JP7350262B2 - Multi-can installation boiler - Google Patents

Description

The present invention is a system in which a plurality of boilers are installed in parallel and steam is supplied through a common steam header, and the amount of combustion in each boiler is controlled based on the steam pressure value. This concerns the installed boiler.

Figure 4 of Japanese Patent Application Laid-open No. 2000-205502 shows multiple boilers installed in parallel and a number control device that calculates the amount of combustion required for the entire boiler, and calculates the load amount for the entire boiler. By doing this, the number of boilers to be operated and the combustion amount are determined, and the number control device outputs combustion commands to each boiler to control the number of boilers to burn the required amount. Boiler is listed. In this multi-can boiler, the steam generated in each boiler is collected in a steam header and then sent to the steam usage area. The steam header is equipped with a header steam pressure detection device, and the unit control device detects the steam pressure at the steam header and controls the boiler operation so that the detected steam pressure value is maintained at a predetermined value. do.

The unit control device sets the operating priority for each installed boiler, and once the unit control unit determines the combustion amount for the entire boiler, it outputs combustion commands to the boilers in the order of the operating priority. . The amount of combustion in the boiler decreases as the steam pressure increases, and increases as the steam pressure decreases. Boilers with a high priority start combustion even when the steam pressure is relatively high, and In a low-temperature boiler, combustion begins only after the steam pressure has reached a relatively low value.

Although the number control by the number control device is determined based on the steam pressure at the steam header section common to each boiler, a steam pressure detection device is also installed in each boiler. By providing each boiler with a boiler operation control device and a boiler steam pressure detection device that detects the steam pressure within the boiler, individual operation control can be performed. Additionally, if the steam pressure inside the boiler becomes higher than the combustion stop pressure set for the boiler, combustion can be stopped even if a combustion command is output from the unit control device to the relevant boiler. There is.

Therefore, the number of steam pressure detection devices required is the number of boilers plus the number of devices for the common header section. In a multi-boiler installation system where a large number of boilers are installed, the increase in the number of steam pressure detection devices is not a big problem, but when controlling the number of installed boilers with two boilers installed, three steam pressure detection devices are required. 1.5 times as many detection devices are required, and a control device for controlling the number of detection devices is also required, which increases the cost burden.

The invention described in Japanese Unexamined Patent Publication No. 2000-205502 aims to reduce costs by eliminating the need for a pressure detection device for a steam header. In this invention, when the steam pressure value used to change the combustion amount is set differently for each boiler and operation is performed using the individual steam pressure in each boiler, the lower the steam pressure value is, the more the boiler is As the number of combustion boilers increases and the steam pressure increases, the number of combustion boilers decreases, making it possible to perform operational control similar to control of the number of boilers.

However, the steam pressure values in the individual boilers are different from the steam pressure values in the common steam header, which may cause variations in the operating state. The steam generated in each boiler is sent to a common steam header through individual steam piping, and if steam is supplied by combustion in the boiler, the steam pressure in the boiler and the steam pressure in the common steam header are have almost similar values. However, if the steam in the steam header is prevented from flowing back into the boiler, and the pressure in the boiler is lower than the pressure in the steam header, the pressure in the boiler and the pressure in the steam header will be different for a boiler without steam supply. There will be a difference. If the number of boilers is controlled based on the steam pressure in the boiler, which is different from the pressure in the steam header, appropriate operation control will not be possible.

Therefore, the number control device is designed to be able to take in the steam pressure value of the boiler detected by the steam pressure detection device installed in each boiler, and the number control device is designed to take in the steam pressure value of the boiler detected by the steam pressure detection device installed in each boiler. We considered controlling the number of units using the steam pressure value detected by the steam pressure detection device. When controlling the operation of multiple boilers based on the steam pressure of the boiler with the first priority in number control, the boiler with the first priority has a steam pressure value within the control steam pressure range. Since the boiler always continues combustion, by controlling the number of boilers based on the steam pressure of the boiler, it becomes possible to supply steam without excess or deficiency. The steam pressure value, which is the basis for controlling the number of units, uses the steam pressure detection device of the boiler attached to the base, so it is possible to control the number of units appropriately without installing a steam pressure detection device on a common steam header. can.

However, the ignition and combustion transition in the boiler with the first priority was delayed due to the time lag caused by water supply at the time of initial startup, and the boiler with the first priority, which would normally have the highest steam pressure, was ranked second and lower. The steam pressure of the boiler sometimes rose before the boiler with the highest priority. At this time, since the steam pressure that is the basis for controlling the number of units is the boiler with the first priority, priority 2, which has already reached a high pressure due to continued judgment that it is necessary to increase the steam pressure from a control point of view. Combustion continued in boilers with temperatures below 100,000 yen, and in boilers with high steam pressure, there was a possibility that the pressure would rise to the point where the high-high pressure switch or safety valve would operate.

Japanese Patent Application Publication No. 2000-205502

The problem to be solved by the present invention is a multi-boiler installed boiler in which the operation of multiple boilers installed in parallel is controlled based on the steam pressure value of the boiler itself, and the steam of the boiler whose operation priority is not the highest is If the pressure rises before the steam pressure of the boiler with the highest operational priority, the rise in steam pressure of the boilers other than the highest operational priority is slowed down, causing a situation where the high-high pressure switch or safety valve is activated. The goal is to prevent

The invention according to claim 1 is a multi-can installation boiler in which a plurality of boilers each having an operation control device and a steam pressure detection device are installed, and a number control device is added to the operation control device of a certain boiler. However, the other boilers are multi-can boilers that control the number of boilers by receiving combustion commands from the number control device, and the number control device controls the steam pressure detection device installed in each boiler. Basically, the unit control device is configured to be able to import the steam pressure value detected by the steam pressure detection device of the boiler with the highest operating priority. Although the number of units is controlled using the value, the steam pressure value detected by the steam pressure detection device of the boiler with the highest operation priority is better than the steam pressure value detected by the steam pressure detection device of the boiler with the highest operation priority. When the steam pressure value detected by the device is higher than a predetermined value or more, the number of boilers is controlled based on the steam pressure value of the boiler whose steam pressure value is higher than the boiler with the higher operating priority. It is characterized by

The invention according to claim 2 is based on the steam pressure value of the boiler that is higher than the steam pressure value of the boiler with the highest operational priority even though the operational priority is not the highest in the multi-can installed boiler. When controlling the number of boilers, if the difference between the steam pressure value of the boiler whose steam pressure has become high and the steam pressure value of the boiler with the highest operating priority becomes smaller than the threshold, the boiler with the highest operating priority is If you change to control the number of units based on the steam pressure value of the higher boiler, and a certain amount of time passes without the difference between the steam pressure value of the boiler with the highest operating priority becoming smaller than the threshold value, The method is characterized in that it is determined that an abnormality has occurred in the boiler. The invention according to claim 3 provides that in the multi-can installed boiler, regardless of the reference destination of the steam pressure value when controlling the number of boilers, when increasing the combustion amount, combustion is performed from the boiler with the higher operating priority. When increasing the amount and decreasing the combustion amount, the combustion amount is reduced starting from the boiler with the lowest operating priority.

By implementing the present invention, even if the steam pressure of a boiler whose operation priority is not the highest rises before the steam pressure of the boiler whose operation priority is the highest, the steam pressure value of the boiler whose operation priority is not the highest It is possible to slow down the rise and prevent a situation in which a high-high pressure switch or safety valve is activated.

Flow diagram of a multi-can installed boiler in one embodiment of the present invention An explanatory diagram of number control in an embodiment of the present invention

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart of a multi-can boiler according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of controlling the number of boilers according to an embodiment of the present invention. In the example, two boilers 1 are installed, and the boilers are named No. 1 and No. 2, respectively. The steam generated in each boiler is sent to the steam header 2 through a steam pipe 6 connected to the upper part of the boiler, and a main steam valve 8 is installed in the steam pipe 6. The steam generated in each boiler is once collected in a steam header 2 and then supplied to the steam usage area.

Each boiler has a steam pressure detection device 3 that detects the pressure of steam generated in the boiler, and an operation control device 5 that controls the operation of each boiler. The operation control device 5 of the No. 1 unit is also equipped with a number control device 4, but the number control device 4 is only installed in one boiler, and the number control device 4 is not installed in the other boiler. However, the number control device 4 communicates with the operation control device 5 of the second machine, and the communication device 7 based on standards such as RS-485 is used between the number control device 4 and the operation control device 5 of the second machine. Connected.

When performing complex number control, it is generally necessary to install a dedicated number control device, but in a small-scale multi-boiler installation such as two boilers, the number control performed is simple. In this case, by adding a function to control the number of boilers to the boiler operation control device, it is possible to control the number of boilers while keeping costs down. The number control function is performed by setting a program for controlling the number of machines in the operation control device. In this embodiment, the number control device 4 attached to the operation control device 5 of boiler No. 1 controls the number of boilers in two boilers, boiler No. 1 and boiler No. 2.

The number control device 4 outputs a combustion amount instruction to boiler No. 1 itself, and also outputs a combustion amount instruction to boiler No. 2. The actual operation control is carried out by the operation control device 5 installed in each boiler, and each operation control device controls the operation of the boiler based on the combustion amount instruction from the number control device 4.

In controlling the number of boilers, the amount of combustion required for all boilers is determined based on the supplied steam pressure value, and the amount of combustion for each boiler is allocated. Operation priorities are set for the installed boilers, and the amount of combustion is allocated starting from the side with the highest operation priority, and combustion is performed in the order of the operation priority. When increasing the combustion amount, the combustion amount is increased in order from the boiler with the highest operating priority, and the boiler with the highest operating priority starts combustion when the steam pressure is relatively high. When the steam pressure value becomes low, combustion occurs even in boilers with low operation priority. Conversely, when decreasing the combustion amount, the combustion amount is decreased in order from the boiler with the lowest operating priority.

When controlling the number of units using the number control device 4, the steam pressure value detected by the steam pressure detection device 3 of boiler No. 1 or the steam pressure value detected by the steam pressure detection device 3 of boiler No. 2 Based on this, determine the combustion amount of the boiler. The steam pressure value used at this time is basically the steam pressure value detected by the steam pressure detection device of the boiler whose operation priority is the highest to control the number of boilers. When the operation priority of boiler No. 1 is high, the number control device 4 controls the number of boilers based on the steam pressure value detected by the steam pressure detection device 3 on the boiler No. 1 side. Conversely, when the operation priority of Boiler No. 2 is higher, the number control device 4 determines the steam pressure value detected by the steam pressure detection device 3 of Boiler No. 2 whose operation priority is higher. Controls the number of units.

The number control device 4 outputs a signal requesting the steam pressure value to the operation control device 5 of the boiler whose operation priority is higher, and the operation control device of the boiler that received the signal The steam pressure value detected by the steam pressure detection device 3 is sent back to the number control device 4. The number control device 4 determines the necessary combustion amount based on the received steam pressure value, and outputs a combustion amount command to each boiler.

The reason why the steam pressure of the boiler with the higher operating priority is used is because a discrepancy occurs between the steam pressure value in the boiler and the steam pressure value supplied from the steam header 2. In the case of a boiler that generates steam by combustion, when the pressure inside the boiler increases, the pressure inside the steam header 2 also increases, and the steam pressure value inside the boiler and the steam pressure value supplied from the steam header 2 are approximate values. becomes. However, if there is a boiler that is supplying steam and a boiler that is not supplying steam, the steam pressure in the boiler that is not supplying steam will be a value lower than the steam pressure in the steam header 2. At this time, if the number of units is controlled based on the steam pressure detected by the pressure detection device on the side that is not supplying steam, which is a low value, the steam pressure value actually supplied to the steam usage location will be The number of units will be controlled based on steam pressure values that are far apart, and proper operation will not be possible. A boiler with a high priority for operation is a boiler with a high steam pressure value, and the boiler internal pressure is considered to be close to the steam pressure value supplied from the steam header. By performing control based on the steam pressure value detected in the boiler on the side where the steam pressure value is higher, it is possible to appropriately control the number of boilers.

However, the steam pressure value of a boiler with a higher operating priority is not necessarily higher than the steam pressure value of a boiler with a lower operating priority. If you thought that the number of boilers was controlled based on the steam pressure on the side where the steam pressure value was higher, but in reality it was controlled based on the steam pressure on the side where the steam pressure value was lower, then the boiler There is a possibility that a higher combustion amount than necessary is required for the steam, and if the combustion exceeds the required range, the steam pressure will rise more than expected, causing the high-high pressure switch and safety valve to operate. It also becomes.

Therefore, basically, the number of units is controlled based on the steam pressure value detected by the steam pressure detection device 3 on the side of the boiler with the highest operating priority, but if the steam pressure value is detected in a boiler with an operating priority other than the highest. If the steam pressure value is higher than the steam pressure value detected in the boiler with the highest operating priority by a predetermined value or more, operation control is performed based on the steam pressure of the boiler with the lower operating priority. I'll decide. After that, the steam pressure of the boiler with the highest operating priority increases, and when the difference in steam pressure value between the boiler with the lower operating priority and the boiler with the highest operating priority becomes smaller than the "threshold". , the number of boilers is controlled based on the steam pressure value of the boiler with the highest operating priority. In addition, in the above case, if the steam pressure value detected in the boiler with the highest operating priority does not rise and the steam pressure value difference remains above the threshold value for a predetermined period of time, steam pressure detection in any boiler It is determined that there is a equipment failure or that the main steam valve opening is inappropriate.

A time chart in one embodiment of the present invention will be explained based on FIG. 2. In the example, the operation priority of boiler No. 1 is the first, and the operation priority of the boiler No. 2 is the second, and the boiler starts from a state where the operation is stopped. In each boiler, combustion is performed based on the combustion amount instructions at four positions: high combustion, medium combustion, low combustion, and stop.In Figure 2, the combustion instruction for high combustion is "H", and the combustion instruction for medium combustion is The instruction is indicated by "M", the combustion instruction for low combustion is indicated by "L", and the combustion instruction for standby combustion is indicated by "-".

When the operation switch is turned OFF and the steam pressure value in the boiler is 0, when the operation switch is turned ON at time A, the combustion amount instruction to each boiler of Unit 1 and Unit 2 is It changes from "-" for combustion standby to "H" for high combustion. Even if the combustion amount is increased in the order of operation priority, the steam pressure value is significantly insufficient at time A, so the combustion amount is increased simultaneously for the No. 1 and No. 2 boilers. The command to do this is being output. Even if the combustion amount is indicated as high combustion at time A, the steam pressure value does not change immediately because an operation preparation process is actually required. The process of preparing for operation in the boiler is to first check the water level in the boiler, and if a predetermined amount of water has not accumulated in the boiler, water is supplied. If the amount of water in the boiler is sufficient, the sequence for starting combustion will begin; however, if there is no water in the boiler, the next process cannot begin until a predetermined amount of water has accumulated in the boiler, so combustion will not start. The start will be delayed.

Even if two boilers are instructed to start operating at the same timing, the timing of starting the boilers is not necessarily the same. For example, boiler No. 1, which has the first priority, has just finished blowing and there is no water in the boiler, while the second priority boiler has enough water stored to start combustion immediately. In this case, Unit 1, where the water level is low, requires time to collect a certain amount of water in the boiler, and combustion can only be started after that time, whereas the boiler with a high water level can start combustion immediately. Therefore, the No. 2 boiler, which has the second priority, starts combustion earlier than the No. 1 boiler, which has the first priority. In addition, the start of combustion will be delayed if the capacity of the water pump in one boiler has decreased, or if a misfire occurs during ignition in one boiler and a retry is performed.

Therefore, in this embodiment, the number of units is basically controlled based on the steam pressure value detected by the steam pressure detection device 3 on the side of the boiler with a high priority of operation. If the steam pressure value is higher than the predetermined value of 0.20 MPa or more than the steam pressure value detected in the boiler with the first priority in operation, the number of units will be controlled based on the steam pressure of the boiler with the lower priority in operation. . Then, if the steam pressure of the boiler with the highest operating priority increases and the difference in steam pressure values becomes smaller than the threshold value of 0.05 MPa, the steam pressure of the boiler with the highest operational priority increases, and the steam pressure value is no longer used to control the number of units. The number of units will be controlled based on the value. However, in the above case, if the steam pressure value detected in the boiler with the highest operating priority does not rise and the difference in steam pressure value remains above the threshold value for a certain period of time, the It determines that the steam pressure detection device has failed or that the main steam valve opening is inappropriate, and notifies you of the abnormality.

In this case, a high combustion combustion command is output to the two boilers at time A, and combustion is started after each boiler performs a preparatory process. However, the actual combustion starts first in the second unit, which has a lower priority, and the steam pressure value increases in the second unit first. At time B, the steam pressure value of Unit 1 is 0.28 MPa, and the steam pressure value of Unit 2 is 0.45 MPa, which is 0.17 MPa higher in Unit 2 than in Unit 1. In this example, if the steam pressure of the boiler with the second priority is higher than the steam pressure of the boiler with the first priority by more than a predetermined value of 0.20 MPa, the steam pressure of the boiler with the second priority is Since the system is designed to perform operational control, at time B, the steam pressure of the second-priority boiler has not yet reached a difference of more than a predetermined value, and the steam pressure of the first-priority boiler is The number of units is controlled based on this.

Thereafter, at time C, the steam pressure of the first unit becomes 0.30 MPa, and the steam pressure of the second unit becomes 0.50 MPa, and at this point the difference in steam pressure has reached the predetermined value of 0.20 MPa. If the pressure of Unit 2, which has a lower priority, becomes 0.20 MPa or more higher than Unit 1, which has a higher priority, the number of units will be controlled using the steam pressure value of Unit 2, which has a lower priority. In this case, from time C when the difference is greater than a predetermined value, the number of units will be controlled based on the steam pressure value of the second unit. In the settings for number control, if the steam pressure value is 0.30 MPa, the combustion amount will be set to two high combustion units, and if the steam pressure value is 0.50 MPa, the combustion amount will be set to one high combustion unit and one medium combustion unit. When controlling the number of units based on the steam pressure value of Unit 1, which is just before time C and has a relatively low pressure, there will be two high combustion units, but after time C, the steam pressure value of Unit 2, which has a relatively high pressure. Since the steam pressure value, which is the basis for controlling the number of engines, has become higher, the combustion amount will be one high combustion engine and one medium combustion engine. Even if the steam pressure value reference changes, the combustion amount will be lowered from the boiler with the lowest operating priority, so from time C onwards, the combustion amount will be lowered at Unit 2, which has the lower operating priority, and the combustion amount of Unit 2 will be lowered. will be changed to medium combustion.

After that, the difference between the steam pressure values of Unit 1 and Unit 2 decreased, and at time D, the steam pressure value of Unit 1 became 0.50 MPa, and the steam pressure value of Unit 2 became 0.54 MPa, so that the pressure difference was lower than the threshold of 0.05 MPa. It's getting smaller. Therefore, from time D, the number of machines is controlled based on the steam pressure value of the first machine.

Additionally, if there is a delay at the start of combustion, if the delay is temporary, if the operation continues, the normal operating state will return as described above, but a failure has occurred in the steam pressure detection device 3. If the opening degree of the main steam valve 8 is inappropriate, the difference in the reversed steam pressure values will remain larger than the threshold value. In this case, if the steam pressure difference in the state where the steam pressure value is reversed exceeds the threshold value for a certain period of time, a failure of the steam pressure detection device 3 of one of the boilers or a failure of the main steam valve 8 will occur. It determines that the opening is inappropriate and notifies you of the abnormality.

In this embodiment, when the steam pressure value detected in a boiler other than the highest operating priority becomes higher than the steam pressure value detected in the boiler with the highest operating priority by "more than a predetermined value", Assuming that operation control is to be performed based on the steam pressure of the boiler with the lowest operating priority, the predetermined value is 0.20 MPa, but the predetermined value can be any value. If the predetermined value is 0, the number of steam generators will be controlled based on the highest steam pressure value at that time.

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

1 Boiler 2 Steam header 3 Steam pressure detection device 4 Number of units control device 5 Operation control device 6 Steam piping 7 Communication device 8 Main steam valve

Claims (3)

A multi-boiler installed boiler in which a plurality of boilers each having an operation control device and a steam pressure detection device are installed, and a number control device is added to the operation control device of one boiler, and the number control device is added to the operation control device of one boiler, and the number control device is added to the operation control device of one boiler. This is a multi-can installed boiler that performs number control by receiving combustion commands from the device, and the number control device controls the boiler steam pressure detected by the steam pressure detection device installed in each boiler. The unit control device basically controls the number of units using the steam pressure value detected by the steam pressure detection device of the boiler with the highest operating priority. However, the steam pressure value detected by the steam pressure detection device of the boiler with the highest operation priority is higher than the steam pressure value detected by the steam pressure detection device of the boiler with the highest operation priority. A multi-can installation boiler characterized in that when the steam pressure value becomes higher than a predetermined value, the number of boilers is controlled based on the steam pressure value of the boiler whose steam pressure value is higher than that of the boiler with a higher operating priority. . In the multi-can installed boiler according to claim 1, the number of boilers is controlled based on the steam pressure value of the boiler that is higher than the steam pressure value of the boiler with the highest operational priority even though the operational priority is not the highest. When the difference between the steam pressure value of the boiler whose steam pressure has become high and the steam pressure value of the boiler with the highest operating priority becomes smaller than the threshold value, the boiler with the highest operating priority If the change is made to control the number of units based on the steam pressure value, and a certain period of time passes without the difference between the steam pressure value of the boiler with the highest operating priority becoming smaller than the threshold value, an abnormality will occur in one of the boilers. A multi-can installed boiler characterized in that it is determined that a is occurring. In the multi-can installed boiler according to claim 1 or 2, when increasing the combustion amount, the combustion amount is increased from the boiler with the highest operating priority, regardless of the reference destination of the steam pressure value when controlling the number of boilers. A multi-can installed boiler characterized in that when the combustion amount is increased and the combustion amount is decreased, the combustion amount is reduced starting from a boiler with a lower operation priority.

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