Provided is an acetic acid production method that enables smooth reduction and/or increase of acetic acid production with easy operation and can industrially efficiently, stably produce acetic acid with maintained quality even when the acetic acid production volume is changed. The acetic acid production method includes a carbonylation step in which methanol is reacted with carbon monoxide in a continuous system in the presence of a catalytic system, acetic acid, methyl acetate, and water, where the catalytic system includes a metal catalyst and methyl iodide. The carbonylation step employs two or more reactors disposed in parallel.

The invention relates to a method for recovering energy and water from pressure oxidation flash steam where first flash steam directly obtained from a flash vessel is contacted with a first recirculating condensate having a first low condensate temperature to condense at least part of the water vapor in the first dirty flash steam and simultaneously to heat the first recirculating condensate to obtain a first recirculating condensate having a first high condensate temperature and a first vent steam. The invention further relates to a pressure oxidation arrangement adapted for use in the method.

The invention relates to an hydrolysis vessel (200) used during amidification step of acetone cyanohydrin (ACH), in the industrial process for production of a methyl methacrylate (MMA) or methacrylic acid (MAA). The hydrolysis vessel (200) is used for hydrolyzing acetone cyanohydrine with sulfuric acid to produce a mixture comprising -sulfatoisobutyramide (SIBAM). It comprises at least one cooling system (212; 244) on its internal annular periphery area and it is divided into at least two stages, preferably three, along its vertical wall, each stage (S1 to S3) comprising a ACH feeding inlet (201, 202, 203). Such vessel allows controlling both homogeneity and temperature of the mixture, and thus obtaining a high yield for the hydrolyzing reaction in very safe conditions.

Provided is an apparatus for preparing polybutadiene which may improve productivity by minimizing a plugging phenomenon during the preparation of polybutadiene and increasing a conversion rate.

A heat generating system comprises two or more thermal reactors. During operation, a first thermal reactor is pressurized while a second thermal reactor is depressurized to vent unused gas and byproduct. The unused gas and byproduct from the second reactor are separated in a gas separator and the unused gas is supplied to the first reactor while the first reactor is pressurized. An exothermic reaction is triggered in the first reactor, which results in generation of heat and byproduct cluster formation. When the exothermic reaction is complete, the process is reversed and the second thermal reactor is pressurized while the first reactor is depressurized.

A process for washing a particulate substance comprising: (i) combining a particulate substance and a first washing medium in a first vessel to form a slurry and washing the particulate substance with said washing medium; (ii) transferring the slurry to a hydrocyclone; (iii) removing a first by-product stream depleted in particulate substance and a first product stream enriched in particulate substance from the hydrocyclone; (iv) transferring the first product stream to a second vessel and in the presence of a second washing medium forming a slurry and washing the particulate substance with said second washing medium e.g. by agitation thereof; (v) transferring the slurry to a hydrocyclone; (vi) removing a second by-product stream depleted in particulate substance and a second product stream enriched in particulate substance from the hydrocyclone.

The present application provides a continuous preparation system and method for vinylidene chloride. In the present application, by coupling two stages of high gravity reactors, the product vinylidene chloride and water vapor are distilled from a reaction system in form of an azeotrope by adopting a water vapor steam stripping method, and the product obtained using the method has high purity. In addition, by combining steam stripping and high gravity, trichloroethane and alkali solution are rapidly mixed for mass transfer, and the product vinylidene chloride is rapidly distilled from the reaction system in form of the azeotrope (based on rapid diffusion of water vapor), such that the reaction proceeds continuously towards the direction of producing vinylidene chloride, thus significantly improving the conversion rate. As proved by a test apparatus, the present application can stabilize the purity of the vinylidene chloride product at 98% or more (mass fraction), decrease the TOC value of chloride salt wastewater to 100 mg/L or less, and decrease the consumption of materials and the cost of subsequent salt-containing wastewater treatment.

This invention relates to a continuous homogeneous solution phase polymerization process comprising contacting, in an evaporative reactor system at a temperature of 50 C. or more and a pressure of 100 kPa or more, a catalyst system, optionally, a hydrocarbon diluent, optionally, scavenger, and one or more monomer(s) to form a homogeneous polymerization medium, where the polymer product is dissolved in the reaction medium at 10 wt % or more (based upon the weight of the polymer present in the effluent at the exit of the reactor) and the catalyst system is dissolved in the reaction medium, and where the catalyst system comprises an activator and a coordination catalyst precursor compound and where all or part of the polymerization medium is evaporated during the polymerization.

Provided is an apparatus for preparing polybutadiene which may improve productivity by minimizing a plugging phenomenon occurred during the preparation of polybutadiene and increasing a conversion rate. The apparatus for preparing polybutadiene includes two first polymerization reactors arranged in parallel to reduce the plugging phenomenon in which butadiene (reaction raw material), a polymerization catalyst, and a solvent are respectively supplied and polymerized, at least one second polymerization reactor arranged in series with the first polymerization reactors in which a first polymerization solution containing a butadiene polymer discharged from the first polymerization reactors is supplied and a butadiene polymerization reaction is performed, and one or more condensers which condense gases discharged from the first polymerization reactors and the second polymerization reactor and supply a condensate to the first polymerization reactors and/or the second polymerization reactor.

The present invention provides a non-hazardous, improved continuous oxidation process for the preparation of substituted benzoic acid of formula (I) by using continuous process reactor system with improved process controls. (I) wherein: R.sub.1 is H, F, Cl, Br, I, NO.sub.2, amine, or C.sub.1-C.sub.5 alkyl; R.sub.2 is H, F, Cl, Br, I, NO.sub.2, amine, or C.sub.1-C.sub.5 alkyl; and R.sub.3 is H, F, Cl, Br, I, NO.sub.2, amine, C.sub.1-C.sub.5 alkyl;

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