JPH109507A - Intermittent blow control method of boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the intermittent blow at an appropriate blow ratio according to the change in quality of the feed water while preventing the elements other than the electric conductivity from being concentrated too densely in a boiler under the intermittent blow. SOLUTION: In a boiler 1 where the blow ratio is set by analyzing the quality of the feed water in advance, and the set value is inputted in a control device 12 of the boiler as the initially set blow ratio, a feed water electric conductivity sensor 5 to measure the electric conductivity of the feed water is provided in a water feed passage 2 to feed water in the boiler, and a means to calculate the blow ratio from the electric conductivity in the feed water and to compare the calculated blow ratio with the initially set blow ratio is provided on the control device 12. While the calculated blow ratio is smaller than the initially set blow ratio, the intermittent blow is performed at the initially set blow ratio. When the calculated blow ratio is larger than the initially set blow ratio, the intermittent blow is performed at the calculated blow ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermittent blow control method for a boiler.

[0002]

2. Description of the Related Art As boiler can water evaporates, impurities in the water are concentrated. Carryover may occur as the concentration progresses,
Since scale is generated, it is necessary to intermittently blow out part of the can water intermittently to lower the concentration. Intermittent blow is performed by analyzing the quality of feed water at the time of boiler installation, measuring the concentration of silica and chloride ions, and the electrical conductivity in water, obtaining the blow rate from the relationship with the allowable concentration of can water, and determining the blow rate. It is done based on. However, even if the water source is the same, the water quality fluctuates.If water is supplied with a water quality different from the water quality at the time of water analysis, intermittent blow should be performed with an enrichment value outside the appropriate value Become. Therefore, it is conceivable that a water supply electric conductivity sensor is provided in the middle of the water supply path to the boiler, the electric conductivity of the supplied water is measured, and the blow is performed at the latest blow rate calculated from the measured electric conductivity. Was. The above method directly analyzes the water quality of the feed water and attempts to blow in response to changes in the water quality.However, since measurements other than the electric conductivity cannot be easily performed, the blow only using the electric conductivity is performed. When the blow rate determined from the concentration of silica or chloride ions is higher than the electric conductivity, the concentration proceeds to an allowable concentration or more.

[0003]

The problem to be solved by the present invention is that a boiler that performs intermittent blow is
An object of the present invention is to perform intermittent blow at an appropriate blow rate in response to a change in water quality of feedwater while preventing elements other than electric conductivity from being excessively concentrated.

[0004]

Means for Solving the Problems A boiler which heats water supplied into a boiler to extract steam, sets a blow rate by analyzing water quality of feed water in advance, and sets the blow rate to the set blow rate. Input to the boiler controller as the initial setting blow rate, and the controller supplies water to the boiler in a boiler that performs intermittent blow that discharges part of the can water by opening and closing the blow valve based on the blow rate A water supply electric conductivity sensor that measures the electric conductivity of the water supply is provided in the middle of the water supply path to be supplied. Blow rate calculating means for calculating the blow rate, and comparing means for comparing the calculated blow rate calculated from the electric conductivity with a preset initial blow rate, and the calculated blow rate is set to the initially set blow rate. Remote small during the conduct intermittent blow by the value of the initialization blow ratio, performs intermittent blow in the calculated value of the blow rate is when it becomes a larger value than the calculated blow rate initialization blow rate.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an arrangement of each equipment of a boiler embodying the present invention, FIG. 2 shows a relationship between a change in electric conductivity during feed water and an actual blow rate in one embodiment, and FIG. 3 shows an embodiment. It is a flowchart of FIG. Boiler 1 with built-in combustion device
A water supply path 2 is connected to a lower portion of the water supply path, and the water supply path 2 is provided with a water supply tank 3, a water supply pump 4, and a water supply electric conductivity sensor 5 on the way. At the top of the boiler 1, there is a steam connecting pipe 10,
The steam-water separator 7 is provided in connection with the steam communication pipe 10,
The lower part of the steam separator 7 and the boiler main body are connected by a downcomer 8. Water is supplied to the boiler 1 through the water supply path 2, and steam generated by heating the water in the boiler 1 is taken out through the steam communication pipe 10 and the steam separator 7, and together with the steam to the steam separator 7. The sent can water is returned to the boiler through the downcomer 8. A blow pipe 9 is connected in the middle of the downcomer 8, and a blow valve 11 is provided in the middle of the blow pipe 9.
Is provided, and the concentrated still water is discharged by opening the blow valve 11.

A water supply pump 4, a water supply electric conductivity sensor 5,
The boiler 1 and the blow valve 11 are connected to a control device 12 via a signal line 6, and the control device 12 controls the operation of the boiler. The water quality of the feedwater is analyzed in advance, and a blow rate is set based on the relationship with the allowable concentration of the can water and input to the control device 12. The blow rate of the initial setting is set by factors other than the electric conductivity. Keep it. In addition to the initially set blow rate, a calculation formula for calculating the blow rate from the electrical conductivity is input to the control device 12, and a calculating unit that calculates the blow rate from the electrical conductivity, A comparison means for comparing the magnitude of the initial setting blow rate is provided.

When the boiler is operated, the water level information in the boiler is sent to the control device 12, and the water supply pump 4 is operated so as to keep the water level constant, thereby supplying water to the boiler. The feed water conductivity sensor 5 measures the conductivity of the water supplied to the boiler, and sends the measured conductivity to the control device 12 through the signal line 6. The control device 12 determines the calculated blow rate by substituting the electrical conductivity sent from the feed water conductivity sensor 5 into the above-mentioned calculation formula, and compares the calculated blow rate with the previously set initial blow rate. When the initially set blow rate is larger than the calculated blow rate, the initially set blow rate is set as the actual blow rate, and when the calculated blow rate is larger than the initially set blow rate, the calculated blow rate is set as the actual blow rate. The controller 12 also calculates the amount of water supply from the combustion state and the combustion time of the boiler 1, and determines the opening / closing timing of the blow valve 11 based on the amount of water supply and the actual blow rate. By opening / closing the blow valve 11 in accordance with the opening / closing timing, the concentrated water still returning from the steam separator 7 to the inside of the boiler is discharged, and the intermittent blowing reduces the concentration of the water.

FIG. 2 shows that the blow rate determined from factors other than the electric conductivity is 6
%. In this case, even if the calculated blow rate obtained from the electrical conductivity in the supply water is 5%, the elements other than the electrical conductivity will not be sufficiently concentrated unless the blow rate of 6% is maintained. The rate is 6%
It is said. In addition, the calculated blow rate calculated from the electric conductivity in the water supply is 7%, which is larger than 6% of the initially set blow rate.
In the case of, the concentration on the electrical conductivity side will be too advanced unless the blow rate is 7%, so that the actual blow rate is 7%.

[0009]

According to the present invention, it is possible to determine the blow rate according to the change in water quality while preventing the concentration by elements other than the electric conductivity from progressing excessively, and to perform the intermittent blow at an appropriate blow rate. It can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an arrangement of each device of a boiler implementing an intermittent blow control method of the present invention.

FIG. 2 is an explanatory diagram showing a change in electric conductivity during feed water and an actual blow rate in one embodiment of the present invention.

FIG. 3 is a flowchart of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler 2 Water supply path 3 Water supply tank 4 Water supply pump 5 Water supply electric conductivity sensor 6 Signal line 7 Steam separator 8 Downcomer 9 Blow pipe 10 Steam communication pipe 11 Blow valve 12 Controller

Claims (1)

[Claims] 1. A boiler that heats water supplied into a boiler and extracts steam, sets a blow rate by analyzing water quality of feed water in advance, and controls the set blow rate to a boiler control device. In the boiler that performs intermittent blow that discharges a part of the can water by opening and closing the blow valve based on the blow rate, the control device controls the water supply path that supplies water to the boiler. On the way, a water supply electric conductivity sensor for measuring the electric conductivity in the water supply is provided, and the control device has a calculation formula for calculating the blow rate from the electric conductivity and calculates the blow rate from the electric conductivity in the water supply. Blow rate calculating means and comparing means for comparing the calculated blow rate calculated from the electric conductivity with a preset initial blow rate are provided, and while the calculated blow rate is smaller than the initial set blow rate, Intermittent blowing is performed at the value of the initial setting blow rate, and when the calculated blow rate becomes larger than the initial setting blow rate, intermittent blowing is performed at the value of the calculated blow rate. Control method.