The MTG in Jincheng, Shanxi, uses domestic gray pyrolysis gasification technology

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At the site of the coal-to-synthetic oil demonstration project in Jincheng, Shanxi, which is under the general contract of the Second Design Institute of the chemical industry, it can be seen that one set (comprising 6 units) of ash fusion fluidized bed pressurized gasification furnace equipment developed and manufactured in China has been installed, and the gas production facility has entered the critical phase of installation. The ash-melting fluidized-bed gasifier is used for coal-to-oil conversion, providing a solution for low-quality coal with high ash, sulfur, and calorific value content; it also marks the beginning of the adoption of such gasification technologies and equipment in China. The Shanxi Jincheng coal-to-synthetic oil project is a **pilot project** for indirect coal-to-oil conversion using high-sulfur, high-ash, and high-melting-point ’three-high’ low-quality coal to produce methanol-to-gasoline (MTG). It employs a ash fusion fluidized bed pressurized gasification process. This process was developed on the basis of traditional fluidized bed gasification technology. The new process retains the advantages of the original fluidized bed technology. A central jet pipe and annular pipes are designed at the bottom of the gasifier, creating local jet zones within the bed layer. A selective ash separation system is implemented; the high-concentration oxygen entering through the central jet pipe generates localized high temperatures, which cause the ash to agglomerate into balls that gradually grow larger and heavier. Eventually, these balls separate from the semi-coke in the bed layer and are discharged through the annular pipes. In this way, the bed layer can maintain a high concentration of carbon. After entering the gasifier, the raw coal mixes thoroughly with the gasification agents (steam, oxygen) to undergo reactions, during which processes such as viscosity reduction, removal of volatiles, gasification, agglomeration and separation of ash, as well as cracking of tar and phenols take place. The product gas contains no tar or volatile phenols. Compared with fluidized bed systems, this equipment has lower energy consumption and oxygen consumption, a simpler process flow, and simpler structures for the gasification furnace and associated equipment. Compared to introducing gasification technology, the investment is about 50% lower at the same scale. The Shanxi Coal Chemistry Institute of the Chinese Academy of Sciences used pilot and industrial demonstration units based on gray fusion fluidized beds to conduct multiple gasification tests on the ’high-carbon, high-hydrogen, high-sulfur’ coal from Jincheng. Good results were achieved in all aspects related to gasification, with a reasonable balance of conversion rates as well as efficient, economical, and environmentally friendly outcomes. The Jincheng coal-to-oil demonstration project uses 6 ash fusion fluidized-bed pressurized gasifiers (5 in operation and 1 as backup) to produce gas for methanol synthesis, which is then converted into 100,000 tons per year of commercial-grade gasoline. Practice has shown that the ash fusion fluidized bed is suitable for a wide range of coal types, features a simple gasifier structure, has low investment and maintenance costs, operates at moderate temperatures, and has low oxygen consumption; it is particularly suitable for the gasification of low-quality ’high ash, high sulfur, and high calorific value’ coals. It is understood that about 30% of the coal reserves in China’s western regions are ‘high-carbon, high-sulfur, and high-ash’ coal. Due to its high pollution from combustion and the inability to be used for direct liquefaction, ’high-carbon, high-sulfur, and high-ash’ coal has always been classified as a coal type whose mining is prohibited.