Patents by Inventor Tadao Arakawa

Tadao Arakawa 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: 5044152
    Abstract: A method of operating a combined plant which is composed of a gas turbine system including a compressor into which air is introduced through an inlet guide vane, a combustor in which a fuel is burnt with the air compressed by the compressor, and a turbine into which the combustion gas is introduced to generate an output power, a waste-heat recovery boiler which generates steam by the heat possessed by the combustion exhaust gas from the gas turbine system and a steam turbine driven by the steam generated by the waste heat recovery boiler. The opening of the inlet guide vane of the gas turbine system is controlled in accordance with the state of the waste-heat recovery boiler or the steam turbine, such as the temperature of the steam introduced into the steam turbine, thermal stress generated in the steam turbine, temperature of a metallic part of the steam turbine and so forth.
    Type: Grant
    Filed: May 8, 1989
    Date of Patent: September 3, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Shinichi Hoizumi, Yoshiki Noguchi, Tadao Arakawa, Kazusada Hoshino
  • Patent number: 4920276
    Abstract: A heat-and-electricity supply system in which steam from a steam generator is utilized to supply an electric output and a heat output such a system includes: a steam turbine driven by the steam generated in the steam generator; a clutch with reduction gear, connected to a shaft of the steam turbine; a power generator for providing the electric output, connected to the clutch with a reduction gear; a clutch with a speed increasing gear, connected to a shaft of the power generator as occasion demands; a compressor connected to the clutch with speed increasing gear; a heat-side load utilizing a cooling medium or a heating medium supplied from the compressor.
    Type: Grant
    Filed: August 4, 1988
    Date of Patent: April 24, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Akitaka Tateishi, Tadao Arakawa, Masaru Kurosawa, Yoshifumi Kubo, Yoji Nagai
  • Patent number: 4858562
    Abstract: A power generation plant comprising a gas turbine and a waste heat recovery boiler in which feed water is heat-exchanged with exhaust gas from the gas turbine to produce vapor. A steam turbine system incorporates a reheat turbine and a high pressure turbine to which the vapor is supplied from the waste heat recovery boiler, with a generator being driven by the steam turbine system and condenser for condensing vapor from the stream turbine system into condensate and for supplying the condensate to the waste heat recovery boiler as the feed water. The waste heat recovery boiler is provided with a secondary reheater, a super heater, a primary reheater reheating vapor to be supplied to the secondary reheater and an evaporator for evaporating the feed water from the condenser into vapor and for supplying the vapor to the super heater, in order with respect to the exhaust gas flow.
    Type: Grant
    Filed: April 26, 1988
    Date of Patent: August 22, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Tadao Arakawa, Tsuguo Hashimoto, Akihiro Kawauchi
  • Patent number: 4693086
    Abstract: A reheat steam turbine power plant having a boiler with a superheater and reheater disposed therein, a high pressure steam turbine, an intermediate pressure steam turbine, a low pressure turbine, and a condenser condensing a steam exhausted through the low pressure turbine to a condensate. A turbine bypass pipe is provided with a bypass valve. A branch pipe branches off a cold reheater pipe between the check valve and the reheater is connected to the condenser for introducing steam flowing through the turbine bypass pipe. A control valve is arranged in the branch pipe and a controller controls the bypass valve and the control valve. When the turbine bypass line is operational in one of a start-up or an auxiliary operation of the power plant, the control valve and the bypass valve are controlled by the controller so that the quantity of reheat steam introduced into the reheater is controlled and excess or surplus steam is discharged to the condenser through the branch pipe.
    Type: Grant
    Filed: October 15, 1985
    Date of Patent: September 15, 1987
    Assignee: Hitachi, Ltd.
    Inventors: Shinichi Hoizumi, Norio Abe, Takeshi Ueno, Tadao Arakawa, Kunio Hodozuka
  • Patent number: 4622275
    Abstract: A fuel cell power plant comprising a fuel cell employing a molten carbonate as an electrolyte, a reformer for reforming fuel into a reactive gas to be supplied into the anode of the cell, an expansion turbine connected to a compressor, a combustor for burning a gas exhausted from the anode and introducing the combustion gas into the cathode of the fuel cell along with a gas compressed by the compressor, and a waste heat recovery system. The power plant is characterized by the provision of another combustor on the passage through which cathode exhaust gas is sent from the cathode to the turbine and a passage for leading a part of the anode exhaust gas to the combustor, whereby unburned gas, included in the anode exhaust gas, is burned with the cathode exhaust gas supplied as oxygen source so that the temperature of the turbine driving gas is raised, as a result, the overall thermal efficiency of the power plant increases.
    Type: Grant
    Filed: July 31, 1985
    Date of Patent: November 11, 1986
    Assignees: Hitachi, Ltd., Hitachi Engineering Co., Ltd.
    Inventors: Yoshiki Noguchi, Tadao Arakawa, Nobuo Nagasaki, Shigehisa Sugita, Masato Takeuchi
  • Patent number: 4576007
    Abstract: An apparatus for controlling an operation of a turbine plant on a reduction of the load on a turbine operates to compute a saturation pressure corresponding to the temperature in the downcomer pipe by using the detected values representing the conditions of the plant, and to control the reduction of the turbine to maintain the pressure in the downcomer pipe higher than the computed saturation pressure so as to prevent an occurrence of flashing.
    Type: Grant
    Filed: March 26, 1985
    Date of Patent: March 18, 1986
    Assignees: Hitachi, Ltd., Hitachi Engineering Co., Ltd.
    Inventors: Tadao Arakawa, Takeshi Ueno, Hiroshi Tsunematsu, Keiichi Toyoda, Tsuguo Hashimoto
  • Patent number: 4546603
    Abstract: A coal gasification composite power generating plant has a coal gasification plant and a composite power generating plant. The coal gasification plant has a low-pressure steam generator for recovering heat from the furnace wall of a pressurized fluidized bed type coal gasification furnace, and a high-pressure steam generator disposed at the outlet of the gasification furnace and adapted to recover heat from the unrefined gas coming from the gasification furnace. The composite power generating plant includes a gas turbine which uses the gas generated in the gasification plant as the fuel gas, a boiler for recovering heat from the exhaust gas of the gas turbine, and high-pressure and low-pressure steam turbines which operate with the steam generated by the boiler.
    Type: Grant
    Filed: June 8, 1984
    Date of Patent: October 15, 1985
    Assignees: Hitachi, Ltd., Hitachi Engineering Co., Ltd.
    Inventors: Tadao Arakawa, Yoshiki Noguchi, Yukio Hishinuma, Nobuo Nagasaki
  • Patent number: 4353204
    Abstract: A method and system for controlling water level of a drum of a heat recovery steam generator for a combined cycle power plant is provided. The combined cycle power plant includes gas and steam turbines and the steam generator for recovering heat in exhaust gases from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. At a start up operation, the water level of the drum is lowered in advance to the plant start up operation so that abrupt rise of the water level due to swelling phenomenon of the boiler water which may result in heat losses by damping water out of the plant is prevented. Also, a gas turbine load increase is maintained at a constant level during a period in which the abrupt water level rise is expected so that the swelling phenomenon is avoided.
    Type: Grant
    Filed: February 19, 1980
    Date of Patent: October 12, 1982
    Assignee: Hitachi, Ltd.
    Inventor: Tadao Arakawa