Extending existing combined heat and power plants for synthetic natural gas production

In this work, integration of a synthetic natural gas (SNG) production process with an existing biomass CHP steam power cycle is investigated. The paper assesses two different biomass feedstock drying technologies-steam drying and low-temperature air drying-for the SNG process. Using pinch technology, different levels of thermal integration between the steam power cycle and the SNG process are evaluated. The base case cold gas efficiency for the SNG process is 69.4% based on the lower heating value of wet fuel. The isolated SNG-related electricity production is increased by a factor of 2.5 for the steam dryer alternative, and tenfold for the low-temperature air dryer when increasing the thermal integration. The cold gas efficiency is not affected by the changes. Based on an analysis of changes to turbine steam flow, the integration of SNG production with an existing steam power cycle is deemed technically feasible