Coal burns rapidly in a fluidized bed, even at 1500°F. Based on bed volume, the heat release is 300,000–400,000 Btu/(hr)(ft³). Counting the open furnace space above the bed the rate is 100,000–200,000 Btu/(hr)(ft³). Suppose that 200,000 Btu/(hr)(ft³) are generated in a 40 ft steam generator, that the water enters two sets of coils at 70°F, and that in the upper set of coils the water flow rate is 3,000 lb/hr leaving as steam at 900°F and 380 psia. If the steam leaving the lower coils is at 1200°F and 400 psia, what is the flow rate of the water into the lower set of coils?
400-380 = 20
= 300 × 20 × 40