Batch Process Management

Batch process management involves various activities like process control, unit supervision, process management, production planning and scheduling, production management, management of production information, and recipe management. 

A batch management system based on ISA S88 allows the physical model to be created based on the P&I diagrams and a database of all materials.

Batch Management System is a separate system at the supervisory level in the control system hierarchy. It uses an open database like SQL Server for storing the materials data and the recipe information.

Although the S88 standard was available since 1995, it was not very popular since the Batch Management Systems based on it were far too expensive and its implementation required a lot of customization, which in turn required highly skilled engineers for implementation and support. The automation systems in those days were also not so open and flexible, which made adapting to such Batch Management systems difficult. Over the period, the automation systems as well the Batch Management systems have evolved to versions that are more flexible, easier to use and less expensive.

Batch Management Systems explains how to utilize the building blocks and arrange the structures of modern batch management systems to produce flexible schemes suitable for automated batch management, with the capability to be reconfigured to use the same plant equipment in different combinations.

It introduces current best practice in the automation of batch processes, including the drive for integration with MES (Manufacturing Execution System) and ERP (Enterprise Resource Planning) products from major IT vendors.

Evolution of Batch Process Management

During the initial period, automation involved transfer and charging of liquid raw materials and solvents from respective storage tanks to the batching tanks, mixers or reactors, remote monitoring of parameters like temperature, pressure, level and flow and remote operation of valves and motors. It was easy to achieve this using the available PLC/SCADA systems or DCS. Automatic temperature control of batch reactors was attempted using the conventional PID control techniques, without much success. Heavy investment in the automation system, field instrumentation and upgrading the manpower did not yield the desired results. The quality of the product, batch cycle time, productivity still depended on the knowledge and skills of the operator. Less than half of the process operations could be automated, and the rest continued to be manual. An operator was required to carry out field operations as well as go to the control room for carrying out the automated operations.

To reduce the dependence on human skills, it was necessary to transfer the recipes and procedures to the automation systems. It was partially achieved by providing recipe and sequencing functions in the PLC/SCADA or DCS along with some customized software. However, due to frequent changes in formulations and addition of new products, the recipes and sequences were required to be changed. For carrying out these changes, services of the automation system engineers were frequently required. The dependence on the automation system vendor was not only expensive, but it was also prone to exposure of the confidential product formulation information to the automation system vendors. Another major problem was

that the SCADA or DCS stored the historical data on a time basis and not on a batch basis. It was difficult tracking a batch performance on time based historical trends. There was no means of recording the raw materials consumed, key parameters in critical phases, operator actions. If a batch was spoiled, there was no means of tracing the reasons.