JPH01312302A - Rectangular shell-and-tube once-through boiler - Google Patents

Abstract

PURPOSE:To uniform the velocity of combustion gas passing through the groups of water pipes ranging from the upper stream side to the lower stream side by setting the water pipe span on the lower stream side of the combustion gas passage wider than the water pipe span on the upper stream side. CONSTITUTION:Water pipe groups A, B, and C in a once through boiler are laid out so that water pipes 10, 11, and 12 are arranged respectively based on specified dimensions linearly. The pipe span of the water pipes 10, 11, and 12 comprising the water pipe groups A, B, and C is designed to be narrowed from the upper stream side in the direction of the combustion gas flow to the down stream side, which makes it possible to equalize the flow of the combustion gas substantially at a specified velocity from the lower stream side or the side of a burner 1 up to the down stream side or the side of a gas duct 2. In other words, although the volume of the combustion gas is large on the upper stream side, the combustion gas can flow without a marked pressure loss, since the water pipe span is wide, while on the down stream side the volume of the combustion gas is reduced, but the water pipe span is narrow, which increase the velocity of the combustion gas. Therefore, the pressure loss is minimized in a boiler drum and the recovery of heat from the combustion gas on the down stream side is higher. Furthermore, the heat transmission efficiency is higher,which makes it possible to provide higher heat transmission efficiency from the combustion throughout the entire passage as well.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a square multi-tubular once-through boiler, and more particularly to a square multi-tubular once-through boiler in which combustion gas is distributed horizontally. be.

[Prior art]

Generally, small multi-tubular once-through boilers are manufactured based on a cylindrical can structure. This is because, in order to improve the combustion efficiency of a heating means such as a burner, it is considered desirable to arrange the water pipes in an annular shape and use the inside thereof as a combustion chamber.

However, such a can structure tends to occupy a large amount of space depending on the location and arrangement of the boiler, so in recent years various multi-tube once-through boilers based on the so-called square can structure have been proposed. has been done.

Here, the square can structure refers to a structure in which groups of wood pipes made up of a large number of water pipes arranged in series are arranged opposite each other to form a combustion chamber between them, and the combustion gas of the burner flows between the groups of wood pipes. Pass in cross directions.

[Problem that the invention seeks to solve]

Generally, the combustion gas of a boiler burner has a high temperature and a large volume on the upstream side, but as it moves downstream, the temperature decreases and the volume decreases due to heat transfer to the water pipes.

However, in conventional quality-flow boilers with a square structure, each water tube group is arranged parallel to each other or slightly wider on the downstream side, so the combustion gas flow inside the combustion chamber has a large flow velocity between the upstream and downstream sides. decreases.

Furthermore, since each water tube group of the above-mentioned once-through boiler has water tubes arranged at equal intervals, the combustion gas flowing through the gaps between the water tubes is faster on the upstream side and slower on the downstream side.

Therefore, the combustion gas in a conventional once-through boiler has a large pressure loss on the upstream side (and a low flow rate on the downstream side, resulting in a decrease in heat transfer efficiency).

This means that the once-through boiler has insufficient air blowing capacity and a reduction in boiler efficiency, which is an impediment to reducing the initial cost and running cost of the boiler.

[Means for solving problems]

In view of the above-mentioned problems, this invention was made to make the flow velocity of combustion gas substantially uniform from the upstream side to the downstream side. On the other hand, in a multi-tube once-through boiler that allows combustion gas to flow in cross directions, the opposing water tube groups are connected from the upstream side in the combustion gas flow direction.
This is a square multi-tube once-through boiler that is arranged in a tapered manner toward the downstream side.

[Effect]

In the square multi-tube once-through boiler according to the present invention, the interval between the water tubes on the downstream side in the direction of the combustion gas flow path is set wider than the interval between the water tubes on the upstream side, so that the combustion gas passes between the wood tubes. The flow velocity can be made uniform from the second flow side to the downstream side.

〔Example〕

FIG. 1 shows an embodiment of a square multi-tubular once-through boiler according to the present invention. The wood tubes in the once-through boiler of this embodiment are arranged in six rows, three rows on each side, so as to be substantially symmetrical.

In the drawing, (8), (B), and (C) are water pipe groups, respectively.
(1) shows the burner, (2) shows the flue, and (5) shows the bellows connected to the upper and lower ends of each water tube group.

The water tube groups (A), (B), and (C) are water tubes 00), (Ill, 02) of predetermined dimensions arranged in a straight line, respectively.

The water tube group (A) functions as a water cooling wall of the boiler, and has water tubes 00) of the same diameter arranged at equal intervals.
It is constructed by closing the gaps between each woodwind 00 with plate-like members 03) having the same height. This water tube group (A) is located at the outermost side of the boiler case, and is connected to the corresponding water tube group in the direction of flow of combustion gas from the burner (1) (from top to bottom in the figure). The distance between (8゛) and (8゛) is narrow.

Further, the water tube group (B) uses water tubes (11) having approximately the same diameter as the water tube group (A), and is arranged so that the interval d2 on the downstream side is narrower than the interval d on the upstream side. . The water tube group (B) is arranged substantially parallel to the water tube group (Bo) on the other side corresponding to the inner side of the water tube group (8).

Therefore, the combustion gas flow path formed between the water tube group (8) and this water tube group (B) becomes gradually narrower from the upstream side to the downstream side in the flow direction.

Furthermore, each water pipe (II) of the water pipe group (B) and the wood pipe group (A
) are arranged in a staggered manner so as not to coincide with each other in the left-right direction.

Those water pipe groups (B) and the corresponding water pipe groups (Bo
) between the water pipes (11) in the center is a fire-resistant bulkhead (3
) has been established.

On the other hand, the water tube group (C) is the water tube group (A), (
B).

(C) water pipe 00), water pipe 02 with a smaller diameter than (11)
) are arranged in a straight line, and are arranged inside the water tube group (B) and on the downstream side of the fireproof partition wall (3).

The distance d between each water tube 02) of the water tube group (C) and each water tube (11) of the adjacent water tube group (13) is set narrower than the above-mentioned distance d2.

The E header (5) is connected to the upper and lower parts of the opposing water pipe rows as described above, and the water supply system is common, but the steam piping system can be separated.

In the square multi-tube once-through boiler having the above configuration, when the combustion chambers are ignited, the combustion gas exchanges heat with the water tubes (11) on the upstream side of the water tube group (B) mainly by radiation heat transfer within the combustion chamber. Then, through the gaps between the wood pipes (11) on the upstream side of the water pipe group (B), the wood pipe group (A) and the water pipe group (B) are connected.
It flows into the space between the water pipe group (8) and the water pipe group (B).
). Here, each water pipe OO on the upstream side of the water pipe group (B) is equal to each water pipe 0ω on the upstream side of the water pipe group (A).
Since the water pipes 0ω on the upstream side of the water pipe group (8) are arranged in a staggered manner, each water pipe 0ω on the upstream side receives heat exchange by radiation from the gap between the water pipes θ1). This combustion gas is further transferred to the water tube group (
Gap between each water pipe (11) on the downstream side of B), water pipe group (B)
The flue (
2) is discharged from the system. At this time, the partition wall (3) acts to bend the direction of the flow of combustion gas in the first half of the upstream side of the combustion chamber, as shown by the arrow in the figure.

As described above, as the combustion gas moves from the burner (1) side to the flue (2) side, its temperature decreases and its volume decreases.

However, in the square multi-tube once-through boiler according to this invention, each water is divided into groups (A), (B), (C) (7) Water tubes QQ
I, (11).

02) is narrowed from the upstream side to the downstream side in the flow direction of the combustion gas, the combustion gas flows approximately from the burner (1) side (i.e. upstream side) to the flue (2) side (i.e. downstream side). Flows at a constant velocity. In other words, although the volume of combustion gas is large on the upstream side, the gap between the water tubes is wide, so it can pass through without pressure loss.On the downstream side, the volume of combustion gas is reduced, but the gap between the water tubes is narrow, so the flow rate is high. It will pass through.

Therefore, according to the present invention, the pressure loss in the can body is small, the heat recovery rate from downstream combustion gas is high, and further,
It is possible to provide a multi-tubular once-through boiler with high heat transfer efficiency from combustion gas throughout the entire flow path.

〔Effect of the invention〕

As explained above, in the square multi-tubular once-through boiler according to the present invention, combustion gas flows at a substantially uniform flow velocity from upstream to downstream, so that local pressure loss and reduction in heat transfer efficiency can be prevented. I can do it.

Therefore, since the furnace pressure can be reduced, the blowing means can be made lower in output and smaller in size, and the heat transfer efficiency of the can body itself can be improved, making it possible to further improve boiler efficiency. A multi-tubular once-through boiler with low cost and running cost can be provided.

Furthermore, the present invention can be easily applied by making minor modifications to a conventional production line without constructing a new production line, so that the implementation cost can be kept extremely low.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional plan view showing an embodiment of a square multi-tubular once-through boiler according to the present invention. 00), (Ill, 02)...Water tube patent applicant
Miura Kogyo Co., Ltd. Figure 1

Claims (1)

[Claims] In a multi-tube once-through boiler in which a plurality of water tubes are arranged parallel to each other and combustion gas is allowed to flow in cross directions through these water tube groups, From the direction upstream,
A square multi-tubular once-through boiler characterized by its arrangement tapering toward the downstream side.