Miura Co., Ltd.

Soji Sumi

Yukihiro Tokunaga

Tomohiro Ookubo

Kyousuke Ookubo

A boiler according to the present invention includes: a plurality of heat transfer tubes arranged to form a cylindrical shape between an upper header and a lower header to constitute a heat transfer tube row; a boiler body cover of a cylindrical shape provided between the upper header and the lower header so as to surround the heat transfer tube row; and a heat insulating material provided to a predetermined region of a space between the heat transfer tube row and the boiler body cover.

Boiler

A boiler has an upper header, a lower header and a heat-transfer tube. The heat-transfer tube connects the upper header with the lower header. The hear-transfer tube is provided with projections such that a heat-transfer area per unit length of the heat-transfer tube is smaller in an upstream region than that in a downstream region of combustion gas.

A boiler has a plurality of inner heat-transfer tubes which makes up an inner heat-transfer tube row, and a plurality of outer heat-transfer tubes which makes up an outer heat-transfer tube row. Inner fins project from each of the inner heat-transfer tubes on an outer circumferential side of the inner heat-transfer tube row. Outer fins project from each of the outer heat-transfer tubes on an inner circumferential side of the outer heat-transfer tube row. An inner row communicating portion is provided in a lower end portion of the inner heat-transfer tube row. An outer row communicating portion is provided in an upper end portion of the outer heat-transfer tube row. An inner-fin absent region is provided in a lower end portion of each of the inner heat-transfer tubes. An outer-fin absent region is provided in a longitudinally middle portion of each of the outer heat-transfer tubes.

To provide a boiler equipped with a water tube group performing heat recovery effectively and having expansion heating surfaces (fins or the like) of high durability, the present invention provides a boiler () including: a boiler body () having an inner water tube group () and an outer water tube group () that are arranged in an annular fashion; and a burner () arranged at a central portion of the inner water tube group (), in which: intervals between adjacent inner water tubes constituting the inner water tube group () are closed except for portions where a gas flow passage is provided; and stud fins (and) are provided on a portion of at least one of the inner water tube group () and the outer water tube group () in a vicinity of the gas flow passage.

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Matsuyama, Japan

Soji Sumi