JPS6222747Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas burner, and more particularly to a gas burner in which air is sequentially mixed in from the periphery of a fuel gas stream ejected from the center for combustion.

A typical prior art technique will be described with reference to FIG. In this gas burner 1, fuel gas is ejected from an ejection pipe 3 in the center as shown by arrow 2. On the other hand, combustion air is supplied to an annular flow path 8 between the outer cylinder 6 and the inner cylinder 7 as shown by arrows 4 and 5. A part of this combustion air flows as primary air as shown by arrow 9, another part flows as secondary air as shown by arrow 10, and the remaining air flows as shown by arrow 9.
It circulates as secondary air as shown by arrow 11.

When such a gas burner 1 is used in a combustion device with a relatively small combustion chamber cross-sectional area, such as a smoke-tube boiler or an immersion tube heating furnace, it tends to produce a long flame, and may also cause incomplete combustion, oscillating combustion, and carbon adhesion. Poor combustion is likely to occur. This phenomenon is particularly noticeable during low load combustion. . That is, during low-load combustion, both the fuel gas supply amount and the air supply amount are generally throttled, so the pressure decreases and the fuel gas and air are not mixed sufficiently, resulting in the aforementioned combustion failure. Therefore, the turndown ratio cannot be increased, and the air-fuel ratio during low-load combustion must be increased, resulting in a decrease in efficiency.

The purpose of the present invention is to solve the above-mentioned technical problems and provide a gas burner with a simple structure that can increase the turndown ratio and perform low-load combustion at a relatively low air-fuel ratio. shall be.

The present invention includes an outer cylinder 36 whose one end is closed by a closing plate 43 and whose other end has an opening 38 that becomes smaller in diameter axially outward, and which is arranged concentrically within the outer cylinder 36. , and both ends of the inner cylinder 37 are open, and one end of the inner cylinder 37 is
The other end of the inner cylinder 37 is located near the large diameter end of the opening 33, and is located inward (left side in FIG. 3) from the one end of the outer cylinder 36 in the axial direction. and an annular air flow path 39 formed between the inner cylinder 37 and the outer cylinder 36 near the center of the inner cylinder 37 in the axial direction.
Combustion air is supplied to the air flow path 39 through the first flow control valve 31, and the inner cylinder 37 is provided with the above-mentioned position of the inner cylinder 37 than the positions 40 and 41 to which the combustion air is supplied. One end (third
A plurality of communication holes 42 are formed at intervals in the circumferential direction on the right side of the figure, and a fuel injection pipe 44 extends concentrically through the closing plate 43 to near the one end of the inner cylinder 37; Inside the inner cylinder 37, a plurality of holes 46 are formed in a hollow truncated conical shape expanding inwardly toward the inside of the inner cylinder 37, closer to the one end of the inner cylinder than the communication hole 42. , a dispersion plate 45 fixed to the fuel jet pipe 44, and an air jet pipe 5 concentrically inserted through the fuel jet pipe 44.
2, between the fuel jet pipe 44 and the air jet pipe 52,
Fuel gas is supplied through the second flow rate control valve 26 , and at the tip of the fuel jet pipe 44 , the fuel gas is supplied through the second flow control valve 26 .
The passage between the air jet pipe 52 and the air jet pipe 52 is closed, and the distal end of the fuel jet pipe 44 is located in front of the position where the fuel jet pipe 44 of the dispersion plate 45 is fixed (third
A plurality of fuel injection holes 48 are formed at intervals in the circumferential direction (on the left side of the figure), and a hole 5 facing forward is formed at the tip of the air injection pipe 52.
1 and 57 are formed, combustion air is supplied to the air jet pipe 52 via a bypass pipe 22 branched from the upstream side of the first flow control valve 31, and the first and second flow control valves 31, 26 is a gas burner characterized by being interlocked.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a system diagram of an embodiment of the present invention,
The fuel gas line is shown as a solid line, and the air line is shown as a two-dot chain line. The gas burner 15 is used, for example, in a smoke tube boiler or an immersion tube heating furnace.
The gas burner 15 has a fuel supply source 1 such as city gas.
Fuel gas is supplied from 6 through a fuel supply pipe 17. Further, fuel gas is supplied to the pilot burner 18 via a pilot fuel supply pipe 19 branched from the fuel supply pipe 17. Forced blower 20
Combustion air is supplied to the gas burner 15 through an air supply pipe 21. A small amount of combustion air is also supplied to the gas burner 15 via a bypass pipe 22 branched from the air supply pipe 21 .

The fuel supply pipe 17 includes, in order from the upstream side to the downstream side, a main valve 23, a shutoff valve 24, and an orifice 25.
Flow meter using flow control valve 26 and cutoff valve 2
7 is provided. The pilot fuel supply pipe 19 is branched from the fuel supply pipe 17 between the main valve 23 and the cutoff valve 24.
A pilot valve 28 and pilot shutoff valves 29 and 30 are provided in this order from the upstream side. A flow rate control valve 31 is provided in the middle of the air supply pipe 21, and this flow rate control valve 31 responds to a flow rate control valve 26 that controls the fuel gas flow rate. Bypass pipe 22
is branched from the air supply pipe 21 on the upstream side of the flow control valve 31, and a flow control valve B32 is provided in the middle of the bypass pipe 22.

FIG. 3 is an enlarged sectional view of the gas burner 15 of FIG. 2. The main body 35 of the gas burner 15 is constructed by concentrically arranging an inner cylinder 37 with open ends inside an outer cylinder 36 with one end closed. The opening 38 of the outer cylinder 36 is formed in the shape of a hollow truncated cone whose diameter becomes smaller toward the left in FIG. 3 in the axial direction. . One end of the inner cylinder 37 is arranged inwardly with an interval in the axial direction from one end of the outer cylinder 36, and the other end of the inner cylinder 37 is arranged near the large diameter end of the opening 38. An annular air passage 39 is formed between the outer cylinder 36 and the inner cylinder 37, and connecting pipes 40 and 41 communicating with the air passage 39 are provided in the middle of the outer cylinder 36.
Branch pipes 21a and 21b of the air supply pipe 21 are connected to these connecting pipes 40 and 41, respectively. Also, in the middle of the inner cylinder 37, the inside of the inner cylinder 37 and the air flow path 3
A plurality of communication holes 42 are provided at intervals in the circumferential direction.

A fuel injection pipe 44 is provided at one end of the main body 35 (the right end in FIG. 3), passing concentrically through a closing plate 43 at one end of the outer cylinder 36 to near one end of the inner cylinder 37.
is invaded. The fuel supply pipe 17 is connected to this fuel injection pipe 44 . A dispersion plate 45 that expands inwardly into the inner cylinder 37 in the shape of a hollow truncated cone is fixed to the tip of the fuel injection pipe 44 .
A plurality of holes 46 are bored in the hole 5 in a scattered manner.

A cylindrical body 47 is inserted into the distal end of the fuel ejection pipe 44 , the distal end of the cylindrical body 47 is closed, and the cylindrical body 47 projects from the distal end of the fuel ejection pipe 44 . A plurality of fuel injection holes 48 are formed at intervals in the circumferential direction on the side wall of the cylindrical body 47 at the protruding portion. Also, the cylinder body 4
A hole 57 is concentrically drilled in the closed end portion of 7.
Furthermore, a short tube 49 is concentrically connected to the tip of the cylindrical body 47, and the tip of the short tube 49 is closed with an end plate 50 having an air jet hole 51. An air jet pipe 52 is inserted into the cylindrical body 47, and this air jet pipe 5
One end of 2 is communicated with the hole 57. The other end of the air jet pipe 52 extends outwardly through the side wall of the fuel jet pipe 44 in an airtight manner, and is connected to the bypass pipe 22 .

In such a gas burner 15, fuel gas is ejected from the fuel injection holes 48 toward the dispersion plate 45 as shown by a solid arrow 53. On the other hand, part of the air supplied to the air flow path 39 is transferred to the holes 4 of the distribution plate 45.
6, the air flows as primary air as shown by the double-dashed line arrow 54, and some of the other air flows as secondary air from the communication hole 42 as shown by the double-dashed line arrow 55. As shown by a dotted chain arrow 56, the air flows as tertiary air toward the open end of the gas burner 15. Furthermore, a small amount of air that has passed through the bypass pipe 22 is sent from the air outlet 51 to the point indicated by the two-dot chain arrow 5.
It is distributed as shown in 7. That is, the fuel gas ejected radially outward from the fuel nozzle 48 is mixed with primary air supplied toward the center and burned, and is then combusted with secondary and tertiary air supplied sequentially from the periphery. It mixes well with air and burns well.

Here, assume that low-load combustion is performed. During this low-load combustion, the flow rate control valves 26 and 31 work to reduce the supply amount of both fuel gas and air. However, since the bypass pipe 22 is branched from the upstream side of the flow control valve 31, the air flowing through the bypass pipe 22 is jetted out from the air jet hole 51 while maintaining a relatively high pressure state. Therefore, a relatively small amount of fuel gas and a relatively small amount of air can be sufficiently mixed to obtain a good combustion state. Therefore, as shown by the solid line in FIG. 4, even when the combustion amount is low, a good combustion state is achieved at a relatively low air-fuel ratio, and a decrease in thermal efficiency is prevented. In addition, in FIG. 4, the air-fuel ratio of the conventional gas burner is shown by a broken line.

The pressure loss of the air in the bypass pipe 22 needs to be selected to a value that can ensure the necessary amount of air during low load combustion. Further, the amount of air flowing through the bypass pipe 22 during low-load combustion is controlled by a flow rate control valve 32.

Note that the amount of air ejected from the air ejection holes 51 corresponds to the difference between the furnace internal pressure and the supply pressure in the bypass pipe 22, so the amount of air decreases during high-load combustion. However, during high-load combustion, as described above, the fuel gas and air are sufficiently mixed, so there is no effect on the combustion state.

In this way, low-load combustion can be achieved with a relatively low air-fuel ratio, so the present gas burner 15
According to this method, it is possible to obtain a large turndown ratio. That is, while the conventional gas burner 1 shown in FIG. 1 had a turndown ratio of about 5:1, the turndown ratio of the present gas burner 15 was about 10:1.

As described above, according to the present invention, since air is ejected into the center of the fuel gas jet flow, combustion can be performed at a relatively low air-fuel ratio even during low-load combustion, improving thermal efficiency and ,
It becomes possible to set a large turndown ratio.

Particularly, according to the present invention, the dispersion plate 45 expands in the shape of a hollow truncated cone within the inner cylinder 37.
Since a plurality of holes 46 are formed in a scattered manner,
A portion of the air supplied to the air flow path 39 flows through its holes 4.
6 flows as primary air as shown by the arrow 54 in FIG.
2 as secondary air as shown by arrow 55, and the remaining air flows as tertiary air towards the open end of gas burner 15 as shown by arrow 56. Further, a small amount of air flowing through the bypass pipe 22 is blown out from the air jetting pipe 52. Good combustion conditions are thus achieved.

Furthermore, according to the present invention, both the supply amounts of fuel gas and air are changed by the functions of the first and second flow control valves 26 and 31. Even if the supply amounts of the first and second flow control valves 26 and 31 are reduced during low-load combustion, the bypass pipe 22
Since it branches from the upstream side of the first flow control valve 31, air is supplied to the air jet pipe 52 while maintaining a relatively high pressure state in the bypass pipe 22. In this way, a good combustion state can be obtained during low-load combustion, and even when the combustion amount is low, a good combustion state can be achieved at a relatively low air-fuel ratio, and a decrease in thermal efficiency can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a gas burner 1 of the prior art, Fig. 2 is a system diagram of an embodiment of the present invention, Fig. 3 is a sectional view of the gas burner 15 of Fig. 2, and Fig. 4 shows the air-fuel ratio. It is a graph. 15... Gas burner, 21... Air supply pipe, 2
2... Bypass pipe, 31... Flow rate control valve, 48...
...Fuel injection hole, 51...Air injection hole, 52...Air injection pipe.

Claims (1)

[Claims for Utility Model Registration] One end is closed by a closing plate 43, and the other end has an opening 38 that becomes smaller in diameter outward in the axial direction.
an outer cylinder 36 having an outer cylinder 36; an inner cylinder 37 disposed concentrically within the outer cylinder 36 and having both ends open; one end of the inner cylinder 37 has a
The other end of the inner cylinder 37 is located inward from the one end of the outer cylinder 36 at an interval in the axial direction.
The inner cylinder 37 is located near the large diameter end of the inner cylinder 37 and has an annular air passage 39 formed between the outer cylinder 36 and the inner cylinder 37, and is located approximately at the center of the inner cylinder 37 in the axial direction. Outer cylinder 36
Combustion air is supplied to the air flow path 39 through the first flow control valve 31, and the inner cylinder 37 is provided with the above-mentioned position of the inner cylinder 37 than the positions 40 and 41 to which the combustion air is supplied. A plurality of communication holes 42 are formed near one end at intervals in the circumferential direction, and a fuel injection pipe 44 extends concentrically through the closing plate 43 to near the one end of the inner cylinder 37; 37, a hollow truncated conical shape expands inwardly of the inner cylinder 37 closer to the one end of the inner cylinder than the communication hole 42, and a plurality of holes 46 are formed in a scattered manner, and a plurality of holes 46 are formed in a dotted manner. A dispersion plate 45 fixed to the jet pipe 44, and an air jet pipe 5 concentrically inserted through the fuel jet pipe 44.
2, between the fuel jet pipe 44 and the air jet pipe 52,
Fuel gas is supplied through the second flow control valve 26 , and at the tip of the fuel jet pipe 44 , the fuel gas is supplied through the second flow control valve 26 .
The passage between the air jet pipe 52 and the air jet pipe 52 is closed, and the distal end of the fuel jet pipe 44 has a plurality of holes arranged at intervals in the circumferential direction ahead of the position where the fuel jet pipe 44 of the dispersion plate 45 is fixed. A fuel injection hole 48 is formed at the tip of the air injection pipe 52, and a hole 5 facing forward is formed at the tip of the air injection pipe 52.
1 and 57 are formed, combustion air is supplied to the air jet pipe 52 via a bypass pipe 22 branched from the upstream side of the first flow control valve 31, and the first and second flow control valves 31, 26 is a gas burner characterized by being interlocked.