Hitachi, Ltd. and Babcock-Hitachi Kabushiki Kaisha

Hiroshi Kagabu

Akira Kato

Fumito Nakajima

Shinpei Matsuda

Shigeo Uno

Youichi Sakuta

Ammonia is added to combustion flue gas containing nitrogen and sulfur oxides and the gas is brought into contact with a catalyst which contains titanium or tin oxide, or a mixture of the two, as a main component at a temperature between 150 .about. 330.degree. C. Nitrogen oxides are reduced to nitrogen and water, and sulfur oxides are deposited as ammonium sulfates, on the surface of the catalyst which causes a decrease in the ability of the catalyst. A part of the catalyst is removed continuously or intermittently from a catalyst bed and fed to a regeneration tower where it is treated with a hot gas having a temperature of 350 .about. 600.degree. C. The ammonium sulfates deposited on the catalyst are decomposed into SO.sub.3 and NH.sub.3. The SO.sub.3 is adsorbed by an SO.sub.3 absorbent and the NH.sub.3 is returned to the combustion flue gas to be treated.

Growing community of inventors

Tokyo, Japan

Hiroshi Kagabu