Troubleshooting Steam Plant Output: Tips for Evening Class Assignment

[anthonyk2013]

Im attempting this question for an evening class I am attending. hope I am posting in the right place. I'm not sure where I have gone wrong think its where I rearranged my formula to find steam output.

Question attached below

 

[siddharth23]

The work is a bit unclear. I'll get back to you in a day or so.

 

[anthonyk2013]

Ok Thanks

 

[anthonyk2013]

I think I calculated the steam output wrong, I have the over all efficiently of the system 77%, what formula do I use the calculate steam output?
Q=M(h2-h1)

 

[siddharth23]

Yeah that's the one..!
For calculating the steam output, you can directly use the 77% efficiency without involving the economizer and super heater (if I'm not wrong).
So 77% of the heat obtained from the combustion of coal is used to convert water to steam.

 

[anthonyk2013]

Yeah that's the one..!
For calculating the steam output, you can directly use the 77% efficiency without involving the economizer and super heater (if I'm not wrong).
So 77% of the heat obtained from the combustion of coal is used to convert water to steam.

77% is the overall efficiency am I right ? So did I divide .77 by h2-h1 to get steam output?

 

[siddharth23]

77% is the overall efficiency am I right ? So did I divide .77 by h2-h1 to get steam output?

Yes! And equate it with the energy provided by the combustion of coal. Tell me if that gives the right answer.

 

[anthonyk2013]

6244.09 kg/h

 

[siddharth23]

I meant did you get the right answer?