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Process Scheduling, Resource & Inventory
Tracking
Course OutlineCourse Outline
Process scheduling Specifying process scheduling Viewing scheduling & related results Resource tracking Inventory tracking
Process scheduling toolsProcess scheduling tools
Operating Gantt Chart Equipment Occupancy Chart
Recipe Scheduling Information
Purpose of schedulingPurpose of scheduling Based on the scheduling information & annual
operating system time (AOT) specified for the plant, the system will:
Make sure there is no conflict between start time & end time of processing steps
Make sure there is no conflict between the specification of annual operation time, the number of batches, plant cycle time.
Calculate the following: Plant’s batch time The maximum number of batches possible Longest procedure & scheduling bottlenecking
problem
Scheduling function in SPDScheduling function in SPD
For each operation:
i. The process time
ii. The setup and turnaround time
iii. The starting time
iv. The number of cycles (at procedure level)
For entire plant:
i. The AOT
ii. The number of campaigns per year , and either:
a. The number of batches per year, or
b. The batch cycle time, or
c. The batch time slack
Important scheduling definitionsImportant scheduling definitions Setup Time (St): Duration spent for preparation before the actual execution
of an operation May involve cleaning, vacuuming, setting up of equipment Process Time (PT): duration that an equipment is in use to
carry out an operation. Turnaround Time (TT): duration that an equipment is being
prepared for the next cycle Operation Cycle Time (OCT): Amount of time for an operation’s cycle to be OCT=ST+PT+TT Procedure Cycle Time (PTT): duration spent to complete an
entire procedure, including all operations in the procedure Batch Time (BT): duration from 1st operation till the end of
the last operation in a single batch
Operation Gantt chartOperation Gantt chart
PCT for P-1 =10.52 hr
OCT for FILTER-1 in P-2 = 4 hr
Batch time = 11.49 hr
Equipment Occupancy ChartEquipment Occupancy Chart
Procedure cycle time
Turnaround time
Batch time
Recipe Scheduling InformationRecipe Scheduling Information
Path: Task/Recipe Scheduling Information
Make this following changes:
Set number of batches per year: 20 (assuming that the equipment used by this process is used by other processes)
Set Recipe Cycle Time:12 hr Press “Update” Note the different changes
before and after changes
Changes in schedulingChanges in scheduling
Variables Original After recipe change
Batch time
Min cycle time
Number of batches
Batch cycle time
Time slack
Resources & inventory trackingResources & inventory tracking
Resources (ingredient, heat transfer agent, power, labor)
Inventory ( ingredient, heat transfer agent)
Resource tracking (Operator)Resource tracking (Operator)
Path; View/ Resource Consumption Tracking Chart/ Labor/ Multiple Batches…Operator
Set to display for 4 batches & fit to window
2 operators are needed in total
Inventory trackingInventory tracking SPD can only analyses & displays inventory Given the following info: 40 kg of material ‘B’ are used in each batch Suppose there is a 200 kg storage capacity for ‘B’
with an opening inventory of 100 kg Loading rate of ‘B’ into storage: 200 kg/hr Task: determine how often should shipments of
‘B’ be scheduled?
Inventory trackingInventory tracking Path: View/ Resource Inventory Chart/
Ingredient (Multiple Batches) Select ‘B’ and select the Supply Info button.
Fill out the dialog as shown in figure below: Storage capacity: 200 kg Initial content: 100 kg Supply mass flow: 200 kg/h Schedule variable-10% (On-Trigger); 90% (Off-Trigger) On-trigger & Off-Trigger settings: the supply of
‘B’ should be replenished when the inventory falls to 10% of the capacity; and halted when the inventory reaches 90% of storage capacity
Inventory trackingInventory tracking Click OK to continue & the chart will be
displayed with 2 batches. Set the number of batches to 12 by right clicking and selecting Set Number of Batches
1
2
3
4
5
6
7
8
9
10
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12 90% of inventory =
180 kg
10% of inventory =
20 kg
Supply rate = 200 kg/hr
Initial content = 100 kg
Working sessionWorking session Do the same for ingredient A, use
the same storage information based on B (capacity, supply rate, etc). Display for 12 batches. Suggest a solution for the problem that occurs