Freshly generated Coke Oven Gas (COG) has impurities such as coal tar, naphthalene, ammonia, Sulphur, etc. This gas is cleaned in a plant (scrubbing etc.) and the processed gas is fed to the network for use as fuel. The pipeline configurations (U & L bends), and atmospheric conditions (humidity & temperature) cause condensation inside pipes. This condensate converts into the muck (usually Tar/Sulphur) in the longer run. As it gets deposited, it reduces flow and corrodes the pipeline. The corrosion levels are not known until it starts showing up on the external side of the pipe. The pipelines are located at a height of 18-20 meters and the diameter ranges from 100mm to 2000mm and is made of stainless steel (SS). The typical wall thickness of these pipelines is 8-10mm. The temperature of the pipelines is ranging from 70 Deg C to 200 Deg C.
Please note that the COG is inflammable and catches fire with a spark. Earlier attempts of using thermography didn’t work as the difference in temperature (from outside to inside of the pipeline) was not differentiated by thermal cameras. Radio isotopes worked well at ground level but it was found to be difficult to mount at a height that requires scaffolding arrangements. Moreover, the sensor range was limited and hence a large number of such sensors were needed. This was not practical and hence was dropped. Thus, solutions are invited for a non-invasive system to detect and quantify the amount of muck deposition inside the pipelines.