JPH0654287B2 - Non-newtonian measuring device in pipeline - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an apparatus for measuring non-newtonianity of a pipeline transport fluid.

[Conventional technology]

In the pipeline, it is a very important problem in operation to grasp the properties of the fluid inside the pipeline.

In recent years, it has become necessary for CWM to send high-concentration coal slurry such as COM through a pipeline for the purpose of reducing oil consumption. These highly viscous fluids exhibit non-Newtonian properties that do not follow Newtonian flow.

To measure the non-Newtonian property of such a non-Newtonian fluid, a part of the fluid is conventionally sampled from a pipeline, and a rheological measurement device such as a rotational viscometer is used to determine a flow curve that is the relationship between shear rate and shear stress This was done by the method of finding and determining non-Newtonianity in the form of this curve.
However, this kind of off-line measurement is not a problem if the rheological properties in the pipeline are always constant, but its properties depend on the passage of time and history such as high-concentration coal water slurry (CWM). When there is a possibility of change, the time from sampling to obtaining the measurement result becomes a problem. That is, it takes at least several tens of minutes from the sample collection to the determination, and at the time of the determination, the fluid to be measured in the pipeline has been transferred to several Km.
In pipeline operation, it is necessary to control the flow rate and pressure in accordance with changes in fluid properties, particularly changes in viscosity, and the above-mentioned off-line measurement cannot sufficiently meet this requirement.

On the other hand, as a method for online measuring the properties of a fluid in a pipeline, there is a method in which a rotary viscometer or a differential pressure viscometer is directly attached to the pipeline.

In this method using a rotary viscometer, a cylindrical or conical rotor is inserted inside a pipe, and this rotor is rotated at a constant rotational speed by a motor outside the pipe, and the rotational torque that acts on the rotor at that time is continuously measured. Is the way. Since this torque measurement value is proportional to the viscosity, the viscosity can be known from this torque value.

However, this method has problems that it is necessary to put a structure such as a rotor in the pipe of the pipeline, and it is necessary to correct the influence of the fluid flow in the pipe.

The method using a differential pressure type viscometer is to install a flowmeter and a differential pressure meter in the pipeline, measure the flow rate Q and the pressure loss value ΔP continuously, and measure the apparent viscosity at a certain flow rate value from Hagen-Poiseuille's law. Is the way to do it. In the case of this method, there is no drawback as in the case of using the rotational viscometer described above,
The apparent viscosity that is detected serves as a reference for knowing the tendency of the viscosity of the fluid to increase or decrease, but it is impossible to know the non-Newtonian property.

[Outline of Invention]

The present invention has been made to remedy the above-mentioned drawbacks of the prior art, and an object thereof is to provide a measuring device capable of measuring the non-Newtonian property of a fluid flowing in a pipeline on-line.

To this end, the present invention provides a different-diameter pipe section having at least three different pipe diameters formed in the middle of a pipeline, a differential pressure gauge for measuring a differential pressure between the different-diameter pipe sections, and different different-diameter sections. An apparatus for calculating a calculated differential pressure value of another different-diameter pipe section from a differential pressure value of one different-diameter tube section of the pipe section, and a calculated differential pressure value and an actually measured difference from the differential pressure gauge. The basic feature is to have a comparison device for comparing the pressure value.

Here, the types of non-Newtonian fluids will be described. FIG. 3 is called a flow curve, and the shear stress τ is plotted on the horizontal axis and the shear rate is plotted on the vertical axis.
In the flow in the pipe, it is generally expressed by the shear rate and the shear stress on the wall surface of the pipe, and these are defined by the following equation.

However, Q: flow rate R: inner radius ΔP: pressure loss l: differential pressure measurement section R and l are known, so τ can be determined by determining ΔP by the differential pressure gauge and Q by the flowmeter. In the case of Newtonian fluid, the relation of τ is expressed by Hagen-Poiseuille's equation as shown below.

The name and relationship of each curve shown are shown in the following formula.

Newtonian fluid Bingham fluid Power law fluid n> 1: Pseudoplastic fluid n <1: Dilatant fluid Power law fluid with yield value However, η: viscosity n: rheology index τ ₀ : yield response method, τ is obtained by a differential pressure meter and a flow meter, and η is calculated from the ratio.
Even if is obtained, the flow curve is uniquely obtained when it is known that it is a Newtonian fluid, but it is impossible to know the fluid property and the flow curve when the property of the fluid in the pipeline is unknown. .

Therefore, the present invention provides at least three different-diameter pipe portions in the pipeline, and measures τ at these three places,
By comparing this measured value with the calculated value assuming a Newtonian fluid, the non-Newtonian property is attempted.

〔Example〕

 Hereinafter, the present invention will be described in detail based on examples.

In FIG. 1, measuring pipes S, M, and L having a difference in inner diameter are provided in the middle of the pipeline main pipe X to form a diameter difference portion. Differential pressure gauges 1 _S , 1 _M and 1 _{L are} attached to the measuring tubes S, M and L respectively.
Is mounted and is configured to measure the differential pressure ΔP of each tube. The differential pressure gauge 1 may be a normal differential pressure gauge, or two differential pressure gauges may be combined to form a differential pressure gauge. Measuring tube S,
A resistor R is connected between M and L so as not to obstruct the flow of fluid. Alternatively, the entire measuring pipe may be formed in a tapered shape, and the gauges may be provided at three locations separated in the length direction to form the different diameter pipe portion.

The diameters of the measuring pipes S, M, and L are arbitrary as long as there is a difference in diameter, but in this embodiment, the inner radius R _M of the measuring pipe M is the same as the inner radius of the main pipe X, and the shear rate is the same as the main pipe. Match.

Note that one of the measuring tubes S, M, and L may be the main tube X. Further, in the case of using a taper pipe, various modes are possible such as providing one main pipe X with one differential pressure gauge and two taper pipes with two differential pressure gauges.

An arbitrary one output of the differential pressure gauge 1 is connected to the calculator 2. In this embodiment, a differential pressure gauge 1 _M mounted on a measuring pipe M having an intermediate inner diameter is connected to a calculator 2.

The arithmetic unit 2 is for calculating the value of the other measuring tube S, L on the basis of the output values from the differential pressure gauge 1 _M. At this time,
The calculation is performed assuming that the fluid flowing in the pipe is a Newtonian fluid. In this embodiment, two calculators 2 _L and 2 _S are prepared and the values in the tubes L and S are calculated respectively.

Now, differential pressure gauge 1 _S, 1 _M, 1 signal obtained by converting the output to a pressure loss gradient i per unit length from _L E _L, E _M, the E _S EαΔPατ) that, in the computing unit 2 _L, 2 _S enter the respective _{E M, E M × B L} 4, E M × B
Calculate _S ⁴ . here, However, R _M : inner diameter of the measuring pipe M R _S : inner diameter of the measuring pipe S _RL : inner diameter of the measuring pipe L These E _M B _L ⁴ and E _M B _S ⁴ assume that the fluid flowing through the pipe is a Newtonian fluid. , M, each derived from Hagen Poiseuille's formula
Is a value that takes into account the pipe diameter difference between S and L. These values E _M , E
By displaying each point of ^{_{M × B L 4, E M}} × B S 4 in FIG. 4 and the graph showing the ln-lnτ relationship of FIG. 5, the straight line representing the rheological index n = 1 of the Newtonian fluid Noru

The E _M × B _L ⁴ and E _M × B _S ⁴ are input to the differential amplifiers 3 _L and 3 _S , and the difference between the measured values from the differential pressure gauges 1 _L and 1 _S is amplified and output here. In the connection of the input terminals shown in the figure, the outputs ε _L and ε _S of the amplifiers 3 _L and 3 _S are expressed by the following equations.

ε _L = E _L -E _M × B _L ⁴ …… ε _S = E _M × B _S ⁴ -E _S …… The difference between ε _L and ε _S indicates the deviation from the Newtonian fluid in the measuring tubes S and L. It is a thing. Therefore, the non-Newtonianity of the fluid flowing in the pipe can be determined by knowing the magnitude and positive / negative of ε _L and ε _S.

How ε _L and ε _S change for each of the above-mentioned non-Newtonian fluids will be described. First, consider the case of a power law fluid. The exponent n of a power-law fluid is called a rheology index, and is one index indicating non-Newtonianity. When the relationship between the shear rate and the shear stress is represented on a logarithmic log graph, it can be represented by a straight line having an inclination corresponding to the index n as shown in FIGS. 4 and 5. In the figure, the Newtonian fluid (n = 1) and ε _S and ε _L are also shown together. ε _S and ε _L are expressed by the following equations, and since B _L and B _S are constants determined by the device, positive and negative values are taken according to the index n, and the index n
The deviation from the Newtonian fluid (ε _S = 0, ε _L = 0) can be detected.

Next, the case of Bingham fluid will be described. The relationship between the flow rate of the Bingham fluid and the pressure loss is expressed by the following equation called the Buckingham Reiner's equation, and the second and subsequent terms in Katsuko are non-Newtonian terms.

By omitting the minute term in the equation and expressing ε _S and ε _L of the Bingham fluid, the following equation can be expressed.

Since B _L and B _S are constants determined by the device, ε _L and ε _S take a value proportional to the yield value n, and the Newtonian fluid (τ ₀ = 0,
That is, a deviation from ε _L = ε _S = 0) can be detected.

The positive and negative relations of ε _L and ε _S of each fluid described above are summarized in the table below.

In the actual fluid in the pipeline, it is rather rare that it is the ideal Bingham fluid or power law fluid as described above, and it has a power law fluid with yield value that has both properties and / or has a complicated curve There are many cases. In this case, the combination of large and small rheology index n and the yield location tau _0, epsilon _L, the value of epsilon _S is not able to determine uniquely positive and negative, with any of the values, both epsilon _L and epsilon _S Does not become zero at the same time, and obviously a Newtonian fluid (ε
_L = ε _S = 0, and at the same time zero).

In the present embodiment, the outputs ε _L and ε _S described above are further input to the multiplication / division calculators 4 _L and 4 _S , where E _M is divided, and after an appropriate scaling constant is applied, the display 5 _L , 5 _S is displayed. The control signals for control are output from the computing units 4 _L and 4 _S separately from the display.

FIG. 2 shows another embodiment, in which an arithmetic processing unit 7 such as a microprocessor is used. Here, the outputs E _L , E _M , and E _S from the differential pressure gauge (not shown) are digitized by the A / D converter 6 and then processed by the arithmetic processing unit 7. This processing is the same as the processing by the constant calculator 2, the differential amplifier 3, and the multiplication / division calculator 4 in the embodiment of FIG.

〔The invention's effect〕

As described above, according to the measuring apparatus of the present invention, the non-Newtonian property of the fluid in the pipeline can be measured online, and the change in the property of the fluid can be sequentially known, so that the pipeline operation is efficiently performed. be able to.

[Brief description of drawings]

1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment, FIG. 3 is a flow curve diagram showing the properties of a Newtonian fluid and a non-Newtonian fluid, and FIG. FIG. 5 is a flow curve diagram for explaining the operation of the embodiment. 1 ... Differential pressure gauge, 2 ... Constant calculator, 3 ... Differential amplifier,
4 ... Multiplication / division arithmetic unit, 5 ... Display unit, 6 ... A / D converter, 7 ... Arithmetic processing unit.

Claims (1)

[Claims] 1. A different-diameter pipe portion having at least three different pipe diameters formed in the middle of a pipeline, a differential pressure gauge for measuring the differential pressure between the different-diameter pipe portions, and 1 for each different-diameter pipe portion. A device that calculates a calculated differential pressure value of another different diameter pipe portion assuming a Newtonian fluid from the differential pressure value of one different diameter pipe portion, and the calculated differential pressure value and the measured differential pressure value from the differential pressure gauge. A non-newtonian measuring device in a pipeline, comprising: a comparing device for comparing.