Many applications of air gasification of agricultural residues are severely hindered by the presence of tars in the produced gas. The task of this project is to develop reliable and economical methods to remove tars and fly ash/char from the hot gas. The most promising method to achieve this is to dispose a secondary reactor, downstream the gasifier. Cheap and feasible beds of dolomites, magnesites, calcites, chars, charcoals etc...are used to clean the fuel gas. The main goal is to find the cheap and suitable catalytic solid for cleaning and upgrading of the crude gasification product gas.
Participant no 1 (UCM) is studying tar elimination with two installations based in bench scale (1kg/h) fluidized bed gasifiers. Both facilities are based in a 3-stage process: gasifies (+hot metallic filter) + (fixed, fluidized or moving) bed of dolomite or related tar cracking solid + catalytic bed (with steam reforming/cracking catalysts). The tar yield of 20-40g/Nm3 after the gasifier is reduced till 1g/Nm3 with the bed of dolomite and till only 10-50 mg/Nm3 after the catalytic bed, with residence or contact times of only 0.1-0.2 seconds. Dolomites, magnesites and calcites from different quarries are being tested.
Participant no 2 (BTG) is using two slightly different tar cracking systems which are both based on the same principle: the gas containing tar is directed through a reactor consisting of a hot incandescent charcoal bed. In this reactor all the tar compounds are cracked through thermal and catalytic processes. The differences between the two systems lies in their scale and in the way the secondary reactor is heated.
Participant no 3 (KTH) concentrates on the catalytic decomposition of tar from gasification at lab scale. Several types of solids will be tested in the secondary bed. Reliable and fast analytical methods for the determination of selected organic compounds in the complex biomass tar will be applied.
Participant no 4 (RUG) will concentrate on catalytic gas cleaning with in-situ catalyst regeneration to find catalysts for low gasification temperatures. Improving economics and oxygen introduction before the secondary bed are also its goals.
Participant no 5 (TPS) already owns large air gasifiers of biomass. It tries to find type catalysts for the hot gas cleaning from the nitrogen compounds and hydrogen cyanide in order to avoid other more costly post-combustion elimination technics. Dopped dolomites and other tar cracking solids, iron based, are checked by this participant.
The catalytic deactivation and the time-on-stream dependent properties of the solids are being studied. New tar sampling and analysis methods are being developed, checked and standardized.
Funding SchemeCSC - Cost-sharing contracts
7500 AE Enschede
9747 AG Groningen
611 82 Nykoping