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

BP’s Energy Efficient TechnologyBP’s Energy Efficient Technologyfor the Production of Para-Xylenefor the Production of Para-Xylene

BP is now offering its proven and optimized para-xylene technology

for license exclusively through

Lummus Technology

OutlineOutline

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

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OutlineOutline


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BP-LummusBP-Lummus

• BP– 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

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BP pX TechnologyBP 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

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Typical BP pX Technology

Scope

Typical pX Aromatics ComplexTypical pX Aromatics Complex

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HydrotreatedNaphtha

C8+ HeavyReformate

C5

C6-C7 Raffinate

Benzene

Pygas

From Heavies Col

pX ProductC9-C10

C10+

To TolueneConversion

XyleneIsomerization

Catalytic Reformer

Para-xyleneRecovery

TolueneConversion/

Transalkylation

Aromatics Extraction

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BP-Lummus Technology SectionsBP-Lummus Technology Sections

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Isomerization Fractionation Recovery

HydrogenHeavy Reformate /

Mixed XylenesBy-products

pX

pX Lean Recycle

BP-Lummus Technology SectionsBP-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

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Fractionation for BP Crystallization ProcessFractionation for BP Crystallization Process

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Light AromaticsBy-product

Heavy AromaticsBy-product

Sidedraw Aromatics toCrystallizationSection

Fresh Mixed Xylenes Feed to Stabilizer/Xylene Splitter

From IsomSection

Vent

Fractionation for BP Crystallization ProcessFractionation 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

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Fractionation for Selective Adsorption ProcessFractionation for Selective Adsorption Process

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XyleneSplitter

MixedXylenes

Light Ends

H2

DeheptColumn

SA Isom

Heavies [C9+]

pX

Drawback of Fractionation for SA ProcessDrawback 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 (90-120 psig) for xylene splitter– Required for heat integration with several other columns– Increases capital investment

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BP Fractionation vs SA FractionationBP Fractionation vs SA Fractionation

BP Fractionation 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

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pX Recovery Process OptionspX 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

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BP Crystallization TechnologyBP 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

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Crystallization FeaturesCrystallization 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.

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BP’s First Generation Crystallization TechnologyBP’s First Generation Crystallization Technology

(1967)(1967)

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Stage 1 Stage 2

2nd

Step

- 73 F

2nd

Step

- 73 F

CentrifugeCentrifuge

Feed FromFractionation

Raffinate toIsom

RejectCakeMelt

CakeMelt

EthyleneRfrg

Propane Rfrg

pX Product

Cake Wash

Reject

Advances in Modern BP CrystallizationAdvances 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

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BP Crystallization vs Selective AdsorptionBP Crystallization vs Selective Adsorption

BP Crystallization 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

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Recovery Section ComparisonRecovery Section Comparison

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– 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

– 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 100 469 97 1.58

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Xylenes Isomerization and EB ConversionXylenes 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

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BP Xylenes Isomerization and EB ConversionBP 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

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• 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 IsomerizationBP’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

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Overall Energy ComparisonOverall 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

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Overall Energy for BP Crystallization ProcessOverall Energy for BP Crystallization Process

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0.22

0.42

Xylene Recovery Column

0.36

0.42

0.22

Total = 1.0

BP Crystallization: Relative Energy Consumption

Overall Energy for Selective Adsorption Overall Energy for Selective Adsorption ProcessProcess

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Xylene Splitter

Stabilizer

1.85

0.22

Selective Adsorption: Relative Energy Consumption

Total = 2.1

Variable Cost of UtilitiesVariable Cost of Utilities

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Basis:Southeast Asia, ChinaFuel @ $30 per MMkcalElectric power @ $0.08 per kWh

Fuel$/MT pX

Power$/MT pX

Total$/MT pX

BP Crystallization

Base Base Base

Selective Adsorption

Base + $36 Base - $16 Base + $20

Overall Energy Cost

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Other Advantages of BP TechnologyOther 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%+)

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OutlineOutline

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

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SummarySummary

• BP now offering its highly optimized pX technology for license through Lummus Technology

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• 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

Date post:	17-Dec-2015
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BP’s Energy Efficient Technology for the Production of Para-Xylene.

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