In Semi regenerative reformer, before regenerating the catalyst hot stripping of the catalyst in hydrogen atmosphere at 900 deg F is done. Is it necessary to do this hot stripping even if we are dumping and screening the catalyst?
Answers
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07/10/2011
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Kavirayani R Murthy, K R Murthy Consultants, krmurthy_ipcl@yahoo.com
It is highly essential to hot strip to remove sulphur poisoning of the reformer catalyst rather the only way to remove sulphate poisoning of the catalyst if by mistake the catalyst is exposed to regeneration gas like oxygen without completely stripping the sulphur from the catalyst. The sulphate formed on the catalyst can be removed only by hot stripping for a prolonged time with a very careful and close monitor of hydrogen sulphide in the outlet. This is highly essential if you continue to use the catalyst after regeneration.
Even if you wish to dump the catalyst it is preferable to hot strip due to the following reason.
There will be a lot of Iron rust coming in to the reactors may be from weak piping in the system and gets deposited at the top portion of the reactors. Some times this may cause high pressure drop also. The rust thus present is in the form of iron sulphide which is highly pyrophoric in nature. Hot stripping will remove all sulphur as hydrogen sulphide from this rust and decreases the danger of dumping pyrophoric material for safe handling.
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20/04/2011
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Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Hot stripping is done to drive out the hydrocarbons as well as remove the upset sulfur from reformer as H2S. The sulfur might have gone to reformer reactors due to any upset in pretreater.
If you do not strip out hydrocarbons efficiently they hamper regeneration. Likewise upset sulfur that entered reformer may sulfate the catalyst support which is also harmful.
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18/04/2011
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J Rout, B. Tech, routjhr@gmail.com
In SR type reformer, before regenerating the catalyst hot stripping of the catalyst is carried out in hydrogen atmosphere. This is to maximize hydrocarbon removal from catalyst bed.
In our SR type Reformer, before regeneration feed ia cut off at 460 deg C. Then Hydrogen sweeping is done and temperature is raised to 510 deg C with continuous sweeping to eliminate all hydrocarbon from catalyst bed. Catalyst Regeneration is done with nitrogen and Oxygen. If all hydrocarbon are not removed , they will burn during regeneration and situation will be out control.
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