Combination of passive and active enhancement methods for higher efficiency of waste-fired plants; flue gas and solar th
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TECHNICAL PAPER
Combination of passive and active enhancement methods for higher efficiency of waste‑fired plants; flue gas and solar thermal processing Abdulrahman A. Alrobaian1 Received: 10 July 2020 / Accepted: 17 October 2020 / Published online: 31 October 2020 © The Brazilian Society of Mechanical Sciences and Engineering 2020
Abstract This article presents a novel and applied solution for increasing the efficiency and cost-effectiveness of waste-fired power plants and comprehensively analyzes the proposal from thermodynamic, economic, and environmental aspects. The idea is centered around the simultaneous use of passive (flue gas condensation) and active (solar thermal heaters comprising evacuated tube collectors and parabolic trough collectors) for feedwater preheating. In this way, the extracted heat from the turbines for this purpose could be used directly for power generation, and thus, higher waste-to-power efficiency of the cycle. The proposed configuration and the base-case power plant are both simulated in TRNSYS software for dynamic modeling and comparison of the results over an entire year of operation of the power plants. For making the results more reliable for real-life operation conditions, the simulations are run for a real case study in Qassim city, Saudi Arabia. The results of exergy analysis show that the waste incinerator with the annual exergy destruction of 128.3 GWh is the main source of irreversibility in both models. The results further indicate that the proposed novel system is the more suitable option with 11.36 GWh and 68.18 GWh more annual produced electricity and heat, respectively. With these numbers, although the unit product cost of the proposed novel system is 2.2 $/MWh higher than the conventional plant due to the high cost of solar systems, the new system results in a 205.08 ton/GWh lower C O2 emission index which is extremely important and even of high economic value preventing large emission taxes. Keywords Flue gas recovery · Passive efficiency improvement · Solar heat · Active enhancement method · Technoeconomic analysis List of symbols c CHP product unit cost ($/GJ) Ċ Cost rate ($/h) Ė Electricity (kWh) Ėx Exergy rate (kWh) ir Interest rate LHV Lower heating value (kJ/kg) ṁ Mass flow rate (kg/s) P Pressure (kPa) Q̇ Heat rate (kWh) T Temperature (°C) Technical Editor: Ahmad Arabkoohsar. This article has been selected for a Topical Issue of this journal on Nanoparticles and Passive-Enhancement Methods in Energy. * Abdulrahman A. Alrobaian [email protected] 1
Mechanical Engineering Department, Qassim University, Buraydah, Saudi Arabia
V Volume (m3) x Extracted ratio of first preheating line y Extracted ratio of second preheating line Z Purchased cost ($) Ż Investment cost rate ($/hr Abbreviations CI CI COND COND CFWH CFWH CHP Combined heating and power CRF CRF D Destruction eco Economizer eva Evaporator ETC Evacuated tube collector HPT High-pressure turbine IPT Intermediate pressure turbine L Loss lm Logarithmic mean LPT Low-pressu
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