JPH0344961Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is an automatic boiler number control system that determines the required number of boilers to burn in accordance with load fluctuations and automatically follows the load in a multi-can installation system where multiple boilers are installed. It is related to the device.

In the conventional multi-can installation system, a pressure regulator is installed in the steam header to grasp the load condition, and according to the load amount, the required number of units are sequentially shifted to combustion according to the startup order, and if there is a load change, An automatic boiler number control system was used in which boilers were fired and shut down in accordance with the load fluctuations, so that the number of boilers that could be fired was kept in line with the load. In this method, the number of boilers corresponding to the load is always fired, so efficient operation can be maintained, but if boiler combustion is stopped immediately due to a rise in pressure, the pressure will drop again in a short time. In order to start combustion again, we have to start with a pre-purge, and during that time the pressure drops too much, and the boiler goes into combustion, causing the pressure to rise too much. This was causing hunting due to combustion and shutdown due to excessive force.

The purpose of this invention is to solve the above problem.The steam header common to multiple boilers is equipped with a pressure regulator that monitors the load status. The required number of boilers are sequentially shifted to combustion according to the startup order,
In an automatic boiler number control device consisting of a number controller main body that fires and stops the boiler in accordance with the load fluctuation if there is a load change, a boiler stop signal is issued from the number controller main body. This is an automatic boiler number control device that is equipped with a delay circuit that works to issue an electrical stop signal to the boiler that is to be moved to the next combustion stage after the delay time has elapsed.

Below, as an example of this idea, boiler shutdown and
A device for controlling the number of boilers when four boilers are provided that performs three-position control of low combustion amount and high combustion amount will be described.

FIG. 1 is a flow sheet showing an embodiment of this invention. FIG. 2 is an explanatory diagram showing the relationship between steam pressure and the number of boilers fired.

FIG. 3 is an explanatory diagram showing the relationship between steam pressure and the number of boilers fired.

In the figure, H indicates a high combustion amount per can, L indicates a low combustion amount per can, and O indicates a stoppage.

As shown in Fig. 1, four boilers are installed side by side, and each boiler is connected to a steam header 1 common to each boiler through a steam pipe. The steam header 1 is provided with a pressure regulator 2 that replaces steam pressure fluctuations with linear resistance changes. A number controller main body 3 is provided connected to the pressure regulator 2 by a signal line, and the number controller main body 3 receives an electrical signal from the pressure regulator 2 and converts the signal into a signal as shown in FIG. It is configured to detect which of the nine stages the boiler is in and to issue a combustion signal and a stop signal to cause the required number of boilers to burn and stop in accordance with a preset starting order. Each boiler and the number controller main body 3 are connected by a signal line, and a delay circuit 4 is provided between them.
This delay circuit 4 is configured to delay the boiler by a set time and stop the boiler when it receives a stop signal from the number controller main body 3.

The operation of the above configuration will be explained. When the boiler is set to operation, the pressure regulator converts the steam pressure in the steam header into an electrical signal and sends it to the unit controller. The main body of the number controller detects which of the signals shown in FIG. 2 is the signal.
In other words, if the steam pressure is near the lower limit of the control pressure, the load will be considered large and all four units will have high combustion (HHHH in Figure 2).
signal to each boiler. As steam pressure increases, the number of boilers fired is reduced by half. At this time, the delay circuit that receives the signal to stop combustion in the boiler issues a signal to stop the boiler after a set time after receiving the stop signal, and stops the boiler. In FIG. 2, this delay circuit operates when the transition is from HHHL to HHH, from HHL to HH, from HL to H, and from L to O. When the steam pressure reaches O, which is near the upper limit of the control pressure, all boilers stop. Conversely, if the steam pressure decreases, it is assumed that the load increases, that is, the number of combustion units is insufficient, and increases by half a unit, ensuring that the steam pressure and the required number of combustion units are appropriate as set, preventing unnecessary boiler combustion, and reducing losses. Reduce. Here, when increasing the number of combustion engines, the delay circuit is not activated to prevent a decrease in responsiveness.

As shown in Figure 2, depending on the load,
Although we have explained the method of increasing the number of boilers burning one boiler at a time, the method is not limited to this. For example, as shown in Figure 3, as the load increases, the number of boilers with low combustion rate is increased, and then the number of boilers with high combustion rate is increased sequentially. The same applies to the method of shifting to the combustion amount. The delay circuit at this time is from HHHL to HHH and from LLL to
It operates when transitioning to LL, from LL to L, and from L to O (when the boiler stops).

When the combustion order pattern is not limited to those shown in FIGS. 2 and 3, but any order, a delay circuit can be provided to the signal for stopping the boiler.

As described above, the present invention stops the boiler by transmitting the stop signal for a set time after the stop signal is issued, so if the pressure increases within the delay time, the boiler will not stop, and if the load increases during that time, it can be handled. Also, if the load decreases further and the pressure increases, the pressure switch on the boiler side will turn it off (the signal for controlling the number of units and the signal from the boiler pressure switch are connected in series to form an AND circuit), so the boiler side will not rise abnormally. In other words, it is possible to provide stable boiler pressure control even in the face of short-term subtle fluctuations in load.

In addition, the smaller the number of boilers in operation, the more easily they are affected by the load, so the delay time is set to 1 for the number of boilers in operation.
It is desirable to increase the number of boilers in the following order: >Number of boilers in operation 2>Number of boilers in operation 3>Number of boilers in operation 4.

Since the present invention is constructed as described above, it is possible to provide an automatic boiler number control device with extremely high stability.

[Brief explanation of the drawing]

Figure 1 is a flow sheet of one embodiment of the present invention, Figure 2 is an explanatory diagram showing the relationship between steam pressure and the number of boilers fired, and Figure 3 is another explanatory diagram showing the relationship between steam and the number of boilers fired. be. 1 is the steam header, 2 is the pressure regulator, 3 is the number controller body, 4 is the delay circuit, H is the high combustion amount of one can, L is the low combustion amount of one can, and O is the stop.

Claims (1)

[Scope of utility model registration request] A pressure regulator 2 is installed in the steam header 1 that is common to multiple boilers installed, and the required number of boilers are sequentially shifted to combustion according to the start order according to the load amount, thereby eliminating load fluctuations. In an automatic boiler number control device comprising a number controller main body 3 that fires and stops the boilers according to load fluctuations, if any, a predetermined delay time from the time when a boiler stop signal is issued from the number controller main body. 1. An automatic boiler number control device characterized by being provided with a delay circuit 4 which operates to issue an electrical stop signal to the boiler to be moved to the next combustion after the lapse of time.