JPH0554003B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a water supply control unit that maintains the can water level at an appropriate value as steam is consumed in a boiler system, and a water supply means and a chemical solution supply means connected thereto. This invention relates to a chemical injection control device for a boiler system having a boiler system, and particularly relates to a chemical injection control device that stops injection of chemical liquid when the PH or electrical conductivity of boiler can water reaches a predetermined set value. It is something.

<Prior art> In general, in boiler systems, water supply control is performed to constantly maintain the can water level at an appropriate value in response to steam consumption during boiler operation. To prevent this, chemical solutions (can cleaners, oxygen absorbers) are injected at the same time as water is supplied.

FIG. 1 shows a conventional example of such a chemical injection control device, in which a boiler 1 is provided with a water level gauge 2 for detecting the water level in the can, and a water supply control section 3 is connected to this. On the other hand, a water supply pump 4 as a water supply means is connected to the boiler 1, and a chemical liquid pump 5 as a chemical liquid supply means connected to a chemical liquid tank 6 is also connected to the boiler 1. It is connected to the water supply control section 3. Reference numeral 7 denotes a combustion control section which controls combustion intermittently according to the steam pressure of the steam from the boiler 1 so that the steam pressure remains within set upper and lower limits.

In the above configuration, the water supply control unit 3 sends a water supply command signal S1 in order to control the water supply intermittently so that the canned water level in the boiler 1 remains within the set upper and lower limit values in response to fluctuations in the canned water level measured by the water level gauge 2. When is output, in response to this, the water supply means 4 and the chemical solution supply means 5 start operating to supply water to the boiler 1 and simultaneously supply the chemical solution at a fixed ratio.

<Problems to be Solved by the Invention> However, according to the above-mentioned prior art, since the chemical solution is supplied to the boiler at a constant ratio in accordance with the water supply, the operation As the process continues, the chemical solution in the boiler can water becomes concentrated, and at the same time, the PH of the can water increases, and the electrical conductivity, which is correlated with the PH, also increases. By the way, the scale adhesion prevention effect and corrosion prevention effect of the chemical solution on boiler cans gradually increases until the pH or electrical conductivity of the chemical solution reaches a predetermined value (about PH 11.6, electrical conductivity about 3500 μs/m). However, even if the value exceeds that value, the above-mentioned effect will not be exerted that much more, and the effect will remain approximately constant, so the problem is that the medicinal solution injected thereafter will be wasted. It was hot.

Moreover, there was the problem that an increase in PH or electrical conductivity that was higher than necessary could lead to carryover.

<Means for Solving the Problems> In view of the problems such as wasteful consumption of injected chemical liquid in the chemical liquid injection control device in the boiler system based on the above-mentioned conventional technology, the present invention provides a water supply control unit and a system connected thereto. In a chemical liquid injection control device having a water supply means and a chemical liquid supply means, a chemical liquid supply stop means is interposed and connected between the water supply control part and the chemical liquid supply means,
On the other hand, the above-mentioned problem is attempted to be solved by providing a PH detector or an electrical conductivity detector in the boiler and connecting this to the chemical solution supply stop means via a comparator.

<Operation> The structure of the present invention is such that when the water supply means and the chemical solution supply means are interlockedly controlled by the water supply control section and the canned water and the chemical solution are supplied to the boiler at a constant ratio, Detect the rising PH or electrical conductivity of canned water with a PH detector or ratio conductivity detector, and compare the detected value with the PH setting value or electrical conductivity setting value with a comparator. When the value exceeds the set value, a chemical solution supply stop command signal is output from the comparator and is supplied to the chemical solution supply stop means, and the chemical solution supply stop means that receives the command signal takes priority over the interlocking control by the water supply control section 3. The system stops the operation of the chemical solution supply means, thereby stopping the supply of any further chemical solution, and acts to keep the PH or electrical conductivity of the boiler canned water below a predetermined set value.

<Example> Next, an example of the present invention will be described based on FIG. 3 as follows.

In the figure, a chemical liquid supply stop means 8 is interposed and connected between the water supply control unit 3 and a chemical liquid pump 5 as a chemical liquid supply means.
Alternatively, a known PH detector or a known electrical conductivity detector 9 for detecting electrical conductivity is provided in the can, and this is connected to the comparator 10.
is connected to the chemical solution supply stop means 8.

In the above configuration, the water supply means 4 and the chemical supply means 8 are driven in response to the water supply command signal S1 from the water supply control section 3 according to the steam consumption of the boiler 1,
When canned water is supplied into the boiler 1, the chemical solution is also supplied at a constant ratio in conjunction with this. As the operation of the boiler 1 continues with intermittent operation of the water supply means 4 and the chemical solution supply means 8, the chemical solution in the boiler can water becomes concentrated, and as shown in FIG. The pH and electrical conductivity of will increase. This PH or electrical conductivity is detected by a PH detector or electrical conductivity detector 9, and a detection signal S2 representing the detected value is sent to a comparator 10.
Then, the comparator 10 detects this detection signal S
Compare the detected value represented by 2 with a predetermined PH setting value or electrical conductivity setting value,
When the detected value exceeds the set value, a chemical liquid supply stop command signal S3 is supplied to the chemical liquid supply stop means 8.
In response to this, the chemical liquid supply stop means 8 transfers the water supply command signal S1 from the control unit 3 to the chemical liquid pump 5, giving priority to the intermittent operation of the water supply pump 4 and the chemical liquid pump 5 by the water supply control unit 3. Because it blocks
The operation of the chemical liquid pump 5 is stopped at that point, and the supply of the chemical liquid is cut off. After that, as shown by the dashed-dotted lines in Figure 2, even if water is supplied intermittently, chemical solution is not injected into boiler 1, and increases in the pH and electrical conductivity of canned water are suppressed. .

<Effects> As described above, according to the present invention, in a boiler system chemical injection control device having a water supply control section, a water supply means and a chemical supply means connected to the water supply control section,
By intervening and connecting a chemical solution supply stop means between the water supply control unit and the chemical solution supply means, and on the other hand, providing a PH or electrical conductivity detector in the boiler can and connecting it to the chemical solution supply stop means, When the PH or electrical conductivity of boiler canned water exceeds a predetermined set value, the chemical supply stop means stops the operation of the chemical supply means, so even if the canned water is concentrated, the PH Alternatively, since the chemical liquid is not injected when the electrical conductivity exceeds the set value, there is an excellent effect that wasteful consumption of the chemical liquid can be prevented.

Furthermore, since the PH and electrical conductivity of boiler canned water are not increased more than necessary, there is also the effect that the risk of carry over can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the prior art, FIG. 2 A is an operational characteristic diagram of the prior art and the present invention, and FIG.
FIG. 3, which is an enlarged view of the X section in FIG. A, is a block diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Boiler, 3... Water supply control unit, 4... Water supply means (water supply pump), 5... Chemical solution supply means (chemical solution pump), 6... Chemical solution tank, 8... Chemical solution supply stop means, 9... PH value detector or electric power rate detector, 10... comparator.

Claims (1)

[Claims] 1. A boiler system comprising a water supply control section 3 for maintaining the can water level of the boiler 1 at an appropriate value, and a water supply means 4 and a chemical supply means 5 connected to the water supply control section 3, respectively. In the chemical liquid injection control device, the water supply control section 3
A chemical liquid supply stop means 8 is interposed between the chemical liquid supply means 4 and the chemical liquid supply means 4, and the pH or electrical conductivity of the boiler can water is detected, and a detection signal S2 representing the detected value is generated.
A PH detector or electrical conductivity detector 9 that outputs Alternatively, a comparator 10 that outputs a chemical liquid supply stop command signal S3 when the electrical conductivity value exceeds the set value is connected to the chemical liquid supply stop means 8, and the chemical liquid supply stop means 8 outputs a chemical liquid supply stop command signal S3. In response to this, the chemical solution supply means 5
A chemical injection control device for a boiler system, characterized by stopping the operation of the boiler system.