Download Calculating Heat Losses and Savings in Oil & Gas Furnaces: Carbon Credit & Fuel Efficiency and more Exercises Sustainability Management in PDF only on Docsity! Lecture 40: Illustration on carbon credit and efficiency Contents Exercise‐1 Exercise‐2 Key Words: Carbon credit, carbon offset, fuel savings Exercise‐1 An oil fired reheating furnace consumes 100 Kg/ hr oil to heat 1 ton billet to 1400 K. Oil analyses 86 and 14 and is burnt with 25% excess air. Gross calorific value of oil is 45000 kJ/kg. The POC exits the furnace at 1500 K. What are the heat losses & thermal efficiency? % C % H .11 10 kJ hr⁄ .7 10 kJ hr⁄ .5 10 kJ hr⁄ 0.63 10 kJ hr⁄ 16.8 % 16.8 % For this furnace let us install a preheater which can recover 50% of heat to preheat air. Heat losses and to p Preheater installation results in fuel saving. Let F kg hr⁄ is now fuel required. Heat balance F 0.5 31144 45000F 0.63 10 0.76 10 31144F. F 47 kg hr⁄ . Saving in fuel 53 kg hr⁄ . Solution: Heat balance: Heat input = Heat carried by POC + Heat carried by steel +Heat losses. We can calculate amount of POC / 100 kg fuel and heat to POC. All the sensible heat values are taken from the reference given blow. Heat to POC 3 . Heat to steel 0 . Heat input 4 . Heat losses . Thermal efficiency which means that of the calorific value of fuel is used in heating billet. heat to steel are unchanged. Calculate the carbon offset due reheater. Docsity.com For 20 hr da⁄ y and 25 days in month saving 2 it 84 month⁄ . xercise‐2 natural gas is burned in a remelting furnace, which operates 24 hours/day, 300 days in a ear. The natural gas analyses 70% CH and 30% C H . Dry combustion air is 20% excess than theoretical flue g K. I e e heat recovered from flue gases is transferred to air. Calculate annual fuel saving resulting due to preheater installation. Also calculate carbon affect generation. ΔH CO 97.2 10 k cal kg mole ΔH H O V 57.8 10 k cal kg mole ΔH° CH 17.89 10 k cal kg mole ΔH° C H 20.24 10 k cal kg mole nd sensible heat in POC is POC H1200‐H298 {k cal (kg mole H800‐H298{k cal (kg mole) ‐1} Fuel 6500 kg month⁄ Carbon cred E 30 m hr⁄ of y requirements. Flue gas enters the stack at 1200K. Volumes are given at 25 and 1 atmospheric pressure. It is proposed to install a preheater which will cool the ases from 1200K to 800 t may b assumed that 90% of th The heat of combustion values are: ° ° A )‐1} CO2 10650 5458 H2O(V) 1782 4403 O2 7040 3786 N2 6728 3600 Solut : solution is in brief. eat of combustion for the reaction ion given H CH 2O CO 2 H O . Docsity.com
