Best practice guide for handling of coal/biomass blends for co-firing in coal power plants

Handling of biomass as well as coal/biomass blends in existing and new power stations brings with it many issues that need to be addressed technically. There is a very rapid development of biomass capability especially within UK and Europe. It is expected that biomass co-firing will continue to expand in the immediate future, although this will depend on many factors such as government policies, availability of suitable biomass, capital investment in biomass co-firing capabilities and power generation efficiency. This paper looks at addressing the identified major issues and then recommending best practice for biomass co-firing in coal fired power plants, which can be useful to personnel, engineers on plant and for wider research purposes in existing or new co-firing installations. When handling biomass the major issues that were identified were one of moisture content affecting handling, and the other of dust generation [1]. The extent of moisture content being a problem varies from biomass to biomass depending on the particle size and nature of the material [2]. Regarding dust emissions, some biomasses have large amounts of fines hence can generate a considerable amount of dust emission themselves; however they also increase the propensity of the coal to emit dust. As far as existing systems are concerned most of the coal fired power plants that are co-firing biomass with coal are using a direct co-firing method in which the biomass material is mixed with the coal by co-milling or pre mixing process at a suitable stage within the power plants. For a new system greater changes can be brought about which will help in better handling of biomass with the knowledge that has been generated from co-firing experiences as well as handling measurements. This paper looks at best practice for existing handling systems as well as new systems also issues common to both.