Miura Co., Ltd.

Miura Institute of Research & Developement Co., Ltd.

Other

Kanta Kondou

Noboru Takubo

Toshihiro Kayahara

Osamu Tanaka

Akinori Kawakami

Shigehiro Watanabe

Tomohiro Ookubo

Takashi Morimatsu

Koichi Wakae

Boiler efficiency is further improved and the whole boiler body is slimmed down by totally improving heat transfer surfaces confronting gas flow passages, i.e., by forming the heat transfer surface structure into three stages, and moreover by making effective use of the whole heat transfer surfaces of water tubes equipped with fully circumferentially finned water tubes. The water-tube boiler includes: an annular first water tube array made up of a plurality of water tubes and having a first opening; an annular second water tube array made up of a plurality of water tubes and having a second opening, the second water tube array being arranged outside the first water tube array; a combustion chamber provided inside the first water tube array; and a gas flow passage leading from the first opening to the second opening and defined between the two water tube arrays, wherein heat transfer surfaces confronting the gas flow passage are structured into a high-temperature heat transfer surface structure, a middle-temperature heat transfer surface structure, and a low-temperature heat transfer surface structure, as viewed from an upstream side along gas flow.

Water-tube boiler

In a water-tube boiler in which pollutant (especially NOx) emissions are reduced, a plurality of water tubes arranged in an annular shape are provided. At least some of the water tubes thereof are spaced apart along an annulus so as to provide a plurality of gaps therebetween. A combustion-reaction ongoing gas passes through these gaps, and a temperature thereof is lowered to 1400.degree. C. upon contact with the water tubes. The boiler further includes a second plurality of water tubes arranged in an annular shape outside of the first plurality of water tubes. By adjusting the arrangement of the water tubes along respective annuli and/or adjusting an orientation of the tubes along their length (so as to be straight, tilted, or bent), control of the exhaust emissions is enhanced.

The invention provides a water-tube boiler and a burner capable of realizing a reduction in NO.sub.x and CO in both the combustion of liquid fuel and the combustion of gaseous fuel. The water-tube boiler comprises a burner which uses liquid fuel or gaseous fuel switchably, characterized in that a plurality of water tubes are arranged into an annular shape in a zone where burning-reaction ongoing gas derived from the burner is present within a combustion chamber. The water-tube boiler comprises a burner which uses either liquid fuel or gaseous fuel. A first water tube array is formed by arranging a plurality of water tubes into an annular shape in a zone where burning-reaction ongoing gas derived from the burner is present within a combustion chamber. Gaps are provided between adjacent water tubes of the first ongoing gas to flow therethrough. A zone is provided around the first water tube array to allow burning reaction to be continuously effected.

Water-tube boiler and burner

The water-tube boiler fulfills the reduction in NO.sub.x with a simple constitution, and achieves reduction in NO.sub.x and reduction in CO at the same time with a simple constitution. In the water-tube boiler, a plurality of water tubes (5) are arranged in a zone where burning-reaction ongoing gas derived from a burner (10) is present within a combustion chamber (9), and exhaust gas recirculation equipment (26) is provided to feed part of exhaust gas exhausted from the combustion chamber 9 to the burner 10.

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Matsuyama, Japan

Kanta Kondou