When a gas turbine is operated on low calorific value (LCV) gas instead of natural gas, the operating point of the compressor will shift towards the surge line. The compressor pressure ratio can rise to a level where stall or surge can occur. Premixing LCV gas with air inside the compressor of a gas turbine can solve this problem. With all fuel premixed, no fuel needs to be injected through the normal fuel inlet. The mass flow balance between turbine and compressor is restored and matching problems will not occur. From calculations with two LCV gases it could be concluded that all LCV gas could be premixed with compressor air when a low percentage of hydrogen gas was present in the LCV gas. The LCV gas could not be fully premixed in case of a high amount of hydrogen. The calculations show that an OPRA OD 500 gas turbine operated on premixed LCV gas with a low amount of hydrogen can maintain its original efficiency and a loss of 14 efficiency points can be prevented.

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