In this process, acrylic acid (AA) is produced through the oxidation of propylene at 300°C and 2.57 atm with water as the by-product. In a year, this chemical plant operates 24 hours a day for 330 working days, with a total production of 250,000 metric tonnes of AA. The main product is AA, while the side products are acetic acid (ACA), water (H2O), and carbon dioxide (CO2). The selectivity of AA over ACA is 16 and the conversion of propylene to the side reaction 2 is half of the side reaction 1. Details of the reaction are as follows: C3H6 (g) + 1.5O2 (g) → C3H4O2 (v) + H2O (v) (Main reaction) C3H6 (g) + 2.5O2 (g) → C2H4O2 (v) + CO2 (g) + H2O (v) (Side reaction 1) C3H6 (g) + 4.5O2 (g) → 3CO2 (g) + 3H2O (v) (Side reaction 2) Pure oxygen is added to a recycle stream containing a mixture of carbon dioxide and oxygen before being fed to an oxidation reactor. Before feeding it to the reactor, the mixed stream is heated to 300°C and compressed to 2.57 atm. Pure propylene is fed to the reactor through another stream. The preheated gases react exothermically in a jacketed reactor that uses cooling water as a cooling medium to maintain the reaction temperature at 300°C. Propylene is the limiting reactant, and oxygen is fed in excess of 20% into the oxidation reactor. A hot gaseous mixture is produced from the reactor contain acrylic acid as the major product. Acetic acid, carbon dioxide, and water are the side products with unreacted oxygen. The hot gaseous mixture is cooled down in a condenser from 300 to 50°C and fed to a flash column. The column separates the mixture and sends gaseous material such as carbon dioxide and unreacted oxygen through the top product stream to a gas separator. The bottom stream from the flash column contains acrylic acid, acetic acid, and water. The gas separator is used to separate the carbon dioxide gas from the oxygen, and the oxygen is then recycled and mixed with the oxygen feed stream. The efficiency of the gas separator is around 95% and the recycle stream have composition 99 mol% of Oxygen. Before it is recycled, the stream’s pressure is reduced to 1 atm through a valve to match the pressure of the oxygen feed stream. The pressure and temperature of the bottom stream for the flash column are increased to 3 atm and 148°C using a pump, and a heater, respectively. Then, it is fed to a distillation column (DC1) to purify the acrylic acid. The top outlet stream contains water, acetic acid and 5% of the total molar flow of acrylic acid fed to the DC1. The bottom consists of acetic acid and acrylic acid only, where the purity of the acrylic acid obtained is 99.0 mol%. The top outlet is sent to the liquid-liquid extractor (LLE) to separate the water from the acetic acid. 31,680 kmol/hr of ethylene glycol (EG) is used as a solvent to extract the water and flows out as the top stream of the extractor column, leaving acetic acid, solvent, and a small amount of water in the bottom stream. The extraction efficiency is 90% and 1% of solvent fed to the extractor loss to the top stream. The bottom stream will then undergo a distillation process (DC2) to separate the solvent and the acetic acid. The distillate stream contains 95 mol% of acetic acid fed to the distillation column and water, while the bottom stream contains only a small amount of acetic acid and solvent. Draw Process Flow Diagram Only
In this process, acrylic acid (AA) is produced through the oxidation of propylene at 300°C and
2.57 atm with water as the by-product. In a year, this chemical plant operates 24 hours a day
for 330 working days, with a total production of 250,000 metric tonnes of AA. The main product
is AA, while the side products are acetic acid (ACA), water (H2O), and carbon dioxide (CO2).
The selectivity of AA over ACA is 16 and the conversion of propylene to the side reaction 2 is
half of the side reaction 1. Details of the reaction are as follows:
C3H6 (g) + 1.5O2 (g) → C3H4O2 (v) + H2O (v) (Main reaction)
C3H6 (g) + 2.5O2 (g) → C2H4O2 (v) + CO2 (g) + H2O (v) (Side reaction 1)
C3H6 (g) + 4.5O2 (g) → 3CO2 (g) + 3H2O (v) (Side reaction 2)
Pure oxygen is added to a recycle stream containing a mixture of carbon dioxide and oxygen
before being fed to an oxidation reactor. Before feeding it to the reactor, the mixed stream is
heated to 300°C and compressed to 2.57 atm. Pure propylene is fed to the reactor through
another stream. The preheated gases react exothermically in a jacketed reactor that uses
cooling water as a cooling medium to maintain the reaction temperature at 300°C. Propylene
is the limiting reactant, and oxygen is fed in excess of 20% into the oxidation reactor.
A hot gaseous mixture is produced from the reactor contain acrylic acid as the major product.
Acetic acid, carbon dioxide, and water are the side products with unreacted oxygen. The hot
gaseous mixture is cooled down in a condenser from 300 to 50°C and fed to a flash column.
The column separates the mixture and sends gaseous material such as carbon dioxide and
unreacted oxygen through the top product stream to a gas separator. The bottom stream from
the flash column contains acrylic acid, acetic acid, and water. The gas separator is used to
separate the carbon dioxide gas from the oxygen, and the oxygen is then recycled and mixed
with the oxygen feed stream. The efficiency of the gas separator is around 95% and the recycle
stream have composition 99 mol% of Oxygen. Before it is recycled, the stream’s pressure is
reduced to 1 atm through a valve to match the pressure of the oxygen feed stream.
The pressure and temperature of the bottom stream for the flash column are increased to 3
atm and 148°C using a pump, and a heater, respectively. Then, it is fed to a distillation column
(DC1) to purify the acrylic acid. The top outlet stream contains water, acetic acid and 5% of
the total molar flow of acrylic acid fed to the DC1. The bottom consists of acetic acid and
acrylic acid only, where the purity of the acrylic acid obtained is 99.0 mol%. The top outlet is
sent to the liquid-liquid extractor (LLE) to separate the water from the acetic acid. 31,680
kmol/hr of ethylene glycol (EG) is used as a solvent to extract the water and flows out as the
top stream of the extractor column, leaving acetic acid, solvent, and a small amount of water
in the bottom stream. The extraction efficiency is 90% and 1% of solvent fed to the extractor
loss to the top stream. The bottom stream will then undergo a distillation process (DC2) to
separate the solvent and the acetic acid. The distillate stream contains 95 mol% of acetic acid
fed to the distillation column and water, while the bottom stream contains only a small amount
of acetic acid and solvent.
Draw Process Flow Diagram Only
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