Abstract:
The invention relates to a method of closed-loop control of the temperature in a chemical engineering apparatus (101, 201, 301, 401), in which, in a primary circuit (102, 202, 302, 402), a liquid is conveyed out of the apparatus (101, 201, 301, 401), fed at least partly to a heat transferer (103, 203, 303, 403) and recycled at least partly back to the apparatus (101, 201, 301, 401), where the heat transferer (103, 203, 303, 403) is cooled or heated by a heat transfer medium in a secondary circuit (104, 204, 304, 404), comprising the steps of: providing a target value for the temperature of the liquid in the apparatus (101, 201, 301, 401), detecting an actual value for the temperature of the liquid in the apparatus (101, 201, 301, 401) and calculating the temperature difference between the actual value and the target value of the liquid in the apparatus (101, 201, 301, 401). According to the invention, a heat flow taken from or added to the liquid in the primary circuit (102, 202, 302, 402) by the heat transferer (103, 203, 303, 403) is ascertained, a control signal is calculated on the basis of a defined closed-loop control algorithm, where the closed-loop control algorithm is configured such that the control signal is dependent on the heat flow and the temperature difference between the actual value and the target value of the liquid in the apparatus (101, 201, 301, 401), and the flow rate of the stream of liquid through the heat transferer (103, 203, 303, 403) in the primary circuit (102, 202, 302, 402) and/or a flow rate of the heat transfer medium through the heat transferer in the secondary circuit (104, 204, 304, 404) is/are manipulated on the basis of the control signal.
Abstract:
A plant (1) for recovering acrylic acid, which includes: a absorption column (201); a dissociation column (205); a first line (101) connected to the dissociation column (205); a second line (102) connecting the absorption column (201) and the dissociation column (205); a third line (103) feeding a substream of the mother acid obtained in the crystallization into the dissociation column (205); a fourth line (104) connecting the crystallization apparatus and the absorption column (201); and a fifth line (105) connecting the dissociation column (205) and the absorption column (201).
Abstract:
The present invention relates to the process for recovering acrylic acid, comprising the steps a) division of a heated mother acid stream in direction of an absorption column (201) and a dissociation column (205), b) feeding of a heated mother acid substream as runback to the dissociation column (205), c) feeding-in of at least one stripping gas stream to the dissociation column (205), d) feeding-in of a secondary component stream comprising oligomeric acrylic acid from the condensation column (201) to the dissociation column (205), e) dissociation of part of oligomeric acrylic acid in the dissociation column (205) to give monomeric acrylic acid, f) removal of secondary components comprised in the secondary component stream in the dissociation column (205), g) discharge of monomeric acrylic acid as gas mixture with introduced circulating stripping gas stream from the dissociation column (205) and h) feeding-in of the gas mixture to the condensation column (201).
Abstract:
A process for preparing acrylic acid from ethanol and formaldehyde, in which, in a reaction zone A, the ethanol is partially oxidized to acetic acid in a heterogeneously catalyzed gas phase reaction, the product gas mixture A obtained and a formaldehyde source are used to obtain a reaction gas input mixture B which comprises acetic acid and formaldehyde and has the acetic acid in excess over the formaldehyde, and the formaldehyde present in reaction gas input mixture B is aldol-condensed with acetic acid present in reaction gas input mixture B to acrylic acid under heterogeneous catalysis in a reaction zone B, and unconverted acetic acid still present along-side the acrylic acid target product in the product gas mixture B obtained is removed therefrom, and the acetic acid removed is recycled into the production of reaction gas input mixture B.
Abstract:
Process for hydroformylation of olefins having 6 to 20 carbon atoms in the presence of a cobalt catalyst in the presence of an aqueous phase with thorough mixing in a reactor wherein a hydroformylation products-containing first stream is withdrawn at the top of the reactor and an aqueous phase-containing second stream is withdrawn from the bottom of the reactor via at least one line leading out of the bottom of the reactor, which process comprises controlling one or more mass flow parameters of the second stream in accordance with the density of the second stream.
Abstract:
An aqueous solution comprising acrylic acid and the conjugate base thereof in a total amount of at least 10% by weight, based on the weight of the aqueous solution, and propionic acid and the conjugate base thereof, formic acid and the conjugate base thereof, acetic acid and the conjugate base thereof, benzoic acid and the conjugate base thereof, maleic anhydride, maleic acid and the conjugate bases thereof, phthalic anhydride, phthalic acid and the conjugate bases thereof, acrolein, benzaldehyde, 2-furaldehyde, and at least 20 mol % of at least one alkali metal cation; process for preparing this solution; and the use of this solution for preparation of polymer by free-radical polymerization.