Mineral oils: processes and products – Refining – Sulfur removal
Patent
1997-04-07
1999-04-06
Lewis, Michael
Mineral oils: processes and products
Refining
Sulfur removal
208213, 502 34, 502 53, C10G 2500
Patent
active
058913238
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a purification process and in particular to a process wherein an adsorbent bed is periodically regenerated by the passage of a heated gas therethrough.
It has been proposed in U.S. Pat. No. 4,978,439 to remove sulphur compounds from a feedstock stream by passing the feedstock through a bed of a regenerable adsorbent, such as a molecular sieve, and, while one bed is effecting adsorption of sulphur compounds from the feedstock to produce a product stream, another bed, on to which sulphur compounds such as mercaptans had been adsorbed, is undergoing regeneration by passing a heated gas stream through the bed to desorb the sulphur compounds. The effluent from the bed undergoing regeneration is then subjected to reaction with hydrogen, i.e. hydro-desulphurisation, to convert sulphur compounds desorbed during the regeneration to hydrogen sulphide, hydrogen being added to the regeneration gas before or after passage through the adsorbent bed. The effluent from the hydro-desulphurisation stage was then passed through a bed of a suitable absorbent to absorb the hydrogen sulphide. The effluent from the absorbent bed was then added to the product stream.
One disadvantage of this process is that a considerable amount of hydrogen is required since, to effect satisfactory hydro-desulphurisation, the amount of hydrogen that has to be added to the regeneration gas has to be in a substantial excess over the stoichiometric amount required for reaction with the sulphur compounds. The excess of hydrogen merely forms part of the product stream.
We have devised a process wherein this disadvantage is overcome. The process of the invention is also applicable to other purification processes where impurity compounds that react with hydrogen are adsorbed by a regenerable adsorbent. Examples of such other impurities include organo-metallic, e.g. organo-mercury, compounds and organo-chlorine compounds. Reaction of organo-mercury compounds with hydrogen give rise to mercury which can be absorbed by a suitable absorbent, such as copper sulphide. Likewise organo-chlorine compounds react with hydrogen to give hydrogen chloride which can be absorbed with a suitable alkalised absorbent material, for example granules made by agglomerating a mixture of alumina trihydrate, sodium carbonate or bicarbonate, and a binder and calcining the mixture at a temperature below 350.degree. C.
Accordingly the present process provides a process for the regeneration of a regenerable adsorbent bed on to which impurity compounds have been adsorbed while a feedstock stream is undergoing purification to produce a product stream by passage through another bed of said regenerable adsorbent, and/or through a bed of a non-regenerable absorbent, said process comprising passing a regeneration gas stream through the bed undergoing regeneration to desorb said impurity compounds from said adsorbent and passing the effluent from that bed containing said desorbed impurity compounds over a catalyst effective to cause at least some of said impurity compounds to react with hydrogen to give a reaction product followed by absorption of said reaction product using a particulate absorbent, characterised in that the gas stream used for regeneration is circulated round a loop so that it passes through the adsorbent bed undergoing regeneration, then through a bed of said catalyst, then through a bed of absorbent for said reaction product and then returned to the bed undergoing regeneration as the regeneration gas without addition to the product stream, hydrogen being added to the circulating regeneration gas to maintain the hydrogen content at a desired level.
The invention also provides a process for the purification of a feedstock to produce a product stream comprising passing the feedstock through a first bed of regenerable adsorbent, whereby impurity compounds are adsorbed from said feedstock in said bed, periodically discontinuing flow of feedstock through said first bed and, while continuing production of said product stream by passing said feedstock
REFERENCES:
patent: 4661256 (1987-04-01), Johnson
patent: 4952746 (1990-08-01), Johnson
patent: 4978439 (1990-12-01), Carnell et al.
Patent Abstracts of Japan, vol. 12, No. 372 (C-533) & JP,A,63 122790 (Mitsubishi Heavy Ind.) May 26 1988, see abstract.
Patent Abstracts of Japan, vol. 17, No. 622 (C-1130) & JP,A,05 192535 (Kawasaki Heavy Ind.) Aug. 3 1993, see abstract.
Ghyka Alexander G.
Imperial Chemical Industries plc
Lewis Michael
LandOfFree
Purification process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Purification process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Purification process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1368143