JP3107945B2 - Water level electrode rod abnormality determination 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 method for judging electrode rod abnormalities in a water level detecting device for detecting a water level in a boiler.

[0002]

2. Description of the Related Art The water level of a multi-tube type once-through boiler is provided with a water level detecting cylinder connected between an upper header and a lower header by a communication pipe, and a plurality of electrodes having different lengths are provided inside the water level detecting cylinder. A rod is installed, and the water level is detected based on information on the presence or absence of water detected by the electrode rod. The boiler can water is treated with soft water and chemicals. However, since the boil water is concentrated, electrolytic sludge adheres to the electrode rods, causing problems such as detecting the presence of water even when there is no water. Sometimes.
Therefore, when an inconsistency occurs in which the higher electrode rod detects the presence of water while the lower electrode rod detects the absence of water, an abnormality detection device that outputs an abnormality is provided.

[0003] In a boiler, the water surface may fluctuate significantly up and down due to fluctuations in load and the like. If the water level fluctuates up and down from the high water level to the low water level, the high-side electrode will remain wet and the low-side electrode will be empty before detecting water. There was a temporary inconsistency in detecting. This abnormality recovers as soon as the high-side electrode rod dries, but it is not determined whether the abnormality is temporary or permanent, and the electrode rod is detected when an inconsistent water level is detected. It was judged abnormal.
For this reason, there are cases where operation that should not be performed should be stopped, control that does not use the electrode rod determined to be abnormal, control, repair, and replacement of parts should be performed.

[0004]

SUMMARY OF THE INVENTION In the case of a temporary abnormality that recovers immediately, it is not determined that an abnormality has occurred, but an abnormality can be determined only when a permanent abnormality has occurred.

[0005]

Means for Solving the Problems When a low-level electrode detects that there is no water and a high-level electrode detects that water is present, when a water level contradiction occurs, the time during which the contradictory detection occurs is determined by the electrode rod. Count as abnormal time. Each time the electrode rod abnormality time reaches the set time, it is counted as the number of electrode rod abnormality detections.If the electrode on the higher side does not detect the absence of water before the number of electrode rod abnormality detections reaches the set number of times, an electrode rod abnormality is detected. Is output. If the high-side electrode detects that there is no water before the number of detected electrode-bar abnormalities reaches the set number, the abnormal electrode-rod time and the number of detected electrode-rod abnormalities are reset, and the abnormality determination is stopped. When the lower electrode detects the presence of water while the upper electrode does not detect the absence of water, only the electrode rod abnormality time is reset and the number of electrode rod abnormality detections is maintained. In this case, when the lower electrode detects again the absence of water, the abnormal time of the electrode is counted. Count the number of bar abnormality detections.

[0006]

[Effect] Each time the set time elapses while the lower electrode detects that there is no water and the higher electrode detects that there is water, it counts as the number of electrode rod abnormalities. If the high-side electrode does not detect the absence of water before reaching, it indicates that a permanent abnormality has occurred, and if it is a temporary abnormality, it will not be abnormal if it recovers immediately Therefore, continue driving.

[0007]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 3 is a schematic view, in which a water level detection cylinder (4) is provided in the middle of a connecting pipe connecting the upper header (2) and the lower header (3) in the boiler (1). Three electrode rods having different lengths are installed in the water level detection cylinder, and E1, E2, and E3 are set in order from the higher detection position. The signal of the electrode rod is sent to the water level control device (5), the control is determined, and the water supply pump (6)
Alternatively, it is sent to the combustion control device (7). Whether or not the signals output from the electrode rods are inconsistent is determined by a comparator (8) in the water level control device. In the case of inconsistency, the abnormal time measuring device (9) counts the electrode rod abnormal time. When the electrode rod abnormal time reaches a preset time set in advance, the abnormality detection frequency measuring device (10) counts the number of electrode rod abnormality detections. When the number of detections of the electrode rod abnormality reaches the set number, the abnormality of the electrode rod is output to the combustion control device.

FIG. 1 and FIG. 2 are time charts when the electrode rod temporarily becomes abnormal when the water level fluctuates greatly. First, a description will be given based on FIG. The electrode rod E1 detects the presence of water, and the electrode rod E2 does not detect the presence of water (detects the absence of water). The time is compared with the set time. Before the abnormal electrode rod time reaches the set time, the electrode rod E2 detects the presence of water, and when the contradiction is resolved, the abnormal electrode rod time is reset. In the figure, the water level inconsistency is detected once again thereafter. In this case, too, before the electrode rod abnormal time reaches the set time, the electrode rod E2 detects the presence of water and resets the electrode rod abnormal time. In this case, since the electrode rod E1 detects the absence of water, the output of the electrode rod abnormality is not performed in this case.

Next, a description will be given with reference to FIG. Electrode E1
Detects the presence of water, counts the time when the electrode E2 performs an inconsistent output that does not detect the presence of water as the electrode rod abnormal time, and compares the electrode rod abnormal time with the set time. If the electrode rod abnormal time is longer than the set time, it is counted as the number of electrode rod abnormality detections. When the electrode E2 detects the presence of water due to the rise of the water level, the inconsistency of the water level is resolved. Therefore, the abnormal time of the electrode is not set during the period, and the abnormal time of the electrode is reset. The number of detected electrode bar abnormalities is held without resetting, and when the electrode bar abnormal time becomes longer than the set time, it is added to the previous number of detected electrode bar abnormalities and counted. When the number of times of abnormality detection reaches the set number, an electrode rod abnormality is output. If the electrode E1 detects that there is no water before the number of times of detecting the electrode rod abnormality reaches the set number, the abnormal time of the electrode rod and the number of times of detecting the electrode rod abnormality are reset.

【The invention's effect】

[0010] Since the electrode rod abnormality is temporary and the one which can be recovered immediately is not judged to be abnormal, there is no need for unnecessary boiler stoppage or repair.

[Brief description of the drawings]

FIG. 1 is a time chart of an embodiment in which an electrode rod abnormality is determined.

FIG. 2 is a time chart of another embodiment in which an electrode rod abnormality is determined.

FIG. 3 is a schematic diagram of one embodiment.

[Description of Signs] 4 Water level detection cylinder 5 Water level control device 6 Water supply pump 7 Combustion control device 8 Comparator 9 Abnormal time measuring device 10 Abnormal detection frequency measuring device

Claims (1)

(57) [Claims] 1. A multi-tube type once-through boiler comprising a boiler main body composed of upper and lower headers and a water pipe, wherein a water level detecting cylinder connected between an upper header or a steam separator and a lower header by a communication pipe. In the boiler that detects the water level by disposing a plurality of electrode rods of different lengths provided inside the water level detection cylinder and detecting the presence or absence of water in the boiler body, The upper electrode detects the absence of water, and the higher electrode, which has a higher detection position than the lower electrode, detects the presence of water.If an inconsistency occurs, the lower electrode detects that there is no water, and the upper electrode detects that there is no water. While the bar detects water,
The time is counted as the electrode rod abnormality time, and the number of times is counted as the electrode rod abnormality detection count every time the electrode rod abnormality time elapses the set time, and when the electrode rod abnormality detection number reaches the set number, the electrode is counted. It is to output a rod abnormality, when the lower electrode detects the presence of water, resets the electrode rod abnormal time, when the higher electrode detects the absence of water, the electrode rod abnormal time and the electrode. An abnormality determination method for a water level electrode rod in a multi-tube once-through boiler, wherein the number of times of rod abnormality detection is reset.