Even a small amount of fouling in the radiant section of a vacuum heater adversely affects NOx, production run times and overall performance of the fired heater. What is sometimes not realised is that even a localised area of 5 mm of coke left in a coil can have a very significant impact on margin capture. Examples are given where this could lead to a yearly loss in production of US$12.6 million or significantly more. The results in this white paper show the benefit in knowing where fouling (e.g., coke and scale) has formed in a heater coil and why being confident that the coils are cleaned properly after a decoke or descale is crucial.

The consequences of some strategies that may be used to alleviate high tube temperatures caused by fouling are given, from running the furnace inefficiently to cutting coil outlet temperature and finally throughput. The commercial impacts are shown in these cases. Using a more advanced cleaning method, as is now offered with the Quest ADCV™ service as compared to convection mechanical decoking, can provide many benefits.