Fast-start/fast-ramp peaker produces 180 MW in 12 minutes, holds emissions within California’s tight standards

Marsh Landing Generating Station in CaliforniaOver the last couple of years, Siemens Energy Inc and Mitsubishi Power Systems Americas Inc have strengthened their positions among the technology leaders for frame gas turbines. Siemens’ successes include H-class and fast-start/fast-ramp combined cycles, Mitsubishi’s include 501GAC-powered combined cycles and its giant J-class gas turbine.

Power producers evidently have been impressed, judging from the two-to-one advantage the two companies held over perennial market leader GE Energy in sales of frames for US electric generation in 2012 (capacity basis).

More recently, Siemens and Mitsubishi collaborated to assure the success of NRG Energy Inc’s four-unit, nominal 720-MW Marsh Landing Generating Station, a simple-cycle facility in Antioch, Calif, about 40 miles northeast of San Francisco. It began commercial operation May 1, 2013. Siemens supplied four SGT6-5000F (501FD4) gas turbines equipped with ULN (ultra low NOx) combustion systems, four SGen-1000A generators, the SPPA-T3000 control system, and balance-of-plant equipment, as well as technical support for installation and commissioning.

Mitsubishi provided a leading-edge dilution SCR system for each engine to reduce the 9 ppm NOx/4 ppm CO in turbine exhaust to 2.5 ppm/2 ppm out the stack. Ammonia slip is restricted to 10 ppm. Cormetech Inc and Johnson Matthey supplied state-of-the-art SCR and CO catalyst formulations, respectively, to guarantee emissions conformance.

Siemens partnered with NRG to implement an integrated control technology that allows the plant to maintain low emissions while navigating fast, intermittent load ramps. All four units demonstrated ramp rates of up to 32 MW/min, reaching base load in 12 minutes while holding emissions within permit limits. Siemens refers to this as its Clean-Ramp™ technology.

Mitsubishi’s scope included CFD and physical flow modeling to guide the design and supply of all equipment from the gas-turbine expansion joint to the stack, including the following:

• SCR catalyst modules and drop-in CO catalyst panels.

• Inlet and outlet transition ducts and all expansion joints.

• A 2 x 100% tempering-air/purge-air skid complete with accessories and interconnecting ductwork from the fans, including tempering-air distribution devices within the SCR system casing.

• Ammonia forwarding skid, vaporization skid, and injection grid with balancing manifold.

• PLC-based SCR emissions controls and control logic interface to the DCS.

• Exhaust stack with advanced silencing systems.

Marsh Landing, located on a 27-acre brownfield site in a challenging seismic zone, complies with some of the nation’s most strict limits for NOx, CO, VOCs, and particulates. The facility sits adjacent to the Contra Costa Power Plant, a nominal 680-MW station with two 1960s gas/oil-fired steam units; it was retired the day the new facility began commercial operation. Marsh Landing relies on water and wastewater infrastructure owned by the city of Antioch and the Delta Diablo Sanitation District. Its planned water consumption of 50 acre-ft/yr is a 99.99% decrease from what Contra Costa required. The old steam plant had a once-through cooling system.

NRG has a 10-yr power purchase agreement with PG&E for the entire output of the facility. Electricity is delivered to the utility’s existing switchyard adjacent to Marsh Landing via 230-kV lines. Natural gas is supplied via a new pipeline that connects to PG&E’s interstate gas transmission line 400 about ¼ mile from the plant.

Siemens and Mitsubishi engineers will be heavily involved in CTOTF’s™ Fall 2013 Conference and Trade Show in Coeur d’Alene, Idaho, September 8 – 12, where you can get details on these developments and a whole lot more. The lineup of technical sessions for users with Siemens engines is below with links to agendas. You also have the opportunity to meet with Siemens personnel at the Trade Show Monday evening, Booth 4.

Siemens V- and H-Class Roundtable, Wednesday morning, September 11, featuring a user presentation on operating experience with upgraded flow-path components for a V84.2 (SGT6-2000E) and an OEM presentation on operating experience with the SGT6-8000H. Open discussion topics include O&M best practices and lessons learned for both V- and H-class engines.

Siemens Legacy-Class Roundtable, Wednesday afternoon, September 11, will be an intense session covering the impact of air-quality standards on the operation of legacy engines, options for reducing emissions to meet new regulatory requirements, DF42 improvements, bolted-rotor update, rope seal mods, among other topics. The presenters/discussion leaders include several key members of the OEM’s aftermarket management team: Mark Kamphaus, director of service engineering; John Demase, frame owner for mature engines; Bruce Rising, strategic business manager and expert in environmental and regulatory matters affecting gas turbines.

Siemens F- and G-Class Roundtable, all day Thursday, September 12, midway between the 2013 and 2014 meetings of the 501F and 501G Users Groups, is an opportunity to refresh your knowledge on critical issues. Leading engineers on the service teams for these units—including Jonathon Mount, Shantanu Natu, and Brian Micklos—will update the group on the four-way joint issue, efforts to reduce turning-gear speed, conversion of the FD2 to FD3, compressor thru-bolt issue, and other important topics.

The afternoon program features a user presentation on measures to correct the leakage problem associated with the four-way joint, plus a third-party services provider’s recommended design modifications to extend the life of turbine blades. A robust user-only discussion period led by TVA’s Zach Cowart and Colectric Partners’ Scott Trantham will cover the engine from air inlet to exhaust outlet, highlighting best practices and lessons learned.

Here’s the lineup of technical sessions for users with Mitsubishi aeros and frames (Booths 3 and 81):

Special combined session for Mitsubishi and Pratt & Whitney owner/operators, Tuesday afternoon, September 10, will focus on how users benefit from Mitsubishi’s acquisition of Pratt & Whitney. The renamed PW Power Systems Inc will operate as a separate entity reporting to MHI while maintaining a close relationship with Pratt & Whitney. Chuck Levey, VP of PW Power Systems, well known to many CTOTF members, will be on hand to answer questions.

Mitsubishi Roundtable, Wednesday afternoon, September 11, chaired by Mike Dwyer, plant manager of Portland General Electric’s Port Westward Generating Plant (TVA’s Jack Roddam is the vice chair) will dig into the performance and in-service issues for MHI’s J-Class engine and operating experience and performance issues associated with the M501F and M501G machines.

GE, Alstom engines

Ah, but you don’t have Siemens or Mitsubishi gas turbines at your plant. No problem: CTOTF™ is the only user group that serves all frame owner/operators. Here’s the lineup of sessions for users with GE and Alstom engines:

GE F-Class Roundtable, all day Tuesday, September 10, chaired by Pierre Boehler of NRG Energy Inc (Star West Generating’s Mike Hartsig is the vice chair) features a morning of OEM presentations and a busy afternoon. Latter includes presentations on extending HGP component life beyond OEM intervals, turbine component repair-shop experiences, inspection results from a major inspection at 64,000 hours, OpFlex and auto re-ignition, and exhaust frame and diffuser upgrades and refurbishments.

GE E-Class and Legacy Roundtable, Wednesday morning, September 11, directed by Pierre Boehler and Ed Wong of NRG Energy Inc, will focus on transition pieces, combustion liners, fuel-nozzle repairs, electric actuators for fuel valves, hot-section repairs, and monitoring of station batteries.

GE Aero Roundtable, Wednesday afternoon, September 11, with Jason Offutt of Tri-State G&T Assn at the front of the room, will devote half the session to air filters with presentations on field testing of inlet filtration and on how to choose the optimal media within OEM guidelines. A vendor panel will address such topics as: to HEPA or not to HEPA, to puff or not to puff.

Alstom Roundtable, Tuesday afternoon, September 10, with Earl Ferguson of East Kentucky Power Co-op and Bruce Barnhouse of Lincoln Electric System, the chair and vice chair, respectively, features presentations on controls upgrades and on the challenges and issues associated with Alstom generators.


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  1. […] employ “H Class frame peaker technology” for  a new plant according to Chris Curry, NRG Vice President, Business Development. […]