Method for extracting heavy liquefied oil and kerite substance from residue of direct coal liquefaction

Abstract

The invention provides a method for extracting heavy liquefied oil and kerite substances from residues of direct coal liquefaction. The method comprises steps of: a) adding coal residue powder and a first solvent into an extraction apparatus for extraction; b) carrying out solid-liquid separation on an extraction mixture and a raffinate from step a) by a first cyclone separator to obtain a liquid mixture and an underflow mixture; c) sending the underflow mixture from step b) and a second solvent to a re-extraction apparatus for re-extraction to obtain a mixture; d) carrying out a second solid-liquid separation on an extraction mixture and a raffinate from step c) by a second cyclone separator too obtain a liquid mixture and an underflow mixture; e) carrying out precise filtration on a clear liquid mixture from step b) and a re-extracting clear liquid mixture from step e) in a precision filtering device and sending a filtrate to a distillation separator; f) carrying out pressurizing coarse filtration on the underflow mixture from step d) and sending a filtrate part and a clear liquid mixture treated with precise filtration to a distillation separator; g) separating the extraction mixture in the distillation separator.

Description

technical field [0001] The invention relates to the field of coal deep processing, in particular to a method for solid-liquid separation and solvent recovery after extraction of coal liquefaction residue. Specifically, the invention provides a method for extracting heavy liquefied oil and bituminous substances from coal direct liquefaction residue. Background technique [0002] Direct coal liquefaction is an important supplement to the shortage of oil resources in my country, and is of great significance to my country's energy security. No matter which coal direct liquefaction process is adopted, such as IGOR + process, NEDOL process and Shenhua liquefaction process (ZL200410070249.6 and ZL200610090484.9), the conversion rate of coal cannot reach 100%, and there is always liquefaction residue by-products accounting for about 30% of the liquefaction coal input in the end. It is a high-carbon, high-ash and high-sulfur substance mainly composed of minerals in coal, catalysts,...

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Problems solved by technology

Patent JP2289684 and patent JP61276889 use gravity sedimentation method to separate the extraction mixture and raffinate, but the separation efficiency of this method is relatively low, the sedimentation equipment is relatively heavy, and the ash content of the final obtained extract is difficult to meet the requirement of less than 1%. The loss of extraction solvent is relatively large

Kerr-McGee (U.S. Patent No. 3,607,716, U.S. Patent No. 3,607,717) uses light aromatic hydrocarbon solvents such as toluene to extract the liquefaction residue under supercritical conditions. The solid-liquid separation still adopts the method of gravity sedimentation, although the process can obtain ash If the extraction product is less than 1%, the solvent recovery rate is relatively high, but the extraction temperature is relatively high at 325-340°C, and the pressure is relatively high at 5.0MPa. efficiency is not high

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