Week 1 Challenge

Composition

Propane – 0.3 mass %

N-Pentane – 0.2 mass %

Hexane – 0.2 mass %

Heptane – 0.2 mass %

Octane – Determine the mass %

After entering the above composition in a mole fraction in the Aspen HYSYS, the total composition should come to 1. Therefore, the Mass Percentage of Octane is 0.1.

But using degrees of freedom, when it is left to calculate by HYSYS by pressing the normalize option, then the mass percentage of octane becomes 0 % as the HYSYS will make the round figure of the other compositions. This will slightly change the above user-defined compositions. Therefore, 0.1 mass % of octane composition is considered to do the below calculations.

1. Using the above composition generate phase envelope for the stream under the following conditions; Pressure – 5 barg; Temperature – 45°C

2. Using the above composition determine the bubble (boiling point) temperature of the stream at 6 barg pressure. Determine the boiling pressure at 100°C.

By specifying vapor fraction as 0 and pressure at 6 barg, the bubble point temperature is calculated as 46.52°C. With the use of phase envelope at these stream conditions, the boiling pressure at 100°C is 1807 KPa

3. If the required vapor standard gas flow rate is 3 MMSCFD (use stream conditions as in s.no-1) determine the corresponding mass flow rate of the stream.

With the help of adjuster unit operation (making sure maximum iterations and minimum variance), the mass flow rate of the stream at a standard gas flow rate of 3 MMSCFD is 10140 kg/h.

4. If the required actual volumetric rate of vapor at 5 barg pressure and 50°C is 20 m 3 /hr (use stream conditions as in S.No-1), determine the corresponding mass flow rate.

Using adjuster operation with minimum variance and maximum iterations, the corresponding mass flow rate of the stream of actual volume rate at 20 m³/hr is 1628 kg/h.

5. Stream A has the following conditions; Composition is

Methane – 0.1 mol %

Ethane – 0.2 mol %

Pentane – 0.5 mol %

Hexane – 0.2 mol%; Pressure – 5 barg; Temperature – 45°C; Flow rate – 15000 kg/hr

Stream B has the following conditions

Composition

Methane – 0.1 mol %

Pentane – 0.2 mol %

Hexane – 0.5 mol %

Nonane – 0.2 mol%; Pressure – 3 barg; Temperature – 80°C

Determine stream B flow rate such that the mixture stream actual volumetric rate is 125 m 3 /hr. Determine the mixture density and mixture viscosity.

By using stream A flowrate of 15000 kg/hr, when a mixture is set up to mix stream A and B, it is not converging to achieve a mixture stream volumetric flow to 125 m³/hr due to the large flow rate of stream A.

Therefore, stream A flowrate is taking as 1500 kg/hr.

The simulation is shown in the below picture.

With the help of adjuster and trial and error method, the stream flowrate of B at the given mixing condition of 125 m³/h of actual volume flow rate is 4340 kg/h.

The density of the mixture stream C is 46.71 kg/m³ and the vapor phase density is 6.051 kg/m³ and liquid phase density is 618 kg/m³.

The mixture stream C viscosity of the vapor phase is 0.0109 cP and that of the liquid phase is 0.2177 cP.