Unit Unit name Capa Commi LicensorNo. City ssionedon09 Naphtha Splitter Unit1.15 18/03/98 M/S EIL

14 HydroTreater Unit0.56 19/05/98 M/s IFP, France

15 Catalytic Reformer Unit0.56 18/05/98 M/s IFP, France

17 Continuous Catalyst Regen. Unit M/s IFP, France

40 Nitrogen plant600NM3/hrM/s BHPV, Hyderadad

15X-1 Ammonia RefrigerationM/s Kirlosker,

UNIT PURPOSE NSU Feed preparation for HTUHTU Removal of Sulphur, Nitrogen, Oxygen from feed of CRU .CRU For production of high octane reformate (MS component) CCRU For burning coke from CRU catalyst.N2 To produce pure N2 for units.Ammonia To improve Hydrogen purity of recycle gas. Refrigeration

OBEJECTIVE OF CRUTo produce lead free Motor Sprit from Mathura Refinery. The purpose of CCRU type or Reforming Unit is to produce High Octane reformate as component of lead free Motor Spirit.

Design Capacity:0.466 MMT/Year based on 8000 hrs/y

FEED STOCK AND IMPURITIESFEED PREPARATION UNIT (NSU - 09)

SR NAPHTHA EX AVU (C5 -140)SEPERATES INTO C5-85 (LT NAPHTHA) AND 85-140 ( HY NAPHTA) IN NAPHTHA SPLITTER UNIT.TOP TEMP OF NSU IS MAINTAINED HIGHER SIDE TO SKIM BENZENE CONTENT WITH LIGHT NAPHTHA FOR PRODUCTION OF LOW BENZENE REFORMATE.HY NAPHTHA (85-140) FROM NSU BOTTOM IS FEED FOR HTU (HYDROTREATER UNIT)

CATALYST CONTAMINANTSTEMPORARY POISONS ARE THOSE WHICH CAN BE REMOVED FROM CATALYST WITHOUT SHUTDOWN. THEY ARE SULFUR, ORGANIC NITROGEN, WATER AND OXYGENATED ORGANICS AND HALOGEN.

PERMANENT POISONS ARE THOSE WHICH INDUCE A LOSS OF CATALYST ACTIVITY WHICH CAN NOT BE RECOVERED EVEN WITH THE REGENERATION AND MAY BE SO SEVERE THAT THE CATALYST MAY BE REPLACED.THE MAIN PERMANENT POISONS ARE ARSENIC, LEAD , COPPER , IRON , NICKEL AND CHROMIUM

HYDROTREATER UNIT( UNIT-14)TO PROTECT THE REFORMER CATALYST THE FEED HAS TO BE PRETREATED IN ORDER TO ELEMINATE THE FOLLOWING POISONS: S, N2, H20 , DIOLEFIN, ARSENIC AND METALS

BY HYDROREFINING REACTIONS WHERE MERCEPTANS, SULPHIDES AND DISULPHIDES EASILY REACT LEADING TO CORRESPONDING SATURATED AND AROMATIC COMPOUND R-SH+H2 -----> RH +H2S, R-S-R ------> RH +RH +H2S R-NH2+ H2 ----> R-H + NH3

HYDROTREAER UNIT( UNIT-14)HYDROGENATION REACTION CONVERTS THE DIOLEFINS, OLEFINS TO SATURATED COMPOUNDS

THE ARSENIC AND METAL COMPOUNDS ARE ABSORBED ON THE CATALYST ( NICKEL AND MOLYBDENUM CATALYST) LD-145 1.9 M3 HR 348) 19.1 M3

CATALYTIC REFORMINGCATALYTIC REFORMING IS A MAJOR CONVERSION PROCESS HAVING APPLICATIONS IN PETROLEUM REFINING AND PETROCHEMICAL INDUSTRIES IT TRANSFORMS LOW OCTANE NAPTHA TO :-

HIGH OCTANE MOTOR GASOLINE BLENDING STOCKPRODUCE AROMATIC CONCENTRATES RICH IN BENZENE, TOLUENE & XYLENE (BTX)

CATALYTIC REFORMINGBY PRODUCTS

H2 RICH CRU GAS USED AS MAKE-UP FOR HYDROTREATING, AND TO PRODUCE H2 THROUGH PSA-140 MAKING MORE ECONOMIC VIABLE PROCESS.LPG (NOT GENERATED AT PRESENT)

bOCTANE NUMBER OF HYDROCARBONS

OCTANE NUMBER IS A MEASUREMENT OF ANTI-KNOCK CHARACTERISTICS OF FUELS.

AMONG THE SAME CARBON NUMBER COMPOUNDS THE ORDER OF RON (RESEARCH OCTANE NUMBER) IS PARAFFINS < NAPHTHENES < AROMATICS.

BRANCHED PARAFFINS ALSO HAVE HIGH OCTANE. IT INCREASES WITH DEGREE OF BRANCHING.

THEREFORE OCTANE NUMBER OF NAPHTHA CAN BE IMPROVED BY REFORMING THE HYDROCARBON MOLECULE (MOLECULAR REARRANGEMENT). SUCH REARRANGEMENT TAKES PLACE IN REFORMING REACTORS IN PRESENCE OF CATALYST BY WAY OF NUMBEREOUS COMPLEX REACTIONS.

cOCTANE NUMBER OF VARIOUS HYDROCARBONS

n Butane 94.0 IButane 102.0 nPentane 61.8 lPentane 93.0 nHeptane 0.0 loctane100.0Toluene119.7INDEX = A+0.85NTHE HIGHER THIS INDEX, THE LOWER THE SEVERITY OF OPERATION TO MEET THE SAME PRODUCT SPECIFICATION. THE LOWER THIS INDEX (I.E. HIGHER THE PARAFFINS) THE HIGHER THE SEVERITY OF OPERATION TO MEET THE SAME PRODUCT SPECIFICATIONS, AS THE DEHYDROCYCLIZATION OF PARAFFINS BECOMES IMPORTANT.

OCTANE N- HEPTANE 0.0

2-METHYL HEXANE 42.4

3-METHYL HEXANE 56.0

2,2-DIMETHYL PENTANE 89.0

2,3-DIMETHYL PENTANE 91.4

2,4 - DIMETHYL PENTANE 83.1PARAFFINS

OCTANE

1-HEPTENE 54

3-HEPTANE 84

OLEFINAROMATIC

PHENYL GROUP120

PROCESS VARIABLES (INDEPENDENT VARIABLE)PRESSURETEMPERATURESPACE VELOCITYHYDROGEN PARTIAL PRESSURE or H2/HC RECYCLE RATIOQUALITY OF FEED

CRU PROCESS VARIABLES AND THEIR EFFECTS

INCREASED

RON

REFOR- MATE YIELD

COKE DEPOSIT

PRESSURE

TEMP

SPACE VELOCITY

H2/HC RATIO

NAPTHA

QUALITY

A+0.85 N

END BOILING POINT

INITIAL BOILING POINT

REFORMING CATALYSTA REFORMING CATALYST LIKE OTHER CATALYST MUST POSSESS FOLLOWING PROPERTIES

ACTIVITYSELECTIVITYSTABILITYREGENERABILITYCOST EFFECTIVE

CATAYLYST ACTIVITYFOR MOTOR FUEL REFORMING ACTIVITY IS GENERALLY REPRESENTED BY THE TEMP REQUIRED TO PRODUCE A GIVEN OCTANE NUMBER REFORMATE. THE LOWER THE TEMP, THE MORE ACTIVE THE CAT.

THE HIGHER THE SPACE VELOCITY, THE MORE ACTIVE THE CAT.

eSELECTIVITYIN CATALYTIC REFORMING SELECTIVITY OF THE CAT. MEANS THE PERCENT OF DESIRED PROD YIELD FROM THE FEED STOCK.IN MOTOR FUEL REFORMING A HIGH YIELD OF REFORMATE OF THE DESIRED OCTANE NUMBER IS GOOD SELECTIVITY.IN BENZENE, TOLUNE, XYLENE OPERATION, A HIGH YIELD OF BENZENE, TOLUNE, XYLENE AROMATICS IS GOOD SELECTIVITY.A CATALYST CAN HAVE GOOD ACTIVITY BUT HAVE POOR SELECTIVITY. THE P&T CATALYST WILL HAVE ACTIVITY AND GOOD SELECTIVITY.

STABILITY

STABILITY IS GENERALLY MEASURED BY THE AMOUNT OF FEED TREATED PER UNIT WEIGHT OF CATALYST( M3 OF FEED PER KG OF CATALYST)

IT IS CHIEFLY THE COKE DEPOSIT WHICH AFFECTS STABILITY THROUGH ITS INHIBITION OF THE CATALYST ACIDITY AND DECREASE IN METAL CONTACT AREA.

REACTIONS IN CATALYTIC REFORMING

FOLLOWING ARE THE MOST PREVALENT MAIN REACTIONS IN CATALYTIC REFORMINGDEHYDROGENATION OF NAPHTHENES TO AROMATICSISOMERISATION OF PARAFFINS AND NAPHTHENESDEHYDROCYCLISATION OF PARAFFINS TO AROMATICSHYDROCRACKING OF PARAFFINS TO LOWER MOLECULAR WEIGHT COMPOUNDS

A. DEHYDROGENATION OF NAPTHHENES TO AROMATICSPRINCIPAL REACTION PRODUCING AROMATICS FROM NAPHTHENES+3H2 oNAPHTHENE (ON = 83) o AROMATIC (ON =>100)(CYCLOHEXANE)ALKYL CYCLOHEXANE QUICKLY DEHYDROGENATE THAN ALKYL CYCLO PEN.METHYL CYCLOHEXANE RESULTS AN INCREASE OF 45.2 RON ON DEHYDROGENATIONDEHYDROGENATION REACTIONS INCREASE WITH INCREASE IN TEMPERATURE AND DECREASE IN PRESSUREHIGHLY ENDOTHERMICPROMOTED BY THE METALLIC FUNCTION OF THE CATALYST

B. ISOMERISATION OF PARAFFINS & NAPHTHENES

IN ISOMERISATION OF PARAFFINS THE MOLECULAR REARRANGEMENT TAKES PLACE WITH NO CHANGE IN MOLECULAR WEIGHT WITH SUBSTANTIAL IMPROVEMENT IN OCTANE NUMBERISOMERISATION RATE IS FAVOURED BY INCREASE IN TEMPERATURE.H3C CH2 CH2 CH2 CH2 CH3 CH3 CH CH2 CH2CH3

N Paraffin(HEXANE) CH3 RON 25 2 METHYL PENTANE ISO Paraffin(RON 73)

ISOMERISATION REACTIONS ARE REVERSIBLE AND MILDLY EXOTHERMICEQUILIBRIUM IS READILY ATTAINED BETWEEN PARAFFINS AND ISOPARAFFINS AND MAINLY DEPENDS UPON TEMPERATURE, PRESSURE HAS NO EFFECT.REACTIONS ARE PROMOTED BY THE ACIDIC FUNCTION OF THE CATALYST

DEHYDROCYCLISATION OF PARAFFINS (cont)THIS IS A MULTIPLE STEP REACTION, WHICH CONVERTS NORMAL OR ISO-PARAFFIN TO AROMATICS AND GIVE A NOTICEABLE INCREASE IN OCTANE NUMBER.MOST DESIRABLE BUT DIFFICULT REACTION IN REFORMINGFAVOURED AT LOW PRESSURE AND HIGH TEMPMINIMUM SIX CARBON CHAIN IS NEEDED TO CYCLISE TO FORM AROMATICSLONGER CHAIN PARAFFINS DEHYDROCYCLISE FAST, HOWEVER THE TENDENCY OF PARAFFINS TO HYDROCRACK, INCREASES CONCURRENTLY.REACTION IS PROMOTED BY BOTH CATALYTIC FUNCTION (METALLIC AND ACIDIC)

DEHYDROGENATIONTOLUENEMETHYL CYCLOHEXANED. DEHYDROGENATION OF PARAFFINCYCISAtionCH3CH3CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CHC7H14CH2CH2CH-CH3CH2CH2CH23H2 +CH3

D. DEHYDROGENATION OF PARAFFINMOST DESIRABLE BUT DIFFICULT REACTION IN REFORMING.FAVOURED AT LOW PRESSURE AND HIGH TEMP.MINIMUM SIX CARBON CHAIN IS NEEDED TO CYCLISE TO FORM AROMATICS.LONGER CHAIN PARAFFINS DEHYDROCYCLISE FAST, HOWEVER THE TENDENCY OF PARAFFINS TO HYDROCRACK, INCREASES CONCURRENTLY.REACTION IS PROMOTED BY BOTH CATALYTIC FUNCTION. (METALLIC AND ACIDIC)

HYDROCRACKING

RUPTURE OF CARBON TO CARBON BOND WITH REVERSIBLE FORMATION OF LOWER MOLECULAR WEIGHT PARAFFINS.RCH2 CH2 C H3 + H2 RH + CH3 CH2 CH3N PARAFFINPARAFFIN

HYDROCRACKING IS EXOTHERMIC.THESE REACTIONS ARE UNDESIRABLE DUE TO DECREASE IN . REFORMATE YIELD.FAVOURED BY INCREASE IN TEMPERATURE AND PRESSURE.HYDROCRACKING PRODUCE COKE PRECURSOR AND REDUCE . THE CATALYST ACTIVITY.REACTIVITY OF PARAFFINS HYDROCRACKING INCREASE WITH CARBON CHAIN.THE MAIN REACTIONS INVOLVED IN REFORMING ARE CATALYZED EITHER BY THE SUPPORT OR THE METAL FUNCTIONS AS INDICATED BELOW.

CATALYSIS MECHANISMTHE MAIN REACTIONS INVOLVED IN OCTANIZING ARE CATALYSED ESSENTIALLY BY THE SUPPORT OR THE METAL FUNCTIONS AS INDICATED BELOW ::

DEHYDROGENATION - METALLIC FUNCTIONDEHYDROCYCLIZATION - METALLIC+ACIDIC FUNCTION ISOMERIZATION - ACIDIC FUNCTIONHYDROCRACKING - METALLIC FUNCTIONHYDROGENOLYSIS - METALLIC FUNCTION

MAIN OCTANIZING REACTIONSTHE MAIN OCTANIZING REACTIONS TAKE PLACE IN THE VARIOUS REACTORS IN THE FOLLOWING ORDER,

1ST REACTOR 2ND REACTOR 3RD REACTOR

DEHYDROGENATION DEHYDROGENATION CRACKINGISOMERIZATION ISOMERIZATION--CRACKING-- DEHYDROCYCLIZATION DEHYDROCYCLIZATION

OCTANIZING REACTIONSHEAT OF REACTION -- RELATIVE RATE OF REACTIONREACTIONSHEAT OF REACTIONK CAL / MOLERELATIVE RATE

NAPHTHENESDEHYDROGENATION-5030

PARAFFINSDEHYDROCYCIZATION-601 (BASE)

ISOMERIZATIONPARAFFINS +2+4NAPHTHENE 3

CRACKING+100.51) HEAT OF REACTION < 0 = ENDOTHERMIC REACTION2) FOR PRESSURE BELOW 10 BAR

PRESSUREHYDROGEN PARTIAL PRESSURE IS THE BASIC VARIABLE OF ITS EFFECT ON REACTION RATES.DEHYDROGENATION, DEHYDROCYCLISATION ARE ENHANCED BY LOW PRESSURE.THE LOWER THE PRESSURE THE HIGHER THE YIELDS BOTH REFORMATE & HYDROGEN FOR OCTANE NUMBER.LOWER PRESSURE INCREASES IN COKE MAKE.OPERATING PRESSURE RISE INCREASES DESIGN PRESSURE OF EQUIPMENTS.

TEMPERATURECATALYST ACTIVITY IS DIRECTLY RELATED TO REACTOR TEMP. TEMPERATURE ADJUSTMENT IS REQUIRED FOR

TO CHANGE THE REFORMATE OCTANETO PROCESS A DIFFERENT FEED QUALITYTO BALANCE A TEMPORARY LOSS OF ACTIVITY DUE TO TEMPORARY POISONINGTO BALANCE CATALYST AGEING WHICH OCCURS SLOWLY OVER SEVERAL YEARS

SPACE VELOCITYWEIGHT HOURLY SPACE VELOCITY WHSV =WT OF FEED/ WT OF CATALYST

LIQUID HRLY SPACE VELOCITY=VOL OF FEED PER HOUE/VOL OF CATALYST

HYDROGEN TO HYDROCARBON RATIO AND HYDROGEN PARTIAL PRESSUREH2/HC = PURE H2 (MOLE/HOUR) INRECYCLE/ NAPHTHA FLOW RATE( MOLE /HOUR)A LOWER H2/HC RATIO DECREASES THE HYDROGEN PARTIAL PRESSURE AND INCREASES COKE FORMATION

FEED QUALITYN + 2A OR 0.85N +A IS MORE REPRESENTATIVE

THE HIGHER THIS INDEX, THE LOWER THE SEVERITY OF OPERATION TO MEET THE SAME PRODUCT SPECIFICATION. THE LOWER THIS INDEX (I.E. HIGHER THE PARAFFINS) THE HIGHER THE SEVERITY OF OPERATION TO MEET THE SAME PRODUCT SPECIFICATIONS, AS THE DEHYDRACYCLIZATION OF PARAFFINS BECOMES IMPORTANT.

FEED QUALITYLIGHT NAPHTHA HAVE POOR NAPHTHENIC AROMATIC CONTENT AND CONSEQUENTLY A HIGH C6 PARAFFINIC CONTENTCYCLISATION OF C6 PARAFFINNS TO AROMATICS IS MORE DIFFICULT THAN CYCLISATION OF C7 OR C8 PARAFFINESHEAVY FRACTIONS HAVE HIGH NAPHTHENIC AND AROMATIC HYDROCARBON CONTENT THUS NEED LOW SEVERITY TO OBTAIN GOOD YIELDSTHE HIGHER FRACTIONS ALSO CONTAINS POLY CYCLIC COMPOUNDS WHICH PRODUCE HIGH COKE DEPOSITS ON THE CATALYST

HTU process variablesThe hydrotreater reactions favoured by increasing temperature with increase in cock deposition on catalyst.Optimum temperature has been choosen 290 340 oC for new catalyst and end of cycle.

Space velocityLSHV = Hourly feed flow rate M3/hr at 15 oCVol. of catalyst in M3 Space velocity is inversely proportional to residence time. A low liquid hourly space velocity favours hydrogeneration. A change of feed quantity will change space velocity and reactor temperature for same severity.

H2 partial pressure (H2/Hc ratio)

H2/Hc ratio = H2 in recycle gas M3/hr Naphtha feed M3/hr

Increase in H2 partial pressure favours Hydrogeneration and reduce polimerisation & cock deposition.H2 partial pressure may be increased by increasing make up gas or by increasing recycle flow.FEED QUALITY :Higher olifine content in the feed will result in higher exothermicity across reactor with high coke deposits.

STRIPPER BOTTOM TEMPERATURE:To low temperature of stripper reboiler can lead to H2S and water slippage to avoid this stripper temperature to be maintained as specified.

CHEMICAL REACTIONS: The different kinds of Reactions that occur in hydrotreating are: Hydrorefining reactionsHydrogenation reactions

Hydrorefining reactions:

DesulfurizationMercaptides, sulphides and disulfides easily react, leading to the corresponding saturated or aromatic compounds:R-SH + H2RH + H2SR-S-R' + 2H2RH + R'H + H2SR-S-S-R' + 3H2RH + R'H + 2H2S

Sulfur combined into cycles of aromatic structure, like thiophene, is more difficult to eliminate. + 4H2 C4 H10 + H2S

S Thiophene De-NITRIFICATION:Nitrogen compounds inhibit considerably the acidic function of the reforming catalyst. They are eliminated by production of ammonia. The nitrogen compounds of SR naphtha are methylpyrol and quinoline. HCCH+ 4H2C5H12 + NH3 HC C-CH3N Methyl pyrrol n-Pentane Ammonia

QuinolineBenzenePropane

Nitrogen elimination is practically complete. The total Nitrogen content in the product is less than 0.5 PPM

+C3H8+NH3

HYDRO-DEOXYGENATION:Oxygen or oxygen compounds modify the acidic function of the reforming catalyst. They are eliminated by production of water. The oxygen compounds of straight-run are peroxides and phenols.

Oxygen is almost completely transformed into water.

HCHCHCOHCH+ H2HCHCCHHCCHCH+ H2OCHPhenolBenzene

HYDROGENATION:1)Olefinic hydrocarbons at high temperature provoke coke deposit on the reformer catalyst as well as in the furnace coils. If present in small quantities, they are eliminated by transformation to paraffins. The reaction is highly exothermic. Olefinic compounds are normally absent in straight run products.Olefins and Di-olefins are converted into saturated compounds;Cn + H2n Cn H2n+2 (highly exothermic)

2)Aromatic hydrogenation occurs as a consequence of temperature and hydrogen partial pressure. But combined with the H2S partial pr., the use of selected catalyst allows the limitation of these hydrogenation reactions. Less than 1% wt. of aromatics of the feed are hydrogenated in the hydrotreater.

Elimination of arsenic and METALS:

Arsenic, lead, mercury, sodium and to lesser degree Cu, Ni, Fe damage permanently the reforming catalyst. These compounds are adsorbed on the catalyst.

E.HYDROCRACKING

RUPTURE OF CARBON TO CARBON BOND WITH REVERSIBLE FORMATION OF LOWER MOLECULAR WEIGHT PARAFFINS.

RCH2 CH2 C H3 + H2 RH + CH3 CH2 CH3 N PARAFFINPARAFFIN

HYDROCRACKING IS EXOTHERMIC.THESE REACTIONS ARE UNDESIRABLE DUE TO DECREASE IN REFORMATE YIELD.FAVOURED BY INCREASE IN TEMPERATURE AND PRESSURE.HYDROCRACKING PRODUCES COKE PRECURSORS AND REDUCES THE CATALYST ACTIVITY.REACTIVITY OF PARAFFINS FOR HYDROCRACKING INCREASES WITH CARBON CHAIN.

THE MAIN REACTIONS INVOLVED IN REFORMING ARE CATALYZED EITHER BY THE SUPPORT OR THE METAL FUNCTIONS AS INDICATED BELOW.