Parasitic Loss

Measuring the "Parasitic" Costs of Oil-Fired Industrial Boilers

In determining cost advantages between oil and natural gas, boiler operators traditionally determine efficiency based on "stack loss." Unfortunately, this method ignores losses and costs associated exclusively with oil-firing. These expenditures, categorized as Thermal Losses and Operating Losses, are generally not quantified.

Recent research quantifies losses and costs

A recent research project conducted by Dr. Herbert M. Eckerlin of North Carolina State University, deals with these costs in a detailed and convincing manner.

A total of 67 boiler installations ­ of which 41 were for industrial applications ­ have been tested to date and the results form the basis for the following report.

We are grateful to Dr. Eckerlin for his cooperation in preparing the material and permitting its publication in this format.

It is not unusual to hear a plant manager or purchasing agent claim that, "My boiler operates 4 to 6 percent more efficiently on oil than on natural gas." This evaluation, however, does not include the "parasitic" losses and costs commonly associated with oil-fired boilers. Without an accurate method of measuring and evaluating these often-ignored expenses, a precise comparison of total costs between the two fuels cannot be achieved.

Research assesses impact of parasitic losses on bottom line costs

The study conducted by Dr. Eckerlin classifies parasitic losses of oil-fired boilers into two primary areas and assesses their impact on bottom line costs. These two areas are Thermal Losses and Operating Losses.
The evaluation of other costs, such as heat loss from oil storage tanks, and corrosion and maintenance costs, were too time-consuming and were not considered in the initial program. Dr. Eckerlin hopes to evaluate industry averages for these losses in a future study.

How the research study measured boiler efficiency

Having gathered appropriate data from 67 oil-fired boiler installations, Dr. Eckerlin expanded on the traditional approach of measuring boiler efficiency. Rather than subtracting all losses from a base of 100, he used three yardsticks:

• Stack Loss Efficiency ­ based on 100, minus stack losses
  

• Total Thermal Loss Efficiency ­ based on 100, minus thermal losses (including stack losses)
  

• Overall Efficiency ­ based on 100, minus total thermal losses and operating costs
  

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