Adding hydrogen to fuel gas to improve energy performance of gas-turbine plants

Abstract

The study aims to calculate the technical and economic efficiency of adding hydrogen to natural gas to improve the energy characteristic of the fuel in gas-turbine plants during long-term gas field operations. Mathematical modelling techniques in the CAS CFDPT (computer-aided system for computational fluid dynamics of power turbomachinery) program were used to develop a mathematical model of the General Electric 6FA gas turbine engine. It was shown that a decrease in the calorific value of the fuel leads to an increase in fuel consumption by 11% and the amount of CO2, NO2 in the turbine exhaust gas. It was determined that, during the freezing season and peak power rating operations, the turbine power is limited by the fuel system capacity (its maximum value amounted to 5.04 kg/s). It was shown that energy characteristics can be improved by adding hydrogen to the feed natural gas. Energy efficiency was calculated at different fuel components (hydrogen and natural gas) ratios at variable-load operation in the range between 75 and 85 MW. Instant fuel gas flow amounted to 5.04 kg/s (with 4.5% hydrogen and 95.5% natural gas in the feed fuel) at 85 MW. Due to its high cost, the use of hydrogen is only advisable in peak power rating operations to reach the maximum capacity of the gas-turbine plant. The proposed method of adding 4.5% hydrogen to fuel gas allows the maximum fuel consumption to be maintained at a rate of 5.04 kg/s to reach the topping power of 85 MW. When using this method, there are no limitations on the maximum and peak capacity of the gas-turbine plant.