DD281803A5 - METHOD AND DEVICE FOR THE OXYDATION OF HYDROCARBONS - Google Patents

Abstract

The invention relates to methods and apparatus for the oxidation of hydrocarbons. The process according to the invention for the oxidation of hydrocarbons by means of oxygen-containing gases, in which the oxidizing gas is introduced into the reactor in the form of the bubble stream formed into flattened beams transverse to the direction of flow of the reaction liquid, is characterized in that the adjacent jets are separated from each other by non-gassed zones become. The apparatus for the oxidation of hydrocarbons consisting of a horizontal drum divided into a series of sections, the sections being provided with tube distributors for the oxidizing gas, which in turn are composed of a series of the pre-drilled arms perpendicular to the direction of flow of the reaction fluid, has distributor arms, which are arranged at a distance from each other, which prevents the connection of the gas bubbles of the adjacent arms together and more than 400 mm. Between the individual arms, the device may have the submerged under the liquid level and a free passage over the bottom of the reactor ermoeglichenden partition walls. By the method according to the invention, a selectivity improvement was achieved {oxidation process; hydrocarbons; Rays, adjacent; separated from each other; Zones, unfranked; Device; Selektivitaetsverbesserung}

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a method and a device for the oxidation of hydrocarbons in the liquid phase by means of oxygen-containing gases. The invention is used above all in the multistage oxidation of cyclohexane and for the oxidation of other hydrocarbons.

Characteristic of the known state of the art

The oxidation of hydrocarbons in the liquid phase is a widely used method in the chemical industry. Such processes may include but are not limited to: the oxidation of cyclohexane to cyclohexanol and cyclohexanone, isopropylbenzene to cumene hydroperoxide, toluene to benzoic acid, p-xylene to terephthalic acid are counted. From the point of view of achieving high selectivities, the greatest difficulty is encountered in the oxidation of cyclohexane, in which the desired products, cyclohexanol and cyclohexanone, are more readily oxidized than cyclohexane and undergo by-products, especially mono- and dicarboxylic acids.

In addition to the limitation of the degree of conversion, there is a known method for improving the selectivity of the oxidation processes of the hydrocarbons in the leadership of these processes in several series reaction stages, w.odurch so-called. Back mixing is avoided. An essential factor in the processes of the oxidation of hydrocarbons is the way in which the oxidizing gas is introduced into the reaction liquid. This type is intended to ensure the proper handling of the interphase area and corresponding liquid phase turbulence which will prevent the formation of local differences in concentrations and / or temperatures.

For this purpose, the oxidizing gas is introduced into the reaction liquid in the lowest layer. It is introduced in the form of bubbles, which are obtained for example by means of sieve trays, porous distributors of ceramic or metallic sinters or distributors of appropriately predrilled pipes. In the manifolds, which are constructed for example in the form of a horizontal frame, the tubes are arranged and pre-drilled so that - similar to the use of the sieve plates or the porous manifold - a uniform outflow of Oxydationsgases throughout the plan of the manifold and uniform flow through the Mass of the reaction liquid is achieved. Above the plan of the distributor, therefore, there is an ascending movement of the whole mass of liquid, a falling movement of this liquid is possible only outside the plan of the distributor, on the walls of the reactor. Such a condition neglects mixing in the individual sections of the reactor because the upwardly ascended liquid must travel a long distance before entering the falling zone (adjacent the walls of the reactor or adjacent the transverse walls which make up the reactor divide). Such introduction of the oxidizing gas can cause a complete consumption of the dissolved oxygen and lead to the formation of a substantial volume of the given section, in which lack of dissolved oxygen and lack of further dissolution in the upper zones of the liquid column, with the oxidizing gas with largely exhausted oxygen in Come in contact, the reaction no longer takes place. Since the load of the respective section of the reactor by the

Oxidation gas is constant, causes the non-utilization (in the sense of the reaction) of a volume part of the section the Overloading of another part with the Oxydationssubstrat and the emergence in the latter of the favorable Conditions for too deep oxidation, i. for the oxidation of the desired products to by-products. In the Larger diameter reactors are located outside the liquid drop zones adjacent to the sidewalls of the Reactor additional fall zones e.g. in the axle of a recumbent. The drum of the existing reactor,

or also falling zones are formed parallel to this axis.

Known means for the oxidation of hydrocarbons consist of either a few separate reactors of Container types, sequence bound with a piping system, or represent a reactor, some to the order

contains assembled reaction sections.

For example, a reaction apparatus according to Polish Patent No. 64449 consists of a recumbent drum, which consists of several Sections are divided by pairs of adjacent vertical partitions, one of which is a Overflow partition for the reaction liquid and the other represents the steam chambers of the adjacent sections

shuts off.

In these sections are pre-drilled manifolds, which are constructed for example in the form of a frame through

which is introduced into the reaction liquid, the oxidation gas.

An improvement of this solution consists of a reactor according to the Polish Patent No. 136028. It forms a Further development of the frame construction of manifolds, which are composed of a series of arms, whose Curvature is similar to the curvature of the bottom of the reactor, the pipe elements parallel to the axis

are connected. The improvement consists in such pre-drilling of the arms of the distributors that in their higher lying extreme

Divide the holes are distributed with greater distances to each other, as in the lower-lying central part. To this In this way, a uniform outflow of the oxidizing gas is achieved along the distributor arm, at the same time the

excessive gas flow strength at the ends of the arms and the associated incomplete absorption of oxygen avoided

In this solution, the possibility is provided, portions of the distributor arms, for example, in the longitudinal axis of the Leave reactor unvorgebohrt to elongated liquid fall zones not only on the walls of the Reactor or the reactor section but also on this non-predrilled section to form. The well-known Solutions in both the technology and the equipment use the possibility of achieving another Improvement of the selectivity of the oxidation of the hydrocarbons, as well as the degree of oxygen utilization, i. the Reduction of its concentration in the exhaust gases is not enough. Object of the invention

By the method according to the invention, a selectivity increase in the oxidation of the cyclohexane of 2.5% is achieved, losses of raw materials have been lowered and the degree of utilization of the oxygen is increased.

Explanation of the essence of the invention

The present invention has for its object to provide an improved method and apparatus for the oxidation of hydrocarbons available.

According to the invention, the process consists of oxidizing the hydrocarbons in the liquid phase by oxygen-containing gases by gassing the crude liquid in a bubble reactor with the oxidizing gas in the form of a series of flattened jets to the flow direction of the liquid through the reactor or a section transverse to its section shaped bubbles in that the adjacent beams are separated by non-fumigated zones.

In the method according to the invention, the reaction liquid displacing from the inlet of the given reaction section to its outlet is made to ascend by the oxidation gas bubble jets running transversely to its direction of movement. The liquid then falls down in the non-filled transverse zones between the bubble jets. Below, she comes back in contact with the gas bubbles and is brought back to the ascent. In this way it is possible to repeat the rising and falling of the liquid from the inlet to the outlet of the reaction section. It is achieved an intensive multi-stage circulation of the reaction liquid around the perpendicular to the direction of flow of the liquid levels. In the fall zones, where no fresh oxidizing gas is supplied, the reaction consumption of the already dissolved in the cyclohexane oxygen takes place. The reaction proceeds at lower oxygen concentration, favoring the achievement of increased selectivity. The circulation of the reaction liquid around the planes perpendicular to the liquid flow direction can be used alone or simultaneously with the known circulation around the planes parallel to this direction.

The liquid phase hydrocarbon oxidation apparatus according to the invention, consisting of a cylindrical drum divided into a series of sections provided with tube distributors for the oxidizing gas, which in turn are composed of a series of arms predrilled perpendicularly to the liquid flow direction are, the distributor arms, d'e arranged with a distance to each other, which prevents the gas bubbles from the adjacent arms connect with each other, which is greater than 400mm. To improve the circulation, parallel circulation partitions immersed under the liquid level and freeing passage above the bottom of the reactor can be used between the individual arms

to let. Such partitions can be arranged in pairs between the adjacent arms; they will then form excreted liquid riser zones (over the arms) and liquid trap zones (between the partitions). They can also be arranged individually between the adjacent arms; then they will not separate the ascension space and the dead space from each other; On the other hand, they separate the circulation spaces belonging to the individual distributor arms.

Ausföhrungsbelspiel

The method according to the invention and the device according to the invention are explained in more detail below with reference to an exemplary embodiment shown in the drawing, in which the individual figures show:

Fig. 1: view of a horizontal longitudinal section of a section of the reactor; Fig. 2: view of the vertical cross section of this section.

example

An oxidation process of the cyclohexane with air was continuously conducted under a pressure of 0.9 MPa and at a temperature of 160 ° C. To the process, 130m ³ / h cyclohexane with addition of about 1 ppm of cobalt in the form of cobalt naphthenate as the catalyst and air in total amount of 5800m ³ / h out. In the individual, bounded by the shell 1 in the transverse walls 2 and by the Rachel liquid to the level 3 sections of the reactor. "The air was introduced by means of bubble streams forming flattened, transverse to the direction of movement of the reaction liquid jets, which are unventilated by each other Zones are separated. In the blasting zones, the reaction liquid, together with the air bubbles, has an ascending movement, and in the uninflated zones separating these zones, a falling movement of the reaction liquid occurs. Therefore, intensive circulation occurs within the volume treated by the oxidizing medium.

The process was conducted in a horizontal cylindrical reactor with a total capacity of 110m ³ divided into 6 reaction sections. In the individual sections, containing the sixth section intended to decompose the cyclohexylhydroperoxide, a frame manifold for the oxidizing gas was used, which consisted of the reactor-axis transverse, arcuate, pre-drilled pipe arms 4 and elongated pipe connection elements 5 was. Between the arcuate, pre-drilled pipe arms 4 a distance was maintained, which prevented the connection of the outgoing from the adjacent arms blisters together. This distance was 450mm. Between the individual arcuate, predrilled pipe arms 4, two submerged under the liquid level and free passage above the bottom of the reactor letting partition walls 6 were arranged. The oxidation gas was fed to the vertoiler via the vertical line 7. Selectivity of the reaction was calculated to be 85% based on the analysis of the liquid product from the reactor, converted to cyclohexanol, cyclohexanone and cyclohexylhydroperoxide. In the oxidation of cyclohexane, in which the air was introduced in the form of bubble jets in a known manner, which was carried out while maintaining identical pressure and temperature values and identical loading of reagents in a reactor identical in overall capacity and number of reaction sections, became a selectivity the reaction reaches 82.5%.

Claims (5)

A process for the oxidation of hydrocarbons in the liquid phase by means of the oxygen-containing gases by gassing the reaction liquid in a bubble reaction apparatus with the oxidizing gas in the form of bubble streams leading to a series of flattened, to the flow direction of the liquid in the reactor or in a section of Reaktionspapparates transverse beams are formed, characterized in that the adjacent beams are separated from each other by non-fumigated zones. 2. Device for the oxidation of hydrocarbons in the liquid phase, consisting of one to a series of provided with pipe manifolds for the Oxydationsgas sections lying horizontal drum, wherein the manifolds are composed of a series of perpendicular to the flow direction of the liquid predrilled arms, characterized in that the individual arms (4) of the distributors are arranged at a mutual distance which prevents the gas bubbles from connecting to each other from the adjacent arms, which distance is more than 400 mm. 3. A device according to claim 2, characterized in that between the individual arms (4) to parallel Zirkullations-partitions (6) are arranged, which are immersed under the liquid level and allow a free passage above the bottom of the reactor. 4. Apparatus according to claim 3, characterized in that between the arms (4) each two partitions (6) are arranged. 5. Apparatus according to claim 3, characterized in that between the arms (4) each have a partition wall (6) is arranged.