Chapter Five: Process Optimization through Control and High-Precision Measurements

Processes Optimization

Industrial process optimization is a general and broad discipline. We can define it as the organizational effort aimed at guaranteeing the maximum increase in productivity, the maximum increase in safety, and the reduction of operating costs. The purpose is to maintain productivity and efficiency levels as high as possible through careful control and dosage of the other variables that can be measured.

The reliability of control and measurement instruments is essential to achieve successful results in process optimization. So, it is also in the cement industry.

In this context, KIMA Process Control technological solutions based on artificial intelligence (AI) have several advantages that you can implement in your cement factory to control variables of the process optimization. 

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About KIMA

KIMA Process Control (KPC) is a technology research and development company founded in 1996, headquartered in Jülich, Germany.

Since its foundation, KIMA Process Control has established itself as a reliable partner for diverse industries. They focus on development, production, and commerce for industrial measurement and regulation technologies. KPC unites science with industrial demand and is your expert for all advanced measurement and control purposes in the process industries.

KPC technologies for rotary kiln shell temperature control, gas temperature, volume, and velocity control, optimization of grinding facilities, high-precision temperature and fill level measurement, and vibration speed control are integrated seamlessly into existing processes. While focusing on maximum effectiveness, they provide reliable information, monitor sensitive installations, and minimize wear and damage to systems and materials.

What are the technological solutions of KIMA Process Control for the cement industry and others?

Get to know them:

• KILNCOOLER

• SMARTFILL

• MILLMASTER

• SMART CONTROL

• GASTEMP

• V-SENSE

In this article we will deal with the technological solutions KILNCOOLER, SMARTFILL and GASTEMP. We will also make a brief comment about the other technological solutions (SMARTCONTROL, MILLMASTER and V-SENSE).

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KILNCOOLER

The increased case temperature can lead to hot spots and often the need to shut down the kiln for a week or more.

Did it happen to you?

When we ask experienced kiln operators what circumstances they think influence temperature rises inside kiln shells, in their answers, the exact reasons for a critical temperature rise differ from kiln to kiln, plant to plant another, and from one country to another.

However, there are four similar answers:

1. Increased use of alternative fuels, leading to increased wear on refractory linings and highly varied due to changing conditions;

2. Larger kilns with higher mechanical stress, leading to increased kiln ovality and refractory lining damage;

3. Use of inappropriate refractories;

4. Uneven coatings.

To solve these problems, KILNCOOLER is an efficient technological solution that controls the temperature of the kiln shell by spraying water (atomization) in the areas with the highest temperature or hot spots. Uses precise metering nozzles and valves, monitored by a FUZZY controller that uses infrared sensors to precisely locate hot spots on a circumference.

This means: only the hot spot is cooled down, not necessarily the entire circumference. The "hot spot temperature" can be set individually for each nozzle. 

What are the benefits of using the KILNCOOLER water spray cooling system?

• efficient cooling

• flexible use for hot spots and complete kilns,

• ready-to-use modules (stationary and mobile),

• easy installation or relocation,

• directed cooling on the circumference of the kiln,

• low noise emission.

The key to success is controlled, punctual and efficient cooling. Due to it being a liquid, the cooling efficiency of water is several orders of magnitude higher than that of air. The following example calculation (under the assumption provided in comparison table) shows this big difference in cooling efficiency. Under the assumption that the air blown to the complete kiln can be heated up by 40°C, one can dissipate roughly 2MW of thermal power by using 150,000m3/hr. of air (Figure 1). The same amount of thermal power can be dissipated with 0.9L/s of water, just 3.2m3/hr. water for a complete 60m kiln (Figure 2). 

As you will see in the next figure, not cooling the entire circumference makes it possible to avoid shrinking of the segment and reduce stress in the refractory. The right-hand side image shows the precise treatment of only the hot area with the KILNCOOLER. Shrinking is limited only to the required area.

KILNCOOLER can be applied to all types of rotary kilns for cement, lime, cellulose (paper), glass, among others.

What do our customers say about the KILNCOOLER?

Take a look at the comments of three customers who are satisfied with KILNCOOLER's efficient temperature control.

Holcim - Plant Höver, Hannover, Germany: “When we bought the system in November 2015, we were extremely lucky,” said Matthias Heuer, Production Manager. “Only a few weeks later and just before the Christmas holidays we had fundamental problems with hot spots.”

“A massive hot spot as a result of very thin refractory lining and permanent coating drops were treated with the water spray kiln cooler. Within hours we developed a new coating and stabilized the temperature profile of the kiln surface.”

“Without the system, we would have had to stop the kiln over the two-week holiday as our maintenance team was limited during this period. This meant that we were able to operate until our scheduled kiln stop in January 2016.”

AfriSam, Dudfield, Lichtenburg South Africa: Mr. Theo Conradie, Process Engineer, said, “At 12.0m we had some hotter areas in which the KILNCOOLER reduced the temperature from 350°C to 250°C within a short time. Only a few hours later we saw a second spot at 9.0m with a temperature of 390°C. We moved the system and the temperature dropped from 390°C to 330°C in around four hours.”

Apodi Cimento, Ceará, Brazil: Commenting on the success of KILNCOOLER, Marco Aurelio Silva, Plant Manager, said, “A hot spot was detected at about 31 meter – directly beside the kiln tire. In one hour, the spot temperature was reduced from 420ºC down to 360ºC. But only at the spot! An emergency kiln stop was avoided and the kiln could be further operated. The system has paid back on the first day!” 

Questions about KILNCOOLER?

Does water on a hot iron surface affect its integrity? How much water is really sprayed on the kiln per nozzle? The water we can provide is calciferous, will there be a lime layer and how thick will it be?

To know the answer to these and other questions, after reading this article, request the KILNCOOLER technical brochure, we will send it to your email.

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SMARTFILL

There is nothing more damaging for a ball mill than working with a low fill level: low productivity, high specific energy consumption, accentuated wear of the lining and grinding media, poor cement quality, excess noise, among other problems.

SMARTFILL is a high-precision 360° sound analysis, fail-safe fill level, and temperature measurement system for ball mills. Only SMARTFILL works with structure-borne sound directly on the mill shell separately for chambers #1 and #2, plus temperature inside the mill. Its sensor as an integral part of the mill housing guarantees operation without crosstalk from other mills. SMARTFILL replaces old and inefficient measurement methods (such as microphones), quite useless for today's needs. You can forget about empty or overfilling ball mill fluctuations.

How does SMARTFILL improve your production process?

The precise results of your grinding process are directly improving your production process. In order to achieve this improvement, you permanently need to adjust the mill feed. While keeping the fill level at the optimum, the grinding process becomes stable. 

An experienced operator, for example, takes care of the fill level and manually changes the fresh feed. Using an automatic controller provides you with even more advantages and convenience. 

SMARTFILL automatic control reliably compensates disturbances like strong differences in raw material quality and prevents empty or overfilling. These advantages are based on fact. The automatic controller is reacting fast and precisely on concurrent events, taking the correct decision at any time.

SMARTFILL has a wide application range for all kinds of ball mills for cement, limestone, coal, gold ore, iron ore, aluminum oxide, and more. More than 900 mills worldwide work successfully with SMARTFILL.

For more information about SMARTFILL, after reading this article, contact us and we will send you the technical brochure to your email.

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GASTEMP

GASTEMP measures the transit time of an acoustic pulse, which passes through some known distance of a hot gas. Dividing the distance by the transit time gives the average speed of sound along the path that the pulse was travelling. So, the average temperature along the path is measured.

Usually, thermocouples installed in gas lines are generally subject to high wear and poor accuracy (fluctuation +/- 10%) providing inaccurate information due to pressure differential (ΔP) or pitot tube measurement. This affects the stability of the process and raises operating expenses.

On the other hand, GASTEMP is a contactless measurement by acoustic technology (precision +/- 1%), so a large amount of gas/air volume is optimized! With that result, you get reliability on all applications such as tertiary air, VRM outlet, WHR system inlet and outlet, clinker cooler balance, secondary air temperature measurement (exact information and no heat radiation effect).

This is the downcomer maintenance platform of the first German HeidelbergCement plant where GASTEMP is installed. The brand-new gas volume, speed and temperature measurement for most precise control function of ID fan and calciner/kiln operation.

After reading this article, contact us to send you the technical brochure about GASTEMP.

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Others Optimization Technologies KIMA

SMARTCONTROL - is a powerful, flexible and modular software system, suitable for controlling many technical processes due to its modular design. SMARTCONTROL provides a large series of “building blocks”.

All blocks can be combined in order to build sophisticated closed loop control systems for process industries. 

Handling of these blocks is very easy, mainly by graphical manipulation and parameterization of these blocks. In order to create control loops there are no programming skills required. The structures are simply created via ‘drag and drop’ of connections between blocks and/or signals.

Available technology modules: ball mills (cement, raw, coal, ore), vertical roller mills, roller presses, hot gas generators.

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V-SENS is extremely small and robust sensor has been developed for direct connection to a PLC. With its 4 to 20 mA output, it promptly shows the error status of engines, pumps, sifters, cyclones, mills, or kilns. Additionally, this sensor can protect many different aggregates in combination with threshold value switches by shutting the system down. Wherever exceptional oscillations indicate critical operating conditions, V-SENS can be used as certain indicator.

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MILLMASTER controls closed grinding circuits—fully automated. If required, without an operator. One system can operate up to four mills at the same time, thus increasing your facility’s availability by preventing overfilling and similar failures.

The consequent constant and optimal fill level ensures smooth and stable operation, leading to significantly less wear and a more homogenous product. Additionally, the output increases and the power consumption drops.

The new “auto-adaptive” mechanism automatically and independently determines and adjusts the ideal filling level to always ensure optimal mill operation.

MILLMASTER can be integrated with SMARTFILL and into every automation system—it is simply plugged in via a standard OPC interface. With your previous control system on standby, you can switch to it at any time.

MILLMASTER has a wide application range: vertical mills, ball mills, roller press, separator / fineness, hot gas generator, water injection and ventilation.

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More information?

For more technical and commercial information and case studies of each technology presented in this article, contact the consultants and specialists KIMA/ICC

ICC - Independent Cement Consultants is a technical-commercial representative KIMA Process Control

Contact us

• Dirk Schmidt - schmidt@kima-process.de
• João Butkus - joao.butkus@cementspecialist.org
• Juan Ortega - juan.ortega@cementspecialist.org

Copyright and Credits: The trademarks KILNCOOLER, SMARTFILL, GASTEMP, SMARTCONTROL, V-SENS, MILMASTER, logos, images, technical information published in this article belong to KIMA Process Control GmbH.