1 reply to this topic

[Matteo Giorgio Marrano]

Good morning,

I asked an offer for a water bath heater to an experienced company that designs indirect heaters and desalters..

The bath temperature is 90°C. The solution is 50% Water and 50% Glicole

The result of the sizing is an indirect heater with these dimensions:
- length: 15000 mm
- diameter: 4270 mm

The expansion tank to be put above the heater have these dimensions:
- lenght: 3050 mm
- diameters: 680mm

My doubt regards the size of the expansion tank given by the company.

Consider that the vessel is full of water. The initial temperature will be ambient temperature (20 °C); the final temperature will be 90 °C. For this reason the expansion tank will be able to handle the thermal expansion of the water from 20 °C to 90 °C, right?

From a table and calculations, I founded that from 20 °C to 90 °C the expansion in volume of water is approx 3.5%, so that if I have 100 m3 of water, I will need a 3.5 m3 expansion tank.

The expansion tank given in the offer have a volume lower than 4% of the volume of he indirect heater; why? I don't think it depends only on the fact that there is a water/glycol solution in, there is something that i'm missing...

So, my question is: considering an indirect heater of:

- lenght: 15000 mm
- diameter: 4270 mm
- bath temperature:90°C
- bath solution: 50% water/50% glicol

What will be the right size for the expansion tank? Is the one given by the company right?

thank you in advance,

Matteo

[djack77494]

Matteo,
I like your approach to figuring out the sizing of the expansion tank. However, as you heat the contents of the water bath, the expansion must begin and end in such a way that you know the volume occupied. So, for example, you might want the minimum liquid volume to be 20% and the maximum volume to be 80% of the tank's volume. That's an even bigger problem than the one you presented.

In your situation, I would examine vessel drawings looking specifically for level instrument connections. My thinking would be that the manufacturer would want "to see" the maximum and minimum levels. Quite possibly, the minimum level is within the bath itself rather than in the expansion tank. So carefully look over the manufacturer's information in an attempt to satisfy your interest. Good luck.