Liquid mixing

This is about Liquid Mixing

1. Welcome to our presentation on Liquid Mixing Course Title: Pharmaceutical Engineering Course Code: PHR-320

2. Represented By………. Rupom Mitra Kazi Nadim Hossain Md. Anin Nayeem

3. Liquid mixing Definition Classification Importance Miscible liquid Partially miscible liquid Immiscible liquid

4. Mechanism Bulk Transport Turbulent Mixing Laminar Mixing Molecular Diffusion ------- Motor Shaft Lid Outlet Impeller Baffle Jacket Inlet Mixing Vessels Mixing vessels

5. Mixing Devices Propellers a. Top View b . Side View Fig: Propeller type of mixing devices. A 3 bladed design

6. Turbines 30-50% of diameter of vessel Speed 50-200 rev/min Uses Used in very viscous ranges up to 700 P.s Can handle slurries with 60% of solids Advantages Suitable for Emulsification Different types of turbines

7. Flow pattern during mixing 3 types Tangential or circular flow: Direction: tangent to the impeller shaft 2. Radial flow: Direction: Vertical to the impeller shaft 3. Axial flow: Direction: Parallel to impeller shaft

8. Vortex formation Cause: Shaft mounted vertically in the centre of the tank Turbines arranged perpendicular to shaft High impeller speed Unbaffled tank Disadvantages Low mixing Air bubbles contamination Oxidation of compounds Prevention of vortex Avoid symmetry Off centre Inclined Side entry Baffeld containers More impeller Cylindrical Tank (Dead spots)

9. Return Flow with Draft Tubes Draft tubes are placed to control the direction and velocity of the flow to the the impeller These are mounted around the propeller. In case of turbines , drufts tubes are mounted immediately above the impeller Uses: Used in Manufacture of certain emulsions.. Airjet mixers for mixing of liquids employ draft tubes. Disadvantage: Draft tubes add to the fluid friction in the system that reduce the rate of flow.

10. Equipment For Liquid Mixing Air jet mixer Jet mixer Flow mixer or line mixer or pipe

11. Airjet Mixer Principle : when compressed air jets are passed from thr bottom of a vessel,air bubbles are formed in the liquid phase.The buoyancy of the bubbles lifts the liquids,which are confines to the central portion due to the presence of drat tubes The floatage of the bubbles lifts the liquids,which are confined to the central portion due to the presence of draft tubes . Construction: Compresses air or suitable gas is allowed to pass at high pressure from the inlet provided at the bottom of the tank. This causes buoyancyof the bubbles which lifts the liquid from bottom to the top of the vessel Use: liquids of low viscosity, non foaming, non reactive with gas are mixed by using airjet mixer.

12. Jet mixer Principle: The liquids to be mixed are pumped separately into a jet mixer at different velocities. During mixing the slow moving liquid will be drawn at high velocity jet. This increasess the volume of the jet and decreases velocity,which causes to jet to expand . Conruction : It consist of a vessel and a mixing device known as jet   A typical jet mixing system has 12 jets arranged radically in a cluster in the centre of the mixing tank.The cluster of jets is called an eddy jet mixer. Av individual eddy jetmixer has two concentric nozzles with a suction chamber between them. Advantage : The power required for pumping is often sufficient to complete.

13. Flow Mixer or Line Mixer or Pipe Mixer It may consist of a baffled pipe or an empty chamber Liquids to be mixed are passed through the pipe or chamber Mixing takes place through bulk transport in the direction of flow The power supplied to pump the liquid itself accomplishes mixing. For effective mixing controlling the feed rate is essential.   If the input rate is difficult to controland fluctuations in the added proportions of the liquids are unavoidable,contious mixing equipment of tank type is preferable. Uses : When large volume of liquids are to be mixed,flow mixers are used.

14. Thank You All