Advantage of continuous drying over batch drying is that the
(A) Drying cost per unit weight of dried product is less
(B) Product with more uniform moisture content is produced
(C) Equipment size required is smaller
(D) All 'a', 'b' & 'c'
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 : Batch process is preferred over continuous process, when the (A) Product yields and quality cannot be achieved in continuous process, because of long residence time (B) Sales demand of product is not steady (C) Same ... be used for several processes of the same nature (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : Batch process is preferred over continuous process, when the (A) Product yields and quality cannot be achieved in continuous process, because of long residence time (B) Sales demand of product is not steady (C) Same ... cannot be used for several processes of the same nature (D) All (A), (B) & (C)
Last Answer : (B) Sales demand of product is not steady
Description : Multistage compression of air as compared to single stage compression offers the advantage of (A) Power saving per unit weight of air delivered (B) Moisture elimination in the inter-stage cooler (C) Increased volumetric efficiency (D) All (A), (B) & (C)
Description : In the constant rate period of the rate of drying curve for batch drying, (A) Cracks develop on the surface of the solid (B) Rate of drying decreases abruptly (C) Surface evaporation of unbound moisture occurs (D) None of these
Last Answer : (C) Surface evaporation of unbound moisture occurs
Description : In a laboratory test run, the rate of drying was found to be 0.5 x 10 - 3 kg/m2 .s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.08 on a dry ... of the solids from 0.3 to 0.2 (dry basis) is (A) 2000 (B) 4000 (C) 5000 (D) 6000
Last Answer : (C) 5000
Description : A 25 cm 25 cm 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m 1m 1cm ... 19.2 kg to 17.6 kg is (A) 1000 (B) 1500 (C) 2000 (D) 2500
Last Answer : (A) 1000
Description : Dried finished product sampled from various parts of a __________ dryer exhibits non-uniformity in the moisture content. (A) Rotary (B) Tray (C) Freeze (D) None of these
Last Answer : (B) Tray
Description : Sometimes, batch process is preferred over continuous process, when the product (A) Quality & yield cannot be achieved in continuous processes, because of long residence time (B) Sales demand is fluctuating (C) Both (A) & (B) (D) Neither (A) nor (B)
Last Answer : (C) Both (A) & (B)
Description : Pick out the wrong statement. (A) In a batch reactor, which is exclusively used for liquid phase reactions; temperature pressure and composition may vary with time (B) In a semi-batch reactor, ... system (D) In a continuous flow reactor, both the reactants and the products flow out continuously
Last Answer : (C) In a continuous flow reactor, uniform concentration cannot be maintained throughout the vessel even in a well agitated system
Description : For determining the moisture content of a soil sample, the following data is available Weight of container = 260 g, Weight of soil sample and = 320 g container, Weight of soil sample (dried) and = 310 g container. The moisture content of the soil sample, is (A) 15 % (B) 18 % (C) 20 % (D) 25 %
Last Answer : (C) 20 %
Description : Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to ... tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side
Last Answer : (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger
Description : During drying of a solid, the critical moisture content increases with (A) Decreased drying rate (B) Increased thickness of the solid (C) Increased drying rate (D) Both (B) and (C)
Last Answer : (D) Both (B) and (C)
Description : Drying operation under vacuum is carried out to (A) Dry those materials which have very high unbound moisture content (B) Reduce drying temperature (C) Increase drying temperature (D) Dry materials having high bound moisture content
Last Answer : (B) Reduce drying temperature
Description : Pick out the correct statement. (A) Bound moisture is removed during constant rate drying period (B) Free moisture is removed during falling rate drying period (C) The sum of free moisture and ... (D) The driving force for mass transfer in a wet solid is its free moisture content
Last Answer : (D) The driving force for mass transfer in a wet solid is its free moisture content
Description : It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The ... 5%). (A) 15 min (B) 51 min (C) 71 min (D) 94 min
Last Answer : (C) 71 min
Description : The critical moisture content in case of drying indicates the __________ rate period. (A) Beginning of falling (B) Beginning of constant (C) End of falling (D) None of these
Last Answer : (A) Beginning of falling
Description : The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 2 (D) T
Last Answer : (C) T
Description : 200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 10 -3 kg/m2 .s. The initial ... moisture/kg dry solid). (A) 0.5 (B) 0.05 (C) 0.1 (D) 0.15
Last Answer : (C) 0.1
Description : Batch tray dryers suffers from the disadvantage of (A) High maintenance cost (B) Non-uniform & low production rate (C) High labour cost & low heat economy (D) All 'a', 'b' & 'c'
Last Answer : (C) High labour cost & low heat economy
Description : Pick out the wrong statement pertaining to the roll crushers. (A) Maximum feed size determines the required roll diameter (B) For hard material's crushing, the reduction ratio should not ... ratio and differential roll speed affect production rate & energy consumed per unit of surface produced
Last Answer : (C) Both the rolls run necessarily at the same speed
Description : Swenson-Walker crystalliser is a __________ unit. (A) Continuous (B) Batch (C) Semi-batch (D) Cooling (adiabatic)-cum-evaporation
Last Answer : (A) Continuous
Description : Fluidised bed reactor is characterised by (A) Uniformity of temperature (B) Comparatively smaller equipment (C) Very small pressure drop (D) Absence of continuous catalyst regeneration facility
Last Answer : (A) Uniformity of temperature
Description : Batching refers to (A) Controlling the total quantity at each batch (B) Weighing accurately, the quantity of each material for a job before mixing (C) Controlling the quantity of each material ... be added in each batch according to the moisture content of the materials being mixed in the batch
Last Answer : (C) Controlling the quantity of each material into each batch
Description : The practical limit of moisture content achieved in air drying of timber is (A) 5 % (B) 15 % (C) 25 % (D) 35 %
Last Answer : Answer: Option B
Description : In continuous fluidisation (A) Solids are completely entrained (B) The pressure drop is less than that for batch fluidisation (C) There is no entrainment of solids (D) Velocity of the fluid is very small
Last Answer : (A) Solids are completely entrained
Description : 1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is (A) 520 (B) 200 (C) 400 (D) 500
Last Answer : (C) 400
Description : Bond crushing law (A) Calls for relatively less energy for the smaller product particles, than does the Rittinger law (B) Is less realistic in estimating the power requirements of commercial crushers ( ... (D) States that the work required for the crushing is proportional to the new surface created
Last Answer : (A) Calls for relatively less energy for the smaller product particles, than does the Rittinger law
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)
Last Answer : (D) All (A), (B) and (C)
Description : Vacuum is applied in __________ zone, in case of a general type continuous rotary drum vacuum filter. (A) Filtering (B) Washing (C) Drying (D) All (A), (B) & (C)
Description : Glycerine is used as a coolant in cooling of some engines instead of water, because (A) Its higher boiling point (290°C) increases its heat carrying capacity (B) Comparatively less weight of coolant is required (C) Smaller radiator can be used (D) All a, b & c
Last Answer : (D) All a, b & c
Description : Coke made in narrower by-product coke ovens (as compared to wider ovens) is (A) Less reactive (B) Stronger (C) Smaller in size (D) All (A), (B) & (C)
Description : Which type of processing syste Which type of processing system tends to produce th m tends to produce the most product variety? e most product variety? a)Assembly b)Job shop c)Batch d)Continuous
Last Answer : c)Batch
Description : Which type of Which type of processing system processing system tends to tends to produce the produce the most product variety? product variety? a. Assembl y b. job shop c. Batch d. Continuous
Last Answer : b. job shop
Description : Pick out the wrong statement pertaining to the rotary dryer. (A) Flights (located in the inside shell of rotary dryer) lift the material being dried and shower it down through the current of ... D) Recommended peripheral speed of a rotary drier is in the range of 10 to 30 metres/minute
Last Answer : (C) Rotary dryer is suitable for drying sticky materia
Description : A compacted soil sample using 10% moisture content has a weight of 200 g and mass unit weight of 2.0 g/cm3 . If the specific gravity of soil particles and water are 2.7 and 1.0, the degree of saturation of the soil is (A) 11.1 % (B) 55.6 % (C) 69.6 % (D) None of these
Last Answer : (B) 55.6 %
Description : A partially saturated sample of soil has a unit weight of 2.0 g/cm3 and specific gravity of soil particles is 2.6. If the moisture content in the soil is 20%, the degree of saturation is (A) 20 % (B) 77 % (C) 92 % (D) None of these
Last Answer : Answer: Option C
Description : The dry density of soil is a) Always greater than the saturated density b) Weight of soil solids per unit of total volume prior to drying* c) Total weight of soil solids per unit of its total volume d) Total weight of soil mass per unit of its total volume
Last Answer : b) Weight of soil solids per unit of total volume prior to drying*
Description : Turn down ratio of a burner (A) Should be as low as possible i.e., 1 : 2 (B) Should be 1:1 for a batch type furnace (C) Is the ratio of maximum to minimum permissible heat input rates (D) Is normally much more for a continuous furnace as compared to a batch furnace
Last Answer : (C) Is the ratio of maximum to minimum permissible heat input rates
Description : The main advantage of forced draft over natural draft is that (A) Combustion of fuel is complete (B) Smaller height chimney can be used (C) Furnace control is easier (D) All (A), (B) & (C)
Description : Which of the following procedures should be used to maintain a large electric motor during periods of inactivity? A. A thin layer of air-drying varnish should be applied on the windings. B. ... periodically to remove carbon dust. D. Space heaters should be used to prevent condensation of moisture.
Last Answer : Answer: D
Description : __________ Centrifuge is normally used in sugar mills. (A) Tubular bowl (B) Disc-bowl (C) Suspended batch basket (D) Perforated horizontal basket continuous
Last Answer : (C) Suspended batch basket
Description : __________ centrifuge is the most suitable for separation of non-friable crystals. (A) Tubular bowl (B) Disc-bowl (C) Perforated horizontal basket continuous (D) Suspended batch baske
Last Answer : (C) Perforated horizontal basket continuous
Description : Penicillin is made employing __________ fermentation process. (A) Continuous (B) Aerobic batch (C) Anaerobic batch (D) None of these
Last Answer : (B) Aerobic batch
Description : Pick out the wrong statement. (A) Nitrogen is normally supplied in fertiliser either in Ammoniacal or the nitrate form, from which the soil takes it up in the form of ammonium ions ornitrate ... nitrate fertiliser is obtained as a by-product in an integrated steel plant having by-product coke ovens
Last Answer : (D) Ammonium nitrate fertiliser is obtained as a by-product in an integrated steel plant having by-product coke ovens
Description : Carbon Content by weight in air dried wood may be about __________ percent. (A) 10 (B) 25 (C) 50 (D) 80
Last Answer : (C) 50
Description : Degree of carbonisation of coal during coke making can be roughly judged by the __________ of the coke produced. (A) Colour (B) Moisture content (C) Ash content (D) Volatile matter
Last Answer : (D) Volatile matter
Description : For continuous drying of granular or crystalline material, the dryer used is the __________ dryer. (A) Tunnel (B) Tray (C) Rotary (D) None of these
Last Answer : (C) Rotary
Description : Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate. (A) Increases (B) Decreases (C) Does not affect
Last Answer : (B) Decreases
Description : The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 1.5 (D) T
Last Answer : (B) T