VLE Calculators With Pseudo Components
Crude oil comprises of hundreds of components. It is not possible to know all the components present in crude oil and their mole/ mass/ volume percentage in crude oil. Therefore crude oil is generally characterised as a combination of lighter components like methane, ethane, propane etc. and number of heavier fractions. Also in other multicomponent hydrocarbon mixtures like natural gas, exact concentration of heavier components is not always known and these heavier components are characterised as a single fraction like C6+, C7+ etc. or a combination of more than one fractions. These heavier fractions are also known as pseudo components and are generally defined by their normal boiling point (NBP)/ mean average boiling point (MABP) and specific gravity. Correlations are available in literature to calculate molecular weight and critical properties like critical temperature, critical pressure, critical volume and acentric factor of pseudo components based on their normal boiling point (NBP)/ mean average boiling point (MABP) and specific gravity. As crude oil and therefore pseudo components are mixtures of nonpolar or mildly polar hydrocarbons so these critical properties and molecular weight of pseudo components can be used in equations of state to find VLE properties of crude oil samples and other hydrocarbon mixtures consisting of one or more than one pseudo components. Crude oil characterisation into pseudo components require plotting of true boiling point curve which is a plot of volume of heavier components vaporized vs boiling temperature. Crude oil is characterized into upto a maximum of 40 pseudo components. Specific gravity of pseudo components present in a crude oil sample can be determined experimentally or calculated using watson K factor/ UOP K factor/ K factor which depends on aromaticity of crude oil and generally lies between 9 (aromatic crude) to 13 (paraffinic crude). K factor gives a relation between normal boiling point (NBP)/ mean average boiling point (MABP) and specific gravity of pseudo components.
EQ-COMP VLE Software can include upto a maximum of 40 pseudo components. Normal boiling point (NBP)/ mean average boiling point (MABP) of pseudo components need to be known which can be taken from true boiling point curve of the crude oil sample or hydrocarbon mixture. Specific gravity of pseudo components can be determined experimentally or calculated using K factor of the crude oil sample or hydrocarbon mixture. Mole percent of pseudo components in oil and its molecular weight can be calculated by known mole percent of pseudo components in oil-gas mixture or by volume percentage of pseudo components as per true boiling point curve. Mole percent of oil in oil-gas mixture can be known or calculated using known GOR (gas to oil ratio) at standard conditions and calculated specific gravities and molecular weights of oil and gas.
Following VLE calculations can be performed after inclusion of pseudo components :
- Two phase composition with pseudo components Calculation Cost : 125 USD
- Phase envelope with pseudo components Calculation Cost : 100 USD
- Water dew point curve with pseudo components Calculation Cost : 50 USD
- Hydrate curve with pseudo components Calculation Cost : 200 USD
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