Wisconsin DNR nears permit decision on Columbia coal plant upgrades

The Wisconsin Department of Natural Resources plans a Dec. 18 local public hearing on a draft permit that would allow Wisconsin Power and Light to replace the coal pulverizers and upgrade the turbines at the Columbia power plant in Columbia County, Wisconsin.

The coal pulverizers of each boiler will be replaced, and the steam turbine for each boiler will be upgraded as part of this project, the DNR said. Wisconsin Power and Light (WPL) is a co-owner of and the operator of the nominal 1,054-MW coal fired Columbia Energy Center (CEC). WPL is planning to perform various efficiency projects for CEC Units 1 and 2. These efficiency projects are part of the CEC Comprehensive Asset Management Plan (CAMP) Program. The CAMP is being implemented to improve plant efficiency. The CAMP projects include steam turbine upgrades and replacement of pulverizers.The upgrades to the steam turbine and replacement of the pulverizers are expected to allow WPL to improve the heat rate of both Units 1 and 2 as well as expand the periods in time between routine planned maintenance outages.

In addition to the CAMP projects, in November 2011 WPL was issued a permit to install air quality control systems (AQCS) at Columbia. Since the modifications associated with the CAMP Project are in close proximity time wise with the AQCS project and were under consideration at the same time as the AQCS Project, these two projects are aggregated into a single project for the purposes of determining applicability to the Prevention of Significant Deterioration (PSD) review. The aggregated AQCS and CAMP projects will result in an increase in fuel consumption on an annual basis. This increase in fuel consumption will result in an increase in carbon monoxide (CO) and greenhouse gas (GHG) emissions above the respective PSD significant levels. A PSD permit application for the combined project will be required.

The CAMP Project includes the following key attributes:

  • Resolve the stress corrosion cracking issue in the LP steam turbine rotors;
  • Improve the reliability of the coal pulverization system;
  • Reduce annual pulverizer maintenance cost;
  • Improve the heat rate (efficiency) by approximately 4%;
  • Reduce emission intensity on a pounds per megawatt hour basis;
  • Increase the annual average hourly capacity offer to the Midcontinent Independent System Operator market for energy production;
  • Increase the average tested capacity (MW) for resource adequacy.

The facility has two General Electric (GE) turbines that were installed during the construction of Unit 1 in 1975 and Unit 2 in 1978. Each of the turbines consists of one dual flow combined high pressure and intermediate pressure (HP/IP) section and two dual flow low pressure (LP) sections and is connected to a GE generator rated for 617.8 megavolt-ampere (MVA).

The Columbia Units 1 and 2 existing steam turbines are GE G2-Series turbines. Each steam turbine is coupled to a GE 617.8 MVA hydrogen and water cooled generator. The efficiency of the existing steam turbines has experienced typical degradation over their more than 35 years of operation. In addition to full recovery of this performance degradation, a steam turbine upgrade will incorporate advances in steam turbine technology that have taken place over the past 35 years, making the CAMP Project economically advantageous, the DNR noted.

The steam turbine upgrade portion of the CAMP Project includes the supply and installation of a modified steam path consisting of the following:

  • Fully bladed High Pressure (HP)/Intermediate Pressure (IP) and Low Pressure (LP) rotors;
  • Fully bladed HP/IP and LP inner casings; and
  • Replacement and upgrade of all steam seals.

The Columbia Unit 1 and 2 boilers were manufactured by Combustion Engineering (now Alstom) and have six pulverizers per unit. Each pulverizer supplies fuel to four burners (one on each corner of the furnace) and has a design capacity of approximately 138,000 pounds per hour. Each pulverizer is supplied fuel by a gravimetric type feeder. Major components within the existing pulverizers are reaching the end of their useful life. Depending on the severity of the failure, the pulverizer could be out of service for up to approximately four months. The installation of new pulverizers would improve equipment availability, reliability and efficiency, reduce maintenance costs, and reduce the likelihood of future unit de-rates.

The Public Service Commission of Wisconsin on Oct. 29 approved the co-owners of the Columbia plant for installation of new generator step up transformers for the plant.

Alliant Energy’s (NYSE: LNT) WPL subsidiary and its co-owner utility partners on Jan. 8 received final regulatory approval to upgrade the coal pulverizers and steam turbines at Columbia Energy Center, which is the project now being permitted at the DNR. The investment in new technology and equipment is expected to be around $130m and will be shared with plant co-owners Madison Gas and Electric and Wisconsin Public Service.

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.