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Flow simulation of HP feed water heater result showing water accumulation in condensing zone.

Question asked by Pandurang Nagare on Mar 2, 2016

I'm Pandurang, Working in Tema india ltd. in India, we are working on solidworks flow simulation 15 days evaluation copy (Serial key : 88000995681635697B235PJG) for High pressure feed water heater, if it is working properly we plan to purchase flow simulation license.

 

We have given the all inputs like Inlet Pressure, temp. & Flow rate for Steam inlet in the shell side (boundary condition used : Inlet mass flow) and Inlet Pressure, temp. & Flow rate for Feed water inlet in the tube side (boundary condition used : Inlet mass flow) of this heater. Outlet (boundary condition used : static pressure) temp. for both shell & tube side as per design is also given as a input (Goals are Max Temperature (fluid & solid), total pressure, Mass (fluid), Density, Mass of water, Mass of steam & Max static pressure).

After the flow simulation solver is completed, we are noticed following results in comparison to actual flow dynamics inside heater.

1) In condensing zone we have observed accumulation of water up to top ID of the shell, which is really not going to be the case as feed water heaters are having external drain control mechanism to maintain water level in condensing zone below H.L. (as shown in Image attached). As the flow simulation solver run is considering accumulation of water in condensing zone flooding the complete tube surface, hence we are observing drain sub cooling in the condensing zone itself which is not the real phenomenon inside the heater. The observed temp. at entry point of drain sub cooling zone is 163.64 deg C which ideally should be equal to the saturation temp. corresponding to the steam pressure (~195 deg C). In this situation our query is that how we can simulate the real case of controlled drain level in condensing zone & get correct temp. (~195 deg C) at the entry point of sub cooling zone.

2) We are observing drain sub cooling of approx. 7.5 deg. C which should be approx. 40 deg. C as per design. Can you please clarify this issue.

3) As already explained we have seen water level build up in condensing zone towards shell dish end side, as De super heating zone at the top side of the heater is communicating with the condensing zone hence water should ideally enter the De super heating zone also. Although result (cut plot image) does not show such. Please clarify.

4) The drain temp. result is showing 164.24 deg. C at shell outlet nozzle, however the design drain temp. is 155.28 deg. C, although the sub cooling zone is designed adequately. What can be the explanation for around 9 deg. C difference in the drain temp.

 

We will be happy to get clarifications on above points at the soonest.

 

Regards,

 

Pandurang Nagare

+91-22-66900100 Extn. 232

Tema India Limited

Mumbai, India.

 

 

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