摘要:
A method for producing high purity terephthalic acid wherein a slurry having an acetic acid solvent and, dispersed therein, crude terephthalic acid crystals which has been prepared by subjecting a p-alkyl benzene to a liquid phase oxidation in a solvent of acetic acid is continuously converted to a water slurry by the mother liquid exchange, and then the resultant water slurry is subjected to a hydrogenation treatment, which comprises introducing the above acetic acid slurry to a tower having a center axis having a plurality of agitating blades at the top thereof, to form a region having a high concentration of terephthalic acid crystals in the tower through the sedimentation of the terephthalic acid crystals, supplying the water for substitution to the bottom of the tower in such a manner to form an upward water flow while generating a revolving flow of the high concentration region by the rotation of the agitation blade, to thereby subject said terephthalic acid crystals and said upward water flow to a counter-flow contact, and taking out the acetic acid from a portion being upper than the supply port for the acetic acid slurry while withdrawing the terephthalic acid crystals having contacted with the upward water flow together with the water for substitution from the tower bottom. The above method allows the substitution of the acetic acid solvent of the acetic acid slurry with water, with a high substitution percentage.
摘要:
An apparatus for manufacturing a glass base material, which is a base material of an optical fiber, comprising: a base rod, around and along which said glass base material is formed; a burner that hydrolyzes and accumulates a gas material, which is a base material of said glass base material, around and along said base rod; a first burner-moving-unit that moves said burner in a direction parallel with a longitudinal direction of said base rod; and a second burner-moving-unit that moves said first burner-moving-unit in a same moving direction of said first burner-moving-unit.
摘要:
A process for producing a hydrogenation product of aromatic carboxylic acid which comprises continuously producing the hydrogenation product of aromatic carboxylic acid by hydrogenating an aromatic carboxylic acid having a melting point of 250° C. or higher in a solvent in the presence of a solid catalyst, wherein the hydrogenation is conducted in a condition such that substantially the entire amount of the aromatic carboxylic acid of a raw material is dissolved in the solvent by recycling a portion of a reaction liquid taken out of a reactor into the reactor. An aromatic carboxylic acid having a high melting point and hardly soluble in solvents can be hydrogenated at a suitable reaction temperature in accordance with a continuous process without using a great amount of a solvent and the reaction product of the object compound can be produced very efficiently.
摘要:
A process for producing dimethyl 2,6-naphthalene-dicarboxylate by reacting 2,6-naphthalene-dicarboxylic acid with methanol which comprises effecting the reaction at 200.degree. to 350.degree. C. in the presence of trimethyl trimellitate as an essential solvent and optionally, at least one solvent selected from methyl benzoate, methyl toluate and dimethyl o-phthalate preferably by at least two-stage continuous reaction method. The above process is capable of enhancing the rate of esterification reaction and producing purified objective product in high yield for a long period of time in a stable operation without causing any operational trouble such as corrosion and clogging the production equipment.
摘要:
In a method of manufacturing a hollow stabilizer, a pipe compressing step of compressing an electroseamed pipe in a temperature range of a hot state or a warm state so as to make a rate of a thickness with respect to an outer diameter between 18 and 35% is performed, and a forming step of forming the compressed electroseamed pipe in a stabilizer shape in a cold state is executed. Next, a step of applying a heat treatment to a half-finished stabilizer is performed, a shot peening step of impacting a shot on the half-finished stabilizer is performed, and a step of coating the half-finished stabilizer is performed.
摘要:
An apparatus for manufacturing a glass base material, which is a base material of an optical fiber, the glass base material having a core rod as a central axis, comprises a holding unit having a plurality of scroll chucks connected in series along the core rod for holding an end of the core rod; and a burner that hydrolyzes a gas material, which is a base material of the glass base material, into glass particles and accumulates the glass particles around the core rod to form the glass base material.
摘要:
The method of manufacturing porous glass base material for optical fiber includes that flame-hydrolyzing raw materials for glass in oxyhydrogen flame, depositing the generated glass fine particles on a rotating target to form porous glass base material, dehydrating and sintering the porous glass base material to transform into clear glass. The method features, in terms of the surface temperature of said porous glass base material, which changes as the burner used for depositing glass fine particle is moved relatively to said target, the temperature difference between the surface temperature of the porous glass base material touching the burner flame Ta and the surface temperature of the porous glass base material before touching the flame Tb, that is Ta−Tb, is adjusted to be within the range from 200 to 700 degrees centigrade.
摘要:
In the process for producing a high-purity terephthalic acid of the invention, a slurry of crude terephthalic acid crystals dispersed in an acetic acid solvent, which is produced by a liquid-phase oxidation of p-alkylbenzene in the acetic acid solvent, is continuously converted into a slurry in water by a mother liquor displacement and then subjected to a catalytic hydrogenation. The acetic acid solvent slurry is introduced into a column equipped with a central shaft having a plurality of stirring blades along a vertical direction thereof from an upper portion of the column. The crude terephthalic acid crystals are allowed to sediment to form a high-concentration zone of terephthalic acid crystals in the column. A displacing water is fed into the column from a bottom portion thereof so as to form an upward flow of water in the column while forming circular flows in the high-concentration zone by rotation of the stirring blades, thereby bringing the terephthalic acid crystals into counter-current contact with the upward flow of water. The terephthalic acid crystals after counter-current contact with the upward flow of water is discharged from a bottom portion of the column together with the displacing water, while simultaneously taking the acetic acid solvent out of a portion of the column disposed above a feed portion for introducing the acetic acid solvent slurry. By the process, the acetic acid solvent of the acetic acid slurry is displaced by water in a high degree of mother liquor displacement.
摘要:
In the washing process of the invention, the solid particles in a high-concentration zone, which is formed in a washing tank by a gravitational sedimentation of solid particles, are continuously washed by a counter-current contact with upward flow of a washing liquid which is fed from the bottom portion of the washing tank. With this process, the impurities in the solid particles are sufficiently removed by a simple apparatus. Since the used washing liquid can be recycled as the disperse medium for feeding the solid particles and as the washing liquid, the amount of used washing liquid to be discharged as the waste from the system is reduced.