipe arrangement 2, pressure gauge 3 being installed, being measured pipe 4, vortex generation body 5 and vortex detection device 6; Hot type testing agency 10 has temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9; Flow converter 11 is based on the flow velocity or the flow that calculate determined fluid (omitting diagram) from the output signal of whirlpool formula testing agency 7 and hot type testing agency 10.Below, at first illustrate that referring to figs. 1 through Fig. 3 each constitutes, and then illustrates the switching point of two flowmeters.

Measure with pipe arrangement 2 is installed, loading and unloading are installed in the centre (be not limited to the centre of stream pipe 12, also can be installed in the end) of stream pipe 12 freely, and the portion within it of forming is formed with the tectosome that for example illustrates such tubular of stream 13.Measuring, be formed with joint respectively with the two ends that pipe arrangement 2 is installed.In the outside of such mensuration, by suitable mode firm discharge transducer 11 with installation pipe arrangement 2.Be formed on the stream of measuring with installing in the pipe arrangement 2 13 and form the cross section circle.In this stream 13, determined fluid flows to the direction of arrow.

In the centre of stream 13, dispose and measure pipe 4, temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9.In addition, measure the upstream side of pipe 4 grades and near mensuration pipe 4, be formed with pressure instrumentation portion 14 (configuration is an example) at these.At these pressure instrumentation portion 14 places, in the state setting pressure 3 that is contained.Pressure instrumentation portion 14 has part of taking in pressure gauge 3 and the part that imports the part of the determined fluid that flows in stream 13.Pressure gauge 3 is used for the pressure of the determined fluid that instrumentation flows at stream 13, uses known pressure gauge (but for can the pressure gauge corresponding with flow converter 11) at this.Pressure gauge 3 is to install with flow converter 11 incorporate modes.Pressure gauge 3, on than vortex detection portion 6, temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9 position that slightly upstream side is left, integrated with flow converter 11.

It is tetragonal tubular (shape is an example) that mensuration pipe 4 forms tube section.Measure pipe 4 and form the direction of arrow extension of flowing along determined fluid.Be provided with vortex generation body 5 and the following compression plate 15 that is positioned at the downstream of this vortex generation body 5 at the part place that determined fluid flowed that measures pipe 4.The temperature sensor maintaining part 16 (be one in the present embodiment, but be not limited to this) that the top that keeps temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9 is arranged in the outer setting of measuring pipe 4.Measuring pipe 4 is fixed on the vortex detection device 6 via linking tube portion 17.In the present embodiment, link the vortex detection device 6 of measuring pipe 4 and be installed as with respect to measuring with pipe arrangement 2 loading and unloading being installed freely.

Vortex generation body 5 is the parts that are used for making in the inside of measuring pipe 4 the vortex generation, to set its shape with the mobile opposed mode of determined fluid.Vortex generation body 5 in the present embodiment, forms the triangular prism shape and (is shaped as an example.In No. 2869054 communique of special permission of patent documentation 1, disclose several examples).Vortex generation body 5 is arranged on the peristome office of the side that determined fluid flowed into of measuring pipe 4.Vortex generation body 5 is set to be positioned at the opening portion central authorities that measure pipe 4.

At this, the vortex that takes place by vortex generation body 5 is described.Vortex is to change the vortex that peel off position greatly from amount of exercise, it is to utilize the determined fluid that flows into the above-mentioned opening portion of measuring pipe 4 to produce along flowing of flowing of vortex generation body 5 that this amount of exercise changes big position, when in the cross section of vortex generation body 5 being the such triangle of present embodiment, making triangular ridges portion is pick-up point.Peel off the vortex of outflow from vortex generation body 5,, alternatively produce alternately according to Kaman's stable vortex condition, forms on one side between the vortex that keeps certain apart from and the vortex column pitch from vortex be listed as and flow out.Distance between vortex can be the flow velocity of eddy frequency and the time per unit that calculates based on the flow of being obtained by the fluid of the benchmark container that flows into basis box for example etc. in given time and trying to achieve by the quantity of the vortex that produces at time per unit.

Temperature sensor maintaining part 16 forms in the mode of stretching out to horizontal direction from the lower wall of measuring pipe 4, if in other words, forms in the mode of stretching out respectively from the two side of measuring pipe 4.Temperature sensor maintaining part 16 is not particularly limited, but forms the triangle of overlooking that is shaped as.Temperature sensor maintaining part 16 forms just like the such shape of fin is arranged in measuring pipe 4.Each top of temperature-sensitive sensor 8, heating temperature-sensitive sensor 9 is inserted in such temperature sensor maintaining part 16 as the crow flies.

Vortex detection device 6 is the sensors that are used for vortex detection, is subjected to pressure sensor in this use.Vortex detection device 6 has the compression plate (sensor compression plate) 15 that is configured in the downstream of measuring the vortex generation body 5 in the pipe 4 and is arranged on vortex detection device 6 pressure inside detecting element plates, utilizes the pressure detecting element plate to detect the fluctuation pressure (alternative pressure) that is caused by the Kaman's vortex that utilizes vortex generation body 5 to produce via compression plate 15.Vortex detection device 6 is in the present embodiment to install with flow converter 11 incorporate modes.

Vortex detection mechanism 7 is provided with in order to try to achieve determined flow rate of fluid mobile in measuring with installation pipe arrangement 2 or flow.Determined flow rate of fluid that will flow in measuring pipe 4 or flow calculate as measuring with part flow velocity that pipe arrangement 2 is installed or partial discharge, thereby try to achieve determined flow rate of fluid or the flow that flows in the pipe arrangement 2 with installing measuring.This is based on following reason: even be not to measuring with the integral body of the tube section that pipe arrangement 2 is installed but measure for its part, if mobilely be uniformly then can infer whole flow.That is, in straight tube, flow by rectification flow rate of fluid distribute, be provided as the function of Reynolds number, so can will be scaled and measure from measuring flow velocity with the position of certain distance of central part that pipe arrangement 2 is installed with the interior mean flow rate of pipe arrangement 2 is installed.

The temperature-sensitive sensor 8 and the heating temperature-sensitive sensor 9 that constitute hot type testing agency 10 all adopt technique known.And in the explanation of this omission to concrete structure.The temperature-sensitive sensor 8 of present embodiment is bar-shaped temperature sensor, is that bar-shaped heating temperature-sensitive sensor 9 is the flow sensors (well heater) with function of temperature sensor and heating sensor equally.Temperature-sensitive sensor 8 and heating sensor 9 in the present embodiment, to install with flow converter 11 incorporate modes.

Temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9 reach to be measured with in the stream 13 that pipe arrangement 2 is installed, and the top part is kept by temperature sensor maintaining part 16.Each temperature-sensitive of temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9 partly be configured in measure pipe 4 near.Temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9, (configuration is an example to be set to horizontal row with 6 arrangements of vortex detection device.As long as be configured to not influence vortex detection, then other situations also can).In addition, each temperature-sensitive part (for fear of effect from the outside to mensuration that use the heat that pipe arrangement 2 transmission are installed from) that also can prolong temperature-sensitive sensor 8 in the mode of further stretching out and heat temperature-sensitive sensor 9 to the central authorities of flow 13 from temperature sensor maintaining part 16.

Flow converter 11 has transducer shell 18.In the inside of this transducer shell 18, be provided with the amplification plate 19 of formation with microcomputer etc.Being connected with each lead of conveyer line 20, temperature-sensitive sensor 8 and the heating temperature-sensitive sensor 9 of pressure gauge 3, the conveyer line 21 of vortex detection device 6 on amplifying plate 19 (changes the configuration of temperature-sensitive sensor 8 among Fig. 3 and heating temperature-sensitive sensor 9 for convenience and illustrates.In fact be configured on the position that has rotated 90 °.Dispose in the mode of arranging along the paper right angle orientation of Fig. 3) with the conveyer line 21 of vortex detection device 6.

Temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9 and conveyer line 20 and 21 are introduced into the inside of transducer shell 18.Temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9 and conveyer line 20 and 21 are introduced into the inside of transducer shell 18 and do not expose to the outside.Temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9, pressure gauge 3, vortex detection device 6, amplification plate 19 have the function as flow measurement portion and flow operational part.

At the opening portion of transducer shell 18, under the state of encapsulant (symbol omission), the transducer dome 24 with panel 22 and display board 23 is being installed.On a sidewall of transducer shell 18, be connected with and transmit cable 25.

In above-mentioned formation and structure, multi-vortex flowmeter 1 of the present invention is according to the flow state of the determined fluid that flows in measuring with the stream 13 that pipe arrangement 2 is installed, promptly, separately use the function of vortex shedding flow meter and the function of thermal flowmeter based on following switching point.Particularly, in tiny flow quantity territory or low discharge territory, utilize the function of thermal flowmeter to carry out instrumentation, in the high flow capacity territory, utilize the function of vortex shedding flow meter to carry out instrumentation (carrying out instrumentation by the function of vortex shedding flow meter as best one can).

Multi-vortex flowmeter 1 of the present invention, low discharge territory instrumentation in the high flow capacity territory instrumentation in the function of thermal flowmeter and the function of vortex shedding flow meter has to a certain degree overlapping, in this overlapping scope, determine switching point, and switch (switching point describes in bottom) by flow switch 11 based on the switching point of determining.

At first, the effect when instrumentation tiny flow quantity territory or low discharge territory are described, the effect when promptly carrying out instrumentation by the function of thermal flowmeter.Heating temperature-sensitive sensor 9 carries out flow measurement based on the temperature that is detected by temperature-sensitive sensor 8.Promptly, in the flow measurement portion and flow operational part in flow converter 11, heating heating temperature-sensitive sensor 9 (electric current is flowed), so that make the temperature difference of temperature-sensitive sensor 8 and heating temperature-sensitive sensor 9 certain (for example+30 °), and by the current value calculated mass flow of this heating.The mass rate of calculating is presented on the display part on the top that is arranged on transducer lid 24 after being scaled set unit, and perhaps posting a letter by transmission cable 25 is presented on the not shown display device.

The calculating of the above-mentioned mass rate that remarks additionally, when the direction of arrow flowed, heating temperature-sensitive sensor 9 was cooled by determined fluid at determined fluid (omitting diagram).In order to be controlled to be with the temperature difference of temperature-sensitive sensor 8 necessarily, electric current is flowed on heating temperature-sensitive sensor 9.At this moment, known electric current and the mass rate that flows on heating temperature-sensitive sensor 9 is proportional, thus the calculated mass flow.

Then, effect when carrying out instrumentation by the function of vortex shedding flow meter is described.Detect fluctuation pressure (alternative pressure) based on the Kaman's vortex that produces by vortex generation body 5 at compression plate 15 and pressure detecting element plate place.And, determined flow rate of fluid that will be flowed in measuring pipe 4 by the detected value in the vortex detection device 6 or flow calculate as measuring with the part flow velocity that pipe arrangement 2 is installed or partial discharge, and calculate mobile determined flow rate of fluid or flow (volume flow) in measuring with installation pipe arrangement 2.Flow velocity that calculates or flow are presented on the display part on the top that is arranged on transducer dome 24 after being scaled set unit, and perhaps posting a letter by transmission cable 25 is presented on the not shown display device.

Switching about the function of the flowmeter that in flow converter 11, carries out, measured value from pressure gauge 3 is taken into to flow converter 11, add the factor of this measured value that is taken into and determine switching point, carry out on this basis from the function of thermal flowmeter to the function of vortex shedding flow meter or from the switching of the function of vortex shedding flow meter to the function of thermal flowmeter.

Switching point is described.

Vortex differential pressure Δ P is a relation as follows.

ΔP＝K*ρ*V ²

If this formula of distortion then becomes

V ²＝ΔP/(K*ρ)…(1)

V: flow velocity

Δ P: vortex differential pressure

ρ: density

K: constant.

The calculating 1 of＜switching point 〉

Switch (only with the situation of pressure) with mass rate as variable.

Mass rate Qm is following relation

Qm＝π*R ²*V*ρ…(2)

Qm: mass rate

R: the radius of stream 13,

Density p is

ρ＝ρ0*P/P0…(3)

ρ 0: in the density of 0 ℃ of following 1atm

P: absolute pressure [Mpaabs]

The pressure ≈ 0.10133[Mpaabs of P0:1atm]

Relation.

If (2) formula substitution to (1) formula, is then become

{Qm/(π*R ²*ρ)} ²＝ΔP/(K*ρ)。

If left side arrangement for Qm, is then become

$\mathrm{Qm}=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\mathrm{\&rho;}*\sqrt{\{\mathrm{\&Delta;P}/(K*\mathrm{\&rho;})\}}.$

If this formula of rewriting then becomes

$\mathrm{Qm}=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}*\mathrm{\&rho;}/K)}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right).$

If (3) formula substitution to (4) formula, is then become

$\mathrm{Qm}=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}*\mathrm{\&rho;}0*P/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0/K)}.$

And if then put in order, then become

$\mathrm{Qm}=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}*\mathrm{\&rho;}0/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0/K)}*\sqrt{P}\&CenterDot;\&CenterDot;\&CenterDot;\left(5\right).$

At this, if

$\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="A200780021899E00171.png,A200780021899E00191.png"\; state="\{\{state\}\}">K</figure-callout>}3=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}*\mathrm{\&rho;}0/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0/K)},$ Then (5) formula becomes

$\mathrm{Qm}=\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="A200780021899E00171.png,A200780021899E00191.png"\; state="\{\{state\}\}">K</figure-callout>}3*\sqrt{P}\&CenterDot;\&CenterDot;\&CenterDot;\left(6\right),$ This function becomes switching point (switching point mass rate Qm).

The calculating 2 of＜switching point 〉

Switch (with the situation of Pressure/Temperature) with mass rate as variable.

Mass rate Qm becomes following relation as mentioned above

$\mathrm{Qm}=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}*\mathrm{\&rho;}/K)}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right).$

Density p is following relation

ρ＝ρ0*P/P0*T0/T…(7)

T: absolute temperature [K]

T0: be equivalent to 0 ℃ absolute temperature ≈ 273.15[K].

If (7) formula substitution to (4) formula, is then become

$\mathrm{Qm}=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}*\mathrm{\&rho;}0*P/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0*\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">T</figure-callout>}0/T/K)}.$

And if then put in order, then become

$\mathrm{Qm}=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}*\mathrm{\&rho;}0/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0*\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">T</figure-callout>}0/K)}*\sqrt{(P/T)}\&CenterDot;\&CenterDot;\&CenterDot;\left(8\right).$

At this, if

$\mathrm{<figure-callout\; id="4"\; label="K"\; filenames="A200780021899E00171.png"\; state="\{\{state\}\}">K</figure-callout>}4=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}*\mathrm{\&rho;}0/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0*\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">T</figure-callout>}0/K)},$ Then (8) formula becomes

$\mathrm{Qm}=\mathrm{<figure-callout\; id="4"\; label="K"\; filenames="A200780021899E00171.png"\; state="\{\{state\}\}">K</figure-callout>}4*\sqrt{(P/T)}\&CenterDot;\&CenterDot;\&CenterDot;\left(9\right),$ This function becomes switching point (switching point mass rate Qm).

Among Fig. 4, with the longitudinal axis be mass rate [NL/min] (for convenience, with the expression of the unit (reference value of temperature/pressure is respectively 0 ℃, 1atm) of common flow), be in the chart of pressure [Mpaabs] with the transverse axis, the curve that rises on the right side), the minimum flow of vortex shedding flow meter (dot-and-dash line: the curve that rises on the right side), each line of the maximum flow (dotted line: with the straight line of transverse axis) of thermal flowmeter figure is shown with switching point (heavy line:.Switching point shown in Figure 4 (heavy line), minimum flow (dot-and-dash line) than vortex shedding flow meter is big, littler than the maximum flow (dotted line) of hot type flowmeter, according to the present invention, according to the calculating of above-mentioned switching point, with near the minimum flow (dot-and-dash line) of vortex shedding flow meter and the mode of being close to minimum flow (dot-and-dash line) determine switching point (heavy line).Therefore, by such switching point (heavy line), as can be known, can use the function of vortex shedding flow meter as best one can in the present invention and measure flow from chart.

In addition, if on one side compare and describe on one side with reference to Fig. 5, then in the chart of Fig. 5, switching point (heavy line) is fixing.Switching point (heavy line) need be bigger and littler than the maximum flow (dotted line) of hot type flowmeter than the minimum flow (dot-and-dash line) of vortex flow, so when fixing switching point (heavy line), its with near the maximum flow (dotted line) of thermal flowmeter and the mode of being close to maximum flow (dotted line) determine as the crow flies.Therefore, even can also must measure by the scope that vortex shedding flow meter is measured by thermal flowmeter.General thermal flowmeter is known in the precision aspect than vortex shedding flow meter difference, so when fixing switching point (heavy line), the influence of precision aspect is not little.In the present invention, can solve this point.

More than, as describing,, can provide a kind of high-precision multi-vortex flowmeter 1 of giving full play to the advantage of vortex shedding flow meter according to the present invention referring to figs. 1 through Fig. 5.In other words, can provide a kind of ratio more excellent in the past multi-vortex flowmeter 1.

The vortex differential pressure rose when pressure was high, the result, and the susceptibility of vortex shedding flow meter rises.Therefore,, perhaps add the factor of pressure and temperature, just can carry out mensuration up to low discharge if add the factor of pressure.At this moment, switching point of the present invention becomes useful.By determining switching point in this wise, even pressure, temperature change also can carry out the switching of flowmeter according to the flow (flow velocity) of the most suitable (low as far as possible) as the present invention.

The calculating 3 of＜switching point 〉

Switch (only with the situation of pressure) with volume flow as variable.

Volume flow Q is following relation

Q＝π*R ²*V…(10)

Q: volume flow

R: the radius of stream 13.

And density p becomes

ρ＝ρ0*P/P0…(11)

The density of ρ 0:0 ℃ following 1atm

P: absolute pressure [Mpaabs]

The pressure ≈ 1.10133[Mpaabs of P0:1atm]

If (10) formula substitution to (1) formula, is then become

{Q/(π*R ²)} ²＝ΔP/(K*ρ)。

If left side arrangement for Q, is then become

$Q=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{\{\mathrm{\&Delta;P}/(K*\mathrm{\&rho;})\}}\&CenterDot;\&CenterDot;\&CenterDot;\left(12\right).$

If (11) formula substitution to (12) formula, is then become

$Q=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{\{\mathrm{\&Delta;P}/(K*\mathrm{\&rho;}0*P/P0)\}}.$

And if then put in order, then become

$Q=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}/K/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0*P0)}/\sqrt{P}\&CenterDot;\&CenterDot;\&CenterDot;\left(13\right).$

At this, if

$\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="A200780021899E00171.png"\; state="\{\{state\}\}">K</figure-callout>}1=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}/K/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0*P0)},$ Then (13) formula becomes

$Q=\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="A200780021899E00171.png"\; state="\{\{state\}\}">K</figure-callout>}1/\sqrt{P},$ This function becomes switching point (switching point volume flow Q).

The calculating 4 of＜switching point 〉

Switch (with the situation of Pressure/Temperature) with volume flow as variable.

Volume flow Q becomes following relation as mentioned above

$Q=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{\{\mathrm{\&Delta;P}/(K*\mathrm{\&rho;})\}}\&CenterDot;\&CenterDot;\&CenterDot;\left(12\right).$

And density p becomes following relation

ρ＝ρ0*P/P0*T0/T…(14)

T: absolute temperature [K]

T0: be equivalent to 0 ℃ absolute temperature ≈ 273.15[K].

If (14) formula substitution to (12) formula, is then become

$Q=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{\{\mathrm{\&Delta;P}/(K*\mathrm{\&rho;}0*P/\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0*\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">T</figure-callout>}0/T)\}}.$

And if then put in order, then become

$Q=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}/K/\mathrm{\&rho;}0*\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0/T0)}/\sqrt{(P/T)}\&CenterDot;\&CenterDot;\&CenterDot;\left(15\right).$

At this, if

$\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">K</figure-callout>}2=\mathrm{\&pi;}*{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">R</figure-callout>}}^2*\sqrt{(\mathrm{\&Delta;P}/K/\mathrm{\&rho;}0*\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="A200780021899E00211.png,A200780021899E00231.png"\; state="\{\{state\}\}">P</figure-callout>}0/T0)},$ Then (15) formula becomes

$Q=\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="A200780021899E00171.png,A200780021899E00181.png"\; state="\{\{state\}\}">K</figure-callout>}2/\sqrt{(P/T)},$ This function becomes switching point (switching point volume flow Q).

Among Fig. 6, the curve that very smooth-going right side descends), the minimum flow of vortex shedding flow meter (dot-and-dash line: the curve that very smooth-going right side descends), the maximum flow (dotted line: each line curve that the right side descends) of thermal flowmeter be volume flow [L/min] with the longitudinal axis, be in the chart of pressure [Mpaabs] that figure is shown with switching point (heavy line: with the transverse axis.Switching point shown in Figure 4 (heavy line), minimum flow (dot-and-dash line) than vortex shedding flow meter is big, littler than the maximum flow (dotted line) of hot type flowmeter, according to the present invention, if by the calculating of above-mentioned switching point, then with near the minimum flow (dot-and-dash line) of vortex shedding flow meter and the mode of being close to minimum flow (dot-and-dash line) determine switching point (heavy line).Therefore, by such switching point (heavy line), as can be known, in the present invention, can use the function of vortex shedding flow meter as best one can and measure flow from chart.In addition, the maximum flow of thermal flowmeter (dotted line) minimum flow (dot-and-dash line) that is close to vortex shedding flow meter compared with the past is so can use high-precision thermal flowmeter.

More than, as describing, according to the present invention referring to figs. 1 through Fig. 3 and Fig. 6, carry out re-recognizing of switching point, thereby can use than the good thermal flowmeter of precision in the past, the result can provide a kind of more excellent multi-vortex flowmeter 1 compared with the past.

According to the present invention, even the Pressure/Temperature change also can be carried out the switching of optimal flowmeter.

Outside, in the scope that does not change purport of the present invention, the present invention can have various change embodiments certainly.

Claims (4)

1. multi-vortex flowmeter, mass rate as switching point, is had with volume flow and carries out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use this two flowmeters according to the flow of the determined fluid that in stream, flows, it is characterized by

The switching point of above-mentioned two flowmeters determines according to above-mentioned mass rate, the switching point mass rate Qm of the scope big and littler than the maximum flow of above-mentioned thermal flowmeter than the minimum flow of above-mentioned vortex shedding flow meter by $\mathrm{Qm}=K3*\sqrt{P}$ Determine (wherein, P: the pressure of stream (variable), K3: the definite constant of pressure during by the area of stream, vortex differential pressure, the constant relevant, the density of 1atm under 0 ℃ and 1atm) with the vortex differential pressure.

2. multi-vortex flowmeter, mass rate as switching point, is had with volume flow and carries out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use this two flowmeters according to the flow of the determined fluid that in stream, flows, it is characterized by

The switching point of above-mentioned two flowmeters determines according to above-mentioned mass rate, the switching point mass rate Qm of the scope big and littler than the maximum flow of above-mentioned thermal flowmeter than the minimum flow of above-mentioned vortex shedding flow meter by $\mathrm{Qm}=K4*\sqrt{(P/T)}$ Determine (wherein, P: the pressure of stream (variable), T: the absolute temperature of determined fluid (variable), K4: pressure during by the area of stream, vortex differential pressure, the constant relevant, density, the 1atm of 1atm under 0 ℃ and the definite constant of absolute temperature (273.15K) that is equivalent to 0 ℃) with the vortex differential pressure.

3. multi-vortex flowmeter, mass rate as switching point, is had with volume flow and carries out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use this two flowmeters according to the flow of the determined fluid that in stream, flows, it is characterized by

The switching point of above-mentioned two flowmeters determines according to above-mentioned mass rate, the switching point volume flow Q of the scope big and littler than the maximum flow of above-mentioned thermal flowmeter than the minimum flow of above-mentioned vortex shedding flow meter by $Q=K1/\sqrt{P}$ Determine (wherein, P: the pressure of stream (variable), K1: the definite constant of pressure during by the area of stream, vortex differential pressure, the constant relevant, the density of 1atm under 0 ℃ and 1atm) with the vortex differential pressure.

4. multi-vortex flowmeter, mass rate as switching point, is had with volume flow and carries out the vortex shedding flow meter of instrumentation and carry out the thermal flowmeter of instrumentation with mass rate, separately use this two flowmeters according to the flow of the determined fluid that in stream, flows, it is characterized by

The switching point of above-mentioned two flowmeters determines according to above-mentioned mass rate, the switching point volume flow Q of the scope big and littler than the maximum flow of above-mentioned thermal flowmeter than the minimum flow of above-mentioned vortex shedding flow meter by $Q=K2/\sqrt{(P/T)}$ Determine (wherein, P: the pressure of stream (variable), T: the absolute temperature of determined fluid (variable), K2: pressure during by the area of stream, vortex differential pressure, the constant relevant, density, the 1atm of 1atm under 0 ℃ and the definite constant of absolute temperature (273.15K) that is equivalent to 0 ℃) with the vortex differential pressure.

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