Emissions and performance of a spark-ignition gas engine generator operating with hydrogen-rich syngas, methane and biogas blends for application in southern Brazilian rice industries

Brazil is one of the world's largest rice producers with more than 50 industries in this field. During the processing of the grain, high amounts of husk are generated, with a capacity to produce synthesis gas with high hydrogen content. On the other hand, in the process of parboiling, the final result is considerable volumes of effluent rich in organic matter, generating high amounts of methane. Therefore, spark ignition engine (SI) can operate with biogas, syngas or biogas-syngas mixtures, taking advantage of the bioenergy potential of the rice industries in Brazil. Accordingly, in this work, it was used the spark-ignition engine test operating with typical biogas and syngas compositions generated in the rice industries, named Bio70, syngas1 and syngas2, respectively. An important result could be observed. For both methane and biogas fuel the increase in excess ratio (λ) value from 1 to 1.25 lead to lower CO and NOx emissions as well as an increase in indicated efficiency. Using fuel mix, even at low concentration, such as 10% by vol., Bio70 provided increases in the calorific value of air-fuel mixture (edv) equal to 5.4 and 13.2% for syngas 1 and 2, respectively.