Introduction to Process Heaters
Normally you get involved in process heating because:
- An existing element has performed to expectations but has finally failed due to its useful life-cycle
- An existing element has not performed to expectations or there is more awareness of potential energy savings options.
- A new process needs to be designed.
Analysis of application parameters like watt density, sheath material, efficiency and type of control may indicate that the system needs to be redesigned. Other examples:
- To reduce maintenance and operating costs, replacing cartridge heaters with split-sheath cartridge heaters
- Changing to a different sheath material like Incoloy (which can be used for higher watt density) and therefore may increase heater life
- Replace the electromechanical relays with solid state relays or SCR to improve heater life.
In any case, heater selection is one of the most important steps, but not the first one when designing a heating process. The proper steps are:
- Calculate required wattage for start-up
- Calculate required wattage for process operation
- Calculate required wattage to replace heat loss
Once these basic requirements are known, we then can proceed to: