Recently, the coal-to-oil synthesis project led by Zhang Feiyue, the chief engineer of the Ningxia Coal Industry Co., Ltd. (“Ningxia Coal” for short), with an annual coal indirect liquefaction capacity of 4 million tons, has been honored with the title of "National Outstanding Engineering Team."
Coal liquefaction technology essentially transforms coal into oil products. “There are 2 kinds of technology, the direct liquefaction and indirect liquefaction. The 4-million-ton coal-to-oil project adopts indirect liquefaction technology," Zhang Feiyue said, explaining that such oil products have characteristics such as low sulfur and low aromatic hydrocarbons, making them highly environmentally friendly. China is abundant in coal, deficient in oil, and lacks natural gas. For many years, coal has consistently accounted for about 70% of primary energy consumption. China's dependence on imported oil has exceeded 70% for four consecutive years, posing the greatest constraint on national energy security.
Relying on the abundant and high-quality coal resources in Ningxia, the team of Ningxia Coal have pioneered the exploration of million-ton-level coal indirect liquefaction technology. However, at that time, this technology in China was still not mature. At a critical moment, Ningxia Coal decided boldly to adopt domestically owned proprietary technology and independently invest in the coal-to-oil project.
From the coking of gasifiers, short lifespan of burners, to poor stability of catalysts... each technical challenge was like a roadblock obstructing the team's path. In the Fischer–Tropsch synthesis process (a process of converting a mixture of carbon monoxide and hydrogen gases into liquid hydrocarbons or hydrocarbon compounds using a catalyst and appropriate conditions), a large amount of acidic water is produced, with high chemical oxygen demand (COD) and low pH, making it difficult to treat.
At the beginning, the team considered neutralization with limestone, followed by alcohol separation and membrane treatment. However, this approach was prohibitively expensive, operationally demanding, and raised doubts about whether the wastewater could meet standards in the future. The team consulted multiple water treatment companies and design institutes and eventually determined the process route. The catalytic process was regarded as the "black box" of modern chemical engineering. Previously, the industry had been led by the nose by foreign catalyst suppliers. To crack this mystery, technicians visited enterprises in Beijing, Hebei, Shandong, and other places, borrowing equipment and laboratories, conducting experiments during the wee hours when others rested. "The first generation of Fischer–Tropsch synthesis catalysts were crushed upon entering the reactor, not only with poor stability but also contaminating the product." Recalling the initial situation, Li Hu, director of the Coal Chemical Industry Technology Research Institute of Ning Coal, still vividly remembers. However, the team did not lose heart. After nearly a thousand tests, when a catalyst with characteristics of high oil and wax production and high abrasion resistance was developed, everyone couldn't help but cheer with joy.
For years, with full support from the Science and Technology Department of Ningxia, the team collaborated with 29 domestic enterprises and research institutes, embarking on the path of domestication of 37 major equipment items. After 39 months of construction, good news came in 2016. In October of that year, the project produced qualified methanol, light oil, heavy oil, and qualified wax in December, and qualified diesel on December 21.
The team pioneered the construction of the world's largest single-unit 4 million tons/year high-temperature slurry bed Fischer–Tropsch synthesis unit, introduced a series of single-nozzle dry coal powder pressurized gasification technology with a daily coal injection rate of 2,000–3,000 tons, broke through the 100,000-ton level complete air separation technology, and developed replicable and scalable coal indirect liquefaction complete technology.
Currently, the project's overall domestication rate reaches 98.5%, with oil chemical product output exceeding 4 million tons annually since 2021. By the end of 2023, the unit has operated safely for over 1,300 days, achieving safe, stable, and clean operation. It has also driven a large number of domestic equipment manufacturing enterprises to enter the ranks of international first-class companies.
"Our current important task is to further extend the chain, reinforce the chain, and focus on the development of high-end oil products and high-end chemical products to enhance product added value," Zhang Feiyue said.
