JPH0526403A - Multi-tube type once-through boiler - Google Patents

Abstract

PURPOSE:To provide a low NOX and a low CO in a multi-tube type once-through boiler using a gasification combustion burner by a method wherein the burner and a boiler structure are combined to each other. CONSTITUTION:A plurality of water tubes 110 are arranged substantially in parallel to each other in a vertical row just before a gasification combustion burner B with a desired spacing being left thereat, a spacing of each of the water tubes is set to be substantially equal to a diameter of each of the water tubes 110 or less and combustion gas is flowed in a crossing direction in respect to a group of water tubes 110. A blower 102 and a burner duct 103 are disposed at optional segments on S1, S2 for defined a width of a boiler body A. In addition, the gasification combustion burner B is of a type in which a part of combustion gas is recirculated, a type in which a secondary air is partially mixed, or a type in which a part of the combustion gas is recirculated and at the same time the secondary air is fed. Since a flame of the gasification combustion can be guided into the spacings of the group of water tubes to perform an effective combustion, an independent wide combustion chamber can be eliminated, a temperature of combustion flame and a temperature of gas are controlled with the group of water tubes and occurrence of toxic combustion exhaust materials is restricted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-tube once-through boiler equipped with a can body of a type in which combustion gas is allowed to flow in a crosswise direction along a water pipe group arranged in cascade.

[0002]

2. Description of the Related Art In general, in a can body structure of a small multi-tube type once-through boiler, it is desirable to arrange a water pipe in an annular shape and use the inside thereof as a combustion chamber in order to improve heat exchange efficiency with combustion gas. It is considered.

Therefore, a multi-tube once-through boiler using a can body of this type has a structure in which auxiliary equipment such as a blower, a water supply pump, and a economizer is attached to a substantially cylindrical boiler body.

[0004]

By the way, in the boiler using the can structure as described above, each auxiliary device is arranged around the boiler main body because of structural restrictions, so that the boiler installation area is , It requires several times more than the boiler can. In addition, since a certain amount of space is required around the boiler for maintenance and inspection, a very large space is required when installing a plurality of boilers.

As described above, since the cylindrical can body structure tends to occupy a relatively large space depending on the installation location and arrangement state of the boiler, in recent years, various so-called rectangular can body structures are used as a base. A multi-tube once-through boiler has been proposed.

However, in this type of rectangular multi-tube once-through boiler, the water pipe arrangement of the conventional can body is simply elliptical or rectangular, and has a structure in which a relatively wide space is held as a combustion chamber. Therefore, there is a limit to miniaturization of the can body, and it is difficult to save space in the boiler as a whole.

In recent years, due to environmental pollution problems and the like,
Even in boilers, further reduction of harmful combustion exhausts, especially Nox and CO, is required. As a measure for reducing this kind of harmful combustion exhaust gas, in addition to the method of recirculating exhaust gas, a method of injecting water into the premixed gas, or after adjusting the combustion gas temperature by the cold body near the burner, Although there is a method that employs a method of oxidizing CO in an adiabatic space up to the heat exchanger, only applying these reduction measures to a conventional boiler can will increase the size and complexity of the boiler. Beckoning
The cost also rises.

[0008]

The present invention is to create a boiler unit including a novel can body that overcomes the above-mentioned problems, in which a plurality of water pipes are arranged substantially in parallel in a column.
A multi-tube through-flow boiler of the type in which combustion gas is circulated in the cross direction along these water pipe rows, and a vaporized combustion burner and a desired distance immediately before the vaporized combustion burner are provided,
The first row of water pipes is arranged, and the gap between this and the other rear row water pipes and the gap between the left and right water pipes are set to be substantially equal to or smaller than the diameter of the water pipes, and these water pipe rows are set to the combustion gas It is characterized in that it is provided with a can body arranged in the flow direction, and a blower and a burner duct provided in an arbitrary section on a side wall portion defining the width of the can body.

[0009]

In the multi-tube once-through boiler according to the present invention, the air supply path from the blower to the can body and the exhaust gas flow path from the can body to the flue are substantially provided along the flow path of the combustion gas in the can body. By forming it in the same plane, the installation area can be suppressed to an extremely small range of approximately the same width as the boiler can body,
Moreover, since the flame (blue flame) of the vaporizing combustion burner can be guided to the gap between the water tube groups and effectively burned in this gap space, an independent and wide combustion chamber is not required. Further, since the temperature of the combustion flame and the combustion gas are controlled by the water pipe, there is an advantage that the generation of harmful combustion exhaust substances can be suppressed.

[0010]

1 to 6 show an embodiment of a multi-tube once-through boiler according to the present invention. In the drawing, (10
(0) is the boiler main body in which the can (A) is surrounded by the casing (101), (B) is the vaporization combustion burner attached to the can (A), and (10
2) is a blower, (103) is a vaporization combustion burner (B) and blower
(102) is connected to the burner duct, (105) is a economizer, and (S
1), (S2), (S3), and (S4) indicate outer plates or side wall portions that define the width of the can body (A).

The can body (A) is a vertically elongated rectangular can body as shown in which a plurality of water pipes (110) are arranged in parallel in a substantially parallel manner. The water pipe group is adapted to flow in a crossing direction. In the illustrated example of the can body, the water pipes (110) located on both outer sides are adjacent to each other by fin-shaped members (111).
On both sides of (A), water tube walls (112) that are substantially parallel to each other are formed.

The intermediate water pipe (110) sandwiched between the water pipe walls (112), (112) on both sides is one of two pipes in the width direction of the can body (A).
The rows are arranged in the longitudinal direction (column direction) of the water pipe wall over a large number of rows. This water pipe array (a), (b), (c) ...
The water pipe (110) forming the water pipe wall (112) and the water pipe (110) are arranged in a staggered pattern with different longitudinal arrangement pitches of the can body (A).

In the above embodiment, the gap between the water pipes (110) is set to be substantially equal to or smaller than the diameter d of the water pipes (110). That is, the water pipe (110) in the water pipe wall (112)
Gap between comrades, water pipes in each water pipe row (a), (b), (c)… (11
0) The gap between each other, the gap between the rows of water pipes (a), (b), (c), and the water pipes (110) and the water pipes (a) of the water pipe walls (112) on the left and right sides. ), (B), (c) ... The adjacent water pipes (110) are set so that the gap between them is substantially equal to or smaller than the diameter d of the water pipe (110). In addition, even if all these gaps are the same,
They may be different from each other as long as they are within the above conditions.

Further, the water pipe (110) has upper and lower headers (115), (11) which respectively have upper and lower ends thereof.
6) to form a substantially rectangular can body (A) with a narrow ridge, and by covering it with a casing (101) through a predetermined heat insulating material, the rectangular thin shape shown in the figure is formed. The boiler body (100) is obtained.

The vaporization combustion burner (B) is a vaporization combustion burner of the type in which a part of combustion gas is recirculated,
It is used by attaching it to one end side in the longitudinal direction of (A). In this vaporization combustion burner (B), for example, as shown in FIG. 6, the combustion inner cylinder (10), the flame holding outer cylinder (20), and the fuel spray nozzle (30) are arranged on substantially the same axis. The fuel spray nozzle (30) is a combustion inner cylinder (10) in which a flame holding outer cylinder (20) is fitted.
It is located on the base end side (upstream side).

The combustion inner cylinder (10) is provided with the fuel spray nozzle (3
It is formed by a small-diameter cylinder part (11) on the side opposite to (0) (base end side), and a connecting part (12) and a large-diameter cylinder part (13) connected to this small-diameter cylinder part (11). The peripheral wall portion of the portion (11) is provided with a required number of openings (14 in the illustrated embodiment) (six openings in the illustrated embodiment) having an appropriate shape (generally circular in the illustrated embodiment). Connecting part (1
As described later, 2) has an appropriate inclination (or step) so that a vortex flow is generated along the inner surface of this portion.

The flame holding outer cylinder (20) is arranged so as to cover the periphery of the combustion inner cylinder (10). The base end of the inner cylinder (10) is fixed in contact with the partition member (1) so that the upstream side of the annular space existing between the ends can be sealed.

The difference in outer diameter (D3 -D1) between the flame-holding outer cylinder (20) and the large-diameter cylinder portion (13) of the combustion inner cylinder (10) is the large-diameter cylinder portion of the combustion inner cylinder. Outer diameter difference (D1-D2) between (13) and small diameter cylinder (11)
) Equal to or less than. At the tip of such a flame holding outer cylinder (20), the large diameter cylinder (1
A bent part (21) bent in the central direction is formed so as to cover the tip of (3), and between the tip of this bent part (21) and the tip of the large-diameter tubular part (13). A circulation gap (29) having a predetermined distance is provided.

Thus, the combustion inner cylinder (10) and the flame holding outer cylinder
The space between (20) and the opening (14) and the flow gap (2
9) communicates with the combustion inner cylinder (10), and functions as a circulation path (P) from the front end portion to the base end portion of the combustion inner cylinder (10).

The fuel spray nozzle (30) is located at a position facing the air introduction hole (2) formed in the partition wall member (1), and from this position toward the inside of the combustion inner cylinder (10), kerosene or light oil. , A fuel oil such as heavy oil is sprayed at a predetermined spray angle. that time,
The air introduction hole (2) formed in the partition member (1) serves as the only air supply hole to the combustion inner cylinder (10), but its inner diameter is
In the illustrated embodiment, the diameter is the same as that of the combustion inner cylinder (10).

The gap between the vaporization combustion burner (B) and the first water pipe array (a) located immediately before it is equal to a predetermined distance, for example, approximately three times the diameter d of the water pipe (110), or The water tube row is set to be less than that, and the water tube row that is closest to the vaporizing combustion burner (B) among the water tube rows of the water tube wall is also set based on the above-described predetermined distance.

The blower (102) is of a centrifugal type and is arranged on the side wall portion (S1) at the upper part of the boiler body (100). The blower outlet (102a) of this type of blower (102) is formed downward on the vaporization combustion burner (B) mounting side of the boiler body (100), and the blowout outlet (102a) and the vaporization combustion burner (B) are formed. And are connected by the above-mentioned burner duct (103) arranged on the wall side portion (S2).

The burner duct (103) has a width substantially equal to or smaller than that of the can body (A). For example, the burner duct (103) has a square tubular shape as shown in the drawing, and the vaporization combustion burner (B ) To supply the desired amount of combustion air.

On the other hand, as shown in FIGS. 1 to 4, the economizer (105) includes a fin-shaped heat transfer tube (120) extending horizontally in a substantially L-shaped economizer body (121). It is arranged in a grid pattern. Both ends of these finned heat transfer tubes (120)
Each of them is opened through the side surface of the economizer body (121). Of the openings that open on one side, the uppermost four and the lowermost four are connected by the headers (122a) and (122b) arranged on the side of the body (121), respectively, and The two rows of 8 are connected by the same header (122c). Further, the upper side 2 that opens to the other side
The eight openings of the step and the eight openings of the lower two steps are respectively the headers (122d), (122e) arranged on the side surface of the body (121).
Are in communication with each other. Therefore, the heat transfer tube with fins (120) and the headers (122a) to (122e) easily form a vertically meandering flow path in the economizer (105). In and out of water of the header (122a),
It is performed from the water inlet pipe (123) and the water outlet pipe (124) arranged in (122b). The economizer (105) of this configuration is used for the boiler body (A).
The can body (A) so that it intersects with the water pipe (110) of
It is arranged on the side opposite to the vaporization combustion burner (B) via the through hole, and its width is also substantially equal to the width of the can body (A).

In the above structure, the combustion air flows in the vertical direction from the blower (102) through the burner duct (103) and is supplied to the vaporization combustion burner (B).
It flows into the combustion inner cylinder (10) from the air introduction hole (2) of (B). Simultaneously with or slightly sending it, the liquid fuel from the fuel spray mist nozzle (30) is sprayed, and the mixture of the combustion air and the liquid fuel is ignited by the ignition spark rod (51). , Combustion of liquid fuel droplets begins. This combustion flame moves toward the tip portion of the combustion inner cylinder (10) while increasing the temperature, and is ejected from the tip portion of the combustion inner cylinder (10).

The pressure before and after the opening (14) of the small diameter cylinder (11) at that time is from the air introduction hole (2) to the combustion inner cylinder (10).
Due to the air flow supplied to the combustion inner cylinder (10), the inner circumference side is lower and the combustion inner cylinder (10) outer circumference side is higher.
For this reason, the above-mentioned combustion gas flows from the combustion inner cylinder (1) through the gap (29) between the tip of the combustion inner cylinder (10) and the tip of the flame holding outer cylinder (20).
After passing through the space formed between the flame retardant outer cylinder (20) and the flame holding outer cylinder (20), the gas flows again from the opening (14) of the small diameter cylinder (11) to the upstream of the combustion cylinder (10). Here, the combustion inner cylinder (10) and the flame holding outer cylinder (2
The space formed between (0) and (0) functions as the circulation path (P) of the combustion gas as described above, and the combustion gas that has flowed back into the combustion cylinder section (10) is the fuel spray nozzle (30). The liquid fuel from (1) is heated to vaporize the particles, and the combustion is transferred to the blue flame (vaporized combustion) in the combustion inner cylinder (10). Aperture
At the same time, the combustion gas from (14) also has the effect of lowering the temperature of the combustion gas, thereby suppressing the generation of thermal NOx.

In this way, the liquid fuel sprayed in the combustion inner cylinder (10) shifts to the blue flame state and enters the steady combustion state. In this state, the vaporization of the liquid fuel is as described above. Not only by the recirculated combustion gas, but also by the heat radiation from the inner wall surface of the combustion inner cylinder (10). Also, in the process in which the combustion gas reaches the large-diameter cylindrical portion (13) from the small-diameter cylindrical portion (11) of the combustion inner cylinder (10), a vortex flow S1 generated inside the connecting portion (12)
Holds the connecting portion (12) at a relatively high temperature to further promote the vaporizing action, and further, the bent portion (2) provided on the flame holding outer cylinder (20).
The vortex flow S2 generated inside 1) helps hold the combustion flame of the combustion inner cylinder (10). Therefore, in this recirculation type vaporization combustion burner, it is possible to shorten the time until the vaporization combustion after the fuel is sprayed, and the flame holding property is improved.

Next, the combustion gas ejected from the vaporizing combustion burner (B) is completely burned in the space between the water pipes (110) of the can body (A) from left to right in the figure. It flows, and in this flowing process, combustion flame and combustion gas are
Heat transfer to (110). In this way, the combustion gas
When exiting the can body (A) and flowing into the economizer (105), the economizer (10
In the inside of 5), it flows upward, and further, heat exchange is performed with the heat transfer tube (120).

Here, the heat transfer tube (120) of the above economizer (105)
The water inside is from the four heat transfer tubes (120) at the top to the bottom four.
Towards the heat transfer tubes (120) of each of the headers (122d), (122c), (122
Since it is distributed via e), the uppermost heat transfer tube (120)
The water inside is relatively low, and it is possible to efficiently recover heat from the combustion gas whose temperature has decreased downstream of the economizer (105), and overall, heat recovery is extremely efficient. After that, the combustion gas is discharged from an exhaust stack (not shown).

At this time, since the gaps between the vaporization combustion burner (B) and the first water pipe array (a) and the water pipe wall (112) are set to be narrow as described above, the vaporization combustion burner (B) The flame of
The water tubes (110) in each of the water tube rows (a), (b), (c), etc. extend through the space between the water tubes (110) in the longitudinal direction of the can body, and a combustion reaction occurs in this space.

As a result, the flame from the vaporization combustion burner (B) is transferred from the first water pipe array (a) to the respective water pipe arrays (b), (c) ...
In addition, in contact with the water pipe wall, heat transfer is performed sequentially, and the flame temperature can be suppressed to a low level of, for example, 1200 ° C to 1300 ° C.
Also here, generation of thermal NOx can be suppressed. In addition, the combustion flame is connected to each water pipe (110) by this water pipe (1
Since it becomes a vortex in the gap of 10), the flame holding property is improved, and unburned gas is rapidly taken into the flame flow for complete combustion, and particularly CO is oxidized to CO2. Further, the combustion gas after the combustion reaction also passes through in the longitudinal direction of the can body while being in contact with each water pipe row and the water pipe wall, and is maintained in a relatively low temperature range. Therefore, thermal dissociation of CO2 into CO is suppressed.

Further, since the vaporizing combustion burner (B) is for rapidly vaporizing liquid fuel inside the burner,
The combustion flame formed toward the front of the vaporization combustion burner (B) completes combustion promptly by the time it exerts a heat transfer effect on the water tube and drops to a temperature range where combustion reactions do not occur. Burns completely without remaining.
Therefore, according to the above configuration, the flow paths of the combustion air and the combustion gas in this boiler are formed in the upright space of a predetermined width, and the width of the boiler as a whole is defined by the width in which the flow path can be formed. It is possible to reduce the length to 1, and it can be remarkably wider than the conventional multi-tube once-through boiler having a combustion chamber. In addition, since the burner (B) is arranged on one end surface of the can body (A), the burner (B) can be easily maintained, inspected, and replaced.

In addition, by adopting the can structure as described above, the flame from the vaporization combustion burner (B) and the flow path of the combustion gas can be set in a straight line and relatively long, and the combustion flame, In addition, the combustion gas can be retained in the can body at a relatively low temperature, and it is not necessary to form a separate combustion chamber. This leads to a reduction in harmful exhaust emissions due to the action of imparting a vortex to the flame while making the can compact. For example, when a conventional multi-tube once-through boiler and a multi-tube once-through boiler according to the present invention are examined for the amount of harmful exhaust gas produced with the same outer dimensions and combustion load, NOx is reduced from 70 to 80 ppm to 40 ppm. Regarding CO, the multi-tube type once-through boiler according to the present invention is as low as 50 ppm or less.

These NOx and CO values are equivalent to those of a boiler equipped with an exhaust gas circulation device with a circulation rate of 10%, but the boiler of the present invention does not circulate at all, and circulates combustion gas only in one direction. This type has the effect of reducing harmful exhaust substances, and does not require complicated piping for circulating exhaust gas, resulting in an extremely simple structure.

The multi-tube type once-through boiler according to the present invention is not limited to the can body having the above-mentioned structure, and is, for example, as shown in FIG.
~ The structure shown in Fig. 9 may be used.

That is, in FIG. 7, in the can body having the structure shown in FIG. 2, from the upstream side to the downstream side in the combustion gas flow direction, two or more water pipe groups having different heat transfer surface densities and the density Arranged in order from small to large, smooth water pipe (110) group, horizontal fin water pipe from upstream side to downstream side
The (110 ') group and the erofin water pipe (110'') group are arranged.

On the other hand, those shown in FIGS. 8 and 9 are the water pipe walls.
(112) is composed of three water pipes (110), and this water pipe wall (11
Two straight water pipes (110) from the vaporization combustion burner (B) side are arranged in series between 2) and (112), and the water pipe walls (112), (11)
One erotic fin water pipe (110 '') is arranged between the partition walls (118) connected to the downstream side of 2), and each water pipe (110), (11)
0 ″) and the positional relationship of the vaporization combustion burner (B) are the same as above. In this can body, the water pipe (113) is a water level control tube for detecting the water level in the can of the boiler and controlling the water supply.

Further, FIG. 10 shows another type of vaporization combustion burner applied in the present invention. This vaporized combustion burner (B) is of a type that partially mixes secondary air, and the secondary space is formed in the annular space (3) existing between the combustion inner cylinder (10) and the flame holding outer cylinder (20). It is used as an air introduction flow path. In this burner, the primary air supply hole is the air introduction hole (2) formed in the partition member (1), and the secondary air supply hole is the required number of holes formed in the partition member (1). It is an annular through hole (4).

In this vaporization combustion burner (B), primary air is directed from the air introduction hole (2) toward the combustion inner cylinder (10), and from the through hole (4) toward the annular space (3). While supplying secondary air respectively, liquid fuel is sprayed from the air introduction hole (2) toward the combustion inner cylinder (10) by the fuel spray nozzle (30),
It is ignited by the ignition spark rod (51). As a result, in the combustion inner cylinder (10), the primary combustion from the air introduction hole (2) starts the primary combustion (at this stage, the vaporization combustion by the blue flame has not been made).

The above primary combustion flame moves toward the tip portion of the combustion inner cylinder (10) while increasing the temperature. In this process, the primary combustion flame heats the combustion inner cylinder (10), particularly the large-diameter cylindrical portion (13), and at the same time, the combustion inner cylinder (10).
The unburned content of the liquid fuel contained in the primary combustion flame is inversely heated by the radiant heat from and is vaporized. At this time, a swirl S1 as shown in the drawing is generated inside the connecting part (12), and the swirling flow S1 keeps the connecting part (12) in a relatively high temperature state, further promoting the vaporization action.

The primary combustion flame is the inner cylinder for combustion as described above.
(10) When ejected from the tip, the secondary air from the gap (29) is taken in, and after that, secondary combustion in the blue flame state starts, but the secondary air from the gap (29) burns. It also has the effect of lowering the temperature of the gas, thereby suppressing the generation of thermal NOx.

In this way, the liquid fuel sprayed in the combustion inner cylinder (10) shifts to the blue flame state and becomes the steady combustion state. In this state, the vaporization of the liquid fuel is mainly The heat is radiated from the inner wall surface of the combustion inner cylinder (10). Further, in the process in which the combustion gas reaches the large-diameter cylindrical portion (13) from the small-diameter cylindrical portion (11) of the combustion inner cylinder (10), inside the connecting portion (12),
A vortex flow S1 as shown in the drawing is generated, and the vortex flow S1 keeps the connecting portion (12) in a relatively high temperature state and further promotes the vaporization action. Therefore, in this secondary air-mixing vaporization combustion burner, the time from vaporization of fuel to vaporization combustion can be shortened.

Further, FIG. 11 shows another type of vaporization combustion burner applied in the present invention. This vaporization combustion burner (B) is a type that recirculates a part of combustion gas and introduces secondary air.
The space between the inner cylinder (20) and the outer cylinder (70) serves as a secondary air supply path.

The combustion action of this vaporization combustion burner is as follows.
In the same manner as described above, primary air is supplied from the air introduction hole (2) toward the combustion inner cylinder (10), and secondary air is supplied from the through hole (4) into the annular space (3). , Fuel spray nozzle
Liquid fuel is sprayed from the air introduction hole (2) toward the combustion inner cylinder (10) by (30), and is ignited by the ignition spark rod (51). As a result, in the combustion inner cylinder (10), primary combustion is started by the primary air from the air introduction hole (2),
This primary combustion flame raises the temperature while
Move toward the tip of 0). In this process, the primary combustion flame heats the combustion inner cylinder (10), especially the large-diameter cylinder portion (13), and at the same time, is included in the primary combustion flame by the radiant heat from the combustion inner cylinder (10). The unburned portion of the liquid fuel is heated and vaporized in reverse.

The primary combustion flame is the combustion inner cylinder as described above.
(10) When ejected from the tip, the secondary air from the gap (29) is taken in, and after that, secondary combustion in the blue flame state starts, but the secondary air from the gap (29) burns. It also has the effect of lowering the temperature of the gas, thereby suppressing the generation of thermal NOx.

In the above combustion process, the pressure before and after the opening (14) of the small diameter cylinder (11) is burned by the air flow supplied from the air introduction hole (2) to the combustion inner cylinder (10). The inner peripheral side of the combustion inner cylinder (10) is lower, and the outer peripheral side of the combustion inner cylinder (10) is higher. Therefore, the combustion gas described above flows from the gap (29) between the tip of the combustion inner cylinder (10) and the tip of the flame holding middle cylinder (20) to the combustion inner cylinder (10) and the flame holding middle cylinder. It flows again through the space formed between (20) and the opening (14) of the small diameter cylinder (11) to the upstream of the combustion cylinder (10). The combustion gas that has flowed back into the combustion cylinder (10) heats the liquid fuel from the fuel spray nozzle (30) to vaporize its particles, and burns it in a blue flame (vaporization) in the combustion inner cylinder (10). Combustion). Opening (14)
The combustion gas from the same as the above-mentioned secondary air also has the effect of lowering the temperature of the combustion gas, and as a result, the thermal NO
Suppress x generation.

In this way, the liquid fuel sprayed in the combustion inner cylinder (10) shifts to the blue flame state and becomes the steady combustion state. In this state, the vaporization of the liquid fuel is as described above. Not only by the recirculated combustion gas, but also by the heat radiation from the inner wall surface of the combustion inner cylinder (10). Further, in the process in which the combustion gas reaches the large diameter cylinder portion (13) from the small diameter cylinder portion (11) of the combustion inner cylinder (10), a vortex flow S1 as shown in the figure is generated inside the connecting portion (12). And this vortex flow S1 connects
(12) is kept at a relatively high temperature, and the vaporizing action is further promoted. Therefore, in this secondary air-mixing vaporization combustion burner, the time from vaporization of fuel to vaporization combustion can be shortened. Further, in this steady combustion state, a swirl S2 is generated inside the bent portion (21) provided in the flame holding middle cylinder (20) as shown in the figure, and this swirl S2 is
Helps maintain the flame of the combustion flame of the inner combustion tube (10).

Further, FIG. 12 shows another embodiment of the two-stage combustion type vaporization combustion burner according to the present invention showing another type of the vaporization combustion burner shown in FIG. The (73) is provided in a cross-shaped air conduit (74) attached to the inner peripheral surface of the outer cylinder (70) instead of the inner peripheral surface of the front end closing portion (72). That is, the secondary air ejection hole (73), an air conduit (74) in which each base end is communicated with the annular space (3).
A predetermined number of them are formed on an appropriate portion of the surface (the entire surface in the illustrated embodiment), and are uniformly supplied to the entire primary combustion flame from the flame holding inner cylinder (10). As described above, by uniformly supplying the secondary air into the primary combustion flame, the flame temperature can be uniformly adjusted to a desired value for the entire flame, so that the generation of thermal NOx can be more reliably reduced. You can

Further, in these vaporization combustion burners, a through hole (41) having an appropriate shape is formed in the tip portion of the combustion inner cylinder (10), that is, the inner peripheral portion of the large diameter cylinder portion (13) on the tip side. It is also possible to provide a flame dividing plate (40) having a number of holes. This flame dividing plate (40) is, for example, as shown in FIGS. 13 and 14, a circular disc having a diameter smaller than the inner diameter of the large-diameter tubular portion (13), and a large and small circular through hole.
(41) is bored, and is fixed to the large-diameter cylindrical portion (13) by a support piece (42) attached to an appropriate place on the periphery.

The flame dividing plate (40) is a combustion inner cylinder (10).
By dividing the flame from the tip into small flames for each through-hole (41), it is possible to obtain a short flame as a whole burner, so when the vaporizing combustion burner of the present invention is applied to a thermal device such as a boiler, etc. Further, it is possible to achieve further miniaturization of the furnace (combustion chamber) volume of the thermal equipment, and by extension, the thermal equipment itself. Moreover, as described above, by arranging the through holes (41) so that those having different diameters are adjacent to each other, the flame from the small diameter through holes (41) to the large diameter through holes (41) In addition to the heat radiation to the flames, the hot vortex formed between these flames improves the flame holding property as a whole. In addition, since the sizes of the flames are different from each other, the resonance frequency of the flames is dispersed, and the noise accompanying combustion is reduced.

FIG. 15 shows another example of the flame dividing plate shown in FIGS. 13 and 14, which is an annular through hole having different widths.
(43) is formed so as to form substantially concentric circles.
This example also has the same effects as those described above.

FIG. 16 shows still another modification of the vaporization combustion burner described above, in which the air introduction hole (2) formed in the partition member (1) is provided with an orifice member (60). The orifice (60) in this embodiment has a circular through hole (61) in the center.
By narrowing the air flow path to the combustion inner cylinder (10), a strong vortex is formed in the combustion inner cylinder (10), and the combustion introduced from the opening (14) The gas and the atomized liquid fuel are stirred to promote subsequent vaporization.

The orifice member (60) is not limited to the circular through hole (61) provided only at the center of the orifice member (60). For example, as shown in FIG. 17, the circular through hole (6) is formed at the center.
In addition to forming 2), a plurality of fan-shaped through holes (63) may be formed around the through hole (62).

Further, in those vaporization combustion burners, by coating the flame dividing plate (40) with a metal catalyst such as Pt, Pd, Cu, etc., the combustion reaction is promoted and flame holding property is improved. It is possible to further raise the NOx and further reduce NOx by catalytically decomposing NOx.

[0055]

As described above, in the multi-tube once-through boiler according to the present invention, the air supply path from the blower to the can body and the exhaust gas flow path from the can body to the flue are provided with the combustion gas in the can body. Can be formed in substantially the same plane along the flow path of, the combustion air-combustion gas flow path can be set in the upright space of a predetermined width, the overall width of the boiler , And the occupied space can be significantly reduced.

Further, the multi-tube once-through boiler according to the present invention has a reduced horizontal width as described above, and since each accessory is arranged in the longitudinal direction or above the boiler can body, it can be a flat vertical type. This merit should be remarkably exhibited in the boiler multi-can installation system which has been recently prized.

Further, the can body in the multi-tube type once-through boiler according to the present invention is constructed so that the temperature of the combustion flame and the combustion gas in the gap space of the water pipes is controlled to a relatively low temperature range by each water pipe, and the harmful combustion exhaust gas is discharged. Since the generation of substances can be suppressed, no special device or structure for controlling harmful exhaust substances is required as in the prior art, and the structure is simple and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing an air-combustion gas flow path in an embodiment of a multi-tube once-through boiler according to the present invention.

FIG. 2 is a plan view showing a water pipe arrangement example of a can body in the multi-tube once-through boiler according to the present invention.

FIG. 3 is a partial vertical sectional view of a economizer in a multi-tube once-through boiler according to the present invention.

FIG. 4 is a side view of the economizer in the multi-tube once-through boiler according to the present invention.

FIG. 5 is an overall perspective view of a multi-tube once-through boiler according to the present invention.

FIG. 6 is a side sectional view showing a vaporization combustion burner in a multi-tube once-through boiler according to the present invention.

FIG. 7 is a plan view showing another arrangement example of water tubes of the multi-tube once-through boiler according to the present invention.

FIG. 8 is a schematic side view showing still another example of the can body structure of the multi-tube once-through boiler according to the present invention.

FIG. 9 is a plan view showing another example of the can body structure in the multi-tube once-through boiler according to the present invention.

FIG. 10 is a side sectional view showing another embodiment of the vaporization combustion burner in the multi-tube once-through boiler according to the present invention.

FIG. 11 is a side sectional view showing still another embodiment of the vaporization combustion burner in the multi-tube type once-through boiler according to the present invention.

12 is a side sectional view showing a modified example of the vaporization combustion burner shown in FIG.

FIG. 13 is a side sectional view of an essential part showing another modification of the vaporization combustion burner shown in FIGS. 6 and 10 to 12;

FIG. 14 is a front view of a flame dividing plate in the vaporization combustion burner shown in FIG.

15 is a front view showing another example of the flame dividing plate in the vaporization combustion burner shown in FIG.

FIG. 16 is a side sectional view of a main part showing another modified example of the vaporization combustion burner shown in FIGS. 6 and 10 to 15;

17 is a front view showing another example of the orifice member in the vaporization combustion burner shown in FIG.

[Simple explanation of symbols]

(A) ...... Can body (B) …… Water pipe array (B) …… Water pipe array (C) …… Water pipe array (S1) …… Side wall (S2) …… Side wall (B) ...... Evaporative combustion burner (102) ...... Blower (103) ...... Burner duct (105) …… Coal saver (110) ...... Water tube (110 ') ...... Water tube (110``) ...... Water tube (120) ...... Heat transfer tube

Claims (4)

[Claims] 1. A multi-tube once-through boiler of a type in which a plurality of water pipes are arranged in parallel substantially in parallel and a combustion gas is circulated in a cross direction along these water pipe lines, the vaporization combustion burner (B ) And a desired distance immediately before the vaporization burner (B),
The first row of water pipes (a) is arranged, and this and other rear rows (b), (c) ...
The gap between the water pipe and the left and right water pipes is set to be substantially equal to or smaller than the water pipe diameter d: and the water pipe rows (b), (c), ... Are arranged in the flow direction of the combustion gas. The can body (A) having the structure, and the side wall portions (S1), (S2) defining the width of the can body (A). The blower (102) and the burner duct (1
03) A multi-tube once-through boiler characterized by being equipped with. 2. The vaporized combustion burner (B) according to claim 1.
Is a vaporized combustion burner (B) that recirculates a part of the combustion gas, which is a multi-tube once-through boiler. 3. The vaporized combustion burner (B) according to claim 1.
However, a vaporization combustion burner of the type that partially mixes secondary air
(B) is a multi-tube once-through boiler. 4. The vaporized combustion burner (B) according to claim 1.
Is a vaporized combustion burner (B) that recirculates a part of the combustion gas and introduces secondary air.