ABSTRACT
Technology is now available to increase heater efficiencies to 92% and better. The single, most significant obstacle to overcome in this application is high flue-gas dew points attributable to low concentrations of S03 from sulfur in the fuel. New curves are presented showing flue-gas dew points versus percent sulfur in both oil and gas fuels. Various techniques to achieve these high efficiencies are presented. Their limitations are discussed along with up-todate methods of dealing with corrosion when the flue-gas dew point is encountered. Recent studies have shown that a minimum efficiency of 92% can be justified on heaters as small as 5 MMBtu/h with payouts below 3 years using $2.50/MMBtu fuel costs. Fuel costs will again rise, and many companies feel that $4-$5/MMBtu values are only a few years away. Based on the information presented, a minimum efficiency of 92% should be considered for all applications.
