and debris entrained in the flue gases. The gradual accumulation of highly insulating fouling material progressively reduces the convective section heat transfer efficiency (see Figure 3 ). The result is diminished absorbed duty in the convection section and consequent insufficient process preheat, steam generation, and high stack temperature. This results in increased fuel consumption, further straining both operational budgets and environmental compliance efforts. Carbon tax and the effects on refineries
Process optimisation Improve energy e ciency in fuel combustion FFC Unit optimisation Reduce aring
Combustion fuel substitution by
Reforestation/ natural sinks
gas and/or hydrogen
Emission Reduction Strategies
H O
Crude oil substitution for lower carbon feedstock
Green hydrogen
Low-carbon technologies Electric furnace or boilers CCS Biomass gasi cation Electrofuels
Renewable power
Currently, Asia Pacific is the largest contributor to refinery emissions globally. The region has 35% of global refinery capacity, but accounts for 43% of global refinery emissions. Sixty-six different carbon tax schemes around the world have resulted in a lack of uniformity in carbon policy, pricing, and the timing of introduction. A lack of uniform policies makes it difficult for refiners to pass on the costs of carbon to customers without complex border adjustment mechanisms in place. This could have a significant impact on the profitability of many plants, making reducing CO₂ emissions even more important. A multi-layered approach to mitigating fired heater inefficiencies Various technological developments have enabled a more integrated and effective approach to optimising fired heaters. High-emissivity ceramic coatings High-emissivity ceramic coatings can be applied to both process tubes and refractory surfaces. These coatings enhance radiant and conductive heat transfer, prevent oxidation and scale formation, and reduce NOx and CO₂ emissions. In catalytic reformers, their application has been shown to increase radiant section efficiency by an average of 6.6%, with corresponding
Figure 1 Emissions reduction strategies
This leads to grain boundary penetration of carbon, carbide formation, embrittlement of the surface, crack formation, and loss of metal. The result is reduced service life of the radiant tubes. Role of refractory Refractory surfaces also play a critical role in radiant section performance. Besides providing an insulating barrier to heat loss through the shell, the nature of the refractory surface also influences the radiant heat transfer efficiency to the process. Ideally, these should act as black- body enclosures with maximum emissivity. However, conventional refractory linings often have suboptimal emissivity, which reduces the net heat absorbed by the process tubes and necessitates additional fuel consumption to compensate for this loss. Convection section fouling Finned convection section tubes provide an efficient means of capturing heat exiting with the flue gases from the radiant sections of fired heaters, allowing for process preheating, steam generation, and other applications. The extended surfaces provided by the fins also provide an efficient means of capturing dust
Refining India
36
Powered by FlippingBook