Linear Feed Rate Research Articles

CATALYTIC PROCESSING OF COAL MINE METHANE INTO HYDROGEN-CONTAINING GAS: INFLUENCE OF TRI-REFORMING PROCESS CONDITIONS

In order to develop a catalytic technology for processing coal mine methane into hydrogen-containing gas, thermodynamic analysis of methane tri-reforming (TRM) was carried out, and the influence of temperature (600-850 °C), contact time (0.04-0.15 s), linear feed rate (80-240 cm/min) and composition (CH4 / CO2 / H2O / O2 / He = 1: (0.3-0.5) : (0.2-0.5) : (0.1-0.3) : (2.9-3.2)) of the reaction mixture on the conversion of the initial reagents and target products in the TRM process in the presence of a supported Ni catalyst was studied. It has been shown that with an increase in the temperature of the TRM reaction from 600 to 800 °C the process performance improves (methane conversion: 36 → 94 %, carbon dioxide conversion: 57 → 97 %, hydrogen yield: 37→91 %, carbon monoxide yield: 44→ 94 %, molar ratio H2/CO: 1.5 → 1.7), and at a reaction temperature of 850 °C the process indicators are close to equilibrium values. It has been established that varying the O/C value and the composition of oxidants makes it possible to regulate the performance of TRM process. The optimal conditions for the TRM process were identified to achieve maximum efficiency of the catalytic processing of coal mine methane into hydrogen-containing gas: temperature - in the range of 800-850 °C, contact time - 0.15 s, linear feed rate - 160 cm/min and molar ratio of reagents in the initial feed - CH4 / CO2 / H2O / O2 = 1: 0.5 : 0.2 : 0.25.

Promising Directions in Chemical Processing of Methane from Coal Industry. Part 3. Catalytic Tests

For the processing of coal mine methane into hydrogen-containing gas, a catalytic process of methane tri-reforming (СH4 + O2 + CO2 + H2O) was proposed and its component reactions were studied – partial oxidation (СH4 + O2, POM), dry reforming (СH4 + CO2, DRM) and steam reforming (СH4 + H2O, SRM) of methane. Promoted nickel supported on aluminum oxide was used as a catalyst. Experiments were carried out by varying temperature (600–850 ºC), contact time (0.04–0.15 s), linear feed rate (40–240 cm/min) and composition of the reaction mixture (POM – СH4 : O2 : He = 1 : (0.5–0.7) : (3.3–3.4); DRM – СH4 : CO2 : He = 1 : (0.8–1.4) : (2.6–3.2); SRM – CH4 : H2O : He = 1 : (0.8–2.0) : (2.0–3.2)). Optimal reaction conditions were determined to ensure maximum efficiency of hydrogen production by reforming methane-containing mixtures of various compositions (temperature in the range of 800–850 ºC, contact time 0.15 s, linear feed rate 160 cm/min, molar ratio of CH4 : O2 = 1 : 0.5 for POM, CH4 : CO2 = 1 : 1 for DRM and CH4 : H2O = 1 : 1.1 for SRM). The degree of catalyst carbonization during the reactions was reduced (from 3 to 1.5% for POM, from 20.7 to 2.2% for DRM, and from 15.2 to 0.4% for SRM) due to an increase in the O/C molar ratio in the initial reaction mixture. Regulation of H2/CO molar ratio was achieved over a wide range (0.9–6.5). It has been shown that the hydrogen concentration in the resulting hydrogen-containing mixture is determined by the type of process and is equal to 30±5 vol.%.

β-glucosidase production by recombinant Pichia pastoris strain Y1433 under optimal feed profiles of fed-batch cultivation.

Pichia pastoris, a methylotrophic yeast, is known to be an efficient host for heterologous proteins production. In this study, a recombinant P. pastoris Y11430 was found better for β-glucosidase activity in comparison with a wild type P. pastoris Y11430 strain, and thereby, subjected to methanol intermittent feed profiling for β-glucosidase production. The results showed that at 72h of cultivation time, the cultures with 16.67% and 33.33% methanol feeding with constant rate could produce the total dry cell weight of 52.23 and 118.55g/L, respectively, while the total mutant β-glucosidase activities were 1001.59 and 3259.82 units, respectively. The methanol feeding profile was kept at 33% with three methanol feeding strategies such as constant feed rate, linear feed rate, and exponential feed rate which were used in fed-batch fermentation. At 60h of cultivation, the highest total mutant β-glucosidase activity was 2971.85 units for exponential feed rate culture. On the other hand, total mutant β-glucosidase activity of the constant feed rate culture and linear feed rate culture were 1682.25 and 1975.43 units, respectively. The kinetic parameters of exponential feed rate culture were specific growth rate on glycerol 0.228/h, specific growth of methanol 0.061/h, maximum total dry cell weight 196.73g, yield coefficient biomass per methanol ([Formula: see text]) 0.57 gcell/gMeOH, methanol consumption rate ([Formula: see text]) 5.76 gMeOH/h, and enzyme productivity ([Formula: see text]) 75.96 units/h. In conclusion, higher cell mass and β- glucosidase activity were produced under exponential feed rate than constant and linear feed rates.

Numerical study of chipping during friction element welding

Chipping phenomena during the friction element welding (FEW) process is investigated using finite element modeling. Intensive chipping is observed in a cast aluminum alloy when it is welded to a steel alloy. A Coupled Eulerian-Lagrangian scheme is used to investigate the underlying mechanisms enabling chipping. It is found that chipping is severe when the friction element initially contacts the workpiece and tends to reduce as the former progresses into the latter. Chipping decreases with the increase of rotational speed and the decrease of linear feed rate. Chipping can be minimized by using high rotational speeds coupled with low feed rates.

Development and investigation of the magnetorheological abrasive finishing (MRAF) system to nano-finish exterior cylindrical surfaces

ABSTRACT The invention of magnetorheological abrasive finishing (MRAF) techniques has been prompted by the ever-increasing demand for nano-finished exterior surfaces of cylindrical work samples. In the present study, a novel form of the MRAF system to nano-finish the exterior cylindrical surfaces of various diameters has been devised and their finishing mechanism is discussed. The finishing experiments have been carried out to examine the finishing capabilities of newly devised MRAF system. Taguchi’s parameter design approach has been employed to find the optimal combination of finishing parameters to achieve high-quality surface of S.S.-316 L cylindrical work-sample. The obtained results have been analyzed statistically which demonstrate that the chosen parameters namely F-to-S iron ratio, d.c. supply, work sample rotational speed and linear feed rate have significant effect on the percentage change in average surface roughness (%ΔRa). The effect of finishing time on Ra has also been explored, with the findings revealing that a minimum Ra value of 0.074 µm was attained after 60 minutes of finishing time, demonstrating the developed MRAF process’s superior capabilities.

Seam Formation in Laser Beam Micro-Welding with Spatial Power Modulation

When laser sources of high brilliance are used for the micro-welding of metals, small seam dimensions are generated. If the spatial power is modulated by a superposition of the linear feed rate and a circular-oscillatory movement of high frequency, the width of the seam is controlled by the amplitude of the circular movement. In this study, the irradiation pattern of the seam was calculated and reveals that some spots of the seam area are not irradiated, while other have been irradiated several times. The seam shapes were visualized with micro cross-sections for different laser powers, linear feed rates and oscillatory amplitudes. Thermal simulations were made to discuss the different seam shapes. A consequence of the oscillatory movement is the appearance of different solidification fronts, which are visible in the micro cross-sections.

Subaperture polishing of silicon asphere

Subaperture polishing of silicon aspheric optics using air-inflated membrane tool is reported in the present work. A faster approach for material removal has been applied for local material removal using inflated bonnet polishing tool. Optical quality surface finish on silicon asphere is obtained by applying more pressure and greater velocity on subaperture tool with less distortion on the polishing surface as compared to a larger tool. Further, less tool wear cost makes this process more economical for lower production requirements. The linear feed rate has been optimized to produce optical quality surface finish using less number of iterations. Stylus profilometer and optical profilometer have been used for aspheric surface characterization. The surface accuracy and surface roughness achieved are 127 nm and 1.44 nm, respectively.

Spot nanofinishing using ball nose magnetorheological solid rotating core tool

The spot nanofinishing of surface plays an important role for improving the surface quality of miniature mechanical, electronics, and optics components. The nano-level finishing of these miniature components is highly demanded in today’s industry to fulfill the operational and functional requirement. The principal innovation of the present work is generating uniform magnetic field at the end of a magnetizable rotating core tool for providing a uniform surface roughness on a spot finishing of precision components. To fulfill this requirement, a ball nose magnetorheological nanofinishing process based on solid rotating core tool is developed. The existing ball end magnetorheological finishing (BEMRF) process uses a rotating core with central hole for flow of polishing fluid at the tool end surface. Due to central hole inside the rotating core, a non-uniform magnetic flux density has been experienced at the tool end surface which may result in non-uniform surface roughness in spot finishing, i.e., on a fixed location without any X-Y-axis linear feed rates. The magnetostatic finite element analysis clearly revealed the uniform magnetic flux density at the end surface of the solid rotating core tool than existing BEMRF tool core having central hole. The experimentation has been carried out for spot finishing on ferromagnetic workpiece surface in order to study the variation in surface roughness values. The present ball nose magnetorheological finishing process with solid rotating core tool produced uniform average surface roughness values as 20 nm from 290 nm after 90 min of spot finishing on the ferromagnetic workpiece surface. The experimental results confirmed the effectiveness of generating uniform magnetic field at the end of a magnetizable rotating core tool for a spot uniform nanofinishing of precision components.

Angular feedrate interpolation for three-dimensional implicit curves

The paper presents an approach for angular feedrate interpolations for three-dimensional (3D) tool paths in multi-axis machining. The tool path is identified by a position curve assumed to be 3D implicit curve, and a tool orientation curve is obtained based on the position curve. The angular feedrate interpolations calculate the tool position and orientation at each sampling cycle based on specified angular feedrates and given tool paths. The paper relates analytically geometric properties of the prescribed path to rigid body motions along the path by angular feedrates and angular feed acceleration. The results are then used to develop the angular feedrate interpolation. The angular feedrate is further related to the linear feedrate, the contour error and the orientation error. Illustrations for complex implicit curve interpolation are provided with contour error and orientation error analysis. Further simulations are carried out to illustrate the effectiveness of the interpolation scheme for complex curves.

Linear and angular feedrate interpolation for planar implicit curves

In multi-axis CNC machining, a cutting tool combines translation and rotational movements with respect to a workpiece. This entails CNC interpolation to take angular feedrates defining the speed of the rotational movement into account, while current interpolations are overwhelmingly based on linear feedrates defining the speed of the translation movement. This paper considers linear and angular feedrate interpolations of 2D tool paths for multi-axis machining. A 2D tool path is identified by a position curve assumed to be a 2D implicit curve and a tool orientation curve based on the implicit curve. The paper will relate the angular feedrate to the linear feedrate along the tool paths. The result is then used to develop the angular feedrate interpolation from the linear feedrate interpolation. Detailed interpolation schemes for such hybrid feedrates as a constant linear feedrate with constrained angular feedrate (CLCA) and a constant angular feedrate with constrained linear feedrate (CACL) have further been constructed. A corrected interpolation scheme is further present to augment the initial interpolation. Example interpolations including a quadric curve, the nodal cubic and a quartic curve are carried out to illustrate the feasibility and effectiveness of the proposed approach.

Angular interpolations for planar implicit curves

In multi-axis CNC machining, a cutting tool combines translation movements and rotational movements with respect to a workpiece. This entails CNC interpolation to take angular feedrates defining the speed of the rotational movement into account, while current interpolations are overwhelmingly based on linear federates defining the speed of the translation movement. The paper presents an approach using angular feedrate interpolations for planar tool paths in multi-axis machining, where a planar tool path is identified by a position curve assumed to be a planar implicit curve and a tool-orientation curve is obtained based on the position curve. The angular feedrate interpolations calculate the tool position and orientation at each sampling cycle based on specified angular feedrates and given tool paths. The paper relates analytically geometric properties of the prescribed path to two-dimensional rigid body motions along the path by angular feedrates and angular feed acceleration. The results are then used to develop the angular feedrate interpolation and improve the interpolation from the deviation analysis. The angular feedrate is further related to the linear feedrate and the contour error. Comparison between existing linear interpolation and proposed angular interpolation is also presented under the maximum allowed contour error constraint. Further simulations are carried out to illustrate the effectiveness of the interpolation scheme for complex curves.

A mechatronic approach for analysing timber surfaces

Abstract The development of high speed planing and moulding machines has arguably progressed to the limits imposed by purely mechanical designs. To ensure an adequate surface finish and form with high linear feed rates, demanded on grounds of economy, requires a large number of knives (circa 20) which in turn requires a large cutter circumference. Problems of vibration, proud knives and other such process defects manifest themselves in the produced surface. A novel measuring system based on vision techniques is presented together with examples of usage as a post process analysis instrument and an in-process diagnostic tool. The measuring system utilises a novel embodiment which overcomes problems due to vibration and represents a significant step forward in measurement technology. The route is now open for the design of the truly intelligent machine which will adjust its operating parameters to produce the required surface quality of timber product at the maximum possible speed.