1. Sources

The present Combustion File is part of the cluster of CFs produced within the literature survey phase of the industrial sponsored research and development project PowerFlam1 and is confidential to the participants registered for that project.

This CF is specifically concerned with the research project:

Spliethoff, H., Scheurer W. & Hein, K.R.G. (2000): Effect of co-combustion of sewage sludge and biomass on emissions and heavy metals behaviour, which is published within The Journal of Trans IChemE, Vol.78, Part B, January.

Earlier version of this paper can also be found in 2^nd Int. Symposium on Incineration and Flue Gas Treatment Technologies. Sheffield University, UK, 4-6 July, 1999.

2. Background

·         This combustion file is concerned with the provision of combustion related data to the sponsors.

·         In this html file the source of the data is summarised in section 4 below, in order to give the reader a general overview of the way the data was collected.

·         Fuel and related data, prepared for calculation, are presented in individual Microsoft Excel Worksheets, all contained within a Workbook.

·         Please note that in some cases, the worksheet tabs within a workbook are not all visible without scrolling horizontally.

·         This workbook can be down-loaded by the reader and saved to her/his hard disk.

·         To achieve this click on the “xls” icon on the left hand side of the banner above. The file will be retrieved from the server, and with up-to-date versions of the browser, will appear in a separate window, from which it may be saved to the user’s hard disk.

·         The data in these worksheets are protected – thus the reader cannot change the worksheet without knowledge of the protection password.

·         However the reader can copy and paste the data into his/her own project work book as required – at this point the accuracy and integrity of the data becomes the responsibility of the reader. Included in this workbook are copies of the abstract and synopsis for reference purposes.

·         All credits and sources, and where necessary, instructions/advice for data use, are presented in this html file. These are not necessarily reproduced in the Excel Work Sheets.

3. Abstract

Extensive investigation on co-combustion were carried out using a 0.5 MW pulverised-coal fuelled experimental furnace with fuel preparation, accompanied by tests on an electrically heated tube reactor. The following additional fuels were utilised within the framework of various projects: biomass such as wood and straw and sewage sludge.

The question in focus in the case of the solid feedstock was at first the necessary fuel preparation. The outcome was that biomass (e.g. straw or wood) compared with coal allows a clearly coarser milling due to its higher content of volatile matter. Where the particles have to be < 1 mm for wood, for straw they may be coarser in order to completely combust.

Regarding the combustion behaviour, the major part beside the volatile matter content is on the side of the utilised grain size. The delayed ignition of coal/biomass blends could be manifested through measurements in the flame. In the case of sewage sludge, the fine milling and the high content of volatile matter resulted in an accelerated combustion process.

Co-combustion also had an effect on the emission ´behaviour. Owing to their high volatile matter content, sewage sludge, straw, and wood are suited for application in air and fuel staging with a view to nitrogen abatement.

Besides the emission and the combustion behaviour, the factors to be taken into account in co-combustion are the operational behaviour (slagging, fouling, corrosion) and the quality of the by-products.

4. Synopsis