SU490296A3 - Method for reforming petroleum fractions - Google Patents

Description

(54) METHOD FOR REFORMING OIL FRACTIONS

one

This invention relates to methods for catalytic reforming of a crude feed used to produce high octane gasoline and aromatic hydrocarbons.

The known method of reforming petroleum fractions in the presence of a bifunctional catalyst on an inert support.

However, the catalytic method for producing high octane gasoline and aromatic hydrocarbons is based on a combination of different reactions that are endothermic in their combination. Therefore, the implementation of this method uses large-sized clyidric reactors, especially in diameter, which contain reaction catalysts and within which oil fractions are produced.

Due to the general eidothermicity of the reaction during the process, a decrease in temperature occurs, which can be raised and which depends primarily on the reactivity of the oil fraction being treated, especially the content of naphthees.

Thus, the temperature drop depends on the chemical and loading parameters. It also depends on the degree of intensity.

catalytic reaction during operation. It is known that the temperature drop in the reactors is more significant at the point of entry of oil fractions than at their output.

A disadvantage of the known process is the following. The temperature drop during the process is compensated for by applying heat to the reaction mass to maintain an optimum catalysis temperature.

However, the introduction of this heat should be limited, since with too much overheating, partial thermal cracking of the cracking load and destruction of the catalyst are observed.

On the other hand, if the temperature is not sufficiently high, the catalytic reactions do not proceed under optimal conditions, therefore, in this case, the HC output is sufficiently high.

The purpose of the present invention is to increase the efficiency of the process.

This goal is achieved due to the fact that the feedstock is sequentially passed through an inert zone containing a catalyst support; zone containing a mixture of catalyst with a substrate; and the zone containing the catalyst, with each zone heated to process temperature.

According to the proposed method, heat is introduced into the reaction system as the need for it arises, and an almost adiabatic process is obtained.

Each of the above zones can be separated from one another by intermediate zones that do not contain any substance. Heaters may be placed along the zones, supplying variable amounts of heat to the reaction stream, being moved in each of the said zones. In this case, the temperature in the direction of flow is kept constant during its passage through the zones. With catalytic reforming, this temperature is 450-550 ° C.

According to the invention, the amount of heat input is fixed according to the internal temperature of the catalyst.

The internal temperature of the catalyst can be iria and a constant reference temperature of the reaction.

The apparatus for heating according to the invention can basically be electrical or radiating devices. An electrical winding can also be used to heat the pipes, which will provide heat individually to each pipe or to specific locations of each pipe. When using emitters, they can be arranged in such a way that the heat flux heats up several pipes simultaneously.

The invention does not exclude the possibility of supplying heat directly to the catalyst into the interior of the reaction tubes, for example by passing heated gases through them. This heating method may be advantageously used for large diameter pipes, but the catalytic reforming method according to the invention mainly concerns tube furnaces with a relatively small diameter, which makes it necessary to use external devices for heating pipes. The diameter of such cylindrical tubes is 100-250 mm.

For conventional sizes of conventional pipes, the heat transfer outside the pipes to the load and the catalyst does not allow the use of high temperatures.

The introduction of external heat, which is provided by the invention, will allow to achieve adiabatic conditions sufficient for practical needs, but it must be combined with a special arrangement of catalysis zones.

At the inlet of the reaction tube a layer is inert from the chemical point of view, consisting only of the catalyst base.

According to the invention, this inert layer is followed by a zone containing a diluted catalyst. The dilution wall can vary from 10% to 90%, depending on the characteristics of the product being processed.

When reforming oil fractions, the degree of dilution depends on the origin of the crude oil used, as well as the octane

Isla gasoline, which must be obtained at the end of the process.

In the examples, different degrees of dilution of the catalyst are shown, taking into account the spatial velocity, i.e. the ratio that exists between the charge rate and the weight of the active catalyst.

In all applications, the raw material is introduced in a cold state and the temperature of section 1 is maintained so that the raw material evaporates.

The spatial velocity is equal to the quotient from the division of the charge flow rate (l / h) by the weight of the active catalyst. Thus, the spatial velocity depends on the charge flow rate and the weight of the catalyst.

Figures showing adiabaticity. process, are the maximum deviations (more or less) of the actual measured temperature in the catalysis zone from the theoretical temperature. These figures are given both for experiments carried out under almost adiabatic conditions and for experiments conducted under non-adiabatic conditions.

In all experiments, the total pressure is equal to 25 bar with constant gas recirculation 1.

A series of experiments with changes in spatial velocity and temperature was carried out. The following expenses are selected: 1.2; 2.4; 3 l / h. The catalyst consists of alumina granules, which serves as the basis for catalytic actives.

Dilution of the catalyst is carried out by thorough mixing in the required proportions of 100% of the catalyst and the alumina pellets themselves.

All given in tab. 1 digits dapy for cylindrical catalysis zones with an inner diameter of 45 mm.

It is desirable to combine the location of the diluted catalyst zone with the introduction of idle zones separating the actual catalysis zones. In all cases, the pure active catalyst is in the last zone along the course of the reaction stream.

Due to this arrangement of the catalyst, smaller deviations from

adiabatic conditions than with existing technology, while receiving increased loading costs.

Thanks to the invention, higher octane numbers and a higher content of aromatics are obtained in comparison with the classical catalytic reforming conditions while maintaining the same operating temperature.

An advantage of the invention is also that the operating conditions of the catalyst are more uniform, which contributes to less catalyst response.

The experiments were carried out in a reaction tube with an internal diameter of 4.5 cm and a length of 2 m. The pipe was divided into six sections, independently and

individually heated by thermal layers. The dimensions of the six sections are as follows:

Length, cm

Section 25 25 25 25 50 50 1 2 3 4 5 6

Table 1

table 2

For these five types of distribution and indicated loading costs, the spatial velocities are given in Table. 2

The experiments were carried out at 480 and 509 ° C. For comparison, experiments with a distribution A at 505 ° C and a spatial velocity of about 0.8 (at a flow rate of 1.2 l / h) are given.

The results obtained for each of the selected temperatures are given in table. 3

Note. A-adiabatic process; ON-nonadiabatic process.

Subject invention

A method for reforming petroleum fractions in the presence of a bifunctional catalyst in an inert support, characterized in that, in order to increase the efficiency

T a b l II c a 3

process, the raw materials are sequentially passed through an inert zone containing a catalyst substrate; zone containing a mixture of catalyst with a substrate; n zone containing the catalyst, heating each zone to the process temperature.