JP4215268B2 - Boiler with multiple high combustion nozzles - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a boiler in which combustion is controlled at three positions of high combustion, low combustion, and stop, and the combustion amount at low combustion is smaller than half of the combustion amount at high combustion.
[0002]
[Prior art]
Boilers that perform combustion in a combustion chamber surrounded by a water pipe wall by a heat transfer water pipe and that control combustion at three positions of high combustion, low combustion, and stop are widely used. In a boiler that performs general three-position combustion control, two nozzles are provided in the burner, fuel is injected from both nozzles in the case of high combustion, and fuel is injected only from one nozzle in the case of low combustion. To burn. In this case, when the combustion amount at the time of high combustion is set to 100, the combustion amount at the time of low combustion is set to be about 50, and high combustion of 100% combustion, 50% combustion according to the change of steam pressure Control either low combustion or stop. In the three-position combustion control boiler, when the steam pressure increases, the combustion amount is reduced in the order of high combustion → low combustion → stop to reduce the amount of generated steam, and when the steam pressure decreases, the combustion proceeds in the order of stop → low combustion → high combustion. Increase the amount of steam generated by increasing the amount.
[0003]
When the combustion is frequently started and stopped, the life of the parts is shortened, and the efficiency is lowered because the inside of the furnace is cooled by ventilation in the furnace performed at the time of starting and stopping. If the low combustion is 50% combustion, if the steam requirement exceeds 50% of the boiler load factor, the boiler will perform high combustion or low combustion, but if the boiler load factor is less than 50% A boiler repeats low combustion and a stop alternately, and the frequency | count of start / stop increases. Therefore, it has been considered to reduce the fuel injection amount from the low combustion nozzle and increase the fuel injection fee from the high combustion nozzle accordingly. For example, if the injection amount from the low combustion nozzle is set to 35% and the fuel for 65% is injected from the high combustion nozzle, 35% combustion is performed at low combustion, and low combustion is performed at high combustion. A total of 100% combustion is achieved by the 35% flame by the nozzle and the 65% flame by the high combustion nozzle. If the turndown ratio is increased to reduce the amount of combustion at low combustion and the amount of steam generated at low combustion, the combustion must be stopped until the load factor of the boiler becomes smaller than 35%. Therefore, the frequency of boiler start / stop can be reduced.
[0004]
In addition, boilers are desired to be small and space-saving, and the diameter of the combustion chamber is becoming smaller. However, if the combustion chamber is made smaller, the flame generated by the high combustion nozzle becomes larger in the boiler having a large turndown ratio, so that the flame contacts the heat transfer water pipe around the combustion chamber as shown in FIG. However, there is a problem that soot is generated because the flame is cooled by the heat transfer water pipe.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide a boiler capable of achieving both the prevention of soot generation and the reduction of the combustion chamber diameter in a boiler having a large turndown ratio.
[0006]
[Means for Solving the Problems]
A boiler that burns in a combustion chamber surrounded by a water pipe wall by a heat transfer water pipe, with high combustion that burns at the rated combustion amount, low combustion that burns with a combustion amount smaller than 50% of the rated combustion amount, combustion In a boiler that performs three-position combustion control that controls combustion at three stop positions, a nozzle for injecting fuel is provided with one low combustion nozzle and a plurality of high combustion nozzles, and fuel is supplied to the low combustion nozzle. A low-combustion fuel supply pipe to be sent and a high-combustion fuel supply pipe to send fuel to the high-combustion nozzle are provided, and the high-combustion fuel supply pipe is connected to each high-combustion nozzle by branching along the way. In addition, combustion is performed by injecting fuel with one low combustion nozzle at low combustion, and in addition to fuel injection by the low combustion nozzle at high combustion, a plurality of high combustion nozzles are installed. Even fuel Performing combustion by morphism.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a boiler implementing the present invention. The boiler arrange | positions the perpendicular | vertical heat-transfer water pipe 1 cyclically | annularly, and makes the boiler center part enclosed with the water pipe the combustion chamber 10. FIG. The upper part of the boiler is provided with a burner that generates a downward flame, and the burner is provided with two high combustion nozzles 3 and one low combustion nozzle 4. The fuel supply pipe for supplying fuel to the burner is provided with a fuel pump 5, and is branched downstream of the fuel pump 5 into a high combustion fuel supply pipe 12 and a low combustion fuel supply pipe 13. The high combustion fuel supply pipe 12 is provided with a high combustion solenoid valve 6, the low combustion fuel supply pipe 13 is provided with a low combustion solenoid valve 7, and the high combustion fuel supply pipe 12 is provided with a high combustion solenoid valve 6. Branches further into two paths on the downstream side. The branched high combustion fuel supply pipe 12 is connected to the two high combustion nozzles 3, and the low combustion fuel supply pipe 13 is connected to the low combustion nozzle 4. Two high-combustion nozzles 3 and one low-combustion nozzle 4 have the same fuel injection amount, and the sizes of the flames generated by the nozzles are substantially the same.
[0008]
The boiler supplies water through the lower water supply pipe 8, takes out steam from the upper steam pipe 9, and is provided with a pressure detection device 2 for detecting the steam pressure. The pressure detection device 2, the fuel pump 5, the high combustion solenoid valve 6, and the low combustion solenoid valve 7 are connected to the control device 11. The control device 11 controls the fuel pump 5, the high combustion electromagnetic valve 6, and the low combustion electromagnetic valve 7 in accordance with the steam pressure value detected by the pressure detection device 1.
[0009]
The control device 11 determines the combustion state of the boiler according to the steam pressure value detected by the pressure detection device 2, and when the steam pressure value is lower than the lower limit pressure value, the high combustion, the lower limit pressure to the upper limit pressure. If it is between, low combustion, and if higher than the upper limit pressure, stop. When combustion is performed, the control device 11 operates the fuel pump 5 and opens only the low combustion solenoid valve 7 if low combustion, and low combustion solenoid valve 7 and high combustion solenoid valve 6 if high combustion. open. When combustion is not performed, the operation of the fuel pump 5 is stopped, and the low combustion solenoid valve 7 and the high combustion solenoid valve 6 are closed.
[0010]
In the case of low combustion, since only the low combustion solenoid valve 7 is opened, the fuel from the fuel pump 5 is sent only to the low combustion nozzle 4 through the low combustion fuel supply pipe 13. The flame is burned by the fuel injected by. Since the fuel injection amount of each nozzle is constant and one third of the whole is injected, the fuel amount at the time of high combustion using one low combustion nozzle 4 and two high combustion nozzles 3 is 1. In this case, the amount of fuel at the time of low combustion using only one low combustion nozzle 4 is 1/3, which is about 33%.
[0011]
In the case of high combustion, since both the low combustion solenoid valve 7 and the high combustion solenoid valve 6 are opened, the fuel from the fuel pump 5 passes through both the low combustion fuel supply pipe 13 and the high combustion fuel supply pipe 12. Pass through. Since the high combustion fuel supply pipe 12 branches downstream of the high combustion solenoid valve 6 and is connected to the two high combustion nozzles 3, the high combustion electromagnetic supply provided in the high combustion fuel supply pipe before branching. When the valve is opened, the fuel reaches each of the two high combustion nozzles 3, and the fuel is injected from three nozzles including the low combustion nozzle 4. Since the fuel injection amount from each nozzle is made equal, three flames having substantially the same size are generated during high combustion.
[0012]
The amount of fuel sent to the two high combustion nozzles 3 through the high combustion fuel supply pipe 12 is twice the amount of fuel sent to the low combustion nozzle 4 through the low combustion fuel supply pipe 13. In the case of the conventional boiler described in FIG. 2, when the ratio of the fuel passing through the high combustion fuel supply pipe 12 is increased, the flame on the high combustion side becomes large, and the flame is cooled by contacting the water pipe, There was a problem of soot. However, in the present invention, by providing a plurality of high combustion nozzles and dividing the flame by the fuel passing through the high combustion fuel supply pipe 12, the size of each flame is reduced so that the flame contacts the water pipe. And soot can be prevented. Therefore, the size of the combustion chamber 10 can be reduced while increasing the turndown ratio.
[0013]
In addition, this invention is not limited to said Example, For example, if the nozzle 3 for high combustion is increased to three and each nozzle burns a flame of 1/4, low combustion will be 25%. Combustion can further increase the turndown ratio. Further, the low combustion nozzle 4 and the high combustion nozzle 3 may employ nozzles having different fuel injection amounts, and in that case, the turndown ratio can be set finely.
[0014]
【The invention's effect】
By implementing the present invention, in a boiler having a large turndown ratio, it is possible to achieve both prevention of soot generation and reduction in the size of the combustion chamber, and the boiler can be reduced in size and space.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a boiler implementing the present invention. FIG. 2 is a schematic explanatory diagram of a boiler in a conventional case.
DESCRIPTION OF SYMBOLS 1 Heat transfer water pipe 2 Pressure detection device 3 High combustion nozzle 4 Low combustion nozzle 5 Fuel pump 6 High combustion solenoid valve 7 Low combustion solenoid valve 8 Water supply piping 9 Steam piping 10 Combustion chamber 11 Controller 12 Fuel for high combustion Supply piping 13 Fuel supply piping for low combustion

Claims (2)

A boiler that burns in a combustion chamber surrounded by a water pipe wall by a heat transfer water pipe, with high combustion that burns at the rated combustion amount, low combustion that burns with a combustion amount smaller than 50% of the rated combustion amount, combustion In a boiler that performs three-position combustion control that controls combustion at three stop positions, a nozzle for injecting fuel is provided with one low combustion nozzle and a plurality of high combustion nozzles, and fuel is supplied to the low combustion nozzle. A low-combustion fuel supply pipe to be sent and a high-combustion fuel supply pipe to send fuel to the high-combustion nozzle are provided, and the high-combustion fuel supply pipe is connected to each high-combustion nozzle by branching along the way. In addition, combustion is performed by injecting fuel with one low combustion nozzle at low combustion, and in addition to fuel injection by the low combustion nozzle at high combustion, a plurality of high combustion nozzles are installed. Even fuel Shines, boiler provided a plurality of high combustion nozzle which is characterized in that the combustion. 2. A boiler provided with a plurality of high combustion nozzles according to claim 1, wherein a high combustion solenoid valve is provided upstream of the branch point of the fuel supply pipe for high combustion. Boiler with multiple nozzles.

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