No Subject Requirement (Rule of thumb & Application) References and notes

1 Aerated bulk material density 0.66 multiply by bulk density DCL, if aerated bulk density is not known

2 Applicated material density for air slide conveyor 5 up to 200 lb/ft^3,

For material has angle of repose 35 up to 40 deg is categorized as most free

flowing material (Book)

DCL

· For bulk density ≤ 70PCF - 20inch WG in plenum chamber

· For bulk density > 70PCF - 27inch WG in plenum chamber

DCL,

70PCF ≡ 1.24ton/m^3

20 inch WG ≡ 50 mBar

27 inch WG ≡ 67 mBar

400 mmWG ≡ 40mBar FLSmidth

unknown DCL

Permeability 1.5 m^3/m^2.min, Pressure drop 100mmWG (10mBar) FLSmidth

→ For case P630, length 35m and diaphram area is 0.63*35 =

22.05 m^2, check fan capacity selected from graphical table

43m^3/min (40mBar)

→ Air flow rate through Porous Membrane=

1.5m^3/m^2.min * 22.05m^2 = 33 m^3/min

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∴ Safety factor for air flow rate for fan according to porous

membrane requirement is about 43/33 ≈ SF1.3

8 deg, but may be as low as 6 degrees depending on product material type. DCL , Most product suitable for air gravity conveying are handled

on a conveyor sloped at between 6 and 12 degrees. The slope can

be reduced to 1 or 2 degrees for product which have excellent

fluidizing characteristics.

7 deg, currently aplicated on Tonasa V project is 7 deg (not as minimum but

applied conveyor angle)

FLSmidth, The areated material flows like a liquid

at a suitable inclination of the conveyor

(4o-15

o) depending on the type of material

conveyed

5 Minimum sugested conveyor angle

DESIGN GUIDE FOR AIR SLIDE CONVEYOR

Pressure required for close type conveyor3

Permeability and pressure drop of Porous DIAPHRAM4

6a The volume of free air required (Fan flow rate) 10 SCFM (Standard cubic feet per minute) per square foot

Dimension of air slide conveyor of DCL

A=24 inch (2 ft), length=35m (115 ft)

Membrane area = 2 x 115 (ft^2) = 230 ft^2

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Free air requirement = 10 SCFM/sqft * 230 sqft = 2300 SCFM (65 m^3/min)

∴∴∴∴ Fan flow rate = standard 65 m^3/min

DCL

The volume of free air required for most applications is

approximately 10 SCFM per square foot of conveying media when

handling a product like cement, fly ash, phosphate rock dust, and

lime products. However the air requirements may vary for other

materials from 4 to 15 SCFM (standard cubic feet per minute) per

square foot. In conveying alumina and bauxite, the air

requirement for fluidization can be as little as 4 SCFM. Please be

aware that there is no definite formula for calculating the volume

of free air required. In order to establish the proper air

requirements for materials not previously handled, DCL offers

testing at their facility

6b Handbook of pneumatic conveying engineering

Chapter 18. Fluidized motion conveying system

Basic property of cement portland:

1. Bulk density : 1,070kg/m^3 ≡ 67lbs/ft^3

2. Particle density : 3,060kg/m^3 º 191lbs/ft^3

3. Mean particle size : 14µm

--------------------------------------------------------------

Taken from table that (approximation)

Terminal velocity needed is 5ft/sec ≡ 0.025m/s

Porous membrane area is 230ft^2 ≡ 21.37m^2

→ Fan flow rate is 0.025m/s*21.37m^2 ≡ 0.534 m^3/s ≡ 32m^3/min

→ SF=1.3 (FLSmidth - previous result)

--------------------------------------------------------------------------

Fan flow rate requirement = 1.3 * 32m^3/min ≈ 42m^3/min

∴∴∴∴ Fan flow rate = standard 42m^3/min

6c FLSmidth

Fan flow rate based on P630 and conveying distance 35m is 43

standard m^3/min

∴∴∴∴ Fan flow rate = standard 43m^3/min

7 Air supply interval Up to 100 m FLSmidth

8 Air pressure for open type conveyors installed in

silos or hoppers are generally determined by the

head of product over the conveyor

Air pressure for all material:

• head product over conveyor, H< 2ft - 1PSI

• head product over conveyor, 2≥H<15ft - 2PSI

• head product over conveyo, H>15ft - 6PSI

Except for alumina, pressure of 3 PSI is adequate regardless of head

DCL, pressure up to 1PSI can be supplied by centrifugal blower

and pressure greater than 1PSI should be supplied by positive

displacement blower . A high pressure compressor plant is not

recommended for use in supplying fluidization air as this source is

considered “dirty air” meaning the presence of water and oil

9a Standard dimension of conveying channel Fuller® Airslide™ Conveying Technology, FLSmidth

For example,

Material Cement Portland (A36M/A16M)

A36M: 1.27 up to 1.75 ton/m^3

A16M: 1.06 up to 1.32 ton/m^3

Angle of repose 30-44 deg

For A=600 Nominal capacity > 1,500 m^3/h

For A16M Cement portland, the capacity is > 1,500 ton/h

9b DCL

24 inch (600 mm) - 39,000 ft^3/h ≡ 1,100m^3/h

For A16M Cement portland, the capacity is > 1,100 ton/h

9c FLSmidth

For example,

For P630, capacity range is from 250 up to 1000 m^3/h

For A16M Cement portland, the capacity up to 1,000 ton/h

Conveying angle minimum 4 deg , apllied 7 deg

For 35m conveyor length, Fan capacity 35m^3/min (based on

400mmWG air pressure)

9d Conveyor box width (b) ≈ 0.65 (mass flow rate/particle density)^0.5

Mass flow rate = 800 ton/h

Cement portland (non aerated) density = 72 ~ 99 lbs/ft^3 → 85lbs/P^3

0.5 as aspect ratio (depth/width of flowing bed)

---------------------------------------

b ≈ 0.65 (800/85)^0.5 ≈ 2ft ≈ 610mm

Handbook of pneumatic conveying engineering

Chapter 18. Fluidized motion conveying system