Background and Experience

technology2Today’s electricity is almost exclusively produced through big centralized large-scale plants at a relatively low overall efficiency. The useful utilization of thermal energy is almost nonexistent in these installations as most of the E-works have no great use for this heat. This has been and still is the basis for so-called CHP (Combined Heat and Power) installations for applications where electricity and heat are used in parallel. The majority of these installations run on fossil fuels, mainly on natural gas. These installations show generally high overall efficiencies and reduce this way the overall environmental impact of burning fossil fuels. It is the vision of Synvalor that in the future these CHP installation will be driven by sustainable fuels like waste wood or agro residue and the like, if we as suppliers of such systems can make these installation exactly as reliable as today the ones on natural gas and diesel are.

The main problem in these installations is the feedstock treatment as this usually is done by screw conveyors, hoppers, rotaries and the like, which require due too potential blocking or bridging always some attention from the operators, likewise this is valid for the ash discharge, which usually also contains one or more screw conveyors. Different gasifiers require different feed pretreatment and ash discharge equipment, most fixed and fluid bed gasifiers do not like too moist or too much ash in the feedstock; virtually all like to have a regularly sized feed in order to prevent blockages.

image3The syngas cleaning should contain both dust and tar cleaning and depending on the chosen technology sometimes also some water treatment, as most of the tar removal technology is based on scrubbing the tars out of the gas, which has not to forget an impact on the gas quality going into the gas engine. Also there will be  safety issues when feeding the gas to a gas engine during normal operation (pressure differences during process), start-up and shut-down (too low caloric gas).

Synvalor has a history of integrating all these different technologies into a working plant and actually did test several different types of gasifiers on different feedstocks with different cleaning methods. Synvalor personnel did develop the first toroidal bed gasifier on waste wood in The Netherlands and have operated this plant for many years now by herself. All child diseases with the feeding mechanism into the reactor, with the discharging of the very  reactive ashes, with the actual design and running of the gasifier have all been made and as they say one  never learns more than from your own mistakes. We have made those mistakes and learned from it.

For the E-conversion part Synvalor has a close cooperation with Dordtech, known as a supplier of CHP sets on lowest caloric value gases. We refer gladly for this part of our experience to their website www.dordtech.nl.

Working references for gasifiers are available in The Netherlands and in Spain, both in heating applications as well as in the generation of electricity. Overall energy efficiencies of up to 85 % (depending on the temperature levels of the heat demand) with overall  electrical efficiencies as high as 30% calculated on primary energy input, are within reach today.

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