JP4993696B2 - Boiler system - Google Patents

Description

  The present invention relates to a boiler system in which a plurality of boilers are installed and the number of boilers is controlled so that the required number of boilers are burned.

  A multi-can installation system for boilers is widely used in which a plurality of small boilers are installed instead of a large boiler, and the amount of steam generated is adjusted by adjusting the number of combustion boilers. In a system in which a large number of steam boilers are installed, the number of boilers to be burned is determined according to the steam pressure value in the steam collecting section that collects the steam generated in each boiler. The steam pressure value in the steam collecting portion is detected by a pressure sensor, and the detected steam pressure value is output to a number control device that controls the number of combustion boilers. In the unit control device, the combustion amount of the boiler is determined according to the steam pressure value, and when the detected steam pressure value is low, the amount of steam generated is increased by increasing the number of boiler combustions. The amount of steam generated is reduced by reducing the number of boilers that burn as the temperature rises. The steam pressure value can be kept within a predetermined range by increasing / decreasing the number of combustion boilers according to the steam pressure value of the steam collecting portion.

  Specifically, in the number control device, the steam pressure control range is divided into a plurality of pressure zones, and the combustion amount of the boiler is determined for each pressure zone. In boilers with multiple cans, combustion is generally controlled at three positions: high combustion, low combustion, and stop. High-combustion and low-combustion are based on the steam pressure value detected by the unit control system.・ Set a unit control pattern that sets the number of stops, and burn the determined number of boilers in descending order of priority.

  In the case of a boiler with low combustion at half the amount of combustion in high combustion, the amount of steam generated when two boilers are set to low combustion and the generation of steam when one boiler is set to high combustion The amount will be approximately the same. In this case, one high combustion boiler may be operated instead of the two low combustion boilers, and conversely, two low combustion boilers may be operated instead of the one high combustion boiler. Therefore, Japanese Patent No. 3538313 discloses that a pattern for increasing low combustion and a pattern for increasing high combustion are set, and either one is selected and the number control is performed. In the case of Japanese Patent No. 3583831, the peak of the power consumption in the factory can be lowered by reducing the power consumption of the boiler when the factory power consumption increases. Electricity purchased from an electric power company is contracted based on the amount of electric power during peak hours. Since the basic charge increases when the peak power is large, the basic charge can be kept low by reducing the peak power.

By the way, as the social situation in recent years, the need for energy saving and CO2 reduction is increasing as the revised Energy Saving Law and the Law on Promotion of Global Warming Prevention are being implemented. Various ideas for reducing the amount of energy used in boilers have also been made. Many improvements have been made as a single boiler, and the improvement in efficiency is approaching its limit. Therefore, it is required to reduce the amount of energy used not only as a boiler but also as a system. The energy used in the boiler includes fuel that burns a flame and electric power that operates a blower that supplies combustion air. Conventionally, the number control in consideration of the total energy usage has not been performed, but a method capable of reducing the energy usage is also required in the number control.
Japanese Patent No. 3538313

  The problem to be solved by the present invention is to provide a number control device that performs number control in consideration of reduction of energy consumption.

In the first aspect of the present invention, a plurality of three-position combustion control boilers that control combustion at three positions of high combustion, low combustion, and stop are installed, and a combustion command based on the unit control pattern is issued to each installed boiler. A boiler system provided with a unit control device for output, wherein the unit control device prioritizes improving the overall operating efficiency of the boiler, which is the amount of steam generated relative to the total value of fuel consumption and power consumption. If the operation efficiency priority pattern is selected, the ratio of boilers that perform high combustion is set as follows. Of the high combustion priority mode that outputs a combustion command so that it increases, and the low combustion priority mode that outputs a combustion command so that the ratio of boilers that perform low combustion increases, If you select a mode that improves the load and select the load following priority pattern, set the number of low combustion boilers for each of the rapid load mode, intermediate load mode, and slow load mode to reduce the combustion amount. Is to output a combustion command so as to secure the number of low combustion boilers corresponding to the selected mode, and is characterized in that the combustion command is output based on the mode set through a plurality of levels. .

According to a second aspect of the present invention, in the boiler system, a time schedule function is provided, a time zone in which the load is stabilized and a time zone in which the load is not stable are set in advance, and the operation is performed in the time zone in which the load is stable The number control based on the efficiency priority pattern is performed, and the number control based on the load following priority pattern is performed in a time zone when the load is not stable.

  By implementing the present invention, it is possible to reduce the amount of energy used as a boiler system and also reduce the amount of CO2 generated.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a boiler and a number control device 2 for implementing the present invention. In the figure, four steam boilers 1 are provided, and each boiler 1 is connected to a common steam header 6. The steam generated in each boiler is collected in the steam header 6 and then sent to the steam using apparatus side, and the pressure detection device 4 is provided in the steam header 6 which is a steam collecting portion. Each boiler 1 controls combustion at three positions of high combustion, low combustion, and stop, and an operation control device 3 is provided in each boiler. The operation control device 3 controls the operation of the boiler based on the combustion command from the number control device 2, and performs combustion by supplying a predetermined amount of fuel and combustion air according to the combustion state.

  If the low combustion is a boiler that generates half the amount of steam generated by high combustion, the fuel supply amount and the combustion air supply amount are adjusted to be halved. Here, it is assumed that the amount of steam generated by one low combustion boiler is 1 t / h, and the amount of steam generated by one high combustion boiler is 2 t / h. In this case, the amount of steam generated when four boilers are installed can be adjusted at intervals of 1 t / h between 0 t / h when all four units are stopped and 8 t / h when both units are high combustion. It will be a thing.

  Based on the steam pressure value detected by the pressure detection device 4, a unit control device 2 that determines the combustion amount in each boiler is provided. The number control device 2 sets the combustion amount of the boiler in correspondence with the steam pressure value detected by the pressure detection device 4, and outputs a combustion command to each boiler so that the determined combustion state is obtained. The number control device 2 is also connected to a boiler monitoring device 5 that monitors the operation of the boiler, so that the boiler operating status can also be monitored by the boiler monitoring device 5.

  FIG. 2 is a table listing examples of the number control pattern that is the basis of the number control performed by the number control device 2. The number control device 2 is set with an operation efficiency priority pattern that prioritizes improving the operating efficiency of the boiler and a load follower priority pattern that prioritizes improving the followability of the boiler with respect to load fluctuations. In FIG. 2, the case where the boiler is set to high combustion is indicated as H, the case where the boiler is set to low combustion is indicated as L, and the case where the boiler is stopped is indicated as-. When the steam pressure detected by the pressure detection device 4 increases, the amount of combustion decreases to decrease the supply amount of steam as the steam pressure value increases, and when the steam pressure decreases, the steam pressure value decreases. As the value decreases, the combustion amount is increased to increase the supply amount of steam.

  In the operation efficiency priority pattern, priority is given to improving the overall operation efficiency in the boiler, which is the amount of steam generated relative to the total value of fuel consumption and power consumption. For the operation efficiency priority pattern, a high combustion priority mode that outputs a combustion command so that the ratio of boilers that perform high combustion increases and a combustion command that outputs a ratio of boilers that perform low combustion increase There is a low combustion priority mode, and one of the two modes is selected and set as the operation efficiency priority pattern.

  In the high combustion priority mode, when increasing the steam generation amount, if there is a low combustion boiler, priority is given to the high combustion of the low combustion boiler, and if there is no low combustion boiler, the stopped boiler is Low combustion. When reducing the amount of steam generated, priority is given to stopping the low combustion boiler if there is a low combustion boiler, and if there is no low combustion boiler, the high combustion boiler is set to low combustion. Therefore, the operational status of each boiler is "----" "L ---" "H ---" "HL--" "HH--" "HHL-" "HHH-" "HHHL" "HHHH" ”In the order of“ HHHH ”“ HHHL ”“ HHH- ”“ HHL- ”“ HH-- ”“ HL-- ”“ H --- ”“ L --- ”“ ---- ” The amount of combustion is reduced in the order of "."

  Conversely, in the low combustion priority mode, when increasing the steam generation amount, if there is a boiler that has stopped operating, priority is given to burning the stopped boiler with low combustion, and there is no stopped boiler In this case, the low combustion boiler is set to high combustion. When reducing the amount of steam generated, priority is given to lowering the high combustion boiler if there is a high combustion boiler, and if there is no high combustion boiler, the low combustion boiler is stopped. Therefore, the operation status of each boiler is determined in the order of “----” “L ---” “LL--” “LLL-” “LLLL” “HLLL” “HHLL” “HHHL” “HHHH”. The combustion amount is increased and the combustion amount is decreased in the order of “HHHH”, “HHHL”, “HHLL”, “HLLL”, “LLLL”, “LLL-”, “LL--”, “L ---”, and “----”.

  In the load follow-up priority pattern, when changing the combustion amount, a combustion command is output aiming at securing the number of low-fired boilers set in advance. In the rapid load mode, 3 to 4 low combustion boilers are maintained when the combustion amount is reduced, and 2 to 3 low combustion boilers are provided when the combustion amount is increased. Of course, depending on the number of combustion units, there may be cases where the number of boilers with low combustion cannot be achieved. For example, if the amount of steam determined from the steam pressure value is equivalent to one low combustion boiler, the number of low combustion boilers is one. A combustion command is output. The rapid load mode is used when the steam load fluctuates suddenly. When four units are installed, the combustion state at one place differs depending on whether the amount of steam generated is increased or decreased. In this case, the operation status of each boiler is in the order of "----", "L ---", "LL--", "LLL-", "HLL-", "HLLL", "HHLL", "HHHL", and "HHHH". Increase the amount, and decrease the combustion amount in the order of "HHHH" "HHHL" "HHLL" "HLLL" "LLLL" "LLL-" "LL--" "L ---" "----" Become.

  In the middle load mode, two to three low combustion boilers are maintained when the combustion amount is decreased, and one or two low combustion boilers are provided when the combustion amount is increased. The medium load mode is located between the slow load mode and the rapid load mode. When four units are installed, the combustion state at two locations differs depending on whether the amount of steam generated is increased or decreased. The operational status of each boiler in this case is “----”, “L ---”, “LL--”, “HL--”, “HLL-”, “HHL-”, “HHLL”, “HHHL”, “HHHH”. Increase the combustion amount in order, decrease the combustion amount in the order of "HHHH" "HHHL" "HHLL" "HLLL" "HLL-" "LLL-" "LL--" "L ---" "----" Will do.

  In the slow load mode, one or two low combustion boilers are maintained when the combustion amount is decreased, and the number of low combustion boilers is 0 to 1 when the combustion amount is increased. The slow load mode is used when the steam load is relatively stable. When four units are installed, the combustion state at three locations differs depending on whether the amount of steam generated is increased or decreased. The operation status of each boiler in this case is “----” “L ---” “H ---” “HL--” “HH--” “HHL-” “HHH-” “HHHL” “ The combustion amount is increased in the order of “HHHH”, and “HHHH” “HHHL” “HHLL” “HHL-” “HLL-” “HL--” “LL--” “L ---” “----” The combustion amount will decrease in order.

  When the combustion designation for changing to high combustion is output to the low combustion boiler, the amount of steam generated can be increased in a short time. However, even if a combustion start command is output to a boiler that has stopped combustion, it takes a relatively long time to start the supply of steam after the start of combustion. It may be greatly reduced. Therefore, if a large number of low combustion units are secured when reducing the combustion amount, the next time the combustion amount is increased, the combustion amount can be increased in a short time, and the steam generation amount is immediately increased. Therefore, the load followability becomes high.

Even in the high combustion priority mode, the low combustion priority mode, the rapid load mode, the medium load mode, and the slow load mode, there is only one unit control pattern used in a certain time zone. Determined based on boiler characteristics and load fluctuations.
When performing unit control with the operation efficiency priority pattern, check in advance the mode in which the operation efficiency (steam generation relative to the total value of fuel consumption and power consumption) is higher from the high combustion priority mode and the low combustion priority mode. If there is no problem with load followability in the selected mode (operation efficiency priority pattern), the number of units is controlled in that mode.

  Depending on the characteristics of each boiler, even if priority is given to operating efficiency, some boilers have higher operating efficiency with low combustion and others with higher combustion efficiency. Different. For example, when two low combustion units are more energy efficient than one high combustion unit, the number of units is controlled so as to burn in a low combustion state as much as possible. The energy consumed by the boiler includes fuel that burns a flame, electric power that operates a blower that supplies combustion air, and the like. When calculating the operating efficiency of the boiler, it is necessary to convert the fuel consumption and the power consumption into the same condition because the fuel consumption and the power consumption cannot be directly compared. Conversion can be performed under the same conditions by converting to crude oil using the conversion formula of the Energy Saving Act (Act on Rational Use of Energy).

  When the number control is performed with the operation efficiency priority pattern, the load followability is remarkably deteriorated. Therefore, the number control may not be performed with the operation efficiency priority pattern. In such a case, control the number of units with the operation efficiency priority pattern during the time when the load is stable by the time schedule function, etc., or when the load is stable for a certain time by monitoring the steam pressure. If the steam usage amount fluctuates greatly and the stability of the steam pressure value should be prioritized, the number control is performed with a load following priority pattern with higher load following capability. In the load following priority pattern, based on the assumed load fluctuation, the sudden load mode when the load fluctuation is particularly rapid, the medium load mode when the load fluctuation is the next largest, and the steam load is relatively stable Set the slow load mode.

  In addition, the boiler monitoring device 5 is provided with a function that can monitor the fuel consumption, the power consumption, and the generated CO2 amount, and the boiler monitoring device 5 has an energy saving eco-effect in the operation efficiency priority pattern and the load followability priority pattern. Be prepared to monitor.

The block diagram of the boiler and unit control apparatus in one Example of this invention Boiler operating state explanatory diagram for each operation control pattern

Explanation of symbols

1 Boiler 2 Number control device 3 Operation control device 4 Pressure detection device 5 Boiler monitoring device 6 Steam header

Claims (2)

A number of three-position combustion control boilers that control combustion at three positions of high combustion, low combustion, and stop are installed, and a unit control device that outputs a combustion command based on the unit control pattern to each installed boiler is provided In the boiler system, the unit control device includes an operation efficiency priority pattern in which priority is given to improving the overall operation efficiency in the boiler, which is the amount of steam generated relative to the total value of fuel consumption and power consumption , and load fluctuations Load follow priority pattern that prioritizes improving the followability of the boiler
When the operation efficiency priority pattern is selected, a high combustion priority mode that outputs a combustion command so that the ratio of boilers that perform high combustion increases, and a combustion command that outputs a ratio of boilers that perform low combustion increases Select a mode that improves operating efficiency from among the low combustion priority modes.
When the load following priority pattern is selected, the number of low combustion boilers is set for each of the rapid load mode, intermediate load mode, and slow load mode. A combustion command is output to ensure the number of combustion boilers,
A boiler system that outputs a combustion command based on a mode set through a plurality of levels. The boiler system according to claim 1, wherein a time schedule function is provided, and a time zone in which the load is stable and a time zone in which the load is not stable are set in advance, and the time zone in which the load is stable is based on an operation efficiency priority pattern. A boiler system that controls the number of units and controls the number of units based on the load following priority pattern during periods when the load is not stable.

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