3rd Global Fuels Conference 2009
15-16 June, Toronto, Canada
The third Global Fuels Conference for cement and lime has successfully taken place in Toronto, Ontario, Canada, with 140 delegates attending from 23 countries. Information on best practice in alternative fuels use was exchanged, and a number of alternative fuels equipment vendors also exhibited at the event. The conference culminated with a field trip to the St Marys Bowmanville cement plant. The next Global Alternative Fuels conference will take place in Washington DC in the USA in May 2010.
After the traditional welcome cocktail reception, the conference started on the morning of Monday 15 June with an official welcome from Pierre Boucher, the CEO of the Cement Association of Canada (CAC). Pierre pointed out that Canada has eight cement companies operating 15 cement plants, with six in Ontario alone. Of the 14Mt of cement produced in recent years, around 4Mt would be shipped to the US. While Canada has an overall alternative fuel usage of around 9%, Quebec is most active in the area with a 29% thermal substitution rate (TSR). Producers in other Canadian provinces are very keen to use higher levels of alternative fuels (AF). Mr Boucher suggested that the conference offered “a great opportunity to raise awareness of AF.” He pointed out that AF comes in two main types: CO2 neutral (including wood, municipal solid waste (MSW) and biogas; and non-CO2 neutral, such as used oil, non-recyclable plastics and tyres (but see below). “When materials are processed properly, AF increase environmental performance without increased risk to human health: the CAC is working hard to enable further use of AF in the future.”
Authors from Marbek Consulting then spoke on their finding from a benchmarking study of energy use in the Canadian cement industry. Most plants were found to be operating efficiently, with one or two ‘stand-out’ plants, and a couple of plants that are still lagging behind (although they may be constrained by location and/or raw materials). The authors concluded that the main opportunities for energy efficiency are now likely to be found in the areas of raw materials and fuel preparation.
Rob Davies of Geocyle (Holcim’s global alternative fuels supply company, operating in 37 countries worldwide) next gave a fantastically detailed overview of AF markets and usage in the US. Geocycle operates in the ‘co-processing’ area, where energy and mineral components are recovered, where naturally-occurring materials are replaced and no new waste streams are created. Rather than speaking about WDF (waste-derived fuels) Rob preferred to speak about ‘engineered fuels’ which are highly specified fuels with a focus on quality control through tight control of inputs. Rob mentioned that there had been a complete collapse in the market for ‘recoverable’ waste, with waste that previously had been shipped to China now sitting stockpiled on ships that are now anchored outside various far-eastern ports, or being stockpiled in the US for having nowhere else to go to. Rob pointed out that AF use in the US is largely controlled by regional or state-wide landfill prices. For example, the nation’s most expensive landfill are found in New York, which means that alternative fuels are widely used – for example in a tyre-derived fuel (TDF) power plant in Connecticut. The cheapest landfilling costs are in the southeast, at around $15/t in Texas and Oklahoma – so that AF are used at lower levels in these areas. In general, all over the US, the use of hazardous waste has decreased, since haz-waste generation has decreased. Non haz-waste useage enjoyed double-digit annual increases between 1985 and 2005, but this is now expected to slow. Rob pointed out that 89% of non-haz-waste is sent to landfill, and that only 1% of the total is used in cement plants.
Rob futher pointed out that the gargantuan piles of tyres that used to exist are continuing to reduce as the cement industry (and other industries) progressively use them up for fuel (and for the production of crumb-rubber, a high-value material commonly used for sports surfaces). Once the tyre piles are exhausted (through what is essentially landfill mining) then demand (and prices) will have to be re-balanced with the new lower supply. Rob pointed out that auto-shredder residue (ASR) use is likely to increase, since the material has high calorific value (CV) and is likely to be available in quantities in the range of 5Mt/year. Around 2Mt/y of carpet residues are available each year (localised around carpet-producing states, mainly in Georgia), and although they can lead to increased in NOx, since carpet residues have high CV, their use is also likely to increase. Construction and demolition waste has a lower CV, but is available in very large tonnages. Around 40Mt of plastics is available each year, of which 12Mt is manufacturing waste. Rob pointed out that the non-recyclable portions of plastics waste streams make good AF.
In the US Geocycle typically blends 3-12 waste streams (but up to 550 at the Holly Hill AF facility) to produce an homogenous engineered fuel: this also allows the cement producer/AF fuel producer to be insulated from variations in the price of individual waste streams. Rob concluded with a glance towards the future. He suggested that forthcoming climate change legislation will impact on AF, particularly because the Obama administration is now fast-tracking CO2 emissions trading rules. Hazardous wastes can currently economically travel around 500 miles (compared to 100 miles for non-haz-waste), but new regulations make it easier to reuse ‘wastes’ locally, possibly making future supply much tighter (and more expensive).
Dirk Lechtenberg, the well-known AF expert and frequent contributor to Global Cement Magazine, next gave details of AF projects around the world, pointing out that his company, MVW Lechtenberg, applies the same European standards to its projects around the world. Dirk reiterated that it is important to open discussions with the public well before the establishment of a new AF project.
Wim Heldens of independent consultancy IC&C BV from the Netherlands next gave a presentation on ‘How to make money with alternative fuels.’ He suggested that new AF projects now show fuel costs of less than US$2/t of clinker, and that, although they can have good burning characteristics (quite apart from the economics of using them), operators “have to like to work with AF” for projects to become successful.
Global Fuels conference stalwart Tom Lowes next spoke about low risk routes to success. He started by saying that in a market downturn, “the lowest cost producer is king.” Since fuel cost is the major variable cost in cement production, AF use is a ‘no-brainer.’ Using sophisticated computer models, Tom was able to give a number of examples where stratification (non-mixing of fuel and combustion gases) was taking place in both kilns and calciners. Tom suggested that it is not sensible to build a big calciner without looking at the ‘engine’ – the momentum and mixing effect from the burner, and he suggested that jet mixing (not turbulent mixing) is the key to increased AF use.
In a fascinating paper, Mauricio Larenas of Beta Analytical spoke on the determination of the biogenic fraction of AF through analysis of C12/C14 ratios. When cosmic rays strike N14 in the atmosphere, they create radiocarbon C14 which oxidises to become C14O2. The radiocarbon has a half life of 5730 years, decaying to C12, so that any C14 incorporated into biological material when it grows is practically all gone after 50,000 years. This is the basis of radio-carbon dating (where measuring the ratio of C12 to C14 in a biological sample gives the age), but for alternative fuels this also allows a determination of the proportion of fossil (or fossil-derived) C12 compared to non-fossil (ie biomass) C14. Mauricio pointed out that the determination of fossil versus non-fossil fuels in a cement plant is currently a very long process, involving complicated sorting, cutting and weighing, which is also labour intensive and relatively inaccurate. By measuring the C12/C14 ratio in stack gases (for example by taking a gas sample every hour for 24 hours, using a gas bag and according to ASTM D7459), the overall fossil/non-fossil ratio of fuel inputs can be determined (using the ASTM D6866 standard and technology which has now been used for over 60 years). The technique can also be applied to individual solid samples, and has also been applied to determine the biogenic/fossil hydrocarbon ratio of tyres. These measurements are critical in optimising the economic benefit of emissions credits.
Ted Reese of Cadence Environmental Energy next gave details on technology that his company has applied to Kirchdorfer Zement in Austria, but which could potentially have widespread application in cement plants around the world. Reflecting Tom Lowes’ paper on the importance of mixing in correct fuel combustion, Ted detailed the Mixing Energy Technology applied to the 1000t/d plant. Kirchdorfer wanted to increase AF use from 35% to 50% TSR, without an increase in CO emissions. The company’s solution was to inject high pressure air through paired nozzles in the sides of the precalciner, which destratified the gas, meal and fuel in the calciner, in order to accelerate mixing and burning, and to bring O2 into contact with CO to reduce CO emissions. Cadence used a rented compressor, a flexible hose and simple injector nozzles and, after having tested multiple injection locations, provided a 3% production increase, decreased CO production, increased AF use, decreased coal use and decreased requirement for SNCR with concomitant reagent saving, all at very low capital expenditure.
In the penultimate paper of the day, Rahim Vaseghi of the Islamic Azad University, Iran, explained why Iran, although it is the world’s second largest crude oil exporter, imports 40% of its internal demand for petroleum products because of its lack of adequate refining capacity. Despite the fact that it has to import petroleum products, the Iranian government heavily subsidises the cost, so that the cost of the 4Gj of energy required to produce a tonne of clinker might be $20-30/t in developed countries, or $10-15/t in other oil-producing GCC countries, but in Iran a cement producer would pay only $3-4/t. Unsurprisingly, energy conservation measures are not a priority in Iran, even though simple measures could save US$120m in thermal energy costs and US$100m in electrical energy costs.
The last paper of the day was given by Luc Rieffel of ATS/WMH, who spoke about his company’s AF handling and dosing capabilities.
Gala Dinner and Global Fuels Awards
Many of the conference delegates elected to participate in a uniquely Canadian gala dinner, taking the ferry to Toronto Island for a barbeque on the patio of an island restaurant and then decamping to a bonfire on a beach with a fabulous view towards the Toronto skyline for toasted marshmallows, beer and campfire songs (and one or two mosquitos).
However, before the end of the evening, the Global Fuels Awards were presented. Geocycle’s Holly Hill facility was awarded the ‘Outstanding alternative fuels project of the year’ award, while Lindner Recyclingtech was awarded the ‘Most innovative technology for alternative fuels’ for its comprehensive range of recycling solutions. California Portland Cement’s Mojave plant was awarded the ‘Outstanding electrical energy efficiency project’ award for the on-going work at the plant (see the June 2009 issue of Global Cement Magazine), while Airstream Fans was awarded the ‘Most innovative technology for electrical energy efficiency’ award for its new fan technology, as applied in recent projects for Titan Cement.
A highlight of the evening was the presentation of the ‘Global Fuels Personality of the Year’ award, to Eric Hansen. Eric is well known in the cement industry around the world for his expertise in combustion and for his many years of service with Cadence. His gentlemanly, gracious and easy manner have endeared him to co-workers and customers alike during his nearly 40 years in the cement industry, and although he now only works half time (“12 hours a day, seven days a week” he says) his is a reassuring presence in the industry: long may it continue.
Second Day
The second day of the conference started with a trio of papers given by cement producers: Holcim, St Marys (owned by Votorantim) and Lafarge. Luc Robitaille of Holcim Canada (the newly-renamed St Lawrence Cement) spoke about his company’s experiences with burning AF at the Joliette plant in Quebec, which operates four long dry kilns. As well as tyres, treated wood and tyre-fluff, the plant burns materials from 100 different suppliers and has invested over Can$20m in AF facilities. The plant uses a Cadence Feed-fork whole tyre mid-kiln feeding system, which led to a reduction in NOx and CO emissions. The plant also uses granular fuels such as sewage sludge and wood dust, alongside shredded telegraph poles and railroad ties, and waste oils and recycled liquid fuels. The plant also uses a mass balance simulator which can help it to forecast emissions from burning particular wastes or combinations of wastes. Luc emphasised that a ‘Citizen’s Committee’ is an extremely useful forum to help in community communication, and concluded that the use of AF at the plant was aided immensely by the positive stance of the Quebec government, which sometimes means that permits to use new fuels will be provided ‘within days’ of application.
Martin Vreogh’s paper on AF use at St Marys Cement (in Ontario) detailed the targets that the company wanted to achieve through its use of AF: to use at least 30% AF TSR, to overcome political and public concerns, to gain permitting, to use socially-acceptable fuels (not recyclables), to maintain the good image of the company, to ensure an economic outcome of the project, to develop long-term mutually-benefical relationships with suppliers and to have no negative effects on cement quality. To do this, it became clear that the company had to know the law, to identify key stakeholders and develop a dialogue with them, to find partner groups, to explore the technical limits of its process, to organise supply chains, processing and logistics, to develop budgets and to use demonstration projects (such as the four day burn at the St Marys plant and a 28 day burn at Bowmanville) to persuade the Federal, Provincial and Municipal governments to allow it to gain the permits required. It was pointed out that to entertain the use of AF, the plant has to be well within the legal limits on all emissions before any testing takes place. At the start of the process of trying to obtain permits for the use of AF, St Marys had envisaged having to pass through 40 permitting tasks: the list is now up to 140 tasks, and permits are still at least some months away from being awarded. Through the first two papers of the day, it became clear that the differing regulatory framework and approaches of the Provincial governments in Canada can have a profound influence on progress towards the use of AF (and away from fossil fuels).
The third cement producer paper of the morning was given by Rob Cumming of Lafarge’s Bath plant, on the company’s project to grow CO2 neutral biomass on its own land (or on the shallow-soiled, rocky and marginal farmland of nearby farmers). Rob suggested that biomass produced in this way has the potential to be the next cheapest fuel after coal. Rob said that Lafarge had looked at a number of sustainability criteria when assessing the project, including the carbon and water balance of the project, the effect on soil sustainability and possible carbon sequestration and the effect on wildlife habitats. Plants considered as biomass crops included sorghum, maize, miscanthus (a form of bamboo), switch grass, industrial hemp, willow and poplar. Challenges included cost, storage and processing (such as drying and densification of the fuel through briquetting or pelletisation). Torrefaction of biomass is a potential solution to some of these problems, since it produces a final fuel which behaves similarly to coal. Rob also mentioned some of the various technologies that can be used to increase plant yield (essentially by deferring the production of seed by the plant so that it continues to build biomass). Coal produces around 100kg CO2/Gj, while unoptimised biomass produces 8-15kg CO2/Gj. However, coal costs £3-4/Gj, while unoptimised biomass costs around $6/Gj (while higher-yielding varieties cost less). As Rob concluded, “The real challenge for alternative fuel is to be more economically viable than coal.”
Industry veteran George Venta next spoke on the effect of the use of AF on cement plant emissions, firstly pointing out that while eight out of 15 plants in Canada use AF, in America 64 out of 98 plants use AF, with most using only scrap tyres and with a low TSR. Contrasting the emissions data between Ontario (which does not yet use much AF) and Quebec (which does), George found that Quebec’s emissions per tonne of clinker produced were lower in every category except HCB (hexachlorobenzene), which was significantly higher. George’s overall conclusion was that burning AF does not lead to higher overall emissions.
Jonathon Forinton, speaking on behalf of Wilfried Zieri of A TEC, looked at the behaviour of trace elements in AF during combustion (see table), and mentioned that A TEC’s RSP combustion chamber, developed in cooperation with Taiheiyo Engineering of Japan, can achieve high levels of AF use, while producing less than 500mg/Nm3 of NOx, without SNCR.
Jennifer Anderson of PANalytical next spoke about the challenges of analysing clinker – “one of the most difficult materials to analyse.” Clinker has many phases with overlapping XRD peaks and with most phases having solid solution composition variations that makes peak matching even more difficult. The use of AF may make phase compositions and crystalinities even more variable and difficult to quantify. Jennifer stated that the Rietveld technique can provide precise answers but that they are not necessarily accurate – they need to be ‘referenced’ or ‘constrained.’
Geoffrey Conroy of Aumund spoke next on Aumund’s range of handling solutions for AF, including the Samson surface feeder – or Miracle Surface Feeder as Conroy cheekily put it. However, the advantages and features of the feeder are obvious, since it has low civil engineering requirements, robust construction and low maintenance and both storage capacity and basic dosing capabilities. Geoff mentioned one cement plant that loads its Samson feeder up with 120t of tyre chips once each shift, and just leaves it to convey (and dose) the chips to the system.
Michael Gramling of the MHC/WTW Group subsequently gave details of a cement plant project in Ireland that aimed at using 50% AF. Michael pointed out that 4t of fluff can substitute for 3t of coal, leading to a saving of at least $4.4m/year at the plant. This was achieved through saving the cost of the coal, the cost of the treatment and preparation of the coal and through earnings in the gate fee for the fluff. Michael claimed that the project in Ireland was on-budget, on-specification and on-time.
Bernd Neumann of Schenck pointed out that an effective air-lock is the key to successful gravimetric dosing and feeding – and if money is to be spent to improve a system for AF, it should be spent here. Schenck has produced a special belt-style weigh-feeder specifically for use with AF, featuring a low tare weight belt for use with low density AF such as rice husks and fluff.
Ricardo Costa gave the next paper – on firing petcoke into white cement kilns - co-authored with Adriano Greco, both of Greco, Brazil. Petcoke, they said, is now very commonly used throughout the Brazilian cement industry, so much so, in fact, that it cannot be considered to be an alternative fuel. To keep the cement as white as possible, a variety of contaminants have to be avoided, including Cr, Mn, Fe, Cu, Va, Ni and Ti. White cement also needs a final reducing zone in the kiln and subsequent fast cooling. The cooling is often accomplished by using water sprays, but this leads to the generation of large quantities of steam with can cause the elongation of the kiln flame. Ricardo suggested that the use of petcoke instead of more expensive coal for the production of white cement can cover the cost of the equipment needed for the changeover in less than three months.
Larry Farmer gave the final paper at the conference, and spoke on the benefits of using oxygen enhancement to increase the rate of AF use, and to widen the variety of AF that can be used. 1-3% enrichment of combustion gases can lead to large differences, with flame temperatures increasing by 50-100°C, increased available heat and heat transfer and higher combustion efficiency. Oxygen enhancement can reduce emissions of CO and THC, and can allow enhanced kiln control and faster recovery from temperature excursions. The increased stability of the kiln – particularly when using AF – can lead to increased production, more consistent quality and better refractory performance since with more stable operation the refractory bricks last longer. Larry claimed that payback for the capital equipment involved is in the order of 2-4 months. He then gave details of an oxygen enrichment project at Steetley Dolomite in the UK. The plant had started to use solvent-derived fuel, with a water content of up to 25%, which had a relatively low heating value and variable composition, co-fired with coal. With oxygen enhancement, production increased by 11.9%, specific emissions were down 9.3% and the plant regained the production it had lost from using AF. Larry Farmer quoted Sam Bainbridge, a process engineer at Steetley: “We have been able to increase production by 10%, taking us back to the performance we had before we started to use alternative fuels – but with extra cost savings of course. The kiln is now more stable and quicker to recover from operational disturbances.”
Farewell, Awards and Field Trip
At the farewell party at the end of the conference, Fives Pillard was awarded the prize for best exhibition stand. Both Mauricio Larenas of Beta Analytical and Larry Farmer of Air Products were commended on their presentations. Rob Cumming was third in the best presentations awards, with his paper on biomass farming at the Lafarge Bath cement plant. Luc Robitaille of Holcim Canada was second with his paper on the use of AF in Quebec, while Rob Davies of Geocycle was first, with his comprehensive and valuable study of AF use in the US.
The conference field trip visited St Marys Cement’s Bowmanville cement plant, 100km east of Toronto. The plant is currently applying for permits to burn AF, and hopes to be able to start its AF programme from 2009 onwards.
