GAS TO LIQUIDS...Very interesting and knowledgable..

WHAT IS GAS TO LIQUID???

The conversion of natural gas into liquid fuels is an attractive option to commercialise abundant gas reserves. Gas to Liquids (GTL), with virtually unlimited markets, offers a new way to unlock remote gas reserves, complementary to other traditional technologies such as Liquefied Natural Gas (LNG) and pipelines. GTL conversion is an umbrella term for a group of technologies that can create liquid synthetic fuels from a variety of feedstocks.  The basic technology was developed in Germany in the 1920s, and is known as the Fischer-Tropsch process after its inventors. In essence it uses catalytic reactions to synthesise complex hydrocarbons from simpler organic chemicals. This process can create identical liquids from a variety of feedstocks, although the technical challenges are greater forbiomass and coal.  There are two main categories of natural gas-based Fischer-Tropsch process technology: the high and the low temperature versions. The high-temperature, iron catalyst-based Fischer-Tropsch GTL process produces fuels such as petrol (gasoline) and gasoil that are closer to those produced from conventional crude oil refining. The resultant GTL products are virtually free of sulphur, but contain aromatics.  The low-temperature, cobalt catalyst-based Fischer-Tropsch GTL process, however, produces an extremely clean synthetic fraction of gasoil called GTL Fuel that is virtually free of sulphur and aromatics. Shell is one of several companies that have developed low-temperature Fischer-Tropsch GTL technology. Shell's proprietary GTL process, also known as Shell Middle Distillate Synthesis - SMDS, uses a much more active and selective catalyst than earlier processes, which enables the production of a range of finely tailored liquid fuels in a fully commercialised system. There are three main stages: In the first, natural gas is partially oxidized at high temperature and pressure in the Shell Gasification Process (syngas manufacture step).  The second stage, Heavy Paraffin Synthesis (Fischer-Tropsch synthesis step), is the heart of the process. Here the gas is converted into liquid hydrocarbons.  Finally, the Heavy Paraffin Conversion (hydrocracking step) reactor is used to fine-tune the product by selective cracking and fractionation to separate the desired middle distillate products. The products from Fischer-Tropsch GTL plants includes middle distillates such as GTL Fuel for transport use, naphtha for chemical feedstocks, normal paraffin for detergent feedstocks and lubricant base oils. In addition, there could also be condensates and LPG production from treating of wellstream gas. Shell GTL products comprise primarily of clean GTL Fuel (gasoil) and naphtha. There is flexibility to vary the proportions of these products, depending on the intensity of the Fischer-Tropsch GTL cracking process and other operating conditions. Specialist products from GTL plants are lower volume streams, such as normal paraffin (detergent feedstock) and lubricant base oils, which are sold into high-value markets of limited size.  Shell has pioneered the development of Gas to Liquids technology and has operated a medium scale GTL plant at Bintulu, Malaysia since 1993, that has current capacity of 14,700 bbl/day. With a decade of operating experience at the Bintulu plant, Shell technologists have the confidence to scale up to a worldscale 140,000 bbl/day GTL plant planned to be operational in Qatar towards the end of the decade. Benefits of GTL Fuel GTL technology is capable of converting natural gas into clean products for use as fuels or chemical feedstock. GTL products are virtually pure paraffinic hydrocarbons that have excellent combustion properties and burn with a smooth, controlled flame. GTL Fuel for transport, in particular, is a clear, clean fuel, virtually free of sulphur and aromatics and has a very high cetane number. Cetane number is a measure of fuel combustion quality – the higher the cetane number, the more complete the combustion. GTL Fuel has a cetane number of 75-80, much higher than the typical refinery diesel range of 45-50.  Below is an example of GTL products (left) compared to a 350ppm sulphur diesel (right) This unique gas-derived transport fuel can provide great flexibility. It can be used either as a pure product or as a blend with conventional diesel. Since it is made from natural gas reserves, it contributes to improving the diversity of supply of transport fuels and reducing dependence on petroleum products.  GTL Fuel has a large number of benefits for both regulators and fleet operators. It can be used in conventional diesel engines, but provides significantly lower emissions of local pollutants, such as particulates, carbon monoxide, hydrocarbons and nitrogen oxides, even when compared to so-called 'sulphur-free' diesel. Emission Benefits  GTL Fuel significantly contributes to the reduction of local emissions, although percentages vary by vehicle type and test condition: light duty vs. heavy duty; Euro-3 vs. Euro-4. For example, emissions benefits for 100% GTL Fuel in a trial of Volkwagen Golf cars in Berlin in 2003 using a current modern (Euro-3) light duty engine and compared to current European diesel are approximately:  particulates 26% lower  nitrogen oxides 6% lower  hydrocarbon 63% lower  carbon monoxide 91% lower Blends of GTL Fuel (25-30%) with conventional diesel also reduce local emissions, the benefit being disproportionately high.  Greenhouse Gas Emissions  An external study concluded that, on a life-cycle analysis basis, a 'Shell GTL system', compared to a 'crude oil refinery system', has no greater impact on global warming and has a significantly lower impact on air acidification and smog formation, and lower emissions of particulate matter.  Cost Effectiveness of GTL Fuel  Unlike some other "alternative" fuels, particularly gas-derived products, such as Compressed Natural Gas (CNG), GTL Fuel is compatible with existing diesel engines and distribution infrastructure, and therefore more cost-effective to introduce. An independent study carried out by the California Energy Commission showed that GTL Fuel is the most cost-effective alternative fuel in reducing emissions.  A further study has been carried out to estimate the cost effectiveness of various options for the reduction of Europe's dependence on imported petroleum. The study developed a quantitative estimate of the cost effectiveness of key alternative fuels for the reduction of petroleum dependence, taking into account differences in GHG emissions between the options, in passenger cars, light duty commercial vehicles, and heavy duty trucks. Other fuels considered included biodiesel, bioethanol, BTL Fuel, CNG, hydrogen, and LPG. Scenarios were developed that would plausibly satisfy the requirements of the EU with the most appropriate fuels in the post-2010 timeframe. The study concluded that GTL Fuel offers the most cost-effective reduction in petroleum use to meet EU targets.  Moreover, GTL Fuel can provide a bridge to future fuels and technologies, as: It is an enabler for new ultra-efficient exhaust filter devices.  It can be used in diesel-electric hybrid vehicles.  The homogeneity of synthetic GTL Fuel in combination with its uniquely high cetane number creates particular opportunities for advanced drivetrain designs. Major automotive industry players are optimistic that they can utilise the fuel's unique properties to develop more efficient derivatives of the internal combustion engine. This can deliver potential benefits such as improved efficiency, better driveability, lower noise level and reduced emissions.  GTL Fuel is particularly well suited for onboard reforming applications, either in conjunction with advanced internal combustion engine technology, or to produce hydrogen for fuel cell vehicles.  GTL technology provides a platform for development of Biomass to Liquids (BTL) and Coal to Liquids (CTL) products with identical chemical composition. GTL Products In addition to GTL Fuel, GTL plants can also produce a range of other products, such as naphtha, normal paraffin - a feedstock used in the detergent industry - and lubricant base oils. GTL Naphtha is the highly paraffinic C5-C8 fraction produced from the Fischer-Tropsch GTL process. The high paraffinicity makes it an ideal steam cracker feedstock for ethylene and propylene manufacture. The paraffinic nature and the purity of GTL Naphtha results in higher ethylene and propylene yields compared to petroleum-based naphtha feedstock.  Shell GTL Normal Paraffin is the future LAB feedstock of choice, providing significant cost savings for LAB producers. Please visit the Shell GTL Normal Paraffin section of our site.  Lubricant base oils are the starting material for the lubricants that keep vehicle engines, gearboxes and transmissions turning smoothly. Advances in engine design and the need to improve emissions and fuel economy place increasing demands on the lubricants, and GTL Base Oils will bring a step change in the ability to meet future lubricant requirements.  Shell is the leading producer of GTL Base Oils, and has been making pure, high quality base oils commercially since 1993 using feedstock from the Bintulu GTL facility. This small volume of high value product has been used in the highest tier of Shell lubricant products. The production from the Pearl GTL project will lead to a significant change, both in terms of the volume of base oils available and the range of base oil types.