4.3.4 Exhaust Gas Heat Recovery. Exhaust gases discharged from diesel
generators range in temperature up to approximately 600deg. F (316deg. C) at
full load. The temperature depends on the size of the unit, the fuel used,
and the combustion cycle (i.e., 2 or 4 stroke engines). Larger engines
operate at lower temperatures. Exhaust gas recovery systems include the
a) Heat is recovered in the form of hot water or steam in a heat
recovery boiler which also acts as an exhaust silencer. These devices are
often referred to as "Heat-Recovery Silencers." Heat recovery boilers
receiving exhaust gas shall be designed to run dry when there is no thermal
load. Diverter valves shall not be used.
b) Hot water cogeneration is often preferred over steam systems.
Advantages include ease of process control, independent of operating
temperatures which are critical for low pressure/temperature steam
c) Some process configurations use heat recovered from jacket and
lubricant cooling systems to preheat heat-recovery boiler feedwater and fuel
d) Combined cycle applications are often used to generate additional
power and to produce hot water or to lower steam pressure for usage.