JP6919439B2 - Combustion device - Google Patents

Description

The present invention relates to a combustion device that sprays liquid fuel into a combustion chamber and burns it.

Conventionally, there is a combustion device capable of continuously changing the amount of sprayed fuel. In such a combustion device, a supply line for supplying fuel to a spraying part such as a nozzle for spraying fuel and a return line for returning the supplied fuel to the supply source are provided to control the flow rate of returning to the return line. There is a boiler device provided with a combustion device that continuously changes the amount of spray from the spray unit (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-340465

In a conventional combustion device, it is conceivable to increase the turndown ratio (TDR) of the boiler device by increasing the flow rate returned to the return line at the time of low combustion and reducing the amount of spray from the spray section. However, when the amount of spray from the spray portion is small, the spray pressure for spraying the fuel from the spray portion decreases, and the fuel cannot be atomized and sprayed to an extent that it can be ignited. As a result, ignition failure may occur.

The present invention has been conceived in view of such circumstances, and an object of the present invention is to provide a combustion device capable of increasing the turndown ratio while promoting atomization of fuel.

In order to achieve the above object, the combustion apparatus according to an aspect of the present invention is a flow rate that adjusts the flow rate of the spray unit that sprays the liquid fuel and the liquid fuel that is supplied to the spray unit and returns to the return path. and an adjustment portion, wherein the spraying unit is seen containing a first spraying section spray volume of each of which varies with the second spray unit in accordance with the flow rate adjusted by the flow rate adjusting unit, the flow rate adjusting unit, Among the liquid fuel supplied to the spray unit, the control unit includes a flow rate adjusting valve for adjusting the flow rate of the liquid fuel returned to the return path and a control unit for controlling the opening degree of the flow rate adjusting valve. In the first combustion range in which the liquid fuel is supplied to the first spray unit of the first spray unit and the second spray unit, the liquid fuel supplied to the first spray unit is returned to the return path. The opening degree of the flow rate adjusting valve is controlled so as to change the flow rate of the fuel, and the liquid fuel is supplied to both the first spraying portion and the second spraying portion, which is larger than the combustion amount in the first combustion range. In the second combustion range, the flow rate of the liquid fuel supplied to the first spray unit is not returned to the return path, while the flow rate of the liquid fuel supplied to the second spray unit is returned to the return path. The opening degree of the flow rate adjusting valve is controlled so as to change .

According to the above configuration, by providing the first spraying portion and the second spraying portion, it is possible to suppress a decrease in the spray pressure in each spraying portion. As a result, atomization of the fuel to be sprayed can be promoted, and the turndown ratio can be increased. Further, by providing a flow rate adjusting unit for adjusting the flow rate of the liquid fuel returned to the return path, the amount of spray from the first spraying unit and the second spraying unit can be adjusted.

Preferably, the flow rate adjusting unit includes, as the flow rate adjusting valve, a first flow rate adjusting valve that adjusts the flow rate of the liquid fuel supplied to the first spraying unit and returned to the return path, and the second flow rate adjusting valve. and a second flow rate control valve for controlling the flow rate of liquid fuel back into the return path of the liquid fuel supplied to the spray unit, wherein the control unit, the in the first combustion range, the first flow rate control valve controls opening by changing the flow rate of liquid fuel back into the return path, in the pre-Symbol second combustion range, the first flow rate adjusting valve is controlled to a closed state, open the second flow rate control valve Control the degree.

According to the above configuration, the control unit can adjust the combustion amount in the first combustion range by controlling the opening degree of the first flow rate adjusting valve, and control the opening degree of the second flow rate adjusting valve to perform the second. The amount of combustion in the combustion range can be adjusted. Therefore, it leads to promotion of atomization of fuel.

Preferably, the spray unit includes a third spray unit for igniting the first spray unit.

According to the above configuration, ignition failure of the first spraying portion can be more reliably suppressed.

It is a figure which shows typically the structure of the combustion apparatus. It is a time chart which shows the operation of a combustion apparatus.

<About the outline configuration>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a schematic configuration of the combustion device 1 according to the present embodiment will be described with reference to FIG. The combustion device 1 is mounted on an oil-fired boiler or the like that generates steam.

The combustion device 1 includes a first nozzle 2 and a second nozzle 3 for spraying a liquid fuel such as oil, an ignition nozzle 4 for igniting at least the first nozzle 2, a plurality of valves 41 to 46, and these valves. A control unit 5 for controlling the opening / closing (or opening degree) of 41 to 46 is provided.

The first nozzle 2, the second nozzle 3, and the ignition nozzle 4 each form a spraying unit for spraying the fuel supplied from the fuel pump 10 in the combustion chamber 9. Specifically, the first nozzle 2 constitutes the first spray unit, the second nozzle 3 constitutes the second spray unit, and the ignition nozzle 4 constitutes the third spray unit. The combustion range of combustion in the combustion chamber 9 changes according to the amount of fuel sprayed from each of the nozzles 2 and 3 among these nozzles, that is, the amount of fuel sprayed. Although the nozzle is illustrated as the spray unit, the spray unit is not limited to the nozzle as long as it is a member capable of spraying (spraying) fuel, and may be composed of other members.

The combustion range in the combustion device 1 is provided with an ignition range, a first combustion range, and a second combustion range. In the ignition range, the fuel sprayed from the ignition nozzle 4 is burned. In the first combustion range, the amount of combustion is larger than that in the ignition range, and the fuel ignited by the ignition nozzle 4 and sprayed from the first nozzle 2 is burned. In the second combustion range, the amount of combustion is larger than that in the first combustion range, and the fuel ignited by the first nozzle 2 and sprayed from the second nozzle 3 is burned while continuing the combustion by the first nozzle 2.

The ignition nozzle 4 sprays fuel at the start of combustion and is ignited by an ignition device (for example, an ignition transformer). The ignition nozzle 4 sprays fuel at the maximum possible spray amount that can be sprayed from the start of combustion. Therefore, the fuel can be atomized and sprayed, and the fuel can be reliably ignited. The ignition nozzle 4 sprays fuel and burns in the ignition range, but may be one that sprays and burns fuel not only in the ignition range but also in the first combustion range and the second combustion range.

The first nozzle 2 is sprayed with fuel and ignited by the ignition nozzle 4. The spray amount from the first nozzle 2 is adjusted in the first combustion range and is constant (for example, the maximum possible spray amount) in the second combustion range.

The second nozzle 3 sprays fuel and is ignited by the first nozzle 2. The second nozzle 3 does not spray fuel in the first combustion range, but sprays fuel only in the second combustion range. The amount of spray from the second nozzle 3 is adjusted in the second combustion range.

The diameter (inner diameter) of the ignition nozzle 4 is smaller than the diameter (inner diameter) of the first nozzle 2 and the second nozzle 3. The diameters of the first nozzle 2 and the second nozzle 3 are configured so that the maximum possible spray amount is the same.

In the conventional return flow nozzle, one nozzle corresponds to the entire combustion range of the combustion device (for example, the flow rate is the sum of the flow rate of the first nozzle 2 and the flow rate of the second nozzle 3 in the present embodiment. One nozzle. Hereinafter, it is also referred to as a conventional nozzle). However, since the conventional nozzle has a large diameter, the spray pressure is dispersed. For this reason, it has been difficult to atomize and spray the fuel to an extent that it can be ignited until the supplied fuel reaches a predetermined amount or more. Therefore, the combustion device 1 in the present embodiment employs a plurality of nozzles having a diameter smaller than that of the conventional nozzles to increase the spray pressure per nozzle and promote the atomization of the fuel. As a result, even if the amount of fuel is smaller than that of the conventional nozzle, the fuel can be atomized and sprayed.

In the present embodiment, the fuel is supplied from the fuel tank 8 to the first nozzle 2, the second nozzle 3, and the ignition nozzle 4 via each of the three paths 61, 62, and 63 branched from the main path 6. It is said. Specifically, the main route 6 branches into the first to third routes 61 to 63 at an intermediate position. The first nozzle 2 is connected to the first path 61, the second nozzle 3 is connected to the second path 62, and the ignition nozzle 4 is connected to the third path 63.

The valve 41 is provided on the main path 6, and is, for example, a valve that can switch between two states, an open state and a closed state, that is, a switching valve. The valve 42 is a switching valve provided on the first path 61. The valve 43 is a switching valve provided on the second path 62. The valve 44 is a switching valve provided on the third path 63. The valves 41, 42, 43, 44 as switching valves are composed of, for example, solenoid valves. In the following description, in order to facilitate these distinctions, the valve 41 is referred to as a main solenoid valve, the valve 42 is referred to as a first solenoid valve, the valve 43 is referred to as a second solenoid valve, and the valve 44 is referred to as a third solenoid valve.

A first return path 71 for returning the fuel supplied from the first path 61 to the fuel tank 8 is connected to the first nozzle 2. Further, a second return path 72 for returning the fuel supplied from the second path 62 to the fuel tank 8 is connected to the second nozzle 3. Both the first return path 71 and the second return path 72 join the return main path 7 connected to the fuel tank 8.

The valve 45 is a flow rate adjusting valve provided on the first return path 71. The valve 46 is a flow rate adjusting valve provided on the second return path 72. The valve 45 and the valve 46 as the flow rate adjusting valve are throttle valves whose opening degree can be adjusted, respectively, and are composed of, for example, a motor valve.

The valve 45 returns a part of the fuel supplied from the first path 61 to the fuel tank 8 via the first return path 71 according to the opening degree, thereby reducing the amount of spray from the first nozzle 2. A first flow rate adjusting valve to be adjusted is configured. The valve 46 returns a part of the fuel supplied from the second path 62 to the fuel tank 8 via the second return path 72 according to the opening degree, thereby reducing the amount of spray from the second nozzle 3. A second flow rate adjusting valve to be adjusted is configured. The first flow rate adjusting valve and the second flow rate adjusting valve can be adjusted so that the larger the opening degree, the larger the amount of fuel returned, and therefore the smaller the amount of spray from the first nozzle 2 or the second nozzle 3. As the opening degree is smaller, the amount of fuel returned is smaller, so that the amount of spray from the first nozzle 2 or the second nozzle 3 can be adjusted to be larger.

The control unit 5 controls the opening and closing of the solenoid valves 41 to 44, and also controls (adjusts) the opening and closing of the first flow rate adjusting valve 45 and the second flow rate adjusting valve 46. The control unit 5 can proportionally control the opening degrees of the flow rate adjusting valves 45 and 46. The control unit 5 is realized by a computer including a memory, a timer, and an arithmetic processing unit inside.

<About operation>
The operation of the combustion device 1 according to the present embodiment will be described with reference to FIG. FIG. 2A shows a change in the spray amount of each spraying portion (nozzle), and FIG. 2B shows a load factor in the entire combustion device 1. Before combustion, the valves 41 to 44 are in the closed state, and the valves 45 and 46 are in the fully open state where the opening degree is maximized.

When the control unit 5 starts combustion (t1), the main solenoid valve 41 is opened, and then (or at the same time), the third solenoid valve 44 is opened to supply fuel to the ignition nozzle 4. As a result, the fuel is sprayed from the ignition nozzle 4 at the maximum possible spray amount (100%) of the ignition nozzle 4. In this state, the ignition device ignites.

After that, the control unit 5 controls the opening degree of the first flow rate adjusting valve 45 so that the spray amount from the first nozzle 2 becomes 20% of the maximum possible spray amount of the first nozzle 2, and then the first solenoid valve. The 42 is opened (t2). The diameter of the first nozzle 2 is smaller than that of the conventional nozzle. Therefore, even if the amount of spray from the first nozzle 2 is as small as 20%, the fuel can be reliably atomized and sprayed as compared with the case where the amount of spray from the conventional nozzle is 20%. Therefore, the first nozzle 2 can be reliably ignited. The fuel supply to the ignition nozzle 4 and the fuel supply to the first nozzle 2 may be started at the same time.

After the first nozzle 2 is ignited (t3), the control unit 5 closes the third solenoid valve 44 to stop the spraying from the ignition nozzle 4, and proportionally adjusts the opening degree of the first flow rate adjusting valve 45. Make it smaller (continuously). In this way, the control unit 5 controls the opening degree of the flow rate adjusting valve 45 in the first combustion range to control the flow rate of the fuel supplied to the first nozzle 2. As a result, the amount of fuel sprayed from the first nozzle 2 can be proportionally increased in the first combustion range. The timing of closing the third solenoid valve 44 is not limited to the timing of starting the control to reduce the opening degree of the first flow rate adjusting valve 45, but the timing before that if the first nozzle 2 is ignited. It may be. When the opening of the first flow rate adjusting valve 45 is fully closed, the fuel returning to the first return path 71 becomes zero, so that the spray amount from the first nozzle 2 is the maximum possible spray amount of the first nozzle 2. (T4). At this time, the load factor of the entire combustion device 1 is 50%.

When the spray amount of the first nozzle 2 reaches the maximum possible spray amount as the opening degree of the first flow rate adjusting valve 45 is adjusted (reduced) (t4), the control unit 5 adjusts the opening degree of the first flow rate adjusting valve 45. While continuing the (closed state), the second solenoid valve 43 is opened and the opening degree of the second flow rate adjusting valve 46 is proportionally reduced. When the spray amount from the first nozzle 2 reaches the maximum possible spray amount of the first nozzle 2 (or a little later), the second solenoid valve 43 is opened and the second flow rate adjusting valve 46 is controlled. However, the timing for opening the second solenoid valve 43 and starting the control of the second flow rate adjusting valve 46 may be a time when a predetermined time has elapsed from the start of combustion.

In this way, in the second combustion range, the control unit 5 controls the opening degree of the second flow rate adjusting valve 46 to set the spray amount of the first nozzle 2 to the maximum possible spray amount, and then the second nozzle 3 Control the amount of spray. As a result, the amount of fuel sprayed from the second nozzle 3 can be proportionally increased while the amount of sprayed from the first nozzle 2 is kept constant. Since the second nozzle 3 can atomize and spray the fuel even if the amount of fuel is smaller than that of the conventional nozzle, the second nozzle 3 can be ignited at an early stage. When the opening degree of the second flow rate adjusting valve 46 is fully closed, the spray amount from the second nozzle 3 becomes the maximum possible spray amount (t5). At this time, the load factor of the entire combustion device 1 is 100%.

In FIG. 2, an example of the control contents by the control unit 5 from the start of combustion to reaching the maximum combustion amount has been described. The control unit 5 sets, for example, a load factor corresponding to the combustion amount of the boiler, and controls the opening degrees of the first flow rate adjusting valve 45 and the second flow rate adjusting valve 46 so as to have the load factor. Thereby, the combustion device 1 can be proportionally controlled so as to have an arbitrary load factor.

As described above, in the present embodiment, by adopting the first nozzle 2 and the second nozzle 3, even a small amount of fuel can be atomized and sprayed as compared with the conventional nozzle. Therefore, the turndown ratio can be increased while promoting the atomization of the fuel. Further, by providing the first flow rate adjusting valve 45 and the second flow rate adjusting valve 46 in each of the first return path 71 and the second return path 72, the amount of spray from each of the first nozzle 2 and the second nozzle 3 is proportional. Can be adjusted to. Further, since the spray amount is not adjusted on the upstream side of the first nozzle 2 and the second nozzle 3, atomization of the fuel is likely to be promoted.

The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. Hereinafter, variations of the above-described embodiment applicable to the present invention will be described.

In the above embodiment, an example in which the diameters of the first nozzle 2 and the second nozzle 3 are the same has been described, but the present invention is not limited to this, and the diameter of the first nozzle 2 is smaller than the diameter of the second nozzle 3. It may be a defined one. That is, the maximum possible spray amount of each of the first nozzle 2 and the second nozzle 3 may have a relationship of "first nozzle 2 <second nozzle 3". As a result, if the maximum possible spray amount is the same as that in the present embodiment, the minimum spray amount of the first nozzle 2 can be kept small, so that the turndown ratio can be further increased while promoting the atomization of the fuel. It can be expanded further. Further, in the first combustion range, after controlling the opening degree of the first flow rate adjusting valve 45 so that the spray amount from the first nozzle 2 becomes 20% of the maximum possible spray amount, the first solenoid valve 42 is opened. An example started by However, the spray amount at the start of the first combustion range is not limited to 20%, and may be 15% or 25% depending on the set turndown ratio, and the first flow rate adjusting valve 45 is fully opened. It may be started by opening the first solenoid valve 42 in the state.

Although the example in which the combustion device 1 in the above embodiment is proportionally controlled so as to have an arbitrary load factor has been described, the present invention is not limited to this, and multi-position control may be used. For example, the opening degrees of the first flow rate adjusting valve 45 and the second flow rate adjusting valve 46 are set (stored) in advance for each of stop, low combustion, medium combustion, and high combustion, and the control unit 5 uses, for example, a boiler. The opening degree of the first flow rate adjusting valve 45 and the second flow rate adjusting valve 46 is controlled so as to be one of stop, low combustion, medium combustion, and high combustion according to the amount of steam generated by the above. You may.

The combustion device 1 in the above embodiment has described an example in which an ignition range is provided by the ignition nozzle 4, but the present invention is not limited to this, and the first nozzle 2 is provided at the start of combustion without providing the ignition nozzle 4 and the ignition range. It may be ignited by an igniter by spraying fuel from the igniter. Even in this case, even if the amount of fuel is smaller than that of the conventional nozzle, the fuel can be atomized and sprayed, so that ignition failure and generation of carbon monoxide can be suppressed.

In the above embodiment, an example in which the first nozzle 2 and the second nozzle 3 are provided as the nozzles for adjusting the fuel spray amount has been described, but the present invention is not limited to this, and three or more nozzles are provided. You may. For example, the diameters of the first nozzle 2 and the second nozzle 3 may be made smaller, but different nozzles (three nozzles in total) may be provided. In this case, a return path is also provided for the third nozzle, and a flow rate adjusting valve is provided on the return path to control the opening degree of the flow rate adjusting valve, thereby reducing the amount of spray from the third nozzle. You may try to adjust. As a result, the atomization of the fuel can be further promoted, and the turndown ratio can be further expanded.

Further, in the above embodiment, an example in which a flow rate adjusting valve is provided corresponding to each of a plurality of nozzles including the first nozzle 2 and the second nozzle 3 is shown, but the present invention is not limited to this, and the flow rate adjusting valve is not limited to this. By providing one multi-way adjusting valve (for example, a three-way valve, a four-way valve, etc.) and controlling the opening degree of the multi-way adjusting valve, the amount of spray from a plurality of nozzles may be adjusted. For example, instead of the first flow rate adjusting valve 45 and the second flow rate adjusting valve 46, a multi-way adjusting valve is installed at the confluence point where the first return path 71 and the second return path 72 merge and are connected to the return main path 7. By providing and controlling the opening degree of the multi-way adjusting valve, the flow rate returning to each of the first return path 71 and the second return path 72 may be adjusted. As a result, it is possible to suppress an increase in the number of parts and an increase in manufacturing cost.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Combustion device 2 1st nozzle 3 2nd nozzle 4 Ignition nozzle 5 Control unit 6 Main path 7 Return main path 8 Fuel tank 9 Combustion chamber 10 Fuel pump 41 Electromagnetic valve 41 Main electromagnetic valve 42 1st electromagnetic valve 43 2nd electromagnetic valve 44 3rd electromagnetic valve 45 1st flow rate regulating valve 46 2nd flow rate regulating valve 61 3rd path 61 1st path 62 2nd path 63 3rd path 71 1st return path 72 2nd return path

Claims (3)

A spray part that sprays liquid fuel and
A flow rate adjusting unit for adjusting the flow rate of the liquid fuel supplied to the spray unit and returning to the return path is provided.
The spray unit, viewed contains a first spraying section spray volume of each of which varies with the second spray unit in accordance with the flow rate adjusted by the flow rate adjusting unit,
The flow rate adjusting unit
A flow rate adjusting valve that adjusts the flow rate of the liquid fuel supplied to the spray unit and returned to the return path.
A control unit that controls the opening degree of the flow rate adjusting valve is included.
The control unit
In the first combustion range in which the liquid fuel is supplied to the first spray unit of the first spray unit and the second spray unit, the liquid fuel supplied to the first spray unit is returned to the return path. The opening degree of the flow control valve is controlled so as to change the flow rate of the liquid fuel.
In the second combustion range, which is larger than the amount of combustion in the first combustion range and supplies liquid fuel to both the first spray section and the second spray section, the liquid fuel supplied to the first spray section. A combustion device that controls the opening degree of the flow rate adjusting valve so as to change the flow rate of the liquid fuel supplied to the second spray unit while returning the liquid fuel to the return path. The flow rate adjusting unit serves as the flow rate adjusting valve.
A first flow rate adjusting valve that adjusts the flow rate of the liquid fuel returned to the return path among the liquid fuels supplied to the first spray unit, and
A second flow rate adjusting valve for controlling the flow rate of the liquid fuel returned to the return path among the liquid fuel supplied to the second spray unit is included.
The control unit
In the first combustion range, the opening degree of the first flow rate adjusting valve is controlled to change the flow rate of the liquid fuel returned to the return path.
Before SL in the second combustion range, the first flow rate adjusting valve is controlled to the closed state, controls the opening of the second flow control valve, a combustion apparatus according to claim 1. The combustion apparatus according to claim 1 or 2, wherein the spray unit includes a third spray unit for igniting the first spray unit.

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