To not invest money in worthwhile projects makes as much sense as not depositing your paycheck. In this column, we will briefly look at energy and gas “checks” you might have received in the mail but have yet to cash.
This column is a Combustion Corner feature written by John Clarke, technical director at Helios Electric Company, and appeared in Heat Treat Today’s February 2022 Air & Atmosphere Furnace Systems print edition.
If you have suggestions for savings opportunities you’d like John to explore for future columns, please email Karen@heattreattoday.com.
Technical Director
Helios Electric Corporation
Source: Helios Electrical Corporation
The late Fred Schoeneborn, a long-time energy consultant and friend, described energy savings opportunities that have been identified but not exploited as uncashed checks. To expand on Fred’s metaphor, not to look for opportunities to save natural gas is the equivalent of not collecting and opening your mail.
A furnace or oven is a box that contains the work being processed and the heat used in the process. It is an imperfect box because we are always losing heat. While it is imperfect, there are often opportunities to improve your oven’s performance, saving energy and generally improving quality. (You may notice if you have read a few of my columns, energy savings and quality improvements nearly always coexist.)
At the start of this series, we asked several questions. This time we will consider the following:
- Is my furnace or oven at the correct internal pressure?
- Is it time to rebuild door jams?
- How much fuel is wasted because I am not containing heat within the furnace or letting excessive air reduce my combustion efficiency?
Furnace pressure (in a non-vacuum application) is the simple function of the volume of the material introduced vs. the area of all the openings in our box. The obvious inputs are the products of combustion for direct fired systems, or the atmosphere for indirect systems.
What is the optimum pressure for my system? In general, the best pressure is the lowest pressure at which no tramp or unwanted air can enter the system and contaminate the atmosphere or upset the temperature uniformity. The lower the pressure, the less chance we will have excessive losses around door seals or other furnace penetrations. Most commonly, these pressures are measured in the hundredths or tenths of inches of water column.
In many applications, door sealing surfaces or jams take quite a beating. Their maintenance is expensive in terms of money, labor, and lost production. Expensive, yes, but the cost of NOT maintaining these surfaces may be much more. Losses are a result of radiant and convective losses, but most significantly, product quality because of atmosphere contamination or areas of the furnace not reaching setpoint temperature. When should we maintain these surfaces? In general, the best results I have observed are people who schedule surface maintenance periodically based on wear and available furnace downtime.
Calculating the savings from these fuel savings is more difficult, but in general, maintaining a consistently uniform interior work area saves more than the energy conserved.
About the Author:
John Clarke, with over 30 years in the heat processing area, is currently the technical director of Helios Corporation. John’s work includes system efficiency analysis, burner design as well as burner management systems. John was a former president of the Industrial Heating Equipment Association and vice president at Maxon Corporation.
