Cement factories are among the most energy-intensive industries due to the huge consumption of the clinker manufacturing process (3.2-6.3 GJton-1 ). In addition, the process is characterized by high energy losses since there are two sources of waste heat at high temperature. To improve the system overall efficiency and reduces its emission per ton of cement produced, in this work the authors evaluate the benefits of installing an organic Rankine cycle (ORC) unit adopting low GWP working fluids to recover the waste heat. To design and optimize the ORC cycle, a tool has been developed in MATLAB environment and linked with REFPROP and CoolProp databases. It permits to determine the most appropriate cycle configuration between two different options, and to select the working fluid among 12 low GWP organic media. Being the waste heat at relatively high-temperature values, multistage turbines are used, and a thermal loop is adopted between the waste heat fluxes and the organic fluid for safety reasons. The waste heat sources operating conditions are acquired during an experimental campaign conducted on an in-operation cement industry located in the North of Algeria. The two identified heat sources are recovered via an oil loop and used to feed the ORC. The thermodynamic optimization in terms of net power output is performed, while an economic analysis is carried out to verify the feasibility of the technology through the Algerian techno-economic conditions. The optimization outcomes reveal that the recuperative configuration using pentane as working fluids guarantees the best thermodynamic performance while isopentane and R1233zd(E) guarantee to achieve a net output power 2.1% and 4.6% lower than pentane. However, the economic analysis reveals that the ORC adopting R1233zd(E) ensures the best economic results. Thus, considering also the environmental and safety aspects, the choice fell on the recuperative configuration using R1233zd(E) as working medium which guarantees a net power output of 3.33 MW, a net present value of 6.39 M$, a payback time of 7 years and a higher environmental sustainability.
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Cement factories are among the most energy-intensive industries due to the huge consumption of the clinker manufacturing process (3.2-6.3 GJton-1 ). In addition, the process is characterized by high energy losses since there are two sources of waste heat at high temperature. To improve the system overall efficiency and reduces its emission per ton of cement produced, in this work the authors evaluate the benefits of installing an organic Rankine cycle (ORC) unit adopting low GWP working fluids t...
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