Review of naphthenic acid corrosion in oilrefining

Slavcheva, E.; Shone, Bryan; Turnbull, A.

doi:10.1179/000705999101500761

Cited by 226 publications

(168 citation statements)

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“…2 However, it has been known for some time that there is considerable scatter in plots of low and intermediate values of TAN versus crudes' corrosiveness. 3,4 For this reason, we have investigated the possibility of employing electrochemical techniques to characterize the corrosivity of an unknown crude.…”

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confidence: 99%

“…Experiments in dichloromethane were conducted using 0. (3) small amplitude (±0.010 V) cyclic polarization experiments and (4) large amplitude (±0.5 V) square-wave polarization tests with step widths of 5s, 50s and 500s. Both types of reversibility experiments ( i.e., (3) and (4)) were carried out in a two-electrode cell in which an UME of PdH was the WE and a large PdH foil served as a CE/RE.…”

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confidence: 99%

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Palladium Hydride as a Reference Electrode in Aprotic Solutions

Patrick

Chakravarti

Devine

2015

J. Electrochem. Soc.

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The results of a variety of electrochemical tests indicate palladium hydride (β-PdH) functions as a thermodynamic reference electrode in three aprotic solutions containing H 2(g) and solvents of dichloromethane, dimethylsulfoxide, and acetonitrile. For enhanced electrical conductivity all solutions contained 0.2 M of an ionic liquid, 1-methyl-3-butyl imidazolium tetrafluoroborate. As is required of all thermodynamic reference electrodes (i) the potential of β-PdH was stable, (ii) its small amplitude anodic and cathodic polarization were reversible, and (iii) it exhibited Nernstian behavior assuming that the hydrogen cation activity is controlled by the concentration of adsorbed hydrogen, which is set by the partial pressure of H 2(g) . © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0421603jes] All rights reserved.Manuscript submitted October 30, 2015; revised manuscript received December 8, 2015. Published December 17, 2015 Palladium hydride (PdH) has long been used as a redox system for measurement of pH, and as a titration electrode in nonaqueous solvents.1 The present investigation of PdH as a reference electrode in aprotic solutions arose from an interest in applying electrochemical techniques to assess the corrosivity of crude oil. Specifically, the current study was an offshoot of our efforts to use cyclic voltammetry of platinum in crude oil as a means for identifying the presence and concentrations of redox active corrosive species, such as naphthenic acids, which contribute significantly to the corrosion of steels in crude oil.At present, TAN (Total Acid Number) is employed to estimate the corrosiveness of a crude oil. TAN is the number of mg of potassium hydroxide required to neutralize the acids present in a 1 g sample of crude.2 However, it has been known for some time that there is considerable scatter in plots of low and intermediate values of TAN versus crudes' corrosiveness.3,4 For this reason, we have investigated the possibility of employing electrochemical techniques to characterize the corrosivity of an unknown crude.There are two major obstacles preventing the use of electrochemical techniques to assess the corrosivity of crudes. The first is the high electrical resistivity of crude oil. In a separate study we have addressed the resistivity issue by a combination of the use of ultramicroelectrodes (UME) and the addition of a supporting electrolyte, which does not itself affect the solution's corrosivity. 5 Many virgin crude oils have electrical resistivities on the order of 1 × 10 8 ohm•cm, which, although it is a high value, is nevertheless sufficiently low to permit electrochemical testing by employing UMEs without the need for a supporting electrolyte. However, the main concern over a crude's corrosivity relates to co...

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Palladium Hydride as a Reference Electrode in Aprotic Solutions

Patrick

Chakravarti

Devine

2015

J. Electrochem. Soc.

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“…Consequently, the reaction mechanism leading to sulphide corrosion should partly be impacted by adsorption and accelerated by saturated free fatty acids composing a considerable proportion of waste lard. Moreover, the increasing temperature is known to play a vital role in governing the mechanism of naphthenic acid corrosion either by chemical or electrochemical mechanisms [28]. The latter is more dependent on thermal activation as a greater rate of dissociation of the weak acids occurs at elevated temperatures [29].…”

Section: Reactor Experimentsmentioning

confidence: 99%

Hydrogen Sulphide Corrosion of Carbon and Stainless Steel Alloys Immersed in Mixtures of Renewable Fuel Sources and Tested Under Co-processing Conditions

Gergely¹,

Locskai²,

Szabó³

et al. 2016

Hungarian Journal of Industry and Chemistry

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HUNGARYIn accordance with modern regulations and directives, the use of renewable biomass materials as precursors for the production of fuels for transportation purposes is to be strictly followed. Even though, there are problems related to processing, storage and handling in wide range of subsequent uses, since there must be a limit to the ratio of biofuels mixed with mineral raw materials. As a key factor with regards to these biomass sources pose a great risk of causing multiple forms of corrosion both to metallic and non-metallic structural materials. To assess the degree of corrosion risk to a variety of engineering alloys like low-carbon and stainless steels widely used as structural metals, this work is dedicated to investigating corrosion rates of economically reasonable engineering steel alloys in mixtures of raw gas oil and renewable biomass fuel sources under typical coprocessing conditions. To model a desulphurising refining process, corrosion tests were carried out with raw mineral gasoline and its mixture with used cooking oil and animal waste lard in relative quantities of 10% (g/g). Co-processing was simulated by batch-reactor laboratory experiments. Experiments were performed at temperatures between 200 and 300ºC and a pressure in the gas phase of 90 bar containing 2% (m 3 /m 3 ) hydrogen sulphide. The time span of individual tests were varied between 1 and 21 days so that we can conclude about changes in the reaction rates against time exposure of and extrapolate for longer periods of exposure. Initial and integral corrosion rates were defined by a weight loss method on standard size of coupons of all sorts of steel alloys. Corrosion rates of carbon steels indicated a linear increase with temperature and little variation with composition of the biomass fuel sources. Apparent activation energies over the first 24-hour period remained moderate, varying between 35.5 and 50.3 kJ mol -1 . Scales developed on carbon steels at higher temperatures were less susceptible to spall and detach. Nonetheless, moderate deceleration of corrosion rates as a function of time are due to the less coherent, frequently spalling and low compactness, higher porosity of the scales evolved at lower and higher temperatures, respectively. On the surface of high alloy steels, sulphide scales of an enhanced barrier nature formed during the induction periods and the layer formation mechanism was found to be assisted by the increasing temperature as initial reaction rates considerably decreased over time. Nevertheless, corrosion-related sulphide conversion of metals and mass loss of the high alloys are strongly affected by the composition of the biomass fuel sources especially animal waste lard. Thermal activation in the first 24 hours decreased from 68.9 to 35.2 kJ mol -1 . A greater degree of failure to develop protective sulphide scales was experienced by changing to composition of the biomass fuel sources than the impact of thermal activation between a narrow temperature range at around 100ºC. In accordance with the litera...

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“…One such production challenge is an increased risk of naphthenic acid corrosion that can result in various surface degradation profiles of uniform corrosion, non-uniform corrosion, and localized pitting in piping systems at temperatures between 150°C and 400°C [3,4]. The accuracy, precision, and reliability of structural health monitoring thickness measurement systems must be sufficient to provide a better understanding of the integrity risk associated with refining crude oils of higher acid concentration.…”

Section: Introductionmentioning

confidence: 99%

Structural health monitoring ultrasonic thickness measurement accuracy and reliability of various time-of-flight calculation methods

Eason

Bond

Lozev³

2016

AIP Conference Proceedings

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Abstract. The accuracy, precision, and reliability of ultrasonic thickness structural health monitoring systems are discussed in-cluding the influence of systematic and environmental factors. To quantify some of these factors, a compression wave ultrasonic thickness structural health monitoring experiment is conducted on a flat calibration block at ambient temperature with forty four thin-film sol-gel transducers and various time-of-flight thickness calculation methods. As an initial calibration, the voltage response signals from each sensor are used to determine the common material velocity as well as the signal offset unique to each calculation method. Next, the measurement precision of the thickness error of each method is determined with a proposed weighted censored relative maximum likelihood analysis technique incorporating the propagation of asymmetric measurement uncertainty. The results are presented as upper and lower confidence limits analogous to the a 90/95 terminology used in industry recognized Probability-of-Detection assessments. Future work is proposed to apply the statistical analysis technique to quantify measurement precision of various thickness calculation methods under different environmental conditions such as high temperature, rough back-wall surface, and system degradation with an intended application to monitor naphthenic acid corrosion in oil refineries.

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Review of naphthenic acid corrosion in oilrefining

Cited by 226 publications

References 4 publications

Palladium Hydride as a Reference Electrode in Aprotic Solutions

Palladium Hydride as a Reference Electrode in Aprotic Solutions

Hydrogen Sulphide Corrosion of Carbon and Stainless Steel Alloys Immersed in Mixtures of Renewable Fuel Sources and Tested Under Co-processing Conditions

Structural health monitoring ultrasonic thickness measurement accuracy and reliability of various time-of-flight calculation methods

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