Pot gas heat recovery and emission control

Abstract

Substantial quantities of heat is released to the ambient through pot exhaust, and present pot gas temperature of 150-180°C also affect the operation of the Gas Treatment Centres (GTC). Standard polyester filter bags used in the GTC can only sustain gas temperatures of 135°C. A sharp rise in fluoride emissions (HF) is seen as pot gas temperatures exceed 100°C. Dilution of the pot gas with ambient air is used to achieve acceptable GTC gas temperatures (110-115°C) and emission levels. This results in a need for substantial increase in the filtration capacity of the GTC. A heat exchanger has been developed to combine heat recovery and cost efficient cooling of pot gas. The technology has been tested on pot gas in a pilot plant. Promising stable heat exchange and pressure drop, and minimum fouling deposits over longer test periods have encouraged Alstom to continue the development into a commercial product.