Loss Of Process Efficiency Research Articles

Lignocellulose Fractionation Using Recyclable Phosphoric Acid: Lignin, Cellulose, and Furfural Production.

The conversion of lignocellulose into its building blocks and their further transformation into valuable platform chemicals (e. g., furfural) are key technologies to move towards the use of renewable resources. This paper explored the disentanglement of lignocellulose into hemicellulose‐derived sugars, cellulose, and lignin in a biphasic solvent system (water/2‐methyltetrahydrofuran) using phosphoric acid as recyclable catalyst. Integrated with the biomass fractionation, in a second step hemicellulose‐derived sugars (mainly xylose) were converted to furfural, which was in situ extracted into 2‐methyltetrahydrofuran with high selectivity (70 %) and yield (56 wt %). To further increase the economic feasibility of the process, a downstream and recycling strategy enabled recovery of phosphoric acid without loss of process efficiency over four consecutive cycles. This outlines a more efficient and sustainable use of phosphoric acid as catalyst, as its inherent costs can be significantly lowered.

Determination of conditions ensuring maximum operability of replaceable hard-alloy cutting plates during blade processing

This study is devoted to the definition of conditions ensuring maximum operability of replaceable hard alloy cutting plates during blade processing of hard-to-process materials, with assessment of the possibility to use the tool of Russian production without loss of processing efficiency, as well as the possibility to implement adjustments of regime conditions in non-stop mode, using cloud services in enterprises with network structure, thus supporting the implementation of smart production and the fourth industrial revolution.

Dynamics Modeling-Based Optimization of Process Parameters in Face Milling of Workpieces With Discontinuous Surfaces

AbstractFace milling is widely used in machining processes, aimed at providing workpieces with high surface quality. The chatter generated in face milling could lead to tremendous damage to machine tools, poor machined surface quality, and loss of processing efficiency. Most related researches have been focused on the modeling of spindle dynamics and discretization algorithms for chatter prediction. However, few published articles have taken the geometric characteristics of workpieces into consideration, especially for workpieces with discontinuous surfaces in face milling, which leads to poor accuracy of chatter prediction as well as the waste of processing efficiency. To overcome this shortage, a novel dynamic model for the face milling process is built in this paper, considering the cutting insert engagement based on the geometric characteristics of the workpieces and the tool path. The stability lobe diagrams (SLDs) applicable to workpieces with discontinuous surfaces are constructed. A process parameter optimization model is developed to maximize the chatter-free processing efficiency of the face milling process. The sensitivity analysis is utilized to simplify the objective function, and the genetic algorithm is employed to solve the optimization model. The proposed approach is validated by an experimental case study of an engine block, improving the chatter-free material removal rate by 53.3% in comparison to the classic approach.

Impact of membrane ageing on reverse osmosis performance – Implications on validation protocol

Ageing of reverse osmosis (RO) membrane due to irreversible deposition of foulants or by frequent exposure to chemical cleaning agents is expected to result in performance decline or complete membrane failure, leading to noncompliance and loss of process efficiency. Limited studies have related failures as a result of membrane ageing with integrity monitoring and measured virus removal. In the present study, an accelerated ageing method, whereby membranes were subjected to cyclic fouling, cleaning and hypochlorite exposure, was developed and performance benchmarked against passively and industrially aged samples. Membrane performance during accelerated ageing was evaluated with respect to permeability, online conductivity removal (LRVEC), rejection of spiked NaCl salt (LRVNaCl) and reduction of MS2 phage (LRVMS2). Both LRVEC and LRVNaCl correlated well with LRVMS2 (R2=0.8206 and 0.8514 respectively) for the samples tested in this study, LRVEC was 2–3 times lower than LRVMS2 and LRVNaCl was at least 4 times lower than the corresponding LRVMS2. Interestingly, removal of virus sized pathogens (MS2), LRVMS2 was constantly greater than 4 although salt rejection decreased to 80%. Given the difference in the hydrated radius of ions of NaCl (0.36 and 0.33nm for hydrated Na+ and Cl− ions) compared to MS2 phage (26nm), spiked salt rejection represents a highly conservative procedure for confirmation of LRVMS2 and was shown to provide an early indication of subtle damage induced by chemical cleaning. In addition, the cyclic cleaning method utilized in this study resulted in a more severe performance decline, at equivalent hypochlorite exposure, when compared to passive ageing procedures.

Oxidation-reduction potential (ORP) as a control parameter in a single-stage partial nitritation/anammox process treating reject water

Deammonification process appears to be a good alternative to treat reject water. In this thesis, control strategies were studied at pilot scale in order to optimise the deammonification process operated in a Moving Bed Biofilm Reactor (MBBR) for reject water treatment. The processes were monitored by microbial activity tests, Specific Anammox Activity (SAA), Oxygen Uptake Rate (OUR), and Nitrate Uptake Rate (NUR) tests, in order to measure the anammox, ammonium/nitrite oxidizers and denitrifiers activity. Aeration and redox as control parameters were tested. The results showed that intermittent aeration, with 15min non-aerated period in a one hour cycle, could reduce the aeration time without loss of process efficiency. A redox value of pE=0 gave the best operational condition even if there were different nitrogen loads applied in the system.Pilot scale deammonification MBBR was tested towards to mainstream conditions. The reactor was run at different temperatures (25-19°C) to test the process stability and it was seen that the process started to become unstable when the temperature was at 19°C. Moreover, the combined treatment line, Upflow Anaerobic Sludge Blanket (UASB) reactor and MBBR with deammonification process, was established with the aim of being applied in mainstream treatment. The study results indicated that when the influent of the deammonification process shifted from reject water to UASB effluent (NH4+-N=100 mg/l), the process began to show unstable performance.N2O was measured and compared in the deammonification process treating reject water in this study. Between 0.4% and 2 % of the nitrogen load was converted to N2O in pilot and full scale studies. The results indicated that there was no significant emission difference when the process was performed with continuous or intermittent aeration; the production and consumption of N2O was dependent on the nitrogen loads and DO concentration applied in the system.

Effect of the dilution of synthesis gas with nitrogen on the Fischer–Tropsch process for the production of hydrocarbons

The process of the production of hydrocarbons from synthesis gas diluted with nitrogen according to the Fischer–Tropsch method was investigated. It was experimentally established that inert-ballasted synthesis gas facilitated an increase in selectivity for C5+ and C35+ hydrocarbons and a decrease in selectivity for C1–C4 hydrocarbons. The dilution of synthesis gas improved heat exchange conditions in the reaction zone and decreased the synthesis temperature and a temperature gradient across the catalyst bed. A loss of process efficiency upon the dilution of synthesis gas can be compensated due to an increase in the gas space velocity. The applicability of diluted synthesis gas to the production of the high-molecular-weight C35+ hydrocarbons was demonstrated.

Intermittent aeration in one-stage partial nitritation/anammox process

This study investigated the influence of different aeration strategies, characterized by the ratio (R) between non-aerated and aerated phase duration and dissolved oxygen concentration (DO), on one stage partial nitritation/anammox process performance and efficiency treating reject water. The activity of anammox bacteria, ammonium oxidizers, nitrite oxidizers and denitrifiers was determined by measuring specific anammox activity (SAA), oxygen uptake rate (OUR) and nitrate utilization rate (NUR). The results showed that with the same DO level during continuous aeration and intermittent aeration R=1/3 (in one hour), nitrogen removal efficiencies were similar. This means that introduction of intermittent aeration with R=1/3 can shorten the duration of aeration without any loss of process efficiency. Around 17–20% of the total decrease in ammonium and nitrate occurred in the non-aerated phase when intermittent aeration with R=1/3 was applied. Moreover, introduction of non-aerated phases enhanced the activity of anammox bacteria and limited that of nitrite oxidizers.

Radioactive contamination of groundwater, special aspects and advantages of removal by reverse osmosis and nanofiltration

Contamination of drinking groundwater sources by naturally occurring radioactive materials (NORM) is a rather common problem in several regions in the Middle East and the Arabian Gulf. This contamination which represents public health risks and threat to environment complicates the processes of water treatment and increases their cost. The present work summarizes results of treatment of contaminated groundwater for rejection of radioisotopes.The removal of radium,Ra2+226, 228, uranium, as uranyl cation, UO22+, or carbonate complexes, UO2(CO3)22− and UO2(CO3)34−, and radon, Rn222, was investigated by reverse osmosis (RO) and nanofiltration (NF) in comparison with the most common conventional methods of ion exchange resins (IERs), chemical precipitation/softening, coagulation, and adsorption on surface active media.IERs and chemical softening realized radionuclide rejection from 32 to 95%, but with loss of process efficiency which attained 24% due to undesired parallel removal of similar ions. Removal by IERs was too dependent on resin form and water pH and required periodical shutdown for regeneration of resin which was slow and seldom complete. Softening required chemical dosing stoichiometric to isotope removal, disposal of contaminated sludge and subsequent water filtration. Coagulation failed to remove Ra. Its removal of U ranged from zero to 93% depending on pH due to formation of different U complexes.Only RO, parallel to water desalination, showed steady, high rejection of all isotopes which attained 99% without interference of similar ions, regeneration, or subsequent filtration. NF showed similar behavior, but with lower water desalination.

Effect of Rapid-Feed Step-Drilling Cycle and Super-High-Speed Spindle for High-Speed Micro Drilling in Printed Wiring Boards

A drilling technique using micro-drills of 0.2 mm or less in diameter and a super-high-speed spindle of 160000 rpm or more has been developed for drilling ultra-micro holes in printed wiring boards (PWBs). The drilling process requires higher reliability and quality to maintain the reliability of the electrical connection between circuit layers. On the other hand, higher processing efficiency is also required in PWBs manufacturing. To maintain high productivity, drilling is normally performed using a non-step method, but heat damage called B-RING occurs around the drilled holes with this method. To solve these problems without the loss of processing efficiency, we applied the rapid-feed step-drilling cycle method. We investigated the B-RING for drilling quality and evaluated the drilling time for processing efficiency under various drilling conditions. We found that using a rapid-feed step-drilling cycle with an appropriate number of steps and feed rates ensures a higher level of hole quality and processing efficiency compared with the conventional non-step drilling.