Patent GB-500201-A (GB)
Title: Improvements in or relating to the recovery of stabilised gasoline from vapours produced in cracking hydrocarbons
IPC: C10G7/02
Filed: 1937-08-03
Abstract: 500,201. Cracking and distilling oils. TENCH, F. (Gulf Oil Corporation) Aug. 3 1937, No. 21390. [Class 32] Stabilized motor fuel is recovered from a mixture of vapours of gasoline boiling point range and gases, e.g. the products obtained by cracking oils after separation of products having a higher boiling point than gasoline, by scrubbing the mixture under high pressure with cool unstabilized condensate, cooling a portion of the condensate thus produced and using it as the scrubbing medium, separately rectifying and stabilizing the remaining condensate, delivering the vapours thus liberated to the scrubbing zone, and separately withdrawing stabilized condensate and vapours from the system. A mixture comprising vaporized gasoline and gaseous hydrocarbons and gases is introduced through a pipe 1 into a fractionating column 2 superposed on a stabilizing column 6, the columns being provided with bubble plates and connected by a vapour line 8 as shown in Fig. 2. Unstabilized condensate is collected on the bottom plate 7 of the column 2 and divided into two portions. One portion is led off through the pipe 11 and after cooling in a heat exchanger 16 is recirculated through a line 4 to the top of the column as absorption and cooling medium. The other portion is passed through a pipe 9 into the column 6 where it is stabilized by withdrawal to a re-boiler 20 from which vapours are returned to the column through a pipe 23, the stabilized gasoline being withdrawn through a line 24 and heat exchanger 28, 31 to storage. Additional reflux for the columns may be provided (1) by introducing naphtha through a line 5, (2) by withdrawing a part of the re-cycled condensate from the line 14 and passing it through a line 26, 29 into the top of the column 6. Fixed gases are withdrawn from the top of the column 2 through a line 25. The columns are maintained under a pressure of about 200- 300 lb. per sq. in. In operating the process in conjunction with a cracking plant; Fig. 3, comprising a tubular cracking furnace 31, a separator 32, fractionator 33, combined stabilizer and fractionator 34 of the type described, and absorption tower 35, crude oil, e.g. naphtha or gas oil is fed through lines 60, 61 into the top of the absorption tower 35 and flowing downwardly therethrough absorbs the gaseous hydrocarbons of 3 to 4 carbon atoms per molecule from the gases released from the tower 34. The enriched oil passes to an accumulator 36 from which it is fed through line 66 and heat exchanger 38 into the tubular cracking furnace 31, the cracked products being immediately quenched by cool oil fed through a line 67, and then passed through the heat exchanger 38 into the separator 32. The vapours evolved are freed from tar &c. with the aid of reflux introduced by a pipe 71 and then pass through a line 72 into the column 33, while tarry residues are withdrawn through lines 49 and cooler 48 from .the system, provision for re-circulation being provided by a pump 43 and line 50. Fractionating conditions in the tower 33 are controlled by re-circulation of reflux through the lines 51, 52, and by introduction of fresh reflux through a line 76 so that gasoline vapours and constituents of lower boiling point pass off through the line 1 for stabilizing as described above while higher-boiling fractions are condensed and removed through lines 73, 74, the condensate being passed through a heat exchanger 20 where it is utilized to re-boil and stabilize, the gasoline from the tower 6. The condensate is then passed through a cooler 39 after which it is divided and passed (1) in part as quenching stock to the line 67, (2) through lines 71, 76 as refluxing medium, (3) through line 77 out of the system. Gases escaping from the tower 2 pass through a line 25 into the tower 35, extraneous gases being added through a line 80 if desired.