Process group

Chemical methods of precipitation from aqueous solution are much more common, both in number and variety, than physical methods. The presentation hereunder briefly outlines the processes grouped under chemical methods. 

Production planning requires additional indices next to the production resource index reR. The production process 5 e S as core planning object in production is introduced. Production processes can be grouped into process groups ge G. Production campaigns have a dedicated index ceC numbering the campaigns on the resource. 

Production control data set boundaries and parameters for production operations of resources, processes, output and input products, process groups and change-overs. 

The initial process group grt, Vr e R, e T is the final input data having to be known in order to decide the resource s start-campaign in the first planning period. 

The production process hours lp mcess, V r,.s e IPi determine the duration of production process measured in hours. Process group hours hp roup, / r,g e IP6, teT represents the duration of a process group composed of one or multiple processes. 

Campaign and change-over decisions require several binary variables to decide, which process groups run on which campaign. The binary variable... 

In analogy, the binary variable OC not W R, c e C c e C. teT matches active process groups with active campaigns and uniquely assigns a process group to a campaign. 

Production constraints apply to resource, process and process group control data and model campaign and change-over planning. Initial constraints are related to production processes and planning of process times and quantities. 

The process group hours range between minimum and maximum campaign hours, if a process group is active. This constraint bounds the run time of campaigns per period and activates the process group, if related processes have got a positive run time. 

Scheduled shut down hours have be covered by process group time of the idle process group. 

Subsequently, active process groups are linked with active campaigns via active campaign modes as basis for change-over decisions as illustrated in fig. 71... 

Campaign mode Campaign index process group... 

In the following, the change-over and campaign planning constraints are detailed further. A process group is active, if a respective campaign mode is active. 

The sum of active campaigns must be equal to the sum of active process groups both cannot exceed the maximum number of campaigns defined for the resources per month. 

A change-over variable is set to 1, if campaign modes for first and second process groups and the respective ordered campaigns both are active. 

Process groups without valid change-overs cannot have active campaign modes when following directly one after another. 

It is assumed that only one change-over is possible for every process group combination per period. This assumption is valid for commodity production, where products are not produced multiple times in different campaigns within the same period. 

In order to ensure campaign planning across periods, the process group being the end campaign of the period has to be determined. 

Exact in one process group is the ending campaign of a period. 

The campaign mode OC °ie matching active process groups with active campaigns... 

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