With the transition from coal-fired power generation in Canada, the Alberta power producers took the opportunity to challenge the old-school ways to reduce emissions and increase efficiency. By repowering their conventional plants to utilize clean, efficient, low emission, very competitively priced natural gas – a fuel source solution in abundance in Alberta - power producers are succeeding in making these changes.
The Maxim Power Corporation’s Milner II Phase I Repower Project is a spectacular example of this repowering. Maxim Power wanted to decommission their active coal-fired unit in Grande Cache, Alberta and replace it with a 200MW simple-cycle natural gas power unit. They located and purchased a new but grey market GE gas fired combustion turbine and Vogt HRSG that had been in storage in Utah for eight years but never installed. After the grey market unit was purchased, it was decided to split the installation into two phases. Phase I would be the construction of the simple-cycle gas turbine and Phase II would add the HRSG to provide a combined cycle operation and provide steam for the existing mothballed steam turbine in the old plant.
Maxim Power called on BPC (a joint venture of PCL Industrial and Black & Veatch) to provide a fast tracked solution and install the equipment on the existing Milner site and have it in operation and generating cash flow as quickly as possible. Within the joint venture partnership, B&V provided the engineering design, major procurement and commissioning/start-up specialists. PCL Industrial provided the pipe fabrication, completed all construction utilizing direct-hire craft and provided commissioning and start-up craft support.
BPC’s Milner project group were faced with some unique challenges throughout the project. Piling extended through the first winter on site. The grey market unit was not designed to withstand the harsh northern Canadian winter, where -40C is not uncommon, so the team needed to retrofit the unit to adapt it to the climate. The unit also needed to be protected from the continual coal dust from the adjacent mine.
The first summer onsite also brought unique challenges for the team. The summer that the unit was installed was the wettest summer in over 30 years, and when the rainwater mixed with the existing coal dust and dirt on the ground, the resulting muddy black slough needed constant pumping and draining. Despite the hurdles brought on by the weather, the schedule was maintained.
Another hurdle was the combustion turbine and generator foundations, which required over 800 cubic meters of concrete in a single monolithic pour. The local batching plant didn’t have the capacity to produce this amount of concrete in one day and in this remote location, all other sources were too far away. The solution? BPC set up a portable batching plant on site to provide the necessary concrete.
After the concrete pour, the natural gas power unit was ready to be installed. However, since it had originally been designed for a warmer location with different regulations and had been in storage for over eight years, it needed to be updated. Before it could be installed, the unit had to be updated and recertified to meet current pressure vessel requirements and electrical requirements before it could be operated. In addition, some of the parts needed to be replaced due to age and product updates. The PCL fabrication facility was brought in to help with fabrication of replacement GE piping as the original piping did not meet ABSA regulatory requirements, all without delaying the construction schedule.
For all of the challenges that the team faced with the retrofit and the weather, nothing could have prepared them for the biggest challenge of all – the COVID-19 pandemic that began just as commissioning was starting. More than half of the team had finished their work, so there were only 50 PCLers onsite, but it meant that there were more than enough lunchrooms and offices to observe social distancing. PCL also increased janitorial care frequency of the washrooms, lunchrooms and offices, ensuring that the common areas were sanitized almost every hour. As well, strict measures were taken to ensure that social distancing was observed, and masks were worn everywhere onsite when distancing could not be achieved.
The biggest COVID related challenge? The team responsible for the commissioning and system change from coal to steam was based out of the United States. When the border closed, even though this utility construction was deemed an essential service, the team were still required a two - week quarantine in a hotel room. Rather than quarantine, the crew elected to stay onsite through to the completion of the project, moving from a two-week on, one-week off rotation to staying at work without going home. The team buckled down and worked 12 hours a day for 12 to 14 weeks to finish the project on time and on budget.
With most of the big challenges behind them, the team was ready for the final step of Phase 1 – integrating the new gas unit into the existing plant. The integration into the existing 50-year-old Milner I plant control room and high voltage switchyard needed to be seamless as the construction of the new unit was happening during regular operation of the existing unit. There is a lot detail and effort in the coordination and execution of turning off the old system and connecting into the new one. The switching process involved an intricate lockout to ensure the safety of the construction workers, plant operators and the equipment. The combustion turbine would be operated from the existing Milner I control room, low and medium voltage operational power supplied by the existing Milner I electrical room, and the high voltage power generated is distributed through the existing ATCO high voltage switchyard.
The final step was the installation of all new computer operator stations and connecting them into all of control systems that existed in the Milner I control room. Close to the end of construction, the operators were sitting there running a 50-year-old panel with pneumatic gauges and switches on one side, and on the other side were new operator interface screens and processors, waiting to be turned on.
The result was a new unit that started up smoothly at full capacity and was finished a full month ahead of schedule. This simple fact, taking into account all the uncontrollable challenges, trials and tribulations through the project, demonstrates how a highly experienced, highly capable tier one solution provider is the right solution for difficult and unusually challenging projects. Creativity anchored in experience and resources will always be the most overall cost - effective solution to an industrial process project.
The Milner II Power plant has been steadily producing just under 200MW daily since it went into commercial operation, making it the largest simple cycle power plant producing in Alberta. And Because of the successes on Phase 1, the owner selected BPC to handle Phase II – a true testament to the client’s satisfaction.