Patents by Inventor David A. Larsen

David A. Larsen 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: 6378847
    Abstract: A monolithic, fired ceramic gas diffuser for injecting gas into a molten metal bath, including a first portion, a second portion integrated with the first portion, and a bore passing through the first portion and communicating with the second portion for supplying gas to the second portion, wherein at least the second portion has a network of interconnected pores that provides preferential gas flow from the bore through the second portion to inject gas into the molten metal bath.
    Type: Grant
    Filed: December 14, 2000
    Date of Patent: April 30, 2002
    Inventors: Donald G. Rexford, David A. Larsen, Earle R. Webster, Jr.
  • Patent number: 6322729
    Abstract: A method of forming a monolithic, fired ceramic gas diffuser for injecting gas into a molten metal bath includes the steps of: preparing first and second batch materials, depositing the batch materials into a mold to form different portions of the diffuser, and firing the casting to obtain the monolithic diffuser. Various embodiments of the method include vibrating the mold at least while the second batch material is deposited therein, partially freezing a first portion of the casting, and freezing the entire casting prior to firing.
    Type: Grant
    Filed: December 19, 2000
    Date of Patent: November 27, 2001
    Assignee: Blasch Precision Ceramics, Inc.
    Inventors: Donald G. Rexford, David A. Larsen, Earle R. Webster, Jr.
  • Publication number: 20010042929
    Abstract: A monolithic, fired ceramic gas diffuser for injecting gas into a molten metal bath, including a first portion, a second portion integrated with the first portion, and a bore passing through the first portion and communicating with the second portion for supplying gas to the second portion, wherein at least the second portion has a network of interconnected pores that provides preferential gas flow from the bore through the second portion to inject gas into the molten metal bath.
    Type: Application
    Filed: December 14, 2000
    Publication date: November 22, 2001
    Applicant: Blasch Precision Ceramics, Inc.
    Inventors: Donald G. Rexford, David A. Larsen, Earle R. Webster
  • Publication number: 20010000633
    Abstract: A monolithic, fired ceramic gas diffuser for injecting gas into a molten metal bath, including a first portion, a second portion integrated with the first portion, and a bore passing through the first portion and communicating with the second portion for supplying gas to the second portion, wherein at least the second portion has a network of interconnected pores that provides preferential gas flow from the bore through the second portion to inject gas into the molten metal bath.
    Type: Application
    Filed: December 19, 2000
    Publication date: May 3, 2001
    Applicant: Blasch Precision Ceramics, Inc.
    Inventors: Donald G. Rexford, David A. Larsen, Earle R. Webster
  • Patent number: 6199836
    Abstract: A monolithic, fired ceramic gas diffuser for injecting gas into a molten metal bath, including a first portion, a second portion integrated with the first portion, and a bore passing through the first portion and communicating with the second portion for supplying gas to the second portion, wherein at least the second portion has a network of interconnected pores that provides preferential gas flow from the bore through the second portion to inject gas into the molten metal bath.
    Type: Grant
    Filed: June 1, 1999
    Date of Patent: March 13, 2001
    Assignee: Blasch Precision Ceramics, Inc.
    Inventors: Donald G. Rexford, David A. Larsen, Earle R. Webster, Jr.
  • Patent number: 6042622
    Abstract: Alkali metal bicarbonate salts, e.g., sodium bicarbonate, are crystallized from aqueous solutions thereof in the presence of a crystal growth promoting amount of lecithin or lecithin containing compositions. Alkali metal bicarbonate salts include sodium bicarbonate, potassium bicarbonate and lithium bicarbonate. The process is described as providing increased amounts of large crystals and a narrower and more uniform crystal size distribution.
    Type: Grant
    Filed: July 31, 1996
    Date of Patent: March 28, 2000
    Assignee: BASF Corporation
    Inventor: David A. Larsen
  • Patent number: 6024259
    Abstract: A riser tube for transfer of molten metal therethrough, including a porous ceramic substrate having a hollow cylindrical structure and ceramic impregnant material penetrating into pores of the substrate and plugging at least a portion of the surface pores thereof, to improve gas impermeability of the substrate. According to the present invention, the porous ceramic substrate is immersed in impregnation media containing ceramic particles, the impregnation media is subjected to an elevated pressure such that the media penetrates the pores of the substrate, and the impregnated substrate is then fired, whereby the ceramic particles form a ceramic impregnant material that plugs at least a portion of the surface pores of the substrate.
    Type: Grant
    Filed: May 9, 1997
    Date of Patent: February 15, 2000
    Assignee: Blasch Precision Ceramics, Inc.
    Inventors: Matthew T. Gardner, David A. Larsen
  • Patent number: 5716419
    Abstract: Mineral salts, e.g., potassium chloride, are crystallized from aqueous solutions thereof in the presence of a crystal growth promoting amount of lecithin or lecithin containing compositions. Mineral salts include alkali metal and alkaline-earth metal chloride, sulfate, carbonate, phosphate and nitrate salts. The process is described as providing increased amounts of large crystals and a narrower and more uniform crystal size distribution.
    Type: Grant
    Filed: July 31, 1996
    Date of Patent: February 10, 1998
    Assignee: PPG Industries, Inc.
    Inventor: David A. Larsen
  • Patent number: 5716559
    Abstract: Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously horn have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken.
    Type: Grant
    Filed: June 14, 1996
    Date of Patent: February 10, 1998
    Assignee: Blasch Precision Ceramics, Inc.
    Inventors: David A. Larsen, David P. Bacchi, Timothy F. Connors, Edwin L. Collins, III