Abstract: A method for operating a sheet-forming unit of a papermaking machine. At least one fibrous material suspension is fed to a headbox and is conducted in a plurality of turbulence-generating channels to form sub-flows, and fed to a nozzle. From the nozzle, the at least one fibrous material suspension is in the form of a free jet into the forming unit to define an impingement line. In a final fluidization region of an individual turbulence-generating channel a pressure loss (?p) of ?50 mbar is generated within the fibrous material suspension before inlet thereof into the nozzle, and the fibrous material suspension is guided from the final fluidization region as far as the impingement line in such a way that the dwell time of the suspension in the region defined by the final fluidization region as far as the impingement line ranges from >30 ms to ?300 ms.

Abstract: The invention relates to a method for optimizing the energy balance of a forming section in a machine for producing fibrous webs, in which a fiber suspension, which is fed to the forming section by way of a material ramp after the immobility point is reached, is passed through at least two dewatering units within a compression zone and to a subsequent functional unit. The invention is characterized in that a setpoint value for a target dryness to be set is predefined based on the existing dewatering elements as a function of a theoretical maximum achievable dryness under plant conditions in the area of the transition zone, said setpoint being selected such that it is less than the theoretical maximum achievable dryness but is equal to or greater than a required minimum dryness in the area of the transition zone, and that the target dryness is controlled by lowering the inlet dryness at one of the last dewatering units disposed in the direction of passage of the fiber suspension within the compression zone.

Abstract: A forming section in a machine for producing a web of fibrous material includes a control and/or regulating system including a control and/or regulating device which is connected with at least one device for at least indirect acquisition of one value at least indirectly characterizing the dry content of the fibrous web in a transfer area from the forming section to a following function unit, with a device for input of a desired value for the target dry content, and with at least the control elements of an individual dewatering unit located prior to one of the last dewatering units, or the last dewatering unit inside the compression zone. The control and/or regulating device also includes a device for creating the control variables for controlling the individual dewatering units.

Abstract: A method for operating a sheet-forming unit of a papermaking machine. At least one fibrous material suspension is fed to a headbox and is conducted in a plurality of turbulence-generating channels to form sub-flows, and fed to a nozzle. From the nozzle, the at least one fibrous material suspension is in the form of a free jet into the forming unit to define an impingement line. In a final fluidization region of an individual turbulence-generating channel a pressure loss (?p) of ?50 mbar is generated within the fibrous material suspension before inlet thereof into the nozzle, and the fibrous material suspension is guided from the final fluidization region as far as the impingement line in such a way that the dwell time of the suspension in the region defined by the final fluidization region as far as the impingement line ranges from >30 ms to ?300 ms.

Abstract: A forming section in a machine for producing a web of fibrous material includes a control and/or regulating system including a control and/or regulating device which is connected with at least one device for at least indirect acquisition of one value at least indirectly characterizing the dry content of the fibrous web in a transfer area from the forming section to a following function unit, with a device for input of a desired value for the target dry content, and with at least the control elements of an individual dewatering unit located prior to one of the last dewatering units, or the last dewatering unit inside the compression zone. The control and/or regulating device also includes a device for creating the control variables for controlling the individual dewatering units.

Abstract: The invention relates to a method for optimizing the energy balance of a forming section in a machine for producing fibrous webs, in which a fiber suspension, which is fed to the forming section by way of a material ramp after the immobility point is reached, is passed through at least two dewatering units within a compression zone and to a subsequent functional unit. The invention is characterized in that a setpoint value for a target dryness to be set is predefined based on the existing dewatering elements as a function of a theoretical maximum achievable dryness under plant conditions in the area of the transition zone, said setpoint being selected such that it is less than the theoretical maximum achievable dryness but is equal to or greater than a required minimum dryness in the area of the transition zone, and that the target dryness is controlled by lowering the inlet dryness at one of the last dewatering units disposed in the direction of passage of the fiber suspension within the compression zone.

Abstract: A reactor for testing catalyst systems which has a plurality of catalyst tubes (2) which are arranged parallel to one another in the interior space of the reactor and whose ends are welded into tube plates and also has caps (3) at each end of the reactor which each bound a cap space (4), with a fluid reaction medium (5) being fed via one cap space (4) into the catalyst tubes (2), flowing through the catalyst tubes (2) and being discharged via the other cap space (4), and is also provided with a heat exchange medium circuit in which the heat exchange medium (6) is fed in at one end of the reactor, flows through the intermediate space between the catalyst tubes (2) and flows out at the other end of the reactor, wherein the catalyst tubes (2) are arranged in two or more catalyst tube regions (7) which are thermally separate from one another, is proposed.

Abstract: 2-Methyl-1,4-butanediol and 3-methyltetrahydrofuran are prepared by reacting a compound of the general formula I or II ##STR1## where R.sup.1 and R.sup.2 are each hydrogen or C.sub.1 -C.sub.8 -alkyl and the formyl group of II may also be present as acetal with a C.sub.1 -C.sub.8 -alkanol, is reacted with hydrogen in the presence of copper or of a metal of groups 7 to 10 of the Periodical Table of elements or of a compound of these metals.

Abstract: Preparation of vinyl carboxylates by the reaction of a carboxylic acid with acetylene in the presence of a platinum metal complex catalyst, which contains as ligands carbon monoxide or a nitrile (I), a tertiary nitrogen base (II), a tertiary phosphorus compound (III) having C-organic and/or O-organic radicals or mixtures of said compounds.The end products serve as monomers or comonomers for polymer dispersions.

Abstract: A process for the preparation of phthalides of the formula I ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently of one another, are hydrogen, C.sub.1 - to C.sub.4 -alkyl or C.sub.1 - to C.sub.4 -alkoxy, by reacting phthalic anhydrides of the formula II ##STR2## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are as defined as above, on hydrogenation catalysts at from 50.degree. to 400.degree. C. and at from 1 to 400 bar, wherein the hydrogenation catalysts employed are essentially free from Lewis acids.

Abstract: A process for the preparation of 4-hydroxymethyltetrahydropyrans of the formula I ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen, C.sub.1 - to C.sub.12 -alkyl, C.sub.3 - to C.sub.8 -cycloalkyl, aryl or C.sub.7 - to C.sub.20 -aralkyl, comprises reacting a tetrahydropyrancarboxylic ester of the formula II ##STR2## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are as defined above, and R.sup.5 is hydrogen or C.sub.1 - to C.sub.12 -alkyl, at from 50.degree. to 400.degree. C. and at from 1 to 400 bar in the presence of hydrogen and a hydrogenation catalyst.