Natural Gas Sweetening Using an Energy-Efficient, State-of-the-Art, Solid-Vapor Separation Process

With the anticipated rise in global demand for natural gas (NG) and liquefied natural gas (LNG), sour gas reserves are attracting the attention of the gas industry as a potential resource. However, to monetize these reserves, sour natural gas has to be sweetened by removing acid gases (carbon dioxide and/or hydrogen sulfide) before liquefaction. The solidification of these acid gases could be the basis for their separation from natural gas. In this study, a state-of-the art solid-vapor (SV) separation unit is developed for removal of acid gases from methane and simulated using a customized Aspen Plus operation unit. The operating principles and conditions, mathematical model, and performance results are presented for the SV unit. Further performance analyses, means of optimization and comparisons to conventional methods used by the industry were studied. Results showed that for similar sweet gas purity, the developed SV unit consumes only 27% of the energy required by the amine sweetening unit. Furthermore, it saves on capital costs, as it requires less equipment and does not suffer from high levels of corrosion.Scopus2-s2.0-8513643009

Applying New Sustainability Metric in Different Natural Gas Liquid (NGL) Recovery Configurations to Extend Investment Decision and Incorporate Sustainability Analysis

Sustainable design is considered as one of emerging research area in process system engineering (PSE) society. It extends the investment decision that focuses mainly on profitability analysis to consider other aspects such as the environmental impact and safety aspects. The sustainability dimensions such as the economic and environmental impact are considered to assess the natural gas liquids (NGL) recovery process using a new sustainability metric referred as the sustainability weighted return on investment metric (SWROIM). It extends return on investment (ROI) concept and makes use of the augmented sustainability metrics and process integration targeting (benchmarking) approaches. We adapted a sequential strategy to assess different NGL configurations. The turbo-expanding separation method and its consequent configurations, the most applicable separation technology in today's gas industry were considered to process 84000 kg/h of natural gas. We used ASPEN HYSYS V9 to simulate six NGL flowsheet configurations. Other ASPEN products such as ASPEN Energy Analyser were utilized to perform other energy saving activities to improve the design of baes case. Considering the economic evaluation first, and using the ROI analysis, IPSI-1 and GSP are competing with the original ISS configuration with 44% and 40% as estimated rate of investment, respectively. After the incorporation of the sustainability metric with some weights (e.g. 0.07 for thermal saving via heat integration and 0.3 for CO2 emission reduction) as relative importance to economic profit, both IPSI-1 and GSP configurations improved in SWROIM analysis with 47% and 42%, respectively. However, IPSI-2 showed to be promising with 10 %, a percentage incremental in SWROIM analysis in comparison to 8 % in IPSI-1 configuration for 0.45 as CO2 emission reduction relative importance. 2018 Elsevier B.V

A techno-economic-environmental study evaluating the potential of oxygen-steam biomass gasification for the generation of value-added products

The production of renewable chemicals and fuels is driving modern society towards a type of sustainable development which involves a decreasing dependency on fossil fuels and the minimisation of waste. Biomass, a waste by-product from the urban environment, is a carbon dioxide neutral organic fuel that can potentially serve as a feedstock for the production of sustainable power and heat. Gasification is preferred over the other thermal conversion options for biomass processing whereby the product synthesis gas can be utilised to power generators/turbines and generate clean energy, ammonia and methanol. Incidentally, efficient and economically sound biomass driven supply chains can be integrated into an existing petrochemical infrastructure. Moreover, the potential production volumes of fuels and green chemicals can also be increased by the addition of multiple biomass sources, thereby creating potential positive scale effects. This study proposes a new poly-generation process that utilises multiple sources of biomass feedstock to produce high quality urea, methanol, Fisher-Tropsch liquids and power. Four flowsheet configurations are simulated using Aspen Plus software and the built-in capabilities of the activated analysis using Aspen Process Economic Analyzer and Aspen Energy Analyzer to perform the economic, energy and environmental impact calculations. The results demonstrate that the methanol production technique is the most economic process pathway with a net profit of approximately $0.035 per kg of biomass input, whilst the urea process pathway presents the lowest environmental impact solution with approximately 0.71 kg of CO2-e per kg of biomass input. These results are relative and can be analysed from different perspectives based on the market demand of the products and their applications and local need. For instance, considering at the economic and environmental indicators relative to the production capacity, production of liquid fuels achieve net profits of approximately$0.27 per kg of product, whilst urea production demonstrates the lowest environmental emissions of approximately 3.93 kg of CO2-e per kg of product. - 2019 Elsevier LtdThe authors acknowledge the support of Qatar National Research Fund (QNRF) (a member of Qatar Foundation , Qatar) by GSRA grant No GSRA4-1-0518-17082 . The statements made herein are solely the responsibility of the authors.Scopu

Potential energy savings and greenhouse gases (GHGs) emissions reduction strategy for natural gas liquid (NGL) recovery: Process simulation and economic evaluation

Recovery of sales gas and natural gas liquid (NGL) is characterized by its high energy consumption and significant environmental impact. This study explores the effect of design alternatives for NGL recovery on economic, energy, and environmental metrics. Focus is given to the turbo-expanding separation method owing to its wide applicability and potential for improvements. The primary configurations of turbo-expanding systems were simulated using ASPEN HYSYS. The simulation results included mass and energy balances, unit sizing, and sensitivity analyses using what-if scenarios to improve the design of the base configuration. Other ASPENTech products, such as the ASPEN Process Economic Analyzer and ASPEN Energy Analyzer were utilized to carry out an economic evaluation and optimization of utilities. To illustrate the value of the proposed approach, a case study was analysed for the assessment of various design alternatives to process 84,000 kg/h (5000 kmol/h) of natural gas while accounting for and reconciling the economic, energy, and environmental objectives

Carbon Capture from Post-Combustion Flue Gas Using a State-Of-The-Art, Anti-Sublimation, Solid–Vapor Separation Unit

This work attempts to address the quest of removing carbon dioxide from flue gas streams to help preserve the environment. It is based on a model that is able to describe the solid-liquid-vapour and solid-vapour phase equilibria for the ternary system of N2-O2-CO2 at pressures from 5 to 130 bar and over a wide range of temperature (140 to 220 K). Furthermore, a corresponding state-of-the art solid-vapor (SV) CO2 capture/separation unit is developed and introduced in this work. The SV unit was modeled using the Aspen Custom Modeler software by implementing the thermodynamic model developed before. It was then simulated using the Aspen Plus simulator; its performance was studied and analyzed. Moreover, the performance of the unit was optimized and compared to the most conventional corresponding technology used by the industry (i.e., amine-scrubbing). Results proved that for the same output clean gas composition, which contains only 0.3% CO2, the developed state-of-the-art SV unit consumes almost half of the energy required by the conventional process. Other advantages of the novel SV separation unit include the lower requirement of capital equipment, no need of additional agents (such as solvents) and the avoidance of product contamination with such additional agents

Influence of draw solution type and properties on the performance of forward osmosis process: Energy consumption and sustainable water reuse

Single and multi-component fertilizers were used as a draw solution (DS) in forward osmosis (FO) to produce high-quality water from synthetic and seawater solution, eliminating the need for DS regeneration and reducing the operational energy. The effect of DS type, concentration, circulation flow rates on the FO water flux (WF), specific water flux (SWF), percentage water recovery (%Wrecovery), reverse salt flux (RSF) and percentage salt rejection (%R) were studied. The results showed that single fertilizer draw solution (SFDSs) produced higher WF (4.43 L/m2.h), %Wrecovery (30%) and RSF (60%) in comparison with multi-component draw solution (MCDS) with WF, %Wrecovery and RSF of 2.57 L/m2.h, 17% and 46%, respectively. DS with higher concentration produced the highest SWF and %Wrecovery and consumed less energy. MCDS with concentration of 200 g/L showed SWF in the range of 14.0 to 10.4 L/m2h and energy consumption of 0.312 kW/h m3 in comparison with 10 to 7.8 L/m2h and 0.23 kW/h m3 for MCDS with concentration of 100 g/L. Increasing the recirculation flow rate showed minimum effect on WF and up to 35% energy saving. Pure water extracted using liquid fertilizers utilizing the unique FO mass transport properties balanced nutrient requirement and the water quality parameters, thereby sustaining the aquaponics industry. - 2019 Elsevier LtdThe work was made possible by a grant from the Qatar National Research Fund under the National Priorities Research Program award number NPRP 8-270-2-106 . Its content are solely the responsibility of the authors and do not necessarily represent the official views of QNRF.Scopu

Applying a Sustainability Metric in Energy, Water and Food Nexus Applications; A Biomass Utilization Case Study to Improve Investment Decisions

The demand for energy, water and food (EWF) resources will continue to increase, especially as the population is expected to reach 9 billion by 2050. The consequences of this include resource exhaustion and environmental degradation. Global pressures, such as climate change and resources depletion have encouraged the deployment of alternative energy systems and integration of carbon capture and sequestration processes. Currently, most chemicals and energy carriers are derived from finite fossil fuels which are susceptible to price fluctuation. Biomass, a renewable carbon-based fuel can be considered a promising substitute that can reduce environmental footprints in various applications. Gasification is a preferred route for handling biomass, in which the gas mixture (syngas) product is utilised to drive gas turbines and produce clean energy. Moreover, it can also be used to substitute natural gas in the petrochemical plants for methanol and ammonia production. Analysing the utilisation strategy of diverse biomass feedstocks represents a fertile research problem that can be addressed from a EWF Nexus perspective, which enables the quantification of impacts of biomass utilization strategies on the EWF systems. In this study, the utilisation strategy of biomass gasification feedstock for the poly-generation of different products is evaluated from an economic perspective. The Aspen Plus simulation models an oxygen-steam gasification technology to generate the optimal characteristics for each utilisation technique. Moreover, a sustainability metric was utilised to quantify the effect of each technique on EWF resources and to extend the investment decision making. Preliminary results generated from the simulation are integrated into a linear programming optimisation model that identifies the optimum biomass utilisation techniques that consider environmental and economic performances. The framework developed enables the selection of the optimal mix of biomass techniques that maximises sustainability indices for EWF resource systems, whilst ensuring a positive generation of the three corresponding resources. The results demonstrate that urea production and power generation are the most viable biomass utilisation techniques. - 2019 Elsevier B.V.The authors acknowledge the support of Qatar National Research Fund (QNRF) (a member of Qatar Foundation) by GSRA grant No GSRA4-1-0518-17082.Scopu

A novel hybrid life cycle assessment approach to air emissions and human health impacts of liquefied natural gas supply chain

Global interest in LNG products and supply chains is growing, and demand continues to rise. As a clean energy source, LNG can nevertheless emit air pollutants, albeit at a lower level than transitional energy sources. An LNG plant capable of producing up to 126 MMTA was successfully developed and simulated in this study. A hybrid life cycle assessment model was developed to examine the social and human health impacts of the LNG supply chain?s environmental air emission formation. The Multiregional Input?Output (MRIO) database, the Aspen HYSYS model, and the LNG Maritime Transportation Emission Quantification Tool are the key sources of information for this extensive novel study. We began our research by grouping environmental emissions sources according to the participation of each stage in the supply chain. The MDEA Sweetening plant, LNG loading (export terminal), and LNG transportation stages were discovered to have the maximum air emissions. The midpoint air emissions data estimated each stage?s CO2-eq, NOx-eq, and PM2.5-eq emissions per unit LNG generated. According to the midpoint analysis results, the LNG loading terminal has the most considerable normalized CO2-eq and NOx-eq emission contribution across all LNG supply chain stages. Furthermore, the most incredible intensity value for normalized PM2.5-eq was recorded in the SRU and TGTU units. Following the midpoint results, the social human health impact findings were calculated using ReCiPe 2016 characterization factors to quantify the daily loss of life associated with the LNG process chain. SRU and TGTU units have the most significant social human health impact, followed by LNG loading (export terminal) with about 7409.0 and 1203.9 (DALY/million Ton LNG produced annually), respectively. Natural gas extraction and NGL recovery and fractionation units are the lowest for social human health consequences.Scopu

A process design approach to manage the uncertainty of industrial flaring during abnormal operations

Flare management challenges are related to the flaring uncertainty during abnormal situations. In this work, a multi-objective optimization framework is upgraded with multi-period optimization and Monte Carlo simulation to incorporate the risk associated with uncertain flare events. An ethylene plant is used to present the developed framework. Using the ethylene process historical flaring data, Monte Carlo simulation generates probabilistic values for flaring events and event duration. Here, cogeneration unit (COGEN) is considered as the flare reduction alternative. The results of the formulations are presented as a set of Pareto fronts providing insights into the competing techno-economic and environmental objectives. Sensitivity analysis on the factors for the case suggests that some factors such as CO2 tax savings are severely affected by minor variations in flaring profiles, whereas others such as the fixed and operating costs are less sensitive. Hence, using this approach, the decision maker gains techno-economic-environmental insights regarding the flare reduction alternative (COGEN).This paper was made possible by NPRP grant No 5-351-2-136 from the Qatar National Research Fund (a member of Qatar Foundation ). The statements made herein are solely the responsibility of the author[s]. The author thanks Ahmed Mhd Nabil AlNouss and Fahd Mohammed for their contribution through managing the historical database and for providing access to the GHG calculator

Design, optimization and economic analysis of a monoethylene glycol recovery process: salt precipitation and vacuum operation

In the present study, the energy requirements, performance and economic feasibility of monoethylene glycol (MEG) recovery process (MEG-R-P) were establish based on Aspen Plus simulation. The simulation was carried out in two designs and four scenarios related to the composition (mono and divalent salts) of rich-MEG. The results revealed that, under optimized conditions, a process consists of a vacuum flash separator and distillation column operated at 0.05 bar recovered 99.7% of MEG with a purity of 99.9 wt% MEG for all scenarios. The concentration and type of dissolved solids showed a minimal effect on the process of energy and performance due to high dilution. The net present worth (20 years, 8%) of the capital and operating costs associated with MEG-R-P were 11.5 and 11.7 MMUSD, respectively, representing two to four folds saving compared with published results. The recovered MEG can be recycled 10 times with an estimated saving of 50% of the total MEG purchasing cost for one-time recycling, and up to 80% saving for five times recycling. Obtained results confirm the high economic and environmental benefits achieved by applying the proposed MEG-R-P.Scopu