FG Mechanische Verfahrenstechnik
Refine
Year of publication
Document Type
- Conference Proceeding (74)
- Article (51)
- Scientific journal article peer-reviewed (19)
- Doctoral thesis (10)
- Conference publication not peer-reviewed (8)
- Conference publication peer-reviewed (8)
- Patent (7)
- Scientific journal article not peer-reviewed (5)
- Part of a book (chapter) (5)
- Image (poster) (4)
Way of publication
- Open Access (1)
Keywords
- Elektroabscheider (13)
- Aerosole (11)
- Gasreinigung (10)
- Partikelmesstechnik (10)
- Aerosol (6)
- electrostatic precipitation (6)
- Electrostatic precipitation (5)
- Corona Quenching (4)
- Extinktion (4)
- Filter (4)
Institute
BTU
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.
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.
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.