Patent DE-102010030279-A1 (DE)
Title: Method for cleaning separation of acrylic acid crystals from a suspension of its crystals in mother liquor using a device having a hydraulic washing column, comprises carrying out crystallization of acrylic acid during cooling
Inventor: HEILEK JOERG
IPC: C07C57/07
Filed: 2010-06-18
Abstract: The method for cleaning separation of acrylic acid crystals from a suspension of its crystals in mother liquor using a device having a hydraulic washing column that has a rotation symmetrical process area to its longitudinal axis running from top towards bottom, comprises carrying out crystallization of acrylic acid during cooling. The process area is limited by a cylindrical mantle wall and has two ends opposite to the symmetrical axis. Filter tubes of the device extend through the process area from top ends of the process area parallel to its longitudinal axis. The method for cleaning separation of acrylic acid crystals from a suspension of its crystals in mother liquor using a device having a hydraulic washing column that has a rotation symmetrical process area to its longitudinal axis running from top towards bottom, comprises carrying out crystallization of acrylic acid during cooling. The process area is limited by a cylindrical mantle wall and has two ends opposite to the symmetrical axis. Filter tubes of the device extend through the process area from top ends of the process area parallel to its longitudinal axis. The process area comprises a filter (7) that forms individual direct connection between the respective filter tube interior and the process area in the lower end of the process area, where the filter is implemented external of the process area from the washing column. The quotient Q=L/D from the interval (L) between the upper and lower end of the process area and the diameter (D) of the process area is 0.3-4. The crystal melt area of the washing column joins at the lower end of the process area. A rotation capable reduction device is integrated between both areas and a crystal melt circle is implemented through the crystal melt area. A first conveyor pump (11) is present external of the washing column and has a suction- and pressure side, where first conveyor connection guides from the crystal melt area of the washing column to suction side of the conveyor pump and second conveyor connection guides from the pressure side of the conveyor pump in the crystal melt area of the washing column and has an outlet from the crystal melt circle with adjustable flow. By a heat exchanger, the first conveyor connection guides from the crystal melt area to the suction side of the conveyor pump or the second conveyor connection guides from the pressure side of the conveyor pump to the crystal melt area. A distribution area is arranged at the upper end of the process area and is separated from the process area through a base, which has a passage that guides from the side of the base turned to the process area and from the side of the base turned away the process area in the distribution area. The second conveyor pump (8) has a suction and pressure side at external of the washing column and has a second source of the suspension. The first conveyor connection guides from the source to suction side of the conveyor pump and the second conveyor connection guides from the pressure side of the conveyor pump in the distribution area. The third conveyor pump (13) has a suction and pressure side at external of the washing column and has a third source of the suspension. The first conveyor connection guides from the suction side of the pump to the source and the second conveyor connection guides from the pressure side of the pump in the distribution area and/or in longitudinal section of the process area between its upper end and the filter of the filter tube. The separation process is carried out in its stationary operation. A stream of the suspension guides from the source through the first and second conveyor connection over the distribution area and through the passage in the process area of the washing column using a second pump. A stream of the control liquor guides from the source through the conveyor connection over the distribution area and the passage and/or directly in the process area of the washing column using third pump. A stream comprising mother liquor and the control liquor guides as waste stream in the interior of the filter tube and over the filter tube from the washing column over the filter of the filter tube. The formation of crystal bed at acrylic acid crystals is carried out through the mother- and if necessary control liquor in the process area of the washing column. The acrylic acid crystal wears out with the rotating reduction device. The stream of the acrylic acid crystal flows through the reduction device and/or conveys on the reduction device in the crystal bed. The crystal melt area comprises crystal melt circuit and the process area is filled with the acrylic acid, where the filling height of the fluid surpasses in the process area. The filling of the washing column is carried out in which the stream of the suspension from the source guides through the conveying connection over the distribution area and through the passage. The pressure is contact in dependent upon the duration of the supply of the stream. The average surface load of the filter calculates as arithmetic average value of the time point. The acrylic acid crystals are subjected to crystallization during cooling. The average surface load of the filter is 50 m 3>/(m 2>.h) and the quotient is >= 0.5.