JP3711645B2 - Boiler automatic number controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic boiler number control device that burns and stops a required number of boilers according to a load amount by a signal of a pressure sensor that detects an internal pressure of a steam collecting portion common to a plurality of installed boilers. is there.
[0002]
[Problems to be solved by the invention]
As is well known, in a multi-can installation system in which multiple boilers are installed, a pressure sensor is installed in the steam collecting section to grasp the state of the load, and the required number is determined according to the startup sequence set in advance according to the load amount. An automatic number control system is adopted in which the system is shifted to sequential combustion, and if there is a load change, the boiler is combusted and stopped in accordance with the load change to follow the load.
[0003]
In this method, for example, when three three-position controlled boilers (NO.1 to N0.3) that perform combustion control at three positions of high combustion state H, low combustion state L, and stop state are installed, the graph of FIG. The control pressure is divided into seven steam pressure zones a to g, and the number control corresponding to each steam pressure zone (reference pressure zone) is performed. That is, in the lower limit steam pressure zone a, all cans are in a high combustion state (HHH), and priority is given according to a predetermined priority order as HHH → HHL → HH → HL → H → L as the steam pressure increases. The boiler is stopped from the lower rank boiler, and all cans are stopped in the upper limit steam pressure zone g. When the steam pressure drops, the cans are activated in descending order of priority.
[0004]
However, the above automatic number control system has the following problems.
That is, if the pressure sensor fails due to deterioration or the like, for example, when the signal from the pressure sensor maintains a high pressure value output, the boiler sequentially stops combustion as described above, and finally all cans stop, Steam supply stops. The suspension of steam supply in such a multi-can installation system has a significant impact and must be avoided as much as possible. On the other hand, despite the fact that the pressure sensor detects a low pressure, the appropriate number control is not performed even when all boilers are stopped at the high pressure set value.
[0005]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-described problem, and the number of required units according to the load amount is determined by a signal from a first pressure sensor that detects an internal pressure of a steam collecting portion common to a plurality of installed boilers. Each of the boilers has a second pressure sensor for detecting the pressure in the can, and the number control means detects an abnormality of the first pressure sensor. An abnormality detection means; and a maximum value storage means for storing the maximum value of the detected pressure of the second pressure sensor when the boiler reaches a stop after being operated, and the maximum value is detected when an abnormality is detected by the abnormality detection means. The number control is performed by comparing the reference pressure determined based on the maximum value stored in the value storage means and the input signal from the second pressure sensor.
[0006]
According to the above means, when the abnormality of the first pressure sensor is detected, the number control means controls the number of the control reference value with the maximum value stored in the maximum value storage means and the detected pressure of the second pressure sensor. The number control according to the normal time of the first pressure sensor is executed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
As an embodiment of the present invention, an automatic boiler number control device is provided for a necessary number of units according to the load amount by a signal of a first pressure sensor that detects an internal pressure of a steam collecting portion common to a plurality of boilers installed. In the apparatus comprising a number control means for burning / stopping the boiler and a second pressure sensor for detecting the pressure in the can in each boiler, the number control means detects an abnormality of the first pressure sensor. Means, and maximum value storage means for storing the maximum value of the detected pressure of the second pressure sensor when all the boilers are stopped after all the boilers are operated, and when the abnormality is detected by the abnormality detecting means, It is assumed that the number control is performed by comparing the reference pressure determined based on the maximum value stored in the maximum value storage means and the input signal from the second pressure sensor.
[0008]
This embodiment will be described below. The boiler subject to the number control may be a boiler other than the once-through type. A steam collecting portion common to a plurality of installed boilers is usually referred to as a steam header, but it may be any portion where steam from each boiler gathers. The first pressure sensor may be inserted into the collecting portion, or may be configured such that the detection tube is connected to the collecting portion and inserted into the detecting tube to detect the pressure. The number control means controls the number of combustion by comparing the predetermined control reference value with the detected pressure of the first pressure sensor. Specifically, in the control method by the number control means, the control reference value is divided into pressure bands corresponding to the number of boilers as in the conventional example of FIG. 4, and the pressure detected by the first pressure sensor is in which pressure band. Therefore, a method for controlling the number of units is adopted, but the present invention is not limited to such a pressure band division control method, and can be applied to other control methods.
[0009]
The abnormality detecting means for detecting the abnormality of the first pressure sensor is preferably a pattern in which the number control means compares the detected pressure of the second pressure sensor with the detected pressure of the first pressure sensor, and cannot occur in a normal state, for example, There is no pattern in which the pressure detected by the second pressure sensor exceeds the pressure detected by the first pressure sensor, or the first pressure sensor even though all boilers have the maximum pressure (for example, 8.5 kg / cm ² ). When the detected pressure is a pattern with a pressure much lower than that (for example, 7.0 kg / cm ² G), the first pressure sensor determines that it is abnormal.
[0010]
The unit control means operates all boilers, stores the maximum value of the detected pressure of the second pressure sensor of a specific boiler when the pressure in the collecting section reaches the upper limit of the control reference value and all cans stop Store in the means. The storage of the maximum value is desirably performed during a trial run, but is not limited thereto. The specific boiler to be stored is preferably the first priority boiler (starts up first and stops last), but may be a sensor of the boiler of the next priority. In addition, when the abnormality detection unit detects an abnormality of the first pressure sensor, the number control unit changes and sets the control reference value based on the maximum value stored in the maximum value storage unit, and the detection sensor is set to the second pressure sensor. Change to, and perform unit control.
[0011]
【Example】
In the figure, reference numeral 1 denotes a boiler, and the following three units (NO.1 to NO.3: This No. also indicates the priority of startup along with the boiler number. The lower the number, the higher the priority of startup, the priority of stoppage. Many boilers are installed. Each boiler is provided with an operation control device 11 and a combustion device 12. Reference numeral 13 denotes a second pressure sensor for detecting the pressure in the boiler can. Each boiler is connected to a common steam collecting portion 2 by a steam pipe 5 into which a check valve 6 is inserted. The steam collecting portion is provided with a first pressure sensor 3 for detecting the internal steam pressure, and the number controller 4 controls the combustion / stop of each boiler 1 based on the pressure detection signal. It has become. When a combustion control signal is issued from the number controller 4 to each boiler 1, the boiler activation order follows a preset order. Specifically, the order pattern of starting and stopping is the same as in FIG. A semiconductor pressure sensor is used as the first pressure sensor 3 and the second pressure sensor 13.
[0012]
Reference numeral 7 denotes a combustion supply line connected to the combustion device 12. In the line, the downstream side of the fuel pump 9 is divided into two systems, and a combustion control electromagnetic valve 8 is inserted into each system. . VH represents a high combustion control solenoid valve, and VL represents a low combustion control solenoid valve. The combustion control of the boiler is performed by opening and closing these solenoid valves. That is, when the low combustion control solenoid valve VL is opened and when the high combustion control solenoid valve VH is closed, the low combustion state is established, when both solenoid valves are opened, the high combustion state is established, and when both solenoid valves are closed, the stop state is established.
[0013]
The number controller 4 performs backup control for the abnormality of the first pressure sensor 3 in addition to the above-described normal number control. This backup control includes storage control of the maximum pressure value of the boiler 1 with the highest priority, abnormality detection control of the first pressure sensor 3, and unit control when abnormality of the first pressure sensor 3 is detected.
[0014]
The storage control of the maximum pressure value of the boiler with priority No. 1 is performed as follows.
During the test run, all boilers are operated, and when the pressure in the steam collecting part 2 reaches the upper limit of the control reference value (for example, 8.0 kg / cm ² G) and all the cans stop, the second pressure sensor 3 of the boiler The maximum value (for example, 8.5 kg / cm ² G) of the detected pressure is stored in maximum value storage means (memory not shown). The exchange of signals from the second pressure sensor 13 is performed by communication between the number controller 4 and the operation control device 11.
[0015]
The abnormality detection control of the first pressure sensor 3 and the number control at the time of abnormality detection of the first pressure sensor 3 are performed, for example, according to the control procedure shown in FIG. In step S1 (hereinafter, SN means step SN), it is determined whether or not the output of the first pressure sensor 3 is abnormal on the high pressure side. Specifically, the number controller 4 monitors the detection signal of the second pressure sensor 13 through communication with the operation control device 11 for all cans. For example, the detected pressure of the first pressure sensor 3 is 7.8 kg. / cm ² for a G, the detected pressure of the second pressure sensor 13 of the boiler 1 (NO.1~NO.3) ^{is, 7.0kg / cm 2 G, 6.0kg} / cm 2 G, 5.0kg / cm ^When there is nothing exceeding the detection value of the first pressure sensor 3 such as ² G, it is determined as abnormal. This is because a pressure loss occurs between each boiler 1 and the collecting portion 2, and therefore, the pressure of the collecting portion 2 is lower than the pressure of the boiler 1.
[0016]
When the determination of S1 is NO, the process proceeds to S2, and it is determined whether or not the output of the first pressure sensor 3 is abnormal on the low pressure side. Specifically, for example, when the detected pressure of the first pressure sensor 3 is 7.0 kg / cm ² G, the detected pressure of each of the second pressure sensors 13 of the boiler 1 (NO.1 to NO.3) is 8.5. It is judged as abnormal when it is kg / cm ² G or more. This is because when the pressure of the boiler 1 shows a substantially maximum value, the pressure of the collective part 2 cannot be only 7.0 kg / cm ² G. The abnormality determination in S2 can be configured as follows. That is, when the boiler 1 is configured to stop in order to protect the boiler 1 from high pressure when the detected pressure of the second pressure sensor 13 exceeds the high pressure set value, all the boilers 1 exceed this high pressure set value. You may comprise so that it may determine with abnormality, when the detection pressure of the 1st pressure sensor 3 is considerably lower than a high pressure set value. If this high pressure set value is set to 8.5 kg / cm ² G, it becomes the same as the above-described abnormality determination example.
[0017]
If NO is determined in S2, the process proceeds to S3. Here, the number control when the first pressure sensor is normal, that is, the number control by the first pressure sensor 3 is performed without changing the control reference value.
[0018]
If YES is determined in S1 or S2, the process proceeds to S4, where the control reference value is changed. Specifically, based on the maximum value (8.5 kg / cm ² G) of the detected pressure of the boiler stored during the test operation, the upper limit value of the control reference value (control width) is a predetermined value lower than this maximum value, for example, 8.4 city kg / cm ² G, the lower limit value be 7.4kg / cm ² G. That is, in the normal state, those was ^{8.0kg / cm 2 G~7.0kg / cm 2} G, when an error is detected is changed to ^{8.4kg / cm 2 G~7.4kg / cm 2} G. Incidentally, 7.4 kg although FIG. 4 is an explanatory view of a conventional example, the pressure value 8.0 kg / cm ² G in FIG. 4 to 8.4 kg / cm ² G in the present embodiment, the pressure value 7.0 kg / cm ² G Change each to / cm ² G.
[0019]
Subsequently, the process proceeds to S5, and the number control is executed according to the changed control reference value based on the detection signal of the second pressure sensor 13. As a result, regardless of the failure of the first pressure sensor 3, the second pressure sensor 13 controls the number of units in accordance with the control by the first pressure sensor 3, and prevents the boiler 1 from being stopped or abnormally controlled. Is done.
[0020]
【The invention's effect】
According to the present invention configured as described above, in the event of a failure of the first pressure sensor, the second pressure sensor provided in the boiler can perform unit control similar to the control by the first pressure sensor without any trouble. It is possible to avoid an abnormal situation such as stopping all the cans.
[Brief description of the drawings]
FIG. 1 is a block diagram of a system according to an embodiment of the present invention.
FIG. 2 is a detailed configuration of a main part of the embodiment of the present invention.
FIG. 3 is a flowchart showing a control procedure of the embodiment of the present invention.
FIG. 4 is a diagram illustrating a combustion control pattern of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Boiler 2 Collecting part 3 1st pressure sensor 4 Number controller 13 2nd pressure sensor

Claims (1)

Unit control means for burning / stopping the required number of boilers according to the load amount based on the signal from the first pressure sensor that detects the internal pressure of the steam collecting section common to the boilers installed in a plurality of units, and a boiler for each boiler And a second pressure sensor for detecting the pressure in the unit, wherein the number control means includes an abnormality detection means for detecting an abnormality of the first pressure sensor, and when all the boilers are operated and then stopped. A maximum value storage means for storing the maximum value of the detected pressure of the second pressure sensor, and a reference pressure determined based on the maximum value stored in the maximum value storage means when an abnormality is detected by the abnormality detection means; A boiler automatic number control device that controls the number of units by comparing with input signals from two pressure sensors.

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