Exergy analysis of biomass-to-synthetic natural gas (SNG) process via indirect gasification of various biomass feedstock

This paper presents an exergy analysis of SNG production via indirect gasification of various biomass feedstock, including virgin (woody) biomass as well as waste biomass (municipal solid waste and sludge). In indirect gasification heat needed for endothermic gasification reactions is produced by burning char in a separate combustion section of the gasifier and subsequently the heat is transferred to the gasification section. The advantages of indirect gasification are no syngas dilution with nitrogen and no external heat source required. The production process involves several process units, including biomass gasification, syngas cooler, cleaning and compression, methanation reactors and SNG conditioning. The process is simulated with a computer model using the flow-sheeting program Aspen Plus. The exergy analysis is performed for various operating conditions such as gasifier pressure, methanation pressure and temperature. The largest internal exergy losses occur in the gasifier followed by methanation and SNG conditioning. It is shown that exergetic efficiency of biomass-to-SNG process for woody biomass is higher than that for waste biomass. The exergetic efficiency for all biomass feedstock increases with gasification pressure, whereas the effects of methanation pressure and temperature are opposite for treated wood and waste biomas

Renewable glycoaldehyde isolation from pyrolysis oil by reactive extraction with primary amines

The transition to a sustainable bio-based economy has rapidly increased the interest to obtain renewable platform chemicals from biomass. Glycolaldehyde is one of potential future platform chemicals, which is present in high quantity (5–13 wt%) in wood-derived pyrolysis oil. Water addition to pyrolysis oil isolates glycolaldehyde and other polar compounds, nearly quantitatively in the aqueous phase. In order to apply extraction for the subsequent glycolaldehyde recovery a water-insoluble solvent is required. This work was done to identify a suitable solvent. Firstly, several long chain alkanes and alcohols were evaluated by extracting an aqueous solution of 6.2 wt% glycolaldehyde. The results demonstrated that alkanes cannot extract glycolaldehyde whereas the distribution coefficient of glycolaldehyde in alcohols decreases with chain length, from 0.23 for 1-octanol to 0.04 for oleyl alcohol. Due to low distribution coefficients, primary amines were considered extractants since they can form reversible imines with aldehydes. A solution of 1 M Primene JM-T in 1-octanol and pure Primene JM-T increases the distribution coefficient of glycolaldehyde in 1-octanol by a factor of 10 and 75, respectively. The extraction factors are 0.46 for 1-octanol, 3.79 for 1 M Primene JM-T in 1-octanol and 30.87 for pure Primene JM-T. Another alternative is aniline derivatives. At a concentration of 1 M, 4-ethylaniline gives more than two orders of magnitude higher distribution ratio than 2-ethylaniline and Primene JM-T. The extraction capability of amines is: octylamine >4-ethylaniline >phenylethylamine >>Primene JM-T >2-ethylaniline. In conclusion, highly branched primary amines and orthoalkylanilines are promising extractants, taking into account the reversibility of the Schiff base formation. The final selection of the most suitable extractant/diluent combination will depend on the actual selectivity towards glycolaldehyde and back-extraction yield

Laboratory scale conceptual process development for the isolation of renewable glycolaldehyde from pyrolysis oil to produce fermentation feedstock

A laboratory-based separation sequence has been developed to produce an aqueous glycolaldehyde solution as fermentation feedstock. It consists of water extraction of pyrolysis oil, acid removal, water removal, octanol extraction, phenolic removal, back-extraction, and washing. The octanol-free aqueous glycolaldehyde solution contains approximately 4 wt% glycolaldehyde, which meets the requirement of fermentation feedstoc

Production of discrete oxygenated target chemicals from pyrolysis oil

Biomass is a promising renewable feedstock for chemicals. Pyrolysis of biomass produces a dark, brown coloured liquid (bio oil), which consists of a complex mixture of oxygenated hydrocarbons, water and char. The key advantage of the produced bio-liquids over crude oil is their high content of oxygenates

Possibilities of Using Liquids from Slow Pyrolysis and Hydrothermal Carbonization in Acidification of Animal Slurry

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