Improvements in the vapour-phase cracking of hydrocarbons

摘要

In the vapour phase cracking of hydrocarbons, the cracked products are quenched in a zone maintained at constant temperature and the quenched products transferred to a flashing zone, a rapid swirling motion being imparted to the products during the transfer to prevent deposition of carbon in the transfer pipe. The process is stated to be applicable to the cracking of C2, C3 and C4 saturated hydrocarbons to unsaturated products, e.g. at temperatures of 1350 DEG to 1550 DEG F., but as shown a liquid charge 1 is taken to an intermediate part of column 4 where it serves as reflux and is preheated, bottoms from the column being taken to a vaporizing coil 8 and thence to an evaporator 11 from which vapours go to a cracking coil 15. For vapour charges the evaporator is omitted. Cracked vapours are quenched in chamber 17 to about 600 DEG F. by an oil spray obtained from a side stream from column 4, the quantity of quenching oil being controlled by the temperature in chamber 17. The quenched products pass via line 31 to flash tower 34, a helical vane 32 being disposed in the line 31 to impart a swirling motion to the products. Vapours from tower 34 are fractionated in column 4. To assist vaporization steam may be admitted to evaporator 11, flash tower 34 and column 4.ALSO: In the vapour-phase cracking of hydrocarbons, the cracked products are quenched in a zone maintained at constant temperature and the quenched products transferred to a flashing zone, a rapid swirling motion being imparted to the products during the transfer to prevent deposition of carbon in the transfer pipe. As shown, a liquid charge 1 is taken to an intermediate part of a column 4 where it serves as reflux and is preheated, bottoms from the column being taken to a vaporizing coil 8 and thence to an evaporator 11 from which vapours go to the cracking coil 15. Cracked products are quenched in chamber 17 by an oil spray obtained from a side stream from column 4. Insufficient oil for quenching is passed directly via valve 23, the balance passing via valve 26 which is periodically opened and closed by an electro-magnetic device 30 in accordance with the temperature in the chamber 17. The quenched products pass via line 31 to flash tower 34, a helical vane 32 being disposed in the line 31 to impart a swirling motion to the products. The products from flash tower 34 are fractionated in column 4. To assist vaporization steam may be admitted to evaporator 11, flash tower 34 and column 4. For gasoline the cracking temperature should be in excess of 1,100 DEG F., e.g. from 1,250 DEG F. to 1,350 DEG F. and the temperature in the quenching chamber maintained about 600 DEG F. It is stated that the invention may be used in the cracking of C2, C3 and C4 saturated hydrocarbons to unsaturated hydrocarbons useful in organic syntheses, using a cracking temperature of 1,350 DEG F. to 1,550 DEG F.