In cooperation with science, technology and research experts, Lewa, manufacturer of metering and process diaphragm pumps and systems, participated in the development of new production processes for second generation biofuels (BTL). Such biofuels can be produced from energy plants or unused waste, mainly using two different technologies: thermal decomposition or direct liquefication to produce crude bio oil, and gasification to produce synthesis gas using Fischer-Tropsch synthesis.
Because of their ruggedness and adaptability, Lewa diaphragm metering pumps are already successfully installed in numerous pilot and test facilities under various process conditions and in a many different liquids. Thus, the diagram shows that, in comparison to conventional rotary or centrifugal pumps, diaphragm pumps can achieve an adjustable and highly-flexible delivery flow over a wide range of pressure ratios. Diaphragm metering pumps are also leakage-free and can reach efficiencies of more than 80 percent over the whole metering range. They are especially suitable for high temperatures above 200°C and for ambient pressures above 90 bar and are thus ideal for the difficult process conditions usually found in biofuel production. Lewa supplied process diaphragm pumps working with increasing reactor pressure or as circulation pumps for Fischer-Tropsch synthesis in the world’s first commercially operating Biomass-To-Liquids (BTL) plant. In this process high-grade synthetic fuels (Gas-To-Liquids GTL, Coal-To-Liquids CTL), are extracted from synthesis gas. If the synthesis gas is produced from biomass, this is referred to as Biomass-to-Liquids (BTL) or Synfuel. The heart of this process is the 3-stage gasification consisting of the following process steps: low-temperature gasification, high-temperature gasification and endothermic entrained flow gasification. Biomass, with a water content of approximately 15 till 20 percent, is continuously carbonised in the first process step by partial oxidation (charring) with air or oxygen at temperatures between 400°C and 500°C, for example broken down into tar-containing gas (volatile components) and solid carbon (biocoke). In the second process step, the tar-containing gas is subjected to under-stoichiometric post-oxidation in a combustion chamber above the hemisphere temperature of the fuels with air and/or oxygen.
BTL technology helps to reduce CO₂-emissions
In the third process step, the biocoke is ground to pulverised fuel and is blown into the hot gasification medium. In the gasification reactor, this pulverised fuel and the gasification medium have undergo an endothermic reaction to synthesize crude gas. After appropriate processing, this can then be used as a fuel gas for electricity, steam and heat generation or as a synthesis gas for SynDiesel production. The conversion of the synthesis gas to fuel is performed using Fischer-Tropsch chemistry. The reactive components of the synthesis gas (CO + H₂) react using a catalyst to form hydrocarbons.
FT synthesis was developed in the 1920s in Germany and today is particularly used in South Africa and China for large-scale fuel production from coal. To maximise the diesel yield (SynDiesel), the waxes that are produced in FT synthesis are further refined by hydrocracking. This process originates from petrochemistry and is used to process refinery residues. Due to the instant flammability of the synthetically produced hydrocarbons (preliminary and intermediate products) in the atmosphere, which exceed the ignition temperature in the process described, hermetically sealed diaphragm technology was given preference over rotating technologies (such as centrifugal pumps and canned motor pumps). Maximum process and environmental safety as well as the highest possible availability are the customer benefits gained with the hermetically sealed Lewa pumps. The demands of the Kyoto Protocol to drastically reduce CO₂ emissions are principally implemented in Europe due to the promotion of BTL technology. This European trend is already catching on in the USA, China and other countries. Lewa, with its know-how and local presence, plays an important global role in the development of this cost-effective and environmentally-sound technology in the manufacture of fuels from unused biomasses.
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