Alternate residual oil hydrotreatment-catalytic cracking combined process method and system

Abstract

The invention discloses an alternate fixed bed residual oil hydrotreatment method and system. The method comprises a hydrogenation pretreatment reaction zone, a hydrogenation treatment reaction zone and a catalytic cracking reaction zone; the hydrogenation pretreatment reaction zone comprises a first hydrogenation pretreatment reactor, a second hydrogenation pretreatment reactor and a third hydrogenation pretreatment reactor; the first hydrogenation pretreatment reactor and the second hydrogenation pretreatment reactor are connected in series to serve as an online hydrogenation pretreatment reactor; and when the pressure drop in the first hydrogenation pretreatment reactor rises to the pressure drop design upper limit or the catalyst activity is lower than the requirement, the first hydrogenation pretreatment reactor is cut out, and switching is performed according to the following sequence: the second hydrogenation pretreatment reactor and the third hydrogenation pretreatment reactorare connected in parallel, the third and the first hydrogenation pretreatment reactors are connected in parallel, and the first hydrogenation pretreatment reactor and the second hydrogenation pretreatment reactor are connected in series. The method can realize long operation time without shutdown, ensures reasonable and limited alternate times, improves the utilization efficiency of the hydrotreating main catalyst and the operation stability of the device, and greatly prolongs the operation time and the working efficiency of the hydrotreating reactor.

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. 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 and high ...

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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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