8 replies to this topic

[chemmu]

Dear Freinds,

Good Day to all.

Shall we use super critical steam in the Heat Exchanger ??

Please advise..

[markymaark]

What is your application?

I don't see a need to operate at such a high pressure. The high pressure will cause a large increase in heat exchanger cost to cope with the high pressure.

Steam Heat Exchangers rely mostly on condensation to transfer heat. Heat of vaporization actually decreases as Pressure increases for saturated steam.

50psi Steam
T=298 F
Enthalpy of Evaporation=912 BTU/lb


200psi Steam
T=388 F
Enthalpy of Evaporation=838 BTU/lb

[Sput]

Hello Chemmurugan,

I did not clearly understand your requirement. Can you please explain in detail. I have worked with supercritical fluids for 5 years and we always generated supercritical water to use as a direct injection for quick raise in temperature.

Thanks,
Satya

[Pilesar]

Supercritical steam has zero latent heat of vaporization -- it may be efficient to use in power plants, but there are probably better choices for a heating medium.

[kkala]

It is technically possible to use super critical steam in heat exchangers, but no economic advantage can be seen; partial heat transfer coefficient is anticipated to be close to superheated steam / water, much lower than this of condensing steam (~10000 kcal/m2/h/oC).

[chemmu]

Dear All,

Thank you much for your valuable inputs..

I did not come across this proplem.. But i had a doubt about the usage of supercritical steam in the Heat Exchanger.

If we use the supercritical steam, the amount of steam used is very less (because of high temperature of the steam).. Is this concept correct ????

Edited by chemmurugan, 28 December 2012 - 06:15 AM.

[krsna]

Supercritical steam boiler are working at 220bar pressure so at high pressure we can use DEU type Heat exchanger it can bear the more than 150 bar pressure

[markymaark]

We need to know what application the superheated steam is going to be used for.

[kkala]

I have seen application of supercritical steam (on paper) in steam turbines of feasibility studies. One option was to pass all this steam from turbines to produce electricity and use the exhaust steam in the plant. It was not selected, probably because : (α) Boiler feed water needs special treatment for such high pressures. (β) Steam demands of the plant were complicated enough, additional complication would be undesirable (γ) Handling of such steam is natural to cause reservedness.
Probably you have meant supecritical steam; most of superheated steam (I am aware of) is used for steam turbines as above.