BP’s Energy Efficient Technology for the Production of Para-Xylene

Name: BP’s Energy Efficient Technology for the Production of Para-Xylene
Uploaded: 2017-06-28T07:58:00+00:00
Duration: PTM20S10
Channel: Bryan Jenkins
Description: BP’s Energy Efficient Technology for the Production of Para-Xylene

BP’s Energy Efficient Technology for the Production of Para-Xylene

BP is now offering its proven and optimized para-xylene technology for license exclusively through Lummus Technology

Outline BP-Lummus Para-xylene (pX) Aromatic Complex
Overall Process Scheme Fractionation BP Crystallization Xylenes Isomerization and EB Conversion Overall Energy Comparison Technology Benefits Summary

BP-Lummus BP Lummus Technology World’s second largest producer of pX
10% of world production of pX 3 million MTA capacity at 3 different sites Vast pX technology know-how Lummus Technology Licenses over 75 proprietary processes Design, engineering and project execution strengths Technology improvement skills and resources Worldwide marketing and technical service reach Worldwide, exclusive licensing rights for the BP pX technology

BP pX Technology Uses crystallization process for pX separation
Utilized in own pX units for over 40 years Incorporates many advances and unique, demonstrated design features Offers significant energy consumption savings over competing technologies Requires no proprietary equipment Utilizes a non noble metal catalyst Used internally only by BP so far, now licensed through Lummus

Typical pX Aromatics Complex
C6-C7 Raffinate From Heavies Col Benzene Toluene Conversion/ Transalkylation Benzene Column Toluene Column Hydrotreated Naphtha Aromatics Extraction Pygas Reformate Stripper Catalytic Reformer Typical BP pX Technology Scope Para-xylene Recovery Xylene Isomerization pX Product C8+ Heavy Reformate Xylene Column C9-C10 To Toluene Conversion Deheptanizer Heavies Column C10+

BP-Lummus Technology Sections
Isomerization Fractionation Recovery Hydrogen Heavy Reformate / Mixed Xylenes By-products pX pX Lean Recycle

BP-Lummus Technology Sections
Fractionation Separates light [C7-] and heavy [C9+] aromatics from xylenes [C8s] in mixed xylenes feed C8s are fed to pX recovery section pX recovery via BP crystallization pX is recovered as 99.8%+ product Other xylene isomers (oX/mX) and EB are fed to xylenes isomerization/EB conversion section Xylenes isomerization / EB conversion oX and mX isomerized to pX up to equilibrium composition EB is converted to benzene (primarily), toluene, xylenes and by-products Reactions consume hydrogen

Fractionation for BP Crystallization Process
Vent Light Aromatics By-product Stabilizer / Xylene Splitter Sidedraw Aromatics to Crystallization Section From Isom Section Fresh Mixed Xylenes Feed to Stabilizer/Xylene Splitter Heavy Aromatics By-product

Fractionation for BP Crystallization Process
Single stabilizer and xylene splitter column Proprietary energy integration with isomerization section Cuts vaporization heat requirement in half Crystallization section feed purity requirements are less stringent than those for selective adsorption Lower xylene splitter reflux ratio  lower total column traffic Lower xylene splitter pressure (about 1/3rd) Hence  less energy usage and lower investment

Fractionation for Selective Adsorption Process
pX Light Ends H2 SA Isom Dehept Column Mixed Xylenes Xylene Splitter Heavies [C9+]

Drawback of Fractionation for SA Process
Separate stabilizer and xylene splitter columns Both lights (benzene, toluene) and xylenes taken as overheads, requiring high vaporization energy Stringent specification on C9+ to selective adsorber About 500 ppm Requires large energy and number of stages High pressure ( psig) for xylene splitter Required for heat integration with several other columns Increases capital investment

BP Fractionation vs SA Fractionation
Number of columns Single column Two separate columns Operating Pressure Base Base x 3 Feed specification for recovery section Much less stringent Very stringent for SA molecular sieve Heat integration Proprietary scheme with isomerization section that further minimizes reboiling requirement High pressure required to supply heat duty for SA section columns These features contribute to lower overall energy usage in the BP pX technology compared to SA process

pX Recovery Process Options
Heart of pX technology is recovery section Separates pX from other C8 aromatics (oX, mX and EB) present in a mixed xylenes feedstock Two commercially proven technologies Crystallization Selective adsorption Crystallization introduced in 1960s Selective adsorption introduced in 1970s Only technology licensed in recent years BP crystallization technology was not available for license (but now it is) Licensed crystallization applications limited to high pX feedstock in recent years Market trend expected to change with the entry of BP Technology

BP Crystallization Technology
BP (Amoco) has continuously improved its crystallization and associated technologies over 40+ years BP employs this technology in all its operating units Technology advancements made by BP provide excellent energy performance BP crystallization process has an overall lower energy consumption pX heat of fusion is about half of heat of vaporization needed for SA process Lower energy required for xylene splitter

Crystallization Features
Normal feed is near equilibrium mixture of mixed xylenes, containing about 22 wt% pX Xylene isomers are too close-boiling to separate by simple distillation Crystallization exploits large differences in freezing points of the isomers to separate pX from the others Refrigeration is utilized to crystallize pX (highest freezing point) from the other components pX solids are typically separated by centrifugation pX removal is about 65% per pass due to thermodynamic limitations related to eutectic formation Reject filtrate from crystallization is recycled to isomerization unit to convert oX and mX isomers to pX and EB to benzene, etc.

BP’s First Generation Crystallization Technology (1967)
Raffinate to Isom Stage 1 Stage 2 Feed From Fractionation 2nd Step - 73 F Ethylene Rfrg Propane Rfrg 2nd Cake Wash Step Centrifuge Centrifuge - 73 F Reject Cake Melt Reject Cake Melt pX Product

Advances in Modern BP Crystallization
Reduced refrigeration power requirements by process scheme optimization 2-Stage crystallization 1.00 Modern BP crystallization (Geel, Belgium) 0.58 Process optimization concepts implemented Eliminating crystallizers beyond first stage Eliminating energy expended in re-crystallizing first stage cake melt Optimum processing of recycle streams from product centrifuges Better heat recovery from recovery section raffinate stream

BP Crystallization vs Selective Adsorption
Thermodynamics Uses heat of fusion, which is less than half of heat of vaporization Uses heat of vaporization Separation from desorbent Not applicable Applicable – reflux ratios higher than 1 push tower energy requirement to multiples of heat of vaporization Per pass pX recovery 65% 97% Energy usage for BP crystallization lower than that for selective adsorption process Lower per-pass pX recovery is more than compensated for by overall energy savings

Recovery Section Comparison
Heat of fusion for xylenes = 0.16 GJ/MT Heat of vaporization for xylenes = 0.34 GJ/MT pX Prod, MT/H Recovery Section Feed, MT/h pX Recovery, % Net energy consumed, GJ/MT pX Cryst 100 688 66 0.51 SA 469 97 1.58 Net energy required for SA is 3 times that for crystallization Net energy for crystallization = Net energy required to cool feed 1°C above eutectic point after accounting for heat recovery Net energy for SA = Recovery section feed x Heat of vaporization

Xylenes Isomerization and EB Conversion
Xylenes isomerization (XI) section converts other xylene isomers in feed (from recovery section) to pX for next-pass recovery pX content in XI feed is ~8% and in XI effluent is at equilibrium with other isomers Ethylbenzene also partially converted Via EB deethylation to produce benzene, or Via EB isomerization to produce mixed xylenes, or Via EB transethylation to produce heavy aromatics

BP Xylenes Isomerization and EB Conversion
BP isomerization employs BP’s proprietary HSDE (High Selectivity DeEthylation) catalyst Xylene loss increases with EB conversion per pass For BP crystallization process, isomerization optimized to lower EB conversion Crystallization tolerant of EB (no worse than other isomers) Lower EB conversion  Lower xylene loss For selective adsorption, isomerization optimized to higher EB conversion EB most difficult C8 isomer to separate from pX in SA process

BP’s HSDE Catalyst for Xylene Isomerization
Non-noble catalyst (price advantage) Very low aromatic ring loss (via hydrogenation, cracking) High non-aromatic cracking (Tolerates high non-aromatics in feed) Close approach to xylenes equilibrium Cycle life > 5 years, cumulative life > 10 years Readily recovers from sulfur and other potential poisons Can be regenerated in situ in N2 and low O2 environment

Overall Energy Comparison
Total energy requirement = Sum of energy requirements for fractionation, crystallization and isomerization BP crystallization process Higher power consumption compared to SA But, much lower fuel consumption in xylene splitter Overall, far less energy consumed compared to SA technology Selective adsorption process consumes more fuel Xylene splitter consumes much higher energy to meet stringent impurity limits Also, xylene splitter operates at higher pressure to supply all energy requirements for other ISBL energy users

Overall Energy for BP Crystallization Process
BP Crystallization: Relative Energy Consumption 0.22 0.42 Xylene Recovery Column 0.36 Total = 1.0

Overall Energy for Selective Adsorption Process
Selective Adsorption: Relative Energy Consumption Xylene Splitter Stabilizer 1.85 0.22 Total = 2.1

Variable Cost of Utilities
Overall Energy Cost Fuel $/MT pX Power Total BP Crystallization Base Selective Adsorption Base + $36 Base - $16 Base + $20 Basis: Southeast Asia, China $30 per MMkcal Electric $0.08 per kWh

Other Advantages of BP Technology
Energy savings – lower CO2 emissions No proprietary equipment in the process No special chemical (such as desorbent) required for pX separation Isomerization catalyst is non-noble metal catalyst Process has low aromatic ring loss  low net raw material cost Produces pX of high purity (99.8%+)

Outline BP-Lummus Para-Xylene (pX) Aromatic Complex

Summary BP now offering its highly optimized pX technology for license through Lummus Technology Technology incorporates 40+ years of experience and advancements in all process areas Provides significant savings in variable costs through energy savings and offers many other technology advantages

BP’s Energy Efficient Technology for the Production of Para-Xylene

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