Tube bundle heat exchanger

Description: TECHNICAL FIELD [Detailed description of the invention]

[Industrial application field] The present invention relates to a tube bundle heat exchanger having the features described in the preamble of claim 1. [Conventional technology] This type of tube-bundle heat exchanger is a process used to quickly cool the reaction gas that flows out of a reactor in a cracker or chemical plant when generating high-pressure steam, which is used as a medium to release heat. -Used as a gas-based exhaust heat boiler. In order to control the high gas temperature and the large pressure difference between the gas and the cooling medium that releases heat, the tube plate arranged on the gas inlet side is a tube provided on the gas outlet side. It is designed to be thinner than the board (see DE-C-1294981 and AT-B-361953). The thin tube plate is spaced apart from the tube plate and is reinforced by a support plate connected to the tube plate by the use of anchors. In other known tube bundle heat exchangers (see DE-C-3533219), they are supported by a support plate via support fingers welded to a thin tube plate. The cooling medium is designed to flow through the space between the support plate and the tube plate. The cooling medium is supplied through a ring-shaped chamber and flows into the heat exchanger through a ring-shaped gap between the tube and the support plate. In this way, the cooling medium is introduced sideways with respect to the thin tube plate. By introducing water as a cooling medium in this way, the tube plate can be effectively cooled, and a large flow velocity is created so that the particles contained in the cooling medium are deposited on the tube plate. Can be prevented. Due to the double bottom, the heat exchanger works well, but the cost of making the heat exchanger is relatively high. It is already known to provide a cooling passage in a thick tube plate arranged on the gas outlet side of the tube bundle type heat exchanger of the type originally mentioned (see AT-B-361953). According to this configuration, it is possible to allow gas having a high temperature of 550 to 650 ° C to flow out while maintaining a sufficiently high strength of the tube plate. In the case of this known pipe plate, the cooling passages are arranged so as to be relatively large apart from each other and relatively large apart from the side of the pipe plate that comes into contact with the gas. The cooling action of the tube plate generated by arranging the cooling passages in this way is sufficiently satisfactory, and the gas temperature on the gas outlet side of the heat exchanger can be appropriately controlled. [Problems to be solved by the invention] An object of the present invention is that the cooling medium can be uniformly distributed even when the thickness of the wall on the gas inlet side of the heat exchanger is reduced and the flow velocity of the cooling medium is set high, and the pipe to be cooled is provided. It is to improve the structure of the tube plate of the type of tube bundle heat exchanger originally mentioned so that the production of the plate can be facilitated and the stress distribution inside the tube plate can be made uniform. [Means to solve problems] In order to solve the above problems, a tube bundle heat exchanger of the type originally mentioned having the configuration described in the feature of claim 1 of the claims is provided according to the present invention. See claims 2-9 for advantageous embodiments of the present invention. [Action and effect] According to the present invention, the tube plate on the gas inlet side of the heat exchanger can be designed to be sufficiently thick as a whole, so that the requirement for durability of the cooling medium against high pressure can be satisfied. Since the pipes penetrate the cooling passages extending parallel to each other up and down and extend straight along the pipe row, the distance between the cooling passages adjacent to each other can be set narrowly, so that the cooling medium can be set narrowly. It is possible to widen the overall cross-sectional area of the cooling passage through which the water flows. Since the thickness of the wall body at the bottom of the cooling passage is uniform, it is possible to prevent impurity particles from accumulating inside the cooling passage. Therefore, since the tube plate can be effectively cooled, even a high gas temperature exceeding 1000 ° C can be appropriately controlled. Further, since the flow velocity of the cooling medium flowing through the cooling passage can be adjusted to a value such that the particles contained in the cooling medium do not settle, the risk of overheating of the tube plate can be prevented. Then, the plate portion on the gas inlet side of the pipe plate can be made thinner, and the plate portion on the side facing the jacket hangs down from the thick plate portion of the pipe plate and extends between the cooling passages. It is possible to support the abdominal plate. Such a support method is clearly advantageous because the stress can be uniformly dispersed as compared with the conventional support method using individual anchors (fixing members). Then, by making the plate portion on the gas inlet side of the pipe plate thin, it is possible to perform cooling in a state where the thermal stress is small, and each pipe is welded to the pipe plate portion without a gap. be able to. [Example] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings illustrating examples of the present invention. The heat exchangers shown are those used to cool the cracked gas, especially with boiling water under high pressure, which is partially evaporating. The heat exchanger is composed of a bundle of pipes 1 composed of a plurality of pipes 1 surrounded by a jacket 2 while the gas to be cooled flows through the heat exchanger. For the sake of simplification of the illustration, only one pipe 1 of the pipe rows arranged in one row is shown. Each pipe 1 is held between two pipe plates 3 and 4, and the gas inlet 5 and the gas outlet 6 are connected to the pipe plates 3 and 4, and the pipe plates 3 and 4 are connected to the jacket 2. It is welded. The pipe plate 3 arranged on the gas inlet side includes a cooling passage 7 extending in parallel with each other. The cooling passage 7 is located in the pipe plate 3 so that the distance to the gas side of the pipe plate of the cooling passage 7 is smaller than the distance to the inside of the jacket 2 of the cooling passage 7 when viewed in the axial direction of the pipe plate 3. It is formed. Therefore, the wall thickness of the plate portion 8 of the pipe plate facing the gas inlet side is thin, while the wall thickness of the plate portion 9 of the pipe plate facing the jacket 2 side is thick. .. According to the embodiment illustrated in FIGS. 1 to 6, both sides of the cooling passage 7 are open and open to the chamber 10 surrounding the pipe plate 3 in a ring shape. One or more supply joints 11 for supplying the cooling medium under high pressure are provided on the inlet side of the chamber 10. The cooling passage 7 is formed as a cylindrical hole formed through the pipe plate 3 parallel to the surface of the pipe plate 3. The portion where the cross section continuous with the cooling passage 7 has a substantially circular shape is expanded to a tunnel-shaped profile by cutting. The shape of this tunnel-shaped cross section is shown in the drawing and features an arched ceiling and a flat bottom 12 extending parallel to the upper side of the tube plate 3. A thin bottom with a uniform wall thickness can be easily formed according to the method described above. The side wall 13 of the tunnel-shaped cooling passage 7 is also flat and extends vertically with respect to the bottom 12. The side wall 13 constitutes an abdominal plate 14 that hangs down from the thick plate portion 9 of the tube plate and has a thin wall thickness, and the thin plate portion 8 of the tube plate is between the cooling passages 7. It is supported by the abdominal plate 14 extending to the abdomen. The tube plate 3 has a through hole 15 in the thicker bottom 9, which opens toward the inside of the jacket 2 and in the cooling passage 7 at right angles to the extension in the longitudinal direction. It is open. The pipe 1 of the pipe bundle is formed through the through hole 15 while forming a ring-shaped gap having play. The pipes 1 arranged in a row are penetrated through the cooling passage 7 and welded to the thinner bottom 8 of the pipe plate 3 without play through a fully welded weld seam 16. Has been done. The width of the cooling passage 7 thus formed corresponds to a value from 1 to 2 times the diameter of the pipe 1. The cooling medium supplied to the inlet side of the chamber 10 through the supply joint 11 reaches the cooling passage 7 and is surrounded by the jacket 2 through the ring-shaped gap between the pipe 1 and the through hole 15. It flows into the inside of the exchanger. A part of the cooling medium rises in the jacket 2 along the outside of the pipe 1 and becomes high-pressure steam, which flows out from the outlet joint 17 welded to the jacket 2. The cooling medium that flows into the internal space of the heat exchanger without passing through the ring-shaped gap flows out from the cooling passage 7 on the opposite side of the cooling passage 7 and reaches the outlet side of the chamber 10. This outlet side is separated from the inlet side by two partition walls 22. The partition walls 22 are arranged in the chamber 10 at right angles to the longitudinal axis of the cooling passage 7 and extend over the entire cross section of the chamber 10. With this configuration, one end of the cooling passage 7 is connected to the inlet side of the chamber 10, and the other end of the cooling passage 7 is connected to the outlet side of the chamber 10. .. A bend 23 that opens into the internal space of the heat exchanger is connected to the outlet side of the chamber 10. Therefore, the remaining cooling medium flows into the heat exchanger through the bend 23 and is converted into high pressure steam. Since the cooling medium is distributed and introduced in this way, it is possible to secure a sufficiently high speed of the cooling medium even on the outlet side of the cooling passage 7, and thus the cooling medium is included in the cooling medium. There is no risk of solid particles accumulating on the bottom 12 of the cooling passage 7. The solid particles contained in the cooling medium are discharged through the cooling passage 7. The flow resistance of the shorter cooling passage 7 is configured to be equal to the flow resistance of the longer cooling passage 7 on the center side so that the cooling medium can flow uniformly through all the cooling passages 7. .. Since it is configured in this way, the cross-sectional area of the cooling passage 7 becomes smaller as it goes to the outside, or the cooling passage 7 provided on the outside is provided with a throttle portion. The inlet chamber 18 of the cooling medium, which extends over half the perimeter of the heat exchanger, is shown in FIGS. 7 and 8. The wall of the inlet chamber 18 is connected to the inner wall of the jacket 2 and is connected to the tube plate 3 in the edge region. According to this embodiment, both ends of the cooling passage 7 are closed by the cover 20. Holes 19 and 24 are provided at both ends of the cooling passage 7, and the holes 19 and 24 are axially penetrated through the thick bottom 19 of the pipe plate 3. The hole 19 extends from the inlet chamber 18 and serves to supply the cooling medium through the cooling passage 7. The other hole 24 opens into the internal space of the heat exchanger and allows the remaining amount of cooling medium that does not flow out through the ring-shaped space between the tube 1 and the through hole 15 to be discharged. As shown in FIG. 9, the cooling passage 7 is formed by cutting in the pipe plate 3 as dents extending in parallel with each other. An vaulted or flat ceiling is formed in the cooling aisle 7. The dent is covered by a strip-shaped piece 21 welded to the abdominal plate 14 extending between the cooling passages 7. The tube 1 is welded to the strip-shaped piece 21. Unlike the examples shown in FIGS. 1 to 6, in the example shown in FIG. 9, the number of weld seams is increased, the stress is increased, and the mechanical strength is decreased. However, it is relatively easy to manufacture.

[Simple explanation of drawings]

FIG. 1 is a cross-sectional view of a heat exchanger configured according to an embodiment of the present invention cut in the length direction, and FIG. 2 is a plan view of a tube plate provided on the gas inlet side as viewed from above. The figure is a cross-sectional view cut along the line III-III of Fig. 2, the figure 4 is a cross-sectional view cut along the line IV-IV of Fig. 2, and Fig. 5 is the details of the Z section of Fig. 3. A cross-sectional view, FIG. 6 is a plan view of the section shown in FIG. 5 viewed from above, and FIG. 7 is a tube plate provided on the gas inlet side configured according to another embodiment of the present invention. View from the top, FIG. 8 is a cross-sectional view cut along line VIII-VIII of FIG. 7, FIG. 9 is the heat exchanger shown in FIG. 3 configured according to another embodiment. Detailed sectional view of Z section. 1 ... tube, 2 ... jacket, 3, 4 ... tube plate, 4 ... cooling passage, 5 ...... gas inlet, 6 ...... gas outlet, 7 ...... Cooling passage, 8 ...... Thinner bottom, 9 ...... thicker bottom, 10 ...... chamber, 11 ...... Supply fitting, 12 ...... Flat bottom, 13 ...... Cooling passage side wall, 14 ...... Sternum, 15 ...... Enlarged diameter part, 16 ...... Welded seam, 17 ...... outlet fitting, 18 ...... inlet chamber, 19, 24 ... holes, 20 ... covers, 21 ...... strip-shaped piece of board, 22 ...... partition wall, 23 ...... Bend.