Industrial Operating Conditions Research Articles

Fault detection of RV reducer cycloidal gear under robot working conditions based on optimization improved envelope spectrum sideband energy ratio

Abstract Under industrial robot operating conditions, the cycloidal gear in the rotary vector(RV) reducer in the robot joint runs in a compound rotation motion with a low-speed and incomplete cycle, which complicates the fault detection for the cycloidal gear. Until now, no effective detection method for the cycloidal gear tooth fault under industrial robot operating conditions has been reported. Consequently, a method based on optimization improved envelope spectrum sideband energy ratio is proposed in this paper. Firstly, encoder signals are acquired and used to estimate the instantaneous angular speed (IAS) signals, which are then separated into two sets of data based on rotational directions. Then, the data corresponding to the approximately stable speed is truncated and connected to form a constructed signal. Next, the coherence of the constructed signal is calculated using the fast spectral coherence algorithm. Subsequently, the improved envelope spectrum sideband energy ratio is used as the objective value, and a global optimization algorithm is employed to determine the integration frequency band of the improved envelope spectrum (IES). Finally, the IES of this frequency band is calculated to obtain the fault-relatedorder characteristics. An RV reducer test rig was used for the experiment, and the analysis results from the proposed approach, cyclic spectral coherence (CSCoh), and improved envelope spectrum via feature optimization-gram (IESFOgram) were contrasted. Experiment results show that the proposed method is valid for the detection of tooth faults in the cycloidal gear of the RV reducer in robot operating conditions.

Porous Organic Cage as an Efficient Platform for Industrial Radioactive Iodine Capture

AbstractHerein, we firstly develop porous organic cage (POC) as an efficient platform for highly effective radioactive iodine capture under industrial operating conditions (typically ≥150 °C), ≤150 ppmv of I2). Due to the highly dispersed and readily accessible binding sites as well as sufficient accommodating space, the constructed NKPOC‐DT‐(I−) (NKPOC=Nankai porous organic cage) demonstrates a record‐high I2 uptake capacity of 48.35 wt % and extraordinary adsorption capacity of unit ionic site (~1.62) at 150 °C and 150 ppmv of I2. The I2 capacity is 3.5, 1.6, and 1.3 times higher than industrial silver‐based adsorbents Ag@MOR and benchmark materials of TGDM and 4F‐iCOF‐TpBpy‐I− under the same conditions. Furthermore, NKPOC‐DT‐(I−)Me exhibits remarkable adsorption kinetics (k1=0.013 min−1), which is 1.2 and 1.6 times higher than TGDM and 4F‐iCOF‐TpBpy‐I− under the identical conditions. NKPOC‐DT‐(I−)Me thus sets a new benchmark for industrial radioactive I2 adsorbents. This work not only provides a new insight for effectively enhancing the adsorption capacity of unit functional sites, but also advances POC as an efficient platform for radioiodine capture in industry.

PTFE as a Multifunctional Binder for High-Current-Density Oxygen Evolution.

Binder plays a crucial role in constructing high-performance electrodes for water electrolysis. While most research has been focused on advancing electrocatalysts, the application of binders in electrode design has yet to be fully explored. Herein, the in situ incorporation of polytetrafluoroethylene (PTFE) as a multifunctional binder, which increases electrochemical active sites, enhances mass transfer, and strengthens the mechanical and chemical robustness of oxygen evolution reaction (OER) electrodes, is reported. The NiFe-LDH@PTFE/NF electrode prepared by co-deposition of PTFE with NiFe-layered double hydroxide onto nickel foam demonstrates exceptional long-term stability with a minimal potential decay rate of 0.034mV h-1 at 500mA cm-2 for 1000 h. The alkaline water electrolyzer utilizing NiFe-LDH@PTFE/NF requires only 1.584V at 500mA cm-2 and sustains high energy efficiency over 1000 h under industrial operating conditions. This work opens a new path for stabilizing active sites to obtain durable electrodes for OER as well as other electrocatalytic systems.

High Entropy Alloys as High Performance Catalysts for Electrolytic Water Splitting

Renewable energy driven electrolytic water splitting is a required technology for low-carbon hydrogen production to achieve the goal of net-zero CO2 emission by 2050. This technology also serves as a necessary energy storage route to resolve the intolerable intermittency and unreliability issues of renewable energies. The prevailing of this hydrogen production technology however is restricted by the high cost of electricity. Consequently, developments of cost–effective highly efficient and stable electrocatalysts to drive the electrolytic water splitting reactions are the key. In terms of catalyst developments, mono-component systems are first explored, followed by multi–component systems, taking advantages of possible positive synergy between constituent components. Recently, a new class of multi-component catalyst systems, entropy-stabilized materials, including alloys, oxides, sulfides, phosphides, etc., emerges and is demonstrated promising performances toward electrocatalysis. In light of the variable and flexible element compositions, entropy-stabilized materials provide infinite and enormous potentials for the design of promising electrocatalysts. The key is to maximize the synergy between constituent components. High entropy alloys (HEA), defined as alloys composed of five or more major metallic elements, have been under intensive and extensive development in past fifteen years for their extraordinary mechanical, magnetic, corrosion, and catalytic properties. Herein, an equi–molar FeCoNiCuMo HEA on nickel foam was developed as a breakthrough catalyst for electrocatalytic water splitting, in terms of both activity and stability, in pH-universal media and in severe industrial operation conditions. Furthermore, a new catalytic phenomenon is discovered. Two different catalytic mechanisms function simultaneously on different constituents of the catalyst, and the synergistic interactions between the two categorical domains leads to catalytic kinetics faster than the theoretical limit set by a single rate-limiting step, Tafel step of the Volmer-Tafel route. A new kinetic model is developed to predict a new theoretical lower limit of Tafel slopes of 15 mV/dec based on a synergistic interaction between the two categorical domains of the high entropy alloy catalyst. This new development proves that the theoretical lower limit of Tafel slope of 30 mV/dec posed for the Volmer-Tafel mechanism functioning on a single component catalyst can be further reduced to 15 mV/dec through synergistic interactions between two categorical domains of a multi-component catalyst. It is demonstrated that high entropy materials, composed of five or more atomically/molecularly well-mixed major components, are intrinsically promising candidates for realization of quantum leaps in catalytic performances of catalysts.

Regulation of d‐Band Center of Ruthenium Sites via Electronic Complementary Effect of C60 Fullerene Molecules and Manganese Atoms for Efficient Alkaline Hydrogen Evolution

AbstractDeveloping advanced electrocatalysts is crucial for alkaline hydrogen evolution reaction (HER). A balance in adsorption energy for each reaction intermediate on the catalyst determines the overall catalytic rate. This balance is closely linked to the d‐band center, which is, in turn, controlled by the electronic structure of the active sites. Herein, C60 molecules with electron‐withdrawing properties and manganese (Mn) atoms with electron‐donating properties to drive charge redistribution on Ru active sites are strategically utilized. The synergistic and complementary effects of C60 and Mn regulate the d‐band centers of Ru sites to an optimal position, optimizing both the water adsorption and hydrogen desorption of the synthesized Ru catalysts. The constructed MnRu/C60‐3 catalyst exhibits a low overpotential of 8 mV at 10 mA cm−2, a large TOF value of 15.5 s−1, and a high mass activity of 2.39 A mg−1Ru at an overpotential of 100 mV in 1.0 m KOH. The anion exchange membrane water electrolyzer, assembled with MnRu/C60‐3 as the cathode, demonstrates excellent water electrolysis performance and high stability under industrial operational conditions. This work offers a fresh perspective on catalyst design principles by manipulating the d‐band centers of active sites using two complementary components.

Dry reforming of methane at high temperature and elevated pressure over nickel spinellized powder catalyst and pellets prepared from a metallurgical residue

AbstractThe coke deposition on catalysts is a significant problem in the dry reforming of methane at elevated pressures. Understanding and controlling the mechanisms of such deposition is essential in developing a techno‐economically viable industrial application for the production of synthesis gas and/or hydrogen. The patent‐pending nickel‐supported upgraded slag oxide (Ni‐UGSO) catalysts, in powder form, have demonstrated excellent performance and achieved equilibrium in dry reforming, steam reforming and mixed methane reforming in a gram‐scale laboratory packed bed reactor under barometric pressure. In this extended study, Ni‐UGSO pellets were prepared using the wet impregnation method. The pelletized form of said catalyst was studied under elevated pressure to imitate the industrial operating conditions in a kilogram‐scale laboratory packed bed reactor. The characterization of the fresh and used catalytic formulation produced data allowing the investigation of the physicochemical properties of catalysts and the effects of metal dispersion, reaction pressure and crystallite size, as well as the role of side reactions on the nature of the coke. The metal support nature favored the interaction between the Ni metal and spinels (UGSO), and the presence of the clay binder (kaolinite, quartz) improved the pellet morphology, provided higher Ni dispersion, maintained the crystallite size, reduced the coke formation and achieved similar or higher performance with respect to Ni‐UGSO powder despite having 85% less surface area. The Ni‐UGSO pellet showed negligible coke deposits from 1 to 6.5 atm and operated successfully for 24 h at 5.5 atm, 800°C and gas hourly space velocity 810 L/(h kg cat). This study provides new insight into the design of a more efficient and robust catalyst for methane dry reforming at elevated pressures, which is critical for potential future transfer at the industrial level.

Geoenvironmetal assessment of different types of cryolithic soils in Western Yakutia under the conditions of diamond-mining operations

The problems of geoenvironmental consequences of mining operations are especially acute in the arctic and subarctic regions, where the spread of permafrost significantly reduces the buffering capacity of landscapes. The article presents data on the content of heavy metals in the soil cover of the transient zone between the middle taiga and north taiga landscapes of Western Yakutia under the conditions of mining operations and assesses the resistance of different types of soils to heavy metals pollution. Field and laboratory works were carried out in August 2022. The heavy metals content was determined by atomic absorption spectrometry. Specialized software was used for analysis, such as MS Excel 2013, Statistica 12.0, and QGis 3.26.1. Calculation of organic forms of heavy metals in soil solutions was performed using the NICA-Donnan model. In the course of studies, the structure of the soil cover in the Nakyn kimberlite field in the conditions of the mining industrial complex operation was determined and a sketch map of the soil cover of the territory was compiled. The geochemical series of the studied heavy metals is as follows according to the degree of concentration of heavy metals in cryolithic soils: Pb > Zn > Ni > Cu > Cd > As > Hg. Positive correlations between humus and Cd, Pb, Zn, as well as the occurrence of synergism in the Pb–Cd, Zn–Pb, Zn–Cu pairs were revealed. The soils organic matter enhances migration of heavy metals. The man-made input of Ni and Zn in cryolithic soils will lead to increase of mobile fraction. Cd is more mobile in pale-yellow carbonate and cryogenic soils. The regional background level of heavy metals for these types of soils was calculated, which can be used in future works when the intensity of mining operations increases.

Production of Transportation Fuels from Fischer–Tropsch Waxes: Distillation, Blending, and Hydrocracking

Nowadays, transportation fuels such as diesel or gasoline are standardly produced from crude oil refining. These petroleum-based products are gradually replaced by more environmentally friendly sources, such as Fischer–Tropsch diesel fractions and other biofuels. The present work reports the distillation of Fischer–Tropsch (FTS) waxes and its use for fuel production by (i) blending the FTS wax diesel fraction with fossil diesel (7:93; 15:85; 30:70; and 50:50 wt.%) and (ii) blending the FTS wax heavy fraction (360–700 °C) with vacuum gas oil (10–50 wt.%) followed by hydrocracking at industrial operating conditions (T = 420 °C, WHSV = 0.5–1.0 h−1, P = 10.0 MPa). The obtained products in both cases were analysed and compared with standard EN590 for petroleum-diesel fuels. Overall, our results point to the suitability of the distillation of FTS waxes for renewable fuel production, either by straight blending of the diesel petroleum-based products or co-hydrocracking of the heavy fraction with vacuum gas oil.

CoFeBP Micro Flowers (MFs) for Highly Efficient Hydrogen Evolution Reaction and Oxygen Evolution Reaction Electrocatalysts.

Hydrogen is one of the most promising green energy alternatives due to its high gravimetric energy density, zero-carbon emissions, and other advantages. In this work, a CoFeBP micro-flower (MF) electrocatalyst is fabricated as an advanced water-splitting electrocatalyst by a hydrothermal approach for hydrogen production with the highly efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The fabrication process of the CoFeBP MF electrocatalyst is systematically optimized by thorough investigations on various hydrothermal synthesis and post-annealing parameters. The best optimized CoFeBP MF electrode demonstrates HER/OER overpotentials of 20 mV and 219 mV at 20 mA/cm2. The CoFeBP MFs also exhibit a low 2-electrode (2-E) cell voltage of 1.60 V at 50 mA/cm2, which is comparable to the benchmark electrodes of Pt/C and RuO2. The CoFeBP MFs demonstrate excellent 2-E stability of over 100 h operation under harsh industrial operational conditions at 60 °C in 6 M KOH at a high current density of 1000 mA/cm2. The flower-like morphology can offer a largely increased electrochemical active surface area (ECSA), and systematic post-annealing can lead to improved crystallinity in CoFeBP MFs.

Anomalous Detachment Behavior and Directional Reconstruction Regulation of Leaching-Type Precatalysts for Industrial Water Electrolyzers.

Current reconstruction chemistry studies are mainly operated at the laboratory scale, where the operating parameters are different from those used in industrial water electrolyzers. This gap leads to unclear reconstruction behaviors under industrial conditions and constrains the application of catalysts. Here, this work presents a new reconstruction mechanism and anomalous detachment phenomena observed in leaching-type oxygen-evolving precatalysts under industrial conditions, different from the reported results obtained under laboratory conditions. The identified detachment issues are closely linked to the production of a potassium salt separate phase, which proves sensitive to the local environment, and its instability easily leads to catalyst stripping from the substrate. By establishing detachment critical point and operating parameter-detachment correlation, a targeted reconstruction strategy is proposed to achieve smooth ligand leaching and effectively solve the detachment issue. Theoretical analyses validate the dual-site regulation in directionally reconstructed catalysts with optimized intermediate adsorption. Under industrial conditions, the coupled electrolyzer delivers an industrial-level current density at low cell voltage with prolonged durability, 1 A cm-2 at 2 V for over 340 h. This work bridges the gap of leaching-type precatalysts between laboratory test conditions and industrial operating conditions.

Analysis of patterns of electricity consumption in mining and processing enterprises

Mining and processing enterprises are large consumers of electricity, with a large share of energy costs in the cost of production. Thus, the price of electricity in the cost of production takes higher values for Hydrometallurgical Plant 1. In this regard, the development of energy consumption models that can be used as a basis for managing the energy consumption process is an important component of learning. It is important to analyze the energy consumption to estimate the electricity consumption under different operating conditions of the mining industry. In order to study and plan electricity consumption and develop methods for regulating electricity consumption, it is necessary to determine the place of each technological stage in the energy consumption balance [1]. This article examines the laws of electricity consumption in mining and processing enterprises. The study of such laws helps to determine the level of energy consumption management for the mining and processing plant.

The Influence of Machining Conditions on the Orientation of Nanocrystallites and Anisotropy of Physical and Mechanical Properties of Flexible Graphite Foils.

The physical and mechanical properties and structural condition of flexible graphite foils produced by processing natural graphite with nitric acid, hydrolysis, thermal expansion of graphite and subsequent rolling were studied. The processes of obtaining materials and changing their characteristics has been thoroughly described and demonstrated. The structural transformations of graphite in the manufacture of foils were studied by X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). A decrease in the average size of the coherent scattering regions (CSR) of nanocrystallites was revealed during the transition from natural graphite to thermally expanded graphite from 57.3 nm to 20.5 nm at a temperature of 900 °C. The rolling pressure ranged from 0.05 MPa to 72.5 MPa. The thickness of the flexible graphite foils varied from 0.11 mm to 0.75 mm, the density-from 0.70 to 1.75 g/cm3. It was shown that with an increase in density within these limits, the compressibility of the graphite foil decreased from 65% to 9%, the recoverability increased from 5% to 60%, and the resiliency decreased from 10% to 6%, which is explained by the structural features of nanocrystallites. The properties' anisotropy of graphite foils was studied. The tensile strength increased with increasing density from 3.0 MPa (ρ = 0.7 g/cm3) to 14.0 MPa (ρ = 1.75 g/cm3) both in the rolling direction L and across T. At the same time, the anisotropy of physical and mechanical properties increased with an increase in density along L and T to 12% with absolute values of 14.0 MPa against 12.5 MPa at a thickness of 200 μm. Expressed anisotropy was observed along L and T when studying the misorientation angles of nanocrystallites: at ρ = 0.7 g/cm3, it was from 13.4° to 14.4° (up to 5% at the same thickness); at ρ = 1.3 g/cm3-from 11.0° to 12.8° (up to 7%); at ρ = 1.75 g/cm3-from 10.9° to 12.4° (up to 11%). It was found that in graphite foils, there was an increase in the coherent scattering regions in nanocrystallites with an increase in density from 24.8 nm to 49.6 nm. The observed effect can be explained by the coagulation of nanocrystallites by enhancing the Van der Waals interaction between the surface planes of coaxial nanocrystallites, which is accompanied by an increase in microstrains. The results obtained can help discover the mechanism of deformation of porous graphite foils. The obtained results can help discover the deformation mechanism of porous graphite foils. We assume that this will help predict the material behavior under industrial operating conditions of products based flexible graphite foils.

Mel frequency mapping for intelligent diagnosis of rolling element bearings across different working conditions

The diagnosis of rolling bearing faults under constant operational conditions has garnered substantial scholarly interest, leading to the development of numerous robust and reliable diagnostic techniques. However, the dynamic and variable nature of industrial operating conditions complicates the acquisition of diagnostic data and renders fault prediction problematic, thus posing a formidable obstacle for fault diagnosis in unknown operational settings. Drawing an analogy from human communication, where listeners can comprehend speech irrespective of its speed or intensity, this paper aims to devise a methodology capable of distinguishing between various health states of machinery under fluctuating working conditions. To this end, we present a novel method, Mel Frequency Mapping Classification (MFMC), for nonlinear fault characteristic mapping and classification. This data-driven model, trained on datasets from known operational conditions, adapts well to new settings. Initially, vibration signals are converted from linear Hertz frequencies to nonlinear Mel frequencies through the Mel frequency mapping technique. Subsequently, the extracted fault signal features are transformed into Mel spectrograms, which serve as the input for the data-driven model. Finally, these Mel spectrograms are utilized as input variables for machine learning algorithms, specifically support vector machine (SVM) and multilayer perceptron (MLP), to accomplish automated, intelligent bearing diagnosis. To rigorously assess the efficacy of the proposed methodology in mechanical condition monitoring and intelligent diagnosis across diverse operational conditions, it was tested on two distinct datasets: CWRU and PU. These datasets encompass bearings with varying degrees and types of damage, situated in different components of the bearing, and operating under disparate conditions. Experimental results indicate that the proposed MFMC approach can obtain high cross-condition diagnosis accuracy on the training data under a single condition. This methodology offers a promising avenue for the intelligent diagnosis of mechanical equipment under cross-condition scenarios.

Experimental and modeling study of volatile organic compounds adsorption over zeolitic monolith adsorbent

In this study, a coupled mass and momentum model is developed and solved to describe the dynamic adsorption of a single adsorbate over honeycomb structured zeolite under industrial operating conditions. The Linear Driving Force approximation was used to predict the kinetics of adsorption to the solid-phase mass transfer and Navier Stokes equations were solved both radially and axially under laminar flow conditions through the honeycomb channels. To investigate the effect of key input parameters on model results, a sensitivity analysis was performed. Modeling and experimental results compared the effects of different initial concentrations and gas stream face velocities under a range of conditions to determine adsorption capacity, removal efficiency, and the 5% breakthrough time. Overall, the model output was in good agreement (less than 5% mean absolute relative error in concentration) with the experimental results under industrially relevant operating conditions. Modeling results illustrated that the radial velocity distribution over the monolith channels has an important effect on the shape of the breakthrough curve as well as the 5% breakthrough time. Both experimental results and modeling predictions showed that the long tails of the adsorption breakthroughs were the result of the non-uniform flow distribution, which resulted in delayed saturation of the outer honeycomb channels.

Reduction of precise machining centre column thermal deformations caused by changes in ambient temperature by means of liquid cooling

This paper describes various internal cooling methods and conditions aimed at reducing the displacements of the vertical jig centre column as an isolated unit caused by fluctuations in machining room temperature. The column's internal walls with horizontal and vertical ribs were cooled by the flow of liquid coolant from top to bottom. The cooling process was studied changing the rate of coolant flow and the method of flow generation. The interactions between the thermal phenomena occurring in the column and the conditions prevailing in the machine tool operating room and those occurring in the column areas cooled by the forced flow of liquid coolant are discussed. The FEA Abaqus System and numerical simulations were used to study the heat transfers and to accurately model the displacements. The results of the computations were experimentally validated in industrial operating conditions. On the basis of this study a precise model of the behaviour of the column in cooling conditions was created and the effectiveness of the considered ways of cooling the ribbed internal walls of the jig centre column was evaluated.It has been shown that the division of the column channel into several sections and the spraying of cooling liquid in combination with gravity flow significantly increases the cooling efficiency.

АНАЛИЗ НАПРАВЛЕНИЙ МОДЕРНИЗАЦИИ ПОТОЧНОГО УСТРОЙСТВА АНАЛИЗА ПАРАМЕТРОВ КАЧЕСТВА МОЛОКА

Currently, mechanization and robotization of modern dairy farms require the development of advanced technologies for assessing the quality of manufactured products. Information on the content of milk components such as fat, protein, lactose, somatic cells, progesterone and amino acids serves as the basis for assessing the quality of milk, as well as diagnosing the nutritional balance and clinical condition of cows. (Research Purpose) The research purpose is studying the potential possibilities of upgrading a flow scatterometric device for express analysis of milk quality parameters to ensure laboratory and field tests in conditions as close as possible to production operation. (Materials and methods) The current parameters of the device are considered and the potential possibilities of modernization are analyzed. (Results and discussion) The analysis of the modernization of the flow scatterometric device for express analysis of milk quality parameters revealed 4 ways: modernization of radiation sources; modernization of radiation receivers; modernization of the measuring chamber and its flushing process; modernization of the bracket and housing. Methods of modernization are proposed in all identified areas. (Conclusions) In the course of the study, it was determined that the current device is not sufficiently adapted to the conditions of industrial operation, therefore, to adapt and improve the efficiency of its operation, proposals for modernization were formed: integration of a second radiation source in the ultraviolet range, which will allow detecting protein molecules in the flow of milk-air mixture; the use of a CCD matrix as a radiation receiver for the transition to continuous information about the light scattering indicatrix; reduction of the discharge volume for measurements at a low filling level of the milk hose; development of an additional protective casing for moisture protection and vibration resistance.

A novel scalable polycationic melamine sponge-based filtration matrix for continuous ultrafast adsorption of anionic pollutants

Effective capturing of anionic pollutants from wastewater under industrial operating conditions, which requires high processing flux and fast adsorption rate remains a challenge. Here, a commercially available melamine sponge (MS) with reticulated 3D macroporous structures was covalently modified with positively charged moieties using a single step functionalization under mild conditions. The developed novel polycationic melamine sponge (MS+) was formed by a nucleophilic addition reaction between glycidyltrimethylammonium chloride (GMTA) and MS, followed by a self-propagation of GMTA. The produced MS+ possessed strong electrostatic interactions with different anions such as Rose Bengal (RB) and phosphates (P) under a wide pH range (3–11). The MS+ exhibited promoted static adsorption efficiencies of 400 mg g−1 (P) and 600 mg g−1 (RB), within 5 min and 60 s, respectively. Furthermore, the MS+ showed high stability and recyclability for up to 15 cycles of uses, and the recycling process was environmentally friendly by using 1 M NaCl as a releasing solution. Benefiting from fast flow through the macroporous MS+ and highly positive charged skeleton, the MS+ was applied for rapid dynamic enrichment process of P from real manure wastewater with an enrichment factor of 4.4. Utilization of the MS+ as the substrate brings additional advantages such as low cost, availability, and flexibility to fit into existing filtration devices. The developed MS+ could be expanded for enrichments of other anionic species from various polluted water sources.

The reaction characteristics and mechanism of polymer non-catalytic reduction (PNCR) for NOx removal

To overcome the defects of the traditional selective non-catalytic reduction (SNCR) process (e.g., low efficiency, narrow temperature range), a new modified SNCR technology based on the solid complex polymer reducing agents, also called polymer non-catalytic reduction (PNCR), was investigated both in the laboratory and pilot scale to reveal its reaction characteristics and mechanism. The PNCR process demonstrates excellent removal efficiency (about 90%) of NO in furnace in the wide temperature range (850–1150 °C), and possesses promising application feasibility with an average NOx emission concentration of 68.72 mg·m−3 even on unstable industrial operating conditions. The NO removal behaviors influenced by O2, temperature, or water steam illuminate the unique O2-independent and H2O-promoted reaction characteristics of PNCR in the wide temperature range. The thermogravimetric infrared spectra/mass spectrometry (TG-IR/MS) results further reveal a pyrolysis-assisted formation mechanism of active NH2/NH free radicals without the requirement of O2 and high temperature, which avoids the overoxidation of active radicals and accounts for the wide denitrification temperature window, low oxygen compliance and high denitrification efficiency of PNCR process. The excellent NO removal performance as well as the unique reaction characteristics/mechanism of PNCR forebode its broad industrial application prospect in the field of flue gas cleaning.

Permylene™ membrane technology: An efficient approach to separate propylene from propane

Permylene™ demonstration system (PDS), a membrane-based pilot unit for olefin/paraffin separation, is designed and fabricated by Imtex Membranes Corp. (Imtex). The PDS, equipped with pilot-scale Permylene™ elements, is capable of treating up to 3 kg/h of olefin/paraffin mixture. The PDS unit is installed in Imtex's testing lab in Mississauga, Ontario, Canada. Various plant-collected and lab-blended olefin/paraffin mixtures involving ethylene/ethane (C2), propylene/propane (C3), and butene/butane (C4) have been assessed on the unit. This paper is focused on the application of PDS for C3 separation, and a series of remarkable performances that have been achieved by the Permylene™ membrane and PDS unit. Propylene purity of over 98.5 vol% in the permeate/product stream has been reached over a wide range of propylene recovery rates, which could offer significant flexibility to meet various industrial operation conditions. Furthermore, the PDS unit demonstrates its stability and efficiency with 1200 hrs of continuous C3 permeation. Finally, a case study of recovering 90 % of propylene from 15,000 kg/h of C3 is performed to estimate energy consumption in commercial applications. The energy consumption of the Permylene™ process is calculated and compared with that of the distillation process. The result indicates that the energy consumption in PDS is extremely low, equal to only 8 % of that required in distillation. The study undeniably validates Permylene™'s remarkable capability for C3 separation, highlighting its potential as a viable and energy-efficient alternative to traditional distillation.

Experimental validation of the theoretical ejector model in a low-grade waste heat refrigeration system using R1233zdE as a working fluid

Rising electricity prices and environmental regulations make it increasingly economically justifiable to utilize low-temperature waste heat, generated as a by-product of many technological processes. One potential application is the conversion of heat into cooling capacity using an ejector refrigeration system, to replace conventional electric-consuming cooling systems. Such systems, despite numerous descriptions in the literature, have not found industrial applications up to date. This work presents experimental results on the first commercial prototype cooling system driven by 200 kW waste heat of ultra-low temperature between 60 °C and 70 °C coming from the oil system of air compressors operating under real industrial operating conditions. A refrigeration system configuration based on the use of heat recovery downstream of the ejector and splitting the waste heat recovery heat exchanger into two stages was applied. The low GWP and low-pressure HFO R1233zd(E) refrigerant was used as a working fluid. The high-temperature cooling parameters, equivalent to the glycol temperature of 16 °C/19 °C (outlet/inlet of the evaporator), were examined and the COP of 0,25 was obtained. To obtain such a promising COP value, the critical and subcritical parameters of the ejector were investigated. Based on the experimental results the validation of the ejector theoretical model was performed for low-pressure refrigerant. The ejector component characteristic efficiencies were optimized for the ejector calculation model, and ejector key performance parameters were estimated to a high accuracy. The average relative error in the estimation was 7.1%, 4.5%, and 13.7% for the mass entrainment ratio, pressure ratio and ejector total efficiency, respectively. The resulting accuracy is sufficient from the perspective of refrigeration system design.