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

11

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