Two-stage mixing end leading-out structure of small header of 650 DEG C efficient ultra-supercritical tower type boiler

Abstract

The invention discloses a two-stage mixing end leading-out structure for a small header of a 650 DEG C efficient ultra-supercritical tower type boiler, relates to the technical field of boilers, and solves the problem that main and reheated steam outlet headers of the tower type boiler reach the upper use limit of ferrite heat-resistant steel. The device comprises a collection box, a connecting pipe, small collection boxes and outlet pipe joints, wherein each pipe panel of a final-stage superheater or a final-stage reheater of the tower-type boiler is communicated with one small collection box through the outlet pipe joint; two connecting pipes are symmetrically arranged on the small header, and the small header is communicated with the collecting header through the connecting pipes; the collecting header, the connecting pipe and the small header are all made of iron-nickel-based high-temperature alloy materials. Through the end part leading-out structure of the two-stage mixed small header of the main and reheat steam outlet header, the temperature deviation between the pipes can be reduced, the thermal stress caused by the deviation between the pipes in the conventional large header scheme is effectively eliminated, the wall thickness of the collecting header and the specifications of the pipe joints of the header body are reduced, and the thermal stress and the wall thickness are in direct proportion, so that the thermal stress can be reduced, and the anti-pressure capability is improved.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly processing technology, specifically to a dual-stage mixing end lead-out structure for a 650℃ high-efficiency ultra-supercritical tower boiler with a small header. Background Technology

[0002] Currently, the highest main and reheat steam temperatures in my country's high-efficiency ultra-supercritical boilers 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. A new iron-nickel-based high-temperature alloy material, GH2070P, developed by Xi'an Thermal Power Research Institute Co., Ltd., was selected for designing the main and reheat steam outlet headers and pipes for a 650℃ high-efficiency ultra-supercritical boiler. The parameters for a 650℃ high-efficiency ultra-supercritical boiler are 36.65 MPa.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. Current demands for rapid load changes and reliable safety technologies mean that thick-walled headers, under high transient, strong impact, and thermo-mechanical coupling effects, experience thermal deformation, thermal stress, and thermal fatigue, leading to fatigue cracking and weld joint fracture. 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 susceptibility to hot cracking, exhibiting a tendency for weld hot cracking, liquefaction cracking, reheat cracking, and strain-aging cracking. Manufacturing, on-site installation, and maintenance are challenging, requiring extremely strict quality control. Larger outer diameters and thicker pipe joints of GH2070P headers increase welding stress and raise the risk of weld cracking. 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 two-stage mixing end-outlet structure for the small header of a 650℃ high-efficiency ultra-supercritical tower boiler. This invention, through the two-stage mixing end-outlet structure of the main and reheat steam outlet headers, can reduce inter-pipe temperature deviation, more effectively eliminate thermal stress caused by inter-pipe deviation in conventional large header designs, and reduce the thickness of the header wall and the specifications of the header body pipe joints. Since thermal stress is proportional to wall thickness, this reduces thermal stress, improves compressive strength, and facilitates flexible operation.

[0004] This invention proposes a dual-stage mixing end lead-out structure for a 650℃ high-efficiency ultra-supercritical tower boiler with a small header. Specifically, it includes a collection header, two connecting pipes, 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. Two connecting pipes are symmetrically arranged on the small header, with one end of the connecting pipe 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 end 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 above-mentioned 650℃ high-efficiency ultra-supercritical tower boiler double-stage mixing small header end lead-out structure, 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 through the outlet pipe joint for primary mixing, and then enters the collection header through the connecting pipe to mix with the working fluid in other tube panels.

[0014] The beneficial effects of the 650℃ high-efficiency ultra-supercritical tower boiler small header two-stage mixing end lead-out structure described in this invention are as follows: (1) The 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure described in this invention, by applying the new iron-nickel-based high-temperature alloy material GH2070P to the 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure, can reduce the temperature deviation between pipes, enhance the flexibility of pipe joints, absorb the structural stress caused by the temperature deviation between the small header and the water-cooled wall, and effectively eliminate the thermal stress caused by the pipe deviation in conventional large header schemes. It can reduce the outer diameter, wall thickness, and pipe joint specifications of the header by more than 10%, reduce thermal stress, improve compressive strength, reduce the possibility of header fatigue cracking and weld joint fracture, weaken welding restraint stress, reduce welding stress concentration and weld cracking risk, reduce the number of GH2070P welds in the field installation by 90%, make it easier for manufacturers to achieve mechanical welding, reduce manufacturing difficulty, and improve product qualification rate. It can reduce installation difficulty, allow for greater maintenance, and facilitate 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 schematic diagram of the structure of the dual-stage mixing end lead-out structure of the small header of 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 dual-stage mixing end lead-out structure described in this embodiment specifically includes a small header 1, two connecting pipes 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. Two connecting pipes 2 are symmetrically arranged on the small header 3, one end of which connects to the end of the small header 3, and the other end connects to the small header 1. The connecting pipes 2 are U-shaped.

[0019] The outlet pipe connector 4 is fixedly connected to the water-cooled wall 5. The connection position between the outlet pipe connector 4 and the small header 3 is located at the lower part of the small header 3. The outlet pipe connector 4 is an L-shaped pipe. The material of the outlet pipe connector 4 is GH4070T, an iron-nickel-based high-temperature alloy. The material of the connecting pipe 2 is GH2070P, an iron-nickel-based high-temperature alloy.

[0020] 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.

[0021] A working method for the above-mentioned 650℃ high-efficiency ultra-supercritical tower boiler small header bi-stage mixing end lead-out structure, wherein the working fluid in the tube screen 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 primary mixing, and then enters the collection and collection box 1 through the connecting pipe 2 to mix with the working fluid in other tube screens, thus forming a bi-stage mixing structure.

[0022] In summary, the 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure described in this invention, using the novel iron-nickel-based high-temperature alloy material GH2070P, can reduce inter-pipe temperature deviation, enhance pipe joint flexibility, absorb structural stress caused by temperature deviation between the small header 3 and the water-cooled wall 5, and effectively eliminate thermal stress caused by inter-pipe deviation in conventional large header schemes. It can reduce the outer diameter, wall thickness, and pipe joint specifications of the header 1 by more than 10%, reduce thermal stress, improve compressive strength, reduce the possibility of header fatigue cracking and weld joint fracture, weaken welding restraint stress, reduce welding stress concentration and weld cracking risk, reduce the number of GH2070P welds required for on-site installation by 90%, making it easier for manufacturers to perform mechanical welding, reducing manufacturing difficulty, and improving product qualification rate. It also reduces 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.

[0023] 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 dual-stage mixing end-out structure for a small header of a 650℃ high-efficiency ultra-supercritical tower boiler, characterized in that: Includes a collection box (1), two connecting pipes (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). Two connecting pipes (2) are symmetrically arranged on the small collection box (3). One end of the connecting pipe (2) is connected to the small collection box (3), and the other end is connected to the collection box (1).

2. The 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure according to claim 1, characterized in that: The connection point between the connecting pipe (2) and the small header (3) is located at the end of the small header (3).

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

5. The 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure 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 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure according to claim 5, characterized in that: The outlet pipe connector (4) is an L-shaped pipe.

7. The 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure 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 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure according to claim 1, characterized in that: The connecting pipe (2) is made of iron-nickel-based high-temperature alloy material GH2070P.

9. The 650℃ high-efficiency ultra-supercritical tower boiler small header double-stage mixing end lead-out structure 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 dual-stage mixing end lead-out structure of the small header 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.

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