SlideShare a Scribd company logo
Choosing a hydroprocessing scheme

         A systematic approach to selecting hydroprocessing technology meets process
         objectives with optimal operating and capital costs

         AlpesH GurjAr
         Fluor Daniel India




H
        ydroprocessing technologies        reduce nitrogen and aromatic              (RDS), should be flexible enough to
        are well established in the        content, and enhance cetane number,       process a wide range of feed
        refining industry for the          API gravity and smoke point.              qualities, of diverse origin, at
production of clean fuels. However,        Hydroprocessing of middle distil-         different conversion levels.
increased competition within the           lates also plays a key role in
industry mandates a greater focus          improving cold flow properties such       Basis of technology evaluation
on awareness of the right tech-            as pour point, cloud point and cold       All technologies work well within a
nology and catalysts to achieve the        filter plug point. This enables           specific context and under certain
products and performance needed            refiners to meet the stringent            conditions. The total investment
in the market.                             product specifi-cations determined        costs for a hydroprocessing unit
  For refiners to sustain their profit     by regulatory bodies.                     increase with unit size, feedstock
margins, economical access to state-          The established refinery configur-     sulphur, nitrogen and quantity of
of-the-art technology is a must.           ation includes a minimum of three         cracked stocks. The evaluation of
Refinery management needs to plan          or four hydroprocessing units for         new technology should be based on
for the future to maintain long-           upgrading light, middle and heavy         detailed technical and economic
term growth, maximise asset                                                          analysis.
performance, formulate an effective                                                     The total on-site capital cost
response to changing environ-              The total investment                      estimate for a new hydrotreater unit
mental legislation and incorporate                                                   varies, depending on the licensed
sufficient flexibility to withstand        costs for a                               and proprietary technology. The
business cycles while crude supplies                                                 overall system can be broadly
are becoming increasingly heavy
                                           hydroprocessing                           classified in three parts: a reactor
and sour. Increased operational            unit increase with                        system, hydrogen make-up/recycle
excellence is a priority for refineries,                                             gas compressor and other separation
which leads refiners to look at more       unit size, feedstock                      equipment. The cost of the reactor
innovative ways of maintaining                                                       system and compressor depends on
reasonable margins in new projects,        sulphur, nitrogen and                     the percentage of cracked stock
to quickly recover the investments                                                   present in the hydrotreater feed. The
they have made and to justify              quantity of cracked                       cost of the separation equipment is
additional investment to cope with                                                   a function of unit capacity. The basic
a changing market.                         stocks                                    difference in the capital costs of a
  Hydrotreating, the workhorse of                                                    unit at a given capacity level is
the refinery, serves to meet several       distillates. Upgrading light distillate   the result of variations in the
significant product quality specifi-       involves the use of proven                fractions of the different types of
cations.     Increasingly     stringent    technology for the desulphurisation       feed; for example, straight-run vs
regulations for fuel (for instance,        of FCC naphtha with minimum               cracked stock and the sulphur level
10–15 ppm sulphur in diesel and            octane loss, as this stream contri-       of the feed as well as the catalyst.
gasoline), the processing of lower-        butes significantly to the refinery          The major items of focus during
quality, higher-sulphur crudes,            gasoline pool. Upgrading middle           the evaluation of hydroprocessing
tightening site emissions standards        distillate (kerosene and diesel)          technology are process configur-
(SOx and NOx reduction), and rising        focuses on managing hydrogen and          ation, reactor operating conditions,
gasoline and diesel consumption are        energy consumption, while produc-         number and size of high-pressure
all factors that make significant          ing ultra-low sulphur products. The       items, quantity and type of catalyst
demands of a hydroprocessing unit          gas oils and residue upgrading            used, catalyst deactivation rate,
in a refinery. In addition, a hydro-       technology, such as hydrocracking         make-up hydrogen purity and
processing unit helps refiners to          and residual oil desulphurisation         design pressure level, depending


www.eptq.com                                                                                                      PTQ Q1 2010 71
on the product quality requirements.       sulphur and nitrogen compounds in        process severity/variables
     In determining the compatibility of        a feed depends on the feedstock’s        A key factor to be considered in
     the licensor’s technology with             boiling range, prior processing          establishing an effective hydro-
     existing facilities it is essential to     history (whether         thermally or    processing technology is the level of
     check its capability with regard           catalytically cracked) and the crude     conversion required for achieving
     to variations in feed qualities and        oil type from which it is derived.       the desired objective. This level of
     the effect of product slate for            The olefin content associated with       conversion effectively sets the level
     blending.                                  cracked stock gives an idea of           of process severity required, from
       The key process objectives to            anticipated       exotherms,       the   mild hydrofinishing for removing
     define in order to establish a             configuration of efficient quenching,    contaminants such as sulphur and
     transparent and consistent evalu-          heat recovery and the separation         nitrogen containing compounds, to
     ation methodology are:                     system. It also enables a refiner to     complex molecular reconstructions
     • Desired function of the hydro-           choose a reactor catalyst bed            associated with hydrocracking and
     processing unit in the refinery, such      arrangement. The aromatic content        aromatic saturation reactions. The
     as hydrodesulphurisation (HDS),            of a feed and its saturation             operating conditions of a hydro-
     hydrodenitrification (HDN), olefin         requirements fixes the partial           processing unit are a function of
     saturation, aromatic saturation and        pressure of a distillate hydrotreating   feedstock characteristics based on
     metals removal                             unit, which plays an important           origin. The operating and capital
     • Feed and product specifications          role in the operating and capital        cost of the unit increases with the
     • Minimum catalyst cycle length            cost of the unit. The prediction of      severity of the unit. The proper
     • Hydrogen utilisation                                                              combination of process parameters
     • Availability of the unit (on-stream                                               should be in accordance with the
     operating factor per year)                 The prediction of                        optimal use of hydrogen and the
     • Unit turndown capacity.                                                           available utilities, such as fuel,
                                                unit dynamics caused                     cooling water and steam. The key
     Criteria for selecting technology                                                   process variables are liquid hourly
     No single process technology               by feed quality                          space velocity (LHSV), hydrogen
     solution can be applied to all                                                      partial pressure, temperature and
     refineries because of their widely         changes is of prime                      gas-to-oil ratio.
     different configurations and objec-
     tives. A comprehensive, site-specific
                                                importance during                        liquid hourly space velocity
     study is needed to identify the most
     suitable process scheme under
                                                the design phase of                      LHSV is a measure of the residence
                                                                                         time in the reactor. The lower the
     given scenarios. The evaluation            the unit                                 LHSV, the higher the residence time.
     should be based on the criteria                                                     The lower the LHSV, the bigger the
     developed and approved by project                                                   reactor and the higher the capital
     management and the client during           unit dynamics caused by feed             cost. Typically, the LHSV require-
     the planning phase.                        quality changes is of prime              ment depends on the boiling range
       Technical evaluation of a licensor’s     importance during the design phase       of the hydrocarbons. A heavy feed
     technology is of prime importance          of the unit.                             contains higher amounts of sulphur
     when it comes to customising its                                                    and nitrogen impurities with a
     unique features, amplifying its            process chemistry                        complex ring structure. The removal
     reliability, flexibility and operational   An understanding of the chemistry        of such compounds requires more
     performance, and so meet current           involved in the removal of sulphur       residence time in a reactor and
     needs and future requirements.             and nitrogen compounds is essential      therefore lower LHSV. LHSV can be
     The key points that significantly          when defining the operating              adjusted by either reducing the feed
     influence the hydroprocessing unit’s       severity, based on varying relative      throughput, which is not economical,
     process design follow.                     rates of reactions of different com-     or by the addition of a new reactor
                                                pounds. Desulphurisation, denitrifi-     or more catalyst in the same reactor,
     Feed characterisation                      cation and olefin saturation are         which requires substantial capital
     Good feedstock characterisation,           kinetically controlled reactions.        investment. An optimal design is
     including off-design variations, is        Increasing the process severity, such    usually one that takes advantage
     essential for the proper selection of      as raising the temperature, usually      of a higher-activity, commercially
     catalyst, reaction conditions and          allows these reactions to approach       proven catalyst to set reactor catalyst
     process configuration. A study of          near complete conversion. However,       volumes and pressure levels for a
     feedstock at the micro level provides      the aromatic saturation reaction is      target run length. Figure 1 shows
     a thorough understanding of                thermodynamically limited, so a          the effect of a decrease in LHSV on
     feedstock     reactivity   and    the      careful balancing of kinetic and         polyaromatic saturation levels.
     subsequent processing conditions           thermodynamic       equilibrium     is
     needed to meet process objectives.         required when deciding on pressure       Hydrogen partial pressure
     The distribution and nature of             level and catalyst volume.               The type of feed to be processed,


72   PTQ Q1 2010                                                                                                      www.eptq.com
product quality requirements, yield        span, and so will benefit from a             activity. There is a minor boost in
    and the amount of conversion for a         longer     run,    increased      unit       hydrogen partial pressure as well
    specific catalyst cycle life determine     throughput or the ability to process         with increasing gas circulation rates.
    the hydrogen partial pressure              a challenging feed mix. The                  However, above a certain gas rate,
    required for the operation of a            operating temperature should be              the increase in hydrogen partial
    hydroprocessing unit. The hydrogen         high enough to facilitate faster             pressure will be relatively small and
    partial pressure must be high              kinetic reaction rates, but not so           incur extra heating and cooling
    enough to accomplish the desired           high as to promote undesirable side          costs.
    level of denitrification and partial       reactions or to exceed the metal-               In addition to affecting hydrogen
    saturation of heavy aromatic               lurgical limits of high-pressure             partial pressure, the gas rate is
    molecules.     At     higher     partial   vessels.                                     important because it acts to strip
    pressures, the desulphurisation and          As the end point of hydrocarbon            volatile products from the reactor
    denitrification process is “easier”;       feed increases, there is an increase         liquids, and thus affects the
    however, the unit becomes more             in the concentration of recalcitrant         concentration of various components
    expensive because of the need for          sulphur and nitrogen species in the          in the reactive liquid phase. It also
    thicker-walled       reactors.     The     form of dibenzothiophenes, which             maintains proper mass velocity in
    minimum         pressure       required    necessitates a higher SOR temper-            the catalyst bed, thus reducing the
    typically rises with the required          ature. For grassroots units, a higher-       possibilities of channelling in the
    severity of the unit. A higher
    hydrogen partial pressure decreases
    catalyst deactivation and, therefore,
    increases the predicted cycle length                                  Thermodynamic effects
    for a fixed quantity of catalyst.
      The importance of maintaining
    adequate hydrogen partial pressure
    increases as sulphur levels approach
    the sub-ppm level, because the
    primary HDS reaction shifts from
    a predominantly non-reversible,                                                                          Increasing
                                                                                                             pressure
    single-step reaction to a reversible,                                    Decreasing
    equilibrium-limited, two-step reac-                                      LHSV
    tion. As the unit approaches a higher               LHSV effects
    operating temperature at end-of-run
    (EOR) conditions, the lower-pressure
    unit may struggle to meet 10 wppm
    sulphur requirements because of
    the effects of thermodynamic
    equilibrium.
      At lower sulphur levels, the
    remaining species behave like
    polyaromatics and, therefore, the          Figure 1 The impact of process conditions on polyaromatic saturation
    chemistry of their removal obeys
    similar rules to the saturation of         activity catalyst may be employed            bed, and carries the reaction heat. It
    polyaromatics. Figure 1 shows that         to optimise the unit design temper-          is prudent to maintain a healthy
    an increase in total pressure/             ature and pressure requirements in           hydrogen-to-oil ratio to prevent
    hydrogen partial pressure increases        order to save capital investment.            coking and subsequent deactivation
    the absolute level of polyaromatic                                                      of the catalyst. As a guide, the
    saturation.                                Hydrogen/hydrocarbon ratio and               available hydrogen at the top of the
                                               recycle gas rate                             reactor should be two-and-a-half to
    Temperature (WABT)                         The choice of recycle gas rate is            three times the chemical hydrogen
    For most hydrotreating units, the          governed by economic consider-               consumption for easier feedstocks
    only parameter that typically varies       ations. Recycle hydrogen is used to          and three to four times the chemical
    once the unit is built is the start-of-    enable flow distribution and uniform         hydrogen consumption for cracked
    run (SOR) temperature, depending           physical contact of the hydrogen             feedstocks.
    on catalyst activity. Since the EOR        with oil-soaked catalyst to ensure
    temperature is usually fixed, based        adequate conversion and removal              Catalyst selection
    on the specification or unit               of impurities, while minimising              Hydrotreating catalysts consist of a
    hardware constraints, a higher-            carbon deposition. For high-activity         hydrogenation component dis-
    activity catalyst will help to start the   hydrotreating catalysts, there may           persed on a porous, fairly inert
    reaction at a colder temperature,          be a minimum treat gas circulation           material. For hydrotreating, catalysts
    thereby increasing the temperature         requirement to preserve catalyst             with weak acidity are used, since


74 PTQ Q1 2010                                                                                                            www.eptq.com
hydrogenation and cracking capa-
                                              HDS/HDN                                bilities, its size, shape and pore
                                             reactor with
                                             silica guard                            structure are very important, as they
               Di-olefin
               reactor                                                               govern the pressure drop, surface-
                                                                                     to-volume ratio and diffusion rate.
                             Start-up
                              heater                                                    Different shapes of catalyst are
                                                                                     often used to take advantage of their
                                                                                     high surface-to-volume ratio, while
                                                                                     still maintaining a reasonable reactor
                                                                                     pressure drop. The reaction kinetics
                                                                                     are usually diffusion limited; a small
                                                                                     catalyst with a high surface-to-
                                                                                     volume ratio has better diffusion for
                                                                                     the relatively heavy feed. The
                                                                                     pore diameter for the residuum
                                                                                     hydrotreating catalyst needs to be
                                                                                     quite large relative to a catalyst for
                                                                                     light feed. The increase in pore size
                                                                                     decreases the surface area and the
Figure 2 Naphtha hydrotreater unit co-processing cracked stocks                      catalyst activity. To overcome the
                                                                                     limitations of small vs large pore
cracking     and     the    associated      is high, a NiMo catalyst system may      trade-off, catalysts are layered to
production of light ends and lighter        be the right choice. Recent advances     increase activity; for example, large
liquid product(s) are usually               include staging or stacking both         pore-sized catalyst in the top section
undesirable. A combination of base          CoMo and NiMo catalysts within a         of the reactor, followed by smaller
metals, such as NiMo and CoMo, is           single fixed-bed reactor.                pore-sized catalyst. Typical pore
used to achieve deep HDS and HDN               Hydrocracking catalysts serve         sizes of 75–85 Å for light/heavy gas
activity. Feed composition and              dual functions, containing both          oil feed and 150–250 Å for residue
product quality requirements define         hydrogenation and cracking sites.        feed can be used.
the required chemical composition           The cracking sites are usually the
and quantity of the catalyst.               result of using a porous support of      Feed filtration
Typically, a CoMo catalyst may be           an acidic nature, such as amorphous      Feed filtration is important to
the right choice where the feed is          silica-alumina      and    crystalline   mitigate exchanger and reactor
straight-run distillate with very little    aluminosilicates or zeolites. The best   plugging. An appropriate feed
nitrogen content and the operating          choice of catalyst for a specific        filtration system can reduce the
pressure is low to moderate. On the         objective requires a particular          build of pressure drop in the
other hand, if the feed contains a          balance between the cracking and         reaction section of the unit, which
high percentage of cracked stock            hydrogenation functions.                 results in a significant reduction in
that has a significant nitrogen                In addition to the chemical nature    operating costs. A cartridge or
content and the operating pressure          of the catalyst, which dictates its      wedge wire backwash filter with 25
                                                                                     micron retention is typical for this
                                                                                     application. Cracked feeds should
                                                                                     feed the hydrotreater hot from the
                                                                                     upstream facilities or from inert gas
                                                                                     blanketed storage. The use of steam-
                                                                                     stripped feed that contains a
                                                                                     significant amount of water requires
                                                                                     the installation of a feed coaleaser
                                                                                     upstream of the feed filter. However,
                                                                  Co-current or
                                                                  counter-current    traces of water can be removed by
                                                                  AroSat reactor     using a horizontal feed surge drum
                                                                                     with      associated   water    boot,
                                                                                     eliminating the need for a coaleaser.

                                           Stripper                                  Feed heating section
         Hydrotreating                                                               This section comprises a series of
            reactor
                                                                                     heat exchangers followed by a
                                                                                     charge heater. Hydroprocessing
                                                                                     reactions are exothermic in nature.
                                                                                     The reactor feed effluent exchanger
Figure 3 ULSD unit with AroSat option                                                must recover as much heat as is


www.eptq.com                                                                                                     PTQ Q1 2010 75
economically practical to minimise
the heat input in the charge furnace
to typically less than 15–20% for
heat balance and emergency
operation. Off-design cases such as
cold start-up or loss of feed results
in a high design duty and thus a                                                                      CHPS
higher capital cost. The proper
selection of exchangers enables a
maximum recovery of heat of
reaction, minimises the probability
of leakage and increases the unit’s
reliability. If the feed to the charge
heater is a two-phase stream, to          Figure 4 For straight-run feed (naphtha hydrotreater)
avoid coking/hotspot in the charge
heater tube passes, it is recommended     the second reactor, with a stripper
to have pass balancing to maintain        in between, may be the preferred              processed using moving-bed and/
equal flow distribution. Bypassing        configuration (see Figure 3). For             or ebullated-bed reactors. Recent
the heat exchanger train should be        hydrocrackers,      depending      on         pilot work includes slurry-based
considered in the case of an              capacity, conversion and product              reactors for deep-conversion residue
uncontrollable increase in the reactor    specification targets, it may be best         hydrocracking. Multireactor systems
bed temperature when processing           to investigate two-stage reactor              consisting of moving- and/or
large amounts of cracked stocks.          systems that allow staging of the             ebullated-bed reactors integrated
                                          HDS/HDN reactions in a sour,                  with fixed-bed reactors can be used
reactor configuration                     ammoniacal environment and HDA                to process difficult feeds.
The number of reactors and their          reactions in a sweet, colder
configuration depends on factors          environment to capitalise on kinetic          reactor internals
such as catalyst volume, mass and         reaction rates.                               Reactor internals are exceptionally
volumetric flux, reactor pressure           The reactors selected for light             important for the safe, reliable and
drop, reactor dimensions and              feeds differ markedly from those              profitable operation of a hydro-
materials of construction. A typical      selected for heavy feeds. Fixed-bed           processing unit and may have a
pressure drop of about 0.7–1.5 psi/       reactors have been traditionally              major effect on reactor performance
ft of catalyst bed (SOR to EOR) is        used for light feeds. High asphaltene         in terms of catalyst utilisation
desirable to promote uniform flow         and high metal content feeds, such            efficiency and unit availability. For
through the catalyst bed to have a        as vacuum residue, are successfully           a gas-phase reaction such as naphtha
uniform radial temperature profile.
An excessive pressure drop will
increase the recycle gas compressor
power consumption and could
challenge the mechanical integrity
of the reactor catalyst support trays.
Other factors are flexibility in
fabrication and transportation from                                                                    CHPS
workshop to refinery site. In special
cases,     the    refinery’s   ground
conditions may also preclude the
installation of a single heavy weight
reactor.
  If the feed contains a high level of                                        HHPS
olefins, to avoid fouling in the heat
exchangers, in the heater and in the
top catalyst bed it is advisable to
saturate the olefins at a lower reactor
temperature. A separate olefin                                                               Intermediate
                                                                                             pressure
saturation reactor may be added                                                              break-up drum
upstream of the HDS reactor (see
Figure 2). For a unit where deep
aromatic saturation is required, a
two-stage reactor approach using
HDS/HDN catalyst in the first
reactor and a noble metal catalyst in     Figure 5 For cracked stock feed (high-severity ULSD unit)



www.eptq.com                                                                                                        PTQ Q1 2010 77
CHPS




                                                           HHPS




                                                                                                     CLPS




                                                                          HLPS




    Figure 6 Classic four-drum separation system (hydrocracker unit)

    hydrotreating, a distribution tray is        product cooling and separation           schemes ensures the efficient
    not necessary, but for a trickle-bed         A typical configuration in any           recovery of hydrogen from hydro-
    reactor, processing middle/heavy             hydrotreater includes a feed/            carbon, reduces the relief load of
    distillates, specially designed gas          effluent heat exchanger train, a large   the system and facilitates a lower
    liquid distributors to achieve small-        air-cooled heat exchanger and one,       design pressure for the downstream
    scale contacting of process gas and          two or more flash drums, depending       columns. The configuration of the
    liquid are mandatory. An ideal               on unit heat balance and hydrogen        separation system depends on the
    liquid distributor should have a             recovery requirements.                   economic balance between operating
    high distribution element density,             A straight-run feed with alumina-      and capital cost, in addition to feed
    low pressure drop, large spray               based catalyst produces fewer light      quality and hydrogen availability.
    angle, turndown flexibility and be           ends, so a single, cold, high-pressure
    easy to clean. This enables full             separator (CHPS) may be adequate         High-pressure amine absorption
    catalyst utilisation and thermal             for smaller-capacity units (see          Feed with a higher sulphur content
    uniformity across the catalyst bed,          Figure 4). If the feed contains a        results in the accumulation of H2S in
    so that the lowest possible SOR              large percentage of cracked stock,       the recycle gas loop. H2S inhibits
    temperature       is   achieved     in       which generates large exotherms in       HDS reactions and lowers the purity
    conjunction with minimisation of             a reactor catalyst bed, the use          of the recycle gas and thus the
    the catalyst deactivation rate.              of a hot, high-pressure separator        partial pressure of hydrogen. A high
       The use of robust reactor internals       (HHPS), with a gas component that        H2S concentration in the recycle gas
    improves radial temperature distrib-         will be routed to a CHPS via an air      (typically >2–3 vol%) will influence
    ution and catalyst utilisation, which        cooler/trim cooler, and a liquid         catalyst selectivity in an undesirable
    ultimately translates into a better          component routed to the stripping        way. To compensate, a higher unit
    yield, longer catalyst life and more         section, may be justified (see Figure    pressure may be needed. A high
    efficient use of limited hydrogen            5). This facilitates enhanced heat       sulphur content in the feed and
    resources. Some of the best-in-              integration and lower air cooler         ultra-low sulphur products may
    class reactor internals help to              duty, but increases the hydrogen         require an amine scrubbing system
    achieve less than 5°C radial                 loss and results in a higher capital     in a recycle gas loop to prevent H2S
    temperature spread at the bottom of          cost of the unit.                        build-up and improve catalyst
    deep catalyst beds. Additionally,              Limited resources of hydrogen          activity. The high-pressure amine
    tightly     designed    high-capacity        necessitate further separation of        absorber increases the partial
    trays and quench systems help to             HHPS liquid to a hot, low-pressure       pressure of hydrogen, which, in
    reduce reactor heights in multibed           separator (HLPS) followed by a           turns, results in lower operating and
    reactors.                                    CLPS (see Figure 6). This process        capital     costs    for   the   unit.


74 PTQ Q1 2010                                                                                                        www.eptq.com
Additionally, it increases catalyst       Hydrogen management
life, reduces hydrogen losses             Lower-purity (<85%) hydrogen
through purge and requires lower          make-up gas increases the design
power consumption in the recycle          pressure of the unit, and increases
gas compressor because of the             both the capital and operating costs
increased purity of the gas.              of the unit. A supply of high-purity
                                          hydrogen increases the partial
Gas compression system                    pressure of the hydrogen in the
The choice of recycle and make-up         reactor in conjunction with a lower
gas compressor depends on gas             total operating pressure, and so
purity. The make-up gas flow is           results in lower operating and
typically 25–40% of the recycle gas       capital costs. Additionally, it
flow. High-purity make-up gas             increases catalyst selectivity, stability
compression requires more stages.         and overall cycle length. Optimis-
The multistage reciprocating com-         ation of the hydrogen system may
pressor works well for this service.      provide additional H2 availability,
A sparing arrangement is necessary        while avoiding capital investment.
to ensure reliability and availability.   Pressure swing adsorption or semi-
The lower purity of make-up gas           permeable membrane technology
increases both the capital and            could be considered for the
operating cost of the compressor.         purification of the H2 purge and
The high purity of recycle gas            make-up hydrogen streams from
requires a lower gas circulation rate,    the catalytic reforming unit.
but the lower molecular weight of            The cascading of H2 purge streams
gas requires more head and                for use as H2 make-up streams to
potentially     more      compression     other HDT units increases the purge
stages. The recycle gas acts as a         rate for higher recycle gas purity
major heat sink in a reactor and          and is more economical. Quench
avoids      excursion      probability.   hydrogen rates between the catalyst
Typically, a centrifugal compressor       beds should be minimised consistent
is used for this service in view of its   with safe operation, the ability to
higher reliability and efficiency over    maintain the required hydrogen
a reciprocating compressor.               partial pressure and desired catalyst
                                          life.
stripping section
The stripping section of a middle         summary
distillate   hydroprocessing     unit     Hydroprocessing plays an increas-
mainly removes H2S and light              ingly important role in oil refining
hydrocarbons from the hydrotreated        and is key to the production of clean
product and stabilises the product        transportation fuels. Selection of the
to meet the flashpoint specification.     right technologies, the right combin-
If lighter components are present in      ation of high-activity catalysts,
the feed, to offload the light            appropriate reactor system arrange-
products, distillation can be carried     ment, operating conditions and
out in two steps: H2S steam stripping     advanced reactor internals provides
at a higher pressure, followed by         refiners with a range of advantages.
lower-pressure stabilising. This will     These include low operating and
increase operational flexibility and      capital costs, improved hydrogen
enable the use of a smaller column        utilisation, greater flexibility, more
size with a low design pressure.          scalability and high reliability for
   Use of heavy feed and less             the processing of a range of
cracking in the reactor means a           feedstocks.
standalone, low-pressure stripper
                                          Alpesh Gurjar is an Associate Process
column can be employed. It may be
                                          Specialist at Fluor Daniel India Pvt Ltd. He
one of two types: attached fired          has six years’ experience in process design,
reboiler or steam stripping. For          technical services and operation of various
kerosene and diesel boiling-range         refinery hydroprocessing units. He has worked
hydrocarbon, a fired heater reboiler      with Essar Oil refinery and has a degree in
is more suitable, as it is hard to        chemical engineering from M S University of
achieve a higher temperature              Baroda, India.
with steam.                               Email: alpesh_gurjar@yahoo.co.in



www.eptq.com                                                                              PTQ Q1 2010 77

More Related Content

What's hot

Hydrogen Plant Monitoring & Methane Steam Reformer Troubleshooting
Hydrogen Plant Monitoring & Methane Steam Reformer TroubleshootingHydrogen Plant Monitoring & Methane Steam Reformer Troubleshooting
Hydrogen Plant Monitoring & Methane Steam Reformer Troubleshooting
Gerard B. Hawkins
 
Calculation of an Ammonia Plant Energy Consumption:
Calculation of an Ammonia Plant Energy Consumption:  Calculation of an Ammonia Plant Energy Consumption:
Calculation of an Ammonia Plant Energy Consumption:
Gerard B. Hawkins
 
Internship_13BCH0001
Internship_13BCH0001Internship_13BCH0001
Internship_13BCH0001
Anshul Bhandari
 
SCALE-UP OF MICROCHANNEL REACTORS FOR FISCHER-TROPSCH
SCALE-UP OF MICROCHANNEL REACTORS FOR FISCHER-TROPSCHSCALE-UP OF MICROCHANNEL REACTORS FOR FISCHER-TROPSCH
SCALE-UP OF MICROCHANNEL REACTORS FOR FISCHER-TROPSCH
John Glenning
 
Principles & Practices to Manage Cl lon Stabilizer
Principles & Practices to Manage Cl lon StabilizerPrinciples & Practices to Manage Cl lon Stabilizer
Principles & Practices to Manage Cl lon Stabilizer
Gerard B. Hawkins
 
VULCAN VGP Series Purification Catalyst / Absorbents Operating Manual
VULCAN VGP Series Purification Catalyst / Absorbents Operating ManualVULCAN VGP Series Purification Catalyst / Absorbents Operating Manual
VULCAN VGP Series Purification Catalyst / Absorbents Operating Manual
Gerard B. Hawkins
 
oil_refinery_processes
oil_refinery_processesoil_refinery_processes
oil_refinery_processes
Satej Colaco
 
Piping and Vessels Flushing and Cleaning Procedure
Piping and Vessels Flushing and Cleaning ProcedurePiping and Vessels Flushing and Cleaning Procedure
Piping and Vessels Flushing and Cleaning Procedure
Gerard B. Hawkins
 
Boiler Feedwater Pumps
Boiler Feedwater PumpsBoiler Feedwater Pumps
Boiler Feedwater Pumps
Gerard B. Hawkins
 
Air / Steam Regeneration Procedure for Primary Reforming Ccatalyst
Air / Steam Regeneration Procedure for Primary Reforming CcatalystAir / Steam Regeneration Procedure for Primary Reforming Ccatalyst
Air / Steam Regeneration Procedure for Primary Reforming Ccatalyst
Gerard B. Hawkins
 
Nitrogen purging
Nitrogen  purgingNitrogen  purging
Nitrogen purging
Dermawan Tarigan
 
Velocys ppt140813_ENFL-ACS_2014
Velocys ppt140813_ENFL-ACS_2014Velocys ppt140813_ENFL-ACS_2014
Velocys ppt140813_ENFL-ACS_2014
John Glenning
 
VMT Company Introduction
VMT Company IntroductionVMT Company Introduction
VMT Company Introduction
BenedictSong1
 
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...
Gerard B. Hawkins
 
Other Separations Techniques for Suspensions
Other Separations Techniques for SuspensionsOther Separations Techniques for Suspensions
Other Separations Techniques for Suspensions
Gerard B. Hawkins
 
Bbtc 2011 Dubrovnik ( Th International Bottom Of The Barrel Technology Confer...
Bbtc 2011 Dubrovnik ( Th International Bottom Of The Barrel Technology Confer...Bbtc 2011 Dubrovnik ( Th International Bottom Of The Barrel Technology Confer...
Bbtc 2011 Dubrovnik ( Th International Bottom Of The Barrel Technology Confer...
abakshi2011
 
METHANOL PLANT ARC RETROFIT Case Study
METHANOL PLANT ARC RETROFIT Case StudyMETHANOL PLANT ARC RETROFIT Case Study
METHANOL PLANT ARC RETROFIT Case Study
Gerard B. Hawkins
 
Sedimentation
SedimentationSedimentation
Sedimentation
Gerard B. Hawkins
 
Power Plant Boiler feed pump
Power Plant Boiler feed pump Power Plant Boiler feed pump
Power Plant Boiler feed pump
Vundavilli Gautham
 
Isothermal Methanol Converter (IMC) UA Distribution Analysis
Isothermal Methanol Converter (IMC) UA Distribution AnalysisIsothermal Methanol Converter (IMC) UA Distribution Analysis
Isothermal Methanol Converter (IMC) UA Distribution Analysis
Gerard B. Hawkins
 

What's hot (20)

Hydrogen Plant Monitoring & Methane Steam Reformer Troubleshooting
Hydrogen Plant Monitoring & Methane Steam Reformer TroubleshootingHydrogen Plant Monitoring & Methane Steam Reformer Troubleshooting
Hydrogen Plant Monitoring & Methane Steam Reformer Troubleshooting
 
Calculation of an Ammonia Plant Energy Consumption:
Calculation of an Ammonia Plant Energy Consumption:  Calculation of an Ammonia Plant Energy Consumption:
Calculation of an Ammonia Plant Energy Consumption:
 
Internship_13BCH0001
Internship_13BCH0001Internship_13BCH0001
Internship_13BCH0001
 
SCALE-UP OF MICROCHANNEL REACTORS FOR FISCHER-TROPSCH
SCALE-UP OF MICROCHANNEL REACTORS FOR FISCHER-TROPSCHSCALE-UP OF MICROCHANNEL REACTORS FOR FISCHER-TROPSCH
SCALE-UP OF MICROCHANNEL REACTORS FOR FISCHER-TROPSCH
 
Principles & Practices to Manage Cl lon Stabilizer
Principles & Practices to Manage Cl lon StabilizerPrinciples & Practices to Manage Cl lon Stabilizer
Principles & Practices to Manage Cl lon Stabilizer
 
VULCAN VGP Series Purification Catalyst / Absorbents Operating Manual
VULCAN VGP Series Purification Catalyst / Absorbents Operating ManualVULCAN VGP Series Purification Catalyst / Absorbents Operating Manual
VULCAN VGP Series Purification Catalyst / Absorbents Operating Manual
 
oil_refinery_processes
oil_refinery_processesoil_refinery_processes
oil_refinery_processes
 
Piping and Vessels Flushing and Cleaning Procedure
Piping and Vessels Flushing and Cleaning ProcedurePiping and Vessels Flushing and Cleaning Procedure
Piping and Vessels Flushing and Cleaning Procedure
 
Boiler Feedwater Pumps
Boiler Feedwater PumpsBoiler Feedwater Pumps
Boiler Feedwater Pumps
 
Air / Steam Regeneration Procedure for Primary Reforming Ccatalyst
Air / Steam Regeneration Procedure for Primary Reforming CcatalystAir / Steam Regeneration Procedure for Primary Reforming Ccatalyst
Air / Steam Regeneration Procedure for Primary Reforming Ccatalyst
 
Nitrogen purging
Nitrogen  purgingNitrogen  purging
Nitrogen purging
 
Velocys ppt140813_ENFL-ACS_2014
Velocys ppt140813_ENFL-ACS_2014Velocys ppt140813_ENFL-ACS_2014
Velocys ppt140813_ENFL-ACS_2014
 
VMT Company Introduction
VMT Company IntroductionVMT Company Introduction
VMT Company Introduction
 
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...
The Selective Oxidation of n-Butane to Maleic Anhydride in a Catalyst Packed ...
 
Other Separations Techniques for Suspensions
Other Separations Techniques for SuspensionsOther Separations Techniques for Suspensions
Other Separations Techniques for Suspensions
 
Bbtc 2011 Dubrovnik ( Th International Bottom Of The Barrel Technology Confer...
Bbtc 2011 Dubrovnik ( Th International Bottom Of The Barrel Technology Confer...Bbtc 2011 Dubrovnik ( Th International Bottom Of The Barrel Technology Confer...
Bbtc 2011 Dubrovnik ( Th International Bottom Of The Barrel Technology Confer...
 
METHANOL PLANT ARC RETROFIT Case Study
METHANOL PLANT ARC RETROFIT Case StudyMETHANOL PLANT ARC RETROFIT Case Study
METHANOL PLANT ARC RETROFIT Case Study
 
Sedimentation
SedimentationSedimentation
Sedimentation
 
Power Plant Boiler feed pump
Power Plant Boiler feed pump Power Plant Boiler feed pump
Power Plant Boiler feed pump
 
Isothermal Methanol Converter (IMC) UA Distribution Analysis
Isothermal Methanol Converter (IMC) UA Distribution AnalysisIsothermal Methanol Converter (IMC) UA Distribution Analysis
Isothermal Methanol Converter (IMC) UA Distribution Analysis
 

Similar to Choosing Hydroprocessing Scheme

Reactor Modeling Tools - An Overview
Reactor Modeling Tools - An OverviewReactor Modeling Tools - An Overview
Reactor Modeling Tools - An Overview
Gerard B. Hawkins
 
Optimizing the Steam Generation Cycle and Condensate Recovery Process
Optimizing the Steam Generation Cycle and Condensate Recovery ProcessOptimizing the Steam Generation Cycle and Condensate Recovery Process
Optimizing the Steam Generation Cycle and Condensate Recovery Process
M.S. Jacobs & Associates
 
Optimizing the Steam Generation Cycle and Condensate Recovery Process
Optimizing the Steam Generation Cycle and Condensate Recovery ProcessOptimizing the Steam Generation Cycle and Condensate Recovery Process
Optimizing the Steam Generation Cycle and Condensate Recovery Process
Belilove Company-Engineers
 
10.1016@j.cattod.2013.05.016.pdf
10.1016@j.cattod.2013.05.016.pdf10.1016@j.cattod.2013.05.016.pdf
10.1016@j.cattod.2013.05.016.pdf
IlyasKhan84634
 
Activity test eus vfinal
Activity test   eus vfinalActivity test   eus vfinal
Activity test eus vfinal
BCS LLC
 
Getting the Most Out of Your Refinery Hydrogen Plant
Getting the Most Out of Your Refinery Hydrogen PlantGetting the Most Out of Your Refinery Hydrogen Plant
Getting the Most Out of Your Refinery Hydrogen Plant
Gerard B. Hawkins
 
rosemount_level_user_guide_refining_ind.pdf
rosemount_level_user_guide_refining_ind.pdfrosemount_level_user_guide_refining_ind.pdf
rosemount_level_user_guide_refining_ind.pdf
ssuser3eddcd
 
IRJET- A Study on a Diesel Hydrotreater using Combined Refinery Streams
IRJET-  	  A Study on a Diesel Hydrotreater using Combined Refinery StreamsIRJET-  	  A Study on a Diesel Hydrotreater using Combined Refinery Streams
IRJET- A Study on a Diesel Hydrotreater using Combined Refinery Streams
IRJET Journal
 
Solid Catalyzed Gas Phase Reactor Selection
Solid Catalyzed Gas Phase Reactor SelectionSolid Catalyzed Gas Phase Reactor Selection
Solid Catalyzed Gas Phase Reactor Selection
Gerard B. Hawkins
 
eni_EST_esecutivo
eni_EST_esecutivoeni_EST_esecutivo
eni_EST_esecutivo
Francesco Legname
 
In Situ Oil Sands SOR Reduction Initiative
In Situ Oil Sands SOR Reduction InitiativeIn Situ Oil Sands SOR Reduction Initiative
In Situ Oil Sands SOR Reduction Initiative
philbrown49
 
Mixing of Immiscible Liquids
Mixing of Immiscible LiquidsMixing of Immiscible Liquids
Mixing of Immiscible Liquids
Gerard B. Hawkins
 
Resume talley 1.5.2016.formatted
Resume talley 1.5.2016.formattedResume talley 1.5.2016.formatted
Resume talley 1.5.2016.formatted
Dennis Talley
 
Key Considerations for a Reforming Unit Revamp
Key Considerations for a Reforming Unit RevampKey Considerations for a Reforming Unit Revamp
Key Considerations for a Reforming Unit Revamp
Gerard B. Hawkins
 
The Design and Layout of Vertical Thermosyphon Reboilers
The Design and Layout of Vertical Thermosyphon ReboilersThe Design and Layout of Vertical Thermosyphon Reboilers
The Design and Layout of Vertical Thermosyphon Reboilers
Gerard B. Hawkins
 
Fixed Bed Adsorber Design Guidelines
Fixed Bed Adsorber Design GuidelinesFixed Bed Adsorber Design Guidelines
Fixed Bed Adsorber Design Guidelines
Gerard B. Hawkins
 
CV-cassidy
CV-cassidyCV-cassidy
CV-cassidy
Susan Cassidy
 
Ciclos Refrigerantes Regenerativos 2005
Ciclos Refrigerantes Regenerativos 2005Ciclos Refrigerantes Regenerativos 2005
Ciclos Refrigerantes Regenerativos 2005
XJM
 
Turbulent Heat Transfer to Non Newtonian Fluids in Circular Tubes
Turbulent Heat Transfer to Non Newtonian Fluids in Circular TubesTurbulent Heat Transfer to Non Newtonian Fluids in Circular Tubes
Turbulent Heat Transfer to Non Newtonian Fluids in Circular Tubes
Gerard B. Hawkins
 
Reactor Modeling Tools – Multiple Regressions
Reactor Modeling Tools – Multiple Regressions Reactor Modeling Tools – Multiple Regressions
Reactor Modeling Tools – Multiple Regressions
Gerard B. Hawkins
 

Similar to Choosing Hydroprocessing Scheme (20)

Reactor Modeling Tools - An Overview
Reactor Modeling Tools - An OverviewReactor Modeling Tools - An Overview
Reactor Modeling Tools - An Overview
 
Optimizing the Steam Generation Cycle and Condensate Recovery Process
Optimizing the Steam Generation Cycle and Condensate Recovery ProcessOptimizing the Steam Generation Cycle and Condensate Recovery Process
Optimizing the Steam Generation Cycle and Condensate Recovery Process
 
Optimizing the Steam Generation Cycle and Condensate Recovery Process
Optimizing the Steam Generation Cycle and Condensate Recovery ProcessOptimizing the Steam Generation Cycle and Condensate Recovery Process
Optimizing the Steam Generation Cycle and Condensate Recovery Process
 
10.1016@j.cattod.2013.05.016.pdf
10.1016@j.cattod.2013.05.016.pdf10.1016@j.cattod.2013.05.016.pdf
10.1016@j.cattod.2013.05.016.pdf
 
Activity test eus vfinal
Activity test   eus vfinalActivity test   eus vfinal
Activity test eus vfinal
 
Getting the Most Out of Your Refinery Hydrogen Plant
Getting the Most Out of Your Refinery Hydrogen PlantGetting the Most Out of Your Refinery Hydrogen Plant
Getting the Most Out of Your Refinery Hydrogen Plant
 
rosemount_level_user_guide_refining_ind.pdf
rosemount_level_user_guide_refining_ind.pdfrosemount_level_user_guide_refining_ind.pdf
rosemount_level_user_guide_refining_ind.pdf
 
IRJET- A Study on a Diesel Hydrotreater using Combined Refinery Streams
IRJET-  	  A Study on a Diesel Hydrotreater using Combined Refinery StreamsIRJET-  	  A Study on a Diesel Hydrotreater using Combined Refinery Streams
IRJET- A Study on a Diesel Hydrotreater using Combined Refinery Streams
 
Solid Catalyzed Gas Phase Reactor Selection
Solid Catalyzed Gas Phase Reactor SelectionSolid Catalyzed Gas Phase Reactor Selection
Solid Catalyzed Gas Phase Reactor Selection
 
eni_EST_esecutivo
eni_EST_esecutivoeni_EST_esecutivo
eni_EST_esecutivo
 
In Situ Oil Sands SOR Reduction Initiative
In Situ Oil Sands SOR Reduction InitiativeIn Situ Oil Sands SOR Reduction Initiative
In Situ Oil Sands SOR Reduction Initiative
 
Mixing of Immiscible Liquids
Mixing of Immiscible LiquidsMixing of Immiscible Liquids
Mixing of Immiscible Liquids
 
Resume talley 1.5.2016.formatted
Resume talley 1.5.2016.formattedResume talley 1.5.2016.formatted
Resume talley 1.5.2016.formatted
 
Key Considerations for a Reforming Unit Revamp
Key Considerations for a Reforming Unit RevampKey Considerations for a Reforming Unit Revamp
Key Considerations for a Reforming Unit Revamp
 
The Design and Layout of Vertical Thermosyphon Reboilers
The Design and Layout of Vertical Thermosyphon ReboilersThe Design and Layout of Vertical Thermosyphon Reboilers
The Design and Layout of Vertical Thermosyphon Reboilers
 
Fixed Bed Adsorber Design Guidelines
Fixed Bed Adsorber Design GuidelinesFixed Bed Adsorber Design Guidelines
Fixed Bed Adsorber Design Guidelines
 
CV-cassidy
CV-cassidyCV-cassidy
CV-cassidy
 
Ciclos Refrigerantes Regenerativos 2005
Ciclos Refrigerantes Regenerativos 2005Ciclos Refrigerantes Regenerativos 2005
Ciclos Refrigerantes Regenerativos 2005
 
Turbulent Heat Transfer to Non Newtonian Fluids in Circular Tubes
Turbulent Heat Transfer to Non Newtonian Fluids in Circular TubesTurbulent Heat Transfer to Non Newtonian Fluids in Circular Tubes
Turbulent Heat Transfer to Non Newtonian Fluids in Circular Tubes
 
Reactor Modeling Tools – Multiple Regressions
Reactor Modeling Tools – Multiple Regressions Reactor Modeling Tools – Multiple Regressions
Reactor Modeling Tools – Multiple Regressions
 

Recently uploaded

Patch Tuesday de julio
Patch Tuesday de julioPatch Tuesday de julio
Patch Tuesday de julio
Ivanti
 
Using LLM Agents with Llama 3, LangGraph and Milvus
Using LLM Agents with Llama 3, LangGraph and MilvusUsing LLM Agents with Llama 3, LangGraph and Milvus
Using LLM Agents with Llama 3, LangGraph and Milvus
Zilliz
 
July Patch Tuesday
July Patch TuesdayJuly Patch Tuesday
July Patch Tuesday
Ivanti
 
Mastering OnlyFans Clone App Development: Key Strategies for Success
Mastering OnlyFans Clone App Development: Key Strategies for SuccessMastering OnlyFans Clone App Development: Key Strategies for Success
Mastering OnlyFans Clone App Development: Key Strategies for Success
David Wilson
 
(CISOPlatform Summit & SACON 2024) Keynote _ Power Digital Identities With AI...
(CISOPlatform Summit & SACON 2024) Keynote _ Power Digital Identities With AI...(CISOPlatform Summit & SACON 2024) Keynote _ Power Digital Identities With AI...
(CISOPlatform Summit & SACON 2024) Keynote _ Power Digital Identities With AI...
Priyanka Aash
 
Girls call Kolkata 👀 XXXXXXXXXXX 👀 Rs.9.5 K Cash Payment With Room Delivery
Girls call Kolkata 👀 XXXXXXXXXXX 👀 Rs.9.5 K Cash Payment With Room Delivery Girls call Kolkata 👀 XXXXXXXXXXX 👀 Rs.9.5 K Cash Payment With Room Delivery
Girls call Kolkata 👀 XXXXXXXXXXX 👀 Rs.9.5 K Cash Payment With Room Delivery
sunilverma7884
 
The importance of Quality Assurance for ICT Standardization
The importance of Quality Assurance for ICT StandardizationThe importance of Quality Assurance for ICT Standardization
The importance of Quality Assurance for ICT Standardization
Axel Rennoch
 
High Profile Girls call Service Pune 000XX00000 Provide Best And Top Girl Ser...
High Profile Girls call Service Pune 000XX00000 Provide Best And Top Girl Ser...High Profile Girls call Service Pune 000XX00000 Provide Best And Top Girl Ser...
High Profile Girls call Service Pune 000XX00000 Provide Best And Top Girl Ser...
bhumivarma35300
 
Opencast Summit 2024 — Opencast @ University of Münster
Opencast Summit 2024 — Opencast @ University of MünsterOpencast Summit 2024 — Opencast @ University of Münster
Opencast Summit 2024 — Opencast @ University of Münster
Matthias Neugebauer
 
"Mastering Graphic Design: Essential Tips and Tricks for Beginners and Profes...
"Mastering Graphic Design: Essential Tips and Tricks for Beginners and Profes..."Mastering Graphic Design: Essential Tips and Tricks for Beginners and Profes...
"Mastering Graphic Design: Essential Tips and Tricks for Beginners and Profes...
Anant Gupta
 
Sonkoloniya documentation - ONEprojukti.pdf
Sonkoloniya documentation - ONEprojukti.pdfSonkoloniya documentation - ONEprojukti.pdf
Sonkoloniya documentation - ONEprojukti.pdf
SubhamMandal40
 
IPLOOK Remote-Sensing Satellite Solution
IPLOOK Remote-Sensing Satellite SolutionIPLOOK Remote-Sensing Satellite Solution
IPLOOK Remote-Sensing Satellite Solution
IPLOOK Networks
 
Acumatica vs. Sage Intacct vs. NetSuite _ NOW CFO.pdf
Acumatica vs. Sage Intacct vs. NetSuite _ NOW CFO.pdfAcumatica vs. Sage Intacct vs. NetSuite _ NOW CFO.pdf
Acumatica vs. Sage Intacct vs. NetSuite _ NOW CFO.pdf
BrainSell Technologies
 
(CISOPlatform Summit & SACON 2024) Gen AI & Deepfake In Overall Security.pdf
(CISOPlatform Summit & SACON 2024) Gen AI & Deepfake In Overall Security.pdf(CISOPlatform Summit & SACON 2024) Gen AI & Deepfake In Overall Security.pdf
(CISOPlatform Summit & SACON 2024) Gen AI & Deepfake In Overall Security.pdf
Priyanka Aash
 
Connector Corner: Leveraging Snowflake Integration for Smarter Decision Making
Connector Corner: Leveraging Snowflake Integration for Smarter Decision MakingConnector Corner: Leveraging Snowflake Integration for Smarter Decision Making
Connector Corner: Leveraging Snowflake Integration for Smarter Decision Making
DianaGray10
 
The Role of IoT in Australian Mobile App Development - PDF Guide
The Role of IoT in Australian Mobile App Development - PDF GuideThe Role of IoT in Australian Mobile App Development - PDF Guide
The Role of IoT in Australian Mobile App Development - PDF Guide
Shiv Technolabs
 
WhatsApp Spy Online Trackers and Monitoring Apps
WhatsApp Spy Online Trackers and Monitoring AppsWhatsApp Spy Online Trackers and Monitoring Apps
WhatsApp Spy Online Trackers and Monitoring Apps
HackersList
 
Russian Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl Ser...
Russian Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl Ser...Russian Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl Ser...
Russian Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl Ser...
bellared2
 
What's new in android: jetpack compose 2024
What's new in android: jetpack compose 2024What's new in android: jetpack compose 2024
What's new in android: jetpack compose 2024
Toru Wonyoung Choi
 
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-InTrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc
 

Recently uploaded (20)

Patch Tuesday de julio
Patch Tuesday de julioPatch Tuesday de julio
Patch Tuesday de julio
 
Using LLM Agents with Llama 3, LangGraph and Milvus
Using LLM Agents with Llama 3, LangGraph and MilvusUsing LLM Agents with Llama 3, LangGraph and Milvus
Using LLM Agents with Llama 3, LangGraph and Milvus
 
July Patch Tuesday
July Patch TuesdayJuly Patch Tuesday
July Patch Tuesday
 
Mastering OnlyFans Clone App Development: Key Strategies for Success
Mastering OnlyFans Clone App Development: Key Strategies for SuccessMastering OnlyFans Clone App Development: Key Strategies for Success
Mastering OnlyFans Clone App Development: Key Strategies for Success
 
(CISOPlatform Summit & SACON 2024) Keynote _ Power Digital Identities With AI...
(CISOPlatform Summit & SACON 2024) Keynote _ Power Digital Identities With AI...(CISOPlatform Summit & SACON 2024) Keynote _ Power Digital Identities With AI...
(CISOPlatform Summit & SACON 2024) Keynote _ Power Digital Identities With AI...
 
Girls call Kolkata 👀 XXXXXXXXXXX 👀 Rs.9.5 K Cash Payment With Room Delivery
Girls call Kolkata 👀 XXXXXXXXXXX 👀 Rs.9.5 K Cash Payment With Room Delivery Girls call Kolkata 👀 XXXXXXXXXXX 👀 Rs.9.5 K Cash Payment With Room Delivery
Girls call Kolkata 👀 XXXXXXXXXXX 👀 Rs.9.5 K Cash Payment With Room Delivery
 
The importance of Quality Assurance for ICT Standardization
The importance of Quality Assurance for ICT StandardizationThe importance of Quality Assurance for ICT Standardization
The importance of Quality Assurance for ICT Standardization
 
High Profile Girls call Service Pune 000XX00000 Provide Best And Top Girl Ser...
High Profile Girls call Service Pune 000XX00000 Provide Best And Top Girl Ser...High Profile Girls call Service Pune 000XX00000 Provide Best And Top Girl Ser...
High Profile Girls call Service Pune 000XX00000 Provide Best And Top Girl Ser...
 
Opencast Summit 2024 — Opencast @ University of Münster
Opencast Summit 2024 — Opencast @ University of MünsterOpencast Summit 2024 — Opencast @ University of Münster
Opencast Summit 2024 — Opencast @ University of Münster
 
"Mastering Graphic Design: Essential Tips and Tricks for Beginners and Profes...
"Mastering Graphic Design: Essential Tips and Tricks for Beginners and Profes..."Mastering Graphic Design: Essential Tips and Tricks for Beginners and Profes...
"Mastering Graphic Design: Essential Tips and Tricks for Beginners and Profes...
 
Sonkoloniya documentation - ONEprojukti.pdf
Sonkoloniya documentation - ONEprojukti.pdfSonkoloniya documentation - ONEprojukti.pdf
Sonkoloniya documentation - ONEprojukti.pdf
 
IPLOOK Remote-Sensing Satellite Solution
IPLOOK Remote-Sensing Satellite SolutionIPLOOK Remote-Sensing Satellite Solution
IPLOOK Remote-Sensing Satellite Solution
 
Acumatica vs. Sage Intacct vs. NetSuite _ NOW CFO.pdf
Acumatica vs. Sage Intacct vs. NetSuite _ NOW CFO.pdfAcumatica vs. Sage Intacct vs. NetSuite _ NOW CFO.pdf
Acumatica vs. Sage Intacct vs. NetSuite _ NOW CFO.pdf
 
(CISOPlatform Summit & SACON 2024) Gen AI & Deepfake In Overall Security.pdf
(CISOPlatform Summit & SACON 2024) Gen AI & Deepfake In Overall Security.pdf(CISOPlatform Summit & SACON 2024) Gen AI & Deepfake In Overall Security.pdf
(CISOPlatform Summit & SACON 2024) Gen AI & Deepfake In Overall Security.pdf
 
Connector Corner: Leveraging Snowflake Integration for Smarter Decision Making
Connector Corner: Leveraging Snowflake Integration for Smarter Decision MakingConnector Corner: Leveraging Snowflake Integration for Smarter Decision Making
Connector Corner: Leveraging Snowflake Integration for Smarter Decision Making
 
The Role of IoT in Australian Mobile App Development - PDF Guide
The Role of IoT in Australian Mobile App Development - PDF GuideThe Role of IoT in Australian Mobile App Development - PDF Guide
The Role of IoT in Australian Mobile App Development - PDF Guide
 
WhatsApp Spy Online Trackers and Monitoring Apps
WhatsApp Spy Online Trackers and Monitoring AppsWhatsApp Spy Online Trackers and Monitoring Apps
WhatsApp Spy Online Trackers and Monitoring Apps
 
Russian Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl Ser...
Russian Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl Ser...Russian Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl Ser...
Russian Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl Ser...
 
What's new in android: jetpack compose 2024
What's new in android: jetpack compose 2024What's new in android: jetpack compose 2024
What's new in android: jetpack compose 2024
 
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-InTrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
TrustArc Webinar - 2024 Data Privacy Trends: A Mid-Year Check-In
 

Choosing Hydroprocessing Scheme

  • 1. Choosing a hydroprocessing scheme A systematic approach to selecting hydroprocessing technology meets process objectives with optimal operating and capital costs AlpesH GurjAr Fluor Daniel India H ydroprocessing technologies reduce nitrogen and aromatic (RDS), should be flexible enough to are well established in the content, and enhance cetane number, process a wide range of feed refining industry for the API gravity and smoke point. qualities, of diverse origin, at production of clean fuels. However, Hydroprocessing of middle distil- different conversion levels. increased competition within the lates also plays a key role in industry mandates a greater focus improving cold flow properties such Basis of technology evaluation on awareness of the right tech- as pour point, cloud point and cold All technologies work well within a nology and catalysts to achieve the filter plug point. This enables specific context and under certain products and performance needed refiners to meet the stringent conditions. The total investment in the market. product specifi-cations determined costs for a hydroprocessing unit For refiners to sustain their profit by regulatory bodies. increase with unit size, feedstock margins, economical access to state- The established refinery configur- sulphur, nitrogen and quantity of of-the-art technology is a must. ation includes a minimum of three cracked stocks. The evaluation of Refinery management needs to plan or four hydroprocessing units for new technology should be based on for the future to maintain long- upgrading light, middle and heavy detailed technical and economic term growth, maximise asset analysis. performance, formulate an effective The total on-site capital cost response to changing environ- The total investment estimate for a new hydrotreater unit mental legislation and incorporate varies, depending on the licensed sufficient flexibility to withstand costs for a and proprietary technology. The business cycles while crude supplies overall system can be broadly are becoming increasingly heavy hydroprocessing classified in three parts: a reactor and sour. Increased operational unit increase with system, hydrogen make-up/recycle excellence is a priority for refineries, gas compressor and other separation which leads refiners to look at more unit size, feedstock equipment. The cost of the reactor innovative ways of maintaining system and compressor depends on reasonable margins in new projects, sulphur, nitrogen and the percentage of cracked stock to quickly recover the investments present in the hydrotreater feed. The they have made and to justify quantity of cracked cost of the separation equipment is additional investment to cope with a function of unit capacity. The basic a changing market. stocks difference in the capital costs of a Hydrotreating, the workhorse of unit at a given capacity level is the refinery, serves to meet several distillates. Upgrading light distillate the result of variations in the significant product quality specifi- involves the use of proven fractions of the different types of cations. Increasingly stringent technology for the desulphurisation feed; for example, straight-run vs regulations for fuel (for instance, of FCC naphtha with minimum cracked stock and the sulphur level 10–15 ppm sulphur in diesel and octane loss, as this stream contri- of the feed as well as the catalyst. gasoline), the processing of lower- butes significantly to the refinery The major items of focus during quality, higher-sulphur crudes, gasoline pool. Upgrading middle the evaluation of hydroprocessing tightening site emissions standards distillate (kerosene and diesel) technology are process configur- (SOx and NOx reduction), and rising focuses on managing hydrogen and ation, reactor operating conditions, gasoline and diesel consumption are energy consumption, while produc- number and size of high-pressure all factors that make significant ing ultra-low sulphur products. The items, quantity and type of catalyst demands of a hydroprocessing unit gas oils and residue upgrading used, catalyst deactivation rate, in a refinery. In addition, a hydro- technology, such as hydrocracking make-up hydrogen purity and processing unit helps refiners to and residual oil desulphurisation design pressure level, depending www.eptq.com PTQ Q1 2010 71
  • 2. on the product quality requirements. sulphur and nitrogen compounds in process severity/variables In determining the compatibility of a feed depends on the feedstock’s A key factor to be considered in the licensor’s technology with boiling range, prior processing establishing an effective hydro- existing facilities it is essential to history (whether thermally or processing technology is the level of check its capability with regard catalytically cracked) and the crude conversion required for achieving to variations in feed qualities and oil type from which it is derived. the desired objective. This level of the effect of product slate for The olefin content associated with conversion effectively sets the level blending. cracked stock gives an idea of of process severity required, from The key process objectives to anticipated exotherms, the mild hydrofinishing for removing define in order to establish a configuration of efficient quenching, contaminants such as sulphur and transparent and consistent evalu- heat recovery and the separation nitrogen containing compounds, to ation methodology are: system. It also enables a refiner to complex molecular reconstructions • Desired function of the hydro- choose a reactor catalyst bed associated with hydrocracking and processing unit in the refinery, such arrangement. The aromatic content aromatic saturation reactions. The as hydrodesulphurisation (HDS), of a feed and its saturation operating conditions of a hydro- hydrodenitrification (HDN), olefin requirements fixes the partial processing unit are a function of saturation, aromatic saturation and pressure of a distillate hydrotreating feedstock characteristics based on metals removal unit, which plays an important origin. The operating and capital • Feed and product specifications role in the operating and capital cost of the unit increases with the • Minimum catalyst cycle length cost of the unit. The prediction of severity of the unit. The proper • Hydrogen utilisation combination of process parameters • Availability of the unit (on-stream should be in accordance with the operating factor per year) The prediction of optimal use of hydrogen and the • Unit turndown capacity. available utilities, such as fuel, unit dynamics caused cooling water and steam. The key Criteria for selecting technology process variables are liquid hourly No single process technology by feed quality space velocity (LHSV), hydrogen solution can be applied to all partial pressure, temperature and refineries because of their widely changes is of prime gas-to-oil ratio. different configurations and objec- tives. A comprehensive, site-specific importance during liquid hourly space velocity study is needed to identify the most suitable process scheme under the design phase of LHSV is a measure of the residence time in the reactor. The lower the given scenarios. The evaluation the unit LHSV, the higher the residence time. should be based on the criteria The lower the LHSV, the bigger the developed and approved by project reactor and the higher the capital management and the client during unit dynamics caused by feed cost. Typically, the LHSV require- the planning phase. quality changes is of prime ment depends on the boiling range Technical evaluation of a licensor’s importance during the design phase of the hydrocarbons. A heavy feed technology is of prime importance of the unit. contains higher amounts of sulphur when it comes to customising its and nitrogen impurities with a unique features, amplifying its process chemistry complex ring structure. The removal reliability, flexibility and operational An understanding of the chemistry of such compounds requires more performance, and so meet current involved in the removal of sulphur residence time in a reactor and needs and future requirements. and nitrogen compounds is essential therefore lower LHSV. LHSV can be The key points that significantly when defining the operating adjusted by either reducing the feed influence the hydroprocessing unit’s severity, based on varying relative throughput, which is not economical, process design follow. rates of reactions of different com- or by the addition of a new reactor pounds. Desulphurisation, denitrifi- or more catalyst in the same reactor, Feed characterisation cation and olefin saturation are which requires substantial capital Good feedstock characterisation, kinetically controlled reactions. investment. An optimal design is including off-design variations, is Increasing the process severity, such usually one that takes advantage essential for the proper selection of as raising the temperature, usually of a higher-activity, commercially catalyst, reaction conditions and allows these reactions to approach proven catalyst to set reactor catalyst process configuration. A study of near complete conversion. However, volumes and pressure levels for a feedstock at the micro level provides the aromatic saturation reaction is target run length. Figure 1 shows a thorough understanding of thermodynamically limited, so a the effect of a decrease in LHSV on feedstock reactivity and the careful balancing of kinetic and polyaromatic saturation levels. subsequent processing conditions thermodynamic equilibrium is needed to meet process objectives. required when deciding on pressure Hydrogen partial pressure The distribution and nature of level and catalyst volume. The type of feed to be processed, 72 PTQ Q1 2010 www.eptq.com
  • 3. product quality requirements, yield span, and so will benefit from a activity. There is a minor boost in and the amount of conversion for a longer run, increased unit hydrogen partial pressure as well specific catalyst cycle life determine throughput or the ability to process with increasing gas circulation rates. the hydrogen partial pressure a challenging feed mix. The However, above a certain gas rate, required for the operation of a operating temperature should be the increase in hydrogen partial hydroprocessing unit. The hydrogen high enough to facilitate faster pressure will be relatively small and partial pressure must be high kinetic reaction rates, but not so incur extra heating and cooling enough to accomplish the desired high as to promote undesirable side costs. level of denitrification and partial reactions or to exceed the metal- In addition to affecting hydrogen saturation of heavy aromatic lurgical limits of high-pressure partial pressure, the gas rate is molecules. At higher partial vessels. important because it acts to strip pressures, the desulphurisation and As the end point of hydrocarbon volatile products from the reactor denitrification process is “easier”; feed increases, there is an increase liquids, and thus affects the however, the unit becomes more in the concentration of recalcitrant concentration of various components expensive because of the need for sulphur and nitrogen species in the in the reactive liquid phase. It also thicker-walled reactors. The form of dibenzothiophenes, which maintains proper mass velocity in minimum pressure required necessitates a higher SOR temper- the catalyst bed, thus reducing the typically rises with the required ature. For grassroots units, a higher- possibilities of channelling in the severity of the unit. A higher hydrogen partial pressure decreases catalyst deactivation and, therefore, increases the predicted cycle length Thermodynamic effects for a fixed quantity of catalyst. The importance of maintaining adequate hydrogen partial pressure increases as sulphur levels approach the sub-ppm level, because the primary HDS reaction shifts from a predominantly non-reversible, Increasing pressure single-step reaction to a reversible, Decreasing equilibrium-limited, two-step reac- LHSV tion. As the unit approaches a higher LHSV effects operating temperature at end-of-run (EOR) conditions, the lower-pressure unit may struggle to meet 10 wppm sulphur requirements because of the effects of thermodynamic equilibrium. At lower sulphur levels, the remaining species behave like polyaromatics and, therefore, the Figure 1 The impact of process conditions on polyaromatic saturation chemistry of their removal obeys similar rules to the saturation of activity catalyst may be employed bed, and carries the reaction heat. It polyaromatics. Figure 1 shows that to optimise the unit design temper- is prudent to maintain a healthy an increase in total pressure/ ature and pressure requirements in hydrogen-to-oil ratio to prevent hydrogen partial pressure increases order to save capital investment. coking and subsequent deactivation the absolute level of polyaromatic of the catalyst. As a guide, the saturation. Hydrogen/hydrocarbon ratio and available hydrogen at the top of the recycle gas rate reactor should be two-and-a-half to Temperature (WABT) The choice of recycle gas rate is three times the chemical hydrogen For most hydrotreating units, the governed by economic consider- consumption for easier feedstocks only parameter that typically varies ations. Recycle hydrogen is used to and three to four times the chemical once the unit is built is the start-of- enable flow distribution and uniform hydrogen consumption for cracked run (SOR) temperature, depending physical contact of the hydrogen feedstocks. on catalyst activity. Since the EOR with oil-soaked catalyst to ensure temperature is usually fixed, based adequate conversion and removal Catalyst selection on the specification or unit of impurities, while minimising Hydrotreating catalysts consist of a hardware constraints, a higher- carbon deposition. For high-activity hydrogenation component dis- activity catalyst will help to start the hydrotreating catalysts, there may persed on a porous, fairly inert reaction at a colder temperature, be a minimum treat gas circulation material. For hydrotreating, catalysts thereby increasing the temperature requirement to preserve catalyst with weak acidity are used, since 74 PTQ Q1 2010 www.eptq.com
  • 4. hydrogenation and cracking capa- HDS/HDN bilities, its size, shape and pore reactor with silica guard structure are very important, as they Di-olefin reactor govern the pressure drop, surface- to-volume ratio and diffusion rate. Start-up heater Different shapes of catalyst are often used to take advantage of their high surface-to-volume ratio, while still maintaining a reasonable reactor pressure drop. The reaction kinetics are usually diffusion limited; a small catalyst with a high surface-to- volume ratio has better diffusion for the relatively heavy feed. The pore diameter for the residuum hydrotreating catalyst needs to be quite large relative to a catalyst for light feed. The increase in pore size decreases the surface area and the Figure 2 Naphtha hydrotreater unit co-processing cracked stocks catalyst activity. To overcome the limitations of small vs large pore cracking and the associated is high, a NiMo catalyst system may trade-off, catalysts are layered to production of light ends and lighter be the right choice. Recent advances increase activity; for example, large liquid product(s) are usually include staging or stacking both pore-sized catalyst in the top section undesirable. A combination of base CoMo and NiMo catalysts within a of the reactor, followed by smaller metals, such as NiMo and CoMo, is single fixed-bed reactor. pore-sized catalyst. Typical pore used to achieve deep HDS and HDN Hydrocracking catalysts serve sizes of 75–85 Å for light/heavy gas activity. Feed composition and dual functions, containing both oil feed and 150–250 Å for residue product quality requirements define hydrogenation and cracking sites. feed can be used. the required chemical composition The cracking sites are usually the and quantity of the catalyst. result of using a porous support of Feed filtration Typically, a CoMo catalyst may be an acidic nature, such as amorphous Feed filtration is important to the right choice where the feed is silica-alumina and crystalline mitigate exchanger and reactor straight-run distillate with very little aluminosilicates or zeolites. The best plugging. An appropriate feed nitrogen content and the operating choice of catalyst for a specific filtration system can reduce the pressure is low to moderate. On the objective requires a particular build of pressure drop in the other hand, if the feed contains a balance between the cracking and reaction section of the unit, which high percentage of cracked stock hydrogenation functions. results in a significant reduction in that has a significant nitrogen In addition to the chemical nature operating costs. A cartridge or content and the operating pressure of the catalyst, which dictates its wedge wire backwash filter with 25 micron retention is typical for this application. Cracked feeds should feed the hydrotreater hot from the upstream facilities or from inert gas blanketed storage. The use of steam- stripped feed that contains a significant amount of water requires the installation of a feed coaleaser upstream of the feed filter. However, Co-current or counter-current traces of water can be removed by AroSat reactor using a horizontal feed surge drum with associated water boot, eliminating the need for a coaleaser. Stripper Feed heating section Hydrotreating This section comprises a series of reactor heat exchangers followed by a charge heater. Hydroprocessing reactions are exothermic in nature. The reactor feed effluent exchanger Figure 3 ULSD unit with AroSat option must recover as much heat as is www.eptq.com PTQ Q1 2010 75
  • 5. economically practical to minimise the heat input in the charge furnace to typically less than 15–20% for heat balance and emergency operation. Off-design cases such as cold start-up or loss of feed results in a high design duty and thus a CHPS higher capital cost. The proper selection of exchangers enables a maximum recovery of heat of reaction, minimises the probability of leakage and increases the unit’s reliability. If the feed to the charge heater is a two-phase stream, to Figure 4 For straight-run feed (naphtha hydrotreater) avoid coking/hotspot in the charge heater tube passes, it is recommended the second reactor, with a stripper to have pass balancing to maintain in between, may be the preferred processed using moving-bed and/ equal flow distribution. Bypassing configuration (see Figure 3). For or ebullated-bed reactors. Recent the heat exchanger train should be hydrocrackers, depending on pilot work includes slurry-based considered in the case of an capacity, conversion and product reactors for deep-conversion residue uncontrollable increase in the reactor specification targets, it may be best hydrocracking. Multireactor systems bed temperature when processing to investigate two-stage reactor consisting of moving- and/or large amounts of cracked stocks. systems that allow staging of the ebullated-bed reactors integrated HDS/HDN reactions in a sour, with fixed-bed reactors can be used reactor configuration ammoniacal environment and HDA to process difficult feeds. The number of reactors and their reactions in a sweet, colder configuration depends on factors environment to capitalise on kinetic reactor internals such as catalyst volume, mass and reaction rates. Reactor internals are exceptionally volumetric flux, reactor pressure The reactors selected for light important for the safe, reliable and drop, reactor dimensions and feeds differ markedly from those profitable operation of a hydro- materials of construction. A typical selected for heavy feeds. Fixed-bed processing unit and may have a pressure drop of about 0.7–1.5 psi/ reactors have been traditionally major effect on reactor performance ft of catalyst bed (SOR to EOR) is used for light feeds. High asphaltene in terms of catalyst utilisation desirable to promote uniform flow and high metal content feeds, such efficiency and unit availability. For through the catalyst bed to have a as vacuum residue, are successfully a gas-phase reaction such as naphtha uniform radial temperature profile. An excessive pressure drop will increase the recycle gas compressor power consumption and could challenge the mechanical integrity of the reactor catalyst support trays. Other factors are flexibility in fabrication and transportation from CHPS workshop to refinery site. In special cases, the refinery’s ground conditions may also preclude the installation of a single heavy weight reactor. If the feed contains a high level of HHPS olefins, to avoid fouling in the heat exchangers, in the heater and in the top catalyst bed it is advisable to saturate the olefins at a lower reactor temperature. A separate olefin Intermediate pressure saturation reactor may be added break-up drum upstream of the HDS reactor (see Figure 2). For a unit where deep aromatic saturation is required, a two-stage reactor approach using HDS/HDN catalyst in the first reactor and a noble metal catalyst in Figure 5 For cracked stock feed (high-severity ULSD unit) www.eptq.com PTQ Q1 2010 77
  • 6. CHPS HHPS CLPS HLPS Figure 6 Classic four-drum separation system (hydrocracker unit) hydrotreating, a distribution tray is product cooling and separation schemes ensures the efficient not necessary, but for a trickle-bed A typical configuration in any recovery of hydrogen from hydro- reactor, processing middle/heavy hydrotreater includes a feed/ carbon, reduces the relief load of distillates, specially designed gas effluent heat exchanger train, a large the system and facilitates a lower liquid distributors to achieve small- air-cooled heat exchanger and one, design pressure for the downstream scale contacting of process gas and two or more flash drums, depending columns. The configuration of the liquid are mandatory. An ideal on unit heat balance and hydrogen separation system depends on the liquid distributor should have a recovery requirements. economic balance between operating high distribution element density, A straight-run feed with alumina- and capital cost, in addition to feed low pressure drop, large spray based catalyst produces fewer light quality and hydrogen availability. angle, turndown flexibility and be ends, so a single, cold, high-pressure easy to clean. This enables full separator (CHPS) may be adequate High-pressure amine absorption catalyst utilisation and thermal for smaller-capacity units (see Feed with a higher sulphur content uniformity across the catalyst bed, Figure 4). If the feed contains a results in the accumulation of H2S in so that the lowest possible SOR large percentage of cracked stock, the recycle gas loop. H2S inhibits temperature is achieved in which generates large exotherms in HDS reactions and lowers the purity conjunction with minimisation of a reactor catalyst bed, the use of the recycle gas and thus the the catalyst deactivation rate. of a hot, high-pressure separator partial pressure of hydrogen. A high The use of robust reactor internals (HHPS), with a gas component that H2S concentration in the recycle gas improves radial temperature distrib- will be routed to a CHPS via an air (typically >2–3 vol%) will influence ution and catalyst utilisation, which cooler/trim cooler, and a liquid catalyst selectivity in an undesirable ultimately translates into a better component routed to the stripping way. To compensate, a higher unit yield, longer catalyst life and more section, may be justified (see Figure pressure may be needed. A high efficient use of limited hydrogen 5). This facilitates enhanced heat sulphur content in the feed and resources. Some of the best-in- integration and lower air cooler ultra-low sulphur products may class reactor internals help to duty, but increases the hydrogen require an amine scrubbing system achieve less than 5°C radial loss and results in a higher capital in a recycle gas loop to prevent H2S temperature spread at the bottom of cost of the unit. build-up and improve catalyst deep catalyst beds. Additionally, Limited resources of hydrogen activity. The high-pressure amine tightly designed high-capacity necessitate further separation of absorber increases the partial trays and quench systems help to HHPS liquid to a hot, low-pressure pressure of hydrogen, which, in reduce reactor heights in multibed separator (HLPS) followed by a turns, results in lower operating and reactors. CLPS (see Figure 6). This process capital costs for the unit. 74 PTQ Q1 2010 www.eptq.com
  • 7. Additionally, it increases catalyst Hydrogen management life, reduces hydrogen losses Lower-purity (<85%) hydrogen through purge and requires lower make-up gas increases the design power consumption in the recycle pressure of the unit, and increases gas compressor because of the both the capital and operating costs increased purity of the gas. of the unit. A supply of high-purity hydrogen increases the partial Gas compression system pressure of the hydrogen in the The choice of recycle and make-up reactor in conjunction with a lower gas compressor depends on gas total operating pressure, and so purity. The make-up gas flow is results in lower operating and typically 25–40% of the recycle gas capital costs. Additionally, it flow. High-purity make-up gas increases catalyst selectivity, stability compression requires more stages. and overall cycle length. Optimis- The multistage reciprocating com- ation of the hydrogen system may pressor works well for this service. provide additional H2 availability, A sparing arrangement is necessary while avoiding capital investment. to ensure reliability and availability. Pressure swing adsorption or semi- The lower purity of make-up gas permeable membrane technology increases both the capital and could be considered for the operating cost of the compressor. purification of the H2 purge and The high purity of recycle gas make-up hydrogen streams from requires a lower gas circulation rate, the catalytic reforming unit. but the lower molecular weight of The cascading of H2 purge streams gas requires more head and for use as H2 make-up streams to potentially more compression other HDT units increases the purge stages. The recycle gas acts as a rate for higher recycle gas purity major heat sink in a reactor and and is more economical. Quench avoids excursion probability. hydrogen rates between the catalyst Typically, a centrifugal compressor beds should be minimised consistent is used for this service in view of its with safe operation, the ability to higher reliability and efficiency over maintain the required hydrogen a reciprocating compressor. partial pressure and desired catalyst life. stripping section The stripping section of a middle summary distillate hydroprocessing unit Hydroprocessing plays an increas- mainly removes H2S and light ingly important role in oil refining hydrocarbons from the hydrotreated and is key to the production of clean product and stabilises the product transportation fuels. Selection of the to meet the flashpoint specification. right technologies, the right combin- If lighter components are present in ation of high-activity catalysts, the feed, to offload the light appropriate reactor system arrange- products, distillation can be carried ment, operating conditions and out in two steps: H2S steam stripping advanced reactor internals provides at a higher pressure, followed by refiners with a range of advantages. lower-pressure stabilising. This will These include low operating and increase operational flexibility and capital costs, improved hydrogen enable the use of a smaller column utilisation, greater flexibility, more size with a low design pressure. scalability and high reliability for Use of heavy feed and less the processing of a range of cracking in the reactor means a feedstocks. standalone, low-pressure stripper Alpesh Gurjar is an Associate Process column can be employed. It may be Specialist at Fluor Daniel India Pvt Ltd. He one of two types: attached fired has six years’ experience in process design, reboiler or steam stripping. For technical services and operation of various kerosene and diesel boiling-range refinery hydroprocessing units. He has worked hydrocarbon, a fired heater reboiler with Essar Oil refinery and has a degree in is more suitable, as it is hard to chemical engineering from M S University of achieve a higher temperature Baroda, India. with steam. Email: alpesh_gurjar@yahoo.co.in www.eptq.com PTQ Q1 2010 77