1、,Energy concept for future oil refineries with an emphasis on separation processes,Antonio Carlos Brando de ArajoDepartment of Chemical Engineering Norwegian University of Science and Tecnology (NTNU) Trondheim, NorwayJanuary 2007,About this presentation,Motivation: Focus on environmental aspects in
2、 oil refining is not enough (Szklo 2007, DOE 2000). Energy-efficient processes in oil refining are paramount. Need for research in this field is a must. Focus: Whats up on the future of energy consumption. Opportunities: Ill give directions. Looking at the big picture: Not restricted to separation p
3、rocesses. Goal: Attempting to show what one can expect in terms of more energy-efficient refineries.,About this presentation,Lets tear things down:,Energy concept for future refineries.,Catalytic cracking + separation unit,Energy concept = Energy efficiency. Keep it simple!,Future = Next 20 years. N
4、othing futuristic! No revolution!,Directions will be given but problems wontt be solved here!,Directions will be given Well, it cannot be different since there are lots of alternatives to consider and details cannot be given here!,Outline,A vision for the future A simple guide to oil refining Energe
5、tic issues in an oil refinery Thermodynamic analysis and measures to improve energy consumption. Crude oil distillation (atmospheric and vacuum) Fluid catalytic cracking Catalytic hydrotreating Catalytic reforming Alkylation Separation processes Recap and future directions References,A vision for th
6、e future,According to the APIs Technology Vision 2020: A Technology Vision for the U.S. Petroleum Refining Industry API 2000 report,The petroleum industry of the future will be environmentally sound, energy-efficient, safe and simpler to operate. It will be completely automated, operate with minimal
7、 inventory, and use processes that are fundamentally well-understood. Over the long term, it will be sustainable, viable, and profitable, with complete synergy between refineries and product consumers.To improve energy and process efficiency, the industry will strive to use cost-effective technology
8、 with lower energy-intensity. Refineries will integrate state-of-the-art technology (e.g., separations, catalysts, sensors and controls, biotechnology) to leapfrog current refinery practice and bring efficiency to new levels.,Outline,A vision for the future A simple guide to oil refining Energetic i
9、ssues in an oil refinery Thermodynamic analysis and measures to improve energy consumption. Crude oil distillation (atmospheric and vacuum) Fluid catalytic cracking Catalytic hydrotreating Catalytic reforming Alkylation Separation processes Recap and future directions References,A simple guide to oi
10、l refining,According to the North American Industry Classification System (NAICS) DOE 2006, petroleum refineries are defined as: Establishments primarily engaged in refining crude petroleum into refined petroleum.,Picture of the oil refinery of the future, if the oil consumption maintains its crazy
11、growth Actually, this is a 1876 oil refinery in California.,A simple guide to oil refining Exxon 2005,A simple guide to oil refining,In short: Everything is upgraded to valuable products: More fuel! Over 43% of production is gasoline. Almost 80% is converted to fuel. It is a huge process facility! L
12、ots of reactions and separations to add value to the product. Many opportunities for energy savings.,Outline,A vision for the future A simple guide to oil refining Energetic issues in an oil refinery Thermodynamic analysis and measures to improve energy consumption. Crude oil distillation (atmospher
13、ic and vacuum) Fluid catalytic cracking Catalytic hydrotreating Catalytic reforming Alkylation Separation processes Recap and future directions References,Energetic issues in an oil refinery (DOE 2000, Pellegrino 2005),Refinery gas + petroleum coke + other oil-based by-products accounts for 65% of t
14、he energy sources in an oil refinery. 38% of the energy sources in an oil refinery are used to produce non-fuel products like lubricant oils, wax, asphalt, and petrochemical feedstocks. Oil refineries generate large amounts of electricity on-site. In the U.S., over 40% (1994) of electricity in refin
15、eries are on-site generated. The cost of energy for heat and power accounts for 40% of the operating costs in the refinery!,According to the NAICS, the petroleum refineries consumed 3.1 quadrillion Btu in 2002, almost 20% of the fuel energy consumed by the U.S From the Table 35% is consumed in two d
16、istillation processes. As expected, hydrotreating is also very high, 19% alone. Units in circles are prone to be “optimized” energetically as they represent approx. 80% of the energy consumed by the refining process. We will focus on these units.,Energetic issues in an oil refinery DOE 1998,Energeti
17、c issues in an oil refinery Worrell 2005,Hydrogen generation is yet another high energy consumption process. Large amounts of energy are consumed as fuel, while the rest is basically steam.,Energetic issues in an oil refinery,Future characteristics of oil refineries in terms of energy use: Energy us
18、e is optimized throughout the refinery complex. Energy efficiency and process controls are integrated. Fouling of heat exchangers is essentially eliminated. Innovative heat exchangers are in place (all helical, vertical, no baffles) Use of cogeneration in refineries is optimized, and refineries are
19、power producers. Use of very energy-intensive processes (e.g., distillation, furnaces) is minimized. Source of heat loss (e.g., in pipes) are easily identified through monitoring.How? Identify entirely new technology. Upgrade existing inefficient technology.,Energetic issues in an oil refinery DOE 2
20、000,Energetic issues in an oil refinery DOE 2000,Replacing the conventional energy-intensive separation processes has a tremendous impact on energy consumption. Waste recovery in the short term. Fouling mitigation and new refining processes in the mid and long terms. Membrane is the first step. Cata
21、lytic distillation is in the mid run. Long run: distillation beyond membrane. Pelegrino 1999 say the target is 15-20% energy reduction for U.S. refineries.,Outline,A vision for the future A simple guide to oil refining Energetic issues in an oil refinery Thermodynamic analysis and measures to improv
22、e energy consumption. Crude oil distillation (atmospheric and vacuum) Fluid catalytic cracking Catalytic hydrotreating Catalytic reforming Alkylation Separation processes Recap and future directions References,Thermodynamic analysis DOE 2006,Remember the 5 processes with the largest energy consumpti
23、on? A thermodynamic analysis of these 5 processes is performed. Three measures are defined:TW = Theoretical Work: The least amount of energy that a process would require under ideal conditions. CW = Current Work: Energy consumed under actual plant conditions. PW = Practical Work: Minimum energy requ
24、ired to run the process in real-world, non-standard conditions by applying cutting edge technologies still on the drawing board.By applying these state-of-the-art technologies the maximum potential for energy savings can be quantified by,PI (Potential Improvement) = CW (Current Work) PW (Practical W
25、ork),Crude oil distillation (atmospheric and vacuum),Atmospheric distillation:It is the heart of the refinery. It produces a range of products, from LPG to heavy crude residue. High temperature (bottom 600oC), low pressure (near atmospheric) process.Vacuum distillation:It has heavy crude (high boili
26、ng point) as feedstock. It must then be conducted at vacuum conditions. It produces light and heavy gas oil and asphalt (or resid). These products are upgraded.,Crude oil distillation (atmospheric and vacuum),Crude oil distillation (atmospheric and vacuum),Atmospheric distillation energetic assessme
27、nt DOE 2006:Theoretical work = 22 x 103 Btu/bbl feed Current work = 109 x 103 Btu/bbl feed Practical work = 50 x 103 Btu/bbl feed Potential improvement = 59 x 103 Btu/bbl feedThe potential improvement can be achieved by (Gadalla 2003a, Gadalla 2003b, ANL 1999, TDGI 2001, Liporace 2005, Seo 2000, Riv
28、ero 2004, Yeap 2005, Hovd 1997, Sharma 1999) Control of fouling in the crude preheat train and fired heater. Improved heat integration between the atmospheric and vacuum towers. Improved tray design and heat integration between trays, and optimization of the number of trays and operating conditions
29、for improved vapor-liquid contact and higher throughput. Enhanced cooling to lower overhead condenser cooling water from 75F to 50F. Implementation of advanced control.,Crude oil distillation (atmospheric and vacuum),Vacuum distillation energetic assessment DOE 2006:Theoretical work = 46 x 103 Btu/b
30、bl feed Current work = 89 x 103 Btu/bbl feed Practical work = 54 x 103 Btu/bbl feed Potential improvement = 35 x 103 Btu/bbl feedThe potential improvement can be achieved by (Gadalla 2003a, Gadalla 2003b, ANL 1999, TDGI 2001, Sharma 1999, Liporace 2005, Seo 2000, Rivero 2004, Yeap 2005) Control of f
31、ouling in the fired heater. Improved heat integration between the atmospheric and vacuum towers. Improved tray design and heat integration between trays, and optimization of the number of trays and operating conditions for improved vapor-liquid contact and higher throughput. Enhanced cooling to lowe
32、r overhead condenser cooling water from 75F to 50F. Implementation of advanced control.,Fluid catalytic cracking,Objective: Convert heavy oils into more valuable gasoline and lighter products. Feedstocks are light and heavy gas oil from atmospheric or vacuum distillation, coking, and deasphalting op
33、erations.,High temperature, catalytic cracking reactions:,Fluid catalytic cracking,Fluid catalytic cracking,Energetic assessment DOE 2006:Theoretical work = 40 x 103 Btu/bbl feed Current work = 183 x 103 Btu/bbl feed Practical work = 132 x 103 Btu/bbl feed Potential improvement = 51 x 103 Btu/bbl fe
34、edThe potential improvement can be achieved by (Linhoff 2002, ANL 1999) Addition of a power recovery turbine. Conversion of condensing turbine drive to electric motor drive (wet gas compressor). Improved heat integration, pinch analysis. Minimization of other miscellaneous losses.,Catalytic hydrotre
35、ating,Objective: Remove sulfur, nitrogen, and metals and upgrade heavy olefinic feed by saturation with hydrogen to produce paraffins. It commonly appears in multiple locations in a refinery (5 or more of these units). They are usually placed upstream of units where catalyst deactivation may occur.
36、Typically we can distinguish: Naphtha hydrotreater, kerosene hydrotreater, and gas oil hydrotreater. Main reactions:,Catalytic hydrotreating,Catalytic hydrotreating,Energetic assessment DOE 2006:Theoretical work = 30 x 103 Btu/bbl feed Current work = 81 x 103 Btu/bbl feed Practical work = 55 x 103 B
37、tu/bbl feed Potential improvement = 26 x 103 Btu/bbl feedThe potential improvement can be achieved by (ANL 1999, Gary 2001, Linhoff 2002, Liebmann 1998) Improved pre-heater performance. Improved catalyst. Improved heat integration, pinch analysis. Minimization of other miscellaneous losses.,Catalyti
38、c reforming,Objective: Convert naphthas and heavy straight-run gasoline into high-octane gasoline blending components and hydrogen production. It essentially restructures hydrocarbon molecules to increase the octane of motor gasoline. Main reactions: Dehydrogenation of naphthenes to aromatics: Methy
39、lcyclohexane Toluene + 3H2 Methylcyclopentane Cyclohexane Benzene + 3H2 Dehydrocyclization of paraffins to aromatics: n-Heptane Toluene + 4H2 Isomerization: n-Hexane Isohexane Methylcyclopentane Cyclohexane Hydrocracking: n-Decane Isohexane + nButane,Catalytic reforming,Catalytic reforming,Energetic
40、 assessment DOE 2006:Theoretical work = 79 x 103 Btu/bbl feed Current work = 264 x 103 Btu/bbl feed Practical work = 203 x 103 Btu/bbl feed Potential improvement = 61 x 103 Btu/bbl feedThe potential improvement can be achieved by (ANL 1999, Gary 2001, Packinox 2003) Improved feed and interstage proc
41、ess heater performance (e.g., improved convection section heat recovery). Replace horizontal feed/effluent heat exchangers with vertical plate and frame exchanger. Improved equipment efficiency (e.g., recycle and net gas compressor, reactor product air cooler). Additional process cooling to improve
42、light ends recovery (vapor compression vs. ammonia absorption). Minimization of other miscellaneous losses.,Alkylation,Objective: Produce branched paraffins that are used as blending components in fuels to boost octane levels without increasing the fuel volatility. There are two alkylation processes
43、: sulfuric acid-based and hydrofluoric acid-based. Both are low-temperature, low-pressure, liquid-phase catalyst reactions. Main reaction:,Alkylation (H2SO4 process),Alkylation (H2SO4 process),Energetic assessment DOE 2006:Theoretical work = -58 x 103 Btu/bbl feed Current work = 250 x 103 Btu/bbl fe
44、ed Practical work = 156 x 103 Btu/bbl feed Potential improvement = 94 x 103 Btu/bbl feedThe potential improvement can be achieved by (Gadalla 2003a, TDGI 2001, DOE 2006, Schultz 2002) Improved compressor efficiency, from 25% to 50%. Improved heat integration, pinch analysis. Use of a dividing wall c
45、olumn design or other advanced separation technology. Upgraded control system.,Summary,As expected, crude distillation (atmospheric and vacuum) has the largest potential for savings. Followed by alkylation and catalytic treatments. Note that separation sections are also included in the conversion pr
46、ocesses. As a general potential improvement, I particularly would also include assessment of the control structure design of the refinery.,Outline,A vision for the future A simple guide to oil refining Energetic issues in an oil refinery Thermodynamic analysis and measures to improve energy consumpt
47、ion. Crude oil distillation (atmospheric and vacuum) Fluid catalytic cracking Catalytic hydrotreating Catalytic reforming Alkylation Separation processes Recap and future directions References,Separation processes,The majority of the available literature is related to the issue concerning distillati
48、on and they are heavily concentrated in the atmospheric and vacuum columns. I bet you know the reason! Future solutions for improving energy efficiency in separation processes in oil refineries are basically related to: Membrane technology. Fouling mitigation. Advanced process control and optimizati
49、on. Heat integration. Design of efficient separation systems. What follows are mostly on the drawing board, i.e., no real-world implementation.,Separation processes,Membrane technology: Wauquier 2000 discusses that membrane technology is still an infant in the world of grown-up inefficient processes
50、 in the oil industry. Its main application is in hydrodesulfurization processes in catalyst hydrotreating units, replacing existing separation processes with energy savings up to 20%. Nevertheless, Goulda 2001 and White 2000 claimed a fuel reduction of 36,000 bbl/year (or 20% w.r.t. the conventional
51、 process) by adding a membrane unit in the dewaxing unit to recover part of the solvent stream. The membrane is selective to the solvent from the solvent/oil/wax mix. According to Szklo 2007, further research is needed to develop appropriate membrane materials that can withstand the harsh conditions in petroleum refining processes.,
