US2105935A - Oil treatment - Google Patents

Description

Jan. 18, 1938. H. R. swANsoN OIL TREATMENT Filed NOV. 26. 1930 ?atented Jan. i8, i938 UNHED STAT grosses PATENT FFIQE OIL TREATMENT Application November 26, 1930, Serial No., 498,218

v 11 Claims.

My invention relates to the art of distillation and more particularly to the distillation of hydrocarbons.

One of the objects of my invention is to prolvide an apparatus for the treatment of crude oils under both atmospheric` and sub-atmospheric pressure while utilizing a single heater for heating the oil to be so treated. Heretofore it has been the practice to employ one heater to heat the oil-` before its introduction into the atmospheric apparatus and to employ a second separate heater to heat the oil before its introduction into the sub-atmospheric or vacuum apparatus. While attempts have-been made to incorporate both of these heaters in a single furnace setting, the result has been far from satisfactory due to the inability to regulate the temperatures in the twoheaters independently of each other. 'I'his may be done to some degree by placing the tubes for one heating operation in the roof of a furnace and the tubes for heating of the subsequent operation in the convection bank of the same-furnace.

When a furnace of this type operates atmaxlmum efllclency, the ratio of the work done in the radiant or roof section to the work done in the convection bank, remains constant. The charging stock, however, is subject to a varying boiling point range, dictated by plant operation and by various charging stocks. In order to-take care of this variation, it is necessary to vary the furnace eiiiciency by iiring with more or less excess air which involves a sacrice in furnace efciency and an increase in fuel consumption.

I propose to incorporate both banks of tubes in a single furnace setting and to provide additional means in either of the atmospheric or the vacuum apparatus for varying the `relative quantity of heat suppliedl to the oil in the two apparatuses. Hence, the furnace may be operated with a minimum excess air, thus obtaining high eiiiciencies.

Further objects and advantages of my invention will be apparent from the following specification considered in connection with the accompanying drawing on which isshown more or less diagrammatically, a preferred form of apparatus for carrying out my invention.

Referring to the drawing, reference character I8 designates a conduit leading from a supply of crude oil. Conduit I0 communicates with a pump I I, the discharge of which is connected by a' conduit I2 to a. surface type heat exchanger I3 which is in turn connected by means of a conduit I4 with a bank of roof tubes I5 located In the upper .part of a furnace setting I8. A conduit Il connects the outlet of roof tubes I5 with the interior of an atmospheric' fractionating tower I8.

The vinterior of tower I8 is provided with a series of bubble trays I9, both above and below the point where conduit I14 communicates with the tower. Each bubble'tray is provided with a down pipe 20 for conducting liquid downwardly from one tray to the next. Below conduit l1 within the tower is provided a pocket ZI formed by a ring-shaped disc or collecting deck 22 provided with a central cylindrical flange 23. A ldown fiow pipe 24 extends from near theltop of pocket 2| through plate 22 and discharges onto the next bubble tray below the plate. A 'conduit 25 communicates with the lower part of pocket 2I and with a pump 26, which discharges through a conduit 21 to conduit I4.

A conduit 28 communicates with the upper part of tower I8 and extends toheat exchanger I3. 'I'he heat exchanger I3 is connected by means of conduit 29 with a. cm1 cooler 3o which in tum is connected by a conduit 3I with a water separator 32. A conduit 33 connects the separator 32 with a reflux tank 34. A conduit 35 extends from the upper part of reflux tank 34V and leads to storage while a. conduit 36 connects the lower part of the reflux tank with a reflux pump 31, which discharges through a conduit 38 into the upper part of tower I8.

A conduit 39 communicates with the bottom of tower I8 and leads to a pump 40 which discharges through conduit 4I to a bank of convection tubes 42 placed in furnace` I6 behind the bridge wall 43 thereof so as to be located in the path of the products of combustion leaving the furnace. A conduit 44 connects the outlet of tubes 42 with the interior of a vacuum fractionating tower 45. Vacuum tower 45 is constructed internally similar `to atmospheric tower I8 and is provided with a series of bubble trays I8 above an-d below the point of communication of conduit 44 with the tower. A pocket 46, similar to pocket 2| in tower I8, is formed in tower 45 just below conduit 44.

A conduit 41 communicates with the lower part of pocket. and leads to a pump 48 which discharges through a conduit 49 to conduit 4I. A closed steam coil or heater 50 which may comprise one or more tubes of any desired arrangement `and structure is located within pocket 46 so as to be in contact with liquid contained in the pocket.y f

A conduit`5l communicates with the upper part of vtower 45 and leads to a condenser and cooler 52. A conduit 53 connects the hot well of condenser 52 with a steam jet vacuum pump 54. A.4

conduit 55 connects the bottom of the hot Well with a vacuum run down tank 56. The upper K4from the bottom of the run down tank to a pump 59 which discharges through a conduit Ell to a water separator 6I. Water separator 6I is connected by means of a conduit 62 with a reflux tank 63. A conduit 64 conducts oil from tank 53 to storage while a conduit 65 conducts reflux oil fromthe tank to a reux puirip 66, which discharges through a conduit 6I into the upper part of tower 45. A conduit 68 communicates with the bottom of tower 45 and with a pump 59 which discharges through conduit I0 to storage.

Incorporated in the furnace setting is a superheater 'II which is supplied with steam ythrough a conduit I2 and discharges superheated steam through a conduit 13. Conduit 'I3 communicates with a conduit 'I4 which leads to the lower part of atmospheric tower I8 and with conduits I5 and I6 which lead to within vacuum tower 45. A burner I8 supplies oil for combustion in the furnace chamber 79.

n roof tubes I5 located near thel roof of the furnace. In passing through the roof tubes I5 the crude oil is heated principally by radiant heat to the desired maximum temperature. In order to obtain color stability and to eliminate thermal decomposition and polymerization of unsaturated products, this maximum temperature, in the case of certain crude oils,is necessarily below the boiling point of the oil at atmospheric pressure. 'I'he oil thus heated to this maximum temperature is introduced through conduit II into tower I8. Superheated steam is introduced into the tower through conduit I4 and reduces the partial pressure of the oil vapor and thus vaporization of the oil will take place in the tower at a temperature below its normal boiling point. However, the oil introduced into the tower at the maximum allowable temperature will not contain sufficient heat to supply the latent heat of vaporization necessary to Vaporize the desired quantity of oil in the tower. Hence, unvaporized oil is collected in pocket 2I and a portion of this oil is recirculated through conduit 25, pump 26 and conduit2'I to conduit I4 where it is blended with the newly supplied oil and passed again. through the tubes I5 and thence back to the tower I8. The amount of oil thus recirculated is regulated so that the desired quantity of heat will be carried by the oil into the 'tower to provide the necessary latent heat of vaporization and so that the oil will be heated v in the roof tubes to the desired temperature.

Vapor passes upwardly ower I8 thrdp h the bubble trays i5 therein Vi e usual manner and is discharged from the top of the tower through conduit 28 to heat exchanger I3 where it gives up some of its heat to the crudeoil admitted to the heat exchanger through conduit I2. The vapor passes from the heat exchanger through conduit 29 to condenser 30 where the oil vapor and the steam are condensed and pass through conduit 3| to water separator 32. Liquid oil passes through conduit 33 to reflux tank 54 from which a portion of the oil is led through conduit 35 to storage while the remainder passes through -as reux in the tower 45.

arcades conduit 36. reux pump 3I and conduit 38 to the upper part of tower i8. The reux liquid passes downwardly through tower I8 from one bubble tray to the next through down pipes '20 while the vapor passing upwardly through the tower bubbles through the reflux.

Liquid oil not vaporized in tower I8 passes from the bottom thereof through conduit 38 to pump 49 which forces it through conduit 4I to the tubes l2 where the oil is again heated. In tubes i2 the oil may not be heated above the aforementioned or other predetermined maximum temperature and the oil heated to this temperature 'is discharged through conduit 46 to within vacuum tower d5. However, inasmuch as the heating by the furnace is determined by the amount of heat necessary` to be supplied to roof tubes I5, this amount of heat would heat the oil passing through tubes 42 to too high a. temperature if the only oil that passed through these tubes was that supplied from the bottom of tower I8. Therefore, oil is taken from pocket 46 in tower 45 and passed through conduit 41,

pump i8 and conduit 49 to be recirculated through the tubes d2. Now, if suiiicient oil were to be recirculated in this manner to carry the required amount of heat into tower 45 to provide the necessary latent heat for the vaporization of liquid therein, the temperature of the oil leaving tubes 42 would be below the desired predetermined temperature. In order to remedy this situation I recirculate `only a sufficient quantity of oil to maintain the temperature of `the oil discharged from tubes 42 at the desired temperature. The remainder of the heat necessary for vaporization of the oil in tower 45 is supplied by the steam coil 56, which heats the oil iripocket 46 in the tower.

Steam jet vacuum pump 54 maintains a vac` uum within tower 45 and this, in connection with the reduction of partial pressure due to the introduction of superheated steam, causes the Vaporization of oilin the tower at a temperature much below the boiling point of the oil4 under atmospheric conditions. The oil thusvaporized passes upwardly through the bubble trays I9 and through conduit 5I to the condenser and cooler 52. In the condenser 52 the oil vapors and steam are condensed and pass through conduit 55 to vacuum run down tank 56. The non-condensable gases pass through conduit 53 to steam jet vacuum pump 54, which pump as before stated. maintains thevacuum within tower 45. Liquid passes from vacuum run down tank 56 through conduit 58, pump 59 and conduit l6I) to water separator 6I. The oil passes from the water separator through conduit 62 to reflux tank 63. A portion of this oil passes through conduit 84 to storage while the remainder passes through conduit 65, pump 66 and conduit 61 to be used The bottoms from' tower 45 pass throughconduit 68, pump forces them through conduit 'I0 to storage Thus it will be seen that I have proyiied a v .ratus'an'd the vacuum apparatus, which furnace may be operated at a maximum eiiiciency without heating anyof the oil above a permissible maximum temperature. Additional heat required in one of the e'rs is provided by steam coi placed directly. the tower.

While I have shown and described a preferred embodiment of my invention it is to be understood CII.

that itis diagrammatic and that my invention is not to be limited thereby but is to be given the broadest interpretation commensurate'with the appended claims.

What I claim is:

1. Apparatus for the two-stage distillationl of hydrocarbon oils and the like comprising a heater having a first heating coil and a second heating coil, a rst fractionating tower and a second fractionating tower, means for introducing charging stock into the tubes in the rst heating coil of the heater wherein the oil is heated to a predetermined maximum temperature below the initial boiling point of oil under the total pressure existent in the first fractionating tower,

means for introducing oil heated in said last men.

tioned heating coil into the rst tower, means for introducing steam into the first tower, thereby reducing the partial pressure of the oil vapor and causing vaporization to take place, means for separating the vaporized and unvaporized portions of the oil, means for recirculating part of the unvaporized oil introduced into the rst tower through the tubes in the ilrst heating coil of the heater, together with charging stock, and reintroducing it into the rst tower to supply the latent heat for the desired -vaporizatiom means for introducing bottoms from the rst tower into the tubes in the second heating coil of the heater, means for introducing oil from the second heating coil into the second tower, means for maintaining the second tower under a pressure lower than that in the rst tower, means for introducing steam into the second tower thereby reducing the partial pressure of the oil vapor and assisting vaporization to take place, means for separating the vaporized and unvaporized portions of the oil, means for collecting unvaporized oil in the second tower, means for recirculating enough of said collected oil through the tubes in the' second heating coil of the tower with bottoms from the ilrst tower and reintroducing it into the second tower so that the mixture will be heated only to said predetermined maximum temperature, and means for supplying heat to the oil collected in the second tower to supply the balance. of the latent heat needed for the desired vaporization thereof.

2. The process of distilling. hydrocarbon oilsv and the like which comprises passing the oil through a rst section of a heating zone to heat the oil to a predetermined maximum-temperature below the initial boiling point'of the oil under the total pressure existent in a first fractionating zone, introducing the heated oil into said fractionating zone, introducing steam into said frac-` tionating zone thereby reducing the partial'pressure of the oil and causing vaporization to take place, recirculating unvaporized oil from said fractionating zone through the said section of the heating zone and reintroducing it into said fractionating zone to supply the latent heat for thedesired vaporization of the oil in saidfractionating zone, withdrawing liquid oil from Bald 1ractionating zone, passing the withdrawn liquid oil through asecond heating section of said heating zone, introducing the last mentioned heated oil into a second iractionating zone maintainedat' a lower pressure than the first fracticnating zone,

introducing steam into the second fractionating zone thereby reducing they partial pressure of the oil and assisting vaporization to take place, re-

circulating through the said second heating section of the heating zone with the oil from the iirstr fractionating zone, sufilcient liquid oil from the second fractionating zone to causethe mixture to be heated only to said predetermined temperature and supplying the balance of the latent heat to the oil in the second fractionating zone to obtain the desired degree of vaporization thereof.

3. An apparatus for continuously distilling petroleum oils containing asphalt having in combination, a column having a stripping section, a collecting deck at the top of the stripping section, a heater for heating the oils and asphalt together inthe liquid phase, a feed line to the heater, means for discharging oils from the heater onto the collecting deck, a draw-o i pipe leading from the ,collecting deck, a pump for pumping material from the collecting deck to the feed line, a steam admission pipe at the bottom of the column, and an overflow pipe for carrying residue from the collecting deck downwardly in countercurrent with the steam.

4. An apparatus for continuously distilling petroleum oils containing asphalt having in combination, a heater for heating the oil and asphalt together in the liquid pbase, a feed line to the heater, a column having .1. stripping section with a collecting deck located intermediate the top and bottom plates of the stripping section, means for discharging oils from the heater onto the top plate of the stripping section, a draw-off pipe feed line, a steam admission pipe at the bottom of the column and an overflow pipe for carrying residue vfrom the collecting deck downwardly in countercurrent with the steam.

5. An apparatus for' continuously distilling petroleum oils comprising a heater for heating the oil, a feed line to the heater, a column having a stripping section with a collecting deck located intermediate the top andbottom plates of the stripping section, means for discharging oils from the heateronto the .top plate of the stripping section, a draw-off pipe leading from the collecting4 deck, a pump for pumping material from the collecting deck to theeed line, a steam admission pipev at the bottom of the column and an overow pipe for carrying residue from the collecting' deck downwardly in 4countercurrent with the steam.

6. Apparatus for the distillation oil hydro- .carbon oils comprising a heater for heating the tion, and means for recirculating oil from the collecting deck through the heater.

7. Apparatus for the distillation of hydrocarbon oils comprising a heater for heating the oil to vaporization temperature, a ractionating column having a stripping section, a collecting deck at the top of the stripping section, means for disl charging' unvaporized oil from the heater onto the collecting deck, means for conducting oil from the collecting deck to the stripping section, and means for recirculating oil from the collecting deckthrough the heater.

8. Apparatus for the distillation of hydrocarbon oils comprising a heater for heating the oil. to

. vaporization temperature. a fractionating column having la stripping section, a collecting deck disposed intermediate thetop and bottom plates of the stripping section, means for discharging unvaporized oil from the neatereato the upper 76 gij. aoaasc .the stripping section, means for discharging unvaporized oil from the heater onto the collecting deck, means for conducting oil from the collecting deck to the stripping sectiomand m'eansfor recirculating oil from the collecting deck through the heater.

10. Apparatus for the two-stage distillation of hydrocarbon oils and the like comprising a heater having a rst heating coil and a second heating coil, a first fractionating tower and a second fractionating tower, means for introducing charging stock into the tubes in the rst heating coil of the heater kwherein the oil is heated to a predetermined maximum vaporization temperature below the initial boiling point of oil under the total pressure existent in the iirst fractionating tower, means vfor introducing oil heated .in Asaid last mentioned heating coil into the rst tower, means for separating the vaporized and un- Vaporize'd portions of the oil, means for recirculating part of the unvaporized oil introduced into the .rst to-Wer through the tubes in the'rst heating coil of the heater, together with charging stock, and reintroducingit into the first tower to supply the latent heat for the desired Vaporization, means 'for introducing bottoms from the first tower into the tubes in the second heating coil of the heater, means for introducing oil from the second heating coil into the second tower, means for separating the vaporized and unvaporized portions of the oil, means for collecting unvaporized oil in the second tower, means for recirculating enough of said collected oil through the tubes in the second heating coil of the tower with bottoms from the rst tower and reintroducing it into the second tower so that the mixture will be heated only to said predetermined maximum temperature, and means for supplying heat to the oil collected in the second tower to supply the balance of the latent heat needed for the desired vaporization thereof.

1l. The process of distilling hydrocarbon oils and the like which comprises passing the oil through a rst section of a heating zone to heat the oil to a predetermined maximum vaporization temperature below'the initial boiling point of the oil under the total pressure existent in a rst fractonating zone, introducing the heated oil into said fractionating zone, recirculating unvaporized oil from said fractionating Zone through the said section ofthe heating zone and reintroducing it into said fractionating zone to supply the latent heat for the desired vaporlzation of the oil in said fractionating zone, withdrawing liquid oil from said fractionating zone, passing the withdrawn liquid oil through a second heating section of .said heating zone, introducing the last mentioned heated oil into a second fractionating zone, reclrculating through the said second heating section of the heating zone with the oil from the rst fractionating zone, sufcient liquid oil from the second fractionating zone to cause the mixture to be heated only to said predetermined temperature and supplying the balance of the latent heat to the oil in the second fractionating zone to obtain the desired degree of vaporization thereof. i

HARRY ROBERT SWANSON.

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