Lignite staged liquefaction technology is worth paying attention to
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In terms of global oil and gas resources and consumption, the world is still in an oil and gas era. Our country’s energy and chemical industry development strategy, which focuses on petrochemicals with coal chemicals as a supplement, must not be shaken. Recently, in response to the issue of the large abundance of lignite in the country, some scholars have proposed first carrying out low-temperature coking of lignite to obtain tar, which is then hydrogenated to produce oil products. The remaining semi-coke is subjected to appropriate gasification to yield syngas, which can be further processed into oil products. Mixing these two types of products can result in more optimal finished oils. This allows for maximum coal-to-oil production, improves the efficiency of coal-to-oil conversion, and makes it possible to achieve a higher energy utilization efficiency in this process – and this is what graded liquefaction technology is. The staged liquefaction technique converts the hydrogen-rich portion of coal that is easy to liquefy into oil under mild conditions (400–450°C, 5–8 MPa). The carbon-rich residue remaining after extraction is gasified and then processed into syngas, which can be used for heating, power generation, hydrogen production, or the synthesis of diesel. Under these conditions, coal is utilized fully, the energy conversion efficiency is high, and economic benefits are good. Meanwhile, the operation process is simple, safe, and stable; the degree of domestic production of the equipment is high, and the investment required is low. Although there are still many difficulties in implementing the technology for the fractional liquefaction of lignite, the main issue is that advances are needed in the gasification of semi-coke, and the overall process setup requires a more rational design. It is undeniable, however, that this technology represents a highly promising new route for coal-to-oil production, and it will have a significant impact on China’s coal-to-oil industry.
The staged liquefaction technology for coal seems promising. However, the production process has become longer, and this extension of the production process means increased environmental pollution. Deep processing technologies for environmentally friendly coal development need to be considered comprehensively.
From a practical standpoint, it makes some sense, but there are many steps involved, the process is lengthy, energy consumption and losses are higher, and the investment required is also greater. This is common sense; I hope the original poster can conduct a more detailed calculation and make comparisons, as that would seem more convincing.