How a Southern California Refinery Mastered Power Generation and Cooling with MeeFog Technology

“We were doing well for many years,” says the project manager. “But the refinery kept expanding, kept adding production units, and our MW kept getting tighter and eventually ran short.”

So in the mid-90s, the refinery upgraded to a CW 251B-12 turbine, which gave them 50 MW nominal output. A Heat Recovery Steam Generator (HRSG) supplies the refinery with more than 200,000 lbs. of steam per hour.

“This kept the power generation and refinery demand in approximate balance,” he continues. “But during the hot days, as is typical with any gas turbine, the heat makes the air less dense and the output drops by as much as 5MW.”

Learning from Neighbors

This refinery is far from being the only distributed generation facility in that neighborhood. For instance, there is the Harbor Cogen facility on Pier B Street in Wilmington with a GE Frame 7 that went into operation in 1988, the same year as the refinery’s initial 251B-10. There is also a refinery in Carson, and the Watson Cogeneration Plant next to the refinery, both of which utilize MeeFog inlet cooling to enhance their power generation. The project manager closely monitored the progress of these facilities.

Recovering Lost Power

While the mid-90s upgrade was adequate for a number of years, eventually it did need to boost its generation on hot days. At that point, however, the company didn’t need to launch into a research project to determine what was best.

“I am aware of all the cooling technologies and have evaluated all those for more than ten years,” says the project manager. “I knew on the spot that fogging was the least cost, and most effective way to go.”

He explains that the company chose MeeFog to provide the system because it has the most applications worldwide and the most proven technology.

“You have to make absolutely sure your air flow path from the fog system going down to the GT inlet must be super clean and free of rust or any particles that can get washed off from the walls or silencers,” he adds.

Installation Specifications:

The Meefog system was installed in October 2011. An array with 429 fogging nozzles was installed just downstream of the air filter. The system has 11 operating stages, which can provide up to 30 degrees of cooling, allowing the inlet temperature to be controlled within a few degrees. The automatic control system is set to operate whenever the temperature exceeds 50 degrees. Maintenance on the system is minimal and involves only changing the pump oil on schedule and checking during the annual turnaround to see if any of the nozzles are plugged.

“During the performance tests, we dropped from 100 degrees to 70 degrees F at the inlet,” the project manager says. “We gained 5 MW which brought us back up to the nominal rating.”

Results:

The 14 stages of wet compression are tied into the gas turbine controls so the grid authority has control over the amount of power augmentation via the automatic generation signal. This allows for seamless control of the amount of power augmentation above base load as required by the grid authority. Prior to the installation, the MHPS 501F turbines with evaporative coolers produced 164.2 MW each. This was increased to 180 MW with Wet Compression. The systems gave the plant a total of 64 MW of additional power to sell into the Mexican grid.