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Alstom’s GT26 gas turbine can already handle shale gas and other variable fuels as internal calculations show that shale gas and LNG will be within the company’s hydrogen gas experience range. In Algeria, Alstom could prove the C2+ variation tolerance of its turbine by running the combustion chambers with 15 percent C2+. At the VGB Congress in Friedrichshafen, Germany held recently, Dr. Klaus Knapp, group head, combustor operations and emissions with Alstom, said a hydrogen content of up to 15 percent volume can be handled by the company’s GT26 turbines.
Hydrogen and natural gas show similar Wobbe Index values and so jet penetration, mixing and pressure drop are similar. Knapp said, “We get prepared for extreme cases of shale gas with lots of C2+ that may be 16-18 percent and go up to even 20 percent C2+. Even if we add hydrogen to gas not much happens to the Wobbe Index, even at 100 percent hydrogen.” Moreover,the gas composition must be known in order optimize the system. If NOX emissions are 15ppm, the composition must be known. For hydrogen it will have to be developed.
Handling variable fuel with GT26
Alstom has stepped up R&D efforts to prepare handling future increases in variable LNG with its GT26 gas turbine combustion systems. It is already meeting customer demands by supplying turbines capable of switching to variable fuel types and compositions similar to shale gas with its GT26 gas turbine which has a capacity of about 300 MW.
Hydrogen in natural gas increases the reactivity of the flame and tends to ‘flash back’ or create a flame flare within the combustion chamber. Such flash backs can cause increase in emissions. Alstom’s fleet of gas turbines and equipment is already used with a wide range of gas compositions. It has supplied GT26 gas turbine to clients in Thailand, Algeria, and Spain with variable gas compositions. The fleet includes machines that use diluted gas with a high nitrogen, engines that operate blast furnace gas, and also syngas from heavy oil and gasification.