Gas turbine Sizing

[myango]

Hi all,
Which type of Gas turbine is the best for a plant that needs both steam (23tonnes/hr ,18 bar,350 degrees centigrade ) and power (10MW)
a)Dual pressure Combined cycle with condensing extraction steam turbine
b)Single pressure Combined cycle with condensing extraction steam turbine
c)Gas turbine and HRSG without steam turbine.
Regards

 

[MJCronin]

mango,

Your choice of equipment is very dependent on several other factors such as :

1) What is your yearly load profile for both steam and power ?

2) What will be the skill level of the staff ?

3) What will be the cost of fuel ?

4) Your need for steam if the GT is out of service.

and most importantly....

5) How much can you afford to spend and when do you want it ????/?

There is not a single simple answer to this question. There are several "candidate" plant configurations to consider. Developing a short list of those plants is your first step

-MJC

 

[MisterDonut]

myango,

HRSGs on gas turbines at 10MW and below are almost never dual pressure with reheat, and rarely operate in combined cycle. It is typical for them to make steam for plant use only.
The reason for this is economics. In a plant of this size, it usually not cost-effective to produce electricity from natural gas in combined cycle vs. combined heat and power due to the relatively large capital cost of the steam cycle components. In other words, the money saved by the additional electric power generated by the steam cycle vs. buying off the grid may not be enought to pay off the additional capital cost of the steam turbine and associated componenets in a reasonable period.
Your situation will depend on all of the things mentioned above by MJCronin. If the electrical rates are high compared to gas, it could make sense to do a combined cycle.
Assuming your electrical base load is 10MW, you should be able to generate the 10MW in a GT and get the 23 tonnes/hr of steam for the plant without additional fuel.