Aspen HYSYS V8 Research Articles

Techno-Economic Study of Retrofitting Ammonia Unit to Reduce Carbon Dioxideemission in a Typical Fertilizer Plant

This research presents a comprehensive techno-economic study of the CO2 removal section of a 3850 MTPD ammonia unit in a typical fertilizer plant. The focus is on retrofitting the CO2removal section with a flash gas scrubber to capture significant CO2losses to the reformer fuel header and fuel gas. The captured Carbon dioxide is utilized in the downstream Urea Plant, enhancing the heating value of fuel gas and reducing environmental emissions. Aspen Hysys V8.8 was employed for simulation, using Activated Methyl Diethanolamine (AMDEA) as the absorbent. The results indicate a 95% Carbon dioxide absorption with the installed flash gas scrubber. Design parameters, economic evaluations, and savings calculations were carried out using Excel and Aspen Process Economic Analyzer. The payback period for the project is estimated to be 20 and 21 months for undiscounted and discounted scenarios, respectively. AutoCAD was used for the mechanical drawing of the flash gas scrubber.

Study The Effect of The Main Variables on The Objectives of The Natural Gas Dehydration Plant by ASPEN-HYSYS v8.8

In the NGD process, TEG dehydration is commonly employed to prevent corrosion and blockage of equipment, valves, and piping systems. TEG is frequently lost in the system during this procedure owing to vaporization and carryover. Therefore, it is necessary to study the affection of variables of the dehydration process the process was simulated with ASPEN-HYSYSV8.8 and the thermodynamic model was glycol-package; the process was validated by comparing the Plant results with the simulation results and demonstrating good acceptance. ASPEN-HYSYS conducted a sensitivity study to investigate the impact of variables on the main objectives. , as this study showed that not all of these variables have a strong effect, some of them have a weak effect, for example (wet gas pressure and same case of solvent pressure) and the rest of the variables have a strong effect on this process, so it must be taken into consideration by the station operators where this The changes were targeted because they are subject to change within the plant, and the highest value and the smallest value were taken according to the factory's parameters. As these variables are taken into account and the requisite improvements are made, the natural gas drying process will improve, and the dry gas requirements needed will improve, resulting in increased benefit.

Optimization of Flow Rate TEG (Triethylene Glycol) in Absorbing Water Levels in Glycol Contactor (V-5400) With ASPEN HYSYS Simulation

The purpose of this research is to determine the amount of TEG flow rate required to get dry gas with a moisture content consistent with industry requirements and to determine how much water content is absorbed in dry gas after TEG flow rate optimization. The glycol contactor (V-5400) is the primary piece of equipment for this activity, and the materials are dry gas and TEG solution in the dehydration unit. The research method employed is descriptive quantitative simulation via the use of the Aspen HYSYS V8.8 application tool. According to the simulation findings on the glycol contactor (V-5400) using Aspen HYSYS, in order to get dry gas with a moisture content of 4-7 lb/MMscf, a TEG solution with a flow rate of 2.4 ft3/min and a water content of 2.4 ft3/min is required. absorbed following flow rate optimization TEG is used to convert 7.6026 lb/MMscf water content to 6.7881 lb/MMscf water content with a percentage difference of 0.8145, but real data converts 7.4702 lb/MMscf water content to 6.6984 lb/MMscf water content with a percentage difference of 0.7718.

Concept and evaluation of energy-efficient boil-off gas reliquefiers in LNG carrier ships propelled by dual-fuel engines

Ships carrying liquefied natural gas (LNG) are generally propelled by dual-fuel enginesthat use boil-off gas (BOG) or diesel as fuel. Fuelling the engine with pumped and vaporized LNG is operationally more convenient than compressing BOG. BOG is usually reliquefied using reverse Brayton cycle (RBC) or Claude cycles. In this paper, both these cycles are reconfigured to extract the cold of pumped LNG to reduce power consumption. Steady-state simulations are done on process simulator Aspen HYSYS V8.6®. Capturing the cold from the LNG fuel improves the exergy efficiency of RBC and Claude reliquefiers from 37.8% to 57.5% and 48.5% to 75.6% respectively. The surface area of heat exchangers in the Claude system is one-third that of RBC. Mass flow through compressor and turbine in Claude system is one-fifth and one-ninth of RBC, while volume flow at turbine inlet is only one-fourteenth in the Claude system.The evaluation shows that all equipment needs to be designed with sufficientoperational flexibility to enable the system toextract cold effectively from the LNG fuel supply because it varies widely during the voyage. Claude system with cold extraction from LNG fuel is highly compact and the most efficient reliquefier designed so far.

Techno‐economic assessment and sensitivity analysis of biodiesel production intensified through hydrodynamic cavitation

AbstractSince the last two decades, hydrodynamic cavitation has been introduced as one of the most efficient approaches to intensify transesterification. However, the number of industrial biodiesel plants utilizing this process is still minimal. One primary reason is the lack of information on both its economic and environmental impacts. In this study, a simulation‐based model was developed using Aspen HYSYS V8.4 for comparing flow‐through hydrodynamic cavitation with conventional mechanical stirring in terms of total capital investment, total product cost, net present value, modified internal rate of return, materials, and energy consumption. The two plants operated 7920 hours per year and produced 100 tons of biodiesel per day from fresh sunflower oil. The results showed that total capital investment and total product cost for hydrodynamic cavitation were roughly 65% and 10% lower than those for the mechanical stirring process, respectively. While the net present value was negative for the mechanical stirring, a positive net present value and a modified internal rate of return of 25.61% were obtained in the hydrodynamic cavitation process. Performing sensitivity analysis using the Box‐Behnken design and response surface methodology revealed that net present value was most affected by the linear term of the sunflower oil price. It was also found that hydrodynamic cavitation could significantly reduce materials and energy consumption, owing to higher reactor yield and lower alcohol and catalyst consumption.

Modelling Production of Renewable Energy from Water Splitting High Thermal Electrolysis Processes

Recently, fuel gas from water has become the center of attention because it is a renewable source of energy and eco-friendly. In this study, the hydrogen gas simulated was obtained from the high-temperature water splitting electrolysis model, because it is more efficient than the low-temperature water splitting electrolysis process. It also releases oxygen as a byproduct. The high-temperature electrolysis model is made up of three loops: primary high-temperature helium loop, secondary helium loop, and high-temperature electrolysis loop. Hydrogen gave a temperature of 27.20C, a pressure of 49.5 bars, and a molar flow of 84.02MMSCFD. The hydrogen gas from a high-temperature electrolysis model is simulated with a CO2 gas stream to produce methane and water, also releasing unreacted carbon dioxide and hydrogen. Key parameters such as molar entropy, molar enthalpy, heat flow, and cost flow were evaluated by Aspen HYSYS V8.8. The simulation model used for this work is the Sabatier Process Model. In this model, Continuous stirred tank, Converter, Equilibrium, Gibbs, Plug flow reactors were used to generate methane. The Converter reactor gave the highest yield of methane gas with a mole fraction of 0.2390. Key benchmarks, including temperature, heat flow, cost flow, cost factor were varied to see how they can affect methane gas and other products.

Modelling Production of Renewable Energy from Water Splitting High Thermal Electrolysis Processes

Recently, fuel gas from water has become the center of attention because it is a renewable source of energy and eco-friendly. In this study, the hydrogen gas simulated was obtained from the high-temperature water splitting electrolysis model, because it is more efficient than the low-temperature water splitting electrolysis process. It also releases oxygen as a byproduct. The high-temperature electrolysis model is made up of three loops: primary high-temperature helium loop, secondary helium loop, and high-temperature electrolysis loop. Hydrogen gave a temperature of 27.20C, a pressure of 49.5 bars, and a molar flow of 84.02MMSCFD. The hydrogen gas from a high-temperature electrolysis model is simulated with a CO2 gas stream to produce methane and water, also releasing unreacted carbon dioxide and hydrogen. Key parameters such as molar entropy, molar enthalpy, heat flow, and cost flow were evaluated by Aspen HYSYS V8.8. The simulation model used for this work is the Sabatier Process Model. In this model, Continuous stirred tank, Converter, Equilibrium, Gibbs, Plug flow reactors were used to generate methane. The Converter reactor gave the highest yield of methane gas with a mole fraction of 0.2390. Key benchmarks, including temperature, heat flow, cost flow, cost factor were varied to see how they can affect methane gas and other products.

Exergetic analysis of reverse Brayton cryocooler with different turbine arrangements for HTS power cables

The cooling systems of High-Temperature Superconducting (HTS) power transmission cables are unable to achieve the desired performance as prescribed in the cryogenic road map. Reverse Brayton cycle based Cryocooler (RBC) has been identified as a refrigerator that has the potential to achieve the desired performance for higher cooling load demand. In this article, an exergy analysis of the basic Reverse Brayton Cycle (RBC) and its modifications has been investigated for identification of appropriate cycle configuration that will meet the demand for practical applications of HTS cables. The modifications in the basic cycle are carried out with different arrangements of turbines such as parallel or series expansion that may increase the exergy efficiency of the cooling system with a heat load of 10 kW @ 65 K. The analysis is carried out using Aspen HYSYS V8.6, and helium is used as a working fluid. The effects of important process parameters such as pressure ratio, compressor inlet pressure, and flow diversion on the performance are investigated and are used to optimize these cycles. The best cycle configuration based on RBC is identified and recommended based on the results of the analysis.

Effect of precooling with transcritical CO2 cycle on two types of LNG boil-off gas reliquefaction systems

Precooling improves the performance of boil-off gas reliquefiers in LNG carrier ships. However, net savings of power, additional space and capital cost and fire-safety are some of the factors that decide the choice of precooling system. Carbon dioxide (CO2) may be a preferred refrigerant for offshore systems as it is non-toxic, non-flammable and has lower global warming and zero ozone depleting potential. In this paper, CO2 refrigeration cycle is integrated with reverse Brayton cycle based indirect reliqufier and also with Claude cycle based direct reliquefier. Performances of these systems are compared with reliquefaction systems integrated with vapour compression cycles working on flammable refrigerants. All options of precooling are evaluated using exergy analysis after simulating them in Aspen HYSYS V8.6®. Upon precooling with transcritical CO2 cycle, reverse Brayton and Claude systems show improvements in exergy efficiency by 7.5% and 7.0% respectively. A low precooling temperature suits reverse Brayton system. However, Claude system demands an optimum precooling temperature (280 K) to maximise the exergy efficiency that suits the use of a transcritical CO2 precooler. Though precooling with ethylene-propylene cascaded vapour compression cycles may further improve the performance of reliquefiers, the flammability factor may stand on the way of its selection for onboard systems.

Simulation and Capacity Evaluation of Refinery Flare System and Comparative Analysis of Carbon Capture Technologies

In refinery flare system is the last defense line for controlling over-pressurization of process vessels. Mostly power failure is the worst contingency in the refinery, and the flare capacity is evaluated for this case. The data of pressure safety vessels (PSVs), header network, knockout drums, flare stack and flare tip is to utilize for simulating the flare system of oil refinery complex (ORC-II). Carbon dioxide (CO2) is a significant benefactor in the global warming stances a severe hazard to environment. The procedure was conveyed using 30 wt. % monoethanolamine (MEA) dissolvable and Hollow-fiber cellulose acetic membrane framework. This research consists of two sections. The initial segment the capacity evaluation of the flare framework was finished utilizing Aspen Flare System Analyzer V8.4 and rating of flare framework was conveyed in which to break down the necessary parameters like Mach number and back weight in the system and the adjustments in the flare framework were made as per API 520. In the second part chemical absorption and membrane separation innovations were looked at for post-combustion carbon catch. The research focuses on conveying relative investigation of above-expressed methods for flow rate of vent gas runs between 1 to 200 MMSCFD. The goal is to accomplish 90% recuperation of CO2 with carbon decrease from 10.66 mole % to 2 mole %. The absorption technique is simulated by ASPEN HYSYS V8.4 and program for membrane framework is created by connecting values from ASPEN HYSYS to Microsoft EXCEL. For membrane separation the operating expense is seen as lower than absorption process, yet from the results it was concluded that the absorption technique is superior to membrane technique until the problems concerning degradation of membrane and high capital expense would be settled.

Thermodynamics and Kinetics Study of Diethyl Carbonate (DEC) Synthesis from CO2, Ethanol, and Epoxides with Various Catalysts

Carbon dioxide (CO2) has been the main contributor for global warming over the past decades. However, it can potentially be utilized as raw material of valuable products, such as organic carbonate compound namely diethyl carbonate (DEC). Formation of DEC via indirect route from CO2 and ethanol is accompanied with epoxides as dehydrating agent. This work has been devoted to study thermodynamics and kinetics of indirect DEC synthesis using ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO) with various catalysts. Data from scientific journals and previous experiments conducted at Laboratory of Thermodynamics, ITS were analyzed in this study. Based on the value of (ΔG), it was found that indirect synthesis using EO is the most spontaneous reaction, followed by BO and PO, respectively. Simulation using Aspen HYSYS V8.8 also reveals that reactant and product system after 3 hours of reactions falls into vapor-liquid region and superheated region. Meanwhile, kinetics evaluation of experiment using PO and KI/EtONa catalyst showed that the aforementioned reactions are exothermic due to decreasing value of reaction constant upon reaching certain temperature. Based on Arrhenius equation while presuming that the reaction is elementary and non-elementary, activation energy was estimated as 55.62 kJ/mol and 54.80 kJ/mol, respectively. Furthermore, the use of KI/EtONa as catalyst resulted the highest yield among other catalysts namely KI, KI/CeO2, and KI/Zeolite.

Selection of optimal fluid for refrigeration cycles

Refrigeration and air-conditioning play an important role in our life and industrial applications. They have great impact on our life. They have also contributed to the world’s major environmental issues like ozone layer depletion and global warming. Common refrigerants such as CFCs and HCFCs which are working as fluid in refrigeration cycles have unfavorable environmental impacts and this has brought about concerns and regulations prohibiting their production and use as refrigerants by the year 2030. The development of different refrigerants over time took place based on safety and environmental impact issues. This paper, presents the selection of optimal working fluids for Vapor-Compression Refrigeration Cycle (VCRs) based on computer aided molecular design (CAMD) and process optimization techniques. The resulting methodology utilizes from CAMD for the generation of optimum working fluid candidates. Candidates were evaluated as alternative refrigerants for the R134a refrigerating system through simulation using Aspen Hysys V8.0, with restricted by priority coefficient of performance COP, environmental and safety criteria. Ethyl trifluoromethyl ether 1,1,1-TrifluoroButane (new refrigerant) shows a good environmental and toxicity data also have high COP, 4.5, 2.7 respectively and were favored amongst the studied refrigerants as the choice alternative refrigerants to replace R134a. The methodology systematically identified conventional molecular structures that enable optimum VCRs process performance.

Techno-economic assessment of biodiesel production from canola oil through ultrasonic cavitation

The immiscibility of oil and alcohol is a severe issue in biodiesel production as it causes a low mass transfer rate and long reaction time. This problem can be overcome by incorporating the intensification method, which significantly increases the contact surface area of oil and alcohol through various techniques. In recent years, ultrasonic cavitation has emerged as one of the most effective ways for this purpose. However, it is still unclear whether this technology will provide the industry with an economically profitable process. This paper attempts to assess the potential of ultrasonic cavitation from a techno-economic viewpoint. Two plants based on the conventional mechanical stirring and ultrasonic cavitation processes were designed using Aspen HYSYS V8.4. Total investment, costs of products, net present value, and internal rate of return were used to compare the two processes together. The total investment in the ultrasonic cavitation process was lower than that of the mechanical stirring process by approximately 20.8%. Compared to the conventional process, using ultrasonic reactors also caused products’ costs to reduce by 5.2%. Owing to a positive net present value and an internal rate of return of 18.3%, the ultrasonic cavitation process was a better choice. Moreover, ultrasonic cavitation resulted in a meaningful decrease in both consumed energy and the production of wastes. The overall energy consumption was reduced by 6.9% when ultrasonic cavitation was employed. The amount of waste produced in the ultrasound-assisted process was one-fifth of that in the mechanical stirring process.

Techno-economic assessment of Fischer-Tropsch synthesis and direct methane-to-methanol processes in modular GTL reactors

The aim of this study is to perform a techno-economic assessment of the Fischer-Tropsch synthesis (FTS) process in a microchannel reactor (MCR) to produce clean syncrude, and the Direct Methane to Methanol (DMTM) process in a compact plant footprint. The operational and economic performances of the two processes were modeled using the Aspen HYSYS v7.2. The operational performance parameters include products yield and the economic performance parameters include net present value (NPV), payback period (PBP) and internal rate of return (IRR). In addition, the effects of tailgas recycle ratios and water integration on the performances of the FTS process and the effect of methane recycle ratios on the performances of the DMTM were investigated. The simulation results showed that the unit cost of the DMTM process was sensitive to the methane recycle ratio, however, that of the FTS in MCR was less sensitive to the tailgas recycle ratios. In order to maintain an IRR > 10 %, the tail gas recycle ratio of the FTS in MCR had to be greater than 8 % and 30 %, at CO conversions of 80 % and 72 %, respectively, whereas in the DMTM process, a minimum methane recycle ratio of 60 % was required to achieve any profitability. In addition, the DMTM process appeared to have significantly higher net energy requirements per product yield when compared with those of the FTS in MCR process; however, both processes had higher energy requirements than those of conventional GTL technologies.

Thermo-economic analysis of PEM fuel cell fuelled with biomethane obtained from human waste by computer simulation

Fuel cells, especially Proton Exchange Membrane (PEMFC) is considered as perfect alternative energy source that can either replace or complement existing energy source which is fossil fuel. However, the technology is still at developmental stage due to the lack of availability of fuel sources that is safe and economical. This study, therefore focused on thermo-economic analysis of PEMFC fuelled with biogas from human waste. To achieve the purpose of this study, thermo-economic analysis was used to analyse PEMFC designed to generate 1.45 MW of electricity from domestic human waste. The stages involved are biogas generation, hydrogen production and fuel cell application. The processes were modelled using Aspen HYSYS V8.8, a software developed by Aspen Tech®. The Hydrogen was produced at a rate of 358 kgmole/h, temperature of 330 K, pressure of 4.8 bar and 99% purity from the Preferential oxidation (PrOx) exit stream. Data generated from the simulation model were subsequently used for the thermodynamic and economic analysis and a fuel processor efficiency of 83.5% was obtained. Energy analysis of the process showed that the principle of energy conservation was satisfied, requiring and producing energy simultaneously and a net electrical efficiency of 42.32% was realized, while the result of exergy analysis showed that the unit associated with high irreversibilities and maximum exergy destruction is the steam generator. From the economic analysis, a rate of return of 20% was realized which is an indication that the investment is safe and profitable. The general overview of the processes based on economic and thermodynamics performance shows that the investment is worthwhile and indeed waste can be turned to wealth.

Comparison of Refrigeration Cycles at 28–30 K

A comparative analysis of refrigeration cycles for supporting actual loads at temperatures around 28–30 K is presented. Within this temperature range, such cryoagents as Ne, He, H2, D2 and Ne-He mixture can be used. Refrigeration cycle simulations using various cryoagents were performed using the Aspen HYSYS V8.8 software package.

Use of dual pressure Claude liquefaction cycles for complete and energy-efficient reliquefaction of boil-off gas in LNG carrier ships

Onboard reliquefaction of boil-off gas (BOG) generated due to heat in-leak in LNG carrier ships saves its calorific value and protects environment. Direct cryogenic liquefaction cycles, which use BOG as the working fluid, have the potential to reduce power and size of the system much below the level of existing reverse Brayton refrigerator-based reliquefiers. Though cryogenic liquefiers are not used for liquefaction of natural gas because of large changes in composition of mixture gases after Joule-Thomson expansion in direct liquefaction, it can be safely employed for BOG reliquefaction because large LNG volume acts as the buffer maintaining the composition of BOG throughout the voyage that consists primarily of methane and nitrogen only. Systems are simulated on Aspen HYSYS V8.6®. Dual pressure Claude cycle at BOG compressor exit pressure of 60 bara show 53.7%, 29.5% and 16.3% higher exergy efficiency when compared with reverse Brayton based, Cascade based and mixed refrigerant based indirect reliquefiers respectively. Heat exchanger sizes reduce with increased BOG compressor pressure. Economic analysis of the cryogenic BOG reliquefier with 60 bara compressor pressure shows about 2 years period of return on investment.

Simulation of Ammonia Production using HYSYS Software

Now-a-days, Because of cost and time consuming in the design of plants chemical engineer used simulators to simulate design and operation of chemical equipment and plant, which spares a great deal of time and cash.Today, there are many number of the simulators are refreshed and utilized in the simulation of chemical equipment and plant such as ChemCad, ProII, UniSim……..etc. Among of these simulators, Aspen Hysys is the most utilized programming in all ventures because of aiding in two noteworthy fields (design & operation). Simulation of ammonia synthesis process is done on Aspen Hysys V8.8 with steady state mode making some assumptions and using hypothetical reactors ammonia. By fluctuating the distinctive parameters in this simulation environment, the impact of these parameters in the generation rate of the procedure are watched. Keywords: Ammonia, Simulation, Aspen Hysys DOI : 10.7176/CPER/62-03 Publication date: January 31 st 2020

Synthesis of water capture technologies for gas fired power plants in Qatar

Flue gas from gas fired power plants contains 10–16% (w/w) water vapor with considerable amount of latent heat. Although CO2 capture and utilization have received great attention, water capture from power plant has received limited attention. The power plants in Qatar exhaust 33Millionm3 of water per year. This paper explores selected alternative technologies namely absorption, compression & cooling, and quenching, to enable the recovery of water vapor contained in a base case 750MW power plant flue gas streams. The alternatives for water capture were modeled and optimized over a wide range of operating conditions (pressure, temperature, and flow rate). Using data from an actual gas fired power plant in the state of Qatar, simulation studies were carried out and optimized for all modeled technologies to minimize production cost using Aspen HYSYS V8.6. The results show that the quench unit, operated at pertinent water circulation temperature (50°C), pressure (6 atm), and flowrate of 3500m3/h (recyclable), can extract up to 80.7% of the water in the flue gas. Apart from production cost and water capture percentage, criteria used to screen the alternative technologies were payback period, CO2e emission and brine reduction rate. The research work determined that the quench alternative had the lowest payback period (8.8 years), lowest CO2 emission rate (13kgCO2/m3 H2O) and highest brine reduction (3.44%) among all the tested alternatives. The proposed quench water-recovery technology will have added value to Qatar and other nations with limited water resources, specifically those with access to natural gas resources.

Optimization of Control System of Petroleum Refinery Isomerization Unit by Plant-Wide Control Principles

Industrial process control system due to integration of equipment, existing material and energy recycle streams and their effects are extraordinary importance. The process in terms of safety, product quality and control stability have a challenge when there was defects in a process control system. The isomerization process is gaining importance in the presence of refining context due to upgrading the octane number of light naphtha fractions and also simultaneously reduces aromatic compounds especially benzene content. In this study, the isomerization unit control system of Imam Khomeini Oil Refinery Company (IKORC, shazand, Iran), by defined four controllers include: the temperature controller on pre-heater exchanger, the concentration controller on depentanizer, deisopentanizer and deisohexanizer towers. This work is based on the nine principles of the plant-wide process control, was investigated. It should be noted that currently lack these four controllers in isomerization unit, confront this unit to challenge in dealing with sudden disturbances. The results show that obtained data from dynamic simulation by Aspen Hysys v7.3 had an acceptable compliance with the principles of plant-wide process control theory.