JPH1026307A - Method of controlling chemicals feeding for boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the quantities of chemicals fed into feed water, in conformity with a state of concentration of boiler water, and to enable proper feeding of the chemicals, in a boiler wherein a concentration blow is conducted. SOLUTION: In a boiler wherein a chemicals feed line 6 provided with a chemicals feed pump 4 and a chemicals tank 5 is connected to a feed water line 3 connected to the boiler 1 and a chemicals feed control device 7 controlling the operation of the chemicals feed pump so that chemicals are fed at a prescribed feed rate for the quantity of feed water is connected to the chemicals feed pump 4 and wherein steam is generated by heating the water fed to the boiler. The boiler water concentrated by evaporation is subjected to a concentration blow at a prescribed blow rate by a blowing device conducting discharge of the boiler water, the chemicals feed control device 7 is provided with a chemicals feed rate correcting means to which the blow rate in the blowing device can be inputted and which conducts correction of the chemicals feed rate by the inputted blow rate, and the chemicals feed control device 1 controls the operation of the chemicals feed pump in accordance with the chemicals feed rate corrected by the chemicals feed rate correcting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling chemical injection of a boiler.

[0002]

2. Description of the Related Art In a boiler, a chemical injection line is connected to a water supply line in order to prevent corrosion and the like, and chemical-treated water is supplied by operating the chemical injection pump in conjunction with a water supply pump. . For chemical injection, the quality of the water supply to the boiler is analyzed in advance, and the injection ratio of the chemical to the water supply is determined as the injection rate based on the water quality, and the injection pump is operated based on the water supply to the boiler and the injection rate. It is performed by controlling. The water supplied into the boiler is taken out as steam by heating, and impurities contained in the feedwater are concentrated by repeating evaporation and water supply. If the concentration of the can water has not progressed, it is necessary to inject the chemical at a relatively high rate. However, when the can water is concentrated, the concentration of the chemical in the can water increases, so that the amount of the chemical that needs to be injected decreases.

[0003] In a boiler, if the canned water is concentrated too much, a problem such as carry-over occurs. Therefore, the concentration of the boiler is reduced by performing the concentration blow at a predetermined blow rate with respect to the supplied water amount. The concentration state of the can water differs depending on the blow rate. When the blow rate is set high, the concentration is kept low, and when the blow rate is set low, the concentration becomes high. For this reason, even if the injection rate determined from the water supply quality is the same, if the blow rate is different, the optimum injection rate will be different, resulting in an excessive amount of chemical injection or a shortage of chemical injection. is there. Further, in the case of a boiler in which the blow rate is corrected during operation as described in Japanese Patent Application Laid-Open No. 8-105604, the optimum chemical injection rate has always been changed.

[0004]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is that in a boiler performing a concentration blow,
An object of the present invention is to make the amount of chemical to be injected into the feed water an optimal amount in accordance with the concentrated state of the can water so that the chemical can be injected without excess or shortage.

[0005]

[Means for Solving the Problems] A water supply line connected to a boiler is connected with a chemical injection line provided with a chemical injection pump and a chemical liquid tank. A dosing control device that controls the operation of the dosing pump is connected so that the injection of the drug is performed, and steam is generated by heating the water supplied to the boiler. In a boiler that performs concentration blow at a predetermined blow rate by a blow device that discharges canned water, the blow rate in the blow device can be input, and the drug injection rate is corrected based on the input blow rate. Means are provided, and the dosing control device controls the operation of the dosing pump according to the dosing rate corrected by the dosing rate correcting means.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. A water supply line 3 connected to the lower part of the boiler 1 is provided with a water supply pump 2 and an electric conductivity detecting device 11 in the middle thereof, and a chemical injection line in which a chemical solution tank 5 and a chemical injection pump 4 are provided in the middle of the water supply line 3. 6 are connected. A blow pipe 8 is connected to a lower portion of the boiler 1, and a blow valve 9 is provided in the middle of the blow pipe 8. The boiler control device 12 is connected to each of the boiler combustion device 13, the feedwater pump 2, the water level detection device 14 for detecting the water level in the boiler, and the electric conductivity detection device 11 by signal lines, and is connected to the blow valve 9 and the blow valve. A blow control device 10 for controlling the opening and closing of the pump 9 and a chemical injection control device 7 connected to the chemical injection pump 4 for controlling the operation of the chemical injection pump 4 are also connected.

[0007] Each operation of the boiler is controlled by a boiler control device 12. When the water level in the can detected by the water level detection device 14 is lower than the lower limit water level, the boiler control device 12 operates the water supply pump 2 and starts water supply through the water supply line 3. The water level is kept constant by stopping the operation of the pump 2, and the water supply signal is also output to the chemical injection control device 7. Combustion device 1
The combustion by 3 is also controlled by the boiler control device 12, and the combustion of the combustion device 13 is performed according to a combustion command from the boiler control device 12. The electric conductivity detecting device 11 measures the electric conductivity of the feed water and transmits the measurement result to the boiler control device 12.
Output to The boiler control device 12 calculates the blow rate based on the measured electric conductivity and a previously input calculation formula, and outputs the blow rate to the blow control device 10 and the chemical injection control device 7. The boiler control device 12 includes a combustion device 13
The combustion command output time is integrated, the amount of combustion and the amount of water supplied to the boiler are calculated, and output to the blow control device 10.

In the blow control device 10, the boiler control device 1
The blow timing is determined based on the water supply amount and the blow rate obtained in step 2, and the blow valve 9 is opened and closed. The chemical injection control device 7 is provided with a chemical injection rate correcting means having a calculation formula for correcting the chemical injection rate based on the blow rate, and the chemical injection rate is calculated from the blow rate obtained by the boiler control device 12 and calculated. The operation of the chemical injection pump 4 is controlled based on the obtained chemical injection rate and the water supply signal. By operating the chemical injection pump 4, the chemical in the chemical solution tank 5 is sent to the water supply line 3 through the chemical injection line 6, mixed with the water supplied in the water supply line 3, and supplied into the boiler 1. The boiler 1 heats the can water by the combustion of the combustion device 13 to generate steam, and the concentrated can water is discharged through the blow pipe 8 by opening the blow valve 9.

[0009]

According to the present invention, the amount of chemicals to be supplied into the feed water can be set to an optimum amount without excess or deficiency according to the concentration state of the still water.

[Brief description of the drawings]

FIG. 1 is a flowchart of an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 boiler 2 water supply pump 3 water supply line 4 chemical injection pump 5 chemical liquid tank 6 chemical injection line 7 chemical injection control device 8 blow pipe 9 blow valve 10 blow control device 11 electric conductivity detection device 12 boiler control device 13 combustion device 14 water level detection apparatus

Claims (1)

[Claims] 1. A chemical injection pump and a chemical injection line provided with a chemical liquid tank are connected to a water supply line connected to a boiler, and the chemical injection pump is capable of injecting chemicals at a predetermined chemical injection rate with respect to the supplied water amount. A dosing control device that controls the operation of the dosing pump is connected so that steam is generated by heating the water supplied to the boiler, and the can water concentrated by evaporation is discharged as can water In a boiler performing a concentration blow at a predetermined blow rate by a blow device that performs a blow rate, a blow rate in the blow device can be input, and a drug injection rate correction unit that corrects the drug injection rate based on the input blow rate is provided. A chemical injection control method for a boiler, wherein the chemical injection control device controls the operation of the chemical injection pump according to the chemical injection rate corrected by the chemical injection rate correction means.