7-11 7-29 A coal-burning power plant produces 300 MW of power. The amount of coal consumed during a oneday period and the rate of air flowing through the furnace are to be determined. Assumptions 1 The power plant operates steadily. 2 The kinetic and potential energy changes are zero. Properties The heating value of the coal is given to be 28,000 kJ/kg. Analysis (a) The rate and the amount of heat inputs to the power plant are Q in Qin W net,out 300 MW 0.32 K th Q in 't 937.5 MW (937.5 MJ/s)(24 u 3600 s) 8.1 u 10 7 MJ The amount and rate of coal consumed during this period are mcoal Qin qHV m coal mcoal 't 8.1 u 107 MJ 28 MJ/kg 2.893 u 106 kg 24 u 3600 s 2.893 u 106 kg 33.48 kg/s (b) Noting that the air-fuel ratio is 12, the rate of air flowing through the furnace is m air (AF)m coal (12 kg air/kg fuel)(33.48 kg/s) 401.8 kg/s PROPRIETARY MATERIAL. © 2008 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission.