Sensible heat of hot industrial flue gases cannot be recovered by a/an
(A) Economiser
(B) Regenerator
(C) Ceramic recuperator
(D) None of these
Description : Which of the following is not a continuous waste heat recovery equipment from the flue gases going out of furnace? (A) Economiser (B) Regenerator (C) Ceramic recuperator (D) Waste heat boiler
Last Answer : (B) Regenerator
Description : Waste heat from the outgoing flue gases in a thermal power plant is recovered by a/an (A) Economiser (B) Steam superheater (C) Air preheater (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Pick up the odd one out: b) Regenerator c) Recuperator d) Metallic recuperator e) Economiser
Last Answer : Economiser
Description : In which of the waste heat recovery equipment, the flow of flue gas and air is alternately reversed after a fixed interval of time? (A) Recuperator (B) Regenerator (C) Waste heat boiler (D) None of these
Description : Which of the following is the most suitable for preheating combustion air above 650°C? (A) Regenerator (B) Metallic recuperator (C) Ceramic recuperator (D) None of these
Last Answer : (C) Ceramic recuperator
Description : The economiser is used in boilers to........ A]Increase thermal efficiency of boiler B]Economise on fuel C]Extract heat from the exhaust the gases D]Increase flue gas temperature
Last Answer : A]Increase thermal efficiency of boiler
Description : In a low to medium temperature waste heat recovery system which of the device is most suitable a) Economiser b) Heat wheels c) air preheater d) Recuperator
Last Answer : Heat wheels
Description : An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a (A) Boiler (B) Heat exchanger (C) Recuperator (D) Regenerato
Last Answer : (B) Heat exchanger
Description : The main drawback of supplying more excess air in the combustion of fuel is the (A) Excessive power requirement of air blower (B) Enhanced sensible heat loss in the flue gas (C) Intermittent and uncontrolled combustion of the fuel (D) High exit flue gas temperature from the furnace
Last Answer : (B) Enhanced sensible heat loss in the flue gas
Description : Most of the phosphorous present in the blast furnace burden enters into (A) Hot metal (B) Flue gases (C) Slag (D) Refractory lining
Last Answer : (A) Hot metal
Description : Water-tube boiler is the one, in which (A) Water passes through tubes and flue gases around it (B) Tube carrying hot flue gases are immersed in a pool of water (C) Tubes are placed in vertical position (D) None of these
Last Answer : Option A
Description : Ceramic recuperators compared to metallic recuperators for the same duty (A) Are lighter (B) Occupy more space (C) Are less costly (D) Have higher pressure differential between flue gas & air side
Last Answer : (B) Occupy more space
Description : The heat recoverable from flue gases of furnaces depends on the (A) Thermal efficiency of furnace (B) Quantity of flue gases (C) Flue gas temperature drop through the furnace (D) All (A), (B) and (C)
Description : In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the (A) Rate of firing and emissivity of flame (B) Thermal conductivity of the charge & ... (C) Nature of process; whether batch, continuous or intermittent (D) All (A), (B) and (C)
Description : Too much of excess air in combustion results in high (A) Fuel consumption for the same heat load (B) Stack gas temperature (C) Percentage of oxygen in flue gases (D) All (A), (B) and (C)
Description : The solvent used in liquid extraction should not have high latent heat of vaporisation, because (A) The pressure drop and hence the pumping cost will be very high (B) It cannot ... by distillation may be prohibitively high (D) It will decompose while recovering by distillation
Last Answer : (C) Its recovery cost by distillation may be prohibitively high
Description : n a chemical factory where dyes are made, wet cake at 30 OC consisting of 60% moisture is put in a dryer to obtain an output having only 5% moisture, at atmospheric pressure. In each batch about 120 ... dryer and the dryer efficiency is 80%. Latent heat of steam at 4 kg/cm2 is 520 kcal/kg.
Last Answer : Given that Qty of material dried per batch - 120 Kgs Moisture at inlet - 60% a. The quantity of moisture removed per batch. Water quantity in a wet batch - 120 x 0.6 = 72 Kgs. Quantity of bone dry ... - 48/0.95 = 50.5 Kgs. Equivalent water in a dry batch - 50.5 - 48 = 2.5 Kgs.
Description : Which of the following cannot be measured by a thermometer? a. Latent Heat b. Sensible Heat c. Specific Heat d. Heat of Fusion
Last Answer : Latent Heat
Description : Calculate the recoverable waste heat (Q, in kCal/hour) from flue gases using the followingparameters: V (flow rate of the substance) 2000 m3/hr r (density of the flue gas): 0.9 kg/m3 Cp (specific heat ... (temperature difference): 120 oC h (recovery factor): 50% a. 21600 b. 43200 c. 25600 d. 34000
Last Answer : 21600
Description : In regenerative air preheater (as practised in heating of coke ovens), the heat is transferred (A) Through a metallic wall (B) By direct contact of hot flue gas with air (C) By ... material (like chequor bricks) and then heating the air from this hot material (D) None of these
Last Answer : (C) By heating an intermediate material (like chequor bricks) and then heating the air from this hot material
Description : Metallic recuperators are not used for waste heat recovery, if the hot flue gas temperature is above __________ °C, because corrosion prevails at higher temperatures. (A) 350 (B) 750 (C) 1050 (D) 1250
Last Answer : (B) 750
Description : Capillary wick is a part of a) heat pump b) heat wheel c) heat pipe d) regenerator
Last Answer : heat pipe
Description : Regenerator is widely used in: a) Reheating Furnaces b) heat treatment furnaces c) Baking Ovens d) glass melting furnaces
Last Answer : glass melting furnaces
Description : Which of the following is not an additive for flue gases from furnace to reduce its dew-point? (A) Ammonia (B) Fine dolomite (C) Alkaline powders (D) None of these
Last Answer : (D) None of these
Description : Which furnace employs an I.D. fan for the removal of flue gases from the furnace? (A) Coke oven (B) Blast furnace stoves (C) Beehive coke oven (D) High pressure boiler
Last Answer : (D) High pressure boiler
Description : Furnace aerodynamics is related to the __________ in the furnace. (A) Movement of gases (B) Measurement of flue gas volume (C) Temperature control
Last Answer : (A) Movement of gases
Description : 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
Last Answer : (A) CO content
Description : With increase in C/H ratio of a fuel, the dew point of flue gases (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease; depends on the type of fuel
Last Answer : (B) Decreases
Description : Which of the following accounts for maximum energy loss in a boiler? (A) Flue gases (B) Ash content in the fuel (C) Incomplete combustion (D) Unburnt carbon in flue gases
Last Answer : (A) Flue gases
Description : High sulphur content in a fuel __________ of the flue gases. (A) Decreases the dew point (B) Increases the dew point (C) Reduces the combustion efficiency by limiting the permissible temperature reduction (D) Both (B) and (C)
Last Answer : (D) Both (B) and (C)
Description : Limestone powder is injected during pulverised coal burning in boilers to __________ the flue gases. (A) Reduce SO2 content in (B) Catalytically convert SO2 to SO3 in (C) Increase the dew point of (D) None of these
Last Answer : (A) Reduce SO2 content in
Description : Pick out the wrong statement. (A) A slight haze at the top of chimney indicates good combustion in the furnace (B) A bag filter incurs very small pressure drop and is very efficient for ... dust collection equipment for removal of submicronic dust particles present in flue gas (D) None of these
Last Answer : (B) A bag filter incurs very small pressure drop and is very efficient for removal of submicronic dust particles from flue gases at very high temperature
Description : The function of an economiser in a boiler is to preheat the (A) Feedwater (B) Combustion air (C) Pulverised coal (D) Furnace oil
Last Answer : (A) Feedwater
Description : The thermal efficiency of an air/fuel gas preheating recuperator may be as high as __________ percent. (A) 50 (B) 65 (C) 85 (D) 99
Last Answer : (C) 85
Description : Refractory bricks having high thermal conductivity is desirable, when it is to be used in the (A) L.D. converter (B) Blast furnace (C) Rotary kiln (D) Recuperator
Last Answer : (D) Recuperator
Description : A catalyst (A) Initiates a reaction (B) Lowers the activation energy of reacting molecules (C) Is capable of reacting with any one of the reactants (D) Cannot be recovered chemically unchanged at the end of a chemical reaction
Last Answer : (C) Is capable of reacting with any one of the reactants
Description : Pick out the correct statement. (A) In catalytic reactions, the catalyst reacts with the reactants (B) A catalyst initiates a chemical reaction (C) A catalyst lowers the activation energy of ... molecules (D) A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction
Last Answer : (C) A catalyst lowers the activation energy of the reacting molecules
Description : Heat in BTU necessary to increase the temperature of 1 lb of gas and its accompanying vapour by 1°F is called the (A) Latent heat (B) Humid heat (C) Specific heat (D) Sensible heat
Last Answer : (C) Specific heat
Description : McCabe-Thiele method of binary distillation does not assume that the (A) Sensible heat changes are negligible compared with latent heat changes (B) Molar latent heats of all components are equal (C) Heat of mixing is negligible (D) None of these
Description : Removal of __________ heat is involved in the condensation of a vapor under saturated conditions. (A) Super (B) Sensible (C) Latent (D) Both (B) & (C)
Last Answer : (B) Sensible
Description : Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212°F may be around __________ BTU. (A) 180 (B) 970 (C) 3.97 (D) Data insufficient, can't be predicted
Last Answer : (A) 180
Description : In a cooling tower, water becomes cool by (A) Loosing sensible heat (B) Heat transfer to surroundings (C) Vaporisation due to heat loss to air (D) Loosing latent heat
Last Answer : (A) Loosing sensible heat
Description : Net calorific value is the gross calorific value less the __________ heat of water in the product of combustion when cooled to 15°C. (A) Sensible (B) Latent (C) Sensible and latent (D) None of these
Last Answer : (C) Sensible and latent
Description : Evaporative cooling process employs a combination of cooling and humidification in which the (A) Sensible heat is added (B) Sensible heat is removed and the latent heat is added (C) Latent heat is removed (D) Sensible heat is added and latent heat is removed
Last Answer : Option B
Description : What Are The Methods Adopted To Remove’ S02 Flue Gases?
Last Answer : 1. Wet scrubbing 2. Solid absorbent 3. Catalytic oxidation
Description : Find false statement about effect of sulphur in fuel? (A) It has heating value (B) It helps in electrostatic precipitation of ash in flue gases (C) It leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low (D) It erodes furnace walls
Last Answer : (D) It erodes furnace walls
Description : Which of these is an output of a ‘Furnace’? a. Fuel gas b. Cool Air c. Flue gases d. Water Vapor
Last Answer : c. Flue gases
Description : What is the function of boiler? • To burn the fuel in a confined closed system With the supply of air • To generate steam in varying pressure • To generate steam at constant pressure • To produce flue gases by burning fuel at a given pressure
Last Answer : • To generate steam at constant pressure
Description : The biggest loss in the boiler is a) Moisture in fuel b) Dry flue gases c) Steam formation d) Unburnt carbon
Last Answer : b) Dry flue gases