US1847258A - Process and apparatus for cracking hydrocarbon gases - Google Patents

Description

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March 1932- G. G OBERFELL ET AL PROCESS AND APPARATUS FOR CRACKING HYDROCARBON GASES Filed May 24, 1928 3 NH. 0 m u a u n w w m a w mm WW INVENTOR 9 L. A13, W l l LFL ATTORNEY '7 Patented Mar. 1, 1932 UNITED STATES- PATENT OFFICE GEORGE G. OBERFELL AND FREDERICK E. FBEY, OF BABTLESVHILE, OKLAHOMA, AS-

SIGNOBS TO PHILLIPS PETROLEUM. COMPANY, OF BAB'I'LESVILLE, OKLAHOHA, A

CORPORATION OF DELAWARE PBOCISSAND APPARATUS FOR CRACKING HYDROCABBON GASES Application filed m 24, 1928. Serial m). 280,832.

This invention relates to a process and apparatus a view of reforming said gases and producing as a by-product substantial quantities of li uid hydrocarbons of the character of hen- It has heretofore been proposed to subject hydrocarbons such as occur in natural gas to suitable temperature conditions and at such velocity as to reform some of the hydrocarbons and convert some of the hydrocarbons into liquid hydrocarbons. In such systems the gases are heated directly or indirectly by products of combustion, and tion the resulting gases and liquids are separated and the liquids are recovered and utilized independently of the gases.

Proposals have also been made regarding the recycling of the resulting gases through the reaction steps of the process with a view of converting an additional amount of said resulting gases into liquid hydrocarbons, and thereby augmenting the quantity of liquid hydrocarbons obtained as by-products of the procedure.

The present process differs from the precedin recycling processes in that the recycle gas and raw gas are not mixed while cold and then treated but the gases are heated separately; the raw gas to a temperature near the treating temperature and the recycled gas temperature,

to a temperature higher than the treating and then mixed. In this case the treated or recycled gas acts as a heating medium for the raw gas.

As the raw gas is not heated to a reaction temperature in the heating tubes, no reaction takes place until the two gases are mixed in the reaction chamber. This prevents the formation of tar and carbon in the heating tubes, and results in a greater yield of benzol and less expense for cleaning and replacing tubes.

In this process a portion of the treated gas that has been stripped of its benzol, is recycled to a furnace where it is heated to a temperature above the desired treating temperature of the raw gas, and then this superheated reformed gas is used to heat the raw gas upto the treating temperature.

This process includes the coo ng, purifyfor cracking hydrocarbon gases with.

after the reacline (8) ing, and stripping of the treated gas of henzol; the returning of a gaseous portion to a furnace where it is heated to a temperature above the treating temperature; and then the mixing of this portion with raw gas which has been preheated in separate heating tubes to a temperature lower than the treating temperature. The two gases are mixed in a reaction chamber, the volume and temperatureof each gas being controlled so that the resulting mixture is at the desired treating temperature for a proper time period.

The recycled treated gas may atemperature at which it acts as an mert heating medium or it may be heated to such a temperature fore serving as a heating medium for the raw gas.

The invention is practiced in an apparatus of the type diagrammatically illustrated in the accompanying drawing, which shows a side elevation of the apparatus.

The apparatus shown in the drawing consists of furnace (A), reaction chamber (B), recuperator and tar collector (C), tar scrubber and gas cooler (D), tar catch (E), gas pump (1) condensate collector (G) oil wash tower extraction plant (I), recuperator (J) of furnace (A) recuperator (K) and tar collector (L) of recuperator and tar collector (C).

The flow of gases lows: The raw gas in the process is as folto be treated enters at (1), metered by (2), and passed through line (3) to reducing regulator (4). The gases under a constant reduced pressure pass through gate (a) to distributing header (5) and through gate (6) to tubes (6), where the temperature of the gases is raised considerably. The gases leave tubes 6) through gate (0) are collected in header and pass into line (9). If it is found that the gases may be raised to the desired temperature farther on in the system, gate (6) and gate (0) may be closed and gate ((1), which is a bypass on tubes (6), opened, allowing the gases to pass directly from gate (a) through gate (d) and into line (9). The gases pass from line (9) through gate (e) on to that it is further reformed be-- be heated to where they enter recuperator and where the temperature of the raw gases is raised to just the point below reformation.

The gases leave recuperator (K) at (11) pass through line (12) gate (f) and enter reaction chamber (B) at (13). If the temperature of the gases is raised to the desired temperature in tubes (6), gates (e) and may be closed and gate (g) opened, allowing the gases to flow directly through bypass (14) from tubes (6) to reaction chamber (B). The gases entering reaction chamber (B) at (13) at just below reforming temperature, are mixed with a sutlicient amount of superheated gases entering at (51) to raise the gases to a sufficient temperature to cause them to reform. The reformed gases leave reaction chamber (B) at (15), pass through gate (12.) into recuperator (K) at (16) and are partially cooled by the flow of raw gases in (K) as previously described. The gases leave (K) at (17) enter tar collector (L) where the heavier tar is collected and the uncondensed gases pass from (L) at (18) through gate into gas cooler (D) at (20). If recuperator (K) is not used the hot gases may pass from (15) through bypass (19) into (D) at (20), gates (h) and (i) being closed and bypass gate (7') being open. The gases passing through (D) are cooled, by water sprays (62) supplied by source (61), and the tar-is condensed and collects in the bottom of (D) where it is drawn off with the water through level control valve at The gases pass from (D) at (21) into tar catch (E) at (23) through (22) and then through (24) to compressor (F) at (25) where the gases are com pressed and forced through gate (7:) line (27) from (26) into condensate collector (G) at (28), the condensate being periodically drawn off through (71). The cooled reformed gases under pressure free from any condensate pass from condensate collector (G) at (29) through line (30) into oil wash tower (H) at (31) and as the gases pass up through the column counter current to wash oil, are sprayed at (69), the lower boiling constituents are absorbed by the oil which collects at the bottom of (H) and is auto matically trapped through level control ,valve and from oil wash tower at (63)to recovery plant (I) at (64). The wash oil free from constituents of the gases of tower H passes from recovery plant (I) at (65) through automatic differential control meter (67) then through line (68) to oil spray (69) where the oil completes the cycle.

The gases free from heavier constituents pass from oil wash tower (H) at where the major portion is released through back pressure control regulator from line (33) to gas mains at (35). A smaller portion of the gas passes through gate (1) line (36), meter (37), gate (122.), line (38), reducing regulator (39) and line (40) into stack gas recuperator (J) where the temperature of the gas is raised somewhat. The gases pass from recuperator (J), line (42) distributing header (43), gate (n) into tubes (44) where the temperature is raised considerably more. The gases pass from tubes (44) at (45) and pass at (46) into furnace area (47) where the gases reach a very high temperature. The gases pass from furnace (47) at (48) through gate (0) into collection header (49) through line (50), entering the reaction chamber (B) at (51) and supplying the preheated raw gases with sufliciently high temperature to cause their reformation.

The fuel for furnace (A) is supplied at (52), metered at (53), controlled at gate (12), distributed by header (54), passes through minor contro gates (q) and enters combustion chambers (59) through burners (58).

The air to support combustion is supplied at the desired positive pressure by a steam driven positive blower (55) metered at ('56), passes through recuperator (57), and enters combustion chambers (59) through burners (58).

The hot products of combustion pass from combustion chambers (59) into combustion tunnel (60), upthrough a perforated arch into furnace (47 through another perfo-' The temperature prevailing in the reaction chamber should be such as to reform some ofthe gases and convert some of the same into a substantial amount of liquid hydrocarbons. This temperature will fall in a range from 1250 F. to 1750 F. and the higher the temperature used the faster should be the passage of the gases treated through the reaction chamber. The exposure time in the reaction chamber for the reaction products will be within a range of 0.002 minutes to 10 minutes.

It has been discovered that the precise way, and rate, at which heat is communicated to the gases under treatment greatly affects the efficiency of the process, and an important feature of the invention consists in keeping the temperature of the raw gases at, or slightly below the temperature of reaction until they are introduced in the reaction chamber itself. This is accomplished by raising the raw gaws to approximately the temperature of reaction outside the chamber and that of the recycled gases to the necessary degree of super-heat to establish a correct common temperature of reaction when the two are combined in the reaction chamber as explained.

)Vhile a preferred embodiment of the invention has been disclosed, it will be apparent to those familiar with such processes and paratus that changes may be made in details disclosed without departing from the spirit of the invention as set forth in the claims.

What is claimed and desired to be secured by Letters Patent is:

. thereby raising 1. In a process for the pyrolytic conversion of normally gaseous aliphatic hydrocarbons to crude benzol, continuousl passing said gaseous hydrocarbons throug an elongated passageway of restricted cross-sectional area while heating the same to a temperature just below the conversion temperature of said then passing the gaseous hydrocarbons,

hydrocarbonsthrough an enheated gaseous larged zone of greater cross sectional area than said passageway, passing previously treated residual gas through a second elongated passageway of restricted cross-sectional area while continuously heating the second passageway. to a temperature greater than said conversion temperature, commingling in said zone said gaseous aliphatic hydrocarbons with the residual gas discharged from the second passageway and the temperature of the hot gaseous aliphatic hydrocarbons to a conversion temperature between 1250 and 1750 F., and then separating the crude benzol so produced. r

2. An apparatus for cracking normally gaseous aliphatic hydrocarbons, with separation and collection of condensates and residual gas, presenting the combination of a heating furnace provlded with independent sets of heating tubes, one for raw gas and another for retreating residual gas, a reaction chamber, means for introducing both the heated gases into the reaction chamber, means for withdrawing the treated mixture from the reaction chamber and means for separating the liquids and gases formedin the reaction chamber with provisions for conducting a residue of the gases formed to be retreated into the one of said independent tube sets for retreating residual gas.

- GEORGE G. OBERFELL.

FREDERICK E. FREY.

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