CS245666B1 - An automatic welding apparatus according to a complex contour, comprising a first § a second movable sled placed simultaneously on the first and second pair of guides, and provided with a welding torch, a driving group and a rack in continuous engagement with the gear, characterized in that the first movable sled ( 16) and the second movable carriage (22) are mounted to the first guide screw (15) and the second guide screw (16) connected to the drive group (1) by a selective engagement mechanism (2), the toothed rack (24) being attached to the first movable suction (16), the gear (25) is mounted on the vertical shafts (26) positioned by the bearings in the bearing housing (27) fixed to the second movable suction (22), the welding shaft is fixed to the vertical shaft (26) a burner (29). Advantages of the device: the device allows for the implementation of contact and angular welds according to a complex contour, the drive being carried out by a single electric motor without reversing, a secure direction of the welding torch with a contact speed and an angle of the torch axis relative to the contour normal, rapid adjustment for different welding path configurations. - Google Patents

Abstract

A method for pre-treating a feedstock for catalytic reforming boiling between 60 and 200 °C, which contains 5 to 45 wt. % of a hydrocarbon of the cyclohexane type, 5 to 45 wt. % of an alkylcyclopentane type hydrocarbon, 5 to 20 wt. % of aromatic hydrocarbons, preferably below 0.2 ppm S, below 1 ppm of water and the remainder alkane hydrocarbons, in which the mixture is subjected to selective dehydrogenation of cyclohexane and its homologues, which is carried out at a temperature of 375 to 450 °C, under a pressure of 1.5 to 3.5 MPa with a rate of 5 to 25 volumes of the mixture per volume of catalyst per hour, in the presence of 250 to 2,000 volumes of circulating gas containing hydrogen and saturated hydrocarbons C. to C., per volume of the mixture on a fixedly supported activated catalyst containing 0.15 to 0.35 wt. platinum and 0.12 to 0.85 wt. % rhenium, with the mass ratio between platinum and rhenium being 1 : 0.9 to 2.5, further 0.6 to 1.5 wt. % chlorine on gamma alumina with an admixture of 0.05 to 5 wt. % titanium dioxide

Description

The invention relates to the selective dehydrogenation of cyclohexane and its homologues present in a mixture of saturated and aromatic hydrocarbons boiling between 60 and 200°C prior to catalytic reforming of the mixture.

Catalytic reforming of gasoline has been continuously developing for over 30 years, both in terms of the catalytic system, the mechanical arrangement and the operating parameters. Since 1966, a new era of development has begun with the introduction of stable bimetallic catalysts. This has led to adjustments to the technology, to a reduction in pressure and gas circulation and to a change in the mechanical arrangement, especially in so-called semi-regenerative units, in which a fixed catalyst is used, which is only occasionally regenerated by removing coke. The process is very energy-intensive, because it operates at high temperatures and hydrogen-containing gas is circulated in a molar ratio of over 5 to the incoming gasoline. Strongly endothermic reactions, especially at lower pressures, do not allow maximum use of the catalyst in reactors that are adiabatic.

The temperature drop in the reactors is usually from 70 °C to 5 °C depending on the position of the reactor in the system, the size of the gas circulation, the shape and design of the reactor. Particularly high catalyst underutilization occurs when reducing the pressure in units designed for higher pressures with disadvantageous distribution of catalysts into 3 to 4 reactors arranged in a row. Difficulties also occur with the use of heating furnaces for individual reactors, which are then undersized. It is therefore not possible to produce a high-quality product for the production of aromatics and low-lead gasoline in the required quantity. Reconstruction of machinery, usually unused, for this process is as expensive as the construction of a new unit with progressive parameters.

The invention provides a solution by pre-treating a feedstock for catalytic reforming, boiling in the range of 60 to 200 °C, which contains 5 to 45 wt. % of cyclohexane-type hydrocarbons, 5 to 45 wt. % of alkylcyclopentane-type hydrocarbons, 5 to 20 wt. % of aromatic hydrocarbons, preferably below 0.2 ppm S, below 1 ppm of water and the remainder alkane hydrocarbons, consisting in subjecting this hydrocarbon mixture to selective hydrogenation of cyclohexane^ and its homologues, which is carried out at a temperature of 375 to 450 °C, under a pressure of 1.5 to 3.5 KPa with a rate of 5 to 25 volumes of the mixture per volume of catalyst per hour, in the presence of 250 to 2,000 volumes of circulating gas containing hydrogen and saturated hydrocarbons C^ to the volume of the mixture, on an activated catalyst containing 0.15 to 0.35 wt. % of platinum and 0.12 to 0.85 wt. % rhenium, the weight ratio between platinum and rhenium being 1 : 0.9 to 2.5 and further 0.6 to 1.5 wt. % chlorine on gamma alumina and an admixture of 0.05 to 5 wt. % titanium dioxide and the product freed from 30 to 95 3 cyclohexane and its homologues is subjected to a multi-stage conversion into an aromatic concentrate by reforming.

Of the cyclohexane types of hydrocarbons, C1 to C3 alkylcyclohexanes are predominantly present. Preferred temperatures for selective dehydrogenation are 420 to 440 °C, a pressure of 2 to 2.8 MPa and a rate of 10 to 20 volumes of mixture per volume of catalyst per hour in the presence of 800 to 1,700 volumes of gas and a hydrogen content per volume of liquid mixture. The preferred platinum content is 0.25 to 0.35 wt. and the weight ratio of Pt and Re is 1:1.1 to 1.5. Catalyst activation, or Reactivation after annealing of the columns is carried out by gradual drying in nitrogen at temperatures from 20 to 450 °C, pre-reduction with hydrogen at 350 to 450 °C, then reoxidation in nitrogen with 0.2 to 15 vol. % oxygen and finally reduction with hydrogen with a maximum of 20 ppm water at 350 to 450 °C and stabilization with 0.05 to 0.2 wt. % sulfur in the form of, for example, carbon disulfide.

By analyzing the method according to the invention, the scope of applicability can be determined, which implies that an alkylcyclohexane converter is connected to the reforming unit, preferably before the raw material enters the washing section of the heating furnace, heated by a system of exchangers with the reaction product. The conditions are chosen so that at the temperature of the hydrocarbon and gas mixture reached in the exchangers, the majority of cyclohexanes are selectively converted to aromatics, which results in the majority of cyclohexanes, or alkanes, being hydrocracked. The product from the selective dehydrogenation is freed from cyclohexanes and the non-equilibrium mixture of alkylcyclopentanes with alkanes and aromatics is fed to the first reforming stage.

There, optimal conditions can then be selected for the selective dehydroisomerization of homologues with cyclopentane to aromatics under conditions where alkanes are not yet cleaved under hydrogen pressure. Cyclopentanes are not cleaved either, because the more isothermal nature of the reactor means that the heating at the inlet is lower at the same outlet temperature. For the dehydrocyclization of alkanyls to aromatics, the remaining two reactors in the catalytic reforming unit, in which there is the most catalyst, operate almost isothermally with less heating. It is also possible to maintain the same or increasing inlet temperatures in them, as opposed to the previous decreasing ones, and thus achieve higher conversions. Although the range of concentrations of metals and activators on the catalyst fits into the definition of reforming catalysts, it is characterized by a favorable range of concentrations of both active metals, which allows selective work at low temperatures. The proof is that under these conditions with the aforementioned catalyst, the reaction product is pure hydrogen, which will be shown in the examples below.

In terms of equipment for this treatment of hydrocarbon feedstock for catalytic reforming, it is advantageous to use, for example, a reactor from a smaller reforming unit, which has already been removed from operation due to lower processing, for example, as a upstream reactor.

An example of use is given below. Its conditions illustrate the method according to the invention but do not limit the scope of the invention.

Example

To evaluate the importance of the alkylcyclohexane converter (ACK) device in the reforming unit, the conditions of its operation in the temperature range of 400 to 460 °C with a space velocity of 6 to 12 h ^- ' and raw materials containing approximately 10 wt. % alkylcyclohexanes were first studied.

From Table 1, which shows the composition of the feedstock and product from ACK, it is evident that under ACK conditions, 60 to 80% of alkylcyclohexanes can be selectively removed without changing other types of hydrocarbons. The temperature gradient is half that of the first reactor of the three-stage reforming unit.

Under optimal ACK conditions, achievable in the reforming unit behind the heat exchangers, a larger amount of ACK product with the composition given approximately in the table column was then prepared. This product was then reformed in a conventional three-reaction layer system and the utilization of the catalyst was assessed according to temperature gradients and stability. It is evident from Table 2 that the isothermality improved and thus also the octane number increased at the same inlet temperatures. For the same octane number, the reaction temperatures could then be reduced and thus the energy consumption 1. The dependence of the VM octane number on temperature shows that when 70% of cyclohexanes are removed in ACK, the reaction temperatures can be reduced by 7-10 °C for the same conversion in the range of OČVM 89 to 96 units. Reducing the reaction temperature by the indicated value brought an extension of the catalyst stability by 33%

Table 1

Selective conversion of alkylcyclohexanes (AcCg) in gasoline according to the invention (p = 2.5 MPa, vol. ratio Hg : gasoline 1,200 : 1, catalyst*>: 0.3 wt. % Pt and 0.3 wt. % Re on gamma alumina with 0.9 wt. % chlorine)

Raw material 420 Product at temperature 440 460 volume speed, h ^_> - 6 12 6 12 12 analytical characteristics ^day 20 0.752 0.752 0.752 0.758 0.754 0.759 rain, curve start °C 107 85 93 96 93 89 50% vol. °C 139 140 141 141 141 14.0 end °C 178 182 181 184 182 184

Table, continued

Raw material Product at temperature

T23-\- -ΪΤδ- - flavors % wt. 9.7 14.4 13.4 18.0 16.6 18.9 cyclanes -- 27.9 22.9 23.8 19.6 21.0 18.7 of which AcCg 9.3 21.5 5.4 1.1 2.4 0.2 circulating gas: % vol. H ₂ 100 100 100 100 100 98

x) catalyst activation performed by the following steps (at 1.0 KPa):

- annealing in N ₂ at 20 to 500 °C

- reduction with hydrogen and 10 ppm HjO at 425 °C

- reoxidation with nitrogen and air (0.2 to 5 vol. % 0 ₂ ) at 350 to 425 °C

- deoxidation with air at 425 °C

- hydrogen reduction with 10 ppm H ₂ O at 425 °C,

- sulfurization with carbon disulfide to 0.05% by weight of sulfur

Table 2

Reforming of original gasoline and gasoline modified to ACK (p = 2.5 MPa; vol. rate 1.5 h, inlet temperatures to the 3· reactor 514 and 521 °C, catalyst*^ see Table 1)

Raw material Primary gasoline Gasoline after ACK temperature 3. reactor °C 514 521 514 521 raw material: flavors % wt. 10 10 17 ,7 AcCg % wt. 10 10 3 3 reform results: temperature gradient in reactor 1 °C 34 35 15 16 reformate yield, % wt. 87.7 84.5 94.0 80.8 OfiVM Reformed 89.1 93.5 94.5 96.6

x) distribution of catalyst into the 3rd reactor 1:2:4 '

Claims (4)

SUBJECT OF THE INVENTION Process for pretreating a catalytic reforming feedstock boiling in the range of 60 to 200 ° C, comprising 5 to 45 wt. % of hydrocarbons of the cyclohexane type, 5 to 45 wt. % alkylcyclopentane type hydrocarbons, 5 to 20 wt. aromatic hydrocarbons, preferably below 0.2 ppm S, below 1 ppm water; The process of claim 1 wherein the mixture is subjected to selective dehydrogenation of cyclohexane and its homologs at a temperature of 375 to 450 ° C, at a pressure of 1.5 to 3.5 MPa at a rate of 5 to 25 volumes of catalyst per volume of catalyst per hour, in the presence of. 250 to 2000 volumes of circulating gas containing hydrogen and saturated hydrocarbons C, up to the volume of the mixture per fixed catalyst activated catalyst containing 0.15 to 0.35 wt. % platinum and 0.12 to 0.85 wt. rhenium, wherein the weight ratio between platinum and rhenium is 1: 0.9 to 2.5, further 0.6 to 1.5% by weight. % of chlorine to gamma alumina with 0.05 to 5 wt. titanium dioxide. 2. The process of claim 1 wherein the temperatures are 400-440 [deg.] C., a pressure of 2-2.8 MPa and a rate of 10-20 volumes of the mixture per catalyst volume per hour in the presence of 800-40 ° C. 1,700 volumes of hydrogen containing gas per volume of liquid phase. 3. A process according to claim 1, wherein the content of platinum and rhenium is 0.25 to 0.35% by weight. and a Pt: Re weight ratio of 1: 1.1 to 1.5 by weight. 4. Process according to claim 1, characterized in that the activation or reactivation of the catalyst after annealing of the columns is carried out by successive drying in nitrogen at 20 to 450 ° C, by pre-reduction with hydrogen at 350 to 450 ° C, then by reoxidation in nitrogen with 0.2 to 15% by volume of oxygen, finally reduced by hydrogen with not more than 20 ppm water at 350 to 450 ° C and stabilized at 0.05 to 0.2% by weight. sulfur in the form of eg carbon disulfide.