Skip to main content

Boiler furnace blowback

Cause of Boiler furnace Blow Back

Main cause of boiler furnace blow back is accumulation of hydrocarbons inside the furnace. Hydrocarbons may exist as vapours or liquid form inside the boiler furnace. Accumulated fuel vapours inside furnace catches fire and develops high pressure inside the furnace thereby resulting in dangerous explosion. It is a usual practice that when there is frequent flame failure, operator try to fire the boiler in manual mode. In manual mode pre purging is not automatically controlled. Hence an attempt is made to fire boiler with insufficient pre purging time and eventuality may be catastrophic explosion.

Preventive Actions

  • Allow sufficient time for pre purging the furnace with dampers full open to ensure all the accumulated vapours are expelled out.
  • Purging to be carried out 5-6 times the furnace volume for effective expelling.
  • Never try to reduce purging time or bypass it.
  • Carry out boiler burner and swirler routine as per planned maintenance system.
  • Do not fire boiler with heavy fuel oil or sludge if it is not designed for the same.
  • Air fuel ratio of oil compound regulator to be adjusted correctly to maintain proper and complete combustion.
  • Pilot burner to be maintained in good condition so that flame failure while starting does not occur.
  • Igniter or ignition transformer, its leads, etc. to be properly insulated and tightened.
  • Fuel oil fed to the boiler to be properly treated as per manufacturer’s recommendations.
  • If an economizer or pre heater is fitted in the boiler exhaust, same to be water washed and inspected regularly to avoid back pressure of gases.
  • Conduct furnace inspections periodically to inspect conditions inside.
  • When a flame failure is experienced find and rectify the root cause. Do not try to fire again and again.

Comments

  1. Extremely useful information which you have shared here about furnace. This is a great way to enhance knowledge for us, and also beneficial for us. Thank you for sharing an article like this.
    Chicago duct cleaning company

    ReplyDelete
  2. Should a technician check the transformer when they are cleaning the furnace?

    ReplyDelete
  3. This comment has been removed by the author.

    ReplyDelete

Post a Comment

If you have any doubts.Please let me know

Popular posts from this blog

Differences between MC/MC-C and ME/ME-C engines

The electrohydraulic control mechanisms of the ME engine replace the following components of the conventional MC engine: Chain drive for camshaft Camshaft with fuel cams, exhaust cams and indicator cams Fuel pump actuating gear, including roller guides and reversing mechanism Conventional fuel pressure booster and VIT system Exhaust valve actuating gear and roller guides Engine driven starting air distributor Electronic governor with actuator Regulating shaft Engine side control console Mechanical cylinder lubricators. The Engine Control System of the ME engine comprises: Control units Hydraulic power supply unit Hydraulic cylinder units, including: Electronically controlled fuel injection, and Electronically controlled exhaust valve activation Electronically controlled starting air valves Electronically controlled auxiliary blowers Integrated electronic governor functions Tacho system Electronically controlled Alpha lubricators

Why is a man hole door elliptical in shape?

Any opening in a pressure vessel is kept to a minimum and for a man entry an elliptical hole  is lesser in size than the corresponding circular hole. More over it is prime concern to have a  smoothed generous radius at the corners to eliminate stress concentration. Hence other  geometrical shapes like rectangle and square are ruled out.  To compensate for the loss of material in the shell due to opening, a doubler ring has to be  provided around the opening. The thickness of the ring depends on the axis length along the  dirrection in which the stresses are maximum and the thickness of the shell. It is important to  align the minor axis along the length of the vessel, as the stress in this direction is  maximum. Longitudinal stress: Pd/2t where P= pressure inside the vessel, d= diameter of the arc, t=  thickness of the shell plating  Circumferential stress: Pd/4t  More over a considerable material and weight saving is achieved as minor is along the  direction of maximum stress.

Shell Expansion Plan

It is a two dimensional drawing of a three dimensional surface of the ship’s hull form. This plan is very useful for the following information:It is used for marking the location of a hull Damage on this plan by identifying the strake number , letter and frame number so that the exact location of the damage and also suggested repairs are marked in a localised copy. The shell expansion can be used for finding areas of painting surfaces such as topside, boot topping and bottom areas by applying Simpsons rules directly.  In the shell expansion the vertical scale used is different from the horizontal scale and a suitable adjustment has to be made when calculating areas. This becomes useful in solving disputes concerning areas of preparation and painting. It gives information on the thickness of the original strake which is indicated by the number in the circle shown in the strake.  The quality of steel used is also shown by letters A,B,D E and AH, BH,DH, EH.