National Cranberry

Topics: 5th millennium, Chemical engineering, Separation processes Pages: 4 (809 words) Published: November 6, 2008
2. Throughput is defined as

Throughput=Min {Input rate, Process capacity, Demand rate}
Input Rate = 3000 bbls/hr
Input Rate and Demand Rate > Process Capacity
Throughput =Min {Process Capacity}

It is evident from the process flowchart that the capacity of the drying unit is minimum at 450 and maximum at 600 bbls/hr. However, this does not apply to dry berries.

Both dry and wet berries go through the separation process with a capacity of 1200 bbls/hr. Since 70% of the berries are wet, the capacity for separation is recalculated as

Separation capacity for wet berries = 70% of 1200 bbls/hr = 840 bbls/hr Separation capacity for dry berries = 30% of 1200 bbls/hr = 360 bbls/hr

Since the output from the dryer unit for wet berries can only be a maximum of 600 bbls/hr, we can allocate the additional separation capacity for wet berries to dry berries.

Additional separation capacity = 840-600= 240 bbls/hr

New separation capacity for wet berries = 840 – 240 = 600 bbls/hr New separation capacity for dry berries = 360 + 240 = 600 bbls/hr

Maximum long term achievable throughput rate = Min {Drying, Separating}
= 600 bbls/hr

The current unloading time for a truck with average 75 bbl is 5-10 minutes. Assuming the average unloading time is 7.5 minutes,
The process capacity of one truck = 75*(60/7.5) = 600 bbls/hr This gives the capacity of 5 Kiwanee dumpers at 3000 bbls/hr. 70% of berries are wet; arrival rate for wet berries is 2100 bbls/hr However, the capacity for drying is only 600 bbls/hr

This leads to a backlog of wet berries which do not move forward until the next batch is dried. For dry berries also, there is a bottleneck of separation at 600 bbls /hr and arrival rate of dry berries is 30% of 3000 = 900 bbls/hr. Total backlog berries capacity = Backlog Capacity for Wet + Backlog Capacity for Dry

= (2100-600) + (900-600) = 1800 bbls/hr
This causes the trucks to wait to unload their berries until the dumpers become...
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