Fixed bed reactor for methylamine synthesis

Abstract

The utility model discloses a fixed bed reactor for methylamine synthesis, which comprises a reactor body, the top of the reactor body is communicated with a mixed raw material gas inlet pipe, and the bottom of the mixed raw material gas inlet pipe is provided with a primary distributor; the bottom of the reactor body is communicated with a discharge pipe; a plurality of groups of reaction cavities are sequentially arranged in the reactor body from top to bottom, a material tube pass is communicated between the upper reaction cavity and the lower reaction cavity, redistributors and catalyst packing layers are arranged in the reaction cavities, and the redistributors are positioned above the catalyst packing layers; a first refrigerant inlet is formed in one side of the material tube pass, and a first heating medium outlet is formed in the other side of the material tube pass. Catalyst particles are in a stable accumulation state in the flowing direction from top to bottom, so that the bed expansion or channeling phenomenon caused by airflow impact is reduced, and the service life of the catalyst is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical industry, in particular to a fixed bed reactor for methylamine synthesis. Background Art

[0002] Currently, industrial-scale methylamine synthesis methods both domestically and internationally typically involve continuously passing methanol and ammonia through a reactor in the presence of solid acid catalysts such as γ-Al2O3, Al2O3-SiO2, AlPO, MgO, or ThO2. The reaction is typically conducted at 0.5-4.0 MPa and 350-500°C. Methylamine production systems typically use methanol and liquid ammonia as raw materials for catalytic synthesis to produce crude methylamine. This crude methylamine then undergoes a series of distillation steps, including deamination towers, extraction towers, dehydration towers, and separation towers, to yield monomethylamine, dimethylamine, and trimethylamine, respectively.

[0003] In the aforementioned process of catalyzing the synthesis of crude methylamine from methanol and liquid ammonia, the reaction requires high reaction temperatures and generates significant heat. Prior to the reaction, the raw materials must be heated from ambient temperature to the desired reaction temperature. After the reaction, the product must be cooled from a high temperature to a low temperature before being fed into the subsequent distillation process.

[0004] Currently, fixed-bed adiabatic reactors are mostly used in the methylamine synthesis process. The feed gas enters from the top of the reactor, passes through the catalyst bed, and leaves from the bottom. It has the following main disadvantages:

[0005] 1. After the raw gas enters the reactor, it is difficult to control the temperature of the entire reaction process, so the reaction is difficult to proceed at the optimal reaction temperature (390℃~410℃);

[0006] 2. In conventional adiabatic reactors, the gas phase is difficult to distribute evenly, which easily produces local hot spots, reducing the reaction conversion rate and also affecting the catalyst life.

[0007] To this end, the utility model proposes a fixed bed reactor suitable for methylamine synthesis, which can effectively control the uniform distribution of the gas phase and avoid local temperatures being too high or too low. Utility Model Content

[0008] In order to solve the problems mentioned in the above background technology, the utility model provides a fixed bed reactor for methylamine synthesis.

[0009] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0010] A fixed-bed reactor for methylamine synthesis comprises a reactor body, wherein the top of the reactor body is connected to a mixed raw material inlet pipe, and the bottom of the mixed raw material inlet pipe is provided with a primary distributor; the bottom of the reactor body is connected to a discharge pipe; multiple groups of reaction chambers are sequentially arranged from top to bottom in the reactor body, and a material pipe is connected between the upper and lower reaction chambers; a redistributor and a catalyst packing layer are provided in the reaction chamber, and the redistributor is located above the catalyst packing layer;

[0011] The material pipe side is arranged in multiple groups side by side, and a first refrigerant inlet and a first heat medium outlet are provided through the external shell side.

[0012] Preferably, the primary distributor comprises an annular nozzle, a plurality of nozzles are distributed in an annular pattern at the bottom of the annular nozzle, and the mixed raw material air inlet pipe is connected to the annular nozzle through a connecting pipe.

[0013] Preferably, the redistributor comprises a downcomer, a liquid blocking cap is provided on the top of the downcomer, and the top of the downcomer is in an inclined opening shape.

[0014] Preferably, the downcomer is fixed by a bottom plate, and weir plates are provided around the bottom plate, and the weir plates are fixed to the inner wall of the reaction chamber.

[0015] Preferably, the outer wall of the reaction chamber is provided with a jacket, the bottom side of the jacket is connected to a second refrigerant inlet, and the upper side of the jacket is connected to a second heat medium outlet.

[0016] Preferably, the upper end of the catalyst packing layer is connected to a loading port, and the bottom end is connected to a discharging port.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The utility model provides a primary distributor and a redistributor, so that the mixed raw materials in the mixed raw material inlet pipe can be evenly dispersed, so that they can fully contact with the solid acid catalyst. The flow direction from top to bottom keeps the catalyst particles in a stable accumulation state, reduces bed expansion or channeling caused by airflow impact, and extends the service life of the catalyst.

[0019] The distributor, through its internal structural design, enables the gas to be evenly distributed when entering the reactor, avoiding local gas concentrations that are too high or too low, thereby ensuring the uniformity and efficiency of the reaction. The gas distributor usually includes an air inlet, an air outlet, and an internal gas control mechanism. The air inlet receives compressed gas from the gas source, and the air outlet distributes the gas evenly to various parts of the reactor. Its internal structure ensures that the gas can be evenly dispersed before entering the reactor through the design of a downcomer and a liquid retaining cap. The conical cap structure design of the liquid retaining cap on the upper part prevents the gas from directly entering the distribution pipe. Holes of the same diameter are opened on both sides of each distribution pipe to ensure that the gas flow and flow rate are uniform. After distribution, it is discharged from the bottom to the next layer of catalyst section. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0022] Figure 2 This is a schematic diagram of the installation structure of the redistributor of the utility model;

[0023] Figure 3 For this utility model Figure 2 A magnified schematic diagram of the structure in the middle;

[0024] Figure 4 This is a structural diagram of the primary distributor of the utility model.

[0025] In the figure: reactor body 1, mixed raw material inlet pipe 2, discharge pipe 3, primary distributor 4, annular nozzle 41, nozzle 42, connecting pipe 43, redistributor 5, bottom plate 51, weir plate 52, downcomer 53, liquid blocking cap 54, catalyst packing layer 6, jacket 7, material pipe 8, first refrigerant inlet 9, first heat medium outlet 10, second refrigerant inlet 11, second heat medium outlet 12, loading port 13, unloading port 14. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Reference Figure 1-4 A fixed-bed reactor for methylamine synthesis comprises a reactor body 1, the top of the reactor body 1 being connected to a mixed raw material inlet pipe 2, the bottom of which is provided with a primary distributor 4; the bottom of the reactor body 1 being connected to a discharge pipe 3; the reactor body 1 being provided with multiple groups of reaction chambers arranged sequentially from top to bottom, the upper and lower reaction chambers being connected by a material pipe 8, a redistributor 5 and a catalyst packing layer 6 being provided in the reaction chambers, the redistributor 5 being located above the catalyst packing layer 6;

[0028] The material pipe side 8 is arranged in multiple groups side by side, and a first refrigerant inlet 9 is provided on one side of the external shell side, and a first heat medium outlet 10 is provided on the other side.

[0029] The primary distributor 4 includes an annular nozzle 41, and multiple groups of nozzles 42 are distributed in an annular manner at the bottom of the annular nozzle 41. The mixed raw material inlet pipe 2 is connected to the annular nozzle 41 through a connecting pipe 43. The nozzles 42 are facing the catalyst packing layer 6, so that the mixed raw material in the mixed raw material inlet pipe 2 can be evenly dispersed, thereby fully contacting with the solid acid catalyst.

[0030] The redistributor 5 includes a downcomer 53, a liquid blocking cap 54 is provided on the top of the downcomer 53, and the top of the downcomer 53 is an inclined opening. The downcomer 53 is fixed by a bottom plate 51, and a weir plate 52 is provided around the bottom plate 51, and the weir plate 52 is fixed to the inner wall of the reaction chamber.

[0031] The outer wall of the reaction chamber is provided with a jacket 7, the bottom side of the jacket 7 is connected to a second refrigerant inlet 11, the upper side is connected to a second heat medium outlet 12, the upper side of the catalyst packing layer 6 is connected to a loading port 13, and the bottom side is connected to a discharge port 14.

[0032] The reaction raw materials enter the reactor through the mixed raw material inlet pipe 2, and are first evenly distributed through the annular nozzle 41 on the primary distributor 4 to avoid excessively high or low local gas concentrations, thereby ensuring the uniformity and efficiency of the reaction; then pass through the redistributor 5, whose internal structure is designed with a series of downcomers 53 and liquid retaining caps 54 to ensure that the gas can be evenly dispersed before entering the reactor. The reaction gas raw materials are first dispersed through the liquid retaining cap 54 at the upper end, and then enter from the top inclined opening of the downcomer 53, thereby preventing the gas from directly entering the distribution pipe through the conical cap structure design of the liquid retaining cap 54. Holes of the same diameter are opened on both sides of each distribution pipe to ensure that the gas flow rate and flow rate are uniform. After distribution, the gas is discharged from the bottom to the next layer of catalyst section, and the final product is discharged outward through the discharge pipe 3.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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 orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0034] In this utility model, unless otherwise expressly specified or limited, terms such as "disposed," "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; they may refer to mechanical connection, direct connection, or indirect connection through an intermediate medium; they may refer to internal communication between two elements or interaction between two elements. Those skilled in the art will be able to understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0035] The control method of the present invention is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by technicians in this field. The provision of power is also common knowledge in this field. In addition, the present invention is mainly used to protect mechanical devices, so the control method and circuit connection are no longer explained in detail in the present invention.

[0036] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the present invention can make equivalent replacements or changes based on the technical solution and utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fixed bed reactor for methylamine synthesis, comprising a reactor body (1), characterized in that: The top of the reactor body (1) is connected to a mixed raw material inlet pipe (2), and a primary distributor (4) is provided at the bottom of the mixed raw material inlet pipe (2); the bottom of the reactor body (1) is connected to a discharge pipe (3); a plurality of reaction chambers are sequentially arranged from top to bottom in the reactor body (1), and a material pipe (8) is connected between the upper and lower reaction chambers. A redistributor (5) and a catalyst packing layer (6) are provided in the reaction chamber, and the redistributor (5) is located above the catalyst packing layer (6); A first refrigerant inlet (9) is provided on one side of the material pipe (8), and a first heat medium outlet (10) is provided on the other side.

2. A fixed-bed reactor for methylamine synthesis according to claim 1, characterized in that: The primary distributor (4) includes an annular nozzle (41), and a plurality of nozzles (42) are distributed in an annular manner at the bottom of the annular nozzle (41). The mixed raw material inlet pipe (2) is connected to the annular nozzle (41) via a connecting pipe (43).

3. The fixed-bed reactor for methylamine synthesis according to claim 1, characterized in that: The redistributor (5) comprises a downcomer (53), a liquid blocking cap (54) is provided on the top of the downcomer (53), and the top of the downcomer (53) is in the shape of an inclined opening.

4. A fixed-bed reactor for methylamine synthesis according to claim 3, characterized in that: The downcomer (53) is fixed by a bottom plate (51), and weir plates (52) are provided around the bottom plate (51), and the weir plates (52) are fixed to the inner wall of the reaction chamber.

5. The fixed-bed reactor for methylamine synthesis according to claim 1, characterized in that: The outer wall of the reaction chamber is provided with a jacket (7), and the bottom side of the jacket (7) is connected to a second refrigerant inlet (11), and the upper side is connected to a second heat medium outlet (12).

6. The fixed-bed reactor for methylamine synthesis according to claim 1, characterized in that: The upper end of the catalyst packing layer (6) is connected to a loading port (13), and the bottom end is connected to a discharge port (14).

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