Study On Thermal Extraction Of Coal And Hydrogenation Liquefaction Behavior Of Extract

Direct coal liquefaction (DCL) is a strategic technology to relieve the shortage of oil and to ensure the energy security in China. Lignite and sub-bituminous coal and other low rank coals accounts for more than 40% in China's coal resources, and are considered as the suitable feedstock for coal liquefaction. The existing DCL technology requirements for coal are low ash, low inertinite group and low oxygen content. The existence of ash not only reduces the reactor's handling ability but also brings about such as the equipment wear, plug problems and so on. In addition, the ash will carry away approximately equal amount of liquefaction oil, reducing total oil yield of coal liquefaction. Therefore how to reduce ash content of low rank coal becomes the focus of attention.In order to promote DCL technology in China, basic research of DCL is very necessary. The "863" project" Study on thermal extraction of coal and coal hydrogenation liquefaction" has been approved,this thesis is an important part of the project.Thermal extraction of Shengli(SL) lignite was performed on extraction apparatus mainly using coal liquefaction recycle solvent as extraction solvent, and the effect of extraction conditions on the extraction yield was investigated. Deoxidation reaction of coal accompanying the extraction and the direct liquefaction performance of extracts were also studied. The extraction yield of SL lignite increased with temperature from 18.7% at 340℃to 59.5% at 430℃. However, the solid extract obtained from the used appratus reach the maximal value 32.4%daf at 390℃. The suitable extraction time and solvent to coal ratio was 60min and 5:1 respectively. Oxygen-reduction reaction was induced by the high temperature during the extraction process releasing carbon monoxide and carbon dioxide, and 23.0%daf oxygen of coal were released at 390℃. Results of direct liquefaction show that the extract of SL lignite gives much higher conversion and oil yield but consumes less H₂, produces less gas and water than SL lignite at the same condition.Because of the best liquefaction behavior of the extract ,this paper put forward a imagine which is to combine the thermal extraction of coal and direct coal liquefaction to form a new DCL technics...