Feedstock Flow Rate Research Articles

Development of pure hydrogen generation system based on methanol steam reforming and Pd membrane

Methanol steam reforming (MSR) has been used for in-situ hydrogen production, while hydrogen purification remains a technical challenge to limit the applications of using hydrogen for fuel cells. This study presents a pure hydrogen generation system (PHGS) by integrating MSR and hydrogen purification modules, this system enables low-temperature reforming and high-temperature purification to achieve high yield and recovery of hydrogen. To investigate the combined effects of feedstock flow rates and pressure on MSR and purification, the performance of each module and overall PHGS system were tested. The results showed that PHGS can stably produce high purity hydrogen (>99.99%) under different conditions, the synergistic effects of two modules lead to hydrogen yield exceeding the numerical sum of individual modules. At methanol feed rate of 1.00 g/min and system pressure of 5.0 bar, the pure hydrogen flow rate, CO content, pure hydrogen yield, hydrogen recovery and thermal power output were tested about 1.70 ± 0.01 L/min, 2.4 ± 0.1 ppm, 81.1 ± 0.5%, 87.6 ± 0.5% and 350 W. The PHGS can deliver up to 500 W of thermal power and is suitable for small range-extended electric vehicles. Our work on the developed PHGS can provide a significant reference for future practical applications of systems combining MSR and membrane purification.

Chemical Process Design and Simulation of the Production of Gamma‐Valerolactone: A Green Solvent for Halide Perovskites

Enabling large‐scale perovskite photovoltaic production requires understanding the integrated chemical process flow of precursor ink. Herein, a chemical process design is proposed for producing halide perovskite ink using biomass‐derived gamma‐valerolactone (GVL) as a green solvent for the first time. The proposed design has a perovskite ink production capacity of 154 kg h−1 (at 1 m concentration), which is roughly equivalent to a peak power generation of 300 GW year−1 from perovskite modules. Process simulations in ASPEN Plus showed that the reactor temperature, feedstock flow rate, and precursor colloidal size greatly impact the final ink quality. Under optimum conditions, 98.4% purity of GVL can be achieved through a catalyzed reaction between levulinic acid and isopropyl alcohol with acetone (99.98%) and water (99.99%) as by‐products. Providing a realistic chemical reaction scheme for halide perovskite ink formation as well as understanding the changes in its chemical properties over time are paramount to further improving the proposed process.

Spray Parameters and Coating Microstructure Relationship in Suspension Plasma Spray TiO2 Coatings

In recent years, there has been growing interest in thermal spray techniques using suspension or solution-based coatings. These techniques offer precise control over particle size and microstructure, improving feedstock flowability and allowing for high-quality coating customization. Spray parameters, such as stand-off distance (SOD) and feedstock flow rate, can alter the performance and characteristics of these coatings. Geothermal power plant heat exchangers often face issues like corrosion, scaling, and fouling. The literature suggests that these issues could be mitigated, at least in part, by the use of spray coatings. In this study, TiO2 coatings were applied on a carbon steel substrate using suspension plasma spray (SPS) to enhance the performance of geothermal heat exchanger materials. The impact of SOD (50, 75, and 100 mm) and feedstock flow rate (10, 20, and 30 mL/min) on these coatings was examined through various techniques, including scanning electron microscope (SEM), profilometry, X-ray diffraction (XRD), and adhesion testing. The results demonstrated that coatings deposited using a 10 mL/min feedstock flow rate were well adhered to the substrate due to the efficient melting of the coating material, but as the SOD and feedstock flow rate increased due to poor thermal and kinetic energy exchange between the torch and feedstock particles, adhesion between the coating and substrate decreased.

Influence of alumina fixed-bed in steam reforming of glycerol for hydrogen production

In this study, hydrogen production by steam reforming was carried out in a tubular fixed-bed reactor. The influence of some operating variables such as temperature, flow rate of the feeding glycerol solution and space velocity on hydrogen production under a non-catalyzed reaction was analyzed. The results showed that the hydrogen yield increased with temperature and decreased with the space velocity. As the feedstock flow rate increased, the hydrogen yield decreased rapidly. Compared with a reference experiment without fixed-bed, the use of non-porous alumina fixed-bed showed better results. Under the best reaction conditions (900 °C and a feedstock flow rate of 0.85 g/min), 17 L/h of syngas were obtained, with a purity of about 55% of hydrogen and a production of 2.7 moles of hydrogen by mol of glycerol.

Efficient immobilization of acids into activated carbon for high durability and continuous desulfurization of diesel fuel

AbstractFuel contaminants are the most critical issues in human health, cars' engines life and performance, and refinery equipment, and have an ultimate consecutive economic negative impact over time. Nowadays, sulfur is considered as one of the most dangerous contaminants in fuel, and different approaches have been carried out for desulfurization processing. In this study, new modified activated carbon (AC) for adsorptive diesel fuel desulfurization is carried out. To increase the robustness and effectiveness of a continuous adsorptive desulfurization (ADS) process, the study provides a new surface modification technique of the AC. Real diesel fuel (RDF, sulfur content 7510 ppm) and model diesel fuel (MDF, dibenzothiophene content 637 ppm) were used in a series of ADS tests carried out in a fixed‐bed adsorption column under atmospheric pressure and temperature. To achieve zero emissions of diesel fuel, the process parameters were optimized using the experimental findings. The AC and modified AC were tested via Brunauer–Emmett–Teller and Fourier Transform Infrared to evaluate the effect of the modification process on adsorbent characterization. The liquid hourly space velocity of the feedstock, the height of the absorber bed, and the kind of AC were the optimization parameters. In these circumstances, the ADS procedure was examined to address the impact of the feedstock flow rate on the effectiveness of ADS. The sulfur removal efficiency was 85.3% for RDF and 94% for MDF at 9 cm bed height, 8 h−1 LSHV, and 10 g bed weight, respectively. This is the first time that AC has been used to examine the stability of continuous ADS and to examine how acid immobilization affects sulfur removal. The investigation showed that the modified AC had a high rate of stability and was effective in the continuous ADS process. The spent modified AC was regenerated via a solvent extractive regeneration process to evaluate the durability of the ACs. The results proved that the regeneration performance of various solvents for modified activated carbon 1 decreases as follows: iso‐octane > ethanol > methanol > acetonitrile.

Design Strategy for Performance Enhancement of Vertical Plate Microdistillators

Microdevices have been actively implemented in chemical processes, such as in mixing and reactions. However, microseparation devices, excluding extraction devices, are still under development. In distillation, the use of microdevices has been expected to improve separation performance, as their large specific surface area enables a rapid vapor–liquid equilibrium and for large temperature gradients to be easily realized. In this study, improvements in throughput and product purities in microdistillation devices were achieved for ethyl acetate–toluene distillation. At low feedstock flow rates, ethyl acetate was successfully purified to 99.5 wt%. Although the performance decreased with increasing feedstock flow rate, by increasing the channel length, this performance decrease was suppressed even at high flow rates. The thickness of the channel was also important, and the highest performance was observed at the lowest thickness of 0.5 mm. A performance evaluation using the HETP showed that the efficiency was seven times higher than that of conventional packed column distillators.

Robust optimal operation of continuous catalytic reforming process under feedstock uncertainty

The continuous catalytic regenerative (CCR) reforming process is one of the most significant sources of hydrogen production in the petroleum refining process. However, the fluctuations in feedstock composition and flow rate could significantly affect both product distribution and energy consumption. In this study, a robust deviation criterion based multi-objective optimization approach is proposed to perform the optimal operation of CCR reformer under feedstock uncertainty, with simultaneous maximization of product yields and minimization of energy consumption. Minimax approach is adopted to handle these uncertain objectives, and the Latin hypercube sampling method is then used to calculate these robust deviation criteria. Multi-objective surrogate-based optimization methods are next introduced to effectively solve the robust operational problem with high computational cost. The level diagram method is finally utilized to assist in multi-criteria decision-making. Two robust operational optimization problems with different objectives are solved to demonstrate the effectiveness of the proposed method for robust optimal operation of the CCR reforming process under feedstock uncertainty.

Natural Gas Conversion and Organic Waste Gasification by Detonation-Born Ultra-Superheated Steam: Effect of Reactor Volume

The pulsed detonation (PD) gun technology was applied for the autothermal high-temperature conversion of natural gas and atmospheric-pressure oxygen-free allothermal gasification of liquid/solid organic wastes by detonation-born ultra-superheated steam (USS) using two flow reactors of essentially different volume: 100 and 40 dm3. Liquid and solid wastes were waste machine oil and wood sawdust, with moisture ranging from 10 to 30%wt. It was expected that decrease in the reactor volume from 100 to 40 dm3, other conditions being equal, on the one hand, should not affect natural gas conversion but, on the other hand, could lead to an increase in the gasification temperature in the flow reactor and, correspondingly, to an increase in the product syngas (H2 + CO) quality. The PD gun was fed by natural gas–oxygen mixture and operated at a frequency of 1 Hz. As was expected, complete conversion of natural gas to product syngas in the PD gun was obtained with H2/CO and CO2/CO ratios equal to 1.25 and 0.25, irrespective of the reactor volume. Liquid and solid wastes were gasified to H2, CO, and CH4 in the flow reactors. The steady-state H2/CO and CO2/CO ratios in the syngas produced from waste machine oil were 0.8 and 0.5 for the 100-dm3 reactor and 0.9 and 0.2 for the 40-dm3 reactor, respectively, thus indicating the expected improvement in syngas quality. Moreover, the maximum mass flow rate of feedstock in the 40-dm3 reactor was increased by a factor of over 4 as compared to the 100-dm3 reactor. The steady-state H2/CO and CO2/CO ratios in the syngas produced from the fixed weight (2 kg) batch of wood sawdust were 0.5 and 0.8 for both reactors, and the gasification time in both reactors was about 5–7 min. The measured H2 vs. CO2 and CO vs. CO2 dependences for the syngas produced by the autothermal high-temperature conversion of natural gas and atmospheric-pressure allothermal gasification of liquid/solid organic wastes by USS at f = 1 Hz were shown to be almost independent of the feedstock and reactor volume due to high values of local instantaneous gasification temperature.

Syngas analysis by hybrid modeling of sewage sludge gasification in downdraft reactor: Validation and optimization

In general, sewage sludge obtained from the municipal wastewater treatment plant is one of the significant sources of waste for renewable energy production. In this article, the thermochemical conversion of sewage sludge through a downdraft gasifier is addressed. Two-zone equilibrium and one-zone kinetic model as the hybrid modeling of the sewage sludge gasification is proposed. Three zones of drying & pyrolysis, oxidation, and (char) reduction are modeled by using an integrated thermodynamic stoichiometric equilibrium and Langmuir-Hinshelwood kinetic model. Through the validation and sensitivity analysis, the syngas compositions and cold gas efficiency show to be sensitive to the variations of inlet flow rates of gasifying agents (air and steam), the inlet flow rate of feedstock (sewage sludge), and the temperature and pressure of the gasifier. Through the response surface methodology-based optimization algorithm, the proper operating conditions of the process can be found under the prescribed operating constraints.

Simulation and Optimization of the Ethane Cracking Furnace Using ASPEN PLUS and MATLAB: A Case Study from Petrochemical Complexes

ABSTRACT Ethylene production is one of the most abundant activities in petrochemical industries. So, the main objective is to develop detailed models to describe a pyrolysis section in the real ethylene plant furnace located at the petrochemical complex (PC1), Basra, Iraq. Those models were utilized to evaluate the effects of the reaction temperature, steam to ethane ratio (DS/HC), and feedstock flowrate on the ethylene yield using different feedstock compositions. The simulation validity was tested by comparing the simulation results with the real data collected from the PC1 and showed an acceptable similarity and reliability depending on relative error values. A genetic algorithm coded by MATLAB and Aspen Plus optimizer was used to obtain the optimal operating conditions to give a maximum profit. The optimization results of Aspen Plus and GA showed an increase in the profit equal to 10.541 and 9.823% respectively when the reaction temperature, DS/HC and outlet flowrate of hydrocarbons were in the range of 850–920°C, 0.2–0.5, and 2421–1064 Kmole/hr respectively. Also, Increasing the ethane content in feedstock leads to an increase in the feedstock production of 16–19% ethane content.

Flame establishment and flameholding modes spontaneous transformation in kerosene axisymmetric supersonic combustor with a plasma igniter

Plasma is considered as a potential method to promote the establishment of supersonic flame and has been investigated wildly. This paper provides the establishment process of flame with a plasma igniter (PI) in axisymmetric kerosene combustor under the conditions of Ma=3 and Tt=1680 K, and finds that proposes several typical modes of flameholding during the establishment process, as well as investigates the main factors on the flameholding modes. The results showed that during the establishment process of flame, a phenomenon that a weak flame will spontaneously transform to a stronger flame in a pure supersonic flow will occur. To understand the reason inducing spontaneous transformation, four types of flameholding are classified. The four types of flameholding modes are partial oxidation, weak flame, strong flame and cone-strut flame. Each type of flameholding modes has unique color, brightness, shape and size. The excitation current of plasma igniter, the feedstock flow rate of the plasma igniter, and the fuel equivalent ratio will determine which flame is formed. A simple analysis model including the heat release rate, which is proposed to explain the experimental results, indicates that the heat release rate and flame temperature of flame front are the key factors affecting flameholding modes, and the thermal congestion induced by the heat release maybe the reason causing spontaneous transformation.

Determination of heat transfer coefficient in advanced rotary film evaporator

The object of research is the process of concentrating fruit and vegetable purees in an improved rotary film evaporator. The existing hardware design of traditional processes for processing fruits and vegetables, as a rule, is not unified enough, inconvenient in operation and is designed for high productivity. Concentration of fruit and vegetable purees occurs mainly in vacuum evaporators of periodic and continuous operation at a temperature of 60–80 °C under vacuum, which allows them to significantly preserve their nutritional value. But the duration of the process remains very significant (in devices of periodic action up to 75–90 minutes). One of the most problematic areas in the concentration of fruit and vegetable raw materials is significant losses of biologically active substances. At the same time, an important indicator of the quality of the process of concentrating pasty fruit and vegetable pastes is the value of the heat transfer coefficient, which characterizes the efficiency of the heat transfer method and the design features of the mixing device, taking into account the thermophysical characteristics of the product. To create conditions for conducting research to determine the heat transfer coefficient, it is necessary to use instrumentation with precise regulation of the necessary technological parameters. To study the heat transfer coefficient when concentrating fruit and vegetable purees, an automatic installation of an improved rotary evaporator was designed. The improvement of the rotary film evaporator (RFE) is carried out due to the lower location of the separating space by installing a screw discharge of the paste and preheating the output puree with secondary steam. The experimental dependences of the heat transfer coefficient on the product flow rate make it possible to determine the rational values of the flow rate of the RFE feedstock at various values of the rotor shaft speed. It is found that the heat transfer coefficient is influenced to a large extent by the product consumption, and the rotor speed acts to a lesser extent, only the relative speed of fluid passage around the developed hinged blade changes. It is found that when the frequency changes from 0.3 to 1.7 s–1, an increase in the heat transfer coefficient by 1.45 times is observed, which is explained by a more intensive degree of mixing of the product by the blades.

Multi-objective optimization of an integrated biomass waste fixed-bed gasification system for power and biochar co-production

In this work, an integrated biomass waste gasification combined heat and power (CHP) system is simulated and analyzed based on a multi-scale first-principles numerical model, which consists of a 1D fixed-bed gasifier model and a 1D hybrid peripheral fragmentation and shrinking-core biomass particle model. The simulations are based on a 15kW gasification CHP system and the numerical model is validated by two different groups of experimental data, and the maximum deviation is 2.56% in syngas H2 composition prediction. A multi-objective optimization framework of the integrated biomass waste gasification CHP system is formulated that considers 3 objectives: economic benefit, greenhouse gas emission, and potential health impact caused by PM emission. The best-compromised solution from the Pareto front leads to $142.8/day economic benefit, 694.3 kg CO2eq/day mitigation, and 57.67 Singapore Pollutant Standards Index score. The impacts of the three objectives on decision variables (i.e., feedstock flowrate, feedstock moisture content, and equivalent ratio) are analyzed by investigating 21 different weighted single-objective problems.

Integration of Renewable Hydrogen Production in Steelworks Off-Gases for the Synthesis of Methanol and Methane

The steel industry is among the highest carbon-emitting industrial sectors. Since the steel production process is already exhaustively optimized, alternative routes are sought in order to increase carbon efficiency and reduce these emissions. During steel production, three main carbon-containing off-gases are generated: blast furnace gas, coke oven gas and basic oxygen furnace gas. In the present work, the addition of renewable hydrogen by electrolysis to those steelworks off-gases is studied for the production of methane and methanol. Different case scenarios are investigated using AspenPlusTM flowsheet simulations, which differ on the end-product, the feedstock flowrates and on the production of power. Each case study is evaluated in terms of hydrogen and electrolysis requirements, carbon conversion, hydrogen consumption, and product yields. The findings of this study showed that the electrolysis requirements surpass the energy content of the steelwork’s feedstock. However, for the methanol synthesis cases, substantial improvements can be achieved if recycling a significant amount of the residual hydrogen.

The study of palm kernel shell updraft gasification for supplying heat to an asphalt mixing plant

Air-gasification converts biomass using air into combustible gaseous components which also known as producer gas. The combustion of those gases provides energy for any purposes. In an asphalt mixing plant, this technology is implemented using palm kernel shell as feedstock to generate heat for aggregate heating as a part of hot-mixed asphalt production. Both Cold Gas Efficiency (CGE) and Carbon Conversion Efficiency (CCE) are the common performance indicators of such process. This study examines a performance of an updraft fixed-bed gasifier to convert the shell into producer gas in supplying heat for increasing aggregate temperature from ambient to about 145 – 165°C at capacity of 800 kg/min. The feedstock flowrate was set at 990 kg/hour and equivalence ratios were varied at 0.04, 0.05 and 0.08. Because the gasification reactions were in equilibrium, the producer gas composition for calculating the CGE was predicted using thermodynamic model with minimizing Gibbs free energy. The feedstock and solid residue of the process were analysed to determine the carbon content for calculating the CCE. It is indicated that the performance of the gasification operation for supplying heat in an asphalt mixing plant is limited by operating conditions.

Computer Modeling System of the Industrial Diesel Fuel Catalytic Dewaxing Process

AbstractAn unsteady mathematical model and a computer modeling system of the diesel fuel catalytic dewaxing process (mild hydrocracking) were developed. The modeling system allows for calculating the optimal technological mode to produce low‐freezing diesel fuel with the required cold filter plugging point taking into account the feedstock composition and catalyst activity. The modeling system consists of the main blocks: database, knowledge base, unsteady mathematical model of the diesel fuel catalytic dewaxing process, and application program package. Using the developed computer modeling system, the influence of the feedstock composition and flow rate as well as of the catalyst activity on the cold filter plugging point and the yield of diesel fuel is demonstrated.

Experimental and numerical study on heat transfer driven dynamics and control of transient variations in a solar receiver

A novel and compact variable aperture mechanism coupled to flow channels for recovery of spilled solar power was implemented on a cavity-type solar receiver to regulate its temperature and compensate for the sun’s transient variations. PID and model predictive control methods were initially numerically tested and tuned, and then experimentally tested using a 10 kWe high flux solar simulator for set point tracking and disturbance rejection under simulated sun’s direct normal irradiance. The variable aperture demonstrated a promising performance in regulating the solar receiver’s average temperature by maintaining it within ±1.5 °C of its set point under experimental transient variations. The aperture mechanism’s high performance was achieved while capturing approximately 54% of intercepted spilled solar power, which can be used to preheat the feedstock for better process efficiencies or made available to a secondary end-use process. Additionally, the aperture mechanism was shown to reduce the receiver’s temperature drop in the absence of solar radiation by closing the variable aperture blades which reduced re-radiation losses from the receiver’s cavity. Finally, two other control strategies were experimentally investigated, namely PID feedstock flow rate controller and PID multiple-input single-output controller that can manipulate both the variable aperture size and feedstock flow rate. In all cases and despite severe solar power fluctuations, the variable aperture mechanism demonstrated a promising performance in regulating the temperature in a solar receiver and compensating for the sun’s transient variations.

A review on conducting carbon nanotube fibers spun via direct spinning technique

Due to our modern standard of living, the demand of electrical energy is growing rapidly. To meet this exigency, the conventional metal wires have become obsolete to meet highly efficient electrical energy supply demands. The suitable alternative to metal wires must exhibit good electrical and thermal conductivity, low mass density, negligible skin effects and non-corrosive properties. The axially aligned carbon nanotubes (CNT) assemblies, the CNT fibers, are among the most promising materials to meet these requirements. The CNT fibers hold great potential for highly fuel-efficient electric vehicles and low-power nanochips in ever-advancing computer hardware where conventional wires have no future. This article provides an overview of the conducting nature of CNT fibers. First, CNTs as futuristic conducting material will be elucidated briefly, followed by synthesis techniques of CNT fiber. Specific attention is devoted to the direct spinning technique (FC-CVD) as the fiber produced by this method has quite high electrical conductivity (EC) and of limitless length. Then, the effect of various parameters (during synthesis like carrier gas or feedstock flow rate and after synthesis like doping of metallic nanomaterials, coating of polymers or interaction with the acidic environment) on its EC is discussed. This study would pave the way for the bright future of CNT fiber to be used as electrical wiring by concentrating on current challenges confronting this field.

Transformations of stable gas condensate hydrocarbons into high-octane gasoline components over ZSM-5 zeolite catalyst

The process of stable gas condensate zeoforming was implemented at the laboratory scale under the conditions of varying feedstock composition and technological parameters (temperature, pressure, feedstock flow rate). The directions of hydrocarbon transformations were established. The influence of technological parameters on the composition and properties of the obtained product was estimated. From the perspective of involving the obtained zeoforming product into production of motor gasoline, optimal technological parameters were determined (the temperature of 375 °C, the pressure of 2.5 MPa, the feedstock flow rate of 2 h−1), the most preferred feedstock was established (the feedstock, which contains high amount of naphthenes, which sufficiently influence aromatization reaction). The recipes for motor gasoline blending were developed using the zeoforming product as the major component for the production of different grades, such as RON-92, RON-95, RON-98, meeting the modern specifications.

Cyclodextrine-glutaraldehyde cross-linked nanofiltration membrane for recovery of resveratrol from plant extract

Resveratrol has antibacterial, antioxidant, anthelmintic and insecticide properties. While the demands for use of resveratrol have been increasing, its separation and purification from its crude extract have not matured well-enough yet. Though nanofiltration (NF) can be used for the purification of the resveratrol molecules yet the extent to which this can be achieved is not known. In addressing this, glutaraldehyde cross-linked alpha, beta and gamma-cyclodextrin NF membranes were prepared and studied for their performances in the separation of resveratrol from plant extract. Beta CD-Glu cross-linked membranes are thermally stable up to the temperature of 516 °C and it is hydrophobic in nature. The interplay of the effects of various permeation parameters on flux and rejection rate has been established. The permeation flux reached 11.35 mmol.m-−2. h-1 for a feed concentration of 0.76 mmol.L-1 solution and the maximum % rejection of 98.02 % was eventually recorded for beta CD-Glu cross-linked membrane. The concentration of resveratrol in the feed solution also plays a prominent role in altering the percentage of separation of resveratrol from its crude extract. The transport of resveratrol was explained with a model of solute transport inside the membrane pores which depends on the hydrogen bonding contribution between the solvent, solute and membrane. Overall, it was observed that the rejection decreased when the feedstock flow rate goes up, which indicated that the permeation flux increases. The membrane has a high enrichment of resveratrol separation.