Alkylation Unit Research Articles

Accident prevention and the clean air act amendments of 1990 with particular reference to anhydrous hydrogen fluoride

AbstractThe Sections of the Clean Air Act Amendments (CAAA) of 1990 that refer to accident prevention are to be found in Title III. Two significant requirements of the CAAA in this respect relate to the responsibilities of the Occupational Safety and Health Administration (OSHA), which has promulgated a new Process Safety Management (PSM) standard and the Environmental Protection Agency (EPA), which at the time of writing, is developing Risk Management Program (RMP) regulations. The focus of this paper is on how the requirements of the CAAA may affect the reasons for performing a Quantitative Risk Assessment (QRA) or may affect the results of QRA.In order to limit the discussion, this paper focuses on HF. First, the CAAA requires that the EPA assess the hazards associated with HF: the EPA's current draft report is discussed. Second, a generic assessment of the risks associated with the use of HF is given, with emphasis on alkylation units in refineries. The principal contributors to risk will be listed. Finally, an assessment of OSHA's PSM standard 29 CFR 1910.119, the related requirements of state laws such as California's Risk Management and Prevention Program and the potential requirements of EPA's Risk Management Program will be given, including an assessment of how these requirements may influence quantitative estimates of risk.

Assessment of Fire Damage to Pressure Vessels in a Refinery Unit

A systematic approach is proposed to assess the fitness of pressure vessels in the alkylation unit of a refinery after fire damage. Techniques used to study a Jan. 11, 1991, fire included in-situ metallography; hardness testing; crack detection; and measurements of thicknesses, plumb, circumference, and straightness. Emphasis is placed not on conventional techniques such as hardness testing and in-situ metallography, but on methods of measuring the affected vessels and effectively detecting and sizing distortions caused by the fire. Though these methods have been available in the past, they are not used in typical fire damage assessments.

Mitigation of HF releases

Abstract The hazards of hydrogen fluoride (HF) have long been recognized and industry performance reflects sound operating practices. However, full-scale industry-sponsored HF release tests conducted at the US Department of Energy Test Site in 1986 caused concern in view of the toxicity of HF. Ambient impacts were greater than anticipated, and diking, a primary mitigation technique, proved ineffective for releases of pressurized superheated HF. In partial response to these new technical data, an ad-hoc three-component industry cooperative hydrogen fluoride (HF) mitigation and assessment programme (ICHMAP) was begun in late-1987 to study and test techniques for mitigating accidental releases of HF and alkylation unit acid (AUA), and to enhance capabilities to estimate ambient impacts from such releases. The programme's mitigation components have recently been completed while work on the impact assessment component is nearing completion. The purpose of this article is to describe the programme and to summarize the objective, scope of work, structure, and conclusions from the two mitigation components. The objectives and scope of work of the impact assessment component are also briefly described. Detailed and summary reports for each programme component will shortly be available through the US Department of Commerce, National Technical Information Service (NTIS) of Springfield, Virginia, ICHMAP member companies, collaboratively and individually, screened numerous potential mitigation techniques for accidental HF releases including techniques such as total enclosures with exhaust scrubbers, liquid containment dikes, foam application, water sprays, vapour barriers, and surface tension modifying agents. Water sprays and vapour barriers were judged to be the most promising techniques. Accordingly, the ICHMAP mitigation components consisted of both water spray and vapour barrier programmes. The water spray programme investigated the effectiveness of water or augmented water application systems in mitigating accidental releases of both HF and AUA. The vapour barrier programme assessed the effectiveness of vapour barriers in delaying and diluting accidental releases of heavier-than-air HF vapour clouds in an industrial setting and determined what impact such barriers might have on the consequences of an unconfined vapour cloud explosion.

In situ optical measurements of hydrofluoric acid aerosols

Abstract Large scale field tests were conducted to investigate the effectiveness of water spray mitigation on accidental releases of hydrogen fluoride (HF). This paper reports on a particular aspect of the test programme, namely the measurement of HF aerosol properties with an in situ optical instrument. Aerosol was generated by releasing HF through a sharp-edged orifice into the downwind direction of a large flow chamber. Release conditions were similar to conditions in an alkylation unit or a typical HF storage tank in summer weather. Aerosol properties were measured by inserting the probe at two downstream locations from the release point and at several radial positions within the emanating aerosol plume. A total of 86 usable aerosol data sets were obtained during the test period. As many as 10 data sets were acquired for a typical 11 min duration HF release. The PCSV-P optical instrument measured predominantly submicron aerosol particles near the release orifice. The aerosol then grew to larger particles further downwind. This points to the formation of the aerosol through vaporization-condensation as opposed to a conventional shear spray. HF release pressure and temperature, air humidity, radial position in the plume, and type of acid did not appear to have any significant effect on the measured size distributions for the range of conditions investigated. Understanding the size characteristics of the aerosol is particularly important in determining plume dispersion. The size distribution and dispersion characteristics are important both for design of water spray mitigation systems and as inputs for numerical models. Modelling simulates a broader range of release conditions than can be studied in a necessarily limited series of high cost experiments.

New unit for sulfuric acid alkylation of isobutane by olefins

The authors describe and illustrate a sulfuric acid alkylation unit with a horizontal contact. As a result of the use of this design solution, the isobutane/olefin ratio is 10/1 in comparison with 4/1 to 5/1 in the other types of units, namely vertical reactors and cascade tank reactors. The unit was designed to process the butane-butylene cut (BBC) and part of the propane-propylene cut (PPC) from the G-43-107 cat cracker. The unit design includes provisions for controlled caustic washing of the feed and dehydration in an electric field. The authors present the basic data obtained in the three months of unit operation after startup, in comparison with the operating indexes of a sulfuric acid alkylation unit.

Fluoride Exposure from Hydrofluoric Acid in a Motor Gasoline Alkylation Unit

Fluoride Exposure from Hydrofluoric Acid in a Motor Gasoline Alkylation Unit

Fluoride Exposure from Hydrofluoric Acid in a Motor Gasoline Alkylation Unit

To assess the possible health risks associated with occupational exposure to gaseous fluoride, air and biological monitoring surveys were carried out at a motor gasoline alkylation unit within an oil refinery. Pre- and post-shift urinary fluoride measurements were obtained from 27 male operators and maintenance workers attached to the plant; personal fluoride-in-air monitoring was carried out simultaneously for 23 of these men. All readings were below NIOSH recommendations and Australian exposure standards. Significant exposure identified by changes in urine level during the shift could be demonstrated only in sub-groups of workers whose jobs involved higher routine exposures. No significant correlation between air levels and changes in urinary fluoride during the shift could be demonstrated. This survey indicates that the workers in this plant are not at risk of chronic fluorosis.

Effectiveness of By‐Product Sulfuric Acid for Reclaiming Calcareous, Saline‐Sodic Soils

AbstractCopper smelters produce H2SO4 during the S scrubbing process, creating a continuing supply of H2SO4. Oil refineries use commercial grade H2SO4 in alkylation units and the resultant “spent” acid is a waste product available for other purposes. A 2‐year field experiment was conducted on two irrigated sites in south‐central Montana to evaluate the effectiveness of H2SO4 for reclaiming calcareous, salinesodic soils. Treatments included increasing rates of smelter acid, and comparisons with gypsum (CaSO4 · 2H2O), spent acid, and feedlot cattle manure in combination with smelter acid. Reclamation effectiveness was evaluated by analysis of saturated paste pH, electrical conductivity of the saturation extract (ECe), and sodium adsorption ratio (SAR) values of the soil in the 0‐ to 15‐ and 0‐ to 20‐cm depth intervals. Barley (Hordeum vulgare L) was grown both years as a biological test for reclamation.The degree of reclamation improved with increasing acid rate. Barley dry matter yield on plots that received the highest rate of acid was more than four times that of the check the second year.The effect of spent acid was similar to that of smelter acid. Gypsum lowered ECe and pH vlaues more than an equivalent rate of smelter acid, but SAR and barley dry matter yield were improved similarly by both amendments. Feedlot cattle manure plus smelter acid increased barley dry matter yield 40% over smelter acid alone. We propose that this effect is due to the improved soil nutrient status when both amendments are used together.

Variation of emulsion stability in sulfuric acid alkylation of isobutane with olefins

The makeup of the emulsion and its stability are determined to a great degree by the surface and viscosity properties of the acid. Investigates the dependence of emulsion stability on the properties of the acid circulating in the reactor section of an alkylation unit. Finds that as the surface-active substances that accumulate in the acid tend to lower its surface tension, and this in turn tends to disperse the hydrocarbon feedstock in the acid phase and forms a stable emulsion in the vigorously stirred reactor. Points out that as the acid viscosity increases, the segregation of microdrops of hydrocarbons from the acid phase becomes slower in the settling of the emulsion under natural conditions.

PENTON protects alkylation unit from corrosion at Texas refinery

RETURN TO ISSUEPREVAdvertisementNEXTPENTON protects alkylation unit from corrosion at Texas refineryCite this: Chem. Eng. News 1966, 44, 13, 18Publication Date (Print):March 28, 1966Publication History Published online6 November 2010Published inissue 28 March 1966https://doi.org/10.1021/cen-v044n013.p018Copyright © 1966 American Chemical SocietyArticle Views7Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (533 KB) SUBJECTS:Electrochemistry,Alcohols,Oxidation,Post-translational modification Get e-Alerts

Solving Corrosion Problems in HF Alkylation Units

Abstract Presents review for guidance of present-day operators of anhydrous hydrogen fluoride alkylation process. Covers early laboratory and pilot plant tests and metallurgical problems encountered in first commercial units. Steel was recognized early as a material for contruction of principal components of process units but was not satisfactory for all services. Monel, ruled out initially, later was found satisfactory for service as trim and in various kinds of valves. Valves with steel cocks failed when the HF attacked them, often sealing them into inoperable condition. Grease used for lubrication was troublesome in the stream. Numerous kinds of packing were tried, but none were entirely satisfactory at first. Monel and fluorocarbons made available later solved packing and valve-seat problems and also problem of protecting glass sight level gauges. Steel bolts failed rapidly from stress corrosion cracking when small leaks resulted in acid attack. K-Monel bolts also failed. Duranickel bolts were satisfa...

Use of High Molecular Weight Corrosion Inhibitors In Petroleum Refineries

Abstract The theory of adsorbtive inhibitors is discussed briefly. An account is given of tests by coupons and in refinery equipment evaluating the effect of three semi-polar compounds in reducing the corrosion of refinery equipment. Data on concentrations, technique of additions to streams, coincident use of ammonia, cost per barrel of charge, percentages discharged in effluent and percentage retained in stream are given. Considerable information is revealed indicating the detergent action of the inhibitors assists in reducing deposits on tubes and in pumps and other equipment and thereby extends the period between shutdowns for cleaning. Significant reductions in the corrosion rates in crude distillation units, steam reboilers, straight run deisobutanizers, vacuum pumps, alkylation units, TCC units and other refinery equipment are reported. The author concludes water soluble inhibitors tested are sufficiently soluble in hydrocarbons to provide corrosion protection.

Architectural beauty in an alkylation unit.

Architectural beauty in an alkylation unit.