Experimental and modeling investigation of an integrated biomass gasifier-engine-generator system for power generation and waste heat recovery

This paper presents a combined experimental and modeling investigation on an integrated gasifier-engine-generator system. Both power and waste heat output of the system are studied. Other than the similar investigations in the existed literatures, the instant interaction between the internal combustion engine and the gasifier is considered. Meanwhile, waste heat from both syngas and exhaust gas is recovered to heat biomass feedstock. Two types of commercialized woody biomass, redwood pellets and woodchips, are used as the feedstock, respectively. An integrated model is established and experiments are performed to acquire parameters and relations for modeling, as well as to validate the model. Experiment results show that in most cases, the deviations of major elements, C and O, between input and output of the system are below 15%. The deviations of total mass are lower than 10%. For all experimental conditions, the highest cold gas efficiency (eta(cg))/power generation efficiency is 75.0%/16.4% and 80.8%/19.0%, respectively, for redwood pellets and woodchips. Results of model validation show that the accuracy of the developed model is acceptable. Standard deviations (SDs) of syngas compositions and eta(cg) are all below 10%. The maximum SD of waste heat is 12.81%. According to the evaluation results based on the developed model, energy loss during the gasification process takes up the largest proportion among all energy loss items. For all evaluated conditions, the combined energy of electricity and waste heat account for 43.0-54.6% and 40.0-60.4% of the total energy input when using redwood pellets and woodchips, respectively. The methods and findings can serve as basis and reference for combined cooling, heating, and power systems based on biomass gasification.