The tar protocol provides a guideline as a set of procedures for the measurement of organic contaminants and particles in producer gases from biomass gasifiers. The guideline is described, promoted, and periodically updated via internet on http://www.tarweb.net.
The procedures are designed to cover different gasifier types (fixed bed gasifiers with updraft and downdraft principle, and fluidised bed gasifiers), operating conditions (0° - 900°C and 0.6 - 60 bars) and concentration ranges (1 mg/mn3 to 300 g/mn3). The guideline describes a modular sampling train, and a set of procedures, which include: planning and preparation of the sampling, sampling and post-sampling, analysis, calculations, error analysis and reporting.
The modular sampling train consists of 4 modules. Module 1 is a preconditioning module for isokinetic sampling and gas cooling. Module 2 is a particle collection module including a heated filter. Module 3 is a tar collection module with a gas quench (preferably by circulating a liquid), impinger bottles and a backup adsorber. Module 4 is a volume-sampling module consisting of a pump, a rotameter, a gas flow meter and pressure and temperature indicators. The equipment and materials that are required for procuring this modular sampling train are given in the Guideline.
The sampling procedures consist of a description for isokinetic sampling, a leakage test prior to sampling, the actual sampling and its duration, how the equipment is cleaned after the sampling, and how the samples are prepared and stored.
Analysis of the samples is performed via three procedures. Prior to these procedures, the sample is prepared by Soxhlet extraction of the tars on the particle filter and by collection of all tars in one bulk solution. The first procedure describes the weighing of the particle filter to obtain the concentration of particles in the biomass producer gas. The bulk tar solution is used for two purposes: for determination of gravimetric tar and for analysis of individual compounds. The second procedure describes how to determine the gravimetric tar mass from the bulk solution. The third procedure describes how the solution can be analysed by GC-MS or GC-FID to obtain the concentrations of individual tar compounds.
J.P.A. Neeft, H.A.M. Knoef, U. Zielke, K. Sjöström, P. Hasler, P.A. Simell, M.A. Dorrington, N. Abatzoglou, S. Deutch, C.Greil, G.J. Buffinga, C. Brage, M. Suomalainen: Guideline for Sampling and Analysis of Tar and Particles in Biomass Producer Gases, 2002 (Final Version)
J.P.A. Neeft, S. van Paasen, H.A.M. Knoef, G.-J. Buffinga, U. Zielke, K. Sjöström, C. Brage, P. Hasler, P.A. Simell, M. Suomalainen, M.A. Dorrington, L. Thomas: Tar Guideline. A standard method for measurement of tars and particles in biomass producer gases, 12th European Conference and Technology Exhibition on Biomass for Energy, Industry and Climate Protection, 17-21 June 2002, Amsterdam