THERMODYNAMIC MODELING AND ASSESSMENT OF ALLAM CYCLE UTILIZING NATURAL GAS
A thermodynamic modeling approach has been applied to natural gas-fired Allam cycle which ensures near zero emission while maintaining high cycle efficiency. Each component of the cycle has been modeled separately. Influence of inlet and outlet temperature and pressure of turbine on the efficiency of the cycle has been analyzed. Along with efficiency, recycled flow rate of the cycle also changes with the change of different
parameters. Increasing turbine inlet temperature and pressure ratio results in decreased recycle flow rate. Effect of each parameter on cycle efficiency was examined while keeping other parameters constant at a base value. At an inlet temperature of around 1650 K, maximum efficiency was found 58.9% with a turbine pressure ratio 10 when outlet pressure was 30 bar alongside ASU outlet pressure and temperature difference at recuperator hot end 3 bar and 10 K respectively. Consumption of power by different component of the cycle has been determined at this efficiency to find out the most energy-requiring part of the cycle. 13 % of the produced power was utilized to run the oxygen plant while 21% power was consumed for compression of recycled flow. Extra heat was required in the recuperator to maintain the desired temperature difference at the hot end. This heat was supplied from the ASU. High efficiency of this single turbine supercritical CO2 cycle confirms exceptional performance of Allam cycle. Moreover, no added cost for carbon dioxide capture in this high efficiency cycle makes it an attractive option for environment friendly power generation.