Supercritical CO2 Dewatering Enhanced by Cosolvent and Surfactant Formulations

A dewatering processes using supercritical CO2 (scCO2) with cosolvent and surfactant formulations is being developed to reduce the water content of coal and other porous materials. The high moisture level, poor mixing, and unsuitable heating rate reduce the efficiency of coal-fired power plants. Supercritical CO2, which has been shown to successfully remove water from coal by dissolution and displacement offers a possible economic solution in reducing moisture level and reducing the cost of utilization processes. The proposed program will develop and investigate cosolvent and surfactant formulations in scCO2 which increase water removal by dissolution by increasing the solubility of water in scCO2 and water removal by displacement by reducing the surface tension of capillary bound water in porous materials such as coal. Advanced Cooling Technologies, Inc. (ACT)’s innovative dewatering system designs aim to further enhance dewatering performance, thus, increasing the high heating value of coal and reducing the cost of utilization processes. The proposed new cosolvent and surfactant formulations and dewatering system designs are the key innovation that will increase performance of the water removal process. ACT, in collaboration with Lehigh University and Applied Separations, Inc., will design and fabricate a lab scale scCO2 system where the solubility of cosolvent and surfactant formulations will be measured and a scCO2-based coal dewatering process will be demonstrated. ACT will also work closely with our industrial partners to commercialize the technology. ACT will perform technoeconomic analysis comparing conventional dewatering techniques to the novel scCO2 dewatering process designed in Phase I with cosolvent and surfactant formulations. Parametric studies will be performed to investigate the economics of the novel scCO2-based dewatering process with respect to CO2 supply state, CO2 price, and coal throughput. A lab scale scCO2-based coal dewatering system will be designed and fabricated at ACT and tested to demonstrate and quantify water removal. Coal samples will be analyzed to quantify water removal and higher heating value, and the aqueous vessel effluent stream will be screened to detect any other valuable species that may have been extracted from coal by scCO2. The proposed technology will utilize cosolvent and surfactant formulations in scCO2 with a novel pressure swing dewatering system to improve water removal efficiency from coal and other porous materials. As such, the proposed technology will increase the value of coal and make coal as fuel more competitive to petroleum.