CONSEQUENCES OF RECENT GAS-TURBINE DEVELOPMENTS FOR INDUSTRIAL CHP APPLICATIONS

Developments in gas turbine (GT) technology have been considerable dur ing the last few years. In this paper, consequences regarding the tech nical performance for industrial combined heat and power applications are discussed and the most important design parameters are identified. Some GT types, which represent different stages of the developmental trend, are analysed in the simple and the combined cycle. Both the ind ustrial and the aero-derivative GT classes are included. Conclusions a re: (i) Generally, the developments have broadened the span of achieva ble power-to-heat ratios (alpha-values). Values between 0 and 1.5 are obtainable for different GT-based schemes with acceptable total effici encies. (ii) The total efficiencies achievable depend strongly, and di fferently for different GT types, on the nature of the heat demands in the industrial process. (iii) When opportunities do not exist to cool the exhaust gases in an economizer, i.e. when the stack temperature i s directly given by process heat demands, the total efficiency is inde pendent of the GT class. For both classes, however, the development ha s led to higher total efficiencies when the process temperature demand s are high. (iv) When opportunities exist to cool the exhaust gases in an economizer (which is often the case for the simple cycle and alway s for the combined cycle), the industrial GT developments have given i mproved ability to reach a high total efficiency. The new aero-derivat ive types, on the contrary, are worse than the conventional ones in th is respect. This can also lead to worse performance in combined cycles for the new aero-derivative types. (v) When supplementary firing is a pplied, however, the total efficiency is high and similar for all vari ous units and conditions. The 'new acro-derivative' units have, in tha t case, superior alpha-values-especially in the combined cycle.