Abstract: A plant for preparing a purified isomeric methylene diphenyl diisocyanate monomer from a mixture of different isomeric monomers is disclosed herein. The plant can comprise a distillation apparatus, which comprises: a) a distillation column including a structured packing, b) a source for a mixture of different isomeric methylene diphenyl diisocyanate monomers, c) an evaporator, d) an overhead vapor condenser, e) optionally, an overhead vacuum system and f) a flow-controlled reflux system. The overhead vapor condenser comprises a shell and tube arrangement and is embodied so as to directly subcool the condensate to less than 47° C. The flow-controlled reflux system comprises a heater, which is embodied so as to reheat a partial stream of the condensate formed in the overhead vapor condenser up to 190° C.

Abstract: A process for treating waste fluid generated during a petrochemical process. The process comprises: subjecting at least one first water-based wastewater stream to at least one freeze concentration stage so as to produce a third clean water stream and a fourth concentrated water-based wastewater stream, subjecting at least one second organic fluid-based waste fluid stream to at least one separation stage so as to produce a fifth purified product stream and a sixth concentrated organic fluid-based waste fluid stream, forwarding the fourth concentrated water-based wastewater stream and the sixth concentrated organic fluid-based waste fluid stream to an incinerator, and incinerating the streams in the incinerator. The process is controlled such that incineration of the sixth concentrated organic fluid-based waste fluid stream generates at least 70% of an energy necessary to incinerate the fourth concentrated water-based wastewater stream.

Abstract: A wash column apparatus for the use in a suspension crystallization process for separating crystals from a crystal suspension mixture includes a cylindrical vessel including a piston with a piston head including a filter and a piston rod, movable in the cylindrical vessel, an inlet for supplying a crystal suspension mixture into the cylindrical vessel, an outlet for discharging mother liquor from the cylindrical vessel, an outlet for discharging crystals or crystal melt from the cylindrical vessel, a circulation conduit for circulating melt arranged outside the vessel, in communication with the wash chamber, a static grid element arranged in the wash chamber for restricting movement of the crystal bed and for directing the wash liquid entering into the cylindrical vessel from the circulation conduit so as to homogeneously distribute it over the entire cross-section of the wash column.

Abstract: A plant for preparing a purified isomeric methylene diphenyl diisocyanate monomer from a mixture of different isomeric monomers is disclosed herein. The plant can comprise a distillation apparatus, which comprises: a) a distillation column including a structured packing, b) a source for a mixture of different isomeric methylene diphenyl diisocyanate monomers, c) an evaporator, d) an overhead vapor condenser, e) optionally, an overhead vacuum system and f) a flow-controlled reflux system. The overhead vapor condenser comprises a shell and tube arrangement and is embodied so as to directly subcool the condensate to less than 47° C. The flow-controlled reflux system comprises a heater, which is embodied so as to reheat a partial stream of the condensate formed in the overhead vapor condenser up to 190° C.

Abstract: A wash column apparatus for the use in a suspension crystallization process for separating crystals from a crystal suspension mixture includes a cylindrical vessel including a piston with a piston head including a filter and a piston rod, movable in the cylindrical vessel, an inlet for supplying a crystal suspension mixture into the cylindrical vessel, an outlet for discharging mother liquor from the cylindrical vessel, an outlet for discharging crystals or crystal melt from the cylindrical vessel, a circulation conduit for circulating melt arranged outside the vessel, in communication with the wash chamber, a static grid element arranged in the wash chamber for restricting movement of the crystal bed and for directing the wash liquid entering into the cylindrical vessel from the circulation conduit so as to homogeneously distribute it over the entire cross-section of the wash column.

Abstract: A process to purify a compound comprising a suspension crystallization step and additionally comprises a layer crystallization step and a storage step of an intermediate product obtained from the layer crystallization step before to its further purification in the suspension crystallization step.

Abstract: A process to purify a compound comprising a suspension crystallization step and additionally comprises a layer crystallization step and a storage step of an intermediate product obtained from the layer crystallization step before to its further purification in the suspension crystallization step.

Abstract: The invention relates to a crystallization process for recovering a pure substance from a liquid mixture, a starting mixture being cooled down in a crystallization zone to form a crystal suspension from which crystals of the pure substance are recovered, wherein a) the crystal suspension is subjected to a crude preliminary separation in a (preliminary) separation zone to form a first mother liquor and a crystal mass containing relatively small particles, b) the crystal mass formed in a) is allowed to develop in a development zone at a temperature which is higher than that of the crystallization zone and lower than the melting point of the substance to be recovered, and is separated into a developed crystal mass and a second mother liquor, and c) the developed crystal mass formed in b) is separated into a third mother liquor and the intended pure substance in a separation zone, as well as to an apparatus suitable for performing said process.