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The Chekka cement works supplies cement to both local markets and the Middle East region.

Cement

Cementing Relationships

Holcim upgrades the Simatic DCS in one of its Lebanese operations in record time by teaming up with Siemens Solutions Partner Esprocessing.

Holcim, Lebanon - The most important construction material throughout the developed world is arguably cement. Cement is made essentially by crushing limestone and heating it together with clay and a bit of sand, iron, and ash, and then grinding it to a fine powder. In practice, the cement manufacturing process consists of many simultaneous and continuous operations employing some of the largest moving machinery used in manufacturing. The control system must be sophisticated and effective to manage these operations in real time, to ensure safe operation of the powerful equipment, and to deliver a high-quality product.

At Chekka in Lebanon, Holcim operates a manufacturing unit supplying cement to both local markets and the Middle East region. The facility is not new, and the operators were experiencing increased downtime due to technical failures. For example, there were problems with data communication with an external mobile plant that relied on the use of cables moving with the equipment. The Holcim management decided to solve these problems by replacing the original communication and control systems with new distributed control system (DCS) equipment.

Upgrading to the latest technology

Holcim appointed the Siemens Solution Partner Esprocessing, headquartered in Paris, to help the company replace its control system, then based on Siemens S5 technology and the Cemat 4.12 process control system, with a new system using the latest version of Cemat, which is based on Simatic PCS 7 Version 7. Esprocessing was selected because of the company’s knowledge of Simatic DCSs, its experience in the cement industry, and a track record of successful projects in the Middle East, Africa, and the Indian subcontinent. The objectives set by Holcim were to install a new reliable, fast, and easy-to-use process control system that would minimize plant downtime, increase productivity, optimize energy use, and provide the plant operators with real-time process management data. Holcim required the new system to be installed during a planned kiln maintenance shutdown period of just 12 days.

Control room in the Chekka plant.

Migration in two phases

In view of the very short time window available to complete the site upgrade, the team decided to implement the revamping in two phases. In the first phase, the crusher, stacker, and utility processes would be migrated to PCS 7. The remainder of the processes would continue under the existing DCS. In the second phase, the rest of the systems would be upgraded to Cemat and PCS 7. For the two-phase approach to work, the upgraded units operating under PCS 7 needed to communicate and work together via Industrial Ethernet with the units still running the older systems.

The crusher, stacker, and utility processes were migrated by installing two AS/400 automation systems with a Simatic S7-300 controller for unit control, two redundant servers, an engineering station, a single station, and an OS client, all operating under Cemat based on Simatic PCS 7. To minimize downtime and prevent wiring mistakes, new Simatic ET 200M I/O modules were installed using preconfigured card adaptation units to connect to the existing wiring looms.

The communication issues with external mobile plants (stacker and reclaimer) were solved by replacing the old drum cable links with two new wireless networks. These link the S7-300 programmable logic controller (PLC) in each plant with the raw mill Simatic PLC. Esprocessing also added a server link from the raw meal conveyer belt analyzer back to PCS 7. This enables real-time regulation of the raw mix dosing system based on analysis of the raw meal output.

Smooth production restart

The Esprocessing engineers worked around the clock, and after just 24 hours the systems were up and running again using the new DCS. The engineers then moved on to the second phase, and within 36 hours the entire system was switched over to the new control system. After the 10 days of planned maintenance, Holcim started warming up the kiln and 30 hours later restarted production without any problems related to the new process control system.

Picture credits: Holcim