1st Global CemProcess Conference
24 - 25 April 2017 - London, UK
By Robert McCaffrey, conference convenor
View the conference image gallery
The first Global CemProcess conference on process optimisation in cement manufacture has successfully taken place in London, with 90 delegates from 26 countries taking part, as well as 19 presentations and 12 exhibitors. Delegates paused the conference for its technical content and for its 'collegiate' atmosphere.
The Global CemProcess conference concentrated on process optimisation for two reasons: to allow cement plants to increase production and to decrease costs (ideally both at the same time).
Jose Favilla from the IBM Industrial Academy was the first speaker, looking at cyber models to create digital factories, the so-called '4th Industrial Revolution.' Digital factories are an example of a new generation of engineered systems integrating physical systems and processes with networked computing and cyber models. Favilla suggested that we are transferring from a programmable systems era to an era of cognitive or 'thinking' or 'learning' systems. At some stage in the process, an 'artificial intelligence' module may be incorporated into the system, which will eliminate the possibility of human error and which will also allow the system to improve itself over time. "The factory is just one part of the puzzle," suggested Jose. A network of cyber models will cover the entire process from quarry to concrete batching plant. The system learns from history, can maximise plant efficiency, decrease energy inputs and maximise product quality, while at the same time eliminating unexpected or emergency shut-downs. This machine-based approach, according to Jose Favilla, also "minimises the risk of 'knowledge leak.'"
The second presentation, given by Joachim Harder, was on the total market potential for cement plant automation (excluding China due to the difficulty of obtaining reliable figures). Harder pointed out that there was a peak in cement plant automation expenditure of around US$800m in 2007, which fell after the financial crisis and which has now steadied at around US$600m per year. Instrumentation is the largest value part of the automation market, followed by process automation and gas analysis. The largest market for cement automation systems was in Western Europe, with, in 2015, an 18% market share, followed by the Middle East (14%). The laboratory automation market, on the other hand, has remained strong for the last decade, albeit with a dip in 2010, and approaches around US$100m in each year. The leaders in this market are FLS, thyssenkrupp Industrial Solutions, Herzog/IMP, Sinoma and Iteca. Harder concluded that the market in China is no longer a serious market for western suppliers. "The market for cement plant optimisation is on the rise. FLSmidth already generates higher revenues from cement plant services than from equipment supply."
Matthias Mersmann of aixergee Process Optimisation GmbH next spoke about the possibility of the optimisation of complex systems using dynamic flow sheet simulations. "Overall plant optimisation takes into account all effects both up- and down-stream, avoids process limitations from consequent bottlenecks, requires integration of up- and down-stream equipment into the scope of consideration and requires a detailed look at the process." Mersmann suggested that a dynamic process simulation is required, taking into account that the process is "in sequence, recirculated and in parallel." Any kind of complex process unit can be split up into its process units, each of which can be interconnected to represent the complete process, for example using the Matlab flow sheet approach. Mersmann gave details of a case study where the challenge was to integrate an RDF dryer into a complex plant, while optimising the waste heat off-take and reintroduction points. The successful decision was one that did not overtax the existing fans in the plant, and this demonstrated the usefulness of the dynamic flow sheet approach.
Vincent Grosskopf of Coal Mill Safety Pte Ltd followed to discuss the optimisation of coal mill systems, and the avoidance of fires and explosions. He pointed out that fire and explosion protection starts in the coal storage yard, and continues through any pre-crusher system, onto the conveyor belt to the raw coal silo and on into the raw coal silo itself. Grosskopf pointed out that although individual pieces of equipment may have explosion protection, if they are connected to other pieces of equipment that are prone to explosion or fires, then they may be at risk of disastrous uncontrolled combustion propagation from elsewhere in the system. Explosion isolation or explosion decoupling must be provided as part of the system design, for example through the use of a double flap valve in a pulverised fuel silo baghouse funnel hopper.
In contrast to the first few presentations, the next speaker, Peter Dover of Cement Performance International Ltd, suggested that the key to process optimisation is in the development of cement plant control room operators. Dover suggested that the difference between an ordinary and a great operator is around 20% in terms of performance. A number of different ways can be used to help develop outstanding operators, including experience, advice from master operators, group sessions with peers and specialists, refresher courses and e-learning.
William Duchatelle of Total Lubrifiants next outlined a total cost of ownership (TCO) approach to cleaning of open gear drives in the cement industry. He pointed out that lubricants can reduce the cost of ownership of open gears by extending the lifespan of the equipment, by increasing the lifespan of spare parts, by reducing the number of shutdowns due to maintenance and repair operations and by reducing energy consumption. An oil monitoring programme provides information regarding the condition of the fluid and on the wear level of the equipment, and can aid in the anticipation of gear failures and for the preparation of early interventions. In addition, contamination of lubricants will lead to abrasive wear and will shorten equipment lifespan: filtration devices and cleaning agents can be used to handle oil contamination, although the root causes of contamination should be eliminated if possible. On the other hand, contamination of greases and viscous fluids is more difficult to deal with since the dust is incorporated into the product. In this case, the lubricant may need to be replaced and Duchatelle outlined Lubrilog's approach to this possibility, which uses a high pressure pump to clean gears with a special solvent - even during operation.
Richard Rogers and Klaus Holz of Fuchs Lubritech continued the theme of lubrication, concentrating on open gear lubrication using Ceplattyn, the first sprayable adhesive lubricant developed without using asphaltics and solvents. The lubricant is thixotropic and becomes solid when it does not move, meaning that if the gear is stopped, the lubricant becomes immobile on the gear and remains ready for start-up. At the same time, the lubricant is readily pumpable and sprayable.
At the start of the next session, on pyro-process optimisation, Felix Bartknecht of SICK and Sezin Arikan of Cimsa Cement spoke about the optimisation of clinker burning using advanced process gas monitoring systems. Bartknecht pointed out that the composition of processes gases can be used in many way to give feedback on the 'health' of the pyro-process, in order to make process changes. Arikan gave some details of a preheater blockage problem at her cement plant. All raw material and fuel compositions were collected, but there was no correlation between these and the blockages. A SICK analyser was used to detect SO2 levels in the process gas, and it was found that when SO2 levels in the gas were above 10,000ppm, there would be a preheater blockage within three days. A hole in the burner was found to be a major contributory factor in the problem, and after this was fixed the blockage problems were solved.
Dirk Schmidt of KIMA Echtzeitsysteme gave a presentation co-authored by the German VDZ, on kiln hot-spot treatment using IR-controlled water mist sprays for kiln shell cooling. Hot spots on the kiln shell may occur if there are localised refractory failures inside the kiln. A series of IR-pyrometers are used to measure the temperature and position of hot spots on the rotating kiln, and a logic controller is used to control a series of atomised water jets that only seek to cool the hot spots. Schmidt pointed out that only those hot spots that have a temperature of up to 500C should be treated using the system, since above that temperature the water would harm the micro-structure of steel. In the absence of a walkway that could be used to mount the system, a single steel tube can be rigged along the side of the kiln, which allows the system to be easily moved to the most effective place for hotspot treatment. A production manager at Leube Baustoffe was quoted as saying that due to the localised cooling of hotspots on the kiln shell, the plant was able to continue production at the full rate, all the way through to its scheduled annual maintenance. This active localised kiln shell cooling approach can also be used to promote the formation of thicker refractory coating inside the kiln.
Neil Taylor of Isaksson-Taylor next spoke on the 'missing link' of burning zone optimisation: nodulisation. Taylor pointed out that when a kiln is able to produce a uniform nodulisation of clinker, it is usually possible to push the kiln to much higher production rates of high quality clinker (MPa/tonnes). He suggested that kiln and cooler operation is most stable with clinker nodules between 3 - 20mm and minimal dust. Larger nodules are difficult to cool, while dust will obscure the kiln flame and smaller nodules will be blown around by process gases. Ideal nodulisation leads to optimum clinker distribution into the cooler, more uniform airflow through the cooler clinker bed, more effective cooling and heat recovery, stable secondary and tertiary air, and a stable flame and burning zone - all of which leads back to good nodulisation. Clinker nodulisation occurs after the meal components melt as they enter into the kiln, forming in a hot snowball fashion in the rotating kiln through an interaction with the melt-covered refractory coating. Optimising the conditions for alite growth in the nodules will lead to higher-strength cement. Factors that influence clinker nodulisation include flame characteristics, combustion conditions, fuel and ash characteristics, kiln speed and filling degree, volatile recirculation, the degree of calcination of the meal as it enters the kiln, the raw meal characteristics and the targets and controls that are applied to the kiln system.
Benjamin Berg of Loesche GmbH gave the final presentation of the first day, examining performance enhancements for vertical roller mills. Berg spoke about a wide variety of technology improvements that can be incorporated in both new equipment and also retrofitted to older equipment. Reduced specific energy consumption and improved production rates of 10% each can be foreseen, with a payback period of less than two years. Loesche also partners with Dalog to provide online VRM support, through vibration and torque monitoring at the gearbox and other process equipment.
The conference social evening took place on a pair of red London double-decker buses, which took in all of the city's most memorable tourist sights, including Buckingham Palace, Big Ben, the London Eye, Tower Bridge and St Paul's Cathedral.
Second day
At the start of the second day, Ulrich Mrowald of Claudius Peters Projects GmbH spoke about the optimisation of clinker coolers, in particular the ETA cooler. He suggested that coolers should achieve low clinker output temperatures, have minimum maintenance, high availability, maximum heat return to the kiln, trouble-free handling of fine clinker grains and fast cooling of the clinker down to 1200C to freeze the clinker mineralogy. The ETA cooler features a static inlet and separately moveable aerated lanes, along with independently-controlled side aeration to reduce 'red rivers.' The deep clinker bed of the ETA cooler leads to higher efficiency, but also higher specific electricity consumption. A flat cooler has a crusher at the end of the cooler, while a stage cooler has a roller crusher in the middle of the cooler at a step in the bed. Mid-cooler air extraction from a stage cooler can be used for waste heat recovery or for drying air. In the Duotherm process design, up to 100% of the cooler exhaust gases can be returned back to the cooler, meaning zero dust or other gaseous emissions from the cooler and also a higher potential energy content for waste heat recovery.
Menno Eisenga of Glass Service (GS) firstly explained that his company is known in the glass industry for furnace control, which has subsequently been used for kiln control in the cement industry. ENCI Maastricht decided to install GC's ESIII ('ES3') model-based predictive control system (MPC) to optimise its pyroprocess in 2008. The MPC uses a model of the system to predict what current inputs will do to the system and aims to change inputs to attain a future designated outcome. For example, the total heat input, combustion air input, raw material feed rate and kiln rotation rate might be altered to hit targets for kiln rotation power, the level of free lime, O2, CO2 and NOx levels, and flue gas temperatures in cyclones. Eisenga showed results that ESIII had achieved, stabilising kiln performance, reducing kiln cycling and ultimately achieving fully automatic kiln operation without operator intervention. The control system has also been used to control a slag dryer, where the slag output temperature under operator control was around 130C, but under ECIII control the temperature was 100C or less, allowing the saving of between 30-70% of the gas formerly used for drying.
Frank Lund and Mette Dobel of FLSmidth discussed high level process optimisation and quality control optimisation. Lund pointed out that the road to full automation starts with advanced instrumentation, and will finally lead to remote monitoring (and even, perhaps, to remote operation). He gave some details of a major contract from CRH, for optimisation using high level control of 40 mills and 12 kilns in seven countries on three continents. The FLS ProcessExpert System (PXP) uses a variety of approaches to process control, including model predictive control, fuzzy logic, intelligent process objects and dynamic decision trees, to create an 'open' control solution environment. The system has led to a 7.8% increase in output from a VRM, and a 41% decrease in fineness standard variation. Dobel presented a case study from the Lapeenranta plant of Finnsementti, where the customer was handicapped by the absence of an homogenising pile (due to the plant's location in an urban area). The plant instead uses the QCX/BlendExpert system which uses an online analysis of the composition of the material going into the raw mill to ensure a low standard deviation of either the LSF or C3A level of the product at the end of the kiln.
Olaf Michelswirth of Intercem Engineering then spoke about a kiln inlet seal system that was applied to a cement kiln in a 40-year old plant in central Africa, to avoid hot meal spillage and to avoid false air feed into the kiln. A 3D scanning system was used to determine the exact dimensions of the kiln inlet, while the kiln's 'idiosyncrasies' also had to be taken into account. A new spring-based kiln sealing system with a retention ring was installed under some local difficulties and in under eight days. The kiln inlet sealing system allowed the company to decommission a material handling system that had been installed under the kiln to handle previous fugitive dust.
Donald Cameron of Primasonics International presented a sonic device that 'works like a magic wand' to increase production. Acoustic horns can be manufactured to create sounds waves at different frequencies. An appropriate frequency horn should be selected to provide the maximum debonding effect to clean surfaces, and to eliminate bridging at the bottom of silos. The horns can also be used to reduce build-up on ID fans, on baghouse filters, in electrostatic precipitators, in selective catalytic reduction systems and in ducting.
Matthias Kalkert of KIMA Echtzeitsysteme talked about ball mill filling level measurement using structure-borne sound analysis and fuzzy control. A mill with not enough fill will allow balls to impact on each other creating a high-pitched sound, while an over-filled mill will create a low-frequency 'dull' sound. A microphone can be fixed to the ball mill shell (including for different chambers in the mill) for transmission to an off-mill receiving unit and the frequency spectrum of the mill sound can then be analysed. The analysis can also detect wear in the grinding balls or liners or the existence of any unexpected holes in the diaphragm. Calibration generally needs to be undertaken once per year. The fill level in the mill can subsequently be controlled and optimised by changing the rate of fresh feed input. Controlling the fill level leads to less wear of balls and liners, more homogeneous product quality and increased production.
The penultimate presentation at the conference was co-authored by Paul Flachskampf of Inform GmbH and Matt Barlow of Hanson UK, on centralised logistics planning and transportation optimisation. Flachskampf pointed out that transport is typically at least 20% of the cost of the final delivered cement, so that the potential for optimisation and cost-saving is substantial. Barlow gave details of the implementation of an Inform transportation optimisation system that was applied to the transport systems of Hanson UK. Disparate back office systems were initially standardised onto a SAP system, which was rolled out to all business locations. There is now a single customer contact system, with a centralised orders and despatch system. A GPS system is used to track all of the company's 1600 trucks, so that the company knows where its cement is located at all times, on its journey to the final customer. Barlow suggested that the transport and logistics process must be vigorously standardised, harmonised and optimised to drive value delivery and that this topic has multiple touch points on the concept of Industry 4.0 and the Internet of Things. He emphasised that safety is still of paramount importance in an optimised logistics system.
Martin Rooney of Helmke Orbis finished the conference with a presentation on the replacement of a CRH cement plant's 1.6MW mill drive slip-ring motor in northern Spain within two weeks of first failure alert. There was a space limitation at the site, and a non-standard foundation arrangement. All motor components were sourced from Helmke's existing stock, and the company was able to manufacture other components in-house. The two-week delivery time to the site saved 22 weeks compared to another motor fabrication option that was also considered.
At the end of the conference a number of awards were presented. Total Lubrifiants was awarded the prize for the best exhibition stand. In third place in the best presentation awards was Dirk Schmidt for his paper on hot spot cooling, while in second place was Neil Taylor for his paper on nodulisation. Donald Cameron won first prize for his paper on the use of acoustic horns for process improvement.
The conference was followed by an enjoyable field trip to Hanson's Ketton cement plant to see at first hand many instances of state-of-the-art process optimisation in the cement industry.
Although this was a fairly small conference, attendees praised the conference for its useful technical content, for its friendly and 'collegiate' atmosphere and for its many networking and business opportunities. The event is set to be repeated, with date and location to be confirmed.
Hanson Ketton cement plant (Field trip location in 2017)
The Ketton plant in Rutland is operated by Hanson, HeidelbergCement’s subsidiary in the UK. In operation since 1928, the plant has seen a total of eight kilns over the years. It currently operates Kiln 8, a 68m-long, 1.3Mt/yr capacity Polysius Dopol type 2442 kiln with a suspension pre-heater and AS precalciner. The plant was an early adopter of alternative fuels in the early 1990s. Today it uses a combination of paper/plastic waste, hazardous liquids, MBM and UK coal, with total thermal substitution by alternative fuels of around 65%.
The plant has invested heavily of late in environmental protection, packing equipment, a recent renovation of its vertical roller mill for raw meal and a solar plant that can supply up to a third of the plant’s electrical power during the summer months. Future investment in a new baghouse for the cooler will allow the ID fan to be upgraded, taking the kilns’ clinker capacity from 2750t/day to 3000t/day. It also plans major expansion of its quarry in the coming decades.
