Gas-to-liquid Technology Research Articles

Assessing the lightning performance of sustainable GTL type dielectric liquids versus mineral oils and synthetic ester in a non-uniform electric field

This paper presents for the first time the results of complex comparative tests on the lightning performance of a wide range of sustainable electrical insulating liquids made in GTL (Gas-to-Liquids) technology. Three different GTLs are compared with conventional mineral oils (inhibited and uninhibited) as well as biodegradable synthetic ester. Tests are aimed to determine Lightning Impulse Breakdown Voltage (LIBV) and Acceleration Voltage (Va) at standard lightning impulse voltage of both polarities. Those are performed at 25 mm gap distance of point-sphere electrode setup representing non-uniform electric field distribution. In addition, light emission is studied as well. Results show that for the conditions of experiment LIBV values tend to be similar for all tested dielectric liquids with a slight advantage of mineral oils at negative polarity and GTL-I oil at positive polarity. In turn, in terms of Va, it was found that at negative polarity the GTL oils are, in general, fully comparable with a high grade inhibited mineral oil. The Va of GTLs is in the range 260–275 kV versus 255–260 kV that characterizes mineral oils. When considering positive polarity the GTL-I is slightly inferior to other hydrocarbons with Va equal to 195 kV versus 230–255 kV characterizing other GTLs and mineral oils. For both polarities tested synthetic ester has much lower acceleration voltage in relation to hydrocarbon liquids including GTLs, which constitutes a huge disadvantage of the ester. Although the studies are limited to only one gap distance and non-uniform electric field distribution, it can be stated that the GTLs are worth to be examined as alternative to mineral oil when considering LIBV and Va as the analysed quantities. In addition, a special added value of the performed measurements should be mentioned that the measurements confirmed that Va parameter may be a good dielectric indicator of a dielectric liquid performance, especially when examining new product introduced to the market.

Fisher–Tropsch Synthesis for Conversion of Methane into Liquid Hydrocarbons through Gas-to-Liquids (GTL) Process: A Review

The interest in Gas-to-Liquid technology (GTL) is growing worldwide because it involves a two-step indirect conversion of natural gas to higher hydrocarbons ranging from Liquefied Petroleum Gas (LPG) to paraffin wax. GTL makes it possible to obtain clean diesel, naphtha, lubes, olefins, and other industrially important organics from natural gas. This article is a brief review discussing the state-of-the-art of GTL, including the basics of syngas manufacturing as a source for Fischer-Tropsch synthesis (FTS), hydrocarbons synthesis (Fischer-Tropsch process), and product upgrading. Each one is analyzed, and the main characteristics of traditional and catalysts technologies are presented. For syngas generation, steam methane reforming, partial oxidation, two-step reforming, and autothermal reforming of methane are discussed. For Fischer–Tropsch, we highlight the role of catalysis and selectivity to high molecular weight hydrocarbons. Also, new reactors technologies, such as microreactors, are presented. The GTL technology still faces several challenges; the biggest is obtaining the right H2:CO ratio when using a low steam-to-carbon ratio. Despite the great understanding of the carbon formation mechanism, little has been made in developing newer catalysts. Since 60–70% of a GTL plant cost is for syngas production, it needs more attention, particularly for developing the catalytic partial oxidation process (CPO), given that modern CPO processes using a ceramic membrane reactor reduce the plant’s capital cost. Improving the membrane’s mechanical, thermal, and chemical stability can commercialize the process. Catalytic challenges accompanying the FTS need attention to enhance the selectivity to produce high-octane gasoline, lower the production cost, develop new reactor systems, and enhance the selectivity to produce high molecular weight hydrocarbons. Catalytically, more attention should be given to the generation of a convenient catalyst layer and the coating process for a given configuration.

Conversion process of natural gas into liquid fuels

Gas-to-Liquid (GTL) technology has developed over the past few decades into a financially sound industry offering market diversification to remote natural gas resource stakeholders. Presently, several patented technologies are available for the petroleum industries to transport natural gas cheaply in liquefied form. In the recent past, low natural gas prices in North America can be attributed to the isolation of shale gas resources using GTL technology. Some small technology providers are currently using GTL to eliminate associated gas flaring in remote oil fields. Several smaller technology providers are now looking to GTL to stop associated gas flaring in remote producing fields. In addition, GTL has the potential to extract liquid fuel in gas-rich inland areas. The GTL technology is preferred as the existing technologies that process natural gas through olefins are more complex and have so far proven difficult and costly in terms of commercial viability. The various GTL technologies having prospective market scope are reviewed this article.

Prospects of GTL Technology Use in the Oil and Gas Industry

Progress of the global energy industry as well as resources of natural gas of Russia were indicated in this article. The main region of their development over the years is Western Siberia, where more than 80% of gas reserves are explored. It is from here that the main stream of Russian gas flows to countries in Eastern and Western Europe. To date, good prospects have been opened for the preparation of gas reserves and production in eastern Russia with the launch of the Power of Siberia gas pipeline, which determined the high importance of this region, which is of strategic interest to the gas industry in Russia. The main resources of natural gas will be located in remote from the existing gas transmission system, inaccessible areas and areas with a harsh climate, where there are no large markets for the consumption of hydrocarbons. In connection with this, the search is underway for the transportation of natural gas, alternative to pipeline transportation, to the places of consumption. Three possible options are considered. According to the “General scheme for the development of the gas industry for the period up to 2030” , one of the promising options for the development of gas processing industries is the development and implementation of efficient technologies for the production of synthetic liquid fuels (GTL technology) aimed at solving the problems of developing small, mature and hard-to-reach natural gas fields. The special emphasize was made on one of the promising variants of gas-processing productions development - development and implementation of GTL (Gas to liquid) technology as a new method of production of synthetic liquid hydrocarbons from natural gas. Relevance, possible advantages, and prospects of GTL technology were also mentioned. The example of the Republic of Sakha (Yakutia) shown the possibility of using GTL technology, using as a raw material of natural gas of the Middle-Vilyusk gas condensate (gk) field. Also shown in this article are experimental details of the study of an individual hydrocarbon gas composition, which was determined using the gas chromatography method. The conclusion was made on the Republic's Oil and Gas Complex's overall potential cost-benefit in case of GTL technology implementation.

The economic viability of gas-to-liquids technology and the crude oil–natural gas price relationship

This paper explores the viability of a gas-to-liquids (GTL) technology and examines how GTL penetration could shape the evolution of the crude oil–natural gas price ratio. Much research has established the cointegrated relationship between crude oil and natural gas prices in the U.S. The persistently low U.S. natural gas prices in recent years seem to mark a shift in this relationship, and have led some in industry to begin considering investments in GTL capacity in the US. In order to look forward over decades when the underlying economic drivers may be outside of historical experience, we use a computable general equilibrium model of the global economy to evaluate the economic viability of GTL and its impact on the evolution of the crude oil–natural gas price ratio. Our results are negative for the potential role of GTL. In order to produce any meaningful penetration of GTL, we find it necessary to evaluate scenarios that seem extreme. With any carbon cap GTL is not viable. Moreover, even without a carbon cap of any kind, extremely optimistic assumptions about (i) the cost and efficiency of GTL technology and about (ii) the available resource base of natural gas and the cost of extraction, before the technology penetrates and it impacts the evolution of the crude oil–natural gas price ratio.

E&P Notes (February 2017)

E&P Notes Petroleum Engineering Schools Begin To See Enrollment Declines Stephen Rassenfoss, JPT Emerging Technology Senior Editor Enrollment in US petroleum engineering programs has peaked and is on the downslide, matching the short-lived surge in the 1980s, when a generation of engineers were graduated. Lloyd Heinze, the petroleum engineering professor at Texas Tech University who compiles this annual survey, does not think the current downturn “will be as bad” as the one 3 decades ago. The big question is: Will that long trough be repeated after a decade where the industry stepped up its recruiting to hire college graduates in time for the many workers nearing retirement? That will depend on the level of industry hiring in coming years, which he said is impossible to reliably predict because hiring plans are subject to sudden changes. Four Misconceptions That Lead to Drilling Automation Failure Trent Jacobs, JPT Senior Technology Writer Drilling automation is one of the most promising emerging technologies that the oil and gas industry has to look forward to. The potential benefits span the spectrum from health and safety to lower costs and repeatable well results. But before this technology leaps from pilot to center stage, early adopters will be challenged to create new managerial strategies that improve the interaction of human crews with automated rig systems, according to one expert. “In all the projects that I have worked on, what I have found is that the issues involving people were much bigger than the technical issues,” said Bill Koederitz, chief technology officer at GK Plus Innovations, during a presentation at a recent SPE Gulf Coast Section event. Commercial GTL Project Opens in Southeast Texas Stephen Whitfield, Staff Writer Infra Technology, a company specializing in the development of synthetic fuels from natural gas, coal, and biomass, opened the first completed small-scale commercial gas-to-liquids (GTL) project in the state of Texas. Located in Wharton, a small town 60 miles southwest of Houston, the plant will produce synthetic crude oil from natural and associated gas. The Wharton plant is Infra’s first plant in the US. The company has been operating pilot plants in Russia for the past 7 years. Modularly constructed, the plant utilizes GTL technology based on the Fischer-Tropsch process, where hydro-carbons are created through a series of chemical reactions. The plant will operate in two stages. The first stage involves the production of synthesis gas (syngas) through a reformer that converts solid fuel into gaseous reactants. The technology processes feedgas with varying density, from dry methane to heavy gases. Energy Policy Uncertain in the Wake of Brexit Referendum Stephen Whitfield, Staff Writer With an uncertain future spawning from the Brexit referendum, the British government is seeking to maintain as much consistency in its energy policy as possible. A representative from the British Consulate of Houston said there will be changes to the way goods, services, and people move from the UK to the EU, and while very few concrete statements can be made about how Brexit will impact the oil and gas industry, investment in Britain’s offshore and onshore assets will be critical for the country moving forward. In a presentation hosted by the SPE Gulf Coast Section’s International Study Group, Cynthia Conner examined the potential challenges and opportunities facing the oil and gas industry in the wake of Brexit. Conner is a senior policy lead at the British Consulate of Houston and a member of the Global and Economic Policy Group at the British Embassy in Washington, DC.

Partial oxidation of methane to syngas over Pt/Rh/MgO catalyst supported on FeCralloy woven fibre

AbstractIntegrating a high‐pressure syngas step with Fischer‐Tropsch synthesis (FT) in a single vessel reduces investment and operating costs for Gas‐to‐Liquids technology (GtL). Methane catalytic partial oxidation (CPOX) to produce syngas for FT is an economic opportunity for micro‐refineries. Many metals and metal oxides selectively convert natural gas to CO and , but they also form coke, which must be removed intermittently, otherwise it deactivates the catalyst and can foul the reactor and process lines. Here, we prepared a 1 % mass fraction (0.01 g/g) Pt/Rh (Pt/Rh = 9) catalyst supported on MgO over FeCralloy woven fibre via solution combustion synthesis. At 900 °C, from 0.1–2 MPa, and with a 2:1 feed composition of to , the reaction consumed all the oxygen and we obtained a ratio of 2 (ideal for FT). At low pressure and a 0.1 s residence time the catalyst converted 90 % of the methane at 90 % CO selectivity. At 2 MPa, CO yield reached 50 % ( 80 % conversion and 57 % selectivity). Based on thermodynamic calculations, less than 5 % coke forms below . At high pressure and short residence time (0.1 s), the coke yield (presumed to be coke crystallites) was 24 %. Increasing the residence time to 0.3 s reduced the amount of coke by 33 % because it is metastable.

Small GTL technology for a big country

Gas to liquids (GTL) technology has been applied and proven at large industrial scale in various parts of the world. Such projects, however, consume large quantities of gas, are capital intensive, generate large product volumes, and take decades to bring to fruition. For remote areas of Australia where there are small stranded gas fields and where there is local demand for liquid transportation fuels—which must be transported from manufacturing or import terminal centres—the development of the microchannel GTL reactor is an enabling technology that presents an innovative solution to allow economic development of small GTL projects near the gas deposit, and in the process satisfies local product demand. A microchannel reactor designed to enhance heat transfer in the GTL reactor has been developed and patented by Velocys When used with more active catalysts it provides process intensification to overcome the usual economies of scale benefits associated with larger reactors. The first commercial application of this technology is, at present, being commissioned at ENVIA’s East Oak Oklahoma site using a mixed feedstock of landfill gas and natural gas. Products made by this process do not contain aromatics or sulphur and burn cleaner than petroleum-derived fuels, resulting in lower emissions of NOx, SOx and particulates. Assessment of the use of this novel microchannel reactor technology in remote central Australia is being undertaken. Using a modular skid approach for equipment design and construction to improve site efficiencies, the small GTL concept should be very attractive for a remote Australian context. The standardised modular plants are easier to transport and quicker to install, with lower risk even in the most remote or challenging locations.

GTL FPSO—An Alternative Solution to Offshore Stranded Gas

Summary Sustained and increasing world energy demands have led to very high oil prices. In parallel, there has been a significant increase in interest in economic and environmentally sensitive solutions for the monetization of remote, stranded gas offshore. Current global natural-gas reserves total approximately 6,100 Tcf, according to US Energy Information Administration estimates. Roughly one-half of these reserves are considered to be stranded gas that is uneconomical for market delivery because of the remote location of potential markets, the lack of economic transportation and infrastructure, or the lack of conversion technology. Such regions with significant stranded-gas reserves include Northern Australia, Vietnam, and Indonesia. Gas-to-liquids (GTL) floating production, storage, and offloading (FPSO) offers an attractive new solution to monetize these remote, offshore stranded-gas fields. Products of the GTL process are clean transportation fuels ranging from diesel to jet fuel that can be readily used in the existing energy infrastructure. Although this option was considered in the past by Syntroleum and Statoil in mid-2000, a subsequent examination of this option is warranted because of recent advances in both GTL and FPSO technology. New GTL commercial plants have recently begun production in Qatar, using technologies by Sasol and Shell with the latest advances in process technologies and catalysts. Membrane- and process-intensification technologies show considerable promise in making GTL an attractive option in the future. The newly built oil-FPSO units (at Pazflor and Agbami) instill confidence that large oil- and gas-processing operations can be performed safely and economically on an FPSO unit. A feasibility study has been completed recently as part of a multiyear development program to acquire the basic technology and engineering for GTL FPSO. An assessment was made on the technical feasibility of commercial-scale and near-commercial-scale technologies, and a preliminary design concept of the GTL process was produced for the topside. This study used technologies that best met the needs of the FPSO application and the corresponding preliminary design concept of the hull to support the topside GTL process. Additionally, preliminary market analysis was performed to better define the scope of GTL products to be produced. Economic analysis was performed to identify the major cost factors and understand their sensitivity on project economics. The results of this feasibility study to date suggest that this GTL-FPSO design concept is technically feasible. Its clean fuel and chemical feedstock would be attractive to the market, and the design concept is economically competitive within the range of the current project-cost factors. Future work will be directed at developing a more-definitive process, hull design, and project economics, and will bring commercial realization of this innovative approach to monetizing offshore stranded-gas fields.

Steam Methane Reforming of Natural Gas with Substantial Carbon Dioxide Contents – Process Optimization for Gas-to-Liquid Applications

Steam methane reforming has been a conventional process to produce synthesis gas which is an important feedstock to many chemicals. However, for gas to liquid (GTL) applications this reforming process is not suitable as it produces synthesis gas with very high hydrogen to carbon monoxide ratio than required by the Fischer Tropsch synthesis in GTL line. In this work, a GTL process is designed in which synthesis gas is produced by steam reforming from a natural gas feedstock containing relatively substantial carbon dioxide contents in it. Synthesis gas composition is tailored by tail gas recycling from the Fischer Tropsch products. Process simulation and optimization is performed on Aspen HYSYS to produce synthesis gas with hydrogen to carbon monoxide ratio of 2 which is desired in GTL technology.

Efficiency of Gas-to-Liquids Technology with Different Synthesis Gas Production Methods

The design and optimization of a gas-to-liquids technology (GTL) is considered, mostly from the view of an optimal choice of a synthesis gas (syngas) production method. Material balance and energy efficiency are calculated for a number of flowsheets, which comprise syngas production by various techniques and Fischer–Tropsch (FT) synthesis of liquid hydrocarbons (LHs). Three different methods are considered for syngas production: combined steam and dry reforming; autothermal reforming; and partial oxidation. The FT process is considered in the version, which produces LHs, not waxes. The results of modeling manifest that the choice of syngas production method influences dramatically the efficiency of overall GTL technology. Ways to improve the efficiency of GTL technology are discussed.

Gas-to-Liquids Comes of Age in a World Full of Gas

Gas-To-Liquids Developments By the end of the decade, modular gas-to-liquids (GTL) plants distributed around wellheads in places such as North Dakota, USA, and Siberia, Russia, may become commonplace as pressure mounts on producers to monetize marginal natural gas resources. Small-scale GTL plants take the unwanted natural gas that is a byproduct of oil production, known as associated gas, and transforms it into more valuable liquid products. The technology can also be used to produce stranded gas reserves where a lack of distribution infrastructure exists. The current disparity between crude and natural gas prices and the ever-rising estimates of global natural gas reserves are driving oil companies to study the feasibility of using small-scale GTL plants. North America, where the use of hydraulic fracturing has led to a surge in oil and gas production, will likely be the first region to see the widespread adoption of modular GTL technology. With every new oil well that comes online, operators face tighter pipeline constraints, less gas-processing capacity, and increasing scrutiny from both regulators and the public sector on the disposal of associated gas through flaring. The associated gas that bubbles up with the crude is a phenomenon virtually all oil wells experience and, according to a 2011 report published by the World Bank, more than 5 Tcf of this gas is flared annually while another 15 Tcf is estimated to be reinjected. Two companies, CompactGTL and Velocys, are at the forefront of small-scale GTL development, and both have systems designed specifically to address the untapped markets that associated and stranded gas represent. CompactGTL, based in the United Kingdom, has plans to commission its first modular GTL plant in North America by the end of 2016 to produce synthetic crude oil, or syncrude, from natural gas. Syncrude, a milky white substance, is so free of impurities such as sulfur that it can command a premium price over crude oil because of the flexibility it gives refiners to optimize their operations. “There is an enormous amount of interest in North America for this solution,” said Iain Baxter, director of business development at CompactGTL. “The ability to take natural gas at the point of production and convert that into oil there and then—that is an incredibly valuable capability.”

The Use of Gas-to-Liquid Technology (GTL) to Produce Gasoline and Diesel Fuels

The Use of Gas-to-Liquid Technology (GTL) to Produce Gasoline and Diesel Fuels

A novel configuration of decalin and hydrogen loop in optimized thermally coupled reactors in GTL technology via differential evolution method

In this study, decalin and hydrogen looping approach is proposed in optimized thermally coupled membrane ternary reactors in gas-to-liquid technology (GTL). This novel configuration is named thermally coupled membrane ternary reactor (TCMTR), in which decalin dehydrogenation reaction is coupled with Fischer–Tropsch synthesis (FTS) reactions. Three different reactors are fabricated and integrated with membrane reactor where decalin and hydrogen are produced and utilized simultaneously. Under the optimized operating conditions of TCMTR via differential evolution method, decalin can be properly utilized in this novel configuration as a hydrogen carrier and the required decalin can be produced within the continuous loop and a slight amount of decalin is required for supplementation. 4.77% of the produced hydrogen in the first reactor is utilized in FTS reactions in the second reactor and the remaining 95.23% is utilized in hydrogenation reaction of naphthalene in the third reactor which leads to decalin production as a reactant of the first reactor. A comparison is made between the performances of optimized TCMTR (OTCMTR), conventional tubular reactor (CR) and thermally coupled membrane dual-type reactor (TCMDR). Significant decrease in decalin consumption rate can be achieved in this new scheme, and the hydrogen storage problem and no requirement for injection of fresh feed in each process. The results demonstrate the superiority of OTCMTR to all previously proposed configurations. Furthermore, the hydrogen storage problem is properly addressed by OTCMTR and significant decrease in decalin consumption rate can be achieved in this new scheme.

A new technology for producing synthetic liquid hydrocarbons from gaseous hydrocarbons

Conventional technologies of synthetic liquid fuels (SLF) production from gaseous hydrocarbons by producing synthesis gas and synthesizing synthetic liquid hydrocarbons are examined. A high-efficiency SLF production technology that allows creation of high-efficiency autonomous units of specific capacities, including small ones, eliminates use of oxygen for producing synthesis gas and reduces energy consumption by thorough utilization of the heat of process and energy flows, including low-potential, is described. In this technology, the hydrocarbon feedstock conversion processes and synthesis of liquid hydrocarbons are carried out with highly effective fine-grained catalysts under optimal temperature conditions in compact reactors of a new design. Efficient conversion of gaseous hydrocarbon feedstock right at the gas recovery sites to synthetic liquid fuels (SLF) holds wide prospects in solving many problems of energy security of regions. This will allow production of high-quality SLF that can be transported by conventional means (by tankers, containers, pipelines, etc.). In contrast to hydrocarbon gases, SLF can be stored and marketed by using the existing developed infrastructure [1]. Russia possesses enormous reserves of natural (NG) and associated petroleum gases (APG) and is a major supplier of energy resources to the countries of Western Europe. The largest oil and gas companies of the world have been working vigorously to develop and implement projects based on GTL (gas-to-liquid) technology in regions with substantial NG reserves [2]. Efficient conversion of NG to SLF may introduce corrections to the necessity of implementation of some costly projects. In that case: 1) there will be no need for constructing multi-kilometer trunk pipelines with compressor stations and their costly operation; 2) there will be no need for transit countries for NG transportation; 3) the seasonal NG supply factor will be solved; 4) there will be no need for building costly NG liquefying plants, special liquefied NG storing and dispatching terminals, special vessels for its transportation, receiving terminals with regasification plants, etc.; 5) the APG will be put into commercial production instead of burning in flares; and 6) noxious vehicular emissions will be reduced, which is of especial importance for solving environmental problems of large cities, and so on. Chemical and Petroleum Engineering, Vol. 48, Nos. 5‐6, Sept., 2012 (Russian Original Nos. 5‐6, May‐June, 2012)

Nanofluid concept for enhancement of hydrogen utilization and gasoline production in fixed bed reactor Fischer–Tropsch synthesis of GTL (gas to liquid) technology

The present study proposes a novel configuration for cooling system of Fischer–Tropsch synthesis (FTS) reactor. In this new configuration, nanofluid is used as a coolant inside the shell of fixed bed reactor of FTS. This novel concept has been named nanofluid-cooled fixed bed reactor (NFR). Aqueous based nanofluids consist of alumina nanoparticles are used in the shell side of NFR while saturated water is used in the shell side of conventional reactor (CR) as a coolant. Various nanofluids with different concentrations have been examined and their effects on the reactor performance have been investigated. Heat transfer from tubes is improved in NFR reactor because of using aqueous based nanofluids containing alumina nanoparticles. Therefore tubes are increased in NFR reactor in comparison with CR. The simulation results consist of two schemes of NFR (various concentrations of alumina nanoparticles, NFR I, NFR II) and one scheme for CR. The results of different schemes are presented and they have been compared in terms of temperature, gasoline yield, CO2 yield, H2 conversion and CO conversion. The interesting result is decreasing temperature jump at the entrance of NFR reactor. Also using more tubes inside the shell of NFR I and NFR II causes not only decrease of temperature jump in the entrance of reactor but also increases hydrogen utilization and gasoline production. Hydrogen utilization shows an increase of 18% in NFR I and also 12% in NFR II in comparison with CR. Gasoline production shows an increase of 21% in NFR I and also 10% in NFR II in comparison with CR. The ratio of CO2 yield to gasoline yield is decreased to 2.12% in NFR I and 1.51% in NFR II in comparison with CR.

Simultaneous hydrogen injection and in-situ H2O removal in a novel thermally coupled two-membrane reactor concept for Fischer–Tropsch synthesis in GTL technology

Gas-to-Liquids (GTL) technology converts natural gas, through Fischer–Tropsch synthesis, into liquid and ultra-clean hydrocarbons such as gasoline, light oils, naphtha, diesel, and wax. In this study, a novel thermally coupled multi-tubular two-membrane reactor (TCTMR) is proposed in order to enhance of gasoline production. Fischer–Tropsch synthesis is carried out in the exothermic side with two different membranes and supplies the necessary heat for the endothermic side. Decomposition of ammonia is carried out in the endothermic side with hydrogen-permselective Pd/Ag membrane layer. Therefore, the proposed reactor consists of two different membranes, one for permeation of pure hydrogen from exothermic into endothermic side and another one for separation of water from exothermic side. Water produced during FTS negative influences the reaction by re-oxidation of catalysts, increasing water/gas shift activity and decreasing partial pressures of the products. A steady-state heterogeneous model of the two fixed beds predicts the performance of this novel configuration. The achieved results of this simulation have been compared with the results of the conventional fixed-bed reactor (CR) at identical process conditions. The simulation results show 27.14% enhancement in the gasoline yield and 35.2% decrease in CO2 yield of TCTMR in comparison with the one in CR due to a favorable profile of temperature along the TCTMR.

Looking for alternative energy sources

With unrest in oil-exporting countries, backlashes against biofuels and photovoltaics, and a nuclear incident in Japan, the year 2011 rattled confidence in future energy supplies. The search for alternatives is all the more urgent, but some of the solutions investigated hark back to fossil fuels that we can't afford to burn.

A comparative study between a fluidized-bed and a fixed-bed water perm-selective membrane reactor with in situ H 2O removal for Fischer–Tropsch synthesis of GTL technology

In order to eliminate the pressure drop problem and mal distribution of the temperature profile along the reactors, fluidized-bed membrane reactors are proposed as an alternative for Fischer–Tropsch synthesis (FTS) in gas-to-liquid (GTL) technology. Regarding this, a novel cascading fluidized-bed membrane reactor (CFMR) is proposed in this study and compared with a fixed-bed membrane cascading with fluidized-bed membrane reactor (FMFMR). The CFMR configuration consists of a fluidized-bed water perm-selective membrane reactor followed by a fluidized-bed hydrogen perm-selective membrane reactor. The performance of CFMR is compared with FMFMR in order to investigate the effect of fluidization concept on the reactor performance. Unlike CFMR where a fluidized-bed concept is applied in the first reactor, a fixed-bed concept is used in the first reactor of FMFMR. The modeling results show 5.3% increase in the gasoline yield and 12% decrease in CO 2 yield in CFMR in comparison with FMFMR owing to applying a fluidized-bed concept instead of a fixed-bed concept in which more effective temperature management is achieved. According to the modeling results, CFMR is superior to FMFMR for FTS in GTL technology owing to achieving excellent temperature control and a small pressure drop and consequently higher gasoline yield and lower CO 2 yield.

Differential evolution (DE) strategy for optimization of hydrogen production and utilization in a thermally coupled membrane reactor for decalin dehydrogenation and Fischer–Tropsch synthesis in GTL technology

In this study, the operating conditions of a thermally coupled membrane reactor (TCMR) in gas-to-liquid (GTL) technology are optimized via differential evolution (DE) method to maximize the hydrogen mole fraction in the endothermic side as well as the gasoline yield in the exothermic side. TCMR is designed as a double pipe reactor where highly exothermic Fischer–Tropsch synthesis (FTS) reactions in the exothermic side are coupled with decalin dehydrogenation reaction in the endothermic side. The minimum required hydrogen molar flow rate in the recycled stream is optimized to compensate a hydrogen lack at the end of the reactor in the exothermic side. The optimization results show 14.28% increase in the gasoline yield in optimized TCMR compared with conventional tubular reactor (CR). Moreover, 81.49% hydrogen is produced in the endothermic side and about 1% hydrogen is recycled to the exothermic side for utilization in FTS reactions in optimized TCMR.