JP4191359B2 - Boiler with continuous combustion - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a boiler that controls the combustion amount at three positions of high combustion, medium combustion, and low combustion and performs continuous combustion during operation.
[0002]
[Prior art]
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. As a combustion amount control method during boiler operation, boilers that control the combustion amount at three positions of high combustion, low combustion, and stop are widely used. In this case, assuming that the combustion amount at high combustion is 100, the combustion amount at high combustion is set to approximately twice the combustion amount at low combustion so that the combustion amount at low combustion becomes approximately 50. Combustion amount is controlled according to the steam pressure value. In the case of 3-position combustion control, when the steam pressure value detected by the pressure detection device is low, high combustion of 100% combustion, and when the steam pressure value is high When the combustion is stopped, in the middle, the combustion is reduced to 50% combustion, and the steam pressure value is raised or lowered within a predetermined range.
[0003]
When the boiler is turned on, combustion control is automatically performed according to the steam pressure value. When starting the combustion of the boiler, it is necessary to remove combustible components from the furnace before ignition. Therefore, post-purge immediately after stopping combustion and pre-purge immediately before starting combustion are performed. To start burning. The change of the combustion amount between the high combustion and the low combustion can be performed only by increasing / decreasing the fuel supply amount and the combustion air supply amount, so that the heat emission amount is not particularly increased. However, in the case of a low load where the combustion amount is changed between low combustion and stop, if the inside of the furnace is ventilated every time combustion starts and stops, the heat in the furnace is discharged by ventilating the inside of the furnace. Therefore, the amount of heat loss has increased and the boiler efficiency has been reduced.
[0004]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to prevent the efficiency of the boiler from being lowered even at a low load so that high efficiency operation can be performed.
[0005]
Combustion device having a fuel supply amount adjusting means and a combustion air supply amount adjusting means, and determining the combustion amount of the combustion device according to the combustion device capable of adjusting the combustion amount and the steam pressure value detected by the pressure detection device An operation control device is provided, and during operation, the boiler controls the combustion amount of the combustion device so that the combustion amount determined by the operation control device is obtained. The operation control device performs combustion at the rated combustion amount of the combustion device. Combustion with high combustion, medium combustion that burns at about half the amount of high combustion, combustion amount that is even smaller than medium combustion and does not increase steam pressure The combustion amount is determined at three positions of low combustion, the fuel supply amount and the combustion air supply amount are set for each combustion amount , and the burner has a normal combustion portion that performs high combustion and medium combustion, and a low combustion that performs low combustion. Combustion section is provided and burns to the normal combustion section A normal blower path that transmits a use air, may be provided separately low combustion air passage for sending air for combustion to the low combustion combustion section, during boiler operation, without stopping the combustion, high combustion, medium combustion Combustion is performed at either low combustion, and combustion air is supplied only from the low combustion air passage during low combustion.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
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 burner 2 that generates a downward flame is provided at the upper part of the boiler, and the flame is burned in a combustion chamber 3 in the center of the boiler. The burner 2 includes a normal combustion section 5 that performs high combustion or medium combustion, and a low combustion combustion section 6 that performs low combustion. The combustion air used in the burner 2 is supplied by the blower 10. The blower 10 and the burner 2 are connected by an air passage, and the air passage sends the combustion air to the normal air passage 7 for sending the combustion air to the normal combustion section 5 of the burner and the combustion section 6 for the low combustion. A low combustion air passage 8 is provided. The normal air passage 7 is provided with an air volume adjusting device 15, and the air volume sent to the normal combustion unit 5 is adjusted by the air volume adjusting device 15.
[0007]
The fuel supply pipe 4 for supplying fuel to the burner 2 is branched into three systems in the middle, and a low combustion fuel valve 12, a middle combustion fuel valve 13, and a high combustion fuel valve 14 are respectively provided at the branched portions. Provide. The fuel supply pipe provided with the low combustion fuel valve 12 supplies fuel toward the low combustion combustion section 6, and the fuel supply pipe provided with the middle combustion fuel valve 13 and the high combustion fuel valve 14 are provided. The provided fuel supply pipe supplies fuel to the normal combustion unit 5.
[0008]
In the flame combustion part, a normal flame detection device 16 for detecting the presence or absence of a flame in the normal combustion unit 5 and a low combustion flame detection device 17 for detecting the presence or absence of a flame in the low combustion combustion unit 6 are provided. The boiler supplies water from the lower water supply pipe, takes out the steam from the upper steam pipe 9 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. Connected to each of the pressure detection device 1, the blower 10, the low combustion fuel valve 12, the middle combustion fuel valve 13, the high combustion fuel valve 14, the air volume adjustment device 15, the normal flame detection device 16, and the low combustion flame detection device 17. The operation control device 11 is provided.
[0009]
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, high combustion is performed at the rated combustion amount of the burner 2, and when the steam pressure value is higher than the upper limit pressure, it is 10% of the rated fuel amount at the burner 2. If the combustion is low combustion, and the steam pressure value is an intermediate value, the combustion is set to 50% of the rated combustion amount of the burner 2 and the middle combustion is performed. The fuel supply amount and the combustion air supply amount for each combustion amount are also set, 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.
[0010]
The fuel supply amount is 100% when the low combustion fuel valve 12, the middle combustion fuel valve 13, and the high combustion fuel valve 14 are all opened, and the high combustion fuel supply amount is 100%. In each fuel supply pipe, the fuel supply amount for medium combustion is 50% when the fuel valve 13 is opened, and the fuel supply amount is 10% when only the low combustion fuel valve 12 is opened. Set the fuel supply amount. As for the combustion air supply amount, when the blower 10 is operated and the air volume adjusting device 15 is set to a high combustion opening, the high combustion air supply amount is 100%, and the air flow adjusting device 15 is set to the medium combustion opening. In this case, the medium combustion air supply amount is 50%, and the low combustion air supply amount is 10% when the air flow control device 15 is fully closed.
[0011]
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. When a boiler operation switch (not shown) is turned on, the operation control device 11 starts operation of the boiler. When starting combustion of the boiler, it is necessary to perform pre-purge to ventilate the furnace before starting combustion. The operation control device 11 operates the blower 10 while the supply of fuel is stopped, and the air volume control device 15 is fully opened, whereby pre-purge air is introduced into the furnace for a certain period of time to perform ventilation.
[0012]
The operation control device 11 confirms that the normal flame detection device 16 and the low combustion flame detection device 17 have not detected a flame, and starts combustion from low combustion regardless of the steam pressure value. After the completion of the pre-purge, the air volume control device 15 is fully closed, and combustion air is supplied to the burner 2 only from the low combustion air passage 8. An ignition device (not shown) provided in the low combustion combustion section 6 is operated to open the low combustion fuel valve 12 and supply fuel. The low combustion fuel and air are supplied to the low combustion combustion section 6 of the burner 2, and a low combustion flame is generated in the low combustion combustion section 6.
[0013]
The low combustion flame is detected by the low combustion flame detection device 17, and the signal is sent to the operation control device 11. If the operation control device 11 fails to receive a flame presence signal after a certain period of time has elapsed from the ignition process, it determines that the ignition is abnormal and stops the operation of the boiler, and receives a flame presence signal. If so, it is judged normal and the process proceeds to the next step.
[0014]
The operation control device 11 determines the combustion amount from the steam pressure value detected by the pressure detection device, and performs combustion at the determined combustion amount. When the steam pressure value is lower than the value at which the medium combustion is performed, the operation control device 11 sets the air volume adjusting device 15 to the medium combustion opening (half open) and opens the medium combustion fuel valve 13. When fuel and air are supplied to the normal combustion section 5 of the burner 2, the flame of the low combustion combustion section 6 spreads to the normal combustion section 5 and the burner 2 performs medium combustion.
[0015]
The normal flame detection device 16 detects the flame of the normal combustion portion 5 and sends a signal to the operation control device 11. In the operation control device 11, if a signal indicating that there is a flame in the normal combustion unit 5 cannot be received even after a lapse of a certain time from the shift to the middle combustion, it is determined that the combustion is abnormal and the operation of the boiler is performed. If a signal with a flame is received, it is judged normal and combustion continues.
[0016]
When the steam pressure value is lower than the value at which high combustion is performed, the operation control device 11 sets the air volume adjusting device 15 to a high combustion opening (fully open) and also opens the high combustion fuel valve 14. As a result, the amount of fuel and air supplied to the normal combustion unit 5 increase, and the combustion amount in the normal combustion unit 5 increases, resulting in high combustion. The operation control device 11 subsequently controls combustion at three positions of high combustion, medium combustion, and low combustion in accordance with the steam pressure value, and the fuel supply amount and the combustion air supply amount correspond to the respective combustion amounts. Control the amount.
[0017]
In the case of low combustion, the steam pressure is not increased because there is only a combustion amount that keeps the inside of the furnace warm. For this reason, the steam pressure value is reduced by the use of steam, and then medium combustion is performed. However, since the change from the low combustion to the middle combustion can be performed only by changing the fuel amount and the air amount, it is not necessary to perform the pre-purge as in the case of igniting from the combustion stop. For this reason, low combustion is a combustion amount that does not increase the steam pressure, and a combustion amount that can perform proper combustion (about 5% to 30% of high combustion), so that the inside of the furnace during the operation of the boiler Ventilation will no longer occur and no heat loss will occur due to ventilation.
[0018]
Since an amount of air suitable for each combustion amount is supplied, even if the combustion amount is low and the combustion amount is low, incomplete combustion does not occur and a large amount of CO is not generated. It is also possible to do this. In addition, since the flame detection of the normal combustion part 5 and the low combustion part 6 is performed independently, and the flame is detected by the respective flame detection devices, abnormalities during ignition and combustion transition Each time abnormality can be detected, and the safety can be improved.
[0019]
【The invention's effect】
By carrying out the present invention, ventilation in the furnace is not performed during operation of the boiler, heat can be prevented from being exhausted by ventilation, and the efficiency of the boiler can be prevented from being lowered. It becomes possible to drive.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a boiler implementing the present invention.
DESCRIPTION OF SYMBOLS 1 Pressure detection apparatus 2 Burner 3 Combustion chamber 4 Fuel supply piping 5 Normal combustion part 6 Low combustion combustion part 7 Normal air passage 8 Low combustion air path 9 Steam pipe 10 Blower 11 Operation control device 12 Low combustion fuel valve 13 Medium combustion fuel valve 14 High combustion fuel valve 15 Air flow control device 16 Normal flame detection device 17 Low combustion flame detection device

Claims (2)

Combustion device having a fuel supply amount adjusting means and a combustion air supply amount adjusting means, and determining the combustion amount of the combustion device according to the combustion device capable of adjusting the combustion amount and the steam pressure value detected by the pressure detection device An operation control device is provided, and during operation, the boiler controls the combustion amount of the combustion device so that the combustion amount determined by the operation control device is obtained. The operation control device performs combustion at the rated combustion amount of the combustion device. Combustion with high combustion, medium combustion that burns at about half the amount of high combustion, combustion amount that is even smaller than medium combustion and does not increase steam pressure The combustion amount is determined at three positions of low combustion, the fuel supply amount and the combustion air supply amount are set for each combustion amount , and the burner has a normal combustion portion that performs high combustion and medium combustion, and a low combustion that performs low combustion. Combustion section is provided and burns to the normal combustion section A normal blower path that transmits a use air, may be provided separately low combustion air passage for sending air for combustion to the low combustion combustion section, during boiler operation, without stopping the combustion, high combustion, medium combustion A boiler for performing continuous combustion, characterized in that combustion is performed at any one of low combustion, and combustion air is supplied only from a low combustion air passage during low combustion . The boiler for continuous combustion according to claim 1, wherein a flame detection device for detecting high-combustion and medium-combustion flames and a flame detection device for detecting low-combustion flames are provided, respectively, A boiler that performs continuous combustion, characterized by detecting a low-combustion flame independently.

Images