US1860966A - Process and apparatus for cracking hydrocarbons - Google Patents

Description

y 31, H. SYDNOR 1,860,966

PROCESS AND'APPARATUS F OR CRACKING HYDROCARBQNS Filed Sept. 21, 1928 2 Sheets-Sheet 1 BUBBLE To m2 awwmtoz HAROLD svonok M y 1932- H. SYDNOR 1,860,966

A PROCESS AND APPARATUS FOR CRACKING HYDROCARBONS Filed Sept. 21. 1928 2 Sheets-Sheet 2 BUBBLE TowER LSOAKING DRUM OOOOOGOOOOOOOOOOOOO El STEELBILLET hawk NR6 Lu Byon OR anoawcoz Patented May 31 19.32

HAROLD SYDNOR, OF ELIZABETH, NEW JERSEY, ASSIGNOR TO STANDARD OIL UNITED STATES PATENT OFFICE DEVELOP- MEN! COMPANY, A CORPORATION OF DELAWARE raocnss AND arranarus FOR czaaqxme' nynnooannons Application filed September 21, 1928. Serial No. 307,875.

This invention relates to the art of treating hydrocarbon material, more particularly to the cracking of heavy hydrocarbons to obtain lighter hydrocarbons for use as motor fuel and the like. The invention will be fully understood from the following description, read in conjunction with the accompanying drawings, wherein Fig.1 is a. vertical embodiment of my invention, and,

1 Fig. 2 is a vertical section of a modified form of the apparatus.

Referring to Fig. 1, hydrocarbon material to be cracked, gas oil for instance, is drawn from a source of supply (not shown) by a pipe 1 and heated under pressure to at least partial vaporization preferably of the coil type. The heated oil, which may be-largely or wholly in the form of vapor, is now passed thru pipe 3, provided with valve 311', and thru a highly heated metal billet 4, positioned as shown in a furnace 16 which maybe of conventional type and provided with a burner 17 and bridge wall 17a. The billet 4 is provided with holes 4a drilled longitudinally therethru and connected at each, end to provide a continuous passage of considerable length. Hot vapors issuing from the secondary heater 4 pass by pipe 5, provided with valve 6, to an enlarged zone 7, commonly known .as a. soaking drum or reaction chamber, wherein the velocity of their travel -'is greatly reduced and final cracking takes place.

Crackedproducts from the soaking drum pass by pipe 9, provided with a valve 8, to suitable fractionating' means represented in the drawings at 10 as a bubble tower equipped with the usual vapor line 11, cooling coil 12, reflux-line 13'for returning cycle stock by way of pump 18 and pipe 19 to the feed. line 1, drawofi line 1 4, and bubbling plates 15.

Y but steel slabs secured together may be used.

'I have found that the provision of a tubular heater such as billet 4 is of great advantage, especially in vapor phase cracking.

The billet is preferably a solid steel forging, Corrosion resisting steels or other alloys are sometimes desirable. The'wa-lls of the passagas thru the billet may be of any desired section of a preferred in a primary heater 2,-

thickness, preferably at least one inch. These walls, greatly thickened, as compared with ordinary tube walls, may be heated to high temperatures without localized overheating, and with resultanteven distribution of heat. Their greater strength also permits subjecting the oil to much higher pressures than are possible with the usual equipment.

For example, a forged steel billet six inches Wide, seven feet long and eight feet seven inches high is well adapted for my purposes. Through this billet twenty holes two and one half inches in diameter are drilled longi tudinally and nipples are rolled in at the end of each hole. Return bend connections are in turn rolled into the nipples to produce in the billet a single bank of connected tubes having a total length of 220 feet- The following example is illustrative of the invention.

A gas oil fraction is heated to at least partial vaporization in the primary heater 2 and the vapors, having a temperature at the outlet of primary heater 2 of approximately 0-800 F., and a sq. in. are passed through the conduit formed in the billet 4 at a velocity of approximately 37 feet per second. It will be understood in this connection that the material under treatment is exposed to the higher temperature for i a very short period of time, 1. e. 3 seconds to 15 seconds, but preferably about six seconds, whereby substantial cracking'in the secondary heater is prevented. In some cases, "however,

pressureof 350 lbs. per. 1

ondary heater is greatly reduced or prevented while at the same time a'much higher feed rate may be maintained thru the heating zone for the same drop in pressure because of v of the material inthe systhe greater density tem. At this velocity substantially no depositionof carbon occurs in the billet and the process may be made continuous until such time as the accumulation, of carbon in the complete vaporization proximately 900-1000 and wherein corresponding parts are ind1- soaking drum necessitates the discontinuance of the run. By the use of alternate soaking drums whereby the products from the crackinlg zone 4 may be discharged into one drum w ile the other is being cleaned, it is ossible to operate my process continuously or very long runs. 1 he vapors, heated in the billet 4 toap- F., are discharged into the upper portion of a. thermally insulated soaking drum 7 which may be of the type used in the tube and tank cracking process. The velocity is greatly reduced in the soaking drum, whereby final cracking of the hydrocarbon material is efiected and free carbon is permitted to settle out before the cracked products pass from the soaking drum to the fractionating equipment.

If desired, a valve 3a may be provided in the line 3, whereby a pressure may be maintained inthe billet 4 slightly lower than the pressure carried in the primary For instance, I may carrya pressure of 1000- 1500 pounds per square inch in the primary heater and a pressure of 950-1400 pounds per square inch in the billet so as to insure more of the material being treated in the billet. Alternatively a pump (not shown) may be provided in the line 3 in case it is desired to carry comparatively low pressures in the primary heater 2, for the purpose of maintaining the desired pressure in the billet 4. I may likewise maintain further successive decreased pressure zones in the soaking drum 7 and fractionating means 10 by means of valves 6 and 8. I have operated my process under a single pressure thruout the apparatus, although I prefer to release a part of the rcssure in the bubble tower by means of va ve 8 so as to facilitate separation of the constituents of the cracked products therein.

It may also be desirable at times to discharge the heated products directly from the secondary heating zone into the fraetionat ing means, particularly, when reflux condensate is being returned to the feed line.

Referring to Fig. 2, which represents a bed modification of the apparatus above descri catedby prime numerals, 2', and the billet 4' are positioned in a single furnace setting. In this modification, it will be seen that-the billet 4 is heated by direct contact with the combustion gases from the burner 17 and that these partially spent combustion gases then pass around the tubes comprising the primary heater 2' to heat the latter.

\Vhile in the form of apparatus herein the preheating coil shown the reflux condensate or cycle stock is returned from the tower 10 to the feed line 1 by way of pump 18' and line 19 it will of ceuise be understood that suitable connections (not shown) may be provided for passing heater 2.

, the cracked product.

this stock to storage or other suitable place of disposal when it is desired to subject the oil under treatment to but a single pass thru the apparatus.

It willbe understood also that the appa ratus described is but one form which my invention may take and that other forms and modifications are contemplated which come within the spirit and scope of the invention.

I claim:

1. The method of cracking hydrocarbon material, which comprises heating said bydrocarbon material porization, passing such heated material thru a secondary heating zone, under conditions such that it is exposed toa temperature of at least 1000 F. and a pressure of at least 1500 pounds per square inch for aperiod not exceeding six seconds, and separating the lighter from the heavier constituents.

2. Apparatus for cracking hydrocarbon material, comprising a primary heater, means for supplying hydrocarbon material to said primary heater, a secondary heater communicating with said primary heater and comprising a solid metal bi let having unlined bore holes therethrough, said here holes being connected at their respective ends to form a single continuous passage thru said billet, an enlargedreceive material passing thru said secondary heatin means, and fractionating means connected to receive material from said enlarged zone.

3. Apparatus for cracking hydrocarbon material, comprising a primary heater, means for supplying hydrocarbon material thereto, a secondary heater connected to receive heated material from said primary heater, said secondary heater comprising a solid metal billet having unlined bore holes, said bore holes being connected to form a single continuous passage thru said billet, and fractionating means connected to receive said hydrocarbon material after its passage thru said secondary heater.

4. -Method of cracking hydrocarbon oil substantially in vapor phase, under pressure of 950-1400 pounds per square inch, which vcomprises heating the oil under pressure to a temperature at which it vaporizes at least in part, passing the oil at increased velocity and in substantially the vapor phase through a zone in which it is cracked by heat uniformly distributed through a massive metallic body, the velocity of flow said body being so great that the oil passes therethru in 3 ,to 15 seconds, and collecting HAROLD SYDNOR.

reaction zone adapted to in contact with to at least partial va-

Images