refining india 2023
Enhancing profitability using high-efficiency heat exchangers
Enhancing Profitability Using High Efficiency Heat Exchangers Alfa Laval has been in the refinery industry over 40 years ago with over 3000 high efficiency heat exchangers installed across the world. The benefits of installing Alfa Laval’s technology in refinery processes are substantial, and this has been proven by the performance and economic analysis after years of implementation.
Salwati Ahmad ALfa laval
Alfa Laval has been in the refinery indus- try for more than 40 years, with more than 3,000 high-efficiency heat exchangers installed worldwide. The company’s technol- ogy provides significant performance and economic benefits in refinery processes. Crude distillation unit Crude distillation is the heart of the refin- ery, and optimal performance of this pro- cess is key to profitability. Alfa Laval has more than 1,000 Compabloc welded heat exchangers installed worldwide in atmos- pheric and vacuum distillation processes. There are 25 preheat trains in which every single heat exchanger is a Compabloc. Energy consumption in atmospheric and vacuum distillation processes accounts for more than 30% of the total energy con- sumption of a refinery. Therefore, maxim- ising energy efficiency to reduce energy consumption has a direct impact on the profitability of the refinery. Using Compabloc heat exchangers in the crude preheat train could help reduce energy consumption in the fired heater in two ways. The first is by maximising heat recovery from the hot fractions leav- ing the distillation column. The second is by reducing the pressure drop in the over- head vapour system, thereby reducing the operating pressure in the flash zone of the column. This means energy consumption in the fired heater can be reduced by at least 25%. With low-fouling heat exchang- ers, the end-of-run energy efficiency of the plant will not be far from the start-of-run efficiency. Another opportunity to improve the energy efficiency of the distillation pro- cesses is to recover more waste heat. Using Compabloc heat exchangers for run-down cooling or vapour condensing enables maxi- mum recovery of low-grade energy for the generation of superheated steam or boiler feed water preheating or district heating. Crude Preheating Case Study A major US refinery installed nine Compabloc heat exchangers in the crude preheat train as part of a revamp project. The main objective was to increase the heat recovery while using higher alloys that allowed the refiner to process more advan- tageous crude oils. The results from a pinch analysis showed that the Compabloc solu- tion would allow the refiner to increase the inlet temperature to the heater by an additional 100°F, saving millions of BTU in energy as well as a significant emission reduction. Compabloc were put into service in several locations: atmospheric OVHDS, naphtha kerosene, and vacuum tower bot- tom vs crude positions. Actual operating data from the crude confirms the pinch analysis performance expectations. In addition, the performance and temperature of the Compabloc have remained stable throughout the operating period, proving that low fouling can be expected with the
Alfa Laval solutions for refinery processes
1. Crude distillation (ADU/VDU) 2. Crude oil desalting 3. Naphtha & Kero hydrotreatment 4. Catalytic reforming 5. lsomerisation 6. Fluid catalytic cracking 7. Alkylation 8. Gasoil & residue hydrodesulphurisation
9. Gasoil & residue hydrocracking 10. Visbreaking 11. Hydrogen production 12. Amine treatment
13. Sour water stripping 14. Lube oil production 15. Bitumen production 16. Delayed & flexicoking
Figure 1 Alfa Laval solutions for refinery processes
heat exchangers when designed correctly. Crude distillation unit Crude distillation is the heart of the refinery, and optimal performance of this process is key to profitability. Alfa Laval has more than 1000 Compabloc welded heat exchangers installed in atmospheric and vacuum distillation processes all around the world. There are 25 preheat trains in which every single heat exchanger is a Compabloc. Energy consumption in atmospheric and vacuum distillation processes account for more than 30% of the total energy consumption of a refinery. Therefore, maximizing energy efficiency to reduce energy consumption has a direct impact on the profitability of the refinery. Naphtha combined feed/effluent exchanger (CFE) Using Compabloc heat exchangers in the crude preheat train could help reducing energy consumption in the fired heater in two ways. The first is by maximizing heat recovery from the hot fractions leaving the distillation column. The second is by reducing the pressure drop in the overhead vapor system, thereby reducing the operating pressure in the flash zone of the column. This means energy consumption in the fired heater can be reduced by at least 25%. With low-fouling heat exchangers, the end-of-run energy efficiency of the plant will not be far from the start-of-run efficiency. Another opportunity to improve the energy efficiency of the distillation processes is to recover more waste heat. Using Compabloc heat exchangers for run-down cooling or vapor condensing enables maximum recovery of low-grade energy for generation of superheated steam or for boiler feed water preheating or district heating. energy consumption in the fired heater Naphtha hydrotreating unit The need for hydrotreating is increas- ing as refiners adapt to changing sulphur regulations in engine fuels. To help meet these regulations for gasoline, a naphtha hydrodesulphurisation unit is used, generi- cally called a naphtha hydrotreater (NHT). NHTs are critical refinery process units that remove sulphur from gasoline components by reacting with hydrogen in the presence of specialised catalysts. The process is energy intensive and requires a high degree of heat integration to lower the energy operating expenditures. Over the past decades, refin- eries have been boosting process efficiency by using Compabloc plate heat exchangers in key heat recovery positions. components. Maximising this heat exchang- er’s performance by minimising the feed/ effluent approach temperature is critical as it drives the energy efficiency of the entire process. Heat exchanger designers focused on the hot-end approach temperature (HAT) did you know? Compabloc heat exchangers in the crude preheat train could help reduce
with Compabloc technology, the pinch can easily be reduced to less than 6 to 10°C. This means that by using a traditional tech- nology, the number of S&T in series and the heat transfer area needed to do the same duty will be significantly higher, as will the cost of the heat exchangers. Naphtha CFE case study A major refinery in Europe needs to debot- tleneck an existing naphtha hydrotreater and identified the CFE heat exchanger heat recovery as a limiting factor to its project goals. Additional S&Ts in series with the existing S&T CFE train were evaluated, but the performance of the additional shells fell short of its goals and the new train con- sumed too much pressure drop. Finally, as is often the case, insufficient space was available to install the additional S&Ts, so the project was not feasible with this tech- nology. Concurrently, the refinery evaluated Compabloc heat exchangers to be placed on the hot end of the feed side, vaporising and superheating the feed with hot reac- tor effluent while still using the S&Ts on the cold end. The operating parameters were optimised by Alfa Laval specialists and the
and the minimum internal delta temperature (pinch) as limitations to the thermal design. Pinch temperatures are a function of service and heat transfer technology. For a shell-and-tube unit in the hydro- treater CFE service, typical the internal pinch is between 20 and 40˚C. However,
In this exchanger, process feed is com- bined with hydrogen. It is heated and boiled to a superheated vapour in a series of heat exchangers. The heat source is reactor product vapours, which need to be cooled, condensed, and then separated into various
Petroleum gas and light naphtha
Classified by Alfa Laval as: Business
Distillation tower
Crude oil feed
Heavy naphtha
Kerosene
Fired heater
Light gas oil (LGO)
Heavy gas oil (HGO)
Atmospheric residue
Preheated crude oil
Figure 2 Compabloc in crude preheat train
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