L-shaped wall pipe water bed reactor and methanation process

Abstract

The reactor comprises an inner cylinder and an outer cylinder, the inner cylinder is sleeved with the outer cylinder, an annular space is formed between the inner cylinder and the outer cylinder, and an upper tube plate, a lower tube plate and a catalyst supporting plate are arranged in a cavity defined by the inner cylinder and a lower end socket of the outer cylinder; a reaction area is formed among the upper tube plate, the inner cylinder, the lower tube plate and the catalyst supporting plate, and the reaction area is filled with a catalyst; and a plurality of L-shaped heat exchange tubes are arranged between the upper tube plate and the lower tube plate. According to the reactor and the heat exchange tube, thermal stress can be automatically compensated, the problem of methane leakage caused by weld joint cracking is structurally eradicated, the specific heat exchange area is large, heat can be removed in time, temperature balance of a reaction area is achieved, the temperature runaway phenomenon is avoided, and heat energy generated by reaction is recycled to the maximum extent; when the reactor is used for methanation reaction, the reaction efficiency is high.

Description

Technical Field

[0001] The present invention relates to the technical field of methanation, and in particular to an L-shaped wall tube water bed reactor and a methanation process. Background Art

[0002] The heat exchange tubes of the existing methane water bed reactor are generally straight tubes, and the two ends of the heat exchange tubes are vertically connected to the upper and lower flat tube plates, and the outer periphery of the heat exchange tube between the upper and lower flat tube plates is filled with catalyst. The existing methane water bed reactor structure has the following defects:

[0003] 1. The thermal expansion stress of the heat exchange tube cannot be eliminated, and the weld between the heat exchange tube and the flat tube plate is prone to cracking due to expansion, causing methane leakage.

[0004] 2. The specific cooling area is small, the reaction efficiency is low, the reaction heat cannot be removed in time, the temperature in the reaction area is uneven, and the temperature runaway phenomenon is easy to occur.

[0005] 3. The catalyst loading volume is small and it is inconvenient to load and unload the catalyst. Summary of the invention

[0006] In order to solve the above problems, the present invention provides an L-shaped wall tube water bed reactor and a methanation process.

[0007] The technical solution adopted by the present invention is:

[0008] An L-shaped wall tube water bed reactor comprises an inner tube and an outer tube, wherein the inner tube is provided with an upper end cap, and the outer tube is provided with an upper end cap and a lower end cap, the inner tube is sleeved in the outer tube, the lower end of the inner tube is connected to the side wall of the outer tube, an annular gap is formed between the inner tube wall and the outer tube wall, an upper tube sheet, a lower tube sheet and a catalyst support plate are arranged in a cavity surrounded by the inner tube and the lower end cap of the outer tube, the lower tube sheet is arranged on the catalyst support plate, and a hot water cavity is formed between the lower tube sheet and the catalyst support plate, the catalyst support plate is arranged in the lower end cap of the outer tube, and the upper tube sheet and the catalyst support plate are connected to each other. A steam-water mixing chamber is formed between the upper heads of the inner tube, a reaction zone is formed between the upper tube plate, the inner tube, the lower tube plate and the catalyst support plate, and an air outlet chamber is formed between the catalyst support plate and the lower head of the outer tube, and the reaction zone is filled with catalyst; a plurality of L-shaped heat exchange tubes are installed between the upper tube plate and the lower tube plate, and the hot water chamber is connected with the steam-water mixing chamber through the L-shaped heat exchange tubes, a first through hole connecting the reaction zone and the annular gap is provided on the upper side of the inner tube wall, and a second through hole connecting the reaction zone and the air outlet chamber is provided on the catalyst support plate.

[0009] A reaction gas outlet pipe connected to the outlet cavity and a water inlet pipe connected to the hot water cavity are arranged at the bottom of the outer cylinder, a raw gas inlet pipe connected to the annular gap is arranged at the lower end of the outer cylinder, and a water steam outlet pipe connected to the steam-water mixing cavity is arranged at the top of the inner cylinder.

[0010] Furthermore, the upper tube plate is a flat tube plate, the lower tube plate is composed of a cylindrical side plate and an arc-shaped top plate, the upper end of the L-shaped heat exchange tube vertically passes through the upper tube plate to be connected with the steam-water mixing chamber, and the lower end of the L-shaped heat exchange tube is bent into an L shape toward the center of the reactor and then passes through the lower tube plate to be connected with the hot water chamber.

[0011] Furthermore, the L-shaped heat exchange tube is formed by integrally bending a seamless steel tube.

[0012] Furthermore, a central tube with closed ends is axially arranged in the center of the reaction zone, the lower end of the central tube is connected to the lower tube plate, and a catalyst flow channel is arranged between the upper end and the upper tube plate.

[0013] Furthermore, a catalyst unloading pipe connected to the reaction zone is provided at the bottom of the outer tube, and a catalyst feeding pipe connected to the reaction zone is provided at the top center of the inner tube, and the catalyst feeding pipe passes through the outer tube to form an opening.

[0014] Furthermore, the catalyst support plate is an arc-shaped plate with a middle portion protruding upward.

[0015] A methanation process, using the above-mentioned L-shaped wall tube water bed reactor, comprises the following steps:

[0016] (1) The raw gas enters the reactor from the raw gas inlet pipe, flows upward along the annular gap to the upper end of the inner cylinder, and then enters the reaction zone through the first through hole.

[0017] (2) Boiler water enters the hot water chamber from the water inlet pipe, is evenly distributed through the lower tube plate, and then enters the heat exchange tube, flowing upward along the heat exchange tube;

[0018] (3) The raw gas passes through the catalyst bed from top to bottom in the reaction zone and reacts to generate methane under the action of the catalyst. The methane gas and the unreacted raw gas enter the gas outlet chamber through the second through hole and are discharged from the reactor through the reaction gas outlet pipe. The heat generated during the reaction is taken away by the heat exchange tube. The boiler water in the heat exchange tube is partially vaporized into water vapor after the temperature rises. The steam-water mixture enters the steam-water mixing chamber and is discharged from the reactor through the water steam outlet pipe.

[0019] Preferably, the temperature of the raw gas entering the reactor is 220-230°C, and the temperature of the raw gas exiting the reactor is 250°C±5°C.

[0020] Preferably, in step (3), the hot spot temperature of the catalyst at the initial stage of the reaction is 255±5°C.

[0021] Preferably, the temperature of the boiler water is 150°C±5°C, and the pressure of the water vapor discharged from the reactor is 3.5±5 MPa.

[0022] Beneficial effects of the present invention:

[0023] 1) L-shaped heat exchange tubes are used as heat exchange components. After three-dimensional bending, the L-shaped heat exchange tubes are connected to the upper and lower tube sheets, which can minimize the impact of thermal stress on the heat exchange tubes and enhance welding reliability. In addition, the thermal stress of each tube can be automatically compensated during operation, which prevents methane leakage caused by weld cracking from a structural perspective and ensures equipment safety.

[0024] 2) Densely arranged L-shaped heat exchange tubes are used as heat exchange components. The inside of the tube is circulating hot water, and the outside of the tube is methanation catalyst. The heat exchange area is large and the heat transfer capacity is strong. Heat can be removed in time to achieve temperature balance in the reaction area and avoid the occurrence of temperature runaway.

[0025] 3) The lower tube sheet is arranged at the center of the inner tube. Compared with the reactors of the same height, the reaction zone has a larger volume, a larger catalyst loading amount, a higher reaction efficiency, and saves equipment investment and floor space.

[0026] 4) The installation of internal parts and the loading and unloading of catalysts are more convenient, and maintenance is more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of the L-shaped wall tube water bed reactor of the present invention.

[0028] Figure 2 It is a structural diagram of the lower tube plate of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and a preferred implementation manner.

[0030] Example 1

[0031] See also Figure 1 and Figure 2 , an L-shaped wall tube water bed reactor, comprising a vertically arranged inner tube 1 and a vertically arranged outer tube 2.

[0032] The inner tube 1 is provided with an upper head, the upper end of the inner tube 1 is closed by the inner tube upper head, and the lower end of the inner tube 1 is open; preferably, the inner tube upper head is an elliptical head, which is easy to manufacture.

[0033] The outer tube 2 is provided with an upper head and a lower head, and the upper and lower ends of the outer tube 2 are sealed by the upper head and the lower head of the outer tube. Preferably, the upper head and the lower head of the outer tube are spherical heads to improve the pressure resistance.

[0034] The inner cylinder 1 is axially sleeved in the outer cylinder 2, the lower end of the inner cylinder extends to the upper part of the lower end cap of the outer cylinder, and is fixedly connected to the inner wall of the outer cylinder through the annular support plate 17, the upper end of the inner cylinder extends to the lower part of the upper end cap of the outer cylinder, and is slidably connected to the inner wall of the outer cylinder, and an annular gap 101 is provided between the inner cylinder wall and the outer cylinder wall above the annular support plate 17. An expansion chamber 108 is provided between the top of the inner cylinder and the upper end cap of the outer cylinder to absorb the displacement of the inner cylinder.

[0035] An upper tube sheet 3, a lower tube sheet 4 and a catalyst support plate 5 are arranged in the cavity surrounded by the inner tube and the lower end head of the outer tube. The catalyst support plate 5 is arranged in the lower end head of the outer tube. A steam-water mixing chamber 103 is formed between the upper tube sheet 3 and the upper end head of the inner tube. A reaction zone 104 is formed between the upper tube sheet 3, the inner tube 1, the lower tube sheet 4 and the catalyst support plate 5. An air outlet chamber 105 is formed between the catalyst support plate 5 and the lower end head of the outer tube. The reaction zone is filled with a catalyst. A plurality of L-shaped heat exchange tubes 6 are installed between the upper tube sheet 3 and the lower tube sheet 4. The hot water chamber 102 is connected to the steam-water mixing chamber 103 via the L-shaped heat exchange tubes 6. A first through hole 106 connecting the reaction zone 104 and the annular gap 101 is arranged on the upper side of the inner tube wall. A second through hole 107 connecting the reaction zone 104 and the air outlet chamber 105 is arranged on the catalyst support plate 5.

[0036] The lower end of the outer cylinder 2 is symmetrically provided with two raw gas inlet pipes 9 connected to the annular gap 101 and a first manhole 16 connected to the reaction zone 104. The components in the reaction zone can be inspected and repaired through the first manhole 16. The two symmetrically arranged raw gas inlet pipes 9 are conducive to the uniform distribution of the raw gas in the annular gap 101.

[0037] The bottom of the outer tube 2 is provided with a reaction gas outlet pipe 7 connected to the outlet cavity 105, a water inlet pipe 8 connected to the hot water cavity 102, and a catalyst unloading pipe 12 of the reaction zone 104. The water inlet pipe 8 is located at the center of the bottom of the outer tube 2, and its upper end vertically passes through the outlet cavity 105 and is connected to the hot water cavity 102. The reaction gas outlet pipe 7 and the catalyst unloading pipe 12 are respectively located on both sides of the water inlet pipe 8. The reaction gas outlet pipe 7 is directly connected to the outlet cavity 105, and the upper end of the catalyst unloading pipe 12 passes through the outlet cavity 105 and the catalyst support plate 5 and is connected to the reaction zone, which is conducive to catalyst unloading. Two reaction gas outlet pipes 7 can be provided to increase the outlet speed.

[0038] A second manhole 15 communicating with the expansion chamber 108 is provided at the top of the outer cylinder, through which surface defects of the upper end cap of the inner cylinder can be inspected and repaired.

[0039] The top of the inner tube 1 is provided with a catalyst feed pipe 11 and a temperature measuring tube 14 connected to the reaction zone 104, and a water vapor outlet pipe 10 connected to the steam-water mixing chamber 103. The catalyst feed pipe 11 is located in the center of the inner tube, and its lower end vertically passes through the upper tube plate 3 downward to communicate with the reaction zone 104, and the upper end vertically passes through the expansion chamber 108 and the upper end of the outer tube to form a catalyst feed port. In this embodiment, there are two water vapor outlet pipes 10, which are symmetrically arranged on both sides of the catalyst feed pipe 11, and two corrugated sleeves are provided on the top of the outer tube 2. The upper ends of the two water vapor outlet pipes 10 respectively vertically pass through the expansion chamber 108 and the two corrugated sleeves upward to form a water vapor outlet, and one end of the water vapor outlet pipe extending out of the corrugated sleeve is fixedly connected to the corrugated sleeve through a flange. The setting of the corrugated sleeve can protect the water vapor outlet pipe 10, and can leave redundancy for the thermal expansion of the water vapor outlet pipe. In other embodiments, the water vapor outlet pipe 10 can also be set to three or four. The upper end of the temperature measuring tube 14 vertically passes through the expansion chamber 108 and the upper end cap of the outer cylinder to form a temperature measuring port.

[0040] The upper tube sheet 3 is a flat tube sheet, arranged below the upper end cap of the inner tube, and fixedly connected to the inner tube wall. A catalyst feed pipe through hole and a number of heat exchange tube through holes A uniformly distributed around the catalyst feed pipe through hole are provided in the center of the upper tube sheet. The catalyst support plate 5 is an upwardly protruding arc plate, with no opening in the middle, and second through holes 107 uniformly distributed on the outer edge. The catalyst support plate 5 is fixedly connected to the lower end cap of the outer tube. The lower tube sheet 4 is composed of a cylinder 41 and a hemispherical arc plate 42. The hemispherical arc plate 42 is closed and connected to the upper end of the cylinder 41. The lower end of the cylinder 41 is fixedly supported in the middle of the catalyst support plate 5 and is closed by the catalyst support plate 5, that is, a hot water cavity 102 is formed between the lower tube sheet 4 and the catalyst support plate 5. Heat exchange tube through holes B are uniformly distributed on the cylinder 41 and the hemispherical arc plate 42.

[0041] The L-shaped heat exchange tube 6 is formed by bending a seamless steel tube as a whole, and is annularly surrounding the catalyst feed tube 11. Its upper end vertically passes through the heat exchange tube through hole A of the upper tube plate 3 to communicate with the steam-water mixing chamber 103, and its lower end vertically extends downward to the bottom of the reaction zone and then bends into an L shape toward the center of the reactor, and then passes through the heat exchange tube through hole B to communicate with the hot water chamber 102. The two ends of the L-shaped heat exchange tube 6 are welded to the upper tube plate 3 and the lower tube plate 4 respectively.

[0042] The L-shaped heat exchange tube 6 is made of high-strength seamless steel tube arranged vertically, which can reduce the resistance of the water channel and eliminate dead zones, so as to minimize the resistance of the water channel and facilitate the natural circulation of the hot water / steam mixture; and can make full use of the density change of water in the tube bundle and the natural circulation of the stroke position difference, without the need for forced water circulation by power, and the circulation rate of water can also be naturally adjusted according to the intensity of the reaction heat, thereby improving the uniformity of the catalyst bed temperature.

[0043] A central tube 13 with closed ends is axially arranged in the center of the reaction zone 104. The lower end of the central tube 13 is connected to the lower tube sheet 4, and a catalyst flow channel is arranged between the upper end and the upper tube sheet 3. The arrangement of the central tube 13 can prevent the catalyst from accumulating in the center of the reaction zone. Heat exchange tubes cannot be arranged in the center of the reaction zone, and the accumulated catalyst will cause the reaction heat to be unable to be removed in time, resulting in uneven temperature in the reaction zone.

[0044] Example 2

[0045] The reactor of Example 1 was used to carry out the methanation reaction, and the process steps were:

[0046] (1) The raw gas at a temperature of enters the reactor from the two raw gas inlet pipes 9, flows upward along the annular gap 101 to the upper end of the inner cylinder, and then enters the reaction zone 104 through the first through hole 106.

[0047] (2) Boiler water at a temperature of enters the hot water chamber 102 from the water inlet pipe 8, enters the heat exchange tube 6 after being evenly distributed through the lower tube plate 4, and flows upward along the heat exchange tube 6;

[0048] (3) The raw gas passes through the catalyst bed from top to bottom in the reaction zone and reacts to generate methane under the action of the catalyst. The methane gas and the unreacted raw gas enter the gas outlet chamber 105 through the second through hole 107 and are discharged from the reactor through the reaction gas outlet pipe 7. The heat generated during the reaction is taken away by the heat exchange tube 6. The boiler water in the heat exchange tube 6 is partially vaporized into water vapor after the temperature rises. The steam-water mixture enters the steam-water mixing chamber 103 and is discharged from the reactor through the water vapor outlet pipe 10.

[0049] During the reaction, the temperature of the raw gas entering the reactor is controlled at 220-230°C, and the temperature of the raw gas exiting the reactor is 250°C±5°C; the hot spot temperature of the catalyst at the initial stage of the reaction is 255±5°C; the temperature of the boiler water is 150°C±5°C, and the pressure of the water vapor exiting the reactor is 3.5±5MPa.

[0050] By controlling the above process parameters, the heat energy loss of the system can be reduced, the heat energy generated by the reaction can be recovered to the maximum extent, and the reaction efficiency can be further improved.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications are also within the protection scope of the present invention.

Claims

1. An L-shaped wall tube water bed reactor, comprising an inner tube (1) and an outer tube (2), characterized in that: The inner tube (1) is provided with an upper end cap, and the outer tube (2) is provided with an upper end cap and a lower end cap. The inner tube is sleeved inside the outer tube, and the lower end of the inner tube is connected to the side wall of the outer tube. An annular gap (101) is formed between the inner tube wall and the outer tube wall. An upper tube plate (3), a lower tube plate (4) and a catalyst support plate (5) are provided in a cavity surrounded by the inner tube and the lower end cap of the outer tube. The lower tube plate (4) is arranged on the catalyst support plate (5) and a hot water cavity (102) is formed between the lower tube plate (4) and the catalyst support plate (5). The catalyst support plate (5) is arranged in the lower end cap of the outer tube. A steam-water mixing cavity (103) is formed between the upper tube plate (3) and the upper end cap of the inner tube. The upper tube plate (3), the inner tube (1), A reaction zone (104) is formed between the lower tube plate (4) and the catalyst support plate (5), and an air outlet cavity (105) is formed between the catalyst support plate (5) and the lower end cap of the outer tube. The reaction zone is filled with a catalyst. A plurality of L-shaped heat exchange tubes (6) are installed between the upper tube plate (3) and the lower tube plate (4). The hot water cavity (102) and the steam-water mixing cavity (103) are connected via the L-shaped heat exchange tubes (6). A first through hole (106) connecting the reaction zone (104) and the annular gap (101) is provided on the upper side of the inner tube wall. A second through hole (107) connecting the reaction zone (104) and the air outlet cavity (105) is provided on the catalyst support plate (5). A reaction gas outlet pipe (7) connected to the gas outlet chamber (105) and a water inlet pipe (8) connected to the hot water chamber (102) are provided at the bottom of the outer tube (2); a raw gas inlet pipe (9) connected to the annular gap (101) is provided at the lower end of the outer tube (2); and a water steam outlet pipe (10) connected to the steam-water mixing chamber (103) is provided at the top of the inner tube (1).

2. An L-shaped wall tube water bed reactor according to claim 1, characterized in that: The upper tube plate (3) is a flat tube plate, and the lower tube plate (4) is composed of a cylindrical side plate (41) and an arc-shaped top plate (42). The upper end of the L-shaped heat exchange tube (6) vertically passes through the upper tube plate (3) to communicate with the steam-water mixing chamber (103), and the lower end of the L-shaped heat exchange tube (6) is bent into an L shape toward the center of the reactor and then passes through the lower tube plate (4) to communicate with the hot water chamber (102).

3. An L-shaped wall tube water bed reactor according to claim 2, characterized in that: The L-shaped heat exchange tube (6) is formed by integrally bending a seamless steel tube.

4. The L-shaped wall tube water bed reactor according to claim 1, characterized in that: A central tube (13) with closed ends is axially arranged in the center of the reaction zone (104); the lower end of the central tube (13) is connected to the lower tube plate (4), and a catalyst flow channel is arranged between the upper end and the upper tube plate (3).

5. The L-shaped wall tube water bed reactor according to claim 1, characterized in that: A catalyst unloading pipe (12) connected to the reaction zone (104) is provided at the bottom of the outer cylinder (2), and a catalyst feeding pipe (11) connected to the reaction zone (104) is provided at the top center of the inner cylinder (1), and the catalyst feeding pipe (11) passes through the outer cylinder (2) to form an opening.

6. The L-shaped wall tube water bed reactor according to claim 1, characterized in that: The catalyst support plate (5) is an arc-shaped plate with a middle portion protruding upward.

7. A methanation process, characterized in that: The method is carried out using the L-shaped wall tube water bed reactor according to any one of claims 1 to 6, comprising the following steps: (1) The raw gas enters the reactor from the raw gas inlet pipe, flows upward along the annular gap to the upper end of the inner cylinder, and then enters the reaction zone through the first through hole. (2) Boiler water enters the hot water chamber from the water inlet pipe, is evenly distributed through the lower tube plate, and then enters the heat exchange tube, flowing upward along the heat exchange tube; (3) The raw gas passes through the catalyst bed from top to bottom in the reaction zone and reacts to generate methane under the action of the catalyst. The methane gas and the unreacted raw gas enter the gas outlet chamber through the second through hole and are discharged from the reactor through the reaction gas outlet pipe. The heat generated during the reaction is taken away by the heat exchange tube. The boiler water in the heat exchange tube is partially vaporized into water vapor after the temperature rises. The steam-water mixture enters the steam-water mixing chamber and is discharged from the reactor through the water steam outlet pipe.

8. A methanation process according to claim 7, characterized in that: The temperature of the raw gas entering the reactor is 220-230°C, and the temperature of the raw gas exiting the reactor is 250°C±5°C.

9. A methanation process according to claim 7, characterized in that: In step (3), the hot spot temperature of the catalyst at the initial stage of the reaction is 255±5°C.

10. A methanation process according to claim 7, characterized in that: The temperature of the boiler water is 150°C ± 5°C, and the pressure of the water vapor discharged from the reactor is 3.5 ± 5 MPa.

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