A combined hydrocracking method for processing inferior raw materials

Abstract

The invention discloses a combined hydrocracking method used for processing inferior raw materials. According to the combined hydrocracking method, counter current hydrogenation technology is adopted for pre-treatment of high-nitrogen raw oil, and parallel hydrogenation technology is adopted for pre-treatment of common raw oil; a liquid obtained via counter current hydrogenation and an effluent of parallel hydrogenation are delivered into a hydrocracking reactor for reaction; an effluent of hydrocracking is mixed with gas obtained via counter current hydrogenation; and gas-liquid separation is carried, and an obtained liquid product is subjected to fractionation so as to obtain a hydrocracking product. The liquid obtained via the pre-treatment of high-nitrogen raw oil contains almost no ammonia, so that the liquid is mixed with the effluent obtained via hydrogenation of common raw oil, and a mixture is subjected to hydrocracking, influences of ammonia partial pressure on hydrocracking are reduced, and apparatus running period is prolonged; and at the same time, an ammonium salt is obtained via combination of NH3 in an ammonia-containing gas with hydrogen sulfide, is washed via water injection, so that amine liquid consumption of a recycle hydrogen desulfurization tower is reduced greatly, and operation cost is reduced.

Description

technical field [0001] The invention relates to a hydrocracking process, which mainly refers to the staged processing of different types of raw materials, including countercurrent hydrogenation and cocurrent hydrogenation, especially for the combined hydrocracking of inferior high-nitrogen raw material oil and conventional raw material oil. method. Background technique [0002] Hydrocracking technology is one of the high-quality heavy oil lightening technologies. It has many advantages such as strong adaptability of raw materials, flexible product solutions, high yield of liquid products, and good product quality. increasing trend. As one of the main processes for deep processing of heavy oil, hydrocracking can not only directly produce clean motor fuels such as gasoline, coal, and diesel, but also light and heavy naphtha and hydrocracking tail oil in its products are high-quality chemical raw materials. Therefore, In recent years, hydrocracking technology has gradually de...

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Problems solved by technology

[0004] At present, due to the need to process high-sulfur raw materials in the hydrocracking units of most oil refineries, a hydrogen desulfurization tower will be added to the high-pressure gas circuit. The operation of this tower can effectively reduce the concentration of hydrogen sulfide in the circulating hydrogen and reduce the Corrosion of key equipment such as compressors, increase of partial pressure of hydrogen in the reaction system, etc., but will increase the primary investment of the device, and will continue to consume lean amine liquid during the operation of the device, which will inevitably lead to a decrease in total revenue

However, there are also some enterprises that process low-quality raw materials with low sulfur and high nitrogen. Due to the existence of excessive ammonia partial pressure, the activity of molecular sieve catalysts is virtually reduced, which affects the operating cycle of the device. At the same time, in order to ensure the stability of its activity. Uninterrupted sulfur injection treatment will not only pollute the environment, but also increase the overall investment of the device

[0005] CN1962829 has introduced the production method of clean oil product, but operation is comparatively complicated

CN101455933 introduces the tower top purification device and purification method of the circulating hydrogen desulfurization tower, but they all belong to follow-up operations, and the investment is relatively large, and the problem of large consumption of lean amine solution in the circulating hydrogen desulfurization tower cannot be solved at present

CN1940030A introduces a method for hydrocracking of high-nitrogen feedstock to produce more diesel oil. Although the influence of ammonia partial pressure on the cracking section can be removed, an additional flash tank is required, and at the same time, only a single unit is modified, which is not fully developed. Reasonable use of complementary performance between devices

However, the nitrogen content of the processed raw materials is still low, and it is impossible to predict whether the working conditions of raw materials with higher nitrogen content are feasible

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