Search

Polymeric blend mixed matrix membranes (PB3Ms) are synthesized with different blend compositions at a fixed content of carbon molecular sieve (CMS) inorganic filler. The resulting membranes are characterized by FESEM, TGA, DSC and FTIR analyses. Polyethersulfone (PES)/polyvinyl acetate (PVAc)/CMS polymeric blend mixed matrix membranes are prepared by solution casting method. A homogenous mixture of all these components is formed and cast on a clean glass plate. The produced PB3Ms show drastic enhancement in CO2 permeance and CO2/CH4 selectivity in both single and mixed gas permeation tests in comparison with pure PES membrane. Significant CO2 permeance of 132.47 GPU with CO2/CH4 selectivity of 75.27 at 6 bar is obtained for the PB3M having 80 wt%/20 wt% blend ratio of PES/PVAc and 20 wt% CMS loading. The synthesized polymeric blend mixed matrix membranes in this research study demonstrate competitive CO2/CH4 separation performance in comparison with the reported literature on PB3Ms for gas separation.

Cryogenic carbon dioxide (CO2) capture technologies showed promising results for the purification of highly sour natural gas reserves. However, quantitative experimental data for solid and liquid CO2 formation during cryogenic separation is not adequately examined in the previous studies. Moreover, an economical and efficient cryogenic CO2 capture technology with reduced energy and hydrocarbon losses is necessary to make it attractive for commercial use. A high-pressure cryogenic hybrid network comprised of the packed bed and the cryogenic separator was developed for the cryogenic experimental study on CO2 capture from binary CO2-CH4 mixture to focus these areas. Feed containing 30, 50 and 70 % CO2 content were used and the separation study was conducted in vapor-solid (V-S), vapor-liquid (V-L), and vapor-liquid-solid (V-L-S) regions of phase equilibria. The packed bed was used in the V-S operational domain to quantify CO2 solid up to 20 bar because of the operational limitations. Separation characteristics and V-L isothermal flash measurements at 20, 30, and 40 bar pressure and temperature ranges from -20 to −60 °C were carried out in the cryogenic separator. The operation in the setups was carried out at different compositions of the CH4-CO2 binary mixture to define the boundaries of the hybrid cryogenic network. Liquid formation at 40 bar for 70% CO2 feed was 0.15 kg at -55 °C as compared to 0.03 kg for 30 % CO2 feed. The simulation study was carried out using Aspen Plus along with the Peng Robinson Equation of State (EoS), and the results were compared with the experimental data, which showed good agreement. The hybrid cryogenic network showed an energy reduction of 37 % compared to the conventional cryogenic distillation network with 90.6 to 97.3 % CH4 purity and 2.65 to 12.39 % methane losses with different arrangements of the hybrid cryogenic network.

The inherent safety level (ISL) assessment of a heat exchanger network plays a vital role in developing its inherently safer design. New essential safety indices, i.e., inherent safety index for shell and tube heat exchanger (ISISTHE) and overall safety index for heat exchanger network (OSIHEN), are introduced to overcome this potential gap. A prototype tool is proposed by integrating these indices to a process design simulator via object linking and embedded automation. The heat exchanger network of an ammonia synthesis process and a steam reforming unit are presented as a case study. In conclusion, this prototype tool was found to have the potential to figure out a dangerous heat exchanger in a network. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

The objective of this study is to measure the physicochemical properties of 2-aminoethanoic acid (glycine, GLY) and N,N-dimethyl-1,3-diaminopropane (DMAPA) solution, which are important parameters ...

In process industry, failure or rupture of pressurized vessel is very dangerous especially when there is an escape of flammable gaseous mixture that can cause potential fire or explosion. One of the scenarios that causes such accidents is the blowdown process. Therefore, it becomes crucial to control blowdown process to prevent such accidents. It is important to design optimally to make sure that blowdown valve is according to the requirements. For the safe use of a pressure relief system, some of the parameters are critical, for example, selection of construction material, sizing of relief valves, temperature, and pressure, etc. There is no literature currently available that discusses all the mathematical models or simulation tools for optimum design of the blowdown process. This subject matters because the available models or tools cover different aspects of blowdown process. A meticulous review is required to present the applications of these models and tools based on the accidental scenarios. Therefore, this paper critically reviews the models and tools that are developed purposely to calculate optimum blowdown parameters based on fluid and vessel conditions. Recommendations are given for the development of new simulation tool to simulate phase change conditions especially when solid formation is involved.

High frequency ultrasonic-assisted absorption in a batch system has shown significant enhancement for CO2 removal. Nevertheless, its performance in continuous mode has yet to be studied. A novel continuous high frequency ultrasonic contactor system for CO2 capture has been developed to study the effect of gas flow rate (15–25 SLPM), liquid flow rate (0.1–0.5 SLPM), pressure (10–50 bar) and voltage (0–30 V) on the absorption performance. A validated quadratic model was developed, and the optimum condition was identified using central composite design coupled with response surface methodology. Based on the results, current system demonstrated better absorption performance as compared to other contactors.

One of the challenges for production of natural gas from very sour gas reservoirs with CO2 content up to 80 is the high cost of purification process. The hydrate-based gas separation (HBGS) process is gaining interest globally as a greener solution for separation of CO2 from gaseous streams including sour hydrocarbon mixtures. However, separation of large amounts of CO2 through gas hydrate formation typically leads to considerable loss of hydrocarbons. In this work, selective capturing of CH4 from high CO2 gas mixtures is investigated. Two water-soluble thermodynamic promoters, tetrahydrofuran (THF) and acetone, are used for this purpose. The results indicate that inclusion of these promoters dramatically increased CH4 uptake by sII hydrate formation. However, only THF exhibited a favorable selectivity of CH4. Moreover, this effect is pressure dependent, and the optimum pressure is around 4.5 MPa. Copyright © 2019 American Chemical Society.

The surface tension study is very crucial for the design of CO2 gas absorption contacting equipment. The significance of the surface tension has been increasing due to its consideration in various technological fields. This property influences the mass transfer and hydrodynamics of gas absorption systems, mainly multiphase systems, in which the interface between gas and liquid exists. Therefore, in this study, surface tension of aqueous solutions of sodium l -prolinate (SP) and piperazine (PZ) blends were measured at ten different temperatures from (298.15 to 343.15) K. The SP mass fractions were 0.10, 0.20, and 0.30; while the mass fractions of PZ were 0.02 and 0.05. The experimental results showed that the surface tension increase with increasing the mass fractions of SP and PZ in aqueous blends, and decrease linearly with rising temperature. The experimental data of surface tension were correlated by two empirical correlations as a function of temperature and mass fractions for estimating the predicted data using the optimized correlation coefficients. Moreover, the modeling of surface tension data was carried out using Artificial Neural Network (ANN) approach. The results obtianed from ANN modeling were compared with applied empirical correlation. It was found that the ANN approach outperformed the empirical correlation used in this study. Besides, a quantitative analysis of variation (ANOVA) was performed in order to determine the significance of data. The surface tension of aqueous SP and SP + PZ was also compared with various conventional solvents.

CO2 removal via absorption/stripping system using chemical solvents is a widely acknowledged technology for CO2 capture, either from natural gas or post-combustion processes. It offers higher capture efficiency. However, one of its main drawbacks is the high energy consumption in the regeneration step. Besides, for solvent-based absorption/stripping plant, the units feature nonlinearities as well as high process interactions. Hence, control strategies are crucial in the operational optimization of process set-point changes and disturbance rejections as well as reduction in the operational costs of such systems. Process control systems are key in processing plants as they direct production processes, minimise variations and regulate product consistency. In this paper, an overview on the related efforts that have been carried out in terms of basic and advanced process control strategies are reviewed to provide further understanding on the key features that are required to optimize the operation of the absorption/stripping system.

Risk assessment is the tool for maintaining perfect safety management systems and aiding sustainable process design, with hazard identification as the critical step. This step can be executed by past accidents analysis (PAA) to achieve the mentioned objectives. Despite of available analyses, the recurring of accidents identifies the shortcomings in PAA and requires a detailed examination as reported in this review. The intensified exploration of accident information will strengthen both the safety management system at existing facilities and process designing in terms of sustainability. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

In this work, the performance of potassium glycinate (PG) and virgin coconut oil (VCO) mixture as potential green solvent for carbon dioxide (CO2) capture was investigated. The mixture was prepared by mixing PG with 50 weight percent (w/w%) VCO and characterised using density meter, tensiometer and Fourier Transform Infrared (FT-IR) spectrometer. The densities of PG, VCO and PG-VCO mixtures measured from 303.15 to 333.15 K were fitted against an empirical correlation. Viscosities of pure VCO and PG-VCO mixtures were measured at 308.15 K. The solubility of absorbents were studied by bubbling CO2 directly into the solution and measuring mass increase of the solution. Experimental results showed that the density of PG, VCO, and PG-VCO mixtures decreased with increase in temperature and increased with increase in PG concentration. On the other hand, the viscosity of PG-VCO mixtures were reduced by approximately half compared to pure VCO. Moreover, the addition of VCO into the PG solution enhanced the solubility of CO2 in the mixture due to the additional physical interaction between VCO and CO2 molecules. Maximum CO2 absorption of 3.942 mol CO2/mol of PG was observed for 0.1 M PG-VCO mixture. A mechanism study also revealed that the presence of VCO contributed to the formation of bicarbonate ion and protonated potassium glycinate after the CO2 absorption.

Hazards associated with chemical processes can lead to accidents, which can be managed through process safety strategies. Inherent safety is a proactive tactic, capable of both identifying and minimizing the hazard. Available inherent safety assessment (ISA) methods focus on route selection only. Individual process equipment characteristics, especially the mechanical aspects are not reported for ISA. Subsequently, this paper presents a new technique for suitable material selection of process equipment at initial design stages. In inherently safer mechanical material (ISMM), process characteristics are coupled with the mechanical attributes for mechanical material selection of process equipment. The relative ranking of process equipment is used to highlight the critical process equipment that is more prone to leak. This risky process unit is further studied to select the suitable mechanical material. Two-fold mechanical compatibility criteria are established, which needs to be satisfied for material selection. If the proposed material is found unsuitable, inherent safety theme is used to propose the suitable material. The ISMM technique is verified by a case study of MMA-TBA process plant Hysys simulation. The technique is simple and identifies the crucial equipment in early design stages, which can help the design engineers to implement inherent safety at the basic design stage.

In this work GERG2008 EoS was incorporated in a volumetric-gravimetric-chromatographic technique. The system utilized to measure in-mixtures components experimental selective isotherms individually, with the ability to analyze water vapor–gas components in the same mixture. 5A zeolite was used as a solid adsorbent for binary and ternary CO2/CH4/H2O mixtures adsorption at 50 °C and 70 °C temperature up to 10 bar pressure. Artificial neural network (ANN) modeling was applied to predict ternary and binary gaseous with the presence of water mixtures. This study delivered better clarification in the field of selectivity and reliability in the term of multicomponent and dual phase mixtures analysis.

Over the years notable accidents have occurred in the chemical process industry thus creating a major concern for the safeness of its operation. The disasters led to the dire consequences that claimed human life and health as well as monetary losses. Inherently safer design is an effective solution to prevent accidents because it postulates that the best way to reduce risk is to avoid the hazard rather than control the hazard. Although the implementation of inherently safer design can give great advantages and cost optimal operation throughout process’s life cycle, slow adoption of this principle into real design practice can be observed. This is partly because the inability to realise the benefits of inherent safety implementation among industrial practitioner. This paper presents a methodology for evaluating inherently safer design alternatives and identifying the benefits using an index-based approach at preliminary design stage. The proposed methodology is applied to ammonia storage with the objective of preventing and minimising toxic release. The results have shown that the new methodology can identify the best inherently safer design and the benefits where it is capable to reduce the severity of accident and the requirement to manage hazardous process.

In this work, the equilibrium solubility of CO2 in aqueous solution of 10, 20, and 30 wt% sodium β-alaninate (Na-βala) was investigated using high pressure solubility cell. The solubility experiments were carried out at temperatures 303.15, 313.15, and 333.15 K and over CO2 partial pressure ranging from 2 to 25 bar. Experimental results showed that with the increase in Na-βala concentration and temperature of the system, CO2 loading decreases. Whereas, the CO2 loading increases by increasing the partial pressure of CO2. Furthermore, a modified Kent–Eisenberg model was used to correlate CO2 solubility data as a function of temperature, concentration and CO2 partial pressure. An average absolute deviation of 12.8% was obtained between the experimental and model correlated data, which indicated the good correlation capability of the applied model.

An intumescent coating is an insulating system designed to decrease the heat transfer a substrate structure. The intumescent fire retardant (IFR) coating presented here is based on expandable graphite (EG), ammonium polyphosphate (APP), melamine, and boric acid. Bisphenol epoxy resin BE-188 (BPA) was used as a binder with ACR Hardener H-2310 polyamide amine. Different formulations were developed to study the effects of APP and boric acid on char expansion, heat shielding, char morphology and char composition after a fire test. The coating was tested at 950°C for one hour. Char expansion was examined by furnace using a fire test. The results show that the coating is stable on the substrate. The morphology of the char was studied using Field Emission Scanning Electron Microscope (FESEM) of the coating after a fire test. X-ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed the presence of carbon, borophosphate; boron oxide and sassolite in the residual char. Thermogravimetric analysis (TGA) including derivative plots showed that boric acid and APP enhance the residual weight of intumescent fire retardant coating. X-ray photoelectron spectroscopy (XPS) confirmed that IF5 recorded better carbon content up to 47.45 wt%, in the residual char that enhanced the fire resistance performance of the coating. An accelerated weathering test according to ASTM D 6695-03 showed that the IF5 coating continued its reliability up to 90 days in the hastened weathering chamber.

The failure of shell and tube heat exchangers is a chronic problem in the chemical process industries. Meager safety analysis and lack of inherently safer design considerations are noticeable issues resulting in the failure of these heat exchangers. Existing inherent safety level quantification methods mostly focus on the process route selection in the preliminary design stage. Nevertheless, existing methods have never been applied to quantify the inherent safety level in a heat exchanger network. Therefore, this paper presents a coherent framework to outline an inherently safer heat exchanger network in the preliminary design stage. In this framework, newly developed safety indices are introduced to estimate the inherent safety level of a single heat exchanger and the heat exchanger network. The worst heat exchanger is identified based on the lowest inherent safety level. An inherent risk assessment (IRA) of the worst heat exchanger is carried out to analyze the inherent risk of potential explosion event. Moreover, normal distribution of the safety index values is analyzed through the normality test. Inherent risk assessment and the normal distribution of index values are configured as a decision-making steps for implementing the inherently safer design strategies. This framework is integrated with a process design simulator (Aspen HYSYS) for seamless transfer of the process information. A heat exchanger network of a typical ammonia synthesis loop was considered as a case study. Inherently safer designs for this heat exchanger network are presented by using moderation and simplification methods. The inherent safety level of the heat exchanger network can be improved by applying inherently safer design strategies.

In this research work, thermophysical properties such as density, refractive index, surface tension, and viscosity of aqueous N-methyldiethanolamine (MDEA) and 1-butyl-3-methylimmidazolium trifluoromethanesulfonate [bmim][OTf], 1-butyl-3-methylimmidazolium acetate [bmim][Ac] hybrid solvents were investigated. All thermophysical properties were investigated at an atmospheric pressure, between the temperature ranges of 298.15 to 343.15 K with an interval of 5 K. In all samples, the concentration of MDEA was kept constant at 30 wt%, while the concentration of the ionic liquids was varied between 5–20 wt%. Experimental investigation demonstrated that the thermophysical properties were mainly dependent on the temperature and the concentration of the ionic liquids. All thermophysical properties were decreased with increase in temperature of the system. An increasing trend was observed in density, refractive index, and viscosity data with the increase in the concentration of the ionic liquids. The surface tension data for all samples under investigated was found to be in decreasing order with the increase in the concentration of the ionic liquids. It was also noticed that the use of two different ionic liquids has a different impact on the thermophysical properties of the hybrid solvents. Empirical correlations were used to correlate the experimental data of all the properties as a function of temperature and concentration of both the components (IL and amine). The correlated data were found to be in good agreement with the experimental data at all concentrations.

The performance of a zeolitic imidazolate framework-8 (ZIF-8) membrane in single and binary CO2/CH4 gas separation was investigated by means of a gas transport model that included generalized Maxwell-Stefan and binary friction models. The model concerns gas diffusion through the membrane layer, gas flow through membrane intercrystalline pores, and resistance of the support layer. The effective membrane area considering the actual area for the gas permeated through the membrane was also introduced in this model. The selective ZIF-8 membrane was successfully synthesized using a microwave-assisted solvothermal method on an α-alumina support pre-attached with ZIF-8 seeds by solvent evaporation. The simulated data agreed well with the experimental data. The model revealed that the membrane intercrystalline pores and its effective area significantly affected the CO2/CH4 gas permeation and separation performance.

This paper reports the use of piperazine promoted 2-amino-2-methyl-1-propanol (PZ + AMP) blended solution for the removal of high concentration CO 2 in natural gas (NG). The process behaviour was investigated by conducting the experiments in a bench-scale packed absorption column at high pressure conditions. The CO 2 concentration and temperature profiles along the column were presented in order to study the process behaviour in the column at various operating pressures, CO 2 concentration in NG, total gas flow rates, liquid flow rates, amine concentration and inlet liquid temperature. The temperature bulge was observed in the column and further discussed in this paper.

The large footprint of liquid physical solvent regeneration unit has reduced its feasibility to be employed at offshore condition. The main aim of current work is to design a compact physical desorption unit via computational modelling approach. Two main outcomes obtained from current work include modelling of non-equilibrium desorption phenomenon and introduction of conceptual design for in-line physical desorption unit. The desorption phenomenon was modelled using Computational Fluid Dynamics – Population Balance Model (CFD – PBM) model with integration of bubble nucleation and growth models. The in-line physical desorption unit has been designed based on three design considerations; pressure maintenance in pipeline without using pump, solvent flow rate optimisation, and desorption rate enhancement. The desorption phenomenon in conventional nozzle and initial conceptual design of in-line physical desorption unit were modelled. The CFD modelling approach has been experimentally validated. CFD results were used to analyse the desorption phenomenon in the domain. The pressure drop in the pipeline (inlet) of initial conceptual design was found to be insignificant. The mole fraction of CO 2 in water at the outlet was found to experience higher reduction (better desorption) for initial conceptual design (0.0035) as compared to conventional nozzle (0.0053) from inlet mole fraction of CO 2 at 0.0064 for both cases. The velocity of gas–liquid has been increased from 5.5 m/s (inlet) to 18.5 m/s (outlet) in the initial conceptual design. The optimisation of the initial conceptual design of in-line physical desorption unit would be presented in Part 2 of the study.

A framework for mixed sequential and integrated hybridization (MSIH) based intensification is proposed for cryogenic CO 2 capture from natural gas. Formulation and evaluation of the intensified cryogenic distillation network is also investigated. The present work attempts to experimentally quantify the liquid and solid formation during cryogenic CO 2 capture and the separation efficiencies obtainable in real life under cryogenic temperature and high pressures in presence of their complex dynamics and interactions. Synthesis, sensitivity analysis and evaluation were performed for side mounted switched cryogenic desublimation beds integrated with the distillation column in the cryogenic network. The advantages of mixed integrated hybrid cryogenic distillation network over base case and sequential multibed hybrid networks are highlighted and presented. Optimization of each network has been carried out using the real life efficiencies and experimental solid and liquid formation data. Optimization of mixed sequential and integrated cryogenic network showed promising potential through reduction in energy consumption, hydrocarbon losses and footprints.

This paper is the second part of our study on a novel in-line physical desorption unit. In the first part, the conceptual design and desorption modelling were discussed. In this paper, the work was extended to the optimisation and numerical analysis on the optimised desorption unit design. Similar to first part of our study, the desorption phenomenon was modelled via Computational Fluid Dynamics (CFD) approach. The desorption performance for seven different design parameters were studied and analysed via design of experiment (DOE) method. The objective functions were analysed and the suggested optimised design parameters were determined. Thereafter, the detailed hydrodynamics and mass transfer profile in the suggested optimised designs were simulated and studied. The performances of the optimised designs were found better than conventional nozzle. The solvent velocity at the outlet was found to be relatively high, which was ideal to be utilised together with compact gas liquid separator. The proposed in-line physical desorption unit has potential to be employed in various process conditions including remote and offshore conditions.

Although it has been reported that physical properties of polymeric membranes inherit thickness dependent characteristics, typically when they are subjected to confinement at an ultrathin dimension (

For past decades, the industry and academician realized the core of effective process safety management (PSM) is closely related to good process safety culture. Major accidents in process industry occur at low frequency but the consequences on people, environmental, and assets damage are catastrophic. Previous accidents in process industry recorded many deaths and injuries of facility personnel and public. Hence, many regulations and best practices were introduced to avoid major accidents from occurring and to mitigate the consequences. Risk based process safety (RBPS) Guideline is one of best practices to manage PSM, using risk-based approaches. When accidents happened, internal and external stakeholders are greatly impacted if it is not mitigated effectively. Thus, element stakeholder outreach which lies in Commit to Process Safety pillars are considered as important elements to protect the stakeholders and promoting good safety culture. This article presents a structured technique for stakeholder outreach using RBPS approaches and a work-aid model to ease its implementation in process industry. The technique and work-aid model are beneficial to help the organization managing stakeholders, educating the public on risk management and the importance of embracing safety culture in their life. © 2019 The Authors. Process Safety Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers.

An offshore company intends to develop a new field by installing two wellhead platforms to accommodate the well production from this field. Based on port development plans, the locations of these platforms are closed to port dumping and commercial anchorage areas. This can affect the platform's safety. Therefore, risk assessment and mitigation studies are required to forecast the impact of the new wellhead platform project. In this research, a risk analysis was conducted using a semi-quantitative risk analysis method to determine the value of total external risk that affects the safety of platforms and security of personnel. A sensitivity analysis was also conducted to identify the maximum likelihood factors that affect the risk values of platforms. The values for the new platforms were found to high-risk levels. To ensure that the risks are more tolerable, risk mitigation tasks need to be executed. Such tasks should be conducted by the company and related governmental bodies, such that the risk value, can be reduced to medium risk level. The typical risk factor developed in this research can be used by related stakeholders to determine the risk value for the impact of port development on platforms during construction and operation. © 2019 American Institute of Chemical Engineers

Process safety concept is used to deal with accident scenarios occurring as a result of loss containment. There are four tactics of process safety, and due to superior characteristics, the inherent theme is given priority at the preliminary design stage. In open literature, various methods have been proposed to identify the inherent safety level, and among these indexing methods are typically used. The reported indices have a shortcoming that these have not considered equipment characteristics for inherent safety assessment. Therefore, a new indexing method is proposed in this article to improve the quantification of inherent safety level. This index incorporates process, chemical, and equipment aspects to define the safety level of various process routes via the relative ranking. The proposed index has been tested on process routes to produce methyl methacrylate, which confirms the applicability of this index. The index would enable the practitioners to thoroughly analyze and compare the process routes to identify the inherently safer route. © 2019 American Institute of Chemical Engineers

In this paper, experimental physical properties such as density, refractive index, and viscosity of aqueous potassium l-prolinate (KPr) as a solvent for CO2 capture were investigated. Different concentrations of aqueous KPr in terms of mass fractions (0.05, 0.10, 0.20, 0.30, and 0.40) were studied over a temperature range 298.15–343.15 K. The obtained results showed that all physical properties increase with increasing the concentration of the solution (isothermally), and decrease as the solution temperature rises for any given concentration. The experimental data of density, refractive index, and viscosity were correlated using empirical correlations as a function of both, temperature and concentration. Coefficient of thermal expansion and activation energy were calculated from the experimental density and viscosity data, respectively, in the same temperature range. Thermal expansion coefficient slightly increases with increase in the temperature and concentration, while activation energy increases with the rise in concentration of amino acid salt.

Membrane separation has been used successfully in numbers of industrial applications especially in CO2 removal from CH4 because it’s involved less energy consumption and low maintenance. The aim of this research is to fabricate ZIF-8/6FDA-durene mixed matrix membranes for enhancement of CO2 capture and consequently to optimize its fabrication method. The results showed that membrane fabricated using total dispersion duration of 3 h with filler priming procedure demonstrated homogenous distribution of ZIF-8 in 6FDA-durene matrix and improved the separation performance. Therefore, the membrane is potential for the large scale production via the method optimized in this work.

Inherent safety strategy is an integral component of all engineering activities that strive towards simpler, cheaper, and safer processes. This also implies that less energy and maintenance are required and less waste and pollution are produced, which are the underlying principles of the chemical process industry. However, potential hazards that arise from inherently safer design (ISD) modification must be evaluated carefully to avoid misapplication of the inherent safer design strategy. In the previous work, the author developed a qualitative review tool, the Three-Stage ISD Matrix Tool, with the objective to help assessors understand the impact of ISD modification. In this paper, the Three-Stage ISD Matrix Tool will be combined with quantitative technique, Hazard Identification and Ranking System methodology, with the aim to quantify the impact of ISD modification. Two case studies will be presented in order to demonstrate the applicability of this approach. In the first case study, we show how this technique is capable of identifying the potential hazard that arise from a modification of Union Carbide India Limited facilities prior to the Bhopal accident. In the second case study, we show the applicability of this technique to select the safer options for ammonia storage system considering the fatalities potential and environmental impact. The results show that the combination of qualitative with quantitative technique can help assessors to effectively perceive the total impact of ISD modification.

In this study, physical properties such as density, refractive index, surface tension and viscosity of aqueous potassium salt of l -phenylalanine (K-Phe) were measured over a temperature range of 298.15⿿343.15 K for various mass fractions (0.05⿿0.25) at atmospheric pressure. The effect of temperature and concentration of aqueous amino acid salt on corresponding physical property was studied. The experimental data were correlated using applied empirical correlations as a function of temperature and concentration. Statistical analysis was performed in order to evaluate the performance of applied empirical correlations. The correlated data of physical properties were in good agreement with the experimental data. Moreover, the density data were used for the estimation of coefficient of thermal expansion, while viscosity data were used for the calculation of activation energy. Furthermore, ANOVA analysis was carried out in all the cases to determine the significant influence of temperature and concentration on physical properties.

Recently, ionic liquids (ILs) have been considered as alternative solvents to glycol in dehydration of natural gas. However, due to the unlimited structural variations and possible combinations of cations and anions of the ILs, selection of potential ILs for this separation process has been a difficult task. Activity coefficient at infinite dilution is one of the most important thermodynamic properties for preliminary selection of suitable liquid desiccants for water absorption and designing of the natural gas dehydration process. In this paper, COSMO-RS based quantitative structure–property/activity relationship (QSPR/QSAR) models were developed for prediction of activity coefficient of water at infinite dilution in ILs over various temperatures. COSMO-RS based descriptors were generated for 53 ILs (318 data points) at various temperatures. Multiple linear regressions were applied to develop the models. The accuracies of the models were verified by different statistical tests. The model provides a better understanding of the effect of the structural variations of ILs on their affinity for water.

BACKGROUND In this work, well-intergrown zeolitic imidazolate frameworks-8 (ZIF-8) membrane was synthesized through a microwave-assisted secondary solvothermal growth method. A solvent evaporation seeding method was applied prior to membrane growth. Subsequently, process optimization for the separation of CO2 from natural gas through the ZIF-8 membrane was studied using response surface methodology. The process variables studied included CO2 feed composition (36–83%), total pressure difference (100–700 kPa) and temperature (303–343 K). Three empirical models were generated using a central composite design in order to study the interaction between the process variables and the responses, including CO2 permeance, CH4 permeance and CO2/CH4 separation factor. The optimum condition was then determined for maximum CO2 permeance and CO2/CH4 separation factor and minimum CH4 permeance. RESULTS Using this method, ZIF-8 seeds of nano-size were well distributed on the support due to high nucleation rate at the supersaturation condition. The presence of heavy hydrocarbons affected CH4 permeance, attributed to the molar mass and viscosity. An optimum CO2 permeance of 2.76 × 10−8 mol m−2 s−1 Pa−1 and CO2/CH4 separation factor of 3.72 was obtained at 312 K, 100 kPa and 36% CO2 feed composition. The experimental results were in agreement with the predicted values with an average error lower than ± 7%. CONCLUSION Selective ZIF-8 membrane was successfully synthesized using a feasible and reproducible solvent evaporation seeding method. The experimental data for the optimum condition were in good agreement with the predicted data, showing the accuracy of the empirical models. © 2016 Society of Chemical Industry

Many worlds' major process industry accidents are due to BLEVE such as at Feyzin, France, 1966 and San Juan Ixhuatepec, Mexico City, 1984. One of the approaches to eliminate or minimize such accidents is by the implementation of inherently safer design concept. This concept is best implemented where the consequence of BLEVE can be evaluated at the preliminary design stage, and necessary design improvements can be done as early as possible. Thus, the accident could be avoided or minimized to as low as reasonably practicable (ALARP) without resorting to a costly protective system. However, the inherent safety concept is not easy to implement at the preliminary design stage due to lack of systematic technique for practical application. To overcome these hurdles, this paper presents a new approach to assess process plant for the potential BLEVE at the preliminary design stage and to allow modifications using inherent safety principles in order to avoid or minimize major accidents. A model known as Inherent Fire Consequence Estimation Tool (IFCET) is developed in MS Excel spreadsheet to evaluate BLEVE impacts based on overpressure, radiation heat flux and missile effects. In this study, BLEVE impacts are the criteria used as the decision-making for the acceptability of the design. IFCET is integrated with iCON process design simulator for ease of data transfer and quick assessment of potential BLEVE during the design simulation stage. A case study was conducted to assess of potential BLEVE from a propane storage vessel at the design simulation stage using this new approach. The finding shows promising results that this approach has a potential to be developed as a practical tool.

The inherent safety concept has been introduced to overcome the shortcoming of traditional hazard assessments by allowing modification to be made at any stage of life-cycle of a process plant. However, most of the proposed inherent safety modifications were suitable to prevent fire, explosion and toxic hazard but less attention on the human factor. Therefore, this paper introduces a technique to assess and improve the preventive measure relevant to human factor aspect using inherent safety concept. Analytic Hierarchy Process model integrated with fuzzy logic known as FAHP was employed to rank the identified inherently safer preventive measures. The model was applied refers to the Piper Alpha offshore disaster with the main intention is to prevent similar incident occurring in the future. The result shows the capability of the proposed methodology in selecting the best inherently safer preventive measure together with its implementation cost and maturity time without requiring lots of precise information to translate experts' opinion from human performance's point of view.

Cryogenic carbon capture from natural gas at high pressures requires accurate process synthesis and determination of process parameters due to the presence of solid–vapor and vapor–liquid–solid equilibria. At high pressures, the higher liquid formation not only causes operational problems, but also induces hydrocarbon losses in cryogenic packed beds. The present study proposes a novel multiple cryogenic desublimation based pipeline network with its sections at different cryogenic pressures and temperature profiles to enhance the separation. The experimental study explores the simultaneous separation of water and carbon dioxide from ternary feed gas mixture (CH 4 –CO 2 –H 2 O) by using multiple counter current cryogenic desublimation beds. A novel simulation strategy using multiple equilibrium temperature (MET) concept is also introduced for simulation studies. Simulation studies were subsequently conducted for both atmospheric and high cryogenic bed pressures and compared with experimental measurements. The effect of ambient humidity on dehydration was also investigated experimentally and it was observed that the humidity has significant effects on dehydration due to back diffusion. The effect of some important parameters like bed length, feed gas pressures, bed temperatures, feed flow rates and feed gas pressures for separation were investigated. Experimental investigation was also conducted to quantify liquid formation and vapor–solid equilibrium at high pressures. The experimental results of desublimation based cryogenic pipeline network showed promising potential for industrial exploitation.

The mixed-matrix membrane (MMM), a state-of-the-art polymer-inorganic hybrid, is a relatively recent addition to the membrane family which adopts the synergistic advantages of the polymer and inorganic phase. Although marked improvement has been achieved by MMMs in CO2/CH4 separation, the development of a defect-free structure to transcend the Robeson upper bound limit remains a challenge. In previous years, a number of inorganic materials with diverse nature have been studied for CO2/CH4 separation; however, layered silicates have not attracted much attention despite their superior thermal and mechanical properties. Analyses of the potential of using layered silicates as inorganic fillers in MMM fabrication for CO2/CH4 separation are reviewed. Additionally, the immediate challenges toward successful formation of layered silicate-based MMM and future prospects are addressed.

OSHA PSM standard has been established with 14 elements that define the management principles to control process hazards and protect the workplace. One of the key factors to the success of Process Safety Management (PSM) implementation is that each element comes as a component in an integrated PSM program. Although various kind of integrated safety management systems have been introduced, direct integration system between PSM elements was not extensively studied due to vague concept on interrelation between PSM elements. This also hampers efforts in designing and developing integrated system for PSM. In this study, the interrelation of critical PSM elements was analyzed based on objectives and information functional of the elements stipulated in OSHA PSM regulations. From the conducted analysis, all the critical elements are interrelated at least with other seven PSM elements. Among the elements, Process Hazard Analysis and Mechanical Integrity were identified to have the highest interrelations comprising of 12 interrelated PSM elements. The developed PSM matrix has systematically showed the interrelation of critical PSM elements that useful for the development of Integrated PSM system. © 2016 American Institute of Chemical Engineers Process Saf Prog 36: 74–80, 2017

When incidents happen and the consequences are not mitigated effectively, one of the indicated failures consists of ineffective emergency planning and response (EPR). EPR is an important aspect of the Process Safety Management (PSM) Standards, and the guidelines are stated in CFR 1910.119 (n) which explains the minimum elements of emergency response and procedures in handling emergency or small releases. Despite its implementation in 1992, CSB finds ineffective EPR system in certain accidents such as the Missouri DPS Enterprise Chlorine Gas Release accident in 2002. DPS EPR failed in planning on location of emergency equipment and accessibility. Many other accidents have occurred throughout the decade and even though organizations have their own EPR system, there are issues in meeting minimum PSM requirements. There also exists the problem of self-regulatory policies practiced by organizations, which might not meet these requirements as well. To help organizations meet these minimum requirements, the purpose of this paper is to present a structured and easy technique to plan and implement EPR as per PSM requirements. A model has been developed based on this technique, and its application has been tested as a case study in a refinery in Malaysia and discussed throughout this report. The results reflected the feasibility of this model as it helped users to track and manage documents efficiently. This technique has the potential to help users to manage EPR better and to reduce adverse impacts to people, environment and assets.

This research work was carried out to investigate the influence of blending polymer membranes on the performance of CO2/CH4 separation. This was obtained via blending glassy and rubbery polymers at different concentrations, using solution casting and a solvent evaporation method. All fabricated membranes were characterized by field emission scanning electron microscopy (FESEM), thermo gravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). The membranes were observed to have a dense structure as depicted by FESEM, low residue solvent by TGA and a miscible homogeneous blend structure by DSC. The performance of CO2/CH4 separation of the new blend membranes was compared against that of pure PES membrane at pressures varying from 2 to 10 bar. The experimental results showed that the incorporation of rubbery polymer, polyvinyl acetate (PVAc), into pure polyethersulfone (PES), which is a glassy polymer, resulted in membranes having more efficient CO2 separation. However, by increasing the pressure, the permeability dropped because of the glassy behavior of the membranes. The significant improvement of CO2/CH4 selectivity by adding PVAc in comparison to pure PES membrane indicates that the rubbery polymer (PVAc) can be used to enhance CO2 separation from CO2/CH4 mixtures.

Inherently safer and friendlier plant design offers a simpler, cheaper, safer solution that consumes less energy, requires less maintenance, and produces less waste and pollution. It is a solution that the chemical industry needs to continually adopt in the years ahead. Nevertheless, obtaining an inherently safer process/technology with respect to all potential hazards is quite unfeasible and may lead to conflicts in the alternative process selection. To resolve safety conflicts, thorough understandings of all the hazards associated with the process options are vital. This paper presents a systematic screening procedure for reviewing inherently safer design alternatives using a combination of three-stage ISD matrix tool and guide word approach. The proposed methodology was applied to the ammonia supply system with the objective to understand the trade-off of inherent safety toward the overall process. The results show that the proposed tool is capable of helping users understand the impact of modification toward the safety and implementation cost.

Aqueous phase characterization and thermodynamic modeling of the vapor liquid equilibrium of CO2 in a reactive solvent are important for designing and operating CO2 removal systems. A quantitative method using Raman spectroscopy was applied to determine the absorption capacity and molality of various ionic and molecular species in liquid phase CO2 loaded monoethanolamine (MEA) solutions. Species distribution profiles during absorption were reported for a wide range of CO2 loading. CO2 solubility in aqueous MEA with concentrations varied from 10 to 30 mass% were studied using in situ Raman spectroscopic analysis for pressure ranges from 1 to 50 bar at 303.15, 313.15 and 323.15 K. Vapor liquid equilibrium data for the CO2–MEA–water ternary system was analyzed using the Deshmukh–Mather model.

Cryogenic distillation columns are generally subjected to high-pressure loadings during the natural gas purification process. The high-pressure conditions inside the column cause safety risk e.g. rupture. When an emergency arises, blowdown is a typical way of minimizing the failure hazard. However, blowdown at the cryogenic conditions involves dry ice formation due to the rapid decrease in temperature driven by the Joule-Thomson effect. The dry ice formation intensifies the failure hazard due to the orifice blockage. Therefore, optimization of blowdown parameters is necessary to avoid the dry ice formation. So far, very limited studies are available in the literature for the blowdown of CO₂-CH₄ mixture, especially at the cryogenic conditions. In this study, a computational investigation followed by the experimental validation is accomplished to analyze the dry ice formation during blowdown of CO₂-CH₄ binary mixture from the cryogenic distillation column. The composition of mixture, orifice size, and initial conditions inside vessel have a high impact on blowdown path. A 3.00 mm orifice is the most suitable size for the blowdown at cryogenic conditions as it doesn't promote solidification and discharges the inventory quickly. Based on the experimental observation, an empirical correlation is also developed to instantly find out the optimum blowdown parameters.