Gob-side entry retaining (GER) employed in a thin coal seam (TCS) can increase economic benefits and coal recovery, as well as mitigate gas concentration in the gob. In accordance with the caving style of a limestone roof, the gas concentration and air pressure in the gob were analyzed, and a roof-cutting mechanical model of GER with a roadside backfill body (RBB) was proposed, to determine the key parameters of the GER-TCS, including the roof-cutting resistance and the width of the RBB. The results show that if the immediate roof height is greater than the seam height, the roof-cutting resistance and width of the RBB should meet the requirement of the immediate roof being totally cut along the gob, for which the optimal roof-cutting resistance and width of RBB were determined by analytical and numerical methods. The greater the RBB width, the greater its roof-cutting resistance. The relationship between the supporting strength of the RBB and the width of the RBB can be derived as a co... [more]

Columns are widely used as packed-bed or fixed-bed reactors in the chemical process industry. Packed columns are also used for carrying out chemical separation techniques such as adsorption, distillation, extraction and chromatography. A combination of the variability in flow path lengths, and the variability of velocity along these flow paths results in significant broadening in solute residence time distribution within columns, particularly in those having low bed height to diameter ratios. Therefore, wide packed-column reactors operate at low efficiencies. Also, for a column of a particular bed height, the ratio of heat transfer surface area to reactor volume varies inversely as the radius. Therefore, with wide columns, the available heat transfer area could become a limiting factor. In recent papers, box-shaped or cuboid packed-bed devices have been proposed as efficient alternatives to packed columns for carrying out chromatographic separations. In this paper, the use of cuboid pa... [more]

To recover the filtered residues on a gel layer in a column, the method using the elasticity of the gel layer and flowing water in a cross-flow manner is proposed. Polymerized spherical gel (40 μm) was packed in a column to a set height of 0.7 cm. The suspensions of graphene oxide at various sizes and shapes were injected on the top of the gel layer and then water was flowed at a flow rate of 1000 mL·h−1 until 0.10 MPa. By releasing the applied pressure, the elastic gel layer rose up, and the filtered graphene oxide also rose above the layer. This rise of the gel layer is due to the difference of pressure between the gel layer, including the filtered graphene oxide, and the open bottom of the column, using the flow of water. The cross flow of water through the column carried away the larger-sized filtered graphene oxide floating above the gel layer. The elasticity of the gel layer and cross flow through the column has the potential to recover the filtered particles.

This study investigated the heterogeneous Fenton treatment to process coalbed methane-produced water containing fracturing fluid and chose the development region of coalbed methane in the Southern Qinshui Basin as a research area. We synthesized the catalyst of Fe-Co/γ-Al₂O₃ by homogeneous precipitation method and characterized it by BET, XRD, SEM-EDS, FTIR, and XPS. Based on the degradation rate, we studied the influences of the heterogeneous Fenton method on the coalbed methane output water treatment process parameters, including initial pH, H₂O₂ concentration, and the catalyst concentration. We also investigated the impacts of overall reaction kinetics of heterogeneous catalytic oxidation on coalbed methane-produced water containing fracturing fluid. Results showed that Fe-Co/γ-Al₂O₃ as a Fenton catalyst has a good catalytic oxidation effect and can effectively process coalbed methane-produced water. This reaction also followed first-order kinetics. The optimal conditions were as fo... [more]

Cyanide recovery in the gold-mining industry is a crucial step in terms of the cost of operation. Currently, a process such as AVR (acidification, volatilization and recycling), based on packed towers for stripping and absorption stages, addresses this issue with high levels of investment and operational costs. Gas-filled membrane absorption (GFMA) emerges then as an attractive alternative because the stripping and absorption stages can be performed in a single stage, reducing associated investment and operational costs. Despite the advantages of this technology, applications at industrial scale are still emerging. A possible reason is the lack of clear scaling-up methodologies where experimental data can be taken to select the optimum industrial hollow-fiber membrane contactor module (HFMC). The present study proposes a methodology to select adequately between available industrial Liqui-CelTM modules to design a process under optimal operational conditions. The methodology is based on... [more]

Although continuous production processes are often desired, many processing industries still work in batch mode due to technical limitations. Transitioning to continuous production requires an in-depth understanding of how each unit operation is affected by the shift. This contribution reviews the scientific understanding of similarities and differences between emulsification in turbulent rotor-stator mixers (also known as high-speed mixers) operated in batch and continuous mode. Rotor-stator mixers are found in many chemical processing industries, and are considered the standard tool for mixing and emulsification of high viscosity products. Since the same rotor-stator heads are often used in both modes of operation, it is sometimes assumed that transitioning from batch to continuous rotor-stator mixers is straight-forward. However, this is not always the case, as has been shown in comparative experimental studies. This review summarizes and critically compares the current understandin... [more]

A process consisting of ball milling followed by NaOH leaching was developed to selectively dissolve alumina from black dross. From the ball milling treatment, it was found that milling speed greatly affected the leaching behavior of silica and the oxides of Ca, Fe, Mg, and Ti present in dross. The leaching behavior of the mechanically activated dross was investigated by varying NaOH concentration, leaching temperature and time, and pulp density. In most of the leaching conditions, only alumina and silica were dissolved, while the leaching percentage of other oxides was negligible. The leaching percentage of silica decreased rapidly to nearly zero as pulp density increased to 100 g/L. At the optimum leaching conditions (5 M NaOH, 50 °C, 2 h, pulp density of 100 g/L), the purity of Al in the leaching solution was higher than 98%, but the leaching percentage of alumina was only 35%.

This study is conducted to investigate the characteristics of outflow wastewater of the 1 m³ on-site wastewater treatment unit on the basis of the testing and measurement data of the samples that were taken during the study monitored period (August 2017 to January 2018). For this purpose, samples were taken on a weekly basis from the treated wastewater effluent and five quality parameters (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), pH, E-coli counts) were monitored and measured. The average values of the five parameters were compared with the Jordanian standard maximum values, and water reuse in irrigation of plants classifications have been assessed and investigated. Average values of BOD, COD, TSS, pH, and E-coli in treated wastewater were 11 mg/L, 104 mg/L, 15 mg/L, 7.51, and 387 counts, respectively. The installation of in-line ultraviolet (UV) unit in recirculating delivery system played a vital role in the reduction of counts far... [more]

Fuel gas network (FGN) synthesis is a systematic method for reducing fresh fuel consumption in a chemical plant. In this work, we address FGN synthesis problems using a block superstructure representation that was originally proposed for process design and intensification. The blocks interact with each other through direct flows that connect a block with its adjacent blocks and through jump flows that connect a block with all nonadjacent blocks. The blocks with external feed streams are viewed as fuel sources and the blocks with product streams are regarded as fuel sinks. An additional layer of blocks are added as pools when there exists intermediate operations among source and sink blocks. These blocks can be arranged in a I × J two-dimensional grid with I = 1 for problems without pools, or I = 2 for problems with pools. J is determined by the maximum number of pools/sinks. With this representation, we formulate FGN synthesis problem as a mixed-integer nonlinear... [more]

In this research, an ANOVA analysis and a response surface methodology are applied to analyze the equilibrium of methanol reaction from pure carbon dioxide and hydrogen. In the ANOVA analysis, carbon monoxide composition in the feed, reaction temperature, recycle and water removal through a zeolite membrane are the analyzed factors. Carbon conversion, methanol yield, methanol productivity and methanol selectivity are the analyzed responses. Results show that main factors have the same effect on responses and a common significant interaction is not present. Carbon monoxide composition and water removal have a positive effect, while temperature and recycle have a negative effect on the system. From central composite design, an optimal solution is found in order to overcome thermodynamic limit: the reactor works with a membrane at lower temperature with carbon monoxide composition in the feed equal to 10 mol % and without recycle. In these conditions, carbon conversion, methanol yield, me... [more]

This paper discusses the techno-economic assessment of hydrogen production from biogas with conventional systems. The work is part of the European project BIONICO, whose purpose is to develop and test a membrane reactor (MR) for hydrogen production from biogas. Within the BIONICO project, steam reforming (SR) and autothermal reforming (ATR), have been identified as well-known technologies for hydrogen production from biogas. Two biogases were examined: one produced by landfill and the other one by anaerobic digester. The purification unit required in the conventional plants has been studied and modeled in detail, using Aspen Adsorption. A pressure swing adsorption system (PSA) with two and four beds and a vacuum PSA (VPSA) made of four beds are compared. VPSA operates at sub-atmospheric pressure, thus increasing the recovery: results of the simulations show that the performances strongly depend on the design choices and on the gas feeding the purification unit. The best purity and reco... [more]

Centrifugal pumps are widely used in the industry, especially in the oil and gas sector for fluids transport. Classically, these are designed to transfer single phase fluids (e.g., water) at high flow rates and relatively low pressures when compared with other pump types. As part of their constructive feature, centrifugal pumps rely on seals to prevent air entrapment into the rotor during its normal operation. Although this is a constructive feature, water should pass through the pump inlet even when the inlet manifold is damaged. Modern pumps are integrated in pumping units which consist of a drive (normally electric motor), a transmission (when needed), an electronic package (for monitoring and control), and the pump itself. The unit also has intake and outlet manifolds equipped with valves. Modern systems also include electronic components to measure and monitor pump working parameters such as pressure, temperature, etc. Equipment monitoring devices (vibration sensors, microphones)... [more]

Equipment throughput is one of the most critical parameters for production planning and scheduling, which is often derived by optimization techniques to achieve business goals. However, in semiconductor manufacturing, up-to-date and reliable equipment throughput is not easy to estimate and maintain because of the high complexity and extreme amount of data in the production systems. This article concerns the development and implementation of a throughput management system tailored for a semiconductor wafer fabrication plant (Fab). A brief overview of the semiconductor manufacturing and an introduction of the case Fab are presented first. Then, we focus on the system architecture and some concepts of crucial modules. This study also describes the project timescales and difficulties and discusses both tangible and intangible benefits from this project.

A process improvement in a tablet manufacturing process within a pharmaceutical industry was carried out based on an eco-efficiency approach. As it is one of the most energy consuming processes in the production line, the tablet manufacturing process was considered. It has the highest production volume with a complicated and long manufacturing product life cycle. Data were collected on energy inputs and emissions data for the stages of powder direct mixing, particle size reduction, and tableting. A straightforward approach was then used to analyze environmental impacts in terms of GHG emissions. Non- added value steps were removed from the product life cycle process, which has led to significant time and cost savings, as well as to a reduction in the emission. Annual economic savings have been achieved, a time reduction of approximately 71% was attained, and the reduction in GHG emissions and energy cost were 73.2%. The g CO₂eq per tablet reduction has been calculated within the proces... [more]

Dry reforming is a very interesting process for synthesis gas generation from CH 4 and CO 2 but suffers from low hydrogen yields due to the reverse water⁻gas shift reaction (WGS). For this reason, membranes are often used for hydrogen separation, which in turn leads to coke formation at the process temperatures suitable for the membranes. To avoid these problems, this work shows the possibility of using nickel self-supported membranes for hydrogen separation at a temperature of 800 ∘ C. The higher temperature effectively suppresses coke formation. The paper features the analysis of the dry reforming reaction in a nickel membrane reactor without additional catalyst. The measurement campaign targeted coke formation and conversion of the methane feedstock. The nickel approximately 50% without hydrogen separation. The hydrogen removal led to an increase in methane conversion to 60⁻90%.

Calculation of evaporation requires accurate thermophysical properties of the liquid. Such data are well-known for conventional fossil fuels. In contrast, e.g., thermal conductivity or dynamic viscosity of the fuel vapor are rarely available for modern liquid fuels. To overcome this problem, molecular models can be used. Currently, the measurement-based properties of n-heptane and diesel oil are compared with estimated values, using the state-of-the-art molecular models to derive the temperature-dependent material properties. Then their effect on droplet evaporation was evaluated. The critical parameters were liquid density, latent heat of vaporization, boiling temperature, and vapor thermal conductivity where the estimation affected the evaporation time notably. Besides a general sensitivity analysis, evaporation modeling in a practical burner ended up with similar results. By calculating droplet motion, the evaporation number, the evaporation-to-residence time ratio can be derived. A... [more]

The moisture content of biomass affects its processing for applications such as electricity or steam. In this study, the effects of variation in moisture content of banagrass and energycane was evaluated using techno-economic analysis and life-cycle assessments. A 25% loss of moisture was assumed as a variation that was achieved by field drying the biomass. Techno-economic analysis revealed that high moisture in the biomass was not economically feasible. Comparing banagrass with energycane, the latter was more economically feasible; thanks to the low moisture and ash content in energycane. About 32 GWh/year of electricity was produced by field drying 60,000 dry MT/year energycane. The investment for different scenarios ranged between $17 million and $22 million. Field-dried energycane was the only economically viable option that recovered the investment after 11 years of operation. This scenario was also more environmentally friendly, releasing 16-gCO₂ equivalent/MJ of electricity prod... [more]

Mineral calcination worldwide accounts for some 5⁻10% of all anthropogenic carbon dioxide (CO₂) emissions per year. Roughly half of the CO₂ released results from burning fossil fuels for heat generation, while the other half is a product of the calcination reaction itself. Traditionally, the fuel combustion process and the calcination reaction take place together to enhance heat transfer. Systems have been proposed that separate fuel combustion and calcination to allow for the sequestration of pure CO₂ from the calcination reaction for later storage/use and capture of the combustion gases. This work presents a new tube-in-tube helical system for the calcination of minerals that can use different heat transfer fluids (HTFs), employed or foreseen in concentrated solar power (CSP) plants. The system is labeled ‘flameless’ since the HTF can be heated by other means than burning fossil fuels. If CSP or high-temperature nuclear reactors are used, direct CO₂ emissions can be divided in half.... [more]

A model predictive control (MPC) framework, exploiting both feedforward and feedback control loops, is employed to minimize large disturbances that occur in military water networks. Military installations’ need for resilient and efficient water supplies is often challenged by large disturbances like fires, terrorist activity, troop training rotations, and large scale leaks. This work applies the effectiveness of MPC to provide predictive capability and compensate for vast geographical differences and varying phenomena time scales using computational software and actual system dimensions and parameters. The results show that large disturbances are rapidly minimized while maintaining chlorine concentration within legal limits at the point of demand and overall water usage is minimized. The control framework also ensures pumping is minimized during peak electricity hours, so costs are kept lower than simple proportional control. Thecontrol structure implemented in this work is able to sup... [more]

In recent years gas⁻liquid flow in microchannels has drawn much attention in the research fields of analytics and applications, such as in oxidations or hydrogenations. Since surface forces are increasingly important on the small scale, bubble coalescence is detrimental and leads to Taylor bubble flow in microchannels with low surface-to-volume ratio. To overcome this limitation, we have investigated the gas⁻liquid flow through micronozzles and, specifically, the bubble breakup behind the nozzle. Two different regimes of bubble breakup are identified, laminar and turbulent. Turbulent bubble breakup is characterized by small daughter bubbles and narrow daughter bubble size distribution. Thus, high interfacial area is generated for increased mass and heat transfer. However, turbulent breakup mechanism is observed at high flow rates and increased pressure drops; hence, large energy input into the system is essential. In this work Design of Experiment assisted evaluation of turbulent bubbl... [more]

Recovering valuable compounds from waste streams of bio-based production processes is in line with the circular economy paradigm, and is achievable by implementing “simple-to-use” and well-established process separation technologies. Such solutions are acceptable from industrial, economic and environmental points of view, implying relatively easy future implementation on pilot- and full-scale levels in the bio-based industry. Reviewing such technologies is therefore the focus here. Considerations about technology readiness level (TRL) and Net Present Value (NPV) are included in the review, since TRL and NPV contribute significantly to the techno-economic evaluation of future and promising process solutions. Based on the present review, a qualitative guideline for resource recovery from bio-based production processes is proposed. Finally, future approaches and perspectives toward identification and implementation of suitable resource recovery units for bio-based production processes are... [more]

Aerobic granular sequencing batch reactors (SBRs) are usually inoculated with activated sludge which implies sometimes long start-up periods and high solids concentrations in the effluent due to the initial wash-out of the inoculum. In this work, the use of aerobic mature granules as inoculum in order to improve the start-up period was tested, but no clear differences were observed compared to a reactor inoculated with activated sludge. The effect of the aeration rate on both physical properties of granules and reactor performance was also studied in a stable aerobic granular SBR. The increase of the aeration flow rate caused the decrease of the average diameter of the granules. This fact enhanced the COD and ammonia consumption rates due to the increase of the DO level and the aerobic fraction of the biomass. However, it provoked a loss of the nitrogen removal efficiency due to the worsening of the denitrification capacity as a consequence of a higher aerobic fraction.

Prilling is a common process in the fertilizer industry, where the fertilizer melt is converted to droplets that fall, cool down and solidify in a countercurrent flow of air in a prilling tower. A vibratory granulator was used to investigate liquid jet breakup into droplets. The breakup of liquid jets subjected to a forced perturbation was investigated in the Rayleigh regime, where a mechanical vibration was applied in order to achieve the production of monodispersed particles. Images of the jet trajectory, breakup, and the formed drops were captured using a high-speed camera. A mathematical model for the liquid outflow conditions based on a transient two-dimensional Navier⁻Stokes equation was developed and solved analytically, and the correlations between the process parameters of the vibrator and the jet pressure that characterize their disintegration mode were identified. The theoretical predications obtained from the correlations showed a good agreement with the experimental result... [more]

The availability and low cost of shale gas has boosted its use as fuel and as a raw material to produce value-added compounds. Benzene is one of the chemicals that can be obtained from methane, and represents one of the most important compounds in the petrochemical industry. It can be synthesized via direct methane aromatization (DMA) or via indirect aromatization (using oxidative coupling of methane). DMA is a direct-conversion process, while indirect aromatization involves several stages. In this work, an economic, energy-saving, and environmental assessment for the production of benzene from shale gas using DMA as a reaction path is presented. A sensitivity analysis was conducted to observe the effect of the operating conditions on the profitability of the process. The results show that production of benzene using shale gas as feedstock can be accomplished with a high return on investment.

The expected world population growth by 2050 is likely to pose great challenges in the global food demand and, in turn, in the fertilizer consumption. The Food and Agricultural Organization of the United Nations has forecasted that 46% of this projected growth will be attributed to Africa. This, in turn, raises further concerns about the sustainability of Africa’s contemporary fertilizer production, considering also its high dependence on fertilizer imports. Based on these facts, a novel “green” route for the synthesis of fertilizers has been considered in the context of the African agriculture by means of plasma technology. More precisely, a techno-economic feasibility study has been conducted for a small-scale plasma-assisted nitric acid plant located in Kenya and South Africa with respect to the electricity provision by renewable energy sources. In this study, standalone solar and wind power systems, as well as a hybrid system, have been assessed for two different electricity loads... [more]