ENK5-2000-00335 Biomass/Waste FBC with Inorganics Control - BIFIC

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Summary Information



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EESD (Energy, Environment and Sustainable Development)

Proposal No:	ENK5-2002-00623
Date Prepared:	February 2004
Source:	European Bio-Energy Projects (EUR 20808)

Introduction

The primary objective of the project is to establish the feasibility of using high calorific residual mass streams, i.e. waste, biomass and possible combinations, as fuel in fluidised bed combustion (FBC) installations with minimal strain on the environment. Experimental and modelling studies are incorporated in the approach as well as commercial scale validation.

There is a clear need to broaden the range of fuels for energy generation. Present technology in many regions in Europe appears insufficient to meet near future targets for reducing the quantity of fossil fuels used and meeting new stricter legislation. Legislation no longer permits landfill of high calorific waste streams in many regions in the European Union.

Use of biomass waste mixtures as fuel can be more cost-effective or even profitable because of the lower price of waste fuel than that of clean biomass.

Activities

The use of high calorific residue streams for energy generation is not expected to be without problems so identifying these is the first step before determining the specific research aims. The BIFIC project addresses, in general, the:

• Contribution to the reduction of greenhouse gas emissions, strain on the environment, and of wasteland filling;
• Contribution to a wide enforcement of biomass to energy conversion systems by improving cost-effectiveness and competitiveness. This is supposed to be done by co-firing waste materials;
• Evaluation and optimisation of the process, operability and environmental performance of biomass/waste fired FBC plant, addressing the key issues of selected biomass and waste fuels;
• Application and validation of results at the medium and commercial scale;
• Modelling and simulation for the formation of fouling type deposits and heat transfer, which is a key issue of biomass/waste FBC;
• Development of guidelines and recommendations for the reliable operation of commercial systems based on the selected fuels;
• Identification of ash utilisation options;
• Control of the emission of polluting elements over FBC installations;
• Development of specific methods of planning and optimising logistic processes for these FBC systems; and
• Development and provision of a software tool for planning and optimising logistic processes for FBC systems.

Results

During the first two years of the project, a number of experimental screenings of fuels, bed materials, additives and parameters at small, medium and commercial scale were carried out. A programme of work was achieved using 30 kW, 350 kW, 750 kW, 3 MW, 25 MW and 80 MW FBC reactors, which comprised several tests in which grass, meat and bone meal (MBM), raw material feedstock (RMF), oil cuttings, shredded tyres, demolition wood, clean pellets of waste wood and sewage sludge were combusted either as a single fuel or as a combined fuel in varying proportions.

An extensive analysis has been written on the fuels, bed materials, additives and their combinations within this project. It indicates some of the potential problematic combinations which can be avoided completely. Further, it serves as a basis, in combination with analyses performed on ash, bed materials, deposits and other samples from partner installations, for identifying and addressing new problematic elemental combinations encountered in lab-to-fullscale installations, to be avoided in the future.

The comprehensive mathematical model for the simulation of particle laden gas flow through tube banks and calculations of heat transfer/losses due to deposit build-up will be developed. This model takes the distribution of mineral matter in fuel and the combustion environment that significantly influences the transformation of these mineral matters, in combination with experimental data for the rates of volatile minerals species vaporisation and reactions. It consists of sub-models for the release of the volatile mineral species from the host particles, mineral matter transformation, particle dispersion, particles deposition on the tube walls and heat transfer tubes.

As regards the optimised logistics for waste FBC:

• a detailed market analysis within the project countries (Sweden, Great Britain, Netherlands and Germany) for the selected fuels (sewage sludge, demolition wood, straw, poultry litter, meat and bone meal and waste tyres) has been conducted.
• data necessary to characterise the actual state and the structure of these markets have been collected. Important rules and requirements have been derived from the structural analysis and formulated in mathematical terms.
• an appropriate function has been developed to evaluate different decisions concerning the logistic processes within the system. As a result, a whole mathematical model has been developed to describe the system and its interactions and to decide upon its optimisation concerning the key factor energy costs.

Expected impact

The results obtained from the project will be valuable for a comprehensive understanding of the waste combustion process as regards operability, emission and bed ash utilisation. The commercial-scale waste incinerator operators can learn important information from the results on the combustion of biomass/waste and mixtures. The R&D results from the project will contribute towards the planning, design and operation of existing and future biomass/wastebased FBC plants.

The result can also be used in planning how to supply and cover the demand of the most inexpensive fuel or fuels for mixture and how to design and operate the unit in a very cost-efficient way.

The project delivers valuable reports, guidelines, recommendations and a software tool on logistics. Several restraining factors for a successful, cost-effective and efficient utilisation of biomass/waste in heat and power production are addressed. Solutions for such barriers would effectively clear a path through to a potential market in the area of small- to large-scale FBC systems.

The co-firing of wastes instead of clean biomass as stand-alone fuel makes energy production from biomass considerably more cost-effective. Small and medium enterprises, as well as boiler manufacturers, will have the possibility to use the project deliverables in order to build and operate biomass/waste FBC systems offering improved competitiveness.