R. BINDIG, S. BUTT, and I. HARTMANN

6.1 INTRODUCTION

The use of biomass or bioenergy can be traced back to the beginning of hu­man civilization when people started to burn wood for heating and cook­ing purposes. Ironically, after so many years have gone by, wood still re­mains the largest biomass resource in the world [1]. However, one major difference which has occurred over this period of time is the introduction of the concept “modern biomass” which states the usage of traditional bio­mass resources in highly efficient systems. This concept has been put into practice with more conviction and determination during the last decade, particularly in Europe, due to ever rising CO2 levels in our environment. By now, it is an established fact that about 10-30% of total energy demand for hot water supply and domestic heating in European countries like, Aus­tria, Germany, Sweden and Finland is provided by small scale biomass

Emission Abatement at Small-Scale Biomass Combustion Unit with High-Temperature Catalysts. © Bindig R, Butt S, and Hartmann I. Journal of Thermodynamics & Catalysis 4,125 (2013), doi: 10.4172/2157-7544.1000125. Licensed under Creative Commons Attribution License, http://creative- commons. org/licenses/by/4.0/.

combustion systems [2]. Moreover, it has been also concluded that despite the vast spread of technologically advanced small scale combustion devices in European countries (like countries mentioned above) during the recent years, still the old biomass combustion systems (stoves and boilers) occupy more consumers [3]. These conventional systems which are based on natu­ral draft play a pivotal role in contributing to the high emission levels of par­ticulate matter (PM), carbon monoxide (CO), organic gaseous compounds (OGC) and polycyclic aromatic hydrocarbons (PAH). These facts and fig­ures have triggered an enormous understanding and awareness among the researchers as well as local population concerning harmful pollutants emit­ted by residential biomass combustion systems. For this reason inefficient small scale biomass combustion systems have been heavily criticized and demanded to be replaced by new efficient technologies.

Speaking of older and newer technologies, it has to be mentioned here that two types of technologies exist concerning small scale bio­mass combustion systems. The old biomass combustion systems are based on “up-burn” which is in a process of being rapidly replaced by “down-firing” systems (new technologies). As mentioned above, these older systems are a main source of PM1 (particles with diameter less than 1 pm) in European countries. It has been also concluded that such particles serve as a purpose of “support” onto which carbonaceous par­ticles (organic compounds and soot) are deposited which are primarily responsible for the adverse health effects [4]. So in order to counter such an undesired release of pollutants, particularly from small scale biomass systems, a concept has been conceived according to which “down-firing” technology will be implemented in specially designed wood log stove in combination with catalytic treatment in order to abate harmful emis­sions to minimum possible values. It is noteworthy to mention here that the abatement of emissions through catalytic treatment from small scale biomass combustion systems has not been studied or implemented on a wide scale. So this novel concept of integrating catalytic components in different parts of the stove i. e. grate, walls of combustion chamber and the base will open more channels and schemes in order to accomplish the acceptable emission levels coming out of biomass combustion systems particularly, those used for residential purposes.

FIGURE 2: Time-dependent behavior of temperature during the reference experiment.

In the past, the process of catalysis has been strongly linked to chemi­cal and refinery industries. However, recently the catalytic converters have been deployed and installed in automobiles, biomass fired boilers and power generation facilities in order to promote the environmentally friendly usage of technological devices. It has been estimated that the mar­ket of catalysis around the world worth around US$9 billion, out of which, one third is occupied by the environmental catalysis. So building on this ever growing trend of environmental catalysis, this article gives a further insight into the integration of catalytic components in a downdraft wood log stove to foresee the feasibility of this novel approach to resolve the problem of high emissions (e. g. carbon monoxide, volatile organic com­pounds, dust particles etc.) at small-scale furnaces for solid biomass.