US3397251A

US3397251A - Method of producing ethylene and acetylene

Info

Publication number: US3397251A
Application number: US427598A
Authority: US
Inventors: Glinka Carl
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-09-30
Filing date: 1965-01-25
Publication date: 1968-08-13
Anticipated expiration: 1985-08-13
Also published as: DE1443967A1; GB1064602A; FR1428660A

Description

Aug. 13, 1968 c. GLINKA METHOD OF PRODUCING ETHYLENE AND ACETYLENE Filed Jan. 25, 1965 2 Sheets-Sheet 1 III. II I11 I;

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Aug. 13, 1968 c. GLINKA METHOD OF PRODUCING ETHYLENE AND ACETYLENE Filed Jan. 25, 1965 2 Sheets-Sheet z Inventor.- Ccu Z 50 0.

b 7 @11 4! fir/hr AA /fi 7 United States Patent ice 7 Claims. of. 260679) ABSTRACT 6F THE DISCLOSURE The methods disclosed relate to producing ethylene and acetylene from high boiling point liquid hydrocarbons, i.e. hydrocarbons having a boiling point between 200 and 400. This method consists mainly in conducting the hydrocarbons in the form of a plurality of substantially parallel streaming filaments of liquid through a stream of inert gas at a temperature above the boiling range of the hydrocarbons, re-exposing the gaseous hydrocarbons thereby formed to a second stream of inert gas at a temperature high enough to cause ethylene or acetylene to be formed, and then withdrawing the resultant gaseous product through the intervening spaces between the streaming filaments of liquid hydrocarbons in countercurrent thereto.

This invention relates to a method of producing ethylene and acetylene from high boiling liquid hydrocarbons i.e. hydrocarbons having a boiling point between 200 and about 400 C. I

According to the invention the heat required for cracking such high boiling hydrocarbons to ethylene and acetylene is introduced by inert gases. Methods of producing ethylene and acetylene from low boiling gaseous and liquid hydrocarbons involving the use of inert gases for introducing the heat are already known to the art. However, in order to produce ethylene and acetylene molecules directly from high boiling hydrocarbons special steps must be devised to bring about the much larger number of cracking and other reactions required for the decomposition of the higher molecular stock to the final product and for supplying the greater quantity of heat that is needed. This heat must be brought to the treated hydrocarbons by the inert gases within a higher temperature range because the formation temperature of ethylene is in the neighborhood of about 800 C. and that of acetylene at about 1200 C. The rapid cooling to temperatures below 400 C. of the ethylene and acetylene molecules that are then formed, which is necessary to prevent them from further reacting or decomposing, likewise presents problems because the considerable temperature drop from 1200 C. to under 400 C. of the heat carrier gases and of the products may well adversely affect the thermal economy of the entire process. Careful consideration must also be given to the fact that at temperatures exceeding 1000 C. the greater proportion of the hydrocarbons is decomposed into carbon and hydrogen and that the carbon thus formed may interfere with the process, fouling the gases as well as the products.

It is therefore the object of the present invention to develop a process in which the reactions occurring in the thermal cracking of high boiling hydrocarbons are so controlled that they will proceed smoothly, economically and without trouble in the manner desired.

According to the invention this is achieved by conducting the hydrocarbons in the form of a plurality of substantially parallel streaming filaments of liquid through a stream of inert gas at a temperature above the boiling range of said hydrocarbons, by re-exposing the gaseous hydrocarbons thereby formed to a second stream of inert 3,397,251 Patented Aug. 13, 1968 gas at a temperature high enough to cause ethylene or acetylene to be formed and :by then withdrawing the resultant gaseous product through the intervening spaces between said streaming filaments of liquid hydrocarbons in countercurrent thereto.

In this method the necessary cooling of the ethylene and/ or acetylene thus formed is achieved by withdrawing the same in countercurrent to the streaming filaments of cool oil. Owing to evaporation of oil from the surface of the filaments of liquid that are in contact with the hot gas, the temperature of the oil does not substantially rise and it does not exceed the boiling temperature of the oil. Preferably the temperature of the entering oil is maintained at a level of about C. by recycling and cooling the same outside the reactor and by introducing fresh oil to replace the vaporised oil. The streaming oil filaments are therefore able to cool the ethylene or acetylene to about 250 C. abruptly within a fraction of a second and the ethylene or acetylene molecules are thus preserved.

In view of the formation temperatures of ethylene and acetylene the inert gases which provide the necessary heat must be sufiiciently hot for the necessary temperatures to be reached. The temperatures needed for producing low boiling gaseous hydrocarbons from liquid hydrocarbons are relatively very much lower. Moreover, since the treating times are very short it is advisable for the inert gases to have temperatures substantially above the boiling range of the liquid hydrocarbons and substantially above the formation temperature of the ethylene and/ or acetylene. Generally speaking, the inert gases used for the first thermal treatment should be at a temperature exceeding 1000 C. and for the second treatment the gases should have a temperature exceeding 1200 C. for the production of ethylene and a temperature above 1500 C. for the production of acetylene.

Preferably the proposed method may be performed by first conducting a stream of inert gas at a temperature exceeding 1000 C. transversely through the vertically descending filaments of liquid hydrocarbons and then into a second stream of inert gas at a temperature exceeding 1200" C., the resultant gas mixture being thereafter reintroduced into the vertically descending filaments of liquid hydrocarbons and withdrawn upwards in countercurrent thereto between the filaments of liquid. Alternatively the method may be performed by withdrawing the gaseous hydrocarbons formed by the action of the first stream of inert gas from the process and by reintroducing their low boiling components, after separation from the inert gas, into the same stream of inert gas and then discharging them, together with the products that are formed, upwards between the filaments of streaming liquid in countercurrent thereto.

The invention will now be particularly described by reference to two illustrative embodiments of apparatus for performing the method. These are shown in the accompanying drawings in which FIG. 1 is a longitudinal section of apparatus for producing ethylene by the method proposed by the present invention;

FIG. 2 is a section taken on the line IIII in FIG. 1,

FIG. 3 is an illustrative example of apparatus for the production of acetylene according to the invention, and

FIG. 4 is a section taken on the line IVIV in FIG. 3.

With reference first to FIGS. 1 and 2 a cylindrical upright reactor 1 has an enlarged cylindrical head 1b. The lower portion 1a is likewise cylindrically enlarged and lagged with a heat insulating jacket 13. The enlarged head 1b contains a header tank 2 for the reception of the oil that is to be processed entering through a pipe 7. The floor 2a of the tank has an annular perforated portion through which the oil, in the form of a large number of separate filaments 3 can descent in free fall through the reactor chamber 1 and the upper part of the enlargement 1a at the bottom. The filaments 3 of streaming oil fall into the lower part of the enlargement 1a in which the oil forms a pool communicating through a pipe 5 with a tank 6 containing a fioat 6a which controls the level N of the oil in the pool. From tank 6 the oil is forced by a pump 8 through a heat exchanger 9 back into the header tank 2. The bottom coned end of the enlarged lower part 10 of the reactor is provided with a cock 10 for draining olf solid deposits. concentrically located inside the reactor 1 between the two enlarged portions 1a and 1b is a tube 11 which extends into the upper part of enlargement 1a, and which defines an annular chamber 12 through which the filaments 3 of streaming oil descend. The annular space inside the enlargement 1a surrounding the path of the descending oil is divided by a radial refractory ring 4 into two parts. The bottom end of the inner tube 11 is protected by a refractory shield 18.

Combustion gases at a temperature of about 1400 C. are generated in a furnace 14 and taken through a duct 15 to a central cylindrical distributor 16 whence they issue and pass through the filaments 3 of streaming oil from the inside roughly in the radial direction P. Some of the oil on the surface of the filaments is evaporated and some of the oil vapours thus evolved are converted into gaseous low boiling hydrocarbons by cracking. The evaporation of the oil reduces the temperature of the combustion gases to about 600 C. and the produced gaseous hydrocarbons mix with gases in that part of the annular enlargement 1a that is situated above the refractory ring 4. A second stream of combustion gases at a temperature of about 1400 C. is at the same time tangentially introduced through a duct into this part of the enlargement 1a (cf. FIG. 2). In mixture of this gas into the gas-vapour mixture which has cooled to about 600 C. raises the temperature level again to about 800 C. whereby part of the low boiling hydrocarbons in the combustion gases is converted to ethylene.

The mixture of products, ethylene, hydrocarbons and combustion gases thus formed leaves through a pipe 17, but first at 19 it is defiectedinto the path of descent in annular chamber 12 of the filaments of liquid oil which enters the reactors at a temperature of about 180 C. The gases are thus abruptly cooled to a temperature at which the ethylene molecules that have been formed will not further react or crack. Finally, the products are separated from the combustion gases and isolated.

The relatively small proportion of the recycled oil which evaporates upon making contact with the hot gases is relaced by the introduction of fresh oil which flows into the header tank 2 through pipe 7. The temperature of the oil i raised to about 300 C. by the combustion gases. The fresh oil introduced and the cooling effect in the heat exchanger 9 maintains an entry temperature of about 180 C.

The first treatment of the oil with the hot combustion gases gives rise to the following products in percent by weight of hydrocarbons introduced:

Percent Saturated gaseous hydrocarbons 40 Liquid hydrocarbons 51 Solid residuum 9 The second treatment with the hot combustion gases produces a mixture of the following composition in percent by weight of hydrocarbons introduced:

The solid residuum comprises the 9% residuum from the first treatment and a 6% residuum from the second heat treatment.

The plant illustrated in FIGURES 3 and 4 is intended for the production of acetylene. It differs from that shown in FIGURES 1 and 2 primarily in that the header tank 22 containing the crude oil that is to be treated has a floor 22a with outlet openings distributed over the whole of its area and in that the cylindrical reactor chamber 21 is entirely free from obstructions, so that the descending filaments 3 of oil fill the whole of its section. The enlargement 21a at the lower end of the reactor is substantially cone-shaped but comprises a short upper cylindrical portion containing an admission 36 for hot inert gases at a temperature of about 1600" C., such as combustion gases, as well as an admission 24 for lower boiling gaseous hydrocarbons that have been preheated to a temperature of about 200 C. The bottom end of the enlargement 21a is fitted with a trap 30 for the withdrawal of solids and has an outlet 25 communicating with a tank 26 containing a fioat 26a for keeping the oil pool at a constant level N. From tank 26 the oil can be pumped back into the header tank 22 by a pump 28. The outlet 37 at the top of the enlarged head 21b of the reactor 21 is connected to a cooler 34 in which the liquid hydrocarbons precipitate and from which acetylene, ethylene and very low boiling hydrocarbons, namely those boiling under 0, are withdrawn overhead at 35. Hydrocarbon fractions boiling between 0 and 150 C. are withdrawn at 38 and 39 and taken into a container 29 whence they are blown by a pump 31 into the upper part of enlargement 21a through admission 24. FIG. 4 shows that the admissions in the enlargement 21a are tangential. Hydrocarbons boiling above C. leave the cooler 34 at the bottom 40 and How into the sump of the reactor.

The inert gases which are blown into the bottom enlargement 21a at a temperature of 1600 C. through admission 36 flow in the direction of arrow P1 in a descending spiralling path and penetrate into the interior of the streaming shower of filaments 23. They therefore make contact with the descending filaments of oil 23. Part of the oil vapour thus produced is converted into lower boiling hydrocarbons which are then withdrawn upwards in countercurrent to the streaming filaments of oil and taken to the cooler 34 through pipe 37. From the cooler hydrocarbons boiling between 0 and C. enter tank 29 and after their temperature has been raised to 200 C. they are blown by pump 31 tangentially in the direction of arrow P2 into the upper part of enlargement 21a. They therefore mix with the hot 1600 C. gases flowing as indicated by arrow P1 and are thus now partially converted to acetylene and ethylene. The mixture of hot inert gases, acetylene, ethylene and hydrocarbons ascends between the filaments of liquid oil in countercurrent thereto and is cooled to about 250 C. before returning to the cooler 34 through pipe 37 The acetylene and ethylene that have been formed, the inert gases, and highly volatile hydrocarbons leave together through pipe 35, whereas the remaining hydrocarbons pass through the cycle again.

The temperature of the oil in the header tank 22 is maintained at a temperature of about 180 C. by the supply of fresh oil through pipe 27 or by a cooler not specially shown in the drawing, which may correspond to cooler 9 in FIG. 1. During their descent these hydrocarbons therefore remain liquid and form a pool in the sump at the bottom of the enlargement 21a. During its descent the temperature of the oil may rise to near boiling point. The temperature of the gas which is blown in through admission 36 at 1600 C. may drop a few hundred degrees to say 1200 C. in chamber 21a and when the gas and the gaseous products that have formed have entered the path of the oil streams 23 their temperature abruptly falls to about 400 C., a temperature which may be further reduced to about 250 C. as the gases pass upwards between the filaments of streaming oil.

What I claim is:

1. A method of producing ethylene or acetylene from liquid hydrocarobns boiling between 200 and 400 (3., comprising conducting said hydrocarbons in the form of a plurality of substantially parallel streaming filaments of liquid through a stream of inert gas at a temperature above the boiling range of said hydrocarbons, re-exposing the gaseous hydrocarbons thereby formed to a second stream of inert gas at a temperature high enough to cause ethylene or acetylene to be formed, and then withdrawing the resultant gaseous product through the intervening spaces between said streaming filaments of liquid hydrocarbons in countercurrent thereto.

2. The method claimed in claim 1, wherein the first stream of inert gas is at a temperature exceeding 1000 C. and the second stream of inert gas is at a temperature above 1200 C.

3. The method claimed in claim 1, wherein the first stream of inert gas has a temperature exceeding 1000 C. and the second stream of inert gas has a temperature above 1500 C.

4. The method claimed in claim 1, comprising conducting a stream of inert gas at a temperature exceeding 1000 C. transversely through the vertically descending filaments of liquid hydrocarbons and then into a stream of inert gas at a temperature above 1200 C., the gas mixture being finally taken upwards between the vertically descending filaments of streaming hydrocarbons in countercurrent thereto.

5. The method claimed in claim 1, comprising withdrawing the hydrocarbons formed in the first stream of hot inert gas, separating the lighter boiling components from the inert gas, returning them into the stream of hot inert gas and finally withdrawing them together with the products that form in countercurrent upwards between the vertically descending streaming filaments of liquid hydrocarbons.

6. The method claimed in claim 1, comprising conducting the hydrocarbons that have passed through the stream of hot inert gas, together with the solids formed therein, to apparatus for treating fuels containing water and ash, and then recycling them for further treatment after they have been cooled to at least 200 C. and the solids have been removed therefrom.

7. The method claimed in claim 5, wherein the inert gas has a temperature of about 1600" C.

References Cited UNITED STATES PATENTS 2,113,536 4/1938 Grebe et a1. 260-679 2,921,100 1/1960 Pettyjohn 260679 2,934,410 4/1960 Smith 160679 3,005,857 10/1961 Steinhoferetal 260679 DELBERT E. GANTZ, Primary Examiner.

I. D. MYERS, Assistant Examiner.