DE1768585A1 - Process for quenching thermally cracked gas and apparatus for carrying out this process - Google Patents

Description

PATENT LAWYERS

Dr. D. Thomsen H. TSedtke 'G, Bühling

Dipl.-Cham. Oipl.-lng. Dipi.-Chem.

8000 MONKS 3

VAL 33

TELEPHONE 0411/22 «JM

TELEQRAM ADREStS: THOPAYENT

Munich May 31, 1968

The Japanese Geon Company, Ltd.

Tokyo, Japan \, '*

Method of quenching thermal cracked gas and apparatus for carrying out this process

The invention relates to a method of quenching of thermally cracked gas produced by thermal cracking of hydrocarbons at elevated temperatures, e.g. from liquefied petroleum gas. or natural gas, »aphta, Methane odi.dg ^. was generated. .

In the thermal cracking reaction of hydrocarbons, both the cooling conditions and the cracking conditions are of considerable importance for the yield of the desired gas or for the duration of the cracking reaction. Ba the cracking

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takes place in a very short period of time and, moreover, the gas formed by the cracking is very unstable at elevated temperatures, secondary and tertiary reactions such as further cracking and polymerizations occur, which make it difficult to obtain the desired yield and gas composition, provided the conditions stop at elevated temperatures for a longer period of time. Therefore, the thermal cracked gas, the desired cracking has been completed, must be immediately quenched to a temperature at which it is stable. In the event that a cracked gas containing acetylene and ethylene is to be obtained by cracking ITaphta, experience has shown, for example, that the maximum yield is obtained when a reaction time of the order of 5/1000-7/1000 seconds a temperature range of 1000-1300 ⁰ O is used.

In addition, it is known that with such thermal Cracking reactions always tar and carbon is formed.

The means for quenching the thermally cracked gas have heretofore generally been that. a cooling liquid, for example water, was sprayed from spray nozzles at the exit of the cracking zone against the cracked gas migrating from the cracking zone to a gas-liquid separation zone. In this quenching "was not only the device with regard to the need 'speed of spray nozzles complicated? It was beyond the ER-

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sustained cooling effect localized "because it has been difficult to achieve uniform cooling Moreover, it is impossible to 'the clogging of the nozzles to be avoided by the information contained in the cracked gas tar and carbon This increases the local limitation of the cooling effect;.. Moreover, yields 'The need to frequently clean the nozzles or stop the cracking reaction. ■ ·.

The object of the invention is to provide a deterrent method and to provide an apparatus for high temperature cracked gas which avoids the above disadvantages.

According to the present invention, the cracked gas could be uniformly and efficiently cooled by delivering the thermally cracked gas to a gas passage extending from the cracking zone to the gas-liquid separation zone and by: using sets of spray orifices individually at the inlet of the passage or are arranged in several stages, a cooling liquid is sprayed transversely onto the cracked gas stream and needles are intermittently inserted into the spray openings to remove the carbon and tar. The clogging of the spray openings by carbon and tar could be avoided in a satisfactory manner, so that the cracking process could be effectively maintained for a long period of time and, moreover, the maintenance of the device could be simplified . ■

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■ The aforementioned gas passage is a straight tube may -his, wherein a tube having an enlarged portion as is preferred in the case of a Venturi tube, 'because there is no pressure drop occurs _β as a Venturi tube is a tube similar to a venturi scrubber suitable as is used for introducing powders into G-as ... The venturi tube consists of a converging tube section, a dog section (short cylinder) and a

diverging pipe section. According to the invention, except with a venturi tube as described above, essentially identical results-are obtained if a tube is used which consists of a short cylinder and a diverging tube, or who the diverging tube alone than that Gas passage is used. The inclination of the wall to the axis of the diverging tube is preferably in the range from 0 ° to 8 ° from 2 ° to 5 ° · In all 3? all en is in 'terms of the Accumulation of carbon and tar is conveniently about 1 to 3 times larger than the diameter of the entrance to the passage Made outlet of the cracking zone. Regardless of the type of pipes used as the gas passage, the pipe is expediently designed in such a way that that the flow rate of the 'narrow portion (e.g. the mouth portion of the venturi tube) -'- of the passage gas flowing through in the order of magnitude of 50 and 150 meters per second. '"

The spray openings for the cooling liquid are simple or multiple arrangements in the vicinity of the inlet. of the gas passage, i.e. at the narrow section of the gas,

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transit zone next to the krackaone. Even though;. Spray opening "bsi the nozzle design can be used, is the use of those expedient, which is only from one in the wall of the '·' forming the said gas passage; · ' Rohr's drilled hole is the diameter of the spray opening is expediently in the range from 1 to 15 mm, but is a diameter of 3 to 8 ram is particularly preferred.

You monitor the cooling temperature in this quenching. device is determined by the number of spray openings, their diameter, messerj change in the spray pressure of the cooling liquid and closing; the openings are controlled by the threads. In order for the cooling liquid to reach the gas flowing through the passage without loss, the spray speeds are determined by varying the spray pressure of the cooling liquid. This spray speed is usually of the order of 7 to 40 meters per second "To achieve this speed, a spray pressure of the order of 1 to 30 kg / cm ^£ * is used."

The coolants which can be used according to the invention include with the inclusion of water. the petroleum fractions such as Naphta, kerosene, light oils and the like, as well as the aromatic ones Hydrocarbons such as toluene, xylene, baphthalene and oreo oil.

7 / as mentioned earlier are in the thermally cracked; Gas of hydrocarbons free carbon and tar eathal tsn, the flow. Spray openings clog and oils locally

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increase the cooling effect. It has been customary that occupied with carbon and ™ eer "die either during the thermal cracking process or by disrupting this ^process. Remove and clean the contrary, when erfinfiunge- j according needles are used that fit · openings in the bore of the spray and intermittently inserted therein, the orifice clogging carbon and tar can be removed easily and satisfactorily even during the thermal cracking operation, so that it is possible to carry out the cracking operation for a long period of time.

The spray orifices or nozzles are not only fouled by the carbon and tar contained in the cracked gas, but also by foreign matter contained in the coolant. If in general, for example Water is used as the cooling liquid, one has to consider scale, sludge and the like of the water used Exercise care. In the case of the invention, however, it is possible to use water of lower quality, the formation of scale and sludge is relatively large, since the orifices or nozzles by inserting the threads in more satisfactory Way can be cleaned. ■

This cleaning device with threads does not require any special Design; it is sufficient if this facility · by Inserting the needles cleans the nozzle openings after as a result

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Spraying the coolant for a period of time. Clogging of the openings or nozzles by the carbon odes? empty "or by Premdstoffe contained in the coolant has achieved a certain Ausiaa3. One cleaning is therefore sufficient device with threading, a needle drive device and liadel .sealing devices. The! Have rebukes at the end of their diet a diameter slightly less than the diameter of the spray opening so that the needles do not get jammed in the openings and it is not difficult to pull them out. At the near ^ the distal end of the "rebuke" oofindliciien section is fore-ant a stopper is provided, which by contact with άctd 'inner edge The spray opening prevents the! Tadan from doing more than necessary The device can be designed in such a way that the reprimands are automatically issued at a predetermined interval can be used.

In the following, a method of achieving thermal-cracked ^G ases under -Using a quenching is: described in more detail, as explained before. ^

The the cracking zone leaving the thermally cracked gas of high Seniperatur is to your s'ich directly to · the output represents iürac zone "subsequent gas passage directed and sprayed with a cooling liquid, z..B _e with. Water, ^ under Verv ending of sets of Sprühöffmangen which are located in "the vicinity of the inlet of the gas passage around them * The fine _: particle-reduced water is uniformly distributed in the ' _{sas r}

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to quench the gas by instantly withdrawing latent heat from the high temperature cracked gas. In a quenching process of this type, the spray openings are cleaned by 'intermittent use of the needles ' as soon as the clogging by carbon and tar or premixes has reached a certain extent. Maintenance of the cleaning device using needles is very easy. In addition, the carbon and tar collected in the spray ports can be removed without difficulty and the cracking process can be continued for a very long period of time.

If "the Venturi tube or the aforementioned modified Venturi tube is used in the invention, the cooling effect is more uniform than in conventional methods in which the cooling liquid is sprayed from nozzles which are inserted facing the gas flow; thus the required amount of cooling liquid is lower . · in addition, there is an advantage that virtually no pressure loss occurs and the accumulation of carbon and tar in the tube is low. If, furthermore, this embodiment, the apparatus used in accordance with a plurality of such spray orifices, .the ■ in the zone close to the output the Kraekzone ". are closed by the needles, the zone in which the needles are inserted into the openings acts as part of the Kraekzone, so that precise control of the reaction time is possible.

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The invention is shown below with reference to schematic drawings explained in more detail on several exemplary embodiments »It demonstrate: . "■" "·. '■ ·.

ig. 1 to 3 in longitudinal section a device according to the invention for performing the according to the invention

Procedure and ■ · ■

Pig. 4 in a vertical section a cleaning device ·? tion. ' ■ ■. '' ^

The Pig. Fig. 1 shows a way in which a cracked gas containing acetylene and ethylene produced by the flame cracking of coal fuels is quenched into a Venturi-Kohr-type gas passage using a cooling liquid sprayed from spray orifices, which. are equipped with a device using needles for removing carbon and tar. Fuel, a oxygen and steam are introduced through a nozzle 1, the complete combustion of the fuel taking place in a combustion chamber 5 which is protected by insulating material 2. The hydrocarbon feedstock is introduced into the combustion gas via a nozzle 4 and the hydrocarbons are thermally cracked in the cracking zone 5 because thermally cracked gas is; continuously fed to a Venturi raw material (quenching device), which is located directly at the exit of the cracking zone.

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closes} · υπ to quench the high temperature cracked gas, a cooling liquid is sprayed from spray openings 8 which surround the mouth section 7 of the venturi tube _f with the aid of a suitable device, for example a pump (not shown); which is contained in a Vorratskanmer 6. The cracked gas in your mouth section 7 and in the diverging pipe section 9, cooled to a predetermined temperature, is separated from the cooling liquid in a combustion chamber 10 and from there via a line 11 to the subsequent

· ■ passed the final cleaning stage. For removing foreign matter such as carbon and tar automatically or manually uadein 12, which are provided in the spray ports, intermittently.

inserted into the spray openings.

The I ^i! ig ₀ 2 and 3 show modified embodiments of the quenching device according to Pig, 1. Instead of the Venturi tube described above, the embodiment according to Mg. 2 uses a modified Venturi tube, which consists of a short cylinder and a diverging tube, while the Embodiment according to Pig. 3 only uses a diverging tube. · The same reference symbols denote the same ropes in the figures.

The Pig. 4 shows the details of those who use blame Cleaning device, »-and zv / ar shows the reference symbol 13 a needle that has a shoulder at its distal end, which serves as a stopper? 14 is one seal. The Hadel 13

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moves vertically back and forth in the direction of the arrows with the aid of a suitable needle drive (not shown). The reference numeral 15 is the mouth portion 16 during the Xühlflüssigkeits-Yorratskanmer designated.

■ .In An example of the application by -the invention results obtained will be given. So the deterrent became compliant. 2 was used, the cooling liquid being water. '

Quenching Conditions: Spray Orifice

Temperature of the thermally cracked gas from the Cracking zone

Flow rate of the cracked gas

Speed of the gas ■ s tr cms at the mouth of the mouth spray pressure of the water sprayed water eyes

Temperature, on. which the cracked gas was cooled

Temperature of the water supplied.

Amount of 3 supplied Water

2 mm ! Durchaeas-er

'each 4 (one. level)

950 to TOO (TC 64-0 to 650 mV (HTormal conditions) 80 to 85 m / sec.

2 kg / cm ²

750 to 800 l / h 160 to 170 ⁰ C.

up to 92 ⁰ C

400 to 420 1 / h

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If the needles were inserted once every four hours, so could Äfcine accumulation at the mouthpiece and diverging section of carbon and tar can still be found. was there any contamination of the spray openings at all ' even after continuous operation for 340 'hours. Any- "which no other irregularities could be found either. The yields of acetylene and ethylene were 26 or «, 27% by weight based on Haphta,

On the other hand, when the needles were not inserted, 2 out of 4 spray orifices clogged and there was a significant build-up of carbon and tar on the mouth portion after its 72 hours of operation. Accordingly, the pressure of the thermal cracking apparatus increased, 'increased the efficiency of the cooling, and the temperature rose, · on the hot cracked gas was cooled to 230 to JOO ⁰ O. The yield of acetylene and ethylene on the basis of naphtha took to 23 or 24 wt .- ^ from _o

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Claims (6)

Claims 1) A method of quenching a high temperature cracked gas which has been produced by thermal cracking of hydrocarbons, characterized in that the cracked gas is continuously passed from a thermal cracking zone to a passage that has a stream of cracked gas a set of spray openings arranged in the vicinity of the inlet of this passage, a cooling liquid is continuously sprayed and that, in order to remove carbon and tar that have accumulated in the spray openings, threads are intermittently inserted into these spray openings before the _above 2) Device for carrying out the method according to claim 1, characterized by a passage (7, 9) provided for transferring the cracked gas from the thermal cracking zone (5) to a gas-as-liquid separating zone (10): I which near its entrance has sets of spray openings (8) for the continuous injection of a cooling liquid across the stream of the cracked gas, and that in order to remove the carbon or air that has accumulated in the spray openings needles ( 12; 13) are provided, which can be inserted intermittently into the spray openings _c '. / 8AD 3) device according to claim 2, characterized in that that the passage (7 »9) is a Ventura tube. 4) Device according to claim 2, characterized in that the passage (7 _t 9) is a tube of Einein short cylinder (7) and a diverging tube section (9). 5) Device according to claim 2, characterized in that that the passage (9) iet a diverging tube. 6) Device according to claim 2, characterized in that that the passage (9) is a straight tube. 209810/1789 ÖAD ORJGJMAl