Question 12.8: An IGCC power plant is operating under the following conditi......
An IGCC power plant is operating under the following conditions:
• Electric capacity of the IGCC power plant P_{IGCC} is 180 MW
• Advanced combined cycle thermal efficiency \eta_{CC} is 0.59
• Efficiency of entrained flow oxygen-blown gasifier \eta_{gas} is 0.79
• Gas turbine combustor efficiency \eta_{comb} is 0.985
• Gas turbine efficiency \eta_{GT} is 0.39
• Fuel for gasifier: bituminous coal with LHV of 30 MJ/kg
• Electric generator efficiency \eta_{g} is 0.98
Calculate (i) the overall efficiency of the IGCC power plant, (ii) the rate of heat release in the gas turbine combustor, (iii) the plant fuel consumption rate, and (iv) the power outputs of the gas turbine and ST trains.
1. Overall efficiency of the IGCC power plant including gasifier with HGCU, gas turbine combustor, and combined cycle train with electric generator
\eta_{IGCC}=\eta_\mathrm{g as}\;\eta_\mathrm{c o m b}\;\eta_ \mathrm{CC}\;\eta_{\mathrm{g}}=0.79\times0.985\times0.59\times0.98=0.452. Rate of coal heat input to the gasifier
Q_{\mathrm{gas}}=P_{IGCC}/\eta_{IGCC}=180/0.45=400\;MJ/s3. Fuel consumption rate of the IGCC plant is
m_\mathrm{f}=Q_{\mathrm{gas}}/\mathrm{LHV}=400/30=13.33\mathrm{~kg/s}=48\mathrm{~t/h}4. Rate of heat input to the gas turbine combustor
Q_{\mathrm{GT}}=Q_{\mathrm{gas}}\;\eta_{\mathrm{gas}}\;\eta_{\mathrm{comb}}=400\times0.79\times0.985=311.26\; \mathrm{MW}5. Power output of the gas turbine train
P_{GT}=Q_{GT}\times\eta_{GT}=311.26\times0.39=121.4~{\mathrm M W}6. Power output of the ST train
P_{\mathrm{ST}}=P_{\mathrm{IGCC}}-P_{\mathrm{GT}}=180-121.4=58.6~\mathrm{M W}