Long-life electric radiant tube heater

Abstract

This invention proposes a long-life electric radiant tube heater, comprising an iron-chromium-nickel alloy heating wire, a ceramic body frame, a radiant tube sleeve, and heat dissipation fins. The iron-chromium-nickel alloy heating wire is threaded onto the ceramic body frame, and the iron-chromium-nickel alloy heating wire and the ceramic body form the electric heating core of the electric radiant tube. The radiant tube sleeve is fitted over the outside of the ceramic body frame, and the heat dissipation fins are fixed to the outer wall of the radiant tube sleeve to enhance heat dissipation. The long-life electric radiant tube heater proposed in this invention, by adding heat dissipation fins to the outside of the radiant tube sleeve, can improve heat dissipation efficiency, reduce the heat load on the material, and thus extend its service life.

Description

Technical Field

[0001] This utility model relates to the field of radiation tube structure technology, and in particular to a long-life electric radiation tube heater. Background Technology

[0002] Radiant tubes are indirect heating elements widely used in industrial furnaces. Traditional gas-fired radiant tubes have many problems in industrial applications, such as high flue gas temperature, uneven temperature distribution on the tube wall, and large amounts of combustion products. Although technical optimization measures have been proposed for gas-fired radiant tubes, NOx emissions remain a problem due to the use of coal gas. Electric radiant tubes not only improve heating efficiency but also solve the NOx emission problem at its source.

[0003] Currently, industrial electric radiant tubes are mainly squirrel-cage type. These tubes consist primarily of a heating wire, a ceramic frame, and a radiant tube sleeve. The sleeve radiates heat generated by the heating wire to the workpiece being heated. The heat transfer efficiency and service life of the sleeve directly affect the performance of the electric radiant tube, and these factors are highly dependent on its structure and materials.

[0004] The existing radiant tube heaters have low heat dissipation efficiency and low heat exchange capacity of the radiant tube sleeve, resulting in a high heat load on the radiant tube sleeve material and a short service life of the radiant tube. Utility Model Content

[0005] The main objective of this invention is to provide a long-life electric radiant tube heater, which aims to improve the heat dissipation efficiency of the electric radiant tube and thus extend its service life.

[0006] To achieve the above objectives, this utility model provides a long-life electric radiant tube heater, comprising an iron-chromium-nickel alloy heating wire, a ceramic frame, a radiant tube sleeve, and heat dissipation fins, wherein...

[0007] The iron-chromium-nickel alloy heating wire is threaded through the ceramic body skeleton. The iron-chromium-nickel alloy heating wire and the ceramic body form the electric heating core of the electric radiant tube. The radiant tube sleeve is fitted on the outside of the ceramic body skeleton, and the heat dissipation fins are fixed on the outer wall of the radiant tube sleeve to enhance heat dissipation.

[0008] Preferably, the iron-chromium-nickel alloy heating wire comprises multiple U-shaped heating wires.

[0009] Preferably, the heat dissipation fins are provided in multiple ways.

[0010] Preferably, the outer wall of the radiant tube sleeve is coated with a high-temperature resistant alloy coating.

[0011] Preferably, the high-temperature resistant alloy coating comprises an anti-oxidation layer, a thermal stress buffer layer, and an anti-corrosion layer arranged sequentially from the inside out.

[0012] Preferably, the thickness of the antioxidant layer is 0.3mm to 3mm, the thickness of the thermal stress buffer layer is 0.5mm to 2.0mm, and the thickness of the anti-corrosion layer is 1.0mm to 3.0mm.

[0013] Preferably, the ceramic body skeleton includes multiple parallel mullite ceramic sheets and a mullite ceramic shaft passing through the axial direction of all the mullite ceramic sheets, and an iron-chromium-nickel alloy heating wire passing through the mullite ceramic sheets.

[0014] Preferably, the side of the electric heating core closest to the power supply device is its power supply end, and the side furthest from the power supply device is its heating end, with all mullite ceramic sheets arranged at unequal intervals along the length of the electric heating core.

[0015] Preferably, the mullite ceramic sheets are densely distributed near the heating end and sparsely distributed near the heating end.

[0016] Preferably, the heat dissipation fins are arranged in multiple rows on the outer side wall of the radiant tube sleeve, and each row includes multiple heat dissipation fins arranged at intervals.

[0017] The long-life electric radiant tube heater proposed in this utility model has the following beneficial effects:

[0018] 1. Heat dissipation fins are added to the outside of the radiant tube sleeve, which can improve heat dissipation efficiency, reduce the thermal load on the material, and thus extend its service life.

[0019] 2. The surface of the radiant tube sleeve is coated with a high-temperature resistant alloy coating, which delays high-temperature oxidation and thermal fatigue, and improves the service life of the radiant tube sleeve. Furthermore, the high-temperature resistant alloy coating uses materials with different coefficients of thermal expansion from the inside out, reducing the risk of cracking caused by thermal stress concentration.

[0020] 3. The iron-chromium-nickel alloy heating wire is supported by a ceramic body skeleton, which makes the heating wire less prone to deformation and also ensures high heating efficiency.

[0021] 4. This long-life electric radiant tube heater has the advantages of simple structure, easy implementation, and stable and reliable operation. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the long-life electric radiation tube heater of this utility model.

[0023] In the diagram, 1-Iron-chromium-nickel alloy heating wire, 2-Ceramic body skeleton, 3-Radiation tube sleeve, 4-Heat dissipation fins.

[0024] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0026] It should be noted that in the description of this utility model, the terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] Reference Figure 1 In this preferred embodiment, a long-life electric radiant tube heater includes an iron-chromium-nickel alloy heating wire 1, a ceramic body frame 2, a radiant tube sleeve 3, and heat dissipation fins 4, wherein...

[0028] The iron-chromium-nickel alloy heating wire 1 is threaded through the ceramic body frame 2. The iron-chromium-nickel alloy heating wire 1 and the ceramic body form the electric heating core of the electric radiant tube. The radiant tube sleeve 3 is sleeved on the outside of the ceramic body frame 2. The heat dissipation fins 4 are fixed to the outer wall of the radiant tube sleeve 3 (which can be fixed by welding) to enhance heat dissipation.

[0029] In this embodiment, the iron-chromium-nickel alloy heating wire 1 includes multiple U-shaped heating wires. Multiple heat dissipation fins 4 are provided.

[0030] Furthermore, the outer wall of the radiant tube sleeve 3 is coated with a high-temperature resistant alloy coating. This coating can delay high-temperature oxidation and thermal fatigue. The high-temperature resistant alloy coating comprises, from the inside out, an anti-oxidation layer, a thermal stress buffer layer, and an anti-corrosion layer. All three layers—the anti-oxidation layer, the thermal stress buffer layer, and the anti-corrosion layer—are made from conventional materials available in the prior art. The anti-oxidation layer's main component is alumina, characterized by its high melting point, low oxygen diffusivity, and ability to block oxygen permeation. The middle layer's main component is a metal-ceramic composite material, which mitigates the difference in thermal expansion coefficients between the matrix and the ceramic layer through the ductility of the metallic phase. The outer layer's main component is silicon nitride, which is resistant to acid and alkali corrosion and suitable for chemical or molten salt environments. It is internally doped with 2-5% rare earth oxides as a modifier, which improves the coating's self-healing ability and allows it to fill microcracks at high temperatures.

[0031] The radiant tube sleeve 3 employs three types of gradient functional materials to reduce the risk of breakage caused by thermal stress concentration (the radiant tube sleeve 3 itself is composed of three different materials, and its outer high-temperature alloy coating also has three layers). The design principle mainly follows the thermal stress relief mechanism and targeted solutions for failure modes. The thermal stress relief mechanism is mainly achieved by adjusting the material composition so that the coefficient of thermal expansion of the tube wall gradually changes from the inner layer (high-temperature side) to the outer layer (low-temperature side), matching the thermal expansion behavior at the operating temperature and reducing the concentration of thermal stress between layers. The targeted solution for failure modes mainly addresses the issue that traditional homogeneous materials, due to the large difference in the coefficients of thermal expansion between the inner and outer layers, cause stress concentration at the interface, leading to cracks. The gradient material eliminates abrupt stress through a continuous transition.

[0032] The design of gradient materials mainly consists of three parts: an inner anti-oxidation layer, a middle thermal stress buffer layer, and an outer anti-corrosion layer. The inner anti-oxidation layer can be made of high-melting-point ceramic with a thermal expansion coefficient of 4.5 × 10⁻⁶. -6 / ℃; The intermediate thermal stress buffer layer is made of ceramic-metal gradient hybrid with a thermal expansion coefficient of 5×10. -6 / ℃ gradually transitions to 14×10 -6 / ℃; the outer anti-corrosion layer is made of high-temperature alloy with a coefficient of thermal expansion of 14×10. -6 / ℃, combining high-temperature strength and toughness.

[0033] Specifically, in this embodiment, the thickness of the antioxidant layer is 0.3mm to 3mm, the thickness of the thermal stress buffer layer is 0.5mm to 2.0mm, and the thickness of the anti-corrosion layer is 1.0mm to 3.0mm.

[0034] Specifically, in this embodiment, the ceramic body skeleton 2 includes multiple parallel mullite ceramic sheets and a mullite ceramic shaft passing through the axial direction of all the mullite ceramic sheets, and the iron-chromium-nickel alloy heating wire 1 passes through the mullite ceramic sheets.

[0035] The side of the electric heating core closest to the power supply device is its power supply end, and the side furthest from the power supply device is its heating end. All mullite ceramic sheets are arranged at unequal intervals along the length of the electric heating core. The mullite ceramic sheets are densely distributed near the power supply end and sparsely distributed near the heating end. The denser distribution at the power supply end is primarily because the ceramic sheets better support the electric heating core. The sparser distribution at the heating end is mainly because this allows for better radiant transfer of the heat generated by the electric heating core to the radiant tube sleeve 3. If the ceramic sheets were too densely distributed, it would hinder heat transfer.

[0036] In this embodiment, multiple rows of heat dissipation fins 4 are arranged on the outer wall of the radiant tube sleeve 3, and each row includes multiple spaced heat dissipation fins 4. By adding heat dissipation fins 4 to the outside of the radiant tube, the heat dissipation efficiency of the radiant tube sleeve 3 can be significantly improved, the heat load of the radiant tube sleeve 3 can be reduced, and the service life of the radiant tube sleeve 3 can be extended, thereby extending the overall service life of the electric radiant tube heater.

[0037] The long-life radiant tube heater proposed in this embodiment has the following beneficial effects:

[0038] 1. Heat dissipation fins 4 are added to the outside of the radiant tube sleeve 3, which can improve heat dissipation efficiency, reduce the heat load of the material, and thus extend the service life.

[0039] 2. The surface of the radiant tube sleeve 3 is coated with a high-temperature resistant alloy coating, which delays high-temperature oxidation and thermal fatigue of the radiant tube sleeve 3, and at the same time improves the service life of the radiant tube sleeve 3. On the other hand, the high-temperature resistant alloy coating uses materials with different coefficients of thermal expansion from the inside to the outside, reducing the risk of cracking caused by thermal stress concentration;

[0040] 3. The iron-chromium-nickel alloy heating wire 1 is supported by the ceramic body skeleton 2, which makes the heating wire less prone to deformation and also ensures high heating efficiency.

[0041] 4. This long-life electric radiant tube heater has the advantages of simple structure, easy implementation, and stable and reliable operation.

[0042] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A long-life electric radiant tube heater, characterized in that, It includes an iron-chromium-nickel alloy heating wire, a ceramic frame, a radiant tube sleeve, and heat dissipation fins, among which, The iron-chromium-nickel alloy heating wire is threaded through the ceramic body skeleton. The iron-chromium-nickel alloy heating wire and the ceramic body form the electric heating core of the electric radiant tube. The radiant tube sleeve is fitted on the outside of the ceramic body skeleton, and the heat dissipation fins are fixed on the outer wall of the radiant tube sleeve to enhance heat dissipation.

2. The long-life electric radiant tube heater as described in claim 1, characterized in that, The iron-chromium-nickel alloy heating wire comprises multiple U-shaped heating wires.

3. The long-life electric radiant tube heater as described in claim 1, characterized in that, The heat dissipation fins are provided in multiple ways.

4. The long-life electric radiant tube heater as described in claim 1, characterized in that, The outer wall of the radiant tube sleeve is coated with a high-temperature resistant alloy coating.

5. The long-life electric radiant tube heater as described in claim 4, characterized in that, The high-temperature resistant alloy coating includes an anti-oxidation layer, a thermal stress buffer layer, and an anti-corrosion layer arranged sequentially from the inside out.

6. The long-life electric radiant tube heater as described in claim 5, characterized in that, The thickness of the antioxidant layer is 0.3mm to 3mm, the thickness of the thermal stress buffer layer is 0.5mm to 2.0mm, and the thickness of the anti-corrosion layer is 1.0mm to 3.0mm.

7. The long-life electric radiant tube heater as described in claim 1, characterized in that, The ceramic body skeleton includes multiple parallel mullite ceramic sheets and a mullite ceramic shaft passing through the axial direction of all the mullite ceramic sheets, with an iron-chromium-nickel alloy heating wire passing through the mullite ceramic sheets.

8. The long-life electric radiant tube heater as described in claim 7, characterized in that, The side of the electric heating core closest to the power supply device is its power supply end, and the side furthest from the power supply device is its heating end. All mullite ceramic sheets are arranged at unequal intervals along the length of the electric heating core.

9. The long-life electric radiant tube heater as described in claim 8, characterized in that, The mullite ceramic sheets are densely distributed near the heating end and sparsely distributed near the heating end.

10. The long-life electric radiant tube heater according to any one of claims 1 to 9, characterized in that, The heat dissipation fins are arranged in multiple rows on the outer wall of the radiant tube sleeve, and each row includes multiple heat dissipation fins arranged at intervals.

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