Refinery Energy Losses Due to Fouling in Heat Exchangers Figure 5: Economic Assessment of Losses Due to Fouling in the Hot End of a Pre-heat Train A


14 16


12 10 8 6 4 2


0 50 100 B


7 8


t FFL


6 5 4 3 2 1


150 200 Time (days) Emissions Fuel


one year of operations. When the furnace hits its maximum capacity, throughput must be throttled back and the costs ramp up very quickly depending on the profit margins. In the worst case (see Figure 5A), with the small 85MW furnace, the maximum capacity is reached after just 130 days and with profit margins of US$10 per bbl, losses add up to over US$15 million after a year of operations. If a larger furnace is used (i.e. 90MW, see Figure 5B), the maximum hit duty is hit much later and throughput losses are reduced. Even when furnace capacity is not a bottleneck and total costs are given only by extra fuel burnt, related


Pumping Production loss


emissions and extra pumping costs, losses still amount to US$4 million per year, or US$4.4 per barrel on average.


A network retrofit case study for a small refinery serving a state island19 highlights that fouling plays a major role in the energy recovery and should be considered at the design stage. Figure 6A shows the decline in coil inlet temperature due to fouling for the existing network (configuration C1) compared with three retrofit structures which include an extra unit placed in different positions (C2, C3 and C4). A trade-off


250 300 350 0 50 100 150 200 Time (days) 250


US$2 bbl-1 t FFL


300


350


US$10 bbl-1


10US$ bbl-1


US$2 bbl-1


Cumulative costs (MUS$)


Cumulative costs (MUS$)


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