Case Studies in Chemical and Environmental Engineering 4 (2021) 100138 Available online 4 October 2021 2666-0164/© 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Power generation in white cement plants from waste heat recovery using steam-organic combined Rankine cycle A.M. Khater a, * , Ahmed Soliman b , Tamer S. Ahmed b, c , Ibrahim M. Ismail b a Chemical Engineering Department, Faculty of Engineering and Technology, Badr University in cairo (BUC), Cairo, Egypt b Chemical Engineering Department, Faculty of Engineering, Cairo University Giza, 12613, Egypt c Environmental Engineering Program, Zewail City of Science and Technology, 6th of October City, Giza, 12578, Egypt A R T I C L E INFO Keywords: Waste heat recovery Energy effciency White cement industry Cascade Rankine cycle Organic Rankine cycle ABSTRACT Cement is one of the highly energy-intensive industries. Producing one ton of cement consumes 3-4-GJ which represent about 40% of the variable costs of cement production. Moreover, fuel cost represents 26–34% of production costs. Increasing energy effciency is essential in the cement industry, especially in the white cement production. The thermal energy consumption of the white cement production process is twice the average thermal consumption of grey cement manufacture. Improving energy effciency in the cement industry reduces CO 2 emissions in addition to reducing production costs. This study considered the recovery of waste heat in a white cement plant to improve its energy effciency. The conventional power generation cycles, i.e., steam Rankine cycle, organic Rankine cycle were studied as well as steam-organic combined Rankine cycle. Six different schemes were proposed for the different Rankine cycle systems. A comparative study was made to determine the optimum type of Rankine cycle, scheme, working fuid, and operating conditions based on both thermodynamic and economic evaluation. This research provides a general methodology to evaluate working fuids of different organic Rankine cycle systems to recover high-temperature waste heat. Isopentane and its different isomers -n-pentane, cyclopentane, spiropentane and neopentane-were selected as working fuids. Spi- ropentane produced the highest net power “4483 kWh” and the highest thermal effciency “41.69%”. Although spiropentane achieved the best performance, cyclopentane is recommended to be used as a working fuid due to its availability and relatively cheap price. It requires the lowest capital cost among the other working fuids. Moreover, it has achieved an irreversibility rate lower than spiropentane and its thermal effciency is lower than spiropentane by only 1.6%. Steam-organic combined Rankine cycle is the best choice for recovering high- temperature waste heat. it can generate larger amount of power than traditional steam Rankine cycle. More- over, it has lower capital cost than the steam Rankine cycle because it has been operating at lower pressures. 1. Introduction Energy consumption in Egypt has been tripled from 33 Mtoe 1 in 1990 to 92 Mtoe in 2020, while the amount of energy produced in Egypt decreased from 92 Mtoe in 2019 to 85 Mtoe in 2020. Carbon dioxide emissions in Egypt have been raised from 78 Mt CO 2 in 1990 to 225 Mt CO 2 in 2020 [1,2]. It can be noticed that there was a gap between energy production and consumption in 2020 estimated at about 8%. Improve- ments in energy effciency could help for reducing energy production cost and could also reduce CO 2 emissions. Energy effciency remains one of the most important issues of energy strategies, not only for economic reasons, but also for the environment [3,4]. Alternative energy resources have had great attention due to lack of conventional ones and to control CO 2 emissions and global warming. Waste heat recovery is one of the alternative energy resources. 1.1. Energy consumption and CO 2 emissions in cement industry Cement industry plays a vital role in Egyptian economy. Cement industry Participates by 3.7% in Egyptian GDP while it consumes about 5.3% of total energy in Egypt [5,6]. Egyptian production of cement has been increased from 24 million tons in 2000 to 50 million tons in 2020. Additional increase is expected in the future to meet the growing needs of infrastructure and construction projects prompted by the population rise [5]. Cement industry is an energy intensive industry with energy * Corresponding author. E-mail address: ali.khater@buc.edu.eg (A.M. Khater). 1 1 Mtoe = 11630 GWh Contents lists available at ScienceDirect Case Studies in Chemical and Environmental Engineering journal homepage: www.sciencedirect.com/journal/case-studies-in-chemical- and-environmental-engineering https://doi.org/10.1016/j.cscee.2021.100138 Received 9 August 2021; Received in revised form 19 September 2021; Accepted 23 September 2021