How can the pH be adjusted to an exact value when using liquid caustic for adjustment? ? ?

To what precise value needs it to be controlled? Generally, the pH should be within a certain range, right?

Industrial pH meters have a relatively large degree of deviation, and they need to be calibrated frequently; how can an accurate value be achieved?

Is there really no way then? ?

It is recommended to divide it into two streams, adjust one stream to an excess level, and then mix the two streams to achieve the desired pH

For example, if the pH of the wastewater is 5 and it needs to be adjusted to 7, half of the wastewater can be neutralized to around pH 9; this is relatively easy. Once these two portions are mixed together, the pH will be around 7. Precise adjustment can be achieved by controlling the ratio of the flow rates of the two components

Try to answer the following questions for reference: 1. For the valve adjustment curve, especially with manual valves, the flow rate controlled manually is not continuous, which can easily lead to an excessive amount of lye, resulting in either an alkaline or acidic condition； A pH meter signal display is installed at the operation point, showing the inlet and outlet flow rates (cameras can be considered for channels), as well as the pH value, thereby providing the operators with the necessary parameters. It is advisable to set several additional points for the pH meter according to the process, to facilitate correction. Markings can be made on the manual valve to help operators determine its opening degree. Collect runtime statistics, analyze data retrospectively, and develop countermeasures. 2. The number of PH adjustment tanks: with just 1 tank, there is no time for humans to react; even if the water is slightly acidic, it flows away immediately, leaving no time for anyone to respond ； Emergency adjustment tanks and buffer tanks are installed; the wastewater first flows into the buffer tank. Water that meets the standards is discharged, while that that does not meet the standards is subjected to fine adjustments. If further adjustment is not possible, it is sent to the emergency tank to be processed again. 3. During automatic control: Where should the pH meter probe be placed to ensure representativeness? How many PH probes need to be installed? If there is a high amount of surfactants in the wastewater, under harsh operating conditions or at high temperatures, can the pH probe still provide accurate readings? pH regulation control for environmentally friendly wastewater discharge should have a certain degree of lag, especially in the process of neutralization using lime, which involves lime preparation, neutralization, and aeration. First, manual sampling at specific points is carried out; sampling is conducted simultaneously at the points deemed necessary based on the process analysis, and then probes are installed. The higher the temperature of the PH probe, the more expensive it is and the more difficult it is to maintain; probes containing impurities are prone to forming films that affect the stability of measurements. It is possible to consider taking samples, then installing sedimentation and filtration tanks, cooling the mixture to room temperature before inserting the probe. Although this approach seems complex, the cost of the probe and its operational costs can offset these expenses. Other: It is recommended to use a closed-loop control automated system if possible ； One can consider looking at how other companies in similar industries handle it.

Excuse me, sir on the 9th floor, what is a closed-loop control automatic control system? Could you explain in detail how it is controlled? ? Thank you!