Explosion-proof reactor and application

Abstract

The invention provides an explosion-proof reactor and application, and belongs to the field of chemical equipment. The explosion-proof reactor comprises a shell with openings in the upper end and the lower end, and an upper sealing head and a lower sealing head which are respectively arranged at the upper end and the lower end of the shell; a plurality of reaction tubes are arranged in the inner cavity of the shell; a feeding sleeve is arranged on the upper sealing head, and a first feeding hole and a second feeding hole are formed in the feeding sleeve; a discharge hole is formed in the lower sealing head; and explosion-proof grids are respectively arranged in the inner cavities of the upper sealing head and the lower sealing head. The tail end spray pipe of the feeding distributor penetrates through the anti-explosion grid to directly introduce a combustible raw material medium into the reaction pipe, so that an explosion atmosphere is prevented from being formed in the space of the upper sealing head. According to the explosion-proof reaction tube, the explosion atmosphere is limited in the reaction tube, possible fire explosion in the reaction tube is controlled within the range of the reaction tube through the explosion-proof grids at the two ends of the reaction tube, the explosion-proof grids serve as a detonation-resistant or detonation-resistant flame arrester of the reaction tube, and then the explosion-proof effect is achieved.

Description

Technical Field

[0001] The invention belongs to the field of chemical equipment, and in particular relates to an explosion-proof reactor and its application. Background Art

[0002] The reactor is the core equipment of the chemical plant. In the oxidation reaction process, the typical reactor is a gas-solid reactor in which a solid catalyst catalyzes the reaction of gaseous raw materials. In this type of reactor, air or oxygen-containing gas is often used as an oxidant, which is mixed with flammable and explosive reaction raw materials, so it is very easy to form an explosive atmosphere in the reactor. At the same time, the oxidation reaction requires a higher temperature to initiate, and the reaction is mostly an exothermic reaction, so the minimum explosion ignition energy corresponding to the explosive atmosphere is also easy to achieve. Therefore, this type of reactor is very easy to have the three elements of explosive combustion in terms of technology: combustibles, combustion aids, and ignition energy.

[0003] At present, the main safety measures in the industry for gas-solid two-phase reactors that use air or oxygen-containing gas for oxidation reactions are to suppress the expansion of explosion consequences and prevent the occurrence of explosions.

[0004] The measures to suppress the consequences of explosion are mostly pressure relief facilities such as bursting discs, etc. However, this method cannot prevent the occurrence of explosions, but can only limit the consequences of explosions to an acceptable range.

[0005] Preventing explosions mainly starts from the three elements of explosion and combustion. Both the combustibles and the combustion-supporting materials are reaction raw materials, and the ignition energy is mostly a reaction condition, and the generation of the three elements of combustion cannot be completely avoided. Therefore, the current explosion-proof means mainly control the gas phase system in the reactor outside the explosion limit of the reaction raw materials, that is, limit the concentration of the reaction raw materials. This method prevents combustion from developing into explosion from the perspective of the concentration of the combustibles.

[0006] Limiting the concentration of flammable and explosive reaction raw materials to achieve explosion-proof design also limits the efficiency of the reactor. The lower explosion limit of some flammable and explosive reaction raw materials is very low, and the upper explosion limit is relatively high. Therefore, if the reaction system is completely controlled outside the explosion limit, the concentration of the reactants is too high, which can easily cause most of the raw materials to not participate in the reaction, or even too many side reactions, low reaction yield, and serious waste; if the concentration of the reaction raw materials is too low, the concentration of the target product in the reaction gas is too low, the reactor size is large, and the processing capacity is small.

[0007] Therefore, for many gas-solid reaction systems that use solid-phase catalysts and have relatively high reaction temperatures, if the explosion limit can be effectively broken through and the concentration of the reaction raw materials can be adjusted so that the ratio of the raw materials to air or oxygen-containing gas is closer to the optimal ratio required for the reaction, the design of the reactor can be effectively optimized. Summary of the invention

[0008] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art and to provide an explosion-proof reactor and its application to achieve explosion-proof effect from the perspective of intrinsically safe design.

[0009] The present invention is achieved through the following technical solutions:

[0010] A first aspect of the present invention provides an explosion-proof reactor, comprising: a shell having openings at both ends, and an upper head and a lower head respectively arranged at the upper and lower ends of the shell;

[0011] A plurality of reaction tubes are arranged in the inner cavity of the shell;

[0012] A feed sleeve is arranged on the upper head, and a first feed port and a second feed port are arranged on the feed sleeve;

[0013] A discharge port is arranged on the lower head;

[0014] Explosion-proof grids are respectively arranged in the inner cavities of the upper head and the lower head.

[0015] A further improvement of the present invention is:

[0016] An upper tube plate and a lower tube plate are respectively arranged at the upper end and the lower end of the inner cavity of the shell;

[0017] The upper tube plate and the lower tube plate are respectively provided with vertically penetrating holes;

[0018] Each reaction tube is a tubular structure with openings at both ends;

[0019] The upper end of each reaction tube is connected to the hole on the upper tube plate, and the lower end is connected to the hole on the lower tube plate.

[0020] A further improvement of the present invention is:

[0021] An outlet for the outer space of the reaction tube is arranged on the upper side wall of the shell;

[0022] An inlet for the external space of the reaction tube is arranged on the lower side wall of the shell.

[0023] A further improvement of the present invention is:

[0024] An upper explosion-proof grid is arranged in the lower inner cavity of the upper head;

[0025] A lower explosion-proof grid is arranged in the upper inner cavity of the lower head;

[0026] The upper explosion-proof grid is located above the upper tube plate;

[0027] The lower explosion-proof grid is located below the lower tube plate.

[0028] A further improvement of the present invention is:

[0029] A feed distributor is arranged in the inner cavity of the upper head;

[0030] The upper end of the feed distributor is connected to the second feed port, and the lower end of the feed distributor is provided with a plurality of terminal nozzles;

[0031] The lower end of each terminal nozzle passes through the upper explosion-proof grid and is inserted into the reaction tube in mid-air.

[0032] Preferably, the terminal nozzle is a needle tube or a thin tube.

[0033] A further improvement of the present invention is:

[0034] The feed sleeve comprises: an outer tube and an inner tube passing through the inner cavity of the outer tube;

[0035] An annulus is formed between the outer wall of the inner tube and the inner wall of the outer tube, and the annulus is communicated with the inner cavity of the upper head;

[0036] The upper end of the outer tube is located outside the upper head, and the lower end is located in the inner cavity of the upper head;

[0037] A first feed inlet is provided on the wall of the outer tube;

[0038] The inlet end of the inner tube is located outside the upper end of the outer tube, and the inlet end of the inner tube serves as the second feed port;

[0039] The outlet end of the inner tube is located outside the lower end of the outer tube and is communicated with the feed distributor.

[0040] A further improvement of the present invention is:

[0041] The first feed port is used to inject oxidizing air, and the oxidizing air enters the inner cavity of the upper head through the annulus between the inner tube and the outer tube from the first feed port, and enters the reaction tube through the upper explosion-proof grid.

[0042] A further improvement of the present invention is:

[0043] The second feed inlet is used to inject the combustible raw material medium, and the combustible raw material medium directly enters the reaction tube from the second feed inlet through the terminal nozzle.

[0044] The second aspect of the present invention provides the use of the above-mentioned explosion-proof reactor in the oxidation reaction of p-xylene and air.

[0045] Compared with the prior art, the present invention has the following beneficial effects: the terminal nozzle of the feed distributor in the present invention passes through the explosion-proof grid to directly pass the combustible raw material medium into the reaction tube, thereby avoiding the formation of an explosive atmosphere in the space of the upper head. The present invention limits the explosive atmosphere within the reaction tube, and controls the combustion and explosion that may occur in the reaction tube within the range of the reaction tube through the explosion-proof grids at both ends of the reaction tube. The explosion-proof grids serve as a detonation or deflagration retardant for the reaction tube, thereby achieving an explosion-proof effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic structural diagram of an explosion-proof reactor of the present invention;

[0047] Among them, 1. Shell; 2. Reaction tube; 3. Catalyst; 4. Flow channel of the outer space of the reaction tube; 5. Explosion-proof grid; 6. Feed distributor; 7. Feed sleeve 7; 8. Discharge port; 9. Upper head; 10. First feed port; 11. Second feed port; 12. Terminal nozzle; 13. Inlet of the outer space of the reaction tube; 14. Outlet of the outer space of the reaction tube. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0049] The present invention provides an explosion-proof reactor. By utilizing the explosion-proof grid inside the reactor, even if the reaction gas phase system is within the explosion limit range and has the minimum ignition energy, the generation of explosion overpressure can be suppressed.

[0050] The main principle of the present invention is to utilize the "vessel wall effect" to divide the interior of the reactor into a considerable number of small reaction spaces. Even if combustion occurs in part of the reaction space, the conduction of combustion can be suppressed by suppressing heat conduction, and then the occurrence of gas phase flash explosion can be effectively suppressed in the reactor.

[0051] The explosion-proof reactor provided by the present invention is a tubular reactor, in which the reaction raw materials and oxidizing gas are fed from the top of the reactor and discharged from the bottom. A catalyst 3 is loaded in the middle section of the reaction tube, and a flow channel 4 in the outer space of the reaction tube is used to remove heat and maintain the reaction temperature through a heat removal medium such as molten salt or heat transfer oil.

[0052] like Figure 1As shown, the explosion-proof reactor provided by the present invention comprises: a shell 1 with openings at both ends, and an upper head 9 and a lower head respectively arranged at the upper and lower ends of the shell 1. A plurality of reaction tubes are arranged in the inner cavity of the shell 1; a feed sleeve 7 is arranged on the upper head 9, and the reaction raw materials are injected into the explosion-proof reactor from the feed sleeve 7. Specifically, two feed ports are arranged on the feed sleeve 7, namely a first feed port 10 and a second feed port 11, and the first feed port 10 is used to inject oxidizing air. The second feed port is used to inject a combustible raw material medium. A discharge port 8 is arranged on the lower head. Explosion-proof grids 5 are respectively arranged in the inner cavities of the upper head and the lower head.

[0053] The explosion-proof grid 5 is generally made of a metal material with good thermal conductivity and is honeycomb-shaped. The principle is to use the heat transfer effect of metal or other materials and the wall effect to prevent explosion, which is similar to the internal structure of a flame arrester.

[0054] The embodiments of the explosion-proof reactor of the present invention are as follows:

[0055] Embodiment 1:

[0056] An upper tube sheet and a lower tube sheet are respectively arranged at the upper end and the lower end of the inner cavity of the shell 1, and a plurality of holes are respectively opened on the upper tube sheet and the lower tube sheet. Each reaction tube 2 is a tubular structure with both ends open. The upper end of each reaction tube 2 is connected to the hole on the upper tube sheet, and the lower end of each reaction tube 2 is connected to the hole on the lower tube sheet. The two ends of the reaction tube 2 can be connected to the holes of the upper tube sheet and the lower tube sheet by using a variety of existing sealing connection methods. The two ends of the reaction tube 2 correspond to the holes on the upper tube sheet and the lower tube sheet respectively. After installation, the central axis of each reaction tube is parallel to the central axis of the shell 1.

[0057] A closed reaction tube external space flow channel 4 is formed between the lower end surface of the upper tube plate, the upper end surface of the lower tube plate, the outer walls of each reaction tube 2 and the inner wall of the shell 1 .

[0058] Furthermore, a reaction tube external space outlet 14 is provided on the upper side wall of the shell 1, and a reaction tube external space inlet 13 is provided on the lower side wall of the shell 1. The heat removal medium can enter the reaction tube external space flow channel 4 from the reaction tube external space inlet 13, and after heat exchange, the heat removal medium flows out from the reaction tube external space outlet 14.

[0059] Embodiment 2:

[0060] An upper explosion-proof grid is provided in the lower inner cavity of the upper head 9, and a lower explosion-proof grid is provided in the upper inner cavity of the lower head. The upper head 9 is connected to the flange ( Figure 1After the flange is indicated by a horizontal line in the middle) is installed at the upper end of the shell 1, the upper explosion-proof grid in the upper head 9 is located above the upper tube sheet, and the material can pass through the upper explosion-proof grid to enter the reaction tube 2. After the lower head is installed at the lower end of the shell 1 through the flange, the lower explosion-proof grid in the lower head is located below the lower tube sheet, and the reacted material can pass through the lower explosion-proof grid and be discharged from the discharge port 8.

[0061] Embodiment 3:

[0062] A feed distributor 6 is also provided in the inner cavity of the upper head 9, and the upper end of the feed distributor 6 is connected to the second feed port 11. A plurality of terminal nozzles 12 are provided at the lower end of the distributor 6, and the lower end of each terminal nozzle 12 is directly inserted into the reaction tube 2 in midair after passing through the upper explosion-proof grid, so that the combustible medium raw material injected from the second feed port 11 is directly passed into the reaction tube 2 through the terminal nozzle 12, thus avoiding the formation of an explosive atmosphere in the inner cavity of the upper head 9. Moreover, since the terminal nozzle 12 is inserted into the reaction tube 2 in midair, air can enter the reaction tube 2 through the annulus between the outer wall of the terminal nozzle 12 and the inner wall of the reaction tube 2.

[0063] The end nozzle 12 is a needle tube or a thin tube, which can effectively prevent the reaction in the reaction tube from getting out of control and flashing, causing materials and flames to rush into the feed distributor 6 and cause a chain reaction.

[0064] Embodiment 4:

[0065] The feed sleeve 7 is a sleeve structure, including an outer tube and an inner tube passing through the inner cavity of the outer tube. The inner diameter of the outer tube is larger than the outer diameter of the inner tube. An annulus is formed between the outer wall of the inner tube and the inner wall of the outer tube, and the annulus is connected to the inner cavity of the upper head 9. The upper end of the outer tube is located outside the upper head 9, and the lower end is located in the inner cavity of the upper head 9. A first feed port 10 is opened on the wall of the outer tube, and the first feed port 10 connects the outside of the outer tube with the annulus. The inlet end of the inner tube is located outside the upper end of the outer tube, and the inlet end of the inner tube serves as the second feed port 11. The outlet end of the inner tube is located outside the lower end of the outer tube and is connected to the feed distributor.

[0066] Typical working conditions for applying the device of the present invention are as follows:

[0067] The oxidizing air injected from the first feed port 10 enters the inner cavity of the upper head 9 through the annulus between the inner tube and the outer tube, and enters the reaction tube 2 through the upper explosion-proof grid. The combustible raw material medium injected from the second feed port 11 directly enters the reaction tube 2 through the terminal nozzle 12 of the feed distributor 6. In this way, the combustible raw material medium does not mix with the oxidizing air in the inner cavity of the upper head 9, but contacts the catalyst 3 in the reaction tube 2 separated by the explosion-proof grid 5 to undergo an oxidation reaction, and the reaction product passes through the lower explosion-proof grid and is discharged from the discharge port 8.

[0068] The present invention limits the explosive atmosphere to the reaction tube 2, and controls the possible combustion and explosion in the reaction tube 2 within the range of the reaction tube through the explosion-proof grids 5 at both ends of the reaction tube 2. The explosion-proof grids serve as detonation or explosion-retardant flame arresters for the reaction tube, thereby achieving an explosion-proof effect from the perspective of intrinsically safe design.

[0069] The embodiment of applying the device of the present invention to the oxidation reaction of p-xylene and air is as follows:

[0070] Embodiment 5:

[0071] Para-xylene and air are mixed and catalytically oxidized to form terephthalaldehyde at a high temperature of 300-400°C and a low pressure of 0.05 MPaG. Para-xylene is heated and vaporized and enters the reactor from the second feed port 11, and air is preheated and enters the reactor from the first feed port 10. Para-xylene passes through the feed distributor 6 and directly sprays into the reaction tube 2 with a diameter of 32 mm and a length of 2-3 m without contacting the air through the upper explosion-proof grid. The air passes through the upper head space and the upper explosion-proof grid into the reaction tube 2.

[0072] The reaction tube 2 is filled with a catalyst 3, and is heated to 300-400°C by the high-temperature molten salt in the flow channel 4 outside the reaction tube (the molten salt is preheated to 300-400°C from the outside, and then enters the flow channel 4 outside the reaction tube to heat the reaction tube to initiate the reaction in the reaction tube. Generally, the oxidation reaction is an exothermic reaction, that is, heat is released after the reaction is initiated, and the flowing molten salt is a heat removal medium at a higher temperature in the lower half of the reaction tube. The use of molten salt maintains a stable high temperature in the reactor). Paraxylene and air are evenly mixed in the upper space of the reaction tube 2, and contact the catalyst in the process of flowing downward (the feed pressure of paraxylene and air is higher than the pressure in the reaction tube, thereby promoting the mixed reactants to flow downward), completing the oxidation reaction, and the mixture of terephthalaldehyde and unreacted air generated by the reaction passes through the lower explosion-proof grid and is discharged through the discharge port 8.

[0073] The explosion limit of p-xylene in air is 1.1-7% (V). According to the reaction characteristics, p-xylene is most suitable for reaction at a feed concentration of 2-5% (V) (the concentration configuration is controlled by a flow controller on the pipe connecting the first feed port and the second feed port, and is not within the protection scope of the present invention). Therefore, it is necessary to try to react within the explosion limit of p-xylene. In the present invention, the highest concentration of p-xylene is the lower side of the upper explosion-proof grid, where the end nozzle 12 sprays the medium and the air. Therefore, the situation where the p-xylene concentration is within the explosion limit only occurs in the reaction tube, which is different from mixing directly in the upper head. This mixing method makes the atmosphere within the explosion limit appear in a very small reaction tube, making it difficult for a deflagration interlocking reaction to occur. Therefore, even if a deflagration occurs in part of the reaction tube, it can be effectively isolated to prevent the reactor from exploding.

[0074] In the present invention, the mixture of paraxylene and air exists only in the reaction tube 2, and the inlet and outlet of the reaction tube 2 are blocked by the metal explosion-proof grid 5. Therefore, when combustion or deflagration occurs in the reaction tube 2, when the flame flashes back upstream, since the end nozzle 12 is a pinhole injection feed, the tiny pinhole can effectively prevent the flashback from entering the second feed port 11, and the explosion-proof grid 5 can prevent the flashback from entering the reactor upper head 9. The present invention effectively limits the oxidation reaction explosion to the slender reaction tube 2, thereby preventing the reactor from exploding.

[0075] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0077] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. An explosion-proof reactor, characterized in that: The explosion-proof reactor comprises: a shell with openings at both ends, and an upper head and a lower head respectively arranged at the upper and lower ends of the shell; A plurality of reaction tubes are arranged in the inner cavity of the shell; A feed sleeve is arranged on the upper head, and a first feed port and a second feed port are arranged on the feed sleeve; A discharge port is arranged on the lower head; Explosion-proof grids are respectively arranged in the inner cavities of the upper head and the lower head.

2. The explosion-proof reactor according to claim 1, characterized in that: An upper tube plate and a lower tube plate are respectively arranged at the upper end and the lower end of the inner cavity of the shell; The upper tube plate and the lower tube plate are respectively provided with vertically penetrating holes; Each reaction tube is a tubular structure with openings at both ends; The upper end of each reaction tube is connected to the hole on the upper tube plate, and the lower end is connected to the hole on the lower tube plate.

3. The explosion-proof reactor according to claim 1, characterized in that: An outlet for the outer space of the reaction tube is arranged on the upper side wall of the shell; An inlet for the external space of the reaction tube is arranged on the lower side wall of the shell.

4. The explosion-proof reactor according to claim 2, characterized in that: An upper explosion-proof grid is arranged in the lower inner cavity of the upper head; A lower explosion-proof grid is arranged in the upper inner cavity of the lower head; The upper explosion-proof grid is located above the upper tube plate; The lower explosion-proof grid is located below the lower tube plate.

5. The explosion-proof reactor according to claim 4, characterized in that: A feed distributor is arranged in the inner cavity of the upper head; The upper end of the feed distributor is connected to the second feed port, and the lower end of the feed distributor is provided with a plurality of terminal nozzles; The lower end of each terminal nozzle passes through the upper explosion-proof grid and is inserted into the reaction tube in mid-air.

6. The explosion-proof reactor according to claim 5, characterized in that: The terminal nozzle adopts a needle tube or a thin tube.

7. The explosion-proof reactor according to claim 5, characterized in that: The feed sleeve comprises: an outer tube and an inner tube passing through the inner cavity of the outer tube; An annulus is formed between the outer wall of the inner tube and the inner wall of the outer tube, and the annulus is communicated with the inner cavity of the upper head; The upper end of the outer tube is located outside the upper head, and the lower end is located in the inner cavity of the upper head; A first feed inlet is provided on the wall of the outer tube; The inlet end of the inner tube is located outside the upper end of the outer tube, and the inlet end of the inner tube serves as the second feed port; The outlet end of the inner tube is located outside the lower end of the outer tube and is communicated with the feed distributor.

8. The explosion-proof reactor according to claim 7, characterized in that: The first feed port is used to inject oxidizing air, and the oxidizing air enters the inner cavity of the upper head through the annulus between the inner tube and the outer tube from the first feed port, and enters the reaction tube through the upper explosion-proof grid.

9. The explosion-proof reactor according to claim 7, characterized in that: The second feed inlet is used to inject the combustible raw material medium, and the combustible raw material medium directly enters the reaction tube from the second feed inlet through the terminal nozzle.

10. Use of the explosion-proof reactor according to any one of claims 1 to 9 in the oxidation reaction of p-xylene and air.

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