Within the past decade, UAVs have revolutionized how design and construction projects collect useful images and data. Equipped with video cameras, thermal imaging technologies and other specialized equipment, UAVs are now flown to inspect solar farms and transmission lines, create 3D models of various facilities and refineries to perform hundreds of other tasks previously accomplished other ways — only faster, cheaper and better.
As a result, UAVs are being integrated into workflows to help solve difficult challenges and create new efficiencies. New geospatial, mapping and inspection applications emerge almost weekly. LNG peak shaving facilities are among the many places that UAVs are being utilized to revolutionize tank insulation inspections.
Consider the giant tanks where LNG is stored under low pressure at a very frigid minus 260 degrees Fahrenheit. Similar to a giant thermos bottle, these tanks must be designed with the thermal efficiency needed to prevent LNG from boiling off into vapor.
Built of concrete and steel, the tanks can be as large as 200 feet high and 180 feet across. The double-walled storage tanks contain LNG within an inner wall. To maintain LNG’s cold temperature, the space between the inner and outer walls is filled with loose insulation materials.
Over time, the insulation materials tend to settle, creating “cold spots” in tank walls. These trouble spots allow heat to leak into a tank, reducing the thermal efficiency of the LNG storage vessel, which in turn increases the internal boil-off rate of the LNG. To restore thermal efficiency, additional insulation can be injected into these cold spots through nozzles distributed along the top of a tank. But first, the cold spots must be located.
Pinpointing cold spots has traditionally been a difficult and cumbersome process. LNG facilities have typically sought to locate them by measuring the temperature variances across the surface of the LNG tank’s outer wall. Often they relied on thermal scans taken from the ground to measure these temperatures.
Given the great height of many LNG tanks, maintenance teams also sometimes used riskier methods to elevate their imaging devices so tanks could be assessed from a higher perspective. In some cases, that meant mounting thermal cameras on lifts that slowly moved up and down, capturing images of the tank surface as they circled the tank.