Modeling a Fluidized-Bed Reactor for the Catalytic Polymerization ff Ethylene: Particle Size Distribution Effects

Particle size distributions in the output stream of commercial, fluidized-bed reactors for ethylene polymerization are analyzed using a mathematical model. The impact on the overall reactor performance of the universe of sizes for the particles in the bed, with only a fraction of them being extracted in the product flow, is studied. For the output stream, product size distribution is modeled using both triangular and generalized gamma functions. Extraction system parameters are employed to model the particle quantity and sizes. The importance of the proper modeling of the extraction system is shown through the analysis of the effects several output schemes have on the particle size distribution inside the fluidized-bed. Some of the main reactor variables, such as yield and temperature, are studied for several distributions. Operating variables, such as catalyst feed rate, are varied according to the reactor capacity in a typical, 12 meter bed, 130,000 ton/year reactor. Predictions indicate higher output rates for higher catalyst loads, as expected. A shift towards smaller particle sizes in the product and in the bed is observed when increasing catalyst load. Bed fluidization and heat exchange conditions are shown as affected by size distributions. Results show that it is appropriate to include both product and bed particle diameter distribution when studying the reactor performance.Fil: Grosso, Walter. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Chiovetta, Mario Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Technology, structural change and BOP constrained growth: a structuralist toolbox

The Latin American Structuralism (LAS) is a significant part of the heterodox tradition in the theory of long run growth, with a focus on the problems of developing economies which started their industrialization process when other regions had already accumulated substantial technological capabilities. The emergence of a centre-periphery system posed specific problems to growth and distribution in laggard economies which LAS discusses in a systematic way. In this paper we presented a simple model which, firstly, captures key insights of the LAS school, such as the persistency of technological asymmetries and structural heterogeneity; secondly, it can be used to analyze the impacts of shocks and policies based on how they affect supply-side and demand side parameters of the model; thirdly, it links more closely (Post-) Keynesian macroeconomics based on the BOP constraint with the evolutionary microeconomics concerned with the dynamics of learning; lastly, it can be used as a toolbox and a teachable model in the analysis of the interactions between structural change, technological catching up and long run growth.

Technology, structural change and BOP constrained growth: A structuralist toolbox

The Latin American Structuralism (LAS) is a significant part of the heterodox tradition in the theory of long run growth, with a focus on the problems of developing economies which started their industrialization process when other regions had already accumulated substantial technological capabilities. The emergence of a centre-periphery system posed specific problems to growth and distribution in laggard economies which LAS discusses in a systematic way. In this paper we presented a simple model which,firstly, captures key insights of the LAS school, such as the persistency of technological asymmetries and structural heterogeneity; secondly, it can be used to analyze the impacts of shocks and policies based on how they affect supply-side and demand side parameters of the model; thirdly, it links more closely (Post-) Keynesian macroeconomics based on the BOP constraint with the evolutionary microeconomics concerned with the dynamics of learning; lastly, it can be used as a toolbox and a teachable model in the analysis of the interactions between structural change, technological catching up and long run growth.technology gap - structural change -- structuralist model

Endogenous Labor Market Insitutions in an Open Economy

The paper sets up a two-country asymmetric trade model with heterogeneous firms,search frictions and endogenous labor market institutions. Countries are linked by tradein goods and non-cooperatively set unemployment benefits to maximize national welfare.We show that more open and smaller economies have more generous unemploymentbenefit replacement rates as a larger fraction of the costs is borne by foreign tradingpartners. These results are in line with empirical stylized facts. Additionally, we findthat the optimal level of unemployment benefits is independent from the level of unemploymentbenefits abroad and that non-cooperatively set unemployment rates areinefficiently high.Endogenous labor market institutions, unemployment, international trade, search frictions, heterogeneous firms

Unemployment in an interdependent world

We introduce search and matching unemployment into a model of trade with differentiated goods and heterogeneous firms. Countries may differ with respect to size, geographical location, and labor market institutions. Contrary to the literature, our single-sector perspective pays special attention to the role of income effects and shows that bad institutions in one country worsen labor market outcomes not only in that country but also in its trading partners. This spill-over effect is conditioned by trade costs and country size: smaller and/or more centrally located nations suffer less from inefficient policies at home and are more heavily affected from spill-overs abroad than larger and/or peripheral ones. We offer empirical evidence for a panel of 20 rich OECD countries. Carefully controlling for institutional features and for business cycle comovements between countries, we confirm our qualitative theoretical predictions. However, the magnitude of spill-over effects is larger in the data than in the theoretical model. We show that introducing real wage rigidity can remedy this problem. --Spill-over effects of labor market institutions,unemployment,international trade,search frictions,heterogeneous firms

Unemployment in an Interdependent World

We introduce search and matching unemployment into a model of trade with differentiated goods and heterogeneous firms. Countries may differ with respect to size, geographical location, and labor market institutions. Contrary to the literature, our single-sector perspective pays special attention to the role of income effects and shows that bad institutions in one country worsen labor market outcomes not only in that country but also in its trading partners. This spill-over effect is conditioned by trade costs and country size: smaller and/or more centrally located nations suffer less from inefficient policies at home and are more heavily affected from spill-overs abroad than larger and/or peripheral ones. We offer empirical evidence for a panel of 20 rich OECD countries. Carefully controlling for institutional features and for business cycle comovements between countries, we confirm our qualitative theoretical predictions. However, the magnitude of spill-over effects is larger in the data than in the theoretical model. We show that introducing real wage rigidity can remedy this problem.spill-over effects of labor market institutions, unemployment, international trade, search frictions, heterogeneous firms