DESIGN DATA
The proposed system
would be designed to produce 700 kg/hr of Acid Casein at 10% moisture content,
when fed with wet casein containing up to 55% moisture content.
This duty corresponds
to an evaporation capacity of 700 kg/h, based upon 180°C inlet
temperature and 70°C
outlet temperature.
The cooler would be
designed to cool the product to approximately 40°C.
Wet Feed
Rate kg/h 1400
Initial
Moisture Content % 55
Dry
Product Rate kg/h 700
Final
Moisture Content % 10
Evaporation
Rate kg/h 700
Wet Feed
Temperature °C 35
Hot Air
Inlet Temperature after Heater °C 180
Gas
Exhaust Temperature °C 70
Final
Product Temperature (after cooling) °C 40
Material
Properties
Material
Specific Heat (assumed) 0.4 kcal/kgoC @ 30OC
Bulk
Density – wet material (assumed) 600
kg/m3
Bulk
Density – dry powder (assumed) 700
kg/m3
UTILITY CONSUMPTION
The
following utilities are estimated utility consumptions:
Description
Condition
Design Consumption
Steam 15
barg saturated.
Condensatereturn
@ 90°C, ambient pressure.
Main
Heater
1220
kg/h
Chilled
Water @ 3.5°C
returning
at 8°C based on
ambient
temperature of 40°C and 70%RH
Chiller 22
m³/h
Compressed
Air Instruments – Particles <0.1
micron,
dewpoint -40°C, oil content
<0.01mg/nm³
Instruments 10
Nm³/h
Electrical
Power 400V,
3pH, 50Hz 140 kWh
3.0 MOTORS
& GEARED MOTORS
The
following motors will be required for operation of the plant.
Motors
below 450 kW should be suitable for 400V, 3-phase, 50 Hz.
Motors
over 30 kW should be fitted with thermistors
Plant Item
Installed Power
(kW)
Disintegrator
110.0
Dryer
Cyclone Rotary Valve
0.55
Induced
Draught Fan 90.0
Vibrating
Fluidised Bed 1.8
Discharge
Rotary Valve 0.55
Cooler
Cyclone Rotary Valve 0.55
Cooler FD
Fan 3.0
Cooler ID
Fan 4.0
Total Motor Power 210.45
DESCRIPTION OF
OPERATION
The proposed system
would feature a special Ring dryer with hot disintegrator for product milling,
and multi-stage centrifugal classifier to provide selective recirculation of
semi-dry material. Circulating drying air would be heated by means of indirect
heat exchange with saturated steam and dry product would be collected by a high
efficiency cyclone. Wet feed would be transferred from the decanter to the
dryer by forced draught pneumatic conveyor. The disintegrator would break-up
agglomerates, increasing surface area to ensure rapid heat and mass transfer,
and efficient drying. The material would dry during transport through the Ring
duct to the manifold by the hot drying air. The manifold would act as a
centrifugal classifier, selectively returning larger partially dry and heavier
particles to the Ring duct and disintegrator for further drying and/or size
reduction, whilst
allowing fine dry
product to leave the system with the spent drying air. Dry material would be
separated from the dryer exhaust in a high efficiency cyclone, discharging
via a rotary valve to
the cooler. Filtered process air would be raised to the required inlet
temperature by means of indirect heat exchange with 15 bar g steam. Drying air
would be drawn through the complete system by a single induced draught fan.
Material discharged
from the dryer would be fed via an angled chute into a vibrating fluidised bed cooler.
Dry product would cool whilst being fluidised by means of a through flow of
ambient air. The vibratory action of the unit would assist with the
fluidisation and transport of material along the bed. Filtered, chilled,
process air would be supplied to, and cooler exhaust withdrawn from the bed by
a balanced system of forced and induced draught fans. Entrained fines would be
separated from the spent cooling air by a high efficiency cyclone and
discharged via a rotary valve.
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