Port Westward - First Mitsubishi G1 plant online and meeting customer demand in Oregon

By Jaisen Mody

Manager Engineering, Construction & Startup

Portland General Electric

Title: Port Westward First Mitsubishi G1 plant online and meeting customer demand Abstract: Port Westward Generating Plant started commercial operations in June, 2007 and is supporting PGE’s summer loads in a reliable and cost effective manner. The G class combined-cycle combustion turbine is the first U.S. plant to use Mitsubishi Heavy Industries’ G1 advanced technology. Port Westward Generating Plant is one of the most efficient combined cycle plants of its type in the United States This article will discuss the plant engineering, construction, and startup and what it means to be highly efficient in today’s market. By: Jaisen Mody, Manager

Engineering, Construction & Startup Portland General Electric

Introduction PGE’s 400 MW Port Westward plant started commercial operations in June, 2007. It is the United States first combustion turbine that uses Mitsubishi Heavy Industries (MHI) G1 advanced technology. The new plant is located in Clatskanie, Oregon at the Port Of St Helens Industrial Area near PGE’s existing 545 MW Beaver Generating Plant. During peak construction, the Plant employed approximately 400 union construction workers, nearly all of them local. Mitsubishi Power Systems provided the power island equipment which included one M501G1 gas turbine, one steam turbine, and a Deltak triple-pressure HRSG, with SCR, CO Catalyst and duct burners. The steam turbine is a tandem-compound type–down exhaust with a crossover connection from the high pressure-intermediate pressure stage to the low pressure stage. The plant is designed to operate from a central control room, resulting in an expected operating staff of 18 new PGE employees. Construction started in January 2005 and commercial operations began in June 2007. Port Westward is the newest member of PGE’s diverse family of power generation resources and the company’s first plant to be brought online in more than 10 years. With a generating capacity of 400 megawatts, Port Westward produces enough electricity to power the homes of more than 300,000 PGE customers.

PGE’s load continues to grow at around 2.2% annually. Port Westward is reducing PGE’s dependence on wholesale market purchases and is playing a vital role in Oregon’s energy future. Powered by a new breed of Mitsubishi G1-class combustion turbine, the combined-cycle, natural gas-fired plant is one of the most efficient generators of its type in the United States today. Net plant heat rate including transformer losses is around 6,700 BTU/Kw Hr. The plant was built under budget and just in time to meet PGE’s summer load demand. Port Westward also has low levels of emissions for nitrous oxide, carbon monoxide and volatile oxides of carbon. Levels measured at the plant since it began operation are below the strict levels permitted by the Oregon Department of Environmental Quality. PGE contributed about $5.4 million to the Oregon Climate Trust to fund projects that offset the plant’s carbon dioxide emissions PGE’s original permit application for Port Westward specified a two turbine plant with up to 650 MW of plant capacity using F class turbine technology. However, after careful analysis of projected consumer demand, review of newly available turbine technologies, forecasts of customer elections under the state’s electricity restructuring law, the outcome of a competitive bidding process for wholesale power contracts and an analysis of the natural gas marketplace, PGE modified its original recommendations. The utility decided that, because it is more efficient than the F class turbine, the new G class unit would be a better overall long-term investment for customers. As a result, Port Westward’s target of 650 MW from two natural gas-fired F class turbines was reduced to one unit using the more efficient G class turbine technology. Under average site ambient conditions the new plant has an overall capacity of 414 MW, 389 MW of this being combined-cycle and the remainder duct firing.

Selection Criteria PGE spent considerable time researching the various gas turbine technologies available for gas-fired plants. The existing F class technology was considered together with the GT-24 machines. The utility’s analysis showed that the G class option was a lower-cost option for its customers. Port Westward’s G class machine has scale advantages because it is approximately 100 MW larger than the F class option originally considered. It also has a 3 percent to 4 percent heat rate advantage over the F class alternative. G class machines have been in commercial operation since 1997 and have logged many hours of operation. The only two G class turbine manufacturers, Mitsubishi Heavy Industries and Siemens Power Corp., were considered based on several criteria, including technology attributes, cost, number of operating plants, units deployed, units on order, reliability and technical support and service. After completing a detailed options analysis, PGE engineers and consultants chose the Mitsubishi machine. Two main factors influenced this decision. One was the operating history of Mitsubishi’s fleet of 18 G gas turbines. This fleet of gas turbines now has more than 320,000 hours of cumulative operating history. A second was Mitsubishi’s verification approach in which new technology and design changes are first tested at the company’s verification power plant in Takasago, Japan, prior to commercial release. Port Westward’s G1 unit underwent a thorough verification and testing process, which should result in fewer problems during operation, because both the verification facility and the approach provide meaningful quantitative comparisons with design assumptions. Contracts Normally, a turnkey engineering-procurement-construction (EPC) contract is negotiated with the EPC contractor who in turn procures the turbine and power island equipment. This was not an ideal approach for PGE because the utility felt it would impair its ability to have maximum interface with the original equipment manufacturer (OEM). PGE wanted close contact with the OEM to accomplish several objectives, including:

• Speedy procurement. • Ability for hands-on discussion with the OEM. • Ability to negotiate a long-term service agreement (LTSA) with the OEM.

Thus, PGE decided to negotiate its own turbine deal with the OEM. At the same time, however, PGE did not want to lose the benefits that come with a full-wrap turnkey EPC contract simply because it negotiated its own turbine/power island deal with the OEM. Therefore, PGE assigned the turbine/power island contract to the EPC, Black & Veatch Construction Inc., and hence had only one entity to manage for the entire power project. PGE also negotiated the turbine contract and the LTSA in tandem. It leveraged the turbine award to drive a hard bargain on the LTSA, assuring no major gaps between contracts. The LTSA, which was negotiated and signed with Mitsubishi Power Systems, covers the gas turbine parts and planned maintenance inspections for 12 years. This agreement ensures on-going reliability and OEM cost predictability for this plant. Troutman Sanders LLP assisted PGE with contract negotiations and preparation.

Gas Turbine Advances Since the first G class turbine technology by Mitsubishi was introduced in 1997, there have been significant advances in blade cooling schemes, heat transfer, aerodynamics and sealing technologies. Mitsubishi introduced the G1 machine during its contract negotiations with PGE making Port Westward the first U.S. plant with this advanced machine. Table 1 illustrates how the G and G1 machines are the same and how they are different. Photo 2 compares the row 1 turbine hardware in the G1 gas turbine resulting from design technology advances. Additionally, the G1 extends steam cooling from the combustor transitions to the blade ring on the first row of the turbine (Photo 3). The upgraded hardware was installed in Mitsubishi’s verification power plant in May 2003. To date, the upgraded hardware has accumulated more than 8,083 actual hours of operating experience and 501 start-stop cycles in daily start stop (DSS) load dispatch operation. From the time the engine began operation in 1997 until December 2005, its cumulative operating time was 22,499 hours. G1 versus G Machine M501G1 M501G Compressor Same Same Pressure Ratio Same Same Air Flow Same Same Rotor Same Same Emissions Same Same Combustors Same Same Firing Temperature Same Same Turbine Stages Same Same Row 1 Vane, Blade Row 2 Vane Improved Baseline Exhaust Strut Shape Airfoil Straight Clearance Control Steam Cooled Air Cooled Note: Commonality of compressor, rotor, combustor and materials is maintained. Source: Mitsubishi Power Systems Port Westward Design In addition to the gas turbine manufactured by Mitsubishi, the Port Westward Power Plant has a three-drum Deltak heat recovery steam generator, one Mitsubishi steam turbine and two Mitsubishi electric generators for the gas turbine and steam turbine. The steam turbine is a tandem-compound type-down exhaust with a crossover connection from the high pressure-intermediate pressure stage to the low pressure stage. PGE chose the down exhaust turbine on this 1x1 plant to boost efficiency. The condenser is manufactured by TEI and uses 24-gauge stainless steel tubes. Marley supplied a seven cell fiberglass cooling tower that uses river water for makeup. Port Westward uses the Emerson Ovation DCS system with profibus and field bus communications with local devices to decrease the amount of field wiring and increase the amount of information available to the DCS. The plant uses backup power and demineralized water from its sister plant, Beaver, one mile from the Port Westward site. Port Westward has a static frequency converter for starting and evaporative cooling and duct firing for power boost. An auxiliary boiler provides warm-up and startup steam required for the steam-cooled

components. The steam cooling is one of the reasons Port Westward is so efficient. Steam cooling typically includes additional equipment and protection, which exists on all Mitsubishi G class units in commercial operations. The environmental equipment includes selective catalytic reduction and a carbon monoxide catalyst that reduces nitrogen oxides to 2.5 ppm and carbon monoxide to 4.9 ppm. An ammonia injection system uses the boiler heat for vaporization. Cormetech provided the ammonia catalyst and Englehard supplied the carbon monoxide catalyst. Port Westward includes built-in redundancy for critical equipment. Extensive reviews by PGE’s operating staff ensure adequate access and platforms will be available to assist with equipment maintenance. Black & Veatch and Deltak provided a 3-D model that was reviewed in detail by PGE’s operations staff. Overall plant heat rate is 3 %- 4% better than comparable “F” technology plants. PGE , Black & Veatch and Mitsubishi worked hard in optimizing the cycle and overall plant efficiency. A down exhaust steam turbine, a seven cell cooling tower and low back pressure on the surface condenser all contributed to improving overall efficiency. A 25 MW duct burner system was selected based on operating requirements. The effect of the duct burners on the balance of plant is minimal when they are not dispatched. The site, adjacent to the Columbia River in Columbia County, Ore, takes advantage of existing electrical transmission and gas transportation infrastructure. The location west of the Cascade Mountains is attractive because the generation source is close to PGE’s load; an eastern location could present transmission constraints. Transmission line losses will also be lower, resulting in cost savings. Construction of a transmission line from the Port Westward site to PGE’s decommissioned Trojan Nuclear Plant site allows power delivery directly into PGE’s grid. PGE constructed a single circuit 230-kV transmission line from Port Westward to Bonneville Power Authority’s Allston Substation and a double circuit 230-kV transmission line from Allston to Trojan. Only one circuit is installed at this time. The plant will burn natural gas received from Sumas, a hub in Washington State through which Canadian natural gas is delivered via the Williams Northwest Pipeline. The site has good access to the Kelso-Beaver (K-B) Pipeline. A backup gas supply from the Mist gas storage fields adds to fuel diversity. Compression is provided by 2-reciprocating compressors. The existing Beaver intake structure is used for cooling water from the river. PGE holds a long-term lease from the Port of St. Helens for the Port Westward site. Port Westward Construction Construction started in February 2005 with ground clearing and the installation of stone columns.. The plant is located on native sand and soft silt, so extensive ground reinforcement was required. Stone columns were installed in four main areas: the power block, cooling tower area, the gas compressor building and the switchyard. A total of 4,131 stone columns were installed at an average depth of 40 feet. The columns will mitigate the potential for earthquake induced liquefaction of the loose, saturated sand deposits underlying the dredged sand at the site.

Areas where piles were driven were left untreated. A total of 514 piles were driven to support the foundations for the critical equipment (Photo 4). Foundation pours started in August 2005. Rotating crews worked for nearly 11 hours in 90 F heat in early August, pouring 840-cubic yards of concrete into rebar-reinforced forms to create a five-foot thick base pad. The operation was completed as one continuous pour, with trucks arriving every six minutes and carrying fresh batches of concrete prepared at a mixing facility a mile away. Equipment delivery began in September 2005. Port Westward is fortunate to have road, rail and river access. Most of the heavy equipment was delivered by barge. Ships from China, Korea and Japan delivered equipment to Longview, Ore., where it was transferred to a river barge. Multiaxled, self-propelled transporters (Photo 5) moved the equipment from the barge to the laydown area . Gantry cranes assembled at the site lifted the heavy equipment. The condenser with the water boxes installed was moved as one module using a roller/rail system Despite some obstacles created by Mother Nature, all the equipment arrived safely during the early part of 2006. The ship carrying the Mitsubishi equipment from Takasago, Japan, experienced 30-foot waves during its journey. In Oregon, excessive rains caused the Columbia River to reach flood levels preventing the equipment from being be unloaded until flooding eased. Construction was on schedule until late in 2006 when shortages of labor and productivity issues were encounted. Steps were taken to address both in a timely manner. The quality of work was good and construction was conducted in a safe manner with no days-away-from-work injuries. PGE provided overall project management with a small, dedicated group of professionals, supplemented with engineers, analysts and specialists from several other PGE departments. The plant construction schedule was integrated with schedules for transmission line construction, switchyard construction and various support systems that tie into the plant. Besides scheduling and general work coordination, PGE also managed the cost, communication and project risk. A risk management process was developed and was constantly updated as the project went through the various phases of construction. Management was kept abreast of the risks and their effects on plant schedule, cost and liability. Startup/ Commissioning First fire was achieved in January 2007. Startup and commissioning was a joint effort under Black & Veatch’s direction with Mitsubishi and PGE personal participating on a daily basis. Mitsubishi technical advisors from Takasago were on hand and played a major role in testing, tuning and trouble shooting the gas turbine. As part of the commissioning process, the steam piping was hydrolazed to remove rust and scale. This reduced the duration of the first steam blow to less than one week, saving fuel and helping to keep the project on schedule. During commissioning, several challenges threatened to delay the project schedule:

• Slower-than-expected auxiliary boiler ramp rates proved unable to meet the gas turbine’s cooling requirements, so an attemperator and a bypass valve had to be added to the design.

• The perforated plate on the HRSG was damaged during start-up and had to be repaired. • During final testing, minor damage caused by a foreign object was discovered in the gas turbine

compressor and combustion path. All damaged parts were replaced in record time and performance/ reliability testing was completed on schedule. Black & Veatch, Mitsubishi and PGE all worked together as a team during startup. PGE operations team under the EPC contractor’s direction played an important role during the day to day startup activities. This allowed them to gain valuable experience on this advanced technology plant. PGE will own and operate Port Westward and has hired an 18-member operations team. This team was brought in six months before first fire and participated in startup and commissioning. This on the job training assisted our operations team and the transition from EPC contractor to PGE was smooth. The plant has operated well since beginning commercial operations. Plant performance test results exceeded contractual guarantees and PGE is pleased to be operating this highly efficient plant. In this day and age of high and volatile gas prices Port Westward operates at or near base load serving our customer base in Oregon. The plant cycles well between 50% and 100% load with high ramp rates allowing additional flexibility for our trading floor. In today’s market of volatile gas prices this plant is dispatched every day at base load. The low heat rate is assisting in its dispatch and PGE expects this plant to help all our stakeholders as it continues to run reliably. Author Jaisen Mody holds a Masters degree in Mechanical Engineering from the University Of Washington and has been employed by PGE since 1979. He managed the engineering, construction and startup of the Port Westward Project. Reference H. Arimura, Y. Iwasaki, Y. Fukuizumi, S. Shiozaki and V. Kallianpur, “Upgraded M501G operating experience”, Proceedings of ASME Turbo Expo, Reno Nevada June 6-9, 2005, paper #ASME GT2005-69135.

Captions: Photo 1: Port Westward Plant site June of 2007. Photo courtesy of Black & Veatch Construction Inc. Photo 2: Original (L) and upgraded (R) turbine blade configuration. Photo courtesy of Mitsubishi Power Systems Photo 3: Original (L) and upgraded (R) turbine vane configuration. Photo courtesy of Mitsubishi Power Systems Photo 4: Piles being installed. Photo 5: Gas turbine on transporter. Photo 6: Erecting Steel for Plant Services Building, December of 2005 Photo 7: HPIP Steam Turbine coming off Barge, January of 2006 Photo 8: HPIP Turbine, March of 2006 Photo 9: Stack of the HRSG Photo 10 & 11: Port Westward Plant, June of 2007

Photo 1: Aerial View of Port Westword Plant Site

Photo 2: Original (L) and upgraded (R) turbine blade configuration.

Photo 3: Original (L) and upgraded (R) turbine vane configuration.

Photo 4: Piles being installed

Photo 5: Gas Turbine on transporter.

Photo 6: Erecting Steal for Plant Services Building

Photo 7: HPIP Steam Turbine coming off Barge

Photo 8: HPIP Turbine

Photo 9: Stack of the HRSG

Photo 10: Port Westward Plant

Photo 11: Port Westward Plant