CO2 reduction potentials by utilizing waste plastics in steel works

Abstract

Background, aim, and scope Feedstock recycling has received attention as an effective method to recycle waste plastics. However, estimating the reduction potential by life cycle assessment using coke oven and blast furnace in steel works has been a challenging task due to the complex structure of energy flow in steel works. Municipal waste plastics consist of several plastic resins. Previous studies have generally disregarded the composition of waste plastics, which varies significantly depending on the geographical area. If the reduction potentials by using each plastic resin in steel works can be quantified, the potential of municipal waste plastics (mixtures of plastic resins) can be estimated by summing up the potential of each resin multiplied by the composition of each resin in municipal waste plastics. Therefore, the goal of this study is to investigate the reduction potentials of CO 2 emissions by using individual plastic resins (polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET)) and those for municipal waste plastics in the coke oven and blast furnace. Materials and methods A model was developed to clarify the energy flow in steel works. In order to estimate the changes in energy and material balance in coke ovens when waste plastics are charged, the equations to calculate the coke product yield, gas product yield, and oil product yields of each plastic resin were derived from previous studies. The Rist model was adopted to quantify the changes in the inputs and outputs when plastics were fed into a blast furnace. Then, a matrix calculation method was used to calculate the change in energy balance before and after plastics are fed into a coke oven. Results It was confirmed that product yields of municipal waste plastics (mixtures of plastic resins) could be estimated by summing up the product yield of each plastic resin multiplied by the composition of each resin in municipal waste plastics. In both cases of coke oven and blast furnace feedstock recycling, the reduction potential of CO 2 emissions varies significantly depending on the plastic resins. For example, in the case of coke oven chemical feedstock recycling, the reduction potential of PS and PP is larger than that of PE. On the other hand, in the case of blast furnace feedstock recycling, PE has the largest CO 2 emissions reduction potential, whereas the CO 2 emission reduction potential of PP is smaller than those of PE and PS. In both cases, PET has negative CO 2 emission reduction potentials, i.e., there is an increase of CO 2 emissions. In addition, the reduction potentials of CO 2 emissions are slightly different in each city. Discussions The differences in the reduction potentials of CO 2 emissions by coke oven chemical feedstock recycling of each plastic resin is attributable to the differences in calorific values and coke product yields of each plastic resin. On the other hand, the difference in the CO 2 emission reduction potential for each plastic resin in blast furnace feedstock recycling is att...

Simulation of blast furnace operation during the substitution of coke and pulverized coal with granulated waste plastic

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“…Prema Kjoto protokolu, smanjenje efekta staklene bašte, tj. emisije CO2 predstavlja jedan od glavnih zadataka industrije gvožđa i čelika [6].…”

“…Sekine i saradnici [6] su analizirali uticaj upotrebe otpadne plastike kao supstituenta za koks za visokopećni proces na emisiju CO2. Plastika koju su koristili u svojoj studiji je PE, PP, PS i PET.…”

Life Cycle Assessment Model for the Use of Alternative Resources in Ironmaking

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Wettability and interfacial phenomena investigations on high‐density polyethylene and petroleum coke

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