To allow necessary process changes, research tests and quick modifications, the new equipment must have a degree of built-in flexibility. This requirement led to select a new control system and achieve freedom to change and reprogram the system when necessary
Developing cost-effective vehicle fuel from feedstock
When an EU sponsored research project for Clean Hydrogen Rich Synthesis Gas (CHRISGAS), based on biomass started in the town of Värnamo located in the forested area of southern Sweden, an existing research pilot plant has been retrofitted to enable thermo-chemical derived vehicle fuel research under the auspices of Växjö University. The formation of a non-profit company, the Växjö Värnamo Gasification Center, VVBGC, to operate and maintain the plant initiated investments in the rebuild of the existing process for its new purposes.
The objectives of the CHRISGAS research project are to develop and optimize a process for the production of hydrogen-rich gas from biomass in an energy and cost efficient manner. This gas can then be upgraded to commercial quality hydrogen or to synthesis gas for further refinement into liquid fuels such as DME, (dimethyl ether), methanol or Fischer Tropsch diesel. The primary focus is to demonstrate the economic production of an intermediate product for the manufacturing of vehicle fuel from renewable feedstock – a clean and hydrogen-rich gas based on steam/oxygen blown gasification of biomass. This process step is followed by hot gas cleaning to remove particulates and steam reforming of tar and light hydrocarbons to further enhance the hydrogen yield. Two quantitative goals have been established. The gas generation capacity should reach 3500 Nm3/hour 2) with an accumulated operating time of 2000 hours.
Ethanol production process
The heart of the process is a low-pressurized steam/oxygen blown gasifier cyclone 1c typically operating at 10–15 bar pressure and 950 to 1000 °C. To reduce the inert gas consumption of the fuel feeder, a piston based system is being developed with a performance that exceeds the current one by two orders of magnitude. The biomass fuel is fed at a maximum rate of 4 ton/hour and consists of roots and branches. Gas cooling takes place downstream of the gasifier 1d. The optimal temperature in this phase is a research topic in itself and will be determined during testing. The steam reformer 1g, catalytic or thermal, follows and provides for the first stage of chemical upgrading converting hydro carbons (mainly methane) and tars to hydrogen and carbon monoxide.
The determination of the optimal balance between these two components to achieve high yield of synthesis gas is one of the crucial research tasks. To further enrich the hydrogen in the raw gas and provide for additional upgrading, a water-gas-shift and a hydrogenation reactor 1j is placed after the cooling. The optimal temperature for this stage will be identified as part of the research program.
Topics that the technical challenges are related to are the scaling of the process from laboratory size to semifull scale, making critical filters work at high temperatures and identifying the operating points that provide maximum yield. But more than all this, the greatest question requiring an answer is: “Can biomass replace natural gas in producing a synthesis gas of the quality required for further processing into biodiesel at a cost compatible with commercialization?”