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brian_chapin
11-12-2007, 09:59 PM
We've been using Nalco water treatment chemicals in our 5 evaporative condensers for as long as we can remember.

Recently we took a look at the price we are paying for these chemicals and were somewhat astonished.

Can anyone recommend a different water treatment chemical supplier for a company on the east coast of the US?

We are not interested in magnetics or anything else - just alternative suppliers for treatment chemicals.

Grizzly
12-12-2007, 12:21 AM
Brian.
First question is:-
1) Do you pay for the chemicals used? Or
2) Does Nalco pay for the chemicals used and are paid to provide you with fully inclusive service?
Just have a walk around the bases of your evaps and somewhere there will be a "bleed off" drain line.
Watch the frequency and volume of this bleed line.
The greater the "bleed off" the greater volume of fresh water needed to maintain the working level in the sump.
The more water added the more chemicals used!!
The "bleed off" rate is fairly flexable.
If your customer is paying by the amount of chemicals used. You err on the generous side as to the volume released.
Whereas if as the contractor I am paying for the chemical um! I think I would shut it down a bit.
This statement may may not be completely accurate but over the years I have observed a lot of chemicals going down the drain!
I even had the situation where the dosing pump for the chemicals failed on 1 tower. A replacement was ordered from America and 6 months later when it arrived it was fitted. During the 6 months I checked the water weekly and chlorinated the tower once.
Guess what it passed all the relevant tests weekly and our chemical useage was zilch! Or at least next to nothing.
I hope this is of help?
Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif

US Iceman
12-12-2007, 03:05 AM
Another way to view this is... are you having problems with the water treatment? If not, and Nalco is doing a good job then you are basing the decision solely on cost.

If you change suppliers to save a few bucks, will they guarantee the replacement of your condensers if they fail to maintain your condensers in the same condition as you currently have them with Nalco?

I doubt they will provide that kind of guarantee, so if you do save a few bucks and then the condensers scale up, what have you saved?

Finding a good water treatment company is hard enough (no pun intended) so if you do change I would hold the new firms feet to fire. Otherwise, you stand to risk a lot.

NH3LVR
12-12-2007, 03:57 AM
Just a bit to throw in here.
I had trouble with a National Company, which I will not mention on the forum.
The growth in the loop got worse and worse, and we kept buying more and more chemical, and things got worse still.
After some checking I located a guy who I had used in the past. He had changed companies and it took a little effort to find him.
Within days the loop had been sterilized, and never got out of control again.
It is the expereience of the person, not the company behind it, nor the degrees that count. Also it is his or her integrity.
However my guy does not sevice the East Coast.

brian_chapin
12-12-2007, 02:51 PM
We pay for the chemical - I know are bleed rates are good because we automatically bleed based on electronically measured solids concentration. Water usage itself is something we keep a very close eye on.

If it were a few bucks I was talking about then I wouldn't be concerned.

I just find it hard to believe that a 50gal drum of scale inhibitor is really worth in excess of $2,000 and would like to see what other options are out there.

btw, that inhibitor is downright cheap compared to what we are paying for biocide.

We own the chemical pumps, chemical tanks, feed lines, automatic controllers, etc. I'm just hoping we can source our chemicals elsewhere even if simply use the lower prices elsewhere to stop our current supplier from habitually raising chemical costs.

I'm sure you all know how costs tend to skyrocket when you only have ONE possible supplier.

smpsmp45
13-12-2007, 09:03 AM
If you are keen I can send you some data from India. THis company is making those chemicals & has been widely used for evaporative condesners in many places.

low temp
15-12-2007, 10:54 PM
Perhaps you could consider a non-chemical water treatment system. Evapco has recently released a system in which they call Pulse~Pure. It typically requires less bleed and therefore uses less water than chemical treatment systems. You will never need to buy chemicals again. I have several customer in the NJ/NYC area using them successfully.

More info can be found on a short video at Evapco's website. I can not post the link as this forum won't let me.

NH3LVR
16-12-2007, 01:40 AM
Perhaps you could consider a non-chemical water treatment system. Evapco has recently released a system in which they call Pulse~Pure.
I have read about Evapco's new system. I am skeptical, but willing to listen. Do you have any comparisons between plants using it Vs Chemical treatment?

Sergei
21-12-2007, 05:55 PM
Some companies shut off the water for winter dry operation of evaporative condensers, to save on water and chemicals. Is it smart approach?

Grizzly
21-12-2007, 08:02 PM
Some companies shut off the water for winter dry operation of evaporative condensers, to save on water and chemicals. Is it smart approach?

Sergei.
Have you seen this done?
IF it works? It surely must be down to extreme low temperatures.
In U.K. If you turn off the water pump the plant would trip out on HP.
Ok there are some exposed locations that over condense sometimes. But I have never tried to turn the water off.
After all they are not called Evaporative for nothing!
Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif

Sergei
21-12-2007, 08:37 PM
I saw a few plants. Usually, these plants are cold storages. They have lower refrigeration load in winter. If capacity of condensers are well designed, these plants can run dry when ambient temperature lower than 0 deg C.

brian_chapin
24-12-2007, 02:26 PM
Some companies shut off the water for winter dry operation of evaporative condensers, to save on water and chemicals. Is it smart approach?

Well, there are positives and negatives associated with it.

On the east coast of the US here so usually we run two of our three evaporative condensers dry in the winter. One with water and vfd fans takes care of the load using the other two condensers for unusually high loads. Generally we have no problems in the winter keeping a head pressure of 120psig.

Positives: 1) Less water and water treatment chemical use. 2) Sump heaters can be turned off on the dry condensers. 3) In our situation we never have to worry about the remaining wet condenser freezing since there is always enough load to keep that water above freezing.

Negatives: 1) If something happens to the wet evap, it takes a while to get a dry one filled back up again. 2) Dry coils tend to have greater corrosion than wet ones according to most manufacturers.

It really depends on your load - this facility makes and stores ice cream and bagged ice so our load tends to drop off in the winter quite a bit.

josef
24-12-2007, 05:40 PM
Hallo.
I don't think as though is good arrange much chemicals, Shall I condensers mostly BAC and one Evapco, that Evapco goes without adjustment and chemistry, only turns water every week - 16 years. Magnetic adjustment be but scrapped investment. Condenser in fever period without waters in my opinion deteriorates his service life. Alone odds if pay invest in adjustment and to the chemicals and stretch out the life span of and condenser duty. Shall I experience as though and good water conditioning engagement sediments and in winter on dry atmosphere behind frost will crackle and affects surface adjustment condenser. Josef

Sergei
24-12-2007, 08:03 PM
Well, there are positives and negatives associated with it.

On the east coast of the US here so usually we run two of our three evaporative condensers dry in the winter. One with water and vfd fans takes care of the load using the other two condensers for unusually high loads. Generally we have no problems in the winter keeping a head pressure of 120psig.

Positives: 1) Less water and water treatment chemical use. 2) Sump heaters can be turned off on the dry condensers. 3) In our situation we never have to worry about the remaining wet condenser freezing since there is always enough load to keep that water above freezing.

Negatives: 1) If something happens to the wet evap, it takes a while to get a dry one filled back up again. 2) Dry coils tend to have greater corrosion than wet ones according to most manufacturers.

It really depends on your load - this facility makes and stores ice cream and bagged ice so our load tends to drop off in the winter quite a bit.
Hi, Brian Chapin.
I'd like to give my point to dry operation.
1. Corrosion. I don't think this is issue for evaporative condenser during dry operation. Two major factors of corrosion are moisture and warm temperature. Any moisture on coil will evaporate very quickly due low humidity of ambient air. Subzero temperatures won't help corrosion as well.
2. Energy. Usually, we save energy in refrigeration by trading off between different parts of refrigeration plant. For example, we spent additional 10 HP for condenser power and saved 30 HP for compressors due to lower condensing pressure. This is step to the right direction, because we saved 20 HP. The same approach should be applied to dry operation. Very often we can invest $1,000 for water and chemicals and save $10,000-20,000 for energy. Usually, this approach doesn't require capital investment and pay back is very short. I believe that optimization of refrigeration plant operation is best way to save energy and can be done for many facilities. For your refrigeration plant. Run wet 2 condensers and reduce the speed(VFD) of condenser fans simultaneously for both condensers. This will save you energy compare to dry operation.
Another interesting issue is 120 psig condensing pressure. I know that many people believe(sometimes even good P.E.) that this is minimum allowable pressure for ammonia refrigeration plants. To save energy, condensing pressure should be as close as possible to optimum one. In winter time, optimum condensing pressure well below 100 psig. Certainly, every refrigeration plant has barriers to reduce condensing pressure, but every barrier has solution.

brian_chapin
26-12-2007, 02:24 PM
In winter time, optimum condensing pressure well below 100 psig. Certainly, every refrigeration plant has barriers to reduce condensing pressure, but every barrier has solution.

We have some txv driven dock coolers that don't tend to function well below 120psig. I know we can get them to work with EXVs' but haven't gotten around to pricing it.

Once that barrier is overcome then I have to consider our oil cooling.

Currently I am getting bids on installing instrumentation to automate or float our head pressure as we are doing it manually now. I'm certain we are not as efficient as we could be but considering we were locked at 160psig condensing when I came here two years ago I think we are making forward progress.

Andy
26-12-2007, 02:46 PM
We have some txv driven dock coolers that don't tend to function well below 120psig. I know we can get them to work with EXVs' but haven't gotten around to pricing it.

Once that barrier is overcome then I have to consider our oil cooling.

Currently I am getting bids on installing instrumentation to automate or float our head pressure as we are doing it manually now. I'm certain we are not as efficient as we could be but considering we were locked at 160psig condensing when I came here two years ago I think we are making forward progress.


Hi Brian:)

as a rule we would not go below 6 barg or 90 psig on EEV's, much lower than this and the whole plant will hunt.

You could ofcourse add a solinoide and oriface plant to supliment the EEV's at lower head, activated by a pressure switch on the liquid line (or some of the danfoss controllers have a contact used to bring back the head pressure control at a pre set valve opening degree say 90% thu, you could use this).


Kind Regards Andy:)

Sergei
26-12-2007, 05:29 PM
We have some txv driven dock coolers that don't tend to function well below 120psig. I know we can get them to work with EXVs' but haven't gotten around to pricing it.

Once that barrier is overcome then I have to consider our oil cooling.

Currently I am getting bids on installing instrumentation to automate or float our head pressure as we are doing it manually now. I'm certain we are not as efficient as we could be but considering we were locked at 160psig condensing when I came here two years ago I think we are making forward progress.
In winter time, dock coolers don't require full capacity, because lower refrigeration load due to low ambient temperatures. Some docks require heating to keep dock temperature at acceptable level. Do you really need EVXs?
Certainly, 120 psig head pressure is better than 160 psig. Floating of head pressure, usually based on wet bulb approach feature. Wet bulb approach is useful some refrigeration plants and useless for others. Make sure that you will benefit from floating head pressure.