System and method for producing mesophase pitch and oil products on the basis of hydrogenation of medium and low temperature coal tar

Abstract

The invention relates to a system and a method for producing mesophase pitch and oil products on the basis of hydrogenation of medium and low temperature coal tar. The method mainly includes the stepsof coal tar pretreatment, hydrogenation deasphalting of the coal tar, thermal condensation of heavy components to produce the mesophase pitch, and hydro-refining to light components to produce the oil products. The invention, for the first time, discloses the method, in which the medium and low temperature coal tar, which is low in condensation degree, is used as the raw material, and by modifying pretreatment process and using reasonable catalyst gradation to perform hydro-upgrading, small-molecular pitch is converted into colloid, and meanwhile ash is removed; after product fractionation, the mesophase pitch is produced by performing mixing thermal condensation to the heavy components and a crosslinker, wherein the light components are hydrogenated further to obtain qualified fuel oil products or special oil product. The method can produce high-quality mesophase pitch and oil products, and also allows flexible adjustment on raw material group composition and ash content of the mesophase pitch and quality of the oil products according to demands. The system and the method reduce production difficulty of the mesophase pitch and improve additional value and economical efficiency ofthe medium and low temperature coal tar.

Description

technical field [0001] The invention belongs to the technical field of coal tar deep processing, and in particular relates to a system and method for preparing mesophase pitch and oil products from medium-low temperature coal tar. Background technique [0002] Coal tar is a by-product of coking and pyrolysis. According to the temperature range, time and process of coking and pyrolysis, coal tar is divided into high-temperature coal tar, medium-temperature coal tar, and medium-low temperature coal tar. Due to the different reaction conditions, the properties of high-temperature coal tar and medium-low temperature coal tar are very different. [0003] High-temperature coal tar is a by-product of high-temperature coking, which accounts for 1-2% of coke production capacity. The coking temperature is above 900°C. The thermal condensation reaction is strong and the degree of condensation is high. High-temperature coal tar has a high density, and the density range is 1150-1220kg / m3...

AI Technical Summary

Problems solved by technology

However, the raw material high-temperature coal tar used in this method has high impurity content and high asphaltene content. Most of the metals do not exist in an ion state, but form compounds in a complex state, which cannot be effectively removed by washing, and most of the quinoline insolubles are less than Coke powder of 10 microns is difficult to remove by centrifugation. Therefore, water washing and centrifugation cannot ensure that the raw materials meet the conditions for hydrogenation feed, and cannot guarantee the stable operation of the catalyst.

At the same time, more than 50% of high-temperature coal tar is asphaltenes with a molecular weight greater than 2000. During the hydrogenation process, it is easy to condense and accumulate carbon to block the pores of the catalyst. The limited pores cannot accommodate a large amount of metals and impurities. Active metal oxides of refined catalysts are used The content of molybdenum or tungsten is 15-45%, the metal oxides of cobalt and nickel are 1.5-5%, the content of total metal oxides is more than 16%, the hydrogenation activity is very high, and the condensation and coking of impurities and asphaltenes will cause bed lamination The drop rises rapidly, and the device cannot run stably for a long time

In addition, this method puts the production of mesophase pitch and fuel oil in the same stage of hydrogenation production, which cannot produce mesophase pitch with high yield and low softening point and make the by-product oil meet the standard

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