Number Of Trays Research Articles

Investigation of material cost of a propane-propylene rectification column

In this study a propane-propylene rectification column was investigated in terms of diameter of the column, number of trays, reflux ratio and the construction material costs of the column. During the calculations the reflux ratio was modified between 8 and 30. The chosen material of the column and trays was 1.4404 grade austenitic steel. The calculation has shown that with higher reflux ratio the diameter of the column and the number of trays were changing. Next, the necessary wall thickness of the shell of the column was determined with strength calculation. A material cost function was also determined with these parameters applying various reflux ratio values. From the results it can be concluded that the optimal reflux ratio is 12, because in this case the material cost function has a minimum point.

Fractional distillation of waste plastic pyrolysis oil for isolating narrow hydrocarbons cuts

Pyrolysis of polyolefins generates a large amount of olefins, which can serve as a valuable feedstock for the synthesis of chemicals. Nevertheless, their effective utilization requires refining owing to their diverse carbon distribution. This study performed a comprehensive GC×GC analysis of pyrolysis oils derived from waste polypropylene (PP) and waste high-density polyethylene (HDPE). The chemical composition of PP pyrolysis oil exhibited a high content of iso-olefins, whereas HDPE pyrolysis oil contained mainly alpha-olefins. Experimental batch distillation of PP pyrolysis oil yielded narrow hydrocarbon cuts with iso-olefins content exceeding 70 wt%. In contrast, distillation of HDPE resulted in cuts with more than 25 wt% alpha-olefins content. To perform ASPEN simulations, the physical properties (density, viscosity) of the oil were determined, two ways for obtaining boiling curves (ASTM D2887 and ASTM D86) were compared and two property methods (Peng-Robinson and Soave-Redlich-Kwong) were compared. It was concluded that the ASTM D2887 boiling curve and the Peng-Robinson property method present better experimental agreement for pyrolysis oils using the Theil’s Inequality Coefficients test. Based on the validated batch simulation, continuous distillation process schemes for isolating narrow carbon cuts in the refinery atmospheric tower indicate that a side draw configuration provides a better yield of (19.1 wt%) compared to a dedicated separate distillation column of (11.9 wt%) for the same number of trays, while the dedicated column allows the possibility to achieve higher purity.

Surgical instrument tray optimization process at a university hospital: A comprehensive overview

ObjectiveThis study presents the results of a surgical instrument tray optimization process implemented across all surgical specialties within the largest university hospital in Denmark. MethodsData was extracted from a comprehensive instrument optimization process including all Operating Rooms at Aarhus University Hospital. Adopting a holistic perspective, the optimization process, involved aligning instrument trays across various surgical specialties. This included: a) Reduction in number of instruments, b) Consolidation or separation of trays, c) Modularization - introducing modular trays for specific purposes, and d) Standardization - standardizing commonly used instruments across specialties. Instruments per tray, total number of instruments, and changes in the number of trays were compared against existing tray contents to identify discipline-specific changes. ResultsSome specialties made substantial alterations to tray structures, while others primarily reduced number of instruments in existing trays. Across all specialties, optimization resulted in 17 % decrease in number of tray types (p = 0.01, 95%CI:1.0–6.8), 1 % increase in total number of trays (p = 0.36, 95%CI:-11.9–4.8), 18 % decrease in number of instruments per tray (p = 0.0002, 95%CI: 3.2–7.6) and 16 % reduction in total number of instruments for all specialties (p < 0.0001, 95%CI:404–758). ConclusionThis study underscores complexity of instrument tray design. The approach employed at Aarhus University Hospital, involving interdisciplinary experts in an iterative design process, demonstrated the feasibility of redesigning instrument trays with significant reduction in content. Additionally, data suggests that reducing the number of instruments could lead to a decrease in workload within the Central Sterile Supply Specialty. This presents opportunity to minimize wasted resources and streamlining cleaning processes for unused instruments.

Evaluation of dimethyl carbonate production process from CO2 by rigorous simulation and detailed optimization

AbstractThe CO2‐derived dimethyl carbonate (DMC) synthesis process becomes greatly attentive but suffers high energy consumption in DMC distillation process. In this work, the DMC‐MeOH azeotropes separation process by pressure swing distillation and extractive distillation was compared, and key operating parameters, including the total number of trays and the feeding position of the mixture liquid, were optimized with the minimum total annual cost (TAC) as the objective function. On the basis of this optimization, economic evaluation of different distillation processes was conducted, and it was found that extractive distillation was more economical than pressure swing distillation. The application of the dividing‐wall distillation process upgraded by extractive distillation can significantly reduce the minimum annual total cost by 37.4% and 10.7% compared to the original pressure swing distillation and extractive distillation process, respectively. The optimization of relevant heat exchange network based on pinch technology resulted in energy consumption reduction by 27.2% and 25.9% for its hot and cold utilities, respectively. Carbon life cycle assessment (LCA) on the DMC distillation process revealed over 50% of energy as well as carbon emissions from steam consumption, whose reduction can significantly minimize CO2 emissions, energy consumption, and ultimate cost. © 2024 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Evaluation of the effects of various fan parameters on the cooking process in commercial cooking ovens

Commercial kitchen ovens are utilized in various capacities and models within commercial enterprises, operating on either electric or gas power. Numerous parameters affect the cooking process. Particularly, for effective cooking in an oven, it’s crucial to evenly distribute airflow over the food. Correct airflow significantly impacts the cooking process. Considering the differences in processing requirements based on the characteristics and quantity of the food (such as temperature, humidity, fan speed, duration, etc.), the method of heat transfer should be primarily assessed. Non-uniform distribution of hot air during the cooking process leads to varied cooking qualities among trays within the oven. Therefore, in achieving effective cooking, factors like oven cavity, number of trays, fan geometry, fan rotation speed, direction, movement intervals, and the turbulent airflow generated by the fan in the cooking chamber need thorough examination. This study analyzed simulation data evaluating the effects of different fan geometries, fan rotation directions, and timing on heat transfer in a prototype electric commercial cooking oven using gastronomic GN-1/1 sized with 10 trays. Additionally, comparison of test and design validation data in the specially developed prototype cooking oven was conducted. Assessments were made with different fan movements (fan diameters, rotation direction, speed etc.) and a fan protection plate in front of the oven to achieve more efficient heat distribution on the food. Depending on various fan parameters, this study contributed to reducing energy consumption in the prototype commercial cooking oven.

Morphophysiological comparison of seedlings of Solanum lycopersicum obtained with substrate in tray

The seedbed phase is decisive in the use of quality seedlings for transplanting. This research aimed to evaluate the differentiated vegetative response of tomato cultivars (Solanum lycopersicum L.) to two substrates under tray conditions. The experiment was carried out at the University of Pinar del Río, Cuba. The cultivars 'Celeste', 'Desquite', 'Grandioso' and 'Radiante' were used in a completely randomized design with factorial arrangement (factors: substrate and cultivar). The substrates were made from Fersialitic soil, organic materials (humus or peat) and rice husks. Sowing was carried out in trays with 40 alveoli (tubes), with a capacity for 70 g of substrate each. The substrates used guaranteed adequate morphophysiological development of tomato seedlings, regardless of the cultivar evaluated, although 'Desquite' presented the lowest absolute growth rate. With the use of the substrate based on soil, humus and rice husk, the number of seedlings useful for transplanting increased by 5%, which guarantees a reduction in the number of trays and volume of substrate used in this phase of crop.

Simulation and optimization of a liquified petroleum gas sweetening process using Aspen HYSYS

Liquefied petroleum gas (LPG) is one of the common fossil fuels that can be derived from natural gas or crude oil. In either case, it contains impurities such as H2S and CO2, which should be removed to obtain sweet liquified petroleum gas with a pure concentration of hydrocarbons such as ethane, propane, and butane. The most common method of gas sweetening process is by using amine compounds, which come in various types, each designed for specific and selective removal of acidic gases. In this study, methyldiethanolamine (42 wt.%) was used as a solvent to extract approximately 0.8% of H2S from sour LPG at a temperature of 400C. The objective of this study focuses on simulating and optimizing the LPG sweetening unit using Aspen HYSYS V11 to investigate the different parameters that affect the separation of acidic gases and to achieve high profitability. The number of trays, circulation rates, temperature, mass and molar flow rates, and other parameters were studied to reduce the H2S concentration to 0% in the treated LPG stream. The sweetening process was proposed to produce LPG with high levels of specific preferred specifications such as calorific value and purity, in addition to being environmentally friendly.

Effectivity Of Multi Tray Aerator As Pretreatment Process For Reverse Osmosis Membrane To Utilized As Raw Water At Sungai Itik Village

The community in Sungai Itik Village and its vicinity use river water for their daily needs, such as irrigation for agriculture, fish ponds, washing, bathing, and more. The quality of the river water has an iron (Fe) content of 2,64 mg/L, Total Dissolved Oxygen (TDS) of 347 mg/L, Dissolved Oxygen (DO) of 4,7 mg/L, a temperature of 29°C, and a pH of 5,4. The iron (Fe) content exceeds the standards set by PerMenKes No. 32 of 2017, requiring treatment using a multiple-tray aerator. This study aimed to determine the effective distance and number of trays in treating Sungai Itik's raw water, understand the coefficient of gas transfer (KLa) in the aeration process, and find the optimum aeration time. This study employed a multiple-tray aerator consisting of 5 trays with variations in the tray distances at 30 cm, 40 cm, 50 cm, and 60 cm. Three repetitions were performed for each treatment, both without gravel and with gravel. The results of this study showed that the best reduction in Fe content was achieved by the treatment with gravel at a tray distance of 60 cm using 5 trays, resulting in a 6,64% reduction in Fe from an average value of 1,51 mg/L to 1,41 mg/L. The average pH value was 6,19, and the TDS was 890 mg/L. The highest oxygen transfer rate (KLa) was obtained at a tray distance of 60 cm with gravel, averaging 0,2857/minute, and the optimum aeration time was 10 minutes.

Optimizing the CO2 capture and removal process to recover energy and CO2 from the flue gas of boilers and gas turbines outlet with considering the techno-economic analysis

This research aims to evaluate, simulate, and model the CO2 capture process for removing CO2 from the flue gas outlet flow of boilers and gas turbines. To the best of the knowledge Aspen HYSYS was employed to simulate these processes, enabling the analysis of technical conditions and evaluation of the problems and advantages associated with various designs from a technical perspective. Additionally, Aspen Capital Cost Estimator (ICARUS) was utilized for economic analysis.Initially, the CO2 capture process was examined for the removal of CO2 in the flue gas outlet flows of gas turbines and boilers. Subsequently, the process was simulated in the software to explore different optimal modes. Moreover, the feasibility of using a compressor, blower, ejector, and a combination of ejector and compressor was considered so as to provide the necessary pressure for absorption. Finally, the optimal design was selected, and more detailed studies were conducted on its absorption process, taking into account major variables. Among the important factors affecting absorption, were the number of trays, diameter, height, the amount of inlet gas and amine flow rate entering from the top of the tower, as well as the inlet gas pressure.

Sensitivity analysis of heat flow of heat exchangers in ethanol-water distillation column

In this study sensitivity analysis was made with Unisim Design process simulator software for ethanol-water mixture. The effect of the reflux ratio and the number of trays on the heat flow of the heat exchangers was investigated in case of different purification of bottom product. The results of the sensitivity analysis showed that the heat flow of the reboiler averagely 1.94 times higher than the heat flow of the condenser. Afterwards, the effect of the thermal state of the feed stream was investigated on the heat flow of the condenser and the reboiler. In each cases the mass flow and ethanol content of the distillate stream were also investigated. The results showed that in the studied cases the liquid volume percent of the ethanol varies between 65% and 87%. A simplified cost estimation was calculated with the determination of mass flow of cooling water and low-pressure steam. From the results it was concluded that higher number of trays, higher temperature of the feed stream and higher ethanol content in the bottom product resulted lower costs of the utility streams.

Effects of increased seeding density on seedling characteristics, mechanical transplantation quality, and yields of rice with crop straw boards for seedling cultivation

The high demand for labor during rice seedling cultivation and transplantation poses a major challenge in advancing machine-transplanted rice cultivation. This problem may be solved by increasing the seeding rate during seedling production while reducing the number of seedling trays. In this study, the commonly used combination of 150 g/tray with a 20-day seedling age in rice production was used as CK. Besides, some field experiments were conducted under seedling age conditions of 10 and 15 days from 2021 to 2022 to explore the effects of 250, 300, and 350 g/tray on the seedling quality, mechanical transplantation quality, yields, and economic benefits of rice. The cultivation of seedlings under a high seeding rate and short seedling age significantly affected seedling characteristics, but there was no significant difference in seedling vitality compared to CK. The minimum number of rice trays used in the experiment was observed in the treatment of 350-10, only 152-155 trays per hectare, resulting in a 62% reduction in the number of trays needed. By increasing the seeding rate of rice, missed holes during mechanical transplantation decreased by 2.8 to 4%. The highest yields and economic gains were achieved by the treatment of 300-15. These results indicated that using crop straw boards can reduce the application of seedling trays. On that basis, the yield of rice can be increased by increasing the seeding rate and shortening the seedling age of rice under the premise of ensuring seedling quality.

A two-step approach to create and evaluate an optimization method for surgical instrument trays to reduce their environmental impact

ObjectiveThis study combines Integer Linear Programming (ILP) and carbon footprint analysis based on the Life Cycle Assessment (LCA) method to reduce the carbon footprint of surgical instrument trays and their use. Materials and methodsA case study was carried out quantifying the instrument usage during the radical hysterectomy procedure. Using LCA we modelled the carbon footprint of the instrument trays, cradle to grave. The resulting carbon footprint data were used as input for an ILP model. The ILP model aims for an environmentally optimized composition of surgical instrument trays, without influencing patient safety, and optimizes composition based on different utilization rates. ResultsInstrument usage for the radical hysterectomy procedure was 54%. The LCA showed that with 99.5% of the total carbon footprint, the use phase in which the surgical trays are cleaned and sterilized is the biggest contributor. The ILP showed that for the radical hysterectomy procedure, an annual reduction in emission of 230 kgCO2-eq (46%) can be achieved by optimizing the trays. DiscussionThe results of this study show that the carbon footprint of surgical instrument trays is mainly impacted by the surgical tray size and number of used trays. Implementing the proposed method and environmentally optimizing surgical trays requires a multidisciplinary team, including surgeons, OR scrub nurses and those who have knowledge of LCA and ILP. ConclusionA combined method of ILP and LCA is suitable to provide insights on how to optimize surgical instrument trays with the objective to reduce the carbon footprint of these trays.

A Prospective Evaluation of Cost and Space Utilization Following Implementation of an Intelligent Delivery Platform for Forefoot Single-use Implants and Instrumentation in the ASC Setting

Category: Midfoot/Forefoot; Other Introduction/Purpose: The transition of the US healthcare system from a fee-for-service model to a value-based care model calls for a deeper evaluation of patient care in order to uphold quality and efficiency. Sterile-packed single-use instruments have been introduced as a tool to help facilities streamline operating room logistics and reduce sterilization needs and requirements thus reducing cost, time, and valuable shelf space. With the added intelligent delivery platform, procedure mapping (physician specific stocking of implants) and automatic restocking is now possible1-3. The purpose of this study was to examine the efficiencies of cost savings and reduction of shelf space required for storage of an intelligent delivery platform (Pulse Intelligent Delivery Platform, Stryker, Memphis, TN) with single-use surgery-ready forefoot implants. Methods: A total of 19 cases were performed during a 3-month period (August to November 2022) at a single ambulatory surgery center. Instrument tray reduction was tabulated and compared to the number of trays typically utilized using reusable instruments. Tray management time was evaluated clinically by direct observation. A cost analysis of reprocessed instrumentation trays was then performed looking at sterilization, surgical delay, and instrumentation costs per tray and then compared to pricing for the sterile instrument kits. The instrument, sterilization, and case delay costs/tray at the facility were calculated2. A comparison of space utilization was also performed between the two groups (reprocessed trays versus sterile kits). Results: There was a substantial decrease in the need for reusable instrument trays by 80%. 70% of cases did not require even one tray of reusable instruments to be opened. The delivery platform was shown to lower instrument tray cost per case by 74.25%. Space was also evaluated, and the sterile kits were found to have an 85.9% reduction in space when compared to the reprocessed trays2,3. Conclusion: A forefoot single-use surgery ready intelligent delivery platform has been shown to effectively lower overall instrument tray cost per case by 74.25% in a highly efficient ASC. In addition, an 85.9% reduction in shelf space per tray was also seen comparing reprocessed instrumentation to sterile instrument kits. Pricing is variable per facility, and sterilization and usage processes vary1-6. However, we believe that sterile kits can be more cost effective than reprocessed sets. In addition, space can be saved with the use of sterile instrument kits adding to the established benefits of the delivery platform of procedure mapping and automatic restocking1-3.

Effect of clear aligner attachment design on extrusion of maxillary lateral incisors: A multicenter, single-blind randomized clinical trial

Extrusion of maxillary lateral incisors during aligner treatment is a difficult movement to achieve accurately. Despite recommendations regarding attachment design, few studies and no prospective trials compare predictability among attachments. This study aimed to compare the efficacy between optimized and horizontal attachment designs for achieving maxillary lateral incisor extrusion during clear aligner treatment. The study included maxillary lateral incisors in 3 orthodontic practices requiring at least 0.3 mm of extrusion during the first series of 20-25 aligners in patients aged ≥16 years who were scheduled to begin clear aligner treatment (Invisalign; Align Technology, San Jose, Calif). Teeth were randomly assigned to receive optimized (O), rectangular horizontal nonbeveled (H), rectangular horizontal incisally-beveled (HIB), or rectangular horizontal gingivally-beveled (HGB) attachments. After the first series, a blinded evaluator measured extrusion using superimpositions with initial and predicted models. Linear models determined the difference in the predicted extrusion percentage achieved on the basis of attachment design. Other covariates were patient age, sex, number of trays, and self-reported compliance. Forty patients (74teeth) were enrolled, and 38 patients (71 teeth) completed the study. Intraexaminer and interexaminer reliability for extrusion measurements was high (intraclass correlation coefficient, 0.985 and 0.991, respectively). The achieved extrusion was significantly less than predicted (mean, 73%; P<0.0001). The average achieved extrusion was 62%, 79%, 78%, and 78% for O, H, HIB, and HGB attachments, respectively, with H significantly more effective than O (P= 0.0403). Horizontal attachments (H, HIB, and HGB combined) were significantly more effective than O attachments (P= 0.0060), with an average difference in achieved extrusion of 14% of the predicted amount (95% confidence interval, 4-23; estimated 76% vs 62%). Horizontal attachments were an estimated 22% more effective than O attachments for extruding maxillary lateral incisors. Horizontal attachments are more effective than O attachments for predicted maxillary lateral incisor extrusion between 0.3 and 2.5 mm. The 3 horizontal attachment designs evaluated performed similarly for achieving predicted extrusion. This randomized clinical trial was registered and reported at clinicaltrials.gov (NCT04968353). The protocol was not published before trial commencement. This study was funded in part by the Alexander Fellowship of the Virginia Commonwealth University School of Dentistry, the Southern Association of Orthodontists, and the Virginia Orthodontic Education and Research Foundation. No funding source influenced the study design, the collection, analysis or interpretation of data, writing of the report, or the decision to submit the article for publication.

Extractive-dividing-wall column and multi-objective optimizations of green entrainer-based ultra-high-purity recovery of methyl di glycol and N-Methyl-2-Pyrrolidone

The waste solvent is frequently generated from the processes that highly rely on solvents. Diethylene glycol monomethyl ether or methyl di glycols (MDG) and N-methyl-2-pyrrolidone (NMP) are representative valuable solvents used broadly and removed as waste solvents during the semiconductor material manufacturing processes. Although waste solvent can be practically retrieved by distillation, azeotropic waste solvent mixture only can be recovered by advanced distillation process. In this study, optimal extractive distillation and extractive-dividing wall column are used to recover waste solvent. The process is optimized by multi-objective optimization using genetic algorithm by linking Aspen Plus® and MATLAB. All optimal cases are compared in terms of energy, exergy, economic and environmental parameter. As a result, the potential energy, total annual cost saving and exergy efficiency for extractive dividing wall column are 26.29%, 24.15% and 21.02%, respectively. Exergy loss that is associated with the number of trays can be significantly reduced by optimization while exergy loss that is associated with remixing only can be significantly reduced by dividing-wall column. Further, multi-objective optimization using a genetic algorithm and a range of population provides various results that determine process selection.

Glycol losses calculation in a gas dehydration unit

The gas dehydration process separates gas from water content by mixing absorbents such as glycol in the gas dehydration unit. The gas dehydration process can use triethylene glycol type glycol, reducing the water content to a minimum of 7 lb/mmscfd. In the dehydration process, glycol losses will usually occur either in the reboiler or contactor; for this reason, this study aims to determine the causes of glycol losses, calculate the water content absorbed in the contactor, determine the percentage of glycol losses and calculate how much glycol is needed in each 1mmscfd of gas. Glycol losses are classified into two types: expected and up-standard. In this case, the research method starts by calculating the amount of water content that can be absorbed, the percentage of glycol losses, and the amount of glycol volume required in every one mmscfd of gas. Causes of glycol losses include the number of trays, contact time, absorption surface area, flow rate, and temperature in the reboiler. Of the 60.96 mmscfd of wet gas that entered the contactor, it was found that 32.11 lb/mmscfd of water managed to absorb glycol. Based on the calculation of glycol losses in some test data, the average glycol losses (0.087 gal/mmscf) are still categorized as ordinary losses because the glycol losses that occur do not exceed the safe limit set by the industry, which is 0.01 – 0.15 gal /mmscf. One way to reduce the occurrence of glycol losses is to adjust the pump discharge to the incoming gas flow so that excess glycol is not used when there is contact between glycol and wet gas.

An efficient and random synthesis method for mass exchange networks with multi-component using a node-based vertical non-structural model

Mass exchange network (MEN) synthesis is an important technique to ensure efficient purification of industrial waste gas sources and water streams. However, most existing models for MEN synthesis are not capable of dealing with multi-component problems and achieving optimal designs. In this study, an innovative process integration strategy based on a node-based vertical non-structural model (NV-NSM) is proposed. The developed strategy allows for a more random representation of process configuration and aids in handling both single- and multi-component problems. The NV-NSM arranges several groups of main nodes in the process streams and the sub-nodes in their branches and results in design configurations by connecting any two sub-nodes on the rich and lean streams at the same main node number. When dealing with multi-component synthesis, the number of tray column is directly optimized to balance the mass transfer needs of different components. As part of the current investigation, the random walk algorithm with compulsive evolution (RWCE) is established to realize the simultaneous optimization of multiple variables, including the mass transfer loads, the number of trays, the stream split ratios, and the flowrates of lean streams. Furthermore, the fine-search strategy based on the RWCE is applied to improve global and local optimization performance. Finally, the proposed method is applied to four MEN cases featuring different exchanger specifications and considering both single and multiple components. The implementation and analysis result in more optimal solutions compared to those published in the literature, demonstrating the feasibility and effectiveness of the proposed method in analyzing and evaluating different MEN problems, including multi-component ones.

Operating room efficiency after the implementation of MAKO robotic-assisted total knee arthroplasty.

The aim of this study was to examine if robotic-assisted total knee arthroplasty (RATKA) is cost- and time-effective in terms of implant stock and perioperative parameters, as optimizing perioperative efficiency may contribute to value-based care. Four hundred thirty-two consecutive patients who received primary total knee arthroplasties (TKAs) from May 2017 to March 2020 in a regional hospital were included in this study. Operating room time (OR time), surgical time, number of trays, insert thickness, and length of stay (LOS) were assessed and compared for a cohort group with navigation-assisted procedures to a group with robotic-assisted procedures (MAKO, Stryker, USA). Prediction of implant size was assessed for the robotic-assisted group. The Mann-Whitney U test was used for comparisons between groups when the normality assumption was not met. Categorical variables were assessed using the Fisher's exact test. p < 0.05 was considered statistically significant. In the RATKA group, we noticed a significant mean reduction of 11min in total OR time (p < 0.001), the use of thinner insert (p < 0.001), and a shorter mean length of stay of 1day (p < 0.001). Compared to the navigation group, surgical time was not significantly longer, nor clinically relevant (0.238). In 76.9% of the robotic-assisted cases, the estimated implant size was equal to the final size and in all other cases, the preoperative implant size was oversized. The introduction of the MAKO robotic-assisted total knee arthroplasty resulted in a gain in operating room time, a thinner and more predictable insert thickness, a shorter length of stay in hospital, and less instrumentation compared to navigation-assisted procedures. Level of evidence Level III, Retrospective cohort study.

Effect of Dolomite Addition on The Performance of Palm Oil Mill Fly Ash for Methylene Blue Adsorption

The use of palm oil mill fly ash (FA) as a low-cost adsorbent is one of the solutions for handling FA waste. In this study, the addition of dolomite is expected to improve the adsorbent performance. The aim of this study was to investigate the optimum FA-dolomite adsorbent composition and operating conditions for methylene blue adsorption. Different parameters were studied to optimize adsorption process such as the amount of dolomite, methylene blue flow rate, bed height and number of trays. FA-dolomite was converted into nano-adsorbent by sol-gel method which was coated on zeolite surface. Nano-adsorbents were characterized by XRF, FTIR, XRD and SEM. The adsorption capacity was tested by Spectrophotometer UV-Vis. XRF characterization showed that FA had the highest SiO2 content of 58.15%, while dolomite contained CaO of 52.72%. FTIR characterization detected the groups of Si-O-Si, Si-O-Al, Ca-O and Si-O. XRD characterization showed the average crystalline size of FA-dolomite 2% adsorbent was 28.56 nm and SEM characterization showed fine pores on the adsorbent surface. The highest adsorption efficiency obtained at FA-dolomite 2% was 97.364% and the lowest obtained at FA-dolomite 8% was 13.16% with a flow rate of 500 ml/h, adsorbent height of 9 cm and 3 trays. The greater the amount of dolomite added, the absorption efficiency decreases.

An efficient two-step optimization method for mass exchanger network synthesis

Mass exchanger networks have been considered a promising solution for reducing impurity in streams and maximizing energy recovery in the chemical industry. This paper adjusts two non-structural models with distinct optimization variables and a heuristic algorithm according to the MEN synthesis characteristics. Considering the requirement of the objective function, a two-step optimization method that combines these two models is proposed. In the first step, a feasible solution is determined by the model using the transferred mass as an optimization variable. In the second step, the aforementioned model is employed to maximize tray utilization by adopting the tray number as an optimization variable. The results of the two cases obtained by the proposed method are 406,330 $/yr and 329,326 $/yr, which are lower than the published results, and is verified on two cases regarding quality and efficiency.