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 the motor fuels, on-road diesel and kerosene will exhibit thehighest growth rates, about 3% and 2% per year respectively overthe period 2006–2020. Along with this trend, fuel specificationscontinue to be tightened, pushing demand towards ultra-low-sulfur,low-polyaromatics-content, high-cetane diesel. As a result, therefining industry will be increasingly challenged by the need toproduce higher volumes of high-quality middle distillates fromheavier and sourer crudes, i.e., from more refractory feeds.

Hydrocracking technology can respond to the most demandingmarket constraints. This flexible process is capable of converting awide variety of feedstocks into diesel and kerosene 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, can 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/kerosene andhydrocracking feedstocks encourage investment in hydrocrackingunits owing to high profitability and short payback times. As a result,it is expected that more hydrocracking units will come on-stream inthe next decade than in any previous decade in refining history.

* BMCI: Bureau of Mines Correlation Index

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

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

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

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.

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.

Rec

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pro

cess

H-OilDC, mild hydrocracker + guard bed

MHC, HyC-10

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

Refractory VGODAO-C4, C5

Hytail Increasin

g resistance

tohyd

roprocessing

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

Mid

dle

dis

tilla

tese

lect

ivit

y

Activity

Alumina

Amorphoussilica alumina

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 quality ofthe treated VGO, which, once converted in the FCC unit, offers highergasoline yields, higher octane retention, lower SOx emissions andlower-sulfur products. Under conventional MHC operating conditions(low-to-medium pressure range, 50–100 bar [730–1500 psi] and 20–40% conversion levels) direct production of 10-ppm-sulfur diesel isnot easily attained. Axens’ commercially proven HyC-10 technologyachieves both objectives, thereby enabling diesel cut quality to becontrolled independently from the VGO conversion. This has theadded advantage of not putting excess hydrogen into the treatedVGO and reducing the investment costs.

In addition, HyC-10 systems can be designed to co-process otherdifficult feedstocks present in the refinery such as LCO, light crackedGO, and visbroken GO. Streams like these can exhibit high metal orCCR values, which shorten run cycles. Axens’ permutable guardreactors can be installed to counteract this problem.

H2

VGO

Lights,naphtha

Low-sulphur

VGO

10-ppm-sulfur

diesel tostripping

Diesel fromCDU, FCC, VB,

coker, etc.

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 UCO, present excellentcharacteristics.

The configuration selected will depend on the desired product slateand the investment criteria. For instance, when the hydrocrackingproject is driven by a high diesel incentive, a two-stage full-conversion scheme provides maximum production of exceptional-quality diesel.

Single-stage once-through hydrocracker

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

conversion of heavy DAO

Two-stage hydrocracking scheme

SolvahlC4–C5

VR DAOLight ends

H-OilDC

H2

Asphalt pitch

Recycled VR

VGO

GasolineDieselVGO

Hydrotreatment

Naptha

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 ansolvent deasphalting unit enables nearly full conversion of theDAO. The addition of an integrated hydrotreater on the H-OilDCdistillate fraction ensures ultra-low-sulfur-diesel quality.

For fixed-bed hydrocracking processes, the ultimate performanceof the technology begins with the feed pretreatment and a designthat provides near-perfect liquid–gas distribution throughout theprocess.

Axens’ EquiFlow reactor internals are designed and commerciallyproven to provide the industry’s best in fluid distribution. Thisensures that the entire catalyst inventory is used uniformly and thatthe longest 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 HDMdemetallization catalyst may be required before contact with thepretreatment catalyst.

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.

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

All the catalysts employed for hydrocracking take advantage ofAdvanced Catalytic Engineering (ACE™) technology, which wasfirst implemented in our manufacturing in late 2003. Thetechnology offers a highly controlled preparation method thatinfluences active site formation and leads to improved activity,particularly HDN activity.

For MHC and HyC-10 applications, the most commonconfigurations rely on a combination of the HR 548 hydrotreatmentand HDK 776 conversion catalysts. For lower conversion levels, theamorphous catalyst HDK 776 may be unnecessary.

When medium to high conversion levels are the objectives,HRK 558 is the hydrotreatment catalyst of choice. Depending onthe desired selectivity and the feedstock quality, the hydrocrackingservice is obtained using HDK 776 alone or in combination with thezeolite-based catalyst HYK 742 or an HYC series catalyst.

For conversion applications with the most refractory feeds,the H-Oil technology provides substantial benefits owing to itscontinuous and uniform operation. Two specific ebullated-bedcatalysts are available for this service: HTS 358 for difficultVGO-based fuels and HTS 458 for DAO-based feeds.

A once-through HyK hydrocracker operating with straight-run VGO at80% conversion would typically be loaded with several sets ofEquiFlow reactor internals; three to five different ACT materials;HMC 868 and HF 858 demetallization catalyst; HRK 558; HDK 776; acombination of zeolite hydrocracking catalysts; and HR 516 to ensureoptimal performance in terms of run length and product quality (seefigure right).

• ACT top-bed grading materials are employed to eliminate potentialproblems caused by feed impurities. ACT materials guarantee thebest in pressure drop management.

• The use of HMC 868 and HF 858 catalyst depends on the quantityof metals in the feed, but is generally incorporated in the catalystinventory to ensure long cycle lengths.

• The hydrotreating catalyst HRK 558 features very highdenitrogenation activity while affording deep sulfur and aromaticsremoval.

• The amorphous-type hydrocracking catalyst HDK 776 provides highcracking activity and excellent diesel selectivity while ensuringultimate nitrogen removal. The formulation strongly orients overallselectivity toward middle distillates and affords better UCOcharacteristics, particularly for high-VI lube-oil base stocks.

• The zeolite-based hydrocracking catalyst HYK 742 exhibits very highactivity and has the ability to achieve full conversion, even withrefractory feedstocks.

• Typically, the catalyst inventory terminates with a fraction of HR 516to ensure that the sulfur content in the light products remains onspecification throughout the operation cycle.

The product quality remains excellent throughout the cycle, with nonoticeable change in diesel cetane number or kerosene smoke point.

PDM*

Feed

To separationand fractionation

*Pressure drop managementOptimum cycle lengthOptimum middle distillate yieldsOptimum product qualities

HYK 742 or HYC series

HR 516

ACT

HMC 868 & HF 858

HRK 558

HDK 776

HDM

HDS

HDN

HDA

HCK

Hydrocracking reactor performance is determined by both thecatalysts and the reactor internals. For fixed-bed reactors, EquiFlowinternals ensure uniform liquid–gas 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 greenareas indicate the desired fluid flux, whereas dark blue indicatesfluid flux that is too low and red too high.

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.

Conventional chimney tray

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

EquiFlow, the latest generationof commercial distributors

Low HighFluid flux Low HighFluid flux

EquiFlow

a. Conventional design b. EquiFlow design

Quench-box outlet (viewed from below)

As of 2006, Axens’ hydrocracking technologies had been selected forabout 60 licensed units with a combined capacity of over 2.1 MMBPSD.

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

Our technical services are second to none, and include the provisionof training, catalyst loading, start-up assistance, performancemonitoring, troubleshooting and process optimization.

Axens is a non-aligned pure technology company. We stand by ourtechnologies and products. Improving our customers’ performance isour only business.

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1965 1970 1975 1980 1985 1990 1995 2000 2005

World total: 57 licenses

Total capacity: 2,140,000 BSPD

Axens hydrocracking technologies weigh inwith the right products: clean, high-cetanemiddle distillates from heavy oil fractions.

HyK (high kay) does for middle distillateswhat Prime-G+ does for gasoline; it deliversthe highest-quality products based onoperational best practices, grading materials,

catalysts and reactor internals combined withunparalleled basic engineering design excellenceand technical services.

Improving your performance with the mosteffective refinery solutions is our only business.

Axens – the quality fuels technology provider.

Single source technology and service providerISO 9001 - ISO 14001 - OHSAS 18001

www.axens.net

HyK™ hydrocrackingtechnologies to lighten up

your heavy endsHydrocracking-03/2009/1000-Photos

Axens-BlueMind