Combined hydro-conversion method of coal tar distillate with different boiling ranges

Abstract

The invention relates to a combined hydro-conversion method of coal tar distillate with different boiling ranges, wherein, the first hydrocarbon distillate containing coal tar naphtha latent distillate completes conversion in the first hydrogenation part; the effluent of the first hydrogenation and the second hydrocarbon distillate containing coal tar diesel oil latent distillate complete conversion in the second hydrogenation part; the effluent of the second hydrogenation is separated and the product is recycled. In the invention, combined hydro-conversion is carried out on the coal tar distillate with different boiling ranges to form more agreeable hydrogenation temperature arrangement. The invention has the advantages of improving product quality, operating stably, prolonging the operational cycle and the like, thus particularly suitable for small-scale classified combined hydro-conversion of low temperature coal tar light distillate.

Description

technical field [0001] The invention relates to a method for combined hydrogenation conversion of coal tar fractions with different boiling ranges, which is particularly suitable for small-scale classified combined hydrogenation conversion of light fractions of low-temperature coal tar. Background technique [0002] It is well known that the initial coal tar from coal pyrolysis or coal gas production or other processes, if the coal tar suitable for hydroconversion contains different boiling range fractions (such as naphtha fraction, diesel fraction, heavy fraction), The properties (such as hydrogen content, density, viscosity, residual carbon content, metal content, oxygen content, sulfur content, nitrogen content, aromatics content, coke content, asphaltene content, boiling point) of different boiling range fractions are very different. When they are hydroconverted to produce clean oil, the reaction process, reaction pressure and temperature conditions, catalyst configurati...

AI Technical Summary

Problems solved by technology

[0003] ①Because the content of reactive substances such as oxygen-containing phenols and small molecular unsaturated hydrocarbons in the coal tar naphtha fraction is much higher than that in the coal tar diesel fraction, the coal tar naphtha fraction needs Start the reaction at a lower temperature to prevent the local temperature rise of the catalyst bed from being too large; but at a lower reaction temperature, it is difficult for the diesel fraction to react (including hydrogenation saturation reaction), which will dilute the naphtha fraction , reducing the concentration of reactants and increasing the amount of hydrodeoxygenating agent;

[0004] ②The coal tar naphtha fraction needs to start to react at a lower temperature, but at a lower reaction temperature, it is difficult for the diesel fraction to react (including hydrogenation saturation reaction), and at the same time, a thermal condensation reaction is formed in the catalyst bed. Or coking time conditions, speed up the catalyst coking speed;

[0006] ④Because of the "cracking" effect of the coal tar hydrofining process, the naphtha fraction is "cracked" during the hydrofining process of the diesel fraction, but the time for "cracking" to produce smaller molecules is inconsistent, and the hydrofining process of smaller molecules The time is also long and short, and the refining effect is inconsistent. If the hydrofining effect of the smaller molecules produced by "cracking" is guaranteed, that is, more stringent hydrofining conditions are selected, and the other fractions will be excessively hydrogenated, reducing the liquid yield. Or reduce product quality, and increase hydrogen consumption and catalyst consumption;

[0007] ⑤Industrial experience shows that there is a certain layering phenomenon in the storage tank of the mixed oil of naphtha fraction and diesel fraction. Although the forced circulation in the tank is used to achieve homogenization, the problem of unstable properties of the mixed coal tar is difficult. Complete elimination, which will lead to unstable raw material properties of whole fraction or wide fraction coal tar hydrogenation unit, unstable hydrogenation reaction operation, and unstable operation of the separated part of hydrogenation reaction effluent

There is no report on the method of separating the initial coal tar to obtain coal tar fractions with different boiling ranges and combined hydroprocessing