Sandvik steel belt cooling systems for China coal liquefaction project

London -- Sandvik has supplied 12 dedicated steel belt cooling systems for a direct coal liquefaction (DCL) process to the Shenhua Group, China’s largest coal producer. The cooling systems, each with a solidification capacity of 15 tonnes/hour, were delivered as part of a contract signed between the companies in 2006.

Shenhua’s DCL process produces a liquid residue at viscosities of approx.100 mPa-s and temperatures up to 310ºC. The residue is converted into solid flakes via a steel belt cooling system. The coal slurry is fed onto a continuously running, 1.5 m wide steel belt, which is cooled from beneath with sprayed water as it travels the length of the steel belt, from which it emerges as a uniform layer of solid fuel material.

Depending on the quality of the coal and the process parameters, the solidified product can show very different physical properties, from brittle to tough through to sticky. Therefore, different discharge and breaking devices are installed at the end of the steel belt before the product is discharged for storage.

Design of the units takes into account the very harsh climatic conditions of the site in Inner Mongolia. Here ambient temperatures can range from -30° C to + 40°C with the likelihood of heavy sandstorms. This challenge was further compounded by the requirement to install the systems in the open air, without any shelter.