SaskPower Flue Gas Casing and Transitions

The Client

SaskPower is the principal electric utility in Saskatchewan, Canada. SaskPower generates power from 18 generating facilities, including three coal-fired base load facilities, six natural gas-fired facilities, seven hydroelectric facilities, and two wind power facilities. SaskPower serves more than 490,000 customers through more than 151,000 kilometres of power lines throughout the province.

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The Challenge

SaskPower required multiple duct sections for their Carbon Capture and Storage (ICCS) Project at their Boundary Dam Power Station in Estevan, Saskatchewan. This project is SaskPower’s flagship CCS initiative and is the World’s First Post-Combustion Coal-Fired CCS project.

In previous projects, similar ducts were designed to be fabricated in small panels which would be delivered to site and then completely assembled/welded on site. SaskPower approached Saskarc to complete the entire fabrication of the ducts offsite and then transport to site and install.

The duct sections were very large and heavy and to ensure there were no fit problems on site each section had to be pre-assembled and shop fit prior to shipping. Dimensional accuracy, and square tolerances were of the utmost importance. Detailed and precise fabrication and welding techniques had to be implemented and diligently practiced for the entire project.

The project dimensions:

  • The inlet transition duct – 38.8 ft L x 33 ft W x 42.2 ft H, and weighed 119,214 Lbs.
  • The cooling duct – 12 ft Deep x 41.3ft W x 48.8 ft H and weighed 171,820 Lbs.
  • The outlet transition duct – 38.8 ft W x 42.2 ft 33 ft W x 42.2 ft H and weighed 119,340 Lbs

The Solution

Duct sections were shop fit and welded in panels and then the panels were preassembled to form the modular sections. The ducts were then assembled in the fabrication shop and transported to the mod yard for final assembly and test-fitting.

The duct sections were very large and required special care in fabrication as the flange fit up was crucial. Saskarc, with the help of our engineering personnel, designed specific points where temporary support braces were required to assist with the critical dimensional requirements after fabrication and welding was complete.

Crane services were required to perform the pre-assembly in our modular yard. The final duct assembly was performed in mid-winter which complicated the fit up and welding procedures. Additionally, preheat for the welding area was necessary due to the cold temperatures that prevailed.

The majority of the internal surfaces in the ducts required a specialized corrosion resistant liner to be installed on site after final erection. These surfaces had to be ground smooth and all corner welds required to be ground with a minimum 1/4″ radius. Grinding and polishing was extensive to ensure a near perfect surface finish for application of the liners.

The physical sizes of all 3 duct sections were pushing the transportation limits and there were numerous issues that had to be addressed. Due to the extreme height of the ducts, most of the overhead power lines had to be cut along the route to the jobsite. Additionally, the only route into the construction site had overhead high voltage transmissions lines and these lines could not be cut. In order to maintain the minimum clearance requirements the road directly under the power lines had to be excavated and lowered 6 feet to allow safe passage of the loads. Due to the extreme width of these ducts a portion of highway on the route had to be closed to local traffic during transportation. The route from Saskarc to the jobsite was only 65 kilometers, but the transport for each duct section took on average 12 hours.

The Results

The scope included shop detailing, fabrication of all structural and plate steel, blasting and painting, assembly/modularization of the (3) ducting modules, lifting lugs, route surveys and transportation to site of 205 tons of modularized platework.

  • The modularization of the ducting offsite significantly reduced the onsite erection schedule as well as minimized the work force requirement on site. Savings to the project were realized through reducing costly travel and living out allowances, reducing inclement weather downtime and costly equipment rentals. Furthermore, the reduced work force on site reduced the site health and safety exposure.
  • Feedback from the client regarding this project:

“Timely performance of the work was a matter of paramount importance to SaskPower as these ducts were an integral part of maintaining the scheduled installation, commissioning, start-up and operation of the project. Saskarc was able to maintain the schedule and meet the delivery requirements. Through the entire project, Saskarc maintained the highest level of quality, provided on time delivery and their project management team was very professional and dedicated to working as a team with SaskPower and other contractors to ensure the successful completion of this project.”

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