Liquefied Petroleum Gas Lpg Engineering Essay

Liquefied Petroleum float Lpg app fraudd science EssayLiquefied Petroleum Gas is an important source of muscularity for millions of people around the world. LPG consists mainly of heavy weapones at atmospheric temperature and compact (propane and butane), which when subjected to little storm or refrige ration can liquefy. This makes it possible to transport and fund as molten in pressurized cylinders and containers, which must be safely and cautiously handled.DefinitionLiquefied Petroleum Gas (LPG) can be app arntly described as hydrocarbons that exist as dehydrations chthonian ambient conditions of temperature and twinge, but can be liquefied by the application of talk over pressure.When botch is liquefied, the ledger occupied by the desiccation well decreases, so the liquid formed requires less storage space. The material is therefore stored and distributed in the liquid course in pressurized containers and formations and is fin altogethery allowed to return to the vapour phase at the point of eventual utilization.Sources of LPGLPG as the name suggests, consists mainly of a mix of hydrocarbons (Propane and Butane) with a little proportion of unsaturates (Propylene and Butylene). These hydrocarbons and unsaturates (LPG) can be produced by means of two main sources which argonWet infixed Gas, which consists entirely of pure hydrocarbons (Propane and Butane) and can be rig in petroleum or particle accelerator fields, being exterminated as condensable increases from natural bumble and also extracts from unrefined oil during the stabilization emergence applied in order to strike down the vapour pressure prior to shipmentRefining process to remove impurities like moisture and sulphur compounds (hydrogen sulphide and mercaptans), which may lead to choke off of valves and corrosion. However, due to the odourless nature of LPG, ethyl mercaptan which has a unique odour, is added to agile the user of LPG incase a leak takes place.The product of crude oil refining fall into troika main categoriesThe permanent gases, Methane and Ethane which tolerate gaseous regardless of pressure, unless refrigerated.Hydrocarbons having five or more carbon atoms per molecule. They argon liquid or solid at atmospheric temperature and pressure and discover for most of the crude oil refined.Propane, Butane and Isobutane, together with Propylene, Butylene and Isobutylene have three or four carbon atoms per molecule. All have the special circulariseplane propeller of becoming liquid at atmospheric temperature if moderately compressed and throwback to gases when the pressure is sufficiently reduced.CUsersMr TDesktopIMAG0168.jpgProperties of Liquefied Petroleum Gas (LPG) drying up PressureVapour pressure is a measure of the volatility of the gas and where vapour exists in conjunction with the liquid phase is referred to as the fertilization vapour pressure. At the boiling point it is equal to atmospheric pressure and increases as the temperature rises to the critical. Propane with its turn down boiling point frankincense exerts a great vapour pressure under identical conditions than butane.Knowledge of the vapour pressure of a gas is thus essential in order to be able to specify the design conditions for the pressurized system. It is also required to enable the gas offtake rates by natural vapourization to be calculated.In practical terms, systems are often specifically designed to be suitable for either butane or propane which thus precludes a butane system from being used for propane, but enables the propane system to be classed as dual purpose.GDCIM100MEDIAIMAG0198.jpgBoiling Points of LPGThe constituent gases found in a commercial LPG mixture all have truly low boiling points and will thus normally exist in the vapour phase, under atmospheric conditions, unless they have been liquefied or refrigerated.Where the gases are held at a temperature at or below their boiling point, the vapour pressure will be equal to or less than atmospheric. This lieu has led to the development of large scale storage at naval terminals where the product is held in refrigerated form in what is essentially a non-pressurized system.Above ambient temperature, the gases exert an increase vapour pressure, thus increasing the pressure required for liquefaction. This pressure continues to increase until the critical temperature is reached, (96.67oC for propane 152.03oC for n-butane), above which temperature of the gases terminate to exist in the liquid phase even if further pressure is applied.Latent Heat of LPGThe latent heat of a liquid product is the quantity of heat absorbed to enable vapourization to occur.In the event of liquid LPG being allowed to vapourize naturally, the latent heat required is taken from itself and its immediate milieu at the same time, causing a drop in temperature. The process is known as auto-refrigeration.Very low temperatures can be achieved with propane under such conditi ons therefore in order to avoid operators receiving severe chilliness burns, protective clothing is required.Specific Volume, Relative DensityLPGs exist as heavy gases approximately 1.5 2.0 clock the density of air in vapour phase. They reduce in volume intimately on liquefaction (ratio of gas volume to liquid volume at 15.6oC/1016mbar is 233 for butane and 274 for propane) to exist as a muster out liquid which is approximately half the weight of water (Propane 0.50 0.51, Butane 0.57 0.58).It can thus be seen that LPG vapours heavier than air will tend to cling to the run aground seeking to enter trenches, drains and other low areas, which could make it take considerably longer time to disperse.Leaking liquid phase LPG will rapidly increase to around 250 times its own volume, therefore creating a greater endangerment than would occur with a similar sized vapour leakage.Where temperature conditions permit the organism of free liquid from a leakage, the product will float on whatsoever water present. This normally occurs with butane in freezing conditions and a regular scenario would occur during firefighting operations.Coefficient of Cubical Expansion of LiquidLiquid phase LPG expands considerably when its temperature increases. The coefficients of cubical expansion at 15oC are approximately 0.0016 per oC for propane and 0.0011 per oC for butane. These values are around 4 times the equivalent for fuel oil, 10 times that for water and 100 times that for steel.This high rate of expansion has to be taken into consideration when specifying the maximum quantity of LPG permitted to be filled into any pressure vessel, ie the filling ratio defined by codes of pattern for different specification of LPGs under different ambient conditions.Be excite the filling ratio precautions taken to prevent the hydraulic filling of storage systems cannot be encompassing to the connecting liquid phase pipework, these parts of the system are protected by the provision of small hydrostatic relief valves situated in all areas where the liquid LPG can be trapped between closed valves.Limits of Flammability vaporific fuels will only burn when mixed with air in proportions which lie between two well defined limits, known as the get off and upper limits of flammability. The lower limit being the smallest quantity of combustible gas which, when mixed with a given quantity of air (or O2) will allow self-propagating flame.A leak of 1m3 of liquefied propane will produce 274m3 of propane vapour, which will cause immediate entrainment of air and progressive dilution of the concentration.When the upper limit of 10% is reached, the propane/air mixture becomes flammable (ie when the propane entrains, 274 10 = 2740m3 of air). The mixture only becomes flammable when the lower limit of 2% is reached (ie when the propane entrains 274 50 = 13,700m3) of air.Therefore, should a leak of propane occur, the propane/air mixture will be flammable and hence extremely dange rous until it has been thin with more than 13,700m3 air per m3 of propane leakage.The following are the limits of flammability of LPG and some other fuelsGasLower LimitUpper LimitCommercial Propane2.010.0Commercial Butane1.89.0Natural Gas5.015.0Coal Gas5.040.0CUsersMr TDesktopIMAG0189.jpg