Quick-response variable-flow-direction exhaust temperature thermocouple for three-axis industrial gas turbine

Abstract

The invention belongs to the field of energy power equipment, and particularly relates to a fast-response variable-flow-direction exhaust temperature measuring thermocouple for a three-axis industrial gas turbine, which comprises an outer sheath, a temperature measuring contact and an armored thermocouple wire, and is characterized in that the outer sheath is made of GH4099 high-temperature alloy and is of a thickened conical structure; a high-temperature fuel gas inlet and a high-temperature fuel gas exhaust port are formed in the outer sheath, and the high-temperature fuel gas inlet directly faces the flow direction of high-temperature gas flow; the outer sheath is made of GH4099 high-temperature alloy to be of a thickened conical structure, the material has excellent high-temperature strength and anti-fatigue performance and can bear long-term scouring of high-flow-rate fuel gas, meanwhile, airflow changes directions and decelerates in the sheath, dynamic pressure impact on a temperature measuring contact and an armored thermocouple wire is greatly reduced, and the temperature measuring contact and the armored thermocouple wire are protected from being damaged. The problem that the insertion section is broken due to insufficient strength of a traditional thin-sheath fast-response thermocouple is avoided, and the serious potential safety hazard that turbine blades are impacted with airflow after the thermocouple is broken can be effectively avoided by combining with the scene that the temperature measuring point of the three-axis gas turbine is located in front of a power turbine.

Description

Technical Field

[0001] This invention patent belongs to the field of energy and power equipment, specifically relating to a fast-response variable flow direction exhaust temperature measuring thermocouple for a three-axis industrial gas turbine. Background Technology

[0002] Gas turbines use fuel oil or natural gas as the combustion medium, and the combustion power drives the turbine to generate a continuous source of power. In industrial applications, they can be used to drive rotating machinery such as generators or compressors. The combustion of the medium inside a gas turbine generates high temperatures. To protect the high-temperature components of the turbine from damage, thermocouples are typically used for monitoring exhaust temperature and over-temperature protection. To ensure timely over-temperature protection, improving the thermocouple's response speed is essential. To improve measurement response speed, designers often design very thin thermocouple sheaths, typically less than 3mm, reducing the insulation effect of the sheath and thus increasing response speed. However, excessively thin sheaths can lead to reduced strength. For single-shaft gas turbines, since the exhaust temperature measurement point is located after the power turbine, the ambient flow velocity and pressure at the measurement location are relatively low, reducing the risk of the thermocouple breaking due to airflow impact. Furthermore, there are no turbine blades after the temperature measurement thermocouple, so even if the thermocouple breaks, there is no risk of blade damage. However, for a three-shaft gas turbine, the thermocouple is designed before the power turbine. The high-temperature gas flow velocity in this part is generally above 200m / s. If the thermocouple insertion part breaks due to insufficient strength, it will damage the power turbine blades and cause serious consequences. Therefore, it is necessary to invent an exhaust temperature measuring thermocouple that can respond quickly and has sufficient strength.

[0003] Therefore, the present invention provides a fast-response variable flow direction exhaust temperature measuring thermocouple for triaxial industrial gas turbines. Summary of the Invention

[0004] This invention proposes a fast-response variable-direction exhaust temperature measuring thermocouple for triaxial industrial gas turbines. The purpose is to ensure that the temperature measuring thermocouple for triaxial gas turbines can respond quickly and has sufficient strength. Using the structure of this invention to measure the exhaust temperature of triaxial industrial gas turbines has the advantages of fast response and high strength.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: A fast-response variable flow direction exhaust temperature measuring thermocouple for a three-shaft industrial gas turbine, comprising an outer sheath, a temperature measuring contact, and armored thermocouple wires. The outer sheath is made of GH4099 high-temperature alloy and has a thickened conical structure. The outer sheath has a high-temperature gas inlet and a high-temperature gas exhaust outlet. The high-temperature gas inlet faces the high-temperature gas flow direction, and the high-temperature gas exhaust outlet is located behind the high-temperature gas inlet and offset from it. The temperature measuring contact is fixed inside the outer sheath and is located between the high-temperature gas inlet and the high-temperature gas exhaust outlet. The high-temperature gas inlet enters the rear end of the outer sheath.

[0006] The outer sheath is provided with a positioning pin, the center line of which coincides with the center line of the high-temperature gas inlet, and the positioning pin is aligned with the thermocouple mounting base of the gas turbine.

[0007] The size of the high-temperature gas inlet is larger than the size of the high-temperature gas outlet. The armored wire is a high-temperature resistant armored wire with a diameter of 4mm. The front end of the outer sheath has a central drill hole with a diameter of 3.5mm. The rear end of the outer sheath is enlarged along the extension direction of the central drill hole to form an enlarged section with a diameter of 4.5mm.

[0008] A transition step is formed between the enlarged section and the central drill hole. The measuring end of the armored wire is provided with a double-hole corundum core with an outer diameter of 4mm. The double-hole corundum core is clamped at the transition step and fixed by high-temperature adhesive.

[0009] The root of the outer sheath is provided with a 55° conical sealing structure, which cooperates with the mounting base of the gas turbine housing to form a seal. The conical sealing structure secures the outer sheath to the mounting base by a mounting nut.

[0010] The outer sheath and the armored ferrule are connected by a welding seal. The total length of the armored ferrule and the outer sheath is 8 meters. The end of the armored ferrule away from the outer sheath is connected to a 2-meter-long high-temperature resistant flexible cable.

[0011] The connection between the armored ferrule and the high-temperature resistant flexible cable is fitted with a lead wire mating protective sleeve, and the inside of the lead wire mating protective sleeve is filled with high-temperature adhesive to fix it to the insulation of the high-temperature resistant flexible cable.

[0012] The outer diameter of the head at the front end of the outer sheath is 8mm. The high-temperature gas inlet is a rectangular opening at the front end of the outer sheath, with a height of 5mm. The temperature measuring contact is installed above the rectangular opening. The high-temperature gas exhaust port is a circular hole on the outer sheath opposite to the high-temperature gas inlet, with a diameter of 2.5mm.

[0013] The lead wire connection protective sleeve is made of 316L stainless steel with a wall thickness of not less than 1mm. Both ends of the sleeve are respectively sealed to the outer sheath of the armored wire and the outer sheath of the high-temperature resistant flexible cable by argon arc welding.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. The outer sheath is made of GH4099 high-temperature alloy with a thickened conical structure. This material has excellent high-temperature strength and fatigue resistance, and can withstand the long-term scouring of high-velocity gas. At the same time, the airflow changes direction and slows down inside the sheath, which greatly reduces the dynamic pressure impact on the temperature measuring contact and the armored thermocouple wire. This avoids the problem of the insertion section breaking due to insufficient strength of traditional thin-sheathed fast-response thermocouples. Combined with the scenario where the temperature measuring point of a three-shaft gas turbine is located in front of the power turbine, it can effectively avoid the serious safety hazard of the thermocouple breaking and hitting the turbine blade with the airflow.

[0016] 2. The outer sheath and armored thermocouple wires are welded and sealed together. The tapered sealing structure at the root, combined with the installation nut, ensures a reliable seal with the gas turbine mounting base, preventing high-temperature gas from seeping into the sheath and corroding the components. The design of the lead wire connecting to the protective sleeve and the internal high-temperature potting compound protects the welded joint between the armored thermocouple wires and the high-temperature resistant flexible cable, avoiding wire breakage or insulation failure caused by vibration or oil contamination, and ensuring that the thermocouple maintains stable performance even after running continuously for many hours. Attached Figure Description

[0017] Figure 1 This is a structural diagram of the thermocouple measuring section for exhaust temperature measurement.

[0018] Figure 2 This is a schematic diagram showing the change in the flow direction of high-temperature gas flow inside a thermocouple.

[0019] Figure 3 This is a structural diagram of the exhaust temperature measuring thermocouple. Detailed Implementation

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] The outer sheath is made of GH4099 high-temperature alloy, and high-temperature gas inlet and outlet ports are opened on the sheath. The structural diagram of the exhaust temperature measuring thermocouple is shown below. Figure 1As shown, the front end of the high-temperature alloy sheath tube is tapered, with an outer diameter of 8mm. A 3.5mm diameter central bore is drilled along the axial direction at the front end to accommodate the temperature measuring contact and the measuring end of the armored coupler wire. Extending backward along the central bore, the rear end of the sheath is enlarged to form a 4.5mm diameter enlarged section. A natural annular transition step is formed between the enlarged section and the central bore. This step is used for the positioning and installation of the double-hole corundum core.

[0022] The root of the sheath is machined into a 55° conical sealing structure. The roughness of the conical surface ensures a tight fit with the conical surface of the gas turbine housing mounting base, achieving a reliable seal. At the same time, a locating pin is integrally machined near the root of the sheath housing. The center line of the locating pin is completely coincident with the center line of the high-temperature gas inlet that will be opened later. The locating pin has a rectangular cross-section and protrudes 3mm from the outer wall of the sheath. It is used to align with the keyway of the gas turbine thermocouple mounting base during installation.

[0023] A rectangular high-temperature gas inlet is provided on the windward side of the conical head at the front of the sheath. The opening height is 5mm and the length is adapted to the circumferential curvature of the sheath head to ensure that the inlet can fully receive the high-temperature airflow. On the leeward side of the sheath opposite to the inlet, 15mm behind the inlet, a circular high-temperature gas exhaust port with a diameter of 2.5mm is provided. The flow area of ​​the inlet is larger than that of the exhaust port to ensure that the airflow has sufficient residence time inside the sheath to contact the temperature measuring contact.

[0024] For a detailed diagram of the flow direction change of high-temperature gas flow within the thermocouple, please refer to [link / reference]. Figure 2 The high-temperature gas flow enters the thermocouple sheath from the inlet along the axial direction of the gas turbine. Then, under the obstruction of the sheath's outer shell structure, it quickly changes direction, changing from flowing along the axial direction of the gas turbine to flowing radially, and finally exits from the high-temperature gas exhaust port. During this process, the airflow velocity slows down, which can ensure full contact with the thermocouple temperature measuring contacts without damaging the temperature measuring contacts due to dynamic pressure impact.

[0025] The overall structure diagram of the exhaust temperature measuring thermocouple is as follows: Figure 3 As shown, the 4mm diameter high-temperature resistant armored thermocouple wire has an external mounting nut for fixing the thermocouple to the gas turbine housing mounting base. The total length of the armored thermocouple wire and the high-temperature alloy sheath is 8 meters, which can ensure that it can be bent and fixed at any time near the gas turbine body without being affected by the high temperature of the gas turbine. A 2-meter long high-temperature resistant flexible cable is designed at the tail of the thermocouple for convenient wiring in the junction box. The armored thermocouple wire and the high-temperature resistant flexible cable are welded into the lead wire butt protective sleeve and sealed with high-temperature glue to ensure insulation performance.

[0026] The specific operation process of this fast-response variable-direction exhaust temperature measuring thermocouple in a gas turbine is as follows:

[0027] Installation and positioning: First, insert the thermocouple into the special mounting base on the gas turbine housing through the 55° conical sealing structure at its base, and tighten it with the mounting nut to ensure a reliable seal. At this time, align the positioning pin on the sheath housing with the keyway on the mounting base to ensure that the gas inlet of the thermocouple is accurately aligned with the axial high-temperature gas flow direction of the gas turbine.

[0028] Airflow introduction and reversal: When the gas turbine is running, the high-temperature and high-speed gas flow is directed towards the thermocouple inlet and enters the thermocouple sheath. Since the inlet and outlet are located on both sides of the temperature measuring contact, the gas flow entering the thermocouple sheath is rapidly reversed by the sheath structure, changing from axial flow along the gas turbine to radial flow, and the flow velocity is significantly reduced.

[0029] Heat exchange and temperature measurement: The high-temperature gas, after its flow rate slows down, surrounds and fully washes the thermocouple temperature sensing point located at the center of the sheath. The thermocouple point quickly absorbs the heat from the gas flow, and its temperature rapidly approaches the actual gas temperature. The temperature difference between the cold and hot ends of the thermocouple generates a thermoelectric potential, which converts the temperature change into a corresponding millivolt-level electrical signal. This variable flow structure ensures both sufficient and rapid heat exchange, achieving a fast response to temperature changes, while also avoiding the direct impact of high-speed gas flow and protecting the temperature sensing point.

[0030] Airflow discharge and signal transmission: After heat exchange, the gas is smoothly discharged from the sheath through a small high-temperature gas exhaust port and returns to the main airflow channel. At the same time, the generated thermoelectric potential signal is conducted through the armored thermocouple wire to the high-temperature resistant flexible cable at the tail of the thermocouple, and finally transmitted to the external junction box and control system. The control board collects and processes the signal for real-time status monitoring and over-temperature protection control of the unit.

[0031] Structural protection: Throughout the process, the thickened conical sheath made of GH4099 high-temperature alloy provides robust mechanical protection for the internal armored thermocouple wires and temperature sensing contacts, enabling them to withstand the harsh environment of high temperature, high pressure and high flow rate gas, greatly reducing the risk of thermocouple breakage and damage to the power turbine blades.

Claims

1. A fast-response variable-direction exhaust temperature measuring thermocouple for a three-shaft industrial gas turbine, characterized in that: The device includes an outer sheath, temperature measuring contacts, and armored thermocouples. The outer sheath is made of GH4099 high-temperature alloy and has a thickened conical structure. The outer sheath has a high-temperature gas inlet and a high-temperature gas outlet. The high-temperature gas inlet faces the direction of the high-temperature gas flow, and the high-temperature gas outlet is located behind the high-temperature gas inlet and offset from it. The temperature measuring contacts are fixed inside the outer sheath and are located between the high-temperature gas inlet and the high-temperature gas outlet. The high-temperature gas inlet enters the rear end of the outer sheath.

2. The fast-response variable-direction exhaust temperature measuring thermocouple for a triaxial industrial gas turbine according to claim 1, characterized in that: The outer sheath is provided with a positioning pin, the center line of which coincides with the center line of the high-temperature gas inlet, and the positioning pin is aligned with the thermocouple mounting base of the gas turbine.

3. The fast-response variable-direction exhaust temperature measuring thermocouple for a three-shaft industrial gas turbine according to claim 1, characterized in that: The size of the high-temperature gas inlet is larger than the size of the high-temperature gas outlet. The armored wire is a high-temperature resistant armored wire with a diameter of 4mm. The front end of the outer sheath has a central drill hole with a diameter of 3.5mm. The rear end of the outer sheath is enlarged along the extension direction of the central drill hole to form an enlarged section with a diameter of 4.5mm.

4. The fast-response variable-direction exhaust temperature measuring thermocouple for a three-shaft industrial gas turbine according to claim 3, characterized in that: A transition step is formed between the enlarged section and the central drill hole. The measuring end of the armored wire is provided with a double-hole corundum core with an outer diameter of 4mm. The double-hole corundum core is clamped at the transition step and fixed by high-temperature adhesive.

5. The fast-response variable-direction exhaust temperature measuring thermocouple for a three-shaft industrial gas turbine according to claim 3, characterized in that: The root of the outer sheath is provided with a 55° conical sealing structure, which cooperates with the mounting base of the gas turbine housing to form a seal. The conical sealing structure secures the outer sheath to the mounting base by a mounting nut.

6. The fast-response variable-direction exhaust temperature measuring thermocouple for a three-shaft industrial gas turbine according to claim 5, characterized in that: The outer sheath and the armored ferrule are connected by a welding seal. The total length of the armored ferrule and the outer sheath is 8 meters. The end of the armored ferrule away from the outer sheath is connected to a 2-meter-long high-temperature resistant flexible cable.

7. The fast-response variable-direction exhaust temperature measuring thermocouple for a triaxial industrial gas turbine according to claim 6, characterized in that: The connection between the armored ferrule and the high-temperature resistant flexible cable is fitted with a lead wire mating protective sleeve, and the inside of the lead wire mating protective sleeve is filled with high-temperature adhesive to fix it to the insulation of the high-temperature resistant flexible cable.

8. The fast-response variable-direction exhaust temperature measuring thermocouple for a three-shaft industrial gas turbine according to claim 1, characterized in that: The outer diameter of the head at the front end of the outer sheath is 8mm. The high-temperature gas inlet is a rectangular opening at the front end of the outer sheath, with a height of 5mm. The temperature measuring contact is installed above the rectangular opening. The high-temperature gas exhaust port is a circular hole on the outer sheath opposite to the high-temperature gas inlet, with a diameter of 2.5mm.

9. A fast-response variable-direction exhaust temperature measuring thermocouple for a three-shaft industrial gas turbine according to claim 8, characterized in that: The lead wire connection protective sleeve is made of 316L stainless steel with a wall thickness of not less than 1mm. Both ends of the sleeve are respectively sealed to the outer sheath of the armored wire and the outer sheath of the high-temperature resistant flexible cable by argon arc welding.

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