JPH09280502A - Multitubular once-through boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a combustion chamber compact and arrange rationally the flow of combustion gas and a heat transfer surface by providing an opening part for guiding combustion gas in a side opposed to a plane combustion burner provided in the side surface of rows of water tubes in an annular arrangement, and providing one row or more of water tubes in a semiannular arrangement in the outlet of the opening part so as to form a combustion gas passage. SOLUTION: An upper header and a lower header of a multitubular one-through boiler communicate with each other through many vertical water tubes 21 to form the rows of water tubes in a substantially annular arrangement. A plane combustion burner 24 is attached to one part of the rows of water tubes so that a combustion chamber 26 is formed inside the rows of the water tubes. A part of the annular rows of water tubes opposed to thr plane combustion burner 24 through the combustion chamber 26 is opened throughout an almost whole length in the direction of height. The vertical water tubes 21 are adjacently arranged so that the rows of water tubes are formed in a semiannular arrangement between the opening part 35 and a smoke chamber 27. Thus, a combustion gas passage 29 is formed between the annular rows of water tubes and the semiannular rows of water tubes. Further, The outside of the semiannular rows of water tubes is provided with a smoke chamber cover 28 having the smoke chamber 27, so that a combustion gas passage 30 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-tube type once-through boiler, and more particularly to a water tube arrangement structure for a multi-tube once-through boiler of a type in which combustion gas is passed through a plurality of water tubes in a direction orthogonal to a tube axis. Is.

[0002]

5 and 6 are views showing a conventional small multitubular boiler, FIG. 5 is a sectional view, and FIG. 6 is a sectional view taken along line VI-VI of FIG. As shown in FIG. 5, the can of the small multi-tube boiler has a structure in which an annular upper pipe header 2 and a lower pipe header 3 are connected at a predetermined interval by a large number of vertical water pipes 1. ing. Then, the combustion chamber 6 is formed so that the inside of the ring-shaped water pipe array formed by the vertical water pipes 1 becomes the combustion chamber 6.
The burner 4 on the upper end face or the lower end face (upper end face in the figure) of the
Is installed and the outside of the water pipe array is surrounded by a smoke chamber cover 8 provided with a smoke passage 7, thereby forming a combustion gas passage 9.

In the multi-tube boiler having the above-mentioned structure, the water in the vertical water pipe 1 is heated by the combustion gas of the burner 4, and the water supplied to the lower head 3 is taken out from the upper head 2 as steam. In the above-mentioned multi-tube boiler,
In order to improve the combustion efficiency of the heating means such as a burner, it is considered desirable to arrange the water pipe in an annular shape as shown in FIG. 6 and use the inside as a combustion chamber.

[0004]

In the multi-tube type once-through boiler having the above-mentioned structure, the combustion chamber is provided inside the annular water pipe array, but the burner is concentrated at one location on the upper end of the cylindrical combustion chamber. Because of this, the combustion surface load becomes high, and the diameter and length of the combustion flame become large. Therefore, a combustion chamber with a large space is required, and the volume and installation space of the boiler as a whole must be increased.

Further, it is generally known that heat exchange between a water pipe and combustion gas is performed better when the gas flow direction and the water pipe axis are orthogonal to each other than when they are parallel or oblique. There is. This is because vortices are more likely to be formed behind the water pipe due to the flow in the orthogonal direction, and the heat transfer coefficient due to the turbulent flow can be improved.

However, in the conventional method, the combustion gas of the burner is ejected in parallel with the pipe axis, so that the combustion gas passing through the gap between the water pipes crosses the pipe shaft obliquely and transfers heat to the combustion gas passage. However, there is a drawback in that only a flow state that is disadvantageous in terms of heat transfer can be obtained because the gas is discharged from the flue.

Further, in order to improve the heat transfer coefficient, it is effective to increase the velocity of the combustion gas, but in the above-mentioned configuration, soot is clogged in the gap between the water pipes and rust due to dew condensation of the combustion gas is generated. There are problems such as occurrence, it is not possible to make the gap below a limited value, and because there are many gaps all around the annular water pipe row, the gas flow velocity in the gap between water pipes is made faster However, there was a limit to improving heat transfer.

The present invention has been made in view of the above-mentioned circumstances, and by downsizing the combustion chamber and rationalizing the flow of the combustion gas and the arrangement of the heat transfer surface, the present invention is small and has a small installation area. It is intended to provide a highly efficient multi-tube once-through boiler.

[0009]

In order to achieve the above object, a multi-tube type once-through boiler of the present invention is equipped with a flat combustion burner on the side surface of a row of water pipes arranged in an annular shape, and the opposite side of the flat combustion burner. An opening portion for introducing combustion gas is provided in, and one or more rows of semi-annular water pipes are arranged at the outlet of the opening portion to form a combustion gas passage.

In the multi-tube type once-through boiler of the present invention, the burner is of a flat combustion type, and the burner is provided on the side surface of the combustion chamber instead of the end surface. Here, the flat combustion burner is a burner capable of burning a gas or liquid fuel by forming a short flame on a flat surface with a small combustion sectional load,
It features low combustion noise and low emission of harmful substances.

Therefore, the combustion chamber can be burned in a shape having an extremely small diameter. The burner combustion gas can flow through the gas passage in a state orthogonal to the water pipe axis and at a higher speed than the sufficiently narrowed opening, and the heat transfer can be significantly improved.
Therefore, it is possible to realize a small-sized and highly efficient boiler with improved heat transfer efficiency while eliminating the need for a wide combustion chamber space as in the past.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a multi-tube once-through boiler according to the present invention will be described below with reference to the drawings. 1 and 2 are views showing an embodiment of a multi-tube type once-through boiler of the present invention, FIG. 1 is a sectional view, and FIG. 2 is a sectional view taken along line II-II of FIG. As shown in FIG. 1, a can body of a multi-tube once-through boiler has an upper head 22 and a lower head 23, and the upper head 22 and the lower head 23 are connected by a number of vertical water pipes 21. ing. These many vertical water pipes 21 form a substantially circular water pipe row. Then, a flat combustion burner 24 is provided in a part of the water pipe array.
Is attached, and the combustion chamber 26 is formed inside the row of water tubes. The flat combustion burner 24 is attached to the water pipe 21 by a mounting member 31.

As shown in FIG. 2, a part of the tubular water pipe array, which is opposed to the flat combustion burner 24 with the combustion chamber 26 in between, is opened over substantially the entire length in the height direction. The vertical water pipes 21 are adjacent to each other to form a semi-annular water pipe array between the opening 35 and the flue 27, thereby forming a combustion gas passage 29 with the annular water pipe array. . Further, the combustion gas passage 30 is configured by equipping the smoke chamber cover 28 provided with the smoke passage 27 on the outside of the semi-annular water pipe array.

In the example shown in FIG. 2, the ring-shaped water pipe array has different diameters DP from the center on the burner side and the opening side.
1 and DP2, DP1 can be arranged at any value between DP2 and the arrangement diameter DP3 of the semi-annular row.

FIGS. 3 and 4 are views showing another embodiment of the two rows of water pipes, which are annular and semi-annular, respectively. In the example shown in FIG. 3 and FIG. 4, the two rows of annular and semi-annular water pipes have the same pitch angle (A in the drawings) of adjacent water pipes and a half pitch angle (A / 2 in the drawings) in the opposing rows. ) It is arranged so that it is displaced. The embodiment shown in FIG. 3 is an example in which the heights of the fins 32 connecting adjacent water pipes of the semi-annular water pipe row are changed so that the pitch angle becomes the same as that of the annular water pipe row, and shown in FIG. The embodiment is an example in which a part of the ring-shaped water pipe array is constituted by a vertical water pipe 33 having a small water pipe diameter.

Next, the operation of the embodiment of the multi-tube type once-through boiler shown in FIGS. 1 to 4 will be described. The flame 25 formed by the planar combustion burner 24 is a short flame and has a uniform ejection velocity distribution in the height direction of the vertical water pipe 21. Flat burning burner 24
Is attached to the water pipe 21 by the attachment member 31, is gas-sealed, and the vertical water pipes 21 of the annular water pipe row are arranged so as to be in close contact with each other, so that the burner combustion gas burns with the mounting surface of the burner 24. It is gathered in the opening portion 35 provided so as to separate the chamber 26.

At this time, the combustion gas flowing into the opening 35 becomes uniform in the height direction of the vertical water pipe 21 according to the jet velocity distribution of the burner, and is high speed at the opening which is orthogonal to the water pipe axis and is sufficiently narrowed. And the combustion gas passage 2
Very high heat transfer can be obtained at 9,30.

Further, when the two water pipe rows of the annular shape and the semi-annular shape are arranged so that the pitch angles of the water tubes adjacent to each other are equal and the row pitches are deviated from each other by the half pitch angle, the main gas flows of the rows are opposed to each other. Since the water flows in a zigzag manner so as to reach between the water pipes and the valleys of the water pipes, a stagnation region of the flow, that is, a so-called dead water region does not occur, so that the heat transfer effect can be further enhanced.

In the above embodiments, the example of the structure of two rows of annular and semi-annular has been described, but the gas passages may be constituted by a plurality of rows of water pipes of semi-annular shape, and the gas passages 29 and 30 are further provided. The facing water pipe may be provided with means for promoting heat transfer such as vertical fins and horizontal fins.

[0020]

As described above, according to the present invention, a flat combustion burner is provided on the side surface of a row of water pipes arranged in an annular shape, so that an elongated combustion space with a small diameter can be obtained and the combustion chamber exits. The flue gas becomes a high-speed cross-flow on the water pipe wall that is rationally arranged up to the flue, and the heat transfer efficiency can be significantly improved. Can be provided.

Further, according to the present invention, by equipping the flat combustion burner, there is a very practical effect as a space-saving boiler in a dense area such as an urban area where combustion noise is low and harmful substances are little emitted.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of a multi-tube once-through boiler according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a view showing another example of the water pipe array, and is a cross-sectional view corresponding to FIG. 2.

FIG. 4 is a view showing still another example of the water pipe array, and is a cross-sectional view corresponding to FIG. 2.

FIG. 5 is a vertical sectional view showing a conventional multi-tube once-through boiler.

6 is a sectional view taken along line VI-VI of FIG.

[Explanation of symbols]

 21, 33 Vertical water pipe 22 Upper pipe header 23 Lower pipe header 24 Planar combustion burner 25 Flame 26 Combustion chamber 27 Flue 28 Smoke chamber cover 29, 30 Combustion gas passage 32 Fin 35 Opening

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiro Takemura 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Ebara boiler Co., Ltd.

Claims (2)

[Claims] 1. A flat combustion burner is provided on a side surface of a row of water pipes arranged in an annular shape, an opening for introducing combustion gas is provided on an opposite side of the flat combustion burner, and one or more rows of semi-annular rings are provided at an outlet of the opening. A multi-tube once-through boiler, characterized in that the water pipe rows of the above are arranged to form a combustion gas passage. 2. The water pipe array forming the combustion gas passage,
The multi-tube once-through boiler according to claim 1, wherein adjacent water pipes are arranged such that the pitch angles of the water pipes are equal to each other and the pitches of the adjacent water pipes are offset from each other by a half pitch angle.