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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.

For flow assurance applications, various chemicals are used in the oil and gas industry in order to mitigate corrosion. Among corrosion suppressing compounds, quaternary ammonium salts (QASs) find an exceptional usage as these relatively long chain compounds adsorb onto the surface of the pipeline. The formation of protective layer by adsorbing on the surface prevents corrosion. In this work, tetramethylammonium acetate (TMAAc) which is QAS is evaluated as a corrosion controlling compound in saline environment using weight loss method. The weight loss experiments are performed with the solution concentrations of TMAAc at 0.01, 0.5, 1, 2, 5 and 10 wt%. Corrosion rate values are determined at these concentrations. It is observed that the corrosion with the increase in concentration of TMAAc, corrosion rate is also increased. Rate of metal corrosion varies from 0.068 mm/yr to 0.176 mm/yr in the range of 0.01–10 wt%. The minimum value of corrosion rate is found to be 0.068 mm/yr at the sample concentration of 100 ppm. It is concluded that at lower concentrations, TMAAc can find its application as a commercial corrosion inhibitor.

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.

Chemical process manufacturing is associated with risks, which cannot be eliminated. Anyhow, controlling or minimizing of risks is possible up to a certain extent through various process safety strategies. Among these strategies, the inherent approach offers a sustainable process design. This review aims to offer an extensive survey regarding the bibliometrics and the features of the state-of-the-art inherent assessment methods. For the bibliometric part, numerous trends like publication trend, authors and geographical cooperation and prominent keywords are presented using the VOSviewer software. For the second intention, the scope and features of inherent assessments methods for sustainable process design are discussed in addition to the historical development of these methods. The techniques are categorized among seven groups based on the method adopted for inherent assessment along with the benefits and detriments of each group. It is revealed that initially, the inherent assessment has focused on the comparison of various process routes, whereas, the modern methods intend to minimize the risk. Furthermore, it is recognized that the process equipment approach is not much explored yet, which may improve the sustainable process designing via the equipment characteristics. Finally, the limitations of present schemes and future research directions for inherent assessment implications in the sustainable process design are also highlighted, such that the objectives of economic, healthier, safer and environmental-friendly process plants can be materialized. © 2019 Elsevier Ltd

In this study, three mixtures of methylyltriphenylphosphonium bromide (MTPPB) as hydrogen bond acceptor (HBA) and N-methyl diethanolamine (MDEA) as hydrogen bond donor (HBD) component was used to prepare transition temperature mixtures (TTMs) into different mole ratios of 1:7, 1:10 and 1:16 HBA/HBD. Two important physicochemical properties of TTMs such as density and refractive index were investigated at the atmospheric pressure and temperature ranges of (293.15–353.15) K and (293.15–343.15) K, respectively. The experimental density data were used to derive the molar volume, molecular volume, lattice energy and isobaric thermal expansion coefficients. With the help of experimental refractive index data, the electronic polarization, molar refraction, and free volume were calculated at the whole temperatures. Several empirical equations were used to correlate refractive indices such as an empirical equation and one-parameter equations (Dale–Gladstone, Eykman, Lorentz–Lorenz, Newton, Arago–Biot, and Oster). Finally, the response surface methodology (RSM) was applied to evaluate the effects of two main factors such as temperature and mole ratio on the density and refractive index of TTMs. The results revealed that the molar ratio has almost a higher effect on the studied properties than temperature.

3-dimethylaminopropylamine (DMAPA) and glycine (GLY) mixture was studied as a potential absorbent for carbon dioxide (CO2) capture and utilization. The solubility of CO2 in aqueous GLY-DMAPA solutions within the range of 0.1–2.0 mol/L (M) were measured experimentally using pressure differential technique. Utilization of CO2 was also studied by mixing the CO2-saturated absorbent with ethanol. The final products obtained were characterized by using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The solubility study revealed that the CO2 loading capacity increased as pressure of CO2 increased. In contrast, the loading capacity decreased when concentration of the absorbent and temperature in equilibrium cell increased. However, the total moles of CO2 absorbed showed an opposite trend such that net CO2 absorbed increased as concentration of absorbent increased. The chemical interactions between CO2 and GLY-DMAPA molecules were studied by analyzing the changes of characteristic peaks observed form the FTIR spectra. For CO2 utilization, the addition of ethanol as a reagent into 0.1 M CO2-saturated GLY-DMAPA solution did not produced any precipitate. Nonetheless, as the concentration of GLY-DMAPA increased from 0.5 M to 2.0 M, white precipitates were produced, indicated that the conversion of CO2 into solid compounds occurred instantaneously after the CO2 capture. The optimum concentration of GLY-DMAPA for CO2 capture and utilization depends on the amount of solids generated and the CO2 loading capacity of the absorbent. At 5 bar, the optimum concentration was found to be 1.0 M with 45 mg/g of solids recovered and CO2 loading capacity of 1.6 mol CO2/mol absorbent. The final product was identified as carbamate salt based on the main characteristic peaks present on the FTIR and XPS spectra.

The increasing global energy demand has compelled the researchers to utilize the undeveloped contaminated natural gas (N.G) reservoirs. However, due to the emissions standards established by environmental regulatory authorities, N.G treatment has become more crucial. Amongst the established CO2 separation strategies, the cryogenic CO2 removal techniques are promising due to environmentally friendliness, high N.G purification, low footprint values, no chemical reaction involved and capable of handling N.G with high CO2 content. Design and operation of a cryogenic process require accurate thermodynamic knowledge along with the understanding of the phase behavior of CO2 with light alkanes to make the process cost–effective. Furthermore, the study of frosting and liquefaction behavior of CO2 or CO2–alkanes mixture is significant for the energy minimization and smooth operation of the cryogenic CO2 removal from N.G. This paper provides a critical review of the available experimental and predicted thermodynamic data for CO2–alkanes mixtures at different conditions. The significance of pressure–temperature (PT), pressure–composition (P–xy), and temperature–composition (T–xy) phase diagrams for CO2–alkane mixtures are discussed in this paper. This paper also describes the use of the equation of states (EoS) for predicting the thermodynamic phase behavior of the CO2 mixtures. This review will help the researchers in designing more efficient, economical, and sustainable cryogenic CO2 capture processes.

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.

CO 2 capture using cryogenic packed beds with spherical glass packing material has great potential for applications in the natural gas industry. However, the influence of packing material on their performance has been rarely studied. In the present work, some novel packing materials, including Cellulose Acetate and CA/NH 2 −MIL−101(Al) were used to enhance the performance of the cryogenic packed bed. Pressure drop was determined as a function of specific surface area and module filling fraction experimentally. The CO 2 capture efficiency of the system, axial temperature profile study during cooling and CO 2 recovery steps for the spherical glass beads, CA hollow fibres and composite CA/NH 2 −MIL−101(Al) hollow fibres were also investigated. It was found that the hollow fibres reduce the pressure drop by a factor of 61 % and 33 % compared with the pressure drop caused by the spherical glass beads and monofilament fibres, respectively. The specific surface area provided by the hollow fibres was 230 % and 122 % more than that offered by the glass beads and monofilament fibres respectively. It was also observed that the CO 2 capture efficiency of composite hollow fibres was 141.9 % more than spherical glass beads and 9.5 % greater than the pure CA hollow fibres. The temperature profile study reveals that pure CA and the composite CA/NH 2 −MIL−101(Al) hollow fibres require less energy for cooling than glass beads and provides higher bed saturation time. It was concluded that the NH 2 −MIL−101(Al) hollow fibre reduces the pressure drop and capital cost along with increasing the CO 2 capture efficiency.

In this work, the impact of functional group on the thermodynamics and kinetics of CO2 hydrates are investigated experimentally. The hydroxylated multi-wall carbon nanotubes (OH-MWCNT) and carboxylated carbon nanotubes (COOH-MWCNT) along with pristine carbon nanotubes (MWCNT) are selected for this study. The carbon nanotubes are suspended in a 0.03 wt% sodium dodecyl sulfate (SDS) aqueous solution and the results are compared with SDS aqueous solution at the same concentration of 0.03 wt% and deionized water. The CO2 hydrate phase boundary and kinetic parameters of CO2 hydrate formation including induction time, the initial rate and amount of gas consumed, gas uptake, storage capacity, and water to hydrates conversion are studied. The results show that the nanofluids studied do not affect the equilibrium conditions of CO2 hydrates. In addition, 0.01 and 0.05 wt% of COOH-MWCNT mixed with 0.03 wt% SDS showed highest initial hydrate formation rate and gas uptake. Furthermore, a comparison between SDS and COOH-MWCNT (without stabilizer SDS) at 0.03 wt% revealed that addition of COOH-MWCNT to the water enhance the initial hydrates formation rate compared to SDS.

Risk assessment is an accepted approach used worldwide to improve the sustainability of either the existing process plant or the design of a new installation. In the current practices, risk assessment is normally performed once the design has been completed. A better approach is to perform risk assessment at the initial design stages with the application of inherent safety concept to achieve the sustainable cleaner chemical process. This paper consolidates a new technique to improve the safety level of process piping from potential fire risk using the inherent safety concept. Inherently safer process piping (ISPP) technique utilizes fundamental of fluid flow to predict the potential damage from a major fire accident. A relative ranking of process streams is used to identify the critical process streams that have higher chances of damage. Risk assessment is performed to check if the potential fire exceeds the acceptance criteria or not. If the risk is not in the acceptable range, inherent safety principle is used to reduce the risk to the acceptable limit. The ISPP technique is validated using a case study of methanol process plant. This technique could be used to facilitate design practitioners to incorporate inherent safety at the early design stage.

In this study the dual-functionality of four ammonium based Ionic Liquids (AILs) having hydroxide anion namely: tetramethyl ammonium hydroxide (TMAOH), tetraethyl ammonium hydroxide (TEAOH), tetrapropyl ammonium hydroxide (TPrAOH) and, tetrabutyl ammonium hydroxide (TBAOH) is investigated on binary mixed gas hydrates (50 mol%-50 mol% CO2-CH4). For thermodynamic behaviour, the hydrate liquid vapour equilibrium (HLVE) data are generated in the presence of 10 wt% AILs solutions by the T-Cycle method at temperature and pressure conditions of 275.0–284.0 K and 2.0–6.50 MPa, respectively. THI results revealed that apart from TBAOH, all the considered AILs can shift HLVE curve towards higher pressure and lower temperature regions. Obtained results are further compared with commercial THI inhibitors. Average suppression temperature (Ŧ), Enthalpy of hydrate dissociation (∆Hdiss) and Freezing point temperature (Tf) are also calculated for considered systems. The electrolyte based model is applied for validation of experimental HLVE data. Also, formation kinetics of studied AILs is reported for 1 wt% aqueous AILs solutions at 6.50 MPa with different experimental temperatures (274.0 K and 277.0 K). Induction time, initial formation rate, Relative Inhibition Power (RIP) and total gas uptake are the reported parameters for kinetic study. Furthermore, kinetic results are compared with commercial kinetic inhibitor namely: polyvinyl pyrrolidinium (PVP) at 274.0 K condition. Kinetic data suggested that all the studied AILs can perform as KHI inhibitors. Therefore, the considered AILs (except TBAOH) are able to perform as dual-functional inhibitors which highlight the use of AILs as a potential dual-functional gas hydrate inhibitors for sustainable flow in gas transmission pipelines.

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.

Hollow fibre mixed matrix (HFMM) membranes with nano-filler embedded in polymer matrix offer an attractive route for the fabrication of high performance gas separation membranes. However, the quest to achieve high performance mixed matrix membranes remains a challenge without acquiring even filler distribution in polymer matrix. In this work, HFMM membranes comprising polyetherimide (PEI) with various inorganic and organic montmorillonite (I-MMT and O-MMT) loadings ranging from 1 to 4 wt%, were developed via phase inversion method and coated with PDMS for CO2/CH4 separation. Morphological, filler distribution, dispersion, surface topology and gas separation studies were carried out for developed hollow fibre (HF) membranes. Pure gases (CO2 and CH4) were used at varying pressure of 2–10 bars at ambient conditions. In addition, mixed gas test at CO2/CH4 composition of 50/50 v/v % was carried out for selected membranes. Upon incorporation of I-MMT, the developed mixed matrix membranes (MMMs) showed decrease in CO2/CH4 gas separation performance compared to neat PEI membrane. In contrast, the performance of asymmetric membrane was enhanced by incorporating O-MMT in PEI matrix to form MMMs. Uniform dispersion, void-free morphology and reduced surface roughness were observed for the aforementioned membranes. Furthermore, an increasing trend in ideal selectivity was observed up to 2 wt% O-MMT loading against all feed pressures. Thereafter, opposite trend was observed with increasing filler loading due to filler agglomeration. The maximum ideal selectivity achieved was 18.35 with 2 wt% loading at 4 bar pressure which is 52.2% higher than neat PEI hollow fibre membrane.

The continuous exploration of new gas reserves along with the increase in the global power demand necessitates the development of less demanding technologies, such that the treatment process can be accomplished at a minimized cost. One of the most common and mature technology is the chemical absorption process. Absorption process based on carbonate solvents are currently of interest as a technical alternative that have the potential to overcome the disadvantages of the widely established amine based solvents. One such solvent is potassium carbonate. The challenge associated with this solvent, however, is the slow reaction rate resulting in poor CO2 mass transfer and relatively larger absorption equipment is required. Therefore, there is a significant interest in exploring the possibility of rate enhancement by using promoter to accelerate the mass transfer. Various promoters for carbonate based solvents are studied in recent years including organic and inorganic promoters but the ongoing challenge for this process is to assess the performance of the new mix solvent under a wide range of conditions at a larger scale. Hence, modelling and simulations are required to observe the complex interplay between the chemical and physical properties. In this current work, different promoters are reviewed and the main modelling approach for simulation model development is presented. The main objective is to explore various theoretical approaches to improve design and operation using promoted potassium carbonate. Hence, the modelling and simulation section in this review is divided into 3 major parts; (i) Kinetic modelling & chemical reaction, (ii) Thermodynamic model & physical properties, (iii) Hydrodynamics & mass transfer. The reviews end with conclusions and the challenges in term of absorption efficiency using potassium carbonate and the influences to real applications as well as future directions are highlighted.

A complementary study, which involves computational and in-house collected experimental work, has been employed to elucidate the swelling effect within polysulfone membranes by CO2 at varying operating temperatures. The simulation models have been constructed with accordance to collected experimental data. The experimental and simulated sorption isotherms of CO2 are in fairly good agreement with one another. Subsequently, the constructed molecular structures of unswollen and swollen polysulfone membrane at varying operating temperature has been analyzed to study the effect of CO2 in terms of physical characteristic, glass transition temperature, relaxation and free volume to determine whether the temperature or concentration parameters are more dominant in CO2 swelling. In addition, radial distribution function (RDF) between CO2 and varying groups within polysulfone has been evaluated to determine association reaction that invokes the dilation. RDF at various operating temperature has been employed to be incorporated within a series of thermodynamic equations in order to quantify the interaction of CO2 with polysulfone that constitutes to swelling.

The growth in energy demand for natural gas has led to the exploration of sub-quality natural gas reserves with high CO2 content up to 80% at the offshore condition with temperature and pressure approximately 50 °C and 70 bar. In this work, a gravimetric technique is used to study CO2 and CH4 adsorptions on 13× zeolites at 50 °C and up to 70 bar pressure as an adequate range for offshore operations. 13× zeolite shows high CO2 adsorption capacity with 5.226 mmol/g at 50 °C compared to 4.29 mmol/g at 70 °C. The same trend is noticed for CH4 adsorption on both temperatures. Four equilibrium isotherm models are used to analyze the adsorption data i.e. Langmuir, Freundlich, Toth, and Sips. Virial isotherm model is applied on the experimental data to illustrate the isosteric heat of adsorption and it shows an excellent agreement with R2 = 0.998 for 13× MSZ. Henry's law constant is estimated utilizing Virial coefficients, which shows higher molar selectivity ratio for CO2 on 13× with α ˜ 3.957 at 50 °C as compared to the α ˜ 3.736 at 70 °C. Extended Langmuir (EL) Model and Multisite Langmuir (MSL) models are applied for 30:70, 50:50, and 70:30 CO2:CH4 binary mixtures. The outcomes of MSL exhibit high agreement with the quadrupole and polarizability of the single component and the mixtures. The kinetic rate constant is estimated according to the applied LDF model at higher operational regions. The 13× MSZ shows feasibly good isosteric heat of adsorption, which might refer to the large surface area and pore volume that can accommodate CO2 at higher speed and quantity at offshore conditions.

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.

Gas hydrates have been considered as a promising approach for gas separation, storage, and transportation. However, there are inherent restrictions that hinder this technique for commercialization such as slow hydrate formation, severe gas hydrate formation conditions, and limited storage capacity. Kinetic hydrate promoters are used to incorporate more gas into the liquid phase in order to enhance the hydrate formation process. This comprehensive review sheds light on the use of nanomaterial for gas hydrate promotion and relevant kinetic parameters. This review also addresses the factors that might rule the performance of nanofluids as promoters.

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.

In this work, GERG2008 EoS embedded in volumetric-gravimetric system was developed to allocate multicomponent partial/individual components uptakes in the mixture. The refined arrangement may overlay the current theoretical anticipated outcomes and interchange it with experimental and more trustworthy selective adsorption outcomes. 13X zeolite was utilized as a solid adsorbent for binary and ternary CO2:CH4:H2O mixtures adsorption. Premixed and preloaded water vapor was studied at 343 K and up to 10 bar. Artificial neural network (ANN) modeling was engaged to predict binary and ternary mixtures. ANN results disclosed decent promise with experimental data. Besides, simulated formations utilizing ANN model replicated high consistency. The testified outcomes magnificently identified particular components behavior in ternary and higher multicomponent mixtures.

The continuous exploration of new gas reserves along with the increase in the global power demand necessitates the development of less demanding technologies, especially in terms of energy minimization. However, the development of CO2-rich type of gas resources poses significant challenges in the sour gas treatment industry due to bulk CO2 contaminants and high overflowing pressure at the well- head. For the treatment of CO2 rich natural gas, reliable data at high CO2 partial pressure condition is very crucial and the insight of the transient conditions must be thoroughly studied to design a controlled process that can handle any disturbances that might arise in the future. This paper reports the dynamic modelling and basic regulatory control studies of a high-pressure absorption pilot plant, which is located at Universiti Teknologi PETRONAS (UTP), for CO2 removal using MEA solvent. Steady state simulation has been demonstrated using Aspen Plus utilizing both equilibrium and rate based approaches. Dynamic and control analysis is then carried out in Aspen Dynamic using a modified equilibrium stage model.

In this study, thermo physical properties such as density, viscosity, refractive index and surface tension of aqueous solutions of tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH) and tetrabutylammonium hydroxide (TBAOH) was investigated as a function of temperature. These properties were measured in temperatures ranging from 298.15 to 333.15 K and the temperature was increased by an interval of 5 K from 298.15 K and after 303.15 K, it was increased by an interval of 10 K, while the concentrations of all the aqueous solutions were changed from 2.5 to 30 mass percent. The results revealed that the measured properties of all aqueous ILs are inversely related to temperature, while the increase in concentration had different effects on these properties. In the case of density, an increase in the concentration of ILs TMAOH and TEAOH increased their density, while the increase in the concentration of TPAOH and TBAOH decreased their density. On the other hand, the viscosities and refractive indices of all aqueous ILs increased with an increase in concentration, but the surface tensions decreased with the increase in concentration. The derived properties including thermal expansion and excess molar volume of all the aqueous ILs were determined using density data. The thermal expansion data showed an increasing trend with an increase in the temperatures and concentrations of ILs whereas the negative values of excess molar volumes decreased with an increase in temperatures. The correlation of thermo physical properties with temperatures exhibits a good agreement between experimental and predicted values.

The transition-temperature mixture (TTM) is a new type of solvent and is known as a tuneable solvent similar to deep eutectic solvent (DES). The new type of solvent called ternary transition-temperature mixture (TTTM) was prepared to use for CO2 capture purposes. In this work, TTMs and TTTMs were prepared with potassium carbonate (PC) as a hydrogen bond acceptor (HBA) and three hydrogen bond donors (HBDs) such as glycerol (GL), ethylene glycol (EG) and 2-amino-2-methyl-1-3-propanediol (AMPD) known as a hindered amine (HA). Binary TTMs were PC-GL with mole ratios 1:10 and 1:16 and PC-EG with the same mole ratios. TTTMs were prepared by adding AMPD in binary TTMs such as PC-GL-AMPD 1:16:1 and PC-EG-AMPD 1:10:1. The experimental density and refractive index of all mixtures were measured at temperatures from 293.15 K to 343.15 K with an interval of 5 K. The effect of temperature, mole ratio, molar massand alkyl chain length on the properties was investigated. The molar volumes and isobaric thermal expansion were calculated using experimental density data. The experimental refractive index values were used to derive the specific refraction, molar refraction, free molar volume, electronic polarization and polarizability at several temperatures.

In this work, critical and supercritical operating conditions for CO2 removal studies had been inspected on 13X and 5A Zeolites in terms of CO2 adsorption, at 150 bars and two different operating temperatures, 50 and 70 °C. The newly developed and very high accuracy (10−6 precision) setup which consisted of gravimetric measurements was used to study the static adsorption. Excess isotherms had been corrected (Absolute/Gibbs isotherms) and measured. 13X zeolite showed higher adsorption which was 330 mg/g at 50 °C and 300 mg/g at 70 °C for CO2 at supercritical conditions, compared to 5A zeolite 280 mg/g, 230 mg/g, respectively. The absolute isotherms for both adsorbents are further predicted and simulated via artificial neural network (ANN) modeling. However, the predicted and simulated isotherms showed high agreement and consistency to the experimental data, respectively. Results for both adsorbents were fitted to the most favorable equilibrium models, namely Langmuir, Freundlich, Toth, and Sips isotherm. The results showed high acceptance (R2 0.999) for Langmuir and Toth, especially at higher pressure. Virial curves and coefficients had been used to identify the Isosteric Heat of adsorption for 13X and 5A zeolites at the operating temperatures and pressure range. The curves illustrated that 5A started to saturate faster than 13X. The fluidical density of CO2 was observed at 0.7070 g/cm3 and 0.5054 g/cm3 on 13X at 50 and 70 °C respectively, and 13X had a higher fluidical density of CO2 compared to 5A. 13X and 5A zeolites showed lower rate constants at 70 °C compared to the values at 50 °C. The kinetic rate constant i.e.: k ≈ 0.0098 at 50 °C and 0.0013 at 70 °C on 13X, and k ≈ 0.0026 at 50 °C, and 0.0021 at 70 °C on 5A were observed at 150 bar.

In present study, high pressure CO2 absorption performance of aqueous N-methyldiethanolamine (MDEA) and its hybrid solvents with anhydrous perazine (PZ) and ionic liquid (IL) 1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][OTf] were investigated. The absorption performance of hybrid solvents were carried out to investigate CO2 loading capacity (mol of CO2/mol of solvent), and apparent absorption rate (CO2 capture efficiency, overall rate constant). The CO2 loading capacity of aqueous MDEA and its hybrid solvents were experimentally investigated for a wide range of compositions between pressure ranges of 2 to 50 bar and at three different temperatures (303.15, 313.15, and 333.15 K). Furthermore, apparent absorption rate performance of hybrid solvents were determined at 303.15 K temperature and 2 bar pressure. The effect of temperature, CO2 partial pressure, and ionic liquid (IL) concentrations on CO2 loading of aqueous IL-amines hybrid solvents were also investigated. The results indicated that CO2 loading of hybrid solvents were increased with increase in CO2 partial pressure and IL concentration (up to 10 wt%), further increased concentration of IL suppressed CO2 loading capacity. The CO2 loading capacity of hybrid solvents were also reduced with rise in system's temperature. The addition of IL and anhydrous PZ significantly enhanced CO2 capture efficiency (nCO2) and overall absorption rate constant (k) of aqueous MDEA solvent.

Correlation for effective surface area is one of the important input for modeling of gas absorption in countercurrent packed column. Although the correlation previously developed by other researchers was able to provide quite decent prediction of carbon dioxide (CO2) absorption system, improvement still need to be done especially for high pressure condition whereby consideration for the decrease of effective surface area due to severe vapour backmixing situation needs to be taken into account. In this work, pressure dependent correction correlation was developed by incorporating the ratio of liquid to gas densities. The correlation developed in this study was found to successfully improve the prediction trend of the CO2 concentration profile along the column

The variation of temperature, pressure and composition during cryogenic purification of natural gas using cryogenic packed bed network significantly affects separation. The present work aims to optimize cryogenic packed bed network for maximum product purity with minimum hydrocarbon losses. The separation concept between components of natural gas is based on the difference in freezing points of individual components and their composition in the mixture. The overall process of cryogenic packed bed pipeline network consists of the initial cooling of each bed, the capture of individual component and regeneration of each bed. In previous studies, the process concept of cryogenic packed bed network was validated using experimentation but the optimization study was not carried out. The simulation results and thermodynamic behavior of the individual component in the mixture are included to further explain the process concept. The sensitivity study was carried out to investigate the effect of the temperature and the pressure of each packed bed. For sensitivity study, node-edge schemes were developed and discussed in details by changing operating conditions of packed beds. Based on the node-edge scheme analysis, the optimum values for both temperature and pressures were selected for maximum separation and minimum methane loss. The energy requirements for both dehydration and CO 2 removal were calculated experimentally and compared with simulation results. For the simulation results, Aspen Hysys simulator was used along with Peng-Robinson fluid package. The energy requirements for both simulation and experimental results were calculated at atmospheric and high pressures. Both local and global optima were calculated using golden section search and depth-first strategy. The initial local optima result showed that the product purity can reach up to 77% methane, further optimization using depth-first strategy showed the product purity up to 94% with reduction of hydrocarbon losses from 39 to 16%.

This paper presents a series of experimental and modelling studies on the thermodynamic inhibition effects of four ionic liquids on the methane hydrate formation. The investigated ionic liquids are 1-methyl-3-octylimidazolium chloride MOIM-Cl, 1-methylimidazolium hydrogen sulfate H-MIM-HSO4, tetraethylammonium iodide TEA-I, and 1-hexyl-3-methylimidazolium iodide HMIM-I. The impact of 0.1 mass fraction concentration ionic liquids on the methane hydrate phase boundary was evaluated by measuring the dissociation temperature of methane hydrate in the pressure range of 5.1�11.1 MPa, using a high pressure differential scanning calorimeter. The molar dissociation enthalpy of methane hydrates was calculated using the Clausius�Clapeyron equation. The density was measured for 0.10 mass fraction of aqueous solutions of ionic liquids at 293.15 K, and then compared to the commercially available gas hydrate inhibitors. The results demonstrated that 1-methylimidazolium hydrogen sulfate H-MIM-HSO4 has the highest inhibitory performance among the four ionic liquids considered. Moreover, the Dickens and Quinby-Hunt (electrolyte) model was applied to predict the phase equilibrium data of the studied ILs. The predicted data is in agreement with the experimental data. © 2017

A magnesium-based metal-organic framework (MOF), Mg-MOF-74, has been denoted as a landmark for CO2 capture due to its highly porous structure and strong metal adsorptive sites. However, the gas uptake would be improved if particle texture could favor diffusion into the micropores and accessibility to the adsorption sites. For that reason, multi-wall carbon nanotubes (CNT) or monolayer graphene oxide (GO) was introduced into the MOF material at 0.3 wt% via in-situ synthesis method as an attempt to improve gas adsorption capacities. Mg-MOF-74, Mg-MOF-74@CNT and Mg-MOF-74@GO were synthesized under solvothermal reaction and characterized by PXRD, FTIR, FESEM, TGA and N2@77 K and CO2@298 K adsorption/desorption analysis. The morphology of the Mg-MOF-74 composites showed that the particles were composed of agglomerated crystallites of which the crystal structure was well-preserved with the adjunction of carbon doping agents. The BET specific surface area and the micropore volume of the Mg-MOF-74 pristine material respectively attained 1370 m2/g and 0,4 cm3/g whilst these values were increased up to 1660–1720 m2/g and 0.49 cm3/g for carbon composites. These variations were attributed to better activation of carbon-MOF composites thanks to more regular arrangement of the crystallites composing the agglomerates, facilitating the evaporation of the organic solvent during the thermal treatment applied in the last stage of the synthesis. The introduction of a small fraction of CNT and GO in the reactant mixture also improves the crystallization process, leading to average larger particle sizes. Consequently, the uptake of CO2 at 1 bar and 25 °C was shown to be improved by 18 mol% and 23 mol% for Mg-MOF-74@CNT and Mg-MOF-74@GO, respectively, compared with the pristine Mg-MOF-74. This current work demonstrates that by doping Mg-MOF-74 synthesis with carbonaceous agents, although at very low concentration levels, both morphological and textural properties are modified leading to larger gas adsorption capacities.

Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, DES namely allyltriphenyl phosphonium bromide-diethylene glycol (ATPPB-DEG) was prepared by using three molar ratios of 1:4, 1:10 and 1:16 salt to HBD. The volumetric properties of aqueous DESs, such as density, molar volume, isobaric thermal expansion, apparent molar volume and apparent molar expansibility were reported at several temperatures from 293.15 to 343.15 K. A mathematical equation, so-called Jouyban–Acree model (JAM), was used to correlate the experimental density and molar volume data of aqueous solution of DESs with respect to the concentration and temperature. The results disclosed that this model is an accurate and reliable model for the prediction of aqueous DES properties. The excess properties, such as excess molar volume and excess isobaric thermal expansion were reported and fitted to two different equations. In order to calculate the limiting apparent molar volume values, the apparent molar volume values were fitted into a Redlich–Mayer equation. By applying the Hepler equation, it was found that DESs with molar ratios of 1:4 and 1:10 are as structure-maker solutes, while the DES 1:16 is a structure-breaking solute in aqueous solutions at different temperatures.

This research presents the application of predictive regression model such as quadratic regression for estimation of CO2 solubility in deep eutectic solvents namely allyltriphenylphosphonium bromide-triethylene glycol (ATPPB-TEG) into different molar ratios and their aqueous solutions. In doing so, a design of experiment (DOE) was applied based on Taguchi L18 orthogonal array method. Four factors, namely pressure, temperature, molar ratio and water/DES concentration in mixture were selected as input parameters of model. The output parameter of model was the CO2 solubility in terms of mole fraction of CO2 (XCO2). A quadratic regression model was developed after validation and confirmation through several strong approaches. The results disclose that the prediction of developed quadratic regression model is in acceptable agreement with experimental solubility data. The overall R-squared (R2) and absolute relative error (ARE) values of proposed quadratic regression model were 0.9966 and 0.0725, respectively. Moreover, analysis of variance (ANOVA) indicates that pressure is the most significant factor influencing the XCO2. Finally, the signal to noise (S/N) ratio shows that the highest levels for pressure, concentration of DES in mixture, and molar ratio, and lowest level for temperature are the optimal levels of input parameters to obtain the highest CO2 solubility in this system. The developed quadratic regression model and correlation are effective and provide quick, reliable and accurate predictions of CO2 solubility in DESs without carrying out any time consuming, difficult and expensive experimental measurements. To the best of our knowledge, this is the first time a regression model was developed for prediction of CO2 solubility in DESs and their aqueous solutions.

In this work, zeolite T particles were modified with three different types of silane groups including, 3-Aminopropyltrimethoxysilane (APTMS), N-(2aminoethyl)-3-aminopropyl-trimethoxysilane (AAPTMS) and 3-(2-(2-aminoethylamino) ethylamino) propyltrimethoxysilane (AEPTMS) which contain monoamine, diamine and triamine group, respectively, before incorporated into 6FDA-durene polyimide. The physicochemical properties of the particles and the resultant membranes were characterized using XRD, FESEM, EDX, FTIR, TGA and DSC. The results demonstrated that the incorporation of APTMS modified zeolite T particles into 6FDA-durene polymer matrix failed to improve the interfacial adhesion between filler and polymer phases. This phenomenon subsequently contributes to the reduction of CO2 permeability of 9.3% and decrement of CO2/CH4 selectivity of 29.5% as compared to membrane incorporated with unmodified zeolite T, which showed CO2 permeability and CO2/CH4 selectivity of 844 Barrer and 19.1, respectively. Meanwhile, composite membranes loaded with AAPTMS and AEPTMS modified zeolite T particles have effectively enhanced the filler/polymer interfacial adhesion and separation properties of the membranes. Although the incorporation of AAPTMS zeolite T particles into 6FDA-durene polymer demonstrated 2.7% reduction of CO2 permeability, increment of CO2/CH4 selectivity up to 26.4 was obtained, which successfully lies on Robeson upper limit 2008. Meanwhile, composite membrane embedded with AEPTMS modified zeolite T particles has resulted in the increment of both CO2 permeability and CO2/CH4 selectivity of 857.7 Barrer and 22.5, respectively. Overall, the effect of different amine groups in the modification of zeolite T surface on the performance of the composite membranes has been demonstrated in this work.

CO 2 capture for power plant and natural gas purification using absorption process suffers two major drawbacks: large absorption body and high regeneration energy. The high energy penalty of absorption technology can be addressed using low heat of absorption solvent. However, the challenge of using low heat of absorption solvent is to develop a practical approach to intensify absorption rate. In recent years, high frequency ultrasonic system emerges as a potential technology for mass transfer process. In this study, the potential of using high frequency ultrasonic system have been investigated using the slow kinetic solvent: (potassium carbonate) without utilizing any chemical promoter. The ultrasonic-assisted absorption system with 20 wt% potassium carbonate (without promoter) has provides 1.75 times higher volumetric mass transfer coefficient than the Piperazine (PZ) promoted potassium carbonate using stirring method. The absorption rate has been increased up to 32 times as compared to the case without ultrasonic irradiation. Besides, the required absorption time to achieve 0.9 loading (CO 2 mole/K 2 CO 3 mole) has been significantly reduced to approximate 400 s. Furthermore, an ultrasonic-assisted absorption model has been developed by including the atomization, ultrasonic streaming, and ultrasonic chemical effect in order to investigate the mechanism involved in high frequency ultrasonic-assisted absorption. Based on the model validation study, the ultrasonic chemical effect is essential to be considered in order to match the simulated and the experimental results. The results of current study prove that, high frequency ultrasonic system possesses high potential to be utilized to enhance the absorption using promoter-free potassium carbonate.

Deep eutectic solvents (DESs) are derived from the concomitant reaction of two or more salts i.e. between hydrogen bond acceptor (HBA) and hydrogen bond donors (HBD) components. In this work, DESs were prepared namely allyltriphenyl phosphonium bromide-diethylene glycol (ATPPB-DEG) and allyltriphenyl phosphonium bromide-triethylene glycol (ATPPB-TEG) into three molar ratios 1:4, 1:10, and 1:16 salt to HBDs. The carbon dioxide solubility in DESs at temperature of 303.15 K and pressure up to 2 MPa were determined and reported in terms of mole fraction, CO 2 loading and Henry's law constants. Krichevsky–Kasarnovsky equation was used to correlate the solubility data and obtain Henry's law constants at 303.15 K. Finally, the effects of hydrogen bonding within DESs, molar ratio, molar volume, free volume, ether group and alkyl chain length were investigated based on CO 2 solubility in DESs. To the best of our knowledge, this is the first time CO 2 solubility in these DESs was studied.

Recently, deep eutectic solvents (DESs) as the new solvents have received considerable amount of attention between researchers in different research fields and are under investigation so find out their potential to become a versatile alternative to ionic liquids (ILs) and traditional solvents. DESs are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). Six DESs were synthesized namely allyltriphenylphosphonium bromide- diethylene glycol (ATPPB-DEG) and allyltriphenylphosphonium bromide- triethylene glycol (ATPPB-TEG) using three mole ratios of 1:4, 1:10 and 1:16 salt to HBDs. In this work, we report physicochemical properties of these DESs, which include density, molar volume, isobaric thermal expansion, refractive index, specific refraction, molar refraction, free molar volume, electronic polarization and internal pressure at several temperatures from 293.15 K to 343.15 K. Most of these properties are fitted to a linear equation by the method of least-squares using the Levenberg-Marquardt algorithm to derive the corresponding parameters and estimate the root mean square error (RMSE) and least squared correlation coefficient (R2).

Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, six deep eutectic solvents (DESs) were prepared namely allyltriphenyl phosphonium bromide- diethylene glycol (ATPPB-DEG) and allyltriphenyl phosphonium bromide - triethylene glycol (ATPPB-TEG) using three molar ratios of 1:4, 1:10 and 1:16 salt to HBDs. The temperature range for experimental viscosity was from 293.15 to 343.15 K and that of the experimental surface tension was between 298.15 and 343.15 K. The results disclosed that hydrogen bonding in DESs has a great effect on the properties. Among all DESs with the same components, the DESs with the strong hydrogen bonding in their structures had the higher viscosity and surface tension. Besides, by increasing the temperature and quantity of HBDs in DESs, both of these properties experienced a decreasing trend in the amount. It was found that the molecular weight of DESs with the same component has an effect on the properties. The higher molecular weight caused the higher viscosity and surface tension. Further, ATPPB-TEG DESs had the higher viscosity and lower surface tension than ATPPB-DEG DESs because of the higher alkyl chain in their structures. Several models and a new empirical equation were used to correlate the experimental viscosity data. It was found that there is a well agreement between theoretical and experimental values especially when the new empirical equation is used. In addition, the activation parameters for all DESs were calculated using the experimental viscosity data and application of Eyring's absolute rate theory. The experimental surface tension was employed to predict the critical temperature, surface entropy and internal surface energy of DESs. Finally, two empirical equations were used for relating the experimental surface tension to the experimental viscosity of DESs.

The paper aimed to study the chemical absorption of CO2 in monoethanolamine solvent (MEA) using high frequency ultrasonic irradiation of 1.7 MHz. The experiment was conducted at instantaneous regime in order to study the physical enhancement effect of the ultrasound. Hence, a mathematical model is proposed to justify the enhancement effects involved in the absorption process. The parameters of the experiment included ultrasonic power, MEA concentration, temperature, and CO2 partial pressure. Results show that, a significant increase in the chemical absorption rate can be obtained by using ultrasonic power of 18 W, which is up to 60 times faster than the case without ultrasonic irradiation. Besides, the experimental data is in good agreement with the simulated data by obtaining the R2 values ranged from 0.989 to 0.997. Therefore, this study demonstrates a new technology to improve the absorption process. Besides, the enhancement for the chemical absorption using ultrasonic irradiation is believed to be dominated by the fountain formation and also the convective dynamic. In overall, ultrasonic-assisted absorption would be one of the potential alternatives for CO2 capture with its advantages of high mass transfer coefficient and compact design.

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.

Mixed matrix membrane with nano-filler embedded in polymer matrix, is receiving overwhelming attention for gas separation applications due to its attractiveness in providing an economic solution to enhance permselectivity. However, achieving uniform dispersion of nano-filler in host polymer remains a key challenge in developing membrane. In this work, mixed matrix hollow fibre membranes comprising polyetherimide (PEI) with various modified montmorillonite (f-Mt) loading, was developed via phase inversion method for CO2/CH4 separation. The Mt was modified with aminolauric acid to impart organophilicity to enhance compatibility towards organic polymer matrix. The synthesized hollow fibers were characterized using field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and permeation test. The permeation tests were carried out with pure gases at ambient temperature with varying pressures of 2 and 4 bars. An increasing trend in ideal selectivity was observed up to 2 wt% f-Mt loading. Thereafter, opposite trend was observed with increasing filler loading due to exfoliated layers that created more tortuous path for the penetrating gas molecules. The maximum ideal selectivity was found with 2 wt% f-Mt loading at 2 bar, which showed 39% increment as compared to neat PEI hollow fibre membrane. This increment in gas selectivity was related to the dispersion state and aspect ratio of f-Mt. Various phenomenological models were employed to calculate the aforementioned properties. Adopting to Cussler and Yang-Cussler models, the aspect ratio of the f-Mt was found to be 35 and 50, respectively with 3–4 particles per tactoid.

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 study, experimental CO 2 solubility in aqueous sodium salt of l -phenylalanine (Na-Phe) was investigated at concentrations ( w = 0.10, 0.20, and 0.25) mass fractions. The solubility was measured in a high-pressure solubility cell at temperatures 303.15, 313.15 and 333.15 K, over a CO 2 pressure range of (2–25) bar. The effect of temperature, equilibrium CO 2 pressure and Na-Phe concentration on CO 2 loading were examined. Two different models namely modified Kent-Eisenberg and artificial neural network (ANN) were used to correlate the CO 2 solubility data. Carbamate hydrolysis and amine deprotonation equilibrium constants were estimated as a function of temperature, pressure and solvent concentration from modified Kent-Eisenberg model. Also, the comparison of prediction results obtained from both modeling techniques was carried out. It was found that ANN model performed better than modified Kent-Eisenberg model.