Mounting structure for bed temperature thermocouple of circulating fluidized bed boiler

Abstract

The invention discloses a mounting structure for a bed temperature thermocouple of a circulating fluidized bed boiler, and belongs to the technical field of boiler temperature measurement. The mounting structure is used for mounting the bed temperature thermocouple upwards from the bottom of a boiler air chamber and extending into a hearth. The installation sleeve is fixed with an air chamber sealing plate, the inner protection sleeve is fixed with a hearth air distribution plate, and the lower portion of the inner protection sleeve is contained in the installation sleeve. The key point is that a first gap allowing relative sliding is formed between the mounting sleeve and the inner protective sleeve through socket fit; and a second gap allowing relative sliding is also formed between the inner protective sleeve and the sleeve of the bed temperature thermocouple. And the bed temperature thermocouple is basically arranged along the vertical direction. Thermal expansion displacement is effectively compensated through double sliding gaps, the thermocouple and the sleeve are prevented from being damaged, the installation stability is improved, the service life of the thermocouple is prolonged, and the temperature measurement reliability is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of boiler temperature measurement technology, and in particular to an installation structure for a bed temperature thermocouple used in a circulating fluidized bed boiler. Background Technology

[0002] Circulating fluidized bed (CFB) boilers are widely used in power, chemical, and heating industries due to their advantages such as wide fuel adaptability, high combustion efficiency, and low pollutant emissions. Bed temperature is a critical parameter in the operation of CFB boilers, significantly impacting combustion control, heat transfer efficiency, pollutant generation, and safe operation. Therefore, accurate and reliable bed temperature measurement is essential for ensuring the economical, safe, and stable operation of the boiler. As the primary temperature-sensing element, the proper installation structure of the bed temperature thermocouple directly affects its service life and measurement accuracy.

[0003] Currently, a common installation method for bed temperature thermocouples in circulating fluidized bed boilers is to install them from the bottom of the boiler air chamber upwards, passing sequentially through the bottom structure of the air chamber (such as the air chamber sealing plate) and the air distribution plate at the bottom of the furnace, finally extending the measuring end of the thermocouple into the fluidized bed material layer inside the furnace. In this installation method, the lower part of the thermocouple usually needs to be fixed to the bottom structure of the air chamber to ensure its installation stability and sealing; simultaneously, the portion of the thermocouple passing through the air distribution plate also needs to have a relatively fixed positional relationship with the air distribution plate to ensure its accurate insertion into the predetermined temperature measurement area.

[0004] However, the existing bed temperature thermocouple installation methods described above have the following drawbacks in practical applications: During boiler start-up and shutdown, components such as the furnace and air chamber undergo drastic temperature changes, resulting in significant thermal expansion and contraction. In particular, a considerable axial relative displacement occurs between the furnace air distribution plate (which directly contacts the high-temperature bed material and flue gas) and the relatively cooler bottom sealing plate of the air chamber due to the large temperature difference. In traditional rigid or semi-rigid fixed installation structures, this relative displacement is directly transmitted to the thermocouple and its protective sheath, generating significant mechanical stress. If both ends of the thermocouple or its protective sheath are fixed to the components experiencing relative displacement, and there is a lack of an effective displacement compensation mechanism in between, the thermocouple or its protective sheath is highly susceptible to bending, deformation, or even breakage, greatly shortening its service life and increasing maintenance costs and shutdown risks. Furthermore, if the thermocouple's sheath itself lacks sufficient space to move when heated, it will also be subject to compressive or tensile stress, affecting its stability and lifespan. Therefore, how to design an installation structure that can effectively adapt to the relative displacement of thermal expansion between different components of the boiler and protect thermocouples from stress damage caused by this is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The present invention aims to solve the main problems existing in the installation structure of thermocouples for bed temperature in circulating fluidized bed boilers. Due to the significant thermal expansion and relative displacement between various components during boiler start-up, shutdown and operation, as well as the thermal expansion of the thermocouples themselves, traditional rigid or semi-rigid fixed thermocouples and their protective sleeves are easily subjected to huge mechanical stress, resulting in bending, deformation or even breakage and damage, which seriously affects the service life and measurement reliability of the thermocouples.

[0006] To address the problems existing in the background art, the present invention provides a bed temperature thermocouple installation structure for a circulating fluidized bed boiler. The bed temperature thermocouple is installed inside the boiler, with one part located at the bottom of the boiler and another part located in the air chamber. Its measuring end is located inside the furnace and extends upward from the bottom of the boiler through the air chamber to the furnace.

[0007] The bed temperature thermocouple is set basically in the vertical direction, and the angle between its axis and the vertical direction does not exceed 5°.

[0008] The mounting sleeve is fixedly connected to the air chamber sealing plate at its lower part.

[0009] An inner protective sleeve is provided, the upper part of which is fixedly connected to the furnace air distribution plate, and the lower part of which is accommodated in the mounting sleeve. The bed temperature thermocouple is accommodated in the inner protective sleeve.

[0010] The mounting sleeve and the inner protective sleeve are fitted together by a socket joint, and a first gap is preset to allow the inner protective sleeve to slide relative to the mounting sleeve.

[0011] A second gap is pre-set between the inner protective sleeve and the bed temperature thermocouple sleeve, allowing the bed temperature thermocouple sleeve to slide relative to the inner protective sleeve.

[0012] Compared with existing technologies, this invention, through the above-mentioned technical solution, can effectively compensate for the relative displacement caused by thermal expansion. By setting a first gap between the mounting sleeve and the inner protective sleeve and employing a socket joint, this invention allows the inner protective sleeve to slide freely relative to the mounting sleeve when significant axial relative displacement occurs between the furnace air distribution plate and the bottom sealing plate of the air chamber due to thermal expansion and contraction. This effectively absorbs and eliminates the enormous mechanical stress generated by this relative displacement. Simultaneously, by setting a second gap between the inner protective sleeve and the bed temperature thermocouple sleeve, the thermal expansion of the bed temperature thermocouple itself or fine-tuning during the sliding of the inner protective sleeve is permitted. This dual sliding compensation mechanism fundamentally avoids sleeve bending, deformation, or thermocouple damage caused by thermal stress, significantly improving the service life of the bed temperature thermocouple. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is an embodiment of a circulating fluidized bed boiler bed temperature thermocouple installation structure provided in this application;

[0015] Figure 2 yes Figure 1 A magnified view of a portion of region A shown;

[0016] Figure 3 This is yet another embodiment of a bed-temperature thermocouple mounting structure provided in this application;

[0017] Figure 4 yes Figure 3 A magnified view of a portion of region B shown;

[0018] Figure 5 yes Figure 3 A magnified view of a portion of region C shown;

[0019] Figure 6 This is an embodiment of another thermocouple mounting structure provided in this application;

[0020] Figure 7 yes Figure 6 A magnified view of a portion of region D shown;

[0021] Figure 8 yes Figure 6 A magnified view of a portion of region E shown;

[0022] Figure 9 yes Figure 6 A magnified view of a portion of region F shown.

[0023] Icon labels:

[0024] 1. Installation structure of bed temperature thermocouple in circulating fluidized bed boiler; 111. Inner protective sleeve; 112. Outer protective sleeve; 113. Installation sleeve; 114. Bed temperature thermocouple sleeve; 1141. Ordinary bed temperature thermocouple sleeve; 1142. Wear-resistant bed temperature thermocouple sleeve; 121. First gap; 122. Second gap; 131. Conical refractory mortar layer; 132. Bottom refractory mortar; 141. Bed temperature thermocouple extension tube; 142. Bed temperature thermocouple sleeve connector; 15. Bed temperature thermocouple measuring insert; 16. V-pin; 17. Flange;

[0025] 2. Furnace chamber; 21. Furnace chamber air distribution plate; 22. Air cap; 221. Air cap ventilation hole;

[0026] 3. Air chamber; 31. Bottom sealing plate of the air chamber;

[0027] 4. Boiler bottom; 41. Insulation layer. Detailed Implementation

[0028] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the application. Similarly, the following embodiments are only some, not all, embodiments of the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present application.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] In one embodiment, such as Figure 1 and Figure 2 As shown, a bed temperature thermocouple mounting structure 1 for a circulating fluidized bed boiler is provided. This mounting structure 1 is used to install bed temperature thermocouples inside the boiler for bed temperature measurement, thereby providing key temperature parameters for stable boiler operation and optimized control.

[0031] Reference Figure 1 The installation path of the bed temperature thermocouple starts from the bottom 4 of the boiler, passes upward through the air chamber 3, and then sequentially passes through the bottom sealing plate 31 of the air chamber and the air distribution plate 21 of the furnace, finally extending its measuring end into the furnace 2. Its core temperature sensing element is the bed temperature thermocouple measuring insert 15, which typically contains thermocouple wire (e.g., type K, type N, or other models suitable for high-temperature measurement). One end forms a temperature sensing contact (hot contact) to sense the temperature inside the furnace, while the other end (cold contact) leads out to the outside for connection to a temperature display instrument or control system. The bed temperature thermocouple measuring insert 15 is fitted with a protective bed temperature thermocouple sheath 114. The bed temperature thermocouple is basically set vertically, with its axis forming an angle of no more than 5° with the vertical direction.

[0032] The diagram illustrates the primary air direction within the air chamber 3. During normal boiler operation, this primary air is blown upwards from the air chamber 3, passes through the furnace air distribution plate 21, and is finally ejected at high speed through the air cap ventilation holes 221 on the air cap 22 installed in the furnace 2, and is evenly delivered into the furnace to participate in fuel fluidization and combustion. It is foreseeable that the high-speed airflow ejected from the air cap ventilation holes 221 often carries solid particles (such as coal particles, ash, and bed material) from the bed material, which will continuously scour and wear the bed temperature thermocouple sheath 114 located nearby or downstream (especially its windward side and the area near the air cap). This "sandblasting" effect is one of the important causes of thermocouple damage, especially in high-temperature environments, where the wear resistance of the material will be further tested.

[0033] In this embodiment, the lower part of the bed temperature thermocouple is fixed and connected via flange 17. This flange 17 not only provides a way to install and fix the bed temperature thermocouple, ensuring its positional stability during boiler operation, but also provides a certain degree of sealing by placing a sealing gasket (not shown in the figure) between the flange contact surfaces, preventing high-pressure air in the wind chamber 3 or high-temperature flue gas in the furnace 2 from leaking through the installation holes. Besides flange connection, other feasible connection methods can also be used depending on actual needs and installation convenience, such as threaded connection (internal threads are machined on the mounting sleeve, and external threads are machined on the corresponding part of the thermocouple), ferrule connection (fixation and sealing are achieved through the tightening action of the ferrule), or welding connection (if permanent fixing is required and the sealing requirements are extremely high). The lower end of the bed temperature thermocouple extends further downwards. Its specific connection and lead-out method are not fully shown in the accompanying drawings of this embodiment, but it is usually connected to a junction box or directly leads out a cable. The junction box may contain terminals for connecting compensating wires, or an integrated temperature transmitter to convert millivolt signals into standard current or voltage signals for transmission to the control room.

[0034] To withstand the harsh environment of high temperature and abrasion within the furnace and to protect the internal bed temperature thermocouple measuring insert 15, the bed temperature thermocouple sheath 114 plays a crucial role. It not only provides mechanical support for the measuring insert 15 and isolates it from the external environment, preventing physical damage, chemical corrosion, and erosion from high-speed materials, but also directly affects the stability of its measuring performance and its service life. (Refer to...) Figure 2 ( Figure 1 (Partial enlarged view of area A in the image) In this embodiment, the bed temperature thermocouple sheath 114 adopts a segmented material design to balance the performance requirements and cost of different parts. Specifically, the bed temperature thermocouple sheath 114 includes a lower ordinary bed temperature thermocouple sheath 1141 (i.e., the first material segment) and an upper wear-resistant bed temperature thermocouple sheath 1142 (i.e., the second material segment) that constitutes the measuring end area.

[0035] The bed temperature thermocouple wear-resistant sleeve 1142 is in direct contact with the high-temperature, high-speed fluidized bed material in the furnace 2, therefore it is made of a material with excellent high-temperature wear resistance. For example, it can be the high-temperature super wear-resistant material described in claim 8, whose composition by weight percentage may include: 28% to 35% chromium (Cr), 2% to 5% manganese (Mn), 2% to 6% molybdenum (Mo), 1% to 3% silicon (Si), 20% to 26% nickel (Ni), 4% to 10% tungsten (W), 4% to 10% cobalt (Co), no more than 0.04% sulfur (S), no more than 0.04% phosphorus (P), 0.5% to 0.7% aluminum (Al), and 8% to 12% rare earth elements (RE). This alloy material can maintain high hardness and wear resistance at high temperatures and has good oxidation and corrosion resistance. Of course, depending on the specific degree of wear and temperature conditions, other types of high-temperature wear-resistant alloys can also be selected, such as nickel-based high-temperature alloys, cobalt-based high-temperature alloys, or metal substrate sleeves with a surface coated with a hard wear-resistant layer (such as tungsten carbide, alumina ceramics, etc.).

[0036] The bed temperature thermocouple sheath 1141 can be made of conventional high-temperature resistant stainless steel, such as stainless steel 2520 (i.e., 0Cr25Ni20 or the corresponding grade 310S of SUS304), which has good high-temperature oxidation resistance and certain corrosion resistance, and is relatively inexpensive. Besides stainless steel 2520, other grades of heat-resistant stainless steel, such as 316L (if the corrosion is strong) or Incoloy 800H, can be selected according to the actual operating temperature and corrosive medium. Figure 2 The diagram illustrates that the bed temperature thermocouple measuring insert 15 is housed inside the ordinary bed temperature thermocouple sheath 1141 and the wear-resistant bed temperature thermocouple sheath 1142.

[0037] Figure 1 The diagram also shows the external insulation layer 41 at the bottom 4 of the boiler, used to reduce heat loss, improve thermal efficiency, and protect the boiler's external structure and personnel from high temperatures. This insulation layer 41 can be made of various high-temperature resistant, low-thermal-conductivity materials, such as aluminosilicate fiber felt, calcium silicate board, rock wool, and perlite products. In practical applications, the insulation layer 41 is typically a multi-layered structure, possibly consisting of, from the inside out, high-temperature resistant lightweight insulating bricks or castables, a main insulation material layer (such as aluminosilicate fiber felt), and an outermost protective metal shell (such as aluminum sheet or galvanized iron sheet) to prevent moisture or mechanical damage to the insulation material. The thickness of the insulation layer is determined comprehensively based on factors such as the boiler's design temperature, ambient temperature, and energy-saving requirements.

[0038] This embodiment demonstrates a basic bed-temperature thermocouple installation method, which uses a flange (or other feasible method) for fixation and optimizes the material design of the thermocouple sheath, particularly employing segmented wear-resistant material to improve its wear resistance in specific areas and extend its overall service life. However, as mentioned earlier, the high-speed, dust-laden airflow ejected from the vent cap can still cause significant wear to the thermocouple.

[0039] In another embodiment, such as Figure 3 , Figure 4 and Figure 5 As shown, the circulating fluidized bed boiler bed temperature thermocouple installation structure 1 of the present invention has been optimized based on Embodiment 1 to further improve its stability and service life under high temperature, high wear and thermal expansion and contraction environment.

[0040] In addition to the basic components described in Embodiment 1, such as the bed temperature thermocouple (whose core is the bed temperature thermocouple measuring insert 15, and which has a segmented bed temperature thermocouple sheath 114), flange 17, furnace 2, furnace air distribution plate 21, air cap 22, air cap ventilation hole 221, air chamber 3, air chamber bottom sealing plate 31, boiler bottom 4, and insulation layer 41, the core improvement of this embodiment lies in the introduction of a multi-layer sheath protection and sliding compensation structure, and the provision of a foundation for possible further protective measures.

[0041] Reference Figure 3 and Figure 5 ( Figure 3 (Partial enlarged view of area C) In this embodiment, the installation structure 1 includes an installation sleeve 113 and an inner protective sleeve 111. The lower part of the installation sleeve 113 is fixedly connected to the bottom sealing plate 31 of the air chamber, for example, by welding or bolting. The installation sleeve 113 is fixedly connected to the bed temperature thermocouple via a flange 17, ensuring the stable fixation and sealing of the bed temperature thermocouple within the installation sleeve 113.

[0042] The upper part of the inner protective sleeve 111 is fixedly connected to the furnace air distribution plate 21, for example, by welding. The lower part of the inner protective sleeve 111 is accommodated inside the mounting sleeve 113. Crucially, as... Figure 5As shown, the mounting sleeve 113 and the inner protective sleeve 111 are fitted together by a socket joint, and a first gap 121 is pre-set to allow the inner protective sleeve 111 to slide freely in the vertical direction relative to the mounting sleeve 113. The radial dimension of the first gap 121 can be designed to be at least 0.5 mm, for example, 0.5 mm to 1.0 mm, to ensure sufficient sliding space under various operating conditions. The presence of the first gap 121 allows the inner protective sleeve 111 to slide smoothly within the mounting sleeve 113 when there is a significant axial relative displacement between the furnace air distribution plate 21 (fixed to the inner protective sleeve 111) and the bottom sealing plate 31 of the air chamber (fixed to the mounting sleeve 113) due to the huge temperature difference during boiler start-up and shutdown. This effectively absorbs and compensates for this relative displacement, avoiding sleeve bending, deformation, or damage caused by thermal stress.

[0043] The bed temperature thermocouple (specifically its bed temperature thermocouple sheath 114, shown in the figure as its ordinary sheath portion 1141) is housed within the inner protective sheath 111. Furthermore, as... Figure 5 As shown, a second gap 122 is pre-set between the inner protective sleeve 111 and the bed temperature thermocouple sleeve 114, allowing the bed temperature thermocouple sleeve 114 (and the entire bed temperature thermocouple connected thereto) to slide freely in the vertical direction relative to the inner protective sleeve 111. The radial dimension of this second gap 122 can also be designed to be at least 0.5 mm, for example, 0.5 mm to 1.0 mm, to ensure that the expansion and relative sliding of the thermocouple itself are not hindered. The presence of this second gap 122 can effectively compensate for the axial expansion or contraction of the bed temperature thermocouple itself due to heating, or allow the bed temperature thermocouple to make corresponding fine adjustments when the inner protective sleeve 111 slides, further protecting the internal bed temperature thermocouple measuring insert 15 from unnecessary stress.

[0044] Reference Figure 3 and Figure 4 ( Figure 3 (Partial enlarged view of area B) To provide additional protection for the inner protective sleeve 111 extending into the furnace 2, this embodiment also includes an outer protective sleeve 112. The outer protective sleeve 112 is coaxially fitted over the portion of the inner protective sleeve 111 extending upwards into the furnace 2 from the furnace air distribution plate 21. The lower end of the outer protective sleeve 112 originates from the upper surface of the furnace air distribution plate 21 and is fixedly connected to the furnace air distribution plate 21, for example, by welding. This means that the outer protective sleeve 112 exists only on the furnace air distribution plate 21, providing a robust external barrier for the exposed portion of the inner protective sleeve 111 within the furnace to resist direct erosion and wear from the bed material.

[0045] To further improve the wear resistance of the installation structure, especially in the area near the vent 221 of the air cap 22, the top of the outer protective sleeve 112 is higher than the air outlet of the air cap 22 inside the furnace, with a vertical height difference of at least 100mm. For example, this height difference can be designed within the range of 100mm to 150mm, or optimized according to specific boiler parameters and airflow characteristics. This height design helps the top of the outer protective sleeve 112 effectively avoid or significantly reduce the direct scouring area of ​​the high-speed dust-laden airflow ejected from the air cap 22, thereby extending its service life.

[0046] like Figure 4 As shown, multiple V-shaped pins 16 are also fixedly installed on the outer circumferential surface of the outer protective sleeve 112. These V-shaped pins 16 can be made of heat-resistant alloy material and are firmly fixed to the outer protective sleeve 112 by welding or other methods. They can be distributed in an array along the axial and circumferential directions of the outer protective sleeve 112. The installation of V-shaped pins 16 can, on the one hand, play a certain role in turbulence and change the flow characteristics of the nearby airflow. On the other hand, more importantly, it provides an excellent anchoring foundation for the subsequent laying of refractory materials (such as the conical refractory mortar layer in Example 3), which can significantly enhance the bonding strength and adhesion between the refractory material and the outer protective sleeve 112.

[0047] In this embodiment, the bed temperature thermocouple sheath 114 also adopts a segmented material design to cope with the harsh working conditions inside the furnace. Specifically, the bed temperature thermocouple sheath 114 includes a first material segment (i.e., the ordinary bed temperature thermocouple sheath 1141) and a second material segment (i.e., the wear-resistant bed temperature thermocouple sheath 1142). The second material segment 1142 is made of high-temperature extra-high wear-resistant material and is located at the head of the bed temperature thermocouple. Its length measured downwards from the top of the bed temperature thermocouple is not less than 500mm to ensure sufficient protective margin after long-term wear. The first material segment 1141 is made of stainless steel 2520 and is fixedly connected to the second material segment 1142 by, for example, threaded connection and welding. The connection between the first material segment 1141 and the second material segment 1142 has a polished surface to reduce the risk of stress concentration and premature damage.

[0048] The measuring end of the bed temperature thermocouple, i.e., the top of the wear-resistant sheath 1142 (which houses the sensing end of the bed temperature thermocouple measuring insert 15), extends from the tops of the inner protective sheath 111 and the outer protective sheath 112, directly contacting the fluidized bed material within the furnace 2. To ensure measurement accuracy and sensitivity, no other coaxially arranged protective sheaths (such as the tops of the inner protective sheath 111 or the outer protective sheath 112, which do not cover or contact the side of the measuring portion) are present around the radial periphery of the measuring portion formed by the top of the bed temperature thermocouple sheath 1142. This ensures that the sensing end of the thermocouple can fully and directly sense the bed material temperature.

[0049] This embodiment effectively solves the structural deformation problem caused by thermal expansion by introducing an installation sleeve 113, an inner protective sleeve 111, and a first gap 121 between them, and a second gap 122 between the inner protective sleeve 111 and the bed temperature thermocouple sleeve 114, and optimizing the dimensions of these gaps. Simultaneously, the added outer protective sleeve 112, its specific height design relative to the vent cap, the V-shaped pin 16, and the reinforcement of the material and structure of the bed temperature thermocouple sleeve itself provide stronger mechanical protection and wear resistance for the thermocouple, laying the foundation for further wear-resistant protection measures, thereby significantly improving the reliability and service life of the entire bed temperature thermocouple installation structure.

[0050] In yet another preferred embodiment, such as Figures 6 to 9 As shown, the circulating fluidized bed boiler bed temperature thermocouple installation structure 1 of the present invention, based on Embodiment 2, provides an extremely reliable and durable protection scheme, particularly suitable for the harsh high-temperature, high-speed particle erosion, and complex operating conditions of severe thermal expansion and contraction within a circulating fluidized bed boiler. This embodiment integrates the core sliding compensation mechanism and multi-layer sleeve protection structure of the aforementioned embodiments, and creatively introduces a refractory mud protective layer and a convenient maintenance design, thereby achieving significant technical and economic benefits in practical engineering applications.

[0051] The installation structure 1 in this embodiment also includes an installation sleeve 113, an inner protective sleeve 111, an outer protective sleeve 112, and a first gap 121 and a second gap 122 located between them. The structure, connection relationship, sliding compensation principle, and preferred gap size of these components (for example, the radial dimension of both the first gap 121 and the second gap 122 is at least 0.5 mm) are similar to those described in Embodiment 2, and will not be repeated here. Together, they form the basis for adapting to thermal expansion and preventing structural deformation. The installation angle, sleeve material (e.g., the second material segment 1142 is made of high-temperature special wear-resistant material, and the first material segment 1141 is made of stainless steel 2520 material), wear-resistant section length (not less than 500 mm), connection method, and connection part treatment (e.g., polished surface) of the bed temperature thermocouple (the core is the bed temperature thermocouple measuring insert 15, and it has segmented material bed temperature thermocouple sleeves 114, including ordinary bed temperature thermocouple sleeve 1141 and wear-resistant bed temperature thermocouple sleeve 1142) are also consistent with those of the aforementioned embodiments.

[0052] Reference Figure 6 , Figure 7 ( Figure 6 (enlarged view of a portion of region D) and Figure 8 ( Figure 6 (A magnified view of a portion of region E in the diagram). One of the innovations of this embodiment is the addition of comprehensive refractory mortar protection. Specifically, it includes:

[0053] A conical refractory mortar layer 131 is securely fixed to the outer circumferential surface of the outer protective sleeve 112 by multiple fasteners, preferably V-shaped pins 16. Figure 7 As shown, multiple V-shaped pins 16 are fixedly disposed on the outer circumferential surface of the outer protective sleeve 112, for example by welding. They are distributed along the axial and circumferential directions of the outer protective sleeve 112, providing a solid anchoring foundation for the refractory mortar. The conical refractory mortar layer 131 is laid and anchored on and between these V-shaped pins 16, completely covering the outer surface of the outer protective sleeve 112 from the furnace air distribution plate 21 upwards, and extending upwards to or near the top of the outer protective sleeve 112, forming an integral protective layer with a specific conical profile. This conical design (smaller at the top and larger at the bottom or approximately streamlined) has proven extremely important in practical engineering, as it can very effectively change the air distribution from the nearby air cap 22 ( Figure 7 The primary air (such as air jets at high speed from the ventilation holes 221 of the vent cap (as shown in the diagram), which is mixed with a large number of solid bed material particles, is ejected from the vents. Figure 6The airflow direction (indicated by the arrow in the middle) is as follows. These high-speed, dust-laden airflows would normally directly impact the thermocouple mounting structure, causing severe "sandblasting" wear. However, the presence of the conical refractory mortar layer 131 allows the airflow to smoothly bypass it, or its impact force is effectively absorbed and dispersed by the refractory mortar layer, thus greatly reducing the direct wear on the outer protective sleeve 112 and the inner sleeve. This is one of the key measures to prevent premature damage to the thermocouple due to wear. At the same time, the conical refractory mortar layer 131 also completely covers the connection area between the outer protective sleeve 112 and the furnace air distribution plate 21, providing additional sealing and protection.

[0054] And the bottom refractory mortar 132, such as Figure 6 and Figure 8 As shown, the bottom refractory mortar 132 is applied to the upper surface of the bottom sealing plate 31 of the wind chamber and surrounds the lower part of the mounting sleeve 113. This bottom refractory mortar 132 not only serves a sealing function, preventing high-pressure air in the wind chamber 3 or potentially leaking flue gas in the furnace 2 from escaping through the installation gap, but also provides some fixation and protection for the root of the mounting sleeve 113 and reduces heat loss in that area.

[0055] In this embodiment, the top of the outer protective sleeve 112 (along with the top of the conical refractory mortar layer 131 outside it) is higher than the air outlet of the furnace vent cap 22, and the vertical height difference between the two is designed to be at least 100mm. This specific height difference further ensures that the mainstream high-speed dust-laden airflow ejected from the vent cap is unlikely to directly impact the top of the outer protective sleeve 112 and the inner structure, complementing the guiding effect of the conical refractory mortar, and together forming a strong wear-resistant barrier.

[0056] The measuring end of the bed temperature thermocouple, i.e., the top of the wear-resistant sheath 1142, extends from the top of the conical refractory mud layer 131 and the outer protective sheath 112, directly contacting the bed material inside the furnace 2. To ensure measurement accuracy and rapid response to bed material temperature, no other coaxially arranged protective sheaths, except for the sheath of the bed temperature thermocouple itself (i.e., the wear-resistant sheath 1142), surround the radial portion forming the measuring part at the top of the bed temperature thermocouple sheath 114, ensuring full exposure of the sensing end.

[0057] Reference Figure 6 and Figure 9 ( Figure 6(Partial enlarged view of area F in the diagram) This embodiment also optimizes the maintenance and replacement method of the thermocouple. The bed temperature thermocouple sheath 114 (specifically, its lower end ordinary bed temperature thermocouple sheath 1141 or a special connection structure) is connected to a thermocouple extension tube 141 by threads. This connection can be achieved through a specially designed bed temperature thermocouple sheath connector 142, one end of which is connected to the bed temperature thermocouple sheath 114, and the other end is threaded to the thermocouple extension tube 141. The thermocouple extension tube 141 is located at the bottom 4 of the boiler, usually below the flange 17. This design allows maintenance personnel to easily remove and replace the entire bed temperature thermocouple measuring insert 15, along with its sheath 114 (or just the insert itself, depending on the specific design), from the mounting structure outside the boiler when a damaged bed temperature thermocouple measuring insert 15 needs to be replaced. This is achieved by simply unscrewing the threaded connection between the thermocouple extension tube 141 and the bed temperature thermocouple sheath connector 142, without having to disassemble the flange 17 or more complex components. This allows for online or rapid replacement of the measuring insert, greatly simplifying the maintenance process, shortening downtime or load reduction time, and reducing maintenance costs.

[0058] This embodiment utilizes a complete set of protection mechanisms, namely: the strong wear resistance provided by the wear-resistant sheath 1142 of the bed temperature thermocouple, the additional mechanical protection provided by the outer protective sheath 112, the further isolation provided by the inner protective sheath 111, and the key anti-erosion and flow guiding function of the outermost conical refractory mud layer 131, combined with the thermal expansion sliding compensation provided by the first gap 121 and the second gap 122, so that the entire bed temperature thermocouple installation structure 1 can work stably for a long time in the extremely harsh operating environment of the circulating fluidized bed boiler.

[0059] Practical engineering applications show that the overall performance and service life of the bed temperature thermocouple are significantly improved after adopting the installation structure described in this embodiment. Specifically, its beneficial effects are reflected in the following aspects:

[0060] First, it significantly extends the service life of bed temperature thermocouples, substantially reducing maintenance costs. Previously, thermocouples using traditional installation methods typically had a service life of only a few months due to their inability to effectively cope with thermal expansion stress and wear from the harsh furnace environment, requiring frequent replacement. However, with the installation structure described in this invention, the dual sliding compensation mechanism of the first gap 121 and the second gap 122 effectively eliminates thermal stress damage. Simultaneously, the multi-layered, all-around protection system, consisting of the bed temperature thermocouple wear-resistant sheath 1142, the outer protective sheath 112, the inner protective sheath 111, and especially the external conical refractory mud layer 131, greatly enhances resistance to high temperatures, erosion, and wear. Therefore, the service life of the bed temperature thermocouple is successfully extended from a few months to more than two years. This extended lifespan directly leads to a significant reduction in spare parts consumption and maintenance workload. Applying this invention to circulating fluidized bed boilers can save hundreds of thousands of yuan annually in spare parts costs alone.

[0061] Secondly, the integrity and durability of the installation structure are guaranteed. During the annual planned shutdown maintenance, inspections of the thermocouples using the installation structure of this invention revealed that the lower parts of the installation sleeve 113 and inner protective sleeve 111 located in the air chamber 3 showed no bending deformation due to thermal expansion, thanks to the effective effect of the first gap 121. Simultaneously, the inner protective sleeve 111, outer protective sleeve 112, and the sleeve 114 of the bed temperature thermocouple itself located in the furnace 2 showed virtually no significant wear, protected by the conical refractory mud layer 131 and its own material. Particularly noteworthy is that the conical refractory mud layer 131 outside the outer protective sleeve 112, which serves as the main wear-resistant barrier, maintained over 90% integrity after prolonged operation, requiring only minor inspections and localized repairs for continued use.

[0062] Furthermore, this ensures the accuracy and reliability of bed temperature measurement, providing a solid guarantee for the safe and economical operation of the boiler. Due to the secure installation and proper protection of the thermocouples, their measuring ends can continuously and accurately reflect the true bed temperature within the furnace. During long-term operation, no signal distortion has occurred due to inaccurate bed temperature measurement or thermocouple damage, effectively avoiding potential misjudgments of boiler combustion conditions and improper operation. In particular, it prevents serious accidents such as boiler coking and flameout caused by excessively high or low bed temperatures, strongly guaranteeing the company's normal, continuous, and efficient production.

[0063] Furthermore, it significantly improves the convenience and efficiency of maintenance. As mentioned earlier, the threaded connection design between the bed temperature thermocouple sheath 114 and the thermocouple extension tube 141 allows for online or rapid replacement of the bed temperature thermocouple measuring insert 15. This means that when the measuring insert 15 reaches the end of its service life or is accidentally damaged, maintenance personnel can complete the replacement in a short time without waiting for the boiler to be shut down, greatly shortening the troubleshooting time and improving the availability of the equipment.

[0064] Finally, it also has significant advantages in terms of the economy and durability of wear-resistant measures. Compared with wear-resistant solutions that simply rely on increasing the thickness of the metal protective sleeve or using more expensive alloy materials, the refractory mortar (especially the conical refractory mortar layer 131) used in this invention as the main external wear-resistant layer is not only readily available and inexpensive, but also possesses excellent high-temperature resistance and wear resistance, and is sturdy and durable after being laid and formed. More importantly, the maintenance of the refractory mortar is very simple. Each time the machine is shut down for maintenance, only a routine inspection of the refractory mortar layer is needed, and local repairs are required for a few damaged areas to restore its protective function. Compared with replacing the entire metal protective sleeve, this undoubtedly greatly reduces maintenance costs and workload.

[0065] In summary, this embodiment, through its unique structural design and multiple protection mechanisms, not only fundamentally solves the problems of easy damage, short lifespan, and difficult maintenance of bed temperature thermocouples in existing technologies, but also brings significant economic benefits and production safety guarantees to enterprises in practical applications. It has extremely high promotion and application value and reflects social benefits.

[0066] It should be noted that the terms "first," "second," and "third" in this application are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0067] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. Any equivalent device or equivalent process transformation made based on the content of this application specification and drawings, or direct or indirect application in other related technical fields, are similarly included in the patent protection scope of this application.

Claims

1. A bed temperature thermocouple installation structure for a circulating fluidized bed boiler, wherein the bed temperature thermocouple is disposed inside the boiler, with a portion located at the bottom of the boiler and a portion located in the air chamber, its measuring end located inside the furnace and extending upward from the bottom of the boiler through the air chamber to the furnace, characterized in that, include: The bed temperature thermocouple is set basically in the vertical direction, and the angle between its axis and the vertical direction does not exceed 5°. The mounting sleeve is fixedly connected to the air chamber sealing plate at its lower part. An inner protective sleeve is provided, the upper part of which is fixedly connected to the furnace air distribution plate, and the lower part of which is accommodated in the mounting sleeve. The bed temperature thermocouple is accommodated in the inner protective sleeve. The mounting sleeve and the inner protective sleeve are fitted together by a socket joint, and a first gap is preset to allow the inner protective sleeve to slide relative to the mounting sleeve. A second gap is pre-set between the inner protective sleeve and the bed temperature thermocouple sleeve, allowing the bed temperature thermocouple sleeve to slide relative to the inner protective sleeve.

2. The thermocouple installation structure for circulating fluidized bed boiler bed temperature according to claim 1, characterized in that, It also includes an outer protective sleeve; The outer protective sleeve is coaxially fitted over the portion of the inner protective sleeve that extends upwards into the furnace from the furnace air distribution plate. The lower end of the outer protective sleeve starts from the upper surface of the furnace air distribution plate, and the outer protective sleeve is fixedly connected to the furnace air distribution plate.

3. The thermocouple mounting structure for circulating fluidized bed boilers according to claim 2, characterized in that, The top of the outer protective sleeve is higher than the air outlet of the inner wind cap of the furnace, and the height difference between the two in the vertical direction is at least 100mm.

4. The thermocouple installation structure for circulating fluidized bed boiler bed temperature according to claim 3, characterized in that, The mounting structure also includes: A conical refractory mortar layer is fixed to the outer surface of the outer protective sleeve by multiple fasteners. The conical refractory mortar layer covers the inner protective sleeve and the furnace air distribution plate, and extends upward to the top of the outer protective sleeve. And bottom refractory mortar, which is applied to the upper surface of the bottom sealing plate of the air chamber and surrounds the mounting sleeve.

5. The circulating fluidized bed boiler bed temperature thermocouple installation structure according to claim 4, characterized in that, The fastener is a V-shaped pin; Multiple V-shaped pins are fixedly disposed on the outer circumferential surface of the outer protective sleeve, and the conical refractory mortar layer is laid and anchored on the multiple V-shaped pins.

6. The thermocouple mounting structure for circulating fluidized bed boilers according to claim 1, characterized in that, The first gap and the second gap are at least 0.5 mm.

7. The thermocouple mounting structure for circulating fluidized bed boilers according to claim 1, characterized in that, The bed temperature thermocouple sheath includes a first material segment and a second material segment; The second material segment is made of high-temperature wear-resistant material and is located at the head of the bed temperature thermocouple. The length measured downward from the top of the bed temperature thermocouple is not less than 500 mm. The first material segment is made of stainless steel 2520 and is fixedly connected to the second material segment. The connection between the first material segment and the second material segment has a polished surface.

8. The thermocouple mounting structure for circulating fluidized bed boilers according to claim 7, characterized in that, The composition of the high-temperature extra-grade wear-resistant material, by weight percentage, includes: 28% to 35% chromium (Cr), 2% to 5% manganese (Mn), 2% to 6% molybdenum (Mo), 1% to 3% silicon (Si), 20% to 26% nickel (Ni), 4% to 10% tungsten (W), 4% to 10% cobalt (Co), no more than 0.04% sulfur (S), no more than 0.04% phosphorus (P), 0.5% to 0.7% aluminum (Al), and 8% to 12% rare earth elements (RE).

9. The thermocouple mounting structure for circulating fluidized bed boilers according to claim 1, characterized in that, The bed temperature thermocouple sheath is also connected to a thermocouple extension tube via threads. The thermocouple extension tube is located at the bottom of the boiler to allow for replacement of the measuring insert of the bed temperature thermocouple.

10. The thermocouple mounting structure for circulating fluidized bed boilers according to claim 1, characterized in that, Around the temperature measuring portion at the top of the bed temperature thermocouple sheath, there are no other coaxially arranged protective sleeves besides the bed temperature thermocouple sheath.

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