Archive: Gas

Designing HRSGs for cycling

With U.S. combined-cycle plants increasingly being cycled—rather than being run continuously, as they were designed to do—owner/operators worry that units expected to last two or three decades may survive only a few years without an expensive overhaul. Cycling takes as much of a toll on heat-recovery steam generators as it does on gas turbines. Whether you’re procuring a new HRSG or adapting an existing one for cycling service, robust design features should be what you’re looking for.

O&M staff keep their cool at Alaskan plant

Operating a combined-cycle power plant profitably is no walk in the park, even under ideal conditions. But the extreme conditions at the Beluga Power Plant—from isolation to volcanoes—challenge its staff every day in ways that operators in the lower 48 can only imagine.

Gas turbine "refueling" via IGCC

The jury is still out on the economic and technical feasibility of burning gasified coal to generate electricity. Gasification technology has yet to be proven on a utility scale, especially with Powder River Basin coal as the feedstock. And on the generation side, there are more questions than answers about the capital cost and availability of integrated gasification combined-cycle (IGCC) plants. But with natural gas prices high and rising, it’s definitely worth examining whether it would be economically and technically feasible to convert the existing U.S. fleet of gas-fired combined-cycle plants to burn gasified coal.

Fluid dynamics of the HRSG gas side

Designers of heat-recovery steam generators are using computational fluid dynamics software as one tool to reveal the invisible forces affecting the flow over, under, around, and through structures such as inlet ducts, distribution grids, and guide vanes.

Fleetwide standardization of steam cycle chemistry

Nearly five years ago, a major IPP began standardizing steam cycle chemistry feed, control, and monitoring across its combined-cycle fleet. This article discusses the steps taken, the costs incurred, and the technical and financial benefits achieved. Although the project focused on non-cogeneration plants, the findings detailed below are broadly applicable to other kinds of plants. However, the specific implementations (especially of the chemistry standards) described may have to be modified slightly for application to cogen plants.

Designing HRSG desuperheaters for performance and reliability

Increased cycling of combined-cycle plants has made precise control of attemperator spray water within heat-recovery steam generators more important if damage to their hardware and piping is to be avoided. Complicating the issue is the industry’s still-limited experience with cycling and the fact that demands on the attemperator and turbine bypass of cycled plants are more stringent than those on baseloaded units.

Frame 6C debuts in Turkey

GE Energy’s latest "first" is in Turkey, where the Frame 6C gas turbine-generator—a younger cousin of the popular Frame 6B—has made its commercial debut. The turnkey 130-MW combined-cycle plant, called the GE206C, comprises two 40-MW Frame 6Cs, one GE steam turbine-generator, two heat-recovery steam generators, and a distributed control system. The gas-fired plant (Figure 1), […]

Gas storage investment stymied

  The U.S. needs to add 600 to 800 billion cubic feet (Bcf) of natural gas storage capacity ASAP. Independent storage providers (ISPs) are the entities best equipped to build this needed infrastructure, but they continue to be restrained by anachronistic regulatory policies. The Federal Energy Regulatory Commission’s (FERC’s) December 2005 rule-making to modify its […]