Shell and tube for low delta T with steam

[UtilityLouie]

I'm trying to replace an existing shell and tube heat exchanger that was oversized by quite a bit, but want to make sure I'm not missing a better piece of equipment for this application...

Fluid:
Glycol (40%)
EWT - 85 F
LWT - 115 F
GPM - 2000

Steam:
60 psig

I think with the big delta T between the steam and glycol is causing the problems. I've seen the welded plate and frame units with a super small contact area. Is this the right application for this unit.

 

[Yorkman]

It looks like 30,000 Lbs/hr is your steam usage, but the 60 psig (300 degrees +/-) seems a bit high for an application that requires 115 degree water. I've expeirenced some difficulty with welded plate and frames due to large differentials causing thermal stesses that damaged the exchanger. Are you using some type of mixing valve? Or are you coming straight from the heat exchanger to your procees? If not that may be a way to keep the approaches closer and still get your 115 degree water.
Or can you divide the load between several heat exchangers so you can reduce the supply pressure, and main size, there by keeping the approach a little closer. Just some thoughts to ponder

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int.

 

[pmover]

the typical, off the shelf, plate frame exchangers are generally not suitable for applications with high temperature differences. furthermore, the fluid for both streams must be kept clean; otherwise, fouling may likely take place rather quickly.

plate frame exchanges are beneficial in that they are compact and have a relatively smaller plot space when compared to s&t exchangers of same duty.

yorkman's suggestions are worthy of consideration.

good luck!
-pmover

 

[imiols]

There is a better way to do this. Using a closed looped heat exchanger. It will be cheaper than the rest and can get you the perameters that you need.

http://www.niagarablower.com

 

[TD2K]

You could try contacting Alfa Laval for their Compabloc welded plate and frame. Your temperatures shouldn't be giving you a problem on a shell and tube if it's designed for them.

When you say you think the high differential temperatures are giving you problems, what are they?

 

[Joesteam]

I have not seen a problem with operating a heat exchanger with 60 psig with your required temperatures. It is the steam control valve that will regulate how much steam is sent to the exchanger based on the outlet temperature of the liquid. Often the control valve modulates down close to the seat so that the amount of steam that is condensing in the exchanger is less than the amount entering and the heat exchanger actually operates under vacuum conditions at much lower temperatures than the saturation temperature.
If it were me, I would consider two heat exchangers or 1/3-2/3 steam control depending on the ACTUAL minimum and maximum flow rates of the glycol, and you will DEFINATELY need gravity drainage and a couple of massive steam traps....

 

[Joesteam]

I have not seen a problem with operating a heat exchanger with 60 psig with your required temperatures. It is the steam control valve that will regulate how much steam is sent to the exchanger based on the outlet temperature of the liquid. Often the control valve modulates down close to the seat so that the amount of steam that is condensing in the exchanger is less than the amount entering and the heat exchanger actually operates under vacuum conditions at much lower temperatures than the saturation temperature.
If it were me, I would consider two heat exchangers or 1/3-2/3 steam control depending on the ACTUAL minimum and maximum flow rates of the glycol, and you will DEFINATELY need gravity drainage and a couple of massive steam traps....