JPH02154903A - Tube wall thermometer detecting end monitor system - Google Patents

Abstract

PURPOSE:To exactly and early discover an abnormal condition of a heat exchanger tube by actuating an inside failure alarm circuit when a judgement is made that a thermocouple elapse deterioration monitor circuit is provided, an elapse error of some thermocouple exceeds a reference value and this temperature difference has a tendency to increase. CONSTITUTION:A tube wall temperature monitor circuit 6 and besides a thermo couple elapse deterioration monitor circuit 7 are provided in a circuit unit 2, which is provided with an output circuit 7a of an alarm and data, an opera tion and storing circuit 7b of sampling data and an input circuit 7c of a boiler side signal and temperature. With the above constitution, each tube wall tempera ture is measured and stored during a stabilized heating condition and a stop condition. When the same condition is produced thereafter, each temperature is also measured and stored, the tendency of deterioration of a thermocouple 3 is foreseen and the precision lowering of the thermocouple is informed by the alarm by the movement of elapsed temperature change from the sampled data. Thereby, the reliability of the judgment of a degree of deterioration of the thermocouple 3 can be improved to always and exactly grasp the abnormal condition of the heat exchanger tube.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a boiler tube wall thermometer, and more particularly to a tube wall thermometer detection end monitoring system.

[Conventional technology]

Conventional boiler tube wall thermometers are used to understand the temperature distribution of heat transfer tubes exposed to high-temperature atmospheres, such as heaters and reheaters installed in the ice walls of furnaces and combustion gas passages, and to monitor abnormal heating. , displays the measured temperature.

In addition to recording the measured data, it outputs the measured data to an external device and issues an alarm if the temperature exceeds the alarm setting.

FIG. 7 shows a conceptual diagram of this tube wall thermometer.

In the figure, 1 is a tube wall thermometer, 2 is its circuit unit,
3 is a thermocouple which is a detection end, 4 is a heat exchanger tube, and 5 is a header.

In this conventional device, the tip of the thermocouple, which is the detection end of the tube wall thermometer, is often welded through a pad and is long, making it difficult to check the accuracy. Despite the lack of accuracy control, no consideration was given to the function of monitoring the accuracy of this thermocouple.

[Problem to be solved by the invention]

Conventional tube wall thermometers do not take into consideration the function of monitoring the accuracy of the thermocouple at the detection end, and if the accuracy of the thermocouple decreases significantly due to aging, it may cause problems such as abnormal heating of boiler heat exchanger tubes. There was a problem that abnormalities could no longer be detected, leading to accidents.

The purpose of the present invention is to monitor how the accuracy of a thermocouple, which is the emitting end of a tube wall thermometer, changes over time due to deterioration, so that abnormal conditions in heat exchanger tubes can be detected accurately and early. There is a particular thing.

[Means to solve the problem]

The above object is achieved by adding the following circuit to the tube wall thermometer to monitor the deterioration of the thermocouple over time.

That is, instead of checking the accuracy of the thermocouple by a thermoelectromotive force characteristic test, the temperature of each tube wall is measured and stored when the boiler is in a stable heating state and in a stopped state. From then on, when the same conditions are met, each temperature is measured and stored in the same way, and based on the trends in temperature changes over time from this collected data, the tendency of thermocouple deterioration is predicted, and an alarm is sent to the thermocouple. Add a circuit to notify of the decrease in accuracy.

[Operation] The thermocouple aging monitoring circuit added to the tube wall thermometer detects when the temporal error (difference from the initial measurement value) of any thermocouple exceeds a predetermined reference value, and When it is determined that this temperature difference is on the rise, an attached internal failure alarm circuit is activated.

As a result, the operation supervisor can recognize that the accuracy of the thermocouple is decreasing and can take corrective action, thereby preventing the continuation of temperature measurement with a large error.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. still,
The same parts as in the conventional example are given the same reference numerals.

FIG. 1 is a conceptual diagram of a tube wall thermometer according to an embodiment of the present invention, and the circuit unit 2 is provided with a thermocouple aging deterioration monitoring circuit 7 in addition to a tube wall temperature monitoring circuit 6. This thermocouple deterioration monitoring circuit 7 includes an output circuit 7a that outputs an alarm or outputs data due to deterioration of the thermocouple 3, an arithmetic/storage circuit 7b that calculates and stores collected data, a boiler side signal, a temperature It is provided with an input circuit 7C for inputting.

A temperature signal to the thermocouple aging monitoring circuit 7 is inputted via the tube wall temperature monitoring circuit 6. The boiler side signal is a signal for measuring temperature over time, and is a signal as shown below.

(1) A signal sent from the boiler side when the rated load is reached under predetermined operating conditions, such as burner pattern and fan operating status, depending on the characteristics of each boiler.

(2) A signal sent from the boiler side several minutes after a normal stop (the set time is determined based on the characteristics of the boiler).

For these two types of signals from the boiler side, since the deterioration of the thermocouple 3 does not progress rapidly, the data collection interval is set to a heating time of 500 hours or more at the shortest.

The allowable error value, which is the standard for determining deterioration over time, is based on the JISC
The value is the tolerance for each 16020 class, plus a little more than that in consideration of measurement error.

Based on the signal from the boiler, the first pipe wall temperature measurement taken is used as the temperature reference point, and subsequent measured temperatures are expressed as temperature differences from the reference point, plotted over time and shown in a pattern diagram. The pattern diagrams shown in Figures 2 to 5 can be outputted from the thermocouple aging monitoring circuit 7 as desired, but the case where an alarm is output is as shown in Figures 4 and 5. , the plus or minus tolerance value is exceeded twice (or more than once) in a row, and the error is also on the rise.

If it is difficult to make a decision based on one piece of alarm data, make a decision by referring to the other data (in the case of rated load data, immediately after a stop; in the case of data immediately after a stop, the rated load data). By collecting and comparing data under two completely different conditions in this manner, the reliability of determining the degree of deterioration of the thermocouple 3 can be improved.

FIG. 6 is a schematic diagram of the monitoring system of the present invention described above, and the contents described in this diagram are as described above.

〔Effect of the invention〕

As explained above, according to the present invention, by constructing a monitoring system for thermocouples, which are the detection ends of tube wall thermometers, there is no need for thermoelectromotive force characteristic tests that must be performed with the thermocouples removed. It is possible to always accurately grasp the abnormal state of the heat tube.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a tube wall thermometer according to an embodiment of the present invention;
Figures 2, 3, 4, and 5 are graphs of time-dependent transition patterns of thermocouple errors, Figure 6 is a schematic diagram of a monitoring system according to the present invention, and Figure 7 is a pipe wall according to a conventional example. It is a conceptual diagram of a thermometer. 1... Pipe wall thermometer, 2... Circuit unit, 3...
Thermocouple, 7...Thermocouple aging deterioration monitoring circuit. Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A boiler tube wall thermometer with a thermocouple at the detection end collects the boiler tube wall temperature under specific conditions over time, and determines whether the temperature has deteriorated based on the tendency of the thermocouple error to change over time, which is calculated from these data over time. A pipe wall thermometer detection end monitoring system characterized by having a function to predict trends in temperature and issue an alarm as an internal failure.