A shell exhaust and blowdown structure suitable for a vertical tube shell waste heat boiler heat exchanger
By installing flow guide shrouds at the upper and lower ends of the vertical shell-and-tube waste heat exchanger and optimizing the outlet and inlet positions of the medium, the problem of incomplete filling of the shell side medium was solved, achieving full filling of the shell side medium and balanced temperature difference, avoiding local high temperature failure, and optimizing the equipment structure and process flow.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- THE CHALLENGE PETROCHEM MACHINERY CORP
- Filing Date
- 2022-04-12
- Publication Date
- 2026-05-29
AI Technical Summary
Existing vertical shell-and-tube waste heat exchangers cannot be fully filled with shell-side medium under high temperature difference conditions, leading to localized high-temperature failure, which is difficult to repair and has a long replacement cycle.
Upper and lower guide shrouds are installed at the upper and lower ends of the shell. The medium outlet is lower than the exhaust port and the inlet is higher than the drain port. The guide shrouds are connected to the shell-side space through flow holes. The guide shrouds are sealed and welded to the tube sheet. The positions of the exhaust port and drain port are optimized. The longitudinal section of the guide shroud is semi-circular.
It effectively avoids short circuits in the shell-side medium flow, fills the entire shell side, reduces temperature difference, avoids local high-temperature failure, improves equipment structure, optimizes process flow, enhances medium coverage, and avoids local high temperatures.
Smart Images
Figure CN114877719B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of petrochemical equipment technology, specifically to a shell-side exhaust and sewage discharge structure suitable for vertical shell-and-tube waste heat exchangers. Background Technology
[0002] Currently, shell-and-tube waste heat exchangers used in petrochemical plants receive pyrolysis gas from the pyrolysis furnace on the tube side. The tube inlet temperature reaches 800–900°C under normal operating conditions, placing the tube side in a high-temperature state. The shell side medium, water and steam, has a normal operating temperature of around 300°C and exchanges heat with the high-temperature gas on the tube side, rapidly cooling the tube side medium. Therefore, there is a very large temperature difference between the tube and shell sides of the waste heat exchanger.
[0003] Due to the large temperature difference, the tube sheet of the waste heat exchanger is generally designed with a thin tube sheet structure to absorb the large temperature difference. The medium inlet and outlet of the shell side are set as close as possible to the end of the tube sheet. At the same time, vent holes are set on the lower end face of the top tube sheet of the shell, and drain ports are set on the upper end face of the bottom tube sheet of the shell. This ensures that the medium water in the shell side fills the shell side space as much as possible, and all the high-temperature steam generated during the heat exchange process between the shell side and the tube side is discharged. This is to protect the tube sheet, heat exchange tubes and their connecting structures, and avoid structural failure caused by excessively high local temperature due to the presence of steam.
[0004] Currently, the widely used waste heat exchanger structure features a single-layer shell. Due to structural limitations, the design must ensure sufficient reinforcement space for the openings, and manufacturing requires ample welding space. Therefore, the inlet and outlet locations must be as close as possible to the tube sheet ends. Consequently, existing waste heat exchangers, due to these limitations, cannot completely fill the shell with water during operation. The unfilled areas at the top of the tube sheet are filled with high-temperature steam. The side of the tube sheet closest to the shell and the connection between the tube sheet and the heat exchange tubes cannot be adequately cooled, significantly increasing the risk of localized failure due to excessively high shell temperatures. This is a fatal weakness for large vertical heat exchangers; once a failure occurs, repair is difficult, and replacement is time-consuming. Summary of the Invention
[0005] To address the aforementioned technical problems in existing technologies, this invention provides a shell-side exhaust and blowdown structure suitable for vertical shell-and-tube waste heat exchangers.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A shell-side exhaust and blowdown structure suitable for a vertical shell-and-tube waste heat exchanger is provided, comprising a shell, an upper tube sheet, an upper tube box, a lower tube sheet, a lower tube box, and multiple heat exchange tubes. The upper and lower tube sheets are fixed to the two ends of the shell and together form a shell-side space. The upper tube box is fixed to the upper tube sheet and together forms an upper tube-side space, and the lower tube box is fixed to the lower tube sheet and together forms a lower tube-side space. The multiple heat exchange tubes are located within the shell-side space, with their upper ends passing through the upper tube sheet to connect to the upper tube-side space, and their lower ends passing through the lower tube sheet. The shell is connected to the lower tube side space; characterized in that: an upper guide shroud is provided on the outer side of the upper end of the shell, which is connected to the shell side space, and the upper guide shroud is provided with a medium outlet. The upper guide shroud extends across the upper tube sheet and covers a portion of the upper tube box. An exhaust port is provided at a position of the upper guide shroud above the bottom surface of the upper tube sheet. A lower guide shroud is provided on the outer side of the lower end of the shell, which is connected to the shell side space, and the lower guide shroud is provided with a medium inlet. The lower guide shroud extends across the lower tube sheet and covers a portion of the lower tube box. A drain port is provided at a position of the lower guide shroud below the top surface of the lower tube sheet.
[0008] Furthermore, the media outlet is located lower than the exhaust port, while the media inlet is located higher than the drain port.
[0009] Furthermore, the upper and lower ends of the shell are provided with multiple flow holes, which are distributed along the circumference of the shell. The upper and lower flow guides are connected to the shell-side space through the corresponding flow holes.
[0010] Furthermore, the flow passage can be an elongated hole, a round hole, an elliptical hole, or a polygonal hole.
[0011] Furthermore, the exhaust port is set upwards, and the sewage outlet is set downwards.
[0012] Furthermore, the upper and lower fairings are arc-shaped, with their circumference corresponding to the range of 30° to 360° of the shell.
[0013] Furthermore, there are multiple exhaust ports and multiple sewage outlets, with multiple exhaust ports arranged circumferentially along the upper guide shroud and multiple sewage outlets arranged circumferentially along the lower guide shroud.
[0014] Furthermore, the longitudinal sections of the upper and lower fairings are semi-circular.
[0015] Furthermore, the periphery of the upper guide tube is sealed and welded to fix the shell, the upper tube sheet, and the outer wall of the upper tube box.
[0016] Furthermore, the periphery of the lower guide tube is sealed and welded to fix the shell, lower tube sheet, and outer wall of the lower tube box.
[0017] The beneficial effects of this invention are:
[0018] The shell-side exhaust and blowdown structure of the present invention, applicable to vertical shell-and-tube waste heat exchangers, has the following advantages:
[0019] 1. Suitable for applications with large temperature differences between the shell and tube sides. The upper and lower ends of the shell side, close to the corresponding tube side, can discharge the high-temperature gaseous medium to the maximum extent and fill it with liquid medium, thereby minimizing the temperature difference between the shell and tube sides.
[0020] 2. It can solve the problem of short-circuiting of the medium flow at the inlet and outlet due to the limitation of the shell and tube sheet connection structure, and effectively avoid the occurrence of local high temperature failure at the connection position of the shell and tube sheet. Through the reasonable setting of the upper and lower flow guides, the shell-side medium inlet and outlet can be flexibly set, that is, the medium inlet and outlet can be placed flush with the corresponding tube sheet end, thereby achieving the effect of filling the entire shell side as much as possible under operating conditions and achieving the effect of balancing the temperature difference.
[0021] 3. The exhaust port can be set on the top outer guide tube, ensuring that the exhaust port is higher than the bottom of the top tube sheet. The sewage outlet can be set on the bottom outer guide tube, ensuring that the sewage outlet is lower than the top of the bottom tube sheet. Compared with the exhaust and sewage outlets originally located on the tube sheet, the exhaust and sewage discharge effect is better.
[0022] Furthermore, based on meeting the process principles and flow requirements, the longitudinal section of the flow guide can be set as a semi-circular structure, and the cross-section can be set as 1 / 3, 1 / 2, or full-section enclosed shell structure.
[0023] 5. The upper and lower guide fairings can adopt a shell-like structure, which is easy to process and has no manufacturing difficulty; during normal operation of the equipment, there will be no structural problems.
[0024] 6. The addition of upper and lower guide shrouds has optimized the shell-side structure of the large vertical waste heat exchanger to a certain extent, and has also effectively improved the implementation of the equipment process flow.
[0025] 7. The upper and lower guide shields allow the medium to be more fully immersed and covered by the upper and lower tube sheets, which can further avoid local high temperature. Attached Figure Description
[0026] Figure 1 This is a front view of the shell-side exhaust structure in the embodiment.
[0027] Figure 2 This is a front view of the shell-side drainage structure in the embodiment.
[0028] Figure 3 This is a top view of the shell-side exhaust and sewage discharge structure in the embodiment.
[0029] Figure 4 This is a top view of the shell-side exhaust and sewage discharge structure in another embodiment.
[0030] Figure 5 This is a top view of the shell-side exhaust and sewage discharge structure in another embodiment.
[0031] Figure label:
[0032] Shell 1, upper tube sheet 2, upper tube box 3, lower tube sheet 4, lower tube box 5;
[0033] Shell-side space 6, upper tube-side space 7, lower tube-side space 8;
[0034] Flow hole 9;
[0035] Upper flow guide shroud 10, medium outlet 11, exhaust port 12;
[0036] Lower guide shroud 13, medium inlet 14, drain outlet 15. Detailed Implementation
[0037] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.
[0038] This embodiment is applicable to the shell-side exhaust and blowdown structure of a vertical shell-and-tube waste heat exchanger, such as... Figure 1 and Figure 2 As shown, the heat exchanger includes a shell 1, an upper tube sheet 2, an upper tube box 3, a lower tube sheet 4, a lower tube box 5, and multiple heat exchange tubes (not shown in the figure). The shell 1 is a cylindrical body. The upper tube sheet 2 and the lower tube sheet 4 are fixed to the two ends of the shell 1 respectively, forming a shell-side space 6. The upper tube box 3 is fixed to the upper tube sheet 2, forming an upper tube-side space 7. The lower tube box 5 is fixed to the lower tube sheet 4, forming a lower tube-side space 8. Multiple heat exchange tubes are located within the shell-side space 6, with their upper ends passing through the upper tube sheet 2 to connect to the upper tube-side space 7, and their lower ends passing through the lower tube sheet 4 to connect to the lower tube-side space 8. The above is the existing waste heat boiler heat exchanger structure. An improvement is proposed:
[0039] The upper end of the shell 1, as close as possible to the upper tube sheet 2, and the lower end of the shell 1, as close as possible to the lower tube sheet 4, are respectively provided with flow holes 9. An upper guide shroud 10 is attached to the outer side of the upper end of the shell 1. The upper guide shroud 10 is connected to the shell-side space 6 through the corresponding flow holes 9. The upper guide shroud 10 is provided with a medium outlet 11. The upper guide shroud 10 extends across the upper tube sheet 2 and covers a portion of the upper tube box 3. An upward-facing exhaust port 12 is provided at a position of the upper guide shroud 10 above the bottom surface of the upper tube sheet 2. The position of the medium outlet 11 is lower than the position of the exhaust port 12. The periphery of the upper guide shroud is sealed and welded to fix the outer walls of the shell 1, the upper tube sheet 2, and the upper tube box 3.
[0040] A lower guide shroud 13 is provided on the outer side of the lower end of the shell 1. The lower guide shroud 13 is connected to the shell-side space 6 through a corresponding flow hole 9. The lower guide shroud 13 is provided with a medium inlet 14. The lower guide shroud 13 extends across the lower tube sheet 4 and covers a portion of the lower tube box 5. A downward-facing drain port 15 is provided at a position of the lower guide shroud 13 below the top surface of the lower tube sheet 4. The position of the medium inlet 14 is higher than the position of the drain port 15. The periphery of the lower guide shroud is sealed and welded to fix the outer walls of the shell 1, the lower tube sheet 4, and the lower tube box 5. The longitudinal section of the upper guide shroud 10 and the lower guide shroud 13 is semi-circular, but can be changed to other shapes as needed.
[0041] In this embodiment, the flow hole 9 is an elongated hole, but in practice it can be changed to a round hole, an elliptical hole or a polygonal hole.
[0042] In this embodiment, the upper guide shield 10 and the lower guide shield 13 are arc-shaped, resembling the letter C laterally, and their circumferential direction corresponds to a range of 30° to 360° of the housing 1. There are multiple exhaust ports 12 and drain ports 15. Multiple exhaust ports 12 are arranged circumferentially along the upper guide shield 10, and multiple drain ports 15 are arranged circumferentially along the lower guide shield 13. Multiple flow holes 9 are distributed circumferentially along the housing 1. Figure 3 The exhaust ports 12 (drain ports 15) shown are distributed circumferentially around 1 / 3 of the area of the housing 1, or as... Figure 4 The exhaust ports 12 (drain ports 15) shown are distributed circumferentially around half the area of the housing 1, or as... Figure 5 The upper guide shroud 10 (lower guide shroud 13) shown is a complete ring, covering the entire ring of the shell 1, and multiple exhaust ports 12 (drain ports 15) are distributed around the shell 1 in a 360° range.
[0043] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0044] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.
[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A shell-side exhaust and blowdown structure suitable for a vertical shell-and-tube waste heat exchanger, comprising a shell, an upper tube sheet, an upper tube box, a lower tube sheet, a lower tube box, and multiple heat exchange tubes. The upper and lower tube sheets are respectively fixed to both ends of the shell and together form a shell-side space. The upper tube box is fixed to the upper tube sheet and together forms an upper tube-side space. The lower tube box is fixed to the lower tube sheet and together forms a lower tube-side space. The multiple heat exchange tubes are located within the shell-side space, with their upper ends passing through the upper tube sheet and connecting to the upper tube-side space, and their lower ends passing through the lower tube sheet and connecting to the lower tube-side space. An upper guide shroud connecting to the shell-side space is provided on the outer side of the upper end of the shell. The upper guide shroud has a medium outlet and extends across the upper tube sheet, covering a portion of the upper tube box. A lower guide shroud connecting to the shell-side space is provided on the outer side of the lower end of the shell. The lower guide shroud has a medium inlet and extends across the lower tube sheet, covering a portion of the lower tube box. The structure is characterized by: The upper and lower ends of the shell are provided with multiple flow holes, which are distributed along the circumference of the shell. The upper and lower flow guides are connected to the shell-side space through the corresponding flow holes. An exhaust port is provided at a position above the bottom surface of the upper tube sheet in the upper guide shroud; so that the upper end of the shell side near the corresponding tube side can discharge the high-temperature gaseous medium and be filled with the liquid medium; a drain port is provided at a position below the top surface of the lower tube sheet in the lower guide shroud. The media outlet is located lower than the exhaust port, and the media inlet is located higher than the drain port.
2. The shell-side exhaust and blowdown structure for a vertical shell-and-tube waste heat exchanger according to claim 1, characterized in that: The flow passage can be a long, narrow, round, elliptical, or polygonal hole.
3. The shell-side exhaust and blowdown structure for a vertical shell-and-tube waste heat exchanger according to claim 1, characterized in that: The exhaust port is set facing upwards, and the sewage outlet is set facing downwards.
4. The shell-side exhaust and blowdown structure for a vertical shell-and-tube waste heat exchanger according to claim 1, characterized in that: The upper and lower fairings are arc-shaped, with their circumference corresponding to the range of 30° to 360° of the shell.
5. The shell-side exhaust and blowdown structure for a vertical shell-and-tube waste heat exchanger according to claim 4, characterized in that: There are multiple exhaust ports and sewage outlets. The multiple exhaust ports are arranged circumferentially along the upper guide shroud, and the multiple sewage outlets are arranged circumferentially along the lower guide shroud.
6. The shell-side exhaust and blowdown structure for a vertical shell-and-tube waste heat exchanger according to claim 1, characterized in that: The longitudinal sections of the upper and lower fairings are semi-circular.
7. The shell-side exhaust and blowdown structure for a vertical shell-and-tube waste heat exchanger according to claim 1, characterized in that: The periphery of the upper guide tube is sealed and welded to fix the shell, the upper tube sheet, and the outer wall of the upper tube box.
8. The shell-side exhaust and blowdown structure for a vertical shell-and-tube waste heat exchanger according to claim 1, characterized in that: The periphery of the lower guide tube is sealed and welded to fix the shell, lower tube sheet, and outer wall of the lower tube box.