Download Material Balance in Coke Making - Fuel, Furnace and Refractory - Lecture Notes and more Study notes Sustainability Management in PDF only on Docsity! Lecture 5 Material balance in Coke making In coke‐making, it is often required to calculate the amount of coke, coke oven gas and tar produced per ton of coal. This can be done by performing elemental balance. For this purpose ash, C, N, H and O balance can be done to obtain the require information. This is illustrated by the following problem 1. By product coke ovens are surrounded by air. There may occur leakage of air in the oven. Consider a coke‐ oven surrounded by moist air, (The air is at 750 mm Hg pressure and 26 temperature) . The relative humidity of air is 40%. It carbonizes coal of the composition (Wt%) C76.1, H 4.6, N2.3, S 1.9,O 2.5, H O 6.3 and ash 6.3. The following product and by products are produced: Product: Coke (Wt %) C 85.2, H 1.9, O 2.2, N 0.8, S 1.2 and Ash 8.7 By –product: (a) Coke oven gas (vol % dry basis) and C6H6 1.1,C2H4 2.7,CH4 4.4, CO 1.7, CO2 1.3, H2 36.5, N2 6.9, O2 2, H2S2.1 and NH31.3 (b) Tar (40 kg/ton of coal) analysis (Wt %) C=89.4, H 4.5, N 1.1. and incombustibles Rest. Required per ton of Coal i. Amount of coke /ton of coal g. al. ii. Amount of coke‐oven gas iii. fraction of S in coke and coke oven gas iv. Amount of air leakage: The vapor pressure of moisture in air at saturation is 25.21 mmH v. Calorific value in coke and coke oven gas in terms of fraction of calorific value of Co Solution: Basis of calculation: 1000 kg coal i. Amount of coke /ton of coal Ash balance is used to determine the amount of coke. Let x kg is amount of coke. . . x 724.1 kg coke Answer. Docsity.com ii. Amount of coke oven gas can be calculated by performing C balance C from coal= C in tar+ C in coke + C in Cokes oven gas Let y kg is the amount of Cokes oven gas . . . y 6 0.01 2 0.027 0.344 0.117 0.013 S S By solving we get y= 15.357 kg mole iii. Sulphur distribution a) f fraction of S in coke 0 . . . .457 Ans. b) fraction of S in coke oven gas 0 pN pO pH O 750 mm Where p is partial pressure. RH Relative humanitiy H O H O .543 Ans. iV. To calculate amount of air leaked in to coke oven. N balance is to be done. N is insert. Let Z kg mole is amount of air leaked. In this problem air is moist. We have to find composition of moist air. It follows drom Dalton’s law; V H O V H O PN2 + pO2 + RH x p S H2O = 750 Substituting the value of RH and pSH2O, we get after simplification pN 584.533, pO2 155.382 and p H2O 10.084 moles of N from moist air . 0.7794 N2 from coal+ N2 from air = N in coke + N in tar+ N2 in coke oven gas . 0.7794 Z . . . 0.069 0.0065 15.357. Docsity.com
