Cracked gas compression interstage selective hydrogenation method

Abstract

The invention discloses a cracked gas compression interstage selective hydrogenation method, belonging to the selective hydrogenation technical field. Aiming at reducing energy consumption and cocking of separation and hydrogenation flows in ethylene unit while reducing energy consumption and coking of cracked gas compressing machine stage and improving application universality and easy operationof the method, mixed phase hydrogenation reaction is carried out between stages of cracked gas compression machine, compressed condensate is taken as liquid phase material flow, hydrogenation is carried out under the presence of catalyst to reduce alkyne and dialkene content in cracked gas, and the material after hydrogenation is cooled and fed into the suction tank at a fourth compression stage.The method of the invention reduces high unsaturated hydrocarbon while consuming part of hydrogen, thus not only reducing energy consumption and coking amount of separation and hydrogenation flows but also reducing coking and energy consumption of compression stage. The method of the invention has wide application and can be used in various cracking separating flows.

Description

technical field [0001] The present invention relates to a method for the selective hydrogenation of alkynes and dienes, more specifically, the present invention relates to a method for the selective hydrogenation of alkynes and dienes in cracked gas from an olefin production unit. Background technique [0002] Unless otherwise specified, the highly unsaturated hydrocarbons mentioned in the present invention refer to hydrocarbons containing triple bonds or two double bonds. [0003] Processes for the conversion of hydrocarbons at high temperatures, such as steam thermal cracking or catalytic cracking, to provide unsaturated hydrocarbons such as ethylene, acetylene, propylene, butadiene, butene; saturated alkanes such as ethane, propane, butane; There are also light components such as methane, hydrogen and carbon monoxide and hydrocarbons with a boiling point in the gasoline range. The gas-phase monoolefins with more than two carbon atoms obtained by these processes also cont...

AI Technical Summary

Problems solved by technology

The shortcoming of this patent is: 1, because this patent application places the mixed-phase hydrogenation reactor on the downstream side of the front depropanizer, what enters the mixed-phase hydrogenation reactor is cooled and partially condensed rich in C 3 and lighter component streams, so this patented technology can only hydrogenate low-carbon alkynes in the mixed-phase hydrogenation reactor, and cannot hydrogenate high-carbon alkynes such as butyne and butadiene, so The amount of hydrogen consumed is limited, and a large amount of remaining hydrogen enters the cryogenic part of the cracked gas, resulting in high energy consumption

2. If the remaining high-carbon alkynes and dienes enter the polymerization process, the activity of the polymerization catalyst will be reduced, and the physical properties of the polymer will be deteriorated

3. Since the patent application does not carry out hydrotreating on the stream entering the front depropanizer, the alkynes and diolefins in the stream are likely to cause coking in the tower and increase energy consumption

4. Due to the use of this patent application technology, a series of additional equipment is required to separate the C 3 and C 3 The above components are additionally treated to remove alkynes and diolefins, thereby increasing equipment investment and production energy consumption as a whole

[0010] Throughout the prior art, whether it is CN1098709A and CN 1109090C, or other methods using catalytic reaction distillation such as CN1961059A and WO2006083336A2, selective hydrogenation is carried out in the cracking and separation process, and the starting point for consideration is to reduce the subsequent separation and hydrogenation process Factors such as energy consumption, coking, hydrogenation load, and equipment investment do not take into account the energy consumption and coking of the cracked gas compressor section.

In addition, CN1098709A and CN 1109090C are suitable for the separation process of front depropanization or front deethanization, not suitable for sequential separation process, etc., so their application has limitations

The method of catalytic reaction distillation still introduces easily polymerized dienes into the catalytic reaction rectification column, so there are more or less problems of diene polymerization that need to be overcome, and inevitably there are catalysts that are not easy to regenerate and operating requirements are relatively high. Disadvantages of height and limited means of adjustment

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