Air, dew point

Inlet air dew point Nozzle spray cone angle... 

Irrespective of the method used to produce the granules and the consequent batch size, a signiflcant factor in scale-up is the increase in drying capacity in larger equipment. The heat delivered to the bed of fluidizing granules comes from a combination of inlet air temperature and volume, and, to a lesser extent, inlet air dew point. As previously mentioned, the process air volume is also responsible for fluidization behavior, and this will be the first variable to be considered. 

Scale-Up Considerations Drying-Process Air Dew Point and Dry Bulb Temperature... 

Prior to a discussion on the impact of processing air dew point and temperature on the drying rate behavior of a product, it is necessary to consider heat and mass transfer. Water will move from the granule to air in an attempt to reach an equilibrium, or saturated condition, determined by thermodynamics, which can be read from a phase diagram or psychrometric chart. The rate at which water will move from liquid in the granule to vapor in the air increases the further away the system is from equilibrium. When the water evaporates, it requires an amount of energy, the heat of vaporization, in order to change from liquid to vapor. Because of this, we must also consider transfer of heat as well as movement of material. These concepts can be described by equations shown in Table 5. 

Ideally, all sizes of the fluid bed equipment should be equipped with inlet air dew point control. In the northern climates, this would include dehumidification in the summer months and humidification during the cold, dry winter months. In this manner, the inlet air dew point becomes a recipe... 

Jones DM. Effect of process air dew point on a top-spray fluidized bed-coating process. Presented in Session 265 Coating in the pharmaceutical industry. Proceedings of AIChE Annual Meeting, 1998. 

Nearly all types of coating processes will benefit from a consistent process air dew point. Humidity control systems may be complex, incorporating dehumidifiers (for dew point reduction to about 5-iO C). desiccant dryers (for products requiring low product temperatures and dew points below 0 C), steam humidifiers (to increase dew point in cold, dry weather), etc. It is suggested that laboratory trials be conducted to evaluate product and process sensitivity to variations in inlet air dew point. 

Drying is recommended for PSF/PET MindeF B) blends. Dehumidified hopper drier or circulating air oven with air dew point of -29°C, are preferred. 

Ultra-thin epoxy films with thickness d p of 60, 125, 250, and 650 nm were spin-coated in C02-reduced, dried air (dew point -70 °G) from the appropriately diluted prepolymer solution in methyl ethyl ketone (MEK). After film preparation, the specimens were stored in the same atmosphere at about 23 °C for 72 h. This room temperature (RT) curing was followed by a post-curing" step at 120 °C in argon for 1 h. 

Moist room air leaking into dry-process air Dew point meter incorrect... 

The whole dryer section is enclosed in a drying hood with doors which can be opened e. g. for inspection. It allows controlled flow of the hot and dry make-up air as well as of the vapor laden exhaust air. The pressure inside the hood should be balanced in such a way that a minimum of air is blown from the hood into the machine hall or sucked from the machine hall into the hood. For effective pocket ventilation the hot air enters via blow boxes or blow rolls and flows to both sides of the machine where it is sucked off To prevent condensation the hood walls are insulated and make up air is supplied along both hood sides from underneath. These measures allow a low amount of make-up air, a high air dew point of the exhaust air and effective heat recovery. 

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