The IFK FID online tar measurement device TTA 300 was originally developed in the 1990s and has been further developed with the final goal for commercialization in the past years. This page only shows a brief summary of the measurement method. Further information can be found in respective publications.
The measurement method is based on a difference measurement between two volumes of sample gas. The total hydrocarbon content of one volume is measured with an FID. The sample gas from the second volume is led over a suitable filter that captures the “condensable hydrocarbons” (tars). The remaining gaseous hydrocarbons (C1-C6) are subsequently measured with the FID. The difference of the total hydrocarbon content and the C1-C6 hydrocarbons determine the tar content of the gas.
Calibration is done with propane in a concentration of the expected total hydrocarbon concentration of the sample gas. Propane is used as calibration gas for a gas mix because its response factors to common PAKs is around 1. The device has 3 measurement ranges up to a total hydrocarbon concentration of 120 gC/m³stp.
Based on the tar definition, filter materials for the tar condensation can be selected. According to experiences and tests at IFK, a mix of cellulose acetate (conventional cigarette filter) and a phyllosilicate called “bentonite” is used in the analyses of tars in producer gases of biomass gasification processes.