Inhibitor protection of steel from corrosion and hydrogen impregnation, and the technology of chemical cleaning of equipment in solutions of sulfuric and sulfamic acids

1986 ◽  
Vol 21 (4) ◽  
pp. 376-381
Author(s):  
A. K. Mindyuk ◽  
V. I. Sholok ◽  
O. P. Savitskaya ◽  
A. D. Tkach ◽  
Yu. S. Kost'
Keyword(s):  
Hydrogen Impregnation ◽  
Chemical Cleaning ◽  
Inhibitor Protection

Silicon Surface Chemical Treatments in Oxide/Nitride Dielectric Stack Properties

2002 ◽  
Vol 716 ◽  
Author(s):  
D. Jacques ◽  
S. Petitdidier ◽  
J.L. Regolini ◽  
K. Barla
Keyword(s):  
Oxygen Content ◽  
Oxide Thickness ◽  
Morphological Data ◽  
Electrical Characteristics ◽  
Electrical Measurements ◽  
Chemical Cleaning ◽  
Force Microscopy ◽  
Chemical Treatments ◽  
Atomic Force ◽  
Interfacial Oxygen

AbstractOxide/Nitride dielectric stack is widely used as the standard dielectric for DRAM capacitors. The influence of the chemical cleaning prior to the stack formation has been studied in this work. As a result, morphological data such as stack surface roughness (Atomic Force Microscopy) and silicon nitride (SiN) incubation time for growth are comparable for all the studied cases on <Si>. However, Tof-SIMS exhibits different oxygen content at the Si/stack interface following the different chemical treatments. Electrical measurements show comparable C-V and I-V results, for the same Equivalent Oxide Thickness (same capacitance at strong accumulation i.e.-3V) while the different studied interfaces bring different interface states density with lower values for higher interfacial oxygen content. For DRAM applications, a clear improvement in electrical characteristics is obtained under low interfacial oxygen content conditions. Results are compared in embedded-DRAM cells for which we developed an industrially compatible dielectric deposition sequence to obtain minimum leakage current with maximum specific capacitance and no particular linking constraints.

Leakage Current Reduction of Ni-MILC Poly-Si TFT Using Chemical Cleaning Method

2018 ◽  
Vol 28 (8) ◽  
pp. 440-444
Author(s):  
Kwang-Jin Lee ◽  
◽  
Doyeon Kim ◽  
Duck-Kyun Choi ◽  
Woo-Byoung Kim
Keyword(s):  
Leakage Current ◽  
Chemical Cleaning ◽  
Cleaning Method ◽  
Current Reduction

Enhancing Efficiency of Full-Scale Ultrafiltration Membrane Treatment for Increased Capacity and Lower Operating Costs

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
M.C. White PE ◽  
M.J. Kosterman
Keyword(s):  
Citric Acid ◽  
Water Treatment ◽  
Operating Costs ◽  
Percent Reduction ◽  
Chemical Cleaning ◽  
Optimization Program ◽  
Systematic Optimization ◽  
Percent Increase ◽  
Treatment Facilities ◽  
Membrane Treatment

At time of commissioning, the Racine, Wisconsin, USA ultrafiltration (UF) membrane treatment system fail short of meeting its operational goals concerning capacity and chemical cleaning intervals. The systematic optimization of this 189-million-litre-per-day (MLD) capacity UF system provided tangible operational benefits, which included a 30-percent reduction in power use, a 50-percent reduction in chlorine chemical use, a 36-percent reduction in citric acid use and a simultaneous 7-percent increase in net treatment capacity of the system. In addition, the optimization program reduced the level of buildup of foulants on the surface of the membranes. This paper summarizes the optimization procedures followed at Racine, discussing how similar measures may be applicable to other water treatment facilities.

Low-pressure membrane filtration with unconventional coagulation regimes

2005 ◽  
Vol 5 (5) ◽  
pp. 1-8 ◽  
Author(s):  
K.Y. Choi ◽  
B.A. Dempsey
Keyword(s):  
Activated Carbon ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Cross Flow ◽  
Chemical Cleaning ◽  
Sand Filters ◽  
Charge Neutralization ◽  
Floc Size ◽  
Filtration System ◽  
Pre Treatment

The objective of the research was to evaluate in-line coagulation to improve performance during ultrafiltration (UF). In-line coagulation means use of coagulants without removal of coagulated solids prior to UF. Performance was evaluated by removal of contaminants (water quality) and by resistance to filtration and recovery of flux after hydraulic or chemical cleaning (water production). We hypothesized that coagulation conditions inappropriate for conventional treatment, in particular under-dosing conditions that produce particles that neither settle nor are removed in rapid sand filters, would be effective for in-line coagulation prior to UF. A variety of pre-treatment processes for UF have been investigated including coagulation, powdered activated carbon (PAC) or granular activated carbon (GAC), adsorption on iron oxides or other pre-formed settleable solid phases, or ozonation. Coagulation pre-treatment is often used for removal of fouling substances prior to NF or RO. It has been reported that effective conventional coagulation conditions produced larger particles and this reduced fouling during membrane filtration by reducing adsorption in membrane pores, increasing cake porosity, and increasing transport of foulants away from the membrane surface. However, aggregates produced under sweep floc conditions were more compressible than for charge neutralization conditions, resulting in compaction when the membrane filtration system was pressurized. It was known that the coagulated suspension under either charge-neutralization or sweep floc condition showed similar steady-state flux under the cross-flow microfiltration mode. Another report on the concept of critical floc size suggested that flocs need to reach a certain critical size before MF, otherwise membranes can be irreversibly clogged by the coagulant solids. The authors were motivated to study the effect of various coagulation conditions on the performance of a membrane filtration system.

Membrane thickening of water works sludge

2001 ◽  
Vol 1 (5-6) ◽  
pp. 215-220
Author(s):  
A. Gillighan ◽  
S.J. Judd ◽  
R. Eyres
Keyword(s):  
Hydraulic Resistance ◽  
Reasonable Agreement ◽  
Chemical Cleaning ◽  
Solids Concentration ◽  
Significant Difference ◽  
Layer Resistance ◽  
Tubular Membranes ◽  
Resistance Data ◽  
Mechanical Cleaning ◽  
Dynamic Layer

The efficacy of ultrafiltration (UF) and microfiltration (MF) membranes was assessed for the concentration of actual waterworks sludges using crossflow tubular membranes operated at constant trans-membrane pressure. The MF membrane gave higher initial fluxes than the UF membrane but after 10 min of filtration the flux value and its decline tended to be very similar for both membranes operating under the same conditions. All membranes gave permeate product water of &lt;0.2 NTU and &lt;100ppb coagulant at all times. For both membranes mechanical cleaning, with sponge balls, was at least as effective as acid chemical cleaning, indicating that no significant permanent internal fouling occurred for these membrane materials. Hydraulic resistance data indicated a significant difference in the dynamic layer resistance between the two membranes. Whilst the UF membrane had a hydraulic resistance 3.7 times that of the MF membrane, the dynamic layer formed on the UF membrane during operation displayed a maximum hydraulic resistance almost nine times lower than that of the MF membrane operating under the same conditions. Correlation of cake resistance R versus feed solids concentration C for all the data generated for t&gt;0 demonstrated reasonable agreement with the expression R∝ca where a=0.37 in the current study. This trend has been recorded in previous reported studies, a varying between 0.33 and 0.62 depending on sludge dewaterability.

scholarly journals Optimal Cleaning Cycle Scheduling under Uncertain Conditions: A Flexibility Analysis on Heat Exchanger Fouling

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 93
Author(s):  
Alessandro Di Pretoro ◽  
Francesco D’Iglio ◽  
Flavio Manenti
Keyword(s):  
Safety Issue ◽  
Probability Distributions ◽  
Operating Conditions ◽  
Economic Losses ◽  
Optimal Time ◽  
Model Description ◽  
Chemical Cleaning ◽  
Uncertain Variables ◽  
Cycle Scheduling ◽  
Cleaning Cycle

Fouling is a substantial economic, energy, and safety issue for all the process industry applications, heat transfer units in particular. Although this phenomenon can be mitigated, it cannot be avoided and proper cleaning cycle scheduling is the best way to deal with it. After thorough literature research about the most reliable fouling model description, cleaning procedures have been optimized by minimizing the Time Average Losses (TAL) under nominal operating conditions according to the well-established procedure. For this purpose, different cleaning actions, namely chemical and mechanical, have been accounted for. However, this procedure is strictly related to nominal operating conditions therefore perturbations, when present, could considerably compromise the process profitability due to unexpected shutdown or extraordinary maintenance operations. After a preliminary sensitivity analysis, the uncertain variables and the corresponding disturbance likelihood were estimated. Hence, cleaning cycles were rescheduled on the basis of a stochastic flexibility index for different probability distributions to show how the uncertainty characterization affects the optimal time and economic losses. A decisional algorithm was finally conceived in order to assess the best number of chemical cleaning cycles included in a cleaning supercycle. In conclusion, this study highlights how optimal scheduling is affected by external perturbations and provides an important tool to the decision-maker in order to make a more conscious design choice based on a robust multi-criteria optimization.

Improving the performance of high-laser-damage-threshold, multilayer dielectric pulse-compression gratings through low-temperature chemical cleaning

2013 ◽  
Vol 52 (8) ◽  
pp. 1682 ◽  
Author(s):  
Heather P. Howard ◽  
Anthony F. Aiello ◽  
Justin G. Dressler ◽  
Nicholas R. Edwards ◽  
Terrance J. Kessler ◽  
...  
Keyword(s):  
Low Temperature ◽  
Pulse Compression ◽  
Damage Threshold ◽  
Laser Damage Threshold ◽  
Laser Damage ◽  
Chemical Cleaning ◽  
High Laser ◽  
Multilayer Dielectric

Studying the Efficiency of Inhibitors in Chemical Cleaning of Heat-and-Power Equipment by Citric Acid Solutions

2020 ◽  
Vol 67 (1) ◽  
pp. 68-71
Author(s):  
R. T. Burganov ◽  
A. R. Gilmullina ◽  
M. A. Kirilova ◽  
E. A. Kovrizhnykh
Keyword(s):  
Citric Acid ◽  
Power Equipment ◽  
Acid Solutions ◽  
Chemical Cleaning
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