Subhodeep Banerjee

Carbon Sequestration and Optimization of Enhanced Oil and Gas Recovery

There has been a strong emphasis on the development of safe and economical carbon capture, utilization, and storage (CCUS) technologies in recent years because of rising concerns about carbon dioxide (CO2) emissions from fossil fueled power plants. Two technologies that show promise for CCUS application are enhanced oil recovery (EOR) and enhanced gas recovery (EGR), where CO2 is used as a working fluid to extract oil and natural gas respectively from depleted reservoirs. Permanent carbon sequestration is achieved as a byproduct due to subsurface fluid losses throughout the life of the system. In this chapter, numerical simulations of subsurface flow in EOR are conducted using the multiphase flow solver COZSim. For EGR simulations, the TOUGH2 (Transport of Unsaturated Groundwater and Heat) code is employed. An optimization code based on a multi-objective genetic algorithm is combined with COZSim and TOUGH2 and modified for EOR and EGR application respectively. Using GA-COZSim and GA-TOUGH2, the CO2 injection rates are optimized for both constant mass and constant pressure injection scenarios to manage the production of methane or oil for EGR and EOR respectively to ensure high output for the entire life of the system thus allowing for more efficient use of CO2. The results of this study highlight the scope of EGR and EOR technologies along with CO2 sequestration for consideration of deployment on a commercial scale. This chapter presents a review of the authors’ previous work reported in the literature on EOR (Safi et al., Chem Eng Sci 144:30–38, 2016 [1]) and EGR (Biag et al., Energy 94:78–86, 2016 [2]) simulations and optimization.

Transient Cold Flow Simulation of Fast Fluidized Bed Fuel Reactors for Chemical Looping Combustion

Circulating fluidized bed (CFB) in chemical looping combustion (CLC) is a novel carbon capture technology which offers great advantage for high efficiency and low cost. To obtain a thorough understanding of the hydrodynamics behavior inside the reactors as well as CLC process, numerical simulations are conducted. Computational fluid dynamics (CFD) simulations are performed with dense discrete phase model (DDPM) to simulate the gas–solid interactions. CFD commercial software ANSYS Fluent is applied for the simulations. Two bed materials of different particle density and diameter, namely the molochite and Fe100, are used in studying the hydrodynamics and particle behavior in a fuel reactor corresponding to the experimental setup of Haider et al. at Cranfield University in U.K. Both the simulations reach satisfactory agreement with the experimental data concerning both the static pressure and volume fraction at various heights above the gas inlet inside the reactor. It is found that an appropriate drag law should be used in the simulation depending on the particle size and flow conditions to obtain accurate results. The simulations demonstrate the ability of CFD/DDPM to accurately capture the physics of CFB-based CLC process at pilot scale which can be extended to industrial-scale applications.

Numerical Simulation of Chemical Looping and Calcium Looping Combustion Processes for Carbon Capture

Efficient carbon capture and storage (CCS) technologies are needed to address the rising carbon emissions from power generation using fossil fuels that have been linked to global warming and climate change. Chemical looping combustion (CLC) is one such technology that has shown great promise due to its potential for high-purity carbon capture at low cost. Another CCS technology that has garnered interest in recent years is calcium looping (CaL), which utilizes calcium oxide and the carbonation-calcination equilibrium reactions to capture CO2 from the flue stream of fossil fuel power plants. Computational fluid dynamics (CFD) simulations of two CLC reactors are presented in this chapter, along with system level simulations of CaL for postcombustion carbon capture. CFD simulation of a CLC reactor based on a dual fluidized bed reactor is developed using the Eulerian approach to characterize the chemical reactions in the system. The solid phase consists of a Fe-based oxygen carrier while the gaseous fuel used is syngas. Later, the detailed hydrodynamics in a CLC system designed for solid coal fuel is presented based on a cold flow experimental setup at National Energy Technology Laboratory using the Lagrangian particle-tracking method. The process simulation of CaL using Aspen Plus shows an increasing marginal energy penalty associated with an increase in the CO2 capture efficiency, which suggests a limit on the maximum carbon capture efficiency in practical applications of CaL before the energy penalty becomes too large.

Process and Reactor Level Simulations of Coal-Direct Chemical-looping Combustion

Reducing carbon emissions from fossil-fueled power plants has been an active area of research in recent years. One technology that appears to be very promising for high-efficiency low-cost carbon capture is chemical-looping combustion (CLC) (Leion et al. 2009a). CLC involves combustion of fuels (either gas or solid) by heterogeneous chemical reactions with an oxygen carrier, usually a particulate metal oxide. Because of the absence of air in the fuel reactor, the combustion products are not diluted by other gases (e.g., N2), resulting in high purity of CO2 available at the fuel reactor outlet. Also, the net energy release from a CLC process is theoretically identical to that from conventional combustion of the fuel (Abad et al. 2012; Linderholm et al. 2013; Mattisson et al. 2009a). Research by Lyngfelt et al. (2001) has shown that the energy cost of solid circulation, which is the only energy cost of separation, is a very small percentage (approximately 0.3 %) of the total energy released by the combustion process compared to other pre-combustion technologies such as the oxy-fuel combustion in which the oxygen separation process consumes nearly 15 % of the electricity generation (Hong et al. 2009a, b). Therefore, CLC holds significant promise as a next-generation combustion technology due to its potential to allow zero CO2 emission with little effect on the efficiency of the power plant.