The terms ‘Occupancy Time’ and ‘Across-Batch Idle time have only meaning when viewing the equipment resource in a multiple batch perspective.
Procedure Cycle: the once through execution of all operations in the procedure’s queue (one after another as specified by the user on The Operation Sequence Dialog).
Procedure Cycle Duration: the amount of time it takes for single procedure cycle to complete. The procedure cycle duration is always calculated as the time lapsed between the start of the first operation in the queue and the end of that the last operation in the queue. Note that this time may not be equal to the sum of all operation times in the queue as some operations’ timing may overlap others in the procedure (e.g. stir while heating) or there may be gaps between the end of one operation and the start of the next.
Procedure Cycle Time (aka Time Between Consecutive Procedure Starts): the amount of time between consecutive procedure starts (each start handling material from a different batch). Note that a procedure start may trigger the execution of one or more cycles (per batch).
Cycle Cycle Time (aka Time Between Consecutive Cycle Starts): the amount of time between consecutive cycle starts (when each cycle is handling material from the same batch). The cycle time is meaningful if the procedure’s operation sequence is repeated multiple times during a single batch (i.e., the Number of Cycles Per Batch is greater than one).
Procedure Number of Cycles (per batch): the number of times a procedure’s cycle sequence is repeated during the processing of a single batch amount.
Procedure Number of Cycles (per main recipe cycle): the number of times a procedure’s cycle is repeated during the processing of the main recipe cycle time (for independently cycling procedures); see Procedure Cycle Time and Independent Cycling Procedures.
Procedure (Total) Time (or Procedure Duration): the total time it takes for all cycles of a procedure to be completed. It is equal to the time span from the start of the first operation in the queue of the first cycle and the end of the last operation in the queue of the last cycle. If the procedure has only one cycle, then the procedure time (or duration) and the procedure cycle duration are the same. If the procedure has multiple cycles, it is possible that there may be a gap between the end of one cycle and the beginning of another. In that case, the procedure duration is longer than the sum of all cycle durations. There may also be an overlap between cycle durations (if staggered equipment are involved). In that case, the procedure duration is shorter than the sum all of cycle durations.
Operation Setup Time: the amount of time (per cycle) spent before each operation is carried in preparation for the actual execution of the operation. It may involve actions like cleaning, vacuuming, setting up of equipment, etc. which the user opted not to model explicitly.
Operation Process Time: the amount of time (per cycle) during which the actual processing is done. The process time is either specified by the user or calculated by the program.
Operation Turnaround Time: the amount of time (per cycle), that the operation’s equipment is being prepared for the next cycle (cleaning, transferring of material, sterilization, etc. that is not explicitly modeled but simply lumped up as part of the operation’s cycle time).
Operation Duration: the amount of time it takes for an operation's to be performed. The Operation Duration is the sum of the Operation’s Setup Time, Process Time and the Turnaround Time.
Operation Start Time Shift: the time elapsing between the start of an operation and a reference point in time. The reference point can be:
a) the start of the batch
b) the end (or start) of the previous operation (whatever may be) in the sequence
c) the end (or start) of another (named) operation in the same procedure
d) the end (or start) of another (named) operation in another procedure
Start Time Reference Operation: if the Start Time of an operation is not defined with respect to the start of the batch (absolute start time), then it is defined with respect to another reference operation (the Start Time Reference Operation). Note that the start time of an operation can be specified either with respect to the start or with respect to the finish of a start time reference operation.
Absolute Start Time: assuming the earliest operation in a batch starts at time 0, the absolute start time of an operation (or procedure) is the amount of time that elapsed since the beginning of the batch before this operation (or procedure) started executing. If the operation is part of a procedure with multiple cycles, the absolute start time refers to the start of the operation as part of the first cycle of the procedure.
Absolute End Time: assuming the earliest operation in a batch starts at time 0, the absolute end time of an operation (or procedure) is the amount of time that elapsed since the beginning of the batch before this operation (or procedure) ended executing. If the operation is part of a procedure with multiple cycles, the absolute end time refers to the end of the operation as part of the last cycle of the procedure.
Host Equipment or Container Equipment: the equipment resource engaged during the execution of a procedure. Remember that every icon shown on the flowsheet represents a procedure (and not a piece of equipment) that executes in a container equipment resource that may involve one (or more) pieces of equipment (transportation procedures present an exception since they have no associated process equipment).
Equipment Sharing: In a batch process it is common to utilize the same equipment resource for carrying out multiple procedures (equipment sharing). This is particularly common for storage when handling mixing of materials, heating, cooling, reaction, evaporation, extraction, crystallization, etc. By default, whenever a procedure is introduced in the process, the system assumes that the procedure is carried out in its equipment resource and therefore it creates one automatically for it. After the procedure is created, you can assign a pre-existing equipment resource to it (see Selection & Sharing).
Equipment Idle Time: It is the sum of all time spans where the equipment is NOT carrying out any activities as part of a procedure’s cycle specification. This includes:
a) Possible time lapse between the end of a procedure’s cycle to the start of the next cycle
Typically, this time is NOT available for any other in-batch or across-batch activities (unless the ‘Allow Use Across cycles’ is checked (see Equipment Data Dialog: Scheduling Tab).
b) Possible time lapse between the end of a procedure to the start of the next.
Typically this time is available for any other in-batch activity but not across batch activity unless the ‘Allow Use Across Batches’ is checked (see Equipment Data Dialog: Scheduling Tab)
c) Possible time lapse between the end of the last procedure (as part of a single batch activities) and the beginning of the first activity (cycle) of the first procedure in the next batch.
This time is always available for either in-batch or across-batch activity utilization.
Equipment Busy Time: the total time that the equipment resource is active (busy) with the execution of all procedures hosted by it and during a single batch. If the equipment resource is hosting only a single-cycle procedure, then the equipment busy time is the same as the procedure’s cycle duration (same as the procedure’s duration). If the equipment hosts only one procedure with multiple cycles, then the equipment busy time is equal to the sum of all cycle durations (i.e., it does NOT include any gaps between cycles). If the equipment resource hosts multiple procedures, then the equipment busy time is the sum of all procedure times (durations); i.e. it does NOT include any time between procedures (see A sample equipment occupancy chart.). Note that the sum of equipment busy time and equipment idle time equals the recipe cycle time (since the equipment can be either “busy” or “idle”)
Equipment Waiting Time: The sum of all time intervals between the end of one procedure and the start of the next procedure for all procedures hosted by an equipment resource during a batch. Obviously, this time only makes sense if the equipment resource hosts multiple procedures. If only one procedure utilizes the equipment, then the equipment waiting time is zero. In a typical case, the sum of the equipment busy time and the equipment waiting time, makes up the equipment’s occupancy time (see below).
Equipment Occupancy time: The time spanned from the start of the first procedure hosted by an equipment resource to the end of the last hosted procedure by the same equipment resource during a single batch. Note that this may not be equal to the sum of procedure times (if multiple procedures are hosted) as there may be some waiting time between the hosted procedure engagements (see A sample equipment occupancy chart.). If the equipment hosts only one procedure, then the equipment occupancy time equals the procedure time of the hosted procedure.
Equipment In-Batch Idle Time: the portion of an equipment’s idle time that is available for other in-batch activities. Typically it includes the waiting time and the time between the end of last procedure in a batch and the beginning of activities for the next batch. If there are multi-cycled procedures hosted by an equipment resource, and there are gaps (delays) between cycles, normally this time is not counted towards the equipment’s in-batch idle time, unless the option ‘Allow Use Between Cycles’ is checked (see Equipment Data Dialog: Scheduling Tab).
Equipment Across-Batch Idle Time (aka Available Time): The time that the equipment is not considered occupied during a batch (it simply waits until it is engaged by the next batch). It is the time between the end of the last procedure that is hosted by the equipment in one batch and the start of the first procedure that is hosted by the same equipment resource in the next batch. Note that the sum of equipment occupancy time and equipment across-batch idle (aka available time) time equals the recipe cycle time. Typically, if the equipment is hosting multiple procedures during a batch and there are gaps between the end of one procedure and the beginning of the next (waiting time), is not considered available for across batch use and therefore it is not included in the across-batch idle time; unless the option ‘Allow Across Batch Use’ is checked on the Equipment Data Dialog: Scheduling Tab; if it is, the waiting time is included in the across-batch time idle time.
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The terms ‘Occupancy Time’ and ‘Across-Batch Idle time have only meaning when viewing the equipment resource in a multiple batch perspective. |
To better understand the terms involved in the utilization of an equipment resource, please refer to A sample equipment occupancy chart. that shows the equipment occupancy chart for a sample process. Note that the recipe cycle time equals either the sum of busy time and idle time or the sum of occupancy time and across batch idle time. For more details regarding the equipment occupancy chart, please see Equipment Occupancy Chart.
Equipment Effective Occupancy Time: The equipment occupancy time divided by the total number of sets of equipment operated in staggered mode (see Staggered Mode).
Equipment Effective Busy Time: The equipment busy time divided by the total number of sets of equipment operated in staggered mode (see Staggered Mode).
Equipment Effective Waiting Time: The equipment waiting time divided by the total number of sets of equipment operated in staggered mode (see Staggered Mode).
A sample equipment occupancy chart.
Scheduling Bottleneck Equipment: the equipment with the longest occupancy time. The scheduling bottleneck equipment determines the minimum recipe cycle time and the maximum possible number of batches per year (see below).
Procedure Holdup Time: when a batch (cyclical) procedure, (e.g., chromatography) operates in a continuous process, the application assumes that the procedure processes material continuously fed to it and accumulated over a period of time called the holdup time. Typically the holdup time is specified by the user. The specified value of holdup time must be greater or equal to the cycle time of the batch procedure (unless multiple equipment units in staggered mode are involved). For more details, see Holdup Time.
Available Annual Operating Time (AOT): the amount of time per year that all equipment and resources are assumed to be available for running this process.
Utilized Annual Operating Time (AOT): the actual amount of time per year that all equipment and resources where engaged to run this process (may be less than the available annual operating time).
Recipe (or Process) Batch Time (RBT): the time elapsing from the start of the first cycle of the first (earliest scheduled) operation to the end of the last cycle of the last (latest scheduled) operation required to carry out a single batch.
Recipe (or Process) Cycle Time (RCT): the time between the start of two consecutive batches. For a feasible (realizable) campaign, it must be larger or equal to the Minimum Recipe Cycle Time (see below). If a batch is started right after the previous one is ended (but not before) then the cycle time equals the batch time. If a batch is started before the previous batch is ended (more typical) then the cycle time is less than the batch time. Note that there is a constraint as to how soon we can start a batch (while the previous batch processing is still in progress).
Minimum Recipe (or Process) Cycle Time (RCTmin): the minimum time possible between the start of two consecutive batches. It is equal to the longest occupancy time amongst all main equipment resources (excluding main equipment that are explicitly set to be ignored by the scheduling calculations and those main equipment set to be shared across batches).
Recipe (or Process) Cycle Time Slack: The difference between the (actual) recipe cycle time and the minimum recipe cycle time (must always be positive). To maximize the number of batches per year, the cycle time slack should be 0.0.
Maximum Number of Batches: the maximum Number of Batches possible to be processed in a calendar year (without violating the available annual operating time). This Number of Batches can be achieved when the process operates with a cycle time equal to the Minimum Recipe Cycle Time (or the Cycle Time Slack is 0.0).
Number of Batches Per Year: the number of times a batch can be processed in a calendar year (within the available operating time window for this recipe).
Campaign: a string of uninterrupted batch executions (of the same recipe) during a calendar year. Oftentimes, a specific product produced in batch, is produced annually in several campaigns. During the time between campaigns for this product, the equipment is utilized for the execution of recipes leading to other products.
Number of Campaigns: the number of uninterrupted sequences of batches produced each year.