Patents by Inventor Krishniah Parimi

Krishniah Parimi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6359018
    Abstract: An integrated process for producing a liquid hydrocarbon stream from Fischer-Tropsch hydrocarbon product without having to remove particulate contaminants such as catalyst fines from hot Fischer-Tropsch wax is disclosed. The process involves performing Fischer-Tropsch synthesis, preferably under conditions which favor formation of wax and heavy products (i.e., using a catalyst with high chain growth probabilities), and obtaining a waxy heavy fraction including particulate contaminants. The fraction is subjected to hydroprocessing conditions, preferably upflow hydroprocessing conditions, using a catalyst bed which, through judicious selection of hydroprocessing catalysts and/or flow conditions, permits passage of the particulate contaminants. The particulates are then removed from the upgraded liquid product, for example by filtration, distillation and/or centrifugation.
    Type: Grant
    Filed: October 27, 2000
    Date of Patent: March 19, 2002
    Assignee: Chevron U.S.A. Inc
    Inventors: Dennis J. O'Rear, Krishniah Parimi, Richard O. Moore, Jr.
  • Patent number: 6183702
    Abstract: A distributor assembly for a multi-bed, downflow catalytic reactor is disclosed. The distributor assembly is configured for disposal and fixable attachment between the inner surfaces of the walls of a multi-bed downflow cylindrical reactor wall and for disposal between vertically stacked catalyst beds within the reactor.
    Type: Grant
    Filed: December 21, 1998
    Date of Patent: February 6, 2001
    Assignee: Chevron U.S.A. Inc.
    Inventors: Duyen T. Nguyen, Krishniah Parimi, Dennis R. Cash
  • Patent number: 5958220
    Abstract: A distributor assembly for hydroprocessing a hydrocarbon mixture of hydrogen-containing gas and liquid hydrocarbon is presented. The distributor assembly has a circular plate with a plurality of hollow risers bound thereto for distributing hydrogen-containing gas and liquid hydrocarbon through openings in the circular plate member. Each of the hollow risers has a tubular opening In its associated side. The distributor assembly is connected to an internal wall of a reactor. A method is also presented for hydroprocessing a hydrocarbon feed stream comprising flowing a mixture of hydrogen-containing gas and liquid hydrocarbon into a reactor zone to produce evolved hydrogen-containing gas; and flowing the mixture of hydrogen-containing gas and liquid hydrocarbon through a plurality of tubular zones while admixing simultaneously therewith the evolved hydrogen-containing gas.
    Type: Grant
    Filed: November 23, 1998
    Date of Patent: September 28, 1999
    Assignee: Chevron U.S.A. Inc.
    Inventors: Bruce E. Reynolds, Bruce E. Stangeland, Krishniah Parimi, Robert W. Bachtel
  • Patent number: 5885534
    Abstract: A distributor assembly for hydroprocessing a hydrocarbon mixture of hydrogen-containing gas and liquid hydrocarbon is presented. The distributor assembly has a circular plate with a plurality of hollow risers bound thereto for distributing hydrogen-containing gas and liquid hydrocarbon through openings in the circular plate member. Each of the hollow risers has a tubular opening in its associated side. The distributor assembly is connected to an internal wall of a reactor. A method is also presented for hydroprocessing a hydrocarbon feed stream comprising flowing a mixture of hydrogen-containing gas and liquid hydrocarbon into a reactor zone to produce evolved hydrogen-containing gas; and flowing the mixture of hydrogen-containing gas and liquid hydrocarbon through a plurality of tubular zones while admixing simultaneously therewith the evolved hydrogen-containing gas.
    Type: Grant
    Filed: March 18, 1996
    Date of Patent: March 23, 1999
    Assignee: Chevron U.S.A. Inc.
    Inventors: Bruce E. Reynolds, Bruce E. Stangeland, Krishniah Parimi, Robert W. Bachtel
  • Patent number: 5690896
    Abstract: A multi-bed, down-flow reactor includes several distributor assemblies, each having a centrally located mixing chamber and an annular collecting and mixing trough surrounding the mixing chamber. The mixing chamber has an inlet at one side thereof, an outlet in its bottom wall, and a quench gas inlet in its top wall above the outlet. A divider wall traverses the annular trough adjacent to the inlet to cause the pool of liquid collected in the trough to flow in a circular pattern around the mixing chamber to the inlet. This ensures that the liquid circulating through the trough is well mixed with the liquid raining down from the catalyst bed. Turbulent and spiraling flow patterns generated within the chamber further mix the liquid and gas and entrain quench gas in the liquid and gas stream.
    Type: Grant
    Filed: May 5, 1995
    Date of Patent: November 25, 1997
    Assignee: Chevron U.S.A. Inc.
    Inventors: Bruce E. Stangeland, Krishniah Parimi, Dennis R. Cash
  • Patent number: 5603904
    Abstract: A light-weight and easily manufacturable catalyst support structure is provided, which allows fluid flow into a catalyst bed in uniform distribution. The support structure is formed in a cone-like shape in which the diameter enlarges upward. The support structure comprises a shell-like support member, a first mesh layer comprising thick mesh elements, and a second mesh layer having a mesh size which does not allow catalytic particulates to pass through. The first mesh layer overlays the support member, and the second mesh layer overlays the first mesh layer. The shell-like support member includes a circular bottom plate extending perpendicular to the center line of the reactor, and a side wall having a truncated cone shape which extends upward from the edge of the bottom plate. The bottom plate and the side wall are primarily made of perforated plates through which the fluid passes. A plurality of cylindrical flow guides of different diameters are provided underneath the shell-like support member.
    Type: Grant
    Filed: March 28, 1996
    Date of Patent: February 18, 1997
    Assignee: Chevron U.S.A. Inc.
    Inventors: Robert W. Bachtel, Yoshitomo Ohara, Toshio Ishizuka, Tsunehiko Hiraga, Krishniah Parimi, David E. Earls