Towards synthetic fuels production from biomass gasification: Tar content at low temperatures

Biomass conversion into biofuels and biogas is a promising way for power and heat generation. Lately, research has focused on the production of biomethane based on biomass gasification followed by methanation as an alternative to fossil natural gas. The challenge of this process remains in the intensive gas cleaning and required tar removal. In order to study tar removal from the producer gas downstream biomass gasification, solid–vapor and liquid–vapor equilibrium must be known for different tar concentrations, ranging between 0.001 and 100 g.Nm−3. To assess tar removal by condensation at low temperatures, psychrometric charts are developed. Since the composition of tar is complex, toluene, phenol, indene, naphthalene and fluoranthene are selected as tar representatives. Each component is studied separately in four different producer gas compositions formed mainly of hydrogen, carbon monoxide, carbon dioxide and methane in addition to water and nitrogen. Methods for calculating saturation, isenthalpic and constant relative concentration lines are presented. Psychrometric charts of the different tar components are finally plotted at atmospheric pressure. Results show that temperature of 196.15 K is required to reduce the tar content to 0.001 g.Nm−3. [Display omitted] •Tar removal via a secondary physical method at low temperature by condensation.•Fluoranthene, naphthalene, indene, phenol and toluene represent tar components.•Indicate the temperature required to start removal process per tar category.•Liquid-Vapor, Solid-Vapor equilibrium and enthalpy function of temperature.