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Team 10 Flammability David Sediqi, Kori Mondin, Faisal Najem, Sharath Reddy, Jerrell Ross http://www.astm.org/SNEWS/DECEMBER_2004/f lam_dec04.html 1 Slide 2 Introduction Most chemical plants contain flammable materials and face hazards related to their combustion The majori ty of the worst chemical plant accidents involved flammable materials. To avoid and manage these risks, 3 important concepts must be recognized and understood: 1.The Anatomy of the fire 2.The Characteristic Properties of flammable materials 3.Procedures used to reduce fire and explosion hazards http://4vector.com/free-vector/sign-flammable- materials-clip-art-110517 2 Slide 3 Minimize the Risks of Flammable Materials Nearly all of the WORST chemical plant accidents involved flammable materials. Flammable materials can cause severe damage in the form of fires and explosions if not handled properly. The video to the left, shows a Texas Fertilizer plant explosion last year. Over 100 people injured. 3 Slide 4 Anatomy of Fire/Explosion A fire can only occur when a fuel, oxidant, and an ignition source is available. Fuel- the concentration must be present at a certain relative amount to the oxidant. Example: Gasoline, ethanol, methane, ethane, etc. Oxidant- the concentration must be present at a certain relative amount to the fuel. Example: Most common one O2, but can include Cl2, and nitrates Ignition Source- can range from a spark to a flame, but must be strong enough to start a fire. Fires occur over a long time frame and have a low energy release rate, while explosions are the opposite in both ways. http://chemicalengineersdaily.blogspot.com/2012/05/memperkecil-resiko-dari- flammable.html 4 Slide 5 Properties of Flammable Materials Flammable gases and liquids can be characterized by properties that are determined experimentally. Properties include : 1.Flammability Limits 2.Limiting oxygen concentration 3.Minimum ignition Energy 4.Autoignition Temperature 5.Flash Point Crowl D A. Minimize the risks of flammable materials. Chemical engineering progress 2012;108(4):28-33. 5 Slide 6 Flammability Limits Flammable gases and liquids can be characterized by properties that are determined experimentally. One of the main characteristics is Flammability limits. This is divided in two subcategories: Lower flammability limit (LFL) and Upper Flammability limit (UFL) LFL- the concentration of fuel vapor in which below it, no explosion will occur. The mixture is too dilute. UFL- the concentration of fuel vapor in air in which above it, no explosion will occur. The mixture is said to be too concentrated or rich. The LFL and UFL are determined experimentally by mixing flammable gas and an oxidant in a closed container. If ignition occurs, the pressure increase to a maximum. Lower Flammability Test appartus MSB International Fire Behaviour and Fire Suppression Course 2011 6 Slide 7 Matlab Max Pressure vs Fuel Concentration C=[2.05 2.1 3.2 3.9 5.99 7 7.1 7.96]; E=[0 2.1 6 8.2 8.4 7.6 3.8 0]; c = linspace(0,10) dd=polyfit(C,E,2) %take polyfit values to generate equation of parabola below y=-.9795.*c.^2+9.8199.*c-15.786; plot(c,y) hold on; scatter (C,E) hold off axis([0 10 0 10]) title('Max. Explosion Pressure Vs. Fuel Concentration in Air') ylabel('Maximum Explosion Pressure (barg)') xlabel('Fuel Concentration in Air (vol%)') 7 Slide 8 Temperature Effects on Flammability Limits Temperature has a large effect on flammability limits of species. The equations below show this relationship between flammability limits and temperature. Calculation of Flash Points and Flammability Limits of Substances and Mixtures 8 Slide 9 Matlab Determination of Lower Flammability Limits function [ ] = FL( T,Hc,LFL25 ) %calculates the lower flammability limit of a substance at a given temperature if nargin Matlab Examples for Flammability Limit Calculations >> FL(100,889,5) LFL= 4.98 >> UFL(100,889,15) UFL= 14.98 >> LFLmix() input y in matrix form (ex. [y1 y2 y3])for each flammable species in the mixture [.5.5] input LFL in matrix form (ex. [LFL1 LFL2 LFL3])for each flammable species in the mixture [5 3] LFLmix= 3.75 >> UFLmix() input y in matrix form (ex. [y1 y2 y3])for each flammable species in the mixture [.5.5] input UFL in matrix form (ex. [UFL1 UFL2 UFL3])for each flammable species in the mixture [15 12.5] UFLmix= 13.64 https://www.osha.gov/dte/library/flammable_liquid s/flammable_liquids.html 14 Slide 15 Triangle Diagrams Triangle diagrams can be constructed using data provided for chemical species such the LFL, UFL, and LOC. The slope of the stoichiometric line can be calculated using the stoichiometry of the combustion reaction and the equation, The flammability zone can be approximated by using intersections of the limiting oxygen concentration, upper, and lower flammability limits. Triangle diagrams of various species can be constructed using the proper data. Crowl D A. Minimize the risks of flammable materials. Chemical engineering progress 2012;108(4):28-33. 15 Slide 16 Triangle Diagrams The triangle diagrams for propane and ethylene are shown. 16 Slide 17 Limiting Oxygen Concentration This is the concentration of O 2, in which below it, no combustion will occur even though there sufficient amount of fuel The LOC has units of volume % of Oxygen It is determined by the same method of determining the LFL and UFL; the closed vessel apparatus. http://www.fauske.com/chemical-industrial/gas-vapor-flammability 17 Slide 18 LOC and Oxygen mol Ratio Relationship From the stoichiometric combustion reactions, the mole ratio of oxygen to the combusting species can be obtained. A plot of the mol ratio and LOC suggests a logarithmic relationship between the two variables. 18 Slide 19 LOC and Oxygen mol Ratio Relationship A correlation coefficient of 0.6345 suggests that there is somewhat of a relationship between the two variables. 19 Slide 20 Plot of LOC vs O2 mol Ratio (no log) This graph depicts a linear relationship between the LOC and the oxygen mole ratio, and according to the previous matlab code, the correlation coefficient is 0.6163, which is slightly less accurate than the Log-log relationship. 20 Slide 21 LOC and Oxygen mol Ratio Relationship Plotting the logarithm of the LOC concentration versus the logarithm of the oxygen mol ratio of the reaction, the relationship can be observed. The equation for the line of best fit was calculated to be ln(y) = ln(x) + 2.0099, where y is the limiting oxygen concentration and x is the mole ratio. 21 Slide 22 Flash Point The flashpoint is the lowest temperature in which a vapor a vapor will form a mixture in the air that can ignite. At this point, the vapor will burn briefly, but it can lead to the fire point, where it will burn continuously. The flash point has to do with the vapor pressure of the substance, the measure of the concentration of vapor in equilibrium with the liquid. The higher the temperature, the higher the vapor pressure http://www.oil-analysis.org/flashpoint.html 22 Slide 23 The Cleveland Open-Cup Tester to Determine Flash Point The way that the Cleveland Open- Cup tester works is first, the test cup of the apparatus (which is usually brass) is filled to a certain level with a portion of the product. Then, the temperature of this chemical is increased rapidly and then at a slow, constant rate as it approaches the theoretical flash point. The increase in temperature will cause the chemical to begin to produce flammable vapor in increasing quantities and density. The lowest temperature at which a small test flame passing over the surface of the liquid causes the vapor to ignite is considered the chemical's flash point. This apparatus may also be used to determine the chemical's fire point which is considered to have been reached when the application of the test flame produces at least five continuous seconds of ignition. Crowl D A. Minimize the risks of flammable materials. Chemical engineering progress 2012;108(4):28-33. 23 Slide 24 Flashpoint Diagram and Significance The flashpoint occurs at a temperature at which the lowest concentration of vapor in a mixture with air can cause combustion. UFL and the flashpoint differ in temperature because the LFL is typically measured at room temperature, as indicated by the ambient temperature line. The UFL is the vapor concentration in combustion is not possible above. The Autoignition Zone is the point at which spontaneous combustion occurs without an outside source of energy. Crowl D A. Minimize the risks of flammable materials. Chemical engineering progress 2012;108(4):28-33. 24 Slide 25 Flashpoint The boiling point of a hydrocarbon has a significant effect on the flashpoint of the species. A relationship between the flashpoint and boiling point is shown below. 25 Slide 26 Flashpoint Various hydrocarbons boiling point and flashpoints were plotted along with the equation for estimating the flashpoint. The plot reveals a strong linear relationship between boiling point and flashpoint with a coefficient of correlation of approximately 0.9303. 26 Slide 27 LFL and Flashpoint A correlation coefficient of 0.4165 suggests a weak relationship exists between the two variables, LFL and Flashpoint. 27 Slide 28 LFL and Flashpoint A line of best fit for the logarithmic data is calculated to be y = 0.4028x + 3.8086. 28 Slide 29 Minimum Ignition Energy This is the minimum amount of energy to ignite the fuel vapor. Typically a very small amount of energy is needed to ignite a vapor (0.025 mJ), and sparks that are detectable to the touch usually contain 20-25 mJ of energy. These numbers indicate that the elimination of ignition sources is not a major way to prevent fire and explosion hazards http://www.chemicalprocessing.com/articles/2010/192/ 29 Slide 30 Auto Ignition Temperature (AIT) This is the temperature where enough energy is available in the environment to provide an ignition source without an external source. To measure this, the flammable liquid is inserted into a preheated flask with a set temperature. It is observed for a set amount of time until, combustion behavior is observed. If nothing happens the temperature of the flask is raised until combustion behavior is observed. In this picture, the flammable chemical is injected inside the container to the right, and the temperature is adjusted accordingly to determine the autoignition temperature. http://www.msha.gov/TECHSUPP/ACC/StandardTestProcs/ASTP5002.pdf 30 Slide 31 AIT and the Shell Oil Refinery Explosion in Norco, Louisiana In 1988, a shell oil refinery in Norco,LA exploded due to a corrosion in one of the pipes in the Catalytic cracker unit. http://lu.chocodesign.net/explosion-at-shell-norco-refinery-in-1988-pic.html 31 Slide 32 AIT and the Shell Oil Refinery Explosion in Norco, Louisiana (contd) A Catalytic Cracker Unit (CCU), is one of the most important units of an oil refinery. It is the unit that converts the high-boiling, and high molecular weight hydrocarbon fractions of petroleum crude oil into gasoline and other fuel products. http://upload.wikimedia.org/wikipedia/commons/9/95/FCC.png http://upload.wikimedia.org/wikipedia/en/2/25/Fluid_Cat alytic_Cracker.gif 32 Slide 33 AIT and the Shell Oil Refinery Explosion in Norco, Louisiana (contd) The feed containing long chain hydrocarbons and recycle slurry oil from the bottoms product of the distillation column enters the catalyst riser in the CCU. The catalyst riser contains hot powdered catalyst that mixes with the feed and breaks it into smaller molecules of vapor. After a few other processes, the product is extracted and the used catalyst enters the regenerator to be reactivated. http://www.exxonmobil.com/Apps/RefiningTechnologies/Files/sellsh eet_07a_fcc.pdf 33 Slide 34 AIT and the Shell Oil Refinery Explosion in Norco, Louisiana (contd) General process flow diagram of a CCU http://www.cbi.com/images/uploads/tech_sheets/FCC-12.pdf 34 Slide 35 AIT and the Shell Oil Refinery Explosion in Norco, Louisiana (contd) High temperature fluids and high amounts of energy is handled when operating a CCU. In 1988 Norco,LA, corrosion tests were not implemented when a new elbow fitting was placed in the unit. Because of this, the fluid corroded the pipe and created an 8 inch hole in it. because of the high temperature, the vapor cloud ignited and caused an explosion that killed 7 people. The CCU diagram of Shell Oil at Norco indicating the failed elbow Source: Dick Hawrelak, The Shell Oil Norco VCE 35 Slide 36 Prevent Fires From Flammable Materials Some fires and or explosions due to flammable materials can not be prevented totally, but can be reduced by: Storing them properly Informing employees of high risk materials Posting information about the possible dangerous material Limit the amount of flammable materials on site. http://www.protectamerica.com/home-security- blog/home/its-fire-prevention-week_299 36 Slide 37 Storing Flammable Materials Safely Keep the flammable materials away from ignition sources, which include but are not limited to: Sparks from electrical equipment, or metals being cut Tobacco smoke Hot surfaces Fire (open flame) http://www.123rf.com/photo_3276375_ electrical-plug-and-outlet-generating- electricity-sparks-digital-illustration.html http://www.phfc.co m.au/index.php?op tion=com_content& view=article&id=60 6&Itemid=311 http://www.labconco.com/news/open- flame-use-in-a-class-ii-biological-safety-c 37 Slide 38 Well ventilated, to avoid vapor concentration Free of ignition sources Cool temperature and dry Easily accessible by firefighters Labeled with warning signs Away from building exits On the ground floor, to make it easily accessible What is an ideal storage area? http://gardenbite.com/2013/11/01/st oring-garden-chemicals/ http://news.xinhuanet.com/english/2008- 08/26/content_9717750.htm 38 Slide 39 Limit The Amount of Flammable Materials on hand Keep only what you NEED on site Purchase the flammable materials in the smallest volume necessary Do not let the hazardous waste accumulate Only keep the materials that are needed presently for the tasks being worked on. http://www.plant- care.com/chemical-storage- cabinet.html An example of a chemical storage that is not too big, and contains just what is needed for the task at hand. http://www.portal.state.pa.us/p ortal/server.pt/community/high_ school_and_college_tech_assista nce/10405/mercury_and_other_ dangerous_chemicals/552390 An example of a storage with too many flammable materials on hand. 39 Slide 40 Increase Awareness Post warning signs Keep an active log of all flammable materials on hand Keep MSDS sheets on hand for the flammable materials Inform people using the materials about flammability properties, such as: Upper Flammability Limit (UFL) Lower Flammability Limit (LFL) Minimum Ignition Energy (MIE) Limiting Oxygen Concentration (LOC) Flashpoint Ignition Sources http://www.igb.illinois.edu/safety/msds- information http://cdn2.bigcomm erce.com/server3300 /gfhdwrb/products/1 037/images/3044/Da nger_Flammable_Ma terials_Fire_Safety_P oster_P4790__60168.1368112592.850.11 00.jpg 40 Slide 41 Proper Warning signs Appropriate safety signs should be put in instruction manuals and containers that contain flammable or explosive material. Flammable Material http://chemistry.about.com/od/safetysignsandsymbols/ig/Fire-Safety-Signs/Flammable-Sign.- bOO.htm Explosive Material http://chemistry.about.com/od/safetysignsandsymbols/ig/Fire-Safety-Signs/Explosives-Sign.htm Oxidizing Material http://chemistry.about.com/od/healthsafety/ig/Laboratory-Safety-Signs/Oxidizing.htm 41 Slide 42 Conclusion Flammable materials can cause fires and explosions if they are not handled properly. Understanding these materials and risks they pose is the first step to mitigating fire hazards. Out of the 100 chemical plant accidents, almost all of them were due to flammable materials. Understanding the flammability properties can help reduce the the hazards. Storing the flammable materials properly helps reduce the risk. Preventing fires/explosions caused by flammable materials is possible by understanding the properties of the materials Hundreds of lives can be saved. http://www.aiche.org/ccps/resources/chemeondemand/webina rs/introduction-flammable-materials 42 Slide 43 Future Improvements To avoid fires and explosions, industries that handle flammable chemicals should hire third party inspectors to asses whether they are compliant to the governments regulations (OSHA) More relationships between the properties of flammable materials should be studied and researched to see if there is a higher correlation with each other, to improve knowledge about flammable material to increase safety measures. Dr. Sam Mannans research includes flammability http://engineering.tamu.edu/news/2013/03/08/mannan-honored-by-rajiv-gandhi-institute- of-petroleum-technology-in-india 43 Slide 44 References http://www.uregina.ca/hr/hse/assets/docs/pdf/Handling%20and%20Storage%20of %20Flammable%20Materials.pdf http://www.ccohs.ca/oshanswers/prevention/flammable_general.html http://www.chilworth.com/wp- content/uploads/2012/10/TheRelationshipbetweenFlashPointandLFLwithapplicatio ntoHybridMixturesLPS2007.pdf Hristova, M., Tchaoushev, S. Journal of the University of Chemical Technology and Metallurgy. Calculation of Flash Points and Flammability Limits of Substances and Mixtures. 2006. Journal. Crowl D A. Minimize the risks of flammable materials. Chemical engineering progress 2012;108(4):28-33. Dick Hawrelak, The Shell Oil Norco VCE, presented 1999 https://fisher.osu.edu/blogs/macc-admissions/2010/11/02/whats-a-good- reference-for-your-application/ 44