shell and tube temps ?

[old gas bottle]

this nice wheather,s got its down side,got some old carrier hr 30,s [i think thats them] that the cooling tower temperature is getting a bit warm 25 deg C,any sites with the info on max working temperatures, cant seem to find it on the carrier site,think were on the edge here.

[US Iceman]

The numbers I remember for water-cooled equipment are based on what used to be the standard design criteria.

Water supply temp. from the tower = 29.4C (85F)
Water return temp. to the tower = 35C (95F)
Condensing temp. = 40.5C (105F)

Almost all of the older systems I've worked on were based on this set of parameters. This also takes into consideration the cooling tower will supply this water temperature (29.4C) at some maximum design wet bulb temperature for your area.

If the entering air wet bulb temperature increases, or if the tower is dirty, the temperatures may be off.

Newer systems may use different criteria due to energy saving designs for lower discharge pressure.

[binman54]

It depends on the model and operating conditions of the compressor. Try the following site as an example.
http://www.carlylecompressor.com/Fil...ngEnvelope.pdf

[old gas bottle]

there hp ,ing out,had blow off problems etc, had them running not too bad this year but the increase in water temp is killing them,just old in every way,just wondered if there was a max water supply temp as the heads are upto 275 psi,liquid lines too hot etc.cheers.

[US Iceman]

What's the refrigerant? R-22?

275 psig is way to high for water-cooled condensers (if the tower is working properly).

That's about a 125F.

If you have 25C supply water to the condenser, the discharge pressure is 275 psig, and the liquid line is too hot to hold on to, you do have problems.

If the above is correct, and you are using R-22 there are several things to check.

1) Does the water supply have a strainer in it that can be clogged up?

2) Is the pump motor amps close to full load amps?

3) Is there a water regulating valve that controls water flow into the condenser?

If #1 above does not apply, or the strainer is clean, then OK.

If #2 is true, the pump is probably running properly.

If #3 is true, then this is controlling the flow. It might be clogged up itself or not functioning properly.

Otherwise, It sounds like the condenser tubes need to be cleaned.

If the discharge pressure was high and the liquid line was cooler, I would say you had different problems.

Since the pressure is high and the liquid line is hot, the problem is either insufficient water flow to the condenser, or, the tubes are dirty.

[old gas bottle]

hi matey, its just one of those jobs,the cooling tower is enormas and supplies several chiller packs,there old and we have been battling through all sorts of problems this last year,thing is its the company pipe fitters that do the water side of things[well they should]your right in your diagnocis of course,but getting them to overhaul the system just aint happening,then the owness drops back on the chiller not working so thats where we are now,[in the poo],thanks for your input yet again. cheers.

[jamcool]

Tubes might be foul,what your approach temp. is there any type of water treatment to the tower? no treatment can cause alot of problems.Some owners don't care or don't want to spend the money but expect all to run smooth

[US Iceman]

...the company pipe fitters that do the water side of things...

They probably think their job ends at the chiller connections.

Certainly sounds as if this could be a "poo" throwing contest.

Good luck on that one!

[old gas bottle]

the poo hit the fan today ! i swiched em all off,said i,ll come back when the shells are cleaned,valves are renewed and there,s loads of water in them there hills!!

[US Iceman]

the poo hit the fan today ! i swiched em all off,said i,ll come back when the shells are cleaned...

Oh Boy! I bet the poo hit the fan.

I suppose there is nothing like shutting the AC off in hot weather to get someones attention.

Did you wipe off your fingerprints?

[old gas bottle]

no i just told them i,am sick of tweeking this and that trying to make them work without much water, i get like that,nice bloke untill i reach my hp setting,then i blow off !! it worked though,pile of bits on the plant room floor,will let you know the new running pressures soon,cheers.

[US Iceman]

...nice bloke until i reach my hp setting,then i blow off

Perhaps you are not so different than the condensers.

You just need more liquid running through you.

I hear beer is good for that! That lowers the blow off setting.

[Andy]

hi matey, its just one of those jobs,the cooling tower is enormas and supplies several chiller packs,there old and we have been battling through all sorts of problems this last year,thing is its the company pipe fitters that do the water side of things[well they should]your right in your diagnocis of course,but getting them to overhaul the system just aint happening,then the owness drops back on the chiller not working so thats where we are now,[in the poo],thanks for your input yet again. cheers.

I suppose the answer would be.

1/ clean up the existing system, rod condensers and clean strainers

2/ take some load off the towers (either add another tower to cool some o the chillers or add an evaporative condenser or two)

Good luck

Kind Regards Andy

[old gas bottle]

just had all saturday with the pipe fitters, what a mess,never had any inhibitors in, limed up beond belive, rodded the tubes,the isolation valves were siezed best part shut so replaced those,new gaskets etc,dare not add inhibitors now or it will never run again,cleaned the baskets and bingo, runs fine even limed up, 200 heads, 60 backs,striping 8 degs out, even the comps sound sweet and run cool,had to change a oil pump on one,new oil in all four comps, bit of gas, i,am a happy and relived man for a while, and yes iceman the beer followed, well about six to be exact.cheers chaps.

[US Iceman]

It might be worth the trouble to investigate the use of acid or other water treatment to maintain the tube scaling, or better yet, reduce it.

Scaling in tubes often also results in corrosion under the scale. With copper tubes it may not be so bad, but on carbon steel tubes, it can cause some "issues".

Glad you have the problem solved for the time being.

[jamcool]

Had to be involved in acid cleaning 3 chillers 2 weeks ago it took 12 hours to get 1 down to the approach temp. that we were happy with,all because water treatment was bare minimal,there was scale and silica in the tubes it was a B.... to clean we also brushed the tubes,scale and water everywhere.
Don't know about u guys but they don't pay me enough GOING ON STRIKE

[old gas bottle]

if we tried to descale this thing we would need a basket filter the size of england ! think they replace in the next year or two,hopefully i,ll be somewhere else then.

[US Iceman]

I know, the acid cleaning of condenser tubes is not much fun. Brushes only do so much, like removing the small flakes and loose stuff.

Acid cleaning is the only way to get it clean that I have seen.

If someone has seen something else that works, I would like to know what they do for this.

[old gas bottle]

if things are as bad as this one, i think alls lost,we had a small system that we added a water based protective agent with a agressor to clean the system then a protective addative to line the inner surfaces but it clogged the filters constantley for weeks and that was a relitivley clear system, when there is 1/2" of scale on the inside of 3" pipes i think its a skip and a wagon full of new pipe. cheers.

[Chris Burton]

Depending on how many compressors you've got on each circuit you can always disconnect a comp or it's unloaders to keep head pressure down. You'll have to pull the wires on the load side of the MCB as there is an interlock with the saftey circiut wired into the back. The condensor delta T on 30HR should be about 10 'c fully loaded, if it is more than this your probaly low on water flow, less & you,ve got fouling on the surface of the tubes.

[old gas bottle]

your right chris,the shell and tubes,valves were all craped up,all rodded and sorted now,cheers.