Coal-to-liquids (CTL) technology company Clean Coal Technology (CCT) has been awarded the exclusive worldwide commercialisation rights of a newly developed technology for the deep gas purification process of synthesis gas (syngas), which can be based on coal, coke, heavy oil, residual oil or natural gas.
The deep gas purification technology has the advantage of lower capital investment, as well as lower running costs for a CTL plant. The lifespan of costly catalysts, which is a significant part of the operational cost of a plant, can be extended by the process and can achieve savings through lowering the concentration levels of possible deactivators of catalysts.
CCT, which is registered in South Africa and a joint venture between South African and Chinese expertise, explains that the significant operational cost in a synthesis plant comprises replacement of catalysts when required. Normally, the lifespan of a methanol synthesis catalyst is two years and the life of a Fischer-Tropsch (FT) synthesis catalyst is between 8 months and 18 months.
The one-off charge of a methanol synthesis catalyst is usually from 100 t to 200 t and costs up to $3-million, while the one-off charge of an FT synthesis catalyst is 500 t to 1 000 t and costs up to $22-million. Therefore, it is important to prolong the lifespan of a synthesis catalyst to lower the running cost of a plant.
The invention is adaptable in that, depending on the syngas feedstock, such as coal, coke, heavy oil, residual oil or natural gas; the production process being used and the required product stream is a combination of the catalysts and agents being used in the technology. In general, deep hydrolysis catalysts and deep-fine desulphurisers must be used.
Depending on the demand, the deep purifica- tion technology can comprise up to three deep purification towers. The technology can be used in the plants of CTL, methanol, acetic acid, anhydride acetic acid and dimethyl carbonate to protect the expensive catalyst and precious metal catalyst or to ensure product quality.
Meanwhile, as previously reported in Mining Weekly, CCT also has the exclusive rights to market and commercialise technology based on a novel FT process, developed by engineers at the University of the Witwatersrand, in Johannesburg.
The reaction is used to produce syncrude and other chemicals from syngas and can be applied to CTL, gas-to-liquids and waste-gas-to-liquids, as well as a new combined feed process. The technology offers reduced carbon dioxide (CO2) emission, reduced capital and operating costs, as well as simplicity of operation.
CCT technical consultant Ray Swanepoel says that CCT’s technology allows the small-scale construction of CTL plants, which have a distinctive configuration in that they do not use oxygen.
CCT states that the key novelty of the process is the system’s one-pass design. The elimination of the recycle phase improves the operability of the process and removes the requirement for certain items of equipment that are key to the operation of a recycle-based system. The removal of these items reduces the operating costs and, as a result, has a significant positive impact on the profitability of the process.
In particular, the new process design permits the elimination of upstream air separation for gasification, reformers for the recycle of methane from the tail gas, as well as the eradication of the requirement for complex and expensive gas separation for the recycle process.
The company has established a pilot plant in China’s north-west coal-mining province of Shaanxi, which has been successfully operated for more than 18 months and approved for commercial development by the provincial government.
“CCT’s technology is designed for smaller-scale resources, which offer various oppor- tunities, as it is difficult to raise funding for large plants in the current financial envi- ronment. Mining companies would rather build smaller, modular plants for less capital and in half the time,” says CCT executive director Dr Lin Tu.
Benefits of the technology include reduced capital and increased operational efficiencies, which are achieved by designing an innovative process with higher carbon efficiency, resulting in lower CO2 emissions, as well as reduced water consumption.
Swanepoel concludes that the response to CCT’s technology has been positive, especially from the international industry. The company plans to carry out continuous improvement in its processing systems and will focus on researching and marketing its technologies worldwide.