Application of Liquid and Gaseous CO_2 in Enhancing Coal and Biomass Gasification and Energy Recovery; Use in Distributed Power Systems

摘要

Application of biomass as a renewable energy source is an essential element in the transition to a more sustainable society. Since biomass fuels are globally available and do not have the intermittency associated with wind and photovoltaics, and they constitute nearly one-quarter of the fuel available from municipal solid waste, the thermal processing of biomass offers the potential to transition from a fossil-fuel driven global economy. Carbon dioxide emissions from using biomass as a fuel are considered to be neutral because this carbon dioxide is fixed by photosynthesis in a relatively short period. The environmental objectives of any gasification system include meeting present emissions and/or future emissions standards on NOx, SOx, particulates, and trace metals, and can include CO_2 capture. The use of CO_2 in EOR can help to reduce carbon footprints as well as significantly improving the flow characteristics and yield of heavy oil. For enhanced oil recovery applications it is important to control the viscosity of the crude oil. In the program presented here, measurements of the effect of gaseous injection on oil viscosities are presented and analyzed. In gasification applications the use of liquid CO_2 as the suspension carrier can improve the cold gas efficiencies considerably because the water vaporization is reduced and more solid feedstock can be carried per unit mass of slurry. A thorough analysis of this aspect of liquid CO_2 is presented with data and analyses. In addition there is a good possibility that LCO_2/proppant slurries (LCO_2P) can be utilized in fracking applications, thereby reducing use of scarce water resources. The development of small scale distributed power generating systems which can be placed at various locations and can utilize CO_2 can enhance these applications. In this paper, the uses of captured CO_2 to enhance biomass and coal gasification as well as ancillary applications for enhanced oil recovery and LCO_2P for fracking applications are elaborated, and both data and simulations are presented in support of the applications of CO_2. In addition several types if distributed power systems are discussed including entrained flow and spouted bed reactors.