(6) condensing the fluidized bed reactor to give the product enters the heat exchanger and sequentially three tube condenser, the heat exchanger
is heated while hydrogen
is also the product of the condensation. The three-stage tubular condenser is condensed by circulating cooling water, and the condensation efficiency of the heat exchanger and the three-stage tubular condenser is 99.9%. The condensed non-condensable gas is trapped by the tail gas trap, separated into hydrogen and crude products by filtration through a filter, and the circulating hydrogen gas enters the vaporizer through the hydrogen buffer tank, and the crude product enters the continuous separator.
(7) Separation The crude product obtained from the existing project is separated by a continuous separator. The continuous separator is separated by the principle of standing stratification to obtain crude product and aniline water. The specific gravity of o-toluidine is small, located in the upper layer, from the continuous separator. The upper overflow port is discharged to obtain crude o-toluidine; the water has a large specific gravity, and is located in the lower layer, and is discharged from the lower overflow port of the continuous separator to obtain aniline water; the crude o-toluidine is temporarily stored in the temporary storage tank, and the aniline water is stored in the aniline. Water storage tank. The aniline water is azeotroped.
(8) Dehydration The crude product of the crude o-toluidine temporary storage tank is driven into a dehydration tower for dehydration. The dehydration tower separates o-toluidine from water and high boilers according to the difference in boiling point of o-toluidine with water and high boilers. The crude o-toluidine is preheated to 150 ° C through the dehydration tower preheater and then enters the dehydration tower from the bottom of the tower (the dehydration tower is a packed tower, the tower is operated under negative pressure, the vacuum is generated by a water ring vacuum pump, and the temperature at the top of the tower is controlled at 75 ° C, the vacuum is 480 mmHg, the temperature of the tower is controlled at 164 ° C, the degree of vacuum is 410 mmHg, the reboiler uses 1.0 MPa steam), the rising steam is in countercurrent contact with the falling liquid, in the contact between the two phases, in the falling liquid Volatile (low-boiling substances, mainly in water and o-toluidine in this EIA) are continuously transferred to the vapor. The volatile (high-boiling substances, this EIA is mainly high-boiling) component in the vapor is continuously The transfer in the falling liquid, the closer the vapor is to the top of the tower, the higher the concentration of the volatile components, and the closer the falling liquid is to the bottom of the tower, the more the volatile components are enriched, and the purpose of component separation is achieved. The water recovered at the top of the column and a small amount of o-toluidine are returned to the continuous separator, and o-toluidine at the bottom of the column and a small amount of high boilers are passed to the rectification column for further rectification.
(9) Rectification The crude product from the dehydration column is sent to the rectification column for rectification. The rectification principle of the rectification column is the same as that of the dehydration column, and the substance is separated by the difference in boiling point of the material. A qualified product is produced at the top of the tower, and a small amount of rectification residue (the main component is high-boiling substance and a very small amount of o-nitrotoluene) is produced at the bottom of the tower, and is disposed of as a dangerous and qualified department.
(10) Azeotropic crude o-toluidine is separated from the aniline pump separated by a continuous separator into azeotrope column to distill a small amount of material to be recycled, and the wastewater enters the sewage treatment station of the plant for treatment. The principle of the azeotrope is the same as that of the dehydration column, and the substance is separated by the difference in boiling point of the material.