A furnace is to be designed for a heat duty of 30 x 106 Btu/hr and efficiency of 75%. The furnace is fired with gaseous fuel at a rate of 17 lb air/lb fuel (NHV = 17000 Btu/lb). The tubes are arranged...

A furnace is to be designed for a heat duty of 30 x 106 Btu/hr and efficiency of 75%. The furnace is fired with gaseous fuel at a rate of 17 lb air/lb fuel (NHV = 17000 Btu/lb). The tubes are arranged in two rows and are of 5 in OD., 40 ft length and 2x OD. Spacing, heat rate of 35000 Btu/hr of projected area is recommended. Calculate:
1) % heat absorbed in radiation section (R %).
2) Heat absorbed in the convection section. (State any assumptions used).
3) The number of tubes in the radiation section.

Extracted text: H.W (1) A furnace is to be designed for a heat duty of 30 x 10° Btu/hr and efficiency of 75%. The furnace is fired with gaseous fuel at a rate of 17 lb air / Ib fuel (NHV = 17000 Btu/lb). The tube are arranged in two rows and are of 5 in OD., 40 ft length and 2x OD. Spacing, heat rate of 35000 Btu/hr of projected area is recommended calculate: 1) % heat absorbed in radiation section (R %). 2) Heat absorbed in the convection section. (State any assumptions used). 3) The number of tubes in the radiation section. H.W (2) 7000 lb/hr of cracked gas of 20560 Btu/lb NHV is used as a fuel in a furnace. The radiant section absorbed 44500 Btu/hr ft of projected area. The tubes are 5 in. OD. , 10 in. spacing, and 20 ft long. They arranged in two rows. The air to fuel ratio is 21.0. Calculate 1) the number of tubes in the radiation section 2) the amount of heat absorbed in this section.