Grain handling equipment

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There us a wide variety of such equipment available on the market, and table 9.6 is an attempt to categorise their ability to move grain.

Table 9.6 Grain Handling Equipment

Type of Equipment Fixed or Portable Horizontal or H Vertical V Capacity range Power Requirement Cost Advantages Disadvantages
Belt and Bucket elevator F V medium low medium 1. efficient 1. can be
    to   to 2. Minimum difficult
    high   high maintenance to erect
          3. high capacity 2. expensive
          4. cleanable  
Auger

(Screw conveyor)

 F P H + V medium medium medium 1. wide range 1. can damage
          available some material
            2. medium to
            heavy wear
Belts F H high low high 1. long distances 1. expensive
  If belt is       2. low power 2. angle very
  ribbed max       3. self cleaning limited
  30° angle          
General purpose elevator with belt or chain with slats F P H medium low to medium 1. multipurpose 1. noisy with chain
  and inclined with ribs   medium   2. inexpensive  
Tractor

shovels

 P H medium on tractor low 1. (flexible requires space
    to - high   2. high output in to operate in
    high     short time -for loading lorries  
Sweep

Augers

Sack

barrows

Pneumatic

 FP H   medium medium medium 1. unloading
          round bins  
P H   depends on - - 1. high labour
    distance.       requirement.
P H + V low high high 1. flexible 1. noisy
    to       2. much dust
    medium       3. reduced cap for wet grain

Belt-and-Bucket Elevator

A flat belt is carried between a crowned pulley at the top and bottom of casing. Small buckets or scoops are fixed to the belts at regular intervals and these carry the grain from the elevator bottom to the top. The capacity depends upon width of buckets, spacing and belt speed. Elevators of up to 20m height and capacities of 50tonnes/h are available.

Auger (Screw Conveyors)

Auger elevators are reasonable in cost, comparatively light in weight, and dependable in their operation. They are available in a wide range of lengths and capacities and are usually powered by an electric motor. Long augers may be mounted on wheels for easy transport. The angle of operation is adjustable, however, the capacity goes down as the auger is raised, see table 9.7. High moisture content also reduces the capacity.

Table 9.7 Example of Auger capacity and power requirements per 3m length of auger (0150mm)

Moisture

content %

Angle of Elevation
0° t/hr kW 22.5° t/hr kW 45° t/hr kW 67.5° t/hr kW 90° t/hr kW
14 27 0.42 25 0.61 21 0.64 17 0.62 13 0 52
25 17 1.32 15 1.40 13 1.33 10 1.08 7 0.52

Note: Auger speed 400 rpm

Power requirement is directly proportional to the auger length.

Flat Belt Conveyor

These are used in practice horizontally although up to 15° inclination is possible. With ribs the angle can be increased to 30°. The capacity is high and loading and unloading can be done any place along the belt. It does not cause any damage to the crop and raises little dust.

Chain and Slats Conveyor

These consist of a chain carrying traverse slats which drag the grain along a metal or wooden trough. Slat width up to 300mm spaced 150 to 300mm apart and chain speeds of 10 - 77 cm/s are used to give outputs up to 30 tonnes/in. Small sized models have no support frame and can be carried by two men.

Sack elevator

These may be a continuous belt with ribs or a chain conveyor with slats.

Dumping Pits

To achieve high capacity with tractors and trailers when taking grain to the store, an effective system of receiving grain must be used. Ideally, it should be possible to dump a trailer load and pull away within minutes. Such a reception facility will normally be associated with an elevator to raise grain for conditioning or storage.

Reception Pit with an Elevator

A concrete wood or steel-lined pit with an inverted pyramid or V-shaped bottom is built in the ground, see figure 9.29.

Figure 9.29 Dump Pit with an auger moving the grain to the elevator.

The crop is dumped from a trailer into the reception pit from which it flows by gravity or by the help of an auger into a second pit containing the bottom end of an elevator. Much time is saved, if reversing to the tipping pit by the farm transport is avoided, by having a "run-over" pit. This requires a safety grid, which must be strong enough to carry a loaded trailer.

Shallow Surface Pits

These are usually in conjunction with an auger. Two simple pits of this kind are shown in Figure 9.30.

Figure 9.30 Small Simple Reception Pits.

Overhead Grain-loading Bins

Hopper-base gravity discharge bins, when erected at a suitable height, facilitate the loading of transport vehicles at high rates. This will cut the waiting cost and should therefore be considered where the capacity of the loading equipment is low compared to the load capacity of the vehicle.

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