A tube-type fixed bed reactor

Abstract

The present invention is a tubular fixed bed reactor, comprising a cylinder, a plurality of reaction tubes are arranged in the cylinder, a gas distribution pipe is inserted in the reaction tube, and the gas distribution pipe can move axially; the gas distribution pipe is arranged in a spiral manner, and its side is against the inner wall of the reaction tube; a spiral channel is formed between the gas distribution pipe and the reaction tube, and the catalyst is placed in the spiral channel; the upper end of the gas distribution pipe is an air inlet, the lower end is closed, and a plurality of air holes are opened on the side; the air holes are arranged obliquely upward from the inside to the outside; the upper end of the reaction tube is closed, and the lower end is an exhaust port; after the reaction gas enters from the air inlet, it enters the reaction tube obliquely upward through the exhaust port to react, and then is discharged downward from the exhaust port for collection. Each airflow obliquely flowing upward from the air hole will form a fluidized state when entering the reaction tube, which can slow down the compaction of the catalyst and extend the catalyst replacement cycle; even if the catalyst is compacted, the catalyst can be loosened by driving the gas distribution pipe to move axially, so that the catalyst can continue to be used.

Description

Technical Field

[0001] The invention relates to the technical field of fixed bed reactors, in particular to a tubular fixed bed reactor. Background Art

[0002] In chemical production, fixed bed reactors are generally used to carry out reactions between gas phases under the action of catalysts.

[0003] Traditional fixed bed reactors usually encounter the following difficulties due to the slender pipes: 1. When filling new catalysts, the reactor's reaction tubes are very high, and some reaction tubes can be as high as 10m from the tube mouth to the bottom of the tube. When filling the tube with catalyst, if the catalyst is added directly from the high tube mouth into the tube, it will not only cause a large amount of catalyst to break, but also easily form a "bridging" phenomenon, causing holes in the bed layer and channel flow, which is not conducive to the catalytic reaction. In severe cases, it will also cause the tube wall to overheat. Therefore, special care must be taken when filling, and various tests such as pressure drop tests are required. 2. When replacing the catalyst, due to the slender pipes, blockages are often very serious. Common methods include water flushing, pipe poking, and knocking and vibration, which are not effective and are prone to cause weld cracks at the tube sheet and tube array. Summary of the invention

[0004] In order to solve the technical problems in the background technology, the present invention discloses a tube-in-tube fixed bed reactor.

[0005] The present invention provides a tubular fixed bed reactor, comprising a vertically arranged cylinder, a plurality of vertically arranged reaction tubes are arranged in the cylinder, a gas distribution pipe is inserted in the reaction tube, and the gas distribution pipe can move along the axial direction of the reaction tube;

[0006] The air distribution pipe is spirally arranged so that the outer wall of the air distribution pipe forms an outer spiral groove and the inner wall of the air distribution pipe forms an inner spiral hole;

[0007] A spiral channel for storing the catalyst is formed between the outer spiral groove and the inner wall of the reaction tube;

[0008] The upper end of the air distribution pipe is an air inlet, the lower end is closed, and the side is provided with multiple air holes;

[0009] The pores are arranged obliquely upward from the inside to the outside;

[0010] The upper end of the reaction tube is closed, and the lower end is an exhaust port;

[0011] A temperature control cavity for introducing a heat transfer medium is formed between the outer wall of the reaction tube and the inner wall of the cylinder, and the temperature control cavity and the spiral channel are isolated from each other;

[0012] After the reaction gas enters from the air inlet, it passes through the air holes and moves obliquely upward into the spiral channel to react, and the finished product is discharged and collected from the exhaust port.

[0013] The beneficial effects of the present invention are as follows: 1. The catalyst is added from the upper end of the reaction tube and slides down along the spiral channel, which prolongs the sliding path of the catalyst and reduces the impact force of the catalyst, thereby protecting the catalyst and preventing the catalyst from being damaged due to falling; 2. Each airflow flowing obliquely upward from the pores will form a fluidized state when entering the reaction tube, which can slow down the compaction of the catalyst and prolong the catalyst replacement cycle; 3. Even if the catalyst is compacted, the catalyst can be loosened by driving the air distribution pipe to move axially so that the catalyst can continue to be used; 4. When replacing the catalyst, the catalyst layer can be loosened by driving the air distribution pipe to move axially, so that the catalyst is easy to replace; 5. Since the general trend of the airflow is spiral downward, the gas flows obliquely upward when it flows out of the pores, and collides with the spiral downward airflow, thereby forming turbulence, prolonging the flow path of the airflow, and better promoting heat exchange inside and outside the reaction tube; 6. The airflow rotates downward in the reaction tube, and the rotation process can increase the turbulence and prolong the time of compaction up and down, so as to reduce the number of parking maintenance.

[0014] Furthermore, the air distribution pipe is a rectangular pipe. Compared with a round pipe, a rectangular pipe can be formed by twisting. When a round pipe is twisted, the depth of the outer spiral groove formed on its outer wall is shallow, resulting in insufficient space for the spiral channel.

[0015] The uniformity of the reaction temperature in the cylinder directly affects the stability of the reaction. Based on this, further improvements are: an air inlet pipe is provided at the lower end of the cylinder, and an air outlet pipe is provided at the upper end; the heat-conducting medium enters the cylinder from the air inlet pipe and flows out from the air outlet pipe. The heat-conducting medium enters from the bottom and exits from the top, and can cover the entire inner cavity of the cylinder, so that the temperature in the cylinder is stable, the reaction tube is heated evenly, and the reaction in the reaction tube is more stable; and such a setting is also convenient for controlling the reaction temperature in the cylinder.

[0016] The specific fixed structure of the reaction tube is: an upper orifice plate and a lower orifice plate are arranged up and down in the cylinder; the upper and lower ends of the reaction tube pass through the upper orifice plate and the lower orifice plate respectively; a closed temperature control chamber is formed between the upper orifice plate, the lower orifice plate, the outer wall of the reaction tube and the inner wall of the cylinder; the air inlet pipe and the air outlet pipe are both connected to the temperature control chamber.

[0017] In order to simplify the structure of the present invention, make the air intake in each reaction tube uniform, and improve the utilization rate of the reaction tube, a further design is: an air intake cavity is arranged above the upper orifice plate; the air inlets at the upper ends of the air distribution pipes are connected to the air intake cavity; an input pipe connected to the air intake cavity is arranged on the top of the cylinder; an exhaust cavity is arranged below the lower orifice plate; and an output pipe connected to the exhaust cavity is arranged at the lower end of the cylinder.

[0018] In order to facilitate driving the gas distribution pipe to move in the reaction tube, a further design is that the gas distribution pipe abuts against the inner wall of the reaction tube or has a gap fit with the inner wall of the reaction tube.

[0019] In order to prevent the reaction gas from directly entering the reaction tube, a further design is: a partition is also provided in the cylinder; a straight pipe section is provided at the upper end of the gas distribution pipe, and the partition is provided with a through hole that is shaped like the straight pipe section, and the through hole penetrates the straight pipe section upward; the upper end of the reaction tube abuts against the lower end surface of the partition, so that the air inlet cavity is separated from the inner cavity of the reaction tube.

[0020] To facilitate the disassembly and assembly of the partition, a further design is: the cylinder body includes a cylinder body; an upper head and a lower head are respectively provided at the upper and lower ends of the cylinder body, and the connection between the upper and lower heads is fixed by a flange connection; the partition is clamped between the cylinder body and the upper head.

[0021] The beneficial effects of the present invention are as follows: 1. The catalyst is added from the upper end of the reaction tube and slides down along the spiral channel, which prolongs the sliding path of the catalyst and reduces the impact force of the catalyst, thereby protecting the catalyst and preventing the catalyst from being damaged due to falling; 2. Each airflow flowing obliquely upward from the pores will form a fluidized state when entering the reaction tube, which can slow down the compaction of the catalyst and prolong the catalyst replacement cycle; 3. Even if the catalyst is compacted, the catalyst can be loosened by driving the air distribution pipe to move axially so that the catalyst can continue to be used; 4. When replacing the catalyst, the catalyst layer can be loosened by driving the air distribution pipe to move axially, so that the catalyst is easy to replace; 5. Since the general trend of the airflow is spiral downward, the gas flows obliquely upward when it flows out of the pores, and collides with the spiral downward airflow, thereby forming turbulence, prolonging the flow path of the airflow, and better promoting heat exchange inside and outside the reaction tube; 6. The airflow rotates downward in the reaction tube, and the rotation process can increase the turbulence and prolong the time of compaction up and down, so as to reduce the number of parking maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0023] Figure 1 is a front view of the present invention, wherein a part is cut away;

[0024] Figure 2 yes Figure 1 The enlarged view of point A in the middle;

[0025] Figure 3 This is a front cross-sectional view of the connection between the reaction tube and the gas distribution tube;

[0026] Figure 4 yes Figure 3 The enlarged view of point B in the middle;

[0027] Figure 5 yes Figure 3 Enlarged view of point C in the middle;

[0028] Figure 6 It is a schematic diagram of the structure of the air distribution pipe;

[0029] Figure 7 It is a schematic diagram of the structure of the sleeve;

[0030] In the figure: 1. cylinder; 2. reaction tube; 3. gas distribution pipe; 4. air inlet; 5. air hole; 6. exhaust port; 7. air inlet pipe; 8. air outlet pipe; 9. upper orifice plate; 10. lower orifice plate; 11. air inlet cavity; 12. input pipe; 13. exhaust cavity; 14. output pipe; 15. temperature control cavity; 16. partition; 17. sleeve; 31. straight pipe section; 32. through hole; 33. outer spiral groove; 34. inner spiral hole; 35. spiral channel; 101. cylinder body; 102. upper head; 103. lower head; 104. connecting flange; 105. upper flange; 106. lower flange. DETAILED DESCRIPTION

[0031] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0032] like Figure 1 As shown, the present invention discloses a tubular fixed bed reactor, comprising a vertically arranged cylinder 1. The cylinder 1 comprises a cylindrical body 101, and an upper end cap 102 and a lower end cap 103 are respectively arranged at the upper and lower ends of the cylinder 101. The upper and lower ends of the cylinder 101 are fixed with connecting flanges 104 by welding, and the lower end of the upper end cap 102 is connected with an upper flange 105, which is connected and fixed with the connecting flange 104 at the upper end of the cylinder 1 under the tightening action of bolts and nuts; the upper end of the lower end cap 103 is connected with a lower flange 106, which is connected and fixed with the connecting flange 104 at the lower end of the cylinder 1 under the tightening action of bolts and nuts. The top of the upper end cap 102 is connected with an input pipe 12, and a ball valve is installed on the input pipe 12 for inputting reaction gas into the cylinder 1. The lower end of the lower end cap 103 is connected with an output pipe 14, and a ball valve is also installed on the output pipe 14 for outputting finished products.

[0033] The upper ends of the inner wall of the barrel 101 are respectively provided with an upper orifice plate 9 and a lower orifice plate 10. The vertically arranged reaction tubes 2 are provided in multiple pieces, the upper ends of which penetrate the upper orifice plate 9, and the lower ends of which penetrate the lower orifice plate 10, and are connected and fixed by welding. The upper orifice plate 9 and the lower orifice plate 10 are also used for the installation and positioning of the reaction tube 2.

[0034] A closed temperature control chamber 15 is formed between the upper orifice plate 9, the lower orifice plate 10, the outer wall of the reaction tube 2 and the inner wall of the barrel 101; the upper part of the upper orifice plate 9 and the interior of the upper head 102 form an air intake chamber 11; the lower part of the lower orifice plate 10 and the interior of the lower head 103 form an exhaust chamber 13.

[0035] like Figure 3 and Figure 6As shown, a gas distribution pipe 3 is inserted into the reaction tube 2. The gas distribution pipe 3 is a rectangular tube, twisted into a spiral shape, so that the outer wall of the gas distribution pipe 3 forms an outer spiral groove 33, and the inner wall forms an inner spiral hole 34. The outer spiral groove 33 abuts against the inner wall of the reaction tube 2 or has a gap of 1-2 mm with the inner wall of the reaction tube 2. Such a design also allows the gas distribution pipe 3 to move along the axial direction of the reaction tube 2 in the reaction tube 2.

[0036] like Figure 5 As shown, the lower end of the reaction tube 2 is an exhaust port, and is threadedly connected with a sleeve 17. Figure 7 As shown, the bottom plate of the sleeve 17 is a perforated plate, so that the inner cavity of the reaction tube 2 is connected to the outside. A spiral channel 35 is formed between the outer spiral groove 33 and the inner wall of the reaction tube 2. The catalyst is placed in the spiral channel 35 and blocked by the perforated plate. The catalyst is granular, and its particle size is larger than the aperture of the perforated plate. The catalyst is added from the upper end of the reaction tube 2 and slides down along the spiral channel 35, which prolongs the sliding path of the catalyst and reduces the impact of the catalyst, thereby protecting the catalyst and preventing the catalyst from being damaged by falling.

[0037] The upper end of the gas distribution pipe 3 is an air inlet 4, the lower end is closed, and the side wall of the middle and upper section is also provided with a plurality of air holes 5, which are arranged obliquely upward from the inside to the outside. In this arrangement, after the reaction gas enters from the air inlet 4, it passes through the air holes 5 obliquely upward into the spiral channel 35 for reaction, and the finished product is discharged from the exhaust port 6. The particle size of the catalyst is larger than the aperture size of the air holes 5.

[0038] like Figure 4 As shown, since the general trend of the airflow is to spiral downward, the gas flows out of the air hole 5 obliquely upward, and collides with the spiral downward airflow, thereby forming turbulence, extending the flow path of the airflow, and better promoting heat exchange inside and outside the reaction tube 2;

[0039] A partition plate 16 is also provided between the upper head 102 and the barrel 101. Figure 2 As shown, the partition 16 is sandwiched between the upper flange 105 and the connecting flange 104, which is convenient for the partition 16 to be disassembled and assembled. The upper end of the gas distribution pipe 3 is provided with an untwisted straight pipe section 31, and the partition 16 is provided with a through hole that is shaped like the straight pipe section 31, and the straight pipe section 31 penetrates the through hole upward; the upper end of the reaction tube 2 abuts against the lower end surface of the partition 16. In this way, the inner cavity of the reaction tube 2 is separated from the air inlet cavity 11 to prevent the reaction gas from passing over the gas distribution pipe 3 and directly entering the reaction tube 2. The center position of the straight pipe section 31 is in contact with the through hole, so that the gas distribution pipe 3 can be moved axially in the reaction tube 2 by pushing and pulling the straight pipe section 31.

[0040] The lower end of the barrel body 101 is connected with an air inlet pipe 7, and the upper end is connected with an air outlet pipe 8. The air inlet pipe 7 and the air outlet pipe 8 are both connected with the temperature control chamber 15.

[0041] The working principle of a tubular fixed bed reactor of the present invention is as follows:

[0042] Before the reaction, the heat-conducting medium first enters the temperature control chamber 15 from the air inlet pipe 7 and flows out from the air outlet pipe 8, so that the temperature required for the reaction is reached in the reaction tube 2. Then, the ball valve on the cylinder is opened to allow the reaction gas to enter the air inlet chamber 11 from the input pipe 12 and enter the air inlet 4 respectively, so that the reaction gas can evenly enter the air distribution pipe 3; then the reaction gas enters the reaction tube 2 obliquely upward from the air hole 5, and chemical reactions occur in the reaction tube 2 under the action of the catalyst; each airflow flowing obliquely upward from the air hole 5 will form a fluidized state when entering the reaction tube 2, which can slow down the compaction of the catalyst and extend the catalyst replacement cycle. After passing through the air hole 5, the reaction gas first flows obliquely upward and then flows downward, thereby extending the flow path of the airflow, and the turbulence between the lateral directions can better promote the heat exchange inside and outside the reaction tube 2. The airflow rotates and moves downward in the reaction tube 2. The rotation process can increase the turbulence and extend the time of the upper and lower compaction, so as to reduce the number of parking maintenance. The finished product after the reaction is completed flows out from the exhaust port 6 into the exhaust chamber 13, and is finally discharged from the output pipe 14 for collection.

[0043] When the catalyst is compacted, it is only necessary to open the upper end cap and drive the air distribution pipe 3 to move axially to loosen the catalyst so that the catalyst can continue to be used. Moreover, when replacing the catalyst, the sleeve 17 is removed, the lower end cap 103 is opened, and the catalyst layer is loosened by driving the air distribution pipe 3 to move axially, so that the catalyst can fall smoothly from the spiral channel, thereby facilitating replacement.

[0044] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A tube-in-tube fixed bed reactor, comprising a vertically arranged cylinder (1), wherein a plurality of vertically arranged reaction tubes (2) are arranged in the cylinder (1), characterized in that: A gas distribution pipe (3) is inserted into the reaction tube (2), and the gas distribution pipe (3) can move axially along the reaction tube (2); The air distribution pipe (3) is spirally arranged, so that the outer wall of the air distribution pipe (3) forms an outer spiral groove (33), and the inner wall of the air distribution pipe (3) forms an inner spiral hole (34); A spiral channel (35) for storing a catalyst is formed between the outer spiral groove (33) and the inner wall of the reaction tube (2); The air distribution pipe (3) has an air inlet (4) at its upper end, a closed lower end, and a plurality of air holes (5) at its side. The air holes (5) are arranged obliquely upward from the inside to the outside; The reaction tube (2) has a closed upper end and an exhaust port (6) at the lower end; A temperature control cavity (15) for passing a heat-conducting medium is formed between the outer wall of the reaction tube (2) and the inner wall of the cylinder (1), and the temperature control cavity (15) and the spiral channel (35) are isolated from each other; After the reaction gas enters from the gas inlet (4), it passes through the gas hole (5) and enters the spiral channel (35) obliquely upward to react, and the finished product is discharged from the exhaust port (6) for collection; The air distribution pipe (3) is a rectangular pipe.

2. A tubular fixed bed reactor according to claim 1, characterized in that: The lower end of the cylinder (1) is provided with an air inlet pipe (7), and the upper end is provided with an air outlet pipe (8); The heat-conducting medium enters the cylinder (1) from the air inlet pipe (7) and flows out from the air outlet pipe (8).

3. A tubular fixed bed reactor according to claim 2, characterized in that: An upper perforated plate (9) and a lower perforated plate (10) are arranged in the cylinder (1); The upper and lower ends of the reaction tube (2) respectively penetrate the upper orifice plate (9) and the lower orifice plate (10); A closed temperature control chamber (15) is formed between the upper orifice plate (9), the lower orifice plate (10), the outer wall of the reaction tube (2), and the inner wall of the cylinder (1); The air inlet pipe (7) and the air outlet pipe (8) are both in communication with the temperature control chamber (15).

4. A tubular fixed bed reactor according to claim 3, characterized in that: An air inlet cavity (11) is provided above the upper perforated plate (9); The air inlet (4) at the upper end of the air distribution pipe (3) is communicated with the air inlet cavity (11); An inlet pipe (12) communicating with the air inlet cavity (11) is provided at the top of the cylinder (1); An exhaust cavity (13) is provided below the lower perforated plate (10); An output pipe (14) communicating with the exhaust chamber (13) is provided at the lower end of the cylinder (1).

5. The tubular fixed bed reactor according to claim 1, characterized in that: The gas distribution pipe (3) abuts against the inner wall of the reaction tube (2) or is gap-matched with the inner wall of the reaction tube (2).

6. The tubular fixed bed reactor according to claim 4, characterized in that: A partition plate (16) is also provided in the cylinder (1); The upper end of the air distribution pipe (3) is provided with a straight pipe section (31), the partition plate (16) is provided with a through hole (32) conforming to the straight pipe section (31), and the through hole (32) penetrates the straight pipe section (31) upward; The upper end of the reaction tube (2) abuts against the lower end surface of the partition plate (16), so that the air inlet cavity (11) is separated from the inner cavity of the reaction tube (2).

7. The tubular fixed bed reactor according to claim 6, characterized in that: The cylinder (1) comprises a cylinder body (101); An upper end cap (102) and a lower end cap (103) are respectively provided at the upper and lower ends of the cylinder body (101), and the connection between the upper and lower ends is fixed by a flange connection; The partition plate (16) is sandwiched between the cylinder body (101) and the upper cover (102).

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