JP3933261B2 - Boiler blow control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a boiler blow control device in which the boiler water concentration is maintained at an appropriate value.
[0002]
[Prior art]
When steam is generated by operating the boiler, impurities contained in the boiler feed water remain in the boiler can water and gradually concentrate to cause a carryover phenomenon. For this reason, a blow solenoid valve is provided, and when the boiler water concentration rises, the blow solenoid valve is opened to discharge the boiler water, and when the boiler water concentration falls, the blow solenoid valve is closed. It is widely practiced that a boiler is equipped with a blow control device that maintains the concentration at a specified value to prevent the carryover phenomenon.
[0003]
Conventionally, the blow control device generally controls opening and closing of the blow electromagnetic valve so as to open the blow electromagnetic valve in synchronization with the water supply pump for reasons such as heat exchange between blow and water supply. The blow flow rate is adjusted to a predetermined flow rate by using an orifice, a throttle valve, or the like with the feed water flow rate of the feed water pump.
[0004]
[Problems to be solved by the invention]
Here, in the blow control device, the blow flow rate may decrease due to the clogging of the strainer for the blow solenoid valve or the increase in the exhaust pressure of the blow pipe. In such a case, there is a problem that the amount of can water discharged becomes insufficient and the concentration of the can water increases, causing a carry-over phenomenon and reducing the dryness of the steam.
[0005]
The present invention has been made in view of the above circumstances. Even if the blow flow rate of the blow control device is reduced, the discharge of boiler water is ensured so that the can water concentration can be maintained at a specified value. An object is to provide a control device.
[0006]
[Means for Solving the Problems]
The boiler blow control device of the present invention controls the opening and closing of the blow solenoid valve intermittently in synchronism with the water supply when the boiler water concentration reaches the upper limit value of the can water concentration. This operation is repeated until the water reaches the lower limit value. When the can water concentration reaches the lower limit value, the boiler water control device continues to close the blow solenoid valve and intermittently opens and closes only the water supply. Means for determining whether or not the can water concentration exceeds the upper limit value of the can water concentration and further increases after the water concentration upper limit value is reached and the blow solenoid valve is started to open and close intermittently in synchronization with the water supply ; When it is determined that there is an upward trend, the blow electromagnetic valve is kept open without being synchronized with the water supply, and only means for intermittently opening and closing the water supply is provided.
[0007]
The boiler blow control device of the present invention intermittently controls opening and closing of the blow solenoid valve in synchronization with water supply when the boiler water concentration reaches the upper limit value of the can water concentration. This operation is repeated until the value reaches the value, and when the can water concentration reaches the lower limit value, in the blow control device of the boiler that continues to close the blow solenoid valve and intermittently opens and closes only the water supply, the boiler water concentration in the boiler Means for determining whether or not the can water concentration exceeds the can water concentration upper limit value after the can water concentration upper limit value has been reached and the blow solenoid valve is intermittently started to open and close in synchronization with the water supply. If the blow solenoid valve is determined to be in an upward trend, the blow solenoid valve is opened in synchronization with the water supply, and the water supply is turned on by delaying the time when the blow solenoid valve is closed relative to the time when the water supply is closed. Blow solenoid valve on time than time Characterized by comprising means for setting long.
[0008]
As a result, when the can water concentration tends to increase due to a decrease in the blow flow rate, etc., the discharge amount of the can water is ensured by opening the blow solenoid valve regardless of whether the water is being supplied or not, and the can water concentration is reduced. Can be kept at the default value.
[0009]
Here, the increase determination setting value of high boiler water concentration than the boiler water concentration limit provided, when the boiler water concentration reaches this increase determination setting value, the boiler water concentration exceeds the boiler water concentration limit Therefore, it can be determined that there is a further upward trend.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is an overall configuration diagram showing an outline of a steam boiler provided with a blow control device. The boiler body 1 includes a combustion device 2 that heats the boiler body 1 to generate steam, and water in the boiler body 1. And a blow control device 4 for maintaining the boiler water concentration at a predetermined value.
[0011]
The blow control device 4 includes a blow pipe 5 connected to the boiler body 1, a blow electromagnetic valve 6 interposed in the blow pipe 5, and a control device 7 that controls opening and closing of the blow electromagnetic valve 6. Is provided. Similarly, a can water concentration sensor 8 for measuring the can water concentration in the boiler body 1 is provided. Output signals from the concentration sensor 8 and the water supply pump 3 are input to the control device 7, and a signal from the control device 7 is input to the blow electromagnetic valve 6, so that the blow electromagnetic valve 6 is opened and closed. Yes.
Here, the can water concentration upper limit C ₁ and the can water concentration lower limit C ₂ shown in FIG.
[0012]
Next, the control operation of the blow control device 4 will be described with reference to FIG.
Since the boiler is heated by the combustion device 2 to generate steam, the water level of the can water decreases with the generation of the steam. And when this can water falls to the feed water pump starting level, the feed water pump 3 will be turned on and water will be supplied and water will be replenished until it reaches the feed water pump stop level. When steam is generated in this manner, impurities brought in from the feed water gradually accumulate in the boiler can water, and the can water concentration detected by the can water concentration sensor 8 increases. When the boiler water concentration is low and does not reach the can water concentration upper limit C ₁ , the blow solenoid valve 6 remains closed even when the feed water pump 3 is turned on.
[0013]
Then, when the boiler continues to generate steam and the can water concentration rises and this reaches the can water concentration upper limit C ₁ (time t ₁ ), the blow solenoid valve 6 is opened in synchronization with the feed water pump 3. , Drain the can water. Thereafter, this operation is repeated until the can water concentration reaches the can water concentration lower limit C ₂ . Then, if the blow flow rate is appropriate, the can water concentration gradually decreases, and when the can water concentration lower limit C _{2 is} reached (time t ₂ ), the blow solenoid valve 6 is closed and the water supply pump is turned on. Even so, the blow solenoid valve 6 continues to close. Usually, it operates in this way to maintain the canned water concentration at an appropriate value.
[0014]
However, the blow flow rate may be insufficient due to clogging of the strainer of the blow solenoid valve 6 or increase in exhaust pressure on the secondary side of the blow pipe 5 (downstream side of the blow solenoid valve 6). For example, when a plurality of boilers are installed and the secondary side of the blow pipe 5 is used as a collecting pipe, the pressure in the collecting pipe rises due to the blow of other plural boilers, resulting in a discharge. Pressure may increase.
[0015]
Therefore, after the can water concentration reaches its upper limit C ₁ and the blow solenoid valve 6 is opened in synchronism with the feed water pump 3 (time t ₃ ), the can water concentration gradually increases on average and reaches a predetermined time. If the can water concentration does not fall below the upper limit C ₁ even after T has elapsed, a means for determining that the blow is insufficient is provided in the control device 7. And when it determines with a can water density | concentration as an upward tendency, the blow solenoid valve 6 which was opened synchronously with water supply until now loses the synchronization with water supply, and is opened continuously (it is opened even when water supply is stopped). (Time t ₄ ), the shortage of blow flow rate is compensated for in the time direction, and the discharge amount is secured to reduce the can water concentration. Then, this operation is continued until the can water concentration reaches the lower limit C ₂ (time t _{4 to} t ₅ ). Thereby, even if the blow flow rate is insufficient, the shortage of can water discharge can be compensated and the boiler water concentration in the boiler can be maintained at an appropriate value.
[0016]
In this embodiment, the blow solenoid valve 6 is continuously opened after it is determined that the blow is insufficient. However, the feed water pump 4 is stopped according to the value of the can water concentration from the can water concentration sensor 8. After that, the time for stopping the blow electromagnetic valve 6 can be delayed, and the time for opening the blow electromagnetic valve 6 can be made longer than the water supply time to compensate for the shortage of drainage. That is, when it is determined that the concentration of the can water exceeds the predetermined value and increases, the blow solenoid valve 6 is set longer than the on time of the water supply pump 3 by a timer or the like. The blow discharge amount can be increased while turning on / off in synchronization with the water supply pump 3.
[0017]
Further, whether or not the can water concentration tends to increase after the blow solenoid valve 2 is opened is seen in the can water concentration after the time T has elapsed, for example, as shown by the one-dot chain line in FIG. A set value C ₃ for determining an increase in can water concentration higher than the upper limit setting may be provided, and when the can water concentration reaches the set value C ₃ , it may be immediately determined that there is an upward trend.
[0018]
【The invention's effect】
As described above, according to the present invention, when the concentration of can water tends to increase due to a decrease in the blow flow rate or the like, the can water can be opened by opening the blow solenoid valve regardless of whether or not the water is being supplied. The amount of discharge can be secured and the can water concentration can be maintained at a predetermined value, thereby preventing the carry-over phenomenon and lowering of the dryness of the steam.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a control operation according to an embodiment of the present invention.
FIG. 2 is an overall configuration diagram showing an outline of a boiler including a blow control device to which the present invention is applied.
[Explanation of symbols]
1 Boiler body 2 Combustion device 3 Water supply pump 4 Blow control device 5 Blow piping 6 Blow solenoid valve 7 Control device 8 Can water concentration sensor

Claims (3)

When the boiler water concentration reaches the upper limit value of the can water concentration , the blow solenoid valve is intermittently opened and closed in synchronization with the water supply, and this operation is repeated until the can water concentration reaches the lower limit value. When the pressure reaches the lower limit, the blow control device for the boiler that continuously closes the blow solenoid valve and intermittently opens and closes only the water supply ,
The boiler water concentration reaches the upper limit value of the can water concentration, and the can water concentration further rises above the upper limit value of the can water concentration after the opening and closing control of the blow solenoid valve is started intermittently in synchronization with water supply. Means for determining whether or not there is a tendency;
A boiler blow control device comprising means for continuously opening and closing the blow electromagnetic valve without being synchronized with the water supply and intermittently opening / closing control of only the water supply when it is determined that there is an upward trend. When the boiler water concentration reaches the upper limit value of the can water concentration , the blow solenoid valve is intermittently opened and closed in synchronization with the water supply, and this operation is repeated until the can water concentration reaches the lower limit value. When the pressure reaches the lower limit, the blow control device for the boiler that continuously closes the blow solenoid valve and intermittently opens and closes only the water supply ,
The boiler water concentration reaches the upper limit value of the can water concentration, and the can water concentration further rises above the upper limit value of the can water concentration after the opening and closing control of the blow solenoid valve is started intermittently in synchronization with water supply. Means for determining whether or not there is a tendency;
When it is determined that the upward tendency is present, the blow solenoid valve is opened in synchronization with the water supply, and the time when the blow solenoid valve is closed relative to the time when the water supply is closed is delayed from the on time of the water supply. Also, a blow control device for a boiler, comprising means for setting a long ON time of the blow solenoid valve . A setting value for determining an increase in the can water concentration that is higher than the upper limit value of the can water concentration is provided , and when the can water concentration reaches the setting value for the increase determination, the can water concentration further increases beyond the upper limit value of the can water concentration. The boiler blow control device according to claim 1, wherein the blow control device is determined to have a tendency.

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