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We have dual fired furnace. The FG generated in the process is used to run the furnace. Of course we switch over to fuel oil when such gas is not available, say, during start up. However of late, we have faced frequent burner blockage by carbon particles and sometimes a fireball coming out of the furnace. Due to this we are unable to run the furnace in fuel gas. However we have not noticed any carbon particle accumulation in the FG filters. Can anyone help us from similar kind of experience?
 
Answers
25/04/2008 A: Hubert Mueller, Bayernoil, guhumueller@web.de
It's difficult to provide a short and simple answer to your question. However, I would suggest that the provision of some more information about your fuel gas net from the main header to the burner tips might be a pre-requisite.
25/04/2008 A: Kamaljit Medhi, Indian Oil Corporation Ltd, medhik@indianoil.in
In most furnaces, the FG supply to the Furnace gets cut off automatically when the arch pressure increases beyond the allowable limit.
We in Digboi Refinery of Indian Oil Corp Ltd had a similar experience. Cooling water flow to one of the condenser got reduced and the condensed stream temperature increased much more than the normal value. This resulted in rise of temperature of the Gas separator leading to vaporization of higher HC and thus changing the composition of the FG being generated from the Separator. Occasional fireball from the furnace as well as burner blockage were also observed.
As you never faced similar kind of problem earlier, please check whether any cooler is malfunctioning. Of course, you will not find the carbon particle or liquid in the fuel gas line initially. However after passing certain distance , heavy HC will tend to condense and if it reaches the Furnace FG Burner, you may experience burner blockage, instability in Furnace Operation and also occasional Fireball from the furnace.
25/04/2008 A: Berthold Otzisk, Kurita Europe GmbH, Berthold.Otzisk@kurita-water.com
The condensation of heavier hydrocarbons is a critical factor for a continuous and effective operation of the fuel gas system. In most cases fuel gas is a mixture of components like hydrocarbons, sulphides and ammonium salts.
An article with the title “Ammonium salt removal in fuel gas burners” was published in PTQ Q4 2007, which describes the ACF technology. The combination of ammonium salts and carbon particles often results in blockage of burner tips