- Modern cement development began with the start of the Industrial Revolution, driven by three main needs:
- Portland cement (hydraulic) for finishing brick buildings in wet climates
- Mortars for masonry construction of harbor works, etc., in contact with seawater
- Development of strong concretes
A cement is a substance used for construction, where mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Cement used in construction are usually inorganic (lime or calcium silicate-based), characterized as non-hydraulic or hydraulic, depending on the ability of the cement to set in the presence of water.
Non-hydraulic cement does not set in wet conditions or underwater but, it sets as it dries and reacts with carbon dioxide in the air. Hydraulic cements (Portland cement) sets and becomes adhesive due to a chemical reaction between the dry ingredients and water. The chemical reaction results in mineral hydrates that are not very water-soluble so this allows setting in wet conditions or underwater.
There are several types of cement production processes: dry, semi-dry, semi-wet, and wet, depending on the preconditioning process of raw. But nowadays, almost all plants are based on the dry process where the main stages are:
- Feed stocks preparation: this stage includes the process of siege, crushing, and pre-homogenization. Typical raw materials used for cement production have 85% cayenne, 13% clay or blackboard, and remaining materials such as silica, alumina, and iron ore. These feed stocks are crushed into particles with a diameter of less than 20 mm and mixed with a pre-homogenization pile.
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- Clinker production: the feed stock first enters the raw material to make a fine powder where 85% of the material is less than 88 μm. Then, the feed is transferred to the homogenizing silos. Afterwards, the meal is thrown into the pre-calciner tower to start the chemical change to cement. Towers mixes homogenous feed with exhaust kiln gas to recover energy at almost 1000°C and to initiate chemical reactions that result in cement. Inside the kiln, temperatures reach approximately 1400°C to complete the process of chemical reactions and produce calcium silicates, called clinkers, with a diameter up to 25 mm.
- Cement preparation: in this stage manufacturing process is completed. Clinker nodules are milled into cement where cement is ready for use as a binder in various concrete mixes.
Primary Process Control Improvements for Cement Production Processes
Prior to any advanced process control (APC) project, even in cement production processes, base-level PID tuning and optimization is a critical pre-requisite step. Unless base-level PID control loops are well tuned, advanced process control (APC) cannot work well, since advanced process control (APC) will be manipulating the setpoints of the base-level PID control loops. Therefore, the first necessary step in the overall process control improvement procedure for cement production processes is PID tuning and optimization of primary or base-level PID controllers. The benefits of PID tuning and optimization in cement production unit is the reduction of the oscillation amplitude or increase of the controller action by a factor of 2 or 3. This allows to enable smoother running of the cement production plant with increased stability in all control loops avoiding unnecessary cement production plant problems such as: damage and/or to fast wear and tear of the equipment, plant irregular shutdowns or off spec product properties and/or grades.
PiControl Solutions LLC has extensive experience in PID tuning and optimization for PID controllers in the cement production industry.We understand and know how to tackle with typical PID control loop problems and have customized PID tuning and optimization software tools to help optimize all cement production unit controllers.
Our unique and novel closed-loop system identification technology makes it possible to tune and optimize base-level PID control loops quickly, efficiently and precisely. With our closed-loop technology we can perform system identification and PID tuning optimization of the following critical base-level PID controllers easily. Moreover, all process and data analysis and PID tuning and optimization work can be easily performed remotely by PiControl Solutions LLC process control engineers.
Advanced Process Control (APC) Improvements for Cement Production Processes
PiControl Solutions LLC has extensive experience in advanced process control optimization for cement production processes. We understand the economics factors that drive the profit margin and have customized multivariable closed-loop system identification and advanced process control (APC) design and optimization tools to help optimize and improve the cement production units.
Because of the relatively small size of many cement production plants, it is more cost-effective to implement DCS-based APC (advanced process control) rather than model predictive control (MPC) techniques. DCS-based APC (advanced process control) approach is fast, cost effective, all inside the existing DCS/PLC, avoiding the complications of OPC/other data communication links from computer to DCS.
We focus to analyze the process and provide the right economic advanced control solution for each cement production plant. Our DCS-based APC (advanced process control) methodology has proven particularly successful in the cement production area. Our DCS-based APC (advanced process control) design will result in the following cement production benefits:
- Optimization of cement kiln operation – The main process control goal of a rotary cement kiln is to maintaining a given temperature profile along the kiln at the lowest energy consumption possible. The rotary cement kiln process many times seems to be unstable because of long slow process dynamics and large disturbances. Our DCS-based APC (advanced process control) methodology will provide increased throughput but stable and tight temperature profile control of a rotary cement kiln with the lowest energy consumption possible.
- Optimization of furnace performance using alternative fuels – Burning process in the furnace unit can lead to instability of the rotary cement kiln in the clinker manufacturing process, especially if alternative fuels are used. Our APC (advanced process control system) can improve the control and mixing rates of alternative fuels to ensure consistent burning, while also ensuring that the kiln does not become unstable due to changes in fuel calorific value.
- Optimization of ball mill control – The most important quality-relevant parameters in cement grinding ball mill process which determines the quality of the produced cement are the fineness, Blaine and the slope of RRSB PSD curve. Our DCS-based APC (advanced process control) system will provide increased throughput of the ball mill by predicting and optimizing all quality-relevant product parameters which finally will be compared with and adjusted, based on the lab assays.
- Optimization of a blending process – Stable and correctly proportioned raw meal is essential for energy-efficient clinker production. Optimal cement blending process at the right proportions can be ensured using our APC (advanced process control system)which will provide wanted specifications and quality of a product for the end-customer.
There are other benefits from our DCS-based APC (advanced process control) technology, such as: smoother plant operation, automated loading and unloading and less work for the operators.
After DCS work on advanced process control (APC) schemes is complete and all advanced process control (APC) parameters are calculated and optimized, PiControl Solutions LLC will over factory acceptance test (FAT) make sure that the advanced process control (APC) design is complete, correct and operable. After completion of process control (APC) control project, PiControl Solutions LLC will conduct dedicated process control training for cementproduction company.
PiControl is an innovative process control software and services company that offers state of-the art, modern solutions at a lower cost, implemented in shorter time compared to competitors.
PiControl Solutions is the only process control and automation company in the world which can perform any advanced process control (APC) project completely remotely. Nowadays, every country uses high speed and reliable internet connection and with a help of medium to high resolution cheap web-cameras or even over widely used remote meeting and screen sharing applications it is possible to do complete design, tuning and optimization, FAT test and start-up of any advanced process control project. Over this low cost online/remote approach huge travel and accommodation costs can be saved and human health and safety can be kept on the high level.
For more information and details, please send us an email: info@PiControlSolutions.com or call the Tel: (832) 495 6436.