الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Environmental regulations concerning global warming has redirected the attention towards limiting carbon emissions from various industrial sources and thermal power plants. The global CO2 emissions in 2020 reached 31.5 giga tonnes, with Egypt participating with 223.5 million tonnes (0.7% of the global emissions). The emissions resulting from the fuel combustion of the thermal power plants are approximately 40% of the total emissions. The CO2 emission standards, developed by Environmental Protection Agency (EPA) for fossil fuel-fired electric utility generating units (EGUs), are 635 kg CO2/MWh. In Egypt, the natural gas (NG) combustion of the thermal power plants represents as high as 95% of the total fuel combustion. On the other hand, global energy production and consumption demand, particularly for electricity, are rapidly rising, owing in part to the world’s growing population. Because of the increasing recurrence of grid failures associated with the rising economic dependency on electricity, and the enhanced development of renewable energy resources, the importance of energy storage systems will expand disproportionately over time. Energy storage systems on the grid help to sustain a diverse portfolio of electricity generation. One of the recent technologies that could handle the CO2 emissions problem and has the ability to store thermal energy at the same time is the cryogenic carbon capture energy storing system (CCC-ES). CCC-ES is a post-combustion method that uses refrigeration to desublimate CO2 in a solid form from the process stream. However, the feasibility of adopting this technology has not been sufficiently demonstrated in terms of: (a) integrating with thermal power plants operating by NG (which are widely used in Egypt), (b) approaching almost zero CO2 emissions, (c) operating under part loads, (d) possibility of operating independently the grid power, and (e) reducing energy penalties and thus increasing overall efficiency by utilizing the waste heat available in the flue gases. Thus, the aim of the current work is to overcome the above-mentioned scientific gaps through designing, applying, and testing a novel thermal integration of CCC-ES technology into the newly designed NG thermal power plants that can achieve almost zero CO2 emissions with the minimum possible energy penalty, and handle the load fluctuation by adopting thermal energy storage. The study will also consider the feasibility of integrating the CCC into the existing and operating thermal power plants and will highlight the necessary modifications and consequent energy requirement compared with the newly designed case. The integration with the newly designed plants is denoted by “Novel integration” while the integration with the existing plant is dented by “Conventional integration”. The cryogenic carbon capture external cooling loop (CCC-ECL) cycle that was developed by Sustainable Energy Solutions LLC (SES) in collaboration with Brigham Young University (BYU) is selected to be integrated with a 650 MW thermal power plant operating with NG in Abu Qir, Egypt. The two plants are simulated inside Aspen Plus software and the simulation results are validated individually by comparing both of them with the actual values of their independent cycles during different operating conditions. A complete dynamic control system, which employs single-input single-output proportional integral controllers, is installed that allows the integrated cycle to be run and tested under various operation scenarios and loads. The integrated cycle, during different part loads, will be examined under the two integration cases while capturing 90% CO2. The 90% carbon capture is the benchmark recommended by the US Department of Energy (DOE). However, the study will investigate the possibility of capturing more CO2 to reach almost zero emissions (99% of carbon emission) and explore the consequent penalties in the power and the thermal efficiency for near zero emissions. The dynamic performance of the integrated cycle, during different part loads, will be studied and analyzed under the two integration cases, to test the safe transition between load without troubleshoot or trips. The mechanism of storing and recovering the energy is explored using the software. When there is an extra power, it will be directed to the compressor of the CCC-ECL plant to start liquefying more NG that will be stored as LNG during the excess power periods. This energy is released by evaporating the LNG in the CCC-ES cycle and using it by gas turbine units during periods of high demand to increase the generated electricity. Based on the status of both the grid and the demand, two possible recovery scenarios will be studied and analyzed determining the energy recovery efficiency for both scenarios. Results showed that modeling the CCC-ECL cycle and the thermal power plant inside Aspen are in very well agreement with their referenced data with a maximum relative error of 3.1%. The transitions from full load to part loads and vice versa have not been affected by the integration of the CCC-ECL and the simulations revealed very reasonable transition time. The integrated cycle, during different loads, succeeded in capturing 90% of the flue gas CO2. For example, the amount captured CO2 at the full load operation, was 274 of 304, and 272 of 302 tonne/hr CO2 for the novel and conventional integration cases, respectively. Depending on the power plant load, the maximum DROP of the overall thermal efficiency of the integrated cycle was 0.0148 (3.5%) and 0.0464 (10.8%) under the novel and the conventional integration cases, respectively, proving that the proposed novel integration is more efficient and recommended to be implemented in the newly designed power plants. The maximum energy penalty was 0.874, and 0.8844 MJe/kgCO2, for the novel and conventional integration cases, respectively. This proves that that the CCC-ECL technology is extremely competitive with alternative technologies such as amine-based absorption that has 1.3791.29 MJe/kgCO2 (43% less). By capturing 99% of CO2, at full load, the overall thermal efficiency dropped by 1.5 and 11% for the novel and conventional integration cases, respectively. The integrated cycle was able to store and recover energy under the two recovery scenarios with recovery efficiency 99.9% without installing any additional equipment, which proved the advantage of this technology over the other energy storage technologies. Therefore, if the CCC-ES technology is adopted all over the thermal power plants in Egypt, 80 million tonnes of CO2 emissions will be captured annually (which represents nearly 36% of the total Egypt emissions, and 0.25% of the global emissions), with energy penalties extremely competitive with alternative technologies, and ability to store and recover energy during the load fluctuation. This will lead to a significant impact on the improvement towards cleaner environment and more stable energy in Egypt in the future.