INVESTIGATION OF DIFFERENT SURGE HANDLING STRATEGIES AND ITS IMPACT ON THE COGENERATION PERFORMANCE FOR A SINGLE-SHAFT GAS TURBINE OPERATING ON SYNGAS

The increasing demand for decentralized power has led to a growing interest in smaller gas turbines for cogeneration applications. One benefit of decentralized power generation is the possibility to utilize fuels that are locally available. One example is syngas, which has gained increasing interest during the recent years. Compared to natural gas the syngas fuels have a large amount of dilutants, such as nitrogen and carbon dioxide, which results in a very low energy density. Hence, significant larger fuel flow is required. However, "the added fuel flow will decrease the compressor surge margin and eventually drive the compressor towards surge. Several methods exist to address this issue including variable inlet guide vanes, increased turbine throat area, compressor bleeding and decreased combustor outlet temperature. This paper examines the operability of a generic all radial single-shaft gas turbine in the 2 MW power range when running on syngas with different heating values. The above methods to combat the decreased surge margin will be analyzed using detailed cycle simulations and their advantages and disadvantages will be discussed. It was found that the increased throat area is the most beneficial of the four methods. The net power output is nearly the same as for natural gas operation and the heat rate is the lowest of the four methods.