PacifiCorp pursues Hunter, Hayden coal plant retrofits

PacifiCorp plans to shut off the coal burn at the end of 2014 at Naughton Unit 3 in Wyoming and to have the converted unit ready to burn natural gas by June 2015.

Those facts were included in initial testimony that PacifiCorp filed Jan. 3 at the Utah Public Service Commission to begin a new rate case. Since then, various parties have moved to intervene in the case as the commission readies for months of review of the rate application.

Chad Teply, vice president of resource development and construction for PacifiCorp Energy, supplied testimony about power plant projects.

For one thing, he noted that the gas-fired Lake Side 2 project in Utah remains on schedule to be placed in service by June 2014.

Another major highlight of the Teply testimony was a description of the emissions control equipment investments required to comply with environmental laws, including the Clean Air Act Regional Haze Rules and the Mercury and Air Toxics Standards (MATS). The investments include a baghouse conversion and low NOX burners (LNB) installation at the coal-fired Hunter Unit 1 in Utah, and a selective catalytic reduction (SCR) system installation at the coal-fired Hayden Unit 1 in Colorado.

The Hunter Unit 1 projects are required to be installed by spring 2014 by the state of Utah Regional Haze State Implementation Plan (SIP) and have been determined to be the least cost compliance alternative for the unit when incorporating costs for potential greenhouse gas (GHG) regulatory outcomes, other emerging environmental regulations, and potential long-term incremental emissions reduction strategies into the economic assessments of the projects.

The Hayden Unit 1 SCR is required by the state of Colorado’s Regional Haze SIP to be installed by Dec. 31, 2016. The Hayden Unit 1 SCR is also a key component of the NOX reduction plan from Public Service Co. of Colorado (the Xcel Energy subsidiary that operates Hayden Unit 1) to the Colorado Public Utilities Commission under the Colorado Clean Air-Clean Jobs Act. PacifiCorp is a minority owner of Hayden Unit 1, with an interest of 24.5%.

The other significant generation plant projects being placed in service during the July 2014-June 2015 rate case test period include the 34-MW Blundell geothermal resource well integration project and the Naughton Unit 3 natural gas conversion project. The Naughton Unit 3 natural gas conversion project is being pursued as the least cost compliance alternative to the state of Wyoming’s Regional Haze SIP requirements for Naughton 3. The natural gas conversion project was identified as the least cost alternative to installing an SCR and baghouse on Naughton Unit 3.

645-MW Lake Side 2 gas project almost ready to start generating

Lake Side 2, located in Vineyard, Utah, is a 645 MW natural gas-fired generation facility, consisting of a 2×1 combined-cycle configuration, using two combustion turbine generators and a single steam turbine generator. More specifically, Lake Side 2 is nominally rated at 548 MW base load and 97 MW of duct firing for a total net capacity of 645 MW at the average ambient temperate of 52 degrees Fahrenheit. Each combustion turbine exhausts into its own heat recovery steam generator which then commonly supply a single steam turbine generator.

The electrical energy generated by Lake Side 2 will be delivered to a new 345-kV point of interconnection substation (Steel Mill) where it will tie into the PacifiCorp transmission system. Lake Side 2 is currently scheduled to reach substantial completion to generate and provide energy and capacity to customers by June 2014.

Lake Side 2 is located in the company’s east balancing authority. PacifiCorp can dispatch power and energy from Lake Side 2 on a forward, day-ahead basis, with real-time optimization of the plant’s usage. This dispatch flexibility will give the company an additional system resource with the ability to provide operating reserves, load-following reserves, and automatic generation control. The added system flexibility will provide increasing benefit to PacifiCorp as load grows, its existing flexible contracts expire, and new wind and solar resources are added to the system, Teply pointed out.

Hunter Unit 1 getting LNBs and baghouse conversion

The Hunter plant is a three-unit coal-fueled plant in Utah with a net generation capacity of approximately 1,320 MW and a currently approved depreciable life for ratemaking purposes of 2042. Unit 1 is 93.8% owned by PacifiCorp and 6.2% owned by the Utah Municipal Power Agency. Units 1 and 2 are basically identical units when considering their base design and originally installed boiler and steam turbine generator equipment. Unit 3 is identical in layout to Units 1 and 2 except the boiler and turbine are from different manufacturers.

Coal is supplied by truck to Hunter from the nearby Sufco, Cottonwood, Dugout, and Deer Creek deep mines. Hunter has a blending facility in the fuels preparation facility, which allows for combustion of various coal types. Deer Creek is owned by PacifiCorp, while the other mines are owned by outside suppliers.

The Hunter Unit 1 baghouse conversion project replaces the originally installed particulate matter (PM) control equipment (electrostatic precipitator) on the unit with a best available retrofit technology baghouse to meet the company’s emissions compliance obligations required by the Regional Haze Rules and incorporated into the state of Utah’s Regional Haze SIP and associated permits by spring 2014. Capturing mercury in the baghouse allows the unit to comply with the EPA’s MATS requirements for mercury capture by the prescribed deadline of April 16, 2015, without installing incremental stand-alone mercury emissions control equipment.

An additional emissions control benefit that the baghouse brings to Unit 1 is the ability to close the scrubber bypass currently installed on the unit, which when considered in conjunction with the Hunter Unit 1 scrubber, reagent preparation, and waste handling projects completed on the unit in 2012 allows the unit to meet a reduced SO2 emissions limit required by the state of Utah Regional Haze SIP and associated permits by spring 2014.

Other equipment to be installed as part of the baghouse project includes upgraded booster fans, boiler reinforcement, new ductwork, modifications to the existing chimney, relocation of the stack opacity monitors, electrical infrastructure, controls, and other miscellaneous appurtenances and support systems.

Construction of the Hunter 1 project began in 2013, and the baghouse conversion is scheduled to be completed and placed in service following a planned major maintenance outage on the unit in spring 2014.

The LNB installation project on Hunter Unit 1 includes the installation of NOX combustion controls that replace originally installed equipment. The new burners utilize improved combustion characteristics and a separated over-fire air supply to the boiler to reduce NOX emissions. The project is scheduled to be completed and placed in service following the same spring 2014 planned major maintenance outage.

Pursuant to Utah Regional Haze SIP requirements, Hunter Unit 2 was equipped in 2011 with the same LNB and baghouse retrofit technologies contemplated in this docket for Hunter Unit 1. The same post-retrofit emissions limits for NOX (0.26 pounds per million Btu) and PM (0.015 pounds per million Btu) are required for each unit.

Hunter Unit 3 was equipped with a fabric filter baghouse (1983) when the unit was originally constructed and was retrofitted with LNB technology in 2007.

All three Hunter units are equipped with wet lime scrubbers to control SO2 emissions to a rate of 0.12 pounds per million Btu.

New SCRs on the way at Hayden in Colorado

The Hayden plant is a 446-MW, two-unit coal-fired facility located in Routt County, Colo. Unit 1 is jointly owned by Public Service Co. of Colorado (PSCo) and PacifiCorp (24.5%). Unit 2 is jointly owned by PSCo, the Salt River Project and PacifiCorp (12.6%). PSCo operates the plant.

In December 2010, the Colorado Air Quality Control Commission (AQCC) promulgated new BART determinations and emissions control requirements for the Hayden units in the Colorado Regional Haze SIP. These BART determinations set emissions limits of 0.08 lbs NOx/MMBtu for Hayden Unit 1, and 0.07 lbs NOx/MMBtu for Hayden Unit 2. Although the BART determinations did not specify how these limits were to be achieved, installation of SCRs is the only technically feasible method currently available. The Unit 1 SCR is expected to enter service in 2015, and the Unit 2 SCR is expected to enter service in 2016.

Environmental groups National Parks Conservation Association and WildEarth Guardians filed petitions for review before the U.S. Tenth Circuit Court of Appeals challenging the legality of EPA approving some aspects of the Colorado Regional Haze SIP. In general, the environmental groups are asking the court to require EPA to make the Colorado Regional Haze SIP more stringent by requiring SCR controls at more units at a faster pace. PacifiCorp, the state of Colorado and other utilities have intervened in the appeal in support of EPA’s approval of the Colorado Regional Haze SIP and against the proposition of making it more stringent, Teply noted.

Naughton 3 to go from baseload coal unit to slow-start, gas-fired peaker

The Naughton plant consists of three coal-fueled units that are all 100% owned and operated by PacifiCorp. The Naughton plant property is adjacent to Westmoreland Coal’s Kemmerer strip mine, which supplies approximately 2.8 million tons per year of sub-bituminous coal to the plant via an overland conveyor.

Naughton Unit 3, which began commercial operation in 1971, has a currently approved depreciable life for ratemaking purposes of 2029, and a net reliable generation capacity of 330 MW. The boiler was retrofitted in 1999 with LNB for NOX removal. The unit configuration also includes: a closed-loop cooling water system, with a mechanical draft cooling tower; an electrostatic precipitator (ESP) for PM removal; and a sodium-based wet flue gas desulfurization system (FGD) for SO2 removal that was retrofitted in 1981.

As part of the Naughton Unit 3 natural gas conversion project, the steam electric unit will be converted from a baseloaded 100% coal-fueled unit to a 100% natural gas-fueled slow-start peaking unit. Coal fueling equipment will be left in place except where it interferes with new natural gas fuel supply equipment. It is anticipated that natural gas supply piping to the converted Naughton Unit 3 can be modified with a new pipeline, approximately 16 inches in diameter, from the existing natural gas supplier metering station located about 1.8 miles east of the plant, Teply wrote.

New boiler natural gas fuel supply equipment will include igniters, flame scanners, LNBs, and natural gas distribution piping. Five levels of LNBs will be installed in existing air compartments on each of the four corners of the boiler and will have the capability to sustain unit operation over a net reliable load range from about 85 MW to 330 MW. Modifications to the boiler burner management control systems will be completed. New process control instruments, control wiring and high performance controller modules will be installed and integrated into the plant’s existing distributed control system.

A 15% to 20% flue gas recirculation system (FGR) will be installed to enable the boiler to attain required operating temperatures and to provide NOx emissions reductions. Flue gas will be recirculated from the existing ductwork between the economizer outlet and the air preheater inlet. Flue gas will be re-injected into the boiler wind box. The FGR will consist of two by 50% capacity fans; including lubricating oil systems, fan motors, foundations, vibration monitoring, controls and interconnecting ductwork.

Flue gas will exit the unit by flowing through: the de-energized existing ESP, the existing induced draft and booster fans, and the FGD bypass ductwork. It will discharge to the atmosphere through the existing wet FGD chimney. All flue gas duct expansion joints between the induced draft fan inlets and the FGD outlet duct will be replaced. Other demolition work will be limited to interfering items only.

PacifiCorp has lately been working on the EPC contract for the Naughton Unit 3 natural gas conversion. Proposals were received from bidders in December 2013.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.