JP2005147558A - Boiler performing low combustion by small-capacity burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent combustion from becoming unstable while changing a rotation speed of a blower according to a combustion amount. <P>SOLUTION: This boiler has a combustion device 2 comprising a small-capacity burner 6 and a combustion amount variable burner 5, and performs low combustion making only the small-capacity burner 6 burn, middle combustion performing small heating power combustion by the combustion amount variable burner 5, and high combustion performing large heating power combustion by the combustion amount variable burner 5. The boiler is provided with: a rotation speed controller 8 changing the rotation speed of the blower 10; a damper device 9 limiting a flow passage area of an air blowing path 7; and an operation controller 11 performing combusting air amount supply control and fuel supply control. The rotation speed controller 8 is set with a high combustion rotation speed/a middle combustion rotation speed/a low combustion rotation speed, the damper device 9 is set with a high combustion opening/a middle combustion opening/a low combustion opening, and the operation controller 11 outputs instructions of the high combustion opening at the high combustion rotation speed in time of the high combustion, the middle combustion opening at the middle combustion rotation speed in time of the middle combustion, and the low combustion opening at the low combustion rotation speed in time of the low combustion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a boiler that has a small-capacity burner and a combustion amount variable burner and controls the combustion amount in stages from high combustion, medium combustion, and low combustion.

  There is a boiler that controls the amount of steam generated by adjusting the amount of fuel supplied to the combustion device and the amount of combustion air and adjusting the amount of combustion. In the boiler described in Japanese Patent Laid-Open No. 2001-272029, the combustion amount is adjusted by high combustion, medium combustion, and low combustion, and the combustion amount is controlled according to the steam pressure value. The boiler is provided with a damper device that changes the flow passage area of the air passage as an air flow adjusting device, and controls the amount of combustion air supplied to the burner by changing the opening degree of the damper device.

  When adjusting the combustion amount for high combustion, medium combustion, and low combustion, the required air amount differs greatly between high combustion and low combustion, so if the air amount is adjusted by changing the rotation speed of the blower Since the rotation speed of the blower at the time of low combustion is significantly reduced, the power consumption can be reduced and the generation of noise can also be reduced. However, when the difference in the amount of supply of combustion air is large, if the amount of blown air is reduced by reducing the rotational speed of the blower, the static pressure of the combustion air becomes small, which causes the problem of unstable combustion. .

In addition, a combustion amount variable burner and a small capacity burner are provided, only the small capacity burner is combusted at low combustion and the combustion amount variable burner is stopped, and combustion is performed by the combustion amount variable burner at medium combustion and high combustion. Therefore, if the combustion amount variable burner is ignited by shifting from low combustion to middle combustion, the static pressure on the blower side is low, so the impact of pressure fluctuation is transmitted to the burner upstream side, The problem of unstable combustion occurs.
JP 2001-272029 A

  The problem to be solved by the present invention is that the combustion air becomes unstable by reducing the static pressure of the combustion air while reducing the power consumption by changing the rotational speed of the blower according to the combustion amount. Is to provide a boiler that can be prevented.

  According to the first aspect of the present invention, there is provided a combustion device comprising a small capacity burner and a combustion amount variable burner, and a combustion air supply amount adjusting means for adjusting the combustion air supply amount to the combustion device. Combustion amount is controlled step by step with low combustion that burns only, medium combustion that performs small thermal power combustion with variable combustion amount burner, high combustion that performs large thermal power combustion with variable combustion amount burner, and according to each combustion amount A boiler that regulates the amount of air supplied for combustion, and the means for adjusting the amount of air supplied for combustion includes a rotation speed control device that changes the rotational speed of the blower that sends the combustion air, and air for combustion from the blower to the combustion device Is provided with an operation control device that controls the fuel supply control to the combustion device, the rotational speed control device, and the combustion air amount supply control to the damper device. In the boiler The number control device is set to high combustion speed, medium combustion speed, and low combustion speed, and the engine speed is set to decrease in order of high combustion speed, medium combustion speed, and low combustion speed. In the damper device, the high combustion opening, medium combustion opening, and low combustion opening are set, and the opening is set to decrease in the order of high combustion opening, medium combustion opening, and low combustion opening. The operation control device changes the combustion amount for high combustion, medium combustion, and low combustion according to the required amount of combustion, high combustion opening at high combustion rotation speed at high combustion, medium combustion rotation speed at medium combustion The boiler performs low combustion with a small-capacity burner, which outputs a command for setting a low combustion opening at a low combustion rotational speed during medium combustion opening and low combustion.

  According to a second aspect of the present invention, in the boiler that performs low combustion by the small-capacity burner, when shifting from low combustion to medium combustion, the operation control device firstly maintains the damper device at the low combustion opening degree. Outputs a command to change the rotational speed to a high combustion rotational speed, then outputs a command to start fuel supply for medium combustion to the combustion amount variable burner, then sets the blower rotational speed to the medium combustion rotational speed, and opens the damper opening Is a command to output a medium combustion opening.

  By changing the rotation speed of the blower and the damper opening, the change in static pressure of the combustion air can be reduced, and when shifting from low combustion to medium combustion to start combustion of the combustion amount variable burner, In addition, since the pressure of the combustion air is increased more and the combustion apparatus is covered with the damper device, it is possible to prevent the impact of pressure fluctuation accompanying the ignition of the combustion amount variable burner from being transmitted to the burner upstream side.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a boiler for carrying out the present invention. A combustion device 2 including a combustion amount variable burner 5 and a small-capacity burner 6 for generating a flame downward is provided at the upper part of the boiler, and the flame is burned in the combustion chamber 3 in the center of the boiler. The combustion amount variable burner 5 enables switching between large thermal power combustion and small thermal power combustion, and the small capacity burner 6 performs combustion with a smaller combustion amount than the small thermal power combustion by the combustion amount variable burner 5. is there. Combustion air used in the combustion amount variable burner 5 and the small capacity burner 6 is supplied by the blower 10. The blower 10 is connected to a rotation speed control device 8 made of an inverter device or the like, and the rotation speed of the blower 10 is controlled by the rotation speed control device so as to change the amount of blown air. The blower 10 and the combustion device 2 are connected by a blower passage 7, and combustion air from the blower 10 is sent to the combustion device 2 through the blower passage 7. A damper device 9 is provided in the middle of the air passage 7, and the flow passage area of the air passage 7 is changed by the damper device 9.

  The fuel supply piping 4 for supplying fuel to the combustion amount variable burner 5 and the small-capacity burner 6 is branched into three systems in the middle, and the low combustion fuel valve 12 and the middle combustion fuel valve 13 are respectively branched. A high combustion fuel valve 14 is provided. The fuel supply pipe provided with the low combustion fuel valve 12 supplies fuel to the small-capacity burner 6, and the fuel supply pipe provided with the medium combustion fuel valve 13 and the fuel provided with the high combustion fuel valve 14. The supply pipe supplies fuel to the combustion amount variable burner 5.

  The boiler supplies water from the lower water supply pipe, takes out the steam from the upper steam pipe and sends it to the steam-using device, and provides a pressure detection device 1 for detecting the steam pressure value in the steam section. An operation control device 11 connected to each of the pressure detection device 1, the low combustion fuel valve 12, the middle combustion fuel valve 13, the high combustion fuel valve 14, the damper device 9, and the rotation speed control device 8 is provided.

  The operation control device 11 determines a combustion amount according to the steam pressure value. When the steam pressure value is lower than the lower limit pressure, the combustion amount variable burner 5 is burned with high heating power, and when the steam pressure value is higher than the upper limit pressure, the combustion amount variable burner 5 is stopped and small. If the combustion is performed only for the capacity burner 6 and the steam pressure value is an intermediate value, the combustion amount variable burner 5 is set to the middle combustion for burning with a small heating power. Combustion in the order of high combustion, medium combustion, and low combustion so that the amount of combustion in each of high combustion, medium combustion, and low combustion is 50% for medium combustion and 10% for low combustion when high combustion is 100% Set the amount to be small. The fuel supply amount and the combustion air supply amount are set for each combustion amount, and the operation control device 11 determines the combustion amount based on the steam pressure value, and the fuel supply amount and the combustion air so that the determined combustion amount is obtained. Adjust the supply amount.

  The fuel supply amount is the high combustion fuel supply amount when the low combustion fuel valve 12, the middle combustion fuel valve 13, and the high combustion fuel valve 14 are all open, and the low combustion fuel valve 12 and the middle combustion fuel valve. The fuel supply amount in each fuel supply pipe is set so that when 13 is opened, the fuel supply amount for medium combustion is set, and when only the low combustion fuel valve 12 is opened, the fuel supply amount for low combustion is set. . The combustion air supply amount is controlled by combining the rotational speed of the blower 10 and the opening degree of the damper device 9, and the rotational speed control device 8 has a high combustion rotational speed, a middle combustion rotational speed, and a low combustion rotational speed. The damper device 9 is set with a high combustion opening, a middle combustion opening, and a low combustion opening. Also in this case, the rotational speed and the opening degree are set so as to decrease in the order of high combustion, medium combustion, and low combustion. When the rotational speed control device 8 sets the rotational speed of the blower 10 to a high combustion rotational speed and the damper device 9 has a high combustion opening, the high combustion air supply amount, the rotational speed of the blower 10 to the medium combustion rotational speed, and the damper device When 9 is the medium combustion opening, the medium combustion air supply amount is set, the rotation speed of the blower 10 is set to the low combustion rotation speed, and when the damper device 9 is set to the low combustion opening, the low combustion air supply amount is set.

  Combustion is controlled at three positions of high combustion, medium combustion, and low combustion, and any combustion is performed when the boiler is in an operating state. FIG. 2 is a time chart showing the control state of the steam pressure value, the combustion amount, the blower rotation speed, and the damper opening, and the control state will be described based on FIG. In FIG. 2, the steam pressure value is between the upper limit value and the lower limit value, and the combustion amount starts from the state of medium combustion. In this case, for fuel supply, the low combustion fuel valve 12 and the medium combustion fuel valve 13 are opened, the rotational speed of the blower 10 is set to the intermediate combustion rotational speed, and the opening degree of the damper device 9 is set to the intermediate combustion opening degree.

  When the steam pressure rises and becomes higher than the upper limit, the combustion amount is set to low combustion. The operation control device 11 outputs a closing command to the middle combustion fuel valve 13 and stops the fuel supply to the combustion amount variable burner 5, thereby reducing the combustion only by the small capacity burner 6. Further, the operation control device 11 outputs a command for setting the rotational speed of the blower 10 to a low combustion rotational speed to the rotational speed control device 8 and setting the opening to a low combustion opening to the damper device 9. Let the air supply amount be the supply amount for low combustion. Since the rotational speed of the blower 10 is set to the low combustion rotational speed at the time of low combustion, the power consumption and noise amount by the blower 10 can be reduced. Moreover, although the air quantity which flows in the ventilation path 7 reduces by setting it as the low combustion rotation speed, the static pressure of combustion air can be ensured by narrowing a flow-path area by the damper apparatus 9, and combustion is stabilized. Can be made.

  Thereafter, when the steam pressure value decreases and becomes lower than the upper limit value, the combustion amount is set to medium combustion. In this case, the operation control device 11 first outputs a command to change the blower rotational speed to the high combustion rotational speed to the rotational speed control device 8 while the opening degree by the damper device 9 remains at the low combustion opening degree. If the rotational speed of the blower 10 is set to a high combustion rotational speed, a larger amount of air than the intermediate combustion rotational speed is sent to the blower passage 7, but the damper device 9 has a low combustion opening, and the damper device 9 has an air amount. Therefore, the amount of air reaching the combustion amount variable burner 5 is an intermediate amount of air between the low combustion and the high combustion.

  Next, the operation control device 11 outputs an opening command to the middle combustion fuel valve 13 and starts fuel supply to the combustion amount variable burner 5. When fuel is supplied to the combustion amount variable burner 5, the flame of the small capacity burner 6 becomes a fire type, and combustion also starts on the combustion surface of the combustion amount variable burner 5. A pressure shock is generated at the moment of start of combustion by the combustion amount variable burner 5, and when the pressure shock is transmitted to the upstream side of the burner, the supply state of combustion air is disturbed and the combustion becomes unstable, but the rotation speed of the blower 10 Is increased to increase the supply pressure of the combustion air, and the damper device 9 further narrows the flow passage area of the blower passage 7, so that the pressure impact when the combustion amount variable burner 5 is ignited reaches the burner upstream side. Can be prevented. Therefore, combustion does not become unstable at the time of transition from low combustion to medium combustion, and stable combustion can be continued.

  When a predetermined time elapses after the middle combustion is started by opening the middle combustion fuel valve 13, the operation control device 11 sets the blower rotational speed to the middle combustion rotational speed with respect to the rotational speed control device 8, and the damper device 9 outputs a command for setting the damper opening to the middle combustion opening. By setting the blower rotation speed to the medium combustion rotation speed and the damper opening to the medium combustion opening, the original medium combustion is achieved.

  When the steam pressure further decreases and becomes lower than the lower limit, the combustion amount is set to high combustion. The pressure impact is generated when the combustion amount is changed only when the combustion of the combustion amount variable burner 5 starts from the low combustion to the middle combustion. In other cases, the pressure impact does not occur. When shifting to high combustion, it is possible to shift directly. The operation control device 11 outputs a command to change to a high combustion rotational speed to the rotational speed control device 8 and a command to change to a high combustion opening degree to the damper device 9, thereby reducing the combustion air supply amount. By supplying a command for opening the high combustion fuel valve 14 with a high combustion supply amount, the fuel supply amount is set to a high combustion supply amount.

  Thereafter, the fuel supply amount and the combustion air supply amount are changed in accordance with the combustion amount. Only during the transition from low combustion to medium combustion, the blower rotation speed is set to the high combustion rotational speed, the damper device supplies the combustion air supply for transition to a low combustion opening degree, and directly transitions during other combustion transitions .

Outline diagram of boiler implementing the present invention Time chart showing control of fuel supply and combustion air supply in one embodiment

Explanation of symbols

1 Pressure detection device 2 Combustion device
DESCRIPTION OF SYMBOLS 3 Combustion chamber 4 Fuel supply piping 5 Combustion amount variable burner 6 Small capacity burner 7 Air passage 8 Rotation speed control device 9 Damper device 10 Blower 11 Operation control device 12 Low combustion fuel valve 13 Medium combustion fuel valve 14 High combustion fuel valve

Claims (2)

  Combustion device composed of a small-capacity burner and a variable combustion amount burner, and a combustion air supply amount adjusting means for adjusting the supply amount of combustion air to the combustion device are provided. The combustion amount is controlled in stages, with medium combustion with small thermal combustion with a variable burner and high combustion with large thermal combustion with a variable burner, and the combustion air supply amount is adjusted to each combustion amount. The combustion air supply amount adjusting means includes a rotation speed control device that changes a rotation speed of a blower that sends combustion air, and a flow passage area of a blower passage that supplies the combustion air from the blower to the combustion device In a boiler comprising a damper device that restricts fuel, and a fuel supply control to the combustion device, a rotation speed control device, and an operation control device that performs a combustion air amount supply control to the damper device, the rotation speed control device includes High combustion The rotation speed, medium combustion speed, and low combustion speed are set, and the rotational speed is set to decrease in the order of high combustion speed, medium combustion speed, and low combustion speed. Set the opening, middle combustion opening, low combustion opening, the opening is set to decrease in order of high combustion opening, medium combustion opening, low combustion opening, the operation control device, The amount of combustion is changed according to the required amount of combustion: high combustion, medium combustion, and low combustion, and high combustion opening at high combustion speed at high combustion, medium combustion opening at low combustion speed at medium combustion, low combustion at medium combustion A boiler that performs low combustion with a small-capacity burner characterized by outputting a command for setting a low combustion opening at a low combustion rotational speed. In the boiler that performs low combustion by the small-capacity burner according to claim 1, when shifting from low combustion to medium combustion, the operation control device firstly increases the blower rotational speed while the damper device remains at the low combustion opening degree. A command to change to the rotation speed is output, then a command to start supplying fuel for medium combustion to the burner with variable combustion amount is output, then the blower rotation speed is set to the medium combustion rotation speed, and the damper opening is set to the medium combustion opening The boiler which performs the low combustion by the small capacity | capacitance burner characterized by the above-mentioned.

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