Question

CaCO 25°C C (i.e., carbon) 25°C Flue gases 320°C Kiln Air 25°C CaO, CaCO3 950°C A vertical kiln is charged with pure limestone (CaCO3) and pure coke (not that kind... pure carbon), both at 25°C. Air (21% 02,79% N2) is blown at the bottom. The reaction between 02 in air and coke provides the heat for decomposition of the CaCO3. Combustion reaction: C02g) > CO2(e) Limestone decomposition reaction: CaCO3) -> Ca0s)+ CO2(g Coke is burned with 20% excess air. The flue gases exit the kiln at 320°C. The solid mixture leaves the bottom at 950°C and consists of 94% CaO and 6% CaCO3 by mass. Assume that the kiln is perfectly insulated, so no heat loss to the surroundings. Question: How many kg/hour of coke is needed if CaCO3 enters the kiln at 1000 kg/hour? ΔΗ0f, CaCO3, solid--1 206.9 kJ/mol AHf, Cao, solid--635.6 kJ/mol f, CO2, gas--393.5 1 kJ/mol Cp, CaCOds) 117.1 J/mol.K Cp, CaO(s)-57.3 Jimol.K Cp for all gases and vapors: 30 J/mol.K

Answer 1

Solution:

Given that:

0 Answer Given thar Co2 940 glh 21-36 k mol h :「1678 x (-635.4) xiol +pi. 36 ×103 X (-393.5이 Art Rea at 25c) on 3 -[-120 6.9x oxo 3 -_7001.74 X103 KJ Requied hear ttear load a 15oc

6602-子9Xlos kJ heat loso 廾ear, to decomposeこ 6602.71 χ0sKT χ mo le ot Coke pc needed 02 Supplied (20% exless ar 1.29 んe Know ar, ar 25c e;S+and Cond AHfs (C02) -393.5 kI mol AHP (Reach-ant) eacHon -n 393.5 k丁 Cp Sodo Ax 2 X 30)

whtch should be equal to heat de composition ok. CaCO3 Coke pu Caabon 200 4 kalh