VHS Deliverable CS.7.1: Report on VHS Case Study 7

Experimental Multi Product Batch Plant

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Introduction

During the first year of the VHS project it turned out that one central interest of the consortium is the treatment of scheduling problems, as for all of the case studies apart from CS2 and CS3 scheduling aspects play an important role. It also turned out that case study CS1 which successfully has been introduced to provide a testbed for the applicability of verification technology to plant control is not so much suited for the formulation and demonstration scheduling problems for the following reasons:

There is only one product which is even hard to define because the process is a recycling process.
The plant dynamic is quite slow, e.g. transportation processes like emptying and filling take several minutes, there is an evaporation step in the process which takes up to 20 minutes. Therefore it is quite time-consuming to run schedules or test the results of optimizing schedules etc. on the plant.

Therefore a new plant has been designed in order to present a plant which is suited for the demonstration of scheduling problems and also can be used like case study CS1 to test research results on an existing plant. To enable this the following aspects have been considered during design:

The plant is a multi product batch plant as two products are produced from three raw materials, due to this it is possible to define quite complex schedules.
The plant dynamic is very fast, e.g. small tanks which comparatively large pipe diameters which makes it possible to run complex schedules within reasonable time.

An other important aim when designing the plant was to have a transportable plant which functions as an eye-catcher and therefore also might serve as a sign of the projects research results to a broader public on related events. The plant already has been successfully shown on two trade-shows (INTERKAMA99, Duesseldorf and ACHEMA 2000, Frankfurt).

Like the CS1 plant, this plant is also equipped with a Siemens S7-300 Programmable Logic Controller which was chosen because it is currently one of the most established PLCs. The programs where written in Siemens AWL dialect (which does not fully conform the IEC1131-3 norm) and Siemens SFC dialect. A graphical user interface was programmed using Siemens WinCC.
The plant was planned starting in Febuary 1999 (first ideas November 1998) to July 1999 and constructed from then until October 1999.

Presentation of the case

The first presentation of the multi-batch plant was given at the VHS meeting in Grenoble in November 1999 and a written description [Bau00] was made available on the VHS webpages early in 2000 covering the following items:

Plant and Process description including a piping and instrumentation diagram.
Presentation of a scheduling and optimization problem.
Short description of the control program for realizing a schedule.

Contributions to the case study

There are currently two contributions to this case study:

The description of the plant, as indicated above [BKS00].
A preliminary report on the formalisation of the online scheduling problem [AN00] using hybrid and timed automata models.

It is expected that these sources of information will trigger efforts in control synthesis in the third year of the project.

Appended documents

[Bau00] A demonstration plant for the control and scheduling of multi-product batch operations.
Nanette Bauer.VHS Case Study 7, 2000.
Download.Bibtex entry: Bau00:cs7descr.
[BKS00] A case study: Multi product batch plant for the demonstration of control and scheduling problems.
Nanette Bauer, Stefan Kowalewski, and Guido Sand.In accepted to ADPM 2000, 2000.
Download.Bibtex entry: bau2000adpm.
[AN00] Online scheduling for vhs case study 7 -- intermediate report.
Karine Altisen and Peter Niebert.VHS deliverable in Workpackage CS.7.1, 2000.
Download.Bibtex entry: AltisenNiebert00.

page created at Wed May 17 13:43:45 MET DST 2000 by Peter Niebert
last modification: Mon Nov 13 15:56:25 CET 2000