Water, Water Everywhere - Without cooling water, not much works in Wacker Chemie's Burghausen plant. That's why the owners equipped their water supply plants with the Simatic PCS 7 automation system during modernization of water plant No. 5. The result is a uniform operating platform for supplying cooling water, cooling and industrial gases.

"Media supply in the plant is of vital importance," said Hartmut Taubert, production engineer for E&IC and technical support at Wacker, describing the special role of cooling water at the Burghausen plant.

A network of several water supply plants and cooling towers provides a reliable supply of water not only in the right quantity but also at a constant temperature. The plant benefits greatly from natural features in the region - the sources of the water supply are the Alz River (flows out of Lake Chiemsee), together with the Alz Canal, the Salzach River (a tributary of the Inn River), and the Austrian Mühlbach River. Nature is an important helper, not just in terms of controlling the temperature. The water quality, too, is influenced to some extent by these rivers.

Integrated Data Network

This redundant water concept supplied by nature provides ideal conditions. The owners created a similar redundancy in their water supply plants and cooling towers. Every plant works independently, but a closely linked network with plantwide data management ensures that cooling water is supplied to all plant operations. Automation concepts must satisfy the requirements for integration while remaining flexible.

At the end of the 1990s, the water supply plants had already been upgraded from conventional electrical engineering, measurement and (automatic) control engineeringandcontrol-room-based technology to state-of-the-art operator control and monitoring systems available at that time from Siemens. In the course of this standardizing, Water Plant 5 was thoroughly modernized last year.

Untreated water from the Alz Canal goes through a basic mechanical cleaning process with screens before other materials are removed from the water by sedimentation. The water is then pumped through gravel filters and fed into the cooling water network. Since it is neither polluted nor warmed strongly during use, it is then returned to the Alz Canal.

The automation system of Water Plant 5 consists of a redundant server and multiple clients. The subsystems such as sand or gravel filters, lift pumps, screening units and sedimentation basins are connected to the automation system by the ET200M distributed I/O and Profibus.

Thanks to the new backplane bus for the ET200M, module replacement during operation is possible. In addition, filtration units and pumps from the phase 1 expansion were integrated and the existing Simatic S7 controllers and WinCC visualization were migrated to Simatic PCS 7 V7.0.

Even the pump monitoring and the motor control for the pumps at the Salzach pumping station are controlled by the new automation system. The pumps convey the water from the Salzach River to the sedimentation basins of the water supply plants over a 64-meter height difference. The performance and thus the flow rate of the pumps can be adjusted to precisely meet the current water needs.

Transparency And Reliability

"We made a conscious decision to select a system that has proven popular and successful in the plant for years," said Taubert.
In addition to the integrated, open system,Taubert said he appreciates appreciates the easy changeover to the new system as well as the cooperation with Siemens and the system integrators in the region.

The project was realized in only three months by system integrator Finze & Wagner (fiwa group), one of Siemens' certified solution partners for the chemical industry. Since its founding in 1972, Finze & Wagner has worked for Wacker as engineering company and active provider of complete planning and design services.

Reliable and easy operation is essential for a water supply plant.
"Since the shift workers rotate among the various media supply operations in the central control room, harmonizing these systems simplifies operation," Taubert said.

For the plant operators to easily familiarize themselves with the new system and the user interfaces, only details of the visualization were redesigned. The purpose of these small changes was to provide greater transparency and reliability during operation of the individual plants, which was achieved among other things by newly defined alarm limits, a similar color design and unified arrangement of buttons.

Wacker also places a high value on monitoring, including visualization and documentation of process data, such as water temperatures, water quantities or pressures in the cooling water supply. This is the basic information for the efficient control of the water supply plant equipment. Trend graphs and overviews of measurement values for the plant operation can be accessed easily. This also applies to verifications required by the German Federal Water Act.

Maintaining An Overview

In the course of the modernization and consolidation of supply operations, the old water supply control room was relocated and combined with two other control rooms for industrial gases and cooling into one central control room. All equipment involved in media supply across the plant is now operated and monitored from there. The Salzach and Mühlbach pumping stations are also monitored by video, so the operators can maintain an overview of the remote equipment.
"Time management was our biggest challenge when migrating Water Plant 5," said project manager Josef Ostermeier of Finze & Wagner in Burghausen.

The first idea was to migrate during operation, but a planned shutdown in the colder months was used for the upgrade. Work began in October 2010 with the software engineering for the control replacement and the visualization of Water Plant 5. Three months were left to prepare the functional specifications, to change the complex hardware (which included dismantling an old, but still operable, mosaic-type control panel), for software engineering, and for performing the so-called loop check of about 1,000 inputs and outputs.

Thanks to the cooperation of all partners, commissioning was completed on schedule before Christmas 2010. This meant that the conversion of the switching stations for water plants 4a and 4b, and the migration of the Salzach pumping station to Simatic PCS 7 process control system could start in January 2011 - exactly as planned. The factory acceptance test was passed in March 2011, and thus all modifications of the cooling water supply system were completed just in time for warmer weather.

Outlook Of Water Management

Reliable water management is essential for the successful operation of pumping stations and water supply plants, and for the reliable supply of cooling water to the chemical plant. That's why Wacker in Burghausen has combined the formerly separate control systems for supplying cooling water, cooling and industrial gases into a uniform operating platform with Simatic PCS 7. As a result, the increased demand for sufficient cooling and industrial water in the coming years can be met.