CN206853643U - A kind of combined type fixed bed reactors - Google Patents

Abstract

The utility model provides a combined fixed bed reactor, which includes a shell, a feed port, a feed port, an upper adiabatic reaction bed, an isothermal reaction bed and a lower adiabatic reaction bed. The fixed bed reactor passes An adiabatic reaction bed is installed on the upper part of the isothermal reaction bed, so that the temperature of the catalyst bed can be raised rapidly to reach the temperature required for the reaction, and the utilization rate of the catalyst bed can be improved; in addition, the adiabatic reaction section can also effectively control the reaction temperature to improve the overall service life of the catalyst; the isothermal reaction bed is equipped with heat exchange tubes uniformly arranged along the axial direction of the isothermal reaction bed, this arrangement regularizes the gas flowing in the radial direction, making it appear The plug flow state avoids material back-mixing; at the same time, the lower adiabatic reaction bed can reduce the size of the reactor and the manufacturing cost.

Description

A combined fixed bed reactor

technical field

The utility model belongs to the field of design and manufacture of chemical equipment and chemical machinery, in particular to a combined fixed-bed reactor.

technical background

Fixed bed reactor, also known as packed bed reactor, is a reactor filled with solid catalyst or solid reactant to realize heterogeneous reaction process. The solids are usually in the form of granules with a particle size of 2 to 15 mm, and are piled up into a bed of a certain height (or thickness). The bed is still and the fluid reacts through the bed. Fixed bed reactors are mainly used to realize gas-solid phase catalytic reactions, such as ammonia synthesis towers, sulfur dioxide contact oxidizers and hydrocarbon steam reformers, etc., and are widely used in petroleum refining industry, inorganic chemical industry, organic chemical industry and other fields.

At present, the traditional fixed bed reactor mostly adopts the tubular fixed bed reactor, which has a large heat transfer area, high heat transfer efficiency, and easy to control the bed temperature of the catalyst, but the tubular reactor is more difficult to process , more materials are needed, the cost is higher, and the differential pressure of each tube is basically the same when the catalyst is loaded, so as to ensure that the flow rate and space velocity of the material in each tube are the same to obtain a better reaction effect. But in fact, for most reactions, as the reaction proceeds, the concentration of the reactants in the material gradually decreases, and the reaction speed gradually slows down, so the heat released by the reaction is also greatly reduced, and there is no need to continue to remove the heat of reaction, so The distribution of reaction heat along the axial direction in the tubular reactor is also uneven, and the requirements for removing heat in the axial direction are also different; in addition, the volume of the shell side of the tubular reactor is much larger than the volume of the tube side, so for the filling With the same volume of catalyst, the volume of shell and tube reactor is much larger than that of adiabatic reactor.

For this reason, Chinese patent document CN 102794138 A discloses a reactor for exothermic reaction, comprising a fixed bed section of tubes and an adiabatic fixed bed section, the fixed bed section of adiabatic type is located downstream of the fixed bed section of tubes , the two-stage catalyst loading volume ratio is (0.2-5): 1, and the above-mentioned reactor is provided with an adiabatic fixed bed section at the lower end of the tubular fixed bed, so that as the reaction proceeds, the concentration of the reactant decreases, and the heat released by the reaction When it is lowered, the material enters the adiabatic fixed-bed reaction, which can solve the problems of large volume of the tube-and-tube reactor, uneven distribution of reaction degree and different heat transfer requirements in the tube-and-tube reactor. However, due to the arrangement of the heat exchanger in the above-mentioned device, the temperature in the upper section of the catalyst bed is low, and the catalyst utilization rate in the upper section of the bed is not high, which is not conducive to the reaction in the isothermal section, resulting in defects such as low production capacity of the reactor and low conversion rate of raw materials. Therefore, how to improve the existing fixed-bed reactors for exothermic reactions to overcome the above-mentioned shortcomings is a technical problem to be solved urgently for those skilled in the art.

Utility model content

The utility model solves the defects of the existing fixed-bed reactors such as low catalyst utilization rate, low reactor production capacity and low conversion rate of raw materials, thereby providing a novel combined fixed-bed reactor.

The technical scheme that the utility model realizes above-mentioned purpose is:

A combined fixed-bed reactor, comprising: a shell, a feed inlet is set at the top of the shell, and a discharge port is set at the bottom of the shell;

The interior of the shell is divided from top to bottom into an upper adiabatic reaction bed, an isothermal reaction bed and a lower adiabatic reaction bed connected in sequence;

A heat exchange structure is arranged in the isothermal reaction bed layer, which includes several heat exchange tubes for filling the catalyst through the isothermal reaction bed layer in the axial direction, and the heat exchange tubes are arranged along the isothermal reaction bed The axial direction of the layer is evenly arranged, and the upper and lower ends of the heat exchange tubes are respectively provided with an upper tube plate and a lower tube plate, and the two ends of the heat exchange tubes are connected with the upper adiabatic reaction bed layer and the lower adiabatic reaction bed layer respectively. The layers are connected, and a heat exchange space for the circulation of the cooling medium is formed between the two adjacent heat exchange tubes, and between the heat exchange tubes and the shell;

A cooling medium inlet is provided on the housing corresponding to the end of the isothermal reaction bed, and a cooling medium outlet is provided on the housing corresponding to the beginning of the isothermal reaction bed.

The height ratio of the upper adiabatic reaction bed, the isothermal reaction bed and the lower adiabatic reaction bed is 1:(0.55-4.1):(0.35-2.0).

The catalyst loading volume ratio of the upper adiabatic reaction bed, the isothermal reaction bed and the lower adiabatic reaction bed is (25-55):(10-35):(20-40).

The height of the isothermal reaction bed is 1-6 meters.

It also includes a first gas mixing distributor, and the first gas mixing distributor communicates with the material inlet provided on the housing;

Air holes are arranged on the peripheral wall of the first gas mixing distributor, and the opening ratio of the first gas mixing distributor is greater than 50%.

It also includes a porous wall plate arranged on the upper part of the upper adiabatic reaction bed and the upper and lower ends of the lower adiabatic reaction bed, and the opening ratio of the porous wall plate is not more than 30%.

The pores of the porous wall plate have an opening size of 1-10mm.

A second gas mixing distributor is arranged between the isothermal reaction bed and the lower adiabatic reaction bed, and the opening ratio of the second gas mixing distributor is greater than 50%.

The combined fixed-bed reactor also includes thermocouples and online analyzers respectively arranged at the material outlets at the lower end of the upper adiabatic reaction bed, the isothermal reaction bed and the lower adiabatic reaction bed.

The online analyzer is a near-infrared detector.

The above-mentioned technical scheme of the utility model has the following advantages:

(1) In the combined fixed-bed reactor described in the utility model, the inside of the housing is separated from top to bottom into an upper adiabatic reaction bed, an isothermal reaction bed and a lower adiabatic reaction bed connected in sequence, Setting the upper adiabatic reaction bed on the upper part of the isothermal reaction bed can make the temperature of the catalyst bed rise rapidly, reach the temperature required for the reaction, improve the utilization rate of the catalyst bed, and then improve the production capacity of the reactor and the conversion rate of raw materials; in addition , because the upper adiabatic reaction bed can use its own reaction heat to raise to the optimum reaction temperature, thereby reducing the heat load of the combined reactor, saving energy, reducing the size and production cost of the combined reactor, and the adiabatic reaction bed The layer can also effectively control the reaction temperature and improve the overall service life of the catalyst. A heat exchange structure is arranged in the isothermal reaction bed, which includes several heat exchange tubes that penetrate the isothermal reaction bed in the axial direction, and the heat exchange tubes are uniformly arranged along the axial direction of the isothermal reaction bed. On the one hand, the method further regulates the gas flowing in the radial direction, making it in a plug flow state, avoiding the back-mixing of the reaction gas in the bed, and improving the reaction efficiency; on the other hand, the above-mentioned setting method has uniform heat transfer and high efficiency ; In addition, the isothermal reaction bed layer converts the heat of reaction into steam, so that the steam heat can be easily used for subsequent reactions, which is beneficial to reduce system energy consumption and avoid energy waste. At the same time, the lower adiabatic reaction bed layer can reduce the size of the reactor and the manufacturing cost.

In summary, the combined fixed-bed reactor described in the utility model has the advantages of uniform distribution of reaction gas, large production capacity, and high catalyst utilization rate by effectively combining the upper adiabatic reaction bed, isothermal reaction bed and lower adiabatic reaction bed. High efficiency, energy saving, small reactor size, low production cost and high conversion rate of raw materials.

(2) In the combined fixed bed reactor described in the utility model, by maintaining the height ratio of the upper adiabatic reaction bed, the isothermal reaction bed and the lower adiabatic reaction bed at 1: (0.55～4.1): (0.35 ～2.0), simultaneously control the catalyst loading volume ratio of the upper adiabatic reaction bed, isothermal reaction bed and lower adiabatic reaction bed at (25～55):(10～35):(20～40) Within the range, thus making the conversion rate of the material reach the highest when passing through the upper adiabatic reaction bed, the isothermal reaction bed and the lower adiabatic reaction bed respectively, which improves the production capacity of the reactor and at the same time minimizes the size of.

(3) In the combined fixed-bed reactor described in the utility model, the first gas mixing distributor communicates with the material inlet arranged on the housing, and the peripheral wall of the first gas mixing distributor is provided with air holes, so that The reaction gas can be evenly distributed, the gas deviation can be prevented, and the load of the catalyst bed in the axial direction of the reactor can be guaranteed to be consistent.

(4) In the combined fixed-bed reactor described in the utility model, since the heat exchange tubes in the isothermal reaction bed inevitably have a certain pressure difference in the process of loading catalyst, the pressure of each heat exchange tube The inconsistency of the material load causes the material at the outlet of the lower end of the isothermal reaction bed to be biased, thereby reducing the conversion rate of the reaction. By setting a second gas mixing distributor between the isothermal reaction bed and the lower adiabatic reaction bed, it can be The materials from the outlet at the lower end of the isothermal reaction bed are mixed evenly again, so as to increase the conversion rate of the reaction.

Description of drawings

Fig. 1 is the structural representation of the combined fixed-bed reactor that embodiment 1 provides;

Fig. 2 is A-A sectional view of Fig. 1;

Among them, the reference signs are as follows:

1-shell; 2-inlet; 3-outlet; 4-upper adiabatic reaction bed; 5-isothermal reaction bed; 6-lower adiabatic reaction bed; 7-heat exchange tube; 8-upper Tube sheet; 9-lower tube sheet; 10-first gas mixing distributor; 11-porous wall plate; 12-second gas mixing distributor; 13-cooling medium inlet; 14-cooling medium outlet.

detailed description

The technical solutions of the utility model will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are part of the embodiments of the utility model, but not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

In the description of the present utility model, it should be noted that the orientations or positional relationships indicated by the terms "inner", "outer", "upper" and "lower" are based on the orientations or positional relationships shown in the accompanying drawings, and are only In order to facilitate the description of the present invention and simplify the description, it does 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 thus should not be construed as limiting the present invention. In addition, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be fixed connection, detachable connection, or integral connection; it can be mechanical connection or electrical connection; it can be direct connection, It can also be indirectly connected through an intermediary, and it can be the internal communication of two elements. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

Example 1

As shown in Figure 1, the combined fixed-bed reactor described in this embodiment comprises:

Housing 1, a feed inlet 2 is provided on the top of the housing 1, and a discharge outlet 3 is provided at the bottom of the housing 1; the inside of the housing 1 is divided into sequentially connected from top to bottom The upper adiabatic reaction bed 4, the isothermal reaction bed 5 and the lower adiabatic reaction bed 6, the upper adiabatic reaction bed 4 is set on the top of the isothermal reaction bed 5 can make the temperature of the catalyst bed rise rapidly to reach the required level of reaction. temperature, improve the utilization rate of the catalyst bed, and then increase the production capacity of the reactor and the conversion rate of raw materials; in addition, because the upper adiabatic reaction bed 4 can use its own heat of reaction to increase to the optimum reaction temperature, thereby reducing the combined reactor. The heat load saves energy, reduces the combined reactor size and production cost, and at the same time, the adiabatic reaction bed can effectively control the reaction temperature and improve the overall service life of the catalyst.

Further, in the fixed bed reactor of this embodiment, a heat exchange structure is provided in the isothermal reaction bed 5, and the heat exchange structure includes heat exchange tubes 7 for filling the catalyst through the isothermal reaction bed 5 in the axial direction , the heat exchange tubes 7 are evenly arranged along the axial direction of the isothermal reaction bed 5. On the one hand, this arrangement further regulates the gas flowing in the radial direction, making it in a flat push flow state, and avoiding the reaction in the bed. The back mixing improves the reaction efficiency; on the other hand, the above-mentioned setting method has uniform heat transfer and high efficiency. The upper and lower ends of the heat exchange tubes 7 are respectively provided with an upper tube plate 8 and a lower tube plate 9, and the two ends are respectively connected with the upper adiabatic reaction bed 4 and the lower adiabatic reaction bed 6; in this embodiment, Between two adjacent heat exchange tubes 7, between the heat exchange tubes 7 and the shell 1, a heat exchange space for the circulation of the cooling medium is formed, and it is set on the shell 1 corresponding to the end of the isothermal reaction bed 5 The cooling medium inlet 13 is provided with a cooling medium outlet 14 on the housing corresponding to the beginning of the isothermal reaction bed layer 5. The cooling medium is saturated water, so that the saturated water passing through the isothermal reaction bed layer can be converted into steam, thereby The steam heat can be easily used for subsequent reactions, which is beneficial to reduce system energy consumption and avoid energy waste.

In the combined fixed-bed reactor described in this embodiment, the height ratio of the upper adiabatic reaction bed 4, the isothermal reaction bed 5 and the lower adiabatic reaction bed 6 is 1:2:1. In other embodiments, the upper The height ratio of the adiabatic reaction bed 4, the isothermal reaction bed 5 and the lower adiabatic reaction bed 6 can be any value within the range of 1: (0.55-4.1): (0.35-2.0); at the same time in this embodiment, The catalyst loading volume ratio of the upper adiabatic reaction bed 4, isothermal reaction bed 5 and lower adiabatic reaction bed 6 is 40:25:30. In other embodiments, the upper adiabatic reaction bed 4, isothermal reaction bed 5 and The catalyst loading volume ratio of the lower adiabatic reaction bed 6 can be any value within the range of (25-55): (10-35): (20-40); the height of the isothermal reaction bed in this embodiment is 5 meters , in other embodiments, the height of the isothermal reaction bed can be any value between 1 and 5 meters. In this embodiment, by controlling the height ratio of each bed in the reactor and the catalyst loading volume ratio, the materials are respectively passed through the upper adiabatic Reaction bed 4, isothermal reaction bed 5 and lower adiabatic reaction bed 6 have the highest conversion rates, thereby increasing reactor throughput while minimizing reactor size.

At the same time, the fixed bed reactor in this embodiment also includes a first gas mixing distributor 10, the first gas mixing distributor 10 communicates with the material inlet provided on the shell 1, and the surrounding wall is provided with Stomata, in the present embodiment, the opening ratio of the gas holes on the peripheral wall of the first gas mixing distributor 10 is 70%, in other embodiments, the opening ratio of the gas holes on the peripheral wall of the first gas mixing distributor 10 can be greater than 50%. %, so that the reaction gas can be evenly distributed, the gas bias flow can be prevented, and the load of the catalyst bed in each axial direction of the reactor can be guaranteed to be consistent.

Further, this embodiment also includes a porous wall plate 11 for fixing the upper adiabatic reaction bed 4 and the lower adiabatic reaction bed 6, which is located above and below the upper adiabatic reaction bed 4 and the lower adiabatic reaction bed 6 At both ends, in this embodiment, the opening rate of the porous wall plate 11 is 20%, in other embodiments, the opening rate of the porous wall plate 11 can be any value not greater than 30%; and the porous wall plate The opening size of the pores of 11 is 5mm, and in other embodiments, the opening size of the pores of the porous wall plate 15 can be any value between 1-10mm, so that the reaction gas and the catalyst have sufficient contact time, Improve catalytic efficiency.

In addition, the fixed bed reactor in this embodiment also includes a second gas mixing distributor 12 arranged between the isothermal reaction bed 5 and the lower adiabatic reaction bed 6, and the opening ratio of the second gas mixing distributor 12 is In other embodiments, the opening ratio of the second gas mixing distributor 12 can be any value greater than 50%, so that the material at the outlet at the lower end of the isothermal reaction bed can be mixed evenly again, thereby improving conversion rate of the reaction. In this embodiment, by setting the lower adiabatic reaction bed 6 at the lower part of the isothermal reaction bed 5, as the reaction proceeds, the concentration of the reactant decreases, and when the heat released by the reaction decreases, the material enters the lower adiabatic reaction bed The layer 6 reacts, thereby solving the problems of large volume of the tube-and-tube reactor in the isothermal reaction bed layer 5, uneven distribution of reaction degree and different heat transfer requirements in the tube-and-tube reactor.

The reactor provided in this embodiment also includes thermocouples and online analyzers respectively arranged at the material outlets at the lower end of the upper adiabatic reaction bed 4, the isothermal reaction bed 5, and the lower adiabatic reaction bed 6. In this embodiment, the on-line The analyzer is specifically a near-infrared detector, so that the temperature and material conversion rate of each reaction bed can be monitored at any time.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the scope of protection of the utility model.

Claims (10)

1. A combined fixed-bed reactor, comprising: a shell (1), a feed inlet (2) is set at the top of the shell (1), and a discharge is set at the bottom of the shell (1) Mouth (3); It is characterized in that, The interior of the housing (1) is divided from top to bottom into an upper adiabatic reaction bed (4), an isothermal reaction bed (5) and a lower adiabatic reaction bed (6) connected in sequence; A heat exchange structure is provided in the isothermal reaction bed (5), which includes several heat exchange tubes (7) for loading catalysts penetrating through the isothermal reaction bed (5) in the axial direction. The thermal tubes (7) are evenly arranged along the axial direction of the isothermal reaction bed (5), and the upper and lower ends of the heat exchange tubes (7) are respectively provided with an upper tube plate (8) and a lower tube plate ( 9), the two ends of the heat exchange tubes (7) are respectively connected with the upper adiabatic reaction bed (4) and the lower adiabatic reaction bed (6), and the two adjacent heat exchange tubes (7) Between the heat exchange tubes (7) and the shell (1), a heat exchange space for cooling medium circulation is formed; A cooling medium inlet (13) is provided on the housing (1) corresponding to the end of the isothermal reaction bed (5), and a cooling medium outlet is provided on the housing (1) corresponding to the beginning of the isothermal reaction bed (5). (14). 2. combined fixed-bed reactor according to claim 1, is characterized in that, described upper adiabatic reaction bed (4), described isothermal reaction bed (5) and described lower adiabatic reaction bed (6 ) has a height ratio of 1: (0.55-4.1): (0.35-2.0). 3. combined fixed-bed reactor according to claim 1 or 2, is characterized in that, described upper adiabatic reaction bed (4), described isothermal reaction bed (5) and described lower adiabatic reaction bed (6) The catalyst loading volume ratio is (25-55): (10-35): (20-40). 4. The combined fixed-bed reactor according to claim 3, characterized in that the height of the isothermal reaction bed is 1-6 meters. 5. combined type fixed-bed reactor according to claim 1,2 or 4, is characterized in that, It also includes a first gas mixing distributor (10), and the first gas mixing distributor (10) communicates with the material inlet provided on the housing (1); Air holes are arranged on the peripheral wall of the first gas mixing distributor (10), and the opening ratio of the first gas mixing distributor (10) is greater than 50%. 6. combined fixed bed reactor according to claim 5, is characterized in that, also comprises the upper end portion that is arranged on upper adiabatic reaction bed layer (4) and the upper and lower end portion of lower adiabatic reaction bed layer (6) A porous wall plate (11), and the opening ratio of the porous wall plate (11) is not greater than 30%. 7. The combined fixed-bed reactor according to claim 6, characterized in that the pores of the porous wall plate (11) have an opening size of 1-10 mm. 8. combined fixed-bed reactor according to claim 5 is characterized in that, the second gas mixing distributor (12) is set between the isothermal reaction bed (5) and the lower adiabatic reaction bed (6) ), and the opening ratio of the second gas mixing distributor (12) is greater than 50%. 9. combined fixed-bed reactor according to claim 8, is characterized in that, described combined fixed-bed reactor also comprises respectively being arranged on described upper adiabatic reaction bed (4), described isothermal reaction bed (5) and a thermocouple and an on-line analyzer at the material outlet at the lower end of the lower adiabatic reaction bed (6). 10. The combined fixed-bed reactor according to claim 9, wherein the on-line analyzer is a near-infrared detector.