Adiabatic fixed bed reactor and reaction method

Abstract

The invention discloses an adiabatic fixed bed reactor and a reaction method. A catalyst bed layer of the reactor is divided into two parts, namely an upper catalyst bed layer and a lower catalyst bedlayer, and an interlayer gap area is arranged between the upper catalyst bed layer and the lower catalyst bed layer; a hydrogen distribution pipe is arranged at the upper part of the interlayer gap area, the hydrogen distribution pipe comprises a main pipe and a plurality of branch pipes, and the branch pipes are perpendicular to the main pipe and are communicated with the main pipe; and hydrogenoutlets are uniformly formed in the downward or obliquely downward pipe walls of the branch pipes, and the main pipe is connected with a hydrogen distribution pipeline outside the reactor. A hydrogendistributor is added into the interlayer gap area between the upper catalyst bed layer and the lower catalyst bed layer of the reactor to supplement hydrogen, the hydrogen distribution points of thehydrogen distributor are distributed in parallel in the horizontal radial direction, gas-liquid materials and hydrogen are effectively mixed secondarily, and the hydrogenation efficiency of the catalyst on the lower middle portion of the reactor is improved.

Description

technical field [0001] The invention relates to the technical field of reactors, in particular to a fixed-bed hydrogenation reactor which adopts a double-layer catalyst and a secondary hydrogen distribution design in the middle of the reactor, saves the total amount of hydrogen and improves selectivity, and its application. Background technique [0002] After steam cracking and separation of liquid hydrocarbon raw materials such as naphtha, the C3 fraction contains propylene, propane, and a small amount of propyne and propadiene (abbreviated as MAPD). The content of MAPD is about 1% to 5% (volume) . In propylene polymerization, MAPD will reduce the activity of polypropylene catalyst and affect the quality of polymerization grade propylene products. In order to remove MAPD from the C3 fraction, catalytic selective hydrogenation and solvent absorption are currently used in industry to remove MAPD. Due to the simple process of catalytic hydrogenation and no environmental poll...

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Problems solved by technology

[0009] The use of a gas-liquid distributor can improve the initial uniformity of the gas-liquid two-phase distribution in the upper part of the catalyst bed in the reactor. However, with the expansion of the device scale, the diameter and height of the reactor continue to increase, and it is difficult for the gas-liquid to reach the middle of the catalyst bed. The lower part also forms a uniform distribution, and the gasification rate of the material near the central area is high. The surface of the catalyst particles is dominated by gas-solid reaction, and the adsorption and desorption rate is much faster than that of the surrounding area. The hydrogenation rate of propylene in the C3 reaction is much higher than that of MAPD. In contrast, the selectivity of the central area is lower than that of the surrounding areas.

Considering that C3 liquid-phase hydrogenation is a refining reaction, MAPD needs to be removed to the ppm level. In order to ensure that the hydrogenation of MAPD in the surrounding area is qualified, the selectivity of propylene in the central area will be greatly lost. Therefore, in actual industrial operation, the obtained propylene The selectivities were all well below the expectations of the catalyst design

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