Possibilities of Using Post-Consumer Wood Waste as a Fuel in a Cement Plant

K e y w o r d s : Post-consumer wood waste; Fuel; Cement plant; Technical analysis; Elementary analysis. 4/2018 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 161 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T The Si les ian Univers i ty of Technology No. 4/2018 d o i : 1 0 . 2 1 3 0 7 / A C E E 2 0 1 8 0 6 2 M . K a j d a S z c z e ś n i a k , T . J . J a w o r s k i , A . W a j d a 162 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 4/2018 the Communication indicates that in justified cases thermal recovery may prove more beneficial than material recycling, taking into account, inter alia, economic or environmental effects. It should be emphasized that both the Communication and the CE strategy focus on existing plants for energy recovery [4-7]. 2. QUANTITATIVE RESOURCES OF ALTERNATIVE FUELS In 2014, conventional fossil fuels represented a 59% share in the European cement industry, while alternative fuels from waste accounted for 41%. According to the literature, it has been estimated that this sector can on average replace up to 60% of traditional waste fuels. As shown in the data from 2014, the use of fuels from the waste in cement plants is at various levels in the European Union. The top are such countries as Germany, the Czech Republic for which the share of energy from alternative fuels replacing conventional fuels in cement plants is above 60%, for Belgium and Poland it is above 50%. In turn, the lowest is in Greece with a share of less than 10% [4, 8]. The share of substitution of conventional fuels with alternative fuels from the waste in the cement industry in 1990 to 2016 in the world, Europe and Poland are shown in Fig. 2 [4]. Data from 2015 show that there are 13 cement plants in Poland. It should be mentioned that some of them obtain as much as 80% of the share of waste utilization in the total stream. The maximum use of waste contributes to reducing the need for additional investments related to the possibility of transforming waste into Energy [4, 6, 8]. In 2014, cement plants in Poland accepted 1372.9 thousand Mg of fuels from waste, including 1091 thousand Mg was RDF fuel (municipal waste fuel). According to estimates of the Association of Cement Producers, approximately 1.2 Figure 2. The share of substitution of conventional fuels with alternative fuels from the waste in the cement industry [4] Figure 1. Municipal waste management in the EU in 2016 [3] Table 1. Preferred parameters of an alternative fuel [9] Parameter Unit Value Moisture content % <20 Calorific value MJ/kg >15 Sulphur content % <1 P O S S I B I L I T I E S O F U S I N G P O S T C O N S U M E R W O O D W A S T E A S A F U E L I N A C E M E N T P L A N T E N V I R O N M E N T 4 /2018 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 163 million Mg of RDF type fuel is currently being developed. That is why solutions are needed to increase the use of fuels from waste generated in the recovery process. New customers of fuels could be modernized or newly created power plants and combined heat and power plants [4, 8]. 3. CHARACTERISTICS OF FUELS FROM WASTE Waste used as an alternative fuel must meet the quality criteria set [6, 9, 12]. The quality parameters of alternative fuels have a direct impact on the firing process as well as the quality of the clinker produced in the rotary kiln. The producer of fuel from waste is obliged to deliver to the cement plant a product that meets the requirements for alternative fuels by cement plants, and which have been determined by the Association of Cement Producers in 2008 – Table 1. The requirements of individual cement plants regarding the quality of waste fuels are slightly different. They concern the following parameters: moisture content, calorific value, chlorine and sulfur content, heavy metals content including mercury. The appropriate division is also required, the fuel fed to the calciner should have up to 30 mm granulation and the fuel delivered to the main furnace burner below 25 mm [6]. Table 2 shows how the requirements posed by cement plants changed over the years. In turn, Table 3 presents the requirements for fuels from waste, among others due to the presence of heavy metals. According to the literature [10, 11], the presence of potentially hazardous elements such as: As, Be, Co, Ni, Cd, Cu, Sn, in the environment not only influences the landscape but primarily affects organisms. In PN-EN 15359:2012 “Solid recovered fuels – Technical requirements and classes” CEN (European Committee for Standardization) has concluded the SRF (solid recovered fuels) classification system, Table 2. Exemplary requirements set by cement plants for alternative fuels [6] no requirements Requirements Unit Cement plants status for 2008 Cement plants status for 2015 Cement plants status for 2017 Bulk density [kg/m3] 150-200 Moisture content [%]mas. 15 18 20