A Small Header Structure and Working Method for a 650℃ High-Efficiency Ultra-Supercritical Tower Boiler

Abstract

This invention discloses a small header structure and operating method for a 650℃ high-efficiency ultra-supercritical tower boiler, relating to the field of boiler technology. It solves the problem of reaching the upper limit of ferritic heat-resistant steel in the main and reheat steam outlet headers of tower boilers. The invention includes a main header, connecting pipes, a small header, and an outlet pipe joint. Each tube panel of the final stage superheater or reheater in the tower boiler is connected to a small header via an outlet pipe joint; the small header is connected to the main header via connecting pipes; the main header, connecting pipes, and small header are all made of iron-nickel-based high-temperature alloy materials. This invention, through the main and reheat steam outlet header and small header structure, can reduce inter-tube temperature deviation, effectively eliminating the thermal stress caused by inter-tube deviation in conventional large header schemes. It can also reduce the wall thickness of the main header, as thermal stress is proportional to wall thickness, thus reducing thermal stress, improving compressive strength, and facilitating flexible operation.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, specifically to a small header structure and working method for a 650℃ high-efficiency ultra-supercritical tower boiler. Background Technology

[0002] Currently, the highest main and reheat steam temperatures of high-efficiency ultra-supercritical boilers in my country reach 610℃ / 625℃. The main and reheat steam outlet headers, pipes, and fittings are made of P92 / T92 steel. Tower boilers all use large header designs for their main and reheat steam outlet headers, reaching the upper limit for ferritic heat-resistant steel. Therefore, GH2070P, a new iron-nickel-based high-temperature alloy material developed by Xi'an Thermal Power Research Institute Co., Ltd., was selected for the design of the main and reheat steam outlet headers and pipes for a 650℃ high-efficiency ultra-supercritical boiler. The parameters of the 650℃ high-efficiency ultra-supercritical boiler are 36.65MPa.g and 655℃ / 653℃. If a conventional large header design is used for the main and reheat steam outlet headers, the temperature deviation at the pipe fittings will be greater due to the increased main and reheat steam outlet temperatures (45℃ / 25℃ respectively). This will make the connection between the large header and the pipe fittings more prone to thermal stress concentration, increasing the risk of thermal fatigue failure. Currently, there are requirements for rapid load change rates and safe and reliable technology. Therefore, thick-walled headers experience thermal deformation, thermal stress, and thermal fatigue under high transient, strong impact, and fluid-thermal-mechanical coupling effects, leading to fatigue cracking of the headers and fracture of welded joints. GH2070P is an age-hardening iron-nickel-based alloy material, widely used in aerospace and other fields. Its large-scale application in pressure-bearing components is a first in the boiler manufacturing industry. This material has a high coefficient of thermal expansion, low thermal conductivity, and high sensitivity to hot cracking, exhibiting a tendency for welding hot cracking, liquefaction cracking, reheat cracking, and strain-aging cracking. Manufacturing, on-site installation, and maintenance are highly challenging, and quality control is extremely stringent. Therefore, the application of the new iron-nickel-based high-temperature alloy material GH2070P in the design of key boiler components directly affects the long-term safe operation of the boiler. Summary of the Invention

[0003] To address the aforementioned issue of existing tower boiler main and reheat steam outlet headers reaching the upper limit for the use of ferritic heat-resistant steel, this invention proposes a 650℃ high-efficiency ultra-supercritical tower boiler small header structure and its operating method. This invention, through the small header structure of the main and reheat steam outlet headers, can reduce inter-tube temperature deviation, effectively eliminating thermal stress caused by inter-tube deviation in conventional large header designs. It can also reduce the wall thickness of the large header, as thermal stress is proportional to wall thickness, thus reducing thermal stress, improving compressive strength, and facilitating flexible operation.

[0004] This invention proposes a small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler, which specifically includes a collection header, a connecting pipe, and a small header. Each tube panel of the final stage superheater or final stage reheater in the tower boiler is connected to a small header. The connecting pipe is a straight pipe, with one end connected to the small header and the other end connected to the collection header.

[0005] Furthermore, the connection point between the connecting pipe and the small header is located at the upper center of the small header.

[0006] Furthermore, it also includes an outlet pipe connector, one end of which passes through the water-cooled wall of the tower boiler and connects to the tube screen of the final superheater or final reheater, while the other end connects to the small header.

[0007] Furthermore, the outlet pipe joint is fixedly connected to the water-cooled wall.

[0008] Furthermore, the connection point between the outlet pipe fitting and the small header is located at the bottom of the small header.

[0009] Furthermore, the outlet pipe fitting is an L-shaped pipe.

[0010] Furthermore, the outlet pipe fitting is made of GH4070T, an iron-nickel-based high-temperature alloy.

[0011] Furthermore, the connecting pipe is made of GH2070P, an iron-nickel-based high-temperature alloy.

[0012] Furthermore, the main collection box and the small collection box are made of GH2070P, a high-temperature alloy material based on iron and nickel.

[0013] A method for operating the small header structure of the 650℃ high-efficiency ultra-supercritical tower boiler described above, wherein the working fluid in the tube panel of the final stage superheater or final stage reheater of the tower boiler enters the small header through the outlet pipe joint for initial mixing, and then enters the collection header through the connecting pipe for mixing with the working fluid in other tube panels.

[0014] The beneficial effects of the small header structure and working method of the 650℃ high-efficiency ultra-supercritical tower boiler described in this invention are as follows: (1) The present invention describes a 650℃ high-efficiency ultra-supercritical tower boiler small header structure and working method. The small header structure of the 650℃ high-efficiency ultra-supercritical tower boiler utilizes a novel iron-nickel-based high-temperature alloy material GH2070P. The enhanced pipe joints of the final stage superheater and final stage reheater absorb the structural stress caused by temperature deviation between the small header and the water-cooled wall, reducing inter-pipe temperature deviation and effectively eliminating thermal stress caused by inter-pipe deviation in conventional large header designs. This reduces the outer diameter and wall thickness of the header by more than 10%, thereby reducing thermal stress, improving compressive strength, and decreasing the possibility of header fatigue cracking and weld joint fracture, facilitating flexible operation. The smaller header size achieved by using the novel iron-nickel-based high-temperature alloy material GH2070P weakens welding restraint stress, reduces the number of GH2070P welds during on-site installation by more than 95%, reduces manufacturing and installation difficulty, allows for greater maintenance clearance, and facilitates on-site operation and maintenance. To improve the operational safety of key components of a 650℃ high-efficiency ultra-supercritical tower boiler using the new iron-nickel-based high-temperature alloy material GH2070P, and to ensure safe, efficient, and flexible operation at 650℃ high-efficiency ultra-supercritical temperature. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, 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 improper limitation of the invention.

[0016] In the attached diagram: Figure 1 This is a structural schematic diagram of a small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to the present invention; Wherein: 1-collector box, 2-connecting pipe, 3-small collector box, 4-outlet pipe connector, 5-water-cooled wall. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. The described embodiments are merely some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] Specific implementation method one: See Figure 1This embodiment is described in detail. The 650℃ high-efficiency ultra-supercritical tower boiler small header structure described in this embodiment specifically includes a collection header 1, a connecting pipe 2, a small header 3, and an outlet pipe connector 4. Each tube panel of the final stage superheater or final stage reheater in the tower boiler is connected to a small header 3 through the outlet pipe connector 4. One end of the outlet pipe connector 4 passes through the water-cooled wall 5 of the tower boiler and connects to the tube panel of the final stage superheater or final stage reheater, while the other end connects to the small header 3. The connecting pipe 2 is a straight pipe, with one end connected to the small header 3 and the other end connected to the collection header 1.

[0019] The connection point between the connecting pipe 2 and the small header 3 is located at the upper center of the small header 3.

[0020] The outlet pipe connector 4 is fixedly connected to the water-cooled wall 5. The connection point between the outlet pipe connector 4 and the small header 3 is located at the lower part of the small header 3, with vertically spaced side bends leading into the small header 3. The outlet pipe connector 4 is an L-shaped pipe, with an arc-shaped pipe at the 90-degree position. The outlet pipe connector 4 is made of GH4070T iron-nickel-based high-temperature alloy; the connecting pipe 2 is made of GH2070P iron-nickel-based high-temperature alloy.

[0021] The main collection box 1 is made of GH2070P, a high-temperature alloy material based on iron-nickel. The small collection box 3 is also made of GH2070P, a high-temperature alloy material based on iron-nickel.

[0022] A method for operating the small header structure of the above-mentioned 650℃ high-efficiency ultra-supercritical tower boiler, wherein the working fluid in the tube panel of the last stage superheater or last stage reheater of the tower boiler enters the small header 3 through the outlet pipe joint 4 for initial mixing, and then enters the collection header 1 through the connecting pipe 2 for mixing with the working fluid in other tube panels.

[0023] In summary, the 650℃ high-efficiency ultra-supercritical tower boiler small header structure and working method described in this invention utilizes a novel iron-nickel-based high-temperature alloy material GH2070P. The enhanced pipe joint flexibility of the final stage superheater and reheater absorbs structural stress caused by temperature deviation between the small header 3 and the water-cooled wall 5, reducing inter-tube temperature deviation and effectively eliminating thermal stress caused by inter-tube deviation in conventional large header designs. This allows for a reduction in the outer diameter and wall thickness of the header 1 by more than 10%, reducing thermal stress, improving compressive strength, and decreasing the possibility of header fatigue cracking and weld joint fracture, thus facilitating flexible operation. The smaller header size achieved through the application of the novel iron-nickel-based high-temperature alloy material GH2070P reduces welding restraint stress, reduces the number of GH2070P welds during on-site installation by more than 95%, lowers manufacturing and installation difficulty, allows for greater maintenance access, and facilitates on-site operation and maintenance. To improve the operational safety of key components of a 650℃ high-efficiency ultra-supercritical tower boiler using the new iron-nickel-based high-temperature alloy material GH2070P, and to ensure safe, efficient, and flexible operation at 650℃ high-efficiency ultra-supercritical temperature.

[0024] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the invention. They can also be reasonable combinations of the features described in the above embodiments. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler, characterized in that: Includes a collection box (1), a connecting pipe (2) and a small collection box (3). Each tube panel of the final stage superheater or final stage reheater in the tower boiler is connected to a small collection box (3). The connecting pipe (2) is a straight pipe, with one end connected to the small collection box (3) and the other end connected to the collection box (1).

2. The small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to claim 1, characterized in that: The connection point between the connecting pipe (2) and the small header (3) is located at the upper center of the small header (3).

3. The small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to claim 1, characterized in that: It also includes an outlet pipe connector (4), one end of which passes through the water-cooled wall (5) of the tower boiler and is connected to the tube screen of the final superheater or the final reheater, and the other end is connected to the small header (3).

4. The small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to claim 3, characterized in that: The outlet pipe joint (4) and the water-cooled wall (5) are fixedly connected.

5. The small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to claim 3, characterized in that: The connection point between the outlet pipe joint (4) and the small header (3) is located at the lower part of the small header (3).

6. The small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to claim 5, characterized in that: The outlet pipe connector (4) is an L-shaped pipe.

7. The small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to claim 6, characterized in that: The outlet pipe fitting (4) is made of iron-nickel-based high-temperature alloy material GH4070T.

8. The small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to claim 1, characterized in that: The connecting pipe (2) is made of iron-nickel-based high-temperature alloy material GH2070P.

9. The small header structure for a 650℃ high-efficiency ultra-supercritical tower boiler according to claim 1, characterized in that: The main collection box (1) and the small collection box (3) are made of GH2070P iron-nickel based high-temperature alloy material.

10. A method for operating the small header structure of the 650℃ high-efficiency ultra-supercritical tower boiler as described in claim 3, characterized in that: The working fluid in the tube panel of the final superheater or final reheater of the tower boiler enters the small header (3) through the outlet pipe joint (4) for a first mixing, and then enters the collection box (1) through the connecting pipe (2) to mix with the working fluid in other tube panels.

Images