The paper presents results of a qualitative assessment of the morbidity and mortality in thyroid cancers by the Belarusian population caused by the Chernobyl accident. In the period of 1986-1998 about 3,851 radiation-induced thyroid cancers appeared in Belarus: about 615 cancers by children and about 3,236 cancers by adolescents and adults. The number of lethal thyroid cancers in this period of time in Belarus is assessed as about 167 cases. The excessive absolute risk (EAR) of the morbidity in the thyroid cancer assessed for the period of 1986-1998 on the basis of given data on the morbidity is about 1.7 per 10 4 PYGy. The excessive absolute risk of mortality is assessed as about 0.075 per 10 4 PYGy. These values agree quite well with analogous risk coefficients established for other groups of people in other epidemiological studies.The research register for this journal is available atThe "Environmental Management and Health" (EMH) Internet Research Register reports on current research worldwide, including studies completed during the past six to nine months. Research may be linked to an academic course of study or project, be independent, or organisation-based. Both industry and the academic world are represented, as well as the government and NGO sectors. The register aims to be comprehensive in its geographic and Sponsors

The paper discusses the results of a kinetic study of the pyrolysis of woody biomass (ordinary oak wood – Quercus robur) under static conditions at temperatures of 673, 773 and 873 K. In experiments, biomass samples weighing about 1.4 g were kept in a heating furnace for a certain period, after which their residual weight was measured and the degree of decomposition achieved was determined. A total of 7 series of experiments were performed: two series each at temperatures of 673 and 873 K and three series at a temperature of 773 K. The obtained results were analyzed in the framework of a single-stage chemical reaction (one-step global model), leading to a loss of the initial mass. It was established that from the phenomenological point of view, the pyrolysis of woody biomass under experimental conditions corresponds to the sigmoidal reaction model by Avarami–Erofeev with an exponent n ranging from 0.508 to 0.985. The use of the results of the first series of experiments led to an activation energy value of 57.2 kJ/mol and a pre-exponential factor value of 38 s–1. The other series of experiments gave an activation energy value of 64.9 kJ/mol and a preexponential factor value of 130 s–1. It is shown that the use of these values of the activation energy and the preexponential factor leads to agreement of the calculated values of the degree of decomposition of the studied biomass samples with the experimental ones in the range of values of the degree of decomposition from 0 to 1. The data presented in this work contribute to a more complete understanding of the kinetics of pyrolysis of biomass, which is necessary for the development of effective equipment for the thermochemical processing of vegetable raw materials.

The objective of the study is to examine the Coats-Redfern approximation and to propose an innovative kinetic calculation method for the complex process of the heavy tar thermal decomposition under non-isothermal process. The thermal decomposition process was examined using the thermogravimetric analysis. There are several kinetic models proposed to analyze pyrolysis mechanism in terms of the formal reaction. In this manner, the kinetic parameters of the pyrolysis process can be evaluated based on total mass loss (thermogravimetric analysis –TGA). The TGA procedures can be conducted with isothermal or non-isothermal conditions, but the experimental data obtained according to this procedure have to be transformed into appropriate correlation. The obtained results have shown that the reaction takes place within temperature range of 540 K to 700 K and the inductive period of the process is about 224 min. Kinetic parameters were estimated with using of the conventional Coats-Redfern method. A new kinetic calculation method has been designed to provide a less laboriousness of identifications procedures compared with Coats-Redfern approximation and to take into account an induction time of the process. As the outcome of this study, it was shown that the kinetic parameters estimated with using of the proposed model-fitted method gives the more appropriate correlation in comparison with the conventional Coats-Redfern method. The proposed method uses the Coats-Redfern algorithm for evaluation of the reaction mechanism, but the value of the constant rate is defined directly from experimental data on the conversion rate.

ВЛИЯНИЕ ДАВЛЕНИЯ ГАЗОВОЙ СРЕДЫ НА ОБРАЗОВАНИЕ ДРЕВЕСНОГО УГЛЯ В ПРОЦЕССЕ ПИРОЛИЗА РАСТИТЕЛЬНОЙ БИОМАССЫ Аннотация. Приводятся результаты экспериментального исследования влияния давления на образование древесного угля в процессе пиролиза древесины, осуществленного на лабораторном стенде при давлениях 1, 3, 5, 7 атм и температуре 400 °С. В качестве исходного сырья использована березовая древесина в виде щепы размером частиц 17 ç 8 ç 6 мм. Влажность сырья составляла 14,2 мас.%, плотность-506,4 кг/м 3 , зольность-0,23 мас.%. Установлено, что повышение давления от 1 до 7 атм приводит к увеличению выхода древесного угля от ~ 25 мас.% до ~ 32 мас.%. Содержание углерода при этом возрастает от 89,1 до 96,4 мас.%. Также экспериментально исследовано влияние искусственного ухудшения условий выхода летучих компонентов парогазовой смеси из реакционной зоны на образование древесного угля и содержание углерода. Полученные данные позволяют предположить, что ухудшение условия выхода из реакционной зоны летучих компонентов приводит к их разложению с образованием углерода, отлагающегося в порах пиролизуемого материала и на его внешней поверхности. Представлены экспериментальные данные, свидетельствующие о том, что компоненты пиролизной смолы разлагаются в присутствии древесного угля с отложением образующегося углерода на его поверхности. На протекание этого процесса указывает различие в массах одинаковых образцов древесного угля, выдерживаемых при температуре 600 °С при отсутствии и наличии пиролизной смолы: конечная масса образца, выдерживаемого в присутствии пиролизной смолы, превышает массу образца, выдерживаемого при ее отсутствии. Эти результаты дают косвенное доказательство правильности предположения о разложении компонентов пиролизной смолы в порах и на поверхности пиролизуемого материала при задержке выхода продуктов пиролиза из реакционной зоны. Результаты настоящего исследования представляют интерес для специалистов, разрабатывающих пиролизное оборудование. Ключевые слова: пиролиз, давление, древесный уголь, содержание углерода, вторичные процессы Для цитирования: Влияние давления газовой среды на образование древесного угля в процессе пиролиза растительной биомассы / С. В. Василевич [и др.] // Вес. Нац. акад. навук Беларусі.

The article features an experimental study of thermally thin biomass samples (beech wood particles 17×8×6 mm) pyrolysis in a laboratory scale batch reactor. The reactor was a cylindrical steel body with internal diameter of 200 mm and height of 500 mm. The temperature of a lateral surface of the cylinder during the experiment was being kept constant (550 °C) due to electrical heating. The initial loading of the apparatus was about 4 kg with moisture content of about 14 % by weight. During the experiment, the temperature values of the material being pyrolyzed were recorded at two points of the radial coordinate, viz. at the wall of the apparatus and on its axis. A one-dimensional numerical model of the nonstationary process of biomass conversion (heat and mass transfer in combination with the Avrami – Erofeev reaction model) has been proposed and verified. The reactor is represented as a set of a countable number of cylindrical layers, considered as cells (representative meso-volumes) with an ideal mixing of the properties inside. The cylindrical surfaces that form cells are considered to be isothermal. The size of the cells is chosen to be sufficiently large in comparison with the individual particles of the layer, which makes it possible to consider the temperature field inside the cell volume as monotonic. The evolution of the temperature distribution over the radius of a cylindrical reactor is determined on the basis of a difference approximation of the process of non-stationary thermal conductivity. The calculated forecasts and experimental data showed a good agreement, which indicates the adequacy of the developed mathematical model of pyrolysis and makes it possible to recommend it for engineering calculations of biomass pyrolysis. This model can also be useful in improving the understanding of the basic physical and chemical processes occurring in the conditions of biomass pyrolysis.