Eni S.p.A. refinery
The Benefits of MeeFog Technology
- Almost 10°C of cooling in summer
- Up to 100 kW of additional power per degree Celsius of cooling
Summer temperatures in Italy can soar. As hot air has a lower mass than colder air, this reduces the mass flow through the turbine and thus inhibits performance by as much as 10%.
By bringing inlet temperatures down by up to 10°C, a MeeFog system provided almost 1 MW of additional power to the turbine, while improving heat rate and lowering emissions.
The Physical Site
Eni S.p.A. is an Italian multinational oil and gas company headquartered in Rome. It has operations in 79 countries, and is currently Italy’s largest industrial company. Through its Refining & Marketing Division, ENI operates five refineries in Italy – Sannazzaro, Livorno, Venice, Taranto and Gela.
Overall, ENI has a refining capacity of approximately 39.3 mmtonnes (equal to 787 kbbl/d). Each of ENI’s refineries in Italy has operating and strategic features that aim at maximizing the value associated with the asset structure and the geographic location.
The Venice Refinery is the company’s model Green Refinery which has been fully converted into a biorefinery where it has implemented recycling and sustainability processes. This facility is located on the Adriatic coast just a few miles from the historic center of Venice.
Environmental stewardship in Italy is regarded as a vital part of corporate responsibility. This can be seen in ENI’s commitment to the Green Refinery as well as in its efforts to reduce fuel consumption and emissions.
Accordingly, it adopted a 25MW GE MS5001 gas turbine to be able to generate onsite power, thereby reducing dependency on the Italian grid. By selecting a gas-fired turbine, it avoided the high emissions levels associated with coal-fired generation.
In addition, ENI adopted a MeeFog system as well as a steam injection system for the gas turbine. Together, they help to lower fuel consumption and curtail emissions.
The climate in Venice is regarded as subtropical. July and August temperatures can sometimes reach close to 40°C and are frequently above 30°C for at least part of the day. During these extremes gas turbine output can drop significantly.
ENI, therefore, decided to use MeeFog for power augmentation at its Venice refinery. The fogging system operates at 2000 psi and produces tiny fog droplets with an average size of 10 microns. Each of the 210 fog nozzles provide a flow rate of 0.045 gpm. A stainless steel piping infrastructure feeds demineralized water to the fog system at a total flow rate of 9 gpm.
“We use demineralized water which is produced by our own demineralization equipment and shared between our fog system and other areas of the refinery such as our boilers,” said Massimiliano Bettin, Downstream and Industrial Operations Manager at ENI’s Venice Refinery.
Seven stages of cooling provide the potential for up to 12°C of cooling. This equates to 1.7°C of cooling per stage. This amount of cooling is only needed for short periods of the day.
“We keep the fog system in operation from May to October and shut it down the rest of the year,” said Bettin. “We are reaching up to 9°C of cooling during dry summer days on average by using our MeeFog system.”
But the climate in Venice can get hot and sticky during some parts of the summer. So how does the MeeFog system cope with periods of high humidity?
“When Venice becomes very humid, we still achieve up to 5°C of cooling on average,” said Bettin. “The turbine presents benefits from MeeFog cooling of up to 100 KW per degree Celsius.”
With the success of the Venice installation, ENI has since added a MeeFog system to its Sannazzaro de’ Burgondi Refinery in Northern Italy near Milan.