High-pressure waste heat boiler for high-temperature and high-pressure flue gas

Abstract

The utility model relates to a high-pressure waste heat boiler for high-temperature and high-pressure flue gas, which comprises a high-temperature evaporator shell provided with two high-temperature evaporators along the flue gas inlet direction. The low-temperature evaporator shell is positioned in the flue gas outlet direction of the high-temperature evaporator shell and is used for shunting the flue gas through a connecting flue; the low-temperature evaporator and the high-temperature evaporator are each internally provided with a plurality of heat exchange pipe pieces distributed side by side, the upper ends and the lower ends of the heat exchange pipe pieces are both connected with transverse pipes, and the two sides of each transverse pipe are both connected with collecting boxes. The device is compact and reasonable in structure and convenient to operate, the transverse pipes are arranged at the water inlet end and the water outlet end of each pipe piece, the two sides of each transverse pipe are connected with the corresponding collecting boxes, and meanwhile the collecting boxes on the pipe pieces are communicated with one another to form a large collecting box to achieve collection and dispersion of steam-water mixtures. The upper collecting box and the lower collecting box are connected with the boiler barrel through the multiple ascending pipes and the multiple descending pipes respectively, water can be fed into each pipe piece evenly, hydraulic deviation is small, water circulation is better, and the evaporation efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat boilers, in particular to a high-pressure waste heat boiler for high-temperature and high-pressure flue gas. Background Art

[0002] A waste heat boiler is a commonly used device for recycling the energy of industrial high-temperature waste gas and is applied to various different industrial fields. When recovering high-temperature flue gas, a water-tube or shell-type heat exchange structure is generally adopted. When the flue gas volume is small and the sealing requirement is high, a shell-type heat exchange structure is usually adopted. In the chemical industry, the operating pressure of the nitrous oxide catalytic cracking tail gas is 0.15 MPa and the temperature is 700 °C. Technologically, steam with a pressure of 10 MPa needs to be generated for waste heat recovery and utilization, and 530 °C flue gas needs to be recycled.

[0003] If a shell-type heat exchange structure is adopted, since GB / T 16508-2022 "Shell Boilers" stipulates that it is only used for horizontal smoke tube structures with a pressure less than 5.3 MPa, only a water-tube heat exchange structure can be adopted.

[0004] For example, Chinese Patent CN117989504A discloses a waste heat boiler for nitrous oxide catalytic cracking tail gas. In this patent, a water-tube heat exchange component is arranged inside a cylindrical shell. However, in actual use, there is a big problem with this solution, that is, since there is one inlet and one outlet for this solution, and they are located at both ends of the evaporator, the water inlet is not uniform enough, resulting in a relatively large hydraulic deviation among the tube sheets. Moreover, the heat exchange tube sheets are arranged in an S shape, the water flow path is long, and after the water passes through a long tube sheet, the water flow rate will be greatly reduced, and the steam-water discharge is slow, thus affecting the evaporation efficiency.

[0005] Therefore, we propose a high-pressure waste heat boiler for high-temperature and high-pressure flue gas. Summary of the Utility Model

[0006] The applicant of the present utility model aims at the above-mentioned disadvantages in the existing production technology and provides a high-pressure waste heat boiler for high-temperature and high-pressure flue gas. By arranging a horizontal tube at the water inlet and outlet ends of each tube sheet, corresponding headers are connected to both sides of the horizontal tube, and the upper header and the lower header are respectively connected to the drum through a plurality of riser tubes and downcomer tubes. The inlet and outlet water pipe joints of the headers are evenly arranged, which can make the hydraulic deviation in each tube sheet smaller, the water circulation better, and the evaporation efficiency improved.

[0007] The technical solution adopted by the present utility model is as follows:

[0008] A high-pressure waste heat boiler for high-temperature and high-pressure flue gas, comprising:

[0009] A high-temperature evaporator shell, inside which two high-temperature evaporators are arranged along the direction of flue gas entry;

[0010] The low-temperature evaporator shell is located in the flue gas outlet direction of the high-temperature evaporator shell and diverts the flue gas through a connecting flue. Part of the flue gas enters the low-temperature evaporator shell where a low-temperature evaporator and a economizer are installed.

[0011] A plurality of heat exchange tube sheets arranged side by side are provided in both the low-temperature evaporator and the high-temperature evaporator. The upper and lower ends of the heat exchange tube sheets are connected with horizontal tubes, and header tanks are connected to both sides of the horizontal tubes. The upper and lower header tanks of the plurality of heat exchange tube sheets are connected through and docked with the boiler drum through a plurality of riser tubes / downcomer tubes.

[0012] Further, it also includes a connecting flue which is arranged at the outlet position of the high-temperature evaporator shell and is connected to the low-temperature evaporator shell. A flue gas recirculation interface is provided on the connecting flue to divert the flue gas.

[0013] As a further improvement of the above technical solution:

[0014] Further, the tube sheets in the low-temperature evaporator adopt spiral fin tubes.

[0015] Further, the high-temperature evaporator near the flue gas inlet direction in the high-temperature evaporator shell adopts plain tubes, and the other high-temperature evaporator adopts spiral fin tube sheets.

[0016] Further, an economizer is also provided in the low-temperature evaporator shell. The economizer is provided with two header tanks for inlet / outlet. The outlet header tank of the economizer is connected to the water inlet of the boiler drum through a pipeline; the inlet header tank of the economizer is the boiler feed water inlet.

[0017] Further, a plurality of pipe joints on the upper header tanks of the low-temperature evaporator and the two high-temperature evaporators extend out of the corresponding shells and are respectively connected to the riser tube joints of the boiler drum through riser tubes; a plurality of pipe joints on the lower header tanks of the low-temperature evaporator and the two high-temperature evaporators extend out of the corresponding shells and are respectively connected to the downcomer tube joints of the boiler drum through downcomer tubes to realize the intercommunication between the two. The pipe joints on the header tanks are hermetically connected to the high-temperature and low-temperature shells through expansion joints.

[0018] Further, both the low-temperature evaporator shell and the high-temperature evaporator shell are cylindrical, and the diameter of the low-temperature evaporator shell is smaller than that of the high-temperature evaporator shell, and the tube sheet structure of the low-temperature evaporator shell is also smaller than that of the high-temperature evaporator shell.

[0019] Further, heat insulation layers are laid inside the low-temperature evaporator shell and the high-temperature evaporator shell.

[0020] Further, on the flue gas inlet side, a flue gas baffle is provided between the shell and the tube sheet. The heat exchange tubes of the tube sheet are arranged vertically, and the heat exchange tubes of the economizer are arranged horizontally.

[0021] Further, it further includes a steel frame, which fixes the two shells and the drum together to form an integral structure. A plurality of interfaces for docking with the riser tubes / downcomer tubes are provided on the drum.

[0022] The beneficial effects of the present utility model are as follows:

[0023] The structure of the present utility model is compact and reasonable, and it is convenient to operate. By providing horizontal tubes at the water inlet and outlet ends of each tube sheet, corresponding headers are connected to both sides of the horizontal tubes, and the upper header and the lower header are respectively docked with the drum through a plurality of riser tubes and downcomer tubes. The pipe joints are evenly arranged, which can make the hydraulic deviation in each tube sheet smaller, the water circulation better, and improve the evaporation efficiency.

[0024] At the same time, the present utility model also has the following advantages:

[0025] (1). A plurality of pipe joints at the inlets and outlets of the upper and lower headers extend out of the shell and are connected to external pipelines, which can ensure the uniform discharge of the steam-water mixture in the upper header. Similarly, a plurality of pipe joints of the lower header intake water and are evenly arranged, which can ensure the uniformity of the feed water, and the heat exchange tubes of the tube sheet are vertically arranged, so as to ensure the smoothness of the water circulation in the entire evaporation section.

[0026] (2). By providing two shells, and then assembling the corresponding evaporator and economizer in the shell, the module can be manufactured and assembled on site.

[0027] (3). By adopting two high-temperature evaporators, the evaporation efficiency is improved. Since there is a large space between the evaporator and the shell, a flue gas baffle needs to be provided to ensure the effective flushing of the heat exchange tubes by the flue gas. The flue gas coming out of the high-temperature evaporator shell is 530 °C. Because a part of the flue gas is recycled and taken away, the remaining flue gas volume becomes smaller, and the corresponding flue gas shell also needs to be smaller to maintain a reasonable flow rate of the flue gas.

[0028] (4). The flue gas pressure of a conventional waste heat boiler is negative pressure or slightly positive pressure, and the flue gas channel is generally a square flue. However, the square flue cannot withstand too high a pressure, and the flue gas is generally not more than 0.01 MPa. If a square flue is adopted, when the pressure is too high, the square structure is prone to deformation, resulting in instability, and an analytical design method needs to be adopted. While the boiler in the present utility model adopts a cylindrical shell, which improves the pressure-bearing effect and can withstand a pressure greater than 0.15 MPa during actual use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a top view (excluding the drum) of the patent of the present utility model.

[0030] Figure 2 It is a side view of the patent of the present utility model.

[0031] Figure 3 This is the front view of the high-temperature evaporator of the utility model patent.

[0032] Figure 4 This is the pipe segment assembly drawing of the utility model patent.

[0033] Wherein: 1. Low-temperature evaporator shell; 2. High-temperature evaporator shell; 3. Drum; 4. Rising pipe; 5. Downcomer; 6. Steel frame; 7. Connecting flue; 8. Upper header I; 9. Lower header II; 10. Support; 11. Support; 12. Upper header II; 13. Lower header II; 14. Low-temperature evaporator; 15. Economizer; 16. High-temperature evaporator I; 17. High-temperature evaporator II; 18. Insulation layer; 19. Pipe segment I; 20. Pipe segment II; 21. Flue gas baffle; 22. Expansion joint, 23. Horizontal pipe. Specific embodiments

[0034] The following combines with the attached drawings to illustrate the specific embodiments of the present utility model.

[0035] As Figures 1 - 4 shown, this embodiment discloses a high-pressure waste heat boiler for high-temperature and high-pressure flue gas. The utility model patent relates to the technical field of waste heat boilers and is a high-pressure waste heat boiler for high-temperature and high-pressure flue gas. It includes a steel frame 6, a drum 3, a high-temperature evaporator shell 2, a low-temperature evaporator shell 1, and a connecting flue 7. The drum 3 is fixed on the upper part of the steel frame 6, and the low-temperature evaporator shell 1 is arranged at the lower part of the steel frame 6. The inside of the low-temperature evaporator shell 1 mainly includes a low-temperature evaporator 14 and an economizer 15. The utility model patent is a waste heat boiler for nitrous oxide catalytic cracking tail gas. By specially improving the pipe segment structure, the water circulation effect is improved, the hydraulic deviation is reduced, and the evaporation efficiency is increased; the heating surface of the boiler adopts smooth tubes in the high-temperature area and spiral fin tubes in the low-temperature area to strengthen heat transfer, realizing modular factory production and on-site assembly.

[0036] Among them, the drum 3 is installed on the steel frame 6;

[0037] The high-temperature evaporator shell 2 is provided with two high-temperature evaporators along the direction of flue gas entry;

[0038] The low-temperature evaporator shell 1 is located in the flue gas outlet direction of the high-temperature evaporator shell 2 and shunts the flue gas through the connecting flue 7. The low-temperature evaporator 14 and the economizer 15 are installed inside the low-temperature evaporator shell 1, and the other end of the low-temperature evaporator shell 1 is provided with a flue gas outlet;

[0039] By setting two shells and then assembling the corresponding evaporators and economizers inside the shells, modular factory production and on-site assembly are realized.

[0040] Both the low-temperature evaporator 14 and the high-temperature evaporator are provided with a plurality of heat exchange tube fins arranged vertically and side by side. Both the upper and lower ends of the heat exchange tube fins are connected to a horizontal tube 23, and headers are connected to both sides of the horizontal tube 23. The headers of the plurality of heat exchange tube fins communicate (forming upper and lower headers) and are docked with the drum 3 through a plurality of riser tubes 4 / downcomer tubes 5.

[0041] In this embodiment, it further includes a connecting flue 7, which is arranged at the outlet position of the high-temperature evaporator housing 2 and is connected to the low-temperature evaporator housing 1. A flue gas recirculation interface is arranged on the connecting flue 7 to divert the flue gas.

[0042] In this embodiment, the tube fins in the low-temperature evaporator 14 adopt spiral finned tubes.

[0043] In this embodiment, the high-temperature evaporator near the flue gas inlet direction in the high-temperature evaporator housing 2 adopts plain tube fins, and the other high-temperature evaporator adopts spiral finned tube fins.

[0044] Regarding the design of the tube fin structure, referring to a finned tube waste heat boiler disclosed in the patent application No. CN202121370872.9, the differences in the heat exchange effects of the two types of tube fins are described in this patent. Since the high-temperature evaporator near the flue gas inlet direction contacts the flue gas at a higher temperature, the plain tube fins can meet the heat exchange requirements without the need to additionally increase the contact area. After the high-temperature flue gas exchanges heat and reduces its temperature, when it contacts the subsequent other high-temperature evaporator and the low-temperature evaporator 14, the contact area is increased by adopting spiral finned tube fins, thereby meeting the heat exchange effect.

[0045] In this embodiment, an economizer 15 is further arranged in the low-temperature evaporator housing 1. The economizer 15 is provided with two headers at the inlet / outlet. The outlet header 8 of the economizer is connected to the water inlet of the drum 3 through a pipeline; the inlet header 9 of the economizer is the boiler feed water inlet.

[0046] In this embodiment, a plurality of pipe joints on the upper headers of the low-temperature evaporator 14 and the two high-temperature evaporators extend out of the corresponding housings and are respectively connected to the riser tube joints of the drum 3 through riser tubes 4; a plurality of pipe joints on the lower headers of the low-temperature evaporator 14 and the two high-temperature evaporators extend out of the corresponding housings and are respectively connected to the downcomer tube joints of the drum 3 through downcomer tubes 5 to achieve the intercommunication between the two.

[0047] In this embodiment, the low-temperature evaporator housing 1 and the high-temperature evaporator housing 2 have the same structure but different dimensions and are both cylindrical. The diameter of the low-temperature evaporator housing 1 is smaller than that of the high-temperature evaporator housing 2, and the fin structure of the low-temperature evaporator housing 1 is also smaller than that of the high-temperature evaporator housing 2. The size of the low-temperature evaporator 14 is small because, after the flue gas comes out of the high-temperature evaporator, a part of the 530-degree flue gas needs to be recycled in the system, and a part of the flue gas is extracted, so the amount of flue gas becomes smaller. Therefore, the size of the subsequent low-temperature evaporator 14 becomes smaller accordingly, and the flue gas treatment of this part can be fully realized.

[0048] In this embodiment, by adopting a circular housing, the stress on the housing is uniform, the calculation is simple, the thickness of the housing is reasonable, and the corresponding thickness can be calculated according to the use temperature and pressure. The working pressure of this time is 0.15 MPa, the calculated temperature is 350 °C (with internal insulation), the diameter of the large cylinder is 4000 mm, and the thickness is 20 mm. The diameter of the small housing is 2000, and the thickness is 12 mm.

[0049] In this embodiment, the specific structure is as follows:

[0050] As Figure 1 In the shown embodiment, it mainly includes a steam drum 3, a high-temperature evaporator housing 2. The high-temperature evaporator housing 2 is internally provided with a high-temperature evaporator I 16 and a high-temperature evaporator II 17. A flue gas baffle 21 is arranged between the housing and the fin I 19; the upper header II 12 and the lower header II 13 are hermetically connected to the cylinder of the high-temperature evaporator housing 2 through expansion joints 22. Because the heat absorption temperature difference between the evaporator and the housing is large and the expansion amounts generated are different, if the pipe joint is directly welded to the housing, it may cause the tearing of the connection weld. The use of expansion joints can effectively avoid this problem. The fins of the high-temperature evaporator I 16 are smooth tubes, and the fins of the high-temperature evaporator II 17 are spiral fin tubes.

[0051] As Figure 2 In the shown embodiment, the steel frame 6 fixes the steam drum 3 at the upper part, and the steel frame 6 fixes the low-temperature evaporator housing 1 at the lower part. The low-temperature evaporator housing 1 mainly includes a low-temperature evaporator 14 and an economizer 15. Upper headers I 8 are respectively arranged on the upper parts of the low-temperature evaporator 14 and the economizer 15, and lower headers I 9 are respectively arranged on the lower parts of the low-temperature evaporator 14 and the economizer 15. The upper headers I 8 and the lower headers I 9 are arranged up and down along the center line of the housing; a plurality of fins II 20 are arranged between the upper header I 8 and the lower header I 9. The inlet and outlet ends of each fin II 20 are respectively communicated with the upper header I 8 and the lower header I 9. The upper header I 8 of the low-temperature evaporator is connected to the riser joint of the steam drum 3 through a riser pipe 4; the lower header 9 of the low-temperature evaporator is connected to the downcomer joint of the steam drum 3 through a downcomer pipe 5; the outlet header 8 of the economizer is connected to the water inlet of the steam drum 3 through a pipeline; the inlet header 9 of the economizer is the boiler feed water inlet.

[0052] As Figures 1 - 3As shown, in this embodiment, the high-temperature evaporator shell 2 mainly includes a high-temperature evaporator I16 and a high-temperature evaporator II17, an upper header II12 is respectively arranged on the upper part of the high-temperature evaporator I16 and the high-temperature evaporator II17, and a lower header II13 is respectively arranged on the lower part of the high-temperature evaporator I16 and the high-temperature evaporator II17, and the upper header II12 and the lower header II13 are arranged up and down along the center line of the shell; a plurality of tube segments I19 are arranged between the upper header II12 and the lower header II13, and the inlet and outlet ends of each tube segment I19 are respectively connected to the upper header II12 and the lower header II13, and the upper header I8 of the high-temperature evaporator I16 and the high-temperature evaporator II17 are respectively connected to the rising pipe joint of the drum 3 through a plurality of rising pipes 4; the lower header II13 of the high-temperature evaporator I16 and the high-temperature evaporator II17 is connected to the descending pipe joint of the drum 3 through a plurality of descending pipes 5;

[0053] like Figure 3 In the illustrated embodiment, the low-temperature evaporator housing 1 has a low-temperature evaporator 14 and an economizer 15 built therein, the high-temperature evaporator housing 2 has a high-temperature evaporator I 16 and a high-temperature evaporator II 17 built therein, and a connecting flue 7 is provided between the low-temperature evaporator housing 1 and the high-temperature evaporator housing 2; the connecting flue 7 is provided with a flue gas recirculation interface.

[0054] Specifically, Figure 4 In the embodiment shown, the water inlet and outlet ends (i.e., the upper and lower ends) of each tube segment are respectively provided with a transverse tube 23, and both sides of the transverse tube 23 are connected with corresponding headers, and the upper header and the lower header realize the concentration and dispersion of steam and water, and the upper header and the lower header are respectively connected to the boiler drum 3 through a plurality of ascending tubes 4 and descending tubes 5, and a plurality of interfaces connected to the ascending tubes 4 and descending tubes 5 are opened on the boiler drum 3. Through the improvement of this design structure, the hydraulic deviation in each tube segment can be reduced, the water circulation is better, and the evaporation efficiency is improved;

[0055] The high temperature evaporator is connected and fixed to the shell through a bracket 10, one end of the bracket can expand freely, and an expansion gap is reserved. The low temperature evaporator is connected and fixed to the shell through a bracket 11, one end of the bracket can expand freely, and an expansion gap is reserved.

[0056] In this embodiment, Figure 2 and Figure 4 As shown, the segments I19 and II20 are arranged vertically, and the upper and lower ends of both sides of the segments are closed to facilitate docking with the header.

[0057] Working principle and usage process of the utility model patent: After the utility model patent is installed, the nitrous oxide catalytic cracking tail gas sequentially passes through the high-temperature evaporator I 16 and the high-temperature evaporator II 17. Then, the flue gas is split. Part of it enters the nitrous oxide cracking device through the flue gas recirculation interface for recirculation use, and part of the flue gas sequentially passes through the low-temperature evaporator 14 and the economizer 15. When the nitrous oxide catalytic cracking tail gas enters the high-temperature evaporator I 16, it exchanges heat with the finned tube sheets I 19 inside and generates steam. When it enters the high-temperature evaporator II 17 and the low-temperature evaporator 14, it exchanges heat with the spiral finned tube sheets II 20 inside and generates steam. The steam enters the drum 3 through the riser tube 4. Subsequently, when the tail gas enters the economizer 15, it exchanges heat with the spiral finned tube sheets inside and generates high-temperature and high-pressure hot water, which enters the drum 3 through the feed water pipeline.

[0058] The utility model patent can meet the waste heat utilization requirements of flue gas pressure of 0.15 MPa, temperature of 700 °C, and steam pressure of 10 MPa, and a flue gas recirculation interface at 530 °C is set. At the same time, the high-temperature area of this boiler uses finned tubes, and the low-temperature area uses spiral finned tubes. The structure is compact and reasonable, realizing modular factory production and on-site assembly.

[0059] The flue gas pressure of a conventional waste heat boiler is negative pressure or slightly positive pressure, and the flue gas passage is generally a square flue. However, a square flue cannot withstand too high a pressure, and the flue gas is generally not more than 0.01 MPa. If a square flue is used, when the pressure is too high, the square structure is prone to deformation, resulting in instability, and an analytical design method needs to be adopted. The boiler in the present utility model uses a cylindrical shell, which improves the pressure-bearing effect and can withstand a pressure greater than 0.15 MPa during actual use;

[0060] In this embodiment, a circular shell is adopted, which belongs to a conventional design model. The shell is evenly stressed, the calculation is simple, and the shell thickness is reasonable. The corresponding thickness can be calculated according to the use temperature and pressure. The working pressure this time is 0.15 MPa, the calculated temperature is 350 °C (with internal insulation), the diameter of the large cylinder is 4000 mm, and the thickness is 20 mm. The diameter of the small shell is 2000, and the thickness is 12 mm.

[0061] The utility model adopts two high-temperature evaporators to improve the evaporation efficiency. Multiple pipe joints are arranged at the inlets and outlets of the upper and lower headers and extend outside the shell and are connected to external pipelines, which can ensure the uniform discharge of the steam-water mixture in the upper header. Similarly, multiple pipe joints in the lower header intake water, which can ensure the uniformity of the feed water, and the heat exchange tubes of the tube sheets are vertically arranged, which can ensure the smoothness of the water circulation in the entire evaporation section. The flue gas coming out of the high-temperature evaporator shell is 530 °C. Because the flue gas is recycled, a part of it is extracted, and the remaining flue gas volume becomes smaller. Correspondingly, the flue gas shell also needs to become smaller to maintain a reasonable flow rate of the flue gas.

[0062] Modular, capable of completing the installation of two casings and the evaporator inside the casings in advance, finishing the main assembly work, and only a small amount of assembly work needs to be completed on site.

[0063] The above description is an explanation of the present utility model, not a limitation thereof. For the scope defined by the present utility model, refer to the claims. Any form of modification may be made within the protection scope of the present utility model.

Claims

1. A high-pressure waste heat boiler for high-temperature and high-pressure flue gas, characterized in that: include: A high-temperature evaporator housing (2) is provided with two high-temperature evaporators in the interior thereof along the direction in which smoke enters; A low-temperature evaporator shell (1) is located in the flue gas outlet direction of the high-temperature evaporator shell (2) and divides the flue gas through the connecting flue (7), and part of the flue gas enters the low-temperature evaporator shell (1) in which a low-temperature evaporator (14) and an economizer (15) are installed; The low-temperature evaporator (14) and the high-temperature evaporator are both provided with a plurality of heat exchange tube sheets distributed side by side, the upper and lower ends of the heat exchange tube sheets are both connected to a transverse tube (23), and both sides of the transverse tube (23) are both connected to a header, and the upper and lower headers of the plurality of heat exchange tube sheets are connected and connected to the boiler drum (3) through a plurality of ascending tubes (4) / descending tubes (5).

2. A high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 1, characterized in that: It also includes a connecting flue (7), which is arranged at the outlet of the high-temperature evaporator shell (2) and connected to the low-temperature evaporator shell (1); a flue gas recirculation interface is provided on the connecting flue (7) to divert the flue gas.

3. A high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 1, characterized in that: The tube sheets in the low-temperature evaporator (14) are spiral finned tubes.

4. A high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 1, characterized in that: The high-temperature evaporator close to the smoke inlet direction in the high-temperature evaporator shell (2) adopts smooth tube sheets, and the other high-temperature evaporator adopts spiral finned tube sheets.

5. The high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 1, characterized in that: An economizer (15) is also provided in the low-temperature evaporator shell (1). The economizer (15) is provided with two inlet and outlet headers. The outlet header (8) of the economizer is connected to the water inlet of the drum (3) through a pipeline; the inlet header (9) of the economizer is the boiler feed water inlet.

6. A high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 5, characterized in that: The multiple pipe joints of the upper header of the low-temperature evaporator (14) and the two high-temperature evaporators extend out of the corresponding shells and are connected to the rising pipe joints of the boiler drum (3) through the rising pipes (4) respectively; the multiple pipe joints of the lower header of the low-temperature evaporator (14) and the two high-temperature evaporators extend out of the corresponding shells and are connected to the descending pipe joints of the boiler drum (3) through the descending pipes (5) respectively, so as to achieve communication between the two, and the pipe joints on the headers are sealed and connected to the high-temperature and low-temperature shells through expansion joints (22).

7. A high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 1, characterized in that: The low-temperature evaporator shell (1) and the high-temperature evaporator shell (2) are both cylindrical, and the diameter of the low-temperature evaporator shell (1) is smaller than the diameter of the high-temperature evaporator shell (2), and the tube sheet structure of the low-temperature evaporator shell (1) is also smaller than the tube sheet structure of the high-temperature evaporator shell (2).

8. The high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 1, characterized in that: A heat insulation layer (18) is laid inside the low-temperature evaporator shell (1) and the high-temperature evaporator shell (2).

9. The high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 1, characterized in that: On the flue gas inlet side, a flue gas baffle is arranged between the shell and the tube sheet, the heat exchange tubes of the tube sheet are arranged vertically, and the heat exchange tubes of the economizer (15) are arranged horizontally.

10. The high-pressure waste heat boiler for high-temperature and high-pressure flue gas according to claim 1, characterized in that: It also includes a steel frame (6) through which the two shells and the boiler drum (3) are fixed together to form an integral structure. The boiler drum (3) is provided with a plurality of interfaces for docking with the ascending pipe (4) / downgoing pipe (5).

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