JP2013257056A - Multi-can installed boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out self-check without disturbing steam supply, in a boiler of carrying out the self-check for confirming soundness of a flame detecting part, by stopping tentatively combustion, when a continuous combustion time gets long, to confirm whether no flame is correctly detected or not.SOLUTION: In a multi-can installed boiler of controlling a can number for combustion by a can number control device 2, the can number control device 2 is set to carry out self-check when reaching a time set in a time zone capable of securing a standby can (boiler having a margin for increasing a combustion quantity), operation priority orders of self-checking objective boilers are sequentially brought down into a subordinate position, when carrying out the self-check, the standby can is allocated to an order more superordinate than the operation priority order after brought down, and the self-check is carried out under this state.

Description

  The present invention relates to a multi-can installation boiler in which a plurality of boilers are installed and a required number of boilers are burned according to a load.

  Multi-can boilers that are composed of a plurality of boilers and a unit control device that outputs an operation command to each boiler and that burns the required number of boilers according to the steam load are widely used. In a multi-can installation boiler, the operation priority is set for each boiler, and the required number of boilers are burned in order from the boiler with the highest operation priority. If the combustion amount of the boiler is set in stages such as high combustion, low combustion, and stop, the number of units with the highest operating priority is high combustion, and the number of units with the next priority is low combustion The remaining amount of combustion is performed by, for example, stopping the combustion. In this case, boilers with higher operating priority have more opportunities to burn, and if combustion concentrates on a specific boiler, the life of the entire system will be shortened. Thus, the combustion time of each boiler is averaged.

  Further, as described in Japanese Utility Model Registration No. 2505285, when the continuous combustion time is long in the boiler, the combustion of the flame detection unit including the flame detection device and the combustion circuit is stopped by temporarily stopping the combustion. A self-check is performed to confirm the sex. Boilers are extremely dangerous if they continue to inject fuel with the flames extinguished, so install a flame detector and inject fuel while confirming that there is a flame. When the flame disappears during combustion, safety is ensured by stopping fuel injection. However, this requires that the flame detection device and the combustion circuit are operating normally. Even if an abnormality has occurred in the flame detection device and the combustion circuit, in the case of an abnormality that makes a misjudgment that there is no flame when there is a flame, the operation of the boiler is stopped in order to stop the boiler operation with an output without flame. Although the rate drops, safety can be secured. However, when an abnormality that erroneously determines that there is a flame occurs when there is no flame, it cannot be detected even if the flame has disappeared, and safety cannot be ensured. An abnormality that erroneously determines that there is a flame when there is no flame can be detected with combustion stopped. Since there is no flame while combustion is stopped, if an output with a flame is performed at that time, it can be determined that an abnormality has occurred in the flame detector. However, depending on the installation environment of the boiler, it may burn continuously for a long time, and in a boiler that does not have an opportunity to stop the combustion, it is impossible to detect an abnormality in flame detection. Although the deterioration of detection accuracy gradually progresses, safety cannot be ensured because the ability cannot be confirmed for many days, so the confirmation interval is determined not to exceed 24 hours.

  For this reason, in a boiler in which the continuous combustion time becomes long, self-check is performed to confirm the function of the flame detection unit including the flame detection device and the combustion circuit by forcibly stopping the combustion. A time when the required amount of steam is relatively low, such as midnight, is set, and when the set time arrives every day, even if the boiler is burning, the combustion is temporarily stopped and a self-check is performed to check the function of the flame detection equipment. By doing in this way, continuous combustion time does not become 24 hours or more, and the capability check of a flame detection part can be performed every day. Alternatively, the continuous combustion time may be measured and the self-check may be performed every time the continuous combustion time reaches a predetermined time. Every time the continuous combustion time becomes 23 hours 59 minutes, the combustion is temporarily stopped and the function of the flame detection unit is checked, so that the flame detection unit is checked every day.

  By the way, it is a boiler that performs long-term continuous combustion that requires a self-check to stop combustion for safety confirmation. That is, among the boilers installed in multiple cans, the combustion that is particularly necessary for combustion is stopped for self-checking. For this reason, there has been a problem that steam supply may be insufficient due to the combustion stop of the boiler and the steam pressure may decrease.

Utility Model Registration No. 2505285

  The problem to be solved by the present invention is that when the continuous combustion time becomes long, the combustion is temporarily stopped, and it is confirmed whether the flame can be correctly detected. In a boiler that performs self-checks to be confirmed, the self-check can be performed without hindering steam supply.

  It consists of a plurality of boilers with operating priorities and a unit control device that outputs operation commands to each boiler. The unit control unit is a combustion command for the required number of boilers from the boilers with high operating priorities. Each boiler is a multi-can boiler that receives a combustion command and performs combustion, and detects the presence or absence of flame in a state where the combustion is temporarily stopped in each boiler. In multi-can installation boilers that perform self-checks to determine abnormalities, the unit control device should perform self-checks at the time set in a time zone in which spare cans can be secured. In addition, lower the operation priority of the boilers subject to self-check sequentially, and assign a spare can to a higher rank than the lowered operation priority Multi cans installed boiler is characterized in that it is intended to perform a self-check in that state.

  By carrying out the present invention, it is possible to check the soundness of the flame detection unit without causing a shortage of the steam supply amount when performing the self-check for temporarily stopping the combustion.

Explanatory drawing of the boiler installation situation in one Example of this invention Explanatory drawing of the boiler operation state in one Example of this invention Flowchart of self-check control in one embodiment of the present invention

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a boiler installation state in one embodiment of the present invention, FIG. 2 is an explanatory diagram of a boiler operation state in one embodiment of the present invention, and FIG. 3 is a flowchart of self-check control in one embodiment of the present invention. is there. In this embodiment, five boilers from boiler A to boiler E are installed in parallel. Steam piping from each boiler is connected to the steam header 4 and a steam pressure detecting device 3 is provided at the steam collecting portion. The operation command for each boiler 1 is output from the number control device 2 connected to each boiler, and the number control device 2 is also connected to the steam pressure detection device 3. The boiler controls the amount of combustion at three positions of high combustion, low combustion, and stop, and controls the amount of steam generated by controlling the amount of combustion in the entire boiler.

Each boiler 1 is provided with a boiler operation control device 5, and the boiler operation control device 5 is connected to the number control device 2 through a signal line. The number control device 2 calculates the required combustion amount of the entire boiler based on the steam pressure value detected by the steam pressure detection device 3, and outputs a combustion command to the required number of boilers. Prioritize the operation priority for each boiler, and when the steam pressure value decreases, increase the number of combustion by changing the combustion command in order from the boiler with the highest operation priority, or change from low combustion to high combustion Increase the amount of combustion. And if the steam pressure value rises and the required combustion amount decreases, the combustion stop command is output in order from the boiler with the lower priority of operation to decrease the number of combustion, or the combustion amount is changed by changing from high combustion to low combustion Reduce the number of units.
The boiler operation control device 5 performs operation control of each boiler based on the combustion command from the number control device 2.

  In addition, each boiler 1 is provided with a flame detection device 6 that detects the presence or absence of a flame in each boiler. The flame detection device 6 and the boiler operation control device 5 are connected by a signal line and detected by the flame detection device 6. The flame presence / absence signal is sent to the boiler operation control device 5 in advance. In the combustion circuit in the boiler operation control device, the presence or absence of a flame is determined based on a signal from the flame detection device 6, and a flame detection unit is formed by the flame detection device and the combustion circuit. In the boiler, since it is dangerous to continue fuel supply with the flame extinguished, if the operation control device 5 receives a no flame signal during combustion, it stops the combustion of the boiler. Ensure safety.

  However, if an abnormality occurs in the flame detection device 6 or the combustion circuit and the presence / absence of the flame cannot be correctly detected, safety cannot be ensured. In the boiler operation control device 5, in order to prevent erroneous determination that there is a flame when no flame is present, it is confirmed that an output without a flame can be performed in a state where combustion is not performed. The soundness of the flame detection unit is checked every time combustion is stopped, but the boiler may perform continuous combustion for a long time. Therefore, if the time during which the soundness of the flame detection unit cannot be confirmed becomes longer, a self-check is performed to confirm the soundness of the flame detection unit by creating a state where there is no flame by forcibly suspending combustion. Do.

  The self-check is set in the number control device 2 that controls the operation of the entire boiler and the boiler operation control device 5 that controls the operation in each boiler. Two times are set in the unit control device 2, and the self-check operation is performed twice a day at the set time. This set time is set in a time zone in which the steam load is low and a spare can (a boiler capable of increasing the combustion amount) can be secured.

  Since the unit control device 2 performs a self-check during the time when a spare can can be secured, even if the steam supply amount decreases due to the combustion stop due to the self-check, the steam supply increases due to the increase in the combustion amount by other boilers. Can compensate for the decrease in quantity. When the self-check by the number control device 2 is normally performed, the self-check is performed twice a day at the same time, so that the continuous combustion time does not become longer than 24 hours.

  The boiler operation control device 5 is set to perform a self-check operation when the continuous combustion time reaches 24 hours. If the self-check is performed when the continuous combustion time of the boiler reaches 24 hours, it is performed regardless of the steam load. For this reason, self-checks may be performed when the boiler load factor is high. In this case, if the steam supply amount decreases due to combustion stop due to self-check, other boilers cannot compensate for the decrease in steam supply amount. For this reason, the steam supply amount may be insufficient. However, the self-check by the boiler operation control device 5 is performed as a backup of the self-check by the number control device 2, and if the self-check by the number control device 2 is performed twice a day, it is continuous. Since the combustion time never becomes 24 hours, the steam supply amount does not become insufficient.

  Further, when the self-check is performed, the operation priority of the self-check target boiler is lowered to a lower level, and spare cans are assigned to a higher rank than the lowered operation priority level, and the self-check is executed in that state. If it does in this way, since the boiler which stops combustion by a self-check stops combustion from the state which made the combustion amount comparatively small, the reduction | decrease range of steam supply amount becomes small. Then, since the steam supply amount is reduced, the boiler assigned to the higher level compensates for the increase in the combustion amount, so that a self-check for stopping the combustion can be performed without causing a shortage of the steam supply amount.

  However, boilers that have stopped burning from the “after the maximum time required for a series of self-check operations since the start of the previous self-check operation” to “this self-check” do not perform self-check operation (combustion stop). . In this case, even if the self-check setting time is skipped once, the next self-check setting time will come within 24 hours from the previous combustion stop. Therefore, it is not necessary to perform a self-check this time.

  Specific control of the self-check will be described. In this embodiment, the boiler controls the combustion amount at three positions of high combustion, low combustion, and stop, the steam supply amount at high combustion is 2 t / h, and the steam supply amount at low combustion is 1 t / h. It is assumed that h. In the first embodiment, the operation priority order of each boiler is returned to the original order before and after the self-check, and in the second embodiment, the operation priority order is switched to a specified order simultaneously with the self-check (rotation is performed). )

  A first embodiment will be described with reference to FIGS. In FIG. 2, the serial number of the self-check process is shown in the upper part, the operation priority and combustion state of the boilers A, B, C, D, and E are shown in the middle part, and the steam supply amount in the entire boiler is shown in the lower part. The combustion state in each boiler is represented by H for high combustion, L for low combustion, and-for combustion stop. The operation priority in this embodiment is that boiler A is first, boiler B is second, boiler C is third, boiler D is fourth, and boiler E is fifth. In the combustion of the boiler determined from the pressure value, the first and second ranks are high combustion, and the third to fifth ranks are low combustion. The amount of steam generated in this state is 7 t / h because 2 t / h is 2 units and 1 t / h is 3 units.

  In step <1>, the boiler E having the lowest operation priority is designated as the buffer boiler, and the combustion of the boiler E, which is the buffer boiler, is first stopped and the self-check is executed. When the boiler E stops combustion, one low-combustion boiler is reduced, and the total steam generation amount is reduced to 6 t / h. However, the boiler that stopped combustion for self-check here is the lowest operating priority boiler, and there are many higher-order boilers, so increase the combustion amount with the higher-order boiler. Can compensate for the decrease in steam generation. In the process <1>, the combustion amount of the boiler C that has been in low combustion with the operation priority of 3rd is high combustion, and the total steam supply amount is 7 t / h. Even if the boiler E stops the combustion for self-checking, it can supply the same amount of steam as the amount of steam generated before the combustion is stopped by making up for the decrease in the upper boiler.

  When the self-check of the boiler E is completed, the operation priority of the boiler E, which is a buffer boiler, is set to the first place in step <2>. At this time, there are two first-ranked boilers, and the first-ranked boiler E performs combustion. Boiler E, which is a buffer boiler, will supply steam instead of the boiler that stops combustion in order to perform self-checking after that, but in the state where combustion is stopped, steam supply is performed immediately. Since it cannot be performed, it is set as the combustion state by setting the operation priority to first. When the combustion amount of the entire boiler increases due to the combustion of the boiler E, the boiler C that has increased the combustion amount instead of the boiler E returns to low combustion. Since the upper three units are high combustion and the lower two units are low combustion, the steam supply rate is 8 t / h. However, immediately after confirming the steam supply of the boiler E, the next process <3> is performed. The amount of time that the amount is excessive is negligible.

  After confirming the combustion operation in the buffer boiler, the self-check is performed while using the buffer boiler. In <3> of the next process, the order of the buffer boilers is set to the highest operation priority among the boilers that are not self-checking. The boilers that have not been self-checked at this time are boilers A, B, C, and D, and the boiler with the highest operating priority is first in boiler A, so boiler E of the buffer boiler is first. . Then, boiler A, which has the highest operating priority among the non-self-checking boilers, is changed to the fifth lowest. The boiler combustion state is changed from high combustion to low combustion because the upper two units are high combustion and the lower three units are low combustion. Boiler E, which is a buffer boiler, is already ranked first in step <2> and does not need to be changed because high combustion has been performed.

  In this state, combustion is stopped in the lowest boiler A, and a self-check is performed. Since the boiler A that performs the self-check reduces the combustion amount by making it the lowest in advance, the decrease in the amount of steam generated due to the combustion stop is relatively small. Furthermore, even if the steam generation amount is reduced by stopping the combustion of the boiler A, the shortage of the steam generation amount can be compensated for by increasing the combustion amount with a higher-order boiler. In <3>, the third-place boiler C is changed from low combustion to high combustion in order to compensate for the decrease in the combustion amount, and the self-check can be executed without causing a shortage of the steam supply amount.

  In the next step <4>, the operation priority order of the boiler A that has undergone the self-check is returned to the first order, which is the original order. Here, there are temporarily two first-ranked boilers, but the boiler E, which is a buffer boiler, will immediately change its rank. At this point, since there is a boiler that has not been self-checked, the self-check operation is continued.

  In the next step <5>, the highest boiler among the non-self-check boilers is the boiler B which has the second highest operation priority, so the boiler E which is the buffer boiler is ranked second and the boiler B Is ranked lowest. Boiler B, which is in fifth position, has low combustion, which is the fifth combustion amount, and boiler E, which is in second position, has high combustion, which is the second combustion amount. Thereafter, combustion is stopped in boiler B and a self-check is performed. Again, the boiler that stops combustion has the lowest priority in operation, so the impact on the steam supply can be minimized, and even if the combustion amount is insufficient, the boiler is the highest. The steam supply amount can be maintained because the higher boiler C becomes highly combusted. When the boiler B self-check is completed, the operation priority of the boiler B is returned to the second place.

  After that, the self-check is sequentially performed in the same manner. The buffer boiler is placed in the order that the boilers that have performed the self-checking so far, and the buffer boiler operates in place of the boiler that performs the self-checking, so the number control can be performed without delay. And since the boiler that performs the self-check has the lowest operating priority immediately before the self-check, the decrease in the steam supply amount due to the combustion stop is a relatively small value, and there is a boiler with a higher rank than the boiler that performs the self-check. Since there are multiple, these boilers can make up for the amount of steam generated. When the self-check is completed for all the boilers, the operation priority of the boiler E, which has been used as a buffer boiler, is returned to the original rank of 5, and the self-check process ends. By doing in this way, even if combustion is stopped by self-check, the amount of steam supply does not become insufficient, and the steam supply pressure does not decrease.

  In the above-described embodiment, the boiler with the lowest operation priority is also burning. However, depending on the load situation, the boiler with the lower operation priority may stop combustion. When a boiler that has stopped combustion and is cold is used as a buffer boiler, steam cannot be generated immediately even if a combustion start command is output, and steaming takes time. Therefore, when there are a plurality of boilers that have stopped combustion, the boiler with the highest steam pressure or the boiler with the highest temperature of the can water is used as the buffer boiler. By doing so, the steaming time can be shortened, and the amount of fuel and electricity consumed can be suppressed, thus saving energy. Moreover, since the boiler with the highest steam pressure is a boiler that is highly likely to burn after the self-checking operation, it is less likely to be wasted if the boiler is steamed as a buffer boiler.

  In the above embodiment, the operation priority is returned to the original operation priority after the self-check is completed. However, the operation priority may be rotated in accordance with the change of the operation priority by the self-check. Next, an example in which the operation priority is changed simultaneously with the self-check will be described.

When the self-check and the operation priority rotation operation are performed at the same time, it can be performed as follows.
1. If the old priority is the lowest and the new priority is the lowest, the boiler with the lowest priority is temporarily burned and self-check is performed. (SKIP when the old priority is first and the new priority is other than the lowest).
2. The priority of the boiler with the lowest new priority is entered in the boiler with the lowest priority.
3. The boiler with the lowest new priority is placed first.
4). The boiler with the oldest priority is ranked first, the combustion is stopped temporarily, and self-check is performed (SKIP when the old priority is the lowest with the new priority).
5. The boiler with the first old priority is set as the new priority (SKIP when the first old priority is the lowest in the new priority).
6). If the priority of the boiler with the lowest new priority is the lowest, proceed to 10.
7). Of the boilers that have a high priority, set the priority of the boiler that is not the new priority to the lowest, stop the temporary combustion, and conduct a self-check (all of the boilers that have a high priority have a new priority) If not, select a boiler with a new priority that is not the lowest, and if the only boiler that is not the new priority is the lowest one with the new priority, do not change the priority and stop burning. Proceed to step 9).
8). Set the new priority for boilers that have stopped burning temporarily. If the new priority is the lowest, the rotation ends. Otherwise, return to 7.
9. Add 1 to the priority of the boiler with the lowest new priority, and return to 6.
10. The boiler with the lowest priority is temporarily burned, self-check is performed, and rotation is completed.
* When changing to a higher priority, wait until steaming.
Old priority: Priority at the start of rotation New priority: Priority at the end of rotation

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1 boiler
2 Number control device
3 Steam pressure detector
4 Steam header
5 Boiler operation control device
6 Flame detection device

Claims (1)

It consists of a plurality of boilers with operating priorities and a unit control device that outputs operation commands to each boiler. The unit control unit is a combustion command for the required number of boilers from the boilers with high operating priorities. Each boiler is a multi-can boiler that receives a combustion command and performs combustion, and detects the presence or absence of flame in a state where the combustion is temporarily stopped in each boiler. In multi-can installation boilers that perform self-checks to determine abnormalities, the unit control device should perform self-checks at the time set in a time zone in which spare cans can be secured. In addition, lower the operation priority of the boilers subject to self-check sequentially, and assign a spare can to a higher rank than the lowered operation priority Multi cans installed boiler is characterized in that it is intended to perform a self-check in that state.

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