Source Blocks

A source block is where a fluid enters the PFS diagram. A source block has zero inputs and one type of output (but may have multiple instances of that one type).

To configure a source block, in addition to the common block properties, you will need to specify the following:

• Throughput
  • Units allows you to specify the units used for measuring output (mass) and time. For example, you might measure throughput in terms of kilograms per hour.
  • Throughput defines the amount of output that can be delivered by the block in a given period of time. This can be a constant numeric value, a variable or a throughput profile.
  • Flow Cost allows you to choose or create a cost model to represent the cost per unit of output delivered by the block.
  • Allocation allows you to specify how output is routed if multiple outgoing paths from the block exist:
    • If Allocate according to connection priorities is selected, the output will be allocated according to the priorities specified for each connection (i.e., all output will go to the highest priority connector until its capacity is reached, then all output will go to the next highest priority connector and so on). When this option is selected, you will be able to set priorities by selecting each connector that carries output from the block and using the commands at Process Flow > Selection > Output Priority. The output priority for each connector is shown at the beginning of the connector caption.
    • If Weighted++ is selected, the allocation will be weighted according to the maximum output specified for each path (in the section directly below). The software calculates the total capacity of all possible paths and determines the percentage of the total capacity represented by each path, then sends that percentage of the "stream" to each path. Once this allocation is calculated, if a particular path is unable to handle what is allocated to it due to restrictions downstream, that path will  handle only as much throughput as the restriction allows. The throughput of the other paths will be adjusted using the maximum output for all the throughput that is left beyond the restricted path.
    • If Equal++ is selected, an equal share of output will be allocated to each of the paths as long as the equally allocated output is equal to or less than the total throughput. If the total throughput is greater than what can be achieved by equal allocation, then the system will allocate as much as possible using equal allocation across all the paths, then try to allocate what is left equally into the paths that still have capacity left. This is repeated until all paths have reached maximum capacity or the total throughput has been allocated across the paths.
    • If Weighted allocation across paths is selected, the allocation will be weighted according to the maximum output specified for each path (in the section directly below). The software calculates the total capacity of all possible paths and determines the percentage of the total capacity represented by each path, then sends that percentage of the "stream" to each path. Once this allocation is calculated, if a particular path is unable to handle what is allocated to it due to restrictions downstream, that path will handle only as much throughput as the restriction allows. The throughput for the other paths is not changed.
    • If Allocate equal share to all paths is selected, an equal share of output will be allocated to each of the paths. If a given path's capacity is reduced, all other paths will be reduced accordingly. For example, in extreme cases, this can lead to zero throughput for all paths if any one path's flow is reduced to zero.
  • Maximum output defines, for each connected path, a maximum amount of output that can be sent to the path.