What Is Your Flare Philosophy? – Impacts on Digester Gas System Design

The current focus on energy has resulted in a significantly increased the interest in the design, construction, and operation of digester gas utilization systems. As evaluated in a recent Water Environment Research Foundation (WERF) study, there are many impediments to the successful implementation of a digester gas system (WERF, 2012). Of course, one major factor is the cost 1 effectiveness of the system. The potentially costly systems such as engine/generators, heat recovery from an engine (combined heat and power or CHP), digester gas cleaning, and other gas handling and management systems require careful planning and design. A major philosophical decision must be made by utility managers, treatment plant operators, and their engineers, namely, “What is your flare philosophy?” The answer to this question can drive the construction and operating costs, cost effectiveness, and environmental benefit of the digester gas utilization system. Three case studies are presented where the application of statistical gas production data was used to assist in the selection of the engine/generator size and associated gas handling systems.