Category Archives: Chemical Engineering & Technology

Influence of Particles on the Roller Discharge of Thin‐Film Filtration without Gas Throughput

Posted on 20 September 2023 by nVolker Bächle, nMarco Gleiß, nHermann Nirschln

The impact of a particle system on the roller discharge is investigated comparing the behavior of the inorganic white pigment titanium dioxide and the biological model organism yeast. The quality of the removal properties of the filter cakes on a laboratory drum filter is recorded. Five different track-etched membranes are used to assess the filter properties with varying particle-pore size ratios.

Abstract

If fine and compressible particle systems need to be separated, the ground layer compaction caused by the compacting of the filter cake leads to high flow resistances. Thin-film filtration is a suitable method to avoid the limiting effect of the filter cakes. Gas-impermeable filter membranes prevent shrinkage cracking, which can occur during demoisturing of the filter cakes. Titanium dioxide and baker's yeast are used as model particle systems, which are present in different concentrations and are filtered with track-etched membranes in different particle-to-pore size ratios. The parameters determined during the investigation are the residual moisture, the specific solid mass, and the completeness of the discharge. Filtration causes progressive blocking of the membrane pores, resulting in filter medium resistances that are increased by up to a factor of 175. Metabolism of yeast can cause bubbles to accumulate on the membrane and decreasing the free filter area. Without regeneration the specific solid mass flow rate is reduced by 61 % for titanium dioxide and by 13 % for yeast under ideal conditions of this experimental study.

Fuel Property Enhancement of Jatropha Biodiesel by Blending with Nanoparticles

Posted on 19 September 2023 by nAjeet Kumar Prajapati, nYogendra Yadawa, nDeepak Dwivedi, nRakesh Kumarn

Nanoparticles are utilized as additives to enhance the fuel properties of biodiesel. The application of Mg-ZnO as a promising fuel property enhancer is highlighted and the protocol for its synthesis is provided. The fuel property enhancement of biodiesel in terms of fuel density, oxidation stability, and dynamic viscosity by Mg-ZnO is compared with other nanoparticles such as ZnO, SiO₂, and TiO₂.

Abstract

The direct application of Jatropha biodiesel in engines is harmful because of the corrosivity of biodiesel, the emission of poisonous gases, and solid particulate matter. Therefore, it is of paramount important to enhance the biodiesel fuel properties via green routes to effectively utilize it for automotive applications. The synthesis and application of different nanoparticles (NPs) such as ZnO, Mg-ZnO, TiO₂, and SiO₂, as fuel property enhancers for Jatropha biodiesel were investigated. The calorific value, oxidation stability, dynamic viscosity etc. were studied for the NP-blended biodiesels and compared with the traditional biodiesel (B100). Mg-ZnO was found to be a promising candidate as fuel property enhancer for biodiesels.

Adaptive Data‐Driven Modeling Strategy Based on Feature Selection for an Industrial Natural Gas Sweetening Process

Posted on 18 September 2023 by

A machine learning-based modeling approach is proposed that integrates an adaptive immune genetic algorithm with random forest to intelligently select process features as input variables for natural gas sweetening process modeling. This model can adaptively execute physical feature selection and possesses the advantages of strong predictive performance and tolerance to outliers and noise.

Abstract

As the core process of natural gas purification plant, natural gas sweetening directly affects the production efficiency and product quality of the purification plant. However, process modeling based on sulfur content prediction presents challenges in adaptability and accuracy. To tackle this, a machine learning-based modeling approach is proposed that integrates an adaptive immune genetic algorithm with random forest (RF) to intelligently select process features as input variables for RF modeling. The industrial result indicates that the proposed method is able to remove interfering variables and adaptively achieve optimal model precision for different scenarios. It offers a novel research instrument for product quality monitoring in natural gas sweetening plants.

Bubble Interfacial Area in a Swirling Contactor: Experiments and Computational Fluid Dynamics Simulations

Posted on 15 September 2023 by nXiao Xu, nChunkai Gong, nShuo Wang, nQiang Yang, nZhenhao Xin

Swirling flows can be applied for gas-liquid mass transfer process intensification. Experiments and simulations were conducted to investigate the bubble size, gas holdup, and interfacial area in a swirling contactor which was divided into twelve subregions. Bubble breakup and coalescence processes between all bubble size classes were considered using appropriate models.

Abstract

The bubble size, gas holdup, and interfacial area in a swirling contactor were investigated through experiments and simulations. The interfacial area was obtained for liquids and gases with Reynolds numbers Re _l and Re _g, respectively. The contactor was divided into twelve subregions. Re _l was negatively related to bubble size, gas holdup, and interfacial area, whereas Re _g was positively associated. The maximum bubble interfacial area for the entire swirling contactor was 196.3 m⁻¹ with a gas-liquid ratio of 0.022. There is a trade-off between centrifugal acceleration and bubble size for interfacial area.

Design and Simulation of a Low‐Temperature Thermal Desalination System

Posted on 13 September 2023 by nArnab Karmakar, nAbhishek Kumar Patra, nSankarsan Saha, nSumit Kumar Janan

A low-temperature thermal desalination system based on the spray-assisted vacuum flash operation was designed with the passive heating of saline water and effective condensation of water vapor. The flash drum was designed effectively by simulation of the droplet dynamics. A corrugated plate heat exchanger and a thermosyphon solar water heater were designed to optimize the system.

Abstract

The prototype of a low-temperature thermal desalination system treating 2500 L day⁻¹ of saline water was designed thermally and geometrically, to be integrated with a vacuum spray flash drum and spray nozzles, a plate heat exchanger-type condenser, and a thermosyphon solar water heater to produce potable water for a small community. The design bases were the feed flow rate, the feed temperature from 45 to 65 °C, the salinity of 0.035 kg kg⁻¹, and the vacuum drum pressure from 2 to 6 kPa absolute. The estimated yield of potable water based on the simulated droplet dynamics was in the range of 68.91–75.80 %. The plate heat exchanger and the thermosyphon solar water heater were designed for effective condensation and passive heating, respectively.

High‐Intensity Microwave‐Assisted Pyrolysis Liquid Subjected to Supercritical Fluid Extraction with Carbon Dioxide (Case Study: Bio‐phenol)

Posted on 12 September 2023 by

Extraction with supercritical carbon dioxide (scCO₂) was studied for separating value-added chemicals from crude bio-oil produced by pyrolysis of oil palm shell. Organic acids were the dominant group of chemicals enriched by scCO₂ extraction. Phenol was considered as a specific value-added chemical for estimating the production costs, which were compared with the price of a commercial-grade product.

Abstract

A crude bio-oil from high-intensity microwave-assisted pyrolysis of oil palm shell was subjected to an attractive, environmentally friendly separation process, namely supercritical fluid extraction with carbon dioxide (scCO₂), to study the value-added chemicals such as bio-phenol. The operating parameters temperature and pressure were examined above the critical point of carbon dioxide. The yield of scCO₂-oil extract tended to increase significantly with these two parameters according to one-way ANOVA. The extract yield was within 63.09–67.72 %. The scCO₂-oils were characterized for value-added chemical components by GC-MS and compared with the crude bio-oil. Acids, as the dominant group of chemicals, were enriched by scCO₂, and included dodecanoic acid, n-hexadecanoic acid, and octadecanoic acid. The thermal behavior of scCO₂-oil was studied by thermogravimetry. The production cost of bio-phenol extracted from scCO₂-oil was estimated and compared with a commercial phenol product.

Iron‐Based Nanoparticles Oxygen Scavenger for Suppressing Heat‐Stable Salts Formation in Amine

Posted on 8 September 2023 by

The correlation of physicochemical properties of iron-based nanoparticles with their activity in oxygen-scavenging was developed. The addition of a 20 %Fe/HZSM5 oxygen scavenger to methyl diethanolamine (MDEA) did not jeopardize the CO₂ absorption performance but inhibited the MDEA degradation. The absence of the degraded products prevented the formation of heat-stable salts that cause foaming issues.

Abstract

Heat-stable salts (HSS), which trigger excessing foaming in absorber, are formed when protonated methyl diethanolamine (MDEA) reacts with the more acidic degraded products in the presence of dissolved oxygen (DO). The aim is to suppress the HSS formation in MDEA solution inaugurally employing a hybrid iron-based nanoparticles (HINP) oxygen scavenger. It was discovered that the oxygen-scavenging performance of a more cost-effective 20 %Fe/HZSM5 was one-fold higher than the 20 %Fe/MCM-41. The former was verified for its superior structural properties. The Fe²⁺ on its surface first reacted with DO, preventing DO from oxidizing the MDEA. Consequently, the absence of hydroxyl radicals eliminated the potential of formic acid formation, hence suppressing the MDEA-acid HSS formation.

Optimization of Biodiesel Production from Waste Cooking Oil Using Nano Calcium Oxide Catalyst

Posted on 7 September 2023 by nAghareed M. Tayeb, nShereen M. S. Abdel-Hamid, nRanda M. Osman, nSabah Mohamed Faroukn

Biodiesel is an alternative to fossil diesel fuel derived from sustainable biological resources. Biodiesel production from waste cooking oil and methanol in the presence of a nanosized CaO catalyst was studied. Transesterification was performed at different times, temperatures, and methanol/oil ratios, and response surface methodology was used to predict optimum parameters for biodiesel production.

Abstract

The use of nano calcium oxide as a catalyst in biodiesel production has gained attention due to its high catalytic activity, low cost, and environmental friendliness. It efficiently converts triglycerides to fatty acids and methyl esters. In the present study, nano CaO was prepared by precipitation and characterized by various techniques. The results showed that the nano CaO has high purity, nanoscale crystal size, good thermal stability, and high specific surface area. Biodiesel was produced by transesterification from waste cooking oil, methanol, and the nano catalyst. Response surface methodology was applied to predict the optimum parameters for the production of the biodiesel based on its yield. The produced biodiesel was characterized by FTIR spectroscopy and GC-MS and evaluated according to ASTM D6571.

Theoretical Analysis of Metals Supported on Tungsten Oxide Nanowires (W18O49) for Water Dissociation Reaction

Posted on 7 September 2023 by

Applying the density functional theory method, W₁₈O₄₉ was developed for catalyst support on Pt, Pd, Ni, Ir, Ag, and Rh metal atoms for the oxygen evolution reaction. Various adsorbates that are intermediate products in this reaction were tested for adsorption on metal catalysts. Gibbs free energy diagrams were also developed to analyze the potential of the catalyst and W₁₈O₄₉.

Abstract

Pt is the cause of the high total cost of fuel cells and electrolyzers, leading to difficult commercialization. Here, various types of metal atoms, i.e., Pt, Pd, Ni, Ir, Ag, and Rh, suitable for catalysts are used and supported by W₁₈O₄₉ nanowires for oxygen evolution reaction (OER) by the density functional theory (DFT) method. Four adsorbate molecules involved in OER were tested on adsorption energy: OH, O, OOH, and OO. Although the adsorption energy of these adsorbate molecules indicates that W₁₈O₄₉ has low adsorption energy, the Gibbs free energy diagram demonstrates that W₁₈O₄₉ has high OER reaction energy. Pt, Pd, Ni, and Rh have the lowest Gibbs energy to initiate the reaction and reasonable Gibbs free energy for other OER reactions. Bimetallic or trimetallic active sites can be developed along with selecting other metals with Pt, Pd, Rh, and Ni to reduce the Gibbs free energy difference for the decomposition of OH to O and OOH to H₂O. Ag metal can also be applied as a second or third metal because Ag exhibits a relatively low Gibbs free energy difference in the O to OOH step. A selectivity study of each step on bimetallic and trimetallic active sites needs to be performed.

Food Waste Gasification to Produce Hydrogen for Proton Exchange Membrane Fuel Cell Applications: Comparison of Fixed‐Bed and Fluidized‐Bed Gasifiers Models

Posted on 4 September 2023 by nYounes Alouani, nDennoun Saifaoui, nMohamed-Amine Alouani, nAbdelkader Alouanin

The potential of biomass gasification, specifically food waste, as a solution for increasing energy demands and sustainable waste management is evaluated. The process of converting waste into syngas and subsequently purifying the hydrogen for use in proton exchange membrane fuel cells is described. The unique advantages and drawbacks of fixed and fluidized-bed gasifiers are highlighted.

Abstract

The proton exchange membrane fuel cell (PEMFC) has been expected to play a pivotal role in energy corridors within the next few years. The gasification of biomass sources is used to produce hydrogen. Many researchers have simulated the biomass gasification model through Aspen Plus to generate hydrogen. However, they have not been targeting the purification of hydrogen gas which is the product of biomass gasification. Thus, the Aspen gasification models for both the fixed and fluidized-bed gasifiers integrated with the hydrogen purification system to produce hydrogen for PEMFC applications are developed in this work. Food waste is selected as biomass feedstock. The gasifiers have been modeled on Gibbs free minimization energy. Shift reactors along with the preferential oxidation reactor have been employed to limit the amount of CO in the syngas. The validated models were then employed to estimate the performance of both the fixed-bed food waste gasifier and fluidized-bed food waste gasifier in terms of syngas produced and hydrogen obtained after purification.