Top PDF Chemical Process Dynamics and Controls

Chemical Process Dynamics and Controls

Chemical Process Dynamics and Controls

In March of 2005, 15 people were killed at the of a refinery explosion in Texas City, TX. The refinery is the third largest in the country with the capability to process over 400,000 barrels of crude oil daily. On this particular day, the isomerization unit (whose purpose is to boost the octane rating of fuels) was being started up. As part of the normal start-up sequence, operators began feeding hydrocarbon liquid into the tower. However, a discharge valve that should have been opened was overlooked. A high level alarm was ignored and a second high-level alarm had not yet been re-enabled from the various maintenance activities that had been going on while the unit was down. Upon realizing that the tower was filling, a discharge valve was opened to release the hot fluid from the bottom of the vessel. This fluid then passed through a heat exchanger, warming the fluid that was still being pumped into the tower. The boiling that resulted in the bottom of the tower caused liquids to spill over the top of the stack and into a blow down drum with an atmospheric vent and no flare. The blow down drum could not contain the volume and began ejecting liquid and vapor hydrocarbon from the atmospheric vent. The vapors were soon ignited by a diesel truck with its ignition on. Fifteen people in a nearby trailer were killed in the resulting explosion. Inadequacies in the written start-up procedures, operator training, and the design of the safety relief system led to tragic and unnecessary loss of life. But examples such as these serve to make process environments even safer places to work in and around.
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JAZ2 controls stomata dynamics during bacterial invasion

JAZ2 controls stomata dynamics during bacterial invasion

In this work, we filled the signaling gap between the COI1 receptor and the NAC TFs by the identification of JAZ2 and its targets MYC2, MYC3 and MYC4. Thus, we showed that phytopathogenic Pseudomonas produces COR to hijack a COI1-JAZ2- MYC2/3/4-NAC19/55/72 signaling module controlling stomatal responses during the invasive process. Cell-specific expression of JAZ2 at guard cells suggested that JAZ2 could regulate stomatal dynamics during bacterial invasion. Loss- and gain-of-function analyses using jaz2-3 and jaz2Δjas mutants after infiltration or spray inoculation confirmed this hypothesis, and supported the idea that JAZ2 primarily functions at the guard cells. The gain-of-function jaz2Δjas allele blocked stomatal reopening and increased resistance to Pto DC3000, whereas the loss-of-function jaz2-3 was partially impaired in stomatal closure and more susceptible to the bacteria. This partial phenotype of jaz2-3 in stomatal closure could be due to redundancy among JAZ proteins. In fact, COR can still be perceived in the jaz2-3 mutant at the stomatal guard cells, suggesting that in these cells other JAZ proteins should be co-receptors with COI1, in addition to JAZ2. We only succeed analyzing the expression patterns of 7 JAZs, and therefore, a role for the remaining JAZs (JAZ4, JAZ7, JAZ8, JAZ10, JAZ11 and JAZ13) at the stomata could be expected.
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Flavour chemical dynamics during fermentation of kombucha tea

Flavour chemical dynamics during fermentation of kombucha tea

of few esters. Of course, metabolism mechanism of flavour components participated by microorganisms in kombucha fermentation broth shall be further studied in the future. The physical and chemical conditions, such as pH value, and total acidity in kombucha fermentation broth, were direct evidence of the growth of different microorganisms present and the accumulation of flavour metabolic products. In this study, it was interesting that the growth of bacteria and yeasts was not absolutely consistent with the decrease rate of pH value and the increase rate of total acidity. Probably, there was a more direct interrelation between pH value, total acidity and acids like monoacids, binary acids. Kombucha microorganism is a complex microbial ecosystem and its composition changes with original place and fermentation process. During fermentation the co-relations between microorganisms are especially complex and uncertain; hence, more investigations about chemical constituents in fermenting kombucha tea broth are necessary to reveal the formation mechanism kombucha tea quality.
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THE IMPACT OF ACCOUNTING INTERNAL CONTROLS TO REDUCE PRODUCTION COSTS IN THE JORDANIAN CHEMICAL COMPANIES

THE IMPACT OF ACCOUNTING INTERNAL CONTROLS TO REDUCE PRODUCTION COSTS IN THE JORDANIAN CHEMICAL COMPANIES

Study (Abu Hammour 0.2016) entitled "The effect of the accounting systems of internal control in the reduction of production costs in the light of the accounting information systems" aimed to identify the level of the existence of accounting internal control systems in the Jordanian chemical companies and aimed as well to make sure whether there is a statistically significant effect of the accounting systems of internal control in the Jordanian chemical companies to reduce the actual cost of production in these companies. The researcher used the descriptive and analytical approach in order to achieve the objectives of the study which relied on secondary and primary sources in the data collection and analysis to achieve objectives of the study may be a study population of chemical companies listed on the Amman Stock Exchange and number of 69 companies were selected 56 companies, including by (81 %) of the study population was distributed by the resolution (5) questionnaires for each company, and thus be a study sample consisting of 280 individuals. Statistical tools involved t-Test for a sample of individual as well One test Way Anova The study results showed that there is a high level of field adjusting production costs in light of the accounting information systems, where high importance came, according to the views of the sample, while the most important recommendations of the study that the departments of the Jordanian chemical companies activating more interesting and more effectively accounting information systems so that the effect on reducing production costs to the extent possible the process.
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Control of a Chemical Reactor with Chaotic Dynamics

Control of a Chemical Reactor with Chaotic Dynamics

dynamics [9]. Peng et al. observed chaotic behavior in a closed three-variable autocatalator [10]. Lynch showed that dynamics of a parallel cubic autocatalator can lead to chaos as the input concentration ratio to the reactor increases [11]. It was also shown that chaos occurs in a mixed cubic and quadratic autocatalytic reaction [12]. Lynch proved that existence of chaotic behavior does not depend on presence of a reaction step involving cubic autocatalysis, and showed that chaotic behavior is preserved when the cubic step is replaced by successive bimolecular steps involving an intermediate [13]. An extended review regarding chaos and its applications in the process system engineering has been made by Lee & Chang [14]. Chaotic behavior is irregular, complex and generally undesirable. Therefore, within the research area of nonlinear dynamics, control of chaos has received increasing attention. Chaos control has been of broad interest since early 1990s. In 1990, Ott et al. showed that a chaotic attractor can be converted to one of a large number of possible attracting periodic motions by making only small time dependent perturbations in system parameters [15]. This method is applied to a prototype model for isothermal chemical chaos to stabilize unstable limit cycles out of chaotic behavior [16]. Bandyopadhyay et al. have successfully applied this approach to stabilize the dynamics of a chaotic non-isothermal CSTR [17].
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Biochemical and structural controls on the decomposition dynamics of boreal upland forest moss tissues

Biochemical and structural controls on the decomposition dynamics of boreal upland forest moss tissues

Predicting the temperature sensitivity of moss decomposi- tion is difficult, because it is not clear if the apparent recalci- trance of moss tissues is due to chemical complexity, physi- cal and structural characteristics impeding microbial decom- position, or a combination of the two. Most studies of moss biochemistry have focused on the peat-forming Sphagnum genus, and it is not clear to what extent these insights ap- ply to non-Sphagnum upland species. While mosses do not contain lignin (Maksimova et al., 2013), they do produce a variety of lignin-like phenols, which have been hypothesized to inhibit decomposition (Tsuneda et al., 2001). In addition, Sphagnum mosses produce structural carbohydrates that also appear to impede decomposition (Hájek et al., 2011; Turet- sky et al., 2008). If the decomposition of upland mosses is limited by chemical properties, we might expect a higher temperature sensitivity of moss decomposition compared to vascular plant litter due to the higher activation energy of more chemically complex compounds (Bosatta and Ågren, 1999; Davidson and Janssens, 2006). This result would sug- gest that the moss C pool is not only under-represented in size due to slow decomposition, but it is also particularly vulner- able to decomposition with warming.
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Benthic macroinvertebrate diversity in a shallow estuary: controls on nutrient and algal dynamics

Benthic macroinvertebrate diversity in a shallow estuary: controls on nutrient and algal dynamics

Distributions of benthic invertebrates are dictated by a complex suite of biotic and abiotic factors interacting on multiple scales, yet predictable shifts in community structure occur in response to gradients of environmental disturbance and instability (Pearson & Rosenberg 1978, and references therein). Because invertebrates are important indicators of aquatic ecosystem health, field surveys and analyses of composition have broad applications for habitat monitoring in freshwater (e.g., Novak & Bode 1992, Kerans & Karr 1994) and coastal marine systems (e.g., Gray & Pearson 1982, Warwick 1986, Clarke & Warwick 1993, Ranasinghe et al. 1994, Ugland 2008). In estuaries, a common driver of both chronic and acute stress to resident biota is the acceleration of nutrient loads that fuel the process of eutrophication (Nixon 1995). As a consequence of persistent algal blooms, excessive accumulation of organic matter, and associated biogeochemical changes, benthic structure in eutrophic and/or hypoxic systems may ultimately shift from diverse to depauperate faunal communities during the transition from normal to polluted conditions (Pearson & Rosenberg 1978, Diaz & Rosenberg 1995, Valiela et al. 1997, Cardoso et al. 2004).
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Self-oscillatory dynamics of the metabolic process in a cell

Self-oscillatory dynamics of the metabolic process in a cell

System (1) – (10) is a completely determined nonlinear system of differential equations in the ten-dimensional phase space. It describes the bio- chemical system with positive feedback, which generates the autocatalysis of NaD⋅ H (see Eqs. (3) and (9)). Therefore, the self-oscillatory modes can appear in it. With the help of numerical computa- tions, we have studied all possible modes arising in the given system at a variation of the dissipation of the kinetic membrane potential α (10). This poten- tial is the most general parameter determining the stability of the metabolic process in a cell.
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Development Of Process Flow And Standard Operating Procedures For Madeena Syrup Process Controls

Development Of Process Flow And Standard Operating Procedures For Madeena Syrup Process Controls

The study at rest or in motion is called fluid mechanics. This area of physics is divided into fluid statics, the study of the behavior of stationary fluids, and fluid dynamics, the study of the behavior of moving, or flowing, fluids. Fluid dynamics is further divided into hydrodynamics, or the study of water flow, and aerodynamics, the study of airflow.

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Study to Define Frequency in Routine Analytical Controls in the Radiolabelling Process

Study to Define Frequency in Routine Analytical Controls in the Radiolabelling Process

The goal of this study is to assess any eventual criticality related with radio- chemical purity tests, determine the possibility of a parametric release and the optimal frequency of tests on radiopharmaceuticals from kits, while ensuring the same safety standards established by the regulations for such matters and, at the same time, reducing operator exposure to ionizing radiation.

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Low flow controls on stream thermal dynamics

Low flow controls on stream thermal dynamics

Water depth together with discharge and velocity directly influences and regulates the distribution and growth of aquatic flora (Riis and Biggs, 2003; Franklin et al., 2008; Bornette and Puijalon, 2011). Macrophyte communities play a key role in unshaded streams (Riis and Biggs, 2003), by increasing physical and biological diversity, and by contributing to habitat structure and ecological functioning of these systems (Warfe and Barmuta, 2006; Thomaz and Cunha, 2010). While stable flows favour macrophyte biomass (Mebane et al., 2014), the increased number and frequency of hydrological disturbance events, such as floods and droughts, can significantly alter the composition and abundance of aquatic macrophyte communities (Riis and Biggs, 2001; Riis and Biggs, 2003; Stromberg et al., 2005), causing biomass destruction, and habitat structure change (Grime, 1979). Under this constraint, plant species with a greater resistance and/or resilience usually dominate (Riis et al., 2008), whereas others, such as Ranunculus species, only occupy channel areas with permanent flow (Westwood et al., 2006). As a result, during droughts, the channels of ephemeral or perennial streams experiencing severe drying can be invaded and colonized by resistant and/or amphibian or riparian plant species (Bunn and Arthington, 2002; Lake, 2003), a process called terrestrialization (Westwood et al., 2006; Holmes, 1999). Strictly aquatic macrophytes (Schuyler, 1984) and non-aquatic forms possess different shading abilities that are quite influential for both water and streambed temperatures. Non-aquatic forms in particular, being characterized by more competitive growth forms (e.g. tall or broad-leafed species; Bornette and Puijalon, 2011), have highly variable shading effects on surface water and streambed sediments. Therefore, water level fluctuations due to drought conditions can influence aquatic vegetation coverage and indirectly, stream temperature regimes. However, to our knowledge, no previous high spatio-temporal resolution studies of the combined impact of both water level and vegetation coverage on temperatures at the channel bed and in the water column have been carried out.
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Dynamics of a Predator Prey System Concerning Biological and Chemical Controls

Dynamics of a Predator Prey System Concerning Biological and Chemical Controls

We investigate an impulsive predator-prey system with Monod-Haldane type functional response and control strategies, especially, biological and chemical controls. Conditions for the stability of the prey-free positive periodic solution and for the permanence of the system are established via the Floquet theory and comparison theorem. Numerical examples are also illustrated to substantiate mathematical results and to show that the system could give birth to various kinds of dynamical behaviors including periodic doubling, and chaotic attractor. Finally, in discussion section, we consider the dynamic behaviors of the system when the growth rate of the prey varies according to seasonal e ff ects.
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Cooperative learning in process dynamics & control course for undergraduate chemical engineering students

Cooperative learning in process dynamics & control course for undergraduate chemical engineering students

The move to promote the implementation of CL and PBL is still at the initial stage. The CL-PBL taskforce is currently at the half-way point of the short term plan. Thus far, the core groups in several faculties, such as the Chemical and Natural Resources Engineering Faculty, the Mechanical Engineering Faculty, the Electrical Engineering Faculty, the Diploma Learning Centre and several other non-engineering faculties have applied CL and PBL in several classes. While there are room for improvements in the implementations, there have been many benefits and positive changes in students observed
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Physical controls on spring bloom dynamics in the Irminger Basin, North Atlantic

Physical controls on spring bloom dynamics in the Irminger Basin, North Atlantic

The interior of the IB is relatively quiescent, although some small eddies (20 to 40 km diameter) develop at the front between the EGC and the Irminger Current (Eden and Böning, 2002), and a few large eddies (diameters up to 70 km) are occasionally observed in the interior of the basin (Krauss, 1995). High values of surface eddy kinetic energy are observed along the Greenland continental shelf (Frantantoni, 2001). In the neighbouring Labrador Sea the associated eddy fluxes are thought to enhance the restratification process after intense winter cooling has overturned the water masses to create Labrador Sea Water (LSW, e.g. Dickson et al., 1996). LSW is found in the IB typically below 1000 m and until recently the Labrador Sea was regarded as the only site of formation of LSW. It is formed by deep convection, the process which exposes cold, saline water, normally held below the permanent thermocline to the sea surface and which drives the abyssal limb of the North Atlantic meridional overturning circulation. Deep convection has previously thought to only occur in the Greenland, Labrador, Mediterranean and Weddell Seas (e.g. Marshall and Schott, 1999). However, modelling studies (Pickart et al., 2003a; Straneo et al., 2003) suggest that the transit time for LSW from the Labrador Sea into the IB is up to two years - much longer than the six months which would be required to match the distribution of LSW, assuming that no LSW was formed in the IB (Sy et al., 1997). Thus the idea, formulated by Nansen (1912) and long since discarded, that LSW can be formed by deep convection in the IB, needed to be revisited.
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A conceptual investigation of process controls upon flood frequency: role of thresholds

A conceptual investigation of process controls upon flood frequency: role of thresholds

An alternative, derived flood frequency approach attempts to apply our understanding of rainfall generation behaviour, and of the transformation process from rainfall into flood response, in order to understand the dynamics of flood fre- quency and its process controls (e.g. Eagleson, 1972). Un- like statistical methods, an understanding of process con- trols upon flood frequency permits the forecasting of flood frequency subject to non-stationarity and heterogeneity, as well as a rationalisation of non-stationarity and heterogene- ity in historic flood frequency behaviour – at least qualita- tively, if not quantitatively. The objective of this study is to present an analysis of the process controls on flood frequency for a simplified representation of catchment hydrological re- sponse, and then to illustrate the impact of heterogeneity in the hydrological response – specifically, that associated with threshold non-linearities in the catchment storage-discharge relationship – in altering flood frequency behaviour. The im- pacts of specific elements of spatial and temporal variability upon flood frequency are then considered. While Kusumas- tuti et al. (2006) considers the sensitivity of flood frequency to threshold impacts for a specific climate using similar cli- mate and catchment parameterisations, this study aims to describe climate and catchment process controls upon flood frequency more generally, and to identify important param- eter groupings that can be used to generally characterise the flood frequency response, including heterogeneity therein, of a given climate-catchment combination.
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Functional Dynamics in Complex Chemical and Biological Systems (FUNCDYN)

Functional Dynamics in Complex Chemical and Biological Systems (FUNCDYN)

Living organisms are characterised by a plethora of chemical, structural and physical details at several levels of complexity. As a consequence, the compre- hensive understanding and modelling of processes and mechanisms on every spatial and temporal scale is a diffi cult task. One of the aims of the F UNCDYN pro- gramme is the development and the dissemination of systematic methods of reduction of model complexity. Without losing the quantitative predictability of models, this can be done by restricting the modelling of the rel- evant temporal and spatial scales to the phenomena under analysis. During the last 30 years, in the fi elds of physics and chemistry, analogous spatio-temporal problems have been successfully approached by the implementation of theoretical and experimental meth- ods derived from the theories of non-linear dynamics and dynamical systems.
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Chemical Process & Design Handbook (Speight) pdf

Chemical Process & Design Handbook (Speight) pdf

separate the product black from water vapor and the combustion off-gases. Fiberglass bag filters allow near quantitative yield of the carbon black. Following pulverization and grit removal steps, the loose, fluffy black is normally pelletized for convenient bulk handling and to reduce the ten- dency to form dust. In the commonly used wet pelletizing process, the black is agitated and mixed with water in a trough containing a rotating shaft with radially projecting pins, which form the pellets. The wet pellets, usually in the 25- to 60-mesh range, are dried in a gas-fired rotating-drum dryer. In the dry pelletizing process, pellets are formed by gentle agitation and rolling of the black in horizontal rotating drums (about 3 m in diame- ter and 6 to 12 m long) for periods of 12 to 36 hours. An oil pelletizing process is also used, to a minor extent, for specialty applications (e.g., cer- tain ink-grade blacks).
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Migrating a Desktop Simulator of a  Chemical Process to the Cloud

Migrating a Desktop Simulator of a Chemical Process to the Cloud

For determining the necessary classes of the cloud simulation, a UML technique designated as Class Respon- sibility Collaborator analysis (CRC analysis) using cards was applied [32]. CRC (Class-Responsibility-Colla- borator) Card Modelling is a simple powerful object-oriented analysis technique, which often includes the users, analysts, and developers in a modelling and design process, and as such brings together the entire development team to form a common understanding of an object-oriented development project. A CRC model is a collection of cards (usually standard index cards or larger) that are divided into three sections: Class, Responsibility and Collaborator. A class represents a collection of similar objects that are things of interest in the system being modelled, and can be a person, place, thing, or any other concept important to the system at hand. The class name appears across the top of the CRC card. A responsibility is anything that the class knows or does. These responsibilities are things that the class has knowledge about itself, or things the class can do with the know- ledge it has. A collaborator is another class that is used to get information from, or perform actions for the class at hand. It often works with a particular class to complete a step (or steps) in a scenario. The collaborators of a class appear along the right side of the CRC card.
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The Quantum Dynamics of Atom Plus Diatom Chemical Reactions

The Quantum Dynamics of Atom Plus Diatom Chemical Reactions

~he uniform semi-·classical method,; We also present and compare the corresponding rate constants obtained from the 1~esults of these four m.ethods., In addition, we exami[r]

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Development Power: The Potential Dynamics in Economic Process

Development Power: The Potential Dynamics in Economic Process

Abstract: Stating from the intrinsic characteristics of macroeconomic development, this paper puts forward the concept of development power and its theoretical frame. The development power is the potential and invisible dynamics to promote economic growth. By means of the development power theory, we can explain some important problems in macro-economy. We discuss the basic properties of development power and obtain some results, such as, the effects of economic policy depends on the development power, the imbalance of economic development is caused by the different levels in development power. The method is given to evaluate development power, and then we may analyze the mutual effects among development powers. Finally, we illustrate that the development power movements exist widely in the economic development.
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