Natural Gas Liquids Recovery Process Research Articles

Ethane integration project—a study for Egyptian NGLs plants and their economics

For Egypt, ethane is a vital chemical precursor, with the potential to significantly attract financial resources and drive economic growth. Enhancing its added value necessitates efficient recovery of ethane before it enters the national grid without processing. This research investigates the technical and economic feasibility of integrating natural gas liquids (NGLs) from three Egyptian NGLs plants—South Western Desert NGLs (SWD NGLs), North Western Desert NGLs (NWD NGLs), and East Mediterranean NGLs (EMD NGLs)—to improve ethane recovery from natural gas fields. The study focuses on revamping these NGLs plants using various NGLs recovery techniques, conducting a comprehensive comparison to identify the most effective methods for processing rich feed gas. Detailed design of the NGLs recovery processes was developed using HYSYS V.14 simulation software and supplementary calculation sheets. The design criteria encompass both technical and economic parameters to ensure a holistic approach in meeting project requirements. Results indicate a significant increase in ethane recovery: 16% for SWD NGLs, 10% for NWD NGLs (A, B, C), and 85% for EMD NGLs. This improvement will boost ethane feedstock for petrochemical companies from 2000 ton/day to 3500 ton/day, enabling increased polyethylene production. Economic analysis for the base case shows an expected internal rate of return (IRR) of 26%, a net present value (NPV) of USD 73 million, and a payback period of approximately 3 years. Sensitivity analysis on product prices, feed gas prices, and total capital investment confirms the project’s economic viability, with all cases showing feasibility (IRR ≥ 15%) except when product prices fall below USD 225/ton for propane, USD 215/ton for liquefied petroleum gas (LPG), and USD 25/bbl for condensate. This study highlights the potential for enhanced ethane recovery, offering substantial economic benefits and supporting the growth of Egypt’s petrochemical industry.

Optimal process selection for natural gas liquids recovery: Energy, exergy, economic, and environmental perspectives

In contrast with extant studies on industrial natural gas liquids (NGL) recovery processes, this study focuses on the most significant configurations, including the industry-standard single-stage (ISS) process, gas subcooled (GSP) process, cold residue gas-recycle (CRR) process, recycle split-vapor (RSV) process, enhanced NGL recovery process (IPSI-1), and internal refrigeration for enhanced NGL recovery process (IPSI-2). Furthermore, this study in-depth analyses the energy, exergy, economics, and environmental factors to determine the optimal configuration based on specific scenarios and priorities. ASPEN HYSYS® V11 is used to simulate six NGL process configurations, each with a processing capacity of 5000 kmol/h. The study identifies critical design variables concerning energy consumption. The energy analysis reveals that the RSV process exhibits the highest energy consumption, totaling 38.00 MW. Additionally, the RSV configuration demonstrates the highest values for exergy destruction, capital cost, CO2 emissions, and purity compared to the other configurations. In contrast, the IPSI-1 process exhibits significantly higher energy efficiency than the RSV process, with 46 % lower energy consumption and the lowest specific CO2 emissions (0.048 kg CO2/kg feed). However, the analytical values for the lowest or middle rankings differ depending on the perspectives considered. Thus, this study provides valuable methods for selecting a conventional technology based on investment, input resources, and sustainable output requirements.

An Inclusive Review on the Assessment of Different Techniques for Natural Gas Liquid Recovery

AbstractA comprehensive review is presented on the natural gas liquid (NGL) recovery process with emphasis on process description, energy requirements, NGL production, operating cost, and propane recovery. The industry standard single‐stage (ISS), recycle split vapor (RSV), cold residue reflux (CRR), and gas subcooled process (GSP) technologies focus on the improvement in the rectifying section of the demethanizer column, while the enhanced NGL recovery process (IPSI) focuses on the stripping section of the column. The fluor process consists of an absorber, a scrub column, and heavy hydrocarbon (HHC) separator, which form the integrated process of liquification and NGL separation. For rich feed, the economic performance, payback, and total annualized cost (TAC) of the IPSI process were lower than the other processes. For lean feed, the results of the scrub column scheme demonstrate the finest economic performance.

Membrane-assisted natural gas liquids recovery: Process systems engineering aspects, challenges, and prospects

Membrane-based natural gas liquid (NGL) recovery processes are still far from their large-scale applications owing to communication gaps among academic researchers and industry practitioners. A comprehensive process systems engineering (PSE) assessment of membrane-based NGL recovery processes is required to determine their commercial suitability. This PSE-based review presents the technical and economic aspects of standalone and integrated membrane processes. Literature review shows that polymeric membranes (e.g., cellulose acetate) are primarily evaluated in NGL recovery processes despite their low separation efficiencies. So far, multiple multistage membrane models with standalone and integrated designs have been suggested by analyzing different configurations to improve separation efficiency. In standalone processes, cellulose acetate membrane modules with high selectivity ratio can improve methane recovery by up to 100%. Absorption or cryogenic integrated processes exhibit high methane recovery (up to 99%) but demonstrate high energy consumption. The integrated absorption–membrane process is more capital cost intensive (i.e., 0.41 m$) than the cryogenic–membrane process (0.39 m$). Furthermore, in this review, the key challenges encountered by membrane processes and related issues are identified to improve their commercial viability by capitalizing on their maximum potential benefits. The major challenges associated with membrane processes constitute the lack of rigorous multistage membrane models and inflexibility in product purity and recovery. The policy implications and future directions suggest that owing to the growing demand for NGLs, membranes that can sustain varying natural gas compositions and conditions may be required. This PSE assessment will help process engineers and policymakers to improve natural gas supply chain economics.

Advanced exergy analysis of the natural gas liquid recovery process

Energy quality in each country is one of the important indicators of economic development, Which affects the economic growth of that country. Exergy analysis, considering all flow properties including pressure, temperature, composition, is a powerful way to evaluate the energy consumption of equipment such as natural gas and liquefied gas plants. Inefficiency of a system can be defined by the conventional exergy analysis method, while, irreversible resources and real potentials for system improvement can only be identified by the advanced exergy analysis method. This analysis splits conventional exergy destruction into two exogenous and endogenous parts according to origin, and also unavoidable and avoidable parts according to the ability to remove and modifications. In this method, the exergy concept was separated by considering the ideal and avoidable condition assumptions. As a real case study, a natural gas liquid plant 800, from National Iranian South Oil Company located in southwest of Iran was considered to be investigated by conventional exergy analysis, advanced exergy analysis methods. The results of conventional exergy analysis illustrated that the highest amount of exergy destruction belonged to compressor and heat exchanger with 509.99 kW and 629.04 kW, respectively. However, in the case of heat exchanger, despite having the highest rate of exergy destruction, it is not considered in modification priorities due to its low avoidable exergy destruction value. Also, advanced exergy analysis suggested that the exergy destruction of the compressor and heat exchanger will be reduced by improving performance of these components.

Design and Simulation of Natural Gas Liquid Recovery Process from Rich Natural Gas

Natural gas plays a growing role in the energy mix by displacing coal due to its relative economic and/or environmental advantages A process of natural gas liquid (NGL) recovery utilizing internally generated energy to achieve energy efficiency was designed. The process utilizes heat generated from the compressor end of the turbo-expander to provide heat energy required to maintain the appropriate operating conditions at the intermediate and bottom sections of the demethanizer column, rather than utilizing dedicated steam generators that requires additional construction, installation, operations and maintenance cost. Simultaneously, the temperature of the hot residue gas is also dropped to the required range for export, rather than utilizing dedicated process gas coolers. The various unit operations such as heat exchangers, liquid separators, Joules Thompson Valve coefficient, demethanizer column, reflux condenser, and bottom reboiler were designed, and cost evaluation performed for each unit, while models were solved using MatLab software. The quality and composition of NGL and residue gas produced are consistent with industrial process plant data. In addition, condenser and reboiler showed that the heat removed from the condenser is 3.180.5kW and 1.65m 2 area was exchanged, while the heat for the reboiler is 474.5kW at 47.25m 2 exchanged area. Also, the temperature profile of the demethanizer column is not uniform as lower temperature is required for the rectifying section (cryogenic absorption). Thus, temperature of -90 o C to – 95 o C favours the production of sales gas as the top product stream, while a temperature range of 30 o C to 36 o C at the bottom favours the recovery of NGL product as the bottom stream. The height and diameter of demethanizer column for distillation and absorption sections are 28m and 1.55m and 7.24m and 3m respectively. Keywords: Natural Gas Liquid, Heat Exchanger, Separator, J-T Valve, Demethanizer Column, DOI: 10.7176/CPER/64-04 Publication date: January 31 st 2022

Retrofit design of an industrial natural gas liquids recovery process based on the pinch technology concept

Energy consumption is increasing very rapidly, especially in the high-energy consuming industries such as oil, gas, and Natural Gas Liquids refineries. Pinch analysis as a well-established and successful technique is used to improve the energy efficiency of the above-mentioned plants. However, the limitations on ΔTmin and those related to the technical and economic aspects result in the lack of capability by the pinch analysis in reducing the utility beyond a specific amount. Also, this analysis only uses the existing process streams and cannot identify and develop high potential streams reducing the external utility consumption. Opportunities for saving energy consumption would increase through the self-refrigeration methods, and they further decrease the utility consumption. Moreover, for minimizing the process changes, the Heat Exchanging Network should be optimized by pinch analysis and then, the opportunities for self-refrigeration of the process should also be challenged. Thus, the present study was conducted to consider the opportunities for reducing the energy consumption and the required utility in a real-life case study of a Natural Gas Liquids plant. Finally, the heat exchanging network redesigned by the grass root plant was revamped with side streaming from the demethanizer column by changing the ΔTmin to 3 °C resulting in the provision of an additional refrigeration stream for inlet feed instead of external utility. This scheme resulted in saving 3671 kW of refrigeration compressors shaft work and saving 6100 kW of the needed energy for the reboiler and condenser. As the result, 546 kW (53 %) of the plant's total energy consumption will be saved by the pinch and self-refrigeration scheme. The total savings in the purchased equipment costs and operating costs saving of the NGL plant are equal to 3,891,560 (USD) and 3,757,451 (USD/year), with 378 days' payback period.

Dynamic simulation and control of Natural Gas Liquids recovery process

As Natural Gas Liquid (NGL) recovery process produces methane-rich gas from C2+ liquids at high pressure and sub-ambient temperature, it is important to implement robust process control schemes for ensuring operating integrity and process safety. The study aims to assess a range of control schemes and their dynamic characteristics for the NGL recovery process, and to determine the most appropriate and effective process control scheme. Equipment sizing have been made through steady state modeling and equipment-specific process design, with which dynamic model for the NGL process has been constructed. Dynamic responses and safety issues are investigated for each control scheme by changing feed flowrate and composition. Emergency scenarios occurred by malfunction or local control error have been addressed with dynamic model and the control scheme selected, for improving process operability and safety in practice. The systematic implementation of control structure with appropriate actions allows to enhance sustainability of NGL recovery processes by reducing unwanted waste generation and minimizing unnecessary energy usage.

Improving NGL recovery process with dividing-wall column for offshore applications

Fractionation process within natural gas processing facility is an essential step that allows to obtain liquid light hydrocarbons that are often used as feedstocks in petrochemical industries. In this article, a process scenario that includes a heat integrated distillation column is proposed for natural gas liquids (NGL) recovery and assessed through multiscale simulations. Aspen HYSYS software was used to develop steady state process models whose results were used to estimate capital and utility costs. It was noticed that the proposed process has the highest capital cost and lower operating cost which reduces remarkably the total annual cost, this process can also achieve 60 % ethane and 97 % propane recoveries with no additional of external refrigeration. Heat integration, low TAC, separation efficiencies for ethane and propane components, self-refrigeration and more importantly a possibility of operating the process in ethane recovery and ethane rejection modes are the main highlights of the proposed NGL recovery process.

Optimization and Exergy Analysis of Natural Gas Liquid Recovery Processes for the Maximization of Plant Profits

AbstractMaximizing the profits of natural gas liquid recovery plants is a challenge. To improve the performance of an existing plant, three process schemes were compared and analyzed with Aspen HYSYS. A high‐pressure absorber (HPA) performed better owing to the added compressor and more reasonable cold energy utilization. The HPA was further optimized by establishing an objective function and identifying and adjusting the main variables on the basis of a new optimization algorithm. The propane recovery of the optimized HPA was 98.8 %, and the plant profitability increased by 3352 million $ a−1. Exergy analysis of the optimum process indicated that the column and air cooler contributed the most to the total exergy destruction. Suggestions for decreasing the exergy destruction of the process are also given.

Economic evaluation of NGL recovery process schemes for lean feed compositions

The economic analysis of lean feed conditions for natural gas liquids (NGL) recovery is required to meet recent increases in the demand for lean gas reservoirs. This paper compares the economic performance of various NGL recovery schemes with consideration of the LNG HHV specification under various lean feed compositions. The ISS and IPSI schemes are typical processes in NGL recovery, especially in the normal and rich fields, whereas HHC separator and scrub column schemes have advantages for lean feeds. All the schemes were built by HYSYS simulation software and optimized using a genetic algorithm. The profitability analysis indicates that the gross profit and payout time give a similar trend compared to the previous studies. However, the results give different outcomes when considering total annualized cost (TAC), especially in terms of lean feed condition. The results show that scrub column scheme shows the best economic performance compared to other schemes under lean feed compositions.

Development of energy-efficient processes for natural gas liquids recovery

A new NGL (natural gas liquids) recovery process configuration is proposed which can offer improved energy efficiency and hydrocarbon recovery. The new process configuration is an evolution of the conventional turboexpander processes with the introduction of a split stream transferring part of the feed to the demethanizer column. In this way additional heat recovery is possible which improves the energy efficiency of the process. To evaluate the new process configuration a number of different NGL recovery process configurations are optimized and compared using a process simulator linked interactively with external optimization methods. Process integration methodology is applied as part of the optimization to improve energy recovery during the optimization. Analysis of the new process configuration compared with conventional turbo-expander process designs demonstrates the benefits of the new process configuration.

NGL supersonic separator: modeling, improvement, and validation and adjustment of k-epsilon RNG modified for swirl flow turbulence model

The processing of natural gas requires the implementation of new technologies in a context of increasing demand around the world. The natural gas liquids (NGL) separation using supersonic devices is a novel and efficient way to reduce volume of installed equipment and operation costs using the effects of highly turbulent and circular flows. This research implemented Computational Fluid Dynamics (CFD) modeling to improve the efficiency of typical NGL recovery process using the supersonic approach. In this research, a novel turbulence modeling approach was implemented aiming to minimize the processing time, and the results obtained were validated with experimental data available. This research is based on the model called k-epsilon RNG modified for swirl flow, this model has not been used and validated previously in highly compressible, turbulent and circular flow systems. The efficiency of the process was improved by 11% in comparison to the efficiency reported in past studies, and the processing time for the modeling was reduced by 40% with the proposed and adjusted turbulence approach. During the validation of the model k-epsilon RNG modified for swirl flow the swirl factor, part of the turbulence model, was adjusted to an optimum value for compressible, turbulent and circular flow systems involved in supersonic NGL separation process, allowing accurate results to be obtained with lower processing time than with other typical and common approaches as RSM and LES.

Exergy analysis of an ethylene refrigeration cycle integrated with a NGL recovery process for a large LNG train

The natural gas liquefaction process consists of a sequence of refrigeration cycles that consumes a considerable amount of energy. The separation of natural gas (NG) from the natural gas liquids (NGL) is considered to be one of the significant parts in the liquefaction of natural gas, as this will influence the LNG product quality. The integration of NGL section with the liquefaction process is one of the fundamental ways to improve the efficiency of the process and provide economic benefit from operating and capital cost perspectives. In this extended abstract, two different configurations of NGL section integrated with the ethylene refrigeration cycle for the Cascade LNG plant—processing 5 million tonnes per annum (MTPA)—are proposed. The objectives of the proposed concepts are to meet the LNG higher heating value (HHV) specification and to achieve minimum power consumption for the refrigeration cycle. Exergy analysis is used as a thermodynamic tool to evaluate the efficiency of the process. The process was simulated using Aspen HYSYS and the results of the proposed configurations are presented and analysed. The proposed configurations can be used to produce LNG and NGL with minimum energy consumption.

Risk-based optimization for representative natural gas liquid (NGL) recovery processes by considering uncertainty from the plant inlet

The need to reduce energy requirement and improve operational flexibility of the NGL recovery process is a challenging problem. Different design options have been developed over the past four decades. This paper presents optimization of six selected process schemes subject to various upstream feed conditions. The process schemes were chosen for their numerous advantages such as future forefront, wide application and commercial availability. HYSYS process models were constructed for each process schemes under common sets of criteria. The information was then transferred to GAMS for optimization. One year real feed plant data was used to examine the performance of the process schemes. The results from single chance constrained optimization showed that the enhanced NGL recovery process (IPSI-1) provides a very competitive profit value with only a 6% risk of violating constraint compared to gas sub-cooled process (GSP) scheme (28%). On the other hand, profit value obtained from the joint chance constrained optimization for GSP was higher than IPSI-1 with a competitive risk of violating constraint 33% and 26%, respectively. Flexible decision to produce more sales gas or NGL product could be made before the plant operation by looking the profit value and its corresponding risk of violation of a constraint.

Techno-economic evaluation of a novel NGL recovery scheme with nine patented schemes for offshore applications

A novel configuration of natural gas liquid (NGL) recovery process is proposed for offshore applications. Nine representative patented NGL recovery processes were chosen and their heat integration was modified for offshore applications. Detail techno-economic analysis of the proposed configuration was performed on these selected conventional NGL recovery processes. The results suggest that the proposed NGL configuration is most efficient among all the processes considered in terms of the operating and capital cost. The cold residue recycle and flashed vapor reflux process had the highest and lowest capital cost requirement among other processes. The excellent heat integration and sharp separation efficiency of the heavier components are the main highlights of the proposed NGL recovery process.

Application of exergy analysis for improving energy efficiency of natural gas liquids recovery processes

Thermodynamic analysis and optimization method is applied to provide design guidelines for improving energy efficiency and cost-effectiveness of natural gas liquids recovery processes. Exergy analysis is adopted in this study as a thermodynamic tool to evaluate the loss of exergy associated with irreversibility in natural gas liquids recovery processes, with which conceptual understanding on inefficient design feature or equipment can be obtained. Natural gas liquids processes are modeled and simulated within UniSim® simulator, with which detailed thermodynamic information are obtained for calculating exergy loss. The optimization framework is developed by minimizing overall exergy loss, as an objective function, subject to product specifications and engineering constraints. The optimization is carried out within MATLAB® with the aid of a stochastic solver based on genetic algorithms. The process simulator is linked and interacted with the optimization solver, in which optimal operating conditions can be determined. A case study is presented to illustrate the benefit of using exergy analysis for the design and optimization of natural gas liquids processes and to demonstrate the applicability of design method proposed in this paper.

A novel conceptual design by integrating NGL recovery and LNG regasification processes for maximum energy savings

Natural gas liquids (NGL) recovery from shale gas needs large amounts of cold energy for cooling, while liquefied natural gas (LNG) regasification requires tremendous hot energy for heating. Thus, recycling the cold energy from LNG regasification process at a receiving terminal to assist the NGL recovery process has great economic benefits on both energy saving and high‐value product recovery. A novel conceptual design by integrating NGL recovery from shale gas and LNG regasification at receiving terminals has been developed. It first generates a process superstructure. Then, a simulation‐assisted mixed‐integer linear programming (MILP) model is developed and solved for the optimal process synthesis. Next, heat exchange network (HEN) design and analysis are performed to accomplish the maximum energy‐saving target. Finally, rigorous plant‐wide simulations are conducted to validate the feasibility and capability of the entire conceptual design coupling of separation and heat integration. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4673–4685, 2013

A novel NGL (natural gas liquid) recovery process based on self-heat recuperation

This study examined an innovative self-heat-recuperation technology that circulates latent and sensible heat in the thermal process and applied it to the NGL (natural gas liquid) recovery process. A CGCC (column grand composite curve) was used to assess the thermodynamic feasibility of implementing the heat pump system and self-heat-recuperation technology into a conventional distillation column. The proposed distillation based on self-heat recuperation reduced the energy consumption dramatically by compressing the effluent stream, whose temperature was increased to provide the minimum temperature difference for the heat exchanger, and circulating the stream heat in the process. According to a simulation of the proposed sequence, up to 73.43 and 83.48% of the condenser and reboiler energy, respectively, were saved compared to a conventional column. This study also proposes heat integration to improve the performance of self-heat recuperation. The results showed that the modified sequence saves up 64.35, 100.00 and 31.60% of the condenser energy requirements, reboiler energy requirements and OP (operating cost), respectively, compared to a classical heat pump system, and 90.24, 100.00, and 67.19%, respectively, compared to a conventional column. The use of these sequences to retrofit a distillation column to save energy was also considered.

Process Design of Natural Gas Liquid Recovery Processes

This research was supported by a Floating Production Platform Topside Systems and Equipment Development Grant from the MOTIE (Ministry of Trade, Industry and Energy) of the Korean government.