Method for drying a humid polymer powder and device suitable for said method

1. A method of drying polymer powders in a drying apparatus ( 1 ), which comprises the steps:

i) treatment of the polymer powder with a heated gas ( 6 a ) in the drying apparatus ( 1 ) equipped with an inlet ( 2 ) and an outlet ( 3 ) for the polymer powder and with heat registers ( 5 ) installed in an interior space ( 4 ) of the drying apparatus ( 1 ),

ii) introduction of the heated gas ( 6 a ) through lines ( 7 ) into the interior space ( 4 ),

iii) heating of the gas ( 6 ) in heat exchangers ( 9 ) for producing heated gas ( 6 a ), wherein

iv) the heating of the heat exchangers ( 9 ) for producing heated gas is effected by means of hot liquid 1,2-dichloroethane ( 19 ) which has been heated by means of thermal energy which originates from a plant for preparation of 1,2-dichloroethane ( 15 ), and

v) wherein hot water ( 5 a ) which has been heated in a heat exchanger ( 13 ) for heating water, for which heat is derived from 1,2-dichloroethane vapor ( 14 ) which has been heated by means of thermal energy which originates from the plant for the preparation of 1,2-dichloroethane ( 15 ), flows through the heat registers ( 5 ).

2. The method as claimed in claim 1 , wherein the gas ( 6 ) is air.

3. The method as claimed in claim 2 , wherein heated air ( 6 a ) is introduced into the interior space ( 4 ) through air lines ( 7 ) on an underside of the fluidized-bed dryer ( 1 ), resulting in fluidization of the polymer powder, and the heat registers ( 5 ) are heated by means of the hot water ( 5 a ), which leaves the heat registers ( 5 ) as cooled water ( 5 b ), and is reintroduced into the heat exchanger ( 13 ) for heating water so that water is circulated between heat registers ( 5 ) and the heat exchanger ( 13 ) for heating water.

4. The method as claimed in claim 3 , wherein liquid 1,2-dichloroethane from the plant for the preparation of 1,2-dichloroethane ( 15 ) is introduced into the heat exchangers ( 9 ) for producing heated gas so that waste heat of the liquid 1,2-dichloroethane is utilized for heating the air ( 6 ).

5. The method as claimed in claim 3 , wherein the hot liquid 1,2-dichloroethane is heated by means of waste heat from distillation columns of the plant for the preparation of 1,2-dichloroethane ( 15 ) and the hot liquid 1,2-dichloroethane is subsequently introduced into the heat exchangers ( 9 ) for heating gas so that waste heat of 1,2-dichloroethane preparation is utilized for heating the air ( 6 ).

6. The method as claimed in claim 1 , wherein the plant for the preparation of 1,2-dichloroethane ( 15 ) is a direct chlorination plant or an oxychlorination plant.

7. The method as claimed in claim 1 , wherein the drying apparatus is a fluidized-bed dryer.

8. The method as claimed in claim 1 , wherein the hot water ( 5 a ) has been heated in the heat exchanger ( 13 ) for heating water by use of a further hot fluid and the further hot fluid originates from the plant for the preparation of 1,2-dichloroethane ( 15 ).

9. An apparatus ( 1 ) for drying polymer powders, which has an inlet ( 2 ) and an outlet ( 3 ) for the polymer powder and heat registers ( 5 ) installed in an interior space ( 4 ) of the drying apparatus ( 1 ) and lines ( 7 ) for a heated gas ( 6 a ) for drying the polymer powder, which lines open into the interior space ( 4 ),

wherein the lines ( 7 ) are connected to heat exchangers ( 9 ) for heating gas ( 6 ) and the heat exchangers ( 9 ) for heating gas are connected to a plant for preparation of 1,2-dichloroethane ( 15 ) so that hot liquid 1,2-dichloroethane ( 19 ) which has been heated by means of thermal energy from the plant for the preparation of 1,2-dichloroethane ( 15 ) can be utilized for heating the gas ( 6 ),

wherein hot water ( 5 a ) is passed through the heat registers ( 5 ) which are connected to a heat exchanger ( 13 ) for heating water flowing through the heat registers ( 5 ) and the heat exchanger ( 13 ) for heating water is additionally connected via line ( 14 ) to the plant for the preparation of 1,2-dichloroethane ( 15 ), in which 1,2-dichloroethane vapor ( 14 ), which has been heated by means of thermal energy which originates from the plant for the preparation of 1,2-dichloroethane ( 15 ), is introduced and discharged through the heat exchanger ( 13 ) for heating water.

10. The apparatus as claimed in claim 9 , wherein the plant for the preparation of 1,2-dichloroethane ( 15 ) is a direct chlorination plant or an oxychlorination plant.

11. The apparatus as claimed in claim 9 , wherein the apparatus is a fluidized-bed dryer.

12. The apparatus as claimed in claim 11 , wherein the gas ( 6 ) is air, and wherein air lines ( 7 ) via which heated air ( 6 a ) is introduced into the interior space ( 4 ) are provided on an underside of the fluidized-bed dryer ( 1 ), and heating of the heat registers ( 5 ) is effected by means of the hot water ( 5 a ), which leaves the heat registers ( 5 ) as cooled water ( 5 b ) and is reintroduced into the heat exchanger ( 13 ) for heating water so that water is circulated between heat registers ( 5 ) and the heat exchanger ( 13 ) for heating water.

13. The apparatus as claimed in claim 12 , wherein the heat exchangers ( 9 ) for heating gas are connected to distillation columns from the plant for the preparation of 1,2-dichloroethane ( 15 ) so that waste heat of the liquid 1,2-dichloroethane from the distillation columns can be utilized for heating the air ( 6 ).