JPS61500868A - Method and apparatus for detecting temperature profile through the thickness of a component - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Method and apparatus for sensing temperature profile through the thickness of a component The present invention particularly relates to temperatures across the thickness of components such as thick plates or thick-walled pipes. The present invention relates to a method and apparatus for detecting. This method is especially used for boilers. used to detect temperature profiles through the wall thickness of components such as pipes. 4. Sru.

The temperature of a thick-walled pipe through which a hot medium flows will only change when the temperature of the medium changes. The temperature of the inner layer will not immediately equal the new temperature, but the temperature of the inner layer will The new temperature will approach the new temperature faster than the normalized average temperature.

The faster the new temperature is approached, the more the inner layer's thermal expansion will overcome the interference from the surrounding material. box office. This generates large stress, and this stress causes material fatigue. (Low cycle district management).

According to the Boiler Technical Supervision Association's regulations, measures must be taken to avoid accidents caused by pipe bursts. Therefore, the material fatigue of the pipe had to be recalculated based on the measured values. Now, measure the temperature and wall thickness of the inner layer of the pipe, and use the following formula based on the measurement results. Recalculations have been carried out in the same way that thermal stress is calculated.

αζ - Shape factor of thermal stress β, − difference in longitudinal elongation E■ Elastic modier Roaring temperature difference ■ - Lateral contact coefficient However, regarding the above formula, the results of the measurements performed are not accurate due to the following reasons: has been revealed.

– When using electrically isolated thermocouples, direct opposite connections reduce temperature differences. However, thermocouples themselves also have characteristics that are affected by the passage of time. In addition, the geometric condition of the thermocouple tip is correct unless it is due to X-ray imaging. cannot be determined with certainty, and the properties of the material insulating the thermocouple are Since the case is not known, the result of the above detection is inaccurate.

If using uninsulated thermocouples, both thermocouples must be For each, first ensure that there is no potential with respect to the measurement transducer. In this case, the temperature of the phase-inner layer of the measuring transducer is actually It is not something that can be measured immediately, and moreover, from the inner layer 31 to 5 Imperial Seals. The measurement was taken from the outside through the hole at a distance from the wall, and it was inserted to the center of the wall. The average wall temperature is measured with the thermocouple sleeve misaligned, so This reduces accuracy.

Therefore, it is an object of the present invention to accurately sense temperature throughout the wall thickness of a component. The object of the present invention is to provide a method and apparatus that can achieve this goal.

To achieve the above object, the features set forth in claims 1 and 2 Advantageous implementations of the invention are proposed according to the invention. 6. According to the present invention, please refer to claims 2 and 4 for aspects. For example, you only need to use one thermocouple and the thermocouple reading at the measurement location is A complete l&degree profile over the wall thickness of the applicable component based on the chronological order of This is advantageous because the feel can be determined.

Other features and advantages of the invention will be more easily understood from the following description with reference to the accompanying drawings. Please explain the drawing as follows.

FIG. 1 is a cross-sectional diagram illustrating a state in which a thermocouple is attached to a component according to the present invention. It is a diagram.

FIG. 2 is a cutaway perspective view of a component according to the present invention, showing the measurement position of a thermocouple. This is what is shown.

As shown in FIG. 1, thermocouple 10 is mounted near the inner layer of component 12. t has been ignored. The thermocouple is inserted into the holder 14.

By attaching the thermocouple near the inner layer of the component in this way, the Accurately detects the complete temperature profile across the thickness of the component according to the method can do. When detecting the temperature profile, -S is performed. Calculations are performed using a microprocessor and electronic data processor in a similar manner. be exposed.

Based on the temporal order of the thermocouple temperature measurements at the thermocouple measurement location (in some configurations) In implementing a method to determine the complete temperature profile through the wall thickness of a component, The equilibrium equation for 74G can be found as follows.

A heat transfer process that leads to a three-dimensional temperature profile: This can be explained using the Elier differential equation.

χ atH-□・Temperature transfer ability of component parts ζPIIP χ - Thermal conductivity coefficient of the component C9 - Unit example capacity of component parts p - Degree of rotation of the material of the component ◇<r, x, kun　-temperature τ - time x, y, z - spatial coordinates The direction in which heat flows is generally the same as the direction of the coordinate axes, so here we will use the following flat line. We will only consider the one-dimensional temperature profile described by the equilibrium equation. Ru.

In this case, as shown in FIG. 2, the following cycle B condition is satisfied.・ Furthermore, measurement position x-r, outside 75 (x-r) and me a In solving the differential equation to determine the temperature profile between For the stationary case: ;) The following first ``U4 condition holds.

To determine the complete temperature profile from the inner layer (x − rt) to the outer layer , the third marginal condition must be satisfied, i.e. X■ as 1 This peripheral condition explains the temporal temperature change in the inner layer, which is the fluid side. Ru.

When determining the peripheral conditions in the inner layer, the analytical solution of differential equation (2) is considered. However, in all cases, this solution is given by the following formula, where m'a2 is It will be done.

For each n, one solution is obtained in order of n.

In the case of the illustrated example, it has been shown that the accuracy of the solution for n+a'l is sufficient. There is. Therefore, the series of solutions after n-'l can be ignored. this place In this case, the following formula is obtained.

For the three given support positions x1+1, x1 and xl-1, uniquely An equation system consisting of three equations with three unknowns that can be solved Analog in the direction of 0 time, which allows you to narrow down the problem to decide the officials according to the time. The coefficient 82 can be eliminated by considering the equation system The unknowns in can be ascertained by calculating the peripheral temperature in the inner layer.

Therefore, given the marginal conditions in the inner layer, following Crank-Nicholson, The complete temperature profile can be fully calculated using a well-known comprehensive differential method. It can be decided to be positive. Using the temperature profile determined in this way, The complete average wall temperature can be determined by the well-known square law.

Another feature of the method described above is that the value of a particular material property at each identification point is determined as a function of temperature. [Vulk Shobo in Erasen City] FDBR Handbook Ni, published in 1976 by Verl-ag) Association of Boiler, Vessel and Piping Structure Specialists (Fachver-band Dall) p'kessal-, Behfltar-und Rohrleitungsb Chapter 3 of "Strength Calculation in Material Properties" of "Handbook" edited by au) See table].

The accuracy of the temperature profile to be determined according to the method described above is based on the other shadows + 9 quantities. It can be enhanced by considering it as a function of predetermined factors.

Electronic data on the overall fatigue level of components that are subjected to stress based on pressure and temperature - It is advantageous to use the above method when calculating the processing system. . In this case, it is clear that the temperature profile changes significantly over the wall thickness. ing. The general temperature difference ◇ is the average wall temperature, and the temperature in the inner layer of the component ◇ It can be entwined with l. That is, Δ34.6, ~◇.

In addition, to can be expressed by the following formula.

where: V - volume of component When examining the overall fatigue level, the pressure applied to such components within a limited time interval is and temperature and temperature profile measurements are obtained. 2+1! ! Fixed position change speed Accordingly, the response cycle is controlled <'H. Assess static and dynamic stresses in component parts. The measurements required for the Alternatively, if there is no satisfaction, please respond to the above-mentioned international! A inspection report M faction ■τOThl: Z and = IAτZONAL SEA, “LCE IE?o :L ON--Hot--...Enjoyment...---Enjoyment...+++Chewing--+--+--+++- -Kyoichi +--Kyoichi Kaichi+-! ff1RNAτZONAL A2”1-IC-’= T-work ON No? CT/EX' 51400405 (5A l11545 )-1＋＋＋＋−・・・＋Zeng・Shu・+Shufuken・＋＋＋＋＋−・−−−・−−・− 1＋＋＋＋Work・++　−Threat・――−・−Work−1

Claims (1)

[Claims] 1. temperature across the wall thickness of components, especially thick plates or thick-walled pipes. A method of detecting formed by a heat transfer process based on the temporal sequence of thermocouple temperature measurements The complete temperature profile is determined based on the following equilibrium equation, (■ ■(τ,x)/■τ)=a(■)×(■2■(τ,x)/■x2) Here, a(■)=λ/cpρTemperature conduction ability of component λ=thermal conductivity coefficient of component cp = unit thermal capacity of component ρ = density of component material ■(τ, x) = temperature τ=time x = route coordinates In addition, the following conditions apply: As τ=0 ■(τ, x) = g(τ) (5) As x=Γme ■(τ, x) = Γ(τ) (3) ■=Γa ■■(τ, x)/■x=0(4) In all cases, with m=1/2 ▲There are mathematical formulas, chemical formulas, tables, etc.▼A method characterized by (7). 2. The method according to claim 1, in which equation (7) is used where n=2. ■(τ, x) = a0 + a1x + a2 (x2/2 + τ) (8) is the temperature profile A method characterized by being sufficiently accurate in determining the 3. Wall thickness of the component used to carry out the method according to claim 1 A device that detects temperature over a period of time, in which only one thermocouple (10) is a component. (12) A device characterized in that it is placed near the inner layer of. 4. 3. The device according to claim 3, wherein the thermocouple (10) is mounted on a holder (14). ).