Chemical Processing Plant Research Articles

Optimization-Based Approach for Process Plant Layout

This paper presents an optimization-based approach for the multifloor process plant layout problem. The multifloor process plant layout problem involves determining the most efficient—based on predefined criteria—spatial arrangement of a set of process plant equipment with associated connectivity. A number of cost and management/engineering drivers (e.g., connectivity, operations, land area, safety, construction, retrofit, maintenance, production organization) have been considered over the last two decades in order to achieve potential savings in the overall plant design process. This work constitutes an extension of the work by Patsiatzis and Papageorgiou [ Ind. Eng. Chem. Res. 2003, 42, 811−824;10.1021/ie020586t] to address the multifloor process plant layout problem. New features introduced modeled tall equipment with height greater than the typical floor height in chemical process plants, with connection points at a design-specified height for each piece of equipment. The number of floors, land area, ...

On the mechanism of pressure rise in vented explosions: A numerical study

Abstract Accidental gas explosions are a significant concern in process industries. In an explosion event, the promotion of flame acceleration due to turbulence generated from obstacles is responsible for many severe damages. This paper discusses the numerical evaluation and the mechanism of pressure rise in vented explosions in the presence of obstructions using computational fluid dynamics (CFD). The large eddy simulation (LES) technique is employed with a dynamic flame surface density (DFSD) in the combustion model to account for the filtered chemical source term. The experimental test case considered for the validation of simulations is a small-scale explosion chamber with removable baffle plates and obstacles. It is found that the maximum overpressure increases with the baffle plates moved downstream from the ignition source or when additional baffles are placed in sequence. Large separation between baffles and the central obstacle results in lower overpressure due to the relaminarisation of the flame front. The trend of explosion overpressure is related to the competition between the strength of venting and expansion in the explosion chamber. Extensive interactions between the flame and the obstruction-generated turbulence are found to wrinkle the flame front and increase the burning rate. Satisfactory agreements have been obtained between LES and the experimental data. This confirms the capability of the developed model in predicting essential safety-related parameters in vented explosions. Results reveal the potential of using LES in the selection of design aspects for loss prevention, such as the area of vents and distance between congested regions in chemical processing plants.

Complex cognitive skill retention: The roles of general mental ability and refresher interventions in a simulated vocational setting

AbstractIn organizations, the assessment of mental abilities is a common way to predict learning success. This paper analyses the effect of general mental ability on skill retention and examines the relationship between refresher interventions and general mental ability in terms of skill retention. Two hundred sixty‐six adult participants were trained to perform a complex cognitive skill in a simulated chemical processing plant (Week 1). After 1 week, 158 participants received intermediate computer‐assisted refresher intervention training in which the skill was applied (Week 2; 108 received no intervention). Finally, participants had to recall (perform) the learned skill after 2 weeks (Week 3). Results show that general mental ability alone affects skill retention with small effect sizes and that refresher interventions affect skill retention positively for low and high general mental ability levels. The findings suggest that persons with low and high general mental abilities benefit equally from refresher interventions in order to maintain complex cognitive skills.

Microwave Chemical Process and Chemical Plant

Microwave Chemical Process and Chemical Plant

Uncertainty Handling in the Safety Risk Analysis: An Integrated Approach Based on Fuzzy Fault Tree Analysis

Chemical process plants, especially the oil and gas plants operating under severe processing conditions and dealing with hazardous materials, are susceptible to catastrophic accidents. Thus safety risk assessment is vital in designing effective strategies for preventing and mitigating potential accidents. Fault tree analysis (FTA) is a well-known technique to analyze the risks related to a specific system. In the conventional FTA, the ambiguities and uncertainties of basic events (BEs) cannot be handled effectively. Therefore, employing fuzzy set theory helps probabilistic estimation of BEs and subsequently the top event (TE). This study presents an integrated approach to fuzzy set theory and FTA for handling uncertainty in the risk analysis of chemical process plants. In this context, the worst case scenario based on a qualitative risk analysis is selected first and then the fuzzy FTA is established. Finally, different fuzzy aggregation and defuzzification approaches are employed to obtain the probability of each BE and TE, the output of each approach is compared to the occurrence probability of TE, and the critical BEs are ranked. The proposed methodology is applied to the fuzzy probabilistic analysis of hydrocarbon release in the BP tragic accident of March 2005. The results indicate that the proposed approach is very effective in risk analysis considering uncertainty reduction or handling.

An emergency response decision matrix against terrorist attacks with improvised device in chemical clusters

Chemical industrial areas may constitute potential targets for deliberate actions by terrorists. Terrorists having sufficient knowledge of chemical process operations or plant layout may take advantage of improvised explosive devices (IEDs) to cause major events such as fire, explosion and toxic gas dispersion with cross-border consequences in chemical clusters. Thus, an efficient cluster-wise emergency plan to enhance the promptness and efficacy of responding to such attacks is crucial. In this study, the effects of blast wave caused by IEDs are assessed and its potentiality in triggering domino scenarios are analysed. A decision tree is developed to determine the emergency level of each company within the cluster based on the attack outcomes. Furthermore, an alert notification system is set based on a decision matrix. Finally, the identified emergency levels and the alert levels are presented in form of a multi-plant decision matrix. The application of the developed methodology is demonstrated in a case study.

Опыт разработки обоснования безопасности опасных производственных объектов взрывопожароопасных химических, нефтехимических и нефтегазоперерабатывающих производств

Опыт разработки обоснования безопасности опасных производственных объектов взрывопожароопасных химических, нефтехимических и нефтегазоперерабатывающих производств

Modified Flower Pollination Algorithm to Optimize WEDM parameters while Machining Inconel-690 alloy

Flower Pollination algorithm (FPA) is one of the global optimization algorithms and was found to outperform genetic algorithm (GA) and particle swarm optimization (PSO) algorithm. In order to improve the performance of existing FP algorithm, a modified FPA has been proposed in the present work. Further, super alloys are finding wide range of applications including power generation turbines, aircraft, nuclear power, automobiles, rocket engines, and chemical processing plants. These materials exhibit superior mechanical and chemical properties. They are found to retain hardness at elevated temperatures, be resistant to corrosion and have low thermal conductivity. Machining of these alloys with conventional processes is very difficult. Wire electrical discharge machining (WEDM) is one of the modern machining techniques and it can machine materials, irrespective of their hardness, as it is a non-contact machining process. Inconel-690, one of the nickel-based alloys is widely used in nuclear power and aerospace applications. The influence of WEDM process parameters such as pulse on time, pulse off time, peak current and servo voltage on responses such as material removal rate (MRR) and surface roughness (SR) has been studied while machining Inconel-690. Mathematical models are developed to predict these responses. The proposed modified FPA has been used to optimize WEDM process parameters. Further, this method has also been applied for simultaneous optimization of the responses. As the current method is found to yield encouraging results, it can be extended to solve other optimization problems also.

Impact Simulation of Straight Tube Heat Exchanger Subject to Cross-Flow

Heat exchangers have been among the most troublesome components of both nuclear power and chemical process plants. Heat exchanger tubes are supported at intermediate points by support plates. Flow- induced vibration of tube can cause it to impact or rub against a support plate or against adjacent tubes and can result in tube fretting wear. Simulation of heat exchanger tube/ support dynamic interaction is presented. The tube/ support interaction parameters, ‘RMS Impact force’ and ‘Contact ratio’ are studied. These are significant inputs to predict fretting wear limited life of the heat exchanger tubes. An algorithm includes equilibrium iteration and variable time stepping based on convergence criteria is implemented in an in-house finite element program. The tool is validated solving documented premature failure case of shell and tube type heat exchanger.

Hybrid Probabilistic Risk Assessment Using Fuzzy FTA and Fuzzy AHP in a Process Industry

There are many available techniques which are widely used for failure probability analysis. Fault tree analysis (FTA) is a well-known method to identify the basic events (BEs) to reach top event. However, the FTA method in real circumstances is limited because of the many unknown and the vagueness of the situations. Thus, fuzzy set theory with respect to subjective expert opinion is employed to cope with the uncertain knowledge of BEs including randomness, ignorance, and shortages of data. In addition, to gain this purpose, much subjectivity may appear; as an example, the main one is the expert weighting. This study highlights the utility of fuzzy set theory and analytic hierarchy process to failure probability analysis in a case study. A chemical process plant has been selected to illustrate the application of proposed model with a comparison of the results with conventional model.

ELECTROMAGNETIC RESONANCE VIBROCAVITATOR

Резонансний електромагнітний віброкавітатор призначений для кавітаційного оброблення рідин на основі води. Ці кавітатори ефективні у використанні для очищення води басейнів аквапарків від біологічних забруднень, для покращення структури питної води. Резонансні електромагнітні віброкавітатори автори створили вперше, їх конструктивна будова захищена патентом на винахід. Конструкція цього вібраційного кавітатора доволі універсальна, що створює передумови для успішного використання її як для трубопроводів незначних перерізів у діапазоні від одного до трьох дюймів, так і для промислових труб водогонів діаметром до 250-300 мм. Особливо ефективним, на нашу думку, вібраційний кавітатор мав би виявитись для біологічного знезараження питної води. Простота його конструкції та обслуговування створюють передумови для вмонтовування кавітатора у трубопроводи перепомповування води в басейнах, аквапарках та водоймах громадського використання, де поряд із знезараженням води здійснюватиметься і її очищення. Внаслідок сплескування кавітаційних бульбашок тут утворюються активні хімічні речовини: гідроксильні радикали, озон, пероксид водню тощо. По суті, ця технологія є комбінованим способом очищувального впливу на воду. Основними вузлами цих кавітаторів є статор із електромагнітами, коливний якір із збурювачами кавітації та резонансна пружна система, що з'єднує якір із статором. Продуктивність кавітаційного оброблення води басейнів – 1,5-2,0 м3/год, ступінь очищення стоків молокопереробних підприємств – 97-98 % за продуктивності до 100 л/год. Продуктивність очищення стоків пивоваріння від дріжджів становить 200-250 дм3/год.

Derived heuristics-based consistent optimization of material flow in a gold processing plant

ABSTRACTMaterial flow in a chemical processing plant often follows complicated control laws and involves plant capacity constraints. Importantly, the process involves discrete scenarios which when modelled in a programming format involves if–then–else statements. Therefore, a formulation of an optimization problem of such processes becomes complicated with nonlinear and non-differentiable objective and constraint functions. In handling such problems using classical point-based approaches, users often have to resort to modifications and indirect ways of representing the problem to suit the restrictions associated with classical methods. In a particular gold processing plant optimization problem, these facts are demonstrated by showing results from MATLAB®'s well-known fmincon routine. Thereafter, a customized evolutionary optimization procedure which is capable of handling all complexities offered by the problem is developed. Although the evolutionary approach produced results with comparatively less variance over multiple runs, the performance has been enhanced by introducing derived heuristics associated with the problem. In this article, the development and usage of derived heuristics in a practical problem are presented and their importance in a quick convergence of the overall algorithm is demonstrated.

Combustion mechanism development and CFD simulation for the prediction of soot emission during flaring

Industrial Flares are important safety devices to burn off the unwanted gas during process startup, shutdown, or upset. However, flaring, especially the associated smoke, is a symbol of emissions from refineries, oil gas fields, and chemical processing plants. How to simultaneously achieve high combustion efficiency (CE) and low soot emission is an important issue. Soot emissions are influenced by many factors. Flare operators tend to over-steam or over-air to suppress smoke, which results in low CE. How to achieve optimal flare performance remains a question to the industry and the regulatory agencies. In this paper, regulations in the US regarding flaring were reviewed. In order to determine the optimal operating window for the flare, different combustion mechanisms related to soot emissions were summarized. A new combustion mechanism (Vsoot) for predicting soot emissions was developed and validated against experimental data. Computational fluid dynamic (CFD) models combined with Vsoot combustion mechanism were developed to simulate the flaring events. It was observed that simulation results agree well with experimental data.

Dap-1 Ammonia Tank Explosion: Safety and Security Concerns in Chemical Process Plant in Bangladesh

Dap-1 Ammonia Tank Explosion: Safety and Security Concerns in Chemical Process Plant in Bangladesh

Modeling of liquid-liquid equilibrium for binary and ternary systems containing ionic liquids with the hexafluorophosphate anion using the ASOG method

Models capable of predicting thermodynamic equilibrium data are essential in developing projects for chemical processing plants. Liquid-liquid equilibrium data (LLE) for systems including ionic liquids are essential for the design and operation of separation processes, but are still scarce. In this sense, the objective of this work is to apply the group contribution ASOG method for calculating activity coefficient data to predict liquid-liquid equilibrium and evaluate their effectiveness in representing the calculated data. ELL experimental data are required for the prediction obtained from the literature for binary and ternary systems containing hexafluorophosphate anion. The modeling was performed with 19 binary and 27 ternary systems at 101.3 kPa and several temperatures. As a result, new ASOG pairs groups were obtained that serve to model new systems that include ionic liquids and other compounds. The average deviation (rms) is approximately 4%. It can be concluded that the ASOG method predicts with good accuracy.

PFA 라이닝 볼밸브의 헬륨누설 검출 및 비산배출에 관한 연구

A PFA lined ball valve, which is machined with fluorinated resin PFA to its inner part for improving corrosion resistance, non-stickness, heat-resistance, has been widely used to the chemical/pharmaceutical industries, the semiconductor/LCD manufacturing processes, etc. with the high purity chemicals as working fluid. EPA stated that 60% of all fugitive emissions come from the valve stem packing in a typical petroleum or chemical processing plant. They monitor regulated components for leaks and maintain seal performance at acceptable levels. Korean industrial standards only deals with the bubble test for in-line leakage of valves, which has the detectable leak rate of 10SUP-4/SUP [mbar·L·sSUP-1/SUP], therefore, it is not sufficient to check fugitive emissions. In this study, we conducted Helium leak detection from a PFA lined ball valve and evaluated fugitive emissions according to ISO 15848-1, which has the detectable leak rate of 10SUP-9/SUP [mbar·L·sSUP-1/SUP], for manufacturing the high-reliable PFA lined ball valves against fugitive emissions.

Experimental investigations on surface integrity issues of Inconel-690 during wire-cut electrical discharge machining process

Nickel-based alloys are finding a wide range of applications due to their superior properties of maintaining hardness at elevated temperatures, low thermal conductivity and resistance to corrosion. These materials are used in aircraft, power-generation turbines, rocket engines, automobiles, nuclear power and chemical processing plants. Machining of such alloys is difficult using conventional processes. Wire-cut electrical discharge machining is one of the advanced machining processes, which can cut any electrically conductive material irrespective of its hardness. One of the major disadvantages of this process is formation of recast layer as it affects the properties of the machined surfaces. In this study, experimental investigation has been carried out to study the effect of wire-cut electrical discharge machining process parameters on micro-hardness, surface roughness and recast layer while machining Inconel-690 material. Interestingly, hardness of the machined surface was found to be lower than that of the bulk material. The micro-hardness and recast layer thickness are inversely related to the variation of process parameters. Recast layer thickness, surface roughness and hardness of the wire-cut electrical discharge machined surfaces of Inconel-690 are found to be in the range of 10–50 µm, 0.276–3.253 µm and 122–171 HV, respectively, for different conditions. The research findings and the data generated for the first time on hardness and recast layer thickness for Inconel-690 will be useful to the industry.

A novel probabilistically timed dynamic model for physical security attack scenarios on critical infrastructures

This study proposes a novel probabilistically timed dynamic model for physical security attack scenarios on critical infrastructures (CIs). The model simulates attacker's attempts to compromise exploitable vulnerabilities in targeted CIs. Attacker's times to successfully compromise physical barriers, intrusion detection systems, and standby safety systems are modeled as random variables represented by user-defined probability distributions. The model assumes a highly skilled attacker, tracks his cumulative time to compromise targeted assets relative to an estimated mission time, and calculates mission success probability under imperfect information. The model uses Monte Carlo sampling technique to propagate uncertainties of input parameters to calculate statistics of mission success probability. Model's utility is demonstrated by a postulated case study in which an attacker attempts to launch undetected and unmitigated fire in 1-out-of-4 protected areas within a chemical process plant. Destroying one of these protected areas represents attacker's mission success in disrupting plant operation in addition to causing property damage. Visual flowcharting and dynamic attack tree logic are used to describe systematic execution of the attack. Simulation results show 64.4% mission success probability with 4.7% standard deviation. Benefits of proposed model include its use in security training to quantify probabilistic outcomes of “what if” scenarios, uncover exploitable vulnerabilities, and implement defensive strategies to improve CI's resilience under attack. The modeling framework can be extended to cyber security applications.

Synthesis of mass exchange networks for single and multiple periods of operations considering detailed cost functions and column performance

Mass exchange network synthesis (MENS) can be used to reduce pollutant emissions into the environment as well as reduce the need for mass separating agents (MSAs). Designing an efficient network using mathematical programming is not a trivial task, due to the fact that the design equations involved are highly non-linear. Chemical plant process parameters also change from time to time due to issues such as changes in environmental conditions, plant start-up/shut-downs, changes in process feed quality, change in product quality demand, and some other disturbance in the system. Such changes in process parameters result in what is known as multi-period operations; hence the synthesised network has to be flexible to handle these changes. In order to circumvent the issues associated with solving non-linear equations in mathematical programming environment, most methods have simplified the cost functions for MENS. Solutions obtained from these methods may not be realistic because the simplified cost functions are based on the assumption that the diameter of a column is 1m or 2m and that the capital cost of packed columns are dependent only on the height of the column. The simplified models do not make provision to check whether the resulting designs are prone to flooding, operate at optimal pressure drops or even whether the ratio of column diameter to size of packing materials would enhance efficient operations. Furthermore the models assumed single period operations for mass exchange network systems. This paper presents a new synthesis method for single and multi-period MENS using detailed cost functions and correlations which check whether selected columns are prone to flooding or not and whether they have optimal pressure drops that ensure efficient separations as well as optimal use of MSAs. The solutions obtained are compared with an existing method that used pinch technology.

The effects of perceived organizational support, perceived supervisor support and perceived co-worker support on safety and health compliance

Although knowledge is cumulating, very little is known about the effects of various sources of support on safety and health compliance. This study goes beyond previous research by investigating the relationships among perceived support from organizations, supervisors and co-workers, and employees’ safety and health compliance behaviour at chemical and petroleum process plants. The results of this study show that the support from organizations, supervisors and co-workers was significantly related to employees’ safety and health compliance. Also, the findings reveal that perceived supervisor support has the strongest influence in ensuring employees’ safety and health compliance behaviour.