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CRYSTAL-GROWTH RATE MODELS AND SIMILARITY OF POPULATION BALANCES FOR SIZE-DEPENDENT GROWTH-RATE AND FOR CONSTANT GROWTH-RATE DISPERSION

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chemical engineering SCIENCE 1993年第8期48卷 1475-1485页

作者： ROJKOWSKI, ZH Warsaw University of Technology Faculty of Chemical and Process Engineering Warynskiego St. 1 PL-00-645 Warsaw Poland

It is shown that the population balance in a mixed suspension mixed product removal crystallizer (MSMPRC), for the case of constant (initial) crystal growth rate dispersion mechanism, can be transformed into a form similar to that valid for the size-dependent growth rate mechanism. This allows one to interpret the experimental crystal size distribution data resulting from the dispersion in terms of size-dependent mean growth rate. An example of fitting several empirical models of constant growth rate dispersion and of size-dependent growth rate to series of experimental data for aluminum ammonium alum crystallizing from its water solution in the MSMPRC is presented and discussed.

关键词： Crystal growth

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Effect of fermentation parameters on the lactic acid production from oil palm empty fruit bunch

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AIP Conference Proceedings 2025年第1期3266卷

作者： Wan Nurul Huda Wan Zainal Siew Lee Lily Lau Nur Shaizatul Akma Mazlan Navin Raj Niam Faculty of Chemical and Process Engineering Technology Universiti Malaysia Pahang Al-Sultan Abdullah Lebuh Persiaran Tun Khalil Yaakob 26300 Kuantan Pahang Malaysia

Fermentation parameters play a crucial role in influencing the growth of microorganism during the fermentation process and affect the productivity. The effects of initial pHs of the medium (4, 6 and 8) and fermentation temperatures (30 °C, 34 °C, and 38 °C) on the lactic acid production from oil palm empty fruit bunch (OPEFB) using Lactobacillus delbruekii subsp. lactis were investigated in this study. The oil palm empty fruit bunch was hydrolysed with different acids prior to fermentation. The results indicate that concentrations of lactic acid produced were increased with the increasing of initial pH medium and fermentation temperature. The maximum concentration of lactic acid was 36.59 g/L obtained after 48 h of fermentation time at initial pH medium of 8 and temperature of 38 °C. The results of the work show that selection of fermentation parameters is crucial because it can increase product yield and productivity.

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GAS ENTRAINMENT BY PLUNGING LIQUID JETS

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chemical engineering SCIENCE 1993年第21期48卷 3585-3630页

作者： BIN, AK Faculty of Chemical and Process Engineering Warsaw University of Technology ul. Waryńskiego 1 00-645 Warszawa Poland

In this paper an extensive survey of the results of possibly all available experimental and theoretical studies on gas entrainment by plunging liquid jets has been presented. The following aspects of the phenomenon are thoroughly discussed: mechanisms, conditions of the onset of entrainment, amount of the entrained gas, characteristics of the resulting bubble dispersion (bubble size, depth of bubble penetration, gas holdup and bubble residence time) and mass transfer. Wherever possible, empirical correlations enabling estimation of the relevant quantities characterizing the entrainment phenomenon studied are given or recommended. Practical applications of the plunging jet aerator in waste treatment, fermentation and in the flotation industry are reviewed and its aeration (e.g. oxygenation) performance is compared with conventional aeration systems.

关键词： Air entrainment

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process efficiency enhancement of single mixed refrigerant LNG process

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AIP Conference Proceedings 2025年第1期3266卷

作者： Nazreen Begum Najibullah Khan Dhiviya Tinakaran Faculty of Chemical & Process Engineering Technology Universiti Malaysia Pahang Al-Sultan Abdullah Lebuh Persiaran Tun Khalil Yaakob 26300 Gambang Pahang Malaysia

Liquefied Natural Gas (LNG) processing is as an energy and cost-intensive process due to the large energy consumption required to liquify the gas. The objective of this study is to enhance the process efficiency of a Single Mixed Refrigerant (SMR) LNG process for a small-scale LNG train with a capacity of 1-2 million tonnes per annum (MTPA). The process efficiency is enhanced by determining the optimal combination of mixed refrigerant composition such as nitrogen, methane, ethane, propane and butane that will minimise the overall energy consumption. The SMR LNG process is modelled and simulated using Aspen Plus. The process efficiency is evaluated using two parameters which are specific power (SP) and coefficient of performance (COP). By enhancing the mixed refrigerant composition of SMR process the results indicate that the specific power (SP) is improved from 0.225 kWh/kg to 0.218 kWh/kg (i.e. improvement about 3.3%). Meanwhile, the coefficient of performance (COP) is improved to 4.22 which indicate about 5% improvement in term of process efficiency enhancement.

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Comparison of different cooling strategies in achieving desired crystal size distribution for seeded potash alum crystallization process

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AIP Conference Proceedings 2025年第1期3266卷

作者： Siti Zubaidah Adnan Noor Asma Fazli Abdul Samad Faculty of Chemical and Process Engineering Technology Universiti Malaysia Pahang Al-Sultan Abdullah Lebuh Persiaran Tun Khalil Yaakob 26300 Kuantan Pahang Malaysia

Crystallization process is governed by nucleation, growth and dissolution mechanisms that are supersaturation dependent. It is thus crucial for the cooling strategy to be capable of controlling these mechanisms. However, to properly control these mechanisms through one cooling strategy is a challenge as increasing supersaturation would increase both nucleation and growth rates, while reducing supersaturation may increase dissolution and nucleation rates. This would contribute to the problem of achieving crystal size distribution (CSD) with significant fines. The trade-off between these rates needs to be balanced and employing several cooling strategies to compare which strategy works well with the selected crystallization process is recommended. This paper aims to provide a performance comparison in terms of CSD for two established cooling strategies labelled I and II, against new strategy III in achieving large sized crystals with less fines for seeded potash alum crystallization process. Strategy I is linear cooling policy, strategy II is for maximizing CSD, and strategy III is for minimizing supersaturation. This comparison study is established by simulation via MATLAB software. Based on the simulation results, strategy I delivers the smallest size of CSD with high fines or small-sized crystals, while strategy II provides large CSD but with significant number of fines. Strategy III gave smaller size of grown seed crystals compared to strategy II but with insignificant fines. Overall, strategy III is considered the best trade-off strategy for seeded potash alum crystallization process in producing large size of crystals with the lowest number of fines.

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Bayesian network analysis of pilot plant keratin production from chicken feathers

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AIP Conference Proceedings 2025年第1期3266卷

作者： Vinhur Lim Mao Some Nurul Syahirah Syahril Muhammad Asyraf Rusli Nurul Sa’aadah Sulaiman Faculty of Chemical and Process Engineering Technology Universiti Malaysia Pahang Al-Sultan Abdullah Lebuhraya Tun Khalil Yaacob 26300 Gambang Kuantan Pahang Malaysia

The uncontrolled disposal of feathers from the poultry industry poses a significant environmental challenge. To address this issue, a pilot plant at Universiti Malaysia Pahang has been developed to recycle chicken feathers for keratin production. However, the uncertainty surrounding the keratin production process in the pilot plant has not been assessed. This study aims to investigate the likelihood of process parameters affecting keratin production quality using a Bayesian Network model. The model, constructed using probability distribution and theory, predicts outcomes based on causal relationships between nodes. GeNIe Modeler software is used to develop the model, with expert opinions informing the conditional probability tables (CPTs). Prediction, diagnosis, and sensitivity analyses are conducted to evaluate the model’s outcomes. Parameters such as temperature, solvent-to-material ratio, concentration of sodium hydroxide (NaOH), and rotational speed are identified as factors influencing keratin production. Additionally, each stage of the process can impact the quality of the keratin product. Results indicate that the model successfully predicts a 96% likelihood of good keratin production quality by identifying critical process parameters. Furthermore, the model can predict keratin production quality based on updated evidence.

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Predicting energy production of integrated torrefaction and combustion in a biomass power plant

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AIP Conference Proceedings 2025年第1期3266卷

作者： Siti Nurazlin Khalil Ruwaida Abdul Rasid Mazni Ismail Noorlisa Harun Wan Hanisah W. Ibrahim Faculty of Chemical and Process Engineering Technology Universiti Malaysia Pahang al-Sultan Abdullah Lebuh Persiaran Tun Khalil Yaakob 26300 Kuantan Pahang Malaysia

Biomass combustion is widely used in energy generation, especially in power plants, and Malaysia’s abundant palm oil waste provides a promising resource for energy production. Additionally, there is a continuous increase in energy demand due to rising living standards and population growth. However, the moisture content in palm oil waste hinders power generation efficiency. To tackle this challenge, implementing a torrefaction process offers a viable solution to effectively reduce moisture content and enhance power generation efficiency. This study revolves around the simulation of biomass combustion in Aspen Plus software, aiming to increase power generation efficiency through the integration of torrefaction. A base case (Case 1) was developed and validated with data from FTJ Biopower Sdn. Bhd. (FTJ) power plant. A comparison was drawn across various cases, out of which, conventional torrefaction with inert nitrogen (Case 2) and oxidative torrefaction with air (Case 3) showed a slight enhancement in power production compared to the others. However, Case 4 whereby combustion with integrated conventional torrefaction with recycle holds potential for cost-saving due to the recycling of produced gas in the process. This study provides a comprehensive evaluation for the integration of torrefaction in power generation process, and it proves the potential of torrefaction as a promising pretreatment for thermal conversion of biomass waste. This information can be beneficial to understand and optimize the overall power generation process for exploring possible integration of torrefaction in existing facilities without the need for laborious, high-cost, and time-consuming experimental investigation.

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Dispersant-based ionic liquids for petroleum pipeline

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AIP Conference Proceedings 2025年第1期3266卷

作者： Ezuan Hakeem Abdul Tahir Mohamad Ikram Mohamad Nuraishah Jasmin Ahmad Musfareza Syamsul B. Abdullah Faculty of Chemical and Process Engineering Technology Universiti Malaysia Pahang Al-Sultan Abdullah Lebuh Persiaran Tun Khalil Yaakob 26300 Kuantan Pahang Malaysia

Petroleum exploration focuses mainly on searching for petroleum, classified as hydrocarbon compounds. As soon as the pipeline is switched off, the viscous petroleum will begin to cool and lose its fluidity, transforming into a gel that is difficult to restart. Pre-treatment of oil with a dispersant is a method for modifying the rheological characteristics of gelled waxy petroleum to improve transport. The current project is to overcome this problem where obstruction is a regular occurrence in upstream or downstream petroleum pipelines. This project aims to test the performance of two types of ionic liquids (ILs), namely hydrophobic ILs and hydrophilic ILs. The study concludes that hydrophilic ILs optimally effect paraffin wax in petroleum pipelines.

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process synthesis with simultaneous consideration of inherent safety-inherent risk footprint

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Frontiers of chemical Science and engineering 2018年第4期12卷 745-762页

作者： Andreja Nemet Jiri J.Kleme Zdravko Kravanja Faculty of Chemistry and Chemical Engineering University of Maribor2000 MariborSlovenia Sustainable Process Integration Laboratory NETME CentreFaculty of Mechanical EngineeringBmo University of Technology61669 Brno Czech Republic

process plants should be designed to be economically viable and environmentally friendly, while also being operable and maintainable during process implementation. The safety of processes is among the most important considerations in obtaining results that are more acceptably realistic, as it is linked to the availability and reliability of the process. Inherent safety can effectively be enhanced in the early stages of the design, when the main decisions on process design are made. The aim of this study is to enhance and select the appropriate risk assessment method and to incorporate it into process synthesis, using a mathematical programming approach. A mixed-integer, nonlinear programming (MINLP) model was used for the synthesis of a methanol production process, considering risk assessment during the synthesis. Risk assessment is performed simultaneously with the MINLP process synthesis, where the risk is determined either for the whole process as overall risk, or on a per unitof- a-product basis. For the latter, a new measurement is proposed: the inherent risk footprint. The results of a case study led to two main conclusions: (i) Significantly safer designs can be obtained at negligible economic expense, and (ii) at higher production capacities, a lower inherent risk footprint can be achieved. The results also indicate that designs obtained using this method can have significantly increased inherent safety, while remaining economically viable.

关键词： inherent safety process design simultaneous risk assessment risk footprint methanol process

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Characterization of biocomposite from polypropylene and alkaline treated pineapple leaves fiber

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AIP Conference Proceedings 2025年第1期3266卷

作者： W. N. F. E. W. Adnan N. N. F. Nadzeri N. A. Yaacob N. I. A. A. Nordin Faculty of Chemical and Process Engineering Technology Universiti Malaysia Pahang Al-Sultan Abdullah Lebuh Persiaran Tun Khalil Yaakob 26300 Kuantan Pahang Malaysia

In recent years, scientific research in the composite area has been focusing on finding an alternative to replace the petroleum-based polymer. Pineapple Leaves Fibre (PALF) is one of the natural fiber potentially for further research and development to achieve this goal. However, the low thermal resistance and hydrophilic properties of PALF are the main drawbacks in this development. This paper studies the effect on properties of polypropylene (PP) biocomposites reinforced with different fibre loading of untreated-PALF and NaOH-treated-PALF. The fibres were characterised by using Fourier Transform Infrared Spectroscopy (FTIR) and Thermal Gravimetric Analysis (TGA). The untreated, 3 wt.% NaOH treated and 9 wt% NaOH treated PALF were grinded and compounded with PP using an extruder at 10, 20 and 30 wt% of fiber loading. Then, the samples were hot pressed into a film. Samples were analysis by its tensile strength and water absorption. The results show that the NaOH treated samples have improved thermal stability in range of 20 – 40% which is due to the removal of lignin and hemicellulose. The 3 wt.% NaOH treated PALF/PP biocomposite has a higher tensile strength at 23 MPa and lower water absorption at 1.19% compared to the 9 wt.% NaOH treated PALF/PP sample having tensile strength 19 MPa and 1.36% water absorption, at 10 wt% fiber loading. NaOH treatment can remove the lignin and hemicellulose content in the fiber. The improved tensile and water absorption of treated fiber biocomposite showed better compatibility of fiber with PP. This study successfully demonstrated that alkaline treatment at concentrations less than 10 wt% can improve the properties of natural fiber and subsequently promote to better compatibility of fiber and polymer matrix.

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