Solar hybridization paths for cement production processes

Date

2023-6

Author

Polat, Onur

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The cement industry generates a significant portion of global CO2 emissions leading to global warming and climate change. A substantial portion of these emissions is due to the burning of fossil fuels to drive high-temperature calcination and sintering processes. In this work, the following possible solarization paths utilizing concentrating solar collectors were identified: (i) preheating the combustion air supplied to the rotary kiln and the calciner, and (ii) directly preheating the raw material mixture in a solar pre-calciner before feeding the mixture into the rotary kiln. A block-interaction model of a cement plant has been developed in MATLAB and verified by comparing the results with the energy audit from an existing cement plant. To compliment the plant model, a 1D model of the rotary kiln using the zone method and Monte-Carlo Ray Tracing in participating medium was coded. This model is used to calculate temperature profiles inside and outside the rotary kiln, predict the fuel consumption of the unit, and assess the effectiveness and realizability of applying a reflective coating on the kiln as a fuel-saving measure. In addition to that, the effects of wind velocity and rotation speed on convective heat losses from the rotating cavity type solar pre-calciner are assesed using the LES approach. Then, the plant model is used to assess the effects of possible solar hybridization paths and other energy-saving approaches. Afterwards, a novel optimization strategy to effectively utilize the heliostat field and the proposed hybridization paths in order to reduce the fuel consumption is developed. Finally, it is shown that significant global carbon dioxide emission savings can be achieved by considering the year-round solar resources in different locations around the world for implementing the proposed strategies.

Subject Keywords

Cement, CO2 Emissions, Fuel, Optimization, Concentrated solar thermal, Monte-Carlo, Zone method, LES, Rotating cavity receiver

URI

https://hdl.handle.net/11511/104458

Collections

Graduate School of Natural and Applied Sciences, Thesis