Gas and steam combined cycles for low calorific syngas fuels utilisation

Abstract

The utilisation of low-calorific syngas fuels in conventional gas turbines and gas and steam combined cycle equipments has been studied by the authors over the last years. In the present work, the effects of using different fuels of the referred type on the performance of a gas and steam combined cycle performance are assessed. The main bottle-necks found when trying to exploit the potential of the syngas fuels considered are also identified and some general rules with regard to the necessary modifications that need to be implemented in standard plants are provided.In continuation to this research line, the present work analyses the challenges that using syngas fuels have on the major equipment of a conventional combined cycle designed for natural gas operation. First, the most relevant constraints imposed by the new fuels onto the conventional power plant are identified. This leads to setting up a list of the bottle-necks that prevent the plant from fully exploiting the potential of the new fuels employed. A list of the necessary modifications of the existing pieces of equipment, selected according to their technical feasibility and economic viability, is developed accordingly. These design updates are then assessed by means of a performance analysis of the redesigned plant. The full analysis is based on commercial and in-house computer codes.The modifications proposed in this work can be regarded as general rules to redesign existing combined cycle power plants. The conclusions drawn from the paper permit to envisage the work that needs to be done if the present combined cycle plants are to be adapted to syngas fuels in a near future.