US1961211A - Method of and apparatus for distillation of oil - Google Patents

Description

June 5, 1934. H. M. GRAHAM 1,961,211

METHOD OF AND APPARATUS FOR DISTILLATION OF OIL Filed March 13, 1931 2 Sheets-Sheet 1 gwuentoz [0 and pm H. M. GRAHAM June 5, 1934.

METHOD OF AND APPARATUS FOR DISTILLATION OF OIL Filed March 13, 1931 2 Sheets-$heet 2 Patented June 5, 1934 UNITED STATES PATENT orslcs METHOD OF AND APEARATUS FOR DISTILLATION OF OIL Application March 13, 1931, Serial No. 522,195

14 Claims.

This invention relates to the art of refining oil and is concerned in particular with a novel method and apparatus for distilling oil with the aid of steam and at sub-atmospheric pressures.

The distillation of oil with the aid of steam and under sub-atmospheric pressures has the advantage that vaporization of the stock can be effected at low temperatures. This is not only desirable from a standpoint of economy but it has the further advantage that injury to the stock, or the product produced thereupon, as a result of over-heating is prevented.

Heretofore, it has been the practice to pass the steam through a vaporizing zone, whereby to produce a mixture of oil and steam vapors. The mixture thus produced is conducted to a separating zone in which the oil vapors are condensed without condensation of the steam. Thereafter all of the steam passes to a cooling Zone in which it is condensed. The amount of steam required in carrying out the procedure outlined is relatively large and represents a substantial part of the cost of production of the oil product.

One object of the present invention is a process which, while retaining the advantages of the method above described, will enable a substantial saving in the amount of steam required, whereby to reduce the cost of production of the oil product.

A further object is a process which will enable condensation of the excess steam with cooling water of the temperature available.

A still further object is to provide novel apparatus for carrying out the process.

The invention consists generally in causing the steam to flow in a circuitous path through apparatus in which a vacuum is maintained by ejector equipment. The said path includes a zone in which oil vapors are entrained with the steam from the ejector equipment and a zone in which the oil vaporsare separated from the steam without condensation of the latter, the steam thereafter being compressed by the ejector equipment and reintroduced into the vaporizing zone. It will be noted that after the circulating body of steam is once established the only additional steam required is motive steam, that is to say steam for causing the body of steam to circulate in the manner described. The motive steam employed is also available to compress the excess steam so that it can be condensed with cooling water of the temperature available.

In the accompanying drawings:

Figure 1 is a side elevation view, partly in section, of apparatus embodying my invention and capable of carrying out my process.

Figure 2 is a similar view of a modified form of apparatus.

The apparatus for carrying out the process, as illustrated, includes a heater 10 of any desired construction to which the charging stock may be delivered by a pump 11, the latter. being arranged in a supply line 12. The heater 10 is preferably regulated to heat the stock to a temperature sufiicient to effect distillation of the latter when under a sub-atmospheric pressure of a determined value.

From the heater 10, the stock is delivered by pipe 13 to a still or tower 14 in which a subatmospheric pressure is'ma-intained and in which the distillation is effected. A perforated pipe 15 extends into the still near the bottom thereof and it is through this pipe that steam is introduced into the still. As the heated stock enters the still 14, oil vapors of the desired constituents are evolved and these vapors commingle with the steam introduced through the pipe 15, the remaining liquid constituents or residuum settling to the bottom of the tower and being drawn off, when desired, through a suitable drain pipe 16. The oil vapors and steam are conducted by a pipe 17 to a condenser 18. A suitable cooling medium may be circulated through the condenser 18 by means of pipes 19. The condenser is adapted to condense only the condensable oil vapors without condensing the steam in order that the latter may be reused. In this connection it is to be noted that of the oil vapors evolved, a relatively small quantity thereof will not condense in the condenser 18 but pass therefrom with the steam, these uncondensable vapors being referred to hereinafter, for convenience, as-fixed gases.

The condenser 18 is formed with a compartment 20 in which the oil condensate is collected and from which the said condensate may be withdrawn through a pipe 21. The mixture of steam and fixed gases remaining after separation therefrom of the oil vapors is withdrawn from the com.- partment 20 by an ejector 22, the latter being sup- 1 plied with steam through a pipe 22a and serving to maintain a vacuum of a predetermined value in the still 14 and condenser 18. In order to enable withdrawal of the steam and fixed gases from the compartment 20 without withdrawal of some of the oil condensate, a hood 23 is arranged in the compartment and is upturned at its lower edge to form a channel 24 in which the condensate collects, the latter being conducted to the bottom of the compartment, through the path to be traversed by the steam, by pipes 25-. The mixture of steam and fixed gases withdrawn from the condenser by the ejector 22 is forced through a pipe 26 to a pipe 27, the latter communicating at one end with the perforated pipe 15 in the bottom of the tower 14 and at the other end with a condenser 28. It will be apparent that in this operation the mixture of steam and fixed gases is compressed as it is being forced through the pipe 26 and is also reheated to some extent by its contact with the injected steam. The mixture of steam and fixed gases entering the pipe 27 divides, a portion thereof entering the condenser 28 while the remainder passes by way of pipe 27a to the perforated pipe 15 where the steam again commingles with the evolving oil vapors in the manner described. Thus, a substantial quantity of steam in the system is caused to flow in a circuitous path, this quantity as compared to the quantity entering the condenser 18 depending for the most part upon the sub-atmospheric pressure at the inlet to the condenser 28 and the pressure drop through the tower, condenser and piping in the system. In other words, the ejector compresses over a range equal to the pressure drop through the circulating system. The quantity of fixed gases evolved as compared to the quantity of steam and oil vapors that are condensed in the condenser 18 is relatively small and as a part of these gases enters the condenser 28, there will, of course, only be a small quantity of them reintroduced into the still.

The condenser 28 comprises a shell body 29 and a drain pipe 30, the latter being of a length sufficient to enable discharge of the steam condensate. The body of the condenser is formed with inlet openings 31 and 32, the former provid ing an inlet for the steam and fixed gases while a water supply nozzle 33 extends through the latter up into the body of the condenser. A deflector 34 which is suitably supported by the top of the condenser body extends downwardly past the steam inlet opening 31 and surrounds the nozzle 33. Cooling water is supplied to the nozzle through a feed pipe 35, the said water being discharged in sprays against the inner wall of the deflector 34 and falling from the wall in a shower toward the drain pipe 30.

The steam and fixed gases that enter the condenser are first directed downwardly beneath the lower edge of the deflector 34. As they pass up through the deflector 34 they are subjected to the cooling action of the sprays from the nozzle 33 and the greater part of the steam is condensed while the fixed gases are cooled. An upper cooling spray may be provided by an auxiliary nozzle 38, the latter being connected to a supply pipe 37. In the upper cooling spray, any steam remaining uncondensed after passage through the lower sprays is condensed while the fixed gases are cooled to substantially the same temperature as the cooling Water of the upper spray. The said gases and any remaining steam are withdrawn from the condenser 28 by an ejector 38 and are forced through a pipe 40 into a second condenser 41, the latter being provided with a nozzle 42 for forming a cooling spray in a similar manner to the nozzle 33 of condenser 28. Any such remaining steam and the steam admitted to the ejector 38 are compressed in the pipe 40 and condensed in the condenser 41. The latter includes a drain pipe 42a which functions similarly to the corre sponding pipe of the condenser 28. An ejector 43 is adapted to withdraw the fixed gases from the condenser 38 and effect their discharge through the so-called barometric type. It is to be under- 0 stood that the use of this type of condenser is solely for the purpose of illustration as other types of condensers may also be availed of.

From the foregoing, it will be apparent that in carrying out the process, a body of steam is 0 caused to flow in a circuitous path which in" cludes the still. The oil vapors are entrained by the steam and conducted to the condenser 18 where they are condensed without condensation of the steam. The motive steam which is supplied to the system through the ejector 22 serves not only to maintain the desired degree of vacuum in the still 14 and condenser 18 but also to compress 1e steam Withdrawn from the condenser 18 over a range equivalent to the drop through the system, thereby causing the steam to again pass into the still and circulate through the apparatus in the manner described. The compression of the steam has the additional advantage that it enables condensation of the steam which T.-

enters the condenser 28 at a higher temperature of cooling water than would otherwise be possible. Thus, it is possible to maintain a high enough vacuum in the still 14 and condenser 18 for the purposes in view with cooling water at the teml" by reducing to a minimum the quantity of steam 1' I required with a resultant saving in the cost of production of the oil product. The only steam condensed in the system, therefore. is the excess steam, this in quantity being substantially the same as that admitted through the ejector 22. 13).

The quantity of excess steam is relatively small as compared to the quantity being ccntinuously passed through the vaporizing zone. This has the advantage that although relatively large quantities of steam may be circulated, only a f3:

relatively small amount of new steam is continuously admitted into the apparatus and the capacities of the condensers need only be large enough to take care of the excess steam.

In some installations, it may be desirable to maintain a higher sub-atmospheric pressure in the still 14 and condenser 18, under the same operating conditions, than can be maintained by the apparatus just described, for example, a system in which the sub-atmospheric pressure at the bottom of the tower is higher than can be maintained by the condensers with cooling water of the temperature available. In Figure 2, a modified arrangement of apparatus is shown which is capable of obtaining this result. In this embodiment, the steam is caused to flow in the circulating system in the same manner as described in connection with Figure 1. However, in order to enable circulation of the steam while at the same time maintaining the desired high I sub-atmospheric pressure by the use of available cooling water, the excess steam and the fixed gases are, prior to being delivered to the con denser 28, first further compressed by an ejector or auxiliary booster 45 in a pipe 45a. After bein the sys- 1 ing further compressed by the ejector 45, the excess steam and fixed gases are treated in the manner described in the first embodiment, that is to say, the steam is condensed and the fixed gases are cooled and then withdrawn from the system.

It will be noted that in this embodiment the ejector 22 serves to compress the steam in the circulating system over a range substantially equal to the drop through the circulating system, thereby causing the steam to circulate in the manner required. The ejector 45, however, compresses only the excess steam which is to be condensed. This excess steam has already been compressed by the ejector 22 together with the main body of steam in the circulating system. While such compression is sufiicient to effect the desired flow of the steam in the circulating system, it will not, in many instances where it is desired to effect the distiliation under a relatively high sub-atmospheric pressure, be adequate to enable condensation of the excess steam with cooling water of the temperature available. The ejector 45, therefore, further compresses the excess steam to such an extent that it can be readily condensed with the cooling water available. In other words, the ejector 22 causes the steam to flow in the system in the desired manner while use of the ejector 45 enables condensation of the excess steam, and hence maintenance of the desired vacuum, at available temperatures of cooling water. In other respects, the apparatus is similar to the embodiment first described and its use is attendant with the same beneficial results.

I claim as my invention:

1. The method of treating oil which consists in delivering it to a vaporizing zone in which a sub-atmospheric pressure is maintained, introducing steam into said zone to produce a mixture of oil vapors and steam, cooling the said mixture to condense substantially all of the oil vapors -without substantial condensation of the steam,

collecting the oil condensate, compressing the steam after separation therefrom of the oil vapors, returning a portion of the compressed steam to said vaporizing zone and further compressing a portion of said compressed steam so that it may be condensed by cooling water of the temperature available.

2. The method of treating oil which consists in delivering it toa vaporizing zone in which a subatmospheric pressure is maintained, circulating steam through said zone to produce a mixture of oil and steam vapors and fixed gases, cooling the said mixture to condense substantially all of the oil vapors without substantial condensation of the steam, collecting the oil condensate, compressing the mixture of steam and fixed gases remaining after separation therefrom of the oil vapors, returning a portion of the compressed mixture to said vaporizing zone and further compressing a portion of said compressed mixture so that the steam component thereof may be condensed with cooling water of the temperature available.

3. Apparatus for treating oil at sub-atmospheric pressures comprising a still, means through which steam is introduced into said still so as to produce a mixture of oil vapors and steam, an ejector for evacuating said still and for withdrawing said mixture of oil vapors and steam, means for condensing substantially all of the oil vapors without substantial condensation of the steam, means for collecting the oil condensate, said ejector compressing all of the steam after separation of the oil vapors therefrom, means for returning a part of the compressed steam to said first named means, whereby to introduce it into the still and means for condensing a part of the compressed steam with cooling water of the temperature available.

4. Apparatus for treating oil at sub-atmospheric pressures comprising a still, means for heating the oil delivered to said still, means through which steam is introduced into said still to produce a mixture of oil vapors and steam, an ejector for evacuating said still and for withdrawing said mixture of oil vapors and steam, a condenser to which said mixture is delivered and by which substantially all of the oil vapors are condensed without substantial condensation of the steam, means for collecting the oil condensate, said ejector compressing all of the steam after separation therefrom of the oil vapors, means for returning a substantial part of the compressed steam to said second named means, whereby to reintroduce it into the still and means for con densing a part of the compressed steam with cooling water of the temperature available.

5. Apparatus for treating oil at sub-atmospheric pressures comprising a still, means for heating the oil delivered to said still, means through which steam is introduced into said still to produce a mixture of oil and steam vapors and fixed gases, an ejector for evacuating said still and for Withdrawing said mixture of oil and steam vapors and fixed gases, a condenser to which said mixture is conducted for condensing substantially all of the oil vapors without substantial condensation of the steam, means for collecting the oil condensate, said ejector compressing all of the steam and fixed gas-es after separation therefrom of the oil vapors, means for returning a part of the compressed mixture to said second named means, whereby to reintroduce it into said still, means for condensing the steam in a part of the compressed mixture with cooling water of the temperature available and means for withdrawing the fixed gases from said condensing means last mentioned.

6. Apparatus for treating oil at sub-atmospheric pressures comprising a still, a steam circulating line, one end of which communicates with said still and through which steam is introduced into the still so as to produce a mixture of oil vapors and steam, a condenser included in said line and in communication with said still through the other end of said line to which said mixture is delivered and which is adapted to condense substantially all of the oil vapors of the mixture without substantial condensation of the steam, means for collecting the oil condensate, means for circulating steam through said line, means for withdrawing the excess steam from said circulating line and means for compressing said excess steam so that it may be condensed by cooling water of the temperature available.

'7. Apparatus for treating oil at sub-atmospheric pressures comprising a'still, means for introducing steam into said still so as to produce a mixture of oil vapors and steam, a condenser to which the said mixture flows and by which substantially all of the oil vapors are condensed without substantial condensation of the steam, means for collecting the oil condensate, means for compressing the steam after separation therefrom of the oil vapors, means for returning a substantial part of the compressed steam to said still and means for further compressing a part of the compressed steam so that it may be condensed by cooling water of the temperature available.

8. Apparatus for treating oil at sub-atmospheric pressures comprising a still, means for introducing steam into said still to produce a mixture of oil vapors and steam, a condenser to which said mixture is delivered and by which substantially all of the oil vapors are condensed without substantial condensation of the steam, means for collecting the oil condensate, an ejector for compressing the steam after separation therefrom of the oil vapors, means for returning a substantial part of said compressed steam to the still and means for further compressing a part of the compressed steam so that it may be condensed by cooling water of the temperature avail able.

9. Apparatus for treating oil at sub-atmospheric pressures comprising a still, means for introducing steam into said still to produce a mix ture of oil vapors and steam, a condenser to which said mixture flows and by which substantially all of the oil vapors are condensed without substantial condensation of the steam, means for collecting the oil condensate, an ejector for compressing the steam after separation therefrom of the oil vapors, means for returning a substantial part of the compressed steam to said still and a second ejector for further compressing a part of the compressed steam so that it may be condensed by cooling water of the temperature available.

10. Apparatus for treating oil at sub-atmospheric pressures comprising a still, means for introducing steam into said still to produce a mixture of oil and steam vapors and fixed gases, condensing means to which said mixture fiows and by which substantially all of the oil vapors are condensed without substantial condensation of said steam, means for collecting the oil condensate, means for compressing the remaining mixture of fixed gases and steam, means for eturning a part of the said compressed mixture to said still, means for further compressing a part of the compressed mixture, condensing means to which said further compressed part of the mixture is delivered and by which the steam in said part is condensed by cooling water of the temperature available, and means for withdrawing the fixed gases from the condensing means last mentioned.

11. Apparatus for treating oil at sub-atmospheric pressures comprising a still, means for heating the oil delivered to said still, means through which steam is introduced into said still to produce a mixture of oil and steam vapors and fixed gases, condensing means to which said mixture flows and by which substantially all of the oil vapors are condensed without substantial condensation of the steam, means for collecting the oil condensate, an ejector for withdrawing the remaining mixture of steam and fixed gases from the condensing means and for compressing the same, means for returning a part of the compressed mixture to said still, an ejector for further compressing a part of the compressed mixture, condensing means to which said further compressed part is delivered and by which the steam therein is condensed by cooling water of the temperature available and an ejector for withdrawing the fixed gases from the condensing means last mentioned.

12. The method of treating oil which consists in introducing it into a vaporizing zone, passing steam through said zone to produce a mixture of oil vapors and steam, evacuating said zone and withdrawing the mixture of oil vapors and steam therefrom with motive steam, cooling the withdrawn mixture of oil vapors and steam to condense the oil vapors without substantial condensation of the steam, compressing all of the withdrawn steam with said motive steam, condensing a portion of the compressed steam with cooling water of the temperature available and reintroducing the remainder of the compressed steam into said zone.

13. The method of treating oil which consists in heating the oil, introducing it into a vaporizing zone, passing steam through said zone to produce a mixture of oil and steam vapors and fixed gases, evacuating said zone and withdrawing the mixture of oil and steam vapors and fixed gases therefrom with motive steam, cooling the withdrawn mixture of oil and steam vapors and fixed gases to condense substantially all of the oil vapors without substantial condensation of the steam, compressing the remaining mixture of steam and fixed gases with said motive steam, cooling a portion of the compressed mixture with cooling water of the temperature available to condense the steam component of said portion and returning the remainder of the compressed mixture to said vaporizing zone.

14. Apparatus for treating oil at sub-atmospheric pressures comprising a still, means through which steam isiintroduced into said still so as to produce a mixture of oil vapor and steam, an ejector for evacuating said still and for withdrawing said mixture of oil vapors and steam, a condenser for condensing substantially all of the oil vapors without substantial condensation of the steam, a second condenser, said ejector withdrawing said steam from said first mentioned condenser and introducing a part of it into said still through said .first named means and the remainder of it into said second condenser, said second condenser being adapted to condense the steam introduced into it and means for withdrawing the fixed gases and uncondensable vapors from said second condenser, whereby to enable maintenance of the desired degree of vacuum in said still.

HAROLD M. GRAHAM.

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