Exhaust off-take

Various furnace movements must be accommodated by the enclosure. Operations such as furnace tilting for tapping and slagging, electrode vertical lift, and direction of furnace roof swing must be coordinated with respect to enclosure shape and the location of the exhaust off-take. 

The enclosure is also capable of storing fume surges during bucket charging. With proper design, the top of the enclosure will fill with fume while the lower working level remains clear. The key to producing this effect is to reduce fume recirculation in the enclosure by proper placement of the air curtain with respect to the exhaust off-take. 

Air Curtain and Exhaust Off-Take Air curtain design and exhaust offtake location are very important considerations. The air curtain is applied on roof openings that are typically 2 to 3 m wide and used for crane rope access. The opening may extend over the length of the enclosure and should, therefore, be served by two sets of independently operated doors— one for tapping and one for charging. This feature minimizes the pen area when one of the two events occurs. 

The optimum position for the exhaust off-take is directly opposite the air curtain discharge. Rising fume with the highest concentration is directed straight into the off-take without excessive recirculation in the enclosure. 

During melting, the air curtain should efficiently direct fume towards the exhaust off-take without allowing recirculation within the enclosure. The air curtain design should therefore also consider the fume trajectory when a lower updraft velocity from melting is experienced. 

The factors affecting the performance of a local exhaust system are well known. For fume control, an added factor is the effect of heat release or buoyancy. Important design parameters are process heat release and the size and geometry of air-supply openings and their location relative to major surfaces of the enclosure, lire kxation of the fume off-take is usually only of secondary importance. 

Inhalation headache, tiredness, sweating, feeling of weakness, muscle cramps, raised temperature. sealed machinery, local exhaust or respiratory protection. fresh air. rest, place in half sitting position, allow to cool off. take to hospital. 

Receptor hoods, also called canopy hoods, are designed to capture contaminants given off by heated processes. They take advantage of the thermal updraft caused by such processes by placing the hood in the path of the updraft, they receive the exhaust and capture the contaminants. 

Figure 4.2 Steve Bechler, a former pitcher for the Baltimore Orioles, died after taking a weight loss supplement containing ephedra. Here he is being taken off the playing field during training camp, when he began to suffer from heat exhaustion, a side effect of ephedra-based drugs.

The finer particles of the solid dissolve first as the solution becomes more concentrated the rate of solution grows slower, and it takes a very long time to dissolve the remaining coarser particles. Hence when a limited amount of solvent or reagent is used, as for example when copper is to be dissolved in a minimum amount of nitric acid, it is best to hold in reserve perhaps one-tenth of the reagent when the nine-tenths are almost exhausted and the reaction with the coarser particles has almost stopped, pour off the solution already obtained, and treat the small residue with the fresh acid held in reserve. 

The effect of the metal oxidation state on the emission intensity has been also investigated by performing controlled potential exhaustive electrolysis experiments. When an MeCN, poorly emissive solution of the Cu complex is reduced cathodi-cally to the corresponding colorless Cu species, a strong fluorescence enhancement is observed. As the redox process is fully reversible, fluorescence can be switched on/off at will, by setting the potential of the working electrode at the proper potentials for Cu -to-Cu (on) and Cu -to-Cu (off ) changes to take place. 

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