Waste heat recovery (WHR) in a cement plant using an organic Rankine cycle (ORC)

Abstract

En este proyecto se ha estudiado el aprovechamiento del calor residual en los gases de escape del horno de una cementera para producir energía eléctrica con un ciclo de Rankine orgánico (ORC). La energía se autoconsumirá, reduciendo la demanda de la red con el ahorro económico y de emisiones de alcance dos que ello supone. Se modelará y dimensionará el ORC, y se calculará la cobertura, el LCOE, los beneficios obtenidos y la reducción de emisiones. La mejor configuración para la fábrica genera 1,6 MWe, cubriendo un 25 % de la demanda anual de la planta con un LCOE de 63 e/MWhe. El proyecto reporta unas ganancias de 11 M e y un ahorro de 2255 toneladas de CO2 anuales. Existen otras configuraciones que generan hasta 6,1 MWe con el mismo LCOE y que permiten cubrir prácticamente toda la demanda de la fábrica. Sin embargo tienen ciertas desventajas que hacen que no sea una solución tan interesante para la cementera.

In this project, a waste heat recovery solution using an organic Rankine cycle (ORC) has been studied, where the energy source comes from the exhaust gases of a clinker kiln. This The electricity produced will be self-consumed by the factory, reducing costs due to lowered grid demand and cutting down scope 2 emissions of the cement production. The ORC will be modeled by its behaviour equations. A preliminary design of its components will be done, calculating the main dimensions of each one and the footprint of the installation. The energy supply will be analyzed besides the scope 2 emission reduc tion associated to the project. An economic study will been done, calculating the LCOE and the main indicators (NPV, IRR, PB). The best configuration for the cement plant generates 1.6 MWe, covering 25% of the annual electricity consumption of the factory with a 63 e/MWhe LCOE. The project NPV is 11 M e and saves of 2255 CO2 tons per year. There are other configurations possible for the ORC that generate up to 6.1 MWe with roughly the same LCOE and able to supply up to 95% of the demand. Despite those better results, certain drawbacks make these configurations not as interesting for the cement plant as the one selected.