How effective is hydrogen in stripping H2S from hydrotreated naphtha?
Answers
|
22/07/2020
|
A:
|
Jake Gotham, InSite Technical Services, jake.gotham@insitetechnical.com
Steam stripping works by depressing the partial pressure of H2S and LPG in the vapour phase, encouraging vaporisation of these light components from the liquid phase. Hot hydrogen could be used as well as steam or instead of steam to achieve the same objective if the same number of kmol/hr were injected.
Various technologies have used hydrogen stripping within the high-pressure loop to remove H2S before the oil reaches a second ‘clean’ reactor. In these cases the hydrogen can be recovered within the high pressure loop and recycled. If you are considering hydrogen stripping in a low-pressure stripper tower, obviously the hydrogen would be lost in the low-pressure off-gas. Depending on your refinery hydrogen balance, that might be a big cost or zero cost.
|
|
21/07/2020
|
A:
|
Manoj, Lummus Global Pte. Singapore, parasharmk@yahoo.com
It’s not a matter of the gas type but more a matter of the temperature to flash off the H2S in the stripper .
|
|
20/07/2020
|
A:
|
keith bowers, B and B Consulting, kebowers47@gmail.com
H2 for H2S stripping is very effective. Absolute efficiency depends on thorough contact and dispersion of the stripping medium. 'Short Circuiting' of any naphtha will impact efficiency.
|
|
20/07/2020
|
A:
|
Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
I have seen hot hydrogen strippers used on naphtha hydrotreaters and they worked OK. A reboiled stripper would normally be preferred, especially since hydrogen availability is often a major refinery constraint or is quite expensive. Hydrogen strippers were a low cost capital option back in the days before low sulfur fuels expanded the demand for hydrogen in the refinery. In those days a lot of the hydrogen winded up in fuel anyway, so routing it to a stripper first made some sense. If your facility has a lot of excess hydrogen from catalytic reforming, it could still make sense but that is certainly no longer the norm at most refineries.
|
|
20/07/2020
|
A:
|
Nagarathinam S Murthy, Ashphil Consultancy, Chennai, nssvdvr@gmail.com
With hydrogen being soluble in naphtha (especially at elevated temperatures and in thr presence of aromatics), no one uses H2 as a stripping medium. Hydrogen is three times costlier than natural gas/refinery fuel. Typically, refiners have successfully used the reboiler heater for stripping H2S in NHTs.
|
|
20/07/2020
|
A:
|
Peter Marsh, XBP Refining Consultants Ltd, peter.marsh@xbprefining.co.uk
Beware. Hydrogen has a counter-intuitive temperature vs solubility relationship in light hydrocarbons. Hydrogen solubility increases with temperature in naphtha so if you divert hydrotreated naphtha from the product stripper to slops or intermediate product tankage, hydrogen will be liberated in the floating roof tank. This creates an extremely hazardous situation as hydrogen forms an explosive atmosphere over an extremely wide range of concentrations in air and self-heats on expansion (reverse Joule-Thomson effect). Ignition can easily occur by spark generation from floating roof movement or lightning strike.
|