Proper insulation in your industrial process oven can be the difference between efficient production and costly energy losses.

High temperature insulation is available in numerous materials and forms.

When designing ovens for process heating applications, insulation typically is the last and least considered area. Insulation isn't sexy. It cannot think for the operator like a controller can. It can be itchy. And those who handle it have to wear a hot, sweaty mask and other protective apparel that might be considered uncomfortable. As a result, some industrial process ovens might not be as well insulated as they could or should be.



Table 2 shows the insulation thickness used to calculate heat savings.
Note: This table is not a table of recommended thicknesses. It represents only a table suitable for a particular type of insulation, ambient condition, surface emmittance and air movement. These tables 14, 15, 16, 17, 18, 19, 20, 21 and 22 all are based on this single condition, which is not representative of any particular set of conditions for industry. This is only presented to illustrate how economics of insulation should be determined.
Source: Thermal Insulation Handbook

Keeping the heat in your process oven is important for a number of reasons. Temperature control, safety, environmental pollution and energy conservation are the big ones. For good reason, we tend to spend most of our time and energy on achieving proper temperature, environmental and safety controls. As energy prices continue to climb, better energy conservation and the economic benefits of insulation thickness should be examined.

Parameters to consider when choosing the insulation type, vapor barriers and cladding for each process heating application include:

  • Hot face (process) temperature (maximum and normal operation).

  • Average ambient cold-face temperature.

  • Indoor or outdoor.

  • Space considerations.

  • Vibration.

  • Moisture and corrosion potential.

  • Installation configurations.

  • Thermal conductivity requirement.

  • Wind factor.

  • Removability requirement.


Table 3 shows heat loss data from bare surface area on NPS piping and flat surfaces.

Because most process heating applications operate above 212oF (100oC), I will confine my discussion to insulation types for with use temperatures at or above 212oF. High temperature insulation is available in numerous materials and forms, including fiberglass, mineral wool (basalt), high purity silica (quartz), ceramic fiber, calcium silicate and expanded perlite (table 1).

After the insulation type has been selected, thickness requirements must be determined. Except when there is a limited space requirement, the most economical insulation thickness should be used. This thickness will yield the best return on investment. Table 2 shows the insulation thickness used to calculate heat savings. Table 3 shows heat loss data from bare surface area on NPS piping and flat surfaces. Table 4 shows heat loss after an appropriate type and insulation thickness has been specified. For the most part, heated processes should be designed to have the insulation perform to a 95 percent or better efficiency level. Considering this, based on energy costing $5 per million BTU, table 5 shows the dollars per square foot that will be lost per year from bare, uninsulated metal surfaces. If the equipment is outdoors and exposed, it can get wet, and the energy dollar loss goes up even more.

Table 4 shows heat loss after an appropriate type and insulation thickness has been specified.

Dry Run, Training

After the insulation type and thickness have been determined, it is critical that the insulation remain dry whether the process is operating or not. If the insulation is allowed to get wet, it will lose about 90 percent of its insulation value. In addition, corrosion problems will begin once moisture enters your insulation system. Specifying and installing a good vapor or moisture barrier that is maintained properly will accomplish the job of keeping the heat in your oven.

Table 5 shows the dollars per square foot that will be lost per year from bare, uninsulated metal surfaces.

North American Insulation Manufacturers Association (NAIMA) and National Insulation Association (NIA) offer training programs that teach how to determine proper insulation practices. Each offers 3 E Plus, a software program for determining heat loss and the most economical insulation thickness.

For more information about NIA or NAIMA training class schedules or to purchase 3 E Plus software, call 703-683-6422 or visit www.insulation.org.

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