@inproceedings{BuergerFloresAlsinaArellanoGarciaetal., author = {B{\"u}rger, Patrick and Flores-Alsina, Xavier and Arellano-Garc{\´i}a, Harvey and Gernaey, Krist V.}, title = {Improving the prediction of phosphate dynamics in biotechnological processes: A case study based on antibiotic production using Streptomyces coelicolor}, series = {27th European Symposium on Computer Aided Process Engineering, Spain, 2017}, booktitle = {27th European Symposium on Computer Aided Process Engineering, Spain, 2017}, editor = {Espu{\~n}a, Antonio and Graells, Mois{\`e}s and Puigjaner, Luis}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {978-0-444-63965-3}, pages = {2869 -- 2874}, language = {en} } @misc{BuergerFloresAlsinaArellanoGarciaetal., author = {B{\"u}rger, Patrick and Flores-Alsina, Xavier and Arellano-Garc{\´i}a, Harvey and Gernaey, Krist V.}, title = {Improved Prediction of Phosphorus Dynamics in Biotechnological Processes by Considering Precipitation and Polyphosphate Formation: A Case Study on Antibiotic Production with Streptomyces coelicolor}, series = {Industrial \& engineering chemistry research}, volume = {57}, journal = {Industrial \& engineering chemistry research}, issn = {1520-5045}, doi = {10.1021/acs.iecr.7b05249}, abstract = {Improved Prediction of Phosphorus Dynamics in Biotechnological Processes by Considering Precipitation and Polyphosphate Formation: A Case Study on Antibiotic Production with Streptomyces coelicolor}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Characterization of flame-generated SiO2 aerosols and their utilization in research of high temperature electrostatic precipitation: A project outlook}, series = {Jahrestreffen der ProcessNet-Fachgruppe Gasreinigung und des TAK Aerosoltechnik}, journal = {Jahrestreffen der ProcessNet-Fachgruppe Gasreinigung und des TAK Aerosoltechnik}, doi = {10.13140/RG.2.2.30701.95209}, pages = {1}, abstract = {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.}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Behaviour of a flame-generated SiO2 aerosol in electrostatic precipitators at elevated temperatures: A back-corona investigation}, series = {Jahrestreffen der ProcessNet-Fachgruppen Mechanische Fl{\"u}ssigkeitsabtrennung und Gasreinigung}, journal = {Jahrestreffen der ProcessNet-Fachgruppen Mechanische Fl{\"u}ssigkeitsabtrennung und Gasreinigung}, doi = {10.13140/RG.2.2.34057.39528}, pages = {1}, abstract = {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.}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Electrostatic Charging and Precipitation of Nanoparticles in Technical Nitrogen: Highly Efficient Diffusion Charging by Hot Free Electrons}, series = {Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung}, journal = {Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung}, doi = {10.13140/RG.2.2.35735.11687}, pages = {1}, abstract = {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., Plourabou{\´e}, 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.}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Electrostatic charging and precipitation of nanoparticles in technical nitrogen: Highly efficient diffusion charging by hot free electrons}, series = {Journal of Aerosol Science}, journal = {Journal of Aerosol Science}, number = {141}, issn = {1879-1964}, doi = {10.1016/j.jaerosci.2019.105495}, pages = {17}, abstract = {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.}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Formation of highly resistive SiO2 nanoparticle layers from the aerosol by electrostatic precipitation at 200 °C: Observations on back corona and nanoparticle layer structure}, series = {Journal of Nanoparticle Research}, volume = {23}, journal = {Journal of Nanoparticle Research}, number = {8}, issn = {1572-896X}, doi = {10.1007/s11051-021-05292-4}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {High temperature coronas in air and flue gas from LPG combustion: Current-voltage characteristics, ion mobilities and free electrons}, series = {Journal of Electrostatics}, volume = {115}, journal = {Journal of Electrostatics}, issn = {1873-5738}, abstract = {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.}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Feasibility of high-temperature electrostatic precipitation for the removal of nanoparticles: A case study on iron oxide separation at up to 800 ºC}, series = {Journal of Electrostatics}, volume = {120}, journal = {Journal of Electrostatics}, issn = {1873-5738}, doi = {10.1016/j.elstat.2022.103754}, abstract = {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.}, language = {en} } @misc{BuergerRiebel, author = {B{\"u}rger, Patrick and Riebel, Ulrich}, title = {Effiziente Hochtemperatur-Gasreinigung mittels Elektroabscheider: Zuk{\"u}nftige Anwendungsgebiete zur Wertstoffr{\"u}ckgewinnung und optimierten W{\"a}rme{\"u}bertragung}, series = {Chemie Ingenieur Technik}, volume = {96}, journal = {Chemie Ingenieur Technik}, number = {3}, issn = {0009-286X}, doi = {10.1002/cite.202300153}, pages = {340 -- 346}, abstract = {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.}, language = {de} }