Saturday, 6 April 2019

Ribbon Blender: Construction, Operation, and Applications

          RIBBON BLENDER (or) mixer machine is widely used for dry powder, Grannules, Low-viscosity paste and liquid in chemicals, food and cosmetics industries. It is particularly appropriate for combining solids and solids with liquids, Approximately two third of the volume of the container of ribbon blender is stuffed to make sure proper mixing.
           The Ribbon Blender can be used in either batch or continous flow form to achieve even and homogeneous blending.

Construction & Operation:
          Ribbon blender consists of a "U"-shaped trough containing a double helical ribbon mixer that rotates inside. The blender's shaft is positioned within the centre of the through and has welded spokes on that helical ribbons (also referred as spirals) are welded. Since the agitator consists of a group of inner and outer hical ribbons, it is saaid as a "double" helical ribbon agitator. The gap between the ribbon's outer edge and the interwalls of the vessel ranges from 4 to 5 mm depending upon application.

          Generally the ribbon blender is powered by a drive system consists of motor, coupling, and gearbox. For blending 500-1000 kg of product a 10 HP to 15 HP  motor is used.
          The agitator shaft exits the blender container at either end through the end plates secured or welded to the container. The area where the shaft exists the container is given a sealing arrangement to make sure that material doesn't travel from the container to the outside and vice-versa.
          The charging of material is generally done through top cover, the cover also containes cleaning and maintenance access. The material is to be blended are loaded into the blender upto 40 to 70 % of the total volume of container. This is generally up to the level of the outer ribbon;s tip. Depending upon the application the agitator is designed to operate at pheripheral speed (also called as tip speed) approx 100 mtr/min.
          During blending, the outer ribbons move the material from the ends to the centre while the inner ribbons move the material from centre to ends. Radial movement is achieved because of the rotational motion of the ribbons. The difference in the pheripheral speeds of the outer and inner ribbons results in axial movement of the material along the axis of the blender. As a result of cobining motions of these homogenious blending is achieved in short time. The efficiency of the blender depends on particle size, density and quantity.
          After blending, the material is discharged form discharge valve located at the bottom of the through. The discharge can be fitted with any kind of valve like slider gate, butter fly depending upon the material. The operation of valve can be done by manual or automatic.
          The motion of the ribbons near the walls can result in "pinch" points, or regions of higher shear and compression, which may damage fragile material. In some cases this can leads to friction and heat generation resulting in product degredation.
          An alternate design to the ribbon blender is paddle agitator, which can handle fragile material. The paddle agitator is composed of both forward and reverse paddles in place of the ribbons. The paddles are positioned to  ove the material in opposing lateral direction as well as in a radial direction. The ribbon design is appropriate for low and medium duty applications, hile paddle design is suitable for heavy duty applications. In some cases we can see hybrid-design like paddle and ribbon agitator.

Name plate details:

Blending Capasity1 m3 (300 kg) or 1.8 m3 (500) kg
Motor Capasity7.5 KW (10 HP) or 11 KW
Speed rates20 RPM
Weight1.5 Ton or 2 Ton
MakeEx:Alpha Factory Automation Ltd

1) Blending large amount of dry solids.
2) Dry blending of capsule formulation.
3) Cooling, drying, heating of materials.
4) Blending of chemicals.

Materials commonly blended are:
Plastic resigns
Epoxy resigns
Face powders
Instant drink blends
Talcum powders
Laundry detergents

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