Boiler Water pH & TDS

Have you measured the pH and TDS of the RO and sugar processing condensate feeds separately?

There could be some little amount of NaOH from your condensate from bleaching the sugar. NaOH is a base that's why you have a base solution. Just like JohnDG said, it's preferably have it tested both source for pH and TDS and dilute to proper proportions using

pH(RO)xVolumetric flow (RO)+ pH (sugar condensate) x Volumetric flow (sugar condensate) = Standard pH x (Volume RO+sugar condensate)

You could also do above equation using TDS--just replace pH.

Pls. double check if above equation is correct, but I think it is.

Hope this helps.

My Friend,

Thank you and grateful to you.

Regards

Dear Friend,

We have studied your expert opinion practically. The PH range from 10.8 to 11.0 is fine. We are hourly checking condensate from evaporators for TDS and sugar. If TDS in condensate are high it may due to raw water valves leakages but no such case observed since last month.

As you mentioned that normally TDS in feed water are in the range of 3 to 5 ppm then will take 1250 hrs to reach up to 500 ppm. It means that we need not to blow down for about 52 days. Is it advisable?

Below please find boilers water operating data sheet. Please study and comments.

Once again thanks for giving nice tips.

Regards,

M. Bilal

Sr. General Manager

Almoiz Industries Ltd.,

Dera Ismail Khan, PAKISTAN

Have you checked your instruments for accuracy?

Check each condensate stream to determine source.

There is really not enough information from your initial post, Mr. Bhatti.

Please give us a bit more history: (1) average boiler TDS for the previous month, (2) average RO TDS and source water TDS (for previous month), processing area condensate (return) TDS average for previous month, and any notes about high values showing up on test records. Also, what portion of steam output is for direct steam heating of the process area, and what portion is used to drive turbine or other machinery to provide motive power in the plant? On a boiler as you describe with low % condensate return the need for blow-down will be more than one with >90% condensate return, and also the boiler TDS can be affected by the ratio of any chemical addition rate (boiler treatments) to blow-down. Do you have a heat recovery system on the boiler blow-down?

Further: what sampling arrangements do you have? Do you have proper sample coolers on these, and what is the cooling water provided to these? What is the calibration interval on your water testing equipment, and are there records of calibrations? Do you have online active instruments that automatically test the boiler water sample? How long since previous calibration? Old style analog sensor technology, or new digital smart sensor technology?

Is the water treatment system comprised of water-softener, RO only, and is the RO a single pass permeate RO? Is there no downstream demineralizing equipment?

What water quality standards have been imposed by the various equipment OEM's that have provided you with equipment using your steam? Is there a silica concentration limit? Iron limit? TDS limit? And so it goes.

Another poster mentions 500 TDS as the upper limit for the class of boiler you have, and I can at least tentatively agree with that, however, certain boiler corrosion issues may become more apparent with this higher TDS level, also there may be boiler carry-over into the steam, through less than unit efficiency of de-misters, silica volatilization into the steam, etc. Solids carryover into the steam can result in superheater damage, and also damage rotating equipment powered by steam.

Does your boiler system incorporate steam attemperation? What is the source of the attemperation water? Is it boiler-feedwater? If so, not being aware of the TDS in that at all times, can lead to a serious problem with contamination of the steam with repect to previous argument requiring protection of downstream equipment.

Hi Everyone,

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Waste Water Treatment , Blow Room