The oil production from any well passes through three stages. The first stage is the natural extraction of oil under the well pressure, the second stage starts when the well pressure decreases. This second stage includes flooding the well with water via pumping sea or brackish water to increase the well pressure and push the oil up enhancing the oil recovery. After the first and secondary stages of oil production from the well, 20–30% of the well reserve is extracted. The well is said to be depleted while more than 70% of the oil are left over. At this stage, the third stage starts and it is called the enhanced oil recovery (EOR) or tertiary recovery. Enhanced oil recovery is a technology deployed to recover most of our finite crude oil deposit. With constant increase in energy demands, EOR will go a long way in extracting crude oil reserve while achieving huge economic benefits. EOR involves thermal and/or nonthermal means of changing the properties of crude oil in reservoirs, such as density and viscosity that ensures improved oil displacement in the reservoir and consequently better recovery. Thermal EOR, which is the focus of this paper, is considered the dominant technique among all different methods of EOR. In this paper, we present a brief overview of EOR classification in terms of thermal and nonthermal methods. Furthermore, a comprehensive review of different thermal EOR methods is presented and discussed.

Hydrogen has a potential to be a clean energy carrier that emits only water after combustion and can be produced from diverse feedstocks. Hydrogen has much better combustion characteristics in conventional combustion systems and higher energy efficiency when used with fuel cells. More than 75 million tons of hydrogen are currently produced primarily using fossil fuels as feedstock via steam methane reforming processes. Steam methane reforming is the mature technology for producing hydrogen and when coupled with CO2 capture can help address climate challenges. Inorganic palladium (Pd) membranes have demonstrated great potential to separate hydrogen due to their stability and high selectivity for hydrogen. In this review, several methods of fabricating Pd-alloy membranes are discussed and compared in terms of membrane stability and selectivity of hydrogen. Such methods include electroless plating (ELP), chemical vapor deposition (CVD), physical vapor deposition (PVD), and electroplating deposition (EPD). The permeability of hydrogen in different Pd-based alloy membranes are presented and compared. Focus has been made, in this review, on Pd–Ag, Pd–Cu, Pd–Au, and Pd–Ru alloys. The effects of impurities (H2S, CO, O2, and CO2) on performance of different Pd-based alloy membranes are also investigated. Moreover, the subject of using Pd-membrane reactors for fuel reforming and H2 production is investigated in detail based on numerous experimental and numerical studies in the literature, considering different membrane reactor designs: axial-flow tubular, radial-flow tubular, axial-flow spherical, packed-bed, fluidized bed, and slurry bubble column. The performance of Pd-membranes in such reactors for hydrogen production is compared, and the effects of temperature, pressure, H2O/CH4 ratio, and residence time on reformer performance are also investigated. Finally, the use of computational methods, particularly, density functional theory (DFT), to complement well-established experimental methods for studying the diffusion of H and its isotopes in different metals is reviewed. The review concludes with some insights into future work to bring Pd-membrane reactors to the level required for hydrogen production at the commercial level.

No abstract

No abstract

Oxy-combustion characteristics of methane and hydrogen-enriched methane have been investigated experimentally in a nonpremixed swirl-stabilized combustor. Experiments were conducted at different firing rates ranging from 2.5 to 4.5 MW/m 3 -bar and 0% to 20% hydrogen content in methane/hydrogen fuel mixtures. When the combustor is operated under gas turbine conditions (≥3.5 MW/m 3 -bar), the flame transitions exhibit trimodal regime (i.e., attached flame → lifted flame → no flame) below which the flame transitions exhibit bimodal regime (i.e., attached flame → no flame). Weak flames at the nozzle exit were generally observed to precede the attached flame → lifted flame transition. The weak flame is due to the entrainment of more CO 2 -containing oxidizer (O 2 /CO 2 ) to the fuel stream that reduces the flame burning rate. The attached flame → lifted flame transition occurs at a critical oxidizer velocity. The critical oxidizer velocity strongly depends on the fuel composition. Moreover, lifted flame oscillates about different points (stabilization points) within the combustor. These points can be interpreted as locations of lower scalar dissipation rate, where the leading edge flame speed matches the local flow velocity. Empirical equations presented in this study captured the trend of our experimentally normalized flame length. The predicted flame length based on the near-field concept gave a good match with our experimentally observed flame length. Temperature data are also presented and can be used in the validation of numerical models to have further insight into the oxycombustion dynamics of methane and hydrogen-enriched methane in a cost-effective way.

No abstract

No abstract

No abstract