Performance Of Unit Operations Research Articles

Membrane-based inverse-transition purification facilitates a rapid isolation of various spider-silk elastin-like polypeptide fusion proteins from extracts of transgenic tobacco

Plants can produce complex pharmaceutical and technical proteins. Spider silk proteins are one example of the latter and can be used, for example, as compounds for high-performance textiles or wound dressings. If genetically fused to elastin-like polypeptides (ELPs), the silk proteins can be reversibly precipitated from clarified plant extracts at moderate temperatures of ~ 30 °C together with salt concentrations > 1.5 M, which simplifies purification and thus reduces costs. However, the technologies developed around this mechanism rely on a repeated cycling between soluble and aggregated state to remove plant host cell impurities, which increase process time and buffer consumption. Additionally, ELPs are difficult to detect using conventional staining methods, which hinders the analysis of unit operation performance and process development. Here, we have first developed a surface plasmon resonance (SPR) spectroscopy-based assay to quantity ELP fusion proteins. Then we tested different filters to prepare clarified plant extract with > 50% recovery of spider silk ELP fusion proteins. Finally, we established a membrane-based purification method that does not require cycling between soluble and aggregated ELP state but operates similar to an ultrafiltration/diafiltration device. Using a data-driven design of experiments (DoE) approach to characterize the system of reversible ELP precipitation we found that membranes with pore sizes up to 1.2 µm and concentrations of 2–3 M sodium chloride facilitate step a recovery close to 100% and purities of > 90%. The system can thus be useful for the purification of ELP-tagged proteins produced in plants and other hosts.

Saponin-rich extract from Glycyrrhiza glabra plant, a safe matter for low interfacial tension oil/water extraction

Interfacial tension (IFT) plays an important role in the processes like extraction and emulsification, and that low level IFT is usually preferred for better hydrodynamic performance of unit operations. The present study explores the effect of a saponin-rich extract from Glycyrrhiza glabra plant on the IFT of conventional n-hexane/water system. FTIR, HPLC and LC/MS analysis indicates a 31.39% glycyrrhizic acid as the main saponin, as well as flavonoid and phenolic compounds. The system IFT was decreased to 79.5% under the apparent CMC of about 0.20 wt%. Comparison of the obtained results with the previously reported results with extract products from other plants and with respect to much lower used dosage (less than 1:50) indicates the high preference of the product. More IFT reduction could still be achieved with temperature (within 293.2–313.2 K) and pH (within 5.5–8.5). Further, NaCl and CaCl2 salts caused more IFT reduction due to salting-out effect and in the order of Hofmeister series; however, by strengthening the salting-in effect, IFT raised in the presence of Na2SO4. The obtained data at different temperatures were nicely reproduced with a correlation based on Szyszkowski adsorption isotherm, and the corresponding parameters were obtained with reasonable variations. Consequently, the adsorption thermodynamic parameters were determined.

Enhancing Gravity Thickener Feedwell Design and Operation for Optimal Flocculation through the Application of Computational Fluid Dynamics

ABSTRACT As the expectations for more consistent and higher density thickened and paste tailings in the minerals industry increase, so do the demands on flocculation performance within gravity thickeners. Low solids feed suspensions are delivered at a high velocity to center feedwells, which not only serve to dissipate the feed’s momentum and evenly distribute the solids, but are also the primary means by which polymer flocculant solutions are distributed across the fine particle to form fast settling (but fragile) aggregates. Computational fluid dynamics (CFD) is a powerful tool for optimizing the design and performance of unit operations used to achieve particle aggregation and sedimentation. Early CFD feedwell modeling gave predictions on the solids and fluid flows, which were useful for identifying discharge asymmetry and short-circuiting currents, but did not give major insights into aggregation states. Incorporating a population balance (PB) model of aggregate growth and breakage made it possible to capture the critical impacts of shear, residence time and solids concentration that characterize polymer-bridging flocculation, in particular the potential for prolonged higher shear conditions to give excessive breakage. This created a unique capability for understanding the complex balance between the hydrodynamic and physical chemistry requirements for flocculation, enabling systematic CFD studies of different design and operation elements. Some of the main conclusions on feedwell design optimization are outlined. Potential future applications of CFD outputs in feed-forward thickener control are also discussed.

Analysis of Performance of Short Tree Logging with Farm Tractor and Logging Trailer

Abstract The paper presents analysis of efficiency of the logging unit comprising Belarus 820 farm tractor and PD80 logging trailer equipped with Ryś-1 crane. Analysis was made based on the working day timing. The unit logged 1- meter long tree pieces (hornbeam, oak, birch) from the area where material for logging was distributed irregularly on the entire felling site. Unfavourable atmospheric conditions were reported during the working day (a thick layer of snow, low temperature, not frozen soil) which could have influenced the unit operation performance. Despite that the performance of the logging unit was comparable to similar logging units described in the literature. Determined coefficient of use of the operating time of the machine K02 was 0.93, coefficient of use of the shift working time K04 − 0.9, coefficient of use of the shift exploitation time K07 − 0.8. Hourly performance in the shift exploitation time was 4.98 m3·h−1, efficiency in the shift working time W02 − 4.80 m3·h−1 and performance in the general shift time W07 − 4.30 m3·h−1.

Techno-economic evaluation of microalgae harvesting and dewatering systems

Microalgal biomass is processed into products by two main process steps: 1) harvesting and dewatering; and 2) extraction, fractionation and conversion. The performance of unit operations for harvesting and dewatering is often expressed in qualitative terms, like “high energy consumption” and “low in operational cost”. Moreover, equipment is analysed as stand-alone unit operations, which do not interact in a chain of operations. This work concerns a quantitative techno-economic analysis of different large-scale harvesting and dewatering systems with focus on processing cost, energy consumption and resource recovery. Harvesting and dewatering are considered both as a single operation and as combinations of sequential operations. The economic evaluation shows that operational costs and energy consumption are in the range 0.5–2€·kg−1 algae and 0.2–5kWh·kg−1 of algae, respectively, for dilute solutions from open cultivation systems. Harvesting and dewatering of the dilute systems with flocculation results in the lowest energy requirement. However, due to required chemicals and loss of flocculants, these systems end at the same cost level as mechanical harvesting systems. For closed cultivation systems the operational costs decrease to 0.1–0.6€·kg−1 algae and the energy consumption to 0.1–0.7kWh·kg−1 algae. For all harvesting and dewatering systems, labour has a significant contribution to the total costs. The total costs can be reduced by a high level of automation, despite the higher associated investment costs. The analysis shows that a single step operation can be satisfactory if the operation reaches high biomass concentrations. Two-step operations, like pressure filtration followed by spiral plate technology or centrifugation, are attractive from an economic point of view, just as the operation chain of flocculation followed by membrane filtration and a finishing step with spiral plate technology or centrifugation.

Partition moment of inertia: Techno-economic partition curve analysis with applications to coal separations

In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. An alternative parameter, the organic efficiency, does indirectly consider process economics, but it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach, the partition moment of inertia, is introduced. This parameter reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure that promises better use of performance data.

Model Adaptation for Real-Time Optimization in Energy Systems

Real-time optimization (RTO) is widely used in industry to operate processes close to their maximum performance. The models used for RTO need to be adapted using real-time data to ensure feasibility of the model optimal inputs and convergence to the real plant optimal point. Heat and power systems are suitable for being optimized in real-time because of their fast dynamics and the benefits achievable by reacting to changes in power prices and steam demand. This work proposes a modifier adaptation strategy that exploits the structure of certain problems to make the adaptation faster and more reliable, which is proven to be particularly useful for heat and power systems. The adaptation is performed in the equations that predict efficiencies or performance of unit operations. By identifying the variables that modify each performance factor, the number of data sets needed for gradient correction is reduced. This makes the proposed strategy suitable for real-time optimization of processes with a large number o...

A Survey of Quality Attributes of Virus Spike Preparations Used in Clearance Studies

Demonstration of effective and consistent viral clearance by small scale models of downstream processing, typically cited as logarithmic reduction value (LRV), is an important safety requirement for biotech products. LRVs have anecdotally been reported to be inconsistent in these small-scale studies, even under controlled conditions when all process parameters are held constant. It was postulated that the quality of virus spike preparations used can in some cases adversely affect performance of these studies, which, from a regulatory standpoint, would be undesirable. This, along with topics discussed in PDA's Technical Report 47 (TR47), "Virus Preparations Used in Viral Clearance Studies," suggests that improving the quality and consistency of virus spike quality and utilizing testing procedures as described within should make these studies more reliable. However, an extensive survey to assess overall quality attributes to date has not been performed. To scout the landscape of spike preparation quality, we systematically characterized 18 commercially available virus preparations, focusing on key attributes identified in TR47: (1) infectious/total- and infectious/particle-associated copy numbers, (2) exogenous DNA/protein content and banding patterns, and (3) presence of aggregates. We found substantial variation across many of the preparations tested, often in more than one category. By modeling small-virus retentive filtration and low-pH inactivation unit operations, we show that virus preparation quality can potentially affect unit operation performance and viral clearance outcome. Our data supports the notion that during early-phase development, characterization of virus stock quality may provide an added level of control. Demonstration of effective and consistent viral clearance is an important safety requirement for biotech products. However, accumulating evidence suggests that the quality of virus preparations used in clearance studies often vary, and thus potentially affect their performance. To scout the landscape of virus preparation quality, we systematically characterized 18 commercially available virus preparations, focusing on key attributes identified in PDA's Technical Report 47 (TR47). Virus Preparations Used in Viral Clearance Studies. We found substantial variation across many of the preparations tested, often in more than one attribute category. By performing small-virus retentive filtration and low-pH inactivation unit operations on a small scale, we also show that virus preparation quality can affect unit operation performance and viral clearance outcome. Our data supports the notion that during early-phase development, characterization of virus stock quality may provide an added level of control.

Dealing with Algal Toxins and Dissolved Organics in Drinking Water

AbstractSeveral types of cyanotoxins found in surface water bodies are recognized as having human health effects, whereas taste and odor affect the palatability of water and give rise to public complaints. Conventional water treatment unit operations may be effective in removing the cyanobacteria cells, but cyanotoxins and dissolved organics are not targeted for removal by them. Special treatment units need to be introduced to deal with these substances and attention paid to the process design as many operational issues may be encountered. We used a water supply project in the Eastern Province of Sri Lanka as a case study to investigate the performance of unit operations in water treatment plants for which the source is shallow surface water sources with high inflows of nutrients. The present case study was designed to evaluate the efficacy of prechlorination, activated carbon adsorption, dissolved air flotation (DAF), filtration and disinfection in removal of cyanotoxins, and taste and odor causing disso...

Using bioprocess stoichiometry to build a plant-wide mass balance based steady-state WWTP model

Steady-state models are useful for design of wastewater treatment plants (WWTPs) because they allow reactor sizes and interconnecting flows to be simply determined from explicit equations in terms of unit operation performance criteria. Once the overall WWTP scheme is established and the main system defining parameters of the individual unit operations estimated, dynamic models can be applied to the connected unit operations to refine their design and evaluate their performance under dynamic flow and load conditions. To model anaerobic digestion (AD) within plant-wide WWTP models, not only COD and nitrogen (N) but also carbon (C) fluxes entering the AD need to be defined. Current plant-wide models, like benchmark simulation model No 2 (BSM2), impose a C flux at the AD influent. In this paper, the COD and N mass balance steady-state models of activated sludge (AS) organics degradation, nitrification and denitrification (ND) and anaerobic (AD) and aerobic (AerD) digestion of wastewater sludge are extended and linked with bioprocess transformation stoichiometry to form C, H, O, N, chemical oxygen demand (COD) and charge mass balance based models so that also C (and H and O) can be tracked through the whole WWTP. By assigning a stoichiometric composition ( x, y, z and a in C x H y O z N a ) to each of the five main influent wastewater organic fractions and ammonia, these, and the products generated from them via the biological processes, are tracked through the WWTP. The model is applied to two theoretical case study WWTPs treating the same raw wastewater (WW) to the same final sludge residual biodegradable COD. It is demonstrated that much useful information can be generated with the relatively simple steady-state models to aid WWTP layout design and track the different products exiting the WWTP via the solid, liquid and gas streams, such as aerobic versus anaerobic digestion of waste activated sludge, N loads in recycle streams, methane production for energy recovery and green house gas (CO 2, CH 4) generation. To reduce trial and error usage of WWTP simulation software, it is recommended that they are extended to include pre-processors based on mass balance steady-state models to assist with WWTP layout design, unit operation selection, reactor sizing, option evaluation and comparison and wastewater characterization before dynamic simulation.

A Data Mining Rule Extraction Method for Thermal Power Unit Operation Optimization

A rule extraction method for thermal power unit operation optimization which based on data mining technology is proposed in this paper. Data mining technology is employed to analyze history data stored in real-time/history database of the unit. Stability index, economic index, environmental index and synthetic index are constructed to evaluate the performance of current operating condition. Through comparison analysis on similar operating condition, the best operating parameters and operating mode can be found out at the current condition. Accompanying with data accumulation proceeding in database, nonlinear static model between the unit operation performance index and controllable parameters is drawn over all operating conditions. Effectiveness of this method is illustrated by a practical operation optimization project, in which the realization scheme of operation guidance is also given out.

Unit Operations Characterization Using Historical Manufacturing Performance

Collecting unit operation performance data on manufacturing processes has many benefits. Besides assessing the health of assets, the data can also be analyzed to drive process improvement activities, to assist in establishing practical operating ranges for new products, and can be used to facilitate process development activities in the laboratory ultimately leading to more robust tech transfers of processes to the manufacturing facility. In this paper, we will describe how to obtain operational variability on the basis of performance data extracted from current and/or historical manufacturing unit operations and its practical uses. Although, the concept was developed initially as a small molecule process design tool, its flexibility is underscored by including an example of how a parenteral manufacturing site used it to identify and correct an issue before it translated into unplanned downtime or product loss.

Granulometric Relationships for Urban Source Area Runoff as a Function of Hydrologic Event Classification and Sedimentation

This study investigated particulate matter (PM) granulometry delivered in source area runoff as a function of hydrologic transport and settling. At a Baton Rouge, LA paved urban watershed, event runoff volume and PM load were “fully captured” and recovered in settling tanks. Events were differentiated as mass-limited (ML) or flow-limited (FL) and PM differentiated into suspended (1 to ~25 μm), settleable (~25 to 75 μm), sediment (75 to 4,750 μm) fractions; and also particle size distributions (PSDs). Suspended sediment concentration (SSC)-turbidity relationships were unique for FL events compared to ML events; while 60 min of quiescent settling produced a single distinct relationship across all events. ML events transported higher proportions of settleable and sediment mass compared to higher suspended mass for FL events. Event-based ratios of settled and unsettled turbidity as well as SSC mass were statistically different for ML and FL events. For the same settling conditions, treatment of ML and FL events were statistically different. Results demonstrated that PM separation by a unit operation was a deterministic function of granulometry, hydrodynamics, unit operation mechanisms and loads, but significantly influenced by the indeterminate nature of local climate; and hydrology which drives PM delivery and is not known a priori. Combining the influences of scour and lack of maintenance, unit operation performance is non-stationary and cannot be described by a single value. Treatment should be tied to an effluent concentration; granulometry and load.

Toward rational design of powder processes

The past 25 years has seen particle technology grow from an under-funded and widely scattered research enterprise to a thriving globally recognized engineering discipline. Despite this change in the research environment, design and analysis of industrial particulate processes remain rooted in empiricism. Scale-up is largely heuristic, and quantitative design methods are non-existent. This is in stark contrast to fluid-phase systems, for which accurate scale-up and design methods have existed for decades. Why is this? One explanation lies in the traditional approaches to studying particle technology operations. Typically, these are studied at two length scales: the macroscale (unit operation level) and the microscale (particle level). Relatively little attention has been directed at an intermediate length scale, the mesoscale, which is characteristic of a “homogeneous” powder. This situation is analogous to ignoring classical thermodynamics and transport properties of fluids in the analysis of fluid-phase operations, instead trying to model unit operation performance directly using statistical mechanics or molecular dynamics. Advances in the design and analysis of particle technology operations requires filling of this “scale gap.” This can be accomplished by studying particulate systems in an analogous way to that used to study fluid-phase unit operations. This will require detailed investigation of mass, momentum, and energy transport in existing unit operations; development of experimental systems with well-defined and characterized flow fields; measurement of powder properties (transport properties and transformation kinetics) in these “simple” experimental systems; validation of theory and simulation against these data; and integration of these theories and simulations into system-level models.

From process simulation to general estimation

The ability to use a simulation program with the aim of making mass and energy balances in a plant, starting from just raw data and process knowledge, is an ambitious and attractive goal. We propose to address a general formulation for the estimation problem in the framework of a simultaneous modular approach. As raw data are corrected to satisfy mass and energy balances and some parameters are computed to give a unit operation performance diagnosis, the estimation consists both of data reconciliation and parameter identification. It follows that the numerical problem is a minimization of a least square objective function. Constrained minimization is performed with an infeasible path strategy which solves the optimization problem and process balance convergence at the same level, with a nonlinear programming code. The confidence intervals computation, for parameters and corrected values of measurements, is also discussed. A simple flash loop flowsheet example gives a better understanding of the theoretical aspects. A more complex flowsheet has been chosen as a second illustrative example.

A strategy for simultaneous data reconciliation and parameter estimation on process flowsheets

The ability to use a simulation program with the aim to make a general balance on a plant, starting just from raw data and process knowledge, is an ambitious and attractive goal. In this context, we will propose a general formulation for the estimation problem in the framework of the simultaneous modular simulator. As raw data are corrected to satisfy mass and energy balances and some parameters are computed to give a diagnostic on the performance of unit operations, the estimation consists both in data reconciliation and in parameter identification. It follows that the numerical problem is a minimization of a Least Square objective function. Constraint minimization is performed with an infeasible path strategy which solves the optimization problem and the process convergence at the same level, with a NonLinear Programming code. The confidence intervals computation, on parameters and on corrected values of measurements, is also discussed. A flash loop flowsheet has been chosen as an illustrative simple example which gives a better understanding of the theoretical aspects.

A study on defense management accounting system

The essence of Defense Resources Management is to maximize the combat capabilities through rational allocation and economization of the limited resources. Since the termination of U.S. military assistance early in the 1970's, we have put a lot of efforts to actualize our Self-Defense Will by setting up our own management system which is proper to our situation, but we have experienced numerous trial and errors and waste of resources because of the partial and superficial immitation of the advanced countries' systems. In order to solve the basic problems of our Defense Management, we have initiated an improvement project of Defense Management System, "Budget Reform Project," and adopted the PPBEES(Planning-Programming-Budgeting-Execution-EvaluatioSny system) which is based on "Defense Management Accounting System(DMAS)". We believe that the DMAS is one of the best management systems we have ever had in the world, since managerial accounting practices based on advanced theory and double entry book-keeping principle are reasonably mechanized enabling the internal check and balance. DMAS, integrated accounting system for the total management, can make it possible to decide the standard cost factor and to measure unit operation performance by analyzing the actual resource consumption data, and further to provide decision makers with cost information rationale in the process of programming and budget formulation. Moreover, with the application of computerized DMAS from local unit to the Ministry of National Defense Headquarters, we can facilitate office automation and unified repoting system, and also we can contribute to the modernization of military information system for approaching into the highly developed information society.