Flow distribution and jet behavior analysis of fabric filter's pulse-jet cleaning.

Particulate Matter (PM) pollution is an alarming environmental problem and one of the most used PM control devices in industry is fabric filter, with a pulse-jet cleaning system. A better understanding of the flow behavior of such pulse-jets is essential to improve cleaning efficiency and diminish dust emissions. Therefore, the present study aims to analyze the flow patterns of the cleaning pulse of an industrial-scale bag filter, with high-pressure and low-pressure systems, using transient three-dimensional CFD simulations. The results show that the center bags in a row take slightly higher shares of air volume and the larger part of it is due to secondary flow. The simulations also give insights into the degree of centralization of the jets: misalignment is progressively reduced along the purge tube, being less pronounced in the high-pressure than in the low-pressure system. Although the mass flow is higher in the high-pressure system, the distribution of the flow among the bags is relatively uniform and similar for both systems.Implications: This work shows, through simulations, that the behaviour of the air pulse during the cleaning is not uniform. There is a variation of the pulse along the duct, due to the movement of the wave that is formed. Besides wave intensity and pressure, the position and shape of the cleaning nozzle also affects the air pulse.

The challenges for solid waste management in accordance with Agenda 21: a Brazilian case review.

This paper aims to evaluate the suitability of the Brazilian solid waste policy (BSWP) with global Agenda 21 and the challenges of implementing the BSWP in municipalities. For this, a review of the principles that guided the creation of this policy was performed to demonstrate that international pressures were important in determining its effectiveness. The contradictory relationship between the satisfactory legal framework that established the Brazilian waste management policy and its weakened implementation in the municipalities is also examined . To illustrate the difficulties faced at the local level, a case study involving municipalities that compose the state of Espírito Santowe was undertaken. In this state, the municipalities signed terms of environmental commitment with supervisory agencies who undertook, within a pre-established schedule, to implement a set of actions to shape the proper management of solid waste, adapted to the requirements of national policy and the guidelines of Agenda 21. Finally, the various difficulties in meeting the requirements are discussed. It is necessary and urgent that Brazil finds a way to coordinate the mechanisms of an innovative and well formulated legal instrument to ensure the successful implementation of solid waste management at the local level to achieve the environmental, economic and social objectives.