Cogeneration Plants - Energy Conversion and Management - page 144

Fig. 9.5 Plant combined cycle cogeneration steam system
• Table 9.3 shows typical values of turbine and overall efficiency and ASR
coefficient for a range of unit sizes of backpressure and condensing turbines.
Small single-valve, single-stage units have low efficiency, less than 50 %.
The multivalve, multistage units may reach an efficiency of up to 80 % in
large power plants; in consequence, the greater the efficiency, the greater the
electric power generated with the same steam flow. A proper sizing of the prime
mover to meet process requirements is the first step in the optimization of a
cogeneration plant;