No....89,780 is correct...
I worked this problem a little different than the book although their answer is correct and even quicker.
First you must realized there's 3 different things that happen...step 1, 2, and 3.
First, the steam is at 5000PSIA and 1200 F which gives you h=1530.8 and s=1.50. Then the steam is throttled. h is constant through a throttling process so h1=h2.
The second stage is at h2 = h1= 1530.8 and 1000 psia, so go to the tables and get s at these conditions...that gives you an s =1.6698. Then it goes through the turbine which is a constant entropy process so s2 = s3.
The third stage is at s3 = s2= 1.6698 and 50 psia which at these conditions go to the tables and get an h =1182.6
Then use eq 28.18 out of the MERM to get the actual h (since efficiency is given).
Then the output power is 1,000,000*(h1 - h(actual)) then convert to KW gives 89,780.
To get the real accurate "h" and "s"'s in this problem you need a steam table book like the one I linked above.
I would prefer not to give my number but can give my e-mail to you...although I would prefer to answer your questions here on the forum in case someone else has the same question.
