Tar measurement standard

Organic contaminants or ‘tars’ are considered as the major problem causing contaminants, which causes a large obstacle for the market introduction of biomass-gasification based systems. Measurement methods as well as definitions for tars are numerous and non-consistent. As a result, the comparison of data and the definition of clear maximum allowable concentrations for tars in the syngas are still problematic.
So far, no well-developed and standardised measurement method exists for tars in biomass-producer gases, and different sampling and analysis methods are currently being used. In a previous EU-project (ERK6-CT1999-20002), ECN was leading the development of a Guideline for tar measurement (“the Guideline”), in order to remove this obstacle. The Guideline aims at measurement of both gravimetric tars as well as individual organic compounds. The measurement principle is based on the discontinuous sampling of a gas stream containing particles and condensable organic compounds. Although several institutes have now used this Guideline, it does not have the status of an international standard and it is not yet used on a routine basis as no detailed data on accuracy and reproducibility of the Guideline have been collected and compared.

ECN Biomass is currently leading a European initiative aimed at of expanding the use of the Guideline and transfers it into a European (CEN) standard method. The activities involve R&D in gathering data on accuracy and reproducibility of the measurement method, (including a Round Robin Test on GC and gravimetric tar analysis, and a parallel measurement campaign), as well as standardisation work at CEN level. The final result will be a CEN standard which will allows manufacturers of gasifiers, gas cleaning systems, and engine or turbine/generator sets to convince potential end-users on the technical performance of the sub-systems, and to define tolerances from which guarantees on performance, system life time etc. can be derived. In addition, the standard will allow companies, institutions and universities that develop gasification technology to have a common method to measure the tar concentrations.

The full version of the Guideline method can be downloaded at Tarweb.EU project: ‘Tar measurement standard’- EU-contract EK5-CT2002-80648.The Guideline sampling set-up: atmospheric and isokinetic sampling train for tar and particles with removable probe and pilot tubes for flow measurement.