Drying pressure operation

Acid circulated over SO absorbing towers is maintained at about 98.5% to minimize its vapor pressure. Where lower concentration product acid is desired, it is made either in separate dilution faciUties, or in drying towers operated at 93—96% H2SO4. 

Solids size, fine Solids size, >150 /zm Compressible cakes Open cakes Dry cake required High filtrate clarity Crystal breakage problems Pressure operation High-temperature operation... 

Composite particles for controlled release of pharmaceutical compounds have been generated by the PGSS process. An example is the formation of 2-3 pm theophylline/hydrogenated palm oil (HPO) particles. The process produced fine and dry powders operating at 60°C and at pressures between 120 and 180 bar. The morphology of the particulates varied with the... 

To overcome this problem, a submerged condensate pot is often installed instead of the steam trap (Fig. 17.le) as described earlier (item 5 above). An alternative remedy is replacing the steam trap by a level condensate pot (Fig. 17.1/). By varying the level control set point, the surface in the reboiler can be adjusted so that the reboiler operates at a pressure high enough to ensure condensate removal at all times without a pump. Note that the bottom of this drum is located below the bottom of the condensing side of the reboiler (189) otherwise, "dry reboiler operation at high rates will not be possible, and reboiler capacity will be reduced. 

Among all solvent-replacement supercritical drying methods, organic solvent-replacement supercritical drying has limitations of poor safety due to its high temperature and pressure operation in addition its equipment and operation costs are high. As for liquid carbon dioxide-replacement supercritical... 

MEG and some of its analogues are used for drying natural gas to prevent the formation of methane hydrate. MEG picks up water from the gas and is recycled through a simple continuous still of a few trays in which the MEG is dried. This operation can enable the desiccant to be used many times but it eventually is so contaminated by inorganic salt (mostly NaCl) that it must be evaporated. This can be done in a wiped surface evaporator under vacuum but this involves fairly expensive equipment and it can be done in a thick wall mild steel pot with an anchor stirrer provided high enough steam pressure or hot oil temperature is available. 

The amount of high-pressiue steam required for recovery of dry DMF is about 40%, and the low-pressiue steam is about 68% of that needed for single-column, atmospheric pressure operation. 

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