These hot water and steam boilers are conventionally-fired boilers based on a 3-pass design, with an additional separate integrated smoke tube pass for waste heat utilisation. They are primarily used in combination with CHP units or gas turbines. The waste heat system uses hot flue gases from upstream combustion processes to assist in the generation of thermal or process heat.
Additional peak load boilers are normally required if waste heat boilers without an auxiliary burner are used. It is often superfluous due to the self-firing functionality. This allows huge amounts of money, space and equipment to be saved.