JPS59203931A - Correcting method of fluid thermometer - Google Patents

Abstract

PURPOSE:To correct exactly the responding delay of an indicating value to presume accurately a fluid temp. by varying a time constant of a fluid thermometer basing on the fluid flow velocity. CONSTITUTION:In correcting the responding delay by using Tf=Tc+taud/dt.Tc with respect to the indicating value Tc of the fluid thermometer 1, the correlation tau=f(Vf) between the time constant tau of the thermometer 1 and a flowing velocity Vf of the fluid 3 is obtained previously. The flow velocity Vf at the time of temp. measurement is measured to obtain the corresponding time constant tau' and the corrected value Tf=Tc+tau'd/dt.Tc is calculated. As the result, the responding delay at the indicating value Tc is corrected exactly, thus the fluid temp. can be presumed accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a correction force method for a fluid thermometer such as a thermocouple thermometer when measuring the temperature of a fluid such as top gas of a blast furnace.

For example, when measuring a gas, liquid, etc. with a thermocouple thermometer and trying to estimate the true fluid temperature, the biggest problem is the delay in temperature response. That is, when the fluid temperature suddenly changes by a certain amount, the thermocouple cannot immediately respond to this temperature change, and always follows with an inherent response delay.

The response delay between and is usually expressed as a time constant. The time constant is the time τ(
(See Figure 1).

Therefore, changes in the indicated value actually measured for each thermoelectric temperature do not always indicate a change in the true fluid temperature. Temperature cannot be estimated.

For this correction, a first-order lag model is usually used. In other words, the correction value for estimating the true fluid temperature is '
rf, m If the indicated value actually measured with the thermocouple thermometer is To% and the time constant of the thermocouple thermometer τ, then the minute is the Laplace operator. This is Tf = 'rc (1+τ
B) In the time domain, it is determined as 'rf=To+τ□To.

t In the past, τ in the above equation was treated as a preselected constant value, and the correction value Tf'e was calculated based on this value, thereby estimating the true fluid temperature.

However, in reality, this is not a constant value, but an amount that changes in relation to the flow velocity of the fluid. Therefore, a large error often inevitably occurs between the correction value Tf determined by the conventional example described above and the true fluid temperature.
In view of these actual circumstances, the present invention was developed with the aim of solving problems.
This was made to solve the problems of the conventional example described above, and the time constant of a fluid thermometer such as a thermocouple thermometer is not set to a constant value, but is changed depending on the flow velocity of the fluid. It is an object of the present invention to propose a correction force method for a fluid thermometer, which makes it possible to estimate the true fluid temperature more accurately by obtaining a correction value of the value. Let's explain based on an example.

First, its basic configuration will be explained.

The correction method for this fluid thermometer is based on the indicated value T actually measured by the fluid thermometer. For, Tf=To+τ−T.

This relates to the case where the true fluid temperature is estimated by correcting the response delay using the equation given by t. That is, first, the correlation τ=r(Vf) between the fluid flow velocity vf of the fluid thermometer and the time constant τ is determined in advance, and then the fluid flow velocity vf at the temperature sensing part of the fluid thermometer at the time of temperature measurement is calculated as the flow velocity. By measuring the total 2, the time constant τ' corresponding to the fluid flow velocity fVc is determined, and this time constant τ' is expressed as τ in the above formula.
Next, the details of the correction method for this fluid thermometer, such as a thermocouple thermometer, will be explained with reference to FIG. 2.

1 is a thermocouple thermometer, the temperature sensitive part of which is disposed in the fluid flow 3. Then, the thermocouple thermometer 1) outputs the indicated value Tc via the temperature converter 4.
. In order to perform the calculation of the above formula on the VC, the following processing is performed.

That is, the instruction value T0 is input to the differentiator 5 and the adder 7, respectively. By adding the instruction value T0 to the output of the differentiator, the correction value Tf is determined.

Now, in the present invention, the function generator 8 is provided with a correlation between the fluid flow velocity vf of the thermocouple thermometer 1 and the time constant τ=f(Vf
) (for example, there is a correlation as shown in Figure 3), and then the flow velocity is 2, the fluid flow velocity vf is measured, and the actual fluid flow velocity vf is input to the function generator 8 to calculate the time constant τ, and this time constant τ is input to the multiplier 6 as described above. Therefore, the correction value Tf obtained in the above manner is the optimum value for estimating the true fluid temperature.

Next, the results obtained by the example of the present invention will be explained with reference to FIG.

That is, Figure 4 (Figure a1 shows the indicated value T actually measured by the thermocouple thermometer l, Figure 4 (Figure b1 shows the fluid flow velocity vf measured by the current meter 2, Figure 4 (Figure c1) shows the indicated value T. From these figures showing the correction value Tf after correction,
It is shown that the response delay of the instruction value T0 is accurately corrected with this correction value vf.

In the case of Fig. 4, the fluid 2 is the gas flow at the top of the blast furnace, the fluid thermometer is a CA sheath thermocouple 6.4φ thermocouple thermometer 1, and the flow meter 2 is a turbine type one. All signal calculations were performed using a digital computer using the equations described above.

The current meter 2 may be an ultrasonic current meter, a Botter meter, etc. if the fluid is a liquid, or a turbine current meter, a hot wire current meter, etc. if the fluid is a gas.

In addition, as the fluid thermometer, in the above-described embodiments, a thermocouple thermometer is used, but the present invention is not limited to this, and suitable resistance thermometers, thermistors, etc.
Other thermometers may be used.

As explained above, in the fluid thermometer correction method according to the present invention, the time constant of a fluid thermometer such as a thermocouple thermometer is
By changing the value based on the fluid flow velocity instead of keeping it as a constant value, a correction value is obtained for the actually measured indicated value, so the response delay in the indicated value is accurately corrected, and the true fluid temperature can be estimated more accurately. The effects of this technology are remarkable, such as eliminating the problems that existed in the conventional example.

[Brief explanation of the drawing]

Figure 1 is a graph for explaining the time constant (Figure a1 shows the true fluid temperature, Figure (b) shows the actually measured indicated value, and Figure 2 shows the graph used to implement the method of the present invention. FIG. 3 is a graph showing an example of the relationship between the time constant and the fluid flow rate. FIG. 4 is a graph showing the results of the embodiment of the present invention. Figure a) shows the actually measured specified value, figure B shows the fluid flow velocity, and figure C shows the corrected value. l... Thermocouple thermometer 2... ...
・・・・・・Velocity meter 3・・・・・・・・・Fluid flow 4・・・・・・
...... Temperature converter 5 ...... Differentiator 6 ...... Multiplier 7 ......・Adder

Claims (1)

[Claims] When estimating the true fluid temperature based on the corrected value 'I'fK obtained by correcting the response delay using the following formula for the indicated value Tc1Il' of the fluid thermometer, , First, determine the correlation between the time constant τ of the fluid thermometer and the fluid flow velocity, and then determine the corresponding time constant τl by measuring the fluid flow velocity at the time of temperature measurement. τ in the formula
A correction force method for a fluid thermometer, characterized by: correcting by substituting and calculating Tf=To+τ−Tc t