SG Gasifier set for annual outage

September 16, 2011

As the summer cooling season draws to a close, the team at the sgSolutions gasification plant is getting ready for the annual fall maintenance outage. This year’s plans call for the shutdown to begin on October 7, with a tentative plan to resume around Thanksgiving weekend.

“The length of this year’s outage is being determined by the work that’s being performed at the combined cycle plant on the other side of the fence,” explained Plant Manager Richard Payonk. “They are doing more critical path work, including control system upgrades and work on their heat recovery steam generator. Those are very big projects that determine the time frame for the outage.”

While those major efforts take place at the combined-cycle plant, the sgSolutions crew will focus primarily on regular and preventive maintenance, Richard said. “We’re using the extra time to perform some major maintenance projects during this outage. They’re the kind of things you might do every ten years or so. One is refurbishing the tail gas incinerator unit on the back end of the sulfur plant. This boiler unit has finned tubes that have become plugged with sulfur over the years, so we’ll clean them. That will extend the life of the unit, improve efficiency, and help with our medium-pressure steam production. We’ll also replace refractories in that unit and in the gasifier.”

The other major job is a continuation of pipe upgrades in the slag water system. “Slag is the mineral by- product that won’t combust in the gasifier,” Richard noted. “The petroleum coke we use makes the water in that system somewhat more acidic than the original coal the plant was designed for. So we’ve gradually been replacing the carbon steel piping that was originally installed with stainless steel pipes that will resist corrosion and give us more flexibility with our fuels.” He added that they have already replaced nearly a quarter-mile of piping. “That may not sound like a lot, but you have to consider that it never goes much farther than 10 or 20 feet before a bend in the pipe.”

The projects are focused on improving the plant’s reliability and run time, which has already been at record levels during 2011. “Even with this extended outage, we’re still on track for achieving production that’s eight to ten percent above our previous best year. That’s a sign that the work we’ve been doing over the past few years is paying off.”

“During this outage, we’ll perform somewhere between 400 and 450 individual jobs, about 150 of which are preventive maintenance,” Richard noted. “They’re the things we do during every outage, including basic cleanup and testing. Some are simple inspections in which you open things up just to make sure they look fine. But they’re all based on operating issues we’ve observed during the last 15 years. It involves a lot of man-hours, but it should keep the plant running well through the winter.”