Designing of the dryer section of nutritional yeast production plant – Industrial sector review – Part 15

Designing of the dryer section of nutritional yeast production plant – Industrial sector review – Part 15

For the cycle of the air, please see attached Psychometric charts

• Saturated Wet bulb temperature of the Air = 55 °C (after heating to 300 °C)
• Drying Air Mass flow rate = 20,685 kg/hr
• Drying Air Volumetric Flow rate = 18, 190 m³/hr
• Density (@105 °C) = 1.13 kg/m³
• heat capacity = 0.24 kcal/kg

1.1.           Data of Cream

• Moisture = 1587.3 kg/hr
• Solid Content = 348.53
• (Cream contains 18% solids, of total feed of 1935.83 kg/hr)
• Optimum moisture content in product = 8%
• Density = 1013.53 kg/m³
• Feed rate = 1.91 m3/hr
• Viscosity  = 1.8 cP

1.2.           Data of Dried Yeast

• Density yeast = 1030 kg/m³
• Thermal conductivity = 0.0256 kcal/m2 h °C
• heat capacity (@ 15 °C) = 1.016 kcal/kg
• Particle size = 30–70 micro meters

1.3.           Data of Water

• Heat capacity of water vapour(@ room temperature)= 0.46 kcal/kg
• Heat vaporisation = 570 kcal/kg
• Heat capacity of water = 1 kcal/kg
• Density of water = 1000 kg/m³

1.4.           Assumptions

No accumulation mass occurs during the whole processing of dyer, i.e. total mass water and product going into the dryer = total mass of water and product coming out

The heat capacity of water vapour, air and yeast do not change with temperature

All droplets are of equal size such that heat and mass transfer rates and drying times are the same for all droplets in the spray dryer

Ideal mixing takes place between the cream droplets and air.

The entire product reaches desire moisture content in negligible time.

Heat transfer between droplet and air is by forced convection

Droplets constituting the spray are spherical

Spray is homogeneous

The chance of coalescence and breakup of the droplets during the trajectory is disregarded

The air proceeds through the dryer as a perfect cyclone

Continued in part 16

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Posted by Ahmed Tariq on Feb 29 2012. Filed under Sci-Tech. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry