Fjjg Frans Janssen

A review of the primary measures for tar elimination in biomass gasification processes

Tar formation is one of the major problems to deal with during biomass gasification. Tar condenses at reduced temperature, thus blocking and fouling process equipments such as engines and turbines. Considerable efforts have been directed on tar removal from fuel gas. Tar removal technologies can broadly be divided into two approaches; hot gas cleaning after the gasifier (secondary methods), and treatments inside the gasifier (primary methods). Although secondary methods are proven to be effective, treatments inside the gasifier are gaining much attention as these may eliminate the need for downstream cleanup. In primary treatment, the gasifier is optimized to produce a fuel gas with minimum tar concentration. The different approaches of primary treatment are (a) proper selection of operating parameters, (b) use of bed additive/catalyst, and (c) gasifier modifications. The operating parameters such as temperature, gasifying agent, equivalence ratio, residence time, etc. play an important role in formation and decomposition of tar. There is a potential of using some active bed additives such as dolomite, olivine, char, etc. inside the gasifier. Ni-based catalyst are reported to be very effective not only for tar reduction, but also for decreasing the amount of nitrogenous compounds such as ammonia. Also, reactor modification can improve the quality of the product gas. The concepts of two-stage gasification and secondary air injection in the gasifier are of prime importance. Some aspects of primary methods and the research and development in this area are reviewed and cited in the present paper.

Thermodynamics of gas-char reactions: first and second law analysis

In energytransformation processes such as combustion, gasi

Integration of a turbine expander with an exothermic reactor loop—Flow sheet development and application to ammonia production

cation and reforming of fossil and renewable fuels, the conservation of energy(

Utilisation of reactor heat in methanol synthesis to reduce compressor duty––application of power cycle principles and simulation tools

rst law of thermody namics) as well as the qualityof energy(second law of thermody namics) is important. This studyfocuses on the conversion of biomass with air and/or steam into gaseous components and char represented bysolid carbon (graphite). Energy and exergy (available energy) losses are analysed by calculating the composition of a dry, ash-free typical biomass feed represented by CH1:4O0:59N0:0017 in equilibrium with varying amounts of air and/or steam. The analysis is carried out for adiabatic systems at atmospheric pressure, with input of biomass and air at ambient conditions and steam at atmospheric pressure and temperature of 500 K. For air gasi

Torrefaction of wood: Part 2. Analysis of products

cation, energyand exergyin the product gas have a sharp maximum at the point where all carbon is consumed, the carbon boundarypoint. This is the optimum point for operating an air-blown biomass gasi

More efficient biomass gasification via torrefaction

er. For gasi

Torrefaction of wood. Part 1. Weight loss kinetics

cation with steam, operation at the carbon boundarypoint is also optimal, but thermody namic process losses hardlyincrease when adding more steam than required. The e9ciencyof steam and air-blown gasi

From coal to biomass gasification : comparison of thermodynamic efficiency

cation was compared using the de

Pretreated olivine as tar removal catalyst for biomass gasifiers : investigation using naphthalene as model biomass tar

nition of rational e9ciency . Although gasi

Olivine as tar removal catalyst for biomass gasifiers: Catalyst characterization

cation bysteam is more e9cient (87.6% vs. 80.5%), this di=erence is expected to level o= if exergylosses for the production of steam are taken into account. The choice between steam and air as a gasifying medium therefore seems to depend more on the required gas compositions. For steam gasi