Gas turbine efficiency and ramp rate improvement through compressed air injection

Abstract

With the transition to more use of renewable forms of energy in Europe, grid instability that is linked to the intermittency in power generation is a concern, and thus, the fast response of on-demand power systems like gas turbines has become more important. This study focuses on the injection of compressed air to facilitate the improvement in the ramp-up rate of a heavy-duty gas turbine. The steady-state analysis of compressed airflow injection at part-load and full load indicates power augmentation of up to 25%, without infringing on the surge margin. The surge margin is also seen to be more limiting at part-load with maximum closing of the variable inlet guide vane than at high load with a maximum opening. Nevertheless, the percentage increase in the thermal efficiency of the former is slightly greater for the same amount of airflow injection. Part-load operations above 75% of power show higher thermal efficiencies with airflow injection when compared with other load variation approaches. The quasi-dynamic simulations performed using constant mass flow method show that the heavy-duty gas turbine ramp-up rate can be improved by 10% on average, for every 2% of compressor outlet airflow injected during ramp-up irrespective of the starting load. It also shows that the limitation of the ramp-up rate improvement is dominated by the rear stages and at lower variable inlet guide vane openings. The turbine entry temperature is found to be another restrictive factor at a high injection rate of up to 10%. However, the 2% injection rate is shown to be the safest, also offering considerable performance enhancements. It was also found that the ramp-up rate with air injection from the minimum environmental load to full load amounted to lower total fuel consumption than the design case.

Исследования Турбокомпрессоров С Общим Рабочим Колесом Для Применения В Двигателях И Энергоустановках

“…Для этого необходимо придерживаться определённых ограничений. В ряде работ рассматривают вопросы моделирования потока газа на входе в проточную часть компрессора [8,9] и способ повышения эффективности работы газовой турбины [10], однако в них не приводят рекомендаций по рациональному проектированию проточной части с периодичным режимом работы. Целью данной работы является исследование особенностей работы ТКО с двумя схемами движения потоков и развитие теории газодинамического расчёта их проточных частей для применения в двигателях и в энергетических установках.…”

Aeroderivative gas turbine back-up capability with compressed air injection

“…The impact of compressed air injection is now being examined more widely for power augmentation and ramp-up rates improvement, within power generation. Injecting compressed air into a gas turbine engine provides additional mass flow for power augmentation [8,9,10,11] in steady-state and can be used to improve the transient ramp rate performance [8,12]. For augmentation, Coriolano S. [13] examines the augmentation benefit of combining a small CAES system in two configurations.…”

“…The article theoretically proves ramp rate improvements, from the storage system integration, without adverse combustion temperature changes. Abudu et al [8] investigate a similar case with compressed air injection for a HD engine. The study concentrates on quantifying ramp rate improvements realized from air injection at varying rates for a HD engine.…”

Impact of gas turbine flexibility improvements on combined cycle gas turbine performance

“…Other works include that of Kim et al [11] and Abudu et al [12] that directly address ramp rate improvements. Kim et al [11] focus on the integration of a GT (in standalone and combined cycle) with a compressed air energy storage (CAES) system to improve the ramp-up.…”

“…The injection schedule was also optimized to minimize the deviation of turbine inlet temperature from the design ramp-up. Abudu et al [12] relate the varied amount of air injected with the improvement of the ramp-up rate. The study also considers two ramp-up strategies:…”