JP2972125B2 - Small once-through boiler with feedwater pump capacity detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply control device for a small once-through boiler for controlling water supply using one water level detecting electrode rod and a timer device.

[0002]

2. Description of the Related Art The presence or absence of water at a height E1 is detected by one water level detection electrode rod E1 provided in a water level detection cylinder, and the presence of water is detected by the electrode rod E1 before water supply. There is a water supply control device for a small once-through boiler that starts water supply after a lapse of a timing time TA and stops the water supply when the electrode rod E1 detects the presence of water by the water supply to control the water level. The above water supply control device can control water supply with one electrode rod and timer device, so the structure of the water level detection part is simple and maintenance is easy, but direct water level detection is only the upper limit water level,
No lower water level was detected. In this case, since combustion should not be performed in a state without water, the electrode rod E3 is provided at a position lower than the electrode rod E1 in order to detect a water level abnormality, and when the electrode rod E3 detects absence of water, When the detection of the absence of water from the electrode rod E1 continues for the abnormality detection time or longer, the water level is abnormal and the combustion is stopped. The capacity of the water supply pump decreases during use.If the capacity decreases, the waterless detection time increases, but if the water level drops significantly, the waterless detection time increases, and the lower water level is detected. Since it was not performed, it was not possible to distinguish which of the causes, and it was not possible to detect a decrease in the capacity of the feedwater pump.

[0003]

The problem to be solved by the present invention is to detect the capability of the water supply pump and to detect the deterioration of the capability at an early stage in the water supply control using one electrode rod and a timer device. It is an object of the present invention to provide a small once-through boiler having a feed water pump capacity detecting device capable of detecting the water supply.

[0004]

A water supply pipe provided with a water supply pump on the way is connected to a lower part of the boiler, and a water level detecting cylinder is connected to a steam part on the upper part of the boiler and a canister part on the lower part of the boiler. A water supply pump control device having a timer device connected to the water level detection electrode rod E1, the electrode rod E1, and the water supply pump is provided, and the water supply pump control device starts to operate the timer device more than when the electrode rod E1 detects no water. In the small once-through boiler, the operation of the feed water pump is started when the water supply timing time TA elapses, the water level rises, and the operation of the water supply pump is stopped after the electrode rod E1 detects the presence of water. As soon as E1 detects the absence of water, the operation of the water supply pump is started, and the water level return time TB until the electrode rod E1 detects the presence of water is detected. Is connected to a water supply pump control device, which detects an abnormality of the water supply pump by comparing the preset water level return time with a preset reference water level return time. When it becomes longer than the return time, it is detected as an abnormality of the water supply pump.

[0005]

[Function] To prevent erroneous detection of the water level due to shaking of the water surface,
If the same water level signal is not output continuously for a certain period of time, the electrode rod E1 does not detect the water level, so that the water level at which the absence of water starts to be detected and the water level at which the presence of water starts to be detected are different. During normal water supply control, since the lower limit water level is not known, the water level difference between when the water supply pump is operated and when the electrode E1 detects the presence of water is unknown, but water is supplied as soon as the electrode E1 detects no water. In this case, the water level difference until the presence of water is detected is known. If the capacity of the water supply pump is reduced, the time required to supply a certain water level difference becomes longer. Therefore, the water supply time is measured by measuring the water level return time TB and comparing it with a preset reference water level return time. The capacity of the pump can be detected.

[0006]

An embodiment of the present invention will be described with reference to the drawings.
The boiler (1) is connected between the upper header (2) and the lower header (3) by a number of water pipes (4), and the water supply pipe (5) is connected to the lower header.
Connected to (3). Electrode E1 for detecting water level inside
(6) and a water level detection cylinder (8) provided with an electrode rod E3 (7)
Communicates with the upper header (2) and the lower header (3). Water pipe (4) by burner (11) installed on top of boiler (1)
The water supply to the boiler (1) when the water level is lowered by heating the steam and generating steam is provided in the middle of the water supply pipe (5) by the water supply pump control device (9) that has a timer device inside. The water supply pump (10) is operated. The electrode rod E1 (6) is used for water supply control, and combustion control is performed when the electrode rod E3 (7) detects the absence of water and when the electrode rod E1 (6) detects the absence of water and the abnormality detection time has elapsed. The device (12) stops the operation of the boiler as a water level abnormality. The feed water pump control device (9) is connected to the feed water pump capacity detecting device (13), and the feed water pump capacity detecting device (13) is connected to the feed water pump (10).
A reference water level return time is set for judging the performance of the engine to be normal, decreased, or abnormal.

In the case of normal water supply control, the water supply pump control device (9) starts the operation of the timer device when the water level drops and the electrode rod E1 (6) detects that there is no water, and the water supply timing time is controlled by the timer device. When it is detected that TA has elapsed, the operation of the water supply pump (10) is started. When the water level rises due to the water supply and the electrode rod E1 (6) detects the presence of water, the water supply pump (10) is stopped. When the presence of water is detected, if the absence of water signal is output for 1 second continuously, it is determined that the water level has dropped, and the detection of absence of water is started, and the absence of water is detected. If the signal indicating that water is present is output continuously for one second, it is determined that the water level has risen, and detection of the presence of water is started. Therefore, the actual water level becomes higher than the water level E1 and there is water. Is started, and the detection of the absence of water is started when the water level becomes lower than the water level E1.

[0008] The detection of the capacity of the water supply pump (10) is periodically performed depending on the operation time of the boiler.
When detecting the water supply capacity, the water supply pump capacity detection device (13) outputs to the water supply pump control device (9) immediately to operate the water supply pump (10) when the electrode rod E1 (6) detects that there is no water. Then, the operation of the timer device for TB detection is started. The water level rises due to the operation of the water supply pump (10), and the electrode rod E1
When (6) detects the presence of water, the operation of the water supply pump (10) is stopped, and the water level returns from the time when the electrode rod E1 (6), which was measured by the timer device, detects the absence of water to the time when the presence of water is detected. The value of the time TB is detected. Water level return time TB detected
And the reference water level return time preset in the feed water pump capacity detection device (13), and determines whether the value of the water level return time TB is normal, whether the capacity has begun to decrease, or whether there is an abnormality that requires the boiler to stop. Judge whether it is within the range and output.
For example, when the value of the water level return time TB is less than 30 seconds, the water supply pump is normal, when it is 30 seconds or more and less than 60 seconds, the water supply pump capacity is reduced, and when it exceeds 60 seconds, the water supply pump is abnormal. If it is determined that the pump is normal, it is returned to the normal water supply control.If it is determined that the water supply pump capacity is reduced, it is returned to the normal water supply control, but an alarm is output and repair is required. When the output is made and it is determined that the feedwater pump is abnormal, the boiler combustion is stopped.

[0009]

According to the present invention, even when the water level is controlled by one electrode rod, the capacity of the water supply pump can be detected, and when the capacity decreases, measures such as replacement of the water supply pump can be taken. Therefore, it is possible to prevent a sudden stop due to a decrease in feedwater pump capacity during the operation of the boiler.

[Brief description of the drawings]

FIG. 1 is a flowchart of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a water level change according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler 2 Upper header 3 Lower header 4 Water pipe 5 Water supply pipe 6 Electrode E1 7 Electrode E3 8 Water level detection cylinder 9 Water supply pump control device 10 Water supply pump 11 Burner 12 Combustion control device 13 Water supply pump capability detection device

Claims (1)

(57) [Claims] 1. A water supply pipe provided with a water supply pump on the way is connected to a lower part of a boiler, and a water level detecting cylinder for water level detection is connected to a steam part at an upper part of the boiler and a water level detector at a bottom part of a boiler lower part. A water supply pump control device having a timer device connected to the electrode rod E1, the electrode rod E1, and the water supply pump is provided, and the water level detection by the electrode rod E1 is performed when a signal indicating that there is no water is output continuously for a certain period of time. The absence of water is detected, and the presence of water is detected when a signal indicating the presence of water is output continuously for a certain period of time. The water supply pump control device is configured to operate the timer device more than when the electrode E1 detects the absence of water. In the small once-through boiler, the operation of the feedwater pump starts when the water supply timing time TA elapses and the water level rises and the electrode rod E1 detects the presence of water. As soon as the pole E1 detects the absence of water, the operation of the water supply pump is started. In that case, the time from when the electrode E1 detects the absence of water to when the presence of water is detected is detected as the water level return time TB. In addition, a water supply pump capacity detecting device that detects an abnormality of the water supply pump by comparing the detected value of the water level return time TB with a preset reference water level return time is connected to the water supply pump control device. Small once-through boiler with feedwater pump capacity detection device.