TY - CHAP A1 - Bürger, Patrick A1 - Flores-Alsina, Xavier A1 - Arellano-García, Harvey A1 - Gernaey, Krist V. ED - Espuña, Antonio ED - Graells, Moisès ED - Puigjaner, Luis T1 - Improving the prediction of phosphate dynamics in biotechnological processes: A case study based on antibiotic production using Streptomyces coelicolor T2 - 27th European Symposium on Computer Aided Process Engineering, Spain, 2017 KW - Streptomyces coelicolor KW - speciation modelling KW - polyphosphate KW - precipitation Y1 - 2017 SN - 978-0-444-63965-3 SP - 2869 EP - 2874 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Bürger, Patrick A1 - Flores-Alsina, Xavier A1 - Arellano-García, Harvey A1 - Gernaey, Krist V. T1 - Improved Prediction of Phosphorus Dynamics in Biotechnological Processes by Considering Precipitation and Polyphosphate Formation: A Case Study on Antibiotic Production with Streptomyces coelicolor T2 - Industrial & engineering chemistry research N2 - Improved Prediction of Phosphorus Dynamics in Biotechnological Processes by Considering Precipitation and Polyphosphate Formation: A Case Study on Antibiotic Production with Streptomyces coelicolor KW - Polyphosphate KW - Streptomyces coelicolor KW - Antibiotic Y1 - 2018 U6 - https://doi.org/10.1021/acs.iecr.7b05249 SN - 1520-5045 SN - 0888-5885 VL - 57 ER - TY - GEN A1 - Bürger, Patrick A1 - Riebel, Ulrich T1 - Characterization of flame-generated SiO2 aerosols and their utilization in research of high temperature electrostatic precipitation: A project outlook T2 - Jahrestreffen der ProcessNet-Fachgruppe Gasreinigung und des TAK Aerosoltechnik N2 - Gas-phase particle separation at significantly elevated temperatures is a scope since heat recovery units might be operated with higher efficiency and lower maintenance costs when fouling by particulate deposits could be reduced. However, this proves difficult for most separation techniques for numerous reasons (particle size limitations, material limitations, pressure difference limitations). While the upper temperature limit for standard electrostatic precipitators (ESP) operated at ambient pressure and with negative polarity is around 400°C, positive polarity theoretically should allow an operation with temperatures well above 600°C. However, there seems to be very little experience with high temperature ESPs even on the lab scale or small pilot scale. To close this apparent gap in electrostatic precipitation research our current project aims to investigate the characteristics of a SiO2 aerosol and the capabilities of an ESP dealing with said SiO2 aerosol at 600°C and above. The aerosol is produced by combustion of silicone oil (HMDSO) in a propane flame which leads to particle size distributions ranging from below 10 nm up to 400 nm. The median value of the distribution and the total number concentration is a function of the gaseous HMDSO amount introduced into the flame. Increasing the HMDSO supply shifts the median to larger particle diameters but also reduces the total number concentration, which is an interesting phenomenon to be looked into in more detail during the project since coagulation cannot explain this on its own. The observed high number concentrations at low HMDSO feed rates may involve thermal rebound which needs further investigation. Additionally, the bipolar charge distribution typical for flame-generated aerosols has to be considered when deriving an explanation for the observations. The next steps will be a more detailed characterization of the produced SiO2 aerosol and the operation of a high temperature ESP in wire-tube geometry. KW - electrostatic precipitation KW - SiO2 aerosols KW - aerosol science Y1 - 2018 U6 - https://doi.org/10.13140/RG.2.2.30701.95209 ER - TY - GEN A1 - Bürger, Patrick A1 - Riebel, Ulrich T1 - Behaviour of a flame-generated SiO2 aerosol in electrostatic precipitators at elevated temperatures: A back-corona investigation T2 - Jahrestreffen der ProcessNet-Fachgruppen Mechanische Flüssigkeitsabtrennung und Gasreinigung N2 - The removal of high-resistivity dusts from gas flows using electrostatic precipitators (ESPs) is challenging and requires counter-measures to suppress back-corona and subsequent particle re-entrainment. The critical dust layer thickness for the occurrence of back-corona may vary by several orders of magnitude depending on the specific dust resistivity, dust layer porosity, particle size, humidity and operating temperature. Despite the difficulties at elevated operating temperatures, processes involving highly resistive dusts (e.g. oxidic materials) may benefit significantly from utilizing high temperature ESPs (HT-ESPs). This is because the specific resistivity of materials like SiO2, Al2O3 and other oxides decreases below the critical value of 10^11 Ω*cm at higher temperatures. Currently, the separation of oxidic nanoparticle products relies on cloth filters which require exhaust gas quenching prior to dust removal. Using heat exchangers instead to recover excess heat is not feasible due to severe scale formation. Therefore, the development of a reliable HT-ESP would allow heat exchange at clean gas conditions reducing operating costs of the overall process. During preliminary experiments for our ongoing investigation of HT-ESPs, the behaviour of a flame-generated SiO2 aerosol was studied at 200°C in a wire-tube configuration. In order to reach a better understanding of the back-corona, measurements of the particle size distribution, particle charge distribution and electric current were conducted for both polarities. Strong effects are found even though the dust layer thickness is a few μm only. While the separation efficiency decreases rapidly after a critical dust layer thickness is reached, the current uptake increases significantly (up to a factor of 20), and a large number of inversely charged particles is found in the clean gas. These effects may indicate a large-scale back-corona. A detailed discussion will be given on the basis of aerosol size and mobility distributions, SEM images and resistivity measurements of the dust layer. We gratefully acknowledge the financial support for this project (EFRE-StaF 23035000) by the European Fund for Regional Development. KW - electrostatic precipitation KW - SiO2 aerosols KW - back corona KW - highly resistive dusts KW - gas cleaning Y1 - 2019 U6 - https://doi.org/10.13140/RG.2.2.34057.39528 ER - TY - GEN A1 - Bürger, Patrick A1 - Riebel, Ulrich T1 - Electrostatic Charging and Precipitation of Nanoparticles in Technical Nitrogen: Highly Efficient Diffusion Charging by Hot Free Electrons T2 - Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung N2 - Electrostatic charging and deposition of a liquid nano-aerosol was studied in dry air and in technical (3.6 % O2) nitrogen. The experiments have shown that electronic charging of aerosols can be important in technical scale electrostatic precipitators (ESPs). Already at operation voltages just slightly above the corona onset voltage, the contribution of the free electrons to the overall current is estimated to be around 50 %. Due to the high temperature of free electrons, diffusion charging by free electrons allows to reach exceptionally high particle charge and extremely high precipitation efficiency. A strongly simplified theoretical model was developed, which gives a good prediction of particle charge based on averaged values of particle diameter, current density, electric field strength, electron temperature and residence time. The ion mobilities were determined by fitting the current-voltage characteristics with a modified Townsend (Monrolin et al. 2018) equation and are significantly higher than the values typically used to describe diffusion charging in air. This may be ascribed to the very dry gas phase and the short average lifespan of the ions under ESP conditions, which is in the order of 1 ms. From the practical point of view, electronic charging might be relevant in a number of technical applications, including high temperature ESPs, ESP applications in dry and oxygen-free gases and pulsed corona systems. We gratefully acknowledge the financial support for this project (EFRE-StaF 23035000) by the European Fund for Regional Development. Monrolin, N., Praud, O., Plouraboué, F. 2018. Revisiting the positive DC corona discharge theory: Beyond Peek's and Townsend's law. Phys. Plasmas 25, 063503; doi: 10.1063/1.5031780. KW - electrostatic precipitation KW - electronic charging KW - free electrons KW - electron temperature KW - corona discharge KW - diffusion charging Y1 - 2020 U6 - https://doi.org/10.13140/RG.2.2.35735.11687 ER - TY - GEN A1 - Bürger, Patrick A1 - Riebel, Ulrich T1 - Electrostatic charging and precipitation of nanoparticles in technical nitrogen: Highly efficient diffusion charging by hot free electrons T2 - Journal of Aerosol Science N2 - Electrostatic charging and deposition of a liquid nano-aerosol was studied in dry air and in technical (3.6 % O2) nitrogen. The experiments have shown that electronic charging of aerosols can be important in technical scale electrostatic precipitators (ESPs). Already at operation voltages just slightly above the corona onset voltage, the contribution of the free electrons to the overall current is estimated to be around 50 %. Due to the high temperature of free electrons, diffusion charging by free electrons allows to reach exceptionally high particle charge and extremely high precipitation efficiency. A strongly simplified theoretical model was developed, which gives a good prediction of particle charge based on averaged values of particle diameter, current density, electric field strength, electron temperature and residence time. The ion mobilities were determined by fitting the current-voltage characteristics with a modified Townsend (Monrolin et al. 2018) equation and are significantly higher than the values typically used to describe diffusion charging in air. This may be ascribed to the very dry gas phase and the short average lifespan of the ions under ESP conditions, which is in the order of 1 ms. From the practical point of view, electronic charging might be relevant in a number of technical applications, including high temperature ESPs, ESP applications in dry and oxygen-free gases and pulsed corona systems. KW - electrostatic precipitation KW - corona discharge KW - free electrons KW - electron temperature KW - ion mobility KW - diffusion charging Y1 - 2020 U6 - https://doi.org/10.1016/j.jaerosci.2019.105495 SN - 1879-1964 SN - 0021-8502 IS - 141 ER - TY - GEN A1 - Bürger, Patrick A1 - Riebel, Ulrich T1 - Formation of highly resistive SiO2 nanoparticle layers from the aerosol by electrostatic precipitation at 200 °C: Observations on back corona and nanoparticle layer structure T2 - Journal of Nanoparticle Research KW - SiO2 aerosol KW - Nanoparticle layers KW - Highly resistive dust KW - Back corona KW - Electrostatic precipitation KW - Thermionic field emission Y1 - 2021 U6 - https://doi.org/10.1007/s11051-021-05292-4 SN - 1572-896X SN - 1388-0764 VL - 23 IS - 8 ER - TY - GEN A1 - Bürger, Patrick A1 - Riebel, Ulrich T1 - High temperature coronas in air and flue gas from LPG combustion: Current-voltage characteristics, ion mobilities and free electrons T2 - Journal of Electrostatics N2 - Positive and negative corona discharges were studied at atmospheric pressure in a tube-wire geometry with a tube diameter of 150 mm. Current-voltage characteristics (CVCs) were measured both in air and in flue gas produced with a liquefied petroleum gas (LPG) burner, covering temperatures from ambient up to 1073 K. Corona operation was stable over the whole temperature range with positive polarity and up to 973 K with negative polarity. Based on a detailed analysis of the original CVC measurements, new insights on the temperature-dependent mobility of gas ions, on the occurrence of free electrons and on the electronic current contribution are presented. Deviations from the Townsend theory of CVCs can be ascribed to the lifetime-dependency of ion mobility caused by the formation of cluster ions. The contribution from free electrons is found to depend on temperature and tube radius. KW - High-temperature gas cleaning KW - Electrostatic precipitation KW - Corona discharge KW - Current-voltage characteristics KW - Gas ion mobility KW - Free electrons KW - Onset voltage Y1 - 2022 UR - https://www.sciencedirect.com/science/article/pii/S0304388622000730 SN - 1873-5738 VL - 115 ER - TY - GEN A1 - Bürger, Patrick A1 - Riebel, Ulrich T1 - Feasibility of high-temperature electrostatic precipitation for the removal of nanoparticles: A case study on iron oxide separation at up to 800 ºC T2 - Journal of Electrostatics N2 - The removal of nanoparticles from hot gas streams is a challenging task. However, there is a huge potential for heat recovery from waste gas incineration, glass furnaces, ceramic, metallurgical, pyrolytic and many other high temperature processes. A prototype application is the separation of nanoparticles formed by condensation in thermal post-combustion processes, in order to achieve efficient heat recovery at high temperatures. This case study evaluates the performance of a high-temperature electrostatic precipitator (HT-ESP) between 400 and 800 ºC for both discharge polarities. The tube-type ESP with 150 mm diameter and 1500 mm length is operated isothermally. Two electrode designs are tested by separating flame-generated iron oxide nanoparticles from a flue gas atmosphere. The total number concentration in the raw gas is around 2*107 cm-3 with a temperature-dependent mode diameter of 20–40 nm. Between 400 and 600 ºC very high separation efficiencies around 99.998% (number-based) were found with just 1.5 s of residence time and negative polarity, using a wire discharge electrode. In fact, the separation is more efficient than at room temperature which is explained by particle charging with free electrons leading to an exceptionally high particle charge. At 700 ºC and 800 ºC, thermionic emissions become more relevant for ESP operation. In this range the best separation efficiencies of 99.96% and 99.5% respectively were obtained using a rod discharge electrode operated below the corona onset voltage. The specific input of energy required for 99% separation efficiency at any temperature is less than 250 J/m3. These findings clearly prove that HT-ESPs are a feasible and highly performing alternative for nanoparticle removal from hot gases at up to 800 ºC. KW - Electrostatic precipitation KW - High-temperature gas cleaning KW - Nanoparticles KW - Diffusion charging KW - Free electrons KW - Thermionic emission Y1 - 2022 U6 - https://doi.org/10.1016/j.elstat.2022.103754 SN - 1873-5738 VL - 120 ER - TY - GEN A1 - Bürger, Patrick A1 - Riebel, Ulrich T1 - Effiziente Hochtemperatur‐Gasreinigung mittels Elektroabscheider: Zukünftige Anwendungsgebiete zur Wertstoffrückgewinnung und optimierten Wärmeübertragung T1 - Efficient High-Temperature Gas Cleaning Using Electrostatic Precipitation: Future Areas of Application for Resource Recovery and Optimal Heat Recovery T2 - Chemie Ingenieur Technik N2 - High‐temperature gas cleaning is a challenge, especially when nanoparticles have to be separated from a hot gas stream. Thus, particle separation is often conducted after quenching the gas stream significantly. However, high‐temperature particle removal can substantially improve heat recovery in many existing industrial processes, as well as in upcoming pyrolytic processes and the flame‐based manufacturing of functional nanoparticles. This contribution describes the experimental results from a pilot‐scale high‐temperature electrostatic precipitator tasked with the removal of nanoparticles from a flue gas atmosphere between 400–800 °C. Additionally, the underlying phenomena are explained, and the future applications are outlined. Over the whole temperature range a reliable and energy‐efficient particle separation was observed. This technology combined with a high‐temperature heat exchanger can strongly reduce the primary energy consumption of high‐temperature processes. N2 - Die Partikelabscheidung aus heißen Gasen, insbesondere die Abscheidung von Nanopartikeln, ist ein herausforderndes Unterfangen, das häufig durch das Quenchen des heißen (Ab)-Gasstroms umgangen wird. Allerdings verspricht die Heißgasreinigung eine verbesserte und effizientere Wärmerückgewinnung aus verschiedensten industriellen Prozessen. Neben den klassischen Hochtemperaturprozessen gewinnen auch Verfahren wie die flammenbasierte Herstellung von Nanopartikeln an Relevanz. In diesem Beitrag werden die experimentellen Ergebnisse eines Hochtemperatur-Elektroabscheiders im Technikumsmaßstab zur Nanopartikelabscheidung aus Verbrennungsabgasen bei 400–800 °C beschrieben sowie die zugrundeliegenden Phänomene und die daraus resultierenden zukünftigen Anwendungsgebiete. Über den gesamten untersuchten Temperaturbereich konnte ein robuster Betrieb mit einer energetisch sehr effizienten Abscheidung beobachtet werden. In Kombination mit einer Hochtemperatur-Wärmerückgewinnung ermöglicht das Verfahren zukünftig eine deutliche Reduktion des Primärenergiebedarfs von Hochtemperaturprozessen. KW - Diffusionsaufladung KW - Elektroabscheider KW - Hochtemperatur Gasreinigung KW - Nanopartikel KW - Thermionische Emission KW - Diffusion charging KW - Electrostatic precipitation KW - High‐temperature gas cleaning KW - Nanoparticles KW - Thermionic emission Y1 - 2024 U6 - https://doi.org/10.1002/cite.202300153 SN - 0009-286X SN - 1522-2640 VL - 96 IS - 3 SP - 340 EP - 346 ER -