Mineral oils: processes and products – Refining – Sulfur removal
Reexamination Certificate
1998-05-06
2001-05-01
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Refining
Sulfur removal
C208S057000, C208S058000, C208S082000, C208S211000, C208S212000, C208S218000, C208S25100H, C208S25400R
Reexamination Certificate
active
06224749
ABSTRACT:
BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The present invention relates to hydroprocessing hydrocarbonaceous feeds using two liquid and one vapor hydroprocessing reaction stages with no hydrogen transfer between the liquid stages. More particularly the invention relates to catalytically hydroprocessing a hydrocarbonaceous feed in two liquid reaction stages and one vapor reaction stage, in which both liquid stages produce an effluent comprising a liquid and a vapor which are separated after each liquid stage, with the first liquid stage vapor effluent and, optionally also the second stage vapor effluent, hydroprocessed in the vapor stage. The partially hydroprocessed first stage liquid effluent is the feed for the second stage. Fresh hydrogen is used for both liquid stage reactions.
2. Background of the Invention
As supplies of lighter and cleaner feeds dwindle, the petroleum industry will need to rely more heavily on relatively high boiling feeds derived from such materials as coal, tar sands, shale oil, and heavy crudes, all of which typically contain significantly more undesirable components, especially from an environmental point of view. These components include halides, metals, unsaturates and heteroatoms such as sulfur, nitrogen, and oxygen. Furthermore, due to environmental concerns, specifications for fuels, lubricants, and chemical products, with respect to such undesirable components, are continually becoming tighter. Consequently, such feeds and product streams require more upgrading in order to reduce the content of such undesirable components and this increases the cost of the finished products.
In a hydroprocessing process, at least a portion of the heteroatom compounds are removed, the molecular structure of the feed is changed, or both occur by reacting the feed with hydrogen in the presence of a suitable hydroprocessing catalyst. Hydroprocessing includes hydrogenation, hydrocracking, hydrotreating, hydroisomerization and hydrodewaxing, and therefore plays an important role in upgrading petroleum streams to meet more stringent quality requirements. For example, there is an increasing demand for improved heteroatom removal, aromatic saturation and boiling point reduction. In order to achieve these goals more economically, various process configurations have been developed, including the use of multiple hydroprocessing stages as is disclosed, for example, in European patent publication 0 553 920 A1 and U.S. Pat. Nos. 2,952,626; 4,021,330; 4,243,519; 4,801,373 and 5,292,428.
SUMMARY OF THE INVENTION
The invention relates to a three stage process for hydroprocessing a hydrocarbonaceous feed in which the feed is reacted with fresh hydrogen in the presence of a hydroprocessing catalyst in two separate, liquid reaction stages, both of which produce a vapor and liquid effluent which are separated after each liquid stage. The partially hydroprocessed first stage liquid effluent is the feed to the second stage and the second stage liquid effluent is the hydroprocessed product liquid. The first stage effluent vapors are hydroprocessed by reacting with hydrogen in a vapor reaction stage to produce hydroprocessed vapors. Fresh hydrogen or a hydrogen containing treat gas is used in each liquid stage. The hydrocarbonaceous feed to be hydroprocessed is introduced into the first liquid stage in which it is partially hydroprocessed and then passed into the second liquid stage to complete the hydroprocessing and form a hydroprocessed product liquid. The hydrogen for the vapor stage reaction is preferably unreacted hydrogen present in the first stage vapor effluent. However, if desired all or a portion of the vapor stage reaction hydrogen may come from fresh hydrogen or a hydrogen-containing treat gas introduced into the vapor stage reaction zone. In the preferred embodiment, sufficient fresh hydrogen or a hydrogen-containing treat gas must be introduced into the first stage to insure sufficient unreacted hydrogen in the first stage vapor effluent. All or a portion of the vapor stage effluent is cooled to condense and recover hydroprocessed carbonaceous material as additional product liquid which may be blended with the second liquid stage product liquid effluent. When the feed comprises hydrocarbons, the cooled and condensed vapor stage effluent will typically comprise material having at least three and preferably at least four carbon atoms. The term “hydrogen” as used herein refers to hydrogen gas. In its broadest sense, the invention comprises a hydroprocessing process which includes two liquid and one vapor reaction stages and which comprises the steps of:
(a) reacting a hydrocarbonaceous feed with fresh hydrogen in a first hydroprocessing liquid reaction stage in the presence of a hydroprocessing catalyst to form a first stage effluent comprising a partially hydroprocessed hydrocarbonaceous liquid and vapor;
(b) separating said first stage liquid and vapor effluent;
(c) reacting said first stage liquid effluent with fresh hydrogen in the presence of a hydroprocessing catalyst in a second hydroprocessing liquid reaction stage to produce a second stage effluent comprising a hydroprocessed hydrocarbonaceous product liquid and vapor;
(d) separating said second stage liquid and vapor effluent, and
(e) reacting said first stage vapor effluent with hydrogen in the presence of a hydroprocessing catalyst in said vapor reaction stage to form a hydroprocessed hydrocarbonaceous vapor.
Typically at least a portion of the hydroprocessed vapor will be cooled to condense out the vaporized hydroprocessed material as additional product liquid, which is separated from the remaining uncondensed vapor.
In one embodiment, the first liquid stage and the vapor stage may both be in the same vessel. In another embodiment, all three reaction stages may each be in a separate reaction vessel. The catalyst used in each stage may be the same or different, depending on the feed and the process objectives. Further embodiments include stripping the recovered, hydroprocessed product liquid to remove undesirable reaction products.
In the practice of the invention, the fresh hydrocarbonaceous feed fed into the first stage reaction zone is mostly liquid and typically completely liquid. During the hydroprocessing, at least a portion of the lighter or lower boiling feed components are vaporized in each liquid stage. The amount of feed vaporization will depend on the nature of the feed and the temperature and pressure in the reaction stages and may range between about 5-80 wt. %. Thus, by liquid reaction stage is meant that some of the feed being hydroprocessed is in the liquid stage. In most cases the hydrocarbonaceous feed will comprise hydrocarbons. In an embodiment in which the process is a hydrotreating process for a sulfur and nitrogen containing distillate or diesel fuel fraction, the hydroprocessing forms H
2
S and NH
3
, some of which is dissolved in the hydroprocessed product liquid and vapor condensate. Simple stripping removes these species from these liquids.
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patent: 5720872 (1998-02-01), Gupta
patent: 6054041 (2000-04-01), Ellis et al.
Ellis Edward S.
Gupta Ramesh
Jung Henry
Markley Gerald E.
Exxon Research and Engineering Company
Griffin Walter D.
Hughes Gerard J.
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