Chemical Process Design and Integration. Robin Smith. Chapter 23 Exercise 6

6. The problem table cascade for a process is given in Table 23.11 below for ATmin = 30C. This process is to be integrated with a steam turbine in a cogeneration scheme. The a inlet steam is at 41 barg and 400C. a. The rate of power generation can be determined from the Willans' Line Model with parameters from Table 23.1 and intercept ratio of 0.05, assuming a mechanical efficiency of 95%. Calculate the power generation for a fully loaded turbine if the inlet steam flow to the turbine is fixed to satisfy process heating requirements. b. Calculate the heat duty of the fuel consumed in the generation of steam if the theoretical flame temperature in the boiler is 1800C and the ambient temperature is 15C. Table 23.11 Problem table cascade for Exercise 6. Interval temperature (C) Heat flow (MW) 15 20 20 21 11.5 400 400 170 115 115 100 100 80 80 50 50 12 0 1 17.5 18 5 c. The fuel consumption can be reduced by air preheat to the boiler by recovery of waste heat from the process. Calculate the fuel consumption and power generation if air preheat is maximized. Assume that the heat capacity flowrates of combustion air and flue gas are equal. Acid dew point for the flue gas is 150C. Table 23.1 Correlating parameters for steam turbines'. Back-pressure turbines Condensing turbines W 2000 kW max Wmax 2000 kW a (kW) 1.08 ATSAT 1.097 + 0.00172TSAT 4.23TSAT 1.155 +0.000538 ATSAT 0.662TSAT 1.191 +0.000759ATSAT -463 + 3.53ATSAT 1.220 + 0.000148 ATSAT b (-)