Naslov
Hydrogen rich syngas from updraft gasification of lignocellulosic feedstock

Autori
Zimbardi, Francesco ; Cerone, Nadia ; Baleta, Jakov

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Proceedings of the European Combustion Meeting 2019 / Pereira, Sandrina ; Costa, Mário - Lisabon : Instituto Superior Técnico, 2019

Skup
9th European Combustion Meeting (ECM 2019)

Mjesto i datum
Lisabon, Portugal, 14.04.2019. - 17.04.2019

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
updraft gasification, water-gas shift reaction ; syngas composition ; lignocellulosic feedstock

Sažetak
Syngas is a mixture of carbon monoxide, hydrogen, carbon dioxide and lower percentages of incondensable hydrocarbons, like methane. It is a flexible energetic and chemical vector, and the process of its generation is flexible towards feedstock. Namely, any kind of material containing carbon can virtually be gasified: coal, biomass, organic urban waste. Fixed bed gasification is one of the most suitable process to exploit lignocellulosics because it can be carried out at small scale (<1MWth) with a relatively simple and robust technology. From fixed bed gasifier syngas can be draft from the bottom (downdraft type) of from the top (updraft type). The latter is characterized by higher energy efficiency conversion and enhanced flexibility of feedstock, as regard moisture content, size and composition. One of the most important parameter for the syngas use is the ratio H2/CO. In the reported work the focus is placed onto tuning syngas composition as a desirable feature of biomass gasification. Such process flexibility can be achieved by introducing steam in the system, by using oxygen or enriched air by a special reactor design (indirect gasification) ; by adding a catalytic step of water gas shift (WGS) or a CO2 adsorption step. Gasification was carried out in a pilot facility able to treat 20-30 kg/g of lignocellulosic feedstock. In the reported tests almond shells were used that maintain a good gas permeation when loaded as bulk. Main system component is a fixed bed, autothermal, updraft gasifier, operated slightly above atmospheric conditions. The gasifier has a cylindrical basic shape with a height of 2.4 m and diameter of 0.5 m. Air, oxygen, steam or mixtures of these can be used as the gasifying means ; the flow of gas is introduced into the lower part of the gasifier below the grate. Novelty of this work can be seen in the measuring evolution of gasification at different heights of the reactive biomass bed. This was achieved by probing syngas streams directly from the core and analyzing it onsite to measure the content of H2, CO2, CO, CH4, CnHm, N2, O2. The chemical composition was correlated to the thermal profile provided by in bed measurements of 7 thermocouples, plus 4 in freeboard. The plant is also equipped with section based on Water Gas Shift to increase the H2 yield. The use of steam increased the hydrogen content and positively affected the molar ratio H2/CO that reached the steady value of 1 by using air and steam as gasifying medium. In the tests, the biomass was completely converted in gaseous and liquid energy carriers with cold gas efficiency (CGE) ranging from 61% to 75%. With WGS the level of H2 in gas reached 37 vol % (53 vol % on nitrogen free basis) corresponding to a new increased H2/CO ratio of 9.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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