Methane Steam Reforming and Steam Injection for Repowering Combined Cycle Power Plants

Abstract

Repowering existing power plants represents a potential route to meet the increasing energy demand, in a context of more and more stringent environmental regulations, hindering the construction of new facilities. Conventionally, repowering is operated into existing steam power plants, thus allowing to increase the design capacity to such an extent that depends on the type of strategy to exploit the waste heat from the additional gas turbine. In this study a new repowering concept is proposed. It involves the integration of an additional unit based on a gas turbine into an existing combined cycle gas turbine (CCGT). Based on this concept, two repowering options are examined. In the first one (Option A), the waste heat from gas turbine flue gases is used to produce steam in a one pressure level steam generator. In the second option (Option B), the exhaust waste heat recovery promotes the generation of a synthesis gas in a methane steam reformer. The integration of the additional unit is operated by the injection of superheated steam (Option A) and the reformed fuel (Option B) into the combustor of the main power plant, thus allowing for a further increase in power output of both topping and bottoming cycles. The simulation study allows to compare the repowering options with respect to the potential increase of power capacity, as well as in terms of energy marginal performance parameters.