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Marine boiler structure

a boiler structure and marine technology, applied in steam boilers, water-tube boilers, lighting and heating apparatus, etc., can solve the problems of high heat stress in marine boilers due to size reduction, corrosion concentrates at a lower portion of superheaters, etc., and achieve the effect of eliminating or reducing conventional temperature imbalances

Inactive Publication Date: 2010-10-07
MITSUBISHI HEAVY IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a marine boiler structure that addresses the problem of non-uniform corrosion progression and thinning of tubes in the superheater. The invention achieves this by remedying the temperature distribution in the combustion gas passing through the superheater and evaporator tube bundle. The invention includes a bottom air port and an ejecting direction of the bottom air that supplies part of the combustion air as bottom air from the furnace bottom portion. This helps to change the flow pattern of the combustion gas and achieve a more uniform temperature distribution in the superheater. The invention also includes a side air port that supplies part of the combustion air as side air from the upper portion of the furnace, which is located closer to the superheater relative to the burner center line. This helps to reduce NOx in the combustion gas. Overall, the invention provides a marine boiler structure that addresses the problem of non-uniform corrosion progression and thinning of tubes in the superheater and evaporator tube bundle, while also reducing NOx in the combustion gas.

Problems solved by technology

In the conventional marine boiler structure described above, because the gas temperature distribution of the combustion gas becomes unbalanced, there is a problem in that corrosion concentrates at a lower portion of the superheater 5.
Furthermore, heat stress in the marine boiler is high due to size reduction, and the problem of increasing level of NOx has been pointed out, reaching about 300 to 400 ppm in some cases, for example, in a marine boiler 1 for oil-fired combustion.

Method used

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Experimental program
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first embodiment

[0048]As shown in FIGS. 1 and 2, in a marine boiler structure of this embodiment, bottom air ports 20 that supply part of combustion air as bottom air from a furnace bottom portion 2a of a furnace 2 are provided in a marine boiler 1A which is configured so that combustion gas generated by combustion in burners 3 flows from the furnace 2, passing through a superheater 5 and an evaporator tube bundle 6. The bottom air ports 20 are located closer to the superheater 5 relative to center lines CL of the burners 3, and in addition, an ejecting direction of the bottom air jetted from the bottom air ports 20 is set within an angular range θ1 inclined in the direction of the burners 3 from a vertically upward direction.

[0049]Note that, the above-described bottom air ports 20 are connected to bottom air ducts 21 formed in the exterior of the furnace 2, and the combustion air is supplied through these ducts.

[0050]The bottom air ports 20 are provided, for example as shown in FIG. 2A, in the sam...

second embodiment

[0059]A second embodiment of a marine boiler structure according to the present invention will be described based on FIGS. 3 and 4A. Note that, identical reference signs are assigned to components similar to those of the above-described embodiment, and detailed descriptions thereof will be omitted.

[0060]In this embodiment, a marine boiler 1B is provided with side air ports 30 that supply part of the combustion air as side air from the upper portion of the furnace 2. The side air ports 30 are provided in the same blast box 3a as the burners 3.

[0061]The side air ports 30 described above are arranged closer to the superheater 5 relative to the burner center line CL, and the ejecting direction of the side air is adjustably set within an angular range ±θ2 that inclines toward both the superheater 5 and the burners 3, with reference to the vertically downward direction. That is, it is preferable that θ2 in this case be set to about 30 degrees, and therefore, it is desirable to provide an ...

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Abstract

Provided is a marine boiler structure that is capable of remedying non-uniformity in corrosion progression by making the temperature distribution of combustion gas that passes through a superheater uniform, and that is also capable of reducing the level of NOx contained in the combustion gas. In a marine boiler structure configured such that combustion gas generated by combustion in a burner flows from a furnace through a superheater and an evaporator tube bundle, a bottom air port that supplies part of the combustion air as bottom air from a furnace bottom portion of the furnace is provided, the bottom air port is positioned closer to the superheater relative to a burner center line, and an ejecting direction of the bottom air is set within a range inclining in the burner direction from the vertically upward direction.

Description

TECHNICAL FIELD[0001]The present invention relates to a marine boiler structure such as a marine boiler, a marine reheat boiler, etc., installed in a vessel.BACKGROUND ART[0002]In comparison with a land boiler used in a power plant, etc., the compactness of the structure is conventionally prioritized in a marine boiler installed in a vessel due to a large constraint on the installation space.[0003]In a conventional marine boiler 1 shown in FIG. 5, one or a plurality of burners 3 are installed at an upper portion of a furnace 2. Combustion gas generated by combusting a fuel in the burners 3 sequentially passes through a front bank tube 4, a superheater 5, and an evaporator tube bundle (rear bank tube) 6, which are disposed downstream of the furnace 2, to carry out heat exchange with fluid such as water, etc. flowing in the tubes. Upon completing heat exchange in this way, the combustion gas passes through an outlet-side gas duct 7 and is ejected to the exterior of the marine boiler 1...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F23M5/00
CPCF22B31/00F23C5/08F22B21/081F23C7/04F23L9/04F23C5/24F22B37/40F22G5/04F23L99/00
Inventor IMADA, JUNJIUCHIDA, ISAO
Owner MITSUBISHI HEAVY IND LTD