Surface Condenser Performance

[Rpsfinest]

We have a Holtec condenser, it is a single shell double tube pass dearating condenser. Here are some of its specs

Number of Tubes 14,520
Tube Length 36’
Tube OD 1.125”
Cooling Water Flow Rate 133,730 gpm
Duty Rating 1067 MMBTU/hr

My question is I am trying to create some trends to track overall performance ie, sub cooling, cleanliness and fouling factors, etc. Can someone with some experience point me in the right direction? I have no heat transfer experience, where should I start? Can someone explain some of the equations I should use to track the performance?

 

[dcasto]

Q = UA Tlm
Q= btu/hr, found either by temperature rise and flowrate on the cooling water side or condensate rate times the heat of condensation on the steam side. if these two values don't match it could be a sign of sub-cooling, more likely bad measurement since it is very difficult to sub cool.
U = heat transfer coeffiecient, the variable you want to trend

A = area, fixed, doesn't changed

Tlm = Delta Temper, log mean average. This doesn't change much but its basically the ((steam temp - water out temp)- (steam cond temp - water in temp))/natural log ((steam temp - water out temp)/ (steam cond temp - water in temp)) There are correction factors to this, I just lump that in as part of the U, mathmatically its correct for watching the change in heat transfer, not correct if you absolutely need to know the U, but you want to trend U, so relative values are fine to watch.

I may have the Tlm backwards on the denominator. anyone else can help me here too.

 

[davefitz]

The official equations to be used by the mfr when issuing performance curves are found in the HEI design standard Steam Surface Condensers, including correction factors for alloy used ( fouling + conductivity) , condensing heat transfer coefficient, and convective coefficient in any subcooler ( if applicable).

The current in situ heat transfer coeeficient could be obtained from a performance test at a specific load, to better predict the effect of current fouling.

Some common inaccuracies to deal with - the actual flowrate of circ water is often not monitored, the steam leakage from packing to condenser might not be within expectations, there can be incondensible air/co2/etc blocking the condensation process, fouling of tubes , etc

 

[rmw]

Go to

http://www.heatexchange.org/pub/default.htm

and look for the steam surface condenser program at the bottom left. It is not expensive. Order it and learn to use it. It will answer all your questions. Short of that if you aren't real familiar with heat transfer, find someone who is. Steam Surface condensers are not your plain vanilla heat exchangers.

rmw