Managing Trace Contaminants in Cryogenic Air Separation

ABSTRACT Atmospheric air contains many trace components which are process contaminants or equipment fouling agents in a cryogenic air separation process unit (ASU). Based on the potential problems that they may cause, the trace contaminants are categorized as corrosive, plugging or reactive species. This paper discusses a three step process to manage the trace contaminants as they move through the ASU: identify the hazard, abate the hazard and verify the abatement. Guidelines that contribute to safe and efficient operation of ASU's are presented and summarized. Focus is placed on the reboiler sump, where high boiling components concentrate in high purity oxygen. The special needs of oxygen vaporizers, where the oxygen is boiled to dryness, are also discussed. Nitrous oxide (N 2 O) is one of the trace contaminants present in the air and it has received special attention in the past few years. It has a low solubility at cryogenic temperatures, and can be present in sufficient quantities to plug equipment. Various methods used to abate N 2 O accumulation are discussed, including a novel adsorbent, together with relevant plant operating data

Pós-operatório de homoimplante de costela avaliado por toracoscopia paraxifóide transdiafragmática modificada em gatos Post-operative of toracoscopy paraxiphoid transdiaphragmatic modificed approach, in cats

O objetivo deste estudo foi de avaliar a exeqüibilidade do acesso paraxifóide transdiafragmático modificado, em gatos, no período pós-operatório de homoimplante de costela para reconstituição de parede torácica. Para tanto foram avaliados 16 gatos após a reconstituição de parede torácica com o uso de homoimplante de costela conservado em açúcar. A cavidade torácica dos animais foi acessada por via transdiafragmática modificada, por meio de uma incisão de 2cm na linha mediana paraxifóide para posterior introdução da cânula ao diafragma utilizando uma óptica de 10mm de diâmetro. Foi identificado o terço médio da parede torácica, sendo necessário que os animais fossem posicionados em decúbito lateral obliquado. Foram constatadas aderências e visibilizado o aspecto dos implantes. Foi possível avaliar a parede torácica de gatos com óptica de 10mm de diâmetro através do acesso transdiafragmático modificado.<br>The purpose of this study was to evaluate a modified thoracic access to test the rib homoimplant in cats. Sisteen adults cats was evaluated ofter thoracic wall reconstituition using a rib homoimplant preserved in sugar. The animals were submitted to a modified trans-diaphragmatic paraxiphoid access, using a optical of 10mm diameter through the midline. The lateral oblique recumbency made become possible the identification of the medial third of the thorax, and it also allowed the identification the adhesions and the aspect of the implants. The evaluation thoracic cavity of the cats with an optic of 10mm of diameter through the modified trans-diaphragmatic paraxiphoid access