Technical discussion: How to calculate the concentration factor for using recycled water as make-up water

The ratio of the salt content in circulating cooling water to that in make-up water is called the concentration factor. This value is generally calculated as the ratio of the chloride (or potassium) ion contents in the circulating water and the make-up water, as these two ions are relatively stable in water. There is also a more convenient way to adjust the ratio of recycled water to make-up water.

This post was last edited by hesonchang214 on 10/8/2011 at 10:27. Potassium ions in recycled water are unstable, and since chlorine tablets are used to disinfect the circulating water, chloride ions cannot be used either. . So what other ways are there to measure the concentration factor?

Reply to 3# szq2000: Then use conductivity.

The various parameters of recycled water tend to change over time, making it difficult to determine the concentration factor using just one parameter. It is better to use several relatively stable parameters to calculate the concentration factor and then compute an average value. Such as conductivity, K, silica, etc.

This post was last edited by hesonchang214 on 10/8/2011 at 10:27. Learned it, hehehe!

The last edit to this post was made by hesonchang214 on 10/8/2011 at 10:28. Reply to 5# aqiao1011: One more question: 1. Regarding the algorithm for the concentration factor, how is the permutation algorithm calculated? For example, in a circulating water system with a capacity of 10,000 liters, where the evaporation rate is 150 liters per hour, how many hours will it take if the compression ratio is set between 1 and 4 (with no wastewater discharge during this period)? How is it calculated? As an example of such a situation, let’s take a production case we encountered as a reference. 2. During the replacement process, if the concentration ratio is reduced from 6 to 3 and the water replenishment rate is 500 cubic meters per hour, how long will it take to reach a ratio of 3? How many hours will it take? How is it calculated? As an example of such a situation, let’s take a production case we encountered as a reference.

You can refer to the book titled \"Chemical Treatment of Open Circulating Cooling Water Systems\" by Qi Dongzi; an electronic version is available on our forum, so you can search for it. The answer to this question is on page 29 of the book; he provides examples for both of the questions you asked.

If pollution discharge and wind loss are not taken into account, it’s actually quite easy to calculate. Assuming the potassium ion concentration in the water used for replenishment is 50 mg/L, which means the potassium content per cubic meter of water is 50 g; if the total amount of water stored is 1000 cubic meters, then the total potassium content in that system will be 50,000 g. By increasing the concentration factor of the circulating water system from 1 to 4.0, the potassium ion content tripled, an increase of 150,000 g. At this point, it is pure water that evaporates; the amount of water added is equal to the amount that evaporates. All the additional K ions come from the water added. Therefore, it can be calculated as follows: Amount of water added * 50 * T = 150,000, where 50 represents the concentration of K ions in the added water, T is the required time, and 150,000 represents the increase in the amount of K ions in the total water volume. But if pollution discharge and wind loss are taken into account, then the formulas in the book must be used.

I agree with what was said above: multiple stable parameters should be used to calculate or verify the concentration ratio. If potassium ions are not stable, silica can be used; if there are large fluctuations in conductivity, sulfate ions can also serve as a reference in the absence of an acid addition system.

Thank you for the reply; this algorithm is very straightforward and simple. One more question: My facility uses biochemical recycled water as make-up water for the circulating water system, and there is no continuous discharge of wastewater. Various methods are employed, such as measuring the K.CA. and conductivity levels in the water, to calculate the concentration factor; however, the resulting values are sometimes less than 1, or even in the tens or hundreds, making them unusable for reference ； Later, I tried to estimate it by dividing the amount of water added by the amount of water discharged, but sometimes no water is discharged, and when discharge resumes, it’s difficult to determine what the appropriate amount of discharge should be Do you have any other good methods to roughly calculate the concentration factor?