Emission measurement data of a wood log stove with an integrated two-stage catalytic converter module

Published: 24-02-2018| Version 1 | DOI: 10.17632/2xcp6rytgw.1
Ingo Hartmann,
Sebastian Günther


Manually fired log wood stoves require a very effective and at the same time economically feasible emission reduction measure in order to be able to use log wood to cover the heat demand in private households in the future. Catalysts integrated in furnaces are a promising way to significantly reduce emissions from incomplete combustion (CO, VOC). In addition to these gaseous oxidizable pollutants, however, there is the big problem that particulate matter is emitted and that, without adapting and converting the combustion system, only about 20 % of particulate matter could be reduced by oxidative catalytic degradation of catalysts. In order to increase the dust reduction significantly, a two-stage catalytic converter module developed by Blue Fire GmbH was integrated in a simple wood-burning stove of the lower price segment (Manufacture: Justus, Model: Falun Stahl, 5 kW) and tested at the DBFZ under simulated natural draft conditions. In the first stage, the soot containing particles are initially retained. In the next step, a part of the carbon-containing components is degraded oxidatively in stage 1 and then discharged again by the flow from stage 1 in order to prevent blocking of stage 1. In the second catalyst stage, the gaseous pollutants CO and VOC are reduced. With this two-stage catalyst arrangement, the pollutants CO could be reduced by more than 80 %, VOC by 50 to 70 % and dust by more than 50 %. The following experimental set-ups were examined: Data from 27.09.2017: Measurement with stage 1 (ceramic packing) and stage 2 (Pt/Pd foam catalyst) and bypass in stage 1 Data from 29.09.2017: Reference Data from 15.11.2017: Measurement with stage 1 (ceramic packing) and stage 2 (Pt/Pd foam catalyst) without bypass in stage 1 Data from 03.01.2018: Measurement with modified stage 1 (ceramic filler with Pt coating) and modified stage 2 (V2O5 honeycomb) without bypass in stage 1 Data from 04.01.2018: Measurement with modified stage 1 (ceramic packing with Pt coating) and stage 2 (Pt/Pd foam catalyst) without bypass in stage 1 Data from 17.01.2018: Measurement with modified stage 1 (ceramic filler with Pt coating) and stage 2 (V2O5 honeycomb and Pt/Pd foam catalyst) without bypass in stage 1 The test setup and the evaluation methods are based on DIN EN 13240, as this method is used to achieve comparability of the results.


Steps to reproduce

No constant pressure or chimney draft is applied to the stove as a test setup; a simulated natural draft is used instead. This method was developed at DBFZ by Dennis Krüger in his diploma thesis "Simulation of the natural draught for test bench measurements" (D. Krüger und J. von Sonntag, Simulation des Naturzuges für Prüfstandmessungen, Hamburg: Technische Universität Hamburg-Harburg, 2011.) and was validated through several test measurement campaigns at DBFZ. In a normal chimney, the pressure fluctuates due to the weather or a different draft is applied, as the chimney has different dimensions than the chimney used in the type test. In order to maintain independence from the weather and other influences, typically a constant chimney draft of 12 Pa is applied in the type test. This constant draft, however, changes the behavior of the stove when it is started, as this causes a higher flow in the chimney. The starting behavior of the wood-burning stove is of interest in this work, since with the installation of the catalytic converter a pressure resistance is placed in the exhaust gas path. When igniting the fuel, it does not build up such a high draft that the pressure drop through the catalyst would be negligible. The chimney draft is produced by a flue gas fan. This requires the measurement of external pressure and temperature. The temperature and pressure as well as the flow velocity are also measured in the measuring section. The two temperatures, the external pressure and the flow velocity are used to calculate the flue draft that should prevail in the measuring section. This is compared with the actual draft and readjusted in case of deviations. This takes place in real time, with the exhaust gas flap being responsible for fine control, since the chimney fan only regulates roughly. At a height of 1500 mm above the stove the exhaust gas composition, flow velocity, delivery pressure and temperature were measured. For the exhaust gas composition, the FTIR, Fourier Transform Infrared Spectrometer, Gasmet CX 4000 from ANSYCO analytische Systeme und Componenten GmbH was used. For isokinetic dust sampling, a Prandtl tube and a thermocouple were installed below the dust sampling probe of Paul Gothe GmbH. Two resistance temperature sensors type PT1000 and two pressure sensors SDP 1000-L05 from Sensirion were used to control the natural draft simulation. After the stove had been heated, the burns for measuring emissions were kept identical. Standard commercial beech firewood was used. One log with a mass of 0.8 kg and a length of 250 mm was used per firing batch. The values of the fuel analysis displayed in file "Fuel properties".