Global control of plants? No big deal. In Leuna, Germany, the Linde Gases Division has established one of the first and largest remote operation centers for central control of air separation plants in Germany, Austria, Switzerland, and the Netherlands.

As one of the world’s largest gas and engineering companies, the Linde Group employs approximately 49,000 people in more than 100 countries. The goal of the Linde Gases Division is to control all air separation plants worldwide with just eight remote operation centers (ROCs). The primary advantage of the ROC concept is the increased efficiency of plant operation. Special functions such as Automatic Load Control (ALC) and Linear Model Predictive Control (LMPC) allow continuous operation of the plants within the optimum working range, which increases productivity and saves energy. The central control renders time-consuming and cost-intensive on-site assignments superfluous, and the maintenance and shutdown of individual plants can be coordinated better. The control center and distribution are under one roof, which pays off in terms of faster and more accurate information flow about parameters such as the product stock for all connected plants and quick response to inquiries from the individual air separation plants.

The remote operation center features the latest technology and provides all local HMI functions of the remote process control systems via terminals (All photos: Linde AG)

Global access to local operating stations

The ROC provides all local HMI functions of the remote process control systems via terminals. Simatic PCS 7 is used as a standard for the automation of air separation plants at Linde, so it was very important to Linde that Simatic PCS 7 could also provide appropriate remote functions and the necessary openness and flexibility. In addition to the key HMI functionality, issues such as network technology with the appropriate IT security (secure external access to a PCS 7 automation cell, an internationally valid network topology, etc.) and usability were important factors to be considered in a high-performance and reliable total solution. The greatest challenge was to operate with very narrow-band network connections. In some countries, connections must be set up with bandwidths of 64 k. There is no local operation on the operating clients in PCS 7 for this – the local clients are accessed by the ROC with Terminal Services (remote desktop protocol). The remote terminals require no special software. Remote access is possible directly via Windows, for example.“The local personnel still look after the plant on the day shift,” explains Dr. Joachim Pretz, ROC manager at Linde Gases in Leuna. He compares the solution with aviation: “Metaphorically, the operator and the local engineers are the aircraft crew and the ROC is the tower with the air traffic controllers, manned 24 hours, seven days a week.”In the ROC, the operator “watches” over five air separation units with two monitors each. The CHIMS system from Siemens serves as a central reporting system in addition to the PCS 7 remote operation to provide a compact general overview of the plant status. The messages, alerts, and alarms of all the plants converge here so that CHIMS also represents a platform for the integration of other automation systems.

Simatic PCS 7 provides the appropriate control functions for remote access

Innovation through partnership

Approximately one year after the project was initiated, the first plants in Schkopau, Hamburg, Salzgitter, and Basel have been integrated and are being controlled from Leuna. Another 70 are to follow gradually. “Technical concepts down to the plant level were discussed and implemented in regular meetings between Siemens and Linde. Siemens gave us excellent support during the introduction of the new technology,” says Wolfgang Suchanek, IPC Platform Leader, Global Operations Linde Gases Division. “We were able to complete the project on schedule. Siemens implemented our requirements and developed and improved new tools with us. We are currently testing the latest CHIMS version, and our knowledge from this is fed back directly into product development. That’s what I call a cooperative partnership,” states Pretz.

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