JP7074337B2 - Combustion device that detects vibration combustion - Google Patents

Description

The present invention is a combustion device that adjusts the combustion amount by adjusting the supply amounts of combustion air and fuel gas, and detects vibration combustion when vibration combustion occurs when the combustion amount is changed. It is about the combustion device to be performed.

As described in Japanese Patent Application Laid-Open No. 11-37456, vibration combustion may occur in a combustion device due to pressure fluctuation due to a combustion reaction. When oscillating combustion occurs, large pressure fluctuations repeatedly occur in the combustion chamber in a short time. When a pressure fluctuation occurs in the combustion chamber, the pressure fluctuation propagates in the air passage that sends the combustion air to the combustion chamber. Therefore, the occurrence of vibration combustion can be detected.

Since large pressure fluctuations occur in a short time during vibration combustion, the pressure in the ventilation path is detected by the blower path pressure detector, and vibration combustion occurs when the fluctuation range within a predetermined time exceeds the set value. It can be determined that it is. In the judgment of vibration combustion, the pressure at the moment is detected at regular intervals, the difference between the maximum value and the minimum value of the detected pressure within the set time is calculated, and when the difference value exceeds the set value, It can be determined that vibration combustion is occurring.

However, in the case of a combustion device in which the combustion amount is adjusted by adjusting the combustion air supply amount and the fuel gas supply amount, the pressure in the air passage also changes depending on the combustion amount. When the combustion amount is set in stages such as high combustion and low combustion, the difference in combustion amount is set large, such as setting the turndown, which is the ratio of the minimum and maximum combustion amount of the combustion device, to 1: 7. Sometimes.

When the fuel gas supply amount and the combustion air supply amount are increased to increase the combustion amount, the amount of combustion air flowing in the ventilation path increases, and the furnace pressure in the combustion chamber also increases. Therefore, even if the difference between the maximum value and the minimum value of the pressure detected within a certain period of time is calculated, it is not possible to distinguish whether the difference is due to a change in the amount of combustion or vibrational combustion. Therefore, the vibration combustion is not determined during the change of the combustion amount, and the vibration combustion is determined based on the wind pressure value detected after the change of the combustion amount is completed. However, vibration combustion may occur while changing the combustion amount. In that case, if the occurrence of vibration combustion is determined after waiting for the end of the combustion amount change, the detection of vibration combustion will be delayed, and during that time. Has a problem that the vibration combustion is continued and the time during which the vibration combustion is generated becomes long.

Japanese Unexamined Patent Publication No. 11-37456

The problem to be solved by the present invention is
It is a combustion device that adjusts the combustion amount by adjusting the combustion air supply amount and the fuel gas supply amount, and if vibration combustion occurs while changing the combustion amount, the vibration combustion occurs earlier. It provides a combustion device that can be detected.

The invention according to claim 1 is a combustion device having a blower for sending combustion air and a fuel gas supply pipe for passing fuel gas, and combusting while supplying combustion air and fuel gas, wherein the combustion air is used. In the combustion device that can change the combustion amount by adjusting the supply amount of fuel gas, a blow path pressure detector that detects the wind pressure in the blow path is installed in the middle of the blow path that sends the combustion air. If it is detected that the wind pressure value detected by the blower path pressure detector is opposite to the direction of the combustion amount change during the change of the combustion amount, it is determined that vibration combustion may have occurred. It is characterized in that it is to perform.

According to the second aspect of the present invention, in the combustion apparatus for detecting the vibration combustion, the wind pressure is based on the wind pressure value detected after the wind pressure value in which the change in the wind pressure opposite to the combustion amount changing direction is detected. The maximum value and the minimum value of the value are calculated, and when the difference between the maximum value and the minimum value of the calculated wind pressure value exceeds the set value, it is determined that vibration combustion is occurring. It is characterized by that.

The invention according to claim 3 is the maximum from the wind pressure value data detected after the wind pressure value in which the change in the wind pressure opposite to the combustion amount change direction is detected in the combustion device for detecting the vibration combustion. The maximum value and the minimum value of the remaining data excluding the value and the minimum value are calculated, and if the difference between the maximum value and the minimum value of the calculated wind pressure value exceeds the set value, vibration combustion occurs. It is characterized in that it is determined to be present.

According to the fourth aspect of the present invention, in the combustion device for detecting the vibration combustion, the wind pressure value used for calculating the maximum value and the minimum value for determining the occurrence of the vibration combustion is the maximum within the set time for movement. Although the value and the minimum value are used, the maximum and minimum values of the wind pressure value are calculated without waiting until the number of detected wind pressure values reaches the set time, and the difference between the maximum value and the minimum value is the set value. When it exceeds the limit, it is determined that vibration combustion is occurring.

By implementing the present invention, it becomes possible to detect the occurrence of oscillating combustion even while the combustion amount is being changed, and by detecting and responding to oscillating combustion at an early stage, the time for oscillating combustion to continue can be shortened. Can be done.

Flow chart of the combustion apparatus carrying out the present invention Explanatory diagram of pressure transition in the air flow path Explanatory drawing of air flow path pressure detection during vibration combustion Explanatory drawing of air passage pressure detection during vibration combustion in other examples

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flow chart of a combustion device for carrying out the present invention, FIG. 2 is an explanatory diagram of a pressure transition in a blower path, and FIG. 3 is an explanatory view of a pressure detection status of a blower path during oscillating combustion. The burner 2 burns by mixing the fuel gas supplied through the fuel gas supply pipe 8 and the combustion air supplied from the blower 6 through the air passage 1. The fuel gas supply amount and the combustion air supply amount are adjusted so as to have a constant ratio, and the combustion amount is changed by increasing or decreasing the fuel gas supply amount and the combustion air supply amount. To adjust the combustion amount, a fuel supply control valve 4 for controlling the fuel gas supply amount is installed in the middle of the fuel gas supply pipe 8, and the rotation speed of the blower 6 is adjusted to the blower 6 by changing the supply power supply frequency. An inverter device 5 to be adjusted is installed, and the fuel supply amount and the combustion air supply amount are adjusted.

The operation control of the combustion device is performed by the operation control device 7 with the operation control device 7 installed. The operation control device 7 is connected to the fuel supply control valve 4 and the inverter device 5 to control the operation of the fuel supply control valve 4 and the inverter device 5. Further, a blower path pressure detecting device 3 for detecting the wind pressure of the combustion air supplied from the blower 6 is installed in the blower path 1. The blow path pressure detection device 3 is also connected to the operation control device 7, and the value of the wind pressure detected by the blow path pressure detection device 3 is input to the operation control device 7.

FIG. 2 shows the wind pressure in the air passage 1. FIG. 2 shows the wind pressure before and after changing the combustion amount from low combustion to high combustion. The case of normal combustion is shown by a broken line, and the wind pressure in the case of vibration combustion is shown. It is shown by a solid line. The oscillating combustion started in the middle of the change of the combustion amount, and the two lines overlapped until then, but after the oscillating combustion started, it is divided into two.

When the amount of combustion increases, the amount of combustion air supplied from the blower 6 to the burner 2 increases, and the pressure in the combustion chamber where the burner 2 burns also increases, so that the wind pressure in the air passage 1 increases. First, focusing on the wind pressure when vibration combustion does not occur in FIG. 2, when the combustion amount is changed, the wind pressure uniformly rises from the wind pressure at the time of low combustion to the wind pressure at the time of high combustion. If the fuel supply amount is increased or decreased in stages, the wind pressure will fluctuate at the timing of changing the fuel supply amount, but when the combustion amount is changed by changing the combustion air and fuel gas proportionally. The wind pressure changes linearly.

The air passage pressure detection device 3 that detects the pressure in the air passage 1 detects the wind pressure at each moment at regular intervals and outputs the wind pressure to the operation control device 7. The wind pressure at each moment detected by the blower path pressure detection device 3 is the wind pressure detected at one time point and the next time point when the amount of combustion is increasing while normal combustion is being performed. Comparing the wind pressures detected in, the wind pressures increase with the passage of time, so the detected wind pressure values should increase. In the operation control device 7, when the wind pressure continues to change in the direction of changing the combustion amount, it can be determined that the vibration combustion has not occurred.

Next, in FIG. 2, attention is paid to the wind pressure when oscillating combustion occurs from the middle of changing the combustion amount. The wind pressure before the vibration combustion occurs is the same as the case where the vibration combustion does not occur, the wind pressure increases with the passage of time, and the wind pressure does not decrease in the middle of the increase in the combustion amount. However, if vibration combustion starts in the middle of changing the combustion amount, a large wind pressure fluctuation occurs in a short cycle during vibration combustion. When vibration combustion occurs while the amount of combustion is increasing, the median value of the wind pressure increases, but the wind pressure value at the moment touches up and down greatly from the median value. The wind pressure value in the air passage 1 detected by the air flow path pressure detection device 3 in the state where vibration combustion is occurring while the combustion amount is increasing is the wind pressure fluctuation due to the vibration combustion when comparing the previous value and the current value. Since this is larger than the wind pressure fluctuation due to the increase in combustion amount, a value lower than the previous wind pressure may be detected in the instantaneous wind pressure.

The operation control device 7 monitors the wind pressure in the air passage 1, and indicates that the detected wind pressure value of the air passage 1 has decreased even though the amount of combustion is increasing. When it is detected, it is determined that vibration combustion may occur. In the operation control device 7, it may be determined that vibration combustion has occurred at this stage, but since there is a possibility that the detection of this measured value is abnormal, the determination of vibration combustion occurrence is performed here. It is not, and the vibration combustion is monitored as there is a possibility of vibration combustion. After that, the operation control device 7 accumulates the wind pressure values in the air passage detected by the air passage pressure detection device 3, and calculates the difference between the maximum value and the minimum value of the wind pressure detected within the set time. If the difference between the calculated maximum value and the minimum value is larger than the set value, it is determined that vibration combustion has occurred.

FIG. 3 shows the wind pressure detection status by the blower path pressure detection device in the situation where vibration combustion is occurring. As shown in FIG. 3, the wind pressure is detected by the blower path pressure detecting device 3 at intervals such as every second, and the wind pressure value within a predetermined time detected a plurality of times is measured. Record and determine the occurrence of oscillating combustion based on the value. In the figure, the wind pressure value is detected every second, and the wind pressure is detected at each point from time T0 to time T4. The value of the wind pressure detected at time T0 is defined as wind pressure P0, and the wind pressure value at time T1 is wind pressure P1, wind pressure P2 at time T2, wind pressure P3 at time T3, and wind pressure P4 at time T4. At the stage of time T0, the oscillating combustion is in the state before the occurrence, and the wind pressure increases due to the increase in the combustion amount, but the large wind pressure fluctuation due to the oscillating combustion does not occur. The oscillating combustion occurs between the time T0 and the time T1, and the wind pressure fluctuates greatly during the oscillating combustion. Here, since vibration combustion occurs while the amount of combustion is increasing, the wind pressure fluctuates greatly in a short cycle, and the median value of the wind pressure tends to increase.

Here, when the wind pressure P0 at the time T0 and the wind pressure P1 at the time T1 are compared, the wind pressure P1 is lower. When the amount of combustion is increased, the wind pressure should normally increase with the passage of time, but since the wind pressure P1 is lower than the wind pressure P0, it is considered that vibration combustion may occur. be able to.

The wind pressure detected by the blower path pressure detecting device 3 is detected at relatively long intervals such as every second, and the cycle of pressure fluctuation due to oscillating combustion is a short cycle of 5 times or more per second. The wind pressure value at the time of detection by the blower path pressure detecting device 3 is somewhere in the fluctuation range that greatly fluctuates, and the wind pressure value differs depending on the timing of detecting the wind pressure. In FIG. 3, the wind pressure P1 at the time of time 1 is low, but it is possible to detect the value of the wind pressure P1'near the peak of the wind pressure that fluctuates greatly, for example, due to a slight difference in the detection timing. .. In this case, since the value of the wind pressure P1'is higher than the wind pressure P0, it means that the vibration combustion cannot be detected at this point. However, even in this case, at the time T2, which is the next wind pressure detection timing, there is a high possibility that a value smaller than the wind pressure P1'where a high value was detected will be detected. When vibration combustion does not occur, it is very unlikely that wind pressure fluctuations that go against the direction of change in combustion amount will occur, but on the other hand, if vibration combustion occurs, the combustion amount will change. There is a possibility that wind pressure fluctuations that go backward in the direction will be detected, and it is less likely that vibration combustion is occurring but only those whose wind pressure is changing in the same direction are detected. Therefore, it is possible to estimate the presence or absence of oscillating combustion depending on whether or not the wind pressure that goes against the changing direction of the combustion amount is detected.

However, if it is determined that vibration combustion has occurred only once when the wind pressure value that goes against the direction of changing the combustion amount is detected, if an abnormality occurs in the measurement of the wind pressure value and the measured value becomes abnormal, it is mistakenly regarded as vibration combustion. May be detected. In order to prevent this erroneous detection, it is possible to improve the determination accuracy of the vibration combustion by detecting a plurality of wind pressure values at regular time intervals and detecting the width in which the wind pressure value changes to determine the vibration combustion. In that case, when a value whose wind pressure value goes against the change in combustion amount is detected, the maximum and minimum values of the wind pressure value detected within the specified period after excluding that value are extracted and the difference is set. When the value is exceeded, it is determined that vibration combustion has occurred.

As the wind pressure value used for determining the vibration combustion, the maximum value and the minimum value within the set time of moving are used. Then, the difference between the maximum value and the minimum value is calculated by calculating the maximum value and the minimum value while the wind pressure value is detected even if the set time has not been reached, and the difference between the maximum value and the minimum value is set. If the value is exceeded, it is determined that vibration combustion is occurring.

A specific description will be given with reference to FIG. When it is detected that the wind pressure P1 at the time T1 is lower than the wind pressure P0 at the time T0, it is considered that the vibration combustion has occurred, so the vibration combustion is confirmed. However, the value of the wind pressure P1 may be lower than the wind pressure P0 due to the wrong value of the wind pressure P1 detected here, and if the value of the wind pressure P1 is significantly smaller in that case, the following Even if the value of the wind pressure P2 is not high, the difference between the wind pressure P1 and the wind pressure P2 becomes a very large value, and it is determined that the vibration combustion is generated by this difference. Therefore, the value of the wind pressure P1 is not used for the determination of the vibration combustion, and the determination is made based on the value after the next wind pressure P2.

When the wind pressure P3 is detected at the time T3, the maximum value and the minimum value are taken out from the wind pressure P2 and the wind pressure P3. If the wind pressure value for calculating the maximum value and the minimum value is the maximum value and the minimum value in 10 seconds of moving, the maximum value and the minimum value between the time T2 and the time T11 are obtained from the time T2 to the time T11. However, the determination of oscillating combustion starts from the time when two wind pressure values are detected. Here, there are only two values, the wind pressure P3 is the maximum value, the wind pressure P2 is the minimum value, and the difference between the maximum value and the minimum value is detected. If the difference between the maximum value and the minimum value exceeds the set value, it is determined that oscillating combustion is occurring. If the difference between the wind pressure P3 and the wind pressure P2 does not exceed the set value, it is not determined that oscillating combustion is occurring at this stage. After that, when the wind pressure P4 is detected at the time T4, the maximum value and the minimum value are calculated from the three points of the wind pressure P2 and the wind pressure P4. When the maximum value is the wind pressure P4 and the minimum value is the wind pressure P2, the difference between the maximum value and the minimum value is calculated. Here, when the difference between the wind pressure P4 and the wind pressure P2 exceeds the set value, the operation control device 7 determines that vibration combustion has occurred.

When it is determined that the vibration combustion is occurring, the operation control device 7 performs an operation for eliminating the vibration combustion. When oscillating combustion occurs, the combustion is temporarily stopped, and when it is restarted, the oscillating combustion will be subsided in many cases. In addition, as a factor that causes vibration combustion, the injection amount of combustion air becomes large and the flame lifts from the combustion surface, which may occur when the combustion start point shifts. Therefore, reducing the combustion amount is also possible for vibration combustion. Effective for repair. Therefore, when vibration combustion occurs, the operation control device 7 reduces the amount of combustion by reducing the fuel supply amount and the combustion air supply amount, or stops the fuel supply to stop the combustion, and then restarts the combustion. By doing this, vibration combustion is eliminated.

By doing so, it is possible to detect the occurrence of oscillating combustion even when the amount of combustion is changed, and it is possible to take measures against oscillating combustion. Since it is possible to respond to the vibration combustion at an earlier stage than when the vibration combustion is determined after the change of the combustion amount is completed, the time during which the vibration combustion is performed can be shortened.

In the above embodiment, the vibration combustion is detected in the state where the combustion amount is increased, but the vibration combustion can be detected even in the state where the combustion amount is decreased. In a state where the amount of combustion is decreasing, the wind pressure value detected by the blower path pressure detecting device 3 tends to decrease due to the decrease in the amount of air supplied for combustion and the decrease in the furnace pressure in the combustion chamber. In this case as well, when vibration combustion occurs, the occurrence of vibration combustion is suspected when a value is detected in which the wind pressure value, which normally continues to decrease, reverses and increases on the way. In this case as well, in order to prevent erroneous detection of oscillating combustion due to an abnormality in the detected value, the wind pressure after that is recorded except for the wind pressure value at which the reverse value was detected first, and the recorded wind pressure is recorded. By determining the occurrence of oscillating combustion based on the difference between the maximum value and the minimum value, oscillating combustion can be detected reliably and early.

FIG. 4 is an explanatory diagram of the air passage pressure detection status at the time of vibration combustion in another embodiment. The difference from the embodiment of FIG. 3 is the remaining data obtained by removing the maximum value and the minimum value from the wind pressure value data detected after the wind pressure value in which the change in the wind pressure opposite to the combustion amount change direction is detected. The maximum value and the minimum value are calculated, and when the difference between the maximum value and the minimum value of the calculated wind pressure value exceeds the set value, it is determined that vibration combustion is occurring.

Also in FIG. 4, when it is detected that the wind pressure P1 at the time T1 is lower than the wind pressure P0 at the time T0, it is considered that the vibration combustion is occurring, so the vibration combustion is confirmed. However, the value of the wind pressure P1 may be lower than the wind pressure P0 due to the wrong value of the wind pressure P1 detected here, and if the value of the wind pressure P1 is significantly smaller in that case, the following Even if the value of the wind pressure P2 is not high, the difference between the wind pressure P1 and the wind pressure P2 becomes a very large value, and it is determined that the vibration combustion is generated by this difference. Therefore, the value of the wind pressure P1 is not used for the determination of the vibration combustion, and the determination is made based on the value after the next wind pressure P2.

When the wind pressure P3 is detected at the time T3, the maximum value and the minimum value are taken out from the wind pressure P2 and the wind pressure P3. If the wind pressure value for calculating the maximum value and the minimum value is the maximum value and the minimum value in 10 seconds of moving, the maximum value and the minimum value between the time T2 and the time T11 are obtained from the time T2 to the time T11. However, the determination of oscillating combustion starts from the time when two wind pressure values are detected. At the time of time T3, there are only two detected wind pressure values, the wind pressure P3 is the maximum value, and the wind pressure P2 is the minimum value. In the embodiment of FIG. 4, the maximum value and the minimum value detected here are not used for the determination of the vibration combustion, and the vibration combustion is determined from the maximum value and the minimum value in the other wind pressure value data. Vibration combustion is not determined at this stage. After that, when the wind pressure P4 is detected at the time T4, the maximum value and the minimum value are calculated from the three points of the wind pressure P2 and the wind pressure P4. Since the maximum value is the wind pressure P4 and the minimum value is the wind pressure P2, the maximum value and the minimum value are calculated from the remaining wind pressure values excluding the wind pressure P4 and the wind pressure P2. Here, since the remaining value is only the wind pressure P3 and there is no difference between the maximum value and the minimum value, it is not determined that oscillating combustion is occurring.

When the time T5 is reached and the wind pressure P5 at that time is detected, the maximum value and the minimum value are calculated from the four points of the wind pressure P5 from the wind pressure P2. Since the maximum value is the wind pressure P4 and the minimum value is the wind pressure P2, the maximum value and the minimum value are calculated from the remaining wind pressure values excluding the wind pressure P4 and the wind pressure P2. The maximum value of the remaining values is the wind pressure P5, the minimum value is the wind pressure P3, and the difference between the maximum value and the minimum value is calculated. Here, when the difference between the wind pressure P3 and the wind pressure P5 exceeds the set value, the operation control device 7 determines that vibration combustion has occurred.

It should be noted that the present invention is not limited to the embodiments described above, and many modifications can be made by a person having ordinary knowledge in the art within the technical idea of the present invention.

1 Blower
2 Burner 3 Blower path pressure detector 4 Fuel supply control valve 5 Inverter device 6 Blower 7 Operation control device 8 Fuel gas supply piping

Claims (4)

It is a combustion device that has a blower that sends combustion air and a fuel gas supply pipe that passes fuel gas, and burns while supplying combustion air and fuel gas, and regulates the supply amount of combustion air and fuel gas. In the combustion device that enables the change of the combustion amount, a blow path pressure detection device that detects the wind pressure in the blow path is installed in the middle of the blow path for sending the combustion air, and the combustion amount is being changed. When it is detected that the wind pressure value detected by the blower path pressure detector is opposite to the direction of changing the combustion amount, it is determined that vibration combustion may have occurred. A combustion device that detects vibration combustion. In the combustion device for detecting vibration combustion according to claim 1, the maximum value of the wind pressure value is based on the wind pressure value detected after the wind pressure value in which the change in the wind pressure opposite to the combustion amount change direction is detected. When the difference between the maximum value and the minimum value of the calculated wind pressure value exceeds the set value, it is determined that vibration combustion is occurring. A combustion device that detects vibrational combustion. In the combustion device for detecting the vibration combustion according to claim 1, the maximum value and the minimum value are obtained from the wind pressure value data detected after the wind pressure value in which the change in the wind pressure opposite to the combustion amount change direction is detected. The maximum and minimum values of the remaining data after excluding are calculated, and if the difference between the maximum and minimum values of the calculated wind pressure value exceeds the set value, it is determined that vibration combustion is occurring. A combustion device that detects vibrational combustion, which is characterized by the fact that it is performed. In the combustion device that detects vibration combustion according to claim 2 or 3, the wind pressure value used for calculating the maximum value and the minimum value for determining the occurrence of vibration combustion is the maximum value and the minimum value within the set time for movement. Although it is a value, the maximum and minimum values of the wind pressure value are calculated without waiting until the number of detected wind pressure values reaches the set time, and vibration occurs when the difference between the maximum value and the minimum value exceeds the set value. A combustion device that detects vibrational combustion, which is characterized in that it determines that combustion is occurring.

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