Miura Co., Ltd.

Yukihiro Tokunaga

Osamu Tanaka

Kenji Yasui

Yusuke Okamoto

Yuji Yoshinari

Soji Sumi

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.

Boiler

First, to decrease an amount of emitted nitrogen oxides to zero as much as possible and also decrease an amount of emitted carbon monoxide to a permissible level. Second, to save energy on combustion at a low air ratio close to 1.0. Third, to attain a stable air ratio control in a low air ratio combustion region. Included are a combustion step in which hydrocarbon-containing fuel is burned by the burner to generate gas free of hydrocarbons but containing oxygen, nitrogen oxides and carbon monoxide, an endothermic step in which endothermic device is used to absorb heat from gas generated in the combustion step, a hazardous-substance decreasing step in which the gas is brought into contact with an oxidation catalyst after the endothermic step to oxidize carbon monoxide contained in the gas by oxygen and reduce nitrogen oxides by carbon monoxide, and a concentration ratio adjusting step in which a concentration ratio of oxygen, nitrogen oxides and carbon monoxide in gas on the primary side of the oxidation catalyst is adjusted to a predetermined concentration ratio on the basis of concentration ratio characteristics of the burner and the endothermic device by using the air-ratio adjusting device of the burner.

Combustion method and combustion apparatus

A combustion method applied to a water-tube boiler and a regenerator of an absorption-type refrigerator includes a concentration ratio adjusting step of adjusting a concentration ratio of nitrogen oxides, carbon monoxide, and oxygen in a gas from a gas generation source to a predetermined reference concentration ratio, and a hazardous-substance decreasing step of decreasing nitrogen oxides, using an oxidation catalyst having characteristics of decreasing the concentrations of nitrogen oxides and carbon monoxide on a secondary side to substantially zero when the concentration ratio on a primary side is set to be a reference concentration ratio, in which the concentration ratio adjusting step detects the concentration of oxygen on the secondary side of the oxidation catalyst to control the concentration ratio so that a detected oxygen concentration becomes a set oxygen concentration substantially close to zero. According to the combustion method, the emission amount of nitrogen oxides can be decreased to close to zero as much as possible, and the emission amount of carbon monoxide can be decreased to a permissible range. Further, the control of a concentration ratio can be performed stably by detecting the concentration of oxygen.

First, the emission amount of nitrogen oxides can be decreased close to zero as much as possible, and the emission amount of carbon monoxide is decreased to a permissible range. Second, energy saving by combustion at a low air ratio close to 1.0 is realized. Third, air ratio control is performed stably in a combustion region at a low air ratio. The present invention includes: a combustion step of burning hydrocarbon-containing fuel in the burner, thereby generating gas free of hydrocarbons but containing oxygen, nitrogen oxides, and carbon monoxide; a hazardous-substance decreasing step of bringing the gas into contact with an oxidation catalyst, thereby oxidizing carbon monoxide contained in the gas by oxygen and reducing nitrogen oxides by carbon monoxide; and a concentration ratio adjusting step of adjusting a concentration ratio of oxygen, nitrogen oxides, and carbon monoxide in gas on a primary side of the oxidation catalyst to a predetermined concentration ratio in which a concentration of nitrogen oxides on a secondary side of the oxidation catalyst is decreased to substantially zero or a value equal to or lower than a predetermined value and a concentration of carbon monoxide on the secondary side of the oxidation catalyst is also decreased to substantially zero or a value equal to or lower than a predetermined value.

Method of treating nitrogen oxide-containing gas

To provide a boiler capable of realizing a reduction in O, a reduction in NOx, and a reduction in CO. The present invention provides a boiler including: a premixed gas burner, and water tubes in close proximity to the premixed gas burner, characterized in that the premixed gas burner ejects a premixed gas toward the water tubes at a predetermined angle; and the boiler further includes a fuel supply portion capable of supplying at least one of a gas fuel and a premixed gas provided at a position on a downstream side of and spaced apart by a predetermined distance from the premixed gas burner.

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Matsuyama, Japan

Yukihiro Tokunaga