Booster Pump to Prevent Cooling water from Vaporizing

[Watkins1j]

I am working with a chemical engineer on a project to stop water from vaporizing as it enters a cooling coil in a tank. The tank has product in it that we keep at a temperature ranging from 235°F to 250°F before we start pumping out. We have cooling water supplied by our towers at 40 - 45 psig and around 72°F. When the product temperature is around 245 - 250°F we start seeing the cooling water line vapor locking and causing more issues with the pump out of the tank.

I am looking at adding a booster pump on the supply line to see if we can get more pressure to prevent the water from vaporizing. As it stands now and looking at the saturated steam tables if we were to get 15 - 20 psig more pressure in the line we should prevent the vapor from occurring.

[highlight #FCE94F][/highlight]Has anyone ever done this with success or is there a better solution to preventing water from vaporizing? Like cooling the water down further before it enters the tank?[/color]

The product in this tank is amines based and the tank is 40 feet in height.

 

[LittleInch]

Looks pretty straightforward to me. Alternatively use a fluid with a higher BP (thermal oil) and then a secondary HE.

The issue will be how do you maintain the pressure at all times. If it drops below the vapour pressure then it will start boiling again.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Compositepro]

Vapor locking will occur with air more than steam. What does vapor-locking really mean in this case? If you have water going into a pipe at pressure and the other end is at lower pressure then water should flow through the pipe. If you are are getting a vapor pocket at a high point in the piping you must have the capability to clear it by flowing water at a high enough rate to push the bubbles downhill, or you need an air vent at the high point. Cooling tower water has plenty of dissolved air, which gets less soluble as water temperature increases.

 

[StoneCold]

Watkins1J
While the theory behind your idea is sound you might want to go a little further. Boosting the inlet pressure is only going to work if you can force enough water through the coil to raise the OUTLET pressure above 20 psig. I would suggest you do a couple more things. First make a sketch of what you have with pressures and measured temperatures so that people here can actually help you out. Second sit down and do a mass balance on the cooling water to figure out a theoretical flow rate and temperatures. Third thing do a hydraulic model and see if you can get it to match up to what you are seeing at the tank. Fourth thing to do is see what your velocity in the pipe is. Are you running fast enough to sweep out any air that is developing? Once you have all that you can run new scenarios with a booster pump, or possibly an orifice plate at the outlet of the tank to give you the backpressure you need to keep the water from flashing.

That's my two cents.

Regards
StoneCold