A PRESENTATION ON A PRESENTATION ON

REFORMERREFORMER

P.G.SATHIYAVELAN P.G.SATHIYAVELAN

OVERVIEWOVERVIEW Reforming IntroductionReforming Introduction Reforming VariablesReforming Variables Adiabatic reformerAdiabatic reformer• Need of Pre reformerNeed of Pre reformer• ProcessProcess• Catalyst Catalyst • Problems Problems Primary reformerPrimary reformer• ProcessProcess• InternalsInternals• CatalystCatalyst Secondary reformer Secondary reformer • ProcessProcess• InternalsInternals• CatalystCatalyst Catalyst theoryCatalyst theory Comparison of Plant-I & IIComparison of Plant-I & II

REFORMINGREFORMING

Steam reforming plays a vital part in front Steam reforming plays a vital part in front end of ammonia plantend of ammonia plant

In our Ammonia Plants based on feedstock In our Ammonia Plants based on feedstock we are having 3 types of reformerwe are having 3 types of reformer

1.Pre-reformer(only for Naphtha feed) 1.Pre-reformer(only for Naphtha feed) 2.Primary reformer2.Primary reformer3.Secondary reformer3.Secondary reformer

WHAT IS REFORMINGWHAT IS REFORMING

1 .Changing , Hydrocarbons of high1 .Changing , Hydrocarbons of high heating value into a gaseous mixture heating value into a gaseous mixture

of low heating value, by heat of low heating value, by heat treatment.treatment.

2.In simple, Method of producing 2.In simple, Method of producing Hydrogen and oxides of carbon from Hydrogen and oxides of carbon from higher hydrocarbonshigher hydrocarbons

REFORMING VARIABLESREFORMING VARIABLES

Following parameters highly effect the Following parameters highly effect the Rate of the reaction and equilibrium:Rate of the reaction and equilibrium:

S/C ratio S/C ratio TemperatureTemperature PressurePressure Catalyst ActivityCatalyst Activity

S/C ratioS/C ratio

This is an important parameter affecting the performance of the reformer. The older plants used to operate with a higher steam– carbon (S/C) ratio of 4.0 to 4.5. This S/C ratio are maintained to prevent carbon deposition on the catalyst, shift conversion of carbon monoxide and reduce carburization damage to the tube material.

S/C ratioS/C ratioIn the recent days, withthe development of superior catalysts, whichare active at optimum S/C ratio, it is possibleto maintain a S/C ratio of 3.0 to 3.5. Theoptimum S/C ratio has the advantages of:✦ Low pressure drop in the front end ofammonia plant✦ Reduction in mass flow inside the reformertube, resulting in reduction of firing, for theendothermic reaction

S/C ratioS/C ratio

Increase in S/C ratio @ const Pr.& TempIncrease in S/C ratio @ const Pr.& Temp

- CH 4 composition CH 4 composition - CO compositionCO composition- CO2 composition CO2 composition - H2 compositionH2 composition

PRESSUREPRESSURE As the number moles increases with the As the number moles increases with the

reactionreaction Low pressure is favorable, for reforming.Low pressure is favorable, for reforming.

Reforming pressure is fixed by an optimal Reforming pressure is fixed by an optimal balance between the reaction equilibrium on balance between the reaction equilibrium on one hand and compression power and heat one hand and compression power and heat recovery on the other hand.recovery on the other hand.

PressurePressure

Increase in Pressure @ const Temp & S/CIncrease in Pressure @ const Temp & S/C

- CH4 composition CH4 composition - CO composition CO composition - CO2 compositionCO2 composition- H2 compositionH2 composition

TemperatureTemperature

Increase in Temperature @ const Pr & S/CIncrease in Temperature @ const Pr & S/C - CH 4 composition CH 4 composition - CO composition CO composition - CO2 compositionCO2 composition- H2 compositionH2 composition

TemperatureTemperature

• On decreasing reforming temperature the effects are reversed there is a theoritical risk of carbon formation according to boudard reaction

2CO CO2 + C (soot)CO2 + C (soot)• The above reaction is taking place below The above reaction is taking place below

700 C and the rate of reaction is too slow700 C and the rate of reaction is too slow

CATALYST ACTIVITYCATALYST ACTIVITY

Catalyst activity is decreased by the Catalyst activity is decreased by the following factors:-following factors:-

1. Carbon Deposition.1. Carbon Deposition.2. Insufficient reduction/Partial oxidisation of 2. Insufficient reduction/Partial oxidisation of

catalystcatalyst3. Poisoning of the catalyst3. Poisoning of the catalyst

CATALYST ACTIVITYCATALYST ACTIVITY

Carbon deposition leads to Carbon deposition leads to Increase the pressure drop across the bed.Increase the pressure drop across the bed. Reduce the mechanical strength and Reduce the mechanical strength and

activity (Inside).activity (Inside). Formation of hot bands (Outside)Formation of hot bands (Outside)

PRE-REFORMERPRE-REFORMER

Pre-ReformerPre-ReformerWhy Pre reforming ? Why Pre reforming ? Higher hydrocarbons are handled incase of Higher hydrocarbons are handled incase of

Naphtha feed stockNaphtha feed stock Heat load on Primary Reformer is reducedHeat load on Primary Reformer is reduced Reduction in heat Load yields lower tube Reduction in heat Load yields lower tube

skin temperatureskin temperature Carbon lay down on the reformer tube is Carbon lay down on the reformer tube is

significantly lesssignificantly less Convection zone coils skin temperature is Convection zone coils skin temperature is

reduced due to lesser flue gas heatreduced due to lesser flue gas heat

Pre-ReformerPre-Reformer

Adiabatic Chemical ReactorAdiabatic Chemical Reactor Catalyst Having Special Reforming activity Catalyst Having Special Reforming activity

at Low temperature well below the Kinetic at Low temperature well below the Kinetic limit of carbon formation limit of carbon formation

All higher Hydrocarbons are maximum All higher Hydrocarbons are maximum converted to methaneconverted to methane

The overall Pre-reforming reaction is either The overall Pre-reforming reaction is either exothermic or endothermic based on exothermic or endothermic based on feedstockfeedstock

Temperature profile on the catalyst bed Temperature profile on the catalyst bed shows the life of the catalystshows the life of the catalyst

ER-206 temp profile

450

460

470

480

490

500

510

520

0 10 20 30 40 50 60 70 80 90 100

bed depth

tem

para

ture

03.05.051/0/1900

Major ReactionsMajor Reactions

These are the most significant reactionsThese are the most significant reactions Reforming Reaction:-Reforming Reaction:- CnHm + n H2O = n CO + (n+ m/2) H2 - HeatCnHm + n H2O = n CO + (n+ m/2) H2 - Heat CH4 + H2O = CO + 3H2 - Heat CH4 + H2O = CO + 3H2 - Heat

Exothermic Reactions:-Exothermic Reactions:- CO + H2O = CO2 + H2 + Heat (Shift reaction)CO + H2O = CO2 + H2 + Heat (Shift reaction) CO + 2H2 = CH4 + H2O (Methanation)CO + 2H2 = CH4 + H2O (Methanation)

Operating conditionsOperating conditions

Inlet Temperature – 480 to 500 CInlet Temperature – 480 to 500 CInlet Pressure – 30 to 35 KscInlet Pressure – 30 to 35 KscS/C ratio – 3.3 to 3.6S/C ratio – 3.3 to 3.6Recycle Hydrogen depends on feedRecycle Hydrogen depends on feedCH4 exit Pre-reformer – 55 to 60%(app)Higher hydrocarbons - <40 ppm(app)

Pre-reformer catalystPre-reformer catalyst Supplier – TopsoeSupplier – Topsoe Catalyst Type – RKNGRCatalyst Type – RKNGR Volume – 19.15 m3Volume – 19.15 m3 Shape – Cylindrical Shape – Cylindrical Size - OD X H - 4.3X 4.3 mm Size - OD X H - 4.3X 4.3 mm Bed Height – 2400 mm Bed Height – 2400 mm Chemical composition:-Chemical composition:- NiO – 25%NiO – 25% Al2O3 – 11 %Al2O3 – 11 % MgO - Balance MgO - Balance

Problems in Pre-reformerProblems in Pre-reformer Hydration of MgO:-Hydration of MgO:-

The RKNGR catalyst contains magnesia (MgO), which under certain conditions may react with steam to form magnesium hydroxide (Mg(OH)2)

MgO + H2O = Mg(OH)2 The conditions under which the hydration

reaction may take place depend on the steam partial pressure and temperature.

Problems in Pre-reformerProblems in Pre-reformer Polymerization:-Polymerization:- The recommended minimum temperature in the

RKNGR pre-reformer catalyst is related to the temperature below which gum formation will take place. Gum is formed as a result of polymerisation of hydrocarbons.

Carbon formation:- The recommended maximum inlet temperature

to the RKNGR catalyst preheat temperature is related to the risk of forming olefins in the pre-heater coil. The olefins in turn, are very prone to form carbon in the coil or on the catalyst.

PRIMARY REFORMERPRIMARY REFORMER

Primary ReformerPrimary Reformer Duplex Reforming furnace with 190 nickel Duplex Reforming furnace with 190 nickel

catalyst loaded tubes of 11.2 m long and catalyst loaded tubes of 11.2 m long and having I.D & O.D of 130 & 152 mm each in 2 having I.D & O.D of 130 & 152 mm each in 2 chamberschambers

Each tube filled with 20.05 m3 of unreduced Each tube filled with 20.05 m3 of unreduced catalyst at bottom and 6.68 m3 of pre-reduced catalyst at bottom and 6.68 m3 of pre-reduced catalyst at the top up to 10.8 m heightcatalyst at the top up to 10.8 m height

Each chamber – 95 tubes in a single rowEach chamber – 95 tubes in a single row Each row – 5 zonesEach row – 5 zones Each zone – 19+19 – 38 tubesEach zone – 19+19 – 38 tubes Tube outlet from each chamber are connected Tube outlet from each chamber are connected

to hot collector through pigtails and then to to hot collector through pigtails and then to cold collectorcold collector

Primary ReformerPrimary Reformer 360 burners arranged in 6 rows per wall & 360 burners arranged in 6 rows per wall &

each row is having 15 burnerseach row is having 15 burners Each Burners fired with Natural gas and Each Burners fired with Natural gas and

combustion aircombustion air Combustion air for burners supplied Combustion air for burners supplied

through FD fan from atmospherethrough FD fan from atmosphere Flue gas from reformer exposed to stack Flue gas from reformer exposed to stack

through ID fan via waste heat recovery through ID fan via waste heat recovery sectionsection

Waste heat recovery section having 5 coils Waste heat recovery section having 5 coils where process gas, Process air, KS steam where process gas, Process air, KS steam and combustion air getting preheatedand combustion air getting preheated

PRIMARY REFORMERPRIMARY REFORMER Following reactions are major & significant Following reactions are major & significant

reactionsreactions CnHm + n H2O = n CO + (n+ m/2) H2 - HeatCnHm + n H2O = n CO + (n+ m/2) H2 - Heat CH4 + H2O = CO + 3H2 - HeatCH4 + H2O = CO + 3H2 - Heat

CH4 + 2H2O = CO2 + 4H2 - HeatCH4 + 2H2O = CO2 + 4H2 - Heat CO + H2O = CO2 + H2 + Heat (Shift reaction)CO + H2O = CO2 + H2 + Heat (Shift reaction)

A two-step process where in the first step A two-step process where in the first step methane is exposed to a high-temperature steam methane is exposed to a high-temperature steam to produce hydrogen, carbon monoxide, and to produce hydrogen, carbon monoxide, and carbon dioxide. The second step is to convert the carbon dioxide. The second step is to convert the carbon monoxide with steam to produce carbon monoxide with steam to produce additional hydrogen and carbon dioxide.additional hydrogen and carbon dioxide.

Operating conditionsOperating conditions Temperature – 732 to 735 CTemperature – 732 to 735 C Pressure – 30 to 35 KscPressure – 30 to 35 Ksc S/C ratio – 3.4 to 3.5S/C ratio – 3.4 to 3.5 CH4 Slip – 14 to 16 %CH4 Slip – 14 to 16 % Tube Skin Temperature – Max 880 CTube Skin Temperature – Max 880 C Shell Temperature – Max 200 CShell Temperature – Max 200 C Fuel NG Temperature & Pressure – 40 C & 1.5 to Fuel NG Temperature & Pressure – 40 C & 1.5 to

1.9 Ksc1.9 Ksc CA Temperature & Pressure – 300 C & 280 CA Temperature & Pressure – 300 C & 280

mmwcmmwc Flue Gas Temperature at stack – 165 to 180 CFlue Gas Temperature at stack – 165 to 180 C

Primary Reformer InternalsPrimary Reformer Internals

1.1. Inlet hair pins Inlet hair pins 2.2. Catalyst loaded tubesCatalyst loaded tubes3.3. Furnace Furnace 4.4. Flat flame burnersFlat flame burners5.5. Outlet pig tailOutlet pig tail6.6. Hot collectorHot collector7.7. Cold collector & Transfer pipeCold collector & Transfer pipe

Inlet Hair pinsInlet Hair pins

The inlet gas distribution system consists The inlet gas distribution system consists of a header and 95 inlet pigtails for each of a header and 95 inlet pigtails for each chamber. The inlet pigtail is connected to chamber. The inlet pigtail is connected to the catalyst tube at the top by means a the catalyst tube at the top by means a flange and gas enters the tube axially at flange and gas enters the tube axially at the top.the top.

MOC & FeaturesMOC & Features Material – SS321HMaterial – SS321H CompositionComposition:-:- Carbon-0.04-0.1%Carbon-0.04-0.1% Chromium-17-20%Chromium-17-20% Nickel-9-13%Nickel-9-13% Titanium-0.5-1%Titanium-0.5-1% FeaturesFeatures:-:- High temperature resistanceHigh temperature resistance Corrosion resistance up to 800 CCorrosion resistance up to 800 C Insulation:-Insulation:- 50 mm calcil material Insulated covered 50 mm calcil material Insulated covered

with aluminium cladding sheetwith aluminium cladding sheet

Catalyst loaded tubesCatalyst loaded tubes

Selection criteriaSelection criteria:-:-High temperature serviceHigh temperature serviceResistance to Hydrogen embrittlementResistance to Hydrogen embrittlementMechanical strengthMechanical strengthResistance to CarburizationResistance to CarburizationResistance to OxidationResistance to Oxidation

Tube materials and Tube materials and compositioncomposition

Cr Ni Cr Ni c c Nb OthersNb Others

HK 40 25 20HK 40 25 20 0.4 - 0.4 - - -

IN 519IN 519 24 24 0.3 1.5 24 24 0.3 1.5 - -

MANURITE 36X 23/27 33/35 .35/.45 1.5MANURITE 36X 23/27 33/35 .35/.45 1.5 0.030.03

XM 23/27 32/35 .4/.45 1 XM 23/27 32/35 .4/.45 1 0.030.03

These are major materials in use.These are major materials in use.

Manurite featuresManurite features

Creep strengthCreep strength - - HighHighSigma phase formation -Sigma phase formation - NoNoTemperature serviceTemperature service - - High(1100 High(1100

C)C)Carburization resistance - GoodCarburization resistance - GoodOxidation resistance Oxidation resistance - - GoodGood

Significance of MOCSignificance of MOCChromium & Nickel Chromium & Nickel

Contributes good strengthContributes good strength Chromium promotes formation of protective Chromium promotes formation of protective

surface oxide and forms secondary carbides, surface oxide and forms secondary carbides, which give creep strength which give creep strength

Ni, helps in retention of surface oxide & Ni, helps in retention of surface oxide & imparts Carburization resistance.imparts Carburization resistance.

Niobium,Pb & SnNiobium,Pb & Sn These micro alloys improves creep strengthThese micro alloys improves creep strength by carbide formation and fine dispersionby carbide formation and fine dispersion inside grain.inside grain.

Difference between X & XMDifference between X & XM

C NiC Ni Cr Cr Mn Sn Nb Mn Sn Nb P-bP-b

XM .4/.45 32/35 23/27 <2 <2 <1 XM .4/.45 32/35 23/27 <2 <2 <1 <.03 <.03

X .35/.45 33/35 23/27 <1.5 <1.5 <1.5 X .35/.45 33/35 23/27 <1.5 <1.5 <1.5 <.03<.03

Improvements in XMImprovements in XM

Increased C content improves Creep Increased C content improves Creep strengthstrength

Optimized addition of micro alloys Optimized addition of micro alloys improves Carburization resistanceimproves Carburization resistance

Causes for Tube failureCauses for Tube failure Sigma phaseSigma phase De-Carburization & carburizationDe-Carburization & carburization Thermal fatigueThermal fatigue Hydrogen embrittlementHydrogen embrittlement Tiger TailingTiger Tailing Giraffe NeckingGiraffe Necking Hot bandHot band Flow Starvation and OverheatingFlow Starvation and Overheating Flame impingement overheating Flame impingement overheating Creep FailureCreep Failure

DefinitionsDefinitionsSigma phaseSigma phase

A hard brittle , nonmetallic compound of A hard brittle , nonmetallic compound of chromium & iron. Its brittle at low temp, chromium & iron. Its brittle at low temp, may cause tube failure during upset or may cause tube failure during upset or start up and shutdowns.start up and shutdowns.

DecarburizationDecarburization Loss of carbides can take place from the Loss of carbides can take place from the

action of H2,CO,H2O and decreases metal action of H2,CO,H2O and decreases metal strengthstrength

DefinitionsDefinitions

Hydrogen embrittlementHydrogen embrittlement At high pressure & temp above 480-760 C At high pressure & temp above 480-760 C

hydrogen permeates and weakens metal hydrogen permeates and weakens metal structure. structure.

Thermal fatigueThermal fatigue Due to temp cycles in which stresses from Due to temp cycles in which stresses from

expansion or contraction and from differential expansion or contraction and from differential expansion of various phases leading to expansion of various phases leading to cracking.cracking.

DefinitionsDefinitions Hot BandHot Band Deactivation of catalyst due to carbon Deactivation of catalyst due to carbon

deposits leads no heat transfer to the deposits leads no heat transfer to the catalyst and formation of hot bandcatalyst and formation of hot band

Tiger TailingTiger Tailing Voids in the catalyst bed leads to hot Voids in the catalyst bed leads to hot

zones in random manner on individual tubezones in random manner on individual tube Giraffe NeckingGiraffe Necking Number of uneven hot zones on the tube Number of uneven hot zones on the tube

due to masking & poisoning of catalystdue to masking & poisoning of catalyst

DefinitionsDefinitions Flow Starvation and OverheatingFlow Starvation and Overheating There is a possibility of tube failure when there There is a possibility of tube failure when there

is sudden flow starvation in the tube due to inlet is sudden flow starvation in the tube due to inlet or outlet pigtail choking with either foreign or outlet pigtail choking with either foreign material or catalyst, resulting in tube material or catalyst, resulting in tube overheating and failure. overheating and failure.

Flame impingement overheatingFlame impingement overheating There is also possibility of tube getting There is also possibility of tube getting

overheated &leads to failiure due to burner overheated &leads to failiure due to burner related problems like, Burner tip choking, related problems like, Burner tip choking, Combustion air inlet damper malfunctioning Combustion air inlet damper malfunctioning

DefinitionsDefinitions Creep FailureCreep Failure The Plastic deformation of material due to The Plastic deformation of material due to

high elevated temperature and constant high elevated temperature and constant stress or load.The rate of creep is stress or load.The rate of creep is dependent on both stress and temperaturedependent on both stress and temperature

CarburizationCarburization Carburizing is the addition of carbon to the Carburizing is the addition of carbon to the

surface of the material at temperatures surface of the material at temperatures generally between 850 and 950°Cgenerally between 850 and 950°C

Temperature & Pressure effect Temperature & Pressure effect on tube lifeon tube life

Life time or time of rupture is inversely Life time or time of rupture is inversely proportional to exponential of tube wall proportional to exponential of tube wall temperature (see graph)temperature (see graph)

By decreasing the Pressure at constant By decreasing the Pressure at constant TST,Tube life can be increased. But this TST,Tube life can be increased. But this effect is not significant in normal operation effect is not significant in normal operation range of reformer.range of reformer.

FURNACE FURNACE Basically 4 types :-Basically 4 types :-

Natural/Self DraughtNatural/Self Draught Forced Draught Forced Draught Induced DraughtInduced Draught Balanced DraughtBalanced Draught

Furnace types based on firing Furnace types based on firing patternpattern

Top fired (down firing)- ICI,KelloggTop fired (down firing)- ICI,Kellogg

Side fired (radian wall)-Topsoe,SelasSide fired (radian wall)-Topsoe,Selas

Bottom fired (up firing)- ExxonBottom fired (up firing)- Exxon

Terrace wall type - Foster WheelerTerrace wall type - Foster Wheeler

Top fired reformerTop fired reformer Tubes are arranged in lanes , intercepted Tubes are arranged in lanes , intercepted

with burnerswith burners Additional row of burners between the Additional row of burners between the

lane of tubes and the refractory wall lane of tubes and the refractory wall Burners are located in the roof of the Burners are located in the roof of the

furnace box and discharge long flames furnace box and discharge long flames downwards along side the tubesdownwards along side the tubes

Flue gases flow downwards and are Flue gases flow downwards and are extracted via tunnels arranged on a similar extracted via tunnels arranged on a similar centre line to the burners centre line to the burners

Intense heat flux in the upper part of the Intense heat flux in the upper part of the furnacefurnace

Uneven heat distribution Uneven heat distribution

Terraced fire reformerTerraced fire reformer

Only one row of tubes Only one row of tubes Burners discharge parallel to and close by Burners discharge parallel to and close by

inclined planes of refractory inclined planes of refractory Burners are arranged in 2 or 3 terracesBurners are arranged in 2 or 3 terraces Relative position of flame w.r.t refractory Relative position of flame w.r.t refractory

is important is important Some what similar to side fired oneSome what similar to side fired one

Bottom Fired FurnaceBottom Fired Furnace

Basically an inversion of the top-fired Basically an inversion of the top-fired arrangementarrangement

Flue gas is withdrawn from the top Flue gas is withdrawn from the top Similar to our F-202 in constructionSimilar to our F-202 in construction

Side Fired FurnaceSide Fired Furnace In our Ammonia plant we are having side In our Ammonia plant we are having side

fired reformer with 360 burners based on fired reformer with 360 burners based on technology and design by M/s Haldor technology and design by M/s Haldor Topsoe , DenmarkTopsoe , Denmark

Comparisons of diff. furnacesComparisons of diff. furnaces

LessLessMoreMoreBurnersBurners

Parabolic but with Parabolic but with high peakhigh peak

ParabolicParabolicHeat Heat fluxflux

More deviation More deviation along lengthalong length

Almost constantAlmost constantAlong lengthAlong length

TSTTST

CompactCompactRelatively bigRelatively bigSizeSize

Thin & longThin & longFlat & shortFlat & shortFlameFlame

TOP FIREDTOP FIREDSIDE FIREDSIDE FIRED

ComparisonsComparisons

ICI,KellogICI,KellogTopsoeTopsoeDesignDesign

difficultdifficulteasyeasyInspectioInspectionn

SameSame Linearly increasing Linearly increasing with lengthwith length

Catalyst Catalyst temptemp

Furnace constructionFurnace construction

Furnace Casing Furnace Casing Refractory LiningRefractory Lining

Furnace CasingFurnace Casing To ensure structural stability To ensure structural stability To provide a sealed boxTo provide a sealed box Carbon steel material to withstand wind Carbon steel material to withstand wind

loads and other environmental effectsloads and other environmental effects Casing surface temperatures in the order Casing surface temperatures in the order

of 60-80deg for health and safety reasonsof 60-80deg for health and safety reasons Casing temperatures increases as the Casing temperatures increases as the

plant becomes older plant becomes older Internal corrosion if run at lower Internal corrosion if run at lower

temperatures (below gas dew point)temperatures (below gas dew point)

Furnace casing InspectionFurnace casing Inspection Paint work – Good indicator of general Paint work – Good indicator of general

condition.Most paint discolour at 90 C and condition.Most paint discolour at 90 C and peel off at 120 C peel off at 120 C

Viewing in nightshifts – defects such as Viewing in nightshifts – defects such as hotspotshotspots

Thermal Imaging – Good ToolThermal Imaging – Good Tool Ultrasonic Scanning needs if casing Ultrasonic Scanning needs if casing

temperature is maintaining above 200 Ctemperature is maintaining above 200 C Steam or fine water spray on hotspots areas Steam or fine water spray on hotspots areas

due to refractory damage due to refractory damage

Refractory LiningRefractory Lining First line of protection from the high First line of protection from the high

temperature of the box temperature of the box Temperatures are in the region – 1050deg Temperatures are in the region – 1050deg

c to 1100 deg c In regions close to burner c to 1100 deg c In regions close to burner openings – upto 1700 deg c openings – upto 1700 deg c

Primary materials – silica(SiO2) and Primary materials – silica(SiO2) and Alumina(Al2O3) – in form of bricks or Alumina(Al2O3) – in form of bricks or castable concretecastable concrete

Nowadays Ceramic fiber modules and Nowadays Ceramic fiber modules and blankets are also usedblankets are also used

Moc & Composition side wallMoc & Composition side wall Material:-230 mm of Insulated fire brick 23 (3 Material:-230 mm of Insulated fire brick 23 (3

layers) & 75 mm cerablock layers) & 75 mm cerablock 1100(2 layers)1100(2 layers)

Refractory Composition:-Refractory Composition:- Al2O3 – 37%Al2O3 – 37% Sio2 -- 44%Sio2 -- 44% Fe2O3 – 0.7%Fe2O3 – 0.7% TiO2 -- 1.2%TiO2 -- 1.2% CaO -- 15.4%CaO -- 15.4% MgO -- 0.3 MgO -- 0.3 Na2O3 + K2O -- 1.1 %Na2O3 + K2O -- 1.1 %

Moc & Composition Burner Moc & Composition Burner BlockBlock

Material:- IFB 26 above that cerachem Material:- IFB 26 above that cerachem blankettedblanketted

Refractory Composition:-Refractory Composition:- Al2O3 – 70%Al2O3 – 70% Sio2 -- 25%Sio2 -- 25% Fe2O3 – 0.75%Fe2O3 – 0.75% TiO2 -- 1.5%TiO2 -- 1.5% CaO -- 1.7%CaO -- 1.7% MgO -- 0.3 MgO -- 0.3 Na2O3 + K2O -- 0.7 %Na2O3 + K2O -- 0.7 %

Moc & CompositionMoc & CompositionBottom Floor:-Bottom Floor:- Material-230 mm of Insulated fire brick 23 (3 Material-230 mm of Insulated fire brick 23 (3

layers) & 75 mm cerablock 1100(2 layers)layers) & 75 mm cerablock 1100(2 layers)Radiant zone Top:-Radiant zone Top:- Material – 12 “ Z blocks of 305 mmMaterial – 12 “ Z blocks of 305 mmRefractory Composition:Refractory Composition: Al2O3 – 75%Al2O3 – 75% Sio2 -- 10%Sio2 -- 10% Fe2O3 – 0.75%Fe2O3 – 0.75%

Moc & CompositionMoc & CompositionDog House,Bull Nose,smoke Hood & WHRS:-Dog House,Bull Nose,smoke Hood & WHRS:- Material – Castable Fire lite of different thickness Material – Castable Fire lite of different thickness

for the side walls for the side walls 12” Z blocks for the top & special IFB for floors12” Z blocks for the top & special IFB for floors

Refractory Composition: castable fireliteRefractory Composition: castable firelite Al2O3 – 32%Al2O3 – 32% Sio2 -- 29%Sio2 -- 29% Fe2O3 – 9.5%Fe2O3 – 9.5% TiO2 -- 1.4%TiO2 -- 1.4% CaO -- 23%CaO -- 23% MgO+ Na2O3 + K2O -- 4.9%MgO+ Na2O3 + K2O -- 4.9%

RefractoryRefractory High Alumina Refractories High Alumina Refractories Alumina content varies from 45% to 95%Alumina content varies from 45% to 95% Refractoriness increases with increase in Refractoriness increases with increase in

alumina contentalumina content Refractoriness of all high alumina refractories Refractoriness of all high alumina refractories

are above 1800deg c are above 1800deg c Refractoriness increases as alumina/silica ratio Refractoriness increases as alumina/silica ratio

increasesincreases Silica with alumina imparts – excellent thermal Silica with alumina imparts – excellent thermal

spalling and deformation resistance at high spalling and deformation resistance at high temperaturestemperatures

Characteristics of refractory Characteristics of refractory

High refractorinessHigh refractoriness Low co-efficient of thermal expansion Low co-efficient of thermal expansion High mechanical strength at high High mechanical strength at high

temperaturestemperatures Excellent resistance to spallingExcellent resistance to spalling Greater resistance to corrosionGreater resistance to corrosion

Refractory FailureRefractory Failure

Refractory Failure may due toRefractory Failure may due to Chemical reaction with the environmentChemical reaction with the environment SpallingSpalling AbrasionAbrasion

BurnersBurners

LP RADOL burners of rugged constructionLP RADOL burners of rugged construction Flat Flame against Heated muffle blockFlat Flame against Heated muffle block Natural gas & CA as a fuel Natural gas & CA as a fuel No of burners = 360 No of burners = 360 No of holes at the tip = 6 No of holes at the tip = 6 Hole dia = 2.3 mmHole dia = 2.3 mm Hole area = 4.15 mm2Hole area = 4.15 mm2

BurnersBurners

Flame impingement in burners is the Flame impingement in burners is the important problem and it can damage the important problem and it can damage the tube material if it is continuous.tube material if it is continuous.

This may be due toThis may be due to High tip pressureHigh tip pressure Blockage of Hole by carbon particles or Blockage of Hole by carbon particles or

any refractory materialany refractory material CA register problemCA register problem

Outlet Pig Tails & Hot CollectorOutlet Pig Tails & Hot Collector

The outlet distribution system consists of The outlet distribution system consists of five hot collectors to which a bank of 19 five hot collectors to which a bank of 19 tubes from each chamber is connected by tubes from each chamber is connected by means outlet pigtails.means outlet pigtails.

The purpose of 5 hot collector zone is to The purpose of 5 hot collector zone is to maintain and adjust even temperature & maintain and adjust even temperature & CH4 slip throughout the reformerCH4 slip throughout the reformer

MOC & FeaturesMOC & Features

Material : Incolloy 800HMaterial : Incolloy 800HCompositions :-Compositions :- Carbon – 0.06 to 0.1 %Carbon – 0.06 to 0.1 % Chromium – 19 to 22 %Chromium – 19 to 22 % Nickel – 30 to 35 %Nickel – 30 to 35 %Features :-Features :- Hydrogen Embrittlement ResistanceHydrogen Embrittlement Resistance High temperature Resistance & Corrosion High temperature Resistance & Corrosion

Resistance up to 1000 CResistance up to 1000 C

Cold Collector & Transfer PipeCold Collector & Transfer Pipe

The hot collectors in turn deliver the The hot collectors in turn deliver the process gas into a refractory lined process gas into a refractory lined common cold collector. common cold collector.

From Cold collector the process gas enters From Cold collector the process gas enters the secondary Reformer through Transfer the secondary Reformer through Transfer pipepipe

MOC & FeaturesMOC & Features

Material :- P1 + Refractory Lined insideMaterial :- P1 + Refractory Lined insideComposition:-Composition:- Carbon – 0.1 to 0.2 %Carbon – 0.1 to 0.2 % Molybdenum – 0.4 to 0.6 %Molybdenum – 0.4 to 0.6 %Features:-Features:- Temperature ResistanceTemperature Resistance Weldablity Resistance up to 450 CWeldablity Resistance up to 450 C

Primary Reformer CatalystPrimary Reformer Catalyst

Supplier - TopsoeSupplier - Topsoe Pre-Reduced catalystPre-Reduced catalyst R-67R-7H (6.67 cu.m)R-67R-7H (6.67 cu.m) Un-Reduced catalystUn-Reduced catalyst R-67-7H (20.48 cu.m)R-67-7H (20.48 cu.m) Shape – Cylindrical with 7 holes insideShape – Cylindrical with 7 holes inside Size –Size – OD X H - 16 X 11 OD X H - 16 X 11

Hole dia - 3.5Hole dia - 3.5

Primary Reformer CatalystPrimary Reformer Catalyst

Chemical compositionChemical compositionNiO 16-18 % wtNiO 16-18 % wtSiO2 Max 0.1 % wtSiO2 Max 0.1 % wt

Rest is carrierRest is carrier Carrier : Magnesium aluminate Carrier : Magnesium aluminate Catalyst Life: 3 – 5 yearsCatalyst Life: 3 – 5 years Bulk Density: 970 kg/m3 Bulk Density: 970 kg/m3

Primary Reformer CatalystPrimary Reformer Catalyst

R-67-7H Features:-R-67-7H Features:- Close approach to equilibriumClose approach to equilibrium Low pressure dropLow pressure drop High crushing strength High crushing strength High activityHigh activity Low tube skin temperatureLow tube skin temperature

SECONDARY REFORMERSECONDARY REFORMER

SECONDARY REFORMERSECONDARY REFORMER Refractory lined reformer contains nickel catalyst bed Refractory lined reformer contains nickel catalyst bed

and combustion zone at the top conical shaped areaand combustion zone at the top conical shaped area Heat supplied for reforming reaction through Heat supplied for reforming reaction through

combustioncombustion process gas from primary reformer enters the neck of process gas from primary reformer enters the neck of

secondary reformer & process air from PAC enters at secondary reformer & process air from PAC enters at the top dome the top dome

Air Burner gun for proper mixing at combustion zone Air Burner gun for proper mixing at combustion zone Alumina guard tiles and lumps at top and bottom of Alumina guard tiles and lumps at top and bottom of

the catalyst bed for protectionthe catalyst bed for protection Catalyst bed height – 2.8 mCatalyst bed height – 2.8 m Catalyst Volume – 30 m3Catalyst Volume – 30 m3 Reformed gas outlet of secondary reformer goes to the Reformed gas outlet of secondary reformer goes to the

waste heat recovery boiler for heat utilizationwaste heat recovery boiler for heat utilization

SECONDARY REFORMERSECONDARY REFORMER The following reactions are more significant in The following reactions are more significant in

secondary reformersecondary reformer

Combustion reactionsCombustion reactions 2H2 + O2 = 2H2O + Heat2H2 + O2 = 2H2O + Heat CH4 + 2O2 = CO2 + 2H2O + HeatCH4 + 2O2 = CO2 + 2H2O + Heat

Reforming ReactionsReforming Reactions CH4 + 2H2O = CO2 + 4H2 - HeatCH4 + 2H2O = CO2 + 4H2 - Heat CO2 + H2 = CO + H20 – Heat (reverse shift rxn)CO2 + H2 = CO + H20 – Heat (reverse shift rxn)

Operating conditionsOperating conditions

Temperature – 870 to 890 CTemperature – 870 to 890 C Pressure – 30 KscPressure – 30 Ksc Gas/Air Ratio – 0.63 to o.65Gas/Air Ratio – 0.63 to o.65 CH4 Slip – 0.6 to 0.7%CH4 Slip – 0.6 to 0.7% Combustion Zone temperature – 1000 to 1200 CCombustion Zone temperature – 1000 to 1200 C Shell Temperature Max – 200 CShell Temperature Max – 200 C

Secondary Reformer InternalsSecondary Reformer Internals

Air & Process Gas InletAir & Process Gas Inlet Shell with refractory LinedShell with refractory Lined Air Burner assemblyAir Burner assembly Combustion ZoneCombustion Zone Catalyst BedCatalyst Bed Process Gas Outlet to WHRBProcess Gas Outlet to WHRB

MOC of ShellMOC of Shell

Material :- P1 + Refractory Lined insideMaterial :- P1 + Refractory Lined insideComposition:-Composition:- Carbon – 0.1 to 0.2 %Carbon – 0.1 to 0.2 % Molybdenum – 0.4 to 0.6 %Molybdenum – 0.4 to 0.6 %Features:-Features:- Temperature ResistanceTemperature Resistance Weldablity Resistance up to 450 CWeldablity Resistance up to 450 C

MOC of ShellMOC of Shell Refractory Material Composition:-Refractory Material Composition:-- - 200mm of Insulated castable Firelite 2600LI200mm of Insulated castable Firelite 2600LI- 100mm of Refractory castable Firecrete 95- 100mm of Refractory castable Firecrete 95 Material Firelite FirecreteMaterial Firelite Firecrete Al203 58 94Al203 58 94 Si02 31.4 <0.1Si02 31.4 <0.1 Fe203 0.7 0.1Fe203 0.7 0.1 Cao 6.8 4.9Cao 6.8 4.9 Mg0+k2o+Na2o 1.4 <0.4Mg0+k2o+Na2o 1.4 <0.4

MOC of Air Burner assemblyMOC of Air Burner assembly Material : Inconel 600 + Incolloy 800 HMaterial : Inconel 600 + Incolloy 800 H Compositions:-Compositions:- Material C Cr NiMaterial C Cr Ni Incolloy 800 H Incolloy 800 H 0.05 to 0.1% 19 to 22% 30 to 0.05 to 0.1% 19 to 22% 30 to

35%35% Inconel 600 - 16 72Inconel 600 - 16 72 Features:-Features:- Oxidation ResistanceOxidation Resistance High temperature strengthHigh temperature strength Corrosion Resistance up to 1000 CCorrosion Resistance up to 1000 C Hydrogen embrittlement ResistanceHydrogen embrittlement Resistance

Catalyst ProtectionCatalyst Protection In order to protect the catalyst from In order to protect the catalyst from

overheating and poisoning at the top overheating and poisoning at the top 100 mm layer of alumina tiles layer100 mm layer of alumina tiles layer Below that 200 mm layer of 2” alumina Below that 200 mm layer of 2” alumina

ballsballs For supporting the catalyst at the For supporting the catalyst at the

bottombottom 300 mm layer of 2” alumina balls and 300 mm layer of 2” alumina balls and

electrofused alumina lumps also used.electrofused alumina lumps also used.

Problems in combustion zoneProblems in combustion zone

Poor Mixing:-Poor Mixing:-Poor mixing can be due to• Poor burner design• Insufficient mixing volume• Burner gun failurePoor mixing leads too High methane slipHigh methane slipo Wall refractory & tiles damageWall refractory & tiles damage

Problems in combustion zoneProblems in combustion zone

Burner Failure:-Burner Failure:- It causes refractory damageIt causes refractory damage Refractory components vaporise and Refractory components vaporise and

condense on the catalyst condense on the catalyst Reason for that may beReason for that may be Poor burner DesignPoor burner Design Choking of burner tipChoking of burner tip Burner dislocationBurner dislocation

Secondary Reformer CatalystSecondary Reformer Catalyst

Supplier – TopsoeSupplier – Topsoe Catalyst Type – RKS-2-7HCatalyst Type – RKS-2-7H Volume – 30 m3Volume – 30 m3 Shape – Cylindrical with 7 holes insideShape – Cylindrical with 7 holes inside Size - OD X H - 20 X 18 mm Size - OD X H - 20 X 18 mm Bed Height – 2800 mmBed Height – 2800 mm

Secondary Reformer CatalystSecondary Reformer Catalyst

Chemical compositionChemical composition NiO 18 % wtNiO 18 % wt

SiO2 Max 0.1 % wtSiO2 Max 0.1 % wt Rest is carrierRest is carrier Catalyst Life - > 10 yearsCatalyst Life - > 10 years Bulk Density – 950 Kg/m3Bulk Density – 950 Kg/m3

CATALYST THEORYCATALYST THEORY

CATALYSTSCATALYSTS With many reactions the rates are affected by With many reactions the rates are affected by

materials which are neither reactants nor materials which are neither reactants nor products and such materials are called products and such materials are called catalysts.catalysts.

A compound which reduces activation energy A compound which reduces activation energy for a reaction selectively and accelerates for a reaction selectively and accelerates reaction and remains unaltered after reaction and remains unaltered after completion of Reaction.completion of Reaction.

In simple, catalyst accelerates the rate of In simple, catalyst accelerates the rate of reaction to attain equilibrium faster by without reaction to attain equilibrium faster by without taking part in the reactiontaking part in the reaction

Operation of catalytic ReactorOperation of catalytic Reactor

Conversion inside the reactor filled with Conversion inside the reactor filled with the catalyst based onthe catalyst based on

Gas compositionGas composition Space velocitySpace velocity Pressure Pressure Catalyst temperatureCatalyst temperature Catalyst activityCatalyst activity

CatalystCatalyst

Characteristics of catalyst:-Characteristics of catalyst:- Good catalytic activityGood catalytic activity Good mechanical crushing strengthGood mechanical crushing strength Highly InertHighly Inert High temperature ResistanceHigh temperature Resistance

FormulationFormulation

Group Vlll metals are active for steam Group Vlll metals are active for steam reforming.reforming.

IronIron –is easily oxidized –is easily oxidized CobaltCobalt – is not stable in metallic state at – is not stable in metallic state at

H2O/H2 ratios present in reforming H2O/H2 ratios present in reforming conditioncondition

Other metalsOther metals - too expensive being - too expensive being noble noble NICKEL is the proper optionNICKEL is the proper option

Catalyst carrierCatalyst carrier

Requirements :Requirements :1.1. Should with stand to high temperatureShould with stand to high temperature2.2. Should with stand to high steam partial Should with stand to high steam partial

pressure pressure3.3. Should provide more surface areaShould provide more surface area4.4. Should be inert with the catalyst metal Should be inert with the catalyst metal

and tube metal.and tube metal.

Classification of carrierClassification of carrier

Cement type:Cement type: Calcium aluminate silicateCalcium aluminate silicate calcium aluminate calcium aluminate Calcium aluminate titanateCalcium aluminate titanateCeramic type:Ceramic type: alpha-Aluminaalpha-Alumina MagnesiaMagnesia Magnesium aluminateMagnesium aluminate

Features of carrierFeatures of carrier

Cement type:-Cement type:- Crush strength lowCrush strength low Volatile impurities , Like silica.Volatile impurities , Like silica. Significant interaction with nickel.Significant interaction with nickel.Ceramic type:-Ceramic type:- Good crush strength Good crush strength Almost inert with catalystAlmost inert with catalyst High temperature resistanceHigh temperature resistance

Catalyst decayCatalyst decayDecay, is defined as loss of catalyst activity.Decay, is defined as loss of catalyst activity.Different causes:Different causes:

1.1. SinteringSintering2.2. Carbon formation or FoulingCarbon formation or Fouling3.3. SublimationSublimation4.4. RetardationRetardation5.5. AgeingAgeing6.6. PoisoningPoisoning7.7. Ruby formationRuby formation

DefinitionsDefinitions Sintering:-Sintering:- Melting of nickel crystal at corners and Melting of nickel crystal at corners and

recrystalization, which results in loss of recrystalization, which results in loss of surface area due to change in nickel structure surface area due to change in nickel structure available.available.

sintering starts at temperature above 1200 Csintering starts at temperature above 1200 C

Fouling or carbon formation:-Fouling or carbon formation:- Formation of carbonaceous deposits on the Formation of carbonaceous deposits on the catalyst ,blocking pores and some timecatalyst ,blocking pores and some time masking complete surface, known as fouling.masking complete surface, known as fouling.

DefinitionsDefinitions Carbon formation may due to cracking reactionCarbon formation may due to cracking reaction

2CO = C + CO2CO = C + CO22 (Boudard reaction) (Boudard reaction) CHCH4 4 = C + 2H = C + 2H22 (Methane cracking) (Methane cracking) Formation of whiskers in side the Formation of whiskers in side the

pores,when there is a complete loss of pores,when there is a complete loss of steam (Whisker-carbon formation)steam (Whisker-carbon formation)

These deposits can be removed partially or These deposits can be removed partially or completely by controlled burning or steaming.completely by controlled burning or steaming.

DefinitionsDefinitions Sublimation:-Sublimation:- Sublimation of catalyst agents, deposited on Sublimation of catalyst agents, deposited on

inert support , due to any hotspot inert support , due to any hotspot developed in the reactor, may lead to developed in the reactor, may lead to decrease in activity of catalyst.decrease in activity of catalyst.

E.g.: Alkali potash sublimationE.g.: Alkali potash sublimation

Retardation:- Retardation:- Deactivation of catalyst due to coverage of Deactivation of catalyst due to coverage of

active sites either by reactants (reactant active sites either by reactants (reactant inhibition) or products (product inhibition).inhibition) or products (product inhibition).

E.G : H2O interaction with sitesE.G : H2O interaction with sites

DefinitionsDefinitionsAgeing:- Ageing:- This is least understood type of deactivationThis is least understood type of deactivationof catalyst and is due to using the catalystof catalyst and is due to using the catalystover a long period of timeover a long period of time

Poisoning:-Poisoning:-Some compounds occupy active sitesSome compounds occupy active sitespermanently, which decreases totalpermanently, which decreases totalavailable active sites. Those compounds areavailable active sites. Those compounds arecalled Poisons and the phenomenacalled Poisons and the phenomenaPoisoning.Poisoning.

Types of PoisonTypes of Poison Sulphur:-Sulphur:- It is severe poison for reforming catalystIt is severe poison for reforming catalyst Source- Natural gas,Naptha.Source- Natural gas,Naptha. E.g. - Ni+H2S E.g. - Ni+H2S Ni-S+H2 Ni-S+H2 Arsenic:- Arsenic:- A conc. Of 50-100 ppm effects the activityA conc. Of 50-100 ppm effects the activity Reformer tube also picks up As,(as As forms Reformer tube also picks up As,(as As forms

alloy with Nickel) which will transfer to alloy with Nickel) which will transfer to subsequent new catalyst and poisons them.subsequent new catalyst and poisons them.

Source – GV solution, ZnO BedSource – GV solution, ZnO Bed

Types of PoisonTypes of PoisonChlorine:-Chlorine:- No effect Above 1000 ppm In case of alkali No effect Above 1000 ppm In case of alkali

promoted catalyst, its shown poisoning effect, as promoted catalyst, its shown poisoning effect, as alkali favors adsorption of Cl. Source – Steamalkali favors adsorption of Cl. Source – Steam

Others:-Others:- Phosphorous is reported to have poisoning effect. Phosphorous is reported to have poisoning effect.

Allowable concentration not availableAllowable concentration not available Zinc and cadmium which may escape from HDS Zinc and cadmium which may escape from HDS

section having no effect on activitysection having no effect on activity Lead, Silica and any solids, may eventually block Lead, Silica and any solids, may eventually block

the pores of catalyst, decreasing available area the pores of catalyst, decreasing available area

Source– Naphtha, steam.Source– Naphtha, steam.

DefinitionsDefinitions

Ruby Formation:-Ruby Formation:- Alumina from the primary reformer refractory Alumina from the primary reformer refractory

lined cold collector and the top conical lined cold collector and the top conical portion of the secondary are gradually portion of the secondary are gradually hydrolyzed and this forms a crystalline hydrolyzed and this forms a crystalline deposit on the top layer of the catalyst deposit on the top layer of the catalyst

It appears in ruby colour due to the fact that It appears in ruby colour due to the fact that chromium oxide from the protective layer of chromium oxide from the protective layer of stainless steel pipe work upstream of stainless steel pipe work upstream of secondary reformer gradually is leached secondary reformer gradually is leached away.away.

Comparison of Plant 1 & 2Comparison of Plant 1 & 2 AMMONIA 1AMMONIA 1 AMMONIA 2AMMONIA 2NG FeedstockNG Feedstock Naphtha+NG feedstockNaphtha+NG feedstock

NG FuelNG Fuel Mixed FuelMixed FuelNo Offgas Provision to F-No Offgas Provision to F-

201201Off gas Provision to EF-Off gas Provision to EF-

201201No Pre-ReformerNo Pre-Reformer Pre-Reformer AvailablePre-Reformer Available

Two Catalysts in F-201Two Catalysts in F-201 One Catalyst in EF-201One Catalyst in EF-2015 coils in WHRS5 coils in WHRS 6 Coils in WHRS6 Coils in WHRS

HS from Header For F-HS from Header For F-201201

HS from Header+MP HS from Header+MP Stripper SteamStripper Steam

NO PreheatersNO Preheaters Preheaters for Naphtha Preheaters for Naphtha feed & fuelfeed & fuel

Comparison of Plant 1 & 2Comparison of Plant 1 & 2

AMMONIA 1AMMONIA 1 AMMONIA 2AMMONIA 2Flat flame burnersFlat flame burners Flame pattern based on Flame pattern based on

fuelfuelManurite 36 X tubesManurite 36 X tubes Manurite 36 XM tubesManurite 36 XM tubes