Fire Tube Boilers

I Overview
Fire tube boilers represent one of a number of pressurized equipment options used to heat water or convert water into steam under controlled conditions. In fire tube boilers, combustion gases pass inside boiler tubes, and heat is transferred to water on the shell side.

II Applications
Fire tube boilers are most commonly used where required steam pressures do not exceed 300 psig.

III Equipment Options
Fire tube boilers are often characterized by their number of passes, referring to the number of times the combustion (or flue) gases flow the length of the pressure vessel as they transfer heat to the water. Each pass sends the flue gases through the tubes in the opposite direction. To make another pass, the gases turn 180 degrees and pass back through the shell.

The turnaround zones can be either dryback or water-back. In dryback designs, the turnaround area has a refractory lining. In water-back designs, the turnaround area is water-cooled, and does not need the refractory lining.

IV Resources
1. Equipment Manufacturer Database
2. Boiler Burner Consortium