Hitachi, Ltd.

Babcock-hitachi Kabushiki Kaisha

Hitachi Babcock Kabushiki-kaisha

Fumio Koda

Shigeru Azuhata

Hironobu Kobayashi

Kiyoshi Narato

Norio Arashi

Kenichi Sohma

Masayuki Taniguchi

Kazutoshi Higashiyama

Shigeki Morita

Hiroshi Miyadera

Yoshitaka Takahashi

Tadayoshi Murakami

Tooru Inada

Keizou Ohtsuka

Tadahisa Masai

Yasuo Yoshii

Hideo Kikuchi

Junichiro Matsuda

Shigekazu Nishimoto

Tetsuo Mimura

Tooru Inata

Isao Koyama

Tatsuzou Enomoto

Kenshi Kobayashi

Takayo Kawase

Masakiyo Tanikawa

Kei Kawano

Boiler

A low-NOx boiler comprises a burner for burning gaseous fuel, heat transfer pipes heating water by combustion heat of the burner to generate steam and having a passage through which water flows, a steam drum communicating with the heat transfer pipe and accumulating the steam from the heat transfer pipe, and an exhaust gas duct located in the furnace to exhaust combustion gas generated by combustion of gaseous fuel outside of the boiler. The boiler further comprises unburnt gas burner in the exhaust gas duct for burning unburnt content in the combustion gas flowing in the duct. The unburnt gas burner includes a nozzle for injecting premixture flow of fuel and combustion air and flame holding plate located near the downstream side of the outlet of the nozzle to interrupt the premixture flow to form a circulating flow on downstream side of the flame holding plate. As gaseous fuel and air are mixed in advance and a flame is formed, the flame length can be shortened. Furthermore, the flame holding plate enables to reduce NOx generated. Unburnt gas burner provided in the exhaust gas duct makes it possible to notably reduce the concentration of NOx discharged to the outside of the system.

Low NOx boiler

A method of combusting a coal-water mixture fuel. The mixture is atomized into a conically-shaped primary pre-combustion chamber. Primary air is supplied, at a rate smaller than that required for complete burning of the mixture and in the form of a swirl about the axis of the jet of the atomized mixture, from the peripheral portion of the primary pre-combustion chamber into a secondary pre-combustion chamber connected to said primary pre-combustion chamber, thus forming a region of low pressure around the jet of the mixture. The region of low pressure serves to induce the atmosphere gas from the secondary pre-combustion chamber of higher temperature back into the primary pre-combustion chamber of a lower temperature, so that the water content of the mixture is evaporated and the mixture is ignited by the heat of the hot atmosphere gas. Then, the mixture is burnt in the secondary pre-combustion chamber in the presence of the remainder portion of the primary air, at a comparatively small air-to-ratio, so that a region of a reducing atmosphere is formed to suppress the generation of NOx. Then, secondary air is supplied, in the form of a swirl about the axis of the jet of the mixture and at a rate sufficient to completely burn the mixture, into the furnace connected to the secondary pre-combustion chamber, thus completely combusting the coal-water mixture.

Method of and apparatus for combusting coal-water mixture

Growing community of inventors

Kure, Japan

Fumio Koda