Laramie River Station reduces boiler emissions

It's the hot spot at Laramie River Station, the Unit 1 boiler. Most of the time, it's just hot. This spring, it's hot because it's the happenin' place to be.

The boiler is getting a lot of attention during the unit's maintenance outage. It's the first of Laramie River's three units to get a new system, called overfire air, to help reduce emissions.

Myron Singleton, mechanical engineer, said: "The overfire air project is used to reduce the NOx emissions that form at the burners. With overfire air, you divert about 15 to 20 percent of the air away from the burners, and we inject up here higher in the furnace to complete the carbon burnout."

Erin Huntimer: "Beneath my feet is the secondary air duct thats bringing air in from the air heaters. Part of what's new with this project is this 72-inch diameter header duct behind me that's redirecting air from the secondary air duct into the new overfire air ports in the boiler."

Taking air away from the burners starves the fire for oxygen. This forces the nitrogen atoms to bond together into more stable, inert nitrogen molecules, rather than nitrogen oxide.

Planning for the outage started more than a year ago. The unit was shut down in mid April.

Myron Singleton: "Before the outage, we started steel construction. We had quite a few modifications to make to the structural steel. And then we started construction of 72-inch diameter header ducts in February."

The overfire air project is the first step to meet upcoming emissions rules in Wyoming being made through what is called a BART analysis. BART stands for Best Available Retrofit Technology. The next step will be installing new burners to reduce nitrogen oxide emissions even more. Each of Laramie River's three units will get them in future outages.

Dave Cummings, environmental coordinator: "What we expect to see with overfire air and the low NOx burners completely installed is possibly a 20-25 percent reduction in NOx emissions, and we hope were going to be getting a little bit better than that. Its just going to depend on how well our older boilers that really are not designed right for this type of thing, how well our boilers and how well our operators we have some of the best operators around here if they can do their jobs to the utmost, then we hope to get that NOx down without losing a megawatt of energy."

Another hot spot in the Unit 1 outage is the turbine deck. This is the last of the three units to get a new high-pressure/intermediate-pressure rotor and stationary blading. The project improves efficiency, meaning more megawatts without burning more fuel. The Unit 2 upgrade results in 12 more megawatts of power. Unit 3 is producing 20 more megawatts. The Unit 1 project is expected to get similar results.

Unit 1's outage activity is winding down. The real heat returns to the boiler in early June, when operators fire the unit to bring it back online.

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