JP2003130303A - Method of quantity control for boilers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent boilers under quantity control from staying out of operation for a long time. SOLUTION: In a method of quantity control for boilers wherein a plurality of boilers A, B, etc., are prioritized and a necessary number of them are operated according to the given priority and to the required load, each boiler is monitored for stopped state and, according to the result of monitoring, adjustment is made of their precedence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler number control method.

[0002]

2. Description of the Related Art In a multi-can installation system in which a plurality of steam boilers (hereinafter, simply referred to as "boilers") are installed, a number-of-units control method is employed in which the number of operating units is controlled according to a load condition. In this number-of-units control method, the priority of operation of each of the boilers is preset. Therefore, depending on the load condition, the low-priority boiler may remain stopped for a long time.

As described above, when the boiler is stopped for a long time, the temperature of the boiler can lowers due to heat radiation.
Then, the vapor in the can is condensed, and the pressure in the can (hereinafter referred to as “can internal pressure”) is rapidly reduced by this condensation. Then, when the internal pressure of the can becomes lower than the atmospheric pressure, the water supply is sucked into the can body, and the water supply fills the can body.

When the operation of the boiler is restarted in such a full water condition, the pressure inside the can rapidly rises, the safety valve of the boiler operates, and the safety valve supplies water (hereinafter referred to as "can water") into the boiler. ")) Spouts with the steam. Then, there arises a problem that the control device and auxiliary devices are contaminated or damaged by the can water ejected from the safety valve. Further, even if the safety valve does not operate, steam having a low dryness in which a large amount of can water is mixed flows out from the boiler, which causes a problem that related devices such as a valve are damaged.

Further, as described above, when the boiler is stopped for a long time, the temperature of the exhaust pipe of the boiler also decreases due to heat radiation. Then, the water contained in the exhaust gas in the exhaust pipe may condense in the exhaust pipe, and the condensed water may corrode the exhaust pipe.

[0006]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is, in a boiler controlling the number of units,
It is to prevent the boilers from being stopped for a long time.

[0007]

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 sets a priority order to a plurality of boilers installed, and this priority order is set. Also, in the boiler number control method for controlling the number of operating boilers according to the required load, the stop status of each boiler is monitored, and the priority order is adjusted according to the monitoring result.

Further, in the invention as set forth in claim 2, the stop condition is monitored based on at least one of a detected value of the internal pressure of the boiler, the temperature of the can body, and the concentration of the can water. Is characterized by.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The present invention can be suitably implemented in a multi-can installation system in which a plurality of boilers are installed. That is, the present invention can be implemented as a number control method in the multi-can installation system. Here, the number-of-units control method sets an operation priority order to each of the boilers, and sets the set priority order (hereinafter,
This is a control method for operating the required number of boilers according to the "setting priority") and the required load.

Now, the number control method of the present invention will be described. The number-of-units control method of the present invention is a number-of-units control method of monitoring the stop status of each of the boilers and adjusting the priority based on the monitoring result. That is, in this number-of-units control method, the priority order is adjusted to be higher than the set priority order, based on the monitoring result, for the boiler having a long stop time and having a high possibility of problems such as full water and condensation. For example, the adjustment of the priority order is changed to the first. Then, this boiler is preferentially operated, and the internal pressure of the can and the temperature of the can body can be raised, so that the problems of full water and dew condensation can be solved.

When the internal pressure of the can and the temperature of the can body rise sufficiently, the priority is returned to the original set priority. Further, depending on the implementation, the adjusted priority order can be used as a new set priority order to continue the unit number control.

As described above, according to the number-of-units control method of the present invention, it is possible to prevent the boilers from being stopped for a long time by adjusting the priority order of the boilers according to the stop situation. Therefore, the problems of full water and dew condensation in each of the boilers can be reliably solved.

In this method of controlling the number of units, the stop state of each of the boilers is detected by detecting the can internal pressure of each of the boilers,
It is performed based on the detected value of at least one of the temperature of the can and the concentration of the can water. Here, the reason why the stop state of each boiler can be monitored based on the detected value of the enrichment will be described. Generally, the boiler is operated so that the concentration is maintained within a predetermined range in order to prevent corrosion of the can and prevent deterioration of the dryness of steam. However, when the boiler is stopped for a long time and the can internal pressure becomes lower than the atmospheric pressure, the feed water flows into the can body, the can water is diluted, and the enrichment falls below the predetermined range. Therefore, the stop status of the boiler can be monitored based on the detected value of the enrichment.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view schematically showing an example of a boiler multi-can installation system for carrying out the present invention.

First, a multi-can installation system for a boiler will be described with reference to FIG. In FIG. 1, the multi-can installation system includes four steam boilers, that is, a first boiler A, a second boiler B, a third boiler C, and a fourth boiler D. A steam line 1, 1, ... Having a check valve (reference numeral omitted) is connected to each of the boilers A to D. These steam lines 1 have a common steam header 2
Respectively connected to. And this steam header 2
From the above, steam is supplied to an appropriate steam-using device (not shown) through the steam supply line 3.

The steam header 2 is provided with pressure detecting means 4 for monitoring the load condition from the steam using equipment. This pressure detecting means 4 is connected via the line 5.
It is connected to the unit number control device 6. This number control device 6
Are connected in series with the controllers 7, 7, ... Of the boilers A to D via the line 5. Then, the number-of-units control device 6 determines the operating number of each of the boilers A to D based on the detection result from the pressure detection unit 4, and prioritizes the preset operation of each of the boilers A to D. According to the order (hereinafter, referred to as “setting priority order”), the operation of the determined number of operating machines is performed.

Next, the construction of each of the boilers A to D in the multi-can installation system will be described. Here, each of the boilers A to D has the same configuration, so the first boiler A will be described. Now, in the first boiler A, a combustion device 8 is provided on the upper part thereof. Further, a water supply line 9 including a water supply pump 9 and a check valve (reference numeral omitted) is connected to a lower portion of the first boiler A.

Next, the control configuration of the first boiler A will be described. At the upper part of the first boiler A, a means for detecting the pressure inside the can in the first boiler A (hereinafter referred to as "can internal pressure detection means") 11 and a temperature for the can body of the first boiler A are detected. Means (hereinafter referred to as “can temperature detecting means”) 12 is provided. In addition, the first boiler A
In the lower part of the tank, there is provided a means 13 for detecting the concentration of canned water (hereinafter referred to as “concentration detecting means”). Here, the enrichment detecting means 13 is configured to detect the enrichment based on the electric conductivity of the can water.

Each of the detection means 11 to 13 is connected to the controller 7 of the first boiler A via a line (not shown). Further, the first boiler A is provided with various detecting means (not shown) such as a water level detecting means (not shown) in the first boiler A, and these detecting means are also provided with lines (not shown). ) Are connected to the controller 7, respectively. Further, the combustion device 8 and the water supply pump 9 are connected to the controller 7 via lines (not shown), respectively.

Then, the controller 7 receives a signal from the unit number control device 6 and controls the operation of the combustion device 8. Further, the controller 7 controls the operation of the water supply pump 9 so as to maintain the water level in the first boiler A within a predetermined water level range based on the detection result from the water level detection means.

Below, the control contents of the unit number control device 6 and the unit number control method of the present invention will be explained. Here, in the unit number control device 6, the setting priority is the order of the first boiler A, the second boiler B, the third boiler C, and the fourth boiler D. Also,
Each of the boilers A to D is operated so that the concentration of can water is maintained within a predetermined range in order to prevent corrosion of the can body and prevent deterioration of the dryness of steam.

After the multi-can installation system is activated, the number-of-units control device 6 activates each of the boilers A to D in order, and operates all the units to raise the pressure inside the steam header 2 to a predetermined pressure. Let Then, thereafter, based on the detection result from the pressure detecting means 4, each of the boilers A is
The number of operating units of D to D is determined, and the boilers A to D for the determined number of operating units are operated in accordance with the set priority order. In addition, the unit number control device 6 controls the boilers A to D.
The stop status of each of the boilers A to D is monitored based on the detection result from each of the detection means 11 to 13 in FIG. Then, the priority order is adjusted based on the monitoring result.

Among the boilers A to D, the lower the priority, the more preferentially the boiler is stopped. And
The lower the priority of the boiler, the longer it remains stopped. For example, since the fourth boiler D has the lowest priority, the state in which it is stopped becomes long. Then,
Due to the heat dissipation, the internal pressure of the can decreases and the temperature of the can body also decreases. Then, when the internal pressure of the can becomes lower than the atmospheric pressure, the water supply in the water supply line 10 starts to be sucked into the can body. Then, the inflow of this supply water starts to reduce the concentration of the canned water.

The internal pressure of the can, the temperature of the can body, and the concentration of the can water are detected by the detecting means 11 to 13, and the unit number control device 6 controls the detecting means 11 to 11.
Based on at least one of the detection results from 13, the priority of the fourth boiler D is adjusted.

First, the case where the priority of the fourth boiler D is adjusted based on the detection result from the can internal pressure detecting means 11 will be described. In this case, when the detection result of the can internal pressure is reduced to a predetermined set pressure value, for example, 0.01 Mpa, the number-of-units control device 6 sets the priority order of the fourth boiler D from the fourth set priority order. Change to the first.

Then, the priority order after this change is in the order of the fourth boiler D, the first boiler A, the second boiler B, and the third boiler C. Thus, if the priority of the fourth boiler D is changed to the first priority, the fourth boiler D
Will be driven preferentially. Therefore, the can internal pressure and the can body temperature of the fourth boiler D can be raised, so that the problem of full water and the problem of dew condensation can be solved.

Then, when the can internal pressure and the can body temperature of the fourth boiler D sufficiently rise, the priorities are returned to the original set priorities again. Thereafter, for each of the boilers A to D, the stop status is monitored, and based on the monitoring result,
After adjusting the priority of the boiler determined to have a long stop time and operating the boiler after the adjustment, the priority is returned to the original setting priority.

Next, a case will be described in which the priority of the fourth boiler D is adjusted based on the detection value of the can body temperature detecting means 12. In this case, the unit number control device 6
Adjusts the priority of the fourth boiler D in the same manner as above when the detection result of the can body temperature drops to a predetermined set temperature, for example, 120 ° C. Here, the set temperature is a value set based on the saturated steam temperature corresponding to the set pressure value and the temperature at which dew condensation occurs.

Next, a case where the stop condition of the fourth boiler D is monitored based on the detection value of the enrichment detecting means 13 will be described. In this case, the unit number control device 6
When the concentration detection result falls below a specified range,
The priority of the fourth boiler D is adjusted in the same manner as above.
Here, in this case, similarly to the above, the fourth boiler D
The can internal pressure and the can temperature are increased, and the concentration of the can water is increased, and the can water returns to the predetermined range.

As described above, according to this number-of-units control method, the boiler having a long stop time is preferentially operated to increase the pressure and temperature of the boiler body of each of the boilers. Can be resolved.

Here, when adjusting the priorities of the boilers A to D, it is preferable to operate the boilers A to D to increase the internal pressure of the can and then adjust the priorities.
The reason for this is that in a boiler in which the internal pressure of the can has dropped for a long stop time, it takes time for the internal pressure of the can to rise to a predetermined pressure, so the pressure in the steam header 2 decreases during that time, and This is because it is possible to prevent unnecessary fluctuations.

[0032]

As described above, according to the present invention, it is possible to prevent each of the boilers from being stopped for a long time in a boiler in which the number of units is controlled. Therefore, problems such as full water and dew condensation can be prevented from occurring in each boiler.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing an example of a boiler multi-can installation system for carrying out the present invention.

[Explanation of symbols]

A first boiler (boiler) B Second boiler (boiler) C third boiler (boiler) D Fourth Boiler 11 Can internal pressure detection means 12 Can temperature detecting means 13 Concentration detecting means

Claims (2)

[Claims] 1. A boiler number control method for setting a priority for a plurality of installed boilers A, B, ... And controlling the number of operating boilers according to the priority and the required load. A monitoring method for controlling the number of boilers, characterized in that the stop status of each of the boilers is monitored and the priorities are adjusted according to the monitoring results. 2. The boiler A, which monitors the stop status,
The method for controlling the number of boilers according to claim 1, wherein the method is performed based on at least one detected value among the internal pressures of the cans, the temperature of the can body, and the concentration of the can water.