INTRODUCTION TO AN OCTAGONAL BLENDER and A DOUBLE CONE BLENDER:
As we discussed in the previous post on V-Blender, both 'Octagonal Blender', as well as, 'Double Cone Blender' are dry powder blenders i.e. solid-solid blender popularly used in Pharmaceutical, Food, Cosmetics and Chemicals industries. In both of these, a fabricated metal container (which carries the powder mixture) rotates across an imaginary horizontal axis i.e. a motorized horizontal shaft, so that the powder particles undergoes constant shuffling due to tumbling and shearing action, resulting into a thorough mixed mass. The bowls of Octagonal Blender and a Double Cone Blender are supported from both the sides with an A shaped metal support structure (just like a swing in a garden) and are rotated with the help of an AC motor and a gearbox.
WHERE AND WHY IS IT USED:
Both the Octagonal and Double Cone Blenders are popularly used in Pharmaceutical, Nutraceutical Manufacturing, Food Processing, Chemical and Cosmetics industries for carrying our operations like Blending, Mixing, Lubricating etc.
(Ref: Pics taken from Jicon Technologies Pvt Ltd, Mumbai India, website is www dot jicon dot com).
COMPARATIVE ANALYSISS BETWEEN 'OCTAGONAL BLENDER' AND 'DOUBLE CONE BLENDER':
1. Size, Shape and Geometry: Octagonal Blender, as the name suggests, consists of an Octagonal Shaped Closed Container. The side cross-sectional view of the Octagonal Blender can show a clear Octagon. Whereas, the Double Cone Blender, as the name suggests, consists of a bowl which has the top and bottom ends made-up of a metal cone, and a central portion is made-up of a low height vertical cylindrical drum. Please refer to the pictures attached above for more details.
2. Material Loading/ Charging and Unloading/ Discharging: Octagonal Blender has a material charging opening (also known as Manhole) which is usually is rectangular opening (located on the top of the blender when it is in a stationary position). The discharge Or unloading is usually done through a bottom circular nozzle which is closed by a butterfly valve usually.
Double Cone Blender too has two openings viz. Top Charging Circular Nozzle Or Manhole and a Bottom Discharge Nozzle sealed with a butterfly valve.
In both of these cases, the manholes are big enough. Octagonal has a rectangular and very big manhole with a removable metal lid, which is fixed to the blender body with the help of a set of Eye Bolts by placing a food grade silicon gasket at the interface. Whereas, incase of the Double Cone, the manhole is Circular with a neck flange and a Hinged Lid Or Cover that is fastened to the neck flange with the help of a set of Eye Bolts by placing a food grade silicon gasket at the interface.
Powder Or any other material loading and unloading Need Not Be Done manually always. There are methods like Vacuum Charging of the material Or Bin Loading etc. Incase of a vacuum charging method, the blender body is vacuumized by applying vacuum externally, and a closed chute is placed in the feed container, which allows the powder to be sucked inside the blender and gets arrested there.
Whereas, incase of a bin blender, a bin full of feed material is attached to the bottom butterfly valve of the blender. The powder falls inside the blender when the blender body is rotated upside down, and the butterfly valve is closed so that powder doesn't slide back in the bin upon bringing in to the original position. Please wait for my next blogpost on Charging and Discharging Methods in the Blender.
3. Blending Mechanism: Both the blenders follows a similar mechanism, i.e. rotation of the Blender Body around a horizontal axis, such that the powder mixture inside keeps shuffling continuously inside. However, the basic difference between the two can be explained with the help of their respective shape, size and geometry.
Incase of an Octagon, the powder particles mostly follows a shearing pattern. Which means, in low rpm rotation, the top most layer of the powder slides down (overcoming the angle of repose) and takes the bottom most position on the surface of the blender. The next eligible layer thus takes the upper position on the recently formed bottom layer. This way the entire powder bed keeps shuffling from top to the bottom. Also, the shallow cone formed at the bottom of the blender forces the powder particles to form cross currents and get thoroughly mixed.
Incase of the Double Cone, the powder particles undergoes simultaneous tumbling and shearing action. Since, both the apexes of the blender i.e. Manhole and Bottom Valve are of much smaller diameter than the central cylindrical diameter, the conical angle formed are steep. This allows the powder mass to contract in volume while the blender is in vertical position (i.e. either the manhole Or bottom valve is up), and expand in volume which the blender is in horizontal position. This way a thorough mixing takes place due to the continuous rotation of the blender body at a low rpm.
4. Space needed, Ease of Operation and Maintanance: Octagonal blenders due to its horizontal volume requires larger space and room. However, cleaning is much easies, as manhole is big enough for a person to enter inside for cleaning Or routine maintenance if any.
Double Cone Blender though can fit in a relatively smaller room, however, need a big headroom. In other words, larger the capacity of the Double Cone Blender, more is the height required for the blender to rotate. Also, cleaning and routine maintenance is slightly difficult (when compared with Octagonal blender), as the shape is complex for a person to enter inside through a manhole.
MAJOR COMPONENTS OF THE BOTH THE BLENDERS IN COMPARATIVE STYLE:
1. Main Bowl Or Container Or Shell with closing lids on manhole and a bottom valve: As discussed above, the Octagonal Blender is essentially a horizontal but octagonally shaped long box (Octagonal shape can be viewed in a cross-sectional or a side view). Whereas, the Double Cone Blender is a box made up of two cones joined to a low height hollow cylinder at the center (lookwise somewhat similar to the RCVD Or Rotocon Vacuum dryer).
2. Drive Assembly: Just like a V Blender, an AC motor along with a suitable Gearbox (mostly hollow shaft) is used for achieving a low RPM with a VFD (Variable Frequency Drive).
Caution: Spur-Pinion gear arrangement is economic and effective, as, blender when stopped suddenly in any position stays locked (meaning doesn't rotate under the influence of gravity), as the gear teeth are locked. However, if you choose to use the Helical Bevel gearbox, electo-mechanical brakes may be needed, as the blender cannot stay in a locked position and tries to automatically achieve the neutral position Or the starting position under the influence of gravity.
3. Supports and Bearings/ Plummer Blocks: The shaft of the blender is mostly supported from both the sides by making an A shaped supports with base plate at the bottom (which are either fixed on the ground Or pedestals by means of anchor fasteners Or are grouted). In rare cases (mostly in small capacity blenders) the arrangement can be Cantilever also, where, the blender is just one side supported. Bearing Or Plummer blocks are used to facilitate smooth, jerk free and easy rotation of the blender.
4. Discharge Valve: Bottom Discharge Valves can be Butterfly Valve, as well as, Rotary valve. One has to be careful about the possibility of the powder leakage and ease of unloading while selecting the bottom discharge valve. Valve can be either manual Or pneumatically actuated.
5. Static Baffle: The Octagonal Blender may have a static baffle inside, which can be effective in disturbing the powder layers and relative positioning of powder particles with each other. However, Double Cone Blenders usually doesn't require a static baffle, as anyways there is very good amount of powder mass volume contraction and expansion keeps happening. Another reason for Not recommending a static baffle inside a Double Cone is that the complexity of cleaning the interiors of the Double Cone Blender because of its size, shape and geometry.
6. Vacuum Charging Arrangement: As mentioned above, both Octagonal Blender Or a Double Cone Blenders can be vacuumized to have the feed powder sucked inside the Blender. However, dusting and material wastage are some of the biggest challenges with the Vacuum Charging.
7. Safety Railing and a Proxy sensor Or Limit Switch: Since both of them are rotary equipments, as per the safety guidelines, the safety railing with a interlocking proxy sensor Or limit switch is provided with each of these blenders. Upon opening the safety railing, the blender motor immediately stops and brings the blender to an immediate halt, thus avoiding any possibility of an accident.
ADVANTAGES AND DISADVATAGES OF BOTH THE BLENDERS IN A COMPARATIVE STYLE :
- Effectiveness: Both Octagonal, as well as, Double Cone blenders are equally effective. The physical properties of the powder Or mass viz. free flowing nature, moisture content, bulk density and flow patterns adopted by the particles can best decide the most appropriate blender. This study must be done by the process people taking the machine vendor in confidence.
- Space occupied: Octagonal blender needs more of horizontal space, whereas, Double Cone requires more of a vertical space Or a headroom.
- Batch Size: Practically, the Octagonal Blender is used for handling bigger size batches, then the Double Cone Blender.
- Simplicity of Operation: Both the blenders are equally easy and simple in operations. Whether PLC-HMI operated Or Push Button type Panel operated, both are extremely easy to use.
- Easy of Automation: Level of automation is mostly Non-Complex Or Straightforward.
MATERIAL OF CONSTRUCTION:
Very Nice info...
ReplyDeleteWell explained
ReplyDeleteSimple to understand
Post a Comment