Classen process

While corn yield per acre has a steadily increasing trajectory, there is a long-term interest in the use of hgnocellulosic biomass for the production of fuel ethanol. Acid-mediated depolymerization of saw dust (and other materials) into sugar was noted in 1819 by Braconnot [15, 16]. This acid-mediated hydrolysis and subsequent fermentation came to be known as the Classen process [17, 18], and by 1910 there were reports of economically successful production of ethanol from wood waste [19, 20]. But interest in these processes waned and they were largely forgotten, as evidenced by the fact that the 2013 opening of a facility... 

Lignum Inversion Company, Chicago (1903) Reports and Letters on the Classen Process of Producing Ethyl Alcohol, Charcoal, Etc from Sawdust and Wood Waste, Ryan Hart Company. 

A. C. Classen used sulfur dioxide as the hydrolytic agent, and experimental plants were built in France to determine the suitability of this process. In 1903 patent rights were sold to an American company, which built an experimental plant at Highland Park, Illinois. Later this company erected a plant at Hattiesburg, Mississippi, to operate on sawmill waste of longleaf pine. Because of mechanical difficulties and a failure to understand the principles involved, the plant closed. Another plant was built at Port Hadlock, Washington, which used the sulfur dioxide process, but it, too, failed after a short time. 

Classen-Houben, D., Sippl, W., Holtje, H.-D. Molecular Modeling on Ligand-Receptor Complexes of Protein-Tyrosine-Phosphatase IB. In EuroQSAR 2002 Designing Drugs and Crop Protectants Processes, Problems and Solutions, Ford, M., Livingstone, D., Dearden, J., Van de Waterbeemd, H. (eds), Black-well, Bournemouth, 2002. 

Classen, A. (1902) Process for Converting Cellulose into Sugar. US Patent 645,518. 

In the process, as operated by the Mitsubishi Petrochemical Company at Ifaeir Yokkaichi, Japan, complex, flue gas from a boiler burning 3 to 4% sulfur fuel oil is treated to remove 97% of the SC>2 (Classen, 1983 Kaneda et al., 1983). Flue gas from the air preheater is first blown into a precooler where a fine spray of recirculated water humidifies and cools the flue gas while removing particulate and other impurities such as chlorides. 

Classen, D. D., 1983, Status of the Chiyoda Thoroughbred 121 Flue Gas Desulfurization Process, Proceedings of Seminar on FGD sponsored by Canadian Electrical Association, Ottawa, Canada, Sept. 19-20. 

The next attempt to set up a workable scheme for processing wood was made by two chemical engineers who had been associated with Classen. 

It is instructive to consider some of the factors leading to the closing down of the Georgetown and Fullerton plants. In neither case was the shutdown caused by the inoperability of the process as was true of the Classen plant. These plants, operating on sawmill wastes, become useless if the waste has to be transported long distances. Lumber operations follow the forests and have to be moved periodically as timber is cut over. The same requirement applies to alcohol plants attached to lumbering operations. The rate of cutover was so rapid at the Fullerton plant sawmill that it forced a curtailment of operations, which with competition from the low cost molasses process eventually led to the closing of these plants. 

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