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(a) Schematic diagram of the flare power cycle (FPC1) in which the flare gas is mixed and combusted with the natural gas in the DOC (b) T-S diagram of FPC1.
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With more than 150 billion m³ of gases annually flared around the world, gas flaring is a major source of greenhouse gas emissions that contaminates the environment with more than 400 Mt CO2/year. Therefore, utilizing the flared gases efficiently becomes inescapable and one of the most promising utilization technologies is using Gas-to-Power (GTP)....
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... studies are carried out for the major operating conditions including effects of maximum and minimum cycle pressures and temperatures, flare composition, and flow rates. Results of the single-and multi-objective optimization analysis are presented and discussed in subsection 4.2. The main findings and conclusions are summarized in section 5. Fig. 2 (a) and (b) depict the configuration and the T-S diagram of the first flare power cycle (FPC1) in which the flare gas is received from the flare gas recovery system (FGRS) at given pressure and temperature with variable flow rate (state "s") to be mixed with the NG. For efficient mixing of NG and flare gas, the temperature and pressure of ...
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... dense phase and could be pumped by pump 1 (16)(17) to the desired pressure. Using the pump instead of the gas compressor significantly reduces the compression power. Then, the high pressurized CO 2 flow is recycled to the DOC after being preheated by the LTR (17-18) and the HTR (18-8) to repeat the cycle as presented in the T-S diagram of FPC1 ( Fig. 2 ...
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... performance of FPC2 is affected by the increase of T min in a similar way for FPC1 (see Fig. 12). This since the variation of T min affects the compression power of Comp. 3 and Pump 1 and the cooling loads of the PC and IC components which are common parts in both ...
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... Therefore, in FPC1, the LCOE for all samples is lower than reported in [23] for all samples. The opposite is true for the FPC2 (Fig. 14) where the indirect approach may be more efficient than the direct method. Therefore, the investigation of utilizing the flare gases to drive the sCO 2 closed power cycle with indirect-combustion is recommended Fig. 12. Effect of the minimum cycle temperature on the (a) thermal efficiency, (b) exergy efficiency, (c) total product unit cost, and (d) LCOE of ...
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Solar energy is pollution-free and causes no greenhouse gas emissions after installation and during power generation. Regarding the environmental concerns raised by power generation systems, in the present study a novel solar-based CCHP system is proposed. The system is a modified configuration of conventional Rankine cycle and ejector refrigeratio...
Citations
... Low fluctuations of mass flow would be easier for the combined power cycle to be handled while a gas-sweetening plant seems to be the best choice for high fluctuations. Sleiti et al. (2022) utilized the advantages of direct oxygen combustion (DOC) in the integration with two proposed flare super critical CO 2 inter-cooled power cycles in FGR. Natural gas and flare gases were mixed and combusted in the first cycle before entering the DOC unit, while, in the second cycle, the flare gases were employed in a heat exchanger to reheat the exhaust flow from the first cycle. ...
The gas flaring network is an inseparable constituent commonly present in most of the oil and gas refineries and petrochemical facilities conferring reliable operational parameters. The improper disposal of burn-off gases improperly results in environmental problems and loss of economic resources. In this regard, waste to energy transforming nexus, in accord with the “carbon neutrality” term, has potentially emerged as a reasonable pathway to preserve our planet. In a transdisciplinary manner, the present review article deeply outlines the different up-to-date strategies developed to recover the emitted gases (flaring minimization) into different value-added products. To analyze the recovery potential of flare gases, different technologies, and decision-making factors have been critically reviewed to find the best recovery methods. We recommend more straightforward recovery methods despite lower profits. In this regard, electricity generation seems to be an appropriate option for application in small amounts of flaring. However, several flare gas utilization processes such as syngas manufacturing, reinjection of gas into petroleum reservoirs, and production of natural gas liquid (NGL) are also recommended as options because of their economic significance, technological viability (both onshore and offshore), and environmental benefits. Moreover, the adopted computational multi-scale data assimilation for predictive modeling of flare gas recovery scenarios has been systematically reviewed, summarized, and inspected.
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... In another study, the sensitivity analysis, economic optimization and design of refrigerant cycles of the stabilization process were investigated. In Sleiti's research, the use of a one-stage refrigeration cycle was introduced as the best cooling method (Sleiti et al. 2022). In addition, in Sarkari's work, steady-state simulation of the liquid natural gas process and GTL process was investigated to determine mass and energy balance (Sarkari et al. 2022). ...
The gas condensate is one of the most valuable products of gas refineries. In unit 700 of the Sarkhon gas refinery, first, the gas condensate is separated from the feed. Then, the vapor pressure of the gas condensate is stabilized by de-ethanizer and de-butanizer towers. The H-701 and H-702 furnaces act as reboilers of the towers. In this research, unit 700 is simulated by HYSYS software. The product of this unit is examined to achieve desirable conditions. In addition, the best conditions are obtained to reduce the gas loss in this unit. The desirable conditions are introduced according to the operational problems of this unit. In this study, the environmental and economic loss due to the loss of hydrocarbons from the de-butanizer tower is identified. Results of this research show that the best operating temperature and pressure of the first feed are 40 °C and 29 bar, respectively. Also, the best temperature and pressure of the second feed are 20 °C and 28 bar, respectively. Also, the best temperature and pressure of the output stream from the S-701 as a feed of the T-701 are 34.35 °C and 22.51 bar, respectively.
... The authors reported that the two options proved to be economically viable when they were implemented on a plant with a capacity of 2500 Barrels per day (BPD). Sleiti et al. [5] employed direct oxy-combustion supercritical CO2 power cycle to achieve no flaring-no emissions solution. Two innovative flared-intercooled power cycles which utilized flare gases and natural gas as fuel were used. ...
Utilizing associated gas (A-Gas) in gas turbines for power generation applications would greatly solve some of the acute power challenges Nigeria is faced with over the years. However, utilizing A-Gas to generate a given power demand, would necessitate the engine fired with associated gas to consume more fuel; thereby causing the engine to operate at elevated turbine entry temperatures, which may affect the creep life of the turbines. This study investigates the effect of associated gas utilization on the creep life of gas turbines. GasTurb details 5.1 was employed to model the A-Gas fuel, while GasTurb 11 was used to model and simulate the performance of the aero-derivative gas turbine engine fired natural gas and associated gas separately. The input and output gas path parameters obtained from GasTurb simulations which include mass flow rate, Pressure ratio, turbine entry temperature, engine rotational speed, power output etc. were used as input to size the HP turbine Blade. Larson Miller parameter and blade metal temperatures obtained for different sections of the blade were used to estimate the time to failure of the HP turbine blade for the two conditions (blade of engine fired with natural gas and A-gas separately) investigated. The results show that the estimated time to failure of the HP turbine blades for engine fired with natural gas is 49,821.4 h as against 33,158 h for the one operated with A-Gas fuel.
... However, Case 6 has the lowest compression power with SEC of 1.32 kWh/kgH2 Feed at aftercooler temperature higher than 37 C compared to 1.45 kWh/kgH2 Feed for Case 9. Therefore, Case 9 is recommended for the wet-cooling conditions and Case 6 for the dry-cooling conditions. But, even though the wet-conditions yield lower SEC than dry-conditions, the capital and operational costs of the wet-cooling system are higher than of the dry-cooling system [43,44]. Therefore, for accurate decision for the selection of the wet or dry cooling i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( x x x x ) x x x conditions, further economic assessment is needed for each situation and is recommended as a future work. ...
Designing an optimal mixed-refrigerant (MR) composition for any cryogenic refrigeration process plays a key role in the process overall performance. However, the existing approaches of developing mixed-refrigerants for these processes are difficult, time-consuming, and semi-random trial and error approaches. Therefore, for the first time, this study presents a systematic thermodynamic approach to optimally design mixed-refrigerants for any cryogenic process. In particular, the developed approach is conducted for the hydrogen precooling process (HPP) with a precooling temperature less than −193 °C. This approach consists of four criteria and seven major steps needed for the development of an energy-efficient HPP. Using this approach, 15 new mixed-refrigerants are created, analyzed, and compared based on the specific energy consumption (SEC) and coefficient of performance of the HPP. Further sensitivity analyses for the major operating conditions of the HPP are conducted for the best five cases. A minimum SEC of 1.03 kWh/khH2Feed at wet-cooling conditions and of 1.32 kWh/khH2Feed at dry-cooling conditions are achieved, which is remarkably 78.81% lower than the SEC of the existing HPP in commercial plants. This study also found that eight-component MR is the best option to create optimal mixtures for cryogenic cooling processes with perfect match between the composite curves of all heat exchangers of the HPP. While methane, nitrogen, and hydrogen components are essential for the MR to achieve energy-efficient HPP, the use of ethylene instead of ethane, H2 instead of neon, and R14 instead of NH3 is recommended to optimize the SEC.
... But their analysis is limited to the capital cost without reporting the LCOE for these configurations. However, the LCOE for CSP-based Allam and partial cooling sCO 2 power cycles are estimated to be in the range from 8 to 11 ¢/kWh as reported by Crespi et al. 46 In the open literature, only three studies 29,47,48 reported the LCOE for DOC-based sCO 2 power cycles working at TIT between 550 and 750°C. However, these studies are limited to preheating (6.3 ¢/kWh) 47 and flared-power cycles (7.7 ¢/kWh). ...
... However, these studies are limited to preheating (6.3 ¢/kWh) 47 and flared-power cycles (7.7 ¢/kWh). 48 Therefore, further economic analysis for DOC-based cycles is needed to assess the economic feasibility of various configurations other than preheated and flared cycles, which is one of the major contributions of the present study as shown in Figure 1. ...
This study presents comprehensive energetic, exergetic, exergoeconomic, and economic (4E) performance analyses for four direct oxy‐combustion (DOC) supercritical carbon dioxide (sCO2) power cycles at design, off‐design, and part‐load conditions. These cycles include the dual recuperator cycle (DRC), intercooling cycle (ICC), partial intercooling cycle (PIC), and reheating cycle (RHC). The analyses were conducted at relatively low turbine inlet temperatures (TIT: 550–750°C) with compressor inlet temperature (CIT) varied from 33°C (wet‐cooling) to 50°C (dry‐cooling). Furthermore, single‐ and multiobjective optimization analyses were conducted for each cycle. At design conditions (high‐pressure of Pc,o = 20 MPa, low‐pressure of Pc,o = 5.4 MPa, TIT = 750°C, CIT = 50°C [dry‐cooling]), the PIC has the highest thermal efficiency (47.78%) compared to 38.36% for DRC, 45.71% for ICC, and 44.39% for RHC. At optimized conditions (Pc,o = 30 MPa, Pc,o = 8 MPa, TIT = 744°C, CIT = 30°C [wet‐cooling]), the ICC shows superior energetic performance (52.08%) compared to 47.97% for DRC, 49.20% for PIC, and 48.62% for RHC. At off‐design conditions with a power demand (PD) of 40% of the design load (50 MW), the thermal efficiency is decreased by 21.82% in DRC, 17.71% in ICC, 22.46% in PIC, and 13.60% in RHC. The ICC has the minimum levelized cost of electricity compared to the other cycles with 5.93 ¢/kWh at design conditions (dry‐cooling), 5.65 ¢/kWh at optimized conditions (wet‐cooling), and 7.2 ¢/kWh at minimum PD (21 MW). Therefore, from an economic point of view, the ICC is recommended as the best power block for a sCO2 power cycle driven by oxy‐combustor at moderate TITs. The study also provides constructive comparisons between the DOC‐sCO2 and indirect (nuclear, solar, and waste heat) sCO2 power cycle systems and the future research directions.
... Zhu coupled the cycle with the integrated coal gasification and analyzed the Allam-Z process feasibility to coal and natural gas power plant [27]. In addition to natural gas, the Allam-Z cycle can also operate with flare gas [28]. Sleiti et al. [29] compared the influence of air cooling and water cooling on Allam-Z cycle efficiency and levelized cost of electricity (LCOE). ...
This paper proposes a modified Allam-Z cycle that uses chemical-looping combustion (CLC) instead of traditional combustion, called CLC-Allam cycle. Under the same cycle and components conditions, the electric efficiency of the CLC-Allam cycle is about 9.5 percentage points higher than the original Allam-Z cycle. The investigation of selecting oxygen carriers in the CLC-Allam cycle reveals that cupric oxide always provides the highest fuel conversion in the supercritical carbon dioxide (SCO2) atmosphere and is thus believed to be the best oxygen carrier among the five investigated metallic oxides. The subsequent analysis focuses on parametric sensitivity and shows that (1) the inlet temperature and isentropic efficiency of CO2 pump have little effect on cycle efficiency, beneficial to enhance the system robustness; (2) the isentropic efficiency of turbine and compressor has a more significant influence on the cycle electric efficiency than the pump; (3) an optimal SCO2 turbine inlet temperature exists for the CLC-Allam cycle and the oxygen carrier will not encounter sintering or melting problems under the optimal temperature.
... In the supercritical phase (T cr > 31.1°C, P cr > 74 bar for pure CO 2 ), the CO 2 has the favorable flow characteristics of a gas and the high density of a liquid [5]; for this reason, the CO 2 is used as working fluid in the supercritical CO 2 power cycles [6][7][8][9][10]. This makes pipelines the suitable mode of CO 2 transport in the supercritical phase. ...
Carbon dioxide transport from capture to utilization or storage locations plays key functions in carbon capture and storage systems. In this study a comprehensive overview and technical guidelines are provided for CO2 pipeline transport systems. Design specifications, construction procedures, cost, safety regulations, environmental and risk aspects are presented and discussed. Furthermore, challenges and future research directions associated with CO2 transport are sorted out including the large capital and operational costs, integrity, flow assurance, and safety issues. A holistic assessment of the impurities' impacts on corrosion rate and phase change of the transported stream is required to improve pipeline integrity. The influence of impurities and the changes in elevation on the pressure drop along the pipeline need to be further investigated to ensure continuous flow via accurate positioning of pumping stations. Although the long-experience in oil and gas pipeline industry forms powerful reference, it is necessary to develop particular standards and techno-economic frameworks to mitigate the barriers facing CO2 transport systems. Digital twins (DT) have potential to transform CO2 transport sector to achieve high reliability, availability and maintainability at lower cost. Herein, an integrated 5-component robust DT framework is proposed for CO2 pipeline transport systems and the future directions for DT development are insinuated. Data-driven-algorithms capable of predicting system's dynamic behavior still need to be developed. The data-driven approach alone is not sufficient and low-order physics based models should operate in tandem with the updated system parameters to allow interpretation and result's enhancing. Discrepancies between dynamic-system-models, anomaly-detection and deep-learning require in-depth localized off-line simulations.
... Introduction ▪ Traditional refrigeration systems use HFO/HFC refrigerant blends which have negative impacts on environment such as ozone depletion and global warming [1][2][3][4][12][13]. ▪ Furthermore, refrigeration and air-conditioning systems consume around 17% of the worldwide electricity [5]. ▪ Therefore, developing new refrigeration systems that work by sustainable energy sources and use eco-friendly refrigerant are urgent need to address these issues [14][15][16]. ▪ Recently, refrigeration systems that use thermal energy as a power source (such as absorption and ejector-based systems) have gained much interest by researchers in the field. ▪ However, most of the proposed thermal refrigerating systems have complex configurations, low COP at low temperature source, and comparatively high capital costs [6-8]. ...
The current electrical refrigeration and air condition systems are considered as one of the major sources for ozone depletion and global warming problems. Furthermore, they consume a large percentage of the worldwide gross production of electricity (around 17%). Therefore, developing new refrigeration systems that might be able to work using renewable sources (solar, geothermal, etc.) and waste heat sources is necessary to address these problems. In this paper, the experimental investigation of an innovative thermal-mechanical refrigeration (TMR) system is presented. The TMR system replaces the electric compressor of the conventional refrigeration systems with an innovative expander-compressor unit (two connected double-acting cylinders). The proposed ECU can be driven by ultra-low heat temperature sources, has simple configuration, and high flexibility for the operating conditions. A hybrid electric-compressor and ECU refrigeration setup was developed to investigate the performance of the ECU and compare it to that of an electric compressor. The experiment was conducted using R134a as a working fluid at different masses. The results show that a maximum COP of 0.57 is obtained at a refrigerant mass of 30g (in electric mode) and a maximum COP of 0.41 is obtained at a refrigerant mass of 60g (in ECU mode).
