Fredrik Klingstedt

Hydrothermally Stable Catalysts for the Removal of Emissions from Small-Scale Biofuel Combustion Systems

Catalytic oxidation of model pollutants, simulating the emissions from small-scale biofuel combustion systems, was studied over different fresh, aged and sulfur poisoned Pd-MeO/γ-alumina (Me = Ni, Ce and La) catalysts. Release of chlorine and restructuring of PdO particles was believed to cause activation of the Pd-MeO supported catalysts.

Artificial neural network modelling applied on NOx reduction with octane in excess oxygen over Ag/Al2O3

A silver/alumina catalyst was tested for its NOx reduction activity during oxygen-rich conditions and during variation in the input parameters, which were nitric oxide, octane and oxygen. The experimental data were investigated by means of artificial neural networks.

Catalytic Removal of NOx from Gas Mixtures Simulating Emissions from the Combustion of Biofuels

The activity of knitted silica-fibre supported Pd, Pt, Pt-Ni, Pd-Ni and Pd-Pt-Ni catalysts as well as Pd based H-ZSM-5 and H-ZSM-35 catalysts was studied in the conversion of gas mixtures containing 200 ppm CH4, 2500 ppm CO, 500 ppm pyridine (or 500 ppm NO), 10 vol.% O2 (or 0.155 vol.% O2), 12 vol.% CO2, 12 vol.% H2O, balanced with He at GHSV of 60000 h−1. Pyridine was found to inhibit both CO and CH4 oxidation. IR studies indicated that NO adsorbed on Pd2+ is the principal adsorbed species on the Pd/HZSM-5 catalyst.

ANN modeling applied to NOX reduction with octane. Ann future in personal vehicles

A silver/alumina catalyst was tested for its NOX reduction activity during oxygen-rich conditions and during variation in the input parameters (nitric oxide, octane and oxygen). A multi-bed approach was tested where the initial bed was divided into four beds acting in different temperature rages. The experimental data were investigated by means of artificial neural networks that were demonstrated to be able to model the process.

NOx and N2O Emission Formation Tendency From Multifuel CFB-Boilers: A Further Development of the Predictor

Present paper is a part of our on-going model development activities with aim to predict formation tendency of gaseous emissions from CFB combustion of different fuels, and especially, fuel-mixtures in real furnaces of various scale. The model is based on detailed description of homogeneous, catalytic, and heterogeneous chemical kinetics, and a sound but simple 1.5D representation of fluid dynamics. Temperature distribution is assumed known. With the tool, different fuels and fuel mixtures can be compared in respect to their tendency to form nitrogen oxides (NOx , N2 O). In this paper the model was tested to predict nitrogen oxide emissions from mono- or co-combustion of coal, wood, and sludge. The plants simulated were the 12MWth CFB combustor located at Chalmers Technical University (A = 2.25m2 , h = 13.6m) and the pilot scale CFB unit at the Technical University Hamburg-Harburg (d = 0.1m, h = 15m). The results gave reasonable representation of the measured emission data, and reflected correctly to the changes in the fuel characteristics and in the furnace operating conditions in most cases. An extensive laboratory fixed-bed reactor study was also performed in order to obtain input values for the kinetic constants of the catalytic reactions for the reduction and decomposition of nitrogen oxides. In literature, there is a limited data available regarding the catalytic activity of CFB solids during combustion of wood- and waste-derived fuels, especially at co-firing conditions. The kinetics for the NO reduction by CO in the temperature range of 780–910°C was determined to be of the following form (NO = 300ppm, CO = 5000ppm): −rNO = k·[NO]0.48·[CO]0.55 mol/g-s with k = 8.15·exp(−8869/T) m3/kg-s (empty reactor effect included) ork = 830·exp(−14930/T) (empty reactor effect excluded), when using a bed sample (250–355 μm) taken from the transport zone in the CTH boiler while burning a mixture of wood pellets and a pre-dried municipal sewage sludge. The role of char particle size and shape as well as the incorporation of energy balance on the char reactivity and the formation of nitrogen oxides is further illustrated by single char particle oxidation simulations.Copyright