Keeping control

Norbert Meierhöfer

Competition compels planners to significantly reduce development costs, use reliable processes, employ less capital and cut back on operating costs.

On the other hand, efforts are being made to automate processes and to keep them running on a continuous basis. In order to understand the difficulties involved in a batch process, it is helpful to take a look at a batching plant. Generally speaking, the plant is used to convert raw materials into products with a higher value by following prede-fined recipes and utilizing various plant resources. These resources comprise apparatus of widely varying types and sizes. In addi-tion, the overall process usually takes in a laboratory with its associated infrastructure. This abundance of possible variations is reflected at a very early stage in research and development, for example in the elaboration of a recipe. Later on during production, the complexity of some batching plants presents planners with problems of detail which are quite simply insoluble. Only a very few programs are tailored to batch processes or use a consistent data model which extends from the R&D department right through to production.

BatchPlus can be used to develop processes and create recipes. However, BatchPlus also fulfils a useful role in simulating sequences in order to gather all of the data required for scaling up. At the development stage, a general recipe is first prepared and adapted to the master recipe. Information is fed into this recipe from specified libraries comprising operations, raw materials and apparatus. Details of the recipe and any possible effects can be simulated by computer before the process actually starts.

There are two principal steps to be noted during process development. The choice of process must take account of the requisite raw materials, solvents, the physical condi-tions of intermediate products and their stability, as well as waste products and the safety of the process itself. The aim of this first stage is to design the process to be as simple as possible. However, attention to detail is called for, which is why BatchPlus also includes a heat calculation tool, for example, to optimize the use of energy and a modelling tool to separate complex, non-ideal compounds. There is even a tool to improve the recipe later on whilst the process is under way. However, BatchPlus software also includes far more extensive functionality, such as:

• material and energy balance sheets,

• scale-up,

• new plant apparatus,

• environmental analyses,

• cost analyses,

• case studies,

• sequence plans.

Even if all of the parameters are correct, the yields are not always the same. For the engineer, the question arises for example as to whether a low yield is simply a one-off anomaly or whether there is a detectable downward trend. Particularly in the case of very expensive batches, reproducible quality and early detection of a bad batch take on added importance. The Infoplus 21 software package combined with Batch 21 therefore offers practical support. The significance of process data such as pressure, temperatures and volume flows is assessed and integrated. However, these tools also gather batch-related data, such as start-time and end-time as well as qualities, costs and other characteris-tics, for analysis and documentation. Statis-tical process control has also been integrated into Infoplus 21 in combination with Batch 21. It is sometimes possible to deduce that the quality is deteriorating simply from a progressive increase in residence time. The program is able to both capture and process such data. The more costly and complex production becomes, the more difficult it is to achieve optimum operating characteristics. The fine detail in particular remains a problem for many companies. This is where MIMI can help with planning operational sequences. The fact is that it is necessary to do more than simply copy production data into a planning tool. With batch processes, it is a matter of translating the significance of individual batch data. MIMI uses the same basic data as Infoplus 21, the program applied in the research department.

Naturally, each of these tools also can be used individually. However, the true benefits only become apparent when a common database is applied throughout all the stages of a product’s lifecycle. Plantelligence bundles together a wide range of information packages such the BatchPlus modelling software, Infoplus 21 and MIMI. Petrochemical companies have been among the first to grasp the advantages of this way of working. In terms of hierarchy, Plantelligence slots in beneath the ERP systems, such as SAP or Baan, and above the field systems, in other words in classic terms above the process management system. This makes Plantelligence an integrated system for the entire company.

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Further information cpp-228