Abstract: The present invention relates to a process for producing diamines and polyamines of the diphenylmethane series (MDA) by reacting aniline and formaldehyde in the presence of an acid catalyst, wherein the aniline contains in total less than 0.5 wt. %, based on the total weight of aniline, of one or more compounds which contain at least one carbonyl group or of one or more compounds that are formed by reaction of these compounds which contain at least one carbonyl group with aniline.

Abstract: Meta-toluene-diisocyanate is produced by reacting meta-toluenediamine with phosgene in the gas phase. The meta-toluenediamine to be vaporized for use in this phosgenation process must contain less than 0.5 wt. % of toluenediamine residue, a total of less than 0.2 wt. % of ammonia and cycloaliphatic amines, and less than 20 ppm of heavy metals. At least 0.1 wt. % of the liquid meta-toluenediamine being to be vaporized must not be vaporized. This non-vaporized content of the meta-toluenediamine must not be fed to the phosgenation reactor.

Abstract: Aromatic isocyanates are produced by reacting one or more aromatic primary amines with phosgene in the gas phase. The phosgene and primary aromatic amine(s) are reacted at a temperature above the boiling temperature of the amine(s) in a reactor having a reaction space which is essentially rotationally symmetric to the direction of flow. The flow fate, averaged over the cross-section, of the reaction mixture along the axis of the essentially rotationally symmetric reaction space in the section of the reaction space in which the conversion of the amine groups into isocyanate groups is between 4 and 80% is not more than 8 m/sec. The flow rate averaged over the cross-section of the reaction mixture along the axis of the essentially rotationally symmetric reaction space in the section of the reaction space in which the conversion of the amine groups into isocyanate groups is 4 to 80% is always below the flow rate averaged over the cross-section at the start of this section.

Abstract: Aromatic diisocyanates are produced by reacting in the gas phase the corresponding primary aromatic diamine with phosgene. The phosgene and the primary aromatic diamine are reacted within a mean residence time of from 0.05 to 15 seconds. The aromatic diamine used contains less than 0.05 mole % overall of aliphatic amine containing no keto groups, per mole of primary amino groups.

Abstract: The invention relates to a process for preparing methylenediphenyl diisocyanates which comprises at least the steps: A) reaction of aniline with formaldehyde in the presence of hydrochloric acid as catalyst to give a mixture of diamines and polyamines of the diphenylmethane series (MDA) and subsequent at least partial neutralization of the hydrochloric acid by means of alkali metal hydroxide, B) reaction of the mixture of diamines and polyamines of the diphenylmethane series obtained in step A) with phosgene to give a mixture of diisocyanates and polyisocyanates of the diphenylmethane series (MDI) and hydrogen chloride, wherein C) the hydrochloric acid which has been neutralized in step A) is separated off in the form of a solution containing alkali metal chloride and is subsequently at least partly fed to an electrochemical oxidation to form chlorine, alkali metal hydroxide and optionally hydrogen and D) at least part of the chlorine produced in step C) is used for preparing the phosgene used in step B).

Abstract: A method is disclosed for operating a switching device using at least one electromagnetic drive, which has a displaceable armature for opening and closing at least one main contact of the switching device. According to at least one embodiment of the invention, a modification of the magnetic flux between a first position, when the main contact is deactivated, and a second position, when the main contact is activated, is identified in the electromagnetic drive and a solenoid current of the electromagnetic drive is restricted to a predetermined minimum current value in the second position, if the magnetic flux modification exceeds a predeterminable value. One advantage of at least one embodiment is that an actuation displacement of the armature can be identified as reliable, if an associated modification of the magnetic flux is also measured. The metrological recording of the magnetic flux is contactless.

Abstract: In order to achieve thermomechanical overload protection with a broad adjustment range for protecting against overload currents, the live components carry an electrical current which is between the value of the overload current and zero. According to at least one embodiment of the invention, switching devices are used which, in a preferred embodiment, switch the current, in parallel, from a first current branch to at least one second current branch, the parallel-connected at least one current branch carrying a partial current, which is between the value of the overload current and zero. In the associated overload protection device, contact devices are provided which are associated with live components on two current branches which can be connected in parallel with one another, wherein at least one current branch can be switched on and off by the switching devices.

Abstract: A method and a device are disclosed for the secure operation of a switching device including at least one main contact which can be switched on and off and which includes contact pieces and a displaceable contact bridge, and at least one control magnet which includes a displaceable anchor. The anchor and the contact bridge are actively connected to each other such that the corresponding main contact can be opened or closed when switched on and off. In at least one embodiment, the method includes the following: a) the path difference, which returns the anchor after switching on and off, is recognised, b) devices which are used to open welded main contacts are released by a release device when the recognised path difference exceeds a predetermined value and a specific time duration of time has run out after switching off.

Abstract: A method and a device for the secure operation of a switching device are disclosed, including at least one main contact which can be switched on and off and which includes contact pieces and a displaceable contact bridge, and also at least one control magnet which includes a displaceable anchor. The anchor acts upon the contact bridge when it is switched on or off such that the corresponding main contact is opened and closed. In at least one embodiment, the method includes: a) the displaceable contact bridge of the at least one main contact recognizes when an opening point has been exceeded after being switched off, and b) the additional operation of the switching device is interrupted, according to a predetermined duration of time, when the opening point is not exceeded.

Abstract: A method and a device for secure operation of a switching device including at least two main contacts which can be switched on and off and include contact pieces and a displaceable contact bridge, and a control magnet having a displaceable anchor. The method may include producing an electric control signal to release a contact breaking device when the control magnets are switched on and off. The emitted control signal lies outside the ON state of the switching contact during the regular operation of the switching device and releasing the contact breaking device in defective operation of the switching device if the switching contact remains in the ON state when the control magnets are switched on or off. The switching contact may connect through the control signal to release the contact breaking device.

Abstract: A method and a device are disclosed for the secure operation of a switching device including at least two main contacts which can be switched on and off and which includes respectively, contact pieces and a displaceable contact bridge, and at least one control magnet which includes a displaceable anchor. The anchor acts upon the contact bridge when it is switched on and off such that the corresponding main contact is opened or closed. At least one embodiment of the inventive method includes the following steps: a) release device for a force element remains in a first state in order to interrupt the main contact as long as the main contacts are closed when switched on and open when switched off, and b) the release device are transferred into a second state if at least the main contact is welded after switching off.

Abstract: A method is disclosed for operating a switching device using at least one electromagnetic drive, which has a displaceable armature for opening and closing at least one main contact of the switching device. According to at least one embodiment of the invention, a modification of the magnetic flux between a first position, when the main contact is deactivated, and a second position, when the main contact is activated, is identified in the electromagnetic drive and a solenoid current of the electromagnetic drive is restricted to a predetermined minimum current value in the second position, if the magnetic flux modification exceeds a predeterminable value. One advantage of at least one embodiment is that an actuation displacement of the armature can be identified as reliable, if an associated modification of the magnetic flux is also measured. The metrological recording of the magnetic flux is contactless.

Abstract: Meta-toluene-diisocyanate is produced by reacting meta-toluenediamine with phosgene in the gas phase. The meta-toluenediamine to be vaporized for use in this phosgenation process must contain less than 0.5 wt. % of toluenediamine residue, a total of less than 0.2 wt. % of ammonia and cycloaliphatic amines, and less than 20 ppm of heavy metals. At least 0.1 wt. % of the liquid meta-toluenediamine being to be vaporized must not be vaporized. This non-vaporized content of the meta-toluenediamine must not be fed to the phosgenation reactor.

Abstract: Primary isocyanates are produced by reacting the corresponding primary amine(s) with phosgene at a temperature above the boiling temperature of the amine(s) in a tube reactor with a reaction space. In this tube reactor, at least one educt stream P containing phosgene and at least one educt stream A containing the amine(s) are fed to the reaction space via a nozzle arrangement. The nozzle arrangement includes a number of n?1 nozzles aligned parallel to the axis of rotation of the tube reactor and a free space surrounding the nozzles. One of the educt streams A or P is fed to the reaction space via the nozzles and the other educt stream is fed to the reaction space via the free space surrounding the nozzles. The reaction space contains at least one moving mixing device.

Abstract: Aromatic isocyanates are produced by reacting one or more aromatic primary amines with phosgene in the gas phase. The phosgene and primary aromatic amine(s) are reacted at a temperature above the boiling temperature of the amine(s) in a reactor having a reaction space which is essentially rotationally symmetric to the direction of flow. The flow fate, averaged over the cross-section, of the reaction mixture along the axis of the essentially rotationally symmetric reaction space in the section of the reaction space in which the conversion of the amine groups into isocyanate groups is between 4 and 80 % is not more than 8 m/sec. The flow rate averaged over the cross-section of the reaction mixture along the axis of the essentially rotationally symmetric reaction space in the section of the reaction space in which the conversion of the amine groups into isocyanate groups is 4 to 80 % is always below the flow rate averaged over the cross-section at the start of this section.

Abstract: A method and device are disclosed for safely operating a switching device with at least one main contact, which can be switched on or off, and which has contact elements and a moving contact bridge, and with at least one control magnet, which has a moving armature. During switching on and off, the armature acts upon the contact bridge whereby closing and opening the corresponding main contact. At least one embodiment of the method includes the following: a) identifying whether the moving contact bridge of the at least one main contact has surpassed an opening point after the switching off; and b) interrupting the further operation of the switching device when the opening point has not been surpassed after a predetermined period of time.

Abstract: Isocyanates are produced by reaction of primary amines with phosgene in the gas phase. In this process, the reaction is terminated by guiding the reaction mixture from the reaction chamber through a cooling stretch into which liquids are injected. Direct cooling takes place in the cooling stretch in one stage in two or more cooling zones connected in series.

Abstract: The invention relates to a process for preparing methylenediphenyl diisocyanates which comprises at least the steps: A) reaction of aniline with formaldehyde in the presence of hydrochloric acid as catalyst to give a mixture of diamines and polyamines of the diphenylmethane series (MDA) and subsequent at least partial neutralization of the hydrochloric acid by means of alkali metal hydroxide, B) reaction of the mixture of diamines and polyamines of the diphenylmethane series obtained in step A) with phosgene to give a mixture of diisocyanates and polyisocyanates of the diphenylmethane series (MDI) and hydrogen chloride, wherein C) the hydrochloric acid which has been neutralized in step A) is separated off in the form of a solution containing alkali metal chloride and is subsequently at least partly fed to an electrochemical oxidation to form chlorine, alkali metal hydroxide and optionally hydrogen and D) at least part of the chlorine produced in step C) is used for preparing the phosgene used in step B).

Abstract: The present invention relates to a process for producing diamines and polyamines of the diphenylmethane series (MDA) by reacting aniline and formaldehyde in the presence of an acid catalyst, wherein the aniline contains in total less than 0.5 wt. %, based on the total weight of aniline, of one or more compounds which contain at least one carbonyl group or of one or more compounds that are formed by reaction of these compounds which contain at least one carbonyl group with aniline.

Abstract: Isocyanates are produced by reacting an organic amine with phosgene in process which includes at least three stages. The first stage is carried out in a dynamic mixer. The second stage is carried out in at least one reactor. The third stage is carried out in at least one material separating apparatus. The pressure in the reactor of the second stage must be greater than or equal to the pressure in the dynamic mixer. The pressure in the third stage material separating apparatus must be lower than the pressure in the second stage reactor.