What are the demerits of sending unstabilized reformate from fixed bed catalytic reformer unit directly to a storage tank?
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14/07/2009
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Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
In addition to the fire hazard associated with the vapor losses, the generation of large quantities of vapor in a floating roof tank can cause the roof to sink. The vapors tend to form near the oil inlet to the tank and lift the roof on that side of the tank, causing the roof to tilt and sink.
A refinery I used to work in put unstabilized full range distillate into a floating roof tank. On start up they had an upset and sunk the roof once. Another time lightning ignited the vapors escaping around the tank seal. Fortunately the roof seals remained in tact until the fire was extinguished; otherwise, the fire could have been much worse than it was.
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04/07/2009
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Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Unstabilized reformate may have more than 6 % of C4 minus hydrocarbons ith high RVP of reformate. So the problems resulting from light hydrocarbon gases would occur in the storage tanks would occur.
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03/07/2009
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Kavirayani R Murthy, K R Murthy Consultants, krmurthy_ipcl@yahoo.com
On the Bifunctional Reforming catalyst several reactions takes place both on active platinum sites and acidic alumina sites. Mutual synergy between these two sites give various products. Important reactions are-
Dehydrogenation of Naphthenes to aromatics
Dehydrocyclization of Long chain paraffins to naphthenes then to aromatics
Dehydroisomerization of Long chain normal paraffins give long chain isoparaffins.
Most of the above reactions produce long chains of carbon compounds. Any compound having C5 + Hydrocarbons is mostly in liquid form.
There are certain other reactions Like Hydrocracking produces C1 to C4 hydrocarbons and Hydrogenolysis reaction produces Methane. These hydrocarbons having carbon number less than C4 are mostly in gaseous form.
When the reformate comes out of the Reformer operating at higher pressure and high temperature contains large portion of Liquid and about 15 to 20% of gaseous products depending on the operating parameters, Reformer environment like chloride and moisture in recycle gas and the composition of feed. The gaseous fragments largely consists of hydrocarbonsless than C4 and process generated hydrogen. This raw reformate is called unstabilized reformate. If we take this reformate in to tanks, since the tanks are at atmospheric temperature and pressure, these gases will try to come out and fill in to atmosphere which is a safety hazard.
Also when we send this unstabilized reformate in to down stream units like columns, the gaseous fragments will unnecessarily occupy the space meant for liquid thereby underutilizing the efficiency of those columns. Also when those down stream columns which are meant for distilling only liquid components for separation, the columns will function inefficiently and they may also malfunction.
Hence in the industrial process unstabilized reformate will always be sent through a stabilizer for removing the gaseous fragments. Thus removing gaseous fragments will avoid the inefficiency of process.
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03/07/2009
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Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Unsatbilized reformate has high vapour pressure due to high C4- content. So the issue of low boiling vapors and their release may have to be considered. This may cause greater release of butanes minus hydrocarbons during storage in the tanks.
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03/07/2009
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keith bowers, B and B Consulting, kebowers47@gmail.com
DO NOT do that. The light ends (c1-c5) will just boil out. There will be lots of outgassing and subsequent hydrocarbon emissions and losses.
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03/07/2009
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Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
It's a safety issue plus gasolene product quality issue.
1) Unstabilised reformate contains LPG & some fuel gas. If stored in atmospheric tanks, LPG will flash off and be potential explosion source if it finds an ignition source and the presence of air.
2) Also reformate containing LPG may well cause gasoline to be off spec due to RVP so can't be used for gasoline pool blending stock until stabilized and light ends removed.
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02/07/2009
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Alan Goelzer, Jacobs Consultancy, alan.goelzer@jacobs.com
First is risk of venting of light gases [H2, C1-C4] around the floating roof of API FR Tank or internal floating pan of API CFR Tank and thus creating a hazardous gas mixture or causing the floating roof or pan to upset and sink.
Best practices vis-a-vis API Tank safety considerations call for limiting the actual vapor pressure of fluids at actual working temperature of the tank to preferably less than 12 psia and no more than 14-15 psia in colder climates.
If the actual tank temperature is close to 100F/38C, then the actual vapor pressure can be inferred from Mini-Method Reid Vapor Pressure testing---assuming that samples are taken in flow through sample system and "pressure samplers" [and not via drainage into metal cans].
Second is severe impact on RVP [Reid Vapor Pressure] contribution to the gasoline pool from H2 + methane/ethane + propane in the unstabilized reformate--even if the butanes content and contribution is acceptable. This assumes that the unstabilized reformate has been at least through a low pressure flash drum and is not coming directly from the cold high-pressure separator.
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