Process Simulation Program Research Articles

Pilot testing of water utilization for integrated solar energy storage and power production using linear Fresnel collector and organic Rankine cycle

This work presents a new method of utilizing water as thermal energy storage to improve the capacity factor of integrated linear Fresnel collector – organic Rankine cycle (LFC-ORC). A new process flow diagram has been proposed to manage overnight operation of the ORC relying on thermal energy storage in water. Pilot testing of 10 kW capacity of LFC-ORC process under arid and desert conditions of Arabian Gulf operating conditions (Qatar) is also reported. A thermodynamic analysis has been performed based experimental evaluation and process simulation of the LFC-ORC production and efficiency. The LFC-ORC operations at storage temperatures of 170 °C showed peak electricity production of 6.76 kW (38 W/m2 aperture area of LFC) whereas 1st law, and 2nd law efficiencies were 6 % and 19 %, respectively. An operational strategy is proposed to generate 5 kW over a period of about 12 h using 10 m3 storage capacity. The developed process simulation program showed that two LFC systems, each 176 m2 aperture area, equipped with three storage tanks each 10 m3, must be installed to generate 5 kW electricity for 24 h. The proposed system can be upscaled to any size as per end-user needs. The new system design would be subjected to further optimization and feasibility to cope with the development of the ORC and LFC efficiency in the future.

Undefined xylose media extracted from biorefinery waste for enhanced and eco‐friendly production of cephalosporin C by Acremonium chrysogenumM35

AbstractXylose‐rich undefined broth, extracted from the dilute acid pretreatment wastes of barley straw, serves as resourceful media for Acremonium chrysogenum M35 culture and production of cephalosporin C (CPC). Concentrating the extract with proper reprocessing enables to prepare various concentrations of xylose broth (2%–8%). The undefined xylose media were prepared for CPC production from A. chrysogenum M35 by the addition of other nutrients. Cell growth and CPC production were the most effective at 6% xylose and additional 2% glycerol, with maximum CPC production of 9.07 g/L after 6 days, which is higher production than that in defined media prepared with laboratory‐level nutrients and reagents. Investigation of autotrophic and reverse trans‐sulfuration pathways for cysteine synthesis, a limited element of three precursors for CPC synthesis, supports the enhanced CPC production in undefined media. Abundance of xylose ensures a maintained NADPH concentration required for sulfate reduction and synthesis of amino sulfide such as cysteine. Cystathionine‐γ‐lyase activity profiling indicated more efficient biosynthesis in undefined media than in other cultures use glycerol and glucose, and the biosynthesis pathway of CPC production by the cephalosporin gene cluster (i.e. pcbC and cefG genes) was investigated. The process using undefined xylose media was designed, and process simulation program confirmed our results.

Reduction of Volatile Organic Compounds (VOCs) Emissions from Laundry Dry-Cleaning by an Integrated Treatment Process of Condensation and Adsorption

Volatile organic compounds (VOCs) are intermittently emitted at high concentrations (tens of thousands of ppmv) from small-scale laundry shops in urban areas, affecting the urban atmospheric environment. In this study, we suggested integrating VOC treatment processes incorporating condensation and adsorption in series to remove VOCs released from small-scale laundry dryers (laundry weighing less than 30 kg). We designed two different processes depending on regeneration modes for adsorber beds; an open-circuit flow process and a closed-loop flow process in regeneration mode. Our VOC treatment processes enable sustainable operation via the regeneration of adsorbers on a regular basis. Before applying the VOC treatment processes, average concentration of total volatile organic compounds (TVOCs) was 4099 ppmv (12,000 ppmv of the peak concentration) during the drying operation. After applying our closed-loop flow process, TVOC concentration decreased to 58 ppmv, leading to 98.5% removal efficiency. We also verified the robustness of our process performance in a continuous operation (30 cycles) by using a process simulation program. Lastly, we observed that our integrated treatment process can contribute to reductions in ozone and secondary organic aerosol generation by 90.4% and 95.9%, respectively. We concluded that our integrated VOC treatment processes are applicable to small-scale laundry shops releasing high-concentration VOCs intermittently, and are beneficial to the atmospheric environment.

A Framework for Economically Optimal Operation of Explosive Waste Incineration Process to Reduce NOx Emission Concentration

Explosives, especially those used for military weapons, have a short lifespan and their performance noticeably deteriorates over time. These old explosives need to be disposed of safely. Fluidized bed incinerators (FBIs) are safe for disposal of explosive waste (such as TNT) and produce fewer gas emissions compared to conventional methods, such as the rotary kiln. However, previous studies on this FBI process have only focused on minimizing the amount of NOx emissions without considering the operating and unitality costs (i.e., total cost) associated with the process. It is important to note that, in general, a number of different operating conditions are available to achieve a target NOx emission concentration and, thus, it requires a significant computational requirement to compare the total costs among those candidate operating conditions using a computational fluid dynamics simulation. To this end, a novel framework is proposed to quickly determine the most economically viable FBI process operating condition for a target NOx concentration. First, a surrogate model was developed to replace the high-fidelity model of an FBI process, and utilized to determine a set of possible operating conditions that may lead to a target NOx emission concentration. Second, the candidate operating conditions were fed to the Aspen Plus™ process simulation program to determine the most economically competitive option with respect to its total cost. The developed framework can provide operational guidelines for a clean and economical incineration process of explosive waste.

Transient Process at Atmospheric Discharge into the Landline and the Appearance of an Electric Arc in the Switch

This document proposes a model of the process of atmospheric discharge of overhead lines followed by an electric arc. The intensity of atmospheric discharges, followed by electric arc and destruction, is determined by the difference in potential and current. Such a structure and form of discharge make it difficult to analyze the transient process and obtain adequate solutions. That is why the model of the transient process in the electric arc of the switch under the conditions of interruption of the AC circuit is specially analyzed. Simple equivalent schemes for the analysis of phenomena with given values of linear parameters are presented, which are very simple to apply. All influential parameters by which the overvoltage values in the model can be estimated were also taken into account. The evaluation of the proposed model was performed using the adapted MATLAB program psbsurlightcuurent for atmospheric electrical discharge, which contains a high frequency current source. The verified simulation method was used to verify the results as part of a method derived from artificial intelligence algorithms. The process simulation program, the obtained voltage and current diagrams confirm the application of the simulation algorithm model.

Performance evaluation of a pressurized oxy-combustion power plant according to wet and dry flue gas recirculation

In a pressurized oxy-combustion (POXY) power plant, it is essential to control the furnace temperature using flue gas recirculation (FGR) as an oxy-combustion environment produces an extremely high temperature in the furnace. However, FGR decreases the plant efficiency as it causes exergy loss in the furnace and increases the power consumption of the FGR booster fan. Therefore, to analyze a POXY plant, the effect of FGR on plant efficiency and performance should be evaluated. In this paper, an advanced supercritical pressure (A-USC) POXY power plant with a distributed pressurized oxy-combustion (DPOC) furnace is simulated and its performance for wet/dry FGR is analyzed. The furnace was modeled using an in-house code, and the whole power plant was simulated using commercial process simulation program. Plant efficiency with the wet FGR is 3.5% higher than that of the dry FGR system owing to the higher latent heat recovery of the FGC and reduction in the exergy loss. In addition, we demonstrated that variation of the plant efficiency for various flowrates of the recirculated gas was not significant in case of the wet FGR system, while considerable decrease in plant efficiency was observed for higher recirculation in the dry FGR cases. Accordingly, we presented an optimal A-USC POXY power plant system with a wet FGR system; the plant net efficiency improved by approximately 10% compared with that of a first-generation oxy-combustion power plant at atmospheric pressure.

Improving the Energy Efficiency for Propane Recovery from Natural Gas using Pinch Technology: A Case Study

Process integration (PI) techniques is an efficient approach to increase the profitability due to reduction in energy, water and raw materials consumption, reduction in greenhouse gas (GHG) emissions, and in waste generation. The PI method, pinch technology is certainly the most widely used in industrial processes. When planning a new plant or revamping an existing plant it is very important to understand and select the right process to minimize capital and operating costs. This research was directed to investigate the reduction of energy consumption in propane recovery units that process natural gas produced from wells existing in the Egyptian western desert fields. The first step was process simulation of the existing gas processing plant using AspenHysys8.3 steady state process simulation program. Next, pinch technology has been adopted in order to achieve minimum hot and cold utilities and save capital cost of the process. Target utilities were calculated using pinch analysis in the Aspen energy analyzer program. Modifications in heat exchanger network could result in savings of 8.3% in hot utility, 6.5% in cold utility of the existing plant and of 46.7% in capital cost for a grass root plant.

Understanding Catalysis—A Simplified Simulation of Catalytic Reactors for CO2 Reduction

The realistic numerical simulation of chemical processes, such as those occurring in catalytic reactors, is a complex undertaking, requiring knowledge of chemical thermodynamics, multi-component activated rate equations, coupled flows of material and heat, etc. A standard approach is to make use of a process simulation program package. However for a basic understanding, it may be advantageous to sacrifice some realism and to independently reproduce, in essence, the package computations. Here, we set up and numerically solve the basic equations governing the functioning of plug-flow reactors (PFR) and continuously stirred tank reactors (CSTR), and we demonstrate the procedure with simplified cases of the catalytic hydrogenation of carbon dioxide to form the synthetic fuels methanol and methane, each of which involves five chemical species undergoing three coupled chemical reactions. We show how to predict final product concentrations as a function of the catalyst system, reactor parameters, initial reactant concentrations, temperature, and pressure. Further, we use the numerical solutions to verify the “thermodynamic limit” of a PFR and a CSTR, and, for a PFR, to demonstrate the enhanced efficiency obtainable by “looping” and “sorption-enhancement”.

Process Simulation of the BOG Re-Liquefaction system for a Floating LNG Power Plant using Commercial Process Simulation Program

Process Simulation of the BOG Re-Liquefaction system for a Floating LNG Power Plant using Commercial Process Simulation Program

Renewable methanol synthesis from renewable H2 and captured CO2: How can power-to-liquid technology be economically feasible?

With the growing concern about environmental issues including high CO2 emission, which is the main contributor to global warming resulting in climate change, CO2 utilization technologies have received much attention. Among diverse technologies, renewable methanol synthesis using H2 generated from the water electrolysis and the CO2 captured from various industrial processes as well as the atmosphere has received significant attention. In this context, the technical and economic feasibility analysis of renewable methanol synthesis was conducted in this study. Using a commercial process simulation program, Aspen HYSYS®, parametric studies were conducted to investigate the effects of diverse operating parameters, such as the reaction pressure, temperature, and H2/CO2 ratio, on the technical performance of this process. Under the optimum conditions of 100 bar and 493 K derived from thermodynamic studies, an economic analysis was performed to estimate the unit methanol production costs at different methanol production capacities using itemized cost estimation, sensitivity analysis, and predictive cost analysis. Predictive cost analysis was conducted to determine how the unit methanol production cost could be rendered reasonable compared to the existing one, which indicated that decreasing the renewable H2 production cost as well as increasing in the CO2 tax credit for a methanol production capacity of 100 ton per day would make the renewable methanol synthesis an economically feasible process.

Comparison and validation of three process simulation programs during warm start-up procedure of a combined cycle power plant

The energy market is one of the largest and most important markets around the world. Where flexibility and efficient operation in the start-up of combined cycle power plants (CCPPs) play an essential role in the competitiveness of CCPPs in the energy market. Moreover, to study the CCPPs, the Dynamic simulation is suitable tool for predicting the behavior of power plant with high accuracy. In this paper, we study the details of warm start-up procedure of CCPP, with subcritical, natural circulation and three-pressure stages heat recovery steam generator. Examining the capability of Power Plant Simulator & Designer (PPSD) by validating the numerical results of PPSD with operational data of real power plant. In addition to compare numerical data of PPSD by another numerical data acquired using another two dynamic simulation tools APROS and ASPEN Plus Dynamics to ensure the capability of PPSD to perform such simulations. The model built based on a real power plant design data with all geometry including heat exchangers, turbines, pipes valves, pumps, and control circuits as well. PPSD shows accurate results with high quality in both qualitatively and quantitatively, compared to the measured data and other simulations well. Moreover, it shows that it is capable to perform a dynamic simulation of CCPP with relatively shorter computation time and user-friendly tools.

Error Investigation for Free Form Surfaces in Bezier Techniques

Surface modeling utilizing Bezier technique is one of the more important tool in computer aided geometric design (CAD). The aim of this work is to design and implement multi-patches Bezier free-form surface. The technique has an effective contribution in technology domains and in ships, aircrafts, and cars industry, moreover for its wide utilization in making the molds. This work is includes the synthesis of these patches in a method that is allow the participation of these control point for the merge of the patches, and the confluence of patches at similar degree sides due to degree variation per patch. The model has been implemented to represent the surface. The interior data of the desired surfaces designed by MATLAB software have been transformed to UG-NX8 software to get the machining process simulation and G-code programs for the model, as well as a virtual machining process has been simulated to show the machining pitfalls, using CIMCO edit software. The sample has been machined using 3-axis vertical CNC machine. Finally, the sample has been measured using (CMM inspection) and it’s found that the average of error (0.144 mm).

Assessment of the Importance of Energy Facilities Reconstruction Factors

In modern conditions, ehe necessity to integrate the complex of managerial, technological and climatic factors in choosing solutions at all stages of the planning and management of construction production requires a re-evaluation of the existing approaches to reconstruction process. In this article the author considered the question of estimating the importance of factors influence on the total duration of the reconstruction of energy facilities. The purpose and objectives of the study were formed, based on the analysis of codes and standards in the construction sphere, as well as data about the objects of reconstruction. The studies of national and foreign scientists and specialists of the construction sphere, process simulation program and programs of federal and regional energy development were used for the methodological basis of the research. The study provides a multifactor analysis of the impact of labor efficiency depending on the work type on the duration of the reconstruction of objects. The quality of the model was checked with three formal criteria. The conclusions and results of the study allow us to conclude about the importance of certain factors in the total model and build the most qualitative model.

Development of SWRO-PRO hybrid process simulation and cost estimation program

The main objective of this paper is to develop computer simulation program for performance evaluation and cost estimation of a reverse osmosis (RO) and pressure-retarded osmosis (PRO) hybrid process to propose guidelines for its economic competitiveness use in the field. A solution-diffusion model modified with film theory and a simple cost model was applied to the simulation program. Using the simulation program, the effects of various factors, including the Operating conditions, membrane properties, and cost parameters on the RO and RO-PRO hybrid process performance and cost were examined. The simulation results showed that the RO-PRO hybrid process can be economically competitive with the RO process when electricity cost is more than 0.2 $/kWh, the PRO membrane cost is same as RO membrane cost, the power density is more than and PRO recovery is same as 1/(1-RO recovery).

A hundred years of chemical equilibrium calculations – The case of ammonia synthesis

An exercise that involves a process of great historical importance – that of synthesizing ammonia from its elements – is presented. In the exercise, the students are required to calculate the equilibrium conversion to ammonia using three mathematical models: a regression model which is based on experimental equilibrium data obtained by Haber and le Rossignol over a hundred years ago; a model based on the Gibbs energy and ideal gas conditions; and the Gibbs energy model with gas phase non-ideality included. The use of state-of-the-art problem-solving tools, including mathematical software packages and process simulation programs, combined with reliable physical property databases for the equilibrium computations, is emphasized. On one hand, the exercise gives students an opportunity to become familiar with and to appreciate the precision of the experimental work and the manual calculations that were carried out more than a hundred years ago, and on the other hand, it gives them an opportunity to practice the use of the modern numerical problem-solving tools. It also helps them master the complex issues involved in phase and chemical equilibrium in reacting systems.

Development and validation of a dynamic simulation model for a large coal-fired power plant

The rapid expansion of renewables due massive use of subsidies in the last years changes the operation of fossil fired power plants in Germany dramatically. Since the large-scale storage of electricity is still difficult and forecasts for wind and solar energy have unavoidable uncertainties, the conventional power plants have to compensate the demand in the grid. Several new measures are introduced by power plants operators in order to respond to these new market conditions like the reduction of the low load operation of the nominal load and the continuous operation at an off-design operation point. In this work, a full-scale dynamic model of large scale coal-fired power plant has been developed to investigate the operation flexibility. The dynamic model, developed in the process simulation program APROS, includes all power plant components and its associated control schemas. The only boundary conditions are the coal composition, the ambient temperature and the temperature and amount of cooling water in condensers. The developed model is validated against operational data from the real power plant during part load transients, showing a very good agreement. The validated model is of high relevance for further investigations regarding flexibility increase in conventional large coal-fired power plants.

Development of a Gas Dynamic and Thermodynamic Simulation Model of the Lontra Blade Compressor™

The Lontra Blade Compressor™ is a patented double acting, internally compressing, positive displacement rotary compressor of innovative design. The Blade Compressor is in production for waste-water treatment, and will soon be launched for a range of applications at higher pressure ratios.In order to aid the design and development process, a thermodynamic and gas dynamic simulation program has been written in house. The software has been successfully used to optimise geometries and running conditions of current designs, and is also being used to evaluate future designs for different applications and markets.The simulation code has three main elements. A positive displacement chamber model, a leakage model and a gas dynamic model to simulate gas flow through ports and to track pressure waves in the inlet and outlet pipes. All three of these models are interlinked in order to track mass and energy flows within the system.A correlation study has been carried out to verify the software. The main correlation markers used were mass flow, chamber pressure, pressure wave tracking in the outlet pipe, and volumetric efficiency. It will be shown that excellent correlation has been achieved between measured and simulated data. Mass flow predictions were to within 2% of measured data, and the timings and magnitudes of all major gas dynamic effects were well replicated.The simulation will be further developed in the near future to help with the optimisation of exhaust and inlet silencers.

Adsorption processes for CO2capture from flue gas using polyaniline solid sorbent

In this simulation study, the temperature swing adsorption (TSA) process and the pressure swing adsorption (PSA) process were utilized to separate flue gas (15.03% CO2 and 84.97% N2) from a power plant with a solid polyaniline sorbent. CO2 can be recovered and sequestrated to reduce greenhouse-gas effects. The method of lines is utilized, combined with upwind differences, cubic spline approximation and LSODE of ODEPACK software to solve the problem. The concentration, temperature, and adsorption quantity in the bed are integrated with respect to time by LSODE of ODEPACK software. The simulation is stopped when the system reaches a cyclic steady state. In this study, experimental data was first regressed to obtain the parameters of the isotherm curves; then the breakthrough curve of the solid polyaniline sorbent was simulated. The feasibility of the adsorption process simulation program became obvious through a comparison of the experimental and simulation results. Four different processes were used in this study: the single-bed five-step TSA process, the single-bed two-step PSA process, the single-bed three-step PSA process and the dual-bed six-step PSA process. The optimal operating conditions were obtained by varying the operating variables, such as adsorption temperature, desorption temperature, feed pressure, bed length, step time, etc. After the variables discussion, the best process is found to be the single-bed three-step PSA process and the best operating conditions are a feed pressure of 6.0 atm, a co-current depressurization pressure of 1.0 atm, a vacuum pressure of 0.1 atm, a bed length of 98.3 cm and step times of 1200, 10 and 500 s. The results of the aforementioned operating conditions are 97.13% purity and 87.26% recovery of CO2.

Density Marching Method for Calculating Phase Envelopes. 2. Three-Phase Envelopes

There are very few automatic procedures in the literature to calculate three-phase envelopes (VLLE boundaries). The best existing procedures require selecting each step manually to complete the three-phase envelope. In this article, a density marching procedure and a saturation point calculation at specified density of one of the incipient phases developed recently for drawing two-phase envelopes is extended to three-phase envelopes. Procedures have been presented to determine three-phase bubble and dew points reliably. Two examples are presented to demonstrate the method. The method has direct application in process simulation and thermodynamic property programs.

Vapor–Liquid Equilibrium of Hydrogen, Vacuum Gas Oil, and Middle Distillate Fractions

Vapor–liquid equilibrium (VLE) data for hydrogen/hydrocarbon mixtures based on real feedstocks at high temperature and pressure is scarce and is needed to model hydrocracking systems accurately. Experiments with a vacuum gas oil have been used to generate VLE data for real hydrogen/hydrocarbon mixtures under hydrocracking conditions in a semibatch reactor with a range of compositions. Flash calculations were performed using a process simulation program and compared to the experimental results. The data was used to verify the existence of equilibrium conditions in the reactor and to show that the Grayson Streed activity coefficient model, combined with Peng–Robinson equation of state, provides a good estimate of liquid phase and vapor phase compositions and individual component volatility.