JP2526471B2 - 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 controller for a small once-through type boiler, and more particularly to a water level controller for low combustion and high combustion (heat load compatible).

[0002]

2. Description of the Related Art The following is known as a conventional water level control system for a small once- through type boiler . In FIG. 3, 1
Is a cylindrical can body, and the upper canister 2 and the lower canister 3 of the can body 1
The fourth water level detection electrode L for shutting off the low water level and the water supply pump 5 are turned on so as to detect the predetermined low, medium and high water levels in the water level controller 4 respectively connected to the water level controller 4 A first water level detection electrode M for control and a second water level detection electrode S for OFF control of the water supply pump 5 are provided, and a third water level for raising the water level in the can at startup to a predetermined water level in the can body 1. The detection electrode D is provided, and the third water level detection electrode D operates at the time of low combustion (it can also operate at times other than low combustion) to prevent overheating of the water pipe at low combustion and perform heat load compatible water level control. There is (conventional example 1). Further, as a water level control system corresponding to a heat load, as shown in Japanese Patent Publication No. 57-35361, in a boiler as shown in FIG. 3, a water level detector detects a low water level and a high water level. It is also known to perform water level control in response to heat load by switching the water level detection position (conventional example 2 ).

[0003]

According to the above-mentioned conventional example 1, since the water level control change width is narrow, the dependency of the third water level detection electrode D at the time of low combustion becomes high, and when this electrode fails. Have problems such as overheating of water pipes, difficulty in setting proper water level zone, and frequent pump start / stop. Further, according to the conventional example 2, when the water level detector fails, the combustion is stopped.
There is a problem of having to do it. The present invention addresses these
In addition to solving the problem, at the time of water level detector failure and startup
Boiler water level control device that can reliably prevent overheating of water pipes
It was made for the purpose of providing .

[0004]

According to the present invention, there is provided a can body in which a substantially vertical water pipe is connected between an upper pipe header and a lower pipe header, and a separator connected in communication between the upper pipe header and the lower pipe header. A first water level controller connected in communication between the upper header and the lower header, a second water level controller connected in communication between the separator and the lower header, and the water pipe for at least high combustion and low combustion. In a steam boiler including a burner for heating to, and a pump for supplying water to the can body,
A first water level detecting means and a second water level detecting means which are respectively provided to detect low and high water levels in the first water level controller, and a third water level detecting means for detecting a predetermined water level in the second water level controller .
Water level detection means, and controls the pump based on the water level detection of the first water level detection means during high combustion to bring the water level inside the can to a predetermined high combustion water level and the second water level detection means during low combustion. of the can body water level by controlling the pump based on the water level detection of a predetermined controls, respectively to a low combustion level of superheat limit water level detection level of the low combustion state and at high burn of the third level detecting means Set it to the higher side, and when high combustion
No water in the first water level detecting means and water in the third water level detecting means
The second water level is detected under the OR condition of "without" and when the combustion is low.
OR condition of no water of means and no water of third water level detection means
Then, each of the pumps is turned on.

[0005]

According to the present invention, the water level inside the can is controlled to be low based on the water level detected by the first water level detecting means when the burner is highly burning, and the can based on the water level detected by the second water level detecting means when the burner is low. The body water level is controlled to be high. Separator and lower tube
Detects the water level in the second water level controller, which is connected in communication with each other
Third level detecting means for sets the detection level to the higher superheat limit water level at low combustion period and a high combustion, during high combustion
Of the first water level detecting means and the third water level detecting means
Under the OR condition with no water and at the time of low combustion, the second water level test
OR Article for Water Out of Outlet Means and Water Out of Third Water Level Detection Means
In this case, since the pumps are configured to be turned on respectively, the pumps are the first water level detection means during high combustion or the third water level detection means.
The water level detector, also at low combustion would be ON by the second level detection means or the third level detecting means, first, not only when a fault occurs in the second level detecting means, ball
Overheating of the water pipe at the time of starting the irradiator may cause the third water level detection
Prevented by no water detection .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in detail below with reference to the drawings. The embodiment shown in the drawings shows, as an example, a square-flow once-through steam boiler,
FIG. 1 is an explanatory view showing the outline of 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 plural rows in the longitudinal direction and in plural rows in the lateral direction (perpendicular to the paper surface), a burner 24 such as a planar combustion burner is provided at one end in the longitudinal direction, and combustion gas is discharged from the other end. Is configured as follows. Reference numeral 25 denotes a water supply pump for supplying water into the can body 20.

[0008] 26 is a separator connected between the upper header 21 and the lower header 22 by a vapor take-out pipe 27 and a downcomer pipe 28, and 29 is a cylindrical tubular member provided between the upper header 21 and the lower header 22. 1 water level controller, each detection end is a water level controller 29
Fourth, first, and second water level detection electrodes L, M, S are inserted so as to detect predetermined low, medium, and high water levels therein. First
The water level detection electrode M turns on the pump 25 based on the detected water level.
By controlling N (start) -OFF (stop), the water level inside the can during high combustion is controlled to a predetermined low water level, and the second water level detection electrode S turns on (starts) the pump 25 based on the detected water level.
By controlling OFF (stop), the water level in the can body 20 is controlled to a predetermined high water level at the time of low combustion, and the fourth water level detection electrode L stops the combustion of the burner 24 in an interlock state when detecting the absence of water. It is for cutting off low water level combustion.

Numeral 30 is a cylindrical second water level detector, one end of which is connected to the upper portion of the separator 26 and the other end of which is connected to the lower portion of the lower pipe holder 22 so as to communicate with each other.
As a mode of communication connection at the other end, as shown in the figure, a separator 26
It may be connected to the lower part, or may be directly connected to the downcomer pipe 28 or the lower head 22. The third water level controller 30 has a third
The water level detection electrode D is inserted so that its detection end detects a predetermined water level. The position of this detection end, that is, the detected water level is set to the higher of the overheat limit water levels during low combustion and high combustion, and the pump 25 is turned on when the water level detection end detects the absence of water.
Configured to do so. The superheat limit water level is the limit water level at which water pipe overheating occurs when the water level falls below the water level inside the can, and the water level inside the can is replaced by the water level inside the second water level controller 30. Set the edge.

Reference numeral 31 denotes a main controller composed of a microcomputer or the like, which is an operating unit according to a processing procedure stored in advance.
32, first, second, third, fourth water level detection electrodes M, S, D,
L, a pressure detector 33 for detecting the steam pressure in the can 20, a feed water temperature detector 34 for detecting the feed water temperature, a water pipe overheat thermostat 35 for detecting overheating of the water pipe 23, and the like, and the burner 24
And controls the pump 25 based on the combustion state, the steam pressure, the feed water temperature, and the water pipe superheat temperature. The pump 25 is controlled at a timing centered on the electrode S when the combustion is low, that is, at a timing based on the water detection of the electrode S, and at a timing when the combustion is high, centered on the electrode M, that is, at a timing based on the water detection of the electrode M. Controlled. Further, more specifically, the ON condition of the pump 25 at the time of low combustion is an OR condition of the condition that T1 has elapsed since the electrode S was OFF (no water detected) or the electrode M is OFF and the electrode D is OFF. O of time
The FF condition is an AND condition of a condition that T2 has passed since the electrode S was turned on (detection of water) and a condition that T5 ( or T6) has passed since the electrode D was turned on. Also, the pump 25 during high combustion
The ON condition of is the OR of the condition that T3 has elapsed from the OFF of the electrode M or the condition that the electrode L is OFF and the condition that the electrode D is OFF.
The OFF condition at the time of high combustion is the condition that T4 has elapsed from ON of the electrode M and the condition of ON from T5 ( or T
6) AND condition with the condition of progress. The above timings (time) T1, T2, T3, T4 are set to appropriate values corresponding to the steam pressure and the feed water temperature, and stored in a memory (not shown) as a timing table. or,
T6 and T5 are the elapsed time from ON of the third water level detection electrode D when the temperature of the overheated thermostat 35 is below a predetermined value at the time of cold start, and the ON of the third water level detection electrode D under other conditions.
Indicates the elapsed time from and is set to T5 <T6. still,
The cold start-up means the start-up in a cold state of the can water at a predetermined temperature or lower (making it in a combustible state), and in the embodiment, the can water temperature is indirectly detected by detecting the water pipe temperature by the overheat thermostat 35. Is detected, and the temperature is below a predetermined value.

The operation of the above embodiment having the above-mentioned structure will be described. (At low combustion) Normally, T1 elapses from the OFF state of the electrode S or the electrode M is OF.
Pumped under the OR condition of F condition and OFF condition of electrode D
25 is turned on, T2 has passed since the electrode S was turned on, and electrode D
Is turned off by AND of the condition of the passage of ON from T5 (or T6), and the water level in the can body 20 is controlled to a high water level suitable for low combustion. For some reason, Ri Do the electrode S is abnormal, the electrode D water level is lowered is the condition of OFF is satisfied, the pump 25 is activated by the electrodes D. Thus, the electrode S for low combustion is backed up by the electrode D. or,
Even if there is no abnormality in the electrode S when starting the boiler, the electrode D
When FF (no water is detected), the pump 25 is activated by the electrode D.
The water pipe is prevented from overheating at the time of starting.

(At high combustion) Normally, T3 elapses from the OFF state of the electrode M or the electrode L is OF.
Pump 25 under OR condition of F condition and OFF condition of electrode D
Is turned on, and the condition of the passage of T4 from the turning on of the electrode M and the electrode D
Is turned off under the AND condition of the condition that T5 (or T6) has passed from ON of, and the water level in the can body 20 is controlled to a low water level suitable for high combustion. For some reason, electrode M becomes abnormal,
The electrode D is Ru is satisfied conditions OFF level is lowered,
The electrode 25 activates the pump 25. Thus, the electrode M for high combustion is backed up by the electrode D.
Even when there is no abnormality in the electrode M when starting the boiler, the electrode D
When is OFF (no water is detected), electrode D pumps
25 is started, and overheating of the water pipe is prevented at startup etc.
It

In any of the above, the pump 25 is started when the water level drops below the electrode L in any state.

The present invention is not limited to the above embodiment, but can be applied to a steam boiler having a cylindrical can as shown in FIG. 2, the components corresponding to those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted. In FIG. 2, the can body 20 is a well-known cylindrical can body similar to that shown in FIG.
Also Ru used <br/> the gas burner to replace it and the well-known gun-type burner.

Further, the water level detecting means may not be separate water level detecting electrodes L, S, M and D as in the above embodiment, but may be integrated electrodes (not shown),
The float type water level detecting means as in the conventional example 2 may be used. Further, the pump is controlled based on the water level detected by the first water level detecting means during high combustion to bring the water level inside the can to a predetermined high combustion water level, and based on the water level detection by the second water level detecting means during low combustion. The method of controlling the pump to control the water level in the can to a predetermined low combustion water level is not limited to the above embodiment, and the first water level detection means M during high combustion
The pump is controlled by the timing control centering on the detection end of the pump to bring the water level in the can to a predetermined high combustion water level, and when the combustion is low, the pump is turned on by the waterless detection of the first water level detection means M.
However, the pump may be controlled based on the detection of the presence of water by the second water level detecting means S to control the water level in the can to a predetermined low combustion water level. Furthermore, the third embodiment of the present invention
In addition to the above-described embodiment in which the pump 25 is turned on immediately when the water level detection electrode D detects the absence of water, an embodiment in which the pump 25 is turned on after a lapse of a predetermined time from the detection of no water is included.

[0016]

As described above, according to the present invention, the first
Since the water level control means and the second water level control means perform the water level control corresponding to the combustion load, the change range of the water level control can be widened, the setting of the proper water level zone can be facilitated, and the number of times of starting and stopping the pump can be increased. Can be reduced . Also, the third water level detection
Measures the detected water level to the overheat limit at low and high combustion.
Set to the higher water level and detect the first water level at high combustion
OR condition of no water of means and no water of third water level detection means
At low combustion, the second water level detection means
3 In the OR condition of the water level detecting means with and without water,
Since it is configured to turn on the pump, the first and second
Even if the water level detection means fails, the third water level detection means can back up, and the water pipe due to the failure of the first and second water level detection means
Overheat can be prevented, and because of the first and second water level detecting means.
Even if there is no obstacle, the third water level detection means
The water level inside the can can be raised and
Water pipe overheating can be prevented. Further, the third water level detecting means is
Instead of directly detecting the water level in the can,
And water level in the second water level controller connected between the lower head
Since it is configured to detect the
It is possible to prevent erroneous detection of the presence of water due to the liquid droplets of the
The third water level detected in the failure-time and start-up or the like of the position detecting means
There is a large effect that the water pipe can be surely prevented from being overheated by the means .

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of an embodiment of the present invention.

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

FIG. 3 is an explanatory diagram showing an outline of a conventional example.

[Explanation of symbols]

 20 canister 21 upper pipe head 22 upper pipe head 23 water pipe 24 burner 25 water supply pump 26 separator 29 first water level controller 30 second water level controller M first water level detection electrode (water level detection means) S second water level detection electrode ( Water level detection means) D Third water level detection electrode (water level detection means)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideo Ando Hidero Ando 7 Eiji Horie-cho, Matsuyama-shi, Ehime Examiner, Miura Kogyo Co., Ltd. Eisuke Kiyota (56) Reference JP-A-54-103905 (JP, A) Kaihei 4-24402 (JP, A) Actual Kaihei 1-170805 (JP, U)

Claims (1)

(57) [Claims] 1. A can body in which a substantially vertical water pipe is connected between the upper header and the lower header, a separator connected in communication between the upper header and the lower header, and the upper header and the lower header. A first water level controller connected in communication therewith, a second water level controller connected in communication between the separator and the lower pipe header, a burner for heating the water pipe to at least high combustion and low combustion, and the can In a steam boiler including a pump for supplying water to a body, first water level detection means and second water level detection means, which are provided to detect low and high water levels in the first water level controller, respectively, and the second water level detection means. A third water level detecting means for detecting a predetermined water level in the water level controller , and controlling the pump based on the water level detection by the first water level detecting means during high combustion to control the water level in the can. At a predetermined high combustion water level, when low combustion Said canister body water level by controlling the pump based on the water level detection of 2 water level detecting means and controls each of the predetermined low combustion level, at low combustion period and a high combustion detection level of said third level detecting means The water temperature of the first water level detecting means is set to a higher one of the overheat limit water levels and at the time of high combustion.
If there is no condition and there is no water in the third water level detecting means, the condition is low.
At the time of combustion, there is no water and the third water level detection by the second water level detection means.
A water level control device for a boiler, wherein each of the pumps is turned on under an OR condition with water out of the output means.