The low pressure drop across TORBED reactors is important because the volumes of gases to be processed are high at 200,000 nm3/h (117,500 acfm) per TORBED reactor and the particle size range that is used in the reactor is small and substantially un-graded. The TORBED reactor based scrubbing plant represents substantial savings in the capital and operating costs of an installation at a smelter.
Extensive pilot trials were completed to demonstrate the TORBED reactor application at 1000mm diameter scale with success in 1990/1. After construction of a 5000mm prototype in 1993, a 6000mm (20 ft) diameter two-stage reactor was installed and commissioned in early 1994. The results were sufficiently favourable that New Zealand Aluminium Smelters Ltd decided to proceed with an expenditure of NZ$94m (£30m) on a new scrubbing plant based on thirteen 6000mm (20 ft) diameter TORBED reactors. These were installed in 1995/6 and the plant is achieving the best world standards. A further 6 such units were commissioned at Comalco’s Bell Bay smelter in Tasmania in 1997.