The popular media promote a plethora of energy-reduction ideas for consumers (light bulbs, thermostats, screen savers, weather stripping, etc.) and precious few for industry. Since industry consumes 33% of the natural gas, 25% of the renewable energy, 23% of the petroleum and 8% of the coal produced in the U.S. (2011 statistics), this absence might appear to be a major lapse in editorial judgment by the pop-culture pundits.

On the contrary, energy reduction in the industrial sector, while rich with money-saving potential, usually involves a higher level of nuance and narrower applicability than the common denominators typically understood by mass media and the public. In industry, the bulk of energy goes into processes – many of which are chemically and mechanically complex and involve safeguards that must not be disregarded. Below are some examples of how higher levels of risk may accompany energy-saving process changes.

Exhaust-Gas Heat Recovery
Adding a recuperative or regenerative heat exchanger to a combustion process can save energy by preheating the combustion air and simultaneously reducing the temperature of wasted exhaust gases. However, there are risks associated with these process changes in some systems, including burner instabilities due to excessive turndown or disproportionately high temperatures if firing rate can’t be turned down safely.

Exhaust-Gas Flow Reduction
Flue-gas recirculation (FGR) and oxygen-enriched combustion are two contrasting methods for reducing waste of hot gas exhausted to atmosphere. Oxygen-enriched combustion reduces the nitrogen content in the exhaust stream and thereby eliminates the waste of a significant portion of the hot gas stream. In order to transfer the same amount of heat to the load, however, the resulting higher flame temperatures are capable of damaging the burner or furnace. Conversely, FGR is capable of delivering the same amount of heat to a load with reduced exhaust-gas waste and without excessive flame temperatures. Unfortunately, FGR reduces oxygen in the furnace and may cause flame instabilities, nuisance shutdowns or worse.