Patents by Inventor Chih M. Hwa

Chih M. Hwa 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: 4306991
    Abstract: This invention relates to an improved composition for inhibiting deposition of scale in aqueous systems. More specifically, it relates to the use of small quantities of an improved composition for preventing formation of scale and sludge deposits in steam generating boilers. The composition is characterized by the fact that by using a plurality of selected ingredients a synergistic effect is obtained. The ingredients comprise a copolymer of styrene sulfonic acid and maleic anhydride or maleic acid, along with a water soluble organophosphonic acid compound.
    Type: Grant
    Filed: July 31, 1980
    Date of Patent: December 22, 1981
    Assignee: Chemed Corporation
    Inventors: Chih M. Hwa, Dionisio G. Cuisia
  • Patent number: 4255259
    Abstract: This invention relates to an improved method for inhibiting deposition of scale in aqueous systems. More specifically, it relates to the use of small quantities of an improved composition for preventing formation of scale and sludge deposits in steam generating boilers. The composition is characterized by the fact that by using a plurality of selected ingredients a synergistic effect is obtained. The ingredients comprise a copolymer of styrene sulfonic acid and maleic anhydride or maleic acid, along with a water soluble organophosphonic acid compound.
    Type: Grant
    Filed: September 18, 1979
    Date of Patent: March 10, 1981
    Assignee: Chemed Corporation
    Inventors: Chih M. Hwa, Dionisio G. Cuisia
  • Patent number: 4190421
    Abstract: This invention constitutes improvement in the art of introducing fuel additives into the fireside of coal fired boiler tubes to facilitate the removal of slag and like deposits from the fireside, to lower acid smut pollution, to control corrosion, and to improve the electrical resistivity of particulate emission. The improvement is achieved by the addition of pulverized coal to the fuel additives.
    Type: Grant
    Filed: July 17, 1978
    Date of Patent: February 26, 1980
    Assignee: Chemed Corporation
    Inventor: Chih M. Hwa
  • Patent number: 4134959
    Abstract: The invention disclosed provides a new composition and method for inhibiting corrosion. The present composition is relatively non-toxic, contains no chromates and zinc, and consists essentially of an azole and a water-soluble phosphate in an effective combination. Effective amounts of the corrosion inhibiting composition are used to provide corrosion protection in both ferrous and non-ferrous metals.
    Type: Grant
    Filed: August 19, 1977
    Date of Patent: January 16, 1979
    Assignee: Chemed Corporation
    Inventors: Russell O. Menke, Jose T. Jacob, Chih M. Hwa
  • Patent number: 4098720
    Abstract: Low toxicity, low pollution potential compositions and methods for inhibiting corrosion of ferrous and non-ferrous metallic parts in aqueous systems. The compositions have no chromate, no polyphosphate and no borate and consist essentially of alkali metal nitrite, alkali metal carbonate or bicarbonate and an azole. Preferably the compositions also include an alkali metal silicate and small amounts of an alkali metal hydroxide. In the corrosion inhibiting method, the aforesaid compositions are added to the system water in amounts sufficient to provide from about 100 to 10,000 parts per million ("ppm") of alkali metal nitrite, the primary inhibitor.
    Type: Grant
    Filed: January 14, 1976
    Date of Patent: July 4, 1978
    Assignee: Chemed Corporation
    Inventor: Chih M. Hwa
  • Patent number: 4067690
    Abstract: The invention disclosed provides a method for boiler water treatment to retard corrosion due to dissolved oxygen. Hydroxylamine, certain derivatives thereof and their salts have now been found to be highly effective oxygen scavengers for use in boiler water and thereby effect reduction of corrosion resulting from dissolved oxygen.
    Type: Grant
    Filed: February 9, 1977
    Date of Patent: January 10, 1978
    Assignee: Chemed Corporation
    Inventors: Dionisio G. Cuisia, Chih M. Hwa, Jose T. Jacob, Murrell L. Salutsky