Page 207 - Industrial Ventilation Design Guidebook

4,4 WATER PROPERTIES AND TREATMENT 1 69

Properties of Solid Being Extracted

• Temperature of decomposition
• Solubility
• State of subdivision
• Surface absorptive properties
• Elasticity
In some cases, fragility related to the dryness of the resultant solid, which
will influence the removal technique

Relationship between Liquid and Solid

• Mechanically held liquid
• Liquid absorbed on solid surfaces

Removal Efficiency Required. This depends on design requirements and
current legislation.

Requirements for Regeneration

• Of liquid
• Of solid
• Of both liquid and solid

Equipment Availability. In many cases the equipment is not available "off
the shelf," and the delivery time may be lengthy; hence, adequate planning is
necessary to ensure that the commissioning date can be met with the plant se-
lected.
4.4.4.3 Heat Transfer Fluids
It is prudent at this stage to briefly consider the problems that can be expe-
rienced in either refrigeration or heat recovery systems when water treatment is
required to prevent freezing. The antifreeze treatment of pure water may be
achieved by various means, typical ones being various brines, ethylene glycol,
and propylene glycol.
In the treating of water by any of these methods, it must be remembered
that due to property changes, they can cause problems on both the heat
transfer characteristics and fluid flow characteristics compared with pure
water.
Many proprietary trade heat transfer fluids are in common use. Depending
on operating temperatures, typical characteristics are

• Density from 600 to 1100 kg irr 3
1
• Specific heat capacity from 1.12 to 2.75 kj kg" K
1
• Thermal conductivity from 0.1 to 0.29 W irr K.
• Boiling points up to 340 °C at atmospheric pressure
• Freezing points down to -15 °C