JPH0692804B2 - Boiler automatic number control system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic platform control device having improved response to load in a multi-can installation system in which a plurality of boilers are installed.

[Conventional technology]

Generally, in a multi-can installation system where multiple boilers are installed, a pressure detector is installed in the steam header to grasp the load condition, and the required number of units are sequentially switched to combustion according to the load amount, if there is a load fluctuation. In accordance with this, an automatic number control system is adopted that follows the load by burning and stopping the boiler. According to this method, since an appropriate number of boilers can be burned according to the load amount, it is possible to maintain high efficiency operation.

[Problems to be solved by the invention]

However, in the actual operation of the boiler, even if the combustion symbol is entered, the boiler performs pre-purge for a predetermined time (about 15 seconds) to scavenging the inside of the furnace for safety.
Until then, it cannot move to combustion. Therefore, the steam pressure is excessively lowered due to the time delay, or the boiler is unnecessarily activated due to the excessive decrease of the pressure, and hunting of the combustion state is likely to occur.

[Means for solving problems]

In view of the above problems, the present invention can supply a stable amount of steam by compensating for the shortage of the amount of steam by forcibly setting another boiler in a low combustion state to a high combustion state during the pre-purge time. A plurality of boilers (1) are installed, and a pressure detector (3) is provided on the steam header (2) common to these boilers to detect the load condition.
In the configuration in which a unit controller (4) for connecting and disconnecting the required number of boilers according to the load amount is connected by the signal from the pressure detector, a new command from the unit controller is used. If there is another boiler in a low combustion state until the boiler in the stopped state is started and transitions to combustion, forced high combustion to force the other boiler in the low combustion state to a high combustion state It is characterized in that a transmission circuit (6) for emitting a signal is provided.

〔Example〕

Preferred embodiments of the present invention will be described below with reference to the drawings. In the figure, (1) is a boiler with a plurality of units installed. Each of these boilers is connected by steam pipes to a common steam header (2). The steam header is provided with a pressure detector (3) for detecting the steam pressure inside the steam header, and this is preset by the unit controller (4) based on the pressure signal. The required number of boilers are burned and stopped according to the startup sequence, and the load is controlled to follow the load. Reference numeral (5) is a comparison operation circuit of the unit number controller, which operates to determine the required number of combustion units based on the pressure signal and output an output signal for combustion control. (6)
Is a forced high-combustion transmission circuit for issuing a forced high-combustion signal for forcibly shifting the boiler to the high-combustion state for a predetermined time when another boiler in the low-combustion state exists.

An example of combustion control of a multi-can installation system with three boilers (NO.1, NO.2, NO.3) installed will be explained.
When a three-position control-type boiler that performs combustion control by three positions of a stopped state, a low combustion state (L), and a high combustion state (H) is used, as shown in FIG. It is set to the operating state. At the stage where the steam pressure is the lowest, all three cans are in a state of high combustion (HHH), and when it comes to the next pressure stage, the NO.3 boiler goes from H to L and shifts to the HHL state. When the pressure is further increased, the boilers of NO.2 and NO.1 are successively changed from H to L, and become the state of LLL. Then, when the pressure is further increased, the combustion is stopped in the order of NO.3, NO.2, NO.1, and when the upper pressure stage is reached, all the cans are stopped.
In addition, when the steam pressure drops, it is set to start in the reverse order to the above order.

In this way, the number of boilers appropriate for the load amount is operated, but the load amount is not constant but repeats fluctuations. Therefore, when the load amount rapidly increases and the steam pressure sharply decreases, the above-mentioned problems occur, for example, when the state changes from the LL state to the LLL state. However, according to the present invention, since the combustion control as shown in FIG. 3 can be performed, the above-mentioned problems can be solved. When a signal instructing the NO.3 boiler to start is output from the LL state, the NO.2 boiler already in the low combustion state is forcibly shifted to the high combustion by simultaneously outputting the forced high combustion signal. When the NO.3 boiler ends pre-purge and starts low combustion, the NO.2 boiler is returned to the low combustion state. By doing so, it is possible to compensate for the shortage of the steam amount due to the time delay until the NO.3 boiler starts combustion.

It should be noted that since the NO.2 boiler does not immediately enter the evaporating state even if it starts burning, the NO.3 boiler may be extended for a predetermined time to a high combustion state.
It is also possible to control the L state to continue as it is. Further, by predicting the degree of pressure decrease after a predetermined time, a compulsory high combustion signal may be issued to a plurality of boilers that are already in a low combustion state, if necessary.

〔The invention's effect〕

Since the present invention is configured as described above, the responsiveness to a load is improved, and even if a sudden load change occurs, excessive decrease in steam pressure or hunting does not easily occur. Therefore, according to the present invention, it is possible to provide an automatic number-of-units control device for a boiler, which has excellent responsiveness and can always supply a stable steam amount.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of an automatic boiler number control system according to the present invention, FIG. 2 is a graph showing an embodiment of an operation pattern of the boiler with respect to steam pressure according to the present invention, and FIG. It is a time chart which shows one Example of combustion control in the invention. (1) ... Boiler, (2) ... Steam header (3) ... Pressure detector, (4) ... Unit controller (5) ... Comparison operation circuit (6) ... Forced high combustion transmission circuit

Claims (1)

[Claims] 1. A plurality of boilers (1) are installed, and a pressure detector (3) for grasping a load state is connected to a steam header (2) common to these boilers. In the configuration provided with the unit number controller (4) that burns and stops the required number of boilers according to the load amount by the signal, the boiler in the stopped state is started by a new command from the unit number controller, and combustion is started. When there is another boiler in a low combustion state until the transition, a transmitting circuit (6) for issuing a forced high combustion signal for forcibly bringing the boiler into a high combustion state is provided. Boiler automatic number control system.