Column Operation Research Articles

DESIGN, CONSTRUCTION AND AUTOMATIC CONTROL SYSTEM OF SINGLE-STAGE SIX-BED ADSORPTION HEAT PUMP

The construction and automatic control of single-stage six-bed adsorption heat pump for heating and cooling purposes is discussed. The presented device is design to simulate operating conditions as well as temperature and uptake changes in the adsorbers/desorbers and consequently to describe the performance of the six–bed adsorption heat pump. The authors focus on advanced operation and strategy of multi-bed heat pump adsorber/desorber performance configuration. Through the use of a sequential system of sorption columns operation, the continuous character of the gained power of device in a wide range is obtained. It is possible as a result of using in the device the quantitative control of the pump by switching sequentially columns (sequential control), quality control by changing the temperature of heating/cooling water flowing in series or parallel through sorption columns and by changing the time parameter of sorption process (adsorption/desorption time) of the bed.

Column Separation of Vanadium(V) from Complex Sulfuric Solution Using Trialkylamine-Impregnated Resins

Separation of V(V) from simulated complex vanadium-bearing (SCV) solution containing Al(III), Fe(III), P(V), and Si(IV) using trialkylamine (N235)-impregnated resins has been investigated. Batch experiments proved that the optimal pH for adsorption and separation of V(V) from impurities was 1.8. Column experiments showed that V(V) was well adsorbed and separated from the impurities under conditions of flow rate of 1.0 mL min−1 and bed height of 12 cm. Most of the impurities that adsorbed on the N235-impregnated resin were effectively eluted with only 2.92% loss of V(V) using 12 bed volumes (BV) of 2 wt.% Na2SO4. Afterwards, V(V) was concentrated about 3.4 times and most of it was recovered using cycle desorption with 1 BV of 14 wt.% Na2CO3. The concentration of the impurities in the initial feed solution was greatly decreased using the present method, implying that V(V) can be effectively separated from SCV solution by such column operations.

Енергоощадний режим роботи ректифікаційної колони зневоднення етиленгліколю

The article offers theoretical analysis of the possibility of using in the distillation column for dehydration of ethylene glycol of several streams of coolant, which has different temperature to reduce energy costs for ethylene glycol production. The directions for the literary review of modern research were selected: optimization in the design and operation of the distillation column, reduction of energy costs during rectification, methods for assessing the energy efficiency of the rectification process. The purpose of the article is to analyze the efficiency of the modernization of the distillation column to reduce energy costs for ethylene glycol production. Cost reduction is possible due to the use of heat carriers of different temperature potentials. For the purpose of estimating the amount of energy savings, a model is used, where the column is provided with thermal energy produced by a heat pump. The proposed model of heat exchange in the distillation column takes into account the internal convective heat exchange between the reflux condenser and the vat residue and the external heat exchange that is realized by the heat pump. In the proposed model, the heat pump operates on the ideal Carnot cycle, consumes mechanical energy and transfers thermal energy from the reflux condenser to the residue, increasing the temperature potential columns. The simplifications for the model solution are formulated and substantiated, an example of calculating the energy efficiency of the rectification process of a binary mixture of ethylene glycol with water is given, dependence of energy efficiency on the temperature of the alternative heat carrier flow is obtained. It is concluded that there is an extreme of theoretical relative economy of energy costs in the column of dehydration of ethylene glycol from the temperature value of the second heat carrier flow.

Improved protein A resin for antibody capture in a continuous countercurrent tangential chromatography system.

Continuous countercurrent tangential chromatography (CCTC) enables steady-state continuous bioprocessing with low-pressure operation and high productivity. CCTC has been applied to initial capture of monoclonal antibodies (mAb) from clarified cell culture harvest and postcapture polishing of mAb; however, these studies were performed with commercial chromatography resins designed for conventional column chromatography. In this study, a small particle size prototype agarose resin (20-25 µm) with lower cross-linking was co-developed with industrial partner Purolite and tested with CCTC. Due to increased binding capacity and faster kinetics, the resulting CCTC process showed more than a 2X increase in productivity, and a 2X reduction in buffer consumption over commercial protein A resins used in previous CCTC studies, as well as more than a 10X productivity increase versus conventional column operation. Single-pass tangential flow filtration was integrated with the CCTC system, enabling simple control of eluate concentration. A scale-up exercise was conducted to provide a quantitative comparison of CCTC and batch column chromatography. These results clearly demonstrate opportunities for using otherwise unpackable soft small particle size resins with CCTC as the core of a continuous bioprocessing platform.

Dynamic Control of Sensor and Actuator failures in Multivariable Distillation Column

This paper examines the impact of sensor and actuator failures in the operation of a multivariable distillation column. Several failure scenarios are evaluated including failures of sensors and actuators in various scales of magnitudes and durations. The results obtained illustrate the ability of process controllers in suppressing the impact of these unwanted events. Closed-loop dynamic responses of the process revealed capabilities of these controllers in dealing with upsets that are small in magnitude and duration. In the case of larger and longer process upsets, process controllers are not adequate in providing the necessary corrective measures. This leaves the necessary interventions to be taken by the plant operators, following alarms that would have been triggered in typical plant operation scenario.

A Low Complexity Decoding Scheme for Raptor-Like LDPC Codes

Recently, a new structure of low density parity check (LDPC) code named raptor-like LDPC code has attracted much attention. It has better performance at low code rate. In this paper, a novel decoding scheme for raptor-like LDPC code is proposed. First, the Gaussian approximation density evolution (GADE) algorithm is used to track and analyze the message transmission during the decoding process. It is found that certain log likelihood ratio (LLR) messages can be approximated by “zero” setting in the early iteration of raptor-like LDPC decoding. In other words, some column and row operations could be eliminated without compromise the performance. Next, we propose a new decoding scheme, which can skip unnecessary column and row operations. In comparison with the traditional belief propagation (BP)-based LDPC decoding scheme, the proposed scheme can reduce the decoding complexity. Additionally, a new algorithm is developed to facilitate the selection of the early iteration number. With this novel design, the proposed decoding scheme performs almost the same as the traditional BP-based scheme. To proof the concept, the raptor-like LDPC codes in the ATSC3.0 digital TV system are used to evaluate the proposed scheme, in comparison with the traditional BP-based schemes, i.e., sum-product algorithm (SPA), offset min-sum algorithm (OMSA), and normalized min-sum algorithm (NMSA). The simulation results confirm that the proposed scheme can reduce the decoding complexity without sacrifice in performance for all SPA, OMSA, and NMSA methods. About 10% complexity reduction can be achieved. This will reduce the buttery consumption for Internet of Things (IoT) and handheld devices.

Topological operations for editing the singularity on a hex mesh

This paper introduces topological operations for editing the singularity on a hex mesh while maintaining the connectivity of hexahedral mesh. The operations include (1) an enhanced column collapse operation that can avoid generating the poor-quality elements; (2) a column insertion operation that is the opposite operation of column collapse; (3) four semantic operations for achieving the movement of different types of singularity pairs based on column operations. To demonstrate their effectiveness, two related applications are provided. One is moving face-based hex mesh editing, in which the interface between the original mesh and the new region mesh is made structured using the semantic operations. The other is hex mesh structure simplification based on the topological operations.

Change in Distillation Column Control Philosophy Using Dynamic Simulation

AbstractAt condensate stripper of a cracker plant with design control philosophy for composition control pant was facing operational difficulty. Due to disturbance in operating parameter column was becoming unstable and product was getting offspec w.r.t. desired purity. One of the applications of dynamic simulation is to troubleshoot the challenges related to control philosophy in practical application. Since steady-state simulation models cannot predict behavior with respect to time, initially steady state model and finally a dynamic model was developed in Aspen HYSYS. The model is used to study the process behavior for existing control philosophy and proposed philosophy. To avoid column puncture and without waiting for plant shut down the existing Temperature Indicator (TI) considered as Temperature Indicator Controller (TIC) for the study. A new control philosophy was developed based on the response of variables after disturbances in feed rate and composition. The revised control philosophy has been implemented and is now working satisfactorily, providing stabilized operation of the column with consistent bottom product quality. This has helped to reduce the loss of C2s in the bottom stream by about 700 ppm, for savings of about $100,000 USD per year.

Conditioning Heavy-Oxygen Water by Rectification under Vacuum

An investigation into the distillation of heavy-oxygen water under vacuum has been performed. Conditions and parameters of the operation of distillation columns for the conditioning of heavy-oxygen water have been determined.

110th Anniversary: Column Efficiency: From Conception, through Complexity, to Simplicity

One of the most enduring concepts in chemical engineering is that of the efficiency of column operations such as distillation, absorption, and stripping. The concept was first articulated by W. K. ...

Operation, validation and model comparison for a reactive dividing wall column

The reactive dividing wall column (RDWC) is a highly integrated apparatus that combines the features of reactive distillation and dividing wall column technology. The high degree of integration results in complex interactions between vapour-liquid equilibrium, chemical reaction and component distribution. This leads to a considerably more complex column design and operation than for conventional distillation columns. Therefore, precise simulation models are a prerequisite for a successful implementation and operation of this technology. A newly developed rate-based (NEQ) RDWC model for packed columns is presented and a detailed investigation on the influence of separation modeling was carried out. Comprehensive experimental RDWC data are presented for the reference system of the butyl acetate transesterification with hexanol and employed for a model validation. The validation results for the NEQ model are compared to the well-known equilibrium stage (EQ) approach. The rate-based model is shown to predict the inner flows and concentrations of the column with higher precision. Furthermore, an analysis of the validation results enhances the understanding of the interactions between separation, chemical reaction and reactant conversion.

Linking the multiscale porous structure of hexacyanoferrate-loaded silica monoliths to their hydrodynamic and cesium sorption properties

Multiscale porous silica monoliths functionalized with potassium/copper hexacyanoferrate (HCF) have been evaluated for the column extraction of cesium from natural water. Compared with commercial silica gel particles, results show that the hierarchically porous architecture of the monoliths improves the bed efficiency in column extraction, and the selectivity, distribution coefficient and exchange kinetics in batch extraction. Cesium breakthrough experiments show that these preferable properties of the monolithic structure are maintained in column operation. This analysis of the batch and breakthrough experiments is supported by scanning and transmission electron microscopy data, residence time distributions, and reactive transport modeling assuming dispersive flow in the macroporous intraskeletal channels and diffusion inside the walls of the structure and the HCF aggregates.

Experimental and simulated operation of absorption column for the removal of VOC from air

Separation processes represent one of the most important operation in chemical industry. The most used techniques are distillation and absorption. The Industrial Chemistry Bachelor’s Degree program at the University of Milano, Chemistry Department, includes a third-year course titled “Industrial Plants with Laboratory”. This laboratory (six university credits course) is devoted to separation processes with an average annual attendance of about 80 people. An experience concerning the use of an absorption column is proposed to the students. A 1 m height column with an internal diameter of 0.044 m, filled with Sulzer-type structural bodies is used for data collection in steady state conditions. Water purifies a mixture of a VOC (acetone) and air in counter current. With the collected data, students check the material balance on the column and, knowing the height of the column, determine the global diffusion coefficients. Moreover, the software PRO II 9.3 by AVEVA is used for the simulation of the plant. The comparison between experimental and simulated data is a key aspect of the laboratory and guarantees a cross-check of both activities. Students evaluation of the course is strongly positive.

A Gibbs energy-driving force method for the optimal design of non-reactive and reactive distillation columns

A simple Gibbs energy-driving force method for the design of non-reactive and reactive distillation columns has been developed. Based on the binary driving force concept and the equilibrium Gibbs energy computation, a systematic procedure for the design of non-reactive distillation columns (NRDC) and reactive distillation columns (RDC) is proposed. The design method exploits the connection between the driving force values and the equilibrium Gibbs energy to determine the number of stages, the optimal feed location, and the heat required at the top and bottom of the column and the minimum reflux ratio. The final design guarantees an optimal operation since maximum thermodynamic efficiency is achieved. The maximum thermodynamic efficiency criterion is equivalent to the minimum entropy condition required for a stable operation of the distillation columns. The method is applied for the design of two non-reactive systems: a) Benzene-Toluene ideal system and b) Ethanol-Water non-ideal system. A reactive distillation column considering the isomerization of n-butane in the presence of an inert compound is designed. The optimal thermal feed condition obtained through the maximum separation efficiency guarantees that the final designs obtained correspond to the minimum energy requirements for the design target of separation.

Column bioleaching of metals from refinery spent catalyst by Acidithiobacillus thiooxidans: Effect of operational modifications on metal extraction, metal precipitation, and bacterial attachment

The feasibility of column bioleaching in the recovery of valuable metals (Ni, V, Mo, and Al) from an uncrushed petroleum refinery spent hydroprocessing catalyst using Acidithiobacillus thiooxidans has been reported. Different operational strategies such as submerged bioleaching in continuous mode, submerged bioleaching in resting period mode, free flow bioleaching in continuous mode, and free flow bioleaching in resting period mode were tested to find out the optimum bioleaching strategy for the recovery of metals from spent hydroprocessing catalyst. Among various operational modifications, submerged bioleaching in continuous mode was considered as the best strategy in which about 82.9% of Ni, 33.4% of Al, and 22.7% of Mo were leached after 315 h of column operation. The maximum yield of V (53.6%) in this column was achieved in 105 h, after which, a rapid decrease in its yield was observed, possibly due to its precipitation. The field emission scanning electron microscopy (FESEM) analysis revealed the presence of V in precipitates. The modified kinetic models showed that the leaching of Al, V and Mo followed the chemical control model, whereas the dissolution of Ni was controlled by diffusion control reaction. The bacterial attachment study with FESEM indicated that the metal toxicity was induced on bacterial cells attached to the sulfur particles. The results of the current study indicate that column bioleaching of spent hydroprocessing catalyst is effective in leaching of Ni and V, whereas leaching of Al and Mo require further treatments.

Importance of Simultaneous Combustion of Tritium and Hydrocarbons by Detritiation System in a Fire Event at Nuclear Fusion Facility

A detritiation system (DS) is required to remove tritium from the atmosphere of a nuclear containment in any extraordinary situations. Realization of a DS that does not require heating of a catalyst reactor for tritium oxidation and frequent switching operation of adsorption columns for tritiated vapor collection will greatly contribute to the improvement of fusion safety. Concerning the catalyst reactor, it has been demonstrated that tritium can be oxidized at room temperature without any heating by the developed hydrophobic catalyst. To achieve a high tritium conversion efficiency for detritiation, it has already been revealed that suppression of production of tritiated hydrocarbons by hydrogenation reactions as side reactions of tritium oxidation in a catalyst reactor is the key issue to be solved. We have to pay special attention to ethylene among hydrocarbons because ethylene is easily tritiated by reaction of hydrogenation. In this study, complete combustion of ethylene at room temperature in the catalyst reactor is proposed as a measure to suppress the formation of tritiated hydrocarbons. Catalytic combustion characteristics of hydrocarbons were obtained, and the change in the ignition temperature by a change in each design parameter of the catalyst was demonstrated. Concerning noble metal species, platinum is superior to palladium due to less susceptibility to water vapor. The smaller the particle size of noble metal is, the higher the activity is, but because it is more susceptible to water vapor, the particle size of noble metal can be optimized. It was suggested that there is an optimum value for the pore size of the catalytic support.

Mathematical modelling and simulation of packed bed column for the efficient adsorption of Cu(II) ions using modified bio-polymeric material

In this study, the application ability of a produced bio-polymer material as a chelating adsorbent for the adsorption of Cu(II) ions from aqueous solution was assessed in a packed bed column. The material was characterised by some physical and chemical technique. The SEM image showed that the material is made up of an orderly porous structure, which will aid adsorption in the process, while BET proved that the material possesses large surface areas. The experimental data were fitted to the Swan model. The Swan model, in combination with the adsorption parameters obtained from pH equilibrium model, was used to predict column breakthrough curves for the adsorption of Cu(II) ions onto the adsorbent. The model was able to predict the breakthrough curve reasonably well at column operation pH of 5.1 and the diffusion coefficient was calculated to be between 2.82 × 10−10 and 3.12 × 10−10 m2/s at different bed heights. Several adsorption and desorption cycles were carried out during the column operation. There was a mass loss of the beads during the third and fourth cycles of adsorption and desorption cycles of 5.0 and 11.0 percent respectively. The used adsorbent capacities in the second, third and fourth cycles of adsorption were 98, 91 and 86 percent respectively. In the fifth cycle of adsorption desorption operations, the adsorption performances reduced greatly in comparison to previous cycles and a 22 percent weight loss in the mass of the beads was observed.

Graphene Oxide Supported on Amberlite Resin for the Analytical Method Development for Enhanced Column Preconcentration/Sensitive Flame Atomic Absorption Spectrometric Determination of Toxic Metal Ions in Environmental Samples

Graphene oxide (GO)-layered nanosheets with a two-dimensional carbon lattice is linked to styrenic carbon of porous XAD polymeric resin via an azo spacer arm without utilizing any oxygen-containing functionality for the first time. The adopted synthesis approach makes all of the epoxy, hydroxyl, carbonyl, and carboxyl groups on the axial and basal planes of the GO sheet available for coordination with metal ions, and the introduction of hydrophilic character as result the highest preconcentration factor for Pb (500) was observed among the GO composites used as a solid-phase extractant in column operation. The developed analytical methodology using XAD–GO for the preconcentration of Pb, Cd, and Zn ions permits the use of an economically viable less sensitive atomic absorption spectrometry for their trace determination in water samples because of the enhanced quantification limit. The application of polymer-immobilized GO in a column sorts out the problem of escape of toxic GO into the environment, and unde...

Adsorption of crystal violet from aqueous solution in continuous flow system using bone char

In the face of water scarcity and more strict environmental regulation, water treatment is a demand and reuse is being encouraged in diverse production processes. Advanced treatments, such as adsorption, may be indicated for specific and/or recalcitrant contaminants removal, such as dyes, present in textile industries wastewater, for example. However, the conventional adsorbents cost may be unattractive for such a purpose. In this context, bone char, 0.5–1.4 mm particle size, mesoporous structure, produced from tannery, food and cattle breeding waste, was tested to remove crystal violet dye from synthetic effluent, in a lab scale fixed bed adsorption column. A complete removal was observed up to 74 min of column operation. The greatest adsorption capacity (qo = 20.63 mg·g−1) was observed for the lowest flow rate evaluated (Q = 15.4 ± 0.8 mL·min−1) and intermediate bed depth (h = 24 cm) at 27.1 ± 0.9 °C. At the same operational conditions, the experimental breakthrough curve was better predicted by Yan model (qo = 20.42 mg·g−1; a = 1.667; b = 2.93 and R2 = 0.955) compared to Thomas model (qo = 22.44 mg·g−1; kTH = 0.056 mL·mg−1·min−1 and R2 = 0.878).

Sulfonated polystyrene waste in liquid phase as on-exchange material to remove Cr (III) in aqueous solution

Polystyrene waste from disposal products has been sulfonated in a homogeneous phase by using sulfur acid and cyclohexane to synthesize cation exchange material, which could be used to uptake Cr(III) from aqueous solution. In this study, by analysis techniques such as SEM (Scanning Electron Microscope) and FITR (Fourier transform infrared), the surface area of material groups is revealed that they are larger than raw materials to increase point of contact with Cr(III). Moreover, it is proven that the additional sulfonic groups were presented. The results pointed out that the dependence of ion exchange column operation on many factors (size, reaction time, flow rate,…) exert an influence on the efficiency of Cr(III) ion treatment. In addition, experimental conditions which affect the sulfonation conversion, have been investigated such as temperature, modification time, H2SO4 concentration,… It was found that reducing the Cr(III)concentration by 87.51% and 98.72% for 10 cm and 15cm ion-exchange height layer after 3 hours operation in the reaction conversion using the column 8mm diameter, flow rate 2.00ml per minute with shaking speed 220 rpm. The experimental data were consistent with Thomas and Yoon-Nelson kinetic models. The ability of sulfonated waste polystyrene to uptake chromium ion from aqueous water has been evaluated significantly.