GB777459A - Improvements in or relating to hydrocarbon reforming with platinum catalyst and regeneration system therefor - Google Patents

Abstract

Apparatus for regenerative platinum catalyst naphtha hydro-forming comprises reactors 20, 25, 30, 36, heaters 12, 22, 27 and product separator 33, the valves and pipes connecting the reactors and heaters being arranged so that the catalyst in any one reactor may be regenerated while the feed passes in series through the other reactors. Hydroforming takes place at 100-350 p.s.i.g. pressure. The temperature increases slightly from the first to the third reactor and the pressure decreases slightly. The catalyst is regenerated at below 1200 DEG F. with flue gas containing a small amount of oxygen, and is then treated with gas of higher oxygen partial pressure. Naphtha feed is introduced at 11, vaporized and heated at 12, mixed with recycle hydrogen from line 16 and heater 17, and passed through lines 18, 19 to reactor 20 containing platinum on alumina catalyst which has been preheated by the passage of hot hydrocarbon and/or hydrogen. Conversion takes place at a pressure of about 200 p.s.i.g. and a temperature of about 980 DEG F. The partly converted feed passes through line 21 to heater 22 and then flows through lines 23, 24 to second reactor 25, and similarly through <PICT:0777459/IV(b)/1> heater 27 and third reactor 30. The product is withdrawn through lines 31, 32 to gas separation and fractionation system 33. When the catalyst in reactor 20 declines in activity, it is purged free from hydrocarbons by introducing hydrogen through lines 38, 39, and this reactor is replaced by reactor 36 by adjustment of valves. The regeneration and rejuvenation system comprises upper and lower pipes 46, 51 having valved branches to each of the reactors. Flue gas generator 59 is supplied with compressed air through line 58 or 60 and with compressed fuel gas from 62. In starting up, air enters through line 60 and flue gas is circulated through water cooler 64 (used for the production of steam at 68) until the required pressure (about 220 p.s.i.g.) is reached. The flue gas is then led through line 71, three-way valve 72 and lines 73, 46 to the top of the reactor to be regenerated; the flue gas purges hydrogen from the catalyst and is withdrawn through lines 51, 74, three-way valve 75, and lines 76, 77, 78, via pressure regulating valve 78a; some of the flue gas may circulate through valve 77a and compressor 69 instead of through line 63. In order to burn off carbonaceous deposits from the catalyst, a small amount of air is introduced through line 58 to provide about 2 per cent oxygen in the circulating flue gas which is at a temperature of 700-850 DEG F. The oxygen partial pressure of the circulating gas is then raised to at least 0.4 atmosphere and the temperature to 950-1200 DEG F. by increasing the fuel gas and air feed to the vessel 59; depending on the degree of deactivation of the catalyst, this treatment may take from 5 minutes to 24 hours. After rejuvenation the catalyst is purged from oxygen by discontinuing the introduction of air at 58 and 60 and passing cooled flue gas through the bed, reducing the temperature to that required for conversion. During the removal of oxygen, the direction of gas flow may be reversed by adjustment of the three-way valves 72, 75. The catalyst is next treated with hydrogen to remove flue gas before re-use in the process. The purging steps may take place at lower pressure by by-passing the regulating valve 78a via line 81. A separate air heater may be provided for heating the rejuvenation gas. The process may include the following features: (a) removal of catalyst fines from gas leaving the reactors by means of cyclone separators or filters; (b) introducing a feed which does not require the full treatment into the heater 22 or 27; (c) fractionation or purification of the feed to remove water, hydrogen sulphide, or high boiling components. Specification 748,777 is referred to.ALSO:<PICT:0777459/III/1> Apparatus for regenerative platinum catalyst naphtha hydro-forming comprises reactors 20, 25, 30, 36, heaters 12, 22, 27, and product separator 33, the valves and pipes connecting the reactors and heaters being arranged so that the catalyst in any one reactor may be regenerated while the feed passes in series through the other reactors. Hydroforming takes place at 100-350 p.s.i.g. pressure. The temperature increases slightly from the first to the third reactor and the pressure decreases slightly. The catalyst is regenerated at below 1200 DEG F. with flue gas containing a small amount of oxygen, and is then treated with gas of higher oxygen partial pressure. Naphtha feed is introduced at 11, vaporized and heated at 12, mixed with recycle hydrogen from line 16 and heater 17, and passed through lines 18, 19 to reactor 20 containing platinum on alumina catalyst which has been preheated by the passage of hot hydrocarbon and/or hydrogen. Conversion takes place at a pressure of about 200 p.s.i.g. and a temperature of about 980 DEG F. The partly converted feed passes through line 21 to heater 22 and then flows through lines 23, 24 to second reactor 25, and similarly through heater 27 and third reactor 30. The product is withdrawn through lines 31, 32 to gas separation and fractionation system 33. When the catalyst in reactor 20 declines in activity, it is purged free from hydrocarbons by introducing hydrogen through lines 38, 39, and this reactor is replaced by reactor 36 by adjustment of valves. The regeneration and rejuvenation system comprises upper and lower pipes 46, 51 having valved branches to each of the reactors. Flue gas generator 59 is supplied with compressed air through line 58 or 60 and with compressed fuel gas from 62. In starting up, air enters through line 60 and flue gas is circulated through water cooler 64 (used for the production of steam at 68) until the required pressure (about 220 p.s.i.g.) is reached. The flue gas is then led through line 71, three way valve 72 and lines 73, 46 to the top of the reactor to be regenerated; the flue gas purges hydrogen from the catalyst and is withdrawn through lines 51, 74, three way valve 75, and lines 76, 77, 78 via pressure regulating valve 78a; some of the flue gas may circulate through valve 77a and compressor 69 instead of through line 63. In order to burn off carbonaceous deposits from the catalyst, a small amount of air is introduced through line 58 to provide about 2 per cent oxygen in the circulating flue gas which is at a temperature of 700-850 DEG F. The oxygen partial pressure of the circulating gas is then raised to at least 0.4 atmosphere and the temperature to 950 DEG -1200 DEG F. by increasing the fuel gas and air feed to the vessel 59; depending on the degree of deactivation of the catalyst, this treatment may take from 5 minutes to 24 hours. After rejuvenation the catalyst is purged from oxygen by discontinuing the introduction of air at 58 and 60 and passed cooled flue gas through the bed, reducing the temperature to that required for conversion. During the removal of oxygen, the direction of gas flow may be reversed by adjustment of the three way valves 72, 75. The catalyst is next treated with hydrogen to remove flue gas before re-use in the process. The purging steps may take place at lower pressure by by-passing the regulating valve 78a via line 81. A separate air heater may be provided for heating the rejuvenation gas. The process may include the following features:- (a) removal of catalyst fines from gas leaving the reactors by means of cyclone separators or filters; (b) introducing a feed which does not require the full treatment into the heater 22 or 27; (c) fractionation or purification of the feed to remove water, hydrogen sulphide, or high boiling components. Specification 748,777 is referred to.