Janusz Licki

Reduction of VOCs in flue gas from coal combustion by electron beam treatment

Abstract Coal combustion is one of the biggest sources of VOCs, which are emitted with various concentrations, polynuclear aromatic hydrocarbons (PAH) are known as the most dangerous, and among them, e.g. benzo(a)pyrene C 20 H 12 , benzo(g,h,I)perylene C 22 H 12 or dibenzo(a,h)anthracene C 22 H 14 are the most toxic according to EPA. Recent years have brought new regulations concerning PAH emission, and European countries have signed an international treaty, covering PAH emission. Tests at the pilot plant constructed at a coal-fired power station were performed with the purpose of estimating the influence of electron beam on VOCs present in flue gas, during SO 2 and NO x removal. The influence of electron beam on the global toxicity factor of flue gas has been analysed. In the presence of ammonia, the concentrations of some PAHs were lower than that without ammonia. The removal efficiencies have been ranged from 40% up to 98%.

Pilot plant for flue gas treatment with electron beam -start up and two stage irradiation tests

Abstract The pilot plant for flue gas treatment with electron beam has been built at Power Plant Kaweczyn, near Warsaw. The irradiation part of the pilot plant has been put in operation in 1991 whereas the complete installation including bag filter started to work in spring 1992. The starting tests consisted of studying the components reliability and influence of the two-stage irradiation process on efficiency of NO x removal. The results have shown that the two- stage irradiation leads to remarkable energy savings and retains high NO x removal. The mathematical models of the double and triple irradiation process are discussed.

Pilot plant for flue gas treatment-continuous operation tests

Abstract Tests of continous operation have been performed on pilot plant at EPS Kaweczyn in the wide range of SO 2 concentration (500–3000 ppm).The bag filter has been applied for aerosol separation. The high efficiences of SO 2 and NO X removal, approximately 90% were obtained and influenced by such process parameters as: dose, gas temperature and ammonia stoichiometry. The main apparatus of the pilot plant (e.g. both accelerators) have proved their reliability in hard industrial conditions.

Pilot plant for electron beam flue gas treatment

Double stage gas irradiation (2 electron accelerators, 50 kW700 keV each) is the main technological principle employed in the Polish pilot plant (20,000 Nm3/h) constructed at EPS Kawȩczyn (low/medium sulphur coal). The pilot plant design is described in the paper.

OPTIMIZATION OF ENERGY CONSUMPTION FOR NOx REMOVAL IN MULTISTAGE GAS IRRADIATION PROCESS

Abstract Previously reported results of the tests performed on industrial pilot plant for EB flue gas treatment has proved the theoretical assumption that multistage gas irradiation leads to power consumption savings in comparison with single gas irradiation process. In this paper the results of theoretical and experimental studies are presented concerning optimization of the ratio of dose distribution between the particular stages. Nonuniform dose distribution causes further decrease in power consumption for NOx removal.

Sulphur isotope compositions of components of coal and S-isotope fractionation during its combustion and flue gas desulphurization

Sulphur isotope compositions were determined in two different Polish coals (hard coal and lignite) and by-products originating from their combustion. The desulphurization process was also investigated. It was demonstrated that desulphurization changes the isotopic composition of sulphur emitted in the form of SO2 to the atmosphere even if the process is conducted in a different way (wet lime technology and electron beam method). This fact has to be considered in the studies regarding anthropogenic sulphur genesis and its fate in the environment.

Electron Beam Technology for Multipollutant Emissions Control from Heavy Fuel Oil-Fired Boiler

Abstract The electron beam treatment technology for purification of exhaust gases from the burning of heavy fuel oil (HFO) mazout with sulfur content approximately 3 wt % was tested at the Institute of Nuclear Chemistry and Technology laboratory plant. The parametric study was conducted to determine the sulfur dioxide (SO2), oxides of nitrogen (NOx), and polycyclic aromatic hydrocarbon (PAH) removal efficiency as a function of temperature and humidity of irradiated gases, absorbed irradiation dose, and ammonia stoichiometry process parameters. In the test performed under optimal conditions with an irradiation dose of 12.4 kGy, simultaneous removal efficiencies of approximately 98% for SO2 and 80% for NOx were recorded. The simultaneous decrease of PAH and one-ringed aromatic hydrocarbon (benzene, toluene, and xylenes [BTX]) concentrations was observed in the irradiated flue gas. Overall removal efficiencies of approximately 42% for PAHs and 86% for BTXs were achieved with an irradiation dose 5.3 kGy. The decomposition ratio of these compounds increased with an increase of absorbed dose. The decrease of PAH and BTX concentrations was followed by the increase of oxygen-containing aromatic hydrocarbon concentrations. The PAH and BTX decomposition process was initialized through the reaction with hydroxyl radicals that formed in the electron beam irradiated flue gas. Their decomposition process is based on similar principles as the primary reaction concerning SO2 and NOx removal; that is, free radicals attack organic compound chains or rings, causing volatile organic compound decomposition. Thus, the electron beam flue gas treatment (EBFGT) technology ensures simultaneous removal of acid (SO2 and NOx) and organic (PAH and BTX) pollutants from flue gas emitted from burning of HFO. This technology is a multipollutant emission control technology that can be applied for treatment of flue gas emitted from coal-, lignite-, and HFO-fired boilers. Other thermal processes such as metallurgy and municipal waste incinerators are potential candidates for this technology application.

Empirical models for NOx and SO2 removal in a double stage flue gas irradiation process

Abstract A multidimensional regression method has been applied to construct empirical model equations of NOx and SO2 removal efficiency in e–b process for a two-stage irradiation system based on results achieved for the EPS Kaw e czyn pilot plant. The influence of different parameters such as dose, temperature, gas humidity and ammonia stoichiometry have been studied. Model equations describe with satisfactory accuracy experimental results. Therefore obtained models equations can be used for prediction of NOx and SO2 removal efficiency in e–b process during two-stage irradiation of flue gases, particularly in the case of scale-up. The results will be implemented in the industrial electron beam flue gas treatment installation being constructed at EPS Pomorzany, Dolna Odra PS Group SA, Poland (flue gas flow 270,000 N m3/h, total beam power of applied accelerators 1.2 MW).

OFF-LINE SYSTEM FOR MEASUREMENT OF NITROUS OXIDE CONCENTRATION IN GASES LEAVING THE IRRADIATION CHAMBER

Abstract The N 2 O concentration in the gas leaving the irradiation chamber was determined by off-line gas chromatographic analysis. The grab sample system involved the scrubber with a 1.0 N NaOH solution and the drying columns. The paper presents preliminary results of N 2 O concentration measurement for two different gas irradiation doses with other technological parameters of the pilot installation being constant.

Electron beam treatment of exhaust gas with high NOx concentration

Simulated exhaust gases with a high NOx concentration, ranging from 200 to 1700 ppmv, were irradiated by an electron beam from an accelerator. In the first part of this study, only exhaust gases were treated. Low NOx removal efficiencies were obtained for high NOx concentrations, even with high irradiation doses applied. In the second part of study, gaseous ammonia or/and vapor ethanol were added to the exhaust gas before its inlet to the plasma reactor. These additions significantly enhanced the NOx removal efficiency. The synergistic effect of high SO2 concentration on NOx removal was observed. The combination of electron beam treatment with the introduction of the above additions and with the performance of irradiation under optimal parameters ensured high NOx removal efficiency without the application of a solid-state catalyst.