Cement manufacturing is a complicated, resource-intensive process in which limestone and other materials are crushed and milled, preheated to separate glass from solids, and then heated in a kiln at temperatures up to 1,450 degrees Centigrade (C). Large quantities of fuel are needed for preheating raw materials and keeping kiln temperatures high enough to produce the calcium silicate and aluminates that represent modern cement mixtures. Traditionally, the fuels used in cement making have been coal, oil and gas. However, due to the increasing financial costs associated with fossil fuels — as well as the negative environmental impacts — cement manufacturers around the world are beginning to explore the use of nontraditional fuels such as scrap tires, paper waste and plastic waste.
These secondary fuels differ greatly from conventional fuels in terms of their physical characteristics and combustion processes, which can disrupt the complex cement-making process if they fail to maintain the proper temperatures, material concentration and other conditions required for a high-quality cement product. To successfully replace fossil fuels with alternative fuels in cement production facilities — without costly physical testing and process — engineers at aixprocess have used engineering simulation software from ANSYS to analyze the real-world impacts of these “green” fuels. The company used fluid dynamics to simulate the effects of these fuels on combustion rates and outputs, heat and mass transfer processes, and chemical reactions within cement kilns. By relying on ANSYS® software instead of physical tests, the team of engineers estimates it was able to cut 30 percent of their analysis costs.
“By using software from ANSYS, we have been able to analyze the effects of replacing 40 percent of the traditional fuels used in an existing cement factory with alternative fuels. Specifically, we worked on determining the process modifications needed to maintain high kiln temperatures and to stay within other operating critical parameters,” said Martin Weng, co-founder of aixprocess. “We have learned that to use these new fuels, we must compensate with increased oxygen pressure and an intensified materials blending process. Real-world testing to reach this same conclusion would have taken much longer and been far more expensive.”
O2-limitation of burnout in the projected case of a 40 percent substitution of the primary fuel based on CO concentration.
Based on their simulations, engineers at aixprocess have a high degree of confidence that cement manufacturers can successfully replace traditional fossil fuels with alternative secondary fuels, leading to both economic and environmental benefits. Next, they plan to use software from ANSYS to analyze and optimize other aspects of the cement-making industry, including chemical reactions within kilns and the separation processes used to isolate gases and solids during the preheating phase.
“Because cement manufacturing is a complex process — characterized by heterogeneous flows, high temperatures, distinct phases and precise material concentrations — it is an ideal application for engineering simulation software,” said Thierry Marchal, director of industry marketing at ANSYS, Inc. “Given the many operating parameters that must be considered when making cement, physical analysis and real-world testing would prove both time- and cost-prohibitive. By running fluid dynamics simulations with ANSYS software, the aixprocess team was able to make a number of subtle process changes and adjustments required by the new fuels — ultimately discovering the optimal set of conditions under which green fuels can be used to support a high-quality cement product. Given how widely cement is used around the world, this work can have significant economic and environmental impacts.”
aixprocess will continue to apply tools from ANSYS as it seeks to improve other components and processes in cement-making facilities, as part of its participation in MoProOpt — a German government-sponsored project created to model cement manufacturing and optimize the processes involved.
The engineering company aixprocess was founded by Martin Weng (Dr. -Ing.) and Markus Hufschmidt (Dipl. Ing.) in 2001. The firm offers complete and problem-oriented consulting and engineering in apparatus design and plant construction, as well as process and flow technology. aixprocess engineers use a combination of conventional engineering methods and innovative simulation tools such as CFD modeling software to analyze and improve customers’ processes and facilities. By using virtual testing tools and facilities, aixprocess is able to reduce development costs significantly.
About ANSYS, Inc.
ANSYS, Inc., founded in 1970, develops and globally markets engineering simulation software and technologies widely used by engineers and designers across a broad spectrum of industries. The Company focuses on the development of open and flexible solutions that enable users to analyze designs directly on the desktop, providing a common platform for fast, efficient and cost-conscious product development, from design concept to final-stage testing and validation. The Company and its global network of channel partners provide sales, support and training for customers. Headquartered in Canonsburg, Pennsylvania, U.S.A., with more than 60 strategic sales locations throughout the world, ANSYS, Inc. and its subsidiaries employ over 1,600 people and distribute ANSYS products through a network of channel partners in over 40 countries. Visit www.ansys.com for more information.