CN105241789A - Non-Newtonian fluid density on-line measuring equipment and method thereof - Google Patents

Abstract

The invention discloses non-Newtonian fluid density on-line measuring equipment and a method thereof. The non-Newtonian fluid density on-line measuring equipment comprises a fluid inlet, a Venturi fluid acceleration current-limiting device, a turbulence tube, an equal settlement tube, a lamina flow measuring tube and a fluid outlet. By a capacitive or micro-differential pressure transmitter, differential pressure with a certain altitude difference is measured at the lamina flow measuring tube; a differential pressure signal is sent to a programmable logic controller PLC or a single-chip microcomputer or a computer, and a fluid density value is calculated. Available fluids contain solid-liquid two-phase flow, solid-liquid two-phase flow, gas (vapor)-liquid two-phase flow and gas-liquid-solid three-phase flow. The equipment is also suitable for fluids such as solutions, colloid, blood and the like. According to the invention, accurate and reliable measurement can be realized, and the key is that on-line continuous measurement can be realized.

Description

Non-Newtonian fluid density on-line measurement device and method

Technical field

The present invention relates to a kind of utilize fluid the density of flow characteristics test material or the device of proportion or method, be specifically related to a kind of non-Newtonian fluid density on-line measurement device and method.

Background technology

Density is one of characteristic of material, is the content that all kinds of technological process of a lot of industrial circle must be monitored.The method of current online density measuring is mainly Coriolis force method.Coriolis force method Main Basis Newton second law: power=quality × acceleration (F=ma), when the particle that quality is m moves in pipeline P axle being done to angular velocity omega rotation with speed V, particle is subject to acceleration and the power thereof of two components:

(1) normal acceleration, i.e. centripetal acceleration α r, its value equals 2 ω r, towards P axle;

(2) cut angle speed alpha t, i.e. Coriolis acceleration, and its value equals 2 ω V, and direction is vertical with α r.Due to compound motion, the α t direction of particle acts on Coriolis force Fc=2 ω Vm, pipeline an opposite force-Fc=-2 ω Vm to particle effect.

Its advantage is as follows:

1. direct measurement quality flow, has very high measuring accuracy;

2. measure liquid scope extensive, comprise the various liquid of high viscosity liquid, the slurries containing solid content, the liquid containing minimum gas, have the mesohigh gas of sufficient density;

3. the vibration of measuring tube is little, can regard as non-moving part, measures without hindrance and movable part in pipeline;

4. pair reply meet stream velocity flow profile insensitive, without the requirement of upstream and downstream straight length;

5. measured value fluid viscosity is insensitive, and the impact that fluid density change must be worth measured value is small;

6. can do measuring multiple parameters, as the density measurement same period, and derive the concentration measured in solution contained by solute thus.

But also there is following deficiency:

1. zero point, instability formed zero point drift, affected its degree of accuracy;

2. can not measure low-density medium and low-pressure gas; In liquid, air content exceedes a certain restriction (different by model) and can show work and affect measured value;

3. vibration interference is comparatively responsive to external world, and thus the fixing requirement of flow sensor installation is higher;

4. can not be used for comparatively Large Diameter Pipeline, still be confined to below 200mm at present;

5. the corrosion of measuring tube inner wall abrasion or deposition fouling can affect measuring accuracy;

6. the pressure loss, weight, volume are comparatively large, expensive.

Visible, design a kind of can measurement the on-line continuous of non-newtonian flow volume density, measure accurately high and measure reliable measurement mechanism and method has become technical matters urgently to be resolved hurrily.

Summary of the invention

Goal of the invention: in order to overcome the deficiencies in the prior art, the invention provides a kind of non-Newtonian fluid density on-line measurement device and method.

Technical scheme: for solving the problems of the technologies described above, non-Newtonian fluid density on-line measurement device provided by the invention, there is vertical housing, described housing is provided with fluid intake pipe and fluid discharge outlet, described housing is made up of uniform settling pipe and laminar flow measuring tube, in described housing, turbulent stirring pipe is installed, the bottom of described turbulent stirring pipe is connected with fluid intake pipe with acceleration current-limiting apparatus successively, described fluid discharge outlet is installed on the bottom of housing, the sidewall of described laminar flow measuring tube is provided with the first differential pressure be arranged above and below and surveys mouth and the second differential pressure survey mouth, described first differential pressure surveys mouth and the second differential pressure survey mouth is connected to differential pressure transmitter.

Particularly, described acceleration current-limiting apparatus is Venturi tube.

Particularly, described first differential pressure is surveyed on mouth and the second differential pressure survey mouth and is all connected to barotropic equilibrium blow valve port by threeway, barotropic equilibrium blow valve port connects pressurized air, once purges in operation every 4 hours, and the second differential pressure can be avoided to survey mouth and the first differential pressure survey mouth blocking or pollute.

Particularly, the dimensional parameters of described housing, the first differential pressure survey mouth and the second differential pressure survey mouth meets

$\frac{1}{2}{{\mathrm{\ζv}}_2}^2\≤1\%g(h_2-h_1)$

H in formula ₁first differential pressure surveys open height, h ₂second differential pressure surveys open height, v ₂second differential pressure surveys mouth fluid velocity, g acceleration of gravity, ζ coefficient of shock resistance.The size design of device makes v ₁and v ₂absolute velocity enough little, can measuring accuracy be improved.

Particularly, described laminar flow measuring tube is even straight length, and internal diameter mismachining tolerance is not more than per mille caliber, makes caliber smooth enough, guarantees v ₁=v ₂.

Particularly, described fluid discharge outlet leads directly to air, guarantees fluid free setting.

The present invention provides the method for application said apparatus on-line measurement non-newtonian flow volume density simultaneously, comprises the following steps:

Step 1, fluid enters from fluid intake pipe

Step 2, fluid accelerates current-limiting apparatus place at venturi fluid and is accelerated, and is limited in certain limit according to pressure fluid inlet inlet flow rate simultaneously;

Step 3, is fully uniformly mixed under venturi fluid accelerates current-limiting apparatus high velocity effect at turbulent stirring pipe place fluid, and pressure reduces simultaneously, and speed reduces;

Step 4, at uniform settling, 4 place's fluid velocities change, and namely fluid velocity is down to 0 after rising, and start under gravity to move downward, speed flowing field is again uniform, uniform settling simultaneously;

Step 5, fluid is in laminar condition in laminar flow measuring tube 5; Differential pressure transmitter obtains the differential pressure signal that the first differential pressure surveys mouth and the second differential pressure survey mouth, based on formula bulk density, p in formula ₂second differential pressure surveys the static pressure of mouth; p ₁first differential pressure surveys the static pressure of mouth; v ₁first differential pressure surveys mouth fluid velocity; v ₂second differential pressure surveys mouth fluid velocity; ρ fluid density; G acceleration of gravity; ζ coefficient of shock resistance; h ₁first differential pressure surveys open height, h ₂second differential pressure surveys open height;

Step 6, final fluid is discharged through fluid discharge outlet.

Inventive principle: non-Newtonian fluid is equally applicable to meet Bernoulli Jacob's energy conservation equation:

$p_1+{\mathrm{\ρgh}}_1+\frac{1}{2}{{\mathrm{\ρv}}_1}^2=p_2+{\mathrm{\ρgh}}_2+\frac{1}{2}{{\mathrm{\ρv}}_2}^2+\frac{1}{2}{{\mathrm{\ζ\ρv}}_2}^2$ Formula 1

Shift onto and draw $\mathrm{\ρ}=\frac{(p_2-p_1)}{g(h_1-h_2)+\frac{1}{2}({v_1}^2-{v_2}^2)-\frac{1}{2}{{\mathrm{\ζv}}_2}^2}$ Formula 2

P in formula ₁: the static pressure of measuring point 1; v ₁measuring point 1 fluid velocity

P ₂: the static pressure of measuring point 2; v ₂measuring point 2 fluid velocity

ρ: fluid density; G: acceleration of gravity; ζ: coefficient of shock resistance

Had by the known error component that causes of formula 2:

Cause error component 1: the velocity contrast of measuring point 1 and side point 2, this error is eliminated by the machining precision improving the density measuring equipment of described non-Newtonian fluid.

Cause error component 2: beautiful power loss, measuring point 1 and measuring point 2 are straight length, ζ < 0.1; The v when the density measuring equipment design of described non-Newtonian fluid simultaneously ₁and v ₂absolute velocity enough little, make be only g (h ₂-h ₁) 1% to improve precision.

Cause error component 3: Δ p=p ₂-p ₁; This value is that differential pressure transmitter records numerical value, adopts high-precision differential pressure transmitter to improve measuring accuracy.

Cause error component 4: Δ h=h ₁-h ₂; The density measuring equipment inherent characteristic measuring point 1 of described non-Newtonian fluid and the difference in height of measuring point 2, standard flow is adopted after installation, such as air, water demarcate this difference in height, to eliminate this error component, in calculation procedure, be provided with temperature compensation to eliminate the impact of temperature on difference in height simultaneously.

Beneficial effect: the present invention adopts the density of elementary errors platen press indirect inspection fluid, by organizing the correction verification in flow field and standard flow to reduce error, measures accurately reliable, and achieves and measure the on-line continuous of non-newtonian flow volume density.

Except technical matters, the technical characteristic forming technical scheme and the advantage brought by the technical characteristic of these technical schemes that the present invention recited above solves, the advantage that the other technologies feature comprised in the other technologies problem that non-Newtonian fluid density on-line measurement device and method of the present invention can solve, technical scheme and these technical characteristics bring, will be described in more detail by reference to the accompanying drawings.

Accompanying drawing explanation

Fig. 1 is the structural representation of embodiments of the invention;

In figure: 1-fluid intake pipe; 2-venturi fluid accelerates current-limiting apparatus; 3-turbulent flow stirring pipe; 4-uniform settling pipe; 5-laminar flow measuring tube; 6-fluid discharge outlet; 7-second differential pressure surveys mouth; 8-first differential pressure surveys mouth; 9-second differential pressure conduit; 10-first differential pressure conduit; 11-differential pressure transmitter; 12-second differential pressure blow valve port; 13-first differential pressure blow valve port.

Embodiment

Embodiment: the structure of patent device as shown in Figure 1, select according to the operating characteristic of fluid by its material can be glass, organic glass, PP, teflon, stainless steel, alloy, graphite etc.The size of device designs according to the characteristic difference of fluid being measured.Key is that controlling fluid settled density inequality does not occur, the phenomenons such as Flow Field Distribution is uneven.Survey non-Newtonian fluid and entered by fluid intake pipe 1, accelerate current-limiting apparatus 2 place fluid at venturi fluid to be accelerated, be limited in certain limit according to pressure fluid inlet inlet flow rate simultaneously, fully be uniformly mixed under venturi fluid accelerates current-limiting apparatus 2 high velocity effect at turbulent stirring pipe 3 place fluid, pressure reduces simultaneously, and speed reduces; At uniform settling pipe 4 place, fluid velocity changes, that is: fluid velocity is down to 0 after rising, and start under gravity to move downward, speed flowing field is again uniform, uniform settling simultaneously; Fluid is in laminar condition in laminar flow measuring tube 5, and laminar flow measuring tube 5 is even straight length, and internal diameter mismachining tolerance is not more than per mille caliber, guarantees v ₁=v ₂, caliber smooth enough simultaneously, reduces the local resistance loss between the second differential pressure survey mouth 7 and the first differential pressure survey mouth 8 make be only g (h ₂-h ₁) 1% to improve precision.Final fluid is discharged through fluid discharge outlet 6, and fluid discharge outlet 6 leads directly to air, guarantees fluid free setting.Laminar flow measuring tube 5 carries out differential pressure measurement in interval, and differential pressure transmitter 11 interface is respectively the second differential pressure and surveys mouth 7 and the first differential pressure survey mouth 8.When initial start-up, pressurized air accesses the second differential pressure blow valve port 12 and the first differential pressure blow valve port 13 purges, and once purges in operation every 4 hours, avoids the second differential pressure to survey mouth 7 and the first differential pressure and surveys mouth 8 and block or pollute.Differential pressure transmitter 11 obtains the input computing machine of differential pressure signal or PLC or single-chip microcomputer and calculates.Its density calculation formula, based on formula 2, adds certain experience and the correction factor of standard flow simultaneously.

Below by reference to the accompanying drawings embodiments of the present invention are described in detail, but the present invention is not limited to described embodiment.For those of ordinary skill in the art, in the scope of principle of the present invention and technological thought, multiple change, amendment, replacement and distortion are carried out to these embodiments and still falls within the scope of protection of the present invention.

Claims (7)

1. a non-Newtonian fluid density on-line measurement device, there is vertical housing, described housing is provided with fluid intake pipe and fluid discharge outlet, it is characterized in that: described housing is made up of uniform settling pipe and laminar flow measuring tube, in described housing, turbulent stirring pipe is installed, the bottom of described turbulent stirring pipe is connected with fluid intake pipe with acceleration current-limiting apparatus successively, described fluid discharge outlet is installed on the bottom of housing, the sidewall of described laminar flow measuring tube is provided with the first differential pressure be arranged above and below and surveys mouth and the second differential pressure survey mouth, described first differential pressure surveys mouth and the second differential pressure survey mouth is connected to differential pressure transmitter.

2. non-Newtonian fluid density on-line measurement device according to claim 1, is characterized in that: described acceleration current-limiting apparatus is Venturi tube.

3. non-Newtonian fluid density on-line measurement device according to claim 1, is characterized in that: described first differential pressure is surveyed on mouth and the second differential pressure survey mouth and is all connected to barotropic equilibrium blow valve port by threeway.

4. non-Newtonian fluid density on-line measurement device according to claim 1, is characterized in that: the dimensional parameters that described housing, the first differential pressure survey mouth and the second differential pressure survey mouth meets

$\frac{1}{2}{{\mathrm{\&zeta;v}}_2}^2\&le;1\%g(h_2-h_1)$

H in formula ₁first differential pressure surveys open height, h ₂second differential pressure surveys open height, v ₂second differential pressure surveys mouth fluid velocity, g acceleration of gravity, ζ coefficient of shock resistance.

5. non-Newtonian fluid density on-line measurement device according to claim 1, is characterized in that: described laminar flow measuring tube is even straight length, and internal diameter mismachining tolerance is not more than per mille caliber.

6. non-Newtonian fluid density on-line measurement device according to claim 1, is characterized in that: described fluid discharge outlet leads directly to air.

7. apply a method for said apparatus on-line measurement non-newtonian flow volume density, it is characterized in that comprising the following steps:

Step 1, fluid enters from fluid intake pipe

Step 2, fluid accelerates current-limiting apparatus place at venturi fluid and is accelerated, and is limited in certain limit according to pressure fluid inlet inlet flow rate simultaneously;

Step 3, is fully uniformly mixed under venturi fluid accelerates current-limiting apparatus high velocity effect at turbulent stirring pipe place fluid, and pressure reduces simultaneously, and speed reduces;

Step 4, at uniform settling, 4 place's fluid velocities change, and namely fluid velocity is down to 0 after rising, and start under gravity to move downward, speed flowing field is again uniform, uniform settling simultaneously;

Step 5, fluid is in laminar condition in laminar flow measuring tube 5; Differential pressure transmitter obtains the differential pressure signal that the first differential pressure surveys mouth and the second differential pressure survey mouth, based on formula bulk density, p in formula ₂second differential pressure surveys the static pressure of mouth; p ₁first differential pressure surveys the static pressure of mouth; v ₁first differential pressure surveys mouth fluid velocity; v ₂second differential pressure surveys mouth fluid velocity; ρ fluid density; G acceleration of gravity; ζ coefficient of shock resistance; h ₁first differential pressure surveys open height, h ₂second differential pressure surveys open height;

Step 6, final fluid is discharged through fluid discharge outlet.