Hitachi, Ltd.

Babcock-Hitachi Kabushiki Kaisha

Hitachi Engineering Co., Ltd.

Toshihiko Sasaki

Shinichi Hoizumi

Shigehisa Sugita

Motoaki Utamura

Tetsuo Sasada

Takashi Ikeguchi

Seiichi Kirikami

Yasushi Takeda

Hideaki Komatsu

Takeshi Suzumura

Shozo Nakamura

Yoshiki Noguchi

Zensuke Tamura

Nobuhiro Seiki

Yasuaki Akatsu

Naoto Koizumi

Toru Kobashi

Asao Takashi

To improve the thermal efficiency when an exhaust heat recovery type combined cycle plant having a gas turbine and a steam turbine in combination is operated at a partial load, the gas turbine exhaust is recirculated and returned to the compressor, and the combustion temperature is prevented from being lowered at the partial load. Preferably, the temperature is maintained constant. In this way, the thermal efficiency during operation at partial load can be improved.

Gas turbine exhaust recirculation method and apparatus

Exhaust recirculation type combined plant

In fuel gasification, particles of, for example, coal and an oxidant are supplied to a reactor, where the coal particles are gasified. The gas thus produced may contain molten slag entrained therein and such slag could subsequently solidify and affect other components of the coal gasification apparatus. Therefore a molten slag cooling heat exchanger is positioned directly above the reactor and this cools the gas so as to cause any molten slag therein to solidify. Hence, such molten slag does not reach an evaporator above the molten slag cooling heat exchanger, so that the efficiency of the evaporator will be maintained. However, solidified molten slag may build up on heat exchange tubes of the molten slag cooling heat exchanger. Therefore, the rate of coolant supplied to the molten slag cooling heat exchanger is varied, to cause expansion and contraction which causes solidified slag to be dislodged. Hence the efficiency of the molten slag cooling heat exchanger does not deteriorate. Cleaning gas and coal particles may be jetted onto the evaporator to dislodge ash or soot therefrom.

Method of fuel gasification and an apparatus for performing such a method

A combined cycle power plant has a plurality of gas turbine units each having a gas turbine and a heat recovery boiler for generating steam from heat from exhaust gas from the gas turbine. The gas turbine of a first one of the gas turbine units is a steam-cooled gas turbine. Steam turbines are driven by steam from the heat recovery boilers. For start-up of the first gas turbine unit, cooling steam generated in a heat recovery boiler different from not being the heat recovery boiler of the first gas turbine unit is fed to the steam-cooled gas turbine to effect cooling thereof during at least part of the start-up operation of the first gas turbine unit.

Combined cycle power plant

A pressurized fluidized bed combustion combined cycle power plant has a gas turbine unit of single spindle type in which a turbine, driven by combustion gas from burning of coal in a pressurized fluidized bed combustion boiler, drives an electrical generator at constant speed and drives a compressor supplying compressed combustion air to the boiler. To permit partial load operation, a control arrangement is provided to effect, in dependence upon an operating load of the boiler, control of at least one of the flow rate of the combustion air into the boiler, and the operating pressure in the combustion chamber of the boiler. The control arrangement may be, for example, a valve controlling a by-pass flow of the combustion air and/or inlet guide vanes of the compressor.

Pressurized fluidized bed combustion combined cycle power plant and

Growing community of inventors

Ibaraki, Japan

Toshihiko Sasaki