Abstract. The liquid organic fraction of pyrolytic tar has a high energy value which makes possible its utilization as an energy source. However, before utilization, it is crucial to remove water from the liquid fraction. The presence of water reduces the energy value of pyrolytic tars. Water separation from the organic tar fraction is a complex process, since an emulsion can be readily formed. Therefore, after phase separation, it is important to know the residual water content in the organic phase and whether it is necessary to further dry it.The results presented in this manuscript focus on a water determination in liquid products from coal and biomass pyrolysis by a coulometric Karl-Fischer titration. The Coulometric Karl-Fischer titration is often used for a water content determination in gaseous, liquid and solid samples. However, to date, this titration method has not been used for a water determination in tars. A new water determination method, which has been tested on different types of tar, has been developed.The Coulometric Karl-Fischer titration is suitable for tar samples with a water content not greater than 5 wt%. The obtained experimental results indicate that the new introduced method can be used with a very good repeatability for a water content determination in tars.
Tars from pyrolysis of brown coal can be refined to obtain compounds suitable for fuel production. However, it is problematic to refine the liquids from brown coal pyrolysis, because high molecular compounds are produced, and the sample solidifies. Therefore we decided to investigate the possibility of treating the product in the gas phase during pyrolysis, using a catalyst. A two-step process was investigated: thermal-catalytic refining. In the first step, alumina was used as the filling material, and in the second step a catalyst based on W-Ni was used. These materials were placed in two separate layers above the coal, so the volatile products passed through the alumina and catalyst layers. Pyrolysis tests showed that using the catalyst has no significant effect on the mass balance, but it improves the properties of the gas and the properties of the organic part of the liquid pyrolysis products, which will then be processed further.
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