Upgraded control system boosts tobacco processing

Background

Tobacco Processors Zimbabwe is a world-class tobacco processing company that provides dedicated facilities and services for handling, storage, processing and packing of leaf tobacco to clients who export their products world-wide. It is owned by local tobacco merchants and provides the first stage of processing of tobacco leaves that will ultimately be used for a variety of consumer products.

While the growing and harvesting of tobacco products is a comparatively uncomplicated and traditional process, the business of preparing the leaves is considerably more complicated. It not only requires sophisticated equipment to take the raw materials from leaves to dried, packed products, but it takes a high degree of control of the equipment to make the processing plant run efficiently and effectively.

It produces a range of products namely, threshed lamina, tobacco stem, bundle leaf, loose leaf and hand strip and it operates three processing lines. These are responsible for blending of tobacco products into packing grade, tipping, busting, conditioning, threshing, drying and packing ready for distribution to the company’s clients.

Quality and integrity of the end-product is an ultimate concern and for this reason the TPZ plant and processes are ISO certified to both ISO 9001:2008 and ISO14001:2004 standards.

The challenge

TPZ was established in 1987 as a processing plant to service the needs of three local tobacco merchants. Through the years it has grown and expanded to service a growing number of clients (including its shareholders). Aging network infrastructure and control systems in recent years had contributed to the plant not running as productively as it could have and fault finding across the aged communication system including its legacy network and various I/Os was becoming problematic.

To compound the situation further, most of the technical glitches that were being experienced could not be explained because of the lack of diagnostic tools which considerably prolonged trouble shooting. In order to address the cause of the issues, TPZ decided to take proactive steps to modernise the entire plant’s control system inline with the latest technology systems and controls available.

Considering the large size of the plant and the scale of the network upgrade a mammoth task lay ahead. The installation had to be seamlessly undertaken in order to minimise interruption of production. System integrators, Auto Control Systems, would therefore be required to work in tandem with Schneider Electric’s technical team to ensure quick and accurate installation and programming of the system and so minimise down-time while the upgrades would be in progress.

The solution

Auto Control Systems proposed that all control systems be upgraded (and standardised) to use Schneider Electric systems and components only. This would simplify communication across the network and would also enable the seamless migration of data from the old network across to the new system. With a 100% Schneider Electric install base they would also be able to make use of the various tools available from Schneider Electric to synchronise data across the network upon commissioning of the new system. In terms of hardware, the upgrade called for a move from
the legacy FIPIO network to a modern and open Ethernet network. This would enable faster communication speeds and vastly improved troubleshooting capabilities through its onboard tools. It would also allow ring and star topologies to be implemented for improved reliability. Simultaneously, PLC would be upgraded to Schneider Electric’s powerful new M340 and UnityPro technologies that allow far more flexibility and control of a wider,more customisable range of I/Os and field devices.

Modern new XBTG human man interfaces (HMI) were also installed across the plant to allow simplified operation and make information more readily available at the fingertips of the plant’s operators and controllers. The addition of Vijeo Designer would also allow engineers to more easily interrogate the system and simplify the replacement or upgrading of field instruments.

Planning steps

Downtime is a costly affair in the tobacco processing industry. As a result, Auto Control Systems had to carefully plan, prepare and quickly install the new systems to minimise lost production time. In order to achieve this Auto Control Systems proposed a two phase upgrade path that would cause the least disruption to operations and allow for a more controlled shift to the new system.

In terms of the plan the first phase would entail the complete upgrading of the FIPWAY and FIPIO network to Ethernet. This would allow for full communications to be established to new devices and components as they were installed. In addition, four other critical process’ controls and HMI would be upgraded from legacy systems to the new XBTG and Unity systems. Upon completion the next phase would call for the upgrading of a further two process control areas , where after line one and two field devices would be upgraded to be controlled from the M340 PLC.

In order to further minimise downtime and simplify on-site installation processes, Schnieder Electric and Auto Control Systems technical teams worked together to ensure that preparation (including programming, conversions, data transfers, parameters etc) was undertaken off-site and off-line as far as possible to enable systems to be brought up quickly after the physical installation had taken place.

Overall ROI

In terms of obsolescence of equipment the benefits of upgrading are enormous. Downtime was already costing the company a considerable amount of money in terms of lost production due to low equipment availability. It is estimated that the company could have lost millions of rands on process downtime alone. In addition, prolonged downtime could have an even more devastating effect on the operation due to nondelivery to customers etc.

Apart from obsolescence and the mitigation of risk, the upgrade is expected to substantially improve overall through-put of the plant and contribute to still higher earnings. Easier upgrades and additions of field equipment and other devices will also enable seamless future upgradeability and the ability to adapt internal processes to fit the exact needs of clients. Improvements in the quality of end-products can also be expected as a result of the more precise nature of the new control systems. In addition, substantial energy savings can be expected as a result of the better programming tools and resultant efficiencies across all equipment on the plant.

Summary

The move to standardise control equipment to Schneider Electric is a progressive move and one that will continue to bear fruit for TPZ in years to come. Not only will the high quality of the equipment deliver troublefree operation in future, but the ability to communicate seamlessly across all platforms considerably simplifies the operation and reduces the amount of training required by on-site staff.

The move to Industrial Ethernet and Unity Pro software provides infinite control for systems engineers to customise and continuously improve the system whenever required. This not only allows the plant to be operated in a highly productive and efficient manner, but also minimises the risk of stoppages and downtime. When problems do occur the advanced fault finding tools aboard Unity Pro allows quick recognition on any of the XBTG HMI’s throughout the plant.

The switch to new technology also mitigates the risk of using unsupported systems that may require specialist or scarce skills to undertake repairs and also enables seamless communication with modern systems including Window 7 based operating stations?