Reasons why marine Oil Boiler Back Fire
In most cases, boiler back firing may occur during normal operation, which place a high risk to the ship and her operators.
On this article, I’m going to list the major things that may lead to boiler back firing. But firstly, lets understand the basic types of boilers which are use on board ship.
As per normal standard on shipbuilding, most vessels with engine above 3000kw usually built in with boilers, for the purpose of fuel heating, jacket water warming, etc. The boilers which are usually installed on board ships are basically two types ;
Types of ship boiler
This type of boiler maybe install on board ship as an auxiliary or main propulsion boiler.
As per fire triangle, which comprises of ; Fuel, oxygen and Ignition, this type of boiler is built with separate burner made up of electric motor ( which drives the fan and fuel pump), ignition electrode , injection nozzle and nozzle housing…… Read more details on Oil boiler here
Exhaust or Economiser boiler ;
Since the exhaust outlet of the main marine diesel engine is of high temperature, it’s utilised by installing tubes in an expanded area away after the turbine.
While the exhaust passes through these tubes, it heats the fluid ( thermal oil or water) inside it. According to some ship builders, they provide bypass flaps valves, which gives you the possibility to send the exhaust out without passing through the tubes.
Futhermore, as you may know, the method of producing steam, the mentioned above process, helps us to achieve steam or heat.
Now, when we talk about boiler back fire, it always happen on oil boiler. This back fire happens as a result of the followings ;
Cause of boiler back fire
Clogged boiler exhaust gas outlet ;
Regular cleaning of the boiler furnace is very recommended, to remove carbon deposits between the tubes. This will allow proper blow through to avoid excess gas in the furnace , which may find it way out when fuel and ignition applies. Note, this could lead to explosive or fire hazards in case the boiler is not being stop as fast as possible.
Blower flap full open;
Sometimes, the blower flap regulator may went out of order ( defective ), instead of reducing the air flow to 30….90% before ignition time, it will remain on same blow through window. It’s important to regularly inspect the performance of this flap regulator motor.
Nozzle leakage or fuel drop back;
Depending on the makers recommendations, nozzles are meant to spray some …..mm distance away into the funnel where burning take place. Therefore having some leakage behind may lead to fire drowning backwards.
Low oil pressure or too much oil deposits in the firing chamber;
Low fuel pump pressure can also result to nozzle not able to spray fuel away as required. Check fuel pressure and maintain as per makers recommendations.
Air regulator micro switch malfunctioning:
This is a very important and most dangerous point you need to check always. Let’s say you are using HFO ( havey fuel oil ) to run your boiler,and the air regulator purging timing is less than normal required time and air pressure for deposited fuel purging, it can lead to explosion or back fire in case there are remains of fuel vapour inside the boiler furnace and your ignition turns on.
With all of the above mentioned causes of boiler back fire and remedies, I strongly believe that you can be able to solve problems in relation to back firing of the auxiliary or main boiler.
If this article helps you, let’s have your comments below. Also you can share to friends who maybe in need of this article.
Also take safety first to avoid accidents or fire hazards. Proper watch keeping is always important onboard.