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Hooman Fatoorehchi Assistant Professor School of Chemical Engineering University of Tehran, Tehran, Iran  Process Engineering
Natural Gas Compression; Joffe's Formula The adiabatic theoretical horsepower to compress 1 MMSCFD (i.e. volumetric flow at standard conditions: 60 deg F, 14.65 pisa): $-w=0.08531 \frac{k}{k-1}T_1 \left[ \left( \frac{P_2}{P_1} \right)^{z\hspace{0.1cm}(k-1)/k}-1 \right]$, where $k=\frac{C_p}{C_v}$ for gas at suction conditions $z$ is compressibility factor at suction conditions $P_1$ is suction pressure, psia $P_2$ is discharge pressure, psia $T_1$ is suction-gas temperature, deg R NOTE: The maximum allowable pressure drop on the tube side of a heat exchanger (for gases) is 10 psi. Typically, the pressure drop across an HE would be 3 to 10 psi. NOTE: Reasonable pressure drop per tray (usually sieve tray) is 0.1 psi (~ 3 in H2O). NOTE: Tower operating pressure is determined most often by the temperature of the available condensing medium, 120 deg F if cooling water (worst summer case) $\rightarrow$ calculate bubble pressure at 120 deg F for reflux drum pressure OR by the maximum allowable reboiler temperature, (150 psig (saturated) steam = 366 deg F) $\rightarrow$ calculate bubble pressure at 366 deg F for reboiler pressure. NOTE: (Fahrenheit to Rankine conversion) deg F + 460 = deg R (Horsepower to kW conversion) 1 HP = 0.7457 ~ 0.746 kW 1 BTU = 1055.06 J Mother Processes in Petrochemical Industries: (1) Steam Cracking Feedstock: Ethane, Propane, Naphtha, or Gas oil depending on availability. Main Product: Ethylene (building block of petrochemicals). Noncatalytic Process. (2) Catalytic Reforming Feedstock: Naphtha Main Product: Benzene, Toluene, Xylenes. (2) Steam Reforming Feedstock: Methane Main Product: Syngas (CO and Hydrogen). Hydrogen is then used to produce ammonia $ \rightarrow $ urea $\rightarrow$ melamine; nitric acid; nitrates; methanol (CO + H2 $\rightarrow$ CH3OH; CO2 + 3 H2 $\rightarrow$ CH3OH + H2O); 2 methanol + O2 $\rightarrow$ 2 formaldehyde + 2 H2O; methanol + CO $\rightarrow$ acetic acid
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