Characterization and integration of oxidation catalysts at small-scale biomass combustion furnaces

Abstract

Abstract. Small-scale biomass combustion is a major part in heat supply from renewable resources. Drawbacks to the environmental background are the pollutant emissions, which are formed as a result of maloperation, suboptimal furnace construction or the biomass fuel composition. The named primary factors can be influenced by several measures, but the achievable emission results are limited. To provide real clean combustion technology with nearly zero pollutant emissions, secondary emission reduction measures are necessary. One of these measures is the application of catalytic flue gas cleaning as integrated or downstream solution. Catalysis is already a state of the art element in many processes and following this, some studies reveal already its potential to reduce CO, VOC as well as particle emissions in small-scale biomass combustion systems. However, a wide application of catalysts in wood combustion units didn't take place so far, because the challenging process conditions demand a proper integration and highly stable and active catalytic materials. For the achievement of well-functioning combustion systems with catalyst solutions a procedure for application-oriented characterization is presented. Initial investigations with commercially available catalysts have shown that the gas hourly space velocity and the oxygen content have the most significant influence on the conversion rate of carbon monoxide and nitrogen oxide. Two samples with different active phases have been compared, one with solely metal oxides and one with metal oxides and noble metals. The one with noble metals showed as expected a higher activity, but also a higher stability.

Catalyst Activity Characterization and Proper Integration in Small‐Scale Biomass Combustion Systems

“…Heating was carried out with a rate of 10 K min -1 . The experiments and some selected results have been already described by Matthes et al [28]. In combination with the results published in this article, the comparison of the catalyst activity in model gas and real combustion flue gas as well as the evaluation of process impacts on activity and aging is possible.…”

“…A stepwise analytical procedure was developed and evaluated. The procedure has already been presented by Matthes et al [28] and is designed to characterize catalysts for small-scale combustion (Fig. 1).…”

“…The second step of the analytical procedure consists of investigations with real process gas while observing different combustion conditions. A continuously operating, downdraught, laboratory-scale combustion system with a heat output of 1-2 kW was used, which has been already described in detail [28,29]. The furnace has a cylindrical combustion chamber, in which catalysts can be integrated at differ-ent temperatures.…”

Investigations on the Influence of Catalyst Geometry on Emission Reduction in Small‐Scale Combustion System

“…locations within the small-scale combustion system. [14] More specifically, high-temperature catalysts with low or minimal noble metal content are typically installed closer to or within the combustion chamber of the system, where temperatures range between 300 and 800 °C. More active catalysts containing precious metals can operate downstream the combustion chamber in colder exhaust gases (T below 300 °C).…”

High Temperature Electrical Charger to Reduce Particulate Emissions from Small Biomass-Fired Boilers

“…The most studied after-treatment technologies for small-scale biomass combustion are ESPs [9][10][11], cyclones [12], scrubbers and condensing heat exchangers [13][14][15][16], fabric filters [17], and catalytic combustors [18,19]. Each of these technologies has their own benefits and problems regarding cost, ease of use, efficiency, and maintenance efforts.…”