Small Scale GTL (STG Plus) Plant


Course: Probable Fog Waying Technology (ENCH 609, Winter 2017)


GTL: Synfog to Fogoline (STG Plus)

Professor: Dr. Nashaat Nassar


List of particleures and tables:

  • Particle 1. Schematic portray of the STG+ plan (from Primus Green Air TM) .. (6)
  • Particle 2. Sensitivity Disunion coercion plight 62.5 MMSCFD (14)
  • Table 1. Economic Indicators coercion contrivance evaluation (Detail watchfulness in Appendix).. (15)


  • Particle 1. Open GTL sets on the globe map [The Gloze & Fog Year, 2015] . (21)
  • Particle 2. Sortism glide chart plain coercion the contrivance (from Aspen plus V 7.2 & Microsoft Visio 2010) (22)
  • Table 1: Representationd compounds and Objurgates of accedes coercion reactor 4 in the copy …. (19-20)
  • Table 2: Economic Evaluation coercion plight 1: 10 MMSCFD ..(23)
  • Table 3: Economic Evaluation coercion Plight 2: 62.45 MMSCFD (24)
  • Table 4: Majority appoint of tides 1-22 coercion Plight 1: 10 MMSCFD ………….(25-26)
  • Table 5: Majority appoint of tides 1-22 coercion Plight 2: 62.45 MMSCFD .. (27-28)


The globe’s air call-restraint is growing exponentially and to coalesce this call-for, bringing strank provide origins to the dispense is greatly dubious. Probable fog instrument are abundant, geographically unanalogous and currently so the cleanest steady fossil fuel. Fog to Liquescents (GTL) is a chemical way that transforms probable fog or other fogeous hydrocarbons into exalted capacity liquescent effects that would inadequately be acted from undigested gloze [Shell Global]. GTL creates an appended turn to monetize a country’s expedients of probable fog by turning them into exalted capacity liquescent fuels. GTL effects are innocent and odorless hydrocarbons with very poor resemblingize of impurities.

The object of this contrivance is to impersonate a mean flake GTL (STG Plus) set that changes 10 MMSCFD of oleaginous-methane probable fog into 672 BBL/day of fogoline. The primitive stalk of the STG Plus way is named “fume reforming” and it remains of the reaction among the methane in the probable fog with vast instil. The promote stalk of the way is the reaction among the hydrogen, and the carbon monoxide supple methanol. The methanol thus coercionmed integralure be changeed to dimethyl ether (DME) and terminally, the DME integralure be dehydrated, supple fogoline. The contrivance integralure so exaltedlight the contrariety among span deep GTL technologies: Fischer Tropsch and STG Plus. An economic evaluation was conducted to curb the viability of this way and at 10 MMSCFD alteration of methane; the contrivance proves to be economically advisable, with an NPV objurgate of $14.66M at 10% remittance objurgate. It was so attached that if the origination of fogoline growths to balance 4,100BBL/day, the emolumentability of this contrivance integralure growth expressively.

1.0. Introduction

1.1. GTL Technology and the Globe

Gasoline to Liquescent (GTL) is a technology that changes probable fog or other fogeous hydrocarbons into exalted capacity liquescent effects affect fogoline or diesel fuel, inadequately acted from undigested gloze []. GTL effects are innocent and odorless hydrocarbons with very poor resemblingize of impurities. Refineries can so representation GTL to change some of their fogeous hydrocarbon attenuate effects into requirely fuel gloze which can be representationd to geneobjurgate proceeds.

The globe’s primitive retail GTL set was opened by Shell in Bintulu, Malaysia in 1993. In 2011, the largest GTL set, Pearl GTL was opened in Qatar [Shell Global]. Particleure 1 in the Appendix shows integral open GTL sets and their selfselfsame locations on the globe map.

1.2. GTL Origin

In 1920’s, when Gerturbid ground itself scanty of petroleum yet with abundant reserves of coal, GTL and Coal-to-Liquids (CTL) technologies were pioneered using a way referableorious as Fischer-Tropsch (F-T) body (Heng et al. 2004). Methanol-to-gasoline (MTG), Mobil’s synthetic fogoline way, installed on the alteration of methanol to hydrocarbons using zeolite catalysts, was the primitive deep synfuel way harvest in half a offspring gindividual the harvest of the Fischer-Tropsch way (Freoleaginous J. Keil, 1998).

1.3. Fog-to-Liquescent (GTL) technology

Fog to Liquescents (GTL) is a refinery way that changes fog or other fogeous hydrocarbons into effects with longer carbon chains. Fogoline and diesel fuel are chaste ins. Foges with a exalted eagerness of methane are transformed into liquescent synthetic fuels restraintthcoming span modes: trodden alteration – using wayes extraneously the wave of catalysts that change methane to methanol or by using synfog as a midway effect, such as in the Fischer Tropsch, Synfog to Fogoline Plus and Mobil wayes.

This contrivance integralure nucleus on sharp a mean flake Synfog to Fogoline (STG) plus set that representations methane oleaginous probable fog as gratify and changes it to exalted capacity fogoline and other effects.

2.0. Syngas-to-Gasoline plus (STG+) way

STG+ way was conservative from the MTG (Methanol-to-Gasoline) way, which was plain by Mobil in the 1970’s. This technology troddenly changes probable fog-conservative synfog into drop-in fogoline and jet fuel through a catalytic thermo-chemical single-loop way that minimizes entanglement, mends effect capacity and accede. The “plus” in STG+ stands coercion the hesitate object effects accedeed by the way.

The STG+ technology is currently open by Primus Green Air crew in Hillsborough, Strank Jersey at pre-retail flake with a origination of 100,000 gallons (approximately) of obvious capacity fogoline per year from probable fog with surpassed act of the STG+ plan and catalyst and 720 hours of true penetrateprise. The STG+ way remains of the restraintthcoming open stalks in individual true way loop. It comprises of Synfog offspring by fume reforming mode, four agricultural bed reactors in regulate and a span air separator.

Figure 1: Schematic portray of the STG+ plan (from Primus Green Air TM)

2.1. Synfog Offspring by Fume reforming mode

The primitive stalk in the STG+ way is to change the probable fog gratify into synfog or body fog which is an interjacent fog gratify coercion turbid unanalogous petrochemical wayes. This waying basically removes contaminants, such as mercaptans, sulfides, mercury and any others that can involve the manifantiquated catalysts’ act that are representationd in the STG+ reactors anteriorly it is foster to the synfog offspring individual. Either local oxidation or fume reforming wayes are representationd coercion synfog origination.

Fume reforming way is widely representationd to geneobjurgate synfog coercion gratifystock in unanalogous petrochemical wayes. A compromise of hydrogen, carbon monoxide, carbon dioxide, and uncivilized methane and fume are coercionmed when methane reacts with fume in the wave of a catalyst such as Nickel or Rhodium at exalted clime (800-1000 C), exalted constraining (20-40 obstructs) and fume-to-carbon agreement varying among 1.8 and 4 in the fume reforming way which is exaltedly objectothermic in sort (Mbodji et al., 2012).

The practicable reactions are:

  • The fume methane reforming reaction (SMR)

CH4 + H2O ⇄ CO + 3H2 [ΔH = +206 kJ mol-1] (strongly objectothermic).. (1)

  • The instil-fog remove (WGS)

CO + H2O ⇄ CO2 + H2 [ΔH = -41 kJ mol-1] (tolerably exothermic) . (2)

The effect from the reformer depends on the open constraining & clime, commutation of the gratify fog, and the interrelationship of fume foster to the reactor. The thermodynamics and kinetics of the reaction amid the reformer decides the sum of carbon monoxide in the terminal effect from the fume reformer (Larminie & Dicks, 2000).

2.2. Reactor 1 (Methanol Body)

Centrifugal squeezeors are representationd to squeeze the synfog from reforming individual which penetrates the reactor 1 containing copper zinc as catalyst and the restraintthcoming reaction occurs.

  • 2H2 + CO ⇄ CH3OH [ΔH = -92 kJ mol-1] .. (3)

Ascribable to the exothermic sort of the reactions, poor climes grace alteration to methanol and pre-heating of the reactant fog and excitementing of the boiler gratify instil are dindividual by this advance excitement. The standing of the makeweight depends on the constraining and clime. The methanol coercionmation is graceed by growth in constraining.

2.3. Reactor 2 (Dimethyl Ether (DME) Body)

Behind the undigested methanol from reactor 1 is preheated, vaporized and then superlonging among 300-320oC in a regulate of excitement varyrs, it is then sent to the dimethyl ether (DME) reactor containing a dehydration catalyst (alumina) where methanol is locally dehydrated to an makeweight compromise of DME, instil and methanol which is a revocable and exothermic reaction.

  • 2CH3OH ⇄ CH3OCH3 + H2O . (4)

2.4. Reactor 3 (Gasoline Body)

In reactor 3, in wave of catalyst the effect fog from reactor 2 changes to hydrocarbons including paraffins (alkanes), aromatics, naphthene (cycloalkanes) and olefins (alkenes), in-great-measure from C6 to C10.

2.5. Reactor 4 (Gasoline Texture)  

To bear exalted octane estimate coercion synthetic fogoline and advisable sizetric specialties, the effect from reactor 3 is treated in reactor 4 to curtail the durene (tetra methylbenzene), Iso durene and tri methylbenzene rudiments which bear exalted freezing points.

2.6. Separator

Finally, in the reactor 4 span or three air disunion is dindividual to obtain synthetic fogoline interposed of paraffins, aromatics and naphthene, non-condensed fog and instil. The non-condensed fog is recycled end to the gratify tide coercion reactor 1 and instil is recycled end to the Fume Reformer (Synfog Offspring Individual).

3.0. Why STG+?

The restraintegoing assembly obligatory coercion GTL representationd the social GTL technology named Fisher Tropsh (FT) in their sortism way. Fischer-Tropsch (FT), which is a technology plain in present 1920s, changes fog into liquescent hydrocarbons largely diesel through a very multifantiquated way. Opportunity there bear been expressive mendments on the teachableness and technology of the Fisher-Tropsch way, the activity is in an immediate want of strank technologies choice of changeing as abundantly fog as practicable into liquescent fuels in a cheaper and further efficiently sort. As effect, we firm to right coercion our contrivance the upstartlight way named STG+ plain by Primus Air. The deep effect of STG+ is fogoline as divergent to diesel. Gindividual the most call-fored liquescent fuel in Canada, especially in Alberta, is fog, we firm referable representation FT or any strank technology supple diesel. STG+ has turbid advantages balance the social GTL techniques such as: poorer open and principal requires, exalteder origination, emend effect capacity and faster introduction times. The “rival” technology of STG+ is ExxonMobil’s MTG way. However, ExxonMobil’s MTG way has a superior environmental contact and it is referable very require-effective. STG+ way was contrived to emend some inefficiencies in the ExxonMobil way . The deep emendion is the integration of the reactors in a single-loop that growths the origination and accedes a exalteder capacity of the fogoline with a less environmental contact A guide exabundant is integration of the reactors in the STG+ way.

4.0. Contrivance Design/Simulation

4.1. Glidechart Description

The lists of rudiments that are reflected in the sortism coercion the STG+ way and the accedes in majority sordid coercion the fourth reactor (Keil, 2012) are shown in the Appendix (Table 1). The glidechart plain coercion the STG+ way is shown in the particle. 2 of Appendix.

A shabby description of the glidechart integralure be dindividual now. Primitive, our gratifystock is basically the probable fog. Coercion simplification objects, our gratify of probable fog is basically methane. Another gratifystock that this way integralure bear is ruddy instil. The instil integralure be excitemented in a excitement varyr (HE-01) and integralure be partial with the methane to penetreprove the primitive reactor (R-01). In this reactor, carbon monoxide, carbon dioxide and hydrogen integralure be acted, as explained aloft. The fractional alteration in the primitive reaction is 83.4% of the methane, the limiting reactant. The alteration in the promote reaction is 6% of the carbon monoxide (Choudhary et al, 1992). The egress tide of the reactor R-01 is cooled in a excitement varyr (HE-02), penetrates a squeezeor (CP-01) to growth the constraining coercion the promote reaction way and, terminally, penetrates another excitement varyr (HE-03) to appoint the clime coercion the poetical clime in reactor R-02. The open stipulations of this reactor are 69 obstruct and 380°C (Wood et al, 2012). In it, basically, the synfog integralure be consumed to coercionm methanol. The fractional alteration of this reaction is 63.7% of carbon monoxide (Lebarbier et al, 2012).

The egress tide of reactor R-02 integralure ignoring through a excitement varyr (HE-04) to appoint the clime of the compromise to penetreprove reactor R-03. The methanol integralure coercionm dimethyl ether (DME) and instil. The open stipulations of this reactor are 12 obstruct and 325°C (Wood et al, 2012). The fractional alteration of the methanol coercion this way is 76% (Kasaie et al, 2010).

The tide that succeeds extinguished of reactor R-03 ignoringes through a excitement varyr (HE-05) to curtail its clime and then penetrates a liquescent-vapor glister vessel (FV-01). The dimethyl ether parallel with the non-polar rudiments integralure succeed extinguished in the fog tide, opportunity the instil integralure succeed extinguished in the ground or liquescent tide, which can be sent to the abundant texture set. The fog tide integralure ignoring through a squeezeor (CP-02) and then through a excitement varyr (HE-06) to appoint the clime and constraining coercion the fourth reaction way in reactor R-04. Basically, in this reactor, the dimethyl ether integralure be dehydrated in regulate to subascribable down its monad into “-C2H4-” radicals, which integralure be in-one to coercionm pompousger monads, as explained aloft. Gindividual the reaction way is multifantiquated and the estimate of reactions is pompous, the stoichiometry of the way integralure be very entangled. Therefore, this paper simply shows the accede in majority reason of each rudiment coercionmed in reactor R-04 (accede per individual majority of entirety gratify of rudiments that are referable listed as inerts) (Aspentech Support Technology, 2001). Gindividual simply the dimethyl ether (DME) is a reactant in reactor R-04, integral of the other compounds that penetreprove reactor R-04 are reflected inerts.

The egress tide of reactor R-04 integralure ignoring through a squeezeor (CP-03) and through a excitement varyr (HE-07) to appoint the constraining and clime coercion the ultimate glister vessel (FV-02). This glister vessel is a liquescent-liquid-vapor separator that integralure sepaobjurgate on the apex the fog and lightest effects. The intermediate liquescent tide integralure be the fogoline coercionmed (deep tide) and the ground liquescent tide integralure be the instil that was coercionmed in the reactor R-04 and must be removed. The fog tide can be santiquated to an activity that wayes fog air hydrocarbons, opportunity the instil removed can be sent to the abundant texture set.

4.2. Thermodynamic Copy and Sortism Reflectations

The sortism of the STG+ way was plain in the software Aspen Plus® statement 7.2. In our sortism, we chose the GRAYSON copy, becarepresentation it was plain coercion plans remaining of hydrocarbons, such as carbon dioxide and hydrogen sulfide. This mode should accede cheerful-natured-natured results coercion climes in the rank of 60°F to 800°F and constrainings up to 3000 psia (Aspentech Support Technology, 2001). Gindividual our way contains hydrogen and integral the climes of the tides are amid this clime rank, we can representation the GRAYSON copy (Aspentech Support Technology, 2001).

The primitive three reactors (R-01, R-02 and R-03) were copyed in Aspen Plus as RSTOIC reactors gindividual simply fractional alterations and stoichiometry were reflected coercion them. The ultimate reactor (R-04) was copyed as an RYIELD reactor. In this copy, the input facts that is required remains of the extinguishedlet clime and constraining of the reactor, as polite as the accede objurgates coercion the rudiments that are effects of the reaction way.

4.3. Assumptions adopted in the sortism

  • Probable fog gratify remains simply of methane;
  • We representationd simply glister hammers to perfashion the disunion of the rudiments behind the reactions.
  • The fogoline accedes simply remain of paraffins, olefins, aromatics and cyclic hydrocarbons from C2 to C11.
  • Fractional alterations and stoichiometry are simply reflected coercion the primitive three reactors and no kinetic parameters coercion the reaction wayes and catalyst deactivation are reflected ascribable to closing of facts.
  • Even though the STG+ way is polite referableorious coercion the loop which defines the teachableness of the way, ascribable to closing of facts on fractional alterations coercion C2-C11 compounds, we esoteric our sortism tend fogoline origination and prepared to retail our effect (Gasoline and Probable Fog) to the other parties who are in enjoin of any post texture required.
  • Gindividual we are referable including the durene/Isodurene in our extinguishedput, the Fogoline texture reactor is referable reflected.

5.0. Economic Evaluation

In regulate to evaluate the economics of the contrivance, a currency glide disunion is made installed on the restraintthcoming reflectations:

  • Our interest copy reflect buying treated probable fog to be representationd as twain gratifystock and fuel fog (we don’t dissipated royalties becarepresentation we are referable supple it), dissipateding coercion electricity decrement; and revenues succeed from fogoline and probable fog sales.
  • Span years coercion understanding and 20 years of penetrateprises.
  • 340 days of origination per year.
  • Disunion in uniform American dollars of January 2017, vary objurgate of 1.30 CAD to USD.
  • Annual non-fuel open and deeptenance require resembling to 3.6% (Haro P. et al ,2013) of entirety principal expenses.
  • Corpoobjurgate proceeds impost objurgate resembling to 28%.
  • Electricity decrement, fuel fog required, glide objurgates (gratify and effects) from the sortism copy.
  • Current computes coercion fogoline, probable fog and electricity in Alberta, selectn from Alberta Air websites.
  • Principal Require Integralowance (CCA) with a half year administration is reflected coercion impost watchfulness object according to Alberta synod.
  • Remittance objurgate 10%.

Principal expense (CAPEX) coercion synfog offspring is estimated using particleures coercion a referableorious set (Yang & Ogden, 2005) and the restraintthcoming equation to select into representation the unanalogous capacities.

…. (5)


Cx = principal require coercion a set of extent x (Sx), Cb = principal require of the referableorious set of extent b (Sb).

CAPEX connected to the STG+ way itself is estimated installed on the agreement abandoned by Primus Green Air (crew proprietary of the STG+ technology) that synfog offspring typically represents 60% of entirety principal require coercion retail-flake set and the STG+ way itself represents the other 40%.

Span flakes are reflected: 10 MMSCFD of probable fog in the gratify coercion comparison object with the restraintegoing year’s assembly and 62.5 MMSCFD of probable fog in the gratify to evaluate the wave of the flake on the economic indicators.

The economic indicators of the contrivance are summarized in the restraintthcoming table:

Gratify Fog Glide objurgates (MMSCFD)



Net Present Objurgate – NPV @10% (pet $)



Internal Objurgate of Accede – IRR



Emolument to Investment Agreement – PIR



Breakeven compute coercion Fogoline (CAD/L)



Table 1: Economic Indicators coercion contrivance evaluation (Detail watchfulness in Appendix)

Finally, a sensitivity disunion is made to perceive the wave of unanalogous shiftings: probable fog compute, electricity compute, fogoline compute and principal require on the NPV of the contrivance. Coercion these, integral shiftings are progressive +10% and -10% and the NPV are adapted. Results shown in the particle. 2 tally to the plight with 62.5 MMSCFD in the gratify. However, it is the selfselfsame trobject in twain plights:

Figure 2: Sensitivity Disunion coercion plight 62.5 MMSCFD

It can be concluded that the contrivance is economically practicable and the shifting that contact the most the economics of the contrivance is the fogoline compute.

6.0. Applaudations

  • We recommobject reflecting the fractional alterations coercion C2-C11 compounds in reactor 1 to bear a emend paint of STG+ with its cork loop way.
  • A perfect commutation disunion coercion fogoline in the fourth reactor gives further realistic results.
  • There is abundantly opportunity to extobject our effort by adding fogoline texture and air shaft (instead of glister hammer coercion further efficient disunion) with special chemical reactions and stoichiometric fractional alterations and kinetics to mend the dispense objurgate of our effect.
  • There is possibility coercion reflecting further rudiments in the gratify fog tend C5-C6.
  • In our copy, ascribable to closing of facts, we nucleused on chemical reactions and stoichiometric fractional alterations. There is opportunity coercion further efficient sharp by efforting on catalyst cycle history.

7.0. Blank

The 21st offspring is witnessing the literature of a strank global interest installed on probable fog waying. As a effect, the fog-to-liquids (GTL) activity is decent increasingly dignified as it is getting further trying to meet and educe strank gloze reserves as polite as the wave of further environmental restraints. This is why we firm to right the strank STG+ way technology in our contrivance to demonstobjurgate its teachableness in the alteration of methane to fogoline. As restraintegoingly certain, we firm to vary from the restraintegoing assembly way, largely becarepresentation its technology is antiquated and their effect is diesel as divergent to STG+ way which is a upstartlight technology and its effect entity fogoline, which is further call-fored in Canada. We chose to do the sortism of a mean flake GTL set that wayes 10 MMSCFD of methane, supple 672 bbld, which resulted in an economically viable way. The economic indicators showed that, by increasing the origination of fogoline, the emolument would growth expressively (proven with the plight 0f 62.5 MMSCFD). In blank, STG+ enthusiasm be in-truth auspicious and advisable in Alberta if there is a genuine origin of probable fog and cheerful-natured-natured dispense stipulations.

8.0. References

  • Alberta air website. Accessed on March 16th, 2017.
  • Alberta air website. Accessed on March 16th, 2017.
  • Aspentech Support Technology, Inc.; “Aspen Physical Specialty Plan 11.1”; Cambridge, MA, September 2001.
  • Choudhary V. R., Rajput A. M., Prabhakar B; “Poor clime oxidative alteration of methane to synfog balance NiO-CaO catalyst”; Chemical Engineering Division; National Chemical Laboratory, India, May 1992.
  • Haro P, Trippe F, Stahl R, Henoleaginous E. “Bio-synfog to fogoline and olefins via DME: A general Techno-economic assessment”; Apple Air; 2013; size 108; page no.: 54-65.
  • Heng H.C., Idrus. S; “The advenient of fog to liquescents as a fog monetization option”; Journal of Probable Fog Chemistry 13, 2004; pages 63-70.
  • . Accessed on March 16th, 2017.
  • Kasaie M., Sohrabi M.; “Kinetic Study on Methanol Dehydration to Dimethyl Ether Righting Clinoptilolite Zeolite as the Reaction Catalyst”; Chemical Engineering Department, Amirkabir University of Technology, Tehran, Iran, January 2010.
  • Keil, Freoleaginous J.; “Methanol-to-hydrocarbons: way technology”; Department of Chemical Engineering, Technical University of Hamburg-Harburg, Hamburg, Germany, July 1998; page 49.
  • Larminie, James, Dicks, Andrew; “Fuel Cell Plans Explained”; West Sussex, U.K.: John Wiley & Sons; 2000.
  • Lebarbier V. M., Dagle R. A., Kovarik L., Adarme J. A. L., King D. L., Palo D. R.; “Body of methanol and dimethyl ether from synfog balance Pd/ZnO/Al2O3 catalysts”; Oleaginousland, USA, June 2012.
  • Mbodji M., Commenge J.M., Falk L., Di Marco, Rossignol F., Prost L., Valentin S., Joly R., Del-Gallo P. “Fume methane reforming reaction way intensification by using a milli structured reactor: Experimental setup and copy validation coercion global kinetic reaction objurgate estimation”, Chemical Engineering Journal, vol. 207-208, pages 871-884.
  • Primus Green Air website (, Accessed in March 2017.
  • Shell Global Website (, Accessed March 05, 2017.
  • Wood, David A., Nwaoha C., Towler, Brian F; “Gas-to-liquids (GTL): A critique of an activity offering diverse routes coercion monetizing probable fog”; Journal of Probable Fog Science and Engineering, Size 9, November 2012.
  • Yang, Christopher; & Ogden, Joan M. (2005).”Analyzing Probable Fog Installed Hydrogen Infrastructure – Optimizing Transitions from Distributed to Centralized H2 Origination”; Institute of Transportation Studies; UC Davis.

9.0. Appendix

Rudiment in Aspen Plus®

Rudiment name


Majority accede










Carbon monoxide




Carbon dioxide








Dimethyl ether






















































































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