Selection of Mixers
Conference of PPA –C 2012
Selection of mixers – Although many mixers are capable of mixing different types of liquids, solids, paste, and other materials, the process of selecting a mixer remains an art because of the many variables involved. The process of selecting and identifying the mixer which delivers the required mixing performance in minimum time, greater product yield and with minimal overall cost is critical. For any application, a variety of mixing equipment can be used. It is therefore necessary to clearly define the process and production objectives that are relevant to the mixing operation.
Mixer selection is carried out taking into consideration several criteria such as:
- Material characteristics – Physical, Chemical and Mechanical properties of the material to be mixed are the most important considerations.
- Mixer operating conditions - Mixers can be designed to operate under pressure and vacuum conditions. Some mixers would need to be provided with heating and cooling arragement as per the process requirements.
- Mixing homogenity and accuracy - Some mixers are more accurate in terms of delivering a better homogenity. High levels of mixing homogenity and accuracy are required for critical applications such as pharmaceutical products, speciality chemicals, explosive materials, etc. In other cases, lower degree of homogenity may be acceptable.
- Process setup – The process set up includes the following factors:
- Quantity of the different material to be mixed
- Material-handling equipment
- Mode of equipment operation: batch or continuous
- Preblending and postblending material storage
- Performing multiple processes in the mixing equipment (liquid addition, drying,coating)
- Charging and discharging of the material from the mixer
- Mixer cleanability – Mixer cleanability is critical in applications such as products related to food and pharmaceutical industry, mixing of colour master batches,etc. The requirement of mixer cleanability should be clearly defined and taken care of at the design stage in terms of mixer internal surface finish, seal design, impeller clearances, and so on.
- Capital cost of equipment – Cost associated with purchase of new mixer and related accessories for operation.
- Operating cost of the equipment – such as cost of power, maintenance cost.
Other factors such as plant layout, operational convenience, equipment safety should also be considered.
Mixing Expert can assist you in selecting a mixer best suited for your product application.