US2007226A - Hydrogenation of hydrocarbons - Google Patents

Description

Patented July 9, 1935 HYDROGENATION F HYDROCARBONS Antoni Szayna, Lwow, Poland, assignor to Sinclair Refining Company, New York, N. Y., a corporation of Maine Application June 6, 1931, Serial No. 542,581 Renewed May 7, 1935 2 Claims.

This invention relates to improvements in the manufacture of lower boiling oils such as gasoline by cracking and hydrogenating higher boiling oils, such as kerosene and gas oil and heavier oil,

5 without a. catalyst.

When higher boiling oils are heated to a cracking temperature the products of the consequent reaction include hydrocarbons relatively poor in hydrogen which tend to polymerize to form "coke or solid or semisolid pitches. The presence of hydrogen in concentration suiiicient to exert more than a characteristic minimum partial pressure tends to inhibit such polymerization and formation of coke and pitches. To be eiective in this respect, however, it is not suiiicient that the hydrogen be generally present in the region of reaction. It must be immediately present, with respect both to time and to place, as the constituent molecules of the higherboiling oil decompose or crack. For this reason the uniform progress of the combined reaction depends to an important extent upon the maintenance throughout the region of reaction of a continuously uniform intimate mixture or dispersion of the hydrogen in the oil.

'I'he conventional apparatus for supplying higher boiling oil and hydrogen to such operations includes, because of the high pressures usually employed, pumps or compressors of reciprocating type. Even though extreme mechanical precautions be taken, there is an ever present tendency toward the development of successive fluctuations in the momentary hydrogen concentration in a composite stream formed by merging the discharge, for example, of an oil stream from such a pump and a hydrogen stream from such a compressor. Thus, even though there be suflicient hydrogen in the system generally to avoid the formation of coke or pitches, coke or pitches will frequently form in a system so operated because the cracking of the oil proceeds irrespective of the hydrogen concentration with consequent polymerization and formation of coke or pitches wherever the hydrogen concentration is deficient. Operating without a catalyst, such coke or pitches do not react to produce desirable products but are either deposited in the system or discharged from the system as coke or pitch.

According to the present invention higher boiling oil and hydrogen are forced to the heating zone, in which the combined cracking and hydrogenating operations proper are carried out, a heating coil arranged in a heating furnace for example, through a receptacle adapted to contain a substantial body of a mixture of the two and a substantial body of the mixture is maintained in this receptacle. 'I'his body of the mixture is maintained at a temperature below that at which substantial cracking of the oil begins and eiective dispersion of the hydrogen in the oil is maintained throughout this body. This receptacle advantageously is proportioned to contain a volume of the mixture exceeding, best several times, the single stroke displacement of any reciprocating hydrogen compressor used plus the volume of oil corresponding on the basis of the proportions of the average mixture supplied to the heating zone. This receptacle through which the mixture passes from the forcing means to the heating zone, in accordance with the invention, thus constitutes a reservoir in which momentary variations of hydrogen concentration are reduced to a Since the oil is maintained at a temperature below that at which substantial cracking begins in this receptacle, momentary variations in the hydrogen concentration are reduced to a minimum before cracking of the oil begins. The mixture of higher boiling oil and hydrogen supplied to the heating zone from this receptacle is not only intimate but also continuously uniform, or very nearly so, so that optimum conditions with respect to hydrogen concentration and dispersion are maintained from a temperature below that at which substantial cracking of the oil begins. Due to the maintenance of these optimum conditions, the combined cracking and hydrogenating operation may be carried out under somewhat lower pressures.

The invention provides for the production of a maximum of gasoline with the formation of but a minimum, if any, of coke or pitches and for the most effective use of the hydrogen supplied to the operation, without a catalyst.

The accompanying drawing illustrates, diagrammatically and conventionally, one form of apparatus adapted for carrying out the process of the invention, Fig. 1 being an elevation partly in section and with parts broken away and Fig. 2 being a fragmentary section facing the small end of receptacle 8.

The apparatus illustrated comprises a pump I and a compressor 2 for supplying oil and hydrogen, respectively, to the heating coil 3 arranged in the heating furnace 4 through a receptacle 8. In the apparatus illustrated the products of the cracking and hydrogenating operation carried out in the heating coil 3 are discharged through the cooling coil 5 to the separator 6. To prolong the period of time at which the reacting materials are maintained at high temperature under high pressure, a thermally insulated digestor may be interposed in the connection between the heating coil 3 and the cooling coil 5. Instead of discharging the hot mixture from the heating coil, or the digestor, through the cooling coil, it may be discharged, with reduction of pressure, into a fractionating system in which it may be fractionated into a residual fraction and one or more distilled fractions by its contained heat. The fan 1 is provided for recirculating over the heating coil 3, together with fresh hot products of combustion from the fire box, a part, advantageously a large part, of the heating gases which have passed over the heating coil 3, to assist in the maintenance of uniform conditions.

The mixture of oil and hydrogen may be heated to a temperature in the range, for example, of 80G-950 F. under a pressure in the range, for example, of 50-300 atmospheres in the heating coil 3. Hydrogen concentrations in the range, for example, of 0.5 4.0%, or better 1-3%, by weight on the oil may be used.

The apparatus illustrated includes a particularly advantageous form of the receptacle to be interposed between the forcing means and the heating zone in accordance with the invention. This receptacle is conical in shape. The mixture of oil and hydrogen supplied from the receptacle to the heating zone is discharged through the small end of the cone, through connection 9. The oil and hydrogen are supplied to the large end of the cone through connections I and Il, respectively, arranged to discharge into the receptacle tangentially with respect to the cone. The point of oil introduction is advantageously spaced toward the small end of the cone from the point of hydrogen introduction. By means of this arrangement, internal moving parts may be eliminated. A receptacle provided with internal mechanical dispersing means, for example, may however be substituted for the form illustrated.

I claim:

1. In the manufacture of lower boiling oils by cracking and hydrogenating higher boiling oils without a catalyst, the improvement which comprises, forcing all the higher boiling oil and hydrogen passing to a heating zone through a receptacle adapted to contain a substantial body of the mixture and thereby maintaining a substantial body of the mixture in said receptacle, maintaining said body of the mixture at a temperature below that at which substantial cracking of the oil begins, maintaining effective dispersion of the hydrogen in the oil in said receptacle, heating the mixture to a cracking temperature under a pressure upwards of 50 atmospheres in said heating zone and maintaining a continuously uniform intimate dispersion of the hydrogen in the oil throughout the region of reaction.

2. -In the manufacture of lower boiling oils by cracking and hydrogenating higher boiling oils without a catalyst, the improvement which comprises, forcing all the higher boiling oil and hydrogen passing to a heating zone through a receptacle adapted to contain a substantial body of the mixture and thereby maintaining a substantial body of the mixture in said receptacle, maintaining said body of the mixture at a temperature below about 650 F., maintaining effective dispersion of the hydrogen in the oil in said receptacle, heating the mixture to a cracking temperature upwards of about 800 F. under a pressure upwards of 50 atmospheres in said heating zone and maintaining a continuously uniform intimate dispersion of the hydrogen in the oil throughout the region of reaction.

ANTONI SZAYNA.

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