Abstract: In a process for preparing acrylic acid, an acrylic acid-containing product gas mixture obtained by catalytic gas phase partial oxidation of a C3 precursor of acrylic acid, after direct cooling with a quench liquid, is fractionally condensed in a separating column provided with internals, rising into itself with sidestream takeoff of crude acrylic acid, and the acrylic acid oligomers which form are dissociated and the resulting dissociation gas is subjected to a countercurrent rectification before it is recycled.

Abstract: The invention relates to a rotor for a centrifuge intended for the separation of solid particles from a fluid, in particular from the lubricating oil of a Diesel combustion engine, with a rotor housing that is rotatable about a central rotational axis and cylindrical in its basic shape, wherein the rotor housing comprises a fluid inlet, a fluid outlet with one or more propulsion nozzles for driving the rotor by means of the fluid flowing through them, and walls that are provided in and partition the interior region of the rotor.

Abstract: Acrylic acid or methacrylic acid is purified by crystallization to obtain crystals and a mother liquor, by a process in which the crystals are washed with a wash liquid containing the acid and having a temperature from 15 to 40° C. Furthermore, a process for the preparation of acrylic acid or methacrylic acid comprises the abovementioned purification process.

Abstract: A wire section for forming a multi-ply fiber web. The wire section includes a first belt which advances a first fiber ply toward a couch roll defining a combining section. A twin-wire zone of the wire section includes first and second wires between which a second fiber ply is initially formed in a gap former. The second wire separates from the first wire and then the first wire supporting the second fiber ply meets the first belt supporting the first fiber ply at the couch roll of the combining section to form the multi-ply fiber web. The twin-wire part is arranged upstream of the combining section along the running direction of the first belt. The second fiber ply runs on the first wire into the combining section at an angle less than 90° with respect to the belt entering the combining section. The path of the wires from the forming roll to the combining section is disclosed. A suction box or arrangement holds the second fiber ply to the first wire when the first and second wires separate.

Abstract: Acrylic acid or methacrylic acid is purified be crystallization to obtain crystals and a mother liquor, by a process in which the crystals are washed with a was liquid containing the acid and having a temperature from 15 to 40° C. Furthermore, a process for the preparation of acrylic acid or methacrylic acid comprises the abovementioned purification process.

Abstract: The invention relates to a fluid filter, such as an oil filter for a combustion engine. The inventive filter comprises an exchangeable filter inset which is provided with a ring-shaped cross-section that encompasses an inner chamber. The outlet for the purified fluid is joined to the inner chamber. The inventive filter also comprises a discharge line for emptying the filter during a filter change. A central discharge dome is provided which extends into the inner chamber. Said dome, together with the filter inset is mounted in such a way as to be axially displaced between a first closing position which closes the discharge line and a second release position which releases the discharge line. According to the invention, the discharge dome is fixed to the housing and is pushed into the release position thereof when said dome is impinged upon with a spring.

Abstract: A process for the preparation of caprolactam is provided, wherein a) a mixture (I) containing 6-aminocapronitrile and water is reacted in the gas phase, in the presence of a catalyst, to give a mixture (II) containing caprolactam, ammonia, water, high-boiling components and low-boiling components, b) ammonia is then removed from the mixture (II) to give a mixture (III) containing caprolactam, water, high-boiling components and low-boiling components, c) water is then removed from the mixture (III) to give a mixture (IV) containing caprolactam, high-boiling components and low-boiling components, and d) a solid (V) containing caprolactam is then obtained from the mixture (IV) by crystallization, the proportion by weight of caprolactam in the solid (V) being greater than in the mixture (IV).

Abstract: A process for the preparation of caprolactam is provided, wherein a) a mixture (I) containing 6-aminocapronitrile and water is reacted in the liquid phase, in the presence of a catalyst, to give a mixture (II) containing caprolactam, ammonia, water, high-boiling components and low-boiling components, b) ammonia is then removed from the mixture (II) to give a mixture (III) containing caprolactam, water, high-boiling components and low-boiling components, c) water is then removed from the mixture (III) to give a mixture (IV) containing caprolactam, high-boiling components and low-boiling components, and d) a solid (V) containing caprolactam is then obtained from the mixture (IV) by crystallization, the proportion by weight of caprolactam in the solid (V) being greater than in the mixture (IV).

Abstract: The present invention relates to the use of an optical line detector for regulating the position of the wash front and/or of the build-up front of the crystal bed of a wash column in a melt crystallization process and a corresponding regulation method. The line detector, for example a CCD camera or a linear array of reflection probes, is arranged in such a way that optical properties of the crystal bed can be detected continuously in a region running parallel to the longitudinal axis of the wash column, this region covering the desired setpoint position of the wash front or of the build-up front.

Abstract: Crude acrylic acid is purified batchwise by crystallization by a process which comprises at least one purification stage and at least one stripping stage and in which at least the first stripping stage is carried out in a different crystallizer from the first purification stage.

Abstract: A process for the preparation of caprolactam is provided, wherein

Abstract: A process for the preparation of caprolactam is provided, wherein

Abstract: The invention relates to a fluid filter, such as an oil filter for an internal combustion engine, comprising a filter housing which can be closed by a screw lid, a filter element and a central, approximately tubular component which projects into the interior of the filter, whereby the central component has bearing surfaces which are used to fix said component into the filter, so that it cannot rotate. The central component and the filter housing have projections and corresponding undercuts which interact with the projections, in order to fix the central component using a detent or snap-fit connection.

Abstract: A mechanism for rotating an object having a flat bottom surface on a conveyor system is described. Four circular disk segments whose rotational axes lie on a plane and are offset 90 degrees from each other are pressed against the bottom surface by a linear drive and subsequently rotated. The top surface of each disk segment lies against the bottom surface in the direction of a tangent of a circle around the rotational axis of the object. The recessed segments do not touch the bottom surface of the object. As the circular disk segments rotate, their outer circumferences rest against the bottom surface and rotate the object. This rotating mechanism is used in strapping machines and provides a method of rotation.

Abstract: In a process for the purification of a crude acrylic acid melt, the crude acrylic acid melt is converted, under the action of low temperatures, into a crude acrylic acid suspension consisting of acrylic acid crystals and residual melt, and the acrylic acid crystals of the crude acrylic acid suspension are freed from remaining residual melt in a wash column, the production of the acrylic acid crystals of the crude acrylic acid suspension being carried out in the presence of water, the wash column being a wash column with forced transport of the acrylic acid crystals and the wash liquid used being the melt of acrylic acid crystals purified in the wash column.

Abstract: Dicarboxylic acid crystals are prepared from a solution containing at least one organic dicarboxylic acid in a process in which at least one anionic polyelectrolyte having a molecular weight of at least 2000 is added to the solution before or during the crystallization.

Abstract: (Meth)acrylic acid is purified by crystallization by a process in which the (meth)acrylic acid is purified by a combination of at least two different dynamic crystallization processes, in particular a suspension crystallization and a layer crystallization.

Abstract: Phthalides in as-obtained phthalide synthesis reaction mixtures are recovered in pure form by (a) distilling compounds having a boiling point below the boiling point of the phthalide from the reaction mixture, provided such compounds are present in the reaction mixture, to obtain a crude phthalide as bottom product, (b) crystallizing the phthalide from a melt of the crude phthalide.

Abstract: A process for preparing phthalides by I. reducing phthalic acid or phthalic acid derivatives, where the carboxyl groups may be replaced by units which can be derived from the carboxyl groups by a condensation reaction and where one or more of the hydrogens of the o-phenylene unit may be substituted by inert radicals, at a cathode in a undivided electrolytic cell and dissolved in an electrolyte, II. discharging the electrolyte from the electrolytic cell when the reaction has proceeded to the stage where the molar ratio (M), formed by the proportion of phthalide and the sum of the proportions of phthalide and phthalic acid of phthalic acid derivatives in the electrolyte, is from 0.8:1 to 0.995:1, and III. crystallizing the phthalides from the electrolyte and removing them from the mother liquor, if appropriate after distillative work-up of the electrolyte is described.

Abstract: A method and a device for regulated actuation of a proportionally operated solenoid valve are described. The described method and the described device are distinguished by the fact that the actuation of the solenoid valve takes place under consideration for the regulating processes which were necessary prior to such time in order to operate the solenoid valve according to specifications.