Hydrocracking

Axens hydrocracking

Excellence from innovation and experience

Processes, catalysts and services

World oil demand is primarily driven by the transportation fuelssector. Forecasts show significant growth in these fuels, while theshare of heavy fuel oil will decrease in the refined products slate.Among fuels, on-road diesel and jet fuel will exhibit the highestgrowth rates, about 2.5% per year over the period 20102020.Along with this trend, fuel specifications continue to be tightened,pushing demand towards ultra-low-sulfur, low-polyaromatics-content, high-cetane diesel.

Hydrocracking technology can respond to the most demandingmarket constraints. This flexible process is capable of converting awide variety of feedstocks into diesel and jet fuel products thatmeet the most challenging specifications. For cases whereincomplete conversion is desired, the unconverted hydrocrackedresidue (also called unconverted oil, UCO) can, because of itsexcellent properties, be used as a high-viscosity-index (VI) lube oilbase stock, as a superior steam cracker feedstock owing to its verylow BMCI* value or as an FCC feed.

High price differentials between on-road diesel/jet fuel andhydrocracking feedstocks encourage investment in hydrocrackingunits owing to high profitability and short payback times.

* BMCI: Bureau of Mines Correlation Index

Axens is an established name in hydrocracking licensing with morethan 40 years experience in all types of hydrocracking processes.

We have a large portfolio of hydroconversion processes, includingfixed- and ebullated-bed technologies. Our commercial unitsoperate at low, medium and high conversion, and in once-through, single-stage recycle and two-stage modes.

As of 2011, Axens hydrocracking technologies had been selectedfor more than 80 licensed units with a combined capacity of over3.3 MMBPSD.

Axens has a global reputation for basic engineering designexcellence. We provide both limited and extended basicengineering packages and can extend this capability upon request.

Our technical services are second to none, and include theprovision of training, catalyst loading, start-up assistance,performance monitoring, troubleshooting and processoptimization.

Conventionalcrude VGO

High-gradediesel, jet fuel

+high-VI lube

oil basesor

FCC, SC feeds

Heavy crudeVGO

Coker VGO

Visbreaker VGO

VGO ex-resid HC

DAO

Lube by-products: aromatic extracts,

paraffins

LCO, HCO

The considerable flexibility available with these technologies isenhanced by a complete line of dedicated materials covering feedpretreatment and conversion steps. Applying the right combinationof materials and process designs enables our technology torespond to a diverse set of economic and operational constraintswith various feedstocks, desired conversion levels and productselectivities. Hydrocracking objectives are achieved while ensuringlong catalyst cycle lengths and employing best practices relating tooperational, environmental and safety concerns.

Our commercial hydrocracker designs can cover a large variety offeedstocks varying from light HGO and LVGO feeds to the mostdifficult feeds, such as highly resinous and organic-nitrogen-containing VGO, processed VGO or DAO. In addition, ourhydrocracker designs are exceptionally adapted for upgrading low-quality products such as LCO, which is used as a cutter stock forheavy fuel oil. With the continuing decrease in demand for heavyfuel oil, additional low-cost LCO will be available for upgrading.

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H-OilDC, mild hydrocracker + guard bed

MHC, HyC-10

HGO, LVGO VGO, HCGO, LCODAO-C3, C4

Refractory VGODAO-C4, C5

Hytail Incre

asing

resis

tance

to hy

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HyKone-stage(once-through or recycle)two-stage

Mid

dle

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elec

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Activity

Alumina

Amorphous

Low-acidityzeolite

High-acidityzeolite

Axens technologies cover every type of feed A wide range of catalysts is available to meet specific market objectives

Mild hydrocracking and HyC-10

For refineries equipped with a VGO FCC unit, mild hydrocracking(MHC) enables increased diesel production through VGOhydroconversion. This process simultaneously improves the qualityof the treated VGO, which, once converted in the FCC unit, offershigher gasoline yields, higher octane retention, lower SOxemissions and lower-sulfur products. Under conventional MHCoperating conditions (low-to-medium pressure range, 50100 bar[7301500 psi] and 2040% conversion levels) direct productionof 10-ppm-sulfur diesel is not easily attained. Axens commerciallyproven HyC-10 technology achieves both objectives, therebyenabling diesel cut quality to be controlled independently from theVGO conversion. This has the added advantage of not puttingexcess hydrogen into the treated VGO and reducing theinvestment costs.

In addition, HyC-10 systems can be designed to co-process otherdifficult feedstocks present in the refinery such as LCO, lightcracked GO, and visbroken GO. Streams like these can exhibit highmetal or CCR values, which shorten run cycles. Axens permutableguard reactors can be installed to counteract this problem.

H2

VGO

Lights,naphtha

Low-sulfurVGO

10-ppm-sulfur

diesel tostripping

Diesel fromCDU, FCC, VB,

coker, etc.

LsV

Prime-DHDT

HyC-10 mild hydrocracking scheme

High-conversion hydrocracking (HyK)

To achieve conversion levels higher than 50% and to maximizemiddle distillate production from VGO and light DAO, Axens offersthree configurations of HyK processes: single-stage once-through,single-stage with liquid recycle, and two-stage. All thehydrocracked products, including unconverted oil (UCO), presentexcellent characteristics.

The configuration selected will depend on the desired productslate and the investment criteria. For instance, when thehydrocracking project is driven by a high diesel incentive, a two-stage full-conversion scheme provides maximum production ofexceptional-quality diesel.

Single-stage once-through hydrocracker

Two-stage hydrocracking scheme

Hydrotreatment

Naphtha

FG+LPG

H2

Feed Hydrocracking

Hydrocracking

H2

H2

Kerosene

Diesel

Bleed

H-OilDC

For the most refractory feeds, including heavy VGO and DAO-containing feeds, the H-OilDC ebullated-bed technology is suitablefor deep-conversion objectives. Conversion levels of over 80% areachievable by adjusting operating temperature, residence time andcatalyst replacement rate. Recycling of unconverted VR to a solventdeasphalting unit enables nearly full conversion of the DAO. Theaddition of an integrated hydrotreater on the H-OilDC distillatefraction ensures ultra-low-sulfur-diesel quality.

H-OilDC and Solvahl (solvent deasphalting) combine for nearly 100%

conversion of heavy DAO

SolvahlC4C5

VR DAOLight ends

H-OilDC

H2

Asphalt pitch

Recycled VR

VGO

GasolineDieselVGO

Our new-generation commercial hydrocracking catalysts treat awide range of feeds to produce a diverse slate of products thatrespond to specific quality targets.

For high conversion hydrocracking applications, the combination ofHRK, HDK and HYK series is definitely the best solution to squeezemore middle distillates from heavy ends while reaching highconversion levels.

A once-through HyK hydrocracker operating with straight-runVGO at 80% conversion (see figure right) would typically beloaded with: several sets of EquiFlow reactor internals; different ACT materials; HF / HMC Series demetallization catalyst; the winning combination of HRK Series + HDK Series + HYKSeries and;

HR Series catalyst to ensure optimal product quality.

Grading materials and reactor internals

For fixed-bed hydrocracking processes, ultimate performance ofthe technology begins with feed pretreatment and a design thatprovides near-perfect liquidgas distribution throughout theprocess.

Axens EquiFlow reactor internals are designed and commerciallyproven to provide the industrys best fluid distribution. This ensuresthat the entire catalyst inventory is used uniformly and that thelongest catalyst cycles are attained.

Once the hydrodynamic design is established, the next step is toensure that undesirable feed materials, such as scale, polymer,other entrained solids, and highly reactive molecules do notprematurely end the operation cycle through pressure drop build-up, catalyst plugging or deactivation. To reduce the effect of thistype of frequent problem, the top bed of the unit is loaded withACT series grading materials that vary from non-porous to porous,large to small and low to high activity. Depending on the metalscontent (V + Ni) in the feed, the addition of Axens HF & HMCSeries demetallization catalysts may be required before contactwith the pretreatment catalyst to ensure long cycle lengths.

The cleaned, uniformly distributed feedstock and hydrogen arenow in the optimum condition to be catalytically hydrotreated toremove sulfur and nitrogen and then hydrocracked into lighterproducts.

High-conversion hydrocracking application

The HRK Series hydrotreating catalyst features very highdenitrogenation activity while affording deep sulfur andaromatics removal.

HDK Series fills the gap between the HRK and HYK Series forboth middle distillate selectivity and conversion activity. Thecombination of HRK Series and HDK Series is the most effectiveway to maximize HDN activity in pretreating section. Theformulation strongly orients overall selectivity toward middledistillates and affords better UCO characteristics, particularly forhigh-VI lube-oil base stocks.

HYK Series, the zeolite-based hydrocracking catalysts, displayshigh activity coupled to exceptional selectivity. HYK Seriescatalysts are well suited for the processing of heavier and morerefractory feedstocks, and their high activity enables them to beextremely tolerant to nitrogen.

Mild hydrocracking application and HyC-10 units

The proposed catalyst arrangement, combined the following highperformance products:

HR 500 series hydrotreating catalyst: a catalyst with exceptionalHDS activity as well as high HDN and HDA performance.

HDK series hydrocracking catalyst specially designed to maximizediesel production while providing higher activity.

When the FCC VGO feed is already pretreated in a catalytic feedhydrotreater (CFHT), this unit can be revamped into a MHC inorder to increase the conversion of VGO to diesel. In this case, theHR 500 series catalyst (CFHT service) is replaced by the catalystcombination: HR 500 Series + HDK Series.

H-OilDC

For conversion applications with the most refractory feeds, the H-OilDC technology associated with HTS Series catalysts providessubstantial benefits owing to its continuous and uniformoperation.

HYK seriesHRK series

HDK series

Demetallization - HF/HMC series

HDSHDN

HDAHCK

HDM

Feed

Grading ACT series

Hydrofinishing - HR series

To Separation & Fractionation

Pretreating Section Cracking Section HR Series

10

20

30

40

Reactor Temperature (C)

Net Conversion (wt%)

HR Series

50 HR Series +HDK Series

HDK series

HDA + HCK

HDS + HDN

EquiFlow quench boxes provide optimal remixing of the effluentsbetween beds. These devices are particularly useful when hotproduct from the previous bed is mixed with fresh, coolerhydrogen. They provide the mixture with a uniform temperaturebefore it makes contact with the subsequent bed. Forhydrocracking applications in which highly exothermic reactionsoccur, compact EquiFlow quench boxes provide near-perfect flowperformance and higher catalyst loading, which lead to substantialactivity gains and margins improvements. The figure below showsthe improvement in the temperature profile of the mixture as itexits the quench box: red and blue indicate high and lowtemperatures, green and yellow show temperatures close to theideal mix temperature.

Hydrocracking reactor performance is determined by both thecatalysts and the reactor internals. For fixed-bed reactors, EquiFlowinternals ensure uniform liquidgas flow distribution in the catalystbeds. This facilitates effective utilization of the entire catalystinventory and minimizes radial temperature gradients, which canresult from non-ideal flow. The images below show the efficiencyof EquiFlow distributor trays. The yellow, light blue and green areasindicate the desired fluid flux, whereas dark blue indicates fluidflux that is too low and red too high.

Conventional chimney tray

Tomographic cross-section image at 0.5m from top of bed

EquiFlow, the latest generation of commercial distributors

Low HighFluid flux Low HighFluid flux

EquiFlow

a. Conventional design b. EquiFlow design

Quench-box outlet (viewed from below)

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Moscow +7 495 933 65 73New Delhi +91 11 43399000Tokyo +81 335 854 985

Axens Headquarters - France +33 1 47 14 21 00

information@axens.net

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