The present invention relates to a process for purifying a wastewater stream WW1 contaminated with nitrobenzene, comprising (I) stripping of the wastewater stream WW1 with a stripping gas SG1 in a continuously operated stripping column to obtain a wastewater stream WW2 which contains nitrobenzene in a concentration reduced relative to WW1 (c.sub.NB,WW2), (II) further purification of the wastewater stream WW2 in a wastewater treatment plant, wherein a target value (c.sub.NB,WW2,TARGET) is specified for the concentration of nitrobenzene in the wastewater stream WW2, which is greater than zero but takes into account the requirements of the wastewater treatment plant for the maximum content of nitrobenzene in the wastewater streams supplied thereto, wherein, for at least one combination of specified boundary conditions of (a) nitrobenzene concentration in WW1, (b) the temperature of WW1, and (c) the temperature of SG1, a set of linear mathematical relationships of the type m.sub.SG1=x.Math.m.sub.WW1 is stored in a database, which linear mathematical relationships define a range of concentrations of nitrobenzene in WW2, wherein the set comprises, in addition to a mathematical relationship (0) which corresponds to the target value c.sub.NB,WW2,TARGET, at least a first mathematical relationship (1) for a first value of c.sub.NB,WW2, which corresponds to 98% of the target value c.sub.NB,WW2,TARGET, and a second linear mathematical relationship (2) for a second value of c.sub.NB,WW2, which corresponds to 102% of the target value c.sub.NB,WW2,TARGET, and wherein the flow rate of the stripping gas is adapted to the flow rate of the wastewater WW1 such that the flow rate of WW1 is within a range of values (AB) that is generated by the first mathematical relationship (1) and the second mathematical relationship (2) at the respective flow rate of WW1, and controlling the concentration of nitrobenzene in WW2 (c.sub.NB,WW2) by adjusting the flow rate of stripping gas SG1 accordingly in the event of a measured actual value of this concentration which is outside a window of >98% to <102% of the target value.

The present invention relates to a process for purifying a wastewater stream WW1 contaminated with nitrobenzene, comprising (I) stripping of the wastewater stream WW1 with a stripping gas SG1 in a continuously operated stripping column to obtain a wastewater stream WW2 which contains nitrobenzene in a concentration reduced relative to WW1 (c.sub.NB,WW2), (II) further purification of the wastewater stream WW2 in a wastewater treatment plant, wherein a target value (c.sub.NB,WW2,TARGET) is specified for the concentration of nitrobenzene in the wastewater stream WW2, which is greater than zero but takes into account the requirements of the wastewater treatment plant for the maximum content of nitrobenzene in the wastewater streams supplied thereto, wherein, for at least one combination of specified boundary conditions of (a) nitrobenzene concentration in WW1, (b) the temperature of WW1, and (c) the temperature of SG1, a set of linear mathematical relationships of the type m.sub.SG1=x.Math.m.sub.WW1 is stored in a database, which linear mathematical relationships define a range of concentrations of nitrobenzene in WW2, wherein the set comprises, in addition to a mathematical relationship (0) which corresponds to the target value c.sub.NB,WW2,TARGET, at least a first mathematical relationship (1) for a first value of c.sub.NB,WW2, which corresponds to 98% of the target value c.sub.NB,WW2,TARGET, and a second linear mathematical relationship (2) for a second value of c.sub.NB,WW2, which corresponds to 102% of the target value c.sub.NB,WW2,TARGET, and wherein the flow rate of the stripping gas is adapted to the flow rate of the wastewater WW1 such that the flow rate of WW1 is within a range of values (AB) that is generated by the first mathematical relationship (1) and the second mathematical relationship (2) at the respective flow rate of WW1, and controlling the concentration of nitrobenzene in WW2 (c.sub.NB,WW2) by adjusting the flow rate of stripping gas SG1 accordingly in the event of a measured actual value of this concentration which is outside a window of >98% to <102% of the target value.

A distillation column including a plurality of alternating plates and spacers stacked in a z-direction is provided. The plates include a respective liquid channeling network on a top surface thereof, a respective vapor opening, and a respective descending ramp. The respective descending ramps abut a respective liquid feed location of the plate immediately below to form a continuous liquid channeling network. The respective vapor openings of adjacent plates are located on opposite sides of the distillation column and form a continuous S-shaped vapor channel defined by the plurality of alternating plates and spacers, and the respective vapor openings. Systems including such distillation columns and processes of distilling a fluid mixture are also provided.

A distillation column including a plurality of alternating plates and spacers stacked in a z-direction is provided. The plates include a respective liquid channeling network on a top surface thereof, a respective vapor opening, and a respective descending ramp. The respective descending ramps abut a respective liquid feed location of the plate immediately below to form a continuous liquid channeling network. The respective vapor openings of adjacent plates are located on opposite sides of the distillation column and form a continuous S-shaped vapor channel defined by the plurality of alternating plates and spacers, and the respective vapor openings. Systems including such distillation columns and processes of distilling a fluid mixture are also provided.

Methods and systems for converting ammonium waste streams into certifiably Organic ammonium salts having a variety of uses in greenhouse gas-reducing activities are herein described. The resulting ammonium salt compositions can be used to enhance crop yield.

Methods and systems for converting ammonium waste streams into certifiably Organic ammonium salts having a variety of uses in greenhouse gas-reducing activities are herein described. The resulting ammonium salt compositions can be used to enhance crop yield.

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.

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.

A distillation column including a plurality of alternating plates and spacers stacked in a z-direction is provided. The plates include a respective liquid channeling network on a top surface thereof, a respective vapor opening, and a respective descending ramp. The respective descending ramps abut a respective liquid feed location of the plate immediately below to form a continuous liquid channeling network. The respective vapor openings of adjacent plates are located on opposite sides of the distillation column and form a continuous S-shaped vapor channel defined by the plurality of alternating plates and spacers, and the respective vapor openings. Systems including such distillation columns and processes of distilling a fluid mixture are also provided.

A distillation column including a plurality of alternating plates and spacers stacked in a z-direction is provided. The plates include a respective liquid channeling network on a top surface thereof, a respective vapor opening, and a respective descending ramp. The respective descending ramps abut a respective liquid feed location of the plate immediately below to form a continuous liquid channeling network. The respective vapor openings of adjacent plates are located on opposite sides of the distillation column and form a continuous S-shaped vapor channel defined by the plurality of alternating plates and spacers, and the respective vapor openings. Systems including such distillation columns and processes of distilling a fluid mixture are also provided.