JPH0523921Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a water supply control device that is effective in preventing a drop in can water level in a boiler system when the steam load suddenly increases. .

[Conventional technology]

Generally, in a boiler system, multiple electrode rods are installed in a water level control cylinder that communicates with the inside of the can, and the electrode rods detect the water level inside the can, and the water pump is turned on and off based on the detection signal. A water supply control method is used.

For example, in the water supply control device shown in FIG. 2, two electrode rods, a first water level detector 3' and a second water level detector 4', are provided in the water level control tube 2', The water supply pump 5' is turned on and off by the signal.
The operation is controlled and the burner 10' is stopped in response to a signal from the second water level detector 4' to prevent overheating of the can. In other words, after the water level reaches the detection end of the first water level detector, the water pump is stopped after a set time T ₃ (for example, several seconds), the water level decreases due to evaporation, and the water level leaves the detection end of the first water level detector. After the set time T ₁ (for example, several tens of seconds), the water supply pump is operated, and the water level returns to the first water level detector even after the water level leaves the detection end of the second water level detector and the set time T ₄ , which is longer than T ₁ , has passed. Cuts off burner combustion when not in use. In the figure, 8' is a combustion control electromagnetic valve for controlling fuel supply, and 6' is a water supply controller for controlling the water supply described above.

[The problem that the idea attempts to solve]

In the above-mentioned water supply control device, when the steam load is stable, the water supply pump starts operating after the set time T ₁ has elapsed before the water level turns off the second water level detector.
Although there is no problem, the following problems occur when the steam load increases rapidly.

That is, when the steam load suddenly increases, the water level falls at a faster rate, and a situation occurs in which the water level turns off the first water level detector and immediately turns off the second water level detector. Then, setting time T ₁ and setting time T ₄
The count starts almost simultaneously, and a few seconds after the water pump starts operating, the combustion cut due to the low water level is performed. In this case, there is no abnormality in the water supply system, and if the water level returns to the first water level detector, operation can be continued, and the situation is not so urgent that the boiler must be stopped. This results in unnecessary combustion cuts, which is undesirable in terms of boiler maintenance and management. As a countermeasure, it is possible to lengthen the set time _T4 , but this is difficult due to restrictions on preventing overheating of the can.

[Means to solve the problem]

In view of the above-mentioned problems, this idea uses the logical sum of the signals from the first water level detector and the second water level detector as a condition for operating the water pump. , a first water level detector and a second water level detector are arranged in a water level control cylinder communicating with the can body so that the detection end of the first water level detector is located above the detection end of the second water level detector. , the water pump is activated by the signals from these water level detectors.
In the ON-OFF operation configuration, the water level is the first
At the earlier timing of the set time T ₁ counted from the time when the water level left the detection end of the water level detector or the set time T ₂ counted from the time the water level left the detection end of the second water level detector. It is characterized by the provision of a water supply controller that operates the water supply pump.

[Effect]

According to the above-mentioned configuration, the condition for operating the feedwater pump is the logical sum of the time T1 after the water level leaves the detection end of the first water level detector and the time _T2 after the water level leaves the detection end of the _second water level detector, and the timing of whichever of _T1 or _T2 is reached first is adopted. Therefore, even when the steam load increases suddenly, by setting the set time _T2 to a short time, the feedwater pump is operated immediately when the water level leaves the detection end of the second water level detector even if the set time _T1 of the first water level detector has not been reached.
This makes it possible to start water supply early before the water level drops abnormally.

〔Example〕

Hereinafter, preferred embodiments of this invention will be described based on the drawings. In the figure, reference numeral 1 denotes a boiler, in which a water level control tube 2 for detecting the water level inside the boiler is connected so that the upper part communicates with the steam part of the boiler and the lower part communicates with the water part of the boiler. ,
They are connected through a connecting pipe 7. Above water level control tube 2
has a first water level detector 3 and a second water level detector 4 inside.
It has two electrode rods, of which the detection end of the first water level detector is located above the detection end of the second water level detector. or,
The detection end of the first water level detector is located at a suitable position to maintain the dryness of the steam generated from the boiler, while the detection end of the second water level detector is located at a suitable position to prevent overheating of the can body. It is located near the lowest water level.

Reference numeral 6 denotes a water supply controller, which operates to turn on and off the water supply pump 5 according to a preset timing based on a signal from the water level detector. Reference numeral 8 denotes a check valve inserted into the water supply line, which prevents canned water from flowing back due to the internal pressure of the boiler when the water supply pump is stopped.
Reference numeral 9 denotes a blow valve, which is opened when removing impurities accumulated in the boiler or blowing can water to prevent concentration of can water. A fuel control electromagnetic valve 11 is inserted into the fuel supply line connected to the burner 10, and its opening/closing operation is controlled by a signal from a steam pressure detection means (not shown). The combustion of the fuel is controlled.

As a specific example of water supply control using the above configuration, the water level reaches the first water level detector 3 and
After _T3 , the water supply pump is stopped, and when the water level decreases due to evaporation and leaves the detection end of the first water level detector and a set time _T1 has elapsed, the water supply pump is started to operate. However, even if the set time _T1 is not reached, the water supply pump is operated when the water level leaves the detection end of the second water level detector 4 and the set time _T2 has elapsed.
In addition, if the water level suddenly drops due to a defective check valve in the water supply line, incorrect operation of the blow valve, or extremely low capacity of the water supply pump, the water level may leave the second water level detector even after the set time T ₄ has passed. If the water level does not return to the level of the first water level detector, combustion of the burner is stopped to prevent overheating of the can body.

[Effect of idea]

Since this invention has the above configuration, by using both the setting time T ₁ of the first water level detector and the setting time T ₂ of the second water level detector, the water supply pump is activated at the earlier timing. Even when the steam load suddenly increases, the water supply pump can be started quickly to prevent the water level in the tank from dropping. Therefore, unnecessary combustion cuts due to temporary low water levels are eliminated, wasteful heat radiation loss is suppressed, overheating of the can body is prevented, and boiler maintenance management becomes easier, which has many practical effects. be able to.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of this invention,
FIG. 2 is an explanatory diagram of a conventional embodiment. DESCRIPTION OF SYMBOLS 1... Boiler, 2... Water level control tube, 3... First water level detector, 4... Second water level detector, 5... Water supply pump, 6... Water supply controller.

Claims (1)

[Scope of utility model registration request] A first water level detector 3 and a second water level detector 4 are installed in a water level control tube 2 that communicates with the can body, so that the detection end of the first water level detector is located above the detection end of the second water level detector. In a configuration in which the water supply pump 5 is turned on and off by the signals from these water level detectors, the set time T ₁ counted from the time when the water level leaves the detection end of the first water level detector and the water level at the first 2. Water supply control for a boiler, characterized in that it is provided with a water supply controller 6 that operates the water supply pump at the timing of the earlier of a set time _T2 counted from the time of leaving the detection end of the water level detector. Device.