To combust recovered chemicals more efficiently, UBE Chemicals, Bangkok, has ordered a chemical recovery boiler.

UBE produces nylon from raw materials, and the production process releases chemicals that can be combusted. Helsinki-based Metso will provide a system that is based on its recovery boiler concept used in the pulp and paper industry. Metso will replace the entire pressure vessel with a newly designed incinerator situated within the existing structure. The current combustion process will be replaced with a complete solution in terms of recovery and end-combustion of chemicals, with a next summer startup scheduled.

“Metso has previously performed a similar replacement for UBE Chemicals in Spain when a new combustion plant for chemicals was installed with exceptional results,” says Watchara Pattananijnirudorn, UBE Thailand executive vice president.

The pressure-vessel concept will utilize burners at two levels where fuels are sprayed into the burning-chamber section of the boiler. Combustion air then is added in a three-level air system in which the air ports are equipped with automatic rodding devices for remote operation. The firing technique reduces the amount of sodium carbonate carryover in flue gases and heat is recovered in the heat-absorbing surfaces consisting of water screens, convection and economizer. The various heat absorption areas are cleaned by soot blowers. The smelt is discharged to the dissolving tank through the water-cooled smelt spout, and the spout is designed for automatic rodding by Metso’s DeckHand, an industrial type robot.