WHAT IS 'V BLENDER':
V Blender is a popular type of a solid - solid (mostly dry powders) blender which works on the principle of diffusion mixing by tumbling action. A closed V shaped container (which has two symmetrical arms forming a V shape) is assembled to rotate between two supports with the help of an AC motor at low RPM, allowing the powder particles to mix under the influence of gravity and tumbling action.
WHERE AND WHY IS IT USED:
V Blenders are popularly used in Pharmaceutical Manufacturing, where various APIs Or Formulation powders needs to be blended. Many a times, V blenders are used in Granulation Process as an alternative to other types of blenders like Double Cone Or Octagonal Blender.
MATERIAL OF CONSTRUCTION:
MAJOR COMPONENTS OF THE V - BLENDER:
1. V Shaped Container Or Shell with closing lids for both the arms: This V shaped vessel constructed has two symmetrical hollow arms forming an Angle Or a V. The bottom of the V has a very small straight vertical cylindrical portion, which has the discharge butterfly valve at the open end Or the bottom end. Whereas, both the arms has closing flanges Or dead plates attached at the open end of each arm by means of a triclover clamp.
2. Drive Assembly: An AC motor along with a suitable Gearbox (mostly hollow shaft) is used for achieving of a low RPM (usually in the range of 10 to 12) without a VFD (Variable Frequency Drive). Note: while choosing the gearbox, one has to keep in mind that the Helical Bevel gearboxes do not have a provision to lock the gears in a stopping position incase of sudden power failure, hence, electo-mechanical brakes may be needed. To avoid this problem, many a times a spur-pinion gear arrangement is used, as it is economical and doesn't need any kind of a brake mechanism.
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 and Feeding Arrangement: Usually a Butterfly Valve is used as a discharge valve, and is fixed to the open end of the cylindrical part attached to the V. This valve can be either manual Or pneumatically actuated. One can use the same opening for feeding the blender by attaching a bottom feeding vessel (vertical cylindrical vessel with neck flange matching the blender bottom flange). In such a case, the feeder vessel (filled with powder) is attached to the bottom flange of the blender by means of a triclover clamp. Upon attaching, the blender is rotated by180 degrees and a position is achieved, where the V angle comes on the top and the feeder is upside down resting on the V. In this position, the powder falls inside the blender due to gravity. Soon the butterfly valve (which was kept open) is closed, and the blender is rotated back to the original position, so that the feeder comes back on the ground. It is detached from the blender by opening the TC clamp, while, the butterfly valve is off.
5. Intensifier: The intensifier is a special arrangement of an inside protruding high speed chopper (i.e. an assembly of small metal rods welded to the central metal shaft, which is driven by an AC motor coupled with the gearbox). The role of an Intensifier is to facilitate fast and turbulent mixing of the powder in the local zone. While the tumbling action inside the main blender yields a slow and consistent blending, the Intensifier breaks any kind of lumpy situation and ensures that the powder gets vigorously mixed. This also ensure that powder particles (travelling two and fro) gets a push to travel across the blender i.e. from one arm to another, thus creating uniform mixing/ blending.
6. Vaccum Charging Arrangement: Just like an Octagonal Blender Or a Double Cone Blender, V Blender can also be vaccumized and thus powder can be 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 it is a rotary equipment, as per the safety guidelines, the safety railing with a interlocking proxy sensor Or limit switch is provided with the blender. 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 OF A 'V' BLENDER:
- Effectiveness: The V blender is more effective as compared with other types of blenders such as Octogonal Blenders, Double Cone Blenders etc. This is so because the powder gets more confined space to travel inside a V blender.
- Gravity Advantage due to rotary motion and V type shape: The rotary motion allows very good shuffling and mixing of the powders due to the tumbling action.
- Occupies less space as compared with Double Cone Or Octagonal Blender: V blender due to its shape and geometry occupies much lesser space.
- Simplicity of Operation: Operating this equipment is no different than operating any other pharmaceutical blender. Whether it is PLC-HMI operated Or Push Button type Panel operated, it is extremely easy to use.
- Easy to Automate: Level of automation is mostly Non-Complex Or Straightforward.
- Cleaning and Maintenance: Due to its shape, size and geometry, it is at times challenging to do washing, cleaning and mechanical maintenance (if any) from inside.
- Batch size cannot be very big: Since feeding and unloading a large quantity of the material can be really time consuming, usually smaller size batches (not more than 2000 ltr) are only taken in a V blender.
- Design related challenges: If the operating room has height limitations, the capacity too may have limitations.
Post a Comment