Theoretical And Experimental Study Of Post-combustion Carbon Capture Integrated With Mediumn To Low Temperature Solar Energy

Carbon capture and storage is an important method and strategic choice to reduce CO₂ emissions.However,the main obstacle is the high energy penalty,which results in the decrease of power output,and leads to the power plant operating in off-design point.Low to medium temperature solar collectors have chacteristics of wide temperature range,high level of thermal energy.Utilizing solar thermal energy to replace steam extraction for CO₂ capture is an effective method to reduce the energy loss.Thus,this paper carried out the theoretical and experimental study on solar coupled CO₂ capture.First of all,starting from the cross area of engineering thermodynamics and chemical thermodynamics,the laws of energy and mass flow in fuel conversion,power cycle and gas separation were revealed.The energy and exergy flow models are established and the mechanism of minimum CO₂ capture energy was carried out.Results show that for direct combustion,the match of level of energy in fuel conversion process is the worst,which has the largest exergy loss;the exergy efficiency of solar collector is influenced by solar thermal efficiency and the level of thermal energy.When solar energy is coupled with the power plant,it can reduce the exergy loss of the coupling system,and then enhance the advantages of solar energy.Secondly,the[bmim][BF₄]ionic liquid was selected and mixed with amine solutions.The properties of density and viscosity were measured under different percentage and temperature,the data of the density and viscosity was fitted.Then,the absorption performance of the blend solvents was tested to evaluate the overall performance.The study found that using ionic liquid to mix with amine solvent can be greatly reduce the density and viscosity,and the blend solvent with AMP+[bmim][BF₄]has higher CO₂ solubility.And then a lab scale of CO₂ absorption-desorption experiment equipment was set up.The absorption and desorption performance was investigated.The cyclic performance of absorption-desorption experiments were tested,the specific regeneration was optimized.Results indicated that this system can gain the lowest specific regeneration energy at 4.2 MJ/kg of CO₂ when L/G ratio is about 4.0.At the same time,a parabolic trough solar collector and linear Fresnel reflector were designed.The thermal performance of these two types of solar collectors were tested and measured.The operating characteristics of solar energy assisted CO₂absorption-desorption system were experimentally studied.Results show that the heating temperature can reach the temperature of the reboiler demand,solar energy can be partially or completely replace energy consumption of CO₂ capture,but the stability of the system is reduced.Under the certain temperature fluctuations of heat source,the CO₂ absorption-desorption system has certain self-adaptive ability,while the specific regeneration energy ranges between 3⁸ MJ/kg CO₂.Finally,a novel integration system was proposed that using geothermal energy to replace the regeneration energy in CO₂ capture process.The proposed system was investigated technically and economically based on a typical 300MW power plant and typical geothermal resources.Some of the parameters were analyzed to show their performance.Results indicate that the geothermal assisted post-combustion CO₂capture system has lower COE and COA when the temperature of geothermal fluid is higher than 160^oC compared with the conventional CO₂ capture plant without geothermal assistance.In the end,the cascade utilization of geothermal energy can improve the performance of system;the net efficiency of power output can be increased by 0.82%.