JP2668724B2 - Boiler water level control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to two water level detectors for performing low water level control for changing steam quality and stopping heating when the water level drops abnormally. The present invention relates to a boiler water level control device.

(Prior art) Conventionally, water level control of a boiler is performed using a pair of water level detectors for starting and stopping a feedwater pump and a low water level detector for shutting off a heat source (combustion device). Therefore, the control water level was at one position and the steam quality was constant.

In order to change the steam quality, it is necessary to provide a large number of water level detectors and switch between the two water level detectors required for the control, and this requires an increase in the number of water level detectors, which is uneconomical. In addition, the maintenance and inspection of the device become complicated.

(Purpose of the Invention) The present invention solves the problems pointed out in the above-mentioned section of the prior art, and without changing the water level detector, changes in steam quality, and It is an object of the present invention to provide a water level control device that enables the accompanying optimum water level control and low water level control that shuts off a heat source.

(Means for Achieving the Object) As means for solving the above-mentioned objects, the present invention provides a water level detector and a low water level detector in a boiler, a water supply pump in a boiler water supply passage, and a water level detector. Circuit A that outputs a water supply pump OFF signal by the water level detection signal and outputs a water supply pump ON signal after the set time t1 after the water level detection inability signal from the water level detector, Water supply pump ON signal by the water level inability signal from the water level detector B, which outputs the feed pump OFF signal after the output or after a set time t2 from the re-output of the water level detection signal from the water level detector, the changeover switch between the circuit A and the circuit B, and the water level from the low water level detector And a circuit for shutting off the heat source by the undetectable signal.

(Operation) In the present invention, the following operations are obtained by the above means.

When set to the circuit A with the changeover switch of the control device, the water level during boiler operation is the highest water level at which the water level detector starts to output the water level detection signal, and the lowest water level at which the water level detector outputs the water level undetectable signal. The water level is reduced by the amount evaporated during the set time t1 from the starting water level.

When the water level during the boiler operation is set to circuit B by the changeover switch of the control device, the set time t2 is The lowest water level is the water level at which the water level detector starts to output a water level undetectable signal at the water level that has risen only by removing the evaporation from the supplied water during the period.

If the water level drops abnormally and the low water level detector becomes unable to detect the water level, the output to the heat source is immediately shut off to stop heating and prevent empty heating.

When the circuit A is set by the changeover switch, the water level during the boiler operation is kept in a low range and the dryness of the steam becomes high. When the circuit B is set, the water level during the boiler operation is kept in a high range and the steam level is kept high. Dryness is reduced. Using a water level detector for starting and stopping the water supply pump and a low water level detector for performing low water level control, by switching between the circuits A and B, two types of steam supply with different dryness and heating can be performed. Low water level control to shut off can be performed.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of one embodiment of the present invention. First
In the figure, 1 is a boiler, 2 is a water level detector, 3 is a low water level detector, 4 is a feedwater pump, 5 is a heat source, 6 is a control device, 7
Is a changeover switch.

The water level detector 2 and the low water level detector 3 are attached to the water level detection tube 10 which is communicated with the steam communication pipe 8 and the water communication pipe 9 of the boiler 1, but may be directly attached to the boiler 1. . The heat source 5 is an electric heater or a combustion device.

The control device 6 outputs a water supply pump 4OFF signal in response to the water level detection signal from the water level detector 2, and outputs a water supply pump 4ON signal after a set time t1 after the water level detection inability signal from the water level detector, a water level detector The feedwater pump 4ON signal is output according to the water level undetectable signal from 2 and the set time t after output.
It is composed of a circuit B for outputting a feed water pump 4 OFF signal after 2 days, a switch for switching between the circuit A and the circuit B, and a circuit for shutting off the heat source by a water level detection disable signal from the low water level detector 3.

If steam with a high degree of dryness is required, the circuit A is set by the changeover switch of the control device. When the boiler is started (power switch ON), the water supply pump operates until the water level detector detects the water level to raise the water level. When the operation switch is turned on, the heat is output to the heat source and heating is started. When the water level falls and the water level detector becomes in a state where the water level cannot be detected, the measurement of the elapsed time is started.
When the set time t1 has elapsed, the feed pump ON signal is output,
When the water supply pump is operated to supply water again and the water level detector detects the water level, a water supply pump OFF signal is output and the water supply pump stops.

On the other hand, if the water level drops abnormally and the low water level detector becomes unable to detect the water level, the output to the heat source is immediately shut off and heating is stopped. Thereafter, when the low water level detector detects the water level by supplying water, the water level is output to the heat source to perform heating.

When it is not necessary to use steam having a high degree of dryness, the circuit B is set by a changeover switch of the control device. When the boiler is started (power switch is ON), the water supply pump is operated to supply water. When the water level detector starts water level detection, the elapsed time starts to be measured, and the water supply pump continues to operate until the set time t2 elapses. You. When the operation switch is turned on, the heat is output to the heat source and heating is started. When heating causes evaporation, the water level drops and the water level detector becomes unable to detect the water level. Immediately the operation is output to the water supply pump to start water supply again, and the elapsed time is measured from the time of output. And
When the set time t2 has elapsed, a water supply pump OFF signal is output, and the water supply pump stops. On the other hand, the low water level control is the same control as the circuit A.

(Effect of the Invention) Two water level detectors, a water level detector for starting and stopping a water supply pump and a low water level detector for detecting a low water level, provide two-level water level control and low water level control for shutting off heating. Becomes possible,
It is possible to supply two types of steam having different dryness without increasing the number of water level detectors and complicating maintenance and inspection.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a boiler water level control device according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Boiler 2 ... Water level detector 3 ... Low water level detector 4 ... Water supply pump 5 ... Heat source 6 ... Control device 7 ... Changeover switch

Claims (1)

(57) [Claims] A boiler has a water level detector and a low water level detector.
The water supply pump 4 is installed in the boiler water supply passage, the water supply pump 4OFF signal is output according to the water level detection signal from the water level detector 2, and the water pump 4ON signal is output after the set time t1 after the water level detection unavailable signal from the water level detector 2. A, the water supply pump is turned on by the water level detection disable signal from the water level detector 2.
A circuit B for outputting a signal and outputting a feed water pump 4 OFF signal after a set time t2 after the output or re-output of the water level detection signal from the water level detector 2, a changeover switch 7 between the circuit A and the circuit B,
And a circuit for shutting off a heat source in response to a water level detection impossible signal from the low water level detector 3.