JP2671246B2 - Method of controlling the number of once-through boilers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-can installation system in which a plurality of small once-through boilers are installed, which automatically determines the number of burner boilers and the number of high burners and the number of low burners by steam load fluctuation. The present invention relates to a method for controlling the number of vehicles.

[0002]

2. Description of the Related Art As a device for controlling the number of small boilers installed in a large number of cans, a plurality of boilers are used as a common steam, as described in JP-A-60-169003 or JP-A-60-21805. A well-known method is to burn a required number of boilers according to a load by a pressure detection device which is received by the header and can detect a load state installed in the steam header. FIG. 2 explains the outline.

In these methods, a plurality of small boilers are installed instead of a large boiler, the pressure of the steam header is detected, and the number of boilers to be burned is controlled according to the load. A boiler is used that has three-position combustion control of stop, low combustion, and high combustion. Combustion control of the boiler is performed according to the steam pressure detected by the pressure detection device.When the steam pressure is high, the number of stopped units is increased, and when the steam pressure is low, the number of high combustion units is increased. For each steam pressure, set the combustion amount that determines the number of stopped boilers, low-combustion boilers, and high-combustion boilers. Combustion control is performed according to the combustion amount set as a pattern and determined by the steam pressure. In this case, the thermal efficiency is good, but the number of operating boilers and the combustion pattern are determined by the pressure detected by the steam header etc.The absolute amount of required steam is not detected, and it is obtained from the difference between the steam generation amount and the steam consumption amount. Since only the steam pressure, which is a relative value, is known, there is a drawback that smooth follow-up control cannot be performed with respect to a sudden change in steam load.

[0004]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a multi-can installation system in which a plurality of small boilers are installed so as to smoothly follow rapid changes in steam load. To supply a highly efficient multi-can system.

[0005]

[Means for solving the problem] A steam header that installs a plurality of once-through boilers with three-position combustion control of stop, low combustion, and high combustion and collects steam generated in each boiler or distributes the collected steam The steam header and each boiler are connected by a steam pipe, and the steam pipe or steam header is provided with a steam collecting portion that collects and flows the steam generated in all the boilers. In a multi-can installation system, a steam accumulator is provided in the middle of the steam pipe that connects the steam header and the boiler, and a steam flow rate detection device that detects the steam flow rate at the gathering part of the steam downstream of the steam accumulator, A pressure detector was installed to detect the steam pressure at the gathering part, and the number of boilers burned was determined by the signal from the steam flow detector to detect the pressure. Units control method of once-through boiler, characterized by determining the number of boilers to perform high combustion low combustion and the number of boiler performing of the combustion amount, that the determined boiler combustion volume by a signal from the device.

[0006]

[Operation] By installing a steam accumulator between multiple boilers and steam headers, steam can be stored in the steam accumulator and the stored steam can respond to sudden changes in steam load. Therefore, it is possible to prevent a sudden pressure change in the steam header. By determining the number of boilers burned by the steam flow rate, which is the absolute amount of required steam detected by the steam flow rate detection device installed in the steam collecting section downstream from the steam accumulator, the steam consumption changes rapidly. However, it is possible to respond quickly. The amount of steam supplied to the boiler, which is determined to burn depending on the steam flow rate, is adjusted by determining the combustion amount of the boiler, that is, the number of high-combustion and low-combustion units, based on the steam pressure detected by the pressure detection device. When the steam supply amount is less than the consumption amount and the steam pressure decreases, the number of low combustion units is reduced to increase the number of high combustion units, and when the steam supply amount is larger than the steam consumption amount and the steam pressure rises, it is high. Adjust by increasing the number of low-combustion units and increasing the number of low-combustion units, and do not change the number of boilers that are combusting unless the absolute steam flow rate changes. The number of stops is reduced, the combustion efficiency can be improved as a whole, and the life of the boiler can be extended by reducing the number of times of starting and stopping.

[0007]

An embodiment of the present invention will be described with reference to the drawings.
Steam pipes from multiple once-through boilers are collected and connected to a steam accumulator. In the illustration of FIG. 1, the steam pipes are combined into one and connected to the steam accumulator, but two or more sets of steam pipes may be divided and connected to the steam accumulator. In FIG. 1, the steam collecting part is from the steam pipe part collected on one upstream side of the steam accumulator to the steam header. A steam flow detector and a pressure detector on the steam header will be installed in the middle of the pipe connecting the output of the steam accumulator to the steam header. Install the steam flow detector and pressure detector in the steam collecting part where the steam generated in each boiler collects and flows, and in the case where a steam accumulator is provided, in the steam collecting part downstream of the steam accumulator. Need, each electrically connected to the controller.

The present embodiment shows a case where 10 boilers are installed for performing three-position combustion control of stop, low combustion, and high combustion. The installed boilers are electrically or mechanically connected to the control device, and a high-combustion, low-combustion, or stop of each boiler is generated by a signal from the control device.

FIG. 3 is a diagram showing the number of boilers to be burned by a signal from the steam flow rate detecting device. The values of F1 to F10 are set steam flow rates and are determined by the steam supply capacity of the installed boiler. In FIG. 3, the dotted line with an arrow shows the steam flow rate and the number of combustions when the measured steam flow rate is increasing, and the two-dot chain line with an arrow shows that the steam flow rate is decreasing. It shows the flow rate of steam and the number of burned fuels when there is. Hysteresis is provided when the steam flow rate is increasing and when it is decreasing to prevent frequent changes in the number of combustion units.

The number of boilers to be burned is determined by the measured steam flow rate, the other boilers are stopped, and the number of high combustion and low combustion are determined by the measurement value from the pressure detection device. Since the number of boilers that burns can be 11 ways from 0 to 10, 11 types of combustion patterns from 0 to 10 are set respectively. FIG. 4 shows a combustion pattern when the number of burned boilers is 6, and the other combustion patterns are omitted. First, the number of combustion units is determined from the steam flow rate. When the determined number of combustion is 6, the combustion pattern of 6 shown in FIG. 4 is adopted. Seven combustion amounts I to VII are defined in the combustion pattern of the six units, and the remaining four boilers are stopped regardless of the steam pressure. Next, the combustion amount, that is, the number of high combustion and the number of low combustion are respectively determined. When the detected pressure is equal to the target set pressure Ps, the combustion amount IV is set, and the high combustion boiler 3
If the detected pressure is low, increase the number of high-combustion units such as combustion amounts V, VI, and VII to decrease the number of low-combustion units. Conversely, if the detected pressure is high, Increase the number of low-combustion units and decrease the number of high-combustion units such as the quantities III, II, and I. With respect to pressure changes, by changing the combustion amount, that is, the ratio of the number of high-burning units to the number of low-burning units, the amount of steam generated is changed to adjust the steam pressure, and the number of units burned until the steam flow rate changes. By not changing
Fluctuations between combustion and stop of the boiler are reduced, and the number of times of starting and stopping can be reduced.

[0011]

EFFECTS OF THE INVENTION By installing the steam accumulator, it is possible to prevent a rapid change in pressure against a rapid change in steam load, and it is possible to supply a stable steam. Furthermore,
By determining the number of burning boilers based on the signal from the steam flow rate detection device and determining the combustion amount based on the signal from the pressure detection device, the appropriate number of burning boilers and combustion state according to the steam load are determined. Since the number of combustion units is determined by the absolute amount of required steam, smooth follow-up of load can be performed smoothly, and the number of combustion units is not changed until the steam flow rate changes. Is reduced, high-efficiency operation becomes possible as a whole, and the life of the boiler can be extended by reducing the number of times of starting and stopping.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional technique.

[Fig. 3] An example of a relationship diagram between the steam flow rate and the number of burning units when the number of installed units is 10.

[Fig. 4] Example of combustion pattern when the number of burners is 6 1 Through-flow boiler 2 Steam accumulator 3 Steam flow rate detector 4 Pressure detector 5 Steam header 6 Controller

Claims (2)

(57) [Claims] Claims: 1. A plurality of once-through boilers of three-position combustion control of stop, low combustion, and high combustion are installed, and a steam header is provided for collecting steam generated in each boiler and distributing the collected steam. A multi-can installation system for boilers, in which the header and each boiler are connected by steam pipes, and the steam pipes or steam headers are provided with a steam collecting part that collects and flows the steam generated in all the boilers. In the above, a steam flow rate detection device for detecting the steam flow rate at the steam gathering part and a pressure detection device for detecting the steam pressure at the steam gathering part are provided, and the number of burning boilers is determined by a signal from the steam flow rate detecting device. The amount of combustion, that is, the number of boilers that perform high combustion and the number of boilers that perform low combustion of the determined number of boiler combustions are determined by the signal from the pressure detection device. Units control method of once-through boiler, wherein. 2. The method for controlling the number of once-through boilers according to claim 1, wherein a steam accumulator is provided in the middle of the steam pipe connecting the steam header and the boiler, and the steam flow rate is detected at the collecting portion of the steam downstream of the steam accumulator. A device and a pressure detection device are provided, the number of boilers burned is determined by a signal from the steam flow rate detection device, and the combustion amount of the boiler is determined by a signal from the pressure detection device. A method of controlling the number of once-through boilers, characterized by determining the number of boilers and the number of boilers that perform low combustion.