JP2000249333A - Burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burner having good combustion performance in an all load range and a wide load range. SOLUTION: The burner comprises an air case 2 connected to a blower 4 to receive air supply from the blower, an end open cylinder 6 disposed in the case 2, and a fuel injection nozzle 7 in such a manner that the cylinder 6 has at least a small-diameter portion 6a and a large-diameter portion 6b, the portion 6b receives a fuel injection from the nozzle 7, and openings 10 to 14 are further provided at the portions 6a, 6b to introduce the air from the case 2 into the cylinder through the openings. In this case, the case 2 has a first air chamber 21 connected to the portion 6a, and a second air chamber 22 connected to the portion 6b, and further a flow rate ratio altering means 35 for altering a ratio of the air flow rate to the chamber 21 to the air flow rate to the chamber 22 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner, and more particularly to a burner capable of increasing or decreasing the amount of combustion using a fluid fuel such as a liquid fuel.

[0002]

2. Description of the Related Art In a petroleum water heater or the like, a variable combustion type gun type burner in which liquid fuel is burned by a so-called two-stage combustion cylinder has been conventionally known. One example of such a conventional burner is shown in FIG. The burner is for heating a heat exchanger provided below the burner, and the airflow in the burner is substantially downward. Such a configuration is often used to provide a compact silencer (not shown) to save space. In this burner, fuel is pressurized by an electromagnetic pump 4 and injected from a fuel injection nozzle 7. The injected fuel is mixed with air from the blower 1, ignited by the spark plug 8, and burns mainly in the combustion cylinder 6. Combustion cylinder 6
As shown in FIG. 4 and FIG. 5, each is composed of a small-diameter portion (first inner cylinder) 6a and a large-diameter portion (second inner cylinder) 6b, both of which are cylindrical. The nozzle housing cylinder 3 having the fuel injection nozzle 7 and the ignition plug 8 therein is composed of a nozzle housing inner cylinder 3a directly housing the fuel injection nozzle 7 and a nozzle housing outer cylinder 3 provided outside thereof.
It has a double structure with b.

[0003] Specifically, the air from the blower 1 is sent to the air case 2 and then used for combustion as described below.
The air that has flowed into the nozzle housing inner cylinder 3a from the air hole 10 provided on the side surface of the nozzle housing inner cylinder 3a passes around the fuel injection nozzle 7, mixes with the injected fuel, and enters the combustion cylinder 6 Sent. A combustion reaction is started by the spark plug 8, and the air flowing from the air hole 10 first supplies oxygen to the fuel. Since the airflow is directed to the combustion tube 6, the combustion reaction is mainly performed inside the combustion tube 6. The air that has flowed into the nozzle housing outer cylinder 3b from the air hole 11 provided on the side surface of the nozzle housing outer cylinder 3b is
The upper surface of a is sent into the first inner cylinder 6a from the swirler 15 having the upper surface radially cut away to supply oxygen to the fuel while adding a flame holding effect to the gas in the combustion cylinder 6 by swirling. First
From the air hole 12 provided on the side surface of the inner cylinder 6a, the small-diameter portion 6a
The air that has flowed into the inside is used as so-called secondary air for combustion. Step 9 between small diameter portion 6a and large diameter portion 6b
The air that has flowed into the large diameter portion 6b from the air hole 13 provided in the combustion tube 6 is sent from the swirler 25, which is formed by radially notching the inner surface of the step portion 9, into the large diameter portion 6b. It supplies oxygen to the fuel while adding a flame holding effect by swirling to the gas inside. The air that has flowed into the large diameter portion 6b from the air holes 14 provided on the side surface of the large diameter portion 6b is also used for combustion as so-called secondary air. Further, air (so-called tertiary air) blown from the periphery of the cylinder 6 to the lower combustion case 60 without flowing into the combustion cylinder 6 has not yet been completely burned by the secondary air in the combustion gas. When a component is present, it contributes to the complete combustion of the unburned component.

The amount of air blown by the blower 1 is controlled according to the amount of fuel supplied by the electromagnetic pump 4 (ie, the amount of fuel injected by the fuel injection nozzle 7). When the load is small, that is, when the required heat amount is small and the input (fuel supply amount) is small, the blowing amount (air supply amount) is also reduced, and the combustion is performed inside the first inner cylinder 6a having a small diameter. Under heavy load,
That is, when the required heat amount is large and the input (fuel supply amount) is large, the blowing amount (air supply amount) is also increased, and the combustion is performed not only in the first inner cylinder 6a but also in the large-diameter second inner cylinder 6b. Since it is performed inside, it is expected that a good combustion state can be obtained from a small load range to a large load range. The control of the blowing amount is performed by controlling the rotation speed of the fan motor of the blower 1 by a method such as proportional control. In addition, since the ratio of the amount of air blown to the small diameter portion and the large diameter portion is determined by the ratio of the respective opening areas, the specific position of the opening,
The number, area, shape, etc. are empirically determined by experiments so that the combustion state is good.

[0005]

However, such a burner has the following problems. First,
Since the inflow air from the opening of the large diameter portion does not contribute to the combustion at a small load, if the ratio of the opening area of the small diameter portion is increased in order to use the air effectively, a good combustion range at the small load Can be obtained to the maximum, but when the air flow rate is increased under a large load, the flow velocity in the small diameter portion becomes excessive and the flame may blow out. Further, if the amount of air blown under a large load is suppressed to a low level to prevent blow-out, there is a risk that soot, NOx, CO, etc. may be generated due to an insufficient amount of air supplied to the large diameter portion. Conversely, if the ratio of the opening area of the large-diameter portion is increased, a good combustion range can be obtained to a maximum when the load is large, but when the load is small, the amount of air blown to the small-diameter portion becomes too small and the small Soot, NOx, CO
And so on. If the amount of air blown is increased even under a small load in order to prevent the generation of these products, the amount of air blown from the opening of the large-diameter portion that does not contribute to combustion becomes too large and wasteful.

That is, if the ratio of the opening area of the small diameter portion is increased, a problem tends to occur at the time of large load, and if the ratio of the opening area of the large diameter portion is increased, the problem tends to occur at the time of small load. For this reason, in the conventional burner, it is a reality that the opening area ratio that can somehow be compromised in performance in the load range from the minimum to the maximum is selected, and good combustion performance can be obtained in the entire load range. Did not. In addition, the practical load range is restricted, and it is difficult to widen the combustion amount control width (the ratio between the maximum output and the minimum output).

[0007] Japanese Patent Application No. 9-36771, which is a prior application of the present applicant.
In No. 30, the above problems were solved,
It has been proposed to provide a burner with a limiting member for limiting the amount of air introduced into the large diameter portion. However, merely providing the limiting member is equivalent to reducing the ratio of the opening area of the large-diameter portion, and the above problem could not be solved. The application also proposes that a flaky valve portion is provided to allow ventilation to the large-diameter portion only when a large amount of air is blown. However, although the burner having such a configuration has a simple structure and is inexpensive, precise control is difficult, and it is not possible to obtain an optimum combustion performance by obtaining an optimum air flow according to a load. . In addition, the same application proposes that a valve is provided by providing an opening in a restricting member having a shape that partitions an air case. However, it is merely described that a valve is provided, and a specific configuration for obtaining an optimum air flow rate according to the operating conditions is not disclosed at all. Not in.

The present invention has been made in view of the above-mentioned problems of the prior art,
It is an object of the present invention to provide a burner which has good combustion performance in a whole load range from a small load to a large load and has a wide load range (combustion amount control width).

[0009]

According to a first aspect of the present invention, there is provided a burner comprising: an air case connected to a blower for receiving air from the blower; and an open end disposed in the air case. And a fuel injection nozzle,
The cylindrical body has at least a small diameter portion and a large diameter portion, the small diameter portion receives fuel injection from the fuel injection nozzle, and the small diameter portion and the large diameter portion are provided with an opening, and the opening is provided. In a burner in which air is introduced from the air case into the interior of the cylinder via the air case, the air case includes a first air chamber connected to the small diameter portion, and a second air chamber connected to the large diameter portion. And a first air chamber and a second air chamber.
The burner is characterized by being provided with a flow rate ratio changing means for changing a ratio of an air flow rate blown into the air chamber.

With this burner, an optimum amount of combustion air can be supplied to each of the small-diameter portion and the large-diameter portion of the combustion cylinder according to the load condition, so that the combustion performance is good in the entire load range from a small load to a large load. And load range (combustion amount control width)
Becomes wider.

According to a second aspect of the present invention, there is provided a burner, wherein the flow ratio changing means opens the flow path of the air blown to the second air chamber in a stepwise manner in accordance with an increase in the fuel injection amount. The burner according to claim 1, further comprising an opening / closing means configured by a movable damper.

With this burner, it is possible to cope with an increase in the required amount of air in the large-diameter portion of the combustion cylinder as the fuel injection amount increases, and to achieve the object of the invention with a relatively simple and compact structure. it can.

According to a third aspect of the present invention, there is provided a burner having a plurality of flow paths for air blown into a second air chamber, wherein at least one of the plurality of air flow paths has the movable damper. 3. The burner according to claim 2, wherein at least one of the other is always open.

In this burner, the minimum necessary air is always supplied to the large diameter portion of the combustion cylinder regardless of the position of the movable damper.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a burner according to an embodiment of the present invention. The burner in FIG. 1 does not differ from the burner described in the prior art in the structure of the combustion cylinder 6 itself. The liquid fuel is sent to the fuel injection nozzle 7 by the electromagnetic pump 4. The fuel injection nozzle 7 is a return nozzle, which sprays a part of the supply liquid and returns surplus liquid to the suction side of the electromagnetic pump 4. The flow rate of the injected liquid fuel is variable and is controlled by a control valve (not shown). The amount of air blown by the blower 1 is also increased / decreased by a conventional control mechanism in response to an increase / decrease in the flow rate of the liquid to be injected.

The air case 2 is divided into a first air chamber 21 and a second air chamber 22 by being partitioned by a partition plate 20. The partition plate 20 has a hollow shape at the center as a whole, and has a horizontal portion 20a and a vertical portion 20b.
Consists of The horizontal portion 20a has a shape having a circular hole substantially at the center, and the vertical portion 20b has a cylindrical shape and is connected to the horizontal portion 20a. The vertical portion 20b has substantially the same inner diameter as the outer diameter of the large-diameter portion 6b of the combustion cylinder, and is provided so as to annularly surround the outer surface of the small-diameter portion 6a of the combustion cylinder at a substantially constant interval. The inner surface is in contact with the upper outer surface of the large diameter portion 6b of the combustion cylinder. The horizontal portion 20a of the partition plate 20 is provided with a first opening 41 having a relatively large area and a second opening 42 having a relatively small area. Note that the second opening 42 does not appear in FIG. 1, and details of the first opening 41 and the second opening 42 are shown in FIGS. 2 and 3. The area ratio between the first opening 41 and the second opening 42 is 8: 1 to 1
20: 1. The relatively large area first opening 41 is opened and closed by the movable damper 35, but the relatively small area second opening 42 is always open.

The first air chamber 21 is directly connected to the blower 1, and the second air chamber 22 receives air from the blower 1 indirectly through the first air chamber 21 and the openings 41 and 42. The lower portion of the second air chamber 22 is provided so as to annularly surround the outer surface of the large-diameter portion 6b of the combustion cylinder at substantially constant intervals. Second air chamber 2
An annular tertiary air guide 50 is provided on the outside of the lower part of 2. The first air chamber 21 communicates with the tertiary air guide 50 through the tertiary air hole 30, the flow path 40, and the opening 45. Further, the tertiary air guide 50 communicates with the space in the combustion case 60 by a plurality of air holes 55 provided on the side surface. The air that has flowed into the tertiary air guide 50 from the first air chamber 21 during operation of the burner has a plurality of air holes 55.
And flows down the outside of the combustion cylinder 6 in the combustion case 60 with a substantially axially symmetric flow distribution, thereby promoting combustion auxiliary.

The first air chamber 21 communicates with the inside of the nozzle housing cylinder 3 by an air hole 10 provided on the side surface of the nozzle housing inner tube 3a and an air hole 11 provided on the side surface of the nozzle housing outer tube 3b. In addition to communicating with the inside of the small-diameter portion 6a by an air hole 12 provided on the side surface of the combustion cylinder small-diameter portion 6a, the air hole 13 provided in the step 9 between the small-diameter portion and the large-diameter portion and a swirler 25 provide a large air flow. It also communicates with the inside of the diameter part 6b. On the other hand, the second air chamber communicates with the inside of the large diameter portion 6b of the combustion cylinder 6 through an air hole 14 provided on the side surface of the large diameter portion 6b.

The reason why only the air flow path to the air hole 14 provided on the side surface of the large diameter portion 6b is distinguished from the others is that the required air flow to the air hole 14 greatly increases and decreases as the load increases and decreases. This is because the required amount of air to be sent to the other air holes does not increase or decrease due to an increase or decrease in load. That is, the amount of fuel combustion (corresponding to the amount of oxygen consumed and the amount of air required for combustion) in the small diameter portion 6a is substantially constant regardless of the magnitude of the load. The air holes 13 provided in the step portion 9 between the small diameter portion and the large diameter portion communicate with the large diameter portion 6b, but when a small load is applied, that is, when combustion is mainly performed in the small diameter portion 6a. In addition, since it contributes to combustion by the flame holding effect, it is more convenient to control the small diameter portion 6a together with the blowing. Also, since the so-called required amount of tertiary air does not change much depending on the magnitude of the load, it is more convenient to control this together with the blowing to the small diameter portion 6a. Therefore, by combining these and blowing air by one air chamber, the purpose can be sufficiently achieved with a relatively simple structure.

The movable damper 35 is rotatably supported at one end by a hinge 37, is driven by a stepping motor 36, and can take several positions from fully open to fully closed. Note that the stepping motor 36 controls the flow rate of the injected liquid fuel,
It is controlled by a control device (not shown). When the fuel supply amount by the electromagnetic pump 4 is minimum, the combustion is almost performed in the small diameter portion 6a, but at this time, the movable damper 35 is fully closed. Therefore, most of the air blown by the blower 1 is supplied to the small-diameter portion 6a, and wasteful air supply to the large-diameter portion 6b is prevented. Even at this time, the supply of air to the large diameter portion 6b is not necessarily zero. First, step 9
The air flowing from the air holes 13 provided in the
5 to the large diameter portion 6b to add a flame holding effect to the gas in the combustion cylinder 6 and, if there is an unburned component, to supply oxygen to the unburned component for combustion. The second air chamber 22 has a second opening 42.
As a result, a small amount of air is introduced from the second air chamber 22 into the large diameter portion 6b through the air holes 14 on the side surface of the large diameter portion 6b. This air also plays an auxiliary role in burning unburned components, if any, in the combustion gas.

The flame increases as the fuel supply amount increases, and the amount of fuel burned and the required air amount in the large-diameter portion 6b increase. Therefore, the stepping motor 36 moves the movable damper 35 in accordance with the increase in the fuel supply amount. The second air chamber is gradually opened to increase the ratio of the flow rate of the air blown to the second air chamber. The total amount of air blown by the blower 1 also increases, but most of the increase
The increase in the flow rate of the air blown into the air chamber is small, and the increase in the flow rate of the air blown into the first air chamber is small. This is because even if the fuel supply amount increases or decreases, the increase or decrease in the oxygen consumption amount in the small diameter portion 6a is small. When the fuel supply amount becomes maximum, the stepping motor 36 fully opens the movable damper 35. At this time, the ratio of the flow rate of the air blown to the second air chamber also becomes maximum.

According to the present invention, an optimum amount of combustion air can be supplied to each of the small-diameter portion and the large-diameter portion of the combustion cylinder according to the load condition. And the load range (combustion amount control width) is widened.

As embodiments of the present invention, in addition to the above, various modifications can be made as follows.

As the movable damper, 35 'in FIG.
As shown in FIG. 6B, a rotary member having a shaft 38 at the center portion, or a sliding member having a sliding door shape as illustrated as 35 ″ in FIG. 6B may be used.

As the movable damper, a movable damper whose opening can be continuously changed or a movable damper which can take only two positions of open and closed may be used.

The control of the stepping motor 36 may be performed in accordance with data such as the amount of air blown and the flow rate of fuel. Specifically, a flow rate or pressure sensor is provided in the fuel supply line and its data is input to the control device. A wind speed sensor is provided in the outlet of the blower and the data is input to the control device. This can be performed by inputting data of the number of revolutions of 1 to the control device. These input values and the stop position of the stepping motor (damper opening)
The specific functional relationship with can be determined by experiment.

An embodiment in which the damper 35 is not completely closed even when the load is minimum and the second opening 42 is not provided is also possible. In addition, when the load is minimum, the damper is fully closed.
An embodiment in which the ventilation to the second air chamber is completely stopped when the load is minimum without providing the opening 42 is also possible.

As described above, the first air chamber and the second air chamber
Forming one case by partitioning it with a partition plate is easy to manufacture and convenient for retrofitting a ready-made burner. However, the first air chamber and the second air chamber are formed in this way. Instead, they may be completely separate. In that case, the first
The air chamber is connected to a blower, the second air chamber is connected to a first air chamber, and a flow rate changing means such as the damper is provided in a flow path between the first air chamber and the second air chamber. Is also possible. Further, a configuration in which a flow path downstream of the blower is branched and connected to the first air chamber and the second air chamber, respectively, and a flow rate changing means such as the above damper is provided between the blower and the second air chamber. Is also possible.

The above embodiment has a relatively simple structure in which two air chambers are provided.
Are air holes 1 provided on the side surface of the nozzle housing inner cylinder 3a
0, air hole 1 provided on the side of nozzle housing outer cylinder 3b
1, air holes 12 provided on the side surface of the small diameter portion 6a, air holes 13 provided on the step 9 between the small diameter portion and the large diameter portion, and
Ventilation is performed to each of the tertiary air holes 30 to form a multipurpose air chamber. In contrast, as another embodiment,
The first air chamber may be further divided into two or more, and different air chambers may be provided depending on the destination of the air, such as making the air chamber for blowing air to the tertiary air holes 30 independent. According to such an embodiment, it is possible to more finely control the blowing amount. The air holes 10, 11, 1
Not all 2, 13, 30 and the like are essential, and any of them can be omitted.

In the above embodiment, the air flow rate of the blower is variable. However, the air flow rate of the air blower is fixed and the exhaust path for discharging excess air is connected to the first air chamber, for example. Is possible.

[0031]

According to the present invention, an optimum amount of combustion air can be supplied to an optimum position in accordance with a load condition, so that the combustion performance is good in a full load range from a small load to a large load, and The load range (combustion amount control width) is widened. Also,
Since the combustion state is stable even under a small load, the wind resistance performance under a small load is improved, the safety is increased, and the wind pressure switch can be eliminated, so that the structure is simplified and the manufacturing cost is reduced. In addition, since it is not necessary to pay close attention to the design of the air hole as in the related art, the production becomes easy, and the input adjustment work in the production line can be omitted or simplified, so that the production cost is reduced.

[Brief description of the drawings]

FIG. 1 is a partially broken elevational view showing a burner according to an embodiment of the present invention.

FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1;

FIG. 3 is a view taken in the direction of arrows BB in FIG. 2;

FIG. 4 is a partially broken elevational view showing a part of the burner of FIG. 1;

FIG. 5 is a perspective view showing a part of the burner of FIG. 1;

FIG. 6 is a partially enlarged view schematically showing a damper of a burner according to another embodiment of the present invention.

FIG. 7 is a partially cutaway elevation view showing a conventional burner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Blower 2 Air case 3 Nozzle storage cylinder 4 Electromagnetic pump 6 Combustion cylinder 6a Small diameter part (1st inner cylinder) 6b Large diameter section (2nd inner cylinder) 7 Fuel injection nozzle 8 Ignition plug 9 Step section 10, 11, 12, 13, 14 Air hole 15 Swirler 20 Partition plate 21 First air chamber 22 Second air chamber 25 Swirler 30 Tertiary air hole 35, 35 ', 35' 'Movable damper 36 Stepping motor 37, 37' Hinge 40 Flow path 41 First opening 42 Second opening 45 Opening 50 Tertiary air guide 55 Air hole 60 Combustion case

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinji Hirase 93F, Edocho, Chuo-ku, Kobe-shi, Hyogo F-term in Noritz Co., Ltd. 3K003 JA06 JA10 KA05 KB03 MA04 NA02 3K055 AA10 BB01 BB10 BD10

Claims (3)

[Claims] 1. An air case connected to a blower and receiving air from the blower, an open-ended cylinder disposed in the air case, and a fuel injection nozzle, wherein the cylinder has at least a small-diameter portion. And a large-diameter portion, wherein the small-diameter portion receives fuel injection from the fuel injection nozzle, and further, the small-diameter portion and the large-diameter portion are provided with an opening. In the burner in which air is introduced into the body, the air case includes a first air chamber connected to the small diameter portion, and a second air chamber connected to the large diameter portion. A burner provided with a flow ratio changing means for changing a ratio of an air flow sent to the air chamber and the second air chamber. 2. The method according to claim 1, wherein the flow rate ratio changing unit includes an opening / closing unit configured by a movable damper that gradually opens a flow path of air blown to the second air chamber in accordance with an increase in the fuel injection amount. The burner according to claim 1, wherein: 3. A plurality of air passages to be blown into the second air chamber, wherein the movable damper is provided in at least one of the plurality of air passages, and at least one of the other air passages is always open. 3. The burner according to claim 2, wherein: