Evaluation of a Micro Gas Turbine Fed by Blends of Biomass Producer Gas and Natural Gas

Small scale gasification is a promising technology for bioenergy generation. Reciprocating engines are usually combined with downdraft gasifiers, nevertheless this approach is associated with high emissions, in particular CO and NOx and with a limited co-generation potential. MGT technology, rapidly improved during the last years, offers the possibility to reduce the levels of pollutants in the exhaust. Moreover they offer some other advantages in the small size range, such as a higher exhaust gas flow at higher temperatures, while maintaining a similar net electric efficiency. Evaluating the possibility to couple a MGT with a gasifier, the quality of the producer gas is also a relevant issue. In this work an overview of the typical gas quality produced by existing small scale gasifiers is carried out; moreover, a review regarding the syngas combustion in GT is realized, considering GT requirements related to gas composition. Co-firing with natural gas is considered, in order to reduce the modification needed to the engine. An evaluation of the proper range of mixing is then carried out. The performances of a commercial 100 kWel MGT are then simulated by means of an “in-house” developed code named AMOS (Advanced MGT system Operation Simulator). This tool allows to perform a steady-state matching analysis based on the characteristic lines of each component, when using a low calorific gas in a MGT. Producer gas and natural gas mixtures are considered and a parametric study is carried out. Performances were computed considering MGT full-load operation.Copyright © 2008 by ASME