Distillation Technology Research Articles

New process function-based selection and configuration methodology for Process Equipment Assemblies (PEAs) exemplified on the unit operation distillation

Process Equipment Assemblies (PEA) are pre-designed equipment sets which are selected instead of time-consuming tailor-made design. This paper introduces a new method for the selection and configuration of PEAs exemplified on the unit operation distillation. First step of the new methodology is the selection of the most suitable technology applying matching matrices. The matching matrix required for selecting a suitable distillation technology is introduced. Next a process function-based planning approach is executed using so called master block flowcharts (MBF). These technology specific flowcharts contain all possible process functions required for any potential separation task and contain the technology specific main function and technology independent process functions. Considering process boundary conditions and functions already available in the infrastructure, the MBF is reduced to the functions required for the process. Next, concrete PEAs are selected starting with the main function where the separation of the fluids takes place using the PEA operating range as the main selection criterion. A tool required to determine the operating range of a distillation column is demonstrated. Finally, the PEAs for auxiliary functions are selected from a databank.

Using the sun to co-generate electricity and freshwater

Using the sun to co-generate electricity and freshwater

Robust dual-layer Janus membranes with the incorporation of polyphenol/Fe3+ complex for enhanced anti-oil fouling performance in membrane distillation

The effective treatment of oily saline wastewater has posed a challenge for membrane distillation (MD) technology due to the severe oil fouling. To address this dilemma, a Janus membrane was successfully developed in this study by incorporating tannic acid (TA)/ferric chloride (FeCl3) complex and polyvinylidene fluoride (PVDF) onto the polytetrafluoroethylene (PTFE) membrane surface via the nonsolvent-induced phase separation (NIPS) method. The characterization results demonstrated that the TA-Fe3+ complex was compatible with the PVDF, and the composite surface layer was firmly attached on the PTFE substrate. Furthermore, the Janus membrane showed a high hydrophilicity and strong underwater superoleophobicity (oil contact angle, 154.80 ± 1.07°), with had an excellent vapor flux (28.30 ± 1.18 Lm−2 h−1) compared with the membrane without the embedding of TA-Fe3+ complex (18.16 ± 1.45 Lm−2 h−1). According to theoretical arithmetic of mass transfer, the evaporation interface of the Janus membrane had transferred during the MD process, contributing to promoting the mass transfer performance and fouling resistance. When treating oily saline emulsion, the Janus membrane exhibited a good desalination and anti-oil fouling stability compared to the control membranes. This study suggests that the fabricated lipophobic Janus MD membrane has great potential in the treatment of oily saline wastewater.

Electrospun Nanostructured Membrane Engineering Using Reverse Osmosis Recycled Modules: Membrane Distillation Application.

As a consequence of the increase in reverse osmosis (RO) desalination plants, the number of discarded RO modules for 2020 was estimated to be 14.8 million annually. Currently, these discarded modules are disposed of in nearby landfills generating high volumes of waste. In order to extend their useful life, in this research study, we propose recycling and reusing the internal components of the discarded RO modules, membranes and spacers, in membrane engineering for membrane distillation (MD) technology. After passive cleaning with a sodium hypochlorite aqueous solution, these recycled components were reused as support for polyvinylidene fluoride nanofibrous membranes prepared by electrospinning technique. The prepared membranes were characterized by different techniques and, finally, tested in desalination of high saline solutions (brines) by direct contact membrane distillation (DCMD). The effect of the electrospinning time, which is the same as the thickness of the nanofibrous layer, was studied in order to optimize the permeate flux together with the salt rejection factor and to obtain robust membranes with stable DCMD desalination performance. When the recycled RO membrane or the permeate spacer were used as supports with 60 min electrospinning time, good permeate fluxes were achieved, 43.2 and 18.1 kg m−2 h−1, respectively; with very high salt rejection factors, greater than 99.99%. These results are reasonably competitive compared to other supported and unsupported MD nanofibrous membranes. In contrast, when using the feed spacer as support, inhomogeneous structures were observed on the electrospun nanofibrous layer due to the special characteristics of this spacer resulting in low salt rejection factors and mechanical properties of the electrospun nanofibrous membrane.

Impact of Various Feed Properties on the Performance of a Control System for a Multiple Dividing Wall Column Pilot Plant

Despite the attractive savings potential of multiple Dividing Wall Columns (mDWC), there are no reports in the open literature of an existing application so far. In this perspective, the control of mDWCs has been a rather little-investigated field. Pilot plants are a necessary step needed to further expand the application window of this sustainable distillation technology. This contribution aimed to show that mDWCs are sufficiently flexible, providing stable operation, even with suboptimal control structures arising from design limitations imposed by equipment. For this purpose, the pilot column design was assessed using dynamic simulation to evaluate its operability in case of different disturbances as well as different feed mixtures. The results showed that, in all cases, the column could be stabilized and product purities maintained. This suggests that even complex configurations such as mDWCs offer sufficient amount of flexibility to allow for the application of one design in different services.

Lane Line Detection Based on Object Feature Distillation

In order to meet the real-time requirements of the autonomous driving system, the existing method directly up-samples the encoder’s output feature map to pixel-wise prediction, thus neglecting the importance of the decoder for the prediction of detail features. In order to solve this problem, this paper proposes a general lane detection framework based on object feature distillation. Firstly, a decoder with strong feature prediction ability is added to the network using direct up-sampling method. Then, in the network training stage, the prediction results generated by the decoder are regarded as soft targets through knowledge distillation technology, so that the directly up-samples branch can learn more detailed lane information and have a strong feature prediction ability for the decoder. Finally, in the stage of network inference, we only need to use the direct up-sampling branch instead of the forward calculation of the decoder, so compared with the existing model, it can improve the lane detection performance without additional cost. In order to verify the effectiveness of this framework, it is applied to many mainstream lane segmentation methods such as SCNN, DeepLabv1, ResNet, etc. Experimental results show that, under the condition of no additional complexity, the proposed method can obtain higher F1Measure on CuLane dataset.

Sequential two-column batch distillation processes for separation of ternary mixture containing three binary minimum boiling point homoazeotropes

Based on the continuous two columns distillation technology, it is difficult to separate the ternary mixture of n-hexane/ethanol/butanone, which contains three binary minimum boiling point homoazeotropes. Through analyzing characteristics of batch distillation and the phase behavior, it is feasible to achieve high purity separation of this kind of complex mixture by two-column batch distillation. Three sequential two-column batch distillation processes including Process A (Double columns with series operation), Process B (Double columns with parallel-then series operation) and Process C (Single column-then double columns process) were designed and analyzed in this work. The processes were evaluated and optimized from the aspects of economy and environment. In terms of economy, environment impacts and operating time, Process B is prior to Process A and Process C. Based on the thermodynamic analysis of the column, the heat integration problem of Process B is considered, which includes a self-preheating scheme at first step, and a heat exchange scheme in which high-pressure column top vapor provide part of the heat to low-pressure column bottom at second step. Compared with the unimproved Process B, the operating cost of the improved Process B can be reduced by 28% and TAC can be reduced by 3% at step 1. The operating cost of the improved Process B can be reduced by 30% at step 2.

Improvement of nanostructured electrospun membranes for desalination by membrane distillation technology

A systematic study is carried out to determine the optimum electrospinning preparation condition to prepare an adequate electrospun nanofibrous membrane (ENM) for direct contact membrane distillation (DCMD). A structural properties investigation of ENM was carried out because of the significant impact of its architectural structure, nanofiber diameter, inter-fiber space and ENM thickness, on DCMD performance. The morphology, hydrophobicity, mechanical properties, crystallinity and DCMD desalination were investigated. A long-term DCMD experiment (100h) was carried out using 30 g/L NaCl aqueous solution, both in the feed and permeate side of the optimum ENM membrane to evaluate its potential to produce drinkable water in case of lack of distilled water, for instance in a remote area, emergency situation, and/or portable system. In this case, drinkable water could be produced after 28 h with a permeate flux of 57.5 kg/m2.h and a salt rejection factor greater than 99.9%. Another long-term DCMD experiment (65 h) was conducted using 30 g/L NaCl aquesous solution as feed but at a higher temperature and distilled water as permeate to evaluate the desalination stability, wettability and scaling of the optimum ENM. A permeate flux of 58.5 kg/m2.h was obtained with a salt rejection factor greater than 99.9%.

Membrane cleaning and pretreatments in membrane distillation – a review

Membrane distillation (MD) is an emerging thermal-based membrane technology that has the capacity to treat a wide range of feed waters, including high salinity brines and wastewater. Compared with pressure-driven processes, MD has the following advantages: low electrical energy consumption, complete removal of non-volatile solutes and ambient operating pressures. On the other hand, membrane fouling and pore wetting remain a challenge holding back its wider industrial implementation. To manage this issue, effective pretreatment and cleaning strategies are essential, as with other membrane processes. Despite the importance of these aspects for achieving a stable and reliable water treatment process, far too little attention has been paid to them in the MD literature. Evidence of this is that a comprehensive review on both membrane cleaning and pretreatment in MD is still lacking, despite the large and growing number of publications related to the technology. In this work, we first provide an overview of the three main types of fouling present in MD: inorganic, organic and biological fouling. After this we review, in detail, the use of pretreatment protocols in a range of MD applications, highlighting their efficacy in preventing fouling and ensuring stable performance. Next, we review the use of state-of-the-art chemical and physical cleaning strategies and discuss the development of ‘self-cleaning’ membranes that are superhydrophobic or omniphobic. Finally, future research directions are suggested, with the aim of helping researchers working in this field to develop membrane distillation technology towards wider commercial implementation.

The potential recovery energy of SWD (sea water desalination) by SGP (salinity gradient power)

Fresh water is needed in industrial activities. For these needs sea water is usually used as raw material if the plant is near the sea and far from the river. SWD (sea water desalination) is used to process sea water to fresh water, that is by reducing levels of salinity or reducing levels of total dissolved solid (TDS). There are two technologies in SWD, namely thermal distillation and reverse osmosis (RO) membrane technology. Residual SWD process or also called blowdown water has high salinity levels can be converted into electrical energy through SGP (salinity gradient power). There are two technologies to capture energy from salinity differences, namely PRO (Pressure Retarded Osmosis) and RED (Reverse Electrodialysis). PRO and RED are renewable energy technology, there are no emision, no moving part, abundant availability in nature and can be recycled. In this article, an analysis for SWD of oil refinery is carried out. From the analysis results it is known that the plant uses thermal distillation technology, requires power as 64.25 MW and 3,403 m3/h seawater to produce 242 m3/h freshwater. With SGP, the potential recovery of power gained is 0.786 MW. This recovery potential is still too small when compared to energy requirements of SWD with thermal distillation technology, but if it use RO technology that only requires 3.6-5.7 kWh/m3 or 0.87 - 1.40 MW to produce 242 m3/h, a significant impack to saving energy will be obtained.

Design of multi-loop control systems for distillation columns: review of past and recent mathematical tools

Abstract Design of a control structure in distillation columns involves selecting proper sets of manipulated and controlled variables (often including tray temperatures for inferential control of product compositions) and one-to-one pairing between the two sets. In this paper, various mathematical tools for achieving this goal are reviewed. First, traditional methods such as Singular Value Decomposition (SVD) and Relative Gain Array (RGA) that build upon a simplified steady-state or dynamic model of the column are explored. The role of optimization in systematizing the control design procedures is also investigated. Then, more recent inferential control techniques that rely on statistical methods such as Principal Component Regression (PCR), Partial Least Squares Regression (PLSR), and other machine learning techniques such as Artificial Neural Networks (ANN) and Support Vector Machine Regression (SVMR) are discussed extensively. The discussions include newer distillation technologies with complex configurations such as dividing-wall columns. Finally, the use of process simulators in aiding the control structure design of distillation columns is surveyed.

Review of Neural Network Algorithm and Its Application in Reactive Distillation

Artificial Neural Networks (ANN) can accurately identify and learn the potential relationship between input and output, and have self-learning capabilities and high fault tolerance, which can be used to predict or optimize the performance of complex systems. Reactive distillation integrates reaction and rectification into one device, so that the two processes occur at the same time and at the same place, but at the same time it also produces highly nonlinear robust behavior, making its process control and optimization unable to use conventional methods. Instead, neural network algorithms must be used. This paper briefly describes the research progress of neural network algorithms and reactive distillation technology, and summarizes the application of neural network algorithms in reactive distillation, aiming to provide reference for the development and innovation of industry technology.

Environmental impact assessment of desalination plants through observations and modeling over Central Red Sea-Yanbu and Rabig

Desalination remains in Saudi Arabia the supreme viable alternative to boost the future water supply requirements. The present research is focused on the environmental issue observations and modeling based on dissolved trace metals, hydrographic parameters, and nutrients at the discharging plume and nearby locations of Rabig desalination plant (RDP) and Yanbu desalination plant (YDP) located at the north of Jeddah city (~ 150 and 400 km, respectively). A multi-effect distillation (MED) technology is used in RDP whereas, in YDP, a combination of multistage flashing (MSF), reverse osmosis (RO), and MED technologies is in use for the production of potable waters. The concentration of dissolved Cu, Ni, and Zn was assessed by using cathodic stripping voltammetry. The observed pattern was reflecting an average value of dissolved Cu, Ni, and Zn at RDP that was 8.24, 5.28, and 12.69 nM, respectively. The correspondent changes at YDP were 17.53, 18.06, and 71.19 nM of Cu, Ni, and Zn, respectively. The statistical validation shows a significant positive correlation between metals and temperature with salinity and a significant negative correlation of dissolved oxygen and pH. The background concentration of nearby YDP is comparatively higher and which is ascribed by the negative effects of nearby industries. Detailed investigation of circulation pattern and brine discharge analysis near the Yanbu desalination plant also carried out with the help of 3d hydrodynamical numerical model Delft3d.

Sustainability Assessment and Techno-Economic Analysis of Thermally Enhanced Polymer Tube for Multi-Effect Distillation (MED) Technology.

Metal-alloys tubes are used in the falling-film evaporator of the multi-effect distillation (MED) that is the dominant and efficient thermal seawater desalination process. However, the harsh seawater environment (high salinity and high temperature) causes scale precipitation and corrosion of MED evaporators’ metal tubes, presenting a serious technical challenge to the process. Therefore, the metal/metal alloys used as the material of the MED evaporators’ tubes are expensive and require high energy and costly tube fabrication process. On the other hand, polymers are low-cost, easy to fabricate into tubes, and highly corrosion-resistant, but have low thermal conductivity. Nevertheless, thermally conductive fillers can enhance the thermal conductivity of polymers. In this article, we carried out a feasibility-study-based techno-economic and socioeconomic analysis, as well as a life-cycle assessment (LCA), of a conventional MED desalination plant that uses titanium tubes and a plant that used thermally enhanced polymer composites (i.e., polyethylene (PE)-expanded graphite (EG) composite) as the tubes’ material. Two different polymer composites containing 30% and 40% filler (expanded graphite/graphene) are considered. Our results indicate that the MED plant based on polymer composite tubes has favored economic and carbon emission metrics with the potential to reduce the cost of the MED evaporator (shell and tubes) by 40% below the cost of the titanium evaporator. Moreover, the equivalent carbon emissions associated with the composite polymer tubes’ evaporator is 35% lower than titanium tubes. On the other hand, the ozone depletion, acidification, and fossil fuel depletion for the polymer composite tubes are comparable with that of the titanium tubes. The recycling of thermally enhanced polymers is not considered in this LCA analysis; however, after the end of life, reusing the polymer material into other products would lower the overall environmental impacts. Moreover, the polymer composite tubes can be produced locally, which will not only reduce the environmental impacts due to transportation but also create jobs for local manufacturing.

Photothermal Membrane Distillation toward Solar Water Production.

Freshwater production is one of the biggest global challenges today. Though desalination can provide a climate-independent source of clean water, the process requires a high energy consumption. Emerging advancement of photothermal nanomaterials and the urgent demand for a green technology transition have reinvigorated the established solar distillation technology. The current development of photothermal vaporization focuses on material innovation and interfacial heating, which largely emphasizes vapor generation efficiency, without considering pragmatic water collection. Moreover, salt accumulation is another critical issue of seawater solar-driven vaporization. The incorporation of photothermal materials into a photothermal membrane distillation (PMD) solar evaporator design harmoniously resolves these issues through combination of renewable energy and efficient interfacial distillation, to achieve the ultimate goal of practical saline water into freshwater conversion. At this juncture, it is imperative to review the recent opportunities and progresses of the PMD system. Here, the fundamental photothermal processes, strategies for efficient evaporator design, evaluation of various criteria for photothermal material incorporation with desired properties, discussions on desalination, water treatment, and energy generation applications are covered. Guidelines in material and system designs to further advance the PMD system that is highly promising in delivering portable water for both large-scale and decentralized systems are provided.

Application of energy-saving hybrid distillation-pervaporation process for recycling organics from wastewater based on thermoeconomic and environmental analysis

Acetonitrile and n-propanol play an indispensable role in the manufacture of perfume and photosensitive materials, and the demand for these chemicals in China is growing. In this work, a series of processes was explored for achieving sustainable and green separation of wastewater containing acetonitrile and n-propanol. The solvent with high separation performance was determined by the combination of relative volatility and biological toxicity. Based on the sequential iterative optimization sequence and taking the minimum total annual costs (TAC) as the objective function, the program written by Visual Basic software was used to optimize the parameters of the basic process. The steam recompression assisted distillation and pervaporation (PV) technology are combined to reduce the energy consumption. Through the Heat Exchanger Network Synthesis (HENs) option, the heat recovery in the process was further improved. Furthermore, exergy and environmental analyses were further used to assess the feasibility of several separation processes. The results showed that compared to the basic process, the TAC and exergy loss of vapor recompression assisted distillation process were reduced by 43.6% and 12.65%, respectively. The use of heat integration and PV technology further reduced energy consumption. The TAC and emissions of novel hybrid process were saved by 74.6% and 53.87%, respectively, which indicates the feasibility of the processes for continuously updated cleaner production.

Membrane technology applied to steel production: Investigation based on process modelling and environmental tools

A model of a two-stage membrane separation process for CO2 capture from iron and steel industry as well as a model for gas-liquid absorption using methyl di-ethanol amine are investigated and compared in the present paper. In order to compare these CO2 capture technologies, the following processes have been investigated: i) two air separation technologies based on distillation and membranes in order to produce the oxygen used in the basic oxygen furnace; ii) a plant for steel production using basic oxygen furnace technology and iii) two plants for CO2 capture based on the above-mentioned technologies. The annual production capacity of the steel mill is 4,000,000 tones. An O2 separation rate of about 96% was obtained in the distillation technology, and about 33% in the membrane technology. The CO2 capture rate obtained in the membrane case is higher than that obtained using methyl di-ethanol amine (93.97% vs. 89.97%). From a technical standpoint, the simulation results lead to the conclusion that membrane-based technology can be a suitable alternative for CO2 removal for steel production. O2 separation using membrane involves higher air flow-rates, lower O2 separation rate compared to cryogenic air distillation (e.g., 33.15% vs. 96.47%) and lower O2 purity. The cases were also evaluated from an environmental point of view using the Life Cycle Assessment methodology. The environmental evaluation shows that membrane technology can lead to lower environmental emissions if membrane production is based on benzene derived from toluene hydrodealkilation, and chlorine and sodium hydroxide are produced using mixed technologies.

A Conductive Hydrophobic Polyaniline Sandwiched Polyvinylidene Fluoride Membrane for Early Detection of Surfactant-Induced Wetting in Membrane Distillation Using Impedance

Wetting of hydrophobic membranes is considered to be one of the major limitations that must be overcome to further the development of membrane distillation technology. Low surface tension liquids c...

Energy, Exergy, and Thermo-Economic Analysis of Renewable Energy-Driven Polygeneration Systems for Sustainable Desalination

Reliable production of freshwater and energy is vital for tackling two of the most critical issues the world is facing today: climate change and sustainable development. In this light, a comprehensive review is performed on the foremost renewable energy-driven polygeneration systems for freshwater production using thermal and membrane desalination. Thus, this review is designed to outline the latest developments on integrated polygeneration and desalination systems based on multi-stage flash (MSF), multi-effect distillation (MED), humidification-dehumidification (HDH), and reverse osmosis (RO) technologies. Special attention is paid to innovative approaches for modelling, design, simulation, and optimization to improve energy, exergy, and thermo-economic performance of decentralized polygeneration plants accounting for electricity, space heating and cooling, domestic hot water, and freshwater production, among others. Different integrated renewable energy-driven polygeneration and desalination systems are investigated, including those assisted by solar, biomass, geothermal, ocean, wind, and hybrid renewable energy sources. In addition, recent literature applying energy, exergy, exergoeconomic, and exergoenvironmental analysis is reviewed to establish a comparison between a range of integrated renewable-driven polygeneration and desalination systems.

Research progress and optimization prospect of constant boiling distillation technology

Coboiling distillation is a special distillation method of separating the azeotropic system mixture, which is widely used in petroleum refining and chemical production. This paper reviewed the selection and characteristics of azeoliling agents, and introduced the research progress of home and abroad in detail. The system compares the advantages and disadvantages of the traditional constant boiling distillation and the new heat pump, compare the advantages, and presents the prospect of constant boiling distillation.