Q1: Forced circulation evaporators are normally used for concentrating liquids having

ANS:C - both(a) & (b)

1. Scaling Characteristics:
   • Scaling refers to the deposition of inorganic salts or minerals from the liquid onto the surfaces of the equipment during the concentration process.
   • These salts or minerals can precipitate out of solution as the liquid is concentrated, forming scale deposits on the heat transfer surfaces of the evaporator.
   • Scaling can occur when the solubility of the salts or minerals is exceeded due to evaporation or changes in temperature or pH.
   • Scale deposits reduce the heat transfer efficiency of the evaporator, leading to decreased performance and increased maintenance requirements.
   • Certain types of evaporators may be more susceptible to scaling, depending on factors such as operating conditions, fluid composition, and equipment design.
2. High Viscosity:
   • Viscosity refers to the resistance of a fluid to flow.
   • Liquids with high viscosity have a thick, syrupy consistency and flow more slowly compared to liquids with low viscosity.
   • High viscosity liquids have poor flow characteristics and can be challenging to handle in evaporator systems.
   • In evaporators, high viscosity liquids may experience difficulty in circulating through the evaporator tubes, resulting in reduced heat transfer efficiency.
   • Forced circulation evaporators are often used for concentrating high viscosity liquids because they use mechanical pumps to overcome the resistance to flow and ensure efficient circulation.
   • Examples of high viscosity liquids include concentrated sugar syrups, molasses, and some food products like fruit purees and sauces.

In summary, scaling characteristics refer to the tendency of certain substances to form scale deposits during evaporation, while high viscosity relates to the thickness and resistance to flow of a liquid. Both factors can influence the choice of evaporator type and operational considerations in industrial processes.