Perspectives and limits for cement kilns as a destination for RDF

Genon, Giuseppe; Brizio, Enrico

doi:10.1016/j.wasman.2007.10.022

Cited by 139 publications

(87 citation statements)

References 4 publications

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“…It consists of different kinds of materials such as paper, cardboard, wood, plastics, textiles and rubber as well as some inorganic materials. RDF is usually a quite inhomogeneous mixture and may have a high content of metallic components [4]. RDF is a partially CO2-neutral fuel as it contains both fossil and biogenic materials [8].…”

Section: Rdf In the Cement Industrymentioning

confidence: 99%

Substitution of Coal by Refuse Derived Fuels (Rdf) in the Precalciner of a Cement Kiln System

Kahawalage¹,

Melaaen²,

Tokheim³

2017

WIT Transactions on Ecology and the Environment

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Cement manufacturing is an energy intensive process where coal is the main energy source. Replacement of coal with refuse derived fuels (RDF) will reduce costs and CO2 emissions as RDF is partly carbon neutral. In modern cement kilns, most of the calcination (CaCO3(s)  CaO(s) + CO2) is carried out in the precalciner, and the process conditions there make it a good reactor for combustion of alternative fuels like RDF. However, most waste-derived fuels have a poorer quality than coal, and this could negatively affect the process. In this study, a model of the calcination and fuel combustion in the precalciner has been developed, and different fuel input cases have been simulated. The results indicate that it is feasible to use RDF to fully replace coal as an energy source in the precalciner. However, to obtain the same degree of calcination, the specific energy consumption will increase by 10% compared to coal if the RDF moisture content is 25% (a quite typical value). This is due to the fuel characteristics. As a result of the increased energy consumption, the exhaust gas flow rate also increases. Using RDF with 25% moisture content increases the exhaust gas volume flow rate from the kiln system by 11%. This is equivalent to a reduction in the production capacity. Considering that waste fuels like RDF are usually less expensive than coal, operating a precalciner with RDF as a coal replacement becomes a trade-off between lower fuel costs and lower production capacity.

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Section: Rdf In the Cement Industrymentioning

confidence: 99%

Substitution of Coal by Refuse Derived Fuels (Rdf) in the Precalciner of a Cement Kiln System

Kahawalage¹,

Melaaen²,

Tokheim³

2017

WIT Transactions on Ecology and the Environment

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“…Waste co-processing has been practiced for more than 20 years, especially in developed countries/regions such as Europe, Japan, the United States, and Canada (GTZ/Holcim 2006; Genon and Brizio 2008). Figure 3 shows the quantities of waste co-processed in the European cement industry in , alternative fuels other than scrap tires and solvents (e.g., MSW and sewage sludge) collectively represented about 2.5 percent of the total energy input to U.S. cement kilns (EPA, 2008).…”

Section: Co-processing Of Msw and Sewage Sludge In The Cement Industrymentioning

confidence: 99%

International Best Practices for Pre-Processing and Co-Processing Municipal Solid Waste and Sewage Sludge in the Cement Industry

Hasanbeigi¹

2012

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Co-processing municipal solid waste (MSW) and sewage sludge in cement kilns can both reduce the cement industry's growing fossil fuel use and carbon dioxide (CO 2 ) emissions and help address the increasing need for safe and environmentally sensitive municipal waste treatment and disposal.The cement industry accounts for approximately 5 percent of current anthropogenic CO 2 emissions worldwide. Given increasing cement demand and production, the industry's absolute energy use and CO 2 emissions will continue to grow. Cement kilns typically burn fossil fuels, which are nonrenewable and being depleted rapidly. Treating wastes in cement kilns, known as co-processing, can reduce the industry's reliance on fossil fuels and decrease associated CO 2 emissions. The ashes from waste co-processing will be integrated into the clinker which can result in saving the virgin raw materials. In addition, treating wastes in cement production can help alleviate the problems associated with the increase in waste generation around the world, especially in developing countries experiencing rapid urbanization. Municipalities and governments in many urban areas, especially those with underdeveloped waste management systems, face growing difficulties disposing of MSW and sewage sludge in a manner that protects human and environmental health.The high temperatures and sufficiently long residence time in cement kilns and other characteristics of cement production make co-processing of waste materials a viable strategy. Wastes have been co-processed in cement kilns for more than 20 years, and this practice is prevalent in some developed countries such as the United States and Japan, as well as in a number of countries in the European Union. Many developing countries such as China and nations in Southeast Asia are initiating programs to promote co-processing of wastes in the cement industry. Regulations, standards, and the technical infrastructure in these developing countries are less mature than in countries that have a long experience with co-processing waste in the cement industry.

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“…Some researchers have focused on emissions and pollution due to alternative fuel combustion in cement kilns [2]- [4]. Impacts in the product and the process have also been investigated by some authors.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Model for Alternative Fuel Combustion in a Rotary Cement Kiln Burner

Ariyaratne¹,

Manjula²,

Melaaen³

et al. 2014

IJMO

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Abstract-Increased use of alternative fuels in cement kilns is a trend in the world. However, replacing fossil fuels like coal with different alternative fuels will give various impacts on the overall kiln process due to the inherent fuel characteristics. Hence, it is important to know to what extent the fossil fuels can be replaced by different alternative fuels without severely changing process conditions, product quality or emissions. In the present study, a mathematical model based on a mass and energy balance for the combustion of different alternative fuels in a cement rotary kiln was developed. First, the impact of different fuel characteristics on kiln gas temperature, kiln gas flow rate and air requirement were observed by using coal (reference case), meat and bone meal (MBM), two different wood types, refuse derived fuel (RDF) and a mixture of saw dust and solid hazardous waste as the primary fuel. It was found that the key process parameters depend largely on the chemical characteristics of the fuel. It appears that MBM shows quite different results from other alternative fuels investigated. Next, simulation of combustion of a mixture of coal and MBM in the rotary kiln burner was carried out in three steps in order to find the reduction in production capacity compared to the reference case. Around 9% of reduction in clinker production rate could be observed when replacing 59% of the coal energy input. Results from a full-scale test using the same mixture of coal and MBM verified the simulation results.Index Terms-Air requirement, alternative fuels, production capacity, rotary cement kiln burner.

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Perspectives and limits for cement kilns as a destination for RDF

Cited by 139 publications

References 4 publications

Substitution of Coal by Refuse Derived Fuels (Rdf) in the Precalciner of a Cement Kiln System

Substitution of Coal by Refuse Derived Fuels (Rdf) in the Precalciner of a Cement Kiln System

International Best Practices for Pre-Processing and Co-Processing Municipal Solid Waste and Sewage Sludge in the Cement Industry

Mathematical Model for Alternative Fuel Combustion in a Rotary Cement Kiln Burner

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