## 1. Introduction

#### 1.1. Separation Vessel Used in Crude Oil Processing

#### 1.2. Simulation Model

#### 1.3. Simulation and Model Selection

#### 1.4. Research Aim and Outcome

## 2. Materials and Methods

#### 2.1. Process Simulation

#### 2.2. Thermodynamics Package

^{−1}·K), $T$ is the absolute temperature (K), V is the volume (m

^{3}), $b$ is the repulsive parameter in equation of state (m

^{3}·mol

^{−1}), $a$ is the attractive parameter in cubic equations of state (J·m

^{3}·mol

^{−2}), ${x}_{i}$ is the mole fraction of component i in the liquid phase, ${b}_{i}$ is an empirical coefficient selected by the simulator, ${T}_{{C}_{i}}$ is the temperature of component i at critical point (K), ${P}_{{C}_{i}}$ is the pressure of component i at critical point (Pa), ${k}_{il}$ is the binary interaction parameter in cubic equations of state, ${a}_{i}$ is an empirical coefficient selected by the simulator, ${\alpha}_{i}$ is an empirical coefficient selected by the simulator, $a{c}_{i}$ is an empirical coefficient selected by the simulator, ${T}_{{r}_{i}}$ is the reduced temperature (dimensionless), ${m}_{i}$ is an empirical coefficient selected by the simulator, and $w$ is the acentric factor.

#### 2.3. Simulation Conditions

#### 2.4. Sensitivity Study

#### 2.5. Phase Envelope

## 3. Results and Discussion

#### 3.1. Effect of Changing the Pressure of the HP Sparator on the Gas Flow Rate, Methane Concentration and Preheater Heating Duty

#### 3.2. High Pressure Separator Temperature Effect on the Gas Flow Rate, Methane Concentration and Preheater Heating Duty

#### 3.3. Effect of Increasing the Inlet HP Separator Feed Flow Rate on the Gas Flow Rate, Methane Mole Fraction, and Heat Required by the Preheater

^{4}to 3.08 × 10

^{4}kg/h (CHEMCAD) and from 1.9661 × 10

^{4}to 2.7562 × 10

^{4}kg/h (UniSim), which explains the available capacity of the HP separator to accommodate an increased inlet flow rate. Moreover, the methane mole fraction remained constant at 0.756045 and 0.741194 in CHEMCAD and UniSim, respectively, since the outlet gas composition is not a function of the inlet flow rate. The composition of the feed, as well as pressure and temperature, are the parameters that influenced the separation process equilibrium constant.

^{3}to 154.56 × 10

^{3}kg/h, as shown in Figure 5. A remarkable increase in the heating duty of the liquid hydrocarbons can be seen when the inlet feed flow rate of the HP separator was increased, since it required more energy to keep the process temperature constant.

#### 3.4. Phase Envelope

## 4. Conclusions and Further Work

## Conflicts of Interest

## Nomenclature

A | Empirical coefficient, selected by the simulator |

${A}_{i}$ | Empirical coefficient, selected by the simulator |

$B$ | Empirical coefficient, selected by the simulator |

${B}_{i}$ | Empirical coefficient, selected by the simulator |

$a$ | Attractive parameter in cubic equations of state (J·m^{3}·mol^{−2}) |

${a}_{il}$ | Empirical coefficient, selected by the simulator |

$b$ | Repulsive parameter in equation of state (m^{3}·mol^{−1}) |

${b}_{i}$ | Empirical coefficient, selected by the simulator |

${a}_{i}$ | Empirical coefficient, selected by the simulator |

$a{c}_{i}$ | Empirical coefficient, selected by the simulator |

${K}_{i}$ | K-value of component |

${k}_{il}$ | Binary interaction parameter in cubic equations of state |

${m}_{i}$ | Empirical coefficient, selected by the simulator |

P | Total pressure (Pa) |

${P}_{{C}_{i}}$ | Pressure of component i at critical point (Pa) |

$R$ | Universal gas constant (J·mol^{−1}·K) |

$T$ | Absolute temperature (K) |

${T}_{{C}_{i}}$ | Temperature of component i at critical point (K) |

${T}_{{r}_{i}}$ | Reduced temperature (dimensionless) |

V | Volume (m^{3}) |

${x}_{i}$ | Mole fraction of component i in the liquid phase |

${y}_{i}$ | Mole fraction of component i in the vapor phase |

$Z$ | Compressibility factor |

${\alpha}_{i}$ | Function in cubic equations of state |

${\Phi}_{il}$ | Fugacity coefficient of component i in liquid phase |

${\Phi}_{iv}$ | Fugacity coefficient of component i in vapor phase |

$\omega $ | Acentric factor |

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**Figure 1.**Thermodynamics model selection chart. Reproduced with permission from Towler, G. and Sinnott, R.K., Chemical engineering design: principles, practice and economics of plant and process design; published by Elsevier, 2012. [20].

**Figure 2.**A diagram of the separation process of crude oil developed by using the CHEMCAD Simulation Software package.

**Figure 3.**HP separator pressure effect on the produced methane mole fraction, the produced gas flow and on the heating duty of the preheater rate.

Component | Chemical Formula | Mass Flow Rate (kg/h) |
---|---|---|

Hydrogen Sulfide | H_{2}S | 854.1820 |

Carbon Dioxide | CO_{2} | 2041.8970 |

Nitrogen | N_{2} | 399.9500 |

Methane | CH_{4} | 13,924.100 |

Ethane | C_{2}H_{6} | 6194.2178 |

Propane | C_{3}H_{8} | 6045.8480 |

I-Butane | C_{4}H_{10} | 889.7230 |

N-Butane | C_{4}H_{10} | 3771.3100 |

I-Pentane | C_{5}H_{12} | 1349.6700 |

N-Pentane | C_{5}H_{12} | 2748.3030 |

N-Hexane | C_{6}H_{14} | 3769.9010 |

Heptane | C_{7}H_{16} | 3795.1810 |

Octane | C_{8}H_{18} | 4069.6010 |

Nonane | C_{9}H_{20} | 3773.9570 |

Decane | C_{10}H_{22} | 3366.5690 |

Undecane | C_{11}H_{24} | 3173.9910 |

Dodecane | C_{12}H_{26} | 2725.6790 |

Tridecane | C_{13}H_{28} | 2585.4040 |

Tetradecane | C_{14}H_{30} | 2321.1870 |

Pentadecane | C_{15}H_{32} | 2065.0300 |

Hexadecane | C_{16}H_{34} | 1831.2710 |

Heptadecane | C_{17}H_{36} | 1717.1020 |

Octadecane | C_{18}H_{38} | 1532.6370 |

Nonadecane | C_{19}H_{40} | 1570.9020 |

Water | H_{2}O | 987.6000 |

Parameter | Design (Range) | Unit Operating Conditions (Design) | Unit Operating Conditions (Data) | Simulation Data Input |
---|---|---|---|---|

Temperature (°C) | −10 to 80 | 20–45 | 43 | 43 |

Pressure (bar) | Up to 92 | 78–83 | 80 | 80 |

Feed flow rate (kmol/h) | - | 1215.6480 | 1800.5150 | 1800.5150 |

Inlet Feed Components | Normalized Inlet Feed Mole Fraction (Provided Data and Simulation) | Normalized Outlet Gas Mole Fraction (Provided Data) | Normalized Outlet Gas Mole Fraction (Simulation) | Normalized Outlet Liquid Phase Stream Product (Provided Data) | Normalized Outlet Liquid Phase Stream Product (Simulation) |
---|---|---|---|---|---|

H_{2}S | 0.0143 | 0.0121 | 0.0122 | 0.0175 | 0.0174 |

CO_{2} | 0.0264 | 0.0316 | 0.0323 | 0.0224 | 0.0217 |

Nitrogen | 0.0081 | 0.0139 | 0.0139 | 0.0024 | 0.0023 |

Methane | 0.4938 | 0.7411 | 0.7560 | 0.2577 | 0.2405 |

Ethane | 0.1172 | 0.1204 | 0.1126 | 0.1212 | 0.1297 |

Propane | 0.0780 | 0.0508 | 0.0463 | 0.1125 | 0.1175 |

i-Butane | 0.0087 | 0.0037 | 0.0034 | 0.0147 | 0.0151 |

n-Butane | 0.0369 | 0.0133 | 0.0120 | 0.0649 | 0.0663 |

i-Pentane | 0.0106 | 0.0023 | 0.0022 | 0.0203 | 0.0205 |

n-Pentane | 0.0217 | 0.0041 | 0.0037 | 0.0421 | 0.0426 |

n-Hexane | 0.0249 | 0.0024 | 0.0021 | 0.0509 | 0.0512 |

Heptanes | 0.0215 | 0.0017 | 0.0009 | 0.0444 | 0.0453 |

Octanes | 0.0203 | 0.0007 | 0.0004 | 0.0428 | 0.0431 |

Nonanes | 0.0167 | 0.0003 | 0.0002 | 0.0356 | 0.0358 |

Decanes | 0.0135 | 0.0001 | 0.0001 | 0.0288 | 0.0289 |

Undecanes | 0.0116 | 0.0001 | 0.0000 | 0.0247 | 0.0248 |

Dodecanes | 0.0091 | 0.0000 | 0.0000 | 0.0195 | 0.0196 |

Tridecanes | 0.0080 | 0.0000 | 0.0000 | 0.0171 | 0.0172 |

Tetradecane | 0.0067 | 0.0000 | 0.0000 | 0.0143 | 0.0143 |

Pentadecans | 0.0055 | 0.0000 | 0.0000 | 0.0119 | 0.0119 |

Hexadecanes | 0.0046 | 0.0000 | 0.0000 | 0.0099 | 0.0099 |

Heptadecane | 0.0041 | 0.0000 | 0.0000 | 0.0087 | 0.0087 |

Octadecanes | 0.0034 | 0.0000 | 0.0000 | 0.0074 | 0.0074 |

Nonadecanes | 0.0033 | 0.0000 | 0.0000 | 0.0071 | 0.0072 |

H_{2}O | 0.0312 | 0.0015 | 0.0015 | 0.0012 | 0.0011 |

Total | 1 | 1 | 1 | 1 | 1 |

Separator Temperature (°C) | Gas Flow Rate (kmol/h) | Methane Mole Fraction |
---|---|---|

43 | 871.1500 | 0.7560 |

53 | 937.7800 | 0.7399 |

63 | 1004.9700 | 0.7241 |

73 | 1073.1800 | 0.7086 |

83 | 1142.9800 | 0.6934 |

Separator Temperature (°C) | Gas Flow Rate (kmol/h) | Methane Mole Fraction |
---|---|---|

43 | 896.9400 | 0.7412 |

53 | 950.5100 | 0.7248 |

63 | 1000.6800 | 0.7089 |

73 | 1048.3200 | 0.6935 |

83 | 1094.2600 | 0.6783 |

Inlet Feed Flow Rate × 10^{3} (kg/h) | Outlet Gas Flow Rate × 10^{4} (kmol/h) | Mole Fraction of Methane in the Outlet Gas Stream |
---|---|---|

95.97 | 1.9100 | 0.7560 |

105.57 | 2.1009 | 0.7560 |

116.12 | 2.3110 | 0.7560 |

127.74 | 2.5421 | 0.7560 |

140.51 | 2.7964 | 0.7560 |

154.56 | 3.0759 | 0.7560 |

**Table 7.**Effect of changing inlet feed flow rate on the produced methane mole fraction and on the outlet gas flow rate (UniSim).

Inlet Feed Flow Rate × 10^{3} (kg/h) | Outlet Gas Flow Rate × 10^{4} (kmol/h) | Mole Fraction of Methane in the Outlet Gas Stream |
---|---|---|

95.97 | 1.9660 | 0.7412 |

105.57 | 2.0934 | 0.7412 |

116.12 | 2.2302 | 0.7412 |

127.74 | 2.3806 | 0.7412 |

140.51 | 2.5517 | 0.7412 |

154.56 | 2.7562 | 0.7412 |

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