JP2017156234A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor capable of sensing a rise in temperature of a plurality of objects to be sensed for temperature accurately with a simple structure.SOLUTION: A temperature sensor 10 for measuring temperatures of a plurality of areas comprises: sensing units 19A, 19B, and 19C that include thermocouples 11A, 11B, and 11C and thermistors 17A, 17B, and 17C; and a measuring instrument. The thermocouples 11A, 11B, and 11C are arranged on objects to be sensed for temperature. The thermistors 17A, 17B, and 17C are in series respectively connected to the thermocouples 11A, 11B, and 11C. The sensing units 19A, 19B, and 19C are in parallel connected to the measuring instrument. The measuring instrument senses a rise in temperatures of the objects to be sensed for temperature on the basis of thermoelectromotive forces of the thermocouples 11A, 11B, and 11C.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a temperature detection device that detects temperatures of a plurality of objects to be measured.

  For example, the temperature of an industrial machine such as a belt conveyor device may increase due to friction of components and natural heat generation of combustible transported materials. As a method of monitoring the heat generation of an industrial machine, a method of installing a thermocouple and a method of detecting a temperature by installing an optical fiber thermometer are known. The following Patent Document 1 describes an ignition monitoring device that installs an infrared temperature detector capable of detecting temperature in a non-contact manner on a belt conveyor device and measures the temperature of a deposit caused by falling or scattering of a conveyed product. Has been.

JP 2002-205813 A

  However, in the case where temperatures are detected by thermocouples at a plurality of locations in an industrial machine, it is necessary to provide a large number of thermocouples and to provide a large number of measuring instruments that detect the temperature data of each thermocouple. Since the optical fiber thermometer, for example, shows an average temperature per meter, the detection sensitivity is low, and it may be difficult to detect a temperature rise before spontaneous ignition. The infrared temperature detector needs to be provided with a large number of detectors corresponding to the measurement locations, and the cost increases when monitoring temperatures at a plurality of locations on the industrial machine.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems and to provide a temperature detection device capable of accurately detecting a temperature increase of a plurality of temperature measurement targets with a simple configuration.

  A temperature detection device according to an aspect of the present invention is a temperature detection device that measures temperatures at a plurality of locations, and includes a thermocouple disposed in a temperature measurement target and a thermistor connected in series to the thermocouple. A plurality of detection units and a plurality of the detection units are connected in parallel, and a measuring instrument that detects a temperature rise of the temperature measurement target based on a thermoelectromotive force of the thermocouple.

  According to this, the connection and disconnection between the thermocouple and the measuring instrument are switched by the change in the resistance value of the thermistor. For this reason, since an electromotive force is output to a measuring device from the thermocouple of the detection part where temperature rose among a plurality of detection parts, temperature can be detected accurately. In addition, since a plurality of detection units are connected in parallel, the number of measuring instruments and the number of measuring instrument terminals can be reduced, so that the temperature can be detected with a simple configuration. Therefore, it is possible to detect a temperature rise of a plurality of objects to be measured with a simple configuration and high accuracy.

  As a desirable mode of the present invention, the resistance value of the thermistor decreases as the temperature increases. According to this, the resistance value of the thermistor whose temperature has increased decreases, and the thermoelectromotive force of the thermocouple connected in series with this thermistor is output. For this reason, even when a plurality of detection units are connected, it is possible to selectively measure with the thermocouple of the detection unit whose temperature has increased.

  As a desirable aspect of the present invention, in the state where the temperature of the detection unit is at room temperature, the thermoelectromotive force of the thermocouple is not output to the measuring instrument, and when the temperature of the detection unit rises, Electric power is output to the measuring instrument. According to this, by providing the thermistor, the output of the thermoelectromotive force of the thermocouple and the cutoff thereof are switched, so that the temperature increase of the belt conveyor device can be detected with high accuracy.

  As a desirable mode of the present invention, the detection unit is arranged in the vicinity of the roller of a belt conveyor device having a conveyance belt and a plurality of rollers that support the conveyance belt and are arranged in the conveyance direction of the conveyance belt. . According to this, it is possible to reliably detect heat generation due to roller friction or the like.

  As a desirable mode of the present invention, the belt conveyor device includes a shaft that rotatably supports the roller, and the detection unit is disposed in contact with or close to the shaft. According to this, since the shaft is a non-rotating member, the thermocouple and the thermistor can be easily arranged on the shaft.

  As a desirable mode of the present invention, the thermocouple has a pair of thermocouple wires, and the thermistor is connected in series to either one of the pair of thermocouple wires. With such a simple configuration, the temperature can be detected with high accuracy.

  As a desirable aspect of the present invention, one thermocouple wire of the plurality of thermocouples is electrically connected to a first terminal of the measuring instrument, and the other thermocouple wire of the plurality of thermocouples is It is electrically connected to the second terminal of the measuring instrument. According to this, since a plurality of thermocouples and a plurality of thermistors are connected to two terminals of the measuring instrument, it is not necessary to provide a plurality of measuring instruments or a large number of terminals, and the temperature can be detected with a simple configuration. can do.

  According to the temperature detection device of one aspect of the present invention, it is possible to accurately detect a temperature increase of a plurality of temperature measurement targets with a simple configuration.

FIG. 1 is a schematic view of a coal-fired power plant including a belt conveyor device to which the temperature detection device according to the embodiment can be applied. FIG. 2 is a schematic side view of the belt conveyor device according to the embodiment. FIG. 3 is a schematic front view of the belt conveyor device according to the embodiment. FIG. 4 is a schematic circuit diagram for explaining the configuration of the temperature detection device according to the embodiment. FIG. 5 is a perspective view for explaining a fixing portion of the detection unit to the roller. FIG. 6 is a table illustrating temperature detection results of the temperature detection device according to the example. FIG. 7 is a table showing the temperature detection results of the temperature detection device according to the comparative example. FIG. 8 is a schematic circuit diagram for explaining the configuration of the temperature detection device according to the comparative example.

  Hereinafter, embodiments of a temperature detection device according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. Moreover, the method, apparatus, and modification example described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

  FIG. 1 is a schematic view of a coal-fired power plant including a belt conveyor device to which the temperature detection device according to the embodiment can be applied. The thermal power plant 100 includes a bunker 104, a pulverized coal machine 105, a boiler 106, a denitration device 107, an electric dust collector 108, and a desulfurization device 109. Coal unloaded from the coal carrier with a coal lift is sent to the coal storage 102 by the belt conveyor device 101. Coal is piled up and stored in the coal storage 102. Coal in the coal storage yard 102 is transferred to the bunker 104 by the belt conveyor device 103 at the time of consumption and temporarily stored. A required amount of coal from the bunker 104 is taken out and sent to the pulverized coal machine 105. The coal is pulverized by the pulverized coal machine 105 to generate pulverized coal. The pulverized coal is supplied to the boiler 106 and combusted to generate high-pressure steam, and the steam turbine is driven by the high-pressure steam to generate power. The flue gas passes through the denitration device 107, the electrostatic precipitator 108, and the desulfurization device 109, and after removing sulfur oxide (SOx), nitrogen oxide (NOx), dust, and the like contained in the flue gas, the flue gas is removed from the chimney 110. Discharged.

  FIG. 2 is a schematic side view of the belt conveyor device according to the embodiment. FIG. 3 is a schematic front view of the belt conveyor device according to the embodiment. 2 and 3 show a part of the belt conveyor device 103 shown in FIG. The belt conveyor device 103 includes a roller driving unit 200, a driving roller 201, a conveying belt 202, a conveying roller 203 provided on the conveying side of the conveying belt 202, and a return roller provided on the return side of the conveying belt 202. 206. Although three conveyance rollers 203 and three return rollers 206 are illustrated, a large number are provided along the conveyance direction or the return direction of the conveyance belt 202.

  The roller driving unit 200 transmits power to the driving roller 201 such as a pulley to rotate the driving roller 201. By the rotation of the driving roller 201, the conveyance belt 202 can move in a predetermined direction. The upper conveyor belt 202 moves to the right side of FIG. 2 and conveys coal. The lower conveying belt 202 moves back in the direction opposite to the conveying direction. The conveyance side rollers 203 each have a conveyance side shaft 204 along the rotation center axis, and the conveyance side shaft 204 is fixed to the conveyance side roller support part 205. The conveyance side roller 203 is rotatably fixed to the conveyance side shaft 204 via a bearing (not shown). A plurality of conveyance side rollers 203 are provided in the conveyance direction to support the conveyance belt 202 on the conveyance side, and each of them is rotated as the conveyance belt 202 moves in the conveyance direction.

  As shown in FIG. 3, the transport side roller support portion 205 is provided on the upper side of the base 210 and supports both ends of the transport side roller 203. The base 210 is supported by a plurality of legs 211. In the present embodiment, the transport side roller 203 may be connected to three transport side rollers 203a, 203b, and 203c. The conveyance side roller 203b is provided in parallel with the base 210, and conveyance side rollers 203a and 203c are connected to both sides of the conveyance side roller 203b, respectively. The conveyance side rollers 203a and 203c are inclined upward, and the conveyance side roller 203 has a concave shape when viewed from the front. The conveyance side shaft 204 has bent portions 204a and 204b, and has a concave shape along each of the conveyance side rollers 203a, 203b, and 203c. With this configuration, the transport belt 202 is concave along the shape of the transport rollers 203a, 203b, and 203c, and can be prevented from dropping when the coal 150 is transported.

  As shown in FIG. 2, the return side roller 206 has a return side shaft 207 along the rotation center axis, and the return side shaft 207 is fixed to the return side roller support portion 208. The return roller 206 is rotatably fixed to the return shaft 207 via a bearing (not shown). A plurality of return side rollers 206 are provided along the return side direction to support the return side conveyance belt 202, and each of the return side rollers 206 is rotated as the conveyance belt 202 moves in the return side direction.

  As shown in FIG. 3, the return side roller support 208 is provided below the base 210 and supports both ends of the return side roller 206. The return side roller 206 is provided in parallel with the base 210, and the return side conveying belt 202 is flat.

  The belt conveyor device 103 may have a total length ranging from several hundreds of meters to 1 km. For example, several hundreds of the conveyance-side rollers 203 and the return-side rollers 206 are arranged. Since the conveyance side roller 203 and the return side roller 206 operate normally even when a rotation abnormality occurs due to deterioration or damage of the bearing and shaft, most of the conveyance side roller 203 and the return side roller 206 operate normally. The movement of 202 is possible. However, the conveyance-side roller 203 or the return-side roller 206 with abnormal rotation generates frictional heat due to contact with the conveyance belt 202 or generates frictional heat from a bearing inside the roller, and the generated frictional heat is generated by the conveyance belt 202. Continue to communicate to the side. For this reason, abnormal heating of the conveyor belt 202 may occur, causing a belt conveyor fire.

  The temperature detection apparatus 10 of the present embodiment includes a plurality of detection units 19A, 19B, 19C, 19D, 19E, and 19F. The plurality of detection units 19A, 19B, and 19C are arranged in the vicinity of the conveyance side roller 203, respectively, and the plurality of detection units 19D, 19E, and 19F are arranged in the vicinity of the return side roller 206, and the conveyance side roller 203 and the return side roller 203, respectively. An increase in temperature of the side roller 206 can be detected.

  FIG. 4 is a schematic circuit diagram for explaining the configuration of the temperature detection device according to the embodiment. The temperature detection apparatus 10 includes a measuring device 30 to which a plurality of detection units 19A, 19B, and 19C and a plurality of detection units 19D, 19E, and 19F are connected in parallel. In FIG. 4, three detection units 19 </ b> A, 19 </ b> B, and 19 </ b> C are illustrated, but the detection unit 19 </ b> D, 19 </ b> E, and 19 </ b> F of the return side roller 206 may be provided, and 4 corresponding to the number of a plurality of rollers. Two or more detection units may be connected in parallel.

  The measuring device 30 is a device that measures temperature based on the thermoelectromotive force of the thermocouples 11A, 11B, and 11C, and a data logger or the like can be used. A display unit 35 is connected to the measuring instrument 30 and displays the temperature measured by the measuring instrument 30. The measuring device 30 can continuously measure the temperature while the belt conveyor device 103 shown in FIGS. 2 and 3 is operating. The measuring instrument 30 may include a storage unit that stores the relationship between the measured temperature and time.

  As shown in FIG. 4, the detection unit 19A has a thermocouple 11A and a thermistor 17A connected in series, the detection unit 19B has a thermocouple 11B and a thermistor 17B connected in series, and the detection unit 19C has a thermocouple. 11C and the thermistor 17C are connected in series. A plurality of detectors 19A, 19B, and 19C are connected in parallel to the measuring instrument 30 via the compensating conductors 15a and 15b.

  The plurality of thermocouples 11A, 11B, and 11C are configured by connecting a pair of thermocouple strands 21 and 22, respectively. For example, a K thermocouple can be used as the thermocouples 11A, 11B, and 11C of the present embodiment. The thermocouple wire 21 is an alloy (chromel) mainly composed of nickel (Ni) and chromium (Cr), and is connected to the plus-side terminal 30 a of the measuring instrument 30. The thermocouple wire 22 is an alloy (alumel) mainly composed of nickel (Ni), and is connected to the negative terminal 30 b of the measuring instrument 30. A location where the thermocouple element 21 and the thermocouple element 22 are connected becomes the hot junction 20. A cold junction (not shown) serving as a reference temperature is provided inside the measuring instrument 30. The measuring instrument 30 includes a compensation circuit for compensating for the temperature change of the cold junction.

  The thermocouples 11A, 11B, and 11C generate thermoelectromotive force due to a temperature difference generated between the hot junction 20 and the cold junction. Due to the thermoelectromotive force, a voltage Vth is generated between the thermocouple element 21 and the thermocouple element 22 at a location away from the hot junction 20. When the temperature of the hot junction 20 is a high temperature Th and the temperature of the cold junction inside the measuring instrument 30 is a low temperature Tc, the relationship Vth = 1 / k × (Th−Tc) is established. Here, k is a proportional constant, and in the case of a K thermocouple, k is about 24 ° C./mV. (Th−Tc) is a temperature difference between the high temperature Th and the low temperature Tc, and the voltage Vth is proportional to the temperature difference (Th−Tc). Thereby, the measuring instrument 30 can detect the temperature of the hot junction 20 based on the voltage Vth output from the thermocouples 11A, 11B, and 11C.

  In the present embodiment, the compensation lead wire 15a is connected to the plus side terminal 30a of the measuring instrument 30, and the compensation lead wire 15b is connected to the minus side terminal 30b. The thermocouple wires 21 of the thermocouples 11A, 11B, and 11C are connected to the connection portions 31a, 32a, and 33a of the compensation lead wire 15a, respectively, and are electrically connected to the plus side terminal 30a. The thermocouple wires 22 of the thermocouples 11A, 11B, and 11C are connected to the connecting portions 31b, 32b, and 33b of the compensating lead wire 15b, respectively, and are electrically connected to the minus side terminal 30b. In this way, the thermocouple strands 21 of the plurality of thermocouples 11A, 11B, and 11C are electrically connected to one positive terminal 30a, and the thermocouple strands 22 of the plurality of thermocouples 11A, 11B, and 11C are The thermocouples 11A, 11B, and 11C are connected in parallel by being electrically connected to one negative terminal 30b.

  As the compensating conductors 15a and 15b, metal wiring having thermoelectromotive force characteristics equivalent to those of the thermocouples 11A, 11B and 11C can be used. For example, the compensating lead wire 15a connected to the positive terminal 30a uses copper (Cu) or iron (Fe) metal wiring, and the compensating lead wire 15b connected to the negative terminal 30b is made of copper (Cu). A metal wiring made of an alloy material containing nickel (Ni) can be used. As described above, the belt conveyor device 103 may have a total length ranging from several hundreds of meters to 1 km. Therefore, by using the compensating conductors 15a and 15b made of a material cheaper than the thermocouples 11A, 11B, and 11C. Cost can be reduced. The compensating conductors 15a and 15b may be made of the same material as the thermocouple wires 21 and 22, respectively. In this case, the temperature rise can be detected with higher accuracy.

  The temperature detection apparatus 10 may be provided with a protective tube (not shown) for protecting the thermocouple wires 21 and 22 of the thermocouples 11A, 11B, and 11C. For example, an insulating ceramic material or a resin material can be used for the protective tube. When a protective tube is provided, it is preferable that the hot junction 20 and the thermistors 17A, 17B, and 17C are arranged outside the protective tube.

  The thermistors 17A, 17B, and 17C are connected in series to the thermocouples 11A, 11B, and 11C by being connected in series in the middle of the thermocouple wire 22. The thermistors 17A, 17B, and 17C have a temperature characteristic in which the resistance value decreases as the temperature increases. As the thermistors 17A, 17B, and 17C, for example, a NTC (Negative Temperature Coefficient) thermistor and a CTR (Critical Temperature Resistor) thermistor can be used.

Here, the resistance value R of the thermistors 17A, 17B, and 17C is expressed by the following equation (1) in the case of an NTC type thermistor. The resistance value R (Ω) in equation (1) is the resistance value at the ambient temperature T (K), and the resistance value R ₀ (Ω) is the reference resistance value at the reference temperature T ₀ (K). B (K) is a temperature characteristic constant called a B constant, and represents the magnitude of resistance change obtained from resistance values at two arbitrary temperatures of the resistance-temperature characteristics. Further, in the CTR type thermistor, the B constant of the formula (1) is very large, and the resistance value can be rapidly changed at a specific temperature.

_{R = R 0 × exp {B} × (1 / T-1 / T 0)} ... formula (1)

  As the thermistors 17A, 17B, and 17C of this embodiment, for example, a thermistor having a zero load resistance value of 5 kΩ or more and a B constant of about 4000 K or more when the ambient temperature is constant at 25 ° C. (298 K) may be used. desirable. Thermistors 17A, 17B, and 17C have a high resistance value of 10 kΩ at room temperature (25 ° C.), for example, when a thermistor having a zero load resistance value of 10 kΩ at 25 ° C. and a B constant of 4100 K is used. When the temperature rises above 85 ° C., the resistance value decreases to 1 kΩ or less, and at 100 ° C., the resistance value decreases to about 600Ω. In addition, when a CTR type thermistor is used, the resistance value changes more rapidly. For example, the resistance value at room temperature (25 ° C.) decreases from about 1 MΩ to about 500Ω when the temperature rises to 85 ° C. or higher. To do.

  As described above, the detection units 19A, 19B, and 19C of the present embodiment are arranged on the plurality of temperature measurement targets of the belt conveyor device 103, respectively. The detectors 19A, 19B, and 19C are connected to the thermocouples 11A, 11B, and 11C and the thermistors 17A, 17B, and 17C in series. Therefore, when the temperature of the belt conveyor device 103 does not increase, In the state, the resistance values of the thermistors 17A, 17B, and 17C are high, and the thermoelectromotive forces of the thermocouples 11A, 11B, and 11C are not output to the measuring instrument 30.

  Of the detection units 19A, 19B, and 19C, for example, when the temperature increase of the belt conveyor device 103 occurs in the temperature measurement target in which the detection unit 19A is arranged, the resistance value of the thermistor 17A of the detection unit 19A decreases. Thereby, the thermoelectromotive force of the thermocouple 11A connected in series with the thermistor 17A is output to the measuring instrument 30. The thermistors 17B and 17C of the detectors 19B and 19C arranged other than the temperature-measured object whose temperature has risen are in a state of high resistance, and the thermocouples 11B and 11C connected in series with these thermistors respectively generate heat. The electromotive force is not output to the measuring instrument 30. In this way, connection and disconnection between the thermocouples 11A, 11B, and 11C and the measuring instrument 30 are switched by changes in the resistance values of the thermistors 17A, 17B, and 17C.

  When a plurality of thermocouples are connected in parallel to a pair of terminals without connecting a thermistor, the average of all thermocouples depends on the balance of the lengths of the thermocouples 11A, 11B, and 11C and the lengths of the compensating conductors 15a and 15b. The temperature is measured and the measured temperatures of the thermocouples 11A, 11B, and 11C vary, and it is difficult to accurately detect the temperature. As described above, the temperature detection device 10 according to the present embodiment generates thermoelectromotive force from the thermocouples 11A, 11B, and 11C at locations where the temperature does not increase due to the temperature characteristics of the resistance values of the thermistors 17A, 17B, and 17C. The thermoelectromotive force is output to the measuring instrument 30 from the thermocouples 11A, 11B, and 11C where the temperature rise has occurred. As described above, since the thermoelectromotive force is selectively output to the measuring instrument 30 from the thermocouple whose temperature has risen among the thermocouples 11A, 11B, and 11C, a plurality of thermocouples 11A are connected to the pair of terminals 30a and 30b. , 11B and 11C can be accurately detected even when connected in parallel. Therefore, it is possible to prevent a fire accident or the like by detecting the occurrence of a temperature rise in the belt conveyor device 103.

  It is preferable that the thermistors 17A, 17B, and 17C have a temperature characteristic of a resistance value such that a thermoelectromotive force is output at, for example, 100 ° C. or higher. Although depending on the type of coal, the spontaneous ignition temperature of coal is about 160 ° C., so that the temperature detection device 10 detects that the temperature of the belt conveyor device 103 has risen to 100 ° C., thereby preventing a fire accident. be able to.

  Since the plurality of detection units 19A, 19B, and 19C are connected to the pair of terminals 30a and 30b, the configuration of the measuring instrument 30 can be simplified as compared to the case of connecting each of the plurality of detection units. Moreover, since the compensation conducting wires 15a and 15b are also composed of two, the configuration of the temperature detecting device 10 is simple and can be easily installed on the belt conveyor device 103.

  FIG. 5 is a perspective view for explaining a fixing portion of the detection unit to the roller. As shown in FIG. 5, the detection unit 19 </ b> A is fixed to the conveyance side shaft 204 of the conveyance side roller 203. Specifically, the hot junction 20 and the thermistor 17 </ b> A of the thermocouple 11 </ b> A are fixed to the end surface 204 c of the transport side shaft 204. Since the thermistor 17 </ b> A is disposed in the vicinity of the hot junction 20, the thermistor 17 </ b> A has a temperature equivalent to that of the hot junction 20. The temperature rise of the conveyance side roller 203 is transmitted to the conveyance side shaft 204, and the temperature of the hot junction 20 of the thermocouple 11A and the thermistor 17A changes. For this reason, the detection unit 19 </ b> A can detect an increase in temperature of the conveyance side roller 203.

  The fixing portion of the detection unit 19 </ b> A is not limited to the end surface 204 c of the transport side shaft 204, and may be an outer peripheral surface 204 d near the end of the transport side shaft 204. The hot junction 20 and the thermistor 17A of the thermocouple 11A are preferably in direct contact with the transport side shaft 204, but may be fixed to the transport side shaft 204 via an insulating resin. Further, the fixing portion may be a conveyance side roller support portion 205 in the vicinity of the conveyance side shaft 204, a screw member (not shown) for fixing the end portion of the conveyance side shaft 204 and the conveyance side roller support portion 205, or the like. It may be. The method for fixing the hot junction 20 and the thermistor 17A of the thermocouple 11A is not particularly limited, and an insulating adhesive tape or adhesive can be used. 5 illustrates the detection unit 19A (thermocouple 11A and thermistor 17A), the same applies to the other detection units 19B and 19C.

  As described above, by arranging the detection units 19A, 19B, and 19C in the vicinity of the end portion of the conveyance side shaft 204, the temperature of the conveyance side roller 203 that is rotationally driven is transmitted to the conveyance side shaft 204. The temperature rise 203 can be detected with high accuracy. Moreover, since the conveyance side shaft 204 supports the conveyance side roller 203 without being driven to rotate, it is easy to fix the detection units 19A, 19B, and 19C.

(Example)
FIG. 6 is a table illustrating temperature detection results of the temperature detection device according to the example. FIG. 7 is a table showing the temperature detection results of the temperature detection device according to the comparative example. In the temperature detection apparatus of the embodiment, the three detection units 19A, 19B, and 19C are arranged in parallel with the measuring instrument 30 as in the temperature detection apparatus 10 shown in FIG. In the detectors 19A, 19B, and 19C, thermocouples 11A, 11B, and 11C and thermistors 17A, 17B, and 17C are connected in series, respectively. In this example, K thermocouples were used as the thermocouples 11A, 11B, and 11C. As the thermistors 17A, 17B, and 17C, NTC thermistors having a zero load resistance value at 25 ° C. of 10 kΩ and a B constant of 4100K were used. The length of each thermocouple wire 21, 22 is about 50 cm. The compensating conductor 15a has a length of 2 m between the terminal 30a and the connection portion 31a, a length of the connection portion 31a and the connection portion 32a, and a length of the connection portion 32a and the connection portion 33a. The compensation lead wire 15b also has a length of 2 m between the connecting portions 31a, 31b, 31c.

  FIG. 8 is a schematic circuit diagram for explaining the configuration of the temperature detection device according to the comparative example. In the temperature detection device 310 of the comparative example shown in FIG. 8, three thermocouples 311A, 311B, and 311C are connected to the measuring instrument 330 in parallel. The temperature detection device 310 of the comparative example is different in that a thermistor is not connected. The thermocouples 311A, 311B, 311C are the same K thermocouples as in the example, and the compensation conductors 315a, 315b to which the thermocouples 311A, 311B, 311C are connected are also the same as those in the example.

  In test 1-3 shown in FIG. 6, one set of thermocouples 11A, 11B, 11C and thermistors 17A, 17B, 17C connected in series is placed in an electric furnace at about 100 ° C., and the other two The set is at room temperature (about 23 ° C.). In Test 1, the thermocouple 11A and the thermistor 17A of the detection unit 19A are placed in a high-temperature furnace, and the other detection units 19B and 19C are at room temperature. Test 2 performs temperature detection by placing only the thermocouple 11B and thermistor 17B of the detection unit 19B in a high temperature furnace, and Test 3 places only the thermocouple 11C and the thermistor 17C of the detection unit 19C in a high temperature furnace. The temperature was detected. In Test 4 shown in FIG. 7, only the thermocouple 311A of the comparative example was placed in an electric furnace, and the other two thermocouples 311B and 311C were detected at room temperature. In Test 5, only the thermocouple 311C was placed in the electric furnace, and the other two thermocouples 311A and 311B were detected at room temperature. The in-furnace temperature and the out-of-furnace temperature of the electric furnace shown in Table 1 of FIG. 6 and Table 2 of FIG. 7 were measured by preparing a thermocouple different from the temperature detectors of Examples and Comparative Examples.

  As shown in FIG. 6, in the test 1 to the test 3, the thermocouple 11A and the thermistor 17A, the thermocouple 11B and the thermistor 17B, and the thermocouple 11C and the thermistor 17C connected in series are all brought to a furnace temperature of about 105 ° C. On the other hand, a temperature of about 100 ° C. is detected. It was shown that all of the temperature detection devices of the examples normally detected the temperature, and the temperature difference between the respective measurement points was small.

  As described above, in the temperature detection device of the embodiment, when the temperature of the thermistors 17A, 17B, and 17C increases, the resistance value decreases, so that the thermocouples that have increased in temperature are selectively selected from the thermocouples 11A, 11B, and 11C. Since the thermoelectromotive force is output to the measuring instrument 30, the temperature can be detected with high accuracy.

  On the other hand, in tests 4 and 5 shown in FIG. 7, the thermocouple 311A detects a temperature of 94.0 ° C. and the thermocouple 311C detects a temperature of 25.6 ° C. with respect to the furnace temperature of about 105 ° C. doing. As described above, the temperature detection device 310 of the comparative example has a large temperature detection error in the thermocouples 311A and 311C, and the difference in detection sensitivity between the thermocouples 311A and 311C is large. This is because the thermoelectromotive force is output to the measuring device 330 from thermocouples at room temperature other than the high-temperature thermocouple, and the thermoelectromotive forces of a plurality of thermocouples are measured. In addition, since the resistance value is different due to the difference in the length of the compensating lead wires 315a, 315b to the thermocouples 311A, 311B, 311C, the thermoelectromotive force of the thermocouple 311A close to the measuring instrument is detected to be high, and the detection sensitivity This is because there is a difference.

  As described above, the temperature detection device 10 according to the present embodiment is a temperature detection device 10 that measures the temperature at a plurality of locations, and the thermocouples 11A, 11B, and 11C that are arranged on the temperature measurement target, the thermocouple 11A, Detection units 19A, 19B, 19C including thermistors 17A, 17B, 17C connected in series to 11B, 11C and a plurality of detection units 19A, 19B, 19C are connected in parallel, and the heat of thermocouples 11A, 11B, 11C And a measuring device 30 that detects a temperature rise of the temperature measurement target based on the electromotive force.

  According to this, connection and disconnection between the thermocouples 11A, 11B, and 11C and the measuring instrument 30 are switched by changes in the resistance values of the thermistors 17A, 17B, and 17C. For this reason, since thermoelectromotive force is output to the measuring device 30 from the thermocouple of the detection part in which temperature rose among several detection part 19A, 19B, 19C, temperature can be detected accurately. Moreover, since the detectors 19A, 19B, and 19C are connected in parallel, the number of measuring instruments and the number of measuring instrument terminals can be reduced, so that the temperature can be detected with a simple configuration. Therefore, it is possible to accurately detect the temperature increase of the belt conveyor device 103 with a simple configuration.

  As a desirable aspect of the present embodiment, the resistance values of the thermistors 17A, 17B, and 17C decrease as the temperature increases. According to this, the resistance value of the thermistor whose temperature has increased decreases, and the thermoelectromotive force of the thermocouple connected in series with the thermistor whose resistance value has decreased is output. For this reason, even when a plurality of detection units 19A, 19B, and 19C are connected, it is possible to selectively measure with the thermocouple of the detection unit whose temperature has increased.

  As a desirable mode of the present embodiment, in the state where the temperature of the detection units 19A, 19B, and 19C is room temperature, the thermoelectromotive force of the thermocouples 11A, 11B, and 11C is not output to the measuring device 30, and the detection units 19A, 19B, and 19C When the temperature rises, the thermoelectromotive force of the thermocouples 11A, 11B, and 11C is output to the measuring instrument 30. According to this, by providing the thermistors 17A, 17B, and 17C, the thermocouples 11A, 11B, and 11C can be switched between outputting and interrupting the thermoelectromotive force. Therefore, since the thermoelectromotive force is selectively output from the thermocouple whose temperature has increased, the temperature increase of the belt conveyor device 103 can be accurately detected.

  As a desirable aspect of the present embodiment, the detection units 19A, 19B, and 19C each include a conveyor belt 202 and a conveyor roller 203 that supports the conveyor belt 202 and is arranged in the conveyance direction of the conveyor belt 202. 103 is disposed in the vicinity of the conveyance side roller 203. According to this, heat generation due to friction or the like of the conveyance side roller 203 can be reliably detected.

  As a desirable aspect of this embodiment, the belt conveyor device 103 includes a conveyance side shaft 204 that rotatably supports the conveyance side roller 203, and the detection units 19 </ b> A, 19 </ b> B, and 19 </ b> C are in contact with or close to the conveyance side shaft 204. Arranged. According to this, since the conveyance side shaft 204 is a member that does not rotate, the thermocouples 11A, 11B, and 11C and the thermistors 17A, 17B, and 17C can be easily disposed in the vicinity of the conveyance side roller 203. Since the temperature rise of the conveyance side roller 203 is transmitted to the detection units 19A, 19B, and 19C via the conveyance side shaft 204, the temperature can be detected with high accuracy.

  As a desirable aspect of the present embodiment, the thermocouples 11A, 11B, and 11C include a pair of thermocouple wires 21 and 22, and the thermistors 17A, 17B, and 17C include a pair of thermocouple wires 21, 22 are connected in series. With such a simple configuration, a thermoelectromotive force is selectively output from a thermocouple whose temperature has risen, so that the temperature can be accurately detected.

  One thermocouple strand 21 of the plurality of thermocouples 11A, 11B, 11C is electrically connected to the terminal 30a of the measuring instrument 30, and the other thermocouple strand 22 of the plurality of thermocouples 11A, 11B, 11C is , And electrically connected to the terminal 30b of the measuring instrument 30. According to this, since the plurality of thermocouples 11A, 11B, 11C and the plurality of thermistors 17A, 17B, 17C are connected to the two terminals 30a, 30b of the measuring instrument 30, a plurality of measuring instruments, There is no need to provide a terminal, and the temperature can be detected with a simple configuration.

  As mentioned above, although embodiment of this invention was described, this invention is not limited with the content of this embodiment, It can change suitably. For example, the temperature detection device 10 that measures the roller temperature of the belt conveyor device 103 is shown. However, the temperature detection device 10 is merely an example, and the temperature detection device 10 is an industrial machine such as a boiler, a prime mover, a transport machine, a power transmission machine, and a machine tool. Can be applied to the use of measuring temperatures at a plurality of locations. The thermocouples 11A, 11B, and 11C may use thermocouples other than the K thermocouple according to the measured temperature. The zero load resistance values and B constants of the thermistors 17A, 17B, and 17C are examples, and are not limited to those shown in the examples. The thermistors 17A, 17B, and 17C may be PTC (Positive Temperature Coefficient) thermistors.

DESCRIPTION OF SYMBOLS 10 Temperature detection apparatus 11A, 11B, 11C Thermocouple 15, 15a, 15b Compensation lead wire 17A, 17B, 17C Thermistor 19A, 19B, 19C, 19D, 19E, 19F Detector 20 Hot junction 21, 22 Thermocouple wire 30 Measuring instrument 30a, 30b Terminals 31a, 31b, 32a, 32b, 33a, 33b Connection unit 35 Display unit 100 Thermal power plant 101, 103 Belt conveyor device 102 Coal storage facility 104 Bunker 105 Pulverizer 106 Boiler 107 Denitration device 108 Electric dust collector 109 Denitration device DESCRIPTION OF SYMBOLS 110 Chimney 150 Coal 200 Roller drive part 201 Drive roller 202 Conveying belt 203, 203a, 203b, 203c Conveying side roller 204 Conveying side shaft 204a, 204b Bending part 204c End surface 204d Outer surface 204d Conveying side roller support Holding part 206 Return side roller 207 Return side shaft 208 Return side roller support part 210 Base 211 Leg part

Claims (7)

A temperature detection device that measures the temperature at multiple locations,
A detection unit including a thermocouple disposed on the object to be measured, and a thermistor connected in series to the thermocouple;
A temperature detection apparatus comprising: a plurality of the detection units connected in parallel; and a measuring device that detects a temperature rise of the temperature measurement target based on a thermoelectromotive force of the thermocouple.   The temperature detection device according to claim 1, wherein the resistance value of the thermistor decreases as the temperature increases.   In the state where the temperature of the detection unit is room temperature, the thermoelectromotive force of the thermocouple is not output to the measuring instrument, and when the temperature of the detection unit rises, the thermoelectromotive force of the thermocouple is output to the measuring instrument. The temperature detection device according to claim 2.   The said detection part is arrange | positioned in the vicinity of the said roller of the belt conveyor apparatus which has a conveyance belt and the roller which supports the said conveyance belt and is arrange | positioned in multiple numbers by the conveyance direction of the said conveyance belt. The temperature detection device according to any one of the above. The belt conveyor device has a shaft that rotatably supports the roller,
The temperature detection device according to claim 4, wherein the detection unit is disposed in contact with or close to the shaft. The thermocouple has a pair of thermocouple wires,
The temperature detection device according to any one of claims 1 to 5, wherein the thermistor is connected in series to either one of the pair of thermocouple strands.   One thermocouple strand of the plurality of thermocouples is electrically connected to the first terminal of the measuring instrument, and the other thermocouple strand of the plurality of thermocouples is connected to the second terminal of the measuring instrument. The temperature detection device according to claim 6, which is electrically connected.

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