In this study, a small-scale (4.7 kWfuel) biomass burner based on “top-lit updraft” (TLUD) technology with automatic process control was developed for process heat generation. The combustion experiments were performed using wood pellets to gain more insights on the process, its repeatability and the behaviors of the emitted gaseous and particulate emissions under different combustion phases. The emission values were compared with similar small-scale combustion technologies as well as the emission limits defined in official regulations. The results showed that the average emissions (based on standardized 13 vol. % O2 content in the dry flue gas (STP)) over the entire process from start-up to switch-off were 29.4 mg/m3 for CO, 80 mg/m3 for NOx, and 3.6 mg/m3 for total particle matter (TPM) measured within the hot gas. These results were below the official limits for wood-fueled small-scale systems. The developed process control approach resulted in very low residual O2 content in the flue gas (approx. 2 vol. %), high flue gas temperatures and repetition accuracy. Thus, the process offers potential for further development in terms of process control, scale-up, and application in different areas.
Single room heaters are usually type tested with constant draft and are allowed under these conditions. However, the mode of operation of the user's firing usually deviates significantly from these conditions of approval, since these are operated in most cases by natural draft and not by constant draft. Since the repeatability of natural draft is hardly given due to the changing environmental conditions, a simulation has been developed, which can simulate the natural draft with high accuracy. Thus, it is basically possible to replicate the natural draft with constant environmental conditions and to use it for test bench measurements. It is a purely physical simulation that does not require any calibration parameters. Chimney geometry and environmental boundary conditions, such as the outside temperature, can be chosen freely. In addition, the cost of the necessary hardware is very low, since the system only needs cheap thermocouples, pressure sensors, and a small USB module for data acquisition.
Based on the decision of representatives from the West African region and feedback from locals in Togo, an advanced continuous-feed, forced-draft, biomass cookstove named “Apeli” was developed. The stove was tested in modified ISO measurements based on the ISO 19867-1:2018 standard. This included a long shutdown operation using wood pellets and short shutdown operations using wood pellets, bamboo pellets, wheat straw pellets and palm kernel shells. Due to the fast shutdown capability, the short shutdown was chosen for more realistic results using this stove type. For cold start and long shutdown operation using wood pellets, the thermal efficiency is determined as 44.1% at a 1116 W power output by emitting 0.272 g CO and 17.2 mg PM 2.5 per MJd at high load. At low load, the efficiency is 38.0% at a 526 W power output by emitting 1.1 g CO and 45.1 mg PM 2.5 per MJd. Due to a misinterpretation of the standard, the burnout duration of the tests with long shutdown is approx. 1.5 min shorter than required. Using a worst-case approximation, values for a theoretical ISO-conforming measurement were calculated and rated according to the ISO 19867-3:2018 standard. The results showed that the Apeli would correspond to Tier 4 for efficiency and PM 2.5 as well as Tier 5 for CO in high-power operation using wood pellets. The use of alternative fuels is possible, but can lead to higher emissions compared to the use of wood pellets. With regard to possibly using the biochar produced in the process for soil application, it has been demonstrated that the PAH content ensures European BioChar-Agro-Organic limitations. The first results of a field test in Togo have shown that operating and feeding the stove by the target group is easy. The required permanent presence of the user during cooking with this stove seems to have a limited influence on acceptance, which seems to primarily depend on the age of the user. Moreover, it can be concluded that the Apeli has good potential to be mass-produced locally at low costs with a reliable supply of spare parts. This can contribute not only to improving clean cooking, but also to fighting air pollution and deforestation caused by solid fuel burning due to the reduced consumption of resources in the form of fuel, especially wood.
A joint project between West African Science Service Center on Climate Change and Adapted Land Use (WASCAL), the University of Lomé and the German Biomass Research Center (Deutsches Biomasseforschungszentrum; DBFZ) was initiated in 2020. The project aims at evaluating alternative and regenerative energy sources for rural areas and creating the basis for successful implementation. In three different work packages, therefore, biomass potentials should be quantified, technologies should be examined with regard to their suitability and - in the case of biogas application - a research structure, pilot biogas laboratory, should be created that is necessary to enable the sustainable implementation of technologies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.