Session: 08-03: Solar Chemistry: Reforming, Base Chemical & Cement Production

Paper Number: 131097

131097 - Precalciner Geometry Optimization Considering a Co2 and H2o Heat Transfer Fluid for Cement Production. 

Abstract: 

Cement is a primary component of concrete and is consumed extensively for construction and transportation infrastructures worldwide. Conventional cement production contributes ~3 – 5% of global carbon dioxide (CO2) emissions [1] and ~8% of anthropogenic CO2 emissions [2]. About 60% of CO2 emissions results from the release of CO2 during calcination of calcium carbonate (CaCO3), ~30% results from burning of fossil fuels to supply heat for the highly endothermic reaction, and ~10% results from indirect energy needs (e.g., electricity and transportation) [2]. For decades, the raw material and high burn temperature (up to 1500 ℃) for production have not been changed to reduce the CO2 emission significantly. Synhelion has developed an absorbing-gas solar receiver which can provide 1500 °C heat to the process via an H₂O/CO₂ heat transfer fluid to provide fossil-free heating for the preheating and calcination stages. The introduction of this technology to commercial cement production plants has the ability to pave the way for the decarbonization of this industry. However, very little work has been done to investigate the viability of solar-heated H₂O and CO₂ gases to efficiently calcinate the cement raw meal relative to conventional gas-fired precalciners. A critical need exists to better understand the particle suspension, flow dynamics, heat transfer, and thermochemistry of the raw meal and calcination reaction when using H₂O and CO₂ gases, which have dramatically different thermophysical and radiative properties relative to fossil fuel air. Over 80% of the energy required for calcination and clinkerization is in the preheaters and precalciner [3]. The objective of this project is to investigate CaCO₃ decomposition utilizing the H₂O/CO₂ heat transfer fluid with a focus on the effect of the fluid’s 1) radiative properties given its high emissivity in the infrared spectrum, 2) catalytic effects on the CaCO₃ kinetics in the H₂O atmosphere, and 3) differing energy/volumetric density and viscosity. The presented study will focus on the precalciner portion of the systemin which the CaCO₃ is suspended in a dilute phase within the heat transfer fluid. The effectiveness of the heat transfer within the precalciner is influenced by the system geometry which has not been optimized for the properties of H₂O/CO₂. A CFD model, constructed in ANSYS Fluent, which includes the effects of radiation and atmosphere dependent material kinetics is used to determine the optimal precalciner geometry. The resulting geometry will be constructed in the coming year for model validation and on-sun testing with an integrated Synhelion receiver.

Presenting Author: Javier Martell Sandia National Laboratories

Presenting Author Biography: Mechanical engineer graduate student from the University of Texas at El Paso (UTEP) with a bachelor's in mechanical engineering and minor in Biomedical Engineering. Currently working for Sandia National Laboratories at the National Solar Thermal Test Facility (NSTTF). My research at the NSTTF relates to industrial decarbonization by assisting in various projects such as Thermal Energy Storage Systems, decarbonization of cement production among others.

Authors:

Javier Martell Sandia National Laboratories
Brantley Mills Sandia National Laboratories
Nathan Schroeder Sandia National Laboratories