Effect of Pressure Drop Due to Grate-Bed Resistance on the Performance of a Downdraft Gasifier
2011 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 11, 5366-5377 p.Article in journal (Refereed) Published
The grate-bed resistance coefficient appears to be an important operating parameter having a strong influence on the overall performance during downdraft fixed-bed gasification- it affects, directly, the velocity profile, temperature distribution, and height of the bed. To date no information on the pressure drop due to the grate-bed resistance has been found. The objective of this paper is to propose a correlation that can predict the total effectof pressure drop (caused by bed resistance and grate-bed resistance), through a grate of a certain surface porosity (open area/total area) covered by the porous bed. The term related to the grate-bed resistance is based on the effective grate porosity, which combined surface bed porosity with geometrical criteria of the grate. Based on this a new term has been integrated into the Ergun’s equation. The prediction has been validated within the experimental work conducted on a 0.7MW downdraft fixed-bed gasifier fueled with wood pellets. In this study, three grates of different porosities and thicknesses have been tested using various operating conditions. The predicted values of pressure drop showed a good agreement within the experimental results with ±7.10% of uncertainty. Although, the lower grate porosity, the higher conversion of fuel and heating value of gas is produced, the stability of the process is disturbed; therefore the grate porosity reduction below 20% is not recommended.
Place, publisher, year, edition, pages
2011. Vol. 25, no 11, 5366-5377 p.
Pressure drop, downdraft gasifier, fixed bed, grate resistance
IdentifiersURN: urn:nbn:se:kth:diva-34416DOI: 10.1021/ef201246cISI: 000297001400049ScopusID: 2-s2.0-81555213086OAI: oai:DiVA.org:kth-34416DiVA: diva2:421082
QC 201112122011-06-072011-06-072011-12-12Bibliographically approved