Hot and Dry Cleaning of Biomass-Gasified Gas Using Activated Carbons with Simultaneous Removal of Tar, Particles, and Sulfur Compounds

Abstract

This study proposes a gas-cleaning process for the simultaneous removal of sulfur compounds, tar, and particles from biomass-gasified gas using Fe-supported activated carbon and a water-gas shift reaction. On a laboratory scale, the simultaneous removal of H 2 S and COS was performed under a mixture of gases (H 2 /CO/CO 2 /CH 4 /C 2 H 4 /N 2 /H 2 S/ COS/steam). The reactions such as COS + H 2 → H 2 S + CO and COS + H 2 O → H 2 S + CO 2 and the water-gas shift reaction were promoted on the Fe-supported activated carbon. The adsorption capacity with steam was higher than that without steam. On a bench scale, the removal of impurities from a gas derived from biomass gasification was investigated using two activated filters packed with Fe-supported activated carbon. H 2 S and COS, three-and four-ring polycyclic aromatic hydrocarbons (PAHs), and particles were removed and a water-gas shift reaction was promoted through the first filter at 320-350 °C. The concentrations of H 2 S and COS decreased to less than 0.1 ppmv. Particles and the one-and two-ring PAHs, except for benzene, were then removed through the second filter at 60-170 °C. The concentration of tar and particles decreased from 2428 to 102 mg Nm and from 2244 to 181 mg Nm −3 , respectively.

Production of Activated Carbon within the Dual Fluidized Bed Gasification Process

“…27−30 For example, Fe-supported AC has been shown to reduce significantly the concentration of H 2 S (from 200 to 1 ppm) in a simulated product gas. 27 In another study, the concentration of tars in the product gas produced from wood gasification was decreased 6fold when AC was used, as compared to a situation in which no AC was used. 29 Activated carbon is a term that is commonly used for carbonaceous materials that have high surface areas and porosities and that are used as adsorbents in gas, liquid, and other purification systems.…”

“…42,43 Most of the AC applied in various gas cleaning studies have BET surface areas in the range of 800−1300 m 2 /g. 27,29,44 In the marketplace, this type of AC costs in the range of 3−4 €/kg (price level in, 2014).…”

“…H 2 S, tars, and SO 2 can be removed by wet scrubbing. , Although wet scrubbing is a well-proven method that is widely applied to handle impurities in the raw gas from gasification processes, the treatment and disposal of the wastewater may entail economic and environmental challenges for the overall process. ,− Furthermore, the thermal efficiency of the process can be decreased, as all the sensible heat of the raw gas from the gasification process is lost in the scrubbing process . To mitigate these effects, various hot gas cleaning methods are being developed. ,,− In some of these methods, AC is used as a catalyst support or, in some rare cases, is used without any catalyst. − For example, Fe-supported AC has been shown to reduce significantly the concentration of H 2 S (from 200 to 1 ppm) in a simulated product gas . In another study, the concentration of tars in the product gas produced from wood gasification was decreased 6-fold when AC was used, as compared to a situation in which no AC was used .…”

Development of a simplified gas ultracleaning process: experiments in biomass residue-based fixed-bed gasification syngas

“…As presented in our previous paper [6], a novel low-to medium-temperature final gas cleaning process based on adsorption and organic solvent-free scrubbing was developed, constructed, and finally coupled to a bubbling-fluidized bed gasifier with hot filter and reformer and downstream Fischer-Tropsch (FT) synthesis. Dry-bed contaminant control is primarily carried out using activated carbons, which are inexpensive multipurpose adsorbents that may also possess beneficial catalytic properties [7]. This final gas cleaning process replaces the capital-intensive wetscrubbing processes which are optimized for syngas purification at a larger scale of hundreds of MW of fuel input.…”

Preparation for Pt-Loaded Zeolite Catalysts Using w/o Microemulsion and Their Hydrocracking Behaviors on Fischer-Tropsch Product

“…The product was produced through an operation of a bench-scale BTL plant installed at AIST Chugoku (Hiroshima, Japan) [36,37]. The BTL plant utilized the woody biomass gasification with oxygen-enriched air/CO2 as a gasifying agent and the FT synthesis over Co+Mn+Zr/SiO2 catalysts [38].…”