CN212273956U - Device for monitoring wall temperature of heat exchange tube in furnace by adopting compressed air cooling protection - Google Patents

Device for monitoring wall temperature of heat exchange tube in furnace by adopting compressed air cooling protection Download PDF

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Publication number
CN212273956U
CN212273956U CN202022122814.6U CN202022122814U CN212273956U CN 212273956 U CN212273956 U CN 212273956U CN 202022122814 U CN202022122814 U CN 202022122814U CN 212273956 U CN212273956 U CN 212273956U
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heat exchange
exchange tube
thermocouple
compressed gas
boiler
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鲍听
张光学
楼玉民
关键
沈利
谢增孝
闫飞
郭恩陶
严小华
杨扬
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Zhejiang Energy Group Research Institute Co Ltd
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Zhejiang Energy Group Research Institute Co Ltd
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Abstract

The utility model relates to a device for monitoring the wall temperature of a heat exchange tube in a furnace by adopting compressed air cooling protection, which comprises a heat conducting block, a compressed gas tube, a thermocouple and a boiler heat exchange tube; the outer wall surface of the boiler heat exchange tube is provided with a heat conduction block, a compressed gas tube is fixed above the heat conduction block, and a thermocouple penetrates through the compressed gas tube and is inserted into the heat conduction block; the outer surfaces of the compressed gas pipe and the heat conducting block are coated with a zirconia thermal barrier layer; the heat conducting block is made of the same metal material as the boiler heat exchange tube, the width of the heat conducting block is 50% -85% of the diameter of the boiler heat exchange tube, the ratio of the height to the width is 1-1.5, and the thickness is 5mm-12 mm. The utility model has the advantages that: the utility model discloses a heat conduction piece and thermocouple are installed at boiler heat exchange tube outer wall, and the thermal resistance between thermocouple and boiler heat exchange tube is very little, and because heat conduction piece surface coating zirconia thermal barrier layer, the thermal resistance between thermocouple and the high temperature flue gas is great, therefore the thermocouple can accurately reflect boiler heat exchange tube pipe wall temperature, and measurement accuracy is high.

Description

Device for monitoring wall temperature of heat exchange tube in furnace by adopting compressed air cooling protection
Technical Field
The utility model relates to a temperature measurement technical field, in particular to can carry out the device monitored to the boiler heat exchange tube in the stove.
Background
The utility boiler is widely used in the power plant production field of China, and a large number of heating surfaces including a platen superheater, a high-temperature superheater, a reheater and the like need to be arranged in a hearth in order to obtain high-temperature high-pressure steam for driving a steam turbine to do work. Taking an ultra-supercritical coal-fired boiler as an example, the temperature of high-temperature high-pressure steam in a superheater tube group is as high as 500-600 ℃, and the temperature of high-temperature flue gas outside the tube group is as high as 800-1000 ℃. The heat exchange tube of the boiler has severe working conditions, the temperature of the local tube wall is close to the upper limit of the temperature tolerance of the metal material, and under the conditions of improper operation or blockage of internal foreign matters and the like, overheating, overtemperature and even tube explosion accidents are easy to happen. Therefore, it is necessary to monitor and measure the wall temperature of the boiler heat exchange tube of the utility boiler to improve the safety of the boiler.
Because the temperature of the boiler heat exchange tube and the external flue gas is very high, the direct temperature measurement of the boiler heat exchange tube in the boiler is not easy, and the lead of the conventional thermocouple is easy to oxidize, deform or even break at high temperature, so that the temperature measuring element is damaged. At present, a wall temperature monitoring method commonly adopted by a power plant is to arrange a thermocouple at the inlet and outlet sections of a heat exchange tube at the top of the furnace, and the service life of the thermocouple is greatly prolonged because the thermocouple is outside a hearth and is not flushed by high-temperature flue gas, but the actual wall temperature of the heat exchange tube inside the furnace cannot be reflected by the measuring method.
In summary, in order to ensure the safe operation of the boiler and prevent the tube explosion of the heating surface, it is necessary to develop a device for effectively monitoring the wall temperature of the heat exchange tube of the boiler in the boiler for a long time.
SUMMERY OF THE UTILITY MODEL
The utility model aims at overcoming the defects in the prior art and providing a device for monitoring the wall temperature of a heat exchange tube in a furnace, which is protected by cooling compressed air.
The device for monitoring the wall temperature of the heat exchange tube in the furnace by adopting compressed air cooling protection comprises a heat conducting block, a compressed gas tube, a thermocouple and a boiler heat exchange tube; the outer wall surface of the boiler heat exchange tube is provided with a heat conduction block, a compressed gas tube is fixed above the heat conduction block, and a thermocouple penetrates through the compressed gas tube and is inserted into the heat conduction block; the outer surfaces of the compressed gas pipe and the heat conducting block are coated with a zirconia thermal barrier layer.
Preferably, the method comprises the following steps: the heat conducting block is made of the same metal material as the boiler heat exchange tube, the width of the heat conducting block is 50% -85% of the diameter of the boiler heat exchange tube, the ratio of the height to the width is 1-1.5, and the thickness is 5mm-12 mm.
Preferably, the method comprises the following steps: the heat conducting block is connected with the boiler heat exchange tube in a full-welding mode.
Preferably, the method comprises the following steps: the upper end of the heat conducting block is provided with a small hole, a thermocouple is inserted into the small hole, and the thermocouple is fixed in the heat conducting block through a fastening bolt.
Preferably, the method comprises the following steps: the compressed gas pipe is made of heat-resistant stainless steel, the pipe diameter is 20mm-35mm, and a compressed gas exhaust port is arranged at the lower part of the compressed gas pipe.
Preferably, the method comprises the following steps: the thickness of the zirconia thermal barrier layer is 0.1mm-0.3 mm.
Preferably, the method comprises the following steps: the thermocouple is K-type nickel chromium-nickel silicon thermocouple or S-type thermocouple.
Preferably, the method comprises the following steps: the upper end of the compressed gas pipe is connected with compressed air or compressed nitrogen.
Preferably, the method comprises the following steps: the upper pipe body of the compressed gas pipe is arranged in parallel with the boiler heat exchange pipe, and the bottom pipe body of the compressed gas pipe inclines towards the boiler heat exchange pipe and is connected with the heat conducting block.
The utility model has the advantages that:
1. the utility model discloses a heat conduction piece and thermocouple are installed at boiler heat exchange tube outer wall, and the thermal resistance between thermocouple and boiler heat exchange tube is very little, and because heat conduction piece surface coating zirconia thermal barrier layer, the thermal resistance between thermocouple and the high temperature flue gas is great, therefore the thermocouple can accurately reflect boiler heat exchange tube pipe wall temperature, and measurement accuracy is high.
2. The utility model discloses a thermocouple adopts the compressed gas cooling, and the compressed gas outside of tubes coating has the zirconia thermal barrier layer that has thermal-insulated effect, and thermocouple wire temperature control is in safety range, and long-term measurement can be realized to measuring device life-span extension, and guarantee boiler safe and reliable moves.
3. The device of the utility model has the advantages of simple and reasonable structure, can use low-priced K type thermocouple, and the compressed gas cost is not high and can acquire on the spot, consequently has lower working costs and better maneuverability.
Drawings
FIG. 1 is a schematic structural diagram of a device for monitoring the wall temperature of a heat exchange tube in a furnace, which is cooled and protected by compressed air;
FIG. 2 is a front view of a device for monitoring the temperature of the wall of a heat exchange tube in a furnace protected by cooling with compressed air;
FIG. 3 is a side view of a device for monitoring the temperature of the wall of a heat exchange tube in a furnace protected by cooling with compressed air;
FIG. 4 is a top view of a device for monitoring the temperature of the walls of heat exchange tubes in a furnace with compressed air cooling protection;
FIG. 5 is a cross-sectional view taken along line A-A of FIG. 2;
FIG. 6 is a cross-sectional view taken along line B-B of FIG. 4;
FIG. 7 is a graph of the B-B profile temperature field of FIG. 4 obtained by numerical simulation of the apparatus;
fig. 8 is a temperature field profile of the a-a section of fig. 2 obtained by numerical simulation of the device.
Description of reference numerals: 1-a heat conducting block; 2-a compressed gas pipe; 3-compressed gas vent; 4-a thermocouple; 5-boiler heat exchange tubes; 6-fastening the bolt.
Detailed Description
The present invention will be further described with reference to the following examples. The following description of the embodiments is merely provided to aid in understanding the invention. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.
Example one
The device for monitoring the wall temperature of the heat exchange tube in the furnace by adopting compressed air cooling protection comprises a heat conduction block 1, a compressed gas tube 2, a compressed gas exhaust port 3, a thermocouple 4 and a boiler heat exchange tube 5. The outer wall surface of a boiler heat exchange tube 5 is provided with a heat conduction block 1, a compressed gas tube 2 is fixed above the heat conduction block 1, and a thermocouple 4 penetrates through the compressed gas tube 2 and then is inserted into the heat conduction block 1.
The heat conducting block 1 is made of the same metal material as the boiler heat exchange tube, the width of the heat conducting block is 50-85% of the diameter of the boiler heat exchange tube, the ratio of the height to the width is 1-1.5, and the thickness is 5-12 mm; the heat conducting block 1 is connected with a boiler heat exchange tube 5 in a full-welding mode; the upper end of the heat conducting block 1 is provided with a small hole for inserting the thermocouple 4, and the thermocouple 4 is fixed by a fastening bolt 6.
The compressed gas pipe 2 is made of heat-resistant stainless steel, the pipe diameter is 20mm-35mm, the bottom of the compressed gas pipe is connected with the heat conducting block 1, the lower part of the compressed gas pipe 2 is provided with a compressed gas exhaust port 3, and compressed air exhausted from the compressed gas exhaust port 3 cannot blow to the heat conducting block.
The outer surfaces of the compressed gas pipe 2 and the heat conducting block 1 are coated with a zirconia thermal barrier layer with the thickness of 0.1mm-0.3 mm.
The thermocouple 4 for measuring the wall temperature may be a common K-type nickel-chromium-nickel-silicon thermocouple, or may be an S-type thermocouple or other types of thermocouples.
The upper end of the compressed gas pipe 2 is connected with compressed air or compressed nitrogen, and the pressure is 0.3MPa-0.6 MPa.
When the thermocouple is in work, compressed gas flows in from the upper end of the compressed gas pipe to cool the lead of the thermocouple, and the zirconia thermal barrier layer is used for insulating heat, so that all leads of the thermocouple are ensured to be thermally shielded, and the thermocouple can not be burnt and damaged when working in a safe temperature range. The device can reliably operate for a long time, and realizes continuous monitoring of the wall temperature of the heat exchange tube of the boiler in the boiler.
Example two
The device for monitoring the wall temperature of the heat exchange tube in the furnace cooled and protected by the compressed air comprises the following installation and use methods: the heat conducting block 1 is connected with the boiler heat exchange tube 5 through welding, and the thermocouple 4 is fixed inside the heat conducting block 1 through the fastening bolt 6, so that the contact thermal resistance between the thermocouple 4 and the boiler heat exchange tube 5 is reduced to the minimum. Meanwhile, because the outer surfaces of the compressed gas pipe 2 and the heat conducting block 1 are coated with the zirconia thermal barrier layer, the convection, heat conduction and radiation influences of high-temperature flue gas on the boiler heat exchange pipe 5 are reduced, and therefore the thermocouple 4 is very close to the wall temperature of the boiler heat exchange pipe 5. Compressed gas is connected from the upper end of the compressed gas pipe 2, the initial pressure is 0.3MPa-0.6MPa, the gas flows from top to bottom, the lead of the thermocouple 4 is cooled, and then the gas is discharged from the compressed gas exhaust port 3. Because the outer surface of the compressed gas pipe 2 is coated with the zirconia thermal barrier layer, the heating of high-temperature flue gas outside the pipe to the gas inside the compressed gas pipe 2 is reduced, and the thermocouple 4 is ensured to be in a safe temperature range below 700 ℃, so that the device can reliably operate for a long time, and the continuous monitoring of the wall temperature of the heat exchange pipe of the boiler in the boiler is realized.
An ANSYS Fluent is adopted to carry out flowing and heat transfer numerical simulation experiments on a device for monitoring the wall temperature of the heat exchange tube in the boiler, which is cooled and protected by compressed air, and the measured temperature in a heat conducting block and the temperature at the wall thickness of the heat exchange tube 1/2 of the boiler are contrastively analyzed:
1) computing boundary conditions
Simulating the flowing and heat transfer process in an actual boiler, wherein the incoming flue gas velocity is 10m/s, the temperature is 900 ℃, the steam velocity in a heat receiver pipe (a boiler heat exchange pipe) is 13m/s, the temperature is 600 ℃, and the air flow velocity in a cooling pipe (a compressed gas pipe) is 20m/s and the temperature is 25 ℃;
2) calculation model
The turbulence model is Realizable k-, and the radiation model adopts a P1 model;
through calculation, the temperature of the wall thickness of the heat exchange tube 1/2 of the boiler is 641 ℃, the temperature in the heat conducting block is 662 ℃, the difference between the two temperatures is only 21 ℃, and the measurement requirement of the heating surface of the boiler can be met.

Claims (9)

1. The utility model provides an adopt device of interior heat exchange tube wall temperature monitoring of compressed air cooling protection which characterized in that: comprises a heat conducting block (1), a compressed gas pipe (2), a thermocouple (4) and a boiler heat exchange pipe (5); the outer wall surface of a boiler heat exchange tube (5) is provided with a heat conduction block (1), a compressed gas tube (2) is fixed above the heat conduction block (1), and a thermocouple (4) penetrates through the compressed gas tube (2) and is inserted into the heat conduction block (1); the outer surfaces of the compressed gas pipe (2) and the heat conducting block (1) are coated with a zirconia thermal barrier layer.
2. The apparatus for monitoring the wall temperature of a heat exchange tube in a furnace protected by cooling with compressed air according to claim 1, wherein: the heat conducting block (1) is made of the same metal material as the boiler heat exchange tube, the width of the heat conducting block is 50% -85% of the diameter of the boiler heat exchange tube, the ratio of the height to the width is 1-1.5, and the thickness is 5mm-12 mm.
3. The apparatus for monitoring the wall temperature of a heat exchange tube in a furnace protected by cooling with compressed air according to claim 1, wherein: the heat conducting block (1) is connected with the boiler heat exchange tube (5) in a full-welding mode.
4. The apparatus for monitoring the wall temperature of a heat exchange tube in a furnace protected by cooling with compressed air according to claim 1, wherein: the upper end of the heat conducting block (1) is provided with a small hole, a thermocouple (4) is inserted into the small hole, and the thermocouple (4) is fixed in the heat conducting block (1) through a fastening bolt (6).
5. The apparatus for monitoring the wall temperature of a heat exchange tube in a furnace protected by cooling with compressed air according to claim 1, wherein: the compressed gas pipe (2) is made of heat-resistant stainless steel, the pipe diameter is 20mm-35mm, and a compressed gas exhaust port (3) is arranged at the lower part of the compressed gas pipe (2).
6. The apparatus for monitoring the wall temperature of a heat exchange tube in a furnace protected by cooling with compressed air according to claim 1, wherein: the thickness of the zirconia thermal barrier layer is 0.1mm-0.3 mm.
7. The apparatus for monitoring the wall temperature of a heat exchange tube in a furnace protected by cooling with compressed air according to claim 1, wherein: the thermocouple (4) adopts a K-type nickel-chromium-nickel-silicon thermocouple or an S-type thermocouple.
8. The apparatus for monitoring the wall temperature of a heat exchange tube in a furnace protected by cooling with compressed air according to claim 1, wherein: the upper end of the compressed gas pipe (2) is connected with compressed air or compressed nitrogen.
9. The apparatus for monitoring the wall temperature of a heat exchange tube in a furnace protected by cooling with compressed air according to claim 1, wherein: the upper pipe body of the compressed gas pipe (2) is arranged in parallel with the boiler heat exchange pipe (5), and the bottom pipe body of the compressed gas pipe (2) inclines towards the boiler heat exchange pipe (5) and is connected with the heat conducting block (1).
CN202022122814.6U 2020-09-24 2020-09-24 Device for monitoring wall temperature of heat exchange tube in furnace by adopting compressed air cooling protection Active CN212273956U (en)

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CN202022122814.6U CN212273956U (en) 2020-09-24 2020-09-24 Device for monitoring wall temperature of heat exchange tube in furnace by adopting compressed air cooling protection

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CN202022122814.6U CN212273956U (en) 2020-09-24 2020-09-24 Device for monitoring wall temperature of heat exchange tube in furnace by adopting compressed air cooling protection

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112066353A (en) * 2020-09-24 2020-12-11 浙江浙能技术研究院有限公司 Device and method for monitoring wall temperature of heat exchange tube in furnace by adopting compressed air cooling protection

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112066353A (en) * 2020-09-24 2020-12-11 浙江浙能技术研究院有限公司 Device and method for monitoring wall temperature of heat exchange tube in furnace by adopting compressed air cooling protection

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