Superbatch

As producers continue to strive towards the highest possible performance, companies who provide CIM and MES solutions to the batch process industries are looking for opportunities to assist their customers. Although the recognized way to achieve peak performance is through finite-capacity scheduling, tools designed for the process industry have proved disappointing, due to their inability to model real-life processes and the difficulty of keeping them updated in line with actual production events.

The company is now able to offer a solution to this problem with its Superbatch scheduling engine. It is both a proven technology and a major step forward in plant-wide batch management technology thanks to its innovative functional design, flexible modelling language (ISA S88.01 conforming) and general, yet fast, scheduling algorithms. It offers the unprecedented ability to work on-line, in conjunction with standard batch control systems, and update schedules as new demands arise or delays and process variations occur.

The Scheduling Problem
At its most fundamental, scheduling is a decision-making process which matches demand for products to available resources to find what and how much should be made and also when and where it can be made.

Difficulties arise when real-world complications are introduced such as multi-step and parallel operations, partially-connected plant and most especially the management of storage tanks. A scheduler like Superbatch, that works at the detailed operational level, must deliver schedules that respect all the constraints of the plant and are directly executable by the production staff or control system.

Further problems arise when the schedule is carried out, as every change in demand, small delay, variation in process yield or resource availability will cause the actual production to deviate from the original schedule. Inevitably, from the moment it is launched, the value of a static schedule declines rapidly towards zero.

Manufacturing Execution Systems (MES) are increasingly used to manage production by downloading instructions to a number of capable batch control systems and by recording production achieved. While these systems faithfully record actual production, the help they give to production managers is strictly limited to what has already happened. The ideal MES would be constantly looking ahead to identify problems in the future requiring action now, such as late despatch, unplanned stoppages and shortage of materials.

The Superbatch Solution
Superbatch not only solves all these problems, but it is already proven in industrial-scale applications. Designed for embedding within a client's MES or scheduling product, Superbatch provides flexible, ISA S88.01 process scheduling for static off-line scheduling and for dynamic scheduling, where changes are broadcast once a minute to screens in departments throughout the factory.

Modelling
The product uses a modelling language which conforms to ISA S88.01 and provides extensions to cover scheduling requirements. This describes the plant, the materials, recipes and ancilliary procedures (such as changeovers and cleaning suitable for hygienic industries) as well as the production batches themselves.

This advanced language has been refined over many years. For example, procedures are not limited to single operations but can be implemented as networks of parallel operations, if required, with limited waits in between. Plant equipment may be either single or multi-purpose and connected in complex networks. Resources such as steam, electricity and different grades of staff may also be modelled.

Compatible materials can be mixed and re-work, including rinse water, can be accommodated too. A critical feature of process scheduling is the management of storage vessels. Superbatch provides advanced options including:

• the ability to start emptying before filling is complete, if appropriate.
• overlaps, where filling or emptying can switch over to the next available tank
• parallel operation, needed when tanks serve as buffers between processes

These features are essential for accurate on-line operation.

Off-Line Scheduling
Once embedded within a graphical user-interface to present the schedule, Superbatch will find the earliest possible time for each batch, subject to the constraints of the model. Equipment allocations may be pre-defined or picked by the user from the feasible set which it offers.

Superbatch also delivers the profiles of each plant item as needed to draw a graphical schedule.

Clients using the product to build static scheduling tools can deliver detailed, executable schedules. Since the plant structure is part of the model, the company and its clients successfully use off-line schedules to design new process plant and plant extensions and check the impact on manufacturing operations of new recipes, maintenance or cleaning procedures.

On-Line Scheduling
Alongside the off-line planner, Superbatch provides an on-line monitor which executes the schedule and a versatile interface called ControlLink which accesses control systems (and simulators) usually across a network.

Scope
Superbatch was designed to work in an integrated environment. Functionally it sits on top of, and communicates with, standard batch control systems to provide the vital plant-wide schedule co-ordinating function.

It can accept a list of batches to be produced from other systems which may range from interactive planning boards and simple spreadsheets to sophisticated mathematical optimization tools run off-line.

In the latter category, the company offers gBSS, its own optimizer for multi-purpose plant design and planning.

Technology
Superbatch is written in object-oriented C++ adhering to the ANSI draft standard, using rpc for its networking, and is portable to a wide variety of environments and control systems.

Process Systems Enterprise Limited, Bridge Studios, 107a Hammersmith Bridge Road Hammersmith, W6 9DA United Kingdom