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Process heating and drying applications vary, with different industry sectors requiring different temperatures of heat.
- Low Temperature (30oC-100oC)
Uses of low temperature process heating include drying, curing, fermentation and laundering. These processes use warm air or water to provide process heat, although in the case of drying, higher temperatures may be needed for some applications.
- Medium Temperature (100°C-250°C)
Uses of medium temperature process heating include dyeing, sterilisation, cooking and baking. These processes generally use warm air or water as the means for heating.
- High Temperature Process Heating (250°C-1200°C)
Uses of high temperature process heating include kilns, glass manufacture and metal foundries. These processes generally use heat provided by gas and oil burners, and electrical heating.
There are a number of sources of process heat with varying temperatures and uses.
- Warm Air
Warm air has a limited capacity to hold heat. It is generally used for the lower range of process heating, and one of its many uses is for drying activities where it supplies heat and removes water.
- Hot Water
Water has a good capacity for holding heat, particularly in comparison with air.
- Hot Oil Heating
Hot oil is used where a higher temperature range is needed that can’t be achieved with water.
- Steam
Steam is the most widespread process heating medium. Steam can contain considerable amounts of heat, especially if condensed.
- Direct Combustion Heat
This is an efficient means of heat transfer, but the combustion material can contaminate the product, and this process cannot be used if the product is flammable.
- Direct Electrical Heating
This is also an efficient means of heat transfer, and in addition is clean, but electrical heating is usually expensive.
- Indirect Combustion Heating
This is where the combustion process is separated from the material to be heated by a wall or tube. It is less efficient than direct combustion, but the product will not be contaminated and it can be used if the product is flammable.
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