3 replies to this topic

[saintful]

Hello everyone, is there any website i can go to that can guide me if i wish to calculate the power produced by a steam turbine if i have parameters like inlet steam temperature, inlet steam pressure and the rotating speed of the turbine? Thank you

[mbeychok]

Saintful:

The theoretical power extracted from each pound of steam is equal to the change in enthalpy (at constant entropy) of the steam between its inlet conditions and its exhaust conditions.

For example, 600 psig inlet steam at 750 °F has an enthalpy of 1380 Btu/lb and an entropy of 1.606 Btu/°F/lb. 50 psig exhaust steam at that same entropy has an enthalpy of 1155 Btu/lb. Thus, the delta H (at constant entropy) for the expansion of the steam from its inlet conditions to its exhaust conditions is 1380 - 1155 = 225 Btu per pound.

Since, there are 2547 Btu per hp-hr, the theoretical hp-hr extracted from each pound of steam:

Theoretical hp-hr/lb of steam = (steam delta H at constant entropy, Btu/lb) / (2547 Btu/hp-hr)

Theoretical hp-hr/lb of steam = 225/2547 = 0.0883

And the actual hp-hr/lb of steam is the theoretical times the efficiency of the turbine. If we assume a 70% efficiency:

Actual hp-hr/lb of steam = (0.0883) (0.70) = 0.0618

Now, if you know the steam usage of the turbine (let's assume 5,000 lbs/hr), the power produced by the turbine is:

Hp produced = (0.0618 hp-hr/lb) ( 5,000 lb/hr) = 309 hp

So, what you need in order to calculate the power produced by a steam turbine is:

(1) The inlet steam temperature and pressure
(2) The exhaust steam pressure
(3) The efficiency of the turbine
(4) The turbine steam usage in pounds per hour
(5) A good Mollier Diagram for steam

[Sadananda Konchady]

You may like try the weblink for freeware at:

http://www.sugartech...bine/index.php3

However, besides the inlet and outlet steam conditions, you will need to input an overall efficiency, (which may be between 50% to 65% in my opinion) depending upon the size of the steam turbine and turbine speed. To get a realistic value for your case, you may need to check turbine suppliers about the appropriate value for overall efficiency.

The program is designed for back pressure steam turbines only and considers the enthalpies of the steam at the inlet and outlet according to the specifications given by the user.

Incidentally, this website is an excellent one for those interested to know the latest technical developments and news in the sugar industry.

[mbeychok]

I agree with the person named "escape" that the site to which he referred you can be useful ... but not necessarily to a student.

I realize that I may be old-fashioned, but it is my belief that usually no one learns anything by using a "calculator progam" found on the Internet ... because rarely do such web sites explain in any detail the underlying algorithms or methodology used in their "calculator program". If only the authors of such programs would realize how much more helpful it would be to explain the underlying methodology.