Exam Question

### (a) Causes of an Uptake Fire (6 Marks)
An uptake fire, often referred to as an economizer or exhaust gas boiler fire, is primarily caused by the ignition of unburnt fuel oil and carbonaceous deposits accumulating within the exhaust gas path of a boiler. The primary causes are detailed below:
* **Incomplete Combustion:** This is the most significant root cause. When fuel oil combustion within the main boiler furnace is inefficient or incomplete, unburnt fuel particles (hydrocarbons) and soot (carbon deposits) are carried over with the exhaust gases into the uptake, economizer, and potentially the exhaust gas turbocharger (for main engine systems).
* **Poor Atomization:** Malfunctioning fuel injectors (worn nozzles, incorrect opening pressure, carbon trumpet formation) lead to large fuel droplets that do not fully combust within the furnace, depositing in the uptake.