Jacques Hermia

Catalytic incineration for odour abatement and VOC destruction

Foreword Catalytic oxidation is a well known process to destruct VOC emissions in air at low energy cost; it is useful when these contaminants are toxic and malodorous. But its use in coating industries is uncommon. The main reasons of this are the habits of the equipment manufactures, the very large variety of VOC to be destructed, the large range of their molecular weights and, in most cases, the eventual poisoning of catalysts. However the advantages are important : in our example, the pay-back time of the catalysts can be estimated to one year on the basis of energy savings, the range of VOC concentrations being 2-5 g/Nrn6. The lower temperature required improves the environmental impact because better efficiency of abatement, lower levels in NOx and CO2 emissions can be reached. Furthermore the small pressure drops make the process very attractive. Therefore the “Societe Belge de Filtration” began a study as part of an ECSC research programme on the feasibility of the catalytic incineration of the gas effluents from the coil-coating works. The research programme includes three steps. The first one is to assess the operating conditions for the most frequently encountered compounds in the gas. The compounds which will be considered below are aromatics, alcohols, ketones (and aldehydes, indirectly), acetates and alcanes. The influence of all parameters has been studied, i.e. temperature, space velocity, VOC concentration and nature. To help this study a simple modelling is developed. In this step the catalyst tested is a Pt/Pd Honeycomb monolithic converter. The purpose of the second step is to carry out continuous tests on a pilot scale reactor directly located in an industrial plant ; it includes the measure of the abatement in real industrial conditions, the assessment of the catalyst ageing and the identification of the possible poisoning. In consideration of this last eventuality the selected catalyst is a Pt Honeycomb monolithic converter. In the same time a last step is carried out in the UCL laboratory dealing with extending tests on simple VOC mixtures and comparative trials on metal oxide catalysts.

Comparison of precious metals and base metal oxides for catalytic deep oxidation of volatile organic compounds from coating plants: test results on an industrial pilot scale incinerator

For the coating application case, base metal oxides catalysts (Cu/Cr, Cu/W or Cu/Mn) are not more resistant to poisoning than PGM catalysts, the best results being obtained for a Pt/Pd (1:5) catalyst formulation. Furthermore, the cleaning of aged PGM catalyst is easy and efficient whereas their degree of compactiveness is very high.

Measurement of odor intensity by an electronic nose

ABSTRACT The possibility of using electronic noses (ENs) to measure odor intensity was investigated in this study. Two commercially available ENs, an Aromascan A32S with conducting polymer sensors and an Alpha M.O.S. Fox 3000 with metal oxide sensors, as well as an experimental EN made of Taguchi-type tin oxide sensors, were used in the experiments. Odor intensity measurement by sensory analysis and EN sensor response were obtained for samples of odorous compounds (n-butanol, CH3COCH3, and C2H5SH) and for binary mixtures of odorous compounds (n-butanol and CH3COCH3). Linear regression analysis and artificial neural networks (ANN) were used to establish a relationship between odor intensity and EN sensor responses. The results suggest that large differences in sensor response to samples of equivalent odor intensity exist and that sensitivity to odorous compounds varies according to the type of sensors. A linear relationship between odor intensity and averaged sensor response was found to be appropriate for the EN based on conducting polymer sensors with a correlation coefficient (r) of 0.94 between calculated and measured odor intensity. However, the linear regression approach was shown to be inadequate for both ENs, which included metal oxide-type sensors. Very strong correlation (r = 0.99) between measured odor intensity and calculated odor intensity using the ANN developed were obtained for both commercial ENs. A weaker correlation (r = 0.84) was found for the experimental instrument, suggesting an insufficient number of sensors and/or not enough diversity in sensor responses. The results demonstrated the ability of ENs to measure odor intensity associated with simple mixtures of odorous compounds and suggest that ANN are appropriate to model the relationship between odor intensity measurement and EN sensor response.

Using batches for modeling and optimizing the brewhouses of an industrial brewery

A detailed simulation model of the four brewhouses of an industrial brewery has been developed with the help of BATCHES, a software dedicated to the simulation of batch and semi-continuous processes. The use of this model has allowed a thorough study of the utilization rates of the pieces of equipment of the brewhouses as well as an analysis of the energy consumption profiles. Taking into account that the utilization rates are generally quite low and that some pieces of equipment are largely oversized, two new configurations for the brewhouses have been proposed, reducing by up to one third the number of pieces of equipment. On the side of the energy study, the combination of the proposed modifications of the process, namely a better standardization of the brewing plant, an adequate production planning and a voluntary limitation of the steam availability level, permits a considerable reduction of the peak energy demands. From the most unfavourable to the most favourable situation encountered during this simulation study, the global reduction amounts to 46%.

Peak utility load reduction in batch processes operated periodically and under uncertainty

A methodology has been developed in order to achieve peak utility load reduction in batch processes operated periodically and under uncertainty. Based on a combination of computer simulation and an analytically based approach, the former with the help of the BATCHES simulator, this methodology has been applied while following the general objective of modelling and optimizing the brewhouses of an industrial brewery. The steam consumption profiles in these brewhouses exhibit a very irregular behaviour with some demand peaks of very short duration which greatly exceed the average demand. The use of the presented methodology has enabled us to suggest a series of measures resulting in a considerable reduction of the steam consumption peaks. These measures are: a better standardization of the equipment, the choice of an optimized production schedule and the acceptance of a voluntary limitation of the steam availability level. From the most unfavourable situation to the most favourable encountered in our study, the global reduction amounts to 55%.

Complementarity of simulation and analytical methodologies—A design application

The complementarity of simulation and analytical methodologies is illustrated by a study following the general objective of modelling and optimizing the brewhouses of an industrial brewery. During this study, an extensive simulation model of the brewhouses of an industrial Belgian brewery has been developed within the framework of the simulation package BATCHES. The use of this simulation model has been complemented by the use of a simple analytical method in order to achieve a quick and efficient design of a new optimized configuration for the brewhouses, representing a notable reduction of the number of equipment items. A series of simulation runs have finally been used to refine this alternative configuration and prove its operability. While such a dual methodology is shown to be easily implemented and used, an economic study has shown that the unit price of production capacity of the brewhouses can consequently be reduced by about 30% in comparison to the base case.

Comparison of Modern Beer Filters

Beer filtration is currently performed using candle filters and horizontal leaf filters. The comparison between these two technologies shows that the candle filter allows smaller pressure rises, but the horizontal leaf filter offers a larger filtration area in a given tank volume. The candle filter comes out as more efficient when narrow candles are used.

Designing a new wort filter underlying theoretical principles

Abstract Systematic use of the theoretical principles governing cake filtration, washing and dewatering by mechanical expression has led to the development of a new wort filter. Though involving thin cakes, it nevertheless produces clear worts and has been optimised to maximise productivity. A prototype installed in a Belgian brewery gives over 12 brews/day, and produces cake (spent grains) with 35% dry solids.