JPH0711283Y2 - Square multi-tube once-through boiler - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a can body of a type in which combustion gas is made to flow in a direction intersecting with a water pipe group arranged in cascade, and an air ratio is set to 1 or more. The present invention relates to a square multi-tubular once-through boiler equipped with a mixed gas burner.

[Conventional technology]

Due to recent demands for energy saving and space saving, there is a tendency that the efficiency and size of a multi-tube once-through boiler are also increased. In particular, various multi-tube once-through boilers based on a so-called rectangular can structure have been proposed in order to reduce the installation space.

Furthermore, due to recent environmental pollution problems and the like, boilers are also required to reduce harmful combustion exhaust emissions.Therefore, there is a tendency for gas burners to be adopted. Among them, premixed gas burners are used to complete the combustion reaction. It is often used because of its fast burning and good flammability.

[Problems to be solved by the device]

The above rectangular can body has water pipes arranged within a substantially rectangular shape, and a clear combustion chamber is formed by the arrangement of the water pipes, and the combustion gas generated in this combustion chamber is passed through the water pipe gap. There is a method in which the water pipes are densely arranged, a combustion reaction is caused in a narrow space between the water tubes, and a combustion gas is circulated. In the former can body type,
Since the combustion space is clearly formed, various types of burners such as premixed burners, all primary air premixed burners, partial premixed burners, etc. can be applied, but in the latter case type Since the jet airflow from the burner has a small distance for entraining the surrounding air, it is inevitable to select an all primary air type premix burner, especially a surface combustion burner that forms a short flame.

However, this type of surface combustion burner, as described above,
Although the combustion reaction is fast and the combustibility is good, the range of air ratio and combustion surface load that can perform stable flame holding is narrow, and if it is out of this range, there is a disadvantage that flashback or blowout will occur. In most cases, the maximum combustion amount is small and the adjustment range of the combustion amount is narrow. In recent years, boilers are required to have a wide load range in addition to improved efficiency.Therefore, burners are also required to have an increased combustion surface load and a stable combustion range. ing. However, in this way, surface combustion burners that aim to increase the combustion surface load and expand the stable combustion range tend to be expensive and have a complicated structure, and it is difficult for the boiler side to select the burner. The problem arises.

That is, in the market, there is a demand for a boiler that can handle a wide fluctuation range of the required load regardless of the type of surface combustion burner.

[Means for Solving the Problems]

The present invention has been made to solve the above-mentioned problems, and a plurality of water pipes are arranged in parallel in a substantially rectangular compartment, and the air ratio of the air-fuel mixture is arranged on one side of the compartment. Is a premixed combustion burner of all primary air type in which is set to 1 or more, and a multi-tube once-through boiler of the type in which combustion gas is circulated in the cross direction with respect to the water pipe, The distance between at least two water pipes located immediately in front of the combustion burner is set to not more than twice the diameter of the water pipe, and the distance between the adjacent water pipes is 1 / the diameter of the water pipe.
It is a square multi-tube once-through boiler set to 2 or less.

[Action]

In the square multi-tube once-through boiler according to the present invention, the supply pressure of the premixed air is high, and in the conventional combustion burner, even if the flame is lifted or blown out, the position is immediately before the surface combustion burner. With a water pipe that can hold flame,
Furthermore, since this water pipe has a catalyst for combustion reaction and deposits such as protrusion-like turbulence promoters, it is possible to stably hold flame even during high load combustion.

〔Example〕

FIGS. 1 to 4 show an embodiment of a square multi-tube once-through boiler according to the present invention.

In the drawing, (A) shows a can body and (B) shows a combustion burner.

The can body (A) includes a pair of water pipe walls (10) and a water pipe wall (10),
The water pipe group (20) arranged between (10) is provided.

The water pipe wall (10) is formed by arranging substantially straight tubular water pipes (11) in one row at equal intervals. By connecting the water pipes with each other by fin-shaped members (12), (11) With the space between them closed, in the illustrated embodiment, they are arranged on both sides of the can body so that they are substantially parallel to each other.

The water pipe group (20) includes straight water pipes (21) arranged in two rows at equal intervals, and the water pipes (21) of the water pipe group (20).
Of the two (21a) on the top side of the row (upper side in FIG. 1),
(21a) defines the gap X between the water pipes as the water pipe (21).
The diameter of the water pipe (21a) is set to 1/2 or less, and the water pipe (21a) is provided on the surface of the two water pipes (21a) facing the combustion burner (B).
It has appropriate deposits along the longitudinal direction of a). In this embodiment, the attached matter is a large number of pin-shaped projections (30) as shown in FIG. 3, and is attached near both sides of the water pipe.

The combustion burner (B) is a general all primary air type surface combustion burner in which the air ratio is set to 1 or more, and is, for example, the fourth
As shown in the figure, a flame holding plate (2) having a large number of through holes (1) for jetting a premixed gas is used in a flat ceramic sintered body or the like. This combustion burner (B)
Between the ends of the water pipe walls (10) (10), the water pipes (21a), (21
In a state of being opposed to a), the gap Y between the surface of the combustion burner (B) and the water pipes (21a), (21a) is set to be twice the water pipe diameter d or less.

In the above configuration, the load required for the boiler is low,
When the combustion amount of the combustion burner (B) is small, the combustion flame is stably maintained by the combustion burner (B) itself as described above, and the boiler can body (A) is generated from the combustion flame and the combustion gas. The heat generates a predetermined amount of steam.

Next, when the load required for the boiler is high and the combustion amount of the combustion burner (B) is large, that is, the amount of premixed gas supplied to the combustion burner is large, and normally the combustion flame does not lift or blow off. The region where the stable combustion is impossible will be described.

In this state, the water pipes (21a), (21a) are sucked by the high-speed premixed airflow, and the water pipes (21a) themselves and each water pipe (21
Large and small eddies are generated on the wake side of the protrusion (30) attached to a) (see Fig. 5). In this swirl portion, the flow velocity of the premixed gas is appropriately decelerated, so in this region, that is, in the wake side of the water pipe (21a) and the protrusion (30), the flame is stably maintained and Since this combustion flame continuously ignites the other unburned premixed gas, all the premixed gas ejected from the combustion burner (B) is completely burned without fail.

In the above embodiment, the projection (30) attached to the water pipe (21a) was a pin-shaped one, but in the present invention, the projection is not limited to such a shape, and for example, as shown in FIG. It may be a plate-like protrusion (30 ') as shown, or a fin-like protrusion (30 ") as shown in FIG.
0 ') and (30 ") may be provided with windows and small protrusions of appropriate shapes. Further, these protrusions (30) and (3)
0 ′) and (30 ″) may be provided not only on both sides of the water pipe (21a) but also on the entire circumference. For example, as shown in FIG. The projection (30) may be formed by spirally winding around the entire circumference of 21a).

Further, in the above description, the deposits to be attached to the water pipe (21a) are the protrusions (30), (30 ') of various shapes, but in the present invention, the ones that physically stabilize the combustion are used. Not limited to this, a material that chemically stabilizes combustion, for example, a catalyst in which a catalyst such as Pt or Pd is attached to a carrier such as ceramic particles may be applied to the surface of the water pipe (preferably the back surface side to the burner). . In this case, the water pipe (21
a) In the wake, the vortex flow range is narrower than in the case where the above-mentioned projections (31), (30 '), etc. are attached, but the above catalyst promotes the combustion reaction and stabilizes flame holding. .

Furthermore, in the square multi-tube type once-through boiler according to the present invention, the deposit on the water pipe (21a) is not limited to either the protrusion or the catalyst, but may be the deposit of both.

[Effect of device]

As described above, according to the square multi-tube once-through boiler according to the present invention, the water pipe arranged immediately before the combustion burner has a high supply pressure of the premixed gas, and in the conventional combustion burner,
Even if the flame is lifted or blown off, the premixed gas ejected from the combustion burner is continuously ignited by the flame retained on the downstream side of the water pipe, because it is continuously ignited. Completely burns, and the flame formed in the wake of the water pipe is stably held by the water pipe and the deposits on the water pipe, so the combustion state is extremely stable. .

Therefore, according to the present invention, it is possible to expand the combustion load range in which any combustion burner can stably burn, and the entire boiler can expand the adjustment range of the steam generation amount corresponding to the load.

That is, according to the present invention, in various premixing burners, the combustion load can be increased and the efficiency of the boiler itself can be increased, so that it is extremely versatile, and if the boiler itself has the same capacity, It can be small.

[Brief description of drawings]

1 to 4 show an embodiment of a rectangular multi-tube type once-through boiler according to the present invention, and FIG. 1 is a schematic plan view showing an arrangement state of a water pipe and a combustion burner. 2 is an enlarged view of a main part of FIG. 1, FIG. 3 is an enlarged perspective view of a water pipe, FIG. 4 is a perspective view showing an example of a combustion burner, and FIG. 5 is for explaining a flame holding state of combustion flame. It is a principal part enlarged plan view of FIG. 6 to 8 show another embodiment of the present invention, each of which is an enlarged view of a main part showing an example of the deposit on the water pipe. (A) ...... Can body (B) ...... Combustion burner (10) ...... Water tube wall (11), (21), (21a) ...... Water tube (20) ...... Water tube group (30), (30 ' ), (30 ″), (30) .....

Claims (2)

[Scope of utility model registration request] 1. An all-primary-air premixing system in which a plurality of water pipes are arranged in parallel in a substantially rectangular compartment and the air ratio of the air-fuel mixture is set to 1 or more on one side of the compartment. A multi-tube once-through boiler of a type in which a combustion burner is arranged and a combustion gas is circulated to the water pipe in an intersecting direction, which is located immediately before the combustion burner (B) and the combustion burner (B). The gap Y between at least two water pipes (21a) is set to not more than twice the diameter d of the water pipe (21a), and the water pipe (2
Water pipe (21a) between the gaps X of adjacent
Square type multi-tube once-through boiler, characterized in that the diameter is set to 1/2 or less. 2. The water pipe (21a) has deposits (30), (31 ') on the surface for maintaining or promoting a combustion reaction.
A square multi-tube once-through boiler according to claim 1, characterized in that