International Journal of Technology (2015) 6: 938-945 ISSN 2086-9614 © IJTech 2015 OPTIMIZATION OF ORGANIC RANKINE CYCLE WASTE HEAT RECOVERY FOR POWER GENERATION IN A CEMENT PLANT VIA RESPONSE SURFACE METHODOLOGY Hendi Riyanto 1* , Sigit Yoewono Martowibowo 1 1 Faculty of Mechanical and Aerospace Engineering, Institut Teknologi Bandung Jl. Ganesa 10, Bandung 40132, Indonesia (Received: June 2014 / Revised: August 2015 / Accepted: October 2015) ABSTRACT A cement plant that produces 8,300 tons per day releases 265,000 Nm 3 /h of flue gas at 360°C from its Suspension Preheater (SP) and 400,000 Nm 3 /h of hot air at 310°C from its air quenching cooler (AQC). It is imperative to recover the waste heat emitted by the plant for power generation, i.e., Waste Heat Recovery Power Generation (WHRPG). This paper aims to optimize waste heat recovery from the cement plant using Response Surface Methodology (RSM), for which an Organic Rankine Cycle (ORC) is applied for electric power generation. The working fluid of an ORC power generation system was selected among candidates of organic working fluids (i.e., isobutane, isopentane, benzene, and toluene) by using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), a Multi-Criteria Decision Analysis (MCDA) method. The ORC power generation system configuration and the corresponding operating conditions employing the selected working fluid (i.e., pressures and temperatures) are optimized by applying RSM. Based on TOPSIS evaluation and considering factors of health, safety, environment impacts, cost, and power generated, isopentane was selected as the working fluid for the ORC WHRPG, which was configured to consist of a boiler, two expansion turbines, a reheater, and a recuperator. Implementation of RSM attained optimum operating conditions of high pressure turbine, low pressure turbine, and condenser at 11.3 bar-a saturated vapor, 4.3 bar-a and 184°C, and 1.8 bar-a, respectively. Finally, the gross electric power generated of 5.7 MW at 12.5 percent of energy conversion efficiency is generated by the pertinent ORC WHRPG. Keywords: Cement plant; Optimization; RSM; ORC; TOPSIS; WHRPG 1. INTRODUCTION The energy consumption per capita per annum has been asserted by economists to be one of the prosperity indicators. Developed countries consume as much as 300 GJ of energy per capita per annum, whereas developing countries consume as little as one-eighth of that of developed countries (Anonymous, 2014). The discrepancy in energy consumption has led to a fierce competition in exploitation of energy resources. Accordingly, energy conversion efficiency improvement is deemed a prudent avenue worth of pursuing. A waste heat recovery system generating electrical power is essential to enhance the overall energy conversion efficiency. A cement plant releases waste heat from two sources, preheating * Corresponding author’s email: hendir@hotmail.com, Tel. +62-22-250-4243, Fax. +62-22-253-4099 Permalink/DOI: http://dx.doi.org/10.14716/ijtech.v6i6.1695