Demonstration of a Top-Lit Updraft Based Pyrolytic Burner with Low Emission Operation and Automatic Process Control

Dennis Krüger,Özge Çepelioğullar Mutlu

doi:10.3390/en14133913

Abstract

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.

Highlights

Thermo-chemical conversion is the most common and developed technology in which biomass can be utilized as fuel to produce useful energy or energy carriers from small-medium to large scale industrial activities as well as space heating or cooking [1]
Traditional combustion systems are known as the source of particulate matter (PM) and gaseous emissions including CO, NOx, SOx polycyclic aromatic hydrocarbons (PAH), and volatile organic compounds (VOC)
In small-scale appliances which are mostly based on natural draft and operated as batch or semi-continuous, the emissions as a result of incomplete combustion of biomass is one of the disadvantages compared to fossil fuelbased combustion [7]

Summary

Introduction

Thermo-chemical conversion is the most common and developed technology in which biomass can be utilized as fuel to produce useful energy (i.e., heat or electricity) or energy carriers (i.e., charcoal, bio-oil, gas) from small-medium to large scale industrial activities as well as space heating or cooking [1]. PM emitted from biomass combustion systems account for 20% of global urban PM emissions [2] They can be relatively higher compared to liquid and gaseous fueled systems and depend on the type of selected fuel, the design, and the capacity of the combustion unit [3,4]. Due to their chemical/physical properties, PM suspensions can accumulate in the air [5]. Exposure to these resulting emissions has a negative impact on human health in the long-term [6]. The development of biomass combustion systems with lower emissions to meet social and economic development and improve human welfare and health become even more critical in addition to the environmental issues [6,8,9]

Objectives

Methods

Results

Conclusion