JP2975874B2 - Boiler water level control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler water level control method.

[0002]

2. Description of the Related Art When water level control is performed by detecting the presence or absence of water at a certain point based on the current value of one electrode rod provided in a water level detection device, water supply is performed when the output without water continues for a certain period of time. This is performed by starting the operation of the pump and stopping the operation of the water supply pump when there is an output indicating that there is water. Also,
The combustion of the boiler is controlled by the steam pressure. When the value of the steam pressure detected by the steam pressure detecting device becomes equal to or higher than the upper limit pressure, the combustion is stopped.

[0003] If the combustion is started at a low water level, the water pipe will be overheated. Therefore, when the start of combustion is output, the water level is checked, and if the water level detection device detects the presence of water, the ignition occurs. When the operation is performed and the absence of water has been detected, the water level rises due to the operation of the water supply pump performed after the detection of the absence of water for a certain period of time, and the ignition operation is performed after waiting for the detection of the presence of water. However, when the above control is performed, there is a problem that even if the start of combustion is output, combustion is not performed until the water level rises and no steam is supplied during that time, so that the steam pressure decreases.

[0004]

An object of the present invention is to prevent a decrease in steam pressure due to a delay in the start of combustion.

[0005]

[MEANS FOR SOLVING THE PROBLEMS] The presence or absence of water is detected by the current value of one electrode rod provided in the water level detection device, and when the absence of water is detected for a certain period of time, the operation of the water supply pump is started, and the presence of water is detected. The boiler stops the operation of the feedwater pump when the steam pressure is detected by the steam pressure detecting device, and stops the combustion when the steam pressure value is equal to or higher than the upper limit pressure, and outputs the start of combustion after performing the prepurge when the steam pressure value is equal to or lower than the lower limit pressure. The output of the start of combustion, and in the boiler which is performing control to start combustion when the presence of water is detected by the water level detection device, when the combustion is stopped due to a rise in steam pressure, The control is switched to control for keeping the water level at or above the water detection level so that the water level detection device can detect the presence of water.

[0006]

When the combustion is stopped due to the pressure increase, the boiler itself and the still water retain heat, and steam is generated even without combustion, so that the water level decreases. By switching to the control that activates the water supply pump immediately after the water level detection device detects that there is no water, the water level is maintained above the water presence detection position, and the water level detection device always detects the presence of water. When the start of combustion is output, the ignition operation can be performed immediately because the presence of water is detected, and the start of combustion is not delayed, so that a decrease in steam pressure can be prevented.

[0007]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a boiler embodying the present invention, and FIG.
Shows changes in water level and combustion state in the embodiment of the present invention. The water level detecting device 1 is connected to the steam section and the canned water section of the boiler, and is provided with an electrode rod 2 for detecting the presence or absence of water at the water level E1. The water level signal detected by the water level detection device 1 is sent to the water level control device 3, which controls the start and stop of the water supply pump 4. The steam generated by heating the water pipe 7 connecting the upper header 5 and the lower header 6 is taken out through a steam separator 8 connected to the upper header 5, and the steam pressure is detected by a steam pressure detector 9. Is detected. The combustion control device 10 uses the steam pressure signal detected by the steam pressure detection device 9 and the water level signal detected by the water level detection device 1 to generate the combustion device 11.
Control.

[0008] The combustion control will be described. Combustion device 11
Is controlled by the steam pressure output from the steam pressure detecting device 9, the combustion pressure increases by performing the combustion, and when the steam pressure exceeds the upper limit pressure, the combustion control device 10 controls the combustion of the combustion device 11. It is stopped, and the combustion stop signal is also output to the water level control device 3. When the supply of steam stops and the steam pressure falls below the lower limit pressure, the combustion control device 10 prepares to start combustion. When starting the combustion, a preparation period for performing the prepurge is required, and after the prepurge is completed, the combustion start output is performed and the water level detection device 1
After confirming that water is output from, the ignition operation is performed.

Next, the water level control will be described. When the water level becomes lower than E1 and a signal indicating that there is no water is sent from the water level detection device 1 to the water level control device 3, a timer provided in the water level control device 3 is activated, and the water absence detection time elapses a set time (T1). Then, the operation of the water supply pump 4 is started. When the water level rises due to the operation of the water supply pump 4 and a signal indicating that there is water is sent from the water level detection device 1 to the water level control device 3, the operation of the water supply pump 4 is stopped. However, when the combustion stop signal output from the combustion control device 10 is input, the water level control device 3 switches to the control for starting the operation of the water supply pump 4 as soon as no water is output from the water level detection device 1, Always keep the water level above E1. In order to prevent the presence of water from being detected due to instantaneous fluctuations in the water level, such as fluctuations in the water surface, the output with water is performed after a certain confirmation time has elapsed since the water level became equal to or higher than the water level E1.

[0010]

According to the present invention, when the combustion is stopped due to an increase in steam pressure, control is performed to keep the water level at or above E1. Therefore, combustion can be started immediately when the start of combustion is output due to a decrease in steam pressure. Since there is no longer a waiting period for waiting for a rise in water level as in the conventional case, it is possible to suppress a significant decrease in steam pressure.

[Brief description of the drawings]

FIG. 1 is a configuration diagram according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a change in steam pressure in one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a change in steam pressure in a conventional case.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water level detection apparatus 2 Electrode rod 3 Water level control apparatus 4 Water supply pump 5 Upper header 6 Lower header 7 Water pipe 8 Gas-water separator 9 Steam pressure detection apparatus 10 Combustion control apparatus 11 Combustion apparatus

Claims (1)

(57) [Claims] 1. A single electrode rod provided in a water level detection device detects the presence or absence of water at a certain point, controls the operation of a water supply pump according to the water level, and is detected by a steam pressure detection device. When the steam pressure exceeds the upper limit pressure, the combustion is stopped, and when the steam pressure falls below the lower limit pressure, the boiler starts burning. When the combustion is stopped due to the increase in steam pressure, the control is switched to the control to start the operation of the water supply pump as soon as the water level detection device detects that there is no water. Boiler water level control method.