Page 106 - Chemical Process Equipment - Selection and Design

78 TRANSFER OF SOLIDS
TABLE 5.2. Codes for Characteristics of Granular Materialsa TABLE 5.3. Bulk Densities, Angles of Repose, and Allowable
Angles of Inclination
Major Code
Class Material Characteristics Included Designalion Recom-
Density Bulk Density, Loose Actual Average Angle of mended
IbS/fP Weight Repose Maximum
Material (Ib/cuft) (degrees) Inclination
No. 200 Sieve (.0029") And Under
Very Fine No. 100 Sieve 1.0059") And Under
No. 40 Sieve 1.016") And Under Alum, fine 45-50 30-45
Alumina 50-65 22 10-12
Fine No. 6 Sieve 1.132") And Under Aluminum sulfate 54 32 17
Granular %"And Under Ammonium chloride 45-52
Size
Granular 3"And Under Ammonium nitrate 45
[')Lumpy Over 3"To Be Special Ammonium sulfate 45-58
X=Actual Maximum Size Asbestos shred 20-25
Irregular Stringy, Fibrous, Cylindrical, Ashes, coal, dry, ;in. max 35-40 40 20-25
Slabs, etc. Ashes, coal, wet, :in. max 45-50 50 23-27
Ashes, fly 40-45 42 20-25
Very Free Flowing-Flow Function > 10 1
Free Flowing-Flow Function >4 But < 10 2 Asphalt, 2 in. rnax 45
Flowability
Average Flowability-Flow Function >2 Butc4 3 Baking powder 40-55 18
Sluggish-Flow Function < 2 4
Barium carbonate 72
Mildly Abrasive -Index 1-17 5 Bauxite, ground 68 35 20
Abrasiveness Moderately Abrasive- Index 18-67 6 Bentonite, 100 mesh max 50-60
Extremely Abrasive- Index 68-416 7
Bicarbonate of soda 40-50
Builds Up and Hardens F Borax, in. 55-60
Generates Static Electricitv G Borax, fine 45-55 20-22
Decomposes- Deteriorates in Storage H
Flammability J Boric acid, fine 55
Becomes Plastic or Tends to Soften K Calcium acetate 125
Very Dusty L
Aerates and Becomes Fluid M Carbon, activated, dry, fine 8-20
Explosiveness N Carbon black, pelleted 20-25
Miscellaneous Stickiness-Adhesion 0
Properties Contaminable, Affecting Use P Casein 36
Or Degradable, Affecting Use Q Cement, Portland 94 39 20-23
Hazards Gives Off Harmful or Toxic Gas or Fumes R
Highly Corrosive S Cement, Portland, aerated 60-75
Mildly Corrosive T Cement clinker 75-95 30-40 18-20
Hygroscopic U Charcoal 18-25 35 20-25
Interlocks, Mats or Agglomerates v
Oils Present W Chips, paper mill 20-25
Packs Under Pressure X Clay, calcined 80-1 00
Very Light and Fluffy-May Be Windswept Y
Elevated Temperature Z Clay, dry, fine 100- 120 35 20-22
Clay, dry, lumpy 60-75 35 18-20
"Example: Afine 100 mesh material with an average density of Coal, anthracite, fin. max 60 35 18
50 Ib/cufl that has average flowability and is moderately abrasive Coal, bituminous, 50 mesh max 50-54 45 24
would have a code designation 50A,,,36; if it were dusty and mildly Coal, bituminous, in. max 43-50 40 22
corrosive, it would be 50A,,,36LT. Coal, lignite 40-45 38 22
(FMC Corp., Materials Handling Division, Homer City, PA, 1983). Coke breeze, in. max 25-35 30-45 20-22
Copper sulfate 75-85 31 17
Cottonseed, dry, delinted 35 29 16
Power is required to run the empty conveyor and to carry the Cottonseed, dry, not delinted 18-25 35 19
load horizontally and vertically. Table 5.5 gives the equations, and Cottonseed meal 35-40 35 22
they are applied in Example 5.4. Squirrel-cage ac induction motors Cryolite dust 75-90
are commonly used as drives. Two- and four-speed motors are Diatomaceous earth 11-14
available. Mechanical efficiencies of speed reducing couplings Dicalcium phosphate 40-50
between motor and conveyor range from 95 to 50%. Details of Disodium phosphate 25-31
idlers, belt trippers, cleaners, tension maintaining devices, struc- Earth, as excavated, dry 70-80 35 20
tures, etc. must be consulted in manufacturers' catalogs. The selec- Earth, wet, containing clay 100-1 10 45 23
tion of belt for strength and resistance to abrasion, temperature, Epsom salts 40-50
and the weather also is a topic for specialists. Feldspar, fin. screenings 70-85 38 18
Ferrous sulfate 60-75
Flour, wheat 35-40
BUCKET ELEVATORS AND CARRIERS Fullers earth, dry 30-35 23
Fullers earth, oily 60-65
Bucket elevators and carriers are endless chains to which are Grain, distillery, spen, dry 30
attached buckets for transporting granular materials along vertical, Graphite, flake 40
inclined or horizontal paths. Figure 5.10 shows two basic types: Grass seed 10-12
spaced buckets that are far apart and continuous which overlap. Gravel, bank run 90-1 00 38 20
Spaced buckets self-load by digging the material out of the boot and Gravel, dry, sharp 90-1 00 15-17
are operated at speeds of 200-300fpm; they are discharged Gravel, pebbles 90-1 00 30 12
centrifugally. Continuous buckets operate at lower speeds, and are Gypsum dust, aerated 60-70 42 23
used for friable materials and those that would be difficult to pick Gypsum, fin. screenings 70-80 40 21
up in the boot; they are fed directly from a loading chute and are Iron oxide pigment 25 40 25
42-56
45
23
Kaolin talc, 100 mesh
discharged by gravity. Bucket carriers are essentially forms of pan Lactose 32
conveyors; they may be used instead of belt conveyors for shorter Lead arsenate 72
distances and when they can be made of materials that are