Series alternate residual oil hydrotreatment-catalytic cracking combined process method and system

Abstract

The invention discloses a series alternate residual oil hydrotreatment-catalytic cracking combined process method and system. The method comprises the following steps: mixing a residual oil raw material and at least part of a catalytically cracked diesel fraction with hydrogen, allowing the obtained mixture to sequentially pass through a hydrogenation pretreatment zone and a hydrotreating reactionzone which are connected in series, carrying out gas-liquid separation on the reaction effluent of the hydrotreating reaction zone, and allowing the separated liquid phase to directly enter a catalytically cracked reaction zone to carry out a catalytic cracking reaction. The hydrogenation pretreatment reaction zone comprises N hydrogenation pretreatment reactors, the first hydrogenation pretreatment reactor to the N-1th hydrogenation pretreatment reactor are sequentially connected in series and are used as N1-stage online hydrogenation pretreatment reactors, and the Nth hydrogenation pretreatment reactor is used as an offline hydrogenation pretreatment reactor. According to the method and the system, the operation time of the hydrotreating pretreatment process is long without shutdown, the stable exertion of the overall catalytic activity of the hydrotreating main catalyst is facilitated, reasonable and limited alternating times are ensured, and the operation time and the working efficiency of the hydrotreating reactor are prolonged.

Description

technical field [0001] The invention relates to a residual oil hydrotreating-catalytic cracking combined process method and system, in particular to a residue oil hydrotreating-catalytic cracking combined process method and system which can be rotated in series. Background technique [0002] As crude oil becomes heavier and worse, more and more heavy oil and residual oil need to be processed. The main purpose of the residue oil hydrotreating process is to greatly reduce the content of impurities such as sulfur, nitrogen, and metals in the residue oil raw material through hydrogenation treatment, and to convert non-ideal components such as polycyclic aromatics, colloids, and asphaltenes through hydrogenation. Increase the hydrogen-to-carbon ratio, reduce the residual carbon content, and significantly improve the cracking performance. [0003] Fixed bed residual oil hydrogenation technology is a deep processing technology for heavy oil. Under the condition of high temperature...

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Problems solved by technology

However, after parallel and series operation, the method needs to stop and replace the catalysts of each hydrogenation pretreatment reactor, and requires a long shutdown time, and cannot continue hydrogenation of residual oil for a long time, thereby affecting the economic efficiency of the refinery; , the pressure drop of each hydrogenation pretreatment reactor is at the highest level in the late stage of operation, and it is also operated in series, which makes the total pressure drop of hydrogenation pretreatment very high. If the original operating conditions are maintained, it will affect the main The catalytic activity of the catalyst, this loss of catalytic activity is irreversible

In order to ensure the catalytic activity of the main catalyst, it is necessary to further increase the reaction severity of the front hydrogenation pretreatment and increase the reaction temperature to a greater extent, which will increase the load on the heating furnace. Sometimes the original design load may be too small to meet heating requirements

[0007] In the above residual oil hydrogenation process, when the fixed bed is filled with hydrogenation protecting agent and hydrodemetallization catalyst at the same time, if a lower proportion of hydrodemetallation agent is used, the hydrodemetallization performance of the entire catalyst system is insufficient, especially At the end of the operation, the metal-accommodating capacity is low, which leads to the rapid deactivation of the catalyst in the main reaction zone, which is not conducive to the long-term operation of the device; Insufficient scale and impurity capacity of the hydrogenation pretreatment reactor leads to a rapid rise in the pressure drop of the hydrogenation pretreatment reactor, shortens the normal operation time, and soon enters the end of operation, resulting in shutdown, which is also not conducive to the long-term operation of the device

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