Hello all,
I know the topic I will ask about has been already discussed in a few other threads but, after reading them and getting as much information as I could on the internet, I was unable to find the answer to my question.
We operate 2x 27MW gas turbines in our process, not to generate electricity but to boost our process gas. Since we are operating in dessert conditions, the GT capacity is very affected by the warm weahter we get over here. Temperatures above 40C (104F) (sometimes well above this value) are common for around 4 months/year. Since when this occurs, relativy humidity is very low (around 15%), it has been thought that the use of a inlet air cooling system based on evaporative cooling (either with a wetted media or fogging) would be a possibility to increase power outlet during theses warm months.
After reading a lot of information on the internet, I see this technology is well proven and, doing the calculations, could work fine with our conditions: from a 40ºC-104F dry bulb temperature we have around 20ºC-68F WB temperature. It means up to around 20ºC-36F gain. This is pretty interesting. I can also easily calculate the air consumption.
Now my question, and please forgive me if it is stupid, but I haven´t been able to find the answer and my heat and transfer knowledge in the psycometrics doesn´t allow me to answer. In order to saturate the inlet air with water, and get the temperature decrase above, what would be the temperature of the water that we will be, either spraying either circulating in the wetting media? Since this is a complex heat and mass transfer problem, involving latent heat as well as sensible heat, I wonder if it has to be lower than 20ºC (lowest air temperature) in order to the water droplets to vaporise and saturate the air or it can be higher than that.
The above is important since, in the climate, air is not the only thing that gets warm. Available potable water (that will have to be demineralised) is also hot, around 30ºC-86F. So if water has to be cooled down prior to be sprayed, an additional small refrigerating system will be required. This will add to a small demin system to get proper water and the skid itself (fogging) or the wetting media system.
I hope my explanation is clear and you can give me an answer or some reference to better understand the heat and mass transfer involed in the system.
Best regards
David
I know the topic I will ask about has been already discussed in a few other threads but, after reading them and getting as much information as I could on the internet, I was unable to find the answer to my question.
We operate 2x 27MW gas turbines in our process, not to generate electricity but to boost our process gas. Since we are operating in dessert conditions, the GT capacity is very affected by the warm weahter we get over here. Temperatures above 40C (104F) (sometimes well above this value) are common for around 4 months/year. Since when this occurs, relativy humidity is very low (around 15%), it has been thought that the use of a inlet air cooling system based on evaporative cooling (either with a wetted media or fogging) would be a possibility to increase power outlet during theses warm months.
After reading a lot of information on the internet, I see this technology is well proven and, doing the calculations, could work fine with our conditions: from a 40ºC-104F dry bulb temperature we have around 20ºC-68F WB temperature. It means up to around 20ºC-36F gain. This is pretty interesting. I can also easily calculate the air consumption.
Now my question, and please forgive me if it is stupid, but I haven´t been able to find the answer and my heat and transfer knowledge in the psycometrics doesn´t allow me to answer. In order to saturate the inlet air with water, and get the temperature decrase above, what would be the temperature of the water that we will be, either spraying either circulating in the wetting media? Since this is a complex heat and mass transfer problem, involving latent heat as well as sensible heat, I wonder if it has to be lower than 20ºC (lowest air temperature) in order to the water droplets to vaporise and saturate the air or it can be higher than that.
The above is important since, in the climate, air is not the only thing that gets warm. Available potable water (that will have to be demineralised) is also hot, around 30ºC-86F. So if water has to be cooled down prior to be sprayed, an additional small refrigerating system will be required. This will add to a small demin system to get proper water and the skid itself (fogging) or the wetting media system.
I hope my explanation is clear and you can give me an answer or some reference to better understand the heat and mass transfer involed in the system.
Best regards
David
