Boiling furnace thermocouple protection brick and application method

Abstract

The application provides a boiling furnace thermocouple protection brick and an application method, the protection brick is a refractory brick body, the brick body is provided with a through installation hole in the axial direction; a thermocouple assembly is adaptively installed in the installation hole, the thermocouple assembly comprises a thermocouple and a thermocouple sleeve wrapped outside the thermocouple; a plug is arranged at one end of the protection brick facing the hearth of the boiling furnace, a ventilation hole is formed in the plug, and the ventilation hole is used for blocking solid materials in the hearth and conducting temperature measuring gas. The application takes the refractory brick body as a protection main body, realizes the double effects of material blocking and gas guiding through the ventilation hole in the plug, can provide support for the thermocouple assembly, resist high temperature in the hearth, material scouring and corrosion gas erosion, avoid sleeve damage, and also can guarantee normal detection of the temperature in the furnace, and the overall structure is simple and convenient for on-site installation and use.

Description

Technical Field

[0001] This invention relates to the field of boiling chlorination reaction technology, and more specifically, to a thermocouple protection brick for a boiling furnace and its application method. Background Technology

[0002] The fluidized bed chlorination process is currently the mainstream technology for producing crude titanium tetrachloride. This process uses titanium ore and petroleum coke as raw materials, with chlorine as the chlorinating agent and fluidizing medium, and the reaction is completed at a high temperature of 900-1000℃. Under these conditions, the furnace is constantly filled with high-speed flowing solid particles, as well as highly corrosive and toxic gases such as titanium tetrachloride, chlorine, and hydrogen chloride, making the overall working environment extremely harsh. To monitor the reaction status in the furnace in real time and ensure production safety and reaction efficiency, multiple thermocouples are installed along the height of the sidewall of the fluidized bed chlorination furnace to continuously collect furnace temperature data. Temperature data is the core basis for controlling the fluidization state inside the furnace and judging the degree of reaction.

[0003] Currently, improvements to the temperature measurement system of fluidized bed chlorination furnaces in the industry mainly focus on two directions: optimizing the overall furnace structure and improving the protective structure of the thermocouples and their sheaths. However, both existing solutions have significant drawbacks and cannot completely solve the problems encountered in field applications. Patent application number 200320130822.9 discloses a circumferentially slit-type, screenless fluidized bed chlorination furnace. This equipment divides the furnace body into multiple sections, with conventional temperature measurement ports located at the top. These ports are simply sealed with general-purpose refractory materials. These conventional temperature measurement ports lack specific protective structures, allowing high-temperature solid materials and corrosive gases to easily penetrate them. This continuously erodes and corrodes the thermocouple sheath, and solid materials tend to accumulate and sinter in the gaps around the sheath. This not only causes high-temperature failure and reduced toughness of the sheath, leading to breakage and thermocouple failure, but also significantly increases the difficulty of thermocouple maintenance and replacement.

[0004] Patent application CN202510609366.7 discloses a temperature measuring device and a fluidized bed chlorination furnace capable of directly measuring the reaction temperature of a bed. This design employs a composite nested structure with a silicon nitride outer sheath and an Inconel inner sheath, with a high-temperature resistant ceramic adhesive filling layer between the sheaths. A vent hole is opened at the outer flange to allow nitrogen gas to pass through. The multi-layered sheath structure and nitrogen purging enhance the sheath's resistance to erosion and corrosion, extending the thermocouple's lifespan. While this design strengthens the sheath's protective performance and alleviates corrosion and wear problems to some extent, the improvement is limited to the temperature measuring element itself and does not optimize the refractory lining structure of the furnace's temperature measuring port. In practical use, even with upgraded sheath materials and structures, the conventional refractory structure at the temperature measuring port cannot prevent solid materials from accumulating in the gaps around the sheath, leading to problems such as material sintering and jamming, and sheath damage from pulling.

[0005] Therefore, there is an urgent need for a special-shaped refractory brick structure that is adapted to the working conditions of a fluidized bed chlorination furnace and is specifically designed to protect thermocouples. Systematic improvements should be made from the temperature measuring port construction end to make up for the shortcomings of existing technologies. Summary of the Invention

[0006] In view of this, the present invention aims to provide a thermocouple protection brick for a fluidized bed furnace and its application method to solve the problem of material sintering and accumulation at the temperature measuring port, which leads to the damage of the thermocouple due to pulling.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] This invention provides a thermocouple protective brick for a fluidized bed furnace. The protective brick is a refractory brick body with a through-hole in the axial direction. A thermocouple assembly is adapted to be installed in the mounting hole. The thermocouple assembly includes a thermocouple and a thermocouple sleeve wrapped around the thermocouple. A plug is provided at one end of the protective brick facing the furnace chamber. A vent hole is provided on the plug. The vent hole is used to block solid materials in the furnace chamber and conduct temperature measuring gas.

[0009] This invention effectively blocks the erosion of solid particles and corrosive gases by adding a protective brick to the outside of the thermocouple assembly, forming a protective barrier for the thermocouple sheath and preventing corrosion or breakage under harsh operating conditions. Simultaneously, a plug and vent are installed on the furnace sidewall to initially prevent large particles from entering the mounting hole and ensure smooth conduction of the temperature-measuring gas. This structure fundamentally solves the problem of direct material impact on the sheath and subsequent temperature measurement failure in traditional unprotected designs, significantly improving the reliability and service life of the thermocouple under complex operating conditions.

[0010] Furthermore, the protective brick is generally rectangular, the mounting hole is a circular through hole, and the axis of the mounting hole, the axis of the thermocouple, and the axis of the thermocouple sheath coincide.

[0011] The axes of the three components are aligned to ensure that the thermocouple measuring end is directly facing the temperature measuring area of ​​the furnace, avoiding temperature deviation caused by misalignment; at the same time, it ensures that the force is even when the sleeve is inserted and withdrawn, preventing one-sided wear, jamming or bending damage.

[0012] Furthermore, the inner diameter of the mounting hole is D1, and the outer diameter of the thermocouple sheath is D2, satisfying the condition that 1mm≤D1-D2≤5mm.

[0013] This design provides ample space for the assembly and subsequent maintenance of the thermocouple sheath, preventing difficulties in disassembly and assembly or damage to the sheath due to excessively small gaps. It also prevents fine particles and corrosive gases from entering due to excessively large gaps, effectively reducing the risk of material accumulation and component corrosion. This size range represents the optimal clearance for this operating condition, balancing ease of assembly and use with overall sealing and protection performance, and is well-suited for nitrogen purging structures.

[0014] Furthermore, the plug is provided with multiple vent holes, which are arranged in a concentric ring around the center of the plug and evenly distributed circumferentially.

[0015] The multiple vent holes on the plug of this invention are arranged in a concentric ring around the center of the plug and are evenly distributed circumferentially. On the one hand, this can expand the gas conduction range, improve the uniformity of the temperature measurement area, and avoid the problem of insufficient temperature measurement coverage of a single vent hole. On the other hand, the symmetrical arrangement structure can make the plug more evenly stressed, effectively reducing the stress concentration caused by long-term scouring of furnace materials, and improving the overall structural strength and service life of the plug.

[0016] Furthermore, the vent hole forms at least two concentric annular hole groups, with the center of the plug as the reference, the one closer to the center is the inner annular hole group, and the one farther from the center is the outer annular hole group.

[0017] This invention divides the vent holes into at least two concentric annular groups and distinguishes between the inner and outer annular groups. This allows for targeted layout based on the different flow fields and material distribution characteristics at the center and edge of the fluidized bed furnace. At the same time, the multiple annular groups further widen the gas flow channels, reduce airflow resistance, and improve the problem of heat conduction lag.

[0018] Furthermore, the vent diameter of the inner annular hole group is d1, and the vent diameter of the outer annular hole group is d2, with d1>d2.

[0019] This invention sets the diameter of the inner annular hole group to be larger than that of the outer annular hole group. The smaller diameter of the outer hole group forms a physical interception of fine particles that are easy to accumulate on the furnace wall side, effectively preventing fine powder from entering the gap and accumulating and sintering. The relatively larger diameter of the inner hole group can ensure smooth gas flow in the core area. While achieving graded blocking of materials, it also meets the needs of temperature measurement and gas conduction, effectively reducing the probability of thermocouple assembly jamming.

[0020] Furthermore, a central vent hole is formed at the center of the plug, and the diameter of the central vent hole is d3, where d3 > d1.

[0021] This invention features a central vent with a larger diameter at the center of the plug. Since the center of the furnace is the core temperature measurement area with the highest temperature and the most intense fluidization reaction, the large-diameter central vent can significantly reduce airflow resistance, accelerate the conduction speed of the true furnace temperature, and effectively reduce temperature measurement errors. This structure, in conjunction with the inner and outer annular hole groups, forms a three-level gradient structure with the hole diameter gradually decreasing from the center to the edge. This structure is perfectly adapted to the radial flow field and particle distribution pattern of the fluidized bed furnace, realizes functional zoning, and further improves the overall performance of material blocking and temperature measurement.

[0022] In this invention, a central vent hole is preferably opened at the center of the plug, and two concentric annular hole groups are arranged around the central vent hole as a reference; wherein, the one closer to the center is defined as the inner annular hole group, and the one farther from the center is defined as the outer annular hole group, thereby forming a multi-ring venting structure that is distributed step by step from the inside to the outside.

[0023] Furthermore, d3 = 0.8mm~1mm, d1 = 0.4mm~0.6mm, and d2 = 0.1mm~0.3mm.

[0024] Furthermore, the raw materials for preparing the protective brick are alumina and silicon oxide.

[0025] The present invention also provides a method for applying the protective brick described in the above technical solution, comprising the following steps:

[0026] Step S1: Install the protective bricks at the thermocouple mounting position of the fluidized bed furnace, with one end of the plug facing the furnace chamber.

[0027] Step S2: First, install the thermocouple into the thermocouple sheath to form a thermocouple assembly. Then, insert the assembly into the mounting hole from the end of the protective brick away from the plug to complete the assembly.

[0028] Step S3: Continuously introduce nitrogen gas into the annular gap between the mounting hole and the thermocouple sheath;

[0029] Step S4: During operation, solid materials are blocked from entering the installation hole by the vent hole on the plug, while the furnace gas is circulated to complete the temperature detection; during maintenance, the nitrogen supply is cut off and the thermocouple assembly can be directly extracted.

[0030] The nitrogen gas continuously introduced into the annular gap by this invention can form a stable gas seal, which, together with the mechanical baffle structure of the plug, forms a double protection, effectively preventing solid materials and corrosive media in the furnace from entering the gap, further improving the protection effect on the thermocouple assembly; at the same time, the whole operation process is convenient and quick. During maintenance, only the nitrogen gas needs to be cut off to directly extract the thermocouple assembly without disassembling the surrounding components, which significantly reduces the difficulty and intensity of maintenance and ensures the continuous and stable operation of the fluidized bed furnace.

[0031] Compared with existing technologies, the fluidized bed thermocouple protection brick and its application method described in this invention have the following advantages:

[0032] (1) The present invention sets the vent holes in a concentric ring circumferentially distributed form. The symmetrical arrangement makes the plugs bear the force evenly, reduces the stress damage caused by scouring, and improves the structural strength. Combined with the gradient aperture design of the central vent hole and the inner and outer multi-layer ring hole groups, the layout is divided according to the flow field characteristics of high temperature in the center of the furnace and more fine powder at the edge. The large central hole reduces the airflow resistance to quickly conduct temperature, and the gradually decreasing aperture on the inner and outer sides realizes the graded interception of particles of different sizes. While ensuring the accuracy of temperature measurement, it effectively prevents the accumulation and sintering of materials.

[0033] (2) By controlling the diameter difference between the mounting hole and the thermocouple sheath to 1mm~5mm, the present invention utilizes a reasonable gap to facilitate component assembly and subsequent pull-out maintenance, while avoiding the problem of material and harmful gas leakage caused by excessive gap, and is perfectly compatible with nitrogen purging system.

[0034] (3) The present invention uses alumina and silica composite refractory material to make bricks. Relying on the high temperature resistance, corrosion resistance and erosion resistance of this material, it can provide stable support and basic protection for thermocouple components under the harsh working conditions of high temperature, corrosive media and fluidized particles in boiling furnace. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0036] Figure 1 Figure (a) is an axial cross-sectional view and Figure (b) is a side view.

[0037] Figure 2 This is a schematic diagram of the assembly structure of the protective brick and thermocouple assembly described in this invention;

[0038] Figure 3 This is a schematic diagram of the end face structure of the plug in Embodiment 1 of the present invention;

[0039] Figure 4 This is a schematic diagram of the end face structure of the plug in Comparative Example 1 of the present invention;

[0040] Figure 5 This is a schematic diagram of the end face structure of the plug in Comparative Example 2 of the present invention;

[0041] Figure 6 This is a schematic diagram of the end face structure of the plug in Comparative Example 3 of the present invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Fluidized bed furnace; 2. Protective brick; 3. Thermocouple assembly; 301. Thermocouple; 302. Thermocouple sheath; 303. Flange; 4. Plug; 5. Central vent hole; 6. Inner annular hole group a; 7. Inner annular hole group b; 8. Outer annular hole group; 9. Mounting hole. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0046] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] like Figures 1-2 As shown, this embodiment discloses a thermocouple protective brick for a fluidized bed furnace. The protective brick 2 is a refractory brick body with a through-hole 9 in the axial direction. A thermocouple assembly 3 is adapted to be installed in the mounting hole 9. The thermocouple assembly 3 includes a thermocouple 301 and a thermocouple sleeve 302 wrapped around the thermocouple 301. A plug 4 is provided at one end of the protective brick 2 facing the furnace chamber of the fluidized bed furnace 1. A vent hole is provided on the plug 4. The vent hole is used to block solid materials in the furnace chamber and conduct temperature measuring gas.

[0048] In this embodiment, a flange 303 is provided at the end of the thermocouple assembly 3 facing away from the furnace, and a nitrogen inlet hole is provided on the flange 303. One stream of nitrogen is sent into the annular gap between the thermocouple sheath 302 and the mounting hole 9 through the inlet hole; another stream of nitrogen is sent into the gap between the thermocouple 301 and the thermocouple sheath 302. The two streams of nitrogen form gas seals respectively, which work together to prevent materials in the furnace from entering the gaps.

[0049] This embodiment also provides a method for applying the protective brick described in the above technical solution, including the following steps:

[0050] Step S1: Install the protective brick 2 at the thermocouple mounting position of the fluidized bed furnace 1, with one end of the plug 4 facing the furnace chamber.

[0051] Step S2: First, install the thermocouple 301 into the thermocouple sleeve 302 to form the thermocouple assembly 3. Then, insert the assembly from the end of the protective brick 2 away from the plug 4 into the mounting hole 9 to complete the assembly.

[0052] Step S3: Continuously introduce nitrogen gas into the annular gap between the mounting hole 9 and the thermocouple sheath 302;

[0053] Step S4: During operation, solid materials are blocked from entering the installation hole 9 by relying on the vent hole on the plug 4, while the furnace gas is circulated to complete the temperature detection; during maintenance, the nitrogen supply is cut off and the thermocouple assembly 3 can be directly extracted.

[0054] It should be noted that in this embodiment, the protective brick 2 is made of alumina and silica composite refractory material. This embodiment does not limit the specific preparation process and molding method of the protective brick 2. Any conventional refractory brick preparation method that can process the above raw materials into an integral cuboid brick and simultaneously meet the requirements of high temperature of 900~1000℃, resistance to chlorine and hydrogen chloride corrosion, and resistance to material erosion is applicable to this solution.

[0055] Example 1

[0056] A thermocouple protection brick for a boiling furnace:

[0057] like Figure 3 As shown, the protective brick 2 is a refractory brick body with a through-hole 9 in the axial direction; a thermocouple assembly 3 is adapted to be installed in the mounting hole 9, the thermocouple assembly 3 includes a thermocouple 301 and a thermocouple sleeve 302 wrapped around the thermocouple 301; a plug 4 is provided at one end of the protective brick 2 facing the furnace of the fluidized bed furnace 1, and a vent hole is provided on the plug 4, the vent hole is used to block solid materials in the furnace and conduct temperature measuring gas;

[0058] The protective brick 2 is generally rectangular, and the mounting hole 9 is a circular through hole. The axis of the mounting hole 9, the axis of the thermocouple 301, and the axis of the thermocouple sheath 302 coincide. The inner diameter of the mounting hole 9 is D1, the outer diameter of the thermocouple sheath 302 is D2, and D1-D2=3mm.

[0059] The plug 4 is provided with multiple vent holes, which form two concentric annular hole groups. With the center of the plug 4 as the reference, the one closer to the center is the inner annular hole group a6, and the one farther from the center is the outer annular hole group 8. A central vent hole 5 is also opened at the center of the plug 4.

[0060] The central vent 5 has a diameter d3=0.8mm, the inner annular hole group a6 has a diameter d1=0.5mm, and the outer annular hole group 8 has a diameter d2=0.1mm.

[0061] The steps for using the protective brick 2 described in this embodiment are as follows:

[0062] S1. Install the protective brick 2 at the preset thermocouple installation position of the fluidized bed furnace 1, so that the end of the protective brick 2 with the plug 4 faces the inside of the furnace.

[0063] S2. Insert thermocouple 301 into thermocouple sleeve 302 to assemble thermocouple assembly 3. Then insert thermocouple assembly 3 into mounting hole 9 from the end of protective brick 2 away from plug 4 to complete the overall assembly.

[0064] S3. During normal operation of the equipment, nitrogen gas is continuously introduced into the annular gap between the mounting hole 9 and the thermocouple sheath 302 at a flow rate of 3-6 Nm³. 3 / h.

[0065] S4. During operation, the vent holes on the plug 4 are distributed in a gradient to block large solid particles in the furnace, while the high-temperature gas in the furnace is circulated to achieve real-time monitoring of the furnace temperature. When the equipment is under maintenance, the nitrogen supply is cut off and the thermocouple assembly 3 can be directly extracted to complete the maintenance and replacement.

[0066] Operational test results

[0067] Testing was conducted after 6 months of continuous operation.

[0068] Material accumulation and jamming: There is no obvious accumulation or sintering of solid material inside the plug 4 and mounting hole 9; the thermocouple assembly 3 can be pulled out smoothly without jamming or deformation.

[0069] Sheath condition: The surface corrosion and wear of the thermocouple sheath 302 are slight, and there are no problems with breakage or detachment;

[0070] Temperature measurement accuracy: The temperature detection error inside the furnace is stable within ±2℃, and the temperature measurement data is accurate and continuous;

[0071] Maintenance difficulty: The removal and replacement of thermocouple assembly 3 can be completed by a single person, resulting in high maintenance efficiency.

[0072] Comparative Example 1

[0073] A thermocouple protection brick for a boiling furnace:

[0074] like Figure 4 As shown, the protective brick 2 described in this comparative example and Example 1 is completely identical in appearance, size, and usage method, with the only difference being:

[0075] The plug 4 is only provided with a central vent 5 and an outer annular hole group 8, and the inner annular hole group a6 is omitted. The diameter of the central vent 5 is d3=1.2mm, and the diameter of the outer annular hole group 8 is d2=0.1mm.

[0076] The test was conducted after 6 months of continuous operation under the same conditions.

[0077] Material accumulation and jamming: A large amount of fine particles of material are deposited and locally sintered on the inner wall of the through hole and in the gap of the mounting hole 9. The thermocouple assembly 3 is severely jammed. Forcibly pulling it out can easily cause the thermocouple sheath 302 to bend or break.

[0078] Sheath condition: Thermocouple sheath 302 has been subjected to long-term material erosion and corrosion, resulting in significant thinning of the tube wall;

[0079] Temperature measurement accuracy: Airflow is easily obstructed, temperature detection error reaches ±5℃, and temperature measurement data fluctuates greatly;

[0080] Maintenance difficulty: The components need to be removed by tapping and prying with tools, which is labor-intensive and can easily damage equipment components.

[0081] Comparative Example 2

[0082] A thermocouple protection brick for a boiling furnace:

[0083] like Figure 5 As shown, the protective brick 2 described in this comparative example and Example 1 is completely identical in appearance, size, and usage method, with the only difference being:

[0084] The plug 4 is provided with three concentric annular hole groups, which are arranged from the inside to the outside as follows: central vent 5, inner annular hole group a6, inner annular hole group b7, and outer annular hole group 8. The diameter of the central vent 5 is d3=0.8mm, the diameter of the inner annular hole group a6 is d1=0.4mm, the diameter of the inner annular hole group b7 is d4=0.15mm, and the diameter of the outer annular hole group 8 is d2=0.1mm.

[0085] Tested after 6 months of continuous operation under the same conditions:

[0086] Material accumulation and jamming: The annular hole group can only block large particles of material, and a small amount of fine powder enters the gap, but no serious sintering jamming occurs;

[0087] Sheath condition: Thermocouple sheath 302 has moderate corrosion and wear, and the degree of damage is greater than that in Example 1 (possibly due to excessive orifice group causing airflow turbulence and local flow velocity changes at the temperature measuring point exacerbating erosion).

[0088] Temperature measurement accuracy: The temperature detection error inside the furnace is stable within ±2℃, and the temperature measurement data is accurate and continuous;

[0089] Maintenance difficulty: Thermocouple assembly 3 can be pulled out relatively smoothly.

[0090] Comparative Example 3

[0091] A thermocouple protection brick for a boiling furnace:

[0092] like Figure 6 As shown, the protective brick 2 described in this comparative example and Example 1 is completely identical in appearance, size, and usage method, with the only difference being:

[0093] The plug 4 has only a central vent 5, and all annular holes are removed.

[0094] Testing was conducted after 6 months of continuous operation.

[0095] Material accumulation and jamming: There is no obvious accumulation or sintering of solid material inside the plug 4 and mounting hole 9; the thermocouple assembly 3 can be pulled out smoothly without jamming or deformation.

[0096] Sheath condition: The surface corrosion and wear of the thermocouple sheath 302 are slight, and there are no problems with breakage or detachment;

[0097] Temperature measurement accuracy: Airflow is easily obstructed, temperature detection error reaches ±8℃, and temperature measurement data fluctuates greatly;

[0098] Maintenance difficulty: The removal and replacement of thermocouple assembly 3 can be completed by a single person, resulting in high maintenance efficiency.

[0099] Comparative Example 4

[0100] Without setting up the protective brick 2, the thermocouple assembly 3 was directly installed at the preset temperature measurement position of the boiling furnace 1. The other operating conditions, nitrogen gas introduction conditions, and running time were consistent with those in Example 1.

[0101] Tested after 6 months of continuous operation under the same conditions:

[0102] Material accumulation and jamming: Solid particles and dust in the furnace come into direct contact with thermocouple assembly 3. Material accumulates and sinters on a large area outside thermocouple sheath 302, and thermocouple assembly 3 is completely jammed. Forcibly pulling it out can easily cause the sheath to break.

[0103] Sheath condition: Thermocouple sheath 302 is directly subjected to high-temperature material scouring and strong corrosive gas erosion throughout the process, resulting in severe wear and corrosion of the tube wall and potential for local damage;

[0104] Temperature measurement accuracy: The temperature measurement point has no protective structure, the airflow is turbulent and the heat conduction is unstable, the temperature detection error is greater than ±10℃, and the data is seriously distorted;

[0105] Maintenance difficulty: Thermocouple assembly 3 cannot be directly extracted; the surrounding furnace structure must be disassembled before maintenance can be carried out, resulting in a large workload and a long maintenance cycle.

[0106] This invention employs a plug 4 with a central vent 5 and a multi-ring gradient annular hole group, combined with a reasonable gap between the protective brick 2 and the thermocouple sheath 302 and a nitrogen purging method. Under the high temperature, strong corrosion, and material scouring conditions of the boiling furnace in titanium tetrachloride production, it can rapidly conduct furnace temperature, control temperature measurement error within a small range, and simultaneously intercept solid particles of different sizes in stages, effectively avoiding component jamming caused by material accumulation and sintering. This structure also reduces stress concentration in the plug, improves the overall structural strength, slows down the wear and corrosion of the thermocouple sheath, and facilitates the processing, assembly, and maintenance of the device. It can operate stably for a long time, significantly reducing operation and maintenance costs and ensuring continuous production.

[0107] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A thermocouple protection brick for a fluidized bed furnace, characterized in that, The protective brick (2) is a refractory brick body with a through-hole (9) in the axial direction; a thermocouple assembly (3) is adapted to be installed in the mounting hole (9), the thermocouple assembly (3) includes a thermocouple (301) and a thermocouple sleeve (302) wrapped around the thermocouple (301); a plug (4) is provided at one end of the protective brick (2) facing the furnace of the fluidized bed furnace (1), and a vent hole is provided on the plug (4), the vent hole is used to block solid materials in the furnace and conduct temperature measuring gas.

2. The protective brick according to claim 1, characterized in that, The protective brick (2) is rectangular in shape, and the mounting hole (9) is a circular through hole. The axis of the mounting hole (9), the axis of the thermocouple (301), and the axis of the thermocouple sleeve (302) coincide.

3. The protective brick according to claim 2, characterized in that, The inner diameter of the mounting hole (9) is D1, and the outer diameter of the thermocouple sleeve (302) is D2, and 1mm≤D1-D2≤5mm.

4. The protective brick according to claim 1, characterized in that, The plug (4) is provided with multiple vent holes, which are arranged in a concentric ring with the center of the plug (4) as the center and are evenly distributed along the circumference.

5. The protective brick according to claim 4, characterized in that, The vent hole forms at least two concentric annular hole groups. With the center of the plug (4) as the reference, the one closer to the center is the inner annular hole group, and the one farther from the center is the outer annular hole group (8).

6. The protective brick according to claim 5, characterized in that, The vent diameter of the inner annular hole group is d1, and the vent diameter of the outer annular hole group (8) is d2, and d1>d2.

7. The protective brick according to claim 6, characterized in that, A central vent hole (5) is opened at the center of the plug (4), and the diameter of the central vent hole (5) is d3, and d3 > d1.

8. The protective brick according to claim 7, characterized in that, d3=0.8mm~1mm, d1=0.4mm~0.6mm, d2=0.1mm~0.3mm.

9. The protective brick according to claim 1, characterized in that, The raw materials for preparing the protective brick (2) are alumina and silicon oxide.

10. The method of applying the protective brick according to any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1: Place the protective brick (2) in the thermocouple mounting position of the boiling furnace (1), with one end of the plug (4) facing the furnace chamber; Step S2: First, insert the thermocouple (301) into the thermocouple sleeve (302) to form a thermocouple assembly (3). Then, insert the assembly into the mounting hole (9) from the end of the protective brick (2) away from the plug (4) to complete the assembly. Step S3: Continuously introduce nitrogen gas into the annular gap between the mounting hole (9) and the thermocouple sheath (302); Step S4: During operation, solid materials are blocked from entering the installation hole (9) by relying on the vent hole on the plug (4), while the furnace gas is circulated to complete the temperature detection; during maintenance, the nitrogen supply is cut off and the thermocouple assembly (3) is directly extracted.

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