The present invention relates to a method for the purification of natural vanillin, comprising a step involving the stripping of a liquid flow F2 containing natural vanillin. The invention also relates to the natural vanillin that can be obtained using the method of the invention, as well as a device for purifying natural vanillin.

Systems and methods of producing potassium sulfate can involve converting a mixed salts feed stream into a conversion end slurry in a conversion unit, the mixed salts feed comprising at least one potassium-containing salt, at least one chloride-containing salt, at least one magnesium-containing salt and at least one sulfate-containing salt and the conversion end slurry comprising schoenite; separating conversion end slurry into a conversion end solids stream and a conversion brine; leaching the conversion end solids stream in a crystallization unit to produce a potassium sulfate product stream comprising potassium sulfate and a crystallizer mother liquor comprising magnesium sulfate and potassium sulfate; collecting heat generated in the conversion unit by a heat pump; and providing at least a portion of the heat collected to the crystallization unit to regulate a temperature of the potassium sulfate product stream and the crystallizer mother liquor stream contained in the crystallization unit.

A Reflux Rinsing apparatus for purifying crystals using solvent vapor through dynamic equilibrium recrystallization. A pressure vessel contains a liquefied gas solvent, impure crystalline starting material initially, and a purified crystalline mass at the conclusion of the purifying process. A mechanism is provided for providing pressure to contents of the pressure vessel and for heating the lower portion thereof. A timer is also connected to the mechanism, the timer being set to heat the pressure vessel to drive vapors and reflux rinsing to remove impurities at the surface of an impure crystalline mass, to reclaim the solvent, leaving purified crystals and impurities in the pressure vessel, and to open the pressure vessel to remove the purified crystals from the vessel walls and bottom surface and to remove the impurities from the vessel. The angle of a crystal bed in the apparatus can be adjusted.

Provided is a hybrid process for producing high-purity para-xylene from a feedstock of aromatic hydrocarbon isomer fractions having 8 carbon atoms, in a liquid phase. The process includes a liquid chromatography separation step and a crystallization step of the para-xylene from the purified stream of para-xylene obtained at the separation step.

A method for retrofitting a system for recovering paraxylene. The system is retrofitted with a pressure swing adsorption unit and a second isomerization reactor. The retrofit lowers the variable cost of the plant, while providing the opportunity to maintain existing equipment and furnace and refrigeration duty.

The disclosure provides a decolorization and purification method of BHET material, which includes the following steps. A first dose of activated carbon is added to preliminarily treat the BHET material. After the preliminary treatment, a first cooling crystallization process and filtration are performed to obtain BHET crystals. Afterwards, an oxidant is used to chemically react with the BHET crystals to destroy a dye or impurities, and then a second dose of activated carbon is added to adsorb a chemically reacted oxide. Next, a second cooling crystallization process, filtration, and drying are performed to obtain a finished product of BHET.

The present invention is a process, a method, and system for recovery and concentration of dissolved ammonium bicarbonate from a wastewater containing ammonia (NH3) using gas separation, condensation, and crystallization, each at controlled operating temperatures. The present invention includes 1) removal of ammonia from waste (sludges, semi-solids, and solids and liquids) without the use of chemicals at a temperature of at least 80 degrees Celsius, 2) condensing the gaseous containing ammonia, carbon dioxide and water vapor to remove water vapor concentrating the amount of gaseous ammonia and carbon dioxide, 3) concentrating the ammonia and carbon dioxide in the water by established means, such as concentrating the gas using partial condensation followed by passing the concentrated gas through an absorption column at a temperature of between about 20 and 50 degrees Celsius to form dissolved ammonium carbonate and ammonium bicarbonate, or total condensation followed by dewatering using reverse osmosis, and 4) crystallizing concentrated dissolved ammonium carbonate and ammonium bicarbonate at a temperature of less than about 35 degrees Celsius to form solid ammonium bicarbonate and ammonium carbonate.

Disclosed herein are processes for producing highly concentrated bleach slurries containing a mixture of crystals of solid sodium hypochlorite pentahydrate in a liquid phase saturated in sodium hypochlorite and containing sodium hydroxide or other alkaline stabilizers. Bleach slurries and compositions exhibiting enhanced stability are also disclosed.

Provided is a technique for continuously performing poor solvent crystallization or reactive crystallization. A porous membrane in which multiple pores through which a liquid passes are formed internally partitions the treatment container into a first flow space and a second flow space. A raw material liquid supply unit continuously supplies a raw material liquid to the first flow space. A treatment liquid supply unit continuously supplies a treatment liquid to the second flow space at a pressure at which the treatment liquid passes through the porous membrane and enters the first flow space. An extraction unit continuously extracts a mixed liquid of the raw material liquid and the treatment liquid from the first flow space. An aging unit precipitates and grows crystals of a target substance from a mixed liquid.

A urea production plant including a synthesis and recovery section has a first evaporation section connected with the synthesis and recovery section and a first condensation section. A granulation section is connected to the first evaporation section. A scrubbing section is connected to the granulation section. A second evaporation section is connected to the scrubbing section. The second evaporation section is connected to the granulation section. A second condensation section is connected to the second evaporation section. A quenching section includes a liquid inlet for the distribution of a quenching liquid is located and connected between the granulation section and the scrubbing section and the quenching section is connected to a quenching liquid providing section and the second condensation section.