Fuels and Combustion

Question: A sample of natural gas containing 80% methane (CH4) and rest nitrogen (N2) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the reminder going to CO, the Orsat analysis in volume percent is [A]. CO2 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60…

Question: For which pair of the fuel gases, calorific value (C.V.) of one fuel is almost double that of the other on volume basis (i.e., kcal/Nm3 ), while the C.V. is same on weight basis (i.e., kcal/kg) ? [A]. Propane and acetylene [B]. Propane and LPG [C]. Sewage gas and gobar gas [D]. B.F. gas…

Question: During coking of coal, the ash content (percentage) [A]. increases [B]. decreases [C]. remains constant [D]. – Answer: Option A Explanation: No answer description available for this question.

Question: For the case of a fuel gas undergoing combustion with air, if the air/fuel ratio is increased, the adiabatic flame temperature will [A]. increase [B]. decrease [C]. increase or decrease depending on the fuel type [D]. not change Answer: Option B Explanation: No answer description available for this question.

Question: Gross & net calorific value is the same for [A]. blast furnace gas [B]. coke oven gas [C]. L.D. converter gas [D]. none of these Answer: Option C Explanation: No answer description available for this question.

Question: Low temperature carbonisation of coal produces [A]. metallurgical coke [B]. soft coke [C]. very low calorific value coke oven gas [D]. no by-products Answer: Option B Explanation: No answer description available for this question.

Question: Incomplete combustion of fuel in the furnace is judged by high __________ of the flue gases. [A]. CO content [B]. dew point [C]. CO2 content [D]. O2 content Answer: Option A Explanation: No answer description available for this question.

Question: Dust content in raw blast furnace gas is about __________ gm/Nm3 , hence it is cleaned to the dust level of about < 10 mg /Nm3 before use. [A]. 15-30 [B]. 1-2 [C]. 70-100 [D]. 150-200 Answer: Option A Explanation: No answer description available for this question.

Question: Blast furnace coke is made from coal by [A]. low temperature carbonisation. [B]. high temperature carbonisation. [C]. medium temperature carbonisation. [D]. heating the coal in an oven in presence of air. Answer: Option B Explanation: No answer description available for this question.

Question: __________ prohibits the use of alcohols directly in petrol engines. [A]. Low octane number [B]. High cost & availability [C]. Low flash point [D]. Low calorific value Answer: Option B Explanation: No answer description available for this question.