ISSN:1066-8527    

DOI:10.1002/prs.680150402

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

ISSN:1066-8527    

DOI:10.1002/prs.680150403

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

摘要:

AbstractMuch process safety technology has been developed through the years and now serves as the basis for present day design standards for process safety in the process industries. This has come about through carefully executed research. Much of this research has had to be done on large scale in order to fully develop and test the technology for dependable correlations necessary to establish design bases. Especially noteworthy are the design guides now available for minimizing hazards of sudden high pressure development by uncontrolled combustion inside process equipment and inside buildings. Very extenstive large scale research was necessary for developing these design guides.Despite the process safety technology and design standards available today, much more is yet needed. As in the past, development of the necessary technology will in some cases require large scale research. This paper discusses some of the major research needs in three areas, as follows:1.Exothermic runaway reactions2.Uncontrolled combustion3.Miscellaneous research needs

ISSN:1066-8527    

DOI:10.1002/prs.680150404

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

ISSN:1066-8527    

DOI:10.1002/prs.680150405

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

摘要:

AbstractTests at 60°C and 16 psia using ethylene, hydrogen and methyl alcohol “fuel vapors” showed that if an atmospheric vent collection header contains 25 vol% of methane and the only source of oxygen is the air, no possible mixture of fuel vapor, nitrogen and residual oxygen is flammable. Addition of these fuel vapors to a header containing 25% by volume of methane in all cases increases the 3.8 vol% oxygen safety factor that exists with zero fuel vapor in the gas stream. It is irrelevant that the fuel vapor has an upper flammable limit (UFL) greater than the methane enrichment gas. The minimum oxygen concentration to sustain a flame (MOC) increases with increased methane: nitrogen ratio in the gas stream, so that the “listed” MOC has no relevance under methane enriched conditions. These findings have important ramifications when applying Coast Guard Regulations in 33CFR.154 for Marine Vapor Control Systems, which implies the need to operate at 170% of the combined gas stream UFL and requires operation at less than the MOC (≤ 8% oxygen) when tanks have been partly inerted with nitrogen. Large reductions of enrichment gas usage with attendant environmental benefits are technically possible using flow control of methane rather than gas analysis downstream of the enrichment station. Operation above the UFL rather than below the MOC can cut enrichment gas usage by 50% or more while actually increasing the assumed 2 vol% oxygen safety factor. A negative flow control error of 7 vol% methane (−28% of target) is required to achieve flammability under worst case assumptions.Exceptions: Users are cautioned that a comprehensive list of exceptions to the 25 vol% methane enrichment method has not been developed. Using the test protocol described the method appears to fail for decomposable fuel vapors, such as ethylene oxide, and fuel vapors susceptible to cool flames under vent header conditions, such as ethyl ether. Coast Guard regulations in 33CFR.154 have not changed and applications for variance are considered on a case‐by‐case basis. In the context of this paper, additional test data development may be justified where the cargo vapor UFL exceeds that of methane.When operating at less than the MOC using nitrogen or other inert diluent, it is important to allow for errors in the MOC value used. NFPA 69 lists many MOCs measured in the 1930s using weak ignition in open ended 2 inch diameter glass tubes. Since MOC depends on test conditions it is optimistic to expect such values to apply to large flare headers. For example, the MOC measured for ethylene was 8% rather than 10% oxygen as listed in NFPA 69. This offsets the oxygen safety factor normally applied for continuously monitored gas streams. Methods for estimating MOC based on LFL can introduce additional errors. These errors are compounded in cases where the MOC is estimated for mixed gas streams using the Le Chatelier Rule. Example calculations are compared with measured MOC values listed in NFPA 69. Some practical considerations are given with respect to oxygen sources in vent collection headers and flame arrest

ISSN:1066-8527    

DOI:10.1002/prs.680150406

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

摘要:

AbstractQuantitative risk analysis (QRA) is a valuable tool for understanding and managing risk in the chemical process industry. QRA is most useful when used to evaluate the impact of design alternatives on facility risk (comparing the risk of one design option to one or more alternatives). QRA also determines the major contributors to facility risk, so that efforts to manage and reduce that risk can be directed to areas where they will have the largest impact and be the most cost effective. However, it is inevitable that the use of a tool which generates a numerical estimate of risk will raise questions as to the tolerability of that estimated risk. The use of quantitative risk guidelines as one tool in the risk management process will be discussed.“Wise Men Foresee Calamity in Order the Better to Bear it.”—Attributed to King Arthur at his Coronation by Geoffrey of Monmouth (c. 1136) inHistoiria regum Britann

ISSN:1066-8527    

DOI:10.1002/prs.680150407

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

摘要:

AbstractThe dust explosion course in pipes of pneumatic conveying systems is discussed. A high number of large scale tests was carried out and the influence of pipe diameter, dust concentration, conveying velocity, location of the ignition source and powder specific parameters was taken into account. The concentration of the ignited dust/air mixture is measured and controlled by an opto‐electronic measuring system. The flame propagation time, the flame front velocity and the explosion pressure depending on the distance of the flame front from the ignition source are shown as well as the explosion pressure as a function of the flame front velocity. The experimental results give important hints concerning the explosion course in pipes, the strength of pipes and location of disengagement systems under practical operating condition

ISSN:1066-8527    

DOI:10.1002/prs.680150408

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

摘要:

AbstractAdvances in technology relative to pilots, pilot ignition, pilot flame detection and pilot gas consumption are needed to reduce the millions of dollars lost as a result of outdated existing pilot technology. These losses are the result of damaged equipment, lost production, fuel usage, safety issues, lawsuits and in some instances jeopardizing personnel.This paper briefly discusses the existing pilot technolgy including pilot ignition and pilot flame detection, the economic impact on the users, and new developments in pilot technology.Over the past decade the major combustion companies have been required by consolidation of plants and the introduction of new Environmental Regulations to concentrate their Research and Development resources on the design of Flares and Burners with higher release rates, increased smokeless capabilities, and lower generation of NOX and CO. This has resulted in minimal Research and Development efforts by the major combustion companies directly relating to the design and improvement of pilots and pilot flame detection.Pilots, ignition and pilot flame detection technology has been forced to take a back seat to those more pressing issues. This has resulted in much concern by the operators of pilots regarding flame stability, ignition methods, reliability, gas usage, and safety. The industry has been forced to accept pilots, ignition and pilot flame detection equipment with outdated technology which has caused losses in the millions of dollars. The most critical component of a flare or burner is the pilot which ignites the vented high pressure relief gas from flares, and the gases or oil released through a burner to create a heat source for various plant processes.

ISSN:1066-8527    

DOI:10.1002/prs.680150409

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

摘要:

AbstractFlash point determinations made from small‐scale fire test apparatus are used by regulatory authorities to classify flammable and combustible liquids. Based on these classificaiton, regulators then specify or provide guidance on the appropriate methods to transport, handle, package, store, dispense, and protect these materials. Closed‐cup flash points of flammable and combustible liquids are used to establish their appropriate classification. Exceptions to these classifications include products such as alcoholic beverages and medicines stored in relatively small containers, which have historically presented a limited fire hazard.Many companies are now reformulating their consumer liquid products to meet customer and regulatory demands for low volatile organic compounds (VOC's). Low VOC formulations often do not inherently result in the total elimination of flammable or combustible liquid solvents. In some cases, the reformulations result in “water‐reducible” products, which contain a high water content. Water‐reducible coatings are products where the solvent system used to disperse and suspend solids is primarily water. The remainder of the solvent system may contain liquids that are classified as flammable or combustible liquids. A natural by‐product of the “water‐reducible” trend is the development of a fire analysis framework which could be adopted by regulatory authorities as part of the movement toward performance‐oriented codes. This methodology could also be used to address limitations of specific test methods. These limitations relate to product vicosity, accuracy in predicting overall fire hazard, ability to assess physical changes of state when a product is tested, and test method reliab

ISSN:1066-8527    

DOI:10.1002/prs.680150410

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY

摘要:

AbstractThe potential for dust and gas explosions in the process industries has been long recognized. Potentially explosive materials are handled in large quantities on a daily basis. A specific hazard associated with conveying materials into incinerators and thermal oxidizers involves the potential for deflagration propagation through process pipes and ducts back into the plant.The deflagration propagation phenomena in pipes and ducts is one that is both highly hazardous and complex to predict. A deflagration, moving down a pipe, under the right conditions can increase in velocity to the point when a transition into detonation occurs with potentially catastrophic results. This deflagration to detonation transition (DDT) is effected by a number of interrelated factors. Knowledge of these factors is crucial to the development of explosion prevention and protection measures.A discussion of the deflagration phenomena is presented with emphasis on pipes and ducts and transition of deflagration to detonation. The use of this information to design explosion protection is described using several industrial examples.

ISSN:1066-8527    

DOI:10.1002/prs.680150411

出版商:American Institute of Chemical Engineers    

年代:1996

数据来源: WILEY