Klaus Woletz

Analyses of products formed by electron beam treatment of VOC/air mixtures

Abstract Butylacetate and xylene were irradiated with electron beam in the dose range of 0–10 kGy at ambient temperature and the removal efficiencies measured by FID and gas chromatography. Gaseous reaction products were measured by FT-IR spectroscopy and by wet sampling of the irradiated gas. Ion chromatographic analyses of the gaseous samples showed that formic, acetic, propionic and butyric acids were important products for the irradiation of butylacetate and xylene. Aerosols were only formed by irradiation of xylene. The overall composition of the aerosols at 10 kGy can be represented by the formula C 25 H 36 O 16 N. Mass balance of experiments for butylacetate and xylene was calculated on the basis of C-balance (mgC/Nm 3 ) and more than 80% recovery was obtained in all experiments. The reaction mechanism is discussed briefly.

Removal of volatile organic compounds from industrial offgas by irradiation induced aerosol formation

Abstract Organic trace components can be removed efficiently from largevolumes of industrial offgas by irradiation with 300 keV electrons. The major reaction product is a sub μm aerosol besides CO and CO 2 . A complete carbon balance of the process was established. The energy efficiency of the process is significantly higher than for conventional technology.

Removal of butylacetate and xylene from air by electron beam a product study

Abstract VOC emissions from industrial processes can cause hazardous impacts on the environment through increased ozone and smog formation. Previously, it was demonstrated that the electron beam technology is a powerful tool to scrub small amounts of VOC from large volume flows at ambient temperature. In this paper, product analyses are presented for the removal of common aliphatic and aromatic hydrocarbons from air. Butylacetate and xylene were added to an air stream of 1000 Nm 3 /h at concentration levels close to 100 mg C/Nm 3 , and irradiated with 550 keV electrons at the AGATE-2 pilot plant of KfK. The removal efficiencies were measured by FID and GC in the dose range 0–10 kGy. The removal efficiency of xylene was found to be close to 90% at 10 kGy which is almost twice as high as that of butylacetate. Three types of products were measured quantitatively by wet chemical analysis, filtration, and FTIR: (i) organic acids (formic, acetic, propionic, butyric acid) (ii) aerosol (iii) inorganic products and by-products (CO, CO 2 , O 3 , NO X ) The major product obtained from xylene irradiation was a particulate matter with a molecular C/O ratio close to 1.5. No aerosol formation was observed in case of butylacetate, the major irradiation product of which was acetic acid. Less than 15% of the removed carbon were converted to CO and CO 2 in both cases. The total carbon balance was 95 ± 15% in all experiments. By model calculation with the AGATE-code, the removal efficiencies and product distributions can be interpreted starting from OH radical attack on the hydrocarbon molecules and subsequent mechanisms which are known from atmospheric chemistry.

Collection of Fine Particles by Novel Wet Electrostatic Precipitator

A novel wet electrostatic precipitator is designed for control of fine aerosol from humid effluent gases. It operates on the principle of unipolar particle charging in a DC corona discharge in a high velocity (> 20 m/s) ionizing stage and aerosol precipitation in the low velocity (< 3 m/s) collection stage under the field of particle own space charge. The high gas velocity in the ionizing section diminishes the corona suppression at high particle number concentrations of H2SO4 and HCl aerosol.

Fine particle generation, evolution and control by small biomass combustion

Purpose – The aim of the paper is to present the results of investigations of fine particle generation by small biomass combustion and the possibility of reducing the emissions by electrostatic precipitation.Design/methodology/approach – The grains, wood‐logs, wood‐, mixed‐ and straw‐pellets were combusted in two stoves and two boilers. The set‐ups were operated according to DIN‐4702. Particle number concentration in the gas flow was measured by Scanning Mobility Particle Sizer and particle mass concentration was measured according to the Guidelines VDI‐2066 upstream and downstream a novel space charge electrostatic precipitator (ESP). The ESP consists of an ioniser and a grounded brush inside of a tube form grounded collector electrode.Findings – The ESP ensures stable operation at gas temperatures up to 350°C. The use of sharp‐points high voltage electrode ensures effective particle charging at high particle number concentrations. The combustion of wood‐pellets is characterized by lower particle mass co...

Application of space-charge electrostatic precipitator for collection of oil mist from pyrolysis gases

A novel electrostatic precipitator CAROLAreg is developed for collection of fine oil mists. It operates on the principle of unipolar particle charging in the corona discharge and particle precipitation under the field of space charge. The pilot precipitator was tested at different gas temperatures. It is shown that the increase of gas temperature changes the characteristics of the corona discharge and particle size distribution, especially for droplets sub-micron droplets. The CAROLAreg precipitator was used for collection of oil mist from pyrolysis gases at the HALOCLEANreg plant. The flow rate of biomass in the HALOCLEANreg plant was 15-30 kg/h. The particle mass concentration in the raw gas was over 100 g/Nm3. The operation voltage of the precipitator was 10-12 kV and corona current up to 0,1 mA. Single stage electrostatic precipitator ensured mass collection efficiency 97-99,5% for pyrolysis oil mist.