5 replies to this topic

[Solibus]

I'm a engineering student and I'm trying to understand how does a steam turbine work in a solar thermal power plant. Usually, in a vapor power cycle electric power generation is constant, because the turbine inlet parameters are always the same. But, in a solar power plant, water is boiled thanks to the sun energy (DNI) which varies during the day. So, the inlet temperature of the turbine will not stay constant. Thus, the electric power generation will also vary.

 

But I have no idea how to know the efficiency and the outlet parameters of the turbine depending on the inlet parameters. Do you know some websites which could explain it?

 

Thank you for your help.

[Shivshankar]

Solibus,

 

 

http://www.volker-qu...tals2/index.php

 

http://www.classroom...rmal_plant.html

 

 

Hope this helps.

 

Regards

Shivshankar

Attached Files

•  Cogeneration2.pdf   372.81KB   17 downloads
•  Cogeneration.pdf   81.96KB   17 downloads

Edited by Shivshankar, 24 April 2013 - 02:23 AM.

[Solibus]

Thank you for your help Shivshankar. But it doesn't help me so much. I will try to be as clear as possible.

 

In the example of your attached document: "Cogeneration2", the coal consumption in the boiler is constant: 1550 kg/hr. Thus the turbine inlet values (temperature, pressure), the turbine exhaust values and the power output are all constant. While in a solar thermal power station, the energy from the sun is not constant. So, if I compare with your example, the coal consumption in the boiler will not be always 1550 kg/hr. But this coal consumption may vary between 500 kg/hr to 2000 kg/hr.

 

Here it is my problem, because I don't understand how will work the turbine. Right now, I think the turbine inlet and exhaust values may be always constant, but the steam flow rate may be different. So maybe, the turbine is designed to produce a power output varying between 20kW to 120kW with a steam flow rate varying between 2000 kg/hr to 6000 kg/hr. But I have no idea, if it's right or no, and I'm looking for some resources which could explain it.

[thorium90]

What you are looking for are 24/7 solar power plants. Not all of them work throughout the day.

Some work by changing to gas firing at night. (If they have gas turbines on site)

Some work by storing energy in molten salts http://cleantechnica...tructed-in-u-s/

Many simply shutdown at night because as you might already know, electricity consumption is lower at night. Therefore, these plants supply peak demand only, not the base demand. As a very simple example, if the power consumption in a place is 10GW during the day and 6GW at night, the solar plant supplies the 4GW during the day while other gas or oil fired plants supplies the remaining 6GW.

 

The available steam pressure changes depending on how much energy is put in since the degree of superheat is the controlled parameter. And as the steam pressure changes, the power to turn the generator changes and therefore the generator produces different amounts of power. Therefore, the inlet temperature to the turbine is an (almost) constant parameter.

 

This website explains the calculations.

Edited by thorium90, 25 April 2013 - 02:48 AM.

[Solibus]

Yes you're right thorium90. So, do you know how does the turbine work for 24/7 solar power plants which work throughout the day?

[thorium90]

erm, i thought the first few lines in my previous post sort of answered that... They either stop at night or use the heat from the salt for steam generation at night.

Anyway,

http://www.the9billi...ional-in-spain/

Edited by thorium90, 25 April 2013 - 03:33 AM.