What are the ways of cleaning fired fuel gas burners online?
The heater is fd fan type and fuel gas is used.
Also, what are the factors that could reduce its efficiency?
Answers
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16/07/2019
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Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
Adding up to Mr Peter Marsh, the Low NOx emissions are achieved by partially circulating the flue gas to the burners. This results in cracking of the Olefinic material traces (if any) present in the Fuel Gas, as the gas riser pipes / tubes are exposed to the hot flue gas (instead of relatively cool combustion air) that creeps thru the tile joints of the burners. The partial blockage of riser tubes by the coke will lead to increased velocities blowing off the riser tips. Subsequently, the gas riser tubes will be completely blocked gradually with coke. The partially blocked gas risers will give rise to uneven flame patterns and related issues. Now to address the query, gas rings (to which gas risers are fixed) can be dropped as a whole and replacing the total set of Gas risers would be the best, instead of trying to clean up the individual riser tubes.
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26/07/2018
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Peter Marsh, XBP Refining Consultants Ltd, peter.marsh@xbprefining.co.uk
Latest generation low NOx burners are particularly prone to fouling because they have multiple gas tips with relatively small diameter drilled gas ports. Fouling deposits may include ammonium salts, iron salts, coke, etc. The best solution for maintaining burner efficiency is to install a skid-mounted fuel gas conditioning system between the fuel gas KO drum and the ESD valves. This typically comprises a droplet separator, a particulate filter, a coalescer, a steam heater and heat traced, thermally insulated fuel gas piping (to keep the fuel gas above its dew point). All burners should have a quick-acting, quarter turn tight shut off isolation valve to allow isolation of individual burners for cleaning or repair with the fired heater on line. However, mechanical cleaning with wire brush or re-drilling ports is quite labour intensive and time consuming. If the fouling deposits are chloride salts and are not oil-soaked or coked, injection of steam or intermittent injection of a strongly basic chloride scavenger chemicals into the fuel gas supply can provide effective on-line cleaning of burner tips without having to remove individual burners.
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26/07/2018
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NS Murthy, Suez, murthy.ns.ext@suez.com
I have seen some refineries have steam / heat tracing of fuel gas line to prevent condensate accumulation (specially during rainy days) which in turn help to make tip cleaner from carbon deposit. Another area worth looking at is the amine loss in your refining complex as any entrained amine will be in fuel gas system which in turn can create such tip fouling.
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24/07/2018
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Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
If a row of burners can be isolated and removed for mechanical cleaning row by row then cleaning without furnace shutdown may be possible depending ont eh furnace design however if the burners are fixed or there is just a single large burner then a furnace shutdown may be required to clean the burner.
It is usually preferable to have a good quality Fuel gas coalescer installed close to the point of use to remove liquid and solid contaminants from fuel gas o protect the burner from fouling and prevent unstable flame patterns. Its far easier to change out a coalescer element than it is to clean burners and implement a regular burner cleaning routine. Particularly for low NOX and Ultra low NOX burners good fuel gas treatment is essential and this can almost eliminate burner cleaning between turnarounds.
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