Author Topic: Raw city water quality range  (Read 1213 times)

Offline AndyS

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Raw city water quality range
« on: Dec 08, 2015, 07:55 »
Hi,

Just curious on how we can better our system to make our chemical injection more accurate. Right now we run a condensate return system that feeds into our condensate tank, which is used to feed into our boiler via our FW pump or condensate pump ( bypassing the tank ) during certain periods of the day, and once the level drops to a level raw city water is used to replenish this to its running level. This raw water is not treated what so ever prior to being injected into the tank. We batch our FW chemicals with a certain recipe and it injects a certain amount based on the flow ( volume ) that has been made up. Now some weeks the chemical readings are bang on, and some weeks we are going way up or way down. Just looking for some insight or ideas to make this more accurate? Our chief insists that the raw water and condensate quality will not change, wondering peoples insight on this?

Thanks
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Offline Jason R

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Re: Raw city water quality range
« Reply #1 on: Dec 08, 2015, 11:13 »
Does the system look like this? (See attached.)

The characteristics of raw water can change depending on what the upstream city treatment plant is doing. Maybe doing some tests on the incoming city water may help narrow down the cause.

I've also experienced that water treatment is a combination of mathematical correlations and gut instinct.

@mautio and @kenzzz may be able to shed some light on this.
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Offline AndyS

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Re: Raw city water quality range
« Reply #2 on: Dec 08, 2015, 12:24 »
Looks similar to that, the only difference is that the condensate pump feeds directly into the boiler, when the pumps running all our high pressure condensate feeds straight into the boiler, and our low pressure condensate still goes to the tank. During off times we bypass our pump and run all condensate into the tank. Also we don't have a dearator ( been hoping for one for awhile  ??? ).

It just seems odd how for a week straight we can have bang on test numbers, but the next week with identical chemical batch formula etc the readings are wayyyyy out. Our FW flow meter shows steady volume coming in, maybe the flow meter for the chemical pump controller could have something going on in it? Been going on for awhile so would love to put an end to this non stop issue .

Thanks
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Offline Colin Farquhar

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Re: Raw city water quality range
« Reply #3 on: Dec 09, 2015, 10:40 »
You say that your reading vary wildly sometimes-which specific readings?  Where are you located-you said you're feeding raw city water to your condensate tank, what are the readings on this water?  Do you have any sort of pre-treatment at all on that line (Softener?)

Colin
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Offline AndyS

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Re: Raw city water quality range
« Reply #4 on: Dec 09, 2015, 12:16 »
Hi,

There is no pre treatment, it is straight from the city into our condensate tank, basically acts as makeup water whenever the tank level drops. The main readings that drop are our phosphates, sulfites. It adds a set amount of chemical injection based on the volume of makeup water. But like mentioned, some weeks its as steady as can be, other weeks it drops like crazy or shoots up like crazy. We don't really test the quality of the city water so not sure what it is condition wise.
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Offline Colin Farquhar

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Re: Raw city water quality range
« Reply #5 on: Dec 09, 2015, 13:04 »
I would check with your city's water treatment/supply branch, find out what ranges and readings they're expecting to supply.  For example, out here: http://www.winnipeg.ca/waterandwaste/water/testResults/Winnipeg.stm  I would first look at the variables in the incoming supply-changing incoming chemistry will affect how much treatment is required.
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Offline Colin Farquhar

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Re: Raw city water quality range
« Reply #6 on: Dec 09, 2015, 13:08 »
Andy-I just saw on another post that you're in Richmond (I'm assuming BC).  If so, I guess you're getting your water from the GVRD watersheds on the North Shore?  That stuff should be pretty soft, but I could see some swings in quality with the changing water levels (and some of the wild rain you've been getting). 

I'm coming back home to BC for a few weeks over Christmas, please make sure to leave the sun out and turn the storms off ;)
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