Original title: Ice Ribbon creates the fastest ice and smart pavilion

　　In the winter sun, the National Speed ​​Skating Stadium ("Ice Ribbon" looks particularly beautiful. As a landmark new competition venue in the Beijing competition area of ​​the 2022 Winter Olympics, it has the largest all-ice design in Asia, with an ice surface area of ​​nearly 12,000 square meters. A few days ago, when I walked into the National Speed ​​Skating Hall, I saw that the ice-slab concrete structure of the venue had been completed, and a concrete floor of about 12,000 square meters was presented smoothly. What is surprising is that the maximum level difference of this huge concrete floor does not exceed 5 mm.

　　Ready to make the "fastest ice"

　　Wu Xiaonan, deputy general manager of a state-owned company and chairman of the National Speed ​​Skating Stadium Company, often describes the "ice ribbon" as "intensive farming, rising from the ground, weaving the sky, flying ribbons, the fastest ice and wisdom pavilion". He said that the ice slab concrete of the National Speed ​​Skating Stadium has been completed, laying a solid foundation for the realization of the "fastest ice" in the next step. "In late October, after 48 hours of uninterrupted construction, we finally produced a complete concrete floor with a thickness of 17 cm. The highlight of this project is that we controlled the level of the entire floor to about 4 mm, which means that If a small steel ball is on the ground, it basically won't roll."

　　The National Speed ​​Skating Stadium uses a carbon dioxide transcritical direct cooling system, and stainless steel coils are covered under the concrete floor, which is also the most important equipment for ice making. When ice making officially begins, carbon dioxide will fill all stainless steel coils in a liquid state. Considering the pressure that liquid carbon dioxide brings to the pipeline, the construction party chooses to use stainless steel coils that are not easy to corrode and have strong pressure resistance. However, the seemingly simple laying of stainless steel pipes has extremely stringent requirements.

　　"The first thing is to ensure airtightness. The 12,000 square meters of ground is covered by a circle of stainless steel refrigeration coils with an interval of 10 cm, with a cumulative length of nearly 120 kilometers. These stainless steel refrigeration coils are connected by welding with nearly 9,000 welds. The volume is very huge. When the carbon dioxide flows in the pipeline, the temperature is around minus 18 degrees Celsius, and the temperature of our ice board must be accurately controlled between minus 7 and minus 9.5 degrees Celsius according to the speed skating competition requirements. In addition, we must ensure that All the pipelines are on the same level after laying. These two requirements are also the fundamental guarantee for the realization of the "fastest ice" in the future." Wu Xiaonan said.

　　After the concrete floor maintenance and the commissioning of the electromechanical equipment are completed, the National Speed ​​Skating Stadium will officially start the ice making process. It is understood that ice making in stadiums is mainly divided into the steps of freezing bottom ice, spraying, drawing lines, and repairing ice. Before freezing the bottom ice, clean the site and remove dust to ensure that the overall environment meets the standards. Then rely on the long-term operation of the refrigeration system to reduce the surface temperature of the ice field to minus 5 degrees Celsius, and then start watering and ice making work on the field. It is estimated that it will take about two weeks for the "Ice Ribbon" to make ice for the first time. By then, the National Speed ​​Skating Stadium will achieve the "fastest ice".