Biomass Diet to Make Old Coal Plant Fit Again

摘要

Switching from coal to renewable woody biomass is a low cost way for old coal stations to meet new EU environmental legislation with a low carbon solution, whilst extending the life of these valuable assets by 10 or more years. Lynemouth is a 3x140MWe coal fired power station dating from the 1970s. With no SOx or NOx controls and with the rising price of carbon it faced closure at the end of 2016. RWE Supply & Trading saw this site to have excellent potential for conversion to biomass to solve these life threatening problems and extend operations at the station given good core attributes of recently upgraded turbines and cold North Sea cooling for an excellent underlying efficiency. Doosan Babcock was engaged because of their extensive experience in biomass conversions over a 30 year period including the RWE Tilbury plant. Firstly Doosan Babcock considered the safety requirements for the use of wood fuel and incorporated the necessary design changes. Then they conducted an overall evaluation of the existing power station and modelled it with the pre-requisites of meeting full load on the biomass fuel, satisfying the pending environmental emissions legislation and operating at maximum efficiency. The model was used to identify and resolve any bottle-necks limiting full load operation on biomass and to meet the other pre-requisites. This resulted in the replacement of fans, a new low NOx combustion system with over-fire air and dynamic classifiers, a primary air cooler for efficiency, ash handling plant and an ESP upgrade. This paper describes the biomass conversion at the Lynemouth power station, and focusses on the work needed within the boiler house, the design process and resulting scheme together with the expected performance and project progress.