Cryogenic carbon capture process can be used to efficiently eliminate CO2 emissions from fossil-fueled power plants. The energy-storing embodiment of cryogenic carbon capture (ES-CCC) integrates energy storage with cryogenic carbon capture and uses natural gas as a refrigerant. ES-CCC captures CO2 from slowly varying or steady-state sources even as it absorbs and replaces large amounts of energy on the grid for energy storage. These large transients occur in the LNG generation as the process moves through energy storing to energy recovery operations. Additionally, raw natural gas often includes CO2 that forms an azeotrope with ethane. Breaking this azeotrope and separating CO2 from other hydrocarbons to meet natural gas pipeline and liquefied natural gas (LNG) standards is very energy intensive. The purpose of this work is to (a) describe a dynamic heat exchanger that reduces the heat exchanger performance and efficiency losses experienced under transient conditions and (b) introduce an alternative extractive distillation system for CO2 separation from ethane that requires less capital and has a lower operating cost than the conventional system for the same purification. This investigation demonstrates theoretically and experimentally that the dynamic heat exchangers can absorb sudden and large changes in flow rates and other properties without compromising either the heat exchanger efficiency or creating thermal or other stresses. These heat exchangers play an essential role in the ES-CCC process. Designs for retrofitting existing heat exchangers and for replacing existing heat exchangers with new designs are both theoretically and experimentally tested. The ES-CCC process requires natural gas processing to meet pipeline and LNG standards in many applications, depending primarily on the CO2 content of locally available NG. The energy, cost, and dynamic response of such processing hinges primarily on the most difficult step, breaking the CO2-ethane azeotrope. This project proposes and analyzes an alternative process for breaking this azeotrope and a control scheme that dramatically improves the dynamic response of natural gas processing plants, including steady and transient control scheme and processing simulations. These contributions to the ES-CCC capture process all have much broader applications in many chemical and energy processes. These contributions to ES-CCC and other industrial processes improve energy efficiency and dynamic performance of many processes and are ready for larger scale demonstration.

This work suggests a new multiple ejector refrigeration cycle operated by an NGL Recovery Plant's waste heat as a replacement to the mechanical compression refrigeration cycle. This will result in significant power reduction and CO2 emission reduction. / Typical NGL plant compresses its feed to a high pressure (3040 kPa). The feed gas compressors’ discharge reaches approximately 150 OC. After that, the feed is cooled by three-stage propane vapour compression refrigeration cycle. This paper examines various options for thermal power cooling in such plants in order to eliminate part of the propane chilling system. Since most of the new plants are located in desert climates, typical designs based on absorption refrigeration are not very efficient. Design proposed in this work employs ejector refrigeration and it is based on 45 OC air as a cooling media (summer conditions in hot climates). Performance factor has been defined as the total cooling provided by the refrigeration system over the total cooling required in the 1st cooling stage of the NGL Recovery Plant. Cooling based on a single N-pentane ejector cycle with N-pentane has COP of 0.342 and performance factor (ƞ) of 0.842. Multistage ejector N-pentane refrigeration system has COP of 0.714 and performance factor (ƞ) of 1.053. For a typical 750 Million scf/d NGL plant, the new design saves $12 Millions in capital costs and $1.5 in annual electricity cost. / Thesis / Master of Applied Science (MASc)