3rd Global CemPower Conference and Exhibition 2015
1 - 2 June 2015, London, UK
The 3rd Global CemPower Conference on electricity issues in the global cement industry has successfully taken place in London on 1-2 June, with delegates from 18 countries and representatives of over half a billion tonnes of cement production capacity in attendance.
The Global CemPower Conference is unique in cement industry meetings worldwide in that it concentrates on the latest trends in power economics for the industry, including the use of waste heat recovery, electrical energy efficiency measures, grinding efficiency, alternative power sources and captive power generation. Delegates rated the conference very highly for its technical content and its usefulness for making contacts.
Amy Saunders, deputy editor of Global Cement Magazine, started the conference by giving a review of the top cement producers around the world. Growth mainly stems from developing countries, with Sudan, Peru, Kazakhstan and Estonia leading growth rates over the period 2000-2012. China has slowed to a GDP growth rate of around 6%, with central and regional governments starting to eliminate excess cement capacity (although discussions with other delegates suggested that growth in China is ‘flat’ - already at 0%). A ban on 32.5 grade cement, new emission standards and a new carbon trading scheme will also bring major change to China. Amy pointed out that cement import/dumping ‘wars’ are likely to become more common as many more countries move into excess supply situations. The Middle East shows a robust level of growth at nearly 4%/yr, but faces major and multiple instability issues. Very strong growth is evident in sub-Saharan Africa, with capacity additions becoming the norm as populations grow and economies become more developed. Europe is coming out of a decade-long slump, but a Grexit could create a major bump in the road. North America shows robust growth, albeit from the bottom of the Great Recession, while central and South America show robust but patchy growth (with Brazil currently performing underwhelmingly).
Amy stated that Anhui Conch of China was the world’s largest cement producer in 2014, with directly-owned production capacity of 240Mt/yr and with waste heat recovery (WHR) units on all of its cement plants. The second largest company was Holcim, with around 180Mt/yr of cement production capacity and the third largest was Lafarge with around 170Mt/yr: When combined, the two companies will become the largest in the world. CNBM/Sinoma operates around 160Mt/yr of cement production capacity directly, but operates up to around 400Mt/yr of production capacity through wholly- or partly-owned subsidiaries, which with different counting methods would make it the largest cement producer in the world, larger even than the merged LafargeHolcim. Cemex, Italcementi, Taiwan Cement, China Resources and Buzzi Unicem round out the rest of the world’s top 10 cement producing companies.
Peter Edwards, editor of Global Cement Magazine, next gave a presentation outlining the implications of the Lafarge-Holcim merger, based on a new Global Cement report. On 7 April 2014 the two companies announced that they would merge, and shortly after gave a list of pre-emptive divestments in order not to incur the wrath of competition authorities around the world. CRH has been lined-up to buy the majority of the divested assets, which are largely in Europe. The two companies had a slight divergence of fortunes, which has led to a renegotiation of the merger terms, meaning that Holcim will take a little more of the combined company than Lafarge: Eric Olsen of Lafarge has been confirmed as the new CEO. The merger has the overall effect of allowing the combined company to optimise its geographic footprint, will allow it to become the largest producer in the US and to own 170Mt/yr of capacity in fast-growing Asia. It will have 340Mt/yr of capacity in 62 mainly developing countries. Peter concluded though, that “Merging could be the easy part.”
Jessica Kuhnert of the Clausthal University of Technology next gave an overview of energy generation for cement production. The energy consumption per tonne of clinker is ‘no longer reducible’ as long as cement remains based on the calcium system, since technology has advanced so that the actual specific energy consumption is close to the theoretical consumption. Jessica suggested that, alongside the reduction of energy and fuel costs, new process designs for combined heat exchange and dust recovery should be considered. A greenfield plant may be able to recovery 40kWh/t clinker of WHR power, but in practice, the level comes in at around 25-30kWh/t. Jessica asked if a cyclone preheater is really necessary for the cement production process? A mooted ‘Low Profile Process’ would do away with the cyclone preheater, and a high-temperature ‘dust separator’ would be used as a core interfacing element instead: The cleaned exhaust gas at 750°C would then be used in a waste heat boiler. Through this approach, up to around 85kWh/t could be produced. Jessica promised to tell delegates more when the applied-for patents have been granted.
Petr Rayman of Rayman Ltd of the Czech Republic next spoke about energy-saving innovations for pneumatic conveying. He first pointed out that the variety of feeder types used in the cement industry have their own advantages and disadvantages, with no one solution being ‘the best:’ Each approach must be chosen for the specific situation. In a pneumatic system, every part of the system has its own inner energy loss and the focus for development must be to reduce this loss. For example in a vessel feeder, there is an energy loss when the vessel is de-aerated to atmospheric pressure at the end of each conveying cycle, with the loss equal to around 10-20% of the total conveying air energy. In a rotary feeder, the energy loss comes from pressurised air leaking through the feeder, via the spaces between the body and the rotor and via empty rotor pockets, as well as the energy required to drive the rotor, totalling around 10-25% of system total required energy. In a screw feeder, the energy loss comes from the energy required to drive the screw and to drive the material through the feeder and can be 40-55% of total required energy. A Venturi feeder may have an energy loss of 50-65% of system energy requirement. Petr suggested that a gravity-based flow feeder has less than 1% energy loss. Petr compared two systems, one a vessel feeder and one a flow feeder, in a Czech power plant, both conveying the same material over the same distance, and found that the specific energy consumption of the flow feeder was approximately half that of the vessel feeder.
Alexander Sharabaroff of the International Finance Corporation started off the event’s main session, on waste heat recovery (WHR), by speaking on financing options and cement market analysis. The IFC is a major investor in the cement industry, helping to finance projects in many developing countries and able to finance projects in higher risk ‘frontier’ countries. “The recent financial crisis has put a strain on spending and the IFC proposes off-balance sheet structures to limit the financial impact of the financed project while accelerating sustainable development,” he stated. Alexander reported that the IFC has favoured the basic steam Rankine cycle as a WHR system, due to its relative simplicity and capital cost benefits. Access to a reliable electricity supply is worth paying for - and a WHR system can go some way to making a cement plant less reliant on an unreliable power supply. Alexander forecast that Chinese WHR unit equipment suppliers are likely to concentrate on projects outside of China, since WHR units are now ubiquitous in China and the market there is saturated. Installed capex costs range from US$1100/kW in China, up towards US$3000/kW in Europe and North America, with a payback time of 2-8 years, depending on the electricity tariff and with an IRR of 14-17%. Alexander gave an overview of the WHR potentials of a number of countries, based on electricity prices, political stability, market size and other factors. India has the most potential, followed (distantly) by Turkey, Vietnam, Mexico, Egypt, Thailand, Brazil and Pakistan. Alexander elucidated the off-balance sheet approach to financing, which has been popularised by cement companies having less robust finances, while at the same time wanting to de-risk their investments. For example, a new WHR unit might now be financed by the equipment supplier, backed by a heat supply agreement with the cement plant and an off-take agreement where the cement plant commits to purchase the generated power at a particular (discounted) cost.
Mr Ino Tatsuo of Anhui Conch Kawasaki (ACK) spoke about recent trends in WHR in Southeast Asia. The company can supply boiler and CK Mills as well as other cement manufacturing equipment. In total, the company (including Kawasaki Heavy Industries references) has 235 references in waste heat recovery, dating back to 1982 in Japan and back to the first WHR unit installed in China, back in 1998. The company also installed the first WHR units in India, Germany and in Vietnam. ACK also installed the world’s largest WHR unit, for Anhui Conch’s Wuhu cement plant in China, with a total capacity of 67MW, working on six large kilns. The company’s WHR units have an average availability of 97%, based on long-term stable operation. The PH boiler is installed next to the preheater tower, while the AQC (air quenching cooler) boiler is situated next to the cooler, with both boilers supplying steam to a central turbine. The condition of the dust in a PH boiler and an AQC boiler is different, so that they require different heat exchangers, boiler designs and dust handling systems. Mr Tatsuo mentioned that a WHR system can be applied to an alkali bypass line, just so long as the gas temperature is lower than the dust melting point. In addition, the exhaust gas from a gas engine can be used for WHR, if the plant is equipped with gas engine sets for captive power generation, for example, while a captive coal-fired boiler (CFB) may also be similarly equipped.
Sabrina Santarossa of Turboden next spoke about some of her company’s 35 years of experience in WHR. The company has 240 organic Rankine cycle (ORC) systems in operation, on biomass, geothermal, solar, waste to energy and industrial heat recovery, with units ranging from 2-15MW. In Turboden’s turbine applications, the heat transfer fluid is a thermal oil based on siloxanes, hydrocarbons or fluorinated fluids, each applicable to progressively lower temperature sources. Compared to a steam turbine, ORC has a small entropy drop, no need to superheat the steam, no risk of blade erosion and a non-oxidising working fluid, while system efficiency is still relatively high at partial loads. Sabrina mentioned the hybrid concentrated solar power plant at Italcementi’s Cimar plant in Morocco, which collects solar energy and which uses an ORC WHR plant for electricity generation. She pointed out that the reliability of the WHR plant depends on the reliability of all of the components of the system, including the cooling system (which might be affected by the quality of the cooling water). Communication between suppliers is crucial to a successful collaboration. Sabrina finally proposed a new scheme for the direct exchange of energy from the AQC hot air stream, doing away with an additional heat transfer loop, leading to greater net output and lower investment costs. However, there are some limitations: there may be several thermal power heat sources, which may be discontinuous and which would therefore complicate the process situation, while the ORC must be close to the heat source. Sabrina mentioned several references in other industries using this approach, although there are currently no references in the cement industry.
Pierre du Baret of Enertime next spoke about the benefits of using refrigerant-based ORCs for medium-to-low temperature exhaust gases in the cement industry. Pierre reminded delegates that there may be a 50°C drop in temperature from the heat source to the heat transfer loop temperature and there will then be another drop to the working fluid temperature. Thermal oils and flammable fluids have their advantages but also some disadvantages, including flammability, aging effects and larger pumps. “Regulatory and safety issues are not to be taken lightly,” stated Pierre, before suggesting the use of refrigerant-based fluids (RBFs) such as HFCs, HFO/HFE. RBFs have a high global warming potential, so that it is critical that systems are ‘air-tight’ - especially since the fluid might cost as much Euro24/kg and several tonnes of fluid would be used in each system. Pierre pointed out the importance of considering the net power production of a WHR unit, rather than just its gross production, since they may be different by 20-30%: the system itself has its own power requirements in terms of pumps, cooling and lubrication systems.
Donald Cameron of Primasonics International spoke about the use of pneumatically-operated sonic horns that produce low-frequency (60-420Hz) high-energy sound waves and which can be used to loosen particles such as soot or other build-ups from process vessels including the heat exchangers that are used in WHR units.
At the end of the first day of the conference, delegates enjoyed a dinner and drinks cruise along the quiet canals of north London on board an appropriately-powered electric narrow-boat.
Daniela Gewalt of Orcan started the second day of the conference, with a presentation on small cost-efficient ORC modules. A lean circuit structure and innovative control algorithm makes the HFC-based modules efficient, with each 2.3 x 1.4m ePack module producing 20kW gross. The system is designed to work on small scale energy sources, which typically show unpredictable and dynamic heat flows. The efficiency of the system is relatively low (<10%), but the system cost is also low. Ambient air is used as the heat sink. The ePack modules are ‘stackable,’ not on top of one another, but rather side by side, to work in parallel in order to cope with additional amounts of waste heat and/or power demands. This also means that there is multiple redundancy, depending on stacking architecture. For example, each ePack may have its own heat exchanger and separate intermediate circuits or there might be a common heat exchanger and a common intermediate circuit (or other architectures). The cost of electricity from the ePacks is comparable to grid-delivered brown coal-generated power, in the region of Euro0.05/kWh, although Daniela also suggested that the units can be effective down to electricity prices of 2 Euro cents/ kWh. IRR of 30% is possible, with a payback period of just over three years.
Darren Bryant of Heatcatcher spoke about approaches to mitigate the operational risk of ORC-based WHR systems. Darren spoke about a 0.5MWe ORC system that the company built for what is now Lhoist (and which was previously Steetly Dolomite) at the Thrislington lime works in the UK. Four 125kW containerised ORC generators with condensers were installed, producing 448kW (net). Electric fans are used for the air-cooled condensers, with lower power requirements. Gas comes to the heat exchanger after the EPS, so dust load is relatively low, although there are still issues with dust build-ups. Sonic horns were latterly applied to deal with dust issues, after a brush cleaning system became inoperable due to heat exchanger tube issues. Darren mentioned some other lessons learned from the project: On a preheater WHR system, the consistency of the dust can be crucial to project success or failure. The system must be 100% isolated from the process, while the boiler must be designed for minimal pressure drop. A hammering system is the most-used system for dealing with dust in the heat exchanger. With an AQC boiler, the dust is typically dry but abrasive, and the location of the WHR system take-off is critical, with come locations giving a 30% improvement in system capacity compared to others. Dust load from the cooler can be reduced with a gravitational de-duster or cyclone, but the pressure drop in the system must be minimised to reduce ‘parasitic’ energy losses. A cost of around Euro3m/MW was achieved with the system at Thrislington, but Darren said that lower costs must be achieved if these systems are to be widely adopted.
Antonio Mendes Nazare of Aqylon, a company that designs, manufactures and installs complete ORC solutions, for cement, steel and glass units, as well as for diesel, gas and biogas engine waste heat, next spoke about power purchase agreements (PPAs) as a means for financing WHR projects in the cement industry. Aqylon prefers to use hydrocarbons or siloxanes (toluenes, alkanes, MDM) as a working fluid, as opposed to refrigerants as a working fluid in its units. The company bases its ORC units on standard container dimensions, so that they are easily transportable worldwide, and are literally stackable. If the customer does not want to invest, for any reason, then Aqylon can offer a variety of financial models to finance the project. For example a special purpose vehicle (SPV) can be incorporated, potentially with the customer as a shareholder (or not), based on a power purchase agreement buying power at a lower price than from the grid. The price may be negotiated over the PPA, or may be indexed to the grid price and is usually 5-30% lower than the grid price. At the end of the PPA, there are three possibilities: that the PPA is not renewed and the equipment is taken back; that the PPA is renewed; or that there is a buy-back option so that the customer can purchase the equipment at an agreed price. Payback times on different projects dependent on local electricity prices.
Next, Min Wu of Nanjing Kesen Kenen Engineering Company, China, spoke about one example of the company’s over 220 WHR projects. The company has many references in building materials, but has also worked in iron and steel plants and on combined heat and power (CHP) plants. The majority of the company’s projects have been in China, but it has also undertaken 12 projects abroad, including five in India and three in Turkey. Min Wu gave details of NKK’s 8.5MW WHR project at Sharjah Cement Factory in the UAE, gathering heat from two production lines, using two AQC and two PH boilers, one 9MW turbo-generator set and three air-cooled condensers. The temperature at the boiler inlet ranges from 300-360°C. Water for the system’s operation comes from an on-site borehole. The steam-boilers utilise dual pressure systems which maximises the use of waste heat and provides an additional 5% power output compared to a single pressure system. Air-cooled condensers and closed-circuits were chosen to minimise the use of water in the system. Water at the site has high mineral content so a two-stage reverse osmosis system is used for water pre-treatment. All equipment for the system was manufacturer in China by a variety of different companies, including Hangzhou Boiler Group (which provided a single-cylinder, direct air-cooled condensing-type turbine), Quingdao Jineng Steam Turbine Group, the Nanyang Explosion Protection Group, Siemens China, ABB China and GEA China. Min Wu stated that the erection quality of the air-cooled condensers directly affects the vacuum quality during operation and this consequently affects power generation. The total EPC period for the project was just 15 months, and the project was commissioned in the first quarter of 2015, successfully passing all guarantee tests.
Dirk Schmidt of Promecon was the first speaker in the next session, which was on grinding efficiency and electrical energy efficiency optimisation. Dirk spoke about online control and optimisation of gas velocity profiles in vertical roller mill (VRM) operation, with the use of zero-drift Fourier transform analysis cross-correlated pairs of triboelectric-based gas velocity sensors. Dirk stated that the sensors can be used to calculate volumes, but this volume calculation must always be temperature-normalised. Dust must be present in the gas stream for the sensors to work, at a concentration range of 10mg-2000g/m3. Dirk suggested that the benefit of his company’s system for measuring gas velocities and volumes comes from its higher accuracies, compared to normal delta-P-based measurements, so that air-flow can be adjusted (downwards) to the minimum effective volumes, thereby saving substantially on fan electricity costs. Promecon sensors can also be used to detect air leakages in mill systems, which can help to optimise mill production capacity. The measurements can also be used as a prime input for the control strategy for a kiln ID fan, potentially leading to around 5% fan specific energy consumption reduction. Dirk concluded that the payback period for installation of the system is typically less than three months.
Matthias Dietrich of Sika Services AG next spoke about the use of grinding aids to reduce energy consumption in VRMs. Vertical roller mills require around 30% less energy than ball mills and 40% of all new mills are now VRMs. Matthias stated that cement producers are typically under pressure to produce high early strength cement, which implies higher cement surface area, while at the same time producing a relatively wide range of particle sizes to improve workability. This push towards finer grinding can lead to a higher specific grinding energy, but Sika offers VRM-specific grinding aids that can allow finer grinding with lower energy consumption. The residual charges on cement particles after grinding can lead to agglomeration, whereas grinding aids can reduce the polarity of the surfaces and the attraction forces of the particles, leading to the deagglomeration of the particles. The dispersion effect of the grinding aid reduces the circulating load of the mill, allowing the separator to work at higher efficiency, increasing grinding fineness and/or mill throughput. Grinding aids can also effectively reduce mill vibration levels. A different aid can be used to enhance subsequent cement strength, allowing a coarser grinding level to be applied, thereby reducing specific energy consumption. The latest grinding aids can reduce specific energy consumption by 15-20%.
Anil Parashar of Binani Cement, Dubai, spoke about grinding optimisation in a capex-constrained environment. Binani operates the largest grinding unit in the Gulf, and it will soon establish a greenfield integrated cement plant in Fujairah, partly in order to supply clinker to the grinding plant. The grinding plant has three ball mills with a total of 2Mt of grinding capacity, and around 40% of the material ground is ground granulated blast furnace slag (GGBFS). Two 70t/hr FLS mills have good performance, but the most recent 110t/hr Chinese-supplied mill has a number of operational issues. The grinding unit is partly constrained by power supply, so energy efficiency is crucial. Slag grinding has higher power demands than clinker grinding, while the moisture content of the raw materials must be low, since hot air drying has been deemed to be uneconomic. Anil stated that slag purchase costs have risen to levels that may not be economic in the future. Anil suggested that careful management of the grinding unit can result in energy efficiency, without significant capital expenditure. It was found that the Chinese mill could not be used at full capacity, and it was being considered to sell it, with a potential US$25m loss. However, with a realignment of power from one of the smaller mills to the largest mill, it has meant that the largest mill can now be operated at its maximum slag grinding capability, leading to higher efficiencies. However, at that point only two mills could be operated at any one time, again due to supply constraints. Capex required to add enough power from the grid to run all three at the same time would amount to $2m, while capex for a pre-grinder for the slag grinding mill would amount to around US$6.5m. However, with a further internal reorganisation of power allocations, the mills can effectively be operated at or near their full nominal capacity, at low capex cost compared to other solutions. Anil stated that future infrastructure developments in the Gulf will underpin cement demand, while regulatory change will promote the increased use of slag-based cements. Slag supply (currently from Japan) may then be the constraining factor on future production growth.
Frank Kassing of Santasalo Gears GmbH (previously known as Moventas and before that as Metso Gears) stated that the use of bevel-planetary gears can bring an energy efficiency advantage compared to use of bevel-helical gears. Internal losses in a helical gear unit amount to around 4.5%. However, the newest planetary gears have an internal loss of around 2.5%, leading to significant power and cooling requirement savings. The company has production facilities in Finland, Germany and in China and distributors worldwide. The energy-efficient bevel-planetary gear units can easily be retro-fitted in place of bevel-helical gears.
Jonathan Selwyn of Lark Energy brought the presentations to a close by speaking about a solar energy project built for Hanson Cement’s Ketton cement plant in the UK. Jonathan mentioned that the renewable energy scene in the UK has been very variable over the last few years, partly due to political changes, requiring some projects to be built from scratch in only eight weeks. However, despite some hurdles and reversals, the UK has become the largest solar power producer in Europe, with an installed capacity of 3GW. Jonathan stated that the installed cost of solar has dropped dramatically, due to huge economies of scale in PV panel manufacture in the Far East, so that solar is approaching or even dipping under the cost of generation from more traditional ‘fossil’ sources. Even Saudi Arabia is investing in solar generation, recognising the cost benefits over fossil fuel power generation. Lark Energy has been involved in progressively larger projects, including one with 33MW of generation capacity. Choosing the right location is the first and potentially most important decision, away from potential protesters, on low grade land and close to a grid connection. At Ketton, the 9MW solar array was built in a disused quarry and was funded by an investor through a power purchase agreement with Hanson. After the first phase, a further 4MW second phase was subsequently built. Solar panels tend to last for 30 years, while the inverters are the one part of the project that may need ongoing maintenance. The best way to maintain the site itself is to put a herd of sheep in place to keep the grass down, to ensure the panels are not overshadowed. The 75 acre solar plant, with 58,000 panels, supplies 15% of the energy requirement of the Ketton cement plant.
At the end of the conference the ‘best presentation’ awards were announced, based on delegate voting: In third place was Global Cement’s own Peter Edwards, while in second place was Dirk Schmidt of Promecon. However, in first place with an eloquent and realistic account of the practicalities of using ORC for WHR was Sabrina Santarossa of Turboden.
Delegates strongly praised the event for its high level of technical content as well as its usefulness for making contacts in the world of waste heat recovery, electrical energy efficiency, captive power generation and grinding optimisation. We look forward to seeing you at the 4th Global CemPower Conference!
What the delegates said:
• It has been very organised. Excellent conference
• Very well organised
• Nice conference, very friendly team
• Very well focused, great agenda, liked the networking opportunities
• Interesting conference, lots of good conversations
• Good organisation for networking
• I think it is very good, with a good range of topics
• Very enjoyable and I made some good contacts. Thank you!
• Congratulations to you and your team on a successful Global CemPower conference this past week! I enjoyed the wide variety of topics and made some good contacts at the event. Thank you for your efforts!