Posted by Mitch on April 23, 2001 at 15:18:24:
In Reply to: Design Problem posted by Jaaron Johnson on April 22, 2001 at 15:05:09:
: I am a senior in Mechanical Engineering at the South Dakota School of Mines and Technology.
: I'm working on a Regenerative Rankine Cycle design problem.
: I have a 50 MW steam power generation facility which operates with a boiler exit temperature and
: pressure of 1000 deg. F and 2500 psia. I need to determine the optimum number of feedwater
: heaters as well as desired extraction pressures to operate these feedwater heaters. Any other
: unknowns are to be designed with economic considerations.
: I looking for help with my unknowns. I'll use any information available. I need the individual
: costs of this facility and insight on the most efficient system.
The boiler feedwater temperature will be important as it determines the maximum amount of heat you can transfer into the water. How you plan on integrating the economizer is also important: using an economizer before a feedwater heater maximizes the LMTD across the unit reducing surface area and maximizing recovery. The trade off is if the water rises above the saturated temperature of the extraction steam for the feedwater heater then you cannot condense the extraction steam and lose the latent heat reducing the value of the feedwater heater. Placing the feedwater heaters first runs the risk of elevating the feedwater temperature towards the flue gas entering temperature reducing the overall efficiency of the boiler.
It can be a real guessing game between boiler and plant efficiency and utilization. Good luck with your classes.
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