Abstract:
The invention relates to a chimney tray (3) for a column (1) for thermally treating fluid mixtures, comprising a collecting tray (4) and at least two chimneys (5-1, 5-2) which are horizontally spaced in the collecting tray (4). Each chimney (5-1, 5-2) has a vertically aligned chimney body (6-1, 6-2), which forms a passage opening (7-1, 7-2) through the collecting tray (4), and a cover device (8-1, 8-2) arranged at a distance from the chimney body (6-1, 6-2), said cover device (8-1, 8-2) covering the respective passage opening (7-1, 7-2) in the vertical direction. The chimney tray (3) according to the invention is characterized by a shield (9) which extends around the chimney body (6-1) of a first chimney (5-1). The lower annular edge (14) of the shield (9) lies below the upper edge (13) of the chimney body (6-1) of the first chimney (5-1), and the upper annular edge (11) of the shield (9) lies above the lower outer edge (12) of the cover device (8-1) of the first chimney (5-1) or adjoins the lower outer edge (12) of the cover device (8-1) of the first chimney (5-1).
Abstract:
The present invention describes a system (1) for recovering liquid or flowable chemicals in a chemical plant (3) which comprises - at least two plant parts (3a, 3b) of the plant (3), - for each plant part (3a, 3b) at least one connection device (5a, 5b) which in each case is arranged at the lowest point of the respective plant part (3a, 3b), - at least one common collecting line (7) which runs beneath the connection devices (5a, 5b) and connects these with one another, - at least one collection container (9) which is arranged at the same height as or higher than the at least two plant parts (3a, 3b) and above the collection line (7), - at least one pump (11) which is provided in the collection line (7), between the connection devices (5a, 5b) and the collection container (9), for drawing off the at least one liquid or flowable chemical which has collected in the collection line (7) and introducing it into the collection container (9). The present invention further relates to a method for recovering liquid or flowable chemicals in a chemical plant (3) by means of the system (1) according to the invention, and to the use of the system (1).
Abstract:
An α,β-unsaturated aldehyde and/or an α,β-unsaturated carboxylic acid are prepared by gas phase oxidation of an alkene with molecular oxygen over a fixed catalyst bed comprising a bed of hollow cylindrical shaped catalyst bodies having a multimetal oxide active composition. The fixed catalyst bed comprises at least three successive reaction zones; the highest local temperature in the fixed catalyst bed does not occur in the reaction zone closest to the reactor outlet; the highest local temperature in the fixed catalyst bed does not occur in the reaction zone closest to the reactor inlet; and the value WT = (ED-ID)/2 in the reaction zone in which the highest local temperature in the fixed catalyst bed occurs is lower than in the other reaction zones, in which ED is the external diameter and ID is the internal diameter of the shaped catalyst body. The yield of the products of value is enhanced in this way.
Abstract:
In a method for removing low, medium and high-boiling by-products obtained when producing acrylic acids or methacrylic acids, the gaseous low-boiling by-products are burned, whereby low and medium-boiling by-products hat have been dissolved in water, if desired together with high-boiling by-products that have been treated with the dissolvent, are taken to the burning stage.
Abstract:
The invention relates to a method for separating acrylic acid, contained as the main constituent and glyoxal, contained as a by-product from a gaseous product mixture of a partial gas phase oxidation of a C 3 precursor compound of acrylic acid. According to said method, a liquid phase P is created, 70 % of the total weight of which consists of acrylic acid and which contains at least 200 mol ppm of glyoxal in relation to the contained molar quantity of acrylic acid. The glyoxal is separated from the acrylic acid by crystallisation from the liquid phase P.
Abstract:
The invention relates to a method for the heterogeneously-catalysed gas phase partial oxidation of an organic compound on a catalyst fixed bed in a multiple-contact fixed bed reactor, whereby the reduction in quality of the catalyst coating with increasing service duration is compensated by a partial catalyst exchange.