Biomass Fired Superheater for Decreased Corrosion Speed and Improved Power Yield

Abstract

This paper describes the principle and test results of a new design for combining a traditional steam cycle power plant fuelled by municipal refuse with a pyrolysis unit for biomass e.g. straw.

The electricity gain from the traditional plant is limited by steam data of 380–430^°C at 40–45 bar. Above this temperature chlorides and fly ash in the fluegas will result in high-temperature corrosion.In this new concept a much less corrosive pyrolysis gas is used in a separate super-heater in order to increase the steam data above this limit. Hereby the specific power yield can be increased essentially. The degassed biomass is utilized in the furnace/boiler increasing the steamflow and hereby also increasing the electricity production further.

A 300 kW pilot plant has been tested with very positive results in respect to energy efficiency, reduction of corrosive matters in the fluegas and handling of the biomass.