DE1643672A1 - Process for the production of olefin hydrocarbons by thermal cracking - Google Patents

Description

Bad is ciie Anilin- & Sod a-Fabrik AG-. "'■ - ■■.

Other characters: '.- Q. Z .-: 25 TgO - Hp / from ludwigshafen / Rh., The 6. Oct. T967

Process for the production of olefin hydrocarbons by

thermal cleavage

The invention relates to the thermal cracking of crude oil or ™ of other oils containing non-evaporable residues to ' Olefins, especially ethylene.

It is known to produce olefinic hydrocarbons by thermal splitting gaseous or completely evaporable liquid hydrocarbons in metal pipes coming from the outside be heated, mixed with steam at temperatures above 750 ° C. This gives fission gases rich in olefins as ethylene and propylene are, and contain even higher olefins and diolefins and other cleavage products,.

In general, pipe coils are used for splitting circular pipe cross-section and with horizontal or vertical parallel arrangement of the pipes, either from the ground or be heated from two sides of the furnace by a multitude of burners. -

Up to now it was only possible to use gaseous or vaporizable liquid hydrocarbons, ds gas condensates or distillates deu Roh-61 9/67

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oil to split into olefinic hydrocarbons. Ch. Run -; During operation, coke formation occurs on the inner walls of the pipes. The fission must therefore be interrupted from time to time and the pipes decoked by burning them out with air; this should of course only be necessary at the longest possible time intervals. The formation of coke on the inner wall of the tubes occurs when products containing residues are split, for example when crude oil is split, to such an extent that running times of a few hours can only be achieved. Therefore, no economic splitting of crude oil was possible in this way.

The desire for a cracking process to produce olefins from crude oil or residual oil, which are much cheaper than crude oil distillates, led to the development of a number of processes for the production of olefins from crude oil, in which a principle other than that of pipe fission is used. these cleavage processes require expensive process steps, e.g. the movement of pesticides for heat transfer, the supply of oxygen for heat generation or devices for periodic operation with alternating heating and split phases. These additional measures are the investment costs for the previously known crude oil cracking plants considerably higher than for systems for splitting hydrocarbons in tube furnaces.

It has now been found, surprisingly, that one Gle.fin-Koh.len- Hydrogen through thermal splitting of hydrocarbons

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in a cracking furnace with externally heated pipe coils at temperatures of 750 to 95O ⁰ C with "addition of steam, if you can produce crude oil or other oils containing non-evaporable residues in the convection zone of the cracking furnace together with steam to temperatures of 300 to 500 ⁰ C heated, the heated mixture leads through a Abscheidungsζ one in which the non-evaporated components are deposited, the mixture freed from non-vaporous components splits in a conventional manner and the cleavage gas by direct cooling or by a combination of indirect and direct cooling. - '

According to a preferred embodiment of the method according to the invention, the heated gas mixture after leaving the separator is cooled and at 10 to 100 ⁰ C is liquefied then a further small part of the gas flow again. As a result of the separation of this part of the crude oil, any droplets or mist entrained in the gas, which may still contain small amounts of solids, can be washed out.

As a starting material for the thermal to be carried out according to the invention Any crude oils can be used for cleavage. Accordingly, crude oils containing large proportions of low-boiling components can be used contain, and also those with large amounts of high-boiling components / are used. Accordingly, both crude oils can use low as well as relatively high Conradson test can be processed. As a rule, however, it is advisable to use crude oils with a high Petrol content, e.g. Algerian or Libyan crude oil, or high

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Share of aliphatics, e.g. Landauer crude oil, to be used, as with the best yields can be achieved with these starting materials. Other oils, "the non-vaporizable ones", are also used as starting materials Containing fractions, "such as residual oils or drained oils Crude oils, usable. These oils usually contain 2 to 15, usually more than 5 percent by weight non-vaporizable components,

The thermal cleavage according to the invention can be carried out in tubular furnaces of conventional design. These tube furnaces contain tube coils with tubes of circular cross-section, the clear width of which is 50 to 150 mm. The length of the pipe coils is 20 to 150 m, depending on the desired degree of gap. If you want to achieve a high yield of ethylene, you have to choose strict gap conditions, ie a small clearance and a short can. In cases where mild cracking conditions are to be set because of the need for other • by-products of the cracking, such as pyrolysis gasoline, tubes with a large internal diameter and length are selected.

The thermal cleavage according to the invention is carried out in detail E.g. so that the crude oil or residual oil with half to ~ twice the amount of steam, preferably 1 to 1, 5 times the amount by weight of steam, mixed and against exhausting flue gas in the convection zone of the "cracking furnace to a temperature between 300 and 5OQ C is preheated. The mixture thus obtained, the largest Part consists of vaporous fractions, is removed via a separator, e.g. a residence time separator or a tangential separator, led, in which the non-evaporated portion from the gas

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electricity is disconnected. The unevaporated portions, which are usually 10 to 30fo of the crude oil, are withdrawn and can be used as heavy fuel oil.

The gas stream obtained is either introduced directly into the can or ^{preheated beforehand to 550 to 700 °} C. and then subjected to thermal cracking in the coil. The reaction pressure at the output of the coil is typically about 0.5 to 2 atmospheres gauge _e Depending on the diameter of the tubes and the desired throughput pressures 3-20 possibility atm at the tube inlet are necessary.

The residence time of the hydrocarbon vapor to be split in the cleavage zone is usually 0.1 to 2. preferably 0.2 to 1, see. The dwell time depends on the state of the Gas mixture based on the pipe outlet.

The hot cracked gases are "How-quenched usual at the end of the coil by direct cooling or a combination of direct and indirect cooling to direct cooling it is advantageous to use the condensed from the cracked gases by cooling to 170 to 20O ⁰ O cracked oil, which has a very high content of high-boiling aromatics. In the case of the combination of indirect and direct cooling first ui 100 to 50Q ^ö G "Ujit $ r extraction is quenched by high-pressure steam in a tube refrigerator, for example, and anschließend.durch directly © cooling completely also by injecting aromate & rei ehera gap oil, -d .feo bie to 150 to 25D ⁰ G, cooled.

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This is followed by a work-up, as it is for the work-up = working of fission gases from gasoline is known.

example 1

0.9 to 1.5 Algerian crude oil and steam to be mixed and in the convection zone of the cracking furnace at 45O ⁰ C preheated. The heated mixture is then passed through a residence time separator at this temperature and the non-evaporated portion is separated off and drawn off from the separator. The non-vaporized material amounted to a total of 13% by weight of the crude oil charge; it corresponds roughly to the specification of heavy fuel oil. The gaseous mixture is then ^{heated further to 57O 0} C and passed through a pipe coil with a circular pipe cross section, which is heated from both sides of the cracking furnace, a temperature of the cracked gas of 850 ⁰ C being reached at the end of the pipe. The resulting fission gas mixture is in an indirect. Quench, di a tube cooler for generating high-pressure steam, cooled to 300 ⁰ C and cooled immediately by direct cooling with the product obtained by cooling of the reformed gas at 200 ⁰ C. to 200 ⁰ C oil gap. The cleavage product which has the composition given in the following composition (based on the amount supplied of the Spaltaone, of the crude oil), _s is as described for the working up of the fission gases from the Benzina pal tung common aufgearbeitetί

BATH

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co 0.1 Weight $ 1643672 -7 - H ₂ - 0.8 Il O, Z. 25 150 CH ₄ . 14.9 Il ° 2 ^Η 6 4.0 Il C ₂ H ₄ 27.0 ti CoHo 0.4 Il ά C- ^C 3 ^H 8 0.9 Il ^G 3 ^H 6 14.9 Il ° Ά 0.6 H ^C 4 ^H 10 0.2 Il ^C 4 ^H 8 3.6 Il ^C 4 ^H 6 4.4 Il Cr- + height 28.2 Il

As can be seen from the analysis of the cracked gas, the yield of ethylene 27 wt. ^. When the ethane is returned and renewed cleavage in an ethane cracking furnace increases the Total loot of $ 30, based on the vaporizable portion of the Of crude oil or about $ 26 based on crude oil used.

Example 2

1.6 to Landauer crude oil and 1.5 tons of steam are combined in the convection zone of the cracking furnace at 37o ⁰ C heated. The heated mixture is passed through a tangential separator and the non-evaporated portion is separated off. It amounts to a total of 31 wt. of crude oil input. The vaporized mixture is ^{heated further to 57O 0} C and then heated in a pipe coil with a circular cross-section (by heating the pipe coil from both sides of the cracking furnace) to 83O ⁰ C

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Quenehkühlung as indicated in Example 1 was cooled to 200 ⁰ C, the cleavage product has the following composition:

co 0.1 Weight H ₂ 0.7 CH ₄ 13.2 Il ^C 2 ^H 6 4.1 Il ^C 2 ^H 4 23.2 ti C ₂ H ₂ 0.4 Il C ₃ H ₈ 0.7 Il ^C 3 ^H 6 14.4 Il C ₃ H ₄ 0.5 Il ^C 4 ^H 1 ₀ 0.2 Il ° 4 ^H 8 . 3.8 H ^C 4 ^H 6 4.1 Il C ₅ + hey 34.6 Il Example 3

1.2 tons of Libyan crude oil are heated ^{to 400 °} C. together with 1.35 tons of steam in the convection zone of a cracking furnace. The heated α mixture is passed through a separator and the non-evaporated portion is separated off. He totaled 22 percent. Fo of crude oil use. The vaporized mixture is weiter'erhitzt at 57Q ° C and then heated in a tube coil of circular cross-section through heating of the tubes from both sides of the cracking furnace at 840 ⁰ C. The gap thereby formed gas mixture is cooled by direct cooling with oil gap (with an initial boiling point of 200 ⁰ C) to 25O ⁰ C. The cleavage product has the following composition;

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- 9 - CO 0.1 ffew.5 Il Il O.Z. 25 150 H ₂ . 0.7 * 11 Il Λ (ΤΤ
wXX * -
A. 13, 8 Il 4.0 Il ^C 2 ^H 4 24.0 ir C ₂ H ₂ 0.3 Il • - ■ " ^C 3 ^H 8 0.8 Il ^C 3 ^H 6 15.1 U ^C 3 ^H 4 0.6 Il ^G 4 ^H 10 0.2 I) ^G 4 ^H 8 3.8 ^C 4 ^H 6 4.1 C- + height «, 32.5

Under these test conditions it is possible to set a runtime the cracking of crude oil for more than 2 months without decoking the To achieve the can.

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Claims (3)

• - 10 - O.Z. 25 150 Claims . A process for the production of olefin hydrocarbons by thermal cracking of hydrocarbons in a cracking furnace with externally heated pipe coils at temperatures from 750 to 950 0 with the addition of water vapor, characterized in that _s that crude oil or other non-vaporizable residue containing oils in the convection zone of the cracking furnace is heated to temperatures of 300 to 50O ⁰ C together with steam, the preheated mixture passes through a separation zone in which the non-vaporized components are separated, the mixture freed from non-vaporous components is split in a conventional manner and the cracking gas is passed through direct cooling or a combination of indirect and direct cooling. 2. The method according to claim 1, characterized in that the preheated hydrocarbon / water vapor mixture is ^{cooled by 10 to 100 0} O after the separation of the non-evaporable portion and the portion liquefied during this cooling is used to wash the gas stream before cooling. 3. Process according to Claims 1 and 2, characterized in that the cleavage is carried out at 800 to 900 ^° C. and 0.5 to 2, preferably 1 to 1.5, parts by weight of steam are used per part by weight of hydrocarbon. ■ Badisehe Anilin- & Soda-Fabrik AG 109827/1 830