Purification Unit Research Articles

Model-based optimization of integrated purification sequences for biopharmaceuticals

Finding the best purification process is a challenging task. Recently, mechanistic models that can accelerate the development of chromatographic unit operations, the most important purification units, became widely available. In previous work, several chromatographic models have been linked together to simulate and optimize integrated processes. However, considering only chromatographic steps may lead to a suboptimal process. Consequently, the aim of this study was to include models for ultra- and diafiltration units into the optimization approach to account for buffer exchange steps before or between chromatography units. This approach was applied to an industrial case, the purification of a monoclonal antibody, where cation exchange, hydrophobic interaction and mixed mode were the possible chromatographic separation modes. It turned out that only the duration of the total filtration step and the duration of the ultrafiltration step were crucial variables for the optimization of the ultra- and diafiltration steps. The ‘best’ in silico purification process was found based on the performance criteria yield and solvent usage. The purity was required to be at least 99.9%.

Techno-economic assessment of polygeneration based on fluidized bed gasification

The electric power sector contributes to about a quarter of the total CO2 emissions worldwide. Therefore, in most mitigation scenarios for the climate change the share of low-carbon electricity supply increases from the current share of approximately 30% to more than 80% by 2050. A promising approach is the polygeneration concept for electrical power and chemicals based on integrated gasification combined cycle. It offers the possibility to capture CO2 in a very efficient pre-combustion process and is able to accommodate the intermittent renewable power generation from wind and solar while operating the gasification island at full load by producing synthetic chemical products during times of low power demand. In this work, a process model of a polygeneration plant including a 350 MWel combined cycle power plant with a fluidized bed dryer, a fluidized bed gasifier, a gas purification unit, a CO-Shift unit, a Rectisol acid gas removal, and a synthesis reactor array is developed. The model is used to investigate the specific CO2 emissions and the process efficiency for different operation modes for power and methanol production. The model offers two options to introduce excess electricity from renewable sources into the process: via hydrogen from electrolysis or via additional drying and heating of the feedstock. The influence on the process efficiency and the economics are assessed.

The selection of catalysts that provide stability and high oxidation rate of hydrogen and methane in the reactors R 2 compartments of helium Orenburg helium plant

This article presents an overview of promising catalysts, the selection of the most effective, calculated the economic effect of the introduction of a new catalyst. The selection of catalysts providing stability of operation and high rate of oxidation of hydrogen and methane flowing in the reactor P 2 of the helium fine purification unit of helium production from helium concentrate was made. To ensure the technological process in the production of chemical, gas processing and oil refining enterprises, catalysts of different modifications and types of both domestic and imported production are used. For stable operation and high oxidation rate of hydrogen and methane flowing in the reactor P-2 of the helium fine purification unit-22 of the Orenburg helium plant, the AP-56 aluminum-platinum catalyst is used. The catalyst AP-56 participating in oxidation processes in connection with the improvement of the technological process does not meet the standards established in the technological regulations, including an increase in hydrogen concentrations, and this in turn worsens the quality of gasoline fractions, in addition, the catalyst AP-56 is promoted by chlorine, which contributes to the development of corrosion on heat exchange equipment located after the reactor. The above circumstances forced manufacturers to reduce the production of aluminum-platinum catalyst AP-56. The most productive among the units of fine cleaning plant, which includes 3 similar compartments with a capacity of up to 400 Nm3/h for raw materials, is considered. To confirm of the selected catalysts on existing equipment and for implementation, the technological calculations of the catalytic purification unit were made, and the main indicators of the process were determined.

Thermodynamic assessment and optimization of a pressurized fluidized bed oxy-fuel combustion power plant with CO2 capture

In this paper, a 600 MW pressurized fluidized bed oxy-fuel combustion power plant integrated with an air separation unit (ASU) and a CO2 compression and purification unit (CPU) was presented. Pressurization increases the flue gas dew point, and more phase-change heat of moisture is thereby available in the flue gas. In the baseline case of 10 bar, the net power efficiency of the plant was 33.40%. The effect of pressure on the plant performance was important whereas the effect of fluidized bed temperature was marginal. The plant with wet mode flue gas recirculation offered higher net power efficiency than the dry mode. Heat integration of ASU, CPU and acid condenser with the steam cycle was conducted to maximize the power production. The use of heat from the acid condenser increased the net power efficiency by 0.81% point over the baseline case. The heat recovery from ASU boosted the net power efficiency by 2.22% points, while the heat recovery from CPU resulted in the net power efficiency improvement of 0.34% point. In the optimization combining ASU, CPU and acid condenser, the net power efficiency increased to 36.83% (LHV), which was competitive over other oxy-fuel combustion counterparts.

Staged oxy-fuel natural gas combined cycle

Exhaust gas recirculation (EGR) in conventional natural gas-fired oxy-combustion cycles is required to maintain the combustion temperature at an allowable level. However, EGR is not beneficial from the system performance perspective. It is difficult to achieve in oxy-fuel cycles due to the high pressure and increased pressure drop in such systems. Consequently, alternative options to control the combustion temperature need to be considered. In this study, staged oxy-fuel natural gas combined cycle (SOF-NGCC) was proposed, which does not require EGR, and its feasibility was evaluated. A process model was developed in Aspen Plus® in order to evaluate the thermodynamic performance of the proposed system and to benchmark it against the Allam cycle and conventional NGCC. The optimum net efficiency of the proposed cycle (47.63–51.32%) was shown to be lower than that for the Allam cycle (54.58%) and the conventional NGCC without post-combustion capture (PCC) (56.95%). However, the SOF-NGCC is less complex and requires smaller equipment than the Allam cycle. This is mostly because the combined volumetric flow rate into expanders in both topping and bottoming cycles is approximately 25% of that estimated for the Allam cycle. Moreover, with a backpressure of 35 bar, no further compression is required prior to the CO2 purification unit.

Novel lymph node segmentation and proliferation index measurement for skin melanoma biopsy images

The lymphatic system is the immune system of the human body, and includes networks of vessels spread over the body, lymph nodes, and lymph fluid. The lymph nodes are considered as purification units that collect the lymph fluid from the lymph vessels. Since the lymph nodes collect the cancer cells that escape from a malignant tumor and try to spread to the rest of the body, the lymph node analysis is important for staging many types skin and breast cancers. In this paper, we propose a Computer Aided Diagnosis (CAD) method that segments the lymph nodes and melanoma regions in a biopsy image and measure the proliferation index. The proposed method contains two stages. First, an automated technique is used to segment the lymph nodes in a biopsy image based on histogram and high frequency features. In the second stage, the proliferation index for the melanoma regions is calculated by comparing the number of active and passive nuclei. Experimental results on 76 different lymph node images show that the proposed segmentation technique can robustly segment the lymph nodes with more than 90% accuracy. The proposed proliferation index calculation has low complexity and has an average error rate of less than 1.5%.

Solubility Measurement of Lauric, Palmitic, and Stearic Acids in Ethanol, n-Propanol, and 2-Propanol Using Differential Scanning Calorimetry

The solubility of saturated fatty acids is essential for the design and operation of separation and purification units, since crystallization is the main method used in these cases. In this work, differential scanning calorimetry (DSC) was used to determine the solubility of lauric, palmitic, and stearic acid in alcoholic solvents (ethanol, n-propanol and 2-propanol). Comparison with literature data confirmed the efficacy and precision of the DSC technique. For the three saturated fatty acids evaluated, the solubility was highest in 2-propanol and lowest in ethanol. Activity coefficient models (Margules, Wilson, and nonrandom two-liquids models) were correlated with the experimental data, showing good agreement.

Self-Optimizing Control Structure and Dynamic Behavior for CO2 Compression and Purification Unit in Oxy-fuel Combustion Application

A CO2 compression and purification unit (CPU) using the phase separation method is a promising option to obtain high-purity CO2 products from oxy-fuel combustion power plants. For such CPU systems,...

Energy efficiency analysis of pressurized oxy-coal combustion system utilizing circulating fluidized bed

Oxy-fuel combustion with circulating fluidized bed (CFB) is one of the most important technology for carbon dioxide capture and sequestration. However, its development and application are seriously hindered by the low net efficiency mainly resulting from the use of air separation unit (ASU) and carbon dioxide compression and purification unit (CPU). In this work, a pressurized oxy-coal CFB combustion cycle was established mainly including ASU, CFB combustion unit, heat exchangers, power island and CPU. Based on the material and energy conservation, the detailed energy penalties of ASU, CPU, and recirculating compressor were investigated under the varying combustion pressures from 0.105 MPa to 3 MPa. Results revealed that with the increase of combustion pressure, the energy consumption of ASU increases while that of CPU decreases. Compared with PC boiler, the influence of the recirculating compression work on CFB system is negligible in lower pressures. Overall, Higher combustion pressure is favorable to the oxy-coal CFB combustion. By minimizing the penalties and recover more latent heat, the net efficiency rises up from 27.2% to 30.5% in this work while the optimum pressure being about 1.1 MPa. Meanwhile the mole fraction of carbon dioxide can reach 92% which is satisfied with the demands.

Techno-economic analysis of calcium looping processes for low CO2 emission cement plants

The scope of this work is to perform a techno-economic analysis of two Calcium Looping processes (CaL) for CO2 capture in cement plants. Both tail-end CaL system with fluidized bed reactors and integrated CaL system with entrained flow reactors have been considered in the analysis. The calculation of the heat and mass balances and the economic analysis are consistent with the methodology defined in the framework of the H2020 Cemcap project.The analysis shows that the assessed CaL systems (especially the tail-end configuration) involve a significant increase of fuel consumption compared to a reference cement kiln without carbon capture. However, a large part of this additional energy input is exploited in a heat recovery steam cycle, which generates the electric power required to satisfy the consumption of the CO2 capture auxiliaries (i.e. the power absorbed by the air separation and CO2 compression and purification units). The integrated CaL process features a lower rise of equivalent fuel consumption (+59% compared to the reference) and a larger reduction of direct CO2 emission (-93% compared to the reference). The specific primary energy consumption for CO2 avoided (SPECCA), which takes into account also the indirect fuel consumption/savings and indirect emissions/avoided emissions due to electricity exchange (import/export) with the grid, ranges between 3.17–3.27 MJLHV/kgCO2 for the integrated system vs. 3.76–4.42 MJLHV/kgCO2 for tail-end cases, depending on the scenario considered for the grid electricity mix.The economic analysis highlights that CaL processes are capital intensive, which involve, roughly, a doubling of the Capex of the whole cement plant with CCS compared to a greenfield conventional cement plant. However, the obtained cost of CO2 avoided is competitive with alternative technologies and ranges between about 52 €/tCO2 of the tail-end configuration and 58.6 €/tCO2 of the integrated one.

A Cogeneration System Based on Solid Oxide and Proton Exchange Membrane Fuel Cells With Hybrid Storage for Off-Grid Applications

Solid oxide fuel cells (SOFC) have developed to a mature technology, able to achieve electrical efficiencies beyond 60%. This makes them particularly suitable for off-grid applications, where SOFCs can supply both electricity and heat at high efficiency. Concerns related to lifetime, particularly when operated dynamically, and the high investment cost are however still the main obstacles towards a widespread adoption of this technology. In this paper, we propose a hybrid cogeneration system that attempts to overcome these limitations, in which the SOFC mainly provides the baseload of the system. The introduction of a purification unit allows the production and storage of pure hydrogen from the SOFC anode off-gas. The hydrogen can be stored, and used in a proton exchange membrane fuel cell (PEMFC) during peak demands. The SOFC system is completed with a battery, used during periods of high electricity production. In this paper, we propose the use of a mixed integer-linear optimization framework for the sizing of the different components of the system, and particularly for identifying the optimal trade-off between round-trip efficiency and investment cost of the battery-based and hydrogen-based storage systems. The proposed system is applied and optimized to two case studies: an off-grid dwelling, and a cruise ship. The results show that, if the SOFC is used as the main energy conversion technology of the system, the use of hydrogen storage in combination with a PEMFC and a battery is more economically convenient compared to the use of the SOFC in stand-alone mode, or of pure battery storage. The results show that the proposed hybrid storage solution makes it possible to reduce the investment cost of the system, while maintaining the use of the SOFC as the main energy source of the system.

Synthesis and Characterization of Belite-rich Cement by Exploiting Alumina Sludge

Alumina sludge from drinking water treatment plants raises serious environmental concerns. In order to address these concerns, the present study aims at exploiting the alumina sludge generated by water purification unit as a raw material substitute in the production of belite clinkers. The chemical composition, morphology and nature of mineralogical phases in the alumina sludge-based clinkers/ cements are assessed respectively by Fluorescence-X (F-X), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analyses. Afterwards, the mechanical testing on the synthesized clinker/belite cements is carried out by employing compressive/ flexural strength analysis. The obtained results show that the best clinker is obtained at 1300°C with a lime saturation factor of raw meal in the order of 85.37% without any chemical stabilizers. In addition, we find a compressive strength value of the mentioned clinker in the order of 18.2 MPa during 28 days curing. With these results, the synthesized alumina sludge-based belite-rich cement shows significant potential to be commercialized.

Multilayered surface for the interactive separation of perchlorate from aqueous medium

Environmental contextPerchlorate from rocket fuel plants or firework manufacturing units can seriously contaminate drinking water. We developed a separation skin on a microfiltration membrane and on sand that can remove perchlorate from water in the presence of competing ions. This method is suitable for a domestic water purification unit selective for perchlorate removal. AbstractThis study reports an interactive separation of perchlorate (ClO4−) by polyethyleneimine (PEI) and poly (styrene sulfonate) (PSS) deposited on a microfiltration membrane and on sand surfaces. The variation of the interaction with respect to deposition and feed variables was assessed. The 9 bilayered ((PEI/PSS) 0.15M NaCl, pH 6)) membranes showed a ClO4− rejection of ~80%. An increase in the feed concentration to 25mgL−1 reduced the rejection to 58%. With a feed pH from 4 to 10, the rejection varied between almost 100% and 16%. The presence of ions reduced the rejection percentage of ClO4− with the interference by the ions in the order of SO42−>HCO3−>NO3−>Cl−. The interference is attributed to the characteristics of the competing ions and the nature of the multilayers. A positive impact of post-treatment (98%) and capping layers on rejection percentage (80% to nearly complete) for synthetic and ClO4− contaminated field water samples is clearly established. The presence of competing ions is also accounted for by a capped membrane system. The selectivity of the competing ions increases with capping layers of 1M NaCl in the order of HCO3−>NO3−>SO42−. In the field water samples up to a SO42− concentration of 3.0mgL−1, the capping layers with 0.4M NaCl result in a near complete rejection of ClO4−, whereas further enhancement requires a capping layer of 1M NaCl. A sand filtration system was developed by incorporating the pre-optimised polyelectrolyte multilayer on sand. Deposition of a single bilayered PEI/PSS multilayer on sand effectively (nearly completely) removes ClO4−.

Parameters of air flow over the upper sieve in the cleaning chamber

The value and direction of the resultant vector of the airflow coming out of the upper sieve, depending on changes in the gap between the blinds in purification of the combine harvester, is assessed. The volume and direction of the resultant vector of the airflow, as well as its components were evaluated in the study. Dynamic pressure was measured over a sieve with Pitot tubes in 6 points along the length, in each section at a distance of 50 mm from the blinds mounting axes. During the purification with a serial sieve by Svr = 7…13 mm speed is almost constant, but when Svr > 13 mm, it intensively reduces from 4 to 2.50 m/s. This mentioned pattern of speed changes of serial sieves affects undoubtedly negatively on the separation of grain. In fact, by increasing of the supply of straw heap, Svr gap between the louvers is increased to reduce static resistance of network. However the increase of Svr reduces the air flow speed and its loosening impact on heap. Thus, one reason for intensive grain losses increase in empty glume by higher feed rates of heap of straw is a decrease in the function v (Svr). Under the influence of the vertical component of velocity and vibrations of sieves the heap layer comes into a quasi-fluid state and the fictional force between particles decreases. It facilitates the passage of grains through the layer. During the tests in purification units of harvesters measurements of air flow velocity over the sieves were made.

Thermodynamic Analysis and Optimization of an Oxyfuel Fluidized Bed Combustion Power Plant for CO2 Capture

In this paper, a 600 MW supercritical oxyfuel fluidized bed combustion power plant is integrated with an air separation unit (ASU) and a flue gas compression and purification unit (CPU). The plant performance is investigated, and two flue gas recirculation modes (i.e., wet and dry modes) are compared under different operating conditions. In the initial analysis, the dry-mode plant has a net power efficiency of 31.6%, while the wet-mode plant has a net power efficiency of 31.5%. In the sensitivity analysis, the air ingress has the most significant influence on the net power efficiency of the plant. The furnace combustion temperature also affects the net power efficiency. The plant is optimized by recovering heat from the ASU, CPU, and acid condenser and utilizing the heat to preheat the feedwater. Although the dry-mode plant has a higher efficiency before optimization, the wet-mode plant has a higher efficiency after optimization; that is, the net power efficiency increases by 2.7% for the wet mode compare...

Deep Distillation Recursive Network for Remote Sensing Imagery Super-Resolution

Deep convolutional neural networks (CNNs) have been widely used and achieved state-of-the-art performance in many image or video processing and analysis tasks. In particular, for image super-resolution (SR) processing, previous CNN-based methods have led to significant improvements, when compared with shallow learning-based methods. However, previous CNN-based algorithms with simple direct or skip connections are of poor performance when applied to remote sensing satellite images SR. In this study, a simple but effective CNN framework, namely deep distillation recursive network (DDRN), is presented for video satellite image SR. DDRN includes a group of ultra-dense residual blocks (UDB), a multi-scale purification unit (MSPU), and a reconstruction module. In particular, through the addition of rich interactive links in and between multiple-path units in each UDB, features extracted from multiple parallel convolution layers can be shared effectively. Compared with classical dense-connection-based models, DDRN possesses the following main properties. (1) DDRN contains more linking nodes with the same convolution layers. (2) A distillation and compensation mechanism, which performs feature distillation and compensation in different stages of the network, is also constructed. In particular, the high-frequency components lost during information propagation can be compensated in MSPU. (3) The final SR image can benefit from the feature maps extracted from UDB and the compensated components obtained from MSPU. Experiments on Kaggle Open Source Dataset and Jilin-1 video satellite images illustrate that DDRN outperforms the conventional CNN-based baselines and some state-of-the-art feature extraction approaches.

An Approach To Address the Low Concentration Methane Emission of Distributed Surface Wells

The majority of gassy mines in China have been located in hilly areas, and distributed surface wells are widely used to recover the methane for mining safety and commercial purposes. However, a large amount of low concentration methane from distributed wells cannot be directly transported due to its high explosion risk, and have to be emitted into the atmosphere, resulting in air pollution and wasting energy. Conventional pressure swing adsorption (PSA) methods are mainly employed to increase the methane concentration for safe transportation. However, they typically adopt large-scale factory mode, which is not effective due to the lack of industrial land for distributed wells. In this study, an efficient approach is proposed to address the low concentration methane emission of distributed wells by designing a distributed purification system, including the units of security drainage, PSA purification, and pressurization. Low concentration methane was initially extracted by the security drainage unit, and then, its concentration was increased in the PSA purification unit. Eventually, after being pressurized in the pressurization unit, the methane parameters can meet the safety requirements of the long distance transportation. Field application of the system was carried out in Sihe Coal Mine in China. The results show that, after purification, the concentration of methane is stable at more than 60%, while the concentration of oxygen was remarkably decreased, and the methane recovery percentage is stable at more than 80%. The total profit of decade is 10936 k¥, and the average daily usable methane volume is 2857.39 m3 as well, which would reduce greenhouse emissions equal to approximately 60.01 km3 carbon dioxide.

Integration of cell-free protein synthesis and purification in one microfluidic chip for on-demand production of recombinant protein.

Recombinant proteins have shown several benefits compared with their non-recombinant counterparts in protein therapeutics. However, there are still some problems with the storage and distribution of recombinant proteins, owing to their temperature sensitivity. Microfluidic chips can integrate different functional modules into a single device because of the advantages of integration and miniaturization, which have the special potential to synthesize drugs when and where they are needed most. Here, we integrated cell-free protein synthesis and purification into a microfluidic chip for the production of recombinant protein. The chip consisted of a main channel and a branch channel. The main channel included two pinches, which were filled with template DNA-modified agarose microbeads and nickel ion-modified agarose beads as the cell-free protein synthesis unit and protein purification unit, respectively. The reaction mixture for protein synthesis was introduced into the main channel and first passed through the protein synthesis unit where the target protein was synthesized; next, the reaction mixture passed through the protein purification unit where the target protein was captured; and, finally, pure protein was collected at the outlet when washing buffer and eluting buffer were sequentially introduced into the branch channel. Enhanced green fluorescent protein (EGFP) was used as the model to investigate the performance of our chip. One chip could produce 70 μl of EGFP solution (144.3 μg/ml, 10.1 μg) per batch, and another round of protein synthesis and purification could be performed after replacing or regenerating nickel ion-modified agarose beads. It should be possible to produce other recombinant proteins on demand with this chip by simply replacing the template DNA.

A viable membrane reactor option for sustainable hydrogen production from ammonia

Conventional hydrogen production from ammonia is both energy and process intensive, requiring high temperature and independent purification units. Here, we present a compact process of energy conversion from NH3 to electricity using a novel membrane reactor, comprised of a dense metallic Pd/Ta composite membrane and Ru/La-Al2O3 pellet catalysts, and a fuel cell unit. The fabricated Pd/Ta composite membrane, having ca. 5 times higher H2 permeability than conventional Pd-Ag membranes, can both lower NH3 dehydrogenation temperature and completely remove an additional hydrogen purification unit. Compared to a packed-bed reactor without membrane, ammonia conversion improves by 75 and 45%, respectively at 425 and 400 °C, and >99.5% of conversion is achieved at 450 °C under pressurized ammonia feed of 6.5 bar. Main barriers of practical application of Pd/Group V metals as a composite hydrogen permeable membrane, embrittlement and durability issues, are overcome owing to pertinent operating temperatures (400–450 °C) of ammonia dehydrogenation coupled with membrane separation. Finally, as-separated hydrogen with <1 ppm of NH3 is provided directly to a polymer electrolyte membrane fuel cell, showing no performance degradation for an extended time of operation. The combined results suggest a feasible and less energy/process intensive option for producing hydrogen or electricity from ammonia.

Multi-angle light scattering as a process analytical technology measuring real-time molecular weight for downstream process control

ABSTRACTFor many protein therapeutics including monoclonal antibodies, aggregate removal process can be complex and challenging. We evaluated two different process analytical technology (PAT) applications that couple a purification unit performing preparative hydrophobic interaction chromatography (HIC) to a multi-angle light scattering (MALS) system. Using first principle measurements, the MALS detector calculates weight-average molar mass, Mw and can control aggregate levels in purification. The first application uses an in-line MALS to send start/stop fractionation trigger signals directly to the purification unit when preset Mw criteria are met or unmet. This occurs in real-time and eliminates the need for analysis after purification. The second application uses on-line ultra-high performance size-exclusion liquid chromatography to sample from the purification stream, separating the mAb species and confirming their Mw using a µMALS detector. The percent dimer (1.5%) determined by the on-line method is in agreement with the data from the in-line application (Mw increase of approximately 2750 Da). The novel HIC-MALS systems demonstrated here can be used as a powerful tool for real-time aggregate monitoring and control during biologics purification enabling future real time release of biotherapeutics.