JP2549631Y2 - Boiler water level control device - 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 level control device for a boiler such as a once-through type small boiler, and more particularly to a water level control device for a low combustion and high combustion type (heat load type).

[0002]

As a conventional throughflow heat load corresponding type of water <br/> position control system of the boiler, respectively at low combustion and during high燃生switch the water level control in the time of low combustion state and a high combustion Controlling the water level to a suitable level ( JP-A-54-103905 )
It has been known. In this conventional example, when the pressure inside the can is high,
During high combustion, the second electrode and the third electrode (or the first electrode and
And the third electrode) during the low combustion.
(Or the first and fourth electrodes) to control the water level respectively
When the internal pressure of the can is low, the first electrode and
And the second electrode and the third electrode during low combustion.
(Or the first and third electrodes) to control the water level respectively
I do.

[0003]

[Devised Problems to be Solved] According to the conventional example of the above
For example, three electrodes are used for high and low combustion control.
The problem is that the number of electrodes used increases.
You. Also, in this conventional example, if an electrode abnormality occurs,
Cannot control backup water level during combustion and low combustion
There is a problem that. In this regard, some water level detection
When the pole becomes abnormal, switch to another water level detection electrode
The technology to perform backup control is disclosed in
It is publicly known from Japanese Patent Application Publication No. However, this known battery
Backup technology, high combustion and low combustion
Even when simply applied to a compatible water level control device,
Appropriate backup water during low combustion, especially during low combustion
There is a problem that position control cannot be performed. That is, the above-mentioned battery
In the first embodiment of the known technique, it is determined that the electrode S is abnormal.
In this case, control by the electrode M and the electrode L
If M is determined to be abnormal, the control by electrode S and electrode L
In the second embodiment, it is determined that the electrode S is abnormal.
Control is performed by the electrodes D and M,
If M is determined to be abnormal, the control by electrode D and electrode S
It is to control. Backup system of the first embodiment
According to control, when the electrode S is abnormal, the water level lower than the electrode S
Because it is controlled by the detecting electrode M and electrode L,
During normal operation, the water level in the can is lower than normal,
There is a risk of heat. Also, the backup control of the second embodiment
According to the above, when the electrode S or the electrode M is abnormal, the water level detector
However, in order to control by electrode D in a can body,
Water level detection is directly affected by the boiling state of
As the operating time elapses, the water level in the can drops,
In some cases, overheating of the water pipe may occur. This consideration
The idea is to consider the above issues,
Water level control for low combustion can be performed, and
In the event of a pole failure, appropriate high and low combustion
The purpose is to be able to perform appropriate water level control.

[0004]

SUMMARY OF THE INVENTION The present invention relates to an upper header.
A can body with a substantially vertical water pipe 23 connected between 21 and the lower header 22
20, a water level controller 29 is communicatively connected before SL between upper header 21 and lower header 22, a burner 24 for heating the water pipe 23 to at least the high combustion and low combustion, water to the boiler body 20 in steam boiler and a pump 25 for supplying it
To detect a sequentially higher predetermined water level in the water level controller 29.
First water level detection means M, second water level detection means
S and the third water level detection means D, and at the time of high combustion , the pump 25 is controlled based on the water level detection of the first water level detection means M to bring the water level in the can body 20 to a predetermined high combustion water level, Based on the water level detected by the second water level detecting means S, the pump 25
To control the water level in the can body 20 higher than the high combustion water level.
And controls each have a predetermined low combustion level, the first level detecting means failure detecting when third level detecting means of the second level detecting means S to control backed up by the failure detection when the second level detecting means S of M And a controller 30 for performing backup control by D.

[0005]

According to this invention, when the burner 24 burns high, the first
The water level in the can is controlled to be low based on the water level detected by the water level detection means M, and the water level in the can is controlled to be high based on the water level detected by the second water level detection means S during low combustion. When the first water level detecting means M is defective, the first water level detecting means in the same water level controller 29 is used.
The pump 25 is backed up by the second water level detection means S for detecting a water level higher than the stage M, and the pump 25 is ON-OFF controlled. When the second water level detection means S is defective, the same water level controller 29 is used.
And the pump 25 is turned on by the third water level detecting means D which detects a higher level than the first water level detecting means M.
Because the FF control, low level control of the water tube overheating Ru made.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the present invention will be described below in detail with reference to the drawings. The embodiment shown in the drawings illustrates a rectangular small once-through steam boiler as an example, and FIG. 1 is an explanatory view schematically showing an embodiment of the present invention.

In FIG. 1, reference numeral 20 denotes a rectangular can body with a can body cover (not shown) covering both side surfaces in a longitudinal direction (direction A in which a combustion flame and a combustion gas flows) removed.
Numerous substantially vertical water tubes between the upper header 21 and the lower header 22
23, 23 are connected in a plurality of rows in the longitudinal direction and in a plurality of rows in the short direction (perpendicular to the paper surface), a burner 24 such as a flat combustion burner is provided at one end in the longitudinal direction, and the combustion gas is discharged from the other end. It is configured as follows. Reference numeral 25 denotes a water supply pump for supplying water into the can body 20.

Reference numeral 26 denotes a steam take-out pipe 27 between headers 21 and 22;
A separator connected by a downcomer pipe 28, a cylindrical water level controller 29 connected between the upper header 21 and the lower header 22, and a predetermined water level in the water level controller 29 whose respective detection ends are sequentially higher. Fourth, first, second, and third water level detection electrodes L, M, S, and D are inserted for detection. The first water level detection electrode M turns on (starts) the pump 25 based on the detected water level.
The OFF (stop) control controls the water level in the high combustion can body to a predetermined low water level, and the second water level detection electrode S controls the pump 25 on and off based on the detected water level to control the water level in the low combustion can body. 20 The internal water level is controlled to a predetermined high water level. The fourth water level detection electrode L stops the combustion of the burner 24 in the interlock state by detecting the absence of water.

Reference numeral 30 denotes a main controller constituted by a microcomputer or the like, which operates according to a previously stored processing procedure.
31, first, second, third, fourth water level detection electrodes M, S, D,
Signals from the L, etc. are input to control the combustion state of the burner 24, and also control the pump 25 to control the water level in the can.

The control of the water level in the can is performed by the above-mentioned first and second water level detection electrodes M and S to control the ON / OFF control of the pump 25 corresponding to the combustion load, the cold start control described below, and the 1. Includes backup control of the second water level detection electrodes M and S. The pump control for the combustion load corresponds to the electrode S at the time of low combustion, that is, the timing control based on the water detection of the electrode S. Based timing control. Furthermore,
More specifically, for example, the ON condition of the low-combustion water supply pump 26 is a condition that T1 has elapsed since the electrode S was turned off (detection of no water), and the OFF condition at the time of low combustion is T2 from the ON of the electrode S (detection of water) to T2. It is a condition of progress. The ON condition of the high-combustion water supply pump 26 is a condition that T3 has elapsed since the electrode M was turned off, and the OFF condition during high combustion is a condition that T4 has elapsed since the electrode M was turned on.

In the cold start control, the third water level detection electrode D is activated during the cold start, and the third water level detection electrode D is not turned off by detecting the presence of water by the second water level detection electrode S without turning off the pump 25. Includes control to turn off the pump by detecting presence of water. Note that the cold start means a start (a combustible state) in a cold state in which the can water is lower than a predetermined temperature, and in the embodiment, a superheat thermostat 32 for detecting the temperature of an appropriate place above the water pipe 23.
The temperature at the start of the operation is detected when the temperature of the water is detected.

The backup control is performed by the first water level detection electrode M
The backup control by the second water level detection electrode S at the time of failure and the backup control by the third water level detection electrode D at the time of failure of the second water level detection electrode S are included.

In the former backup control, when the first water level detecting electrode M is judged to be defective by the means for judging a defect, the pump is controlled by the second water level detecting electrode S, for example, by detecting the presence of water in the water level detecting electrode S. OFF, 2nd
The control includes turning on the pump after a predetermined time has elapsed from the detection of the absence of water by the water level detection electrode S. The means for judging the failure of the first water level detection electrode M includes a first water level detection electrode when the fourth water level detection electrode L changes from the presence of water detection to the absence of water in the presence / absence detection state of the first water level detection electrode M. Means for determining that M is defective, but not limited thereto, means for determining that the first water level detection electrode M is defective if the first water level detection electrode M does not detect the absence of water after a predetermined time from the absence of water of the second water level detection electrode S, or After detecting the absence of water by the second water level detection electrode S, the first water level detection electrode M
If the fourth water level detection electrode L detects the absence of water without passing through the absence of water detection means, it may be determined to be defective.

The latter backup control is the timing control by the third water level detection electrode D when the means for determining the failure of the second water level detection electrode S determines that the second water level detection electrode S is defective.
Pump 25 is turned off by detecting water presence of water level detection electrode D
The control includes turning on the pump 25 after a lapse of a predetermined time from the detection of the absence of water by the third water level detection electrode D. The means for determining whether the second water level detection electrode S is defective includes the second water level detection electrode S
When the first water level detection electrode M changes from the presence detection to the absence detection in the water presence detection state, a means for determining that the second water level detection electrode S is defective is used. Means for determining that the second water level detection electrode S is defective when the second water level detection electrode S does not detect the presence of water after a predetermined time from the presence of water, or the presence of water in the second water level detection electrode S after the presence of water is detected by the first water level detection electrode M If the third water level detection electrode D detects the presence of water without detection, a means for determining a failure may be used.

The operation of the above embodiment in the above configuration will be described. At the time of cold start, that is, at the start of combustion in a state where the water temperature of the can is low, the water level in the can body 20 is raised by the third water level detecting means D, and overheating at the time of cold start is prevented.

In the subsequent operation, during low combustion, the pump 25 is turned on under the condition that T1 has elapsed since the electrode S was turned off,
The electrode S is turned off under the condition that T2 has elapsed since the electrode S was turned on.
The internal water level is controlled to a high water level suitable for low combustion. When it is determined that the electrode S is abnormal for some reason, the pump D is ON / OFF controlled by the electrode D. Thus, the electrode S for low combustion is backed up by the electrode D.

At the time of high combustion, the water supply pump 26 is turned on under the condition that T3 has elapsed from the time when the electrode M is turned off.
It is turned off under the condition of 4 lapses, and the water level in the can 20 is controlled to a low water level suitable for high combustion. When an abnormality of the electrode M is determined for some reason, the pump 26 is turned on and off by the electrode S.
FF control is performed. Thus, the electrode M for high combustion is replaced with the electrode S
Backed up by

The present invention is not limited to the above embodiment, but is applicable to a steam boiler having a cylindrical can body as shown in FIG. In FIG. 2, components corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted. In FIG. 2, a well-known cylindrical can body similar to that of FIG.
Also, a well-known gun type burner or a gas burner that replaces it is used.

The water level detecting means may be an integrated electrode (not shown) instead of the separate water level detecting electrodes L, S, M and D as in the above embodiment.

[0020]

[Effect of the invention] As described above, according to the invention, the normal
Time is a small number of the first water level control means and the second water level control means
Water level corresponding to high combustion and low combustion by water level control means
Control can be performed. Further , even if the first and second water level detecting means fail, they are backed up by the second water level detecting means and the third water level detecting means for detecting higher water levels, respectively , so that the overheating of the water pipe can be reliably prevented. In particular, high combustion
Water level at low combustion, which is important for water level control compatible with low combustion
The backup of the detecting means is the same water as the second water level detecting means.
In the water level controller and the water level higher than the second water level detection means
Since the detection is performed by the third water level detecting means,
Water level in the can body
Low impact, and suitable for low combustion
As a result of maintaining a high water level, differences in water level detection
Prevention of overheating of water pipes can be ensured constantly
And so on .

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an embodiment of the present invention.

FIG. 2 is an explanatory view schematically showing another embodiment of the present invention.

Claims (1)

(57) [Scope of request for utility model registration] 1. A water level controller 29 and the upper header 21 and the can body 20 which is connected to a substantially vertical water tube 23 between lower header 22 is communicated with prior SL between upper header 21 and lower header 22 And a burner for heating the water pipe 23 to at least high combustion and low combustion.
24, in a steam boiler provided with a pump 25 for supplying water to the can body 20, sequentially in the water level controller 29
First water level detection provided to detect a high predetermined water level
Means M, second water level detection means S, and third water level detection means D
The pump 25 is controlled based on the water level detection of the first water level detection means M at the time of high combustion to set the water level in the can body 20 to a predetermined high combustion water level, and the second water level detection means S at the time of low combustion. and controls the pump 25 based on the water level detected it the can body 20 water level to a predetermined low combustion level higher than the high combustion level
Thereby respectively control, control for controlling backed up by a third level detecting means D upon failure detection of the second level detecting means S as well as the backup control by the first level detection means failure detecting at the second level detecting means S of M With container 30
Water level control device of the boiler, characterized in that Bei was.