Construction and lining of the Spurlock steel chimney flues: well planned, well executed, systematically supervised
After considering the jobsite layout, the project time schedule and the weather conditions in Kentucky, Karrena International decided that they would build, grit blast and primer coat steel flue sections on ground level. Once a steel flue was erected by welding these sections together in the windshield, the PennguardTM lining was applied in the erected flue, using a movable work platform.
To ensure the quality of the installed PennguardTM linings in the two Spurlock chimneys, a team of up to three Hadek Quality Assurance (QA) Inspectors was present on site during the surface preparation and lining installation process. Between its offices in Rotterdam, the Netherlands and Pittsburgh, Pennsylvania, Hadek Protective Systems has a group of 14 Quality Assurance Inspectors who are trained to supervise the complete field installation process of a PennguardTM lining.
These pages show some pictures of the process of constructing and lining the Spurlock steel chimney flues.
The steel flue diameter of the Unit 1 chimney is 6.40 metres. The Unit 2 steel flue is 8.24 metres in diameter. Karrena decided to pre-fabricate steel flue sections on site, close to the new chimneys. The grit blasting required for the PennguardTM Block Lining System, as well as the application of PennguardTM Block Primer, were also performed on ground level.
Once grit blasted and primer coated, the steel flue sections were carried to the chimney with a mobile crane. The sections were then attached to the flue in the chimney by welding from two sides. The welds were cleaned with power brushes and then hand painted with PennguardTM Block Primer.
With flue erection complete, Karrena installed a full size suspended work platform to facilitate the installation of the PennguardTM lining system. The platform accommodated a team of up to 10 installers and support workers, who applied the PennguardTM lining from the bottom to the top of each flue. A smaller, faster lift moving through a hatch in the center of the platform was used for transportation of the installation crew, their tools and the PennguardTM lining materials. The lining of the 162 m tall Unit 1 flue took 45 days and the lining of the 165 m tall Unit 2 flue took 38 days.
Mixing of the two component PennguardTM Adhesive Membrane is a critical step in the application process. For the Spurlock project, Karrena used two of Hadek’s proprietary, automated mixing machines. In order to track the quality of the mixing process on a pail-by-pail basis, the staff in charge of the mixing machines produce a small sample card for each pail. Hadek’s QA Inspectors will systematically check the curing of the adhesive on the cards, as a first confirmation that mixing has been successful.
On the work platform, the installers apply the PennguardTM lining using a double buttering technique while minimizing any air inclusion. The installers apply the adhesive back and side joints at the required 3 mm thickness. The application process is monitored by Hadek QA Inspectors, who also keep track of temperature and humidity at regular intervals. The two steel flues in the Unit 1 and Unit 2 wet stacks have a combined surface of 8,130 m².
Fire safety in power plant chimneys: PennguardTM linings reduce fire risk both during and after construction
For any power station owner, fire is one of the more serious risks both during the construction of new plant and during operation and maintenance of existing equipment. FGD plants and the chimneys built directly next to FGD plants are no exception. Ever since the introduction of FGD, a number of large fires have occurred in FGD plants in North America, Europe and Asia.
At Hadek’s request, the Thermal Sciences group of the Exponent engineering company have performed a study entitled “Performance of Different Chimney Flue Designs During Large Power Plant Fires”.
PennguardTM lined test wall before the ASTM E-119 test. Temperatures measured during the ASTM E-119 test.
Exponent’s study report shows how PennguardTM lined steel chimney flues are effectively insulated from overheating, as they are filled with extremely hot smoke from an FGD or power plant fire. By comparison, steel flues without a PennguardTM lining or FRP flues are more likely to overheat, catch fire and collapse (study report is available on request).
Exponent’s test work also included a fire propagation test, to see how a fire could escalate if the joints between PennguardTM Blocks are accidentally set on fire. The test showed that although the joint will catch fire, it will burn slowly and has a tendency to extinguish by itself after some minutes.
The Exponent study shows that although good fire safety practice still has to be followed during construction and operation, the use of PennguardTM lined chimney flues is a valuable, additional step in improving power plant fire safety.
Thermocouples for monitoring of steel substrate temperature. Inside of test chamber during the ASTM E-119 test.