Hydrotreating
ENERGY BALANCE
Desulphurizer
Here Sulphur in Naphtha is made to react with Hydrogen in presence of catalysts to give Hydrogen Sulphide. This reaction takes place at a temperature of 623 K
H2 + S
Hydrogen and Naphtha are assumed to be stored at 303 K
Specific Heat capacity of naphtha is assumed to be 3.5235 kcal/kmol
Specific Heat capacity of Hydrogen =(6.62+0.00081T) kcal/kmol K
∆H = ∑ ni ∫ C pi dT = 6.015915 x10 6 kcal hr i Hence heat required to raise their temperature from 303 K to 693 K
Assuming that the fuel used is Natural gas (calorific value = 39383.82 kJ/m3)
Thus amount of fuel needed to supply this quantity of heat =152.75 m3/hr
Heat liberated within the reactor due to reaction = 1414.575 kcal/kmol
T
∆H sul = ∑ ni ∫ ni C pi dT = 15560.325
623
∆Hr Hence total heat liberated = 11.1 x 1414.575 = 15560.325 kcal/hr
This heat released is utilized in increasing the temperature of the effluents
Solving the equation by a trial and error process we obtain the outlet temperature value as 623.8 K. Hence it is assumed that the outlet temperature is
623 K itself.
Primary Reformer
Within the reformer steam reacts with Naphtha and produces Carbon monoxide and Hydrogen. Side reactions also take place producing Carbon dioxide and
(
)
C n H m + nH 2 O → nCO + m 2 + n H 2
Methane. The exit gases from the reformer are at a temperature of 1093 K .
∆Hr is 53.376 x 103 kcal/kmol
∆H1 is 10.29823 x 107 kcal/hr
CO + H 2 O → CO2 + H 2
∆Hr is –7.834 x 103 kcal/kmol
∆H2 is –0.44489 x 107 kcal/hr
CO + 3H 2 → CH 4 + H 2 O
∆Hr is –49.271 x 103
∆H3 is –1.66672 x 107 kcal/hr
Heat required to raise the temperature of the reaction products from 673 K to
1093 K is
T
∆H ref = ∑ ni ∫ ni C pi dT = 13.94433 x10 7 kcal hr i
623
Thus total heat to be supplied is sum of all the heat requirements and the enthalpy of reactions =22.11061 x 107 kcal/hr
Fuel required for supplying this amount of heat is 5614.13 m3/hr of natural gas.
Desulphurizer
Here Sulphur in Naphtha is made to react with Hydrogen in presence of catalysts to give Hydrogen Sulphide. This reaction takes place at a temperature of 623 K
H2 + S
Hydrogen and Naphtha are assumed to be stored at 303 K
Specific Heat capacity of naphtha is assumed to be 3.5235 kcal/kmol
Specific Heat capacity of Hydrogen =(6.62+0.00081T) kcal/kmol K
∆H = ∑ ni ∫ C pi dT = 6.015915 x10 6 kcal hr i Hence heat required to raise their temperature from 303 K to 693 K
Assuming that the fuel used is Natural gas (calorific value = 39383.82 kJ/m3)
Thus amount of fuel needed to supply this quantity of heat =152.75 m3/hr
Heat liberated within the reactor due to reaction = 1414.575 kcal/kmol
T
∆H sul = ∑ ni ∫ ni C pi dT = 15560.325
623
∆Hr Hence total heat liberated = 11.1 x 1414.575 = 15560.325 kcal/hr
This heat released is utilized in increasing the temperature of the effluents
Solving the equation by a trial and error process we obtain the outlet temperature value as 623.8 K. Hence it is assumed that the outlet temperature is
623 K itself.
Primary Reformer
Within the reformer steam reacts with Naphtha and produces Carbon monoxide and Hydrogen. Side reactions also take place producing Carbon dioxide and
(
)
C n H m + nH 2 O → nCO + m 2 + n H 2
Methane. The exit gases from the reformer are at a temperature of 1093 K .
∆Hr is 53.376 x 103 kcal/kmol
∆H1 is 10.29823 x 107 kcal/hr
CO + H 2 O → CO2 + H 2
∆Hr is –7.834 x 103 kcal/kmol
∆H2 is –0.44489 x 107 kcal/hr
CO + 3H 2 → CH 4 + H 2 O
∆Hr is –49.271 x 103
∆H3 is –1.66672 x 107 kcal/hr
Heat required to raise the temperature of the reaction products from 673 K to
1093 K is
T
∆H ref = ∑ ni ∫ ni C pi dT = 13.94433 x10 7 kcal hr i
623
Thus total heat to be supplied is sum of all the heat requirements and the enthalpy of reactions =22.11061 x 107 kcal/hr
Fuel required for supplying this amount of heat is 5614.13 m3/hr of natural gas.