Production of Clean Fuel by Solvent Skimming of Coal at Low Temperature

为了开发煤转化为几乎不含矿物质和硫化合物的清洁燃料的方法，采用流动式反应器对煤的低温溶剂撇除进行了研究。在350℃、10 MPa条件下，用四氢萘和煤衍生油、石炭油和杂酚油对20种煤进行了萃取，在350℃下，以四氢萘为溶剂，烟煤的萃取率达65 ~ 80%，提取物在室温下分离成约25 - 40%的可溶部分（可溶）和约40%的固体在室温下沉淀（存款）。石炭酸油对低煤阶煤和烟煤都有较好的萃取效果，从褐煤Morwell到次烟煤Miike的萃取率均超过70%，几种煤的萃取物几乎不含矿物质。用四氢萘作溶剂时，煤中的硫大部分保留在残渣中，而用石油作溶剂时，煤中的硫包括黄铁矿硫在内的大部分转移到可溶性组分中。石油中的极性化合物被认为与黄铁矿硫反应，将其转化为可溶性化合物。发现回收含有可溶性级分的溶剂可有效地增加存款的产率并显著降低提取物中的矿物质含量。在10次提取循环后，存款的矿物质含量令人惊讶地降低到低于0.02wt%。因此，所提出的萃取方法的有效性，生产大量的清洁燃料从煤在相当温和的条件下。

To develop methods for converting the coals to the clean fuels which are almost free from mineral matter and sulfur compounds, Solvent skimming of coal at low temperature using a flow-type reactor was examined. Twenty kinds of coals were subjected to the extraction by tetralin and coal derived oils, carbol oil and creosote oil, at 350℃ and 10MPa.The extract yield reached 65 to 80% for bituminous coals at 350℃ when tetralin was used as the solvent, and the extract was separated into about 25 to 40% of soluble fraction at room temperature (soluble) and about 40% of solid precipitated at room temperature (deposit). Carbol oil was effective to extract low rank coals as well as bituminous coals and the extraction yield exceeded 70% for the coals ranging from a brown coal, Morwell, to a sub bituminous coal, Miike.The extracts obtained from several coals were found to be almost free from mineral matters. Most of sulfur in coal was retained in the residue through the extraction when tetralin was used as the solvent, whereas most of sulfur including pyritic sulfur was transferred into the soluble fraction when the carbol oil was used. Polar compounds in the carbol oil were judged to react with the pyritic sulfur to convert it into a soluble compound. Recycling the solvent containing the soluble fraction was found to be effective to increase the yield of deposit and to decrease the mineral matter content in the extract dramatically. The mineral matter content of the deposit was surprisingly reduced below 0.02wt% after 10 extraction cycles. Thus, the validity of the proposed extraction method was presented for producing a large amount of clean fuels from coals under rather mild conditions.