German China India

Advanced Process Control

Advanced Process Control Boosts Energy Efficiency and Product Quality at a Cement Plant

| Editor: Dr. Jörg Kempf

The control room of the Rohrdorf cement plant (Picture: Siemens)
Gallery: 4 Pictures
The control room of the Rohrdorf cement plant (Picture: Siemens)

The grinding stage in a cement plant is extremely energy-intensive, consuming almost half the plant’s total electric power requirement. An expert system, designed especially for cement production and based on components from the advanced process control (APC) library of the Simatic PCS 7 control system, uses real-time plant data to make precise statements about the plant’s quality parameters, and can be integrated into the existing control system with no additional hardware requirements.

At the Südbayerisches Portland-Zementwerk in Rohrdorf/Germany, raw materials extracted from nearby quarries are stored in a blending bed hall and then ground into “raw meal” in a raw mill. In the rotary kiln the raw meal is then burned to create Portland cement clinker, the basic material for all types of cement. The next step is to grind the clinker in a ball mill equipped with steel balls of varying sizes. Depending on the type of cement, other materials such as granulated blast furnace slag can be added at the grinding stage. The Rohrdorf plant has four ball mills with a total grinding capacity of around 270 t/h.

The grinding medium moves in different ways depending on the rotational speed of the mill. Low speeds create a cascade motion in which the balls merely roll around. As the speed increases, the balls are lifted and fall onto the milled material (“cataracting” motion). Above the so-called critical speed, the balls are held against the drum wall by centrifugal force, so scarcely any grinding takes place. The optimum operating speed is above the point at which cataracting begins, and below the critical speed.

Content of the Article:

Comments are being loaded ....

Leave a comment

The comment is checked by an editor and will be released soon.

  1. Avatar
    Avatar
    Edited by at
    Edited by at
    1. Avatar
      Avatar
      Edited by at
      Edited by at

Comments are being loaded ....

Report comment

Kommentar Freigeben

Der untenstehende Text wird an den Kommentator gesendet, falls dieser eine Email-hinterlegt hat.

Freigabe entfernen

Der untenstehende Text wird an den Kommentator gesendet, falls dieser eine Email-hinterlegt hat.

copyright

This article is protected by copyright. You want to use it for your own purpose? Contact us via: support.vogel.de/ (ID: 27423040 / Control & Automation)