scholarly journals Research on the New Drive of a Laboratory Screen with Rectilinear Vibrations in Transient States

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8444
Author(s):  
Jacek Feliks ◽  
Paweł Tomach ◽  
Dariusz Foszcz ◽  
Tomasz Gawenda ◽  
Tomasz Olejnik
Keyword(s):  
Vibration Amplitude ◽  
Vertical Direction ◽  
Drive System ◽  
Major Influence ◽  
Stable Operation ◽  
Correct Operation ◽  
Transient States ◽  
Start Up ◽  
Acceleration Sensors ◽  
Positive Effect

The paper presents the results of research on the vibrating motion of a laboratory screen with a rectilinear (segmental) trajectory of vibrations during its start-up and braking. The investigations were carried out on a modernized stand equipped with a system of two vibrating motors applied in newer solutions of industrial screens, which are mounted directly on the riddle. The tests were carried out for three different frequencies using three-axis acceleration sensors. The analysed parameter was the increase in the amplitude of vibrations in transient states compared to the amplitude during the stable operation of the device. The maximum multiplication of the vibration amplitude of the classic drive system during start-up was 9.7 (mm/mm) in the vertical direction and 5.7 (mm/mm) for the new system. During braking, the maximum multiplication of the vibration amplitude of the classic drive system was 6.9 (mm/mm) vertically, while for the drive system with vibration motors, it was 11.4 (mm/mm). The absence of flexible couplings in the drive system reduces the damping of vibrations and increases the value of amplitude during the start-up and free braking of the machine. This does not have a major influence on the correct operation of the machine in a steady state. However, the use of the new drive system resulted in a significant reduction in power demand and shortened the start-up time, which has a positive effect on the operating costs of the machine.

P-Removal in Completely Mixed Systems

1985 ◽  
Vol 17 (11-12) ◽  
pp. 325-326 ◽  
Author(s):  
H J. G. W. Donker ◽  
P. Opic ◽  
H. P. de Vries
Keyword(s):  
Mixed System ◽  
Domestic Waste ◽  
Recirculation Flow ◽  
Start Up ◽  
Significant Difference ◽  
Aerobic Reactor ◽  
The Difference ◽  
Positive Effect ◽  
Mixed Systems ◽  
P Removal

Ca. 60 % of the Dutch activated sludge plants consist of completely mixed systems, experiments have been carried out in completely mixed pilot plants to study the biological P-removal. The research was carried out in two pilot plants. The pilot plants consisted of: anaerobic reactor, anoxic reactor, aerobic reactor and a clarifier. All the reactors were completely mixed. Both plants were fed with settled domestic waste water at a sludge loading of 400 and 250 g COD/kg sludge.day respectively. The results are given below:sludge loading (g COD/kg sludge.day)400400250ratio Anaerobic : Anoxic : Aerobic1: 1:2,71:1:4,11:1:2,7P-removal (%)802875N-removal (%)505065COD-removal (%)858585 It has been shown that there is no significant difference between the results at the two different sludge loadings. Remarkable is the difference between the ratio 1:1:2,7 in combination with the internal recirculation flow anoxic-anaerobic of 160 % and the ratio 1:1:4,1 with a recirculation flow of 30 %. During the start-up at a sludge loading of 250 g COD/kg sludge.day and an internal recirculation flow of 30 %, bulking sludge developed almost immediately. The Premoval was completely disturbed. Increasing the internal recirculation flow to 160% had a positive effect on settling properties and P-removal. This investigation has pointed out that a completely mixed system is suitable for biological P-removal, without negatively affecting the nitrification. Important factors in the process are the ratio anaerobic:anoxic:aerobic and the recirculation flows.

scholarly journals Solidification Pattern of Si-Alloyed, Inoculated Ductile Cast Irons, Evaluated by Thermal Analysis

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 846
Author(s):  
Iuliana Stan ◽  
Denisa Anca ◽  
Stelian Stan ◽  
Iulian Riposan
Keyword(s):  
Cast Iron ◽  
Eutectic Reaction ◽  
Influencing Factor ◽  
Cooling Curve ◽  
Major Influence ◽  
Cast Irons ◽  
Minor Elements ◽  
Si Content ◽  
Si Effect ◽  
Positive Effect

The solidification cooling curve itself as well as its first derivative, and related temperatures, reported to the calculated equilibrium temperatures in stable and metastable solidification systems, are used to predict the solidification characteristics of the cast iron. Silicon, as the most representative cast iron element, and inoculation, as graphitizing metallurgical treatment, have a major influence on the transition from the liquid to the solid state. Six experimental programs are performed, with Si content typically for non-alloyed (<3.0% Si), low (3.0–3.5% Si) and medium alloyed (4.5–5.5% Si) ductile cast irons, as Si-content increasing, and inoculation simultaneous effects. Silicon is an important influencing factor, but the base and minor elements also affect the equilibrium eutectic temperatures, much more in the Fe-C-Si-Xi stable system (15–20 °C) than in the metastable system (5–10 °C), comparing with their calculation based only on a Si effect (Fe-C-Si system). The highest positive effect of inoculation is visible in non-Si alloyed cast irons (2.5% Si): 9–15 °C for the eutectic reaction and 3 to 4 times increased at the end of solidification (37–47 °C). Increased Si content decreases inoculation power to 7–9 °C for low alloying grade (up to 3.5% Si), with the lowest contribution at more than 4.5% Si (0.3–2.0 °C). 2.5–3.5% Si ductile cast irons are more sensitive to high solidification undercooling, especially at the end of solidification (but with a higher efficiency of inoculation), compared to 4.5–5.5% Si ductile cast irons, at a lower undercooling level, and at lower inoculation contribution, as well.

Dynamic Simulation of Full Start-Up Procedure of Heavy Duty Gas Turbines

2001 ◽  
Author(s):  
J. H. Kim ◽  
T. W. Song ◽  
T. S. Kim ◽  
S. T. Ro
Keyword(s):  
Gas Turbines ◽  
Guide Vane ◽  
Inlet Guide Vane ◽  
Stable Operation ◽  
Heavy Duty ◽  
Operating Characteristics ◽  
Fully Implicit ◽  
Start Up ◽  
Full Speed ◽  
Stage Characteristic

A simulation program for transient analysis of the start-up procedure of heavy duty gas turbines for power generation has been constructed. Unsteady one-dimensional conservation equations are used and equation sets are solved numerically using a fully implicit method. A modified stage-stacking method has been adopted to estimate the operation of the compressor. Compressor stages are grouped into three categories (front, middle, rear), to which three different stage characteristic curves are applied in order to consider the different low-speed operating characteristics. Representative start-up sequences were adopted. The dynamic behavior of a representative heavy duty gas turbine was simulated for a full start-up procedure from zero to full speed. Simulated results matched the field data and confirmed unique characteristics such as the self-sustaining and the possibility of rear-stage choking at low speeds. Effects of the estimated schedules on the start-up characteristics were also investigated. Special attention was paid to the effects of modulating the variable inlet guide vane on start-up characteristics, which play a key role in the stable operation of gas turbines.

Quick start-up and stable operation of a one-stage deammonification reactor with a low quantity of AOB and ANAMMOX biomass

2019 ◽  
Vol 654 ◽  
pp. 933-941 ◽  
Author(s):  
Yifeng Yang ◽  
Yuan Li ◽  
Zaoli Gu ◽  
Feng Lu ◽  
Siqing Xia ◽  
...  
Keyword(s):  
Stable Operation ◽  
One Stage ◽  
Start Up

The Study Summarize of Computational Method on Transition Process in Hydropower Units

2013 ◽  
Vol 457-458 ◽  
pp. 1531-1537
Author(s):  
Bi Ying Wu ◽  
Ning Tang ◽  
Shui Guang Tong
Keyword(s):  
Transient Process ◽  
Transition Process ◽  
Computational Method ◽  
Stable Operation ◽  
Calculation Methods ◽  
Generation System ◽  
Water Power ◽  
Optimization Study ◽  
Start Up ◽  
Power Generation System

In the operation of the hydropower units, it often come across condition changes such as start-up, normal stop, increase or decrease the load and load rejection. This will cause the hydraulic transient process of the water power generation system, which is of great significance to the safe and stable operation of hydropower station. This paper analyzes the method to calculate the transient process of hydropower unit and expounds the principle of all kinds of calculation methods and steps to lay a foundation for further optimization study.

scholarly journals Investigation of transitional processes of vibration machine with inertionic vibrator and asynchronous motor

2021 ◽  
Vol 2 (133) ◽  
pp. 97-109
Author(s):  
Dmytro Kononov ◽  
Viktor Yermokratiev ◽  
Yevhen Miroshnyk
Keyword(s):  
Experimental Data ◽  
Differential Equations ◽  
Nonlinear Differential Equations ◽  
Asynchronous Motor ◽  
Oscillation Amplitude ◽  
Mining Industry ◽  
Stable Operation ◽  
Vibration Machine ◽  
Start Up ◽  
Quality Of Products

Strict compliance with technological requirements in the production of steel is one of the main factors that determine the quality of products. In the mining industry, at metallurgical enterprises and transport hubs, all kinds of vibrating machines are widely used, and in particular vibrating conveyors (VTM): vibrating conveyors, vibrating conveyors and feeders, vibrating screens and screen feeders, and vibratory loaders. The main type of drive of such machines is an inertial drive, which consists of unbalanced vibrators. This drive is simple and has been widely used in vibrating machines of various types. To ensure stable operation (constancy of the oscillation amplitude when changing any system parameters) of such a vibrating machine with an inertial drive, a resonant setting is used. In this regard, there are difficulties that arise during start-up and run-out of the vibrating feeder: increasing the amplitude of oscillations, load on the foundation, power consumption, which leads to the fact that the motor does not reach rated speed and fails during start-up. Purpose: to study the dynamics of transients in VTM, which accompany the start of VTM from rest and run. The idea of the work is computer simulation of VTM dynamics based on numerical integration of a system of nonlinear differential equations describing the motion of a machine. As well as comparing them with experimental data. A mathematical model of VTM has been developed, differential equations of VTM motion have been compiled taking into account the characteristics of an induction motor. To solve the system of differential developed a program in the application Simulink. The obtained dependences confirm the increase in the amplitude of oscillation of the VTM tray when empty and stop VTM, which must be taken into account to calculate the parameters of the systems with vibrating machines. The experimental data are compared with the calculated ones, there is a good coincidence of results.

scholarly journals A study of nonlinear coupling dynamic characteristics of the cold rolling mill system under different rolling parameters

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401771370 ◽  
Author(s):  
Hai Xu ◽  
Ling-Li Cui ◽  
De-Guang Shang
Keyword(s):  
Fault Diagnosis ◽  
Cold Rolling ◽  
Dynamic Characteristics ◽  
Rolling Mill ◽  
Vibration Amplitude ◽  
Strip Thickness ◽  
Drive System ◽  
Nonlinear Coupling ◽  
Cold Rolling Mill ◽  
Coupling Dynamic

The dynamic characteristics of the mill and the drive system are mutually coupled and affected closed-loop system. However, most research has considered only the vibration of the drive system or the vibration of the mill to determine the cause of the accident in the equipment condition monitoring and fault diagnosis process. Condition monitoring and fault diagnosis based on this type of approach can lead to misdiagnosis or missed diagnosis in determining faults in actual systems. So, in this study, a dynamic model of the coupling between a mill and its drive system was developed to study the interaction of the mill and the drive system with the goal of increasing the accuracy of diagnostic methods and to improve the quality of the rolled material. A nonlinear coupling dynamic model was formulated to represent the relation between the gearbox vibration amplitude and various time-varying parameters to study the effects of various parameters on the drive system vibration characteristic under unsteady lubrication. Simulations results showed that increasing the strip speed, the input strip thickness, or the output strip thickness or decreasing the lubricating oil temperature or the roller radius caused the vibration amplitude of the drive system to increase. The vibration frequency caused by variations in the strip inlet or outlet thickness can be transmitted to the drive system, and gear meshing frequency of the gearbox can be transmitted to the mill. Test data from an actual cold rolling mill verified the accuracy of the model. The model was shown to be capable of simulating the mutually coupled and affected mechanism between a mill and its drive system.

scholarly journals Exploring the Effects of Trust and Its Outcomes in B2B Relationship Stages: A Longitudinal Study

2020 ◽  
Vol 12 (23) ◽  
pp. 9937
Author(s):  
Hong-Youl Ha
Keyword(s):  
Firm Performance ◽  
Social Exchange ◽  
Social Exchange Theory ◽  
Temporal Dynamics ◽  
Start Up ◽  
B2b Relationships ◽  
The Impact ◽  
Business To Business ◽  
Positive Effect ◽  
Over Time

Temporal dynamics in business-to-business (B2B) relationships are the evolution of B2B relationship stages. This study offers new insights in examining the impact of the temporal dynamics on firm performance during the B2B relationship stages. Drawing on B2B stage models, social exchange theory and the evolution of trust, the results show that the link between trust and firm performance weakens when a relationship between two parties reaches a particular stage. trust has a positive effect on firm performance in the same period; however, this positive effect decreases over time. Thus, the impact of trust on firm performance is insignificant in subsequent relationship stages in the start-up context. The impact of trust on firm performance is unstable and decreases over time. This study offers new theoretical and managerial insights regarding the temporal dynamics in B2B relationships.

scholarly journals Microbial Structure and Energy Generation in Microbial Fuel Cells Powered with Waste Anaerobic Digestate

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4712
Author(s):  
Dawid Nosek ◽  
Agnieszka Cydzik-Kwiatkowska
Keyword(s):  
Fuel Cells ◽  
Microbial Fuel Cells ◽  
Volatile Fatty Acids ◽  
Current Knowledge ◽  
Oxygen Demand ◽  
Electricity Production ◽  
Stable Operation ◽  
Microbial Structure ◽  
Microbial Composition ◽  
Start Up

Development of economical and environment-friendly Microbial Fuel Cells (MFCs) technology should be associated with waste management. However, current knowledge regarding microbiological bases of electricity production from complex waste substrates is insufficient. In the following study, microbial composition and electricity generation were investigated in MFCs powered with waste volatile fatty acids (VFAs) from anaerobic digestion of primary sludge. Two anode sizes were tested, resulting in organic loading rates (OLRs) of 69.12 and 36.21 mg chemical oxygen demand (COD)/(g MLSS∙d) in MFC1 and MFC2, respectively. Time of MFC operation affected the microbial structure and the use of waste VFAs promoted microbial diversity. High abundance of Deftia sp. and Methanobacterium sp. characterized start-up period in MFCs. During stable operation, higher OLR in MFC1 favored growth of exoelectrogens from Rhodopseudomonas sp. (13.2%) resulting in a higher and more stable electricity production in comparison with MFC2. At a lower OLR in MFC2, the percentage of exoelectrogens in biomass decreased, while the abundance of genera Leucobacter, Frigoribacterium and Phenylobacterium increased. In turn, this efficiently decomposed complex organic substances, favoring high and stable COD removal (over 85%). Independent of the anode size, Clostridium sp. and exoelectrogens belonging to genera Desulfobulbus and Acinetobacter were abundant in MFCs powered with waste VFAs.

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