US1953651A

US1953651A - Process and apparatus for the treatment of alpha liquid, more especially alpha petroleum distillate, with another immiscible liquid

Info

Publication number: US1953651A
Application number: US373047A
Authority: US
Inventors: Holley Alfred Ewart; Mott Owen Edwin
Original assignee: ANGLO PERSIAN OIL Co Ltd
Current assignee: ANGLO PERSIAN OIL Co Ltd; ANGLO-PERSIAN OIL COMPANY Ltd
Priority date: 1928-07-03
Filing date: 1929-06-22
Publication date: 1934-04-03
Anticipated expiration: 1951-04-03

Description

P" 1934- A. E. HOLLEY ET AL 1,953,651

PROCESS AND APPARATUS FOR THE TREATMENT OF A LIQUID,

MORE ESPECIALLY A PETROLEUM DISTILLATB, WITH ANOTHER IMMISCIBLE LIQUID Filed June 22, 1929 v 5 Sheets-Sheet 1 April 3, 1934. A E. HOLLEY ET AL PROCESS AND APPARATUS FOR THE TREATMENT OF A LIQUID,

MORE ESPECIALLY A PETROLEUM DISTILLATE, WITH ANOTHER IMMISCIBLE LIQUID Filed June 22, 1929 5 Sheets-Sheet 2 Inventors 6'. f/ I 0. 6.110%: y

flttorlzey.

Apr!l 1934- A. E. HOLLEY ET AL 1,953,651

PROCESS AND APPARATUS FOR THE TREATMENT OF A LIQUID,

MORE ESPECIALLY A PETROLEUM DISTILLATE, WITH ANOTHER IMMISCIBLE LIQUID .ltorney.

APrl] 1934- A. E. HOLLEY ET AL 1,953,651

PROCESS AND APPARATUS FOR THE TREATMENT OF A LIQUID,

MORE ESPECIALLY A PETROLEUM DISTILLATE, WITH ANOTHER IMMISCIBLE] LIQUID Filed June 22, 1929 5 Sheets-Sheet 4 Flg 7- flttorney.

A. E. HOLLEY ET AL April 3, 1934.

PROCESS AND APPARATUS FOR THE TREATMENT OF A LIQUID,

MORE ESPECIALLY A PETROLEUM DISTILLATE, WITH ANOTHER IMMISCIBLE LIQUID Filed June 22, 1929 5 Sheets-Sheet 5 Inventors J. 5. f/alley; 0. 6. M0125 A) 5 sv-po vi I flfor/wy.

Patented Apr. 3, 15334 PROCESS AND A TREATMENT 0F ESPEEEALLY A PETRQLE 'WETH ANOTHER Alfred Ewart Holley, W

Mott, l eltllarn, England,- assigns Persian Oil Comp England Application June 22,

Mir/ii screen ome orthing and Gwen Edwin rs to Anglo' any, Limited, 'London,

1929, Serial No. 373,047 1 En Great Britain July 3,1928

16 Claims.

This invention relates to the treatment of one liquid with another in counter-current, and, while of general application in the treatment or washing of liquids involvingintimate admixture ,5 and prolonged contact of liquids that are adapted to separate according to their densities, is o i"especial application in the Washingor refining of petroleum distillates. I

It isknown to use a number of pairs of mining and separating vessels at the same leveland so to connect the vessels by piping that a counter current flow of the denser and less dense liquids is produced under the action of gravity, on the denser and less dense liquids bein fed respectively into the first andlast mixing vessels of the set, and being intimately-intermixed in the several mixing vessels, the counter-flow of the liquids being caused solely by the head in the re spective separating vessels consequent upon'the admixture of the liquids of differing densities in the mixing vessels and their subsequent separation in the separating vessels.

The invention has among its objects'to maintain a determined ratio of the denser to the less dense liquid in the mixing vessels irrespective of the rate at which the respective liquids are fed tothe plant, whereby the period of contact neces sary forexample according to theproportion of the reagent or washing liquid used may base cured and wherebythe reagent or washing liquid may be maintained in active use until its efficiency is impaired, and thus the supply of freshiliquid may be maintained at a minimum; generally to improve the treatment and the construction and-operation of the plant employed.

Thus, according to the invention'means are provided to maintain a determined ratio of the denser to the less dense liquid in the mixing vessels irrespective of the rate at which the respectiveliquids are fed to the'plant. This maybe effected according to the invention by causing a local circulation of the denser liquid between the i respective mixingand separating vessels of each pair while permitting, where necessary, any desired proportion of the denser liquid to pass to the succeeding mixing vessel. Thus, the. respective mixing and separating vess be connected near the bottom by an orifice as fording interoominunication or by a pipe connected between them, by which a part of the denser or washing liquid may continuously return from the separating vessel to themixing vesse whence it came by reason of the head in the separating vessel due to the diiference in density of els of a pair may the denser liquid in the separating vessel and of (ciiss is).

the mixed liquids in the mixing vessel, while any desired part or proportion of the denser or washing liquid ma in the operation of the plant, pass on continuously into the next mixing vessel of. the set. A valve or cook controlling the orifice or the pipe referred to may beprovided to permit.

of. adjustment for variation in the proportion of the denser or washing liquid returned from the separating vessel tothe mixing vessel, while a similar provision may be inade with respect to the or the like through which the denser or washing liquid passes on to the next mixing vessel in the set. Again, the proportion of, the denser or washing liquidreturned into the mixing vessel may be determined by the control of the proportion of thev s id liquid which passes onto the succeeding mixing vessel.

.t will be understood that'by the provision of one or a number of connecting pipes between the respective mixing and separating'vessels' and. by the control of the flow through them the amount of liquid circulated back from the separating vessel to its complementary mixing vessel, in relation to that fed forward to the next mixing vessel in the set may be varied widely to meet varying practical requirements. 5 I

-A"cordinglto the invention, moreoven means may he provided, not involving the use of a pump, for the removal from time to time of solid or foreign'matter accumulating at the interrace of the denser andi ss dense liquids in the separating vessels or in certain of them; this a provision of particular utility in wash ing petroleum distillates with alkali, more especially For his purpose a horizontally disposed radial'arm open or slotted at the upper part maybe mounted upena vertically disposed hollow rod or spindle, the upper end of which be suitably carried, while the-lower end is V mounted within a tubular socket set centrally at t 1e bottom of the-separating vessel, the socket 1 being connected to'an outlet pipe extendingbeneaththe vesseL- The outlet pipe may be under the control oi'a valve. Thus, on the verticaladjustment of the upper end of the hollow rod or spindle, the horizontally dis osed radial arm may be. set into such 1 position vertically on the rotation of the hollow rod or spindle the arm niay be swept in. the plane of theinterface, whereby, on opening the valve on the out& letpipe, anyaocumulation of solid matter at the interface may pass with the entrainihg liquid through the slotted arm into the hollow rod or-spindle and thence pass through the outlet pipe under gravity into a skimming tanlr disposed at a level beneath the separating vessel. After settling and separating, the clear washing or denser liquid may be run into a second skimming tank disposed beneath the first referred to. Water under pressure may then be admitted to the first skimming tank, and the clear less dense liquid may be displaced into the second skimming tank, Water and the solid matter may then be run to waste, and the clear washing or denser liquid and the less dense liquid or distillate in the second skimming tank may be returned to the plant.

According to the invention, moreover, a settling tank or settling tanks may also be usefully provided as an extension of a separating vessel, such as the last vessel of a set used in the acid washing of kerosene or spirit, to afiord additional separating space for the purpose of ensuring as far as possible that the liquid under treatment may not carry with it any of the washing or denser liquid in one set or stage to another set or stage in which a different washing or denser liquid is used. Such a tank may be provided at the same level as the separating vessel to which it is connected, or

may be otherwise provided whereby the outlet at the upper part of the separating vessel for the less dense liquid or distillate may discharge into the upper part of the tank. An outlet pipe for the said liquid or distillate advantageously at the opposite end of the tank may be connected with the first mixing vessel of the succeeding set of mixing and separating vessels in which the distillate may then be washed with, for example, a solution of soda.

The denser or washing liquid subsiding at the bottom of the tank may be separately withdrawn or may be returned to the last mixing vessel of the set whence it has issued.

Such a settling tank or tanks may thus be used in extension of any section or units of the plant.

According to the invention, moreover, the mixing vessels may be provided with rotating vanes or blades set upon a vertical axis disposed eccentrically to the vertical centre line of the vessel in such manner as to avoid the formation of a smooth vortex at the centre of the vessel and ineihcient mixing of the liquids, the vertical axis being conveniently in position opposite *shaped sheets of steel or other material, which may advantageously be mounted upon the spindle one immediately beneath the other, the vanes or blades being so disposed that a diagonal line across them is substantially coincident with v low to a position short of the height of the column of liquid in the vessel and are surmounted by an anti-vortex disc transversely mounted upon the spindle. By such means effective intermixture of the liquids within the mixing vessels may be ensured on the rotation of the spindles and the level of the liquid maintained substantially without vortex or cavitation.

The invention comprises of the features method and apparatus hereinafter described.

The accompanying drawings diagrammatically illustrate a plant adapted for use according to the invention.

Figures 1 and 2 represent in elevation and plan respectively a continuous washing plant for washing a motor spirit successively with a solution of sodium hypochlorite and a solution of caustic soda.

Figures 3 and 4 are views corresponding to Figures 1 and 2 of a continuous washing plant for a three-stage continuous washing of kerosene successively with a solution of caustic soda, a solution of acid and a solution of caustic soda.

Figures 5 and 6 are views similar to Figures 1 and 2 of a continuous washing plant for succersively washing White spirit with solution of caustic soda, a solution of acid. a solution of caustic soda and an alkaline solution of sodium hypochlorite.

Figure '7 is a sectional elevation. of a mixing vessel with the means for efiecting admixture of the liquids of differin" densities and of a separating vessel with skimming mechanism.

Figure 3 is a plan view corresponding to Figure '7.

Figure 9 shows diagrammatically a skimming plant for the removal of solid matter accumulating at the interface of the denser and less dense liquids in certain of the separating vessels of the plant such as diagrammatically illustrated in the drawings. 7

Figure 10 is a diagrammatic representation of a plant according to the invention embodying four pairs of mixing and separating vessels.

In carrying the invention into effect in its application to a plant for washing petroleum distillates as illustrated in the accompanying drawings, a series of pairs of mixing and separating vessels a, I), such as hereinbefore described, is provided on the same level. The vessels are preferably closed, but advantageously fitted with hinged explosion covers :1 b the movement of which is limited by means of metal bows, straps or the like a b serving to return the covers to the closed position after movement. Each mixing vessel a is provided with means such as hereinbefore described for intimately intermixing the washing or denser liquid and the less dense liquid or petroleum distillate. The pipe connections between the respective vessels are such that the less dense liquid from any separating vessel b passes in one direction near the top to the mixing vessel a of the pair of vessels a, b next in the series and the denser liquid from that separating vessel passes in opposite direction near the bottom to the mixing vessel 12 of the pair of vessels a, b next in the series. The less dense liquid, that is to say, the petroleum distillate, such as motor spirit, kerosene, or white spirit, flows in the direction indicated by arrows in full lines, entering the plant at the end indicated by I and leaving it at the end indicated Ii, while the flow of the denser liquid, such, for example, as the solution of caustic soda or sodium hypochlorite is in the opposing direction, as indicated by the arrows in dotted lines. Again, the series of pairs of mixing and separating vessels a, b are con veniently arranged in two rows, the respective mixing and separating vessels a, b of each pair being connected together at or about the middle position of the respective columns by a communicating pipe or pipes at, which may be provided with a valve or valves d and near their lower ends by a return pipe or pipes e, a valve e serving for the variation in the proportion of the denser or washing liquid returned through the pipe e from the vessel 12 to the vessel a. By such means any desired ratio of the denser to the less dense liquid may be maintained in the mixing vessels irrespective of the rates at which the respective liquids are fed into the plant, so that a part of the denser liquid passing into each separa vessel is returned continuously into the mixing vessel. whence it came, any desired part of the denser liquid being meanwhile drawn off continuously into the next mixing vessel of the series. lhc respective positions of the mixing and separating vessels of adjacent pairs alternate so that thus the mixing vessel of one pair may be connected to the separating vessel of the adjacent pair by means of a connecting pipe at the upper end, which pipe may be provided with a valve ,1, while the separating vessel referred to may be connected to the mixing vesso]. of the next pair in succession by a pipe 9 which also may be provided with a valve 9 The pipe 1 it will be understood serves for the passage through it of the less dense liquid such as the petroleum distillate from the separating vessel b to the adjacent mixing vessel a, while the pipe 9 iserves for the flow through it in opposite direc tion of the liquid such as a solution of caustic soda or sodium hypochlorite from the separating vessel b to the adjacent mixing vessel a. Suitable means for indicating t levels of the liquids in mixing and separating vessels may be provided. in the form, for instance, of gauge glasses, floats and indicators, or the like.

In order to in the clear understanding of the invention reference may be made spe oially to Fig .re 10 of the accompanying drawings, in which a plant such as illustrated in Figures 1 and 2 and con icing merely four pairs of mix ing and separating vessels or, b respectively are illustrated. The less dense liquid is fed from a su ply indicated 1/ and leaves the apparatus at 3/ and. the denser liquid is fed from a supply indicated a and leaves the apparatus at .2 The directions of flow of the less dense liquid, the denser liquid and the mixture are indicated respectively by full line. broken line and dotted arrows. The local circulation that is roducedaccording to the invention is clearly shown as taking place by way of the connections d and e between the mixing separating vessels of the respective pairs. By reason of the presence of the connec tins e the denser liquid which separates out in the separating vessels b .rom the mixture entering by the connection (I may be partially passed back to the mixing vessel by way of the connection c.

It will be understood that the mixing vessels a may be provided wit 1 any suitable means for the int .nate admixture of the denser and less dense liquids therein. Thus, for example, illustrated. in Figure 7, a vertical spindle it may be provided for the purpose, set vertically and, if required. supported at its lower end within the vessel eccentrically to the centre vertical line thereof and conveniently in position oppo ite to or away from the position of the connecting pipes cl and e. Janos or blades i. i are mounted upon the spindle it one beneath the other and at an angle one to the other, the vanes or blades being so disposed that a diagonal line across horn is substantially coincident with he axis of the spindle. The vanes may extend from the bottom of the vessel to a position short of the extreme height of the column of liquid in the vessel and the uppermost blade may advantageously be surmounted by an anti vortex disc ii transversely mounted upon the spin dle h.

The mixing vessels a may be advantageously provided with covers or bells 7c (Figure "2) secured to the spindles h and having downwardly extending peripheral edges adaptedfor reception within an annular sealing trough Z on the top plate of the vessels. The respective inlet pipes to the mixing vessels may have their inner ends upwardly diverted whereby the liquid may flow into the vessel and the connecting pipes between the respective mixing and separating vessels may similarly extend into the separating vessels and, where desirable, their inner ends may be closed and an orifice be provided at a suitable part of the inlet pipes. Similarly, the outlet pipes from the separating vessels may extend into the said vessels, as at Figure 8, as pipes with closed ends having inlet orifices on those sides of the pipes that are turned away from the interface of the liquids. With such a form or the outlet pipes the plant may be operated, at a higher rate of fiow than otherwise would be the case, as the zone of emulsion formed in the separating vessels at the inflow point may be allowed to extend without liability of passage of mixed liquids through the outlet pipes.

Any convenient means may be provided for imparting rotary movement to the spindles 7L in the mixing vessels. Thus, for example, each spindle It may carry a worm wheel 11 forming with a worm on a horizontal driven shaft b a reduction gearing to which the drive may be imparted through a belt 1 and pulleys from a driving shaft F1 extendiru length of the plant or serving a number of the mixing chambers and supported in a horizontal position upon a framework of channel or girder section mem bers which comprises also horizontal members extending across and above the mixing chambers and serving to carry bearings by which the spindles h are supported and also to carrythe worm and worm wheel reduction gearing horizontal driven shafts. Any oth r means may however be employed for the same purpose.

It will be understood that certain of the separating vessels, such as those intended for'the washing of a petroleum distillate with a solution of soda, may be provided with a skimming device and tank such as hereinbefore described. For this purpose, as illustrated in Figure 7, a horizontally disposed hollow radial arm in may be provided open or slotted at the upper part andmay be mounted upon a vertically disposed hollow spindlen. The arm m may conveniently be formed as a length of metal tube closed at the outer end and slotted along its length on the upper side, the slot being widened from the inner to the outer end of the tube by the bending in of one of the edges of the slot towards the axis of the tube to an increasing extent along the tube. The tube may be curved in plan to an arc, and may be stayed from the hollow spindle. The upper end of the spindle may be passed through a sleeve mounted on the top plate of the vessel and may be provided at the upper end for the reception of means, such as a handle or a wheel, by which the spindle it may be rotated by hand. The lower end of the spindle n is slidably mount ed within a tubular sleeve 0 set centrally at the vertical adjustment of the position of the hollow spindle 11. by such means as a slidable clip or the like 111 mounted upon its upwardly protruding end and adapted to be secured in any desired position thereon, the horizontally disposed hollow radial arm m may be set into such position radially that on the rotation of the spindle n the arm m may be swept in the plane of the interface of the liquids, whereby on opening the valve 13 in the outlet pipe 12 any accumulation of solid matter at the interface may pass through the hollow arm m down the hollow spindle n and thus be removed with the entraining liquid and may thence pass into a skimming tank q, which may advantageously take a cylindrical form, the pipe p, in which there may be provided a sighting box, being advantageously connected centrally at one end, while, near the bottom, at the opposite end of the tank q a water inlet connection (1 may be provided. A pipe (1 may also be provided at the top of the tank q in a central position to extend over into a position above a second and similar skimming tank q disposed in position beneath the tank q and may serve for the purpose of passing the less dense liquid from the tank q to the tank q the pipe (1 being provided with a valve q and a sighting box. The sighting boxes may be of any suitable construction. As illustrated, each may comprise a glassended drum into which extends the inlet pipe the open end of which is disposed above a funnel provided upon the upper end of the outlet pipe. A further connecting pipe q having a sighting box, is provided beneath the tank q and is connected thereto by a branch q and at one end to the upper part of the tank q valves (1 being provided upon each side of the branch connection The outer end of the connecting pipe 1 serves to convey water and the solids removed from the separating vessel to drain away. An outlet pipe 11 is connected beneath the tank to convey the petroleum distillate and the soda solution to a pump for return into the plant. It will be understood that when the solid matter and liquid collected by the arm m has passed into the tank q as determined by means of the sighting box in the pipe 10, separation takes place so that there is a zone of solid matter above a zone of soda solution, and a zone of the distillate above the solid matter. The soda solution is first permitted to pass into the tank q through the pipe a on the-opening of the valve (1 until solid matter appears in the sighting box. Water is then introduced by way of the pipe o to displace the petroleum distillate through the pipe q and the valve q into the tank q until solid matter appears. The water and solid matter in the tank q is then drained away by way of the pipe q at the valve q When the skimming device is not in use the spindle in may be lowered to the lowest position and a bell or cover, as shown in dotted lines, may be fitted over it, such bell or cover fitting into a sealing trough formed around the bearing sleeve. The spindle 11 may also be provided, as illustrated in dotted lines with an arm similar to the arm m to sweep the surface of the less dense liquid. Alternatively. a second skimming device may be provided for this purpose. Similarly, skimming devices may be provided for the surface of the less dense liquid in separating vessels not provided with the device for the interface.

A settling tank such as hereinbefore described may be provided adjacent to a separating vessel, such as the last vessel of a set used in the acid washing of kerosene or spirit, or in any other position as may be required according to the character of the liqud or petroleum distillate to be treated and for the purpose of preventing the denser or washing liquid of one set being carried over with the distillate and thus mixing with the denser or washing liquid of another set in the course of the treatment. Thus, as shown in Figure 4, seti'ling tanks r, r are provided respectively between the first or soda, set and the second, or acid, set and between the second or acid set, and the third or second soda, set. Such tanks may be provided at the same level as the separating vessel to which they are connected and may be otherwise provided whereby the outlet for the less dense liquid or distillate at the upper part of the separating vessel may discharge into the upper part of the settling tank T The outlet pipe advantageously at the opposite end of the tank and also at the upper part may be sim larly connected with the tank 1', while the outlet from the latter may be connected with the upper part of the first mixing vessel of the succeeding set of mixing and separating vessels in which the distillate may then be washed with the difierent washing liquid. It is advantageous that the outlet from the separating vessel should be formed with n the said vessel by a downwardly curving bend or pipe having the open inlet end disposed at the level from which the less dense liquid is to be drawn and connected outside the vessel to a conduit or pipe disposed at a lower level which is connected to the settling tank 1' by an upwardly curving bend delivering the less dense liquid into the said tank at the same level as that from which it was withdrawn from the separating vessel. The same arrangement of piping may be used between the tank r and the succeeding mixing vessel a, except that the delivery of the less dense liquid into the said vessel may be efiiected by a weir box or the like instead of a pipe bend. Any of the denser liquid subsiding at the bottom of the tank or tanks may be separately withdrawn or may be returned to the lower part of the last mixing vessel of the first set as illustrated. It will be understood that it is desirable to provide additional settling space at those positions in the plant where a change over of the denser or washing liquid takes place and, while each space would be provided by enlarging the dimensions of the final separating vessel of a set, it is generally preferable to avoid this by the provision of additional settling tanks as described.

Such a process and plant as hereinbefore described may, for example, be employed for the washing or treatment of motor sp rit first with a solution of a hypochlorite and secondly with a solution of caustic soda, such a plant being illustrated by way of example in Figures 1 and 2 in which three pairs of mixing and separating vessels may be used for the hypochlorite washing and eight for the wash ng with soda solution.

It will be understood that the raw spirit enters the first mixing vessel a of the first pair I and thence flows in succession through all the connected vessels a. b emerging finished at the separating vessel of the last pair of vessels II. Fresh hypochlorite solution is run into the third or the last mix ng vessel of the first section of the plant and flows in counter-current to the spirit, the spent hypochlorite solution emerging from the first separating vessel of the pair I.

The solution of soda enters the mixing vessel at that end of the plant at which the finished spirit emerges and flows in counter-current to the spirit until it is spent and discharged from the fourth separator at the end of the second section of the plant. It is essential that the means for feeding the spirit, the hypochlorite solution and the soda solution should be under carefully regulated control, by valves or cocks provided for adjustment against graduations. The volume of spirit to hypochlorite solution or soda solution respectively in each mixln vessel or separating vessel may be approximatmy 50:50. This ratio is maintained by controlling the flow by means of valves between the respective pairs of mixing and separating vessols and at the end of the plant. The rate of feed (the spirit being 1,000 volumes per hour) may be, for example, approximately volumes for the hypochlorite solution and 2 volumes for the soda solution. As an alternative to the use of soda solution, a solution of lime may be used. This has the advantage of being cheaper, and having quicker action so that smaller separators and smaller plant generally may be used, while the emulsion formed with the less dense li uid is more readily separated. At the same time, the lime solution requires considerably more water for its preparation so that larger plant and extra labour are required and pumping costs in supplying the solution to the plant are increased. In the use of lime the rate of feed for every 10 volumes or" spirit per hour may be 30 volumes oi calcium hypochlorite solution of 1 normal strength and 400 volumes of saturated lime water (approximately .04 N alkali), fed together the first section of the plant and volumes of lime water in the second section of the plant.

It will be understood that other chemicals that may be suitable for the purpose, such as sodium plumbiie or Doctor solution, may be used in such plant, the sections of the plant and the dimensions of the mixing and separating vessels being determined according to the requirements of each particular application.

Again, the process and plant illustrated in Fig ures 3 and i may be used for the continuous countercurrent treatment of kerosene successively with soda solution, concentrated sulphuric acid and soda solution. In order to avoid the entrainment of small quantities of soda with acid or of acid with soda in the stream of kerosene, extra settling space is provided in the form of tanks in the manner hereinbefore described through which tanks the kerosene fiows without turbulence and in which it deposits such ontrained chemical which may be returned by a pipe to the mixing vessel whence it came.

It will be understood that for the washing of kerosene the plant illustrated in Figures 3 and 4 may be provided in three sections, that is to say, there may be three pairs of mixing and separating vessels for the first soda washing, five pairs of mixing and separating vessels for the acid treatment and three pairs of mixing and separating vessels for the final soda washing and two settling tanks 1', r may be provided respectively at the end of the first soda washing section and at the end of the acid section of the plant, it

6 being understood that the kerosene passes from the soda washing section of the plant to a mixing vessel containing acid and kerosene and that'in order to avoid any possibility of flow in the wrong direction that is of acid and kerosene into the soda solution, the stream of kerosene may be caused to flow over a shallow weir of two or three inches high and that a similar weir may be provided where the kerosene flows from the acid section of the plant to the second soda washing section; It will furthermore be understood that the volume ratio of soda solution to kerosene in each separating vessel and mixing vessel may be approximately 50250 in the soda section of the plant and of acid to kerosene about 30:70 in the acid section, and these ratios are maintained by valves in the manner described. The feeds may, for example, be approximately (taking kerosene as 1,000 volumes per hour) soda (each section)3 volumes, acid- 7 volumes.

In the passage of the kerosene from the acid section of the plant to the second soda section by way of settling tanks 1', T the kerosene retains traces of acid when passing into the first mixing chamber oi the soda section and this and the following separating vessel, or at least the latter, is lead-lined while the inlet from the said separating vessel to the following mixing vessel is advantageously provided as an inlet pipe, preferably of gun metal, extending into the mixing chamber to carry the kerosene away from the walls of the vessel. taken with the first mixing vessel, or the latter, as hereinbefore stated, may be lead-lined. In the use of lime solution instead of soda for every 1000 volumes per hour of kerosene passing through the plant '7 volumes of sulphuric acid (oleum with 20% free $03) and 300 volumes of lime water (approximately .04 N alkali) may be employed.

Again, the process and plant illustrated by way of example in Figures 5 and 6 may be used for the successive counter-current treatment or" white spirit with soda solution, acid and soda solution. After the treatment, the spirit may be distilled and may be given a final treatment with a solution of hypochlorite containing soda. In such a case a plant similar to that last before referred to may be employed in which settling tanks are provided between the first soda and acid sections and between the acid and the second soda sections of the plant respectively, it being understood that the final treatment with hypo chlorite solution containing soda may be effected in a section of the plant comprising for example three pairs of mixing and separating vessels. ment may be approximately the same as in that carried out in the plant last before referred to. The volume ratio of white spirit to hypochloritesoda solution may be approximately 50:50 in the separating vessels and in the mixing vessels and the respective rates of feeding, for example, about 1,000:150.

In using lime water for the treatment of the white spirit, for every 1000 volumes of the spirit passing through the plant 20 volumes of lime water may pass through the first section of the plant, 12 volumes of sulphuric acid (oleum) may pass through the second section, and 200 volumes of lime water through the third section. After re-distillation, the spirit is treated in a section of the plant through which 15 volumes of l N hypochlorite may pass and in a final stage through which 50 volumes of lime water may pass.

It will be understood that the head may be increased by means of a pump or otherwise and that the units or pairs of vessels may be arranged at The same precaution may be The ratios of volumes in such a treat different levels, the flow of one liquid being effected under gravity, while the other liquid is raised by a pump. It will however be understood that it is one of the objects of the invention ordinarily to avoid the use of pumps for the'purpose of maintaining the head or for effecting or assisting the counter-current flow of the liquids.

It will thus be understood that the process of the invention may be carried out in a plant of a capacity varying according to the character of the treatment to be carried out and the volumes of the respective liquids, and that the controlling valves may be adjusted to determine the period of contact and the ratio of the respective liquids to be maintained in the respective vess ls irrespec tive of the rate at which the liquids are fed to the plant.

We claim:

1. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a series of pairs of mixing and separating vessels disposed at the same level, means of communication between the mixing and separating vessels of each pair for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids sep-- arate according to their relative densities, means for effecting the transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in one direction, means for effecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in the direction opposite to that followed by the less dense liquid, andmeans to maintain a determined ratio of the denser to the less dense liquid in the mixing vessels irrespective of the rate at which the respective liquids are fed to the series of pairs of mixing and separating vessels and independently of the counter-flow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels, substantially as described.

2. Apparatus for the treatment or" a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a series of pairs of mixing and separating vessels disposed at the same level, means of communication between the mixing and separating vessels of each pair for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities, means for effecting the transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession one direction, means for eiiecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next insuccession in the direction opposite to that followed by the less dense liquid, and means for effecting the return flow of the denser liquid from the separating vessel to the mixing vesselof each pair of vessels, and independently of the counter-flow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels substantially as hereinbefore described.

3. Apparatus for the treatment of a liquid, moreserving for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities and produce a head of the respective liquids inthe separating vessels, means for effecting the transfer of the less dense liquid in the separating vessels to the mixing vessels of the pair of vessels next in succession in one direction, means for effecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in the direction opposite to that followed by the less dense liquid, and means of communication between the mixing and separating vessels of each pair towards the lower end of the said vessels for the return flow of the denser liquid from the separating vessels to the mixing vessel of each pair of vessels, and independently of the counter-flow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels substantially as hereinbefore described.

i. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a series of pairs of mixing and separating vessels disposed at the same level, means of communication between the mixing and separating vessels of each pair for a passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities, means in the separating vessels to effect the removal from time to time of solid matter accumulating at the interface of the denser and less dense liquids in the separating vessel, means for effecting a transfer of the less dense liquid in the separating vessels to the mixing vessels of the pair of vessels next in succession in one direction, means for effecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in the direction opposite to that followed by the less dense liquid, and means for effecting the return flow of the denser liquid from the separating vessel to the mixing vessel of each pair of vessels, and independently of the countei ilow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels substantially as hereinbefore described.

5. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a series of pairs of mixing and separating vessels disposed at the same level, means of communication between the mixing and separating vessels of each pair for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities a rotatable collector of solid matter accumulating at the interface of the denser and less dense liquids in the separating vessels, the said collector being adjustable in elevation according to the position of the interface, means whereby the liquid and solid matter withdrawnby the collector may be separated, means for effecting the transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in one direction, means for effecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in the direction opposite to that followed by the less dense liquid, and means for effecting the re-. turn flow of the denser liquid from the separating vessel to the mixing vessel of each pair of vessels and independently of the counter-flow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels, substantially as hereinbefore de scribed.

6. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a series of pairs of mixing and separating vessels disposed at the same level, means of communication between the mixing and separating vessels of each pair for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities, adjustable collectors provided in the separating ve. sels for the removal of solid matter accuinulating at the interface of the denser and less dense liquids, a vessel into which the said collectors deliver the solid matter and the entrained liquid which separate in zones, a second vessel communicating with the first vessel and receiving the denser liquid therefrom, other means of communication between the vessels whereby the less dense liquid may pass to the second vessel, means respectively for removing the solid matter from the first vessel and the liquid from the second vessel, means for effecting a transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in one direction, mean for effecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in the direction opposite to that followed by the less dense liquid, and means for effecting the return flow of the denser liquid from the separating vessel to the mixing vessel of each pair of vessels and independently of the counter-flow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels, substantially as hereinbefore described.

'7. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, according to claim 6, comprising a collector for the removal of solid matter accumulating at the interface of the denser and less dense liquids in the separating vessels, the said collector being adjustable in elevation according to the position of the said interface, a vessel in communication with the said collector to receive the solid matter and the entrained liquid and to serve for the separation thereof into three zones, a second vessel disposed at a level lower than the first vessel and communicating with the lower part thereof forthe transfer of the separated denser liquid to the second vessel, means connected to the first vessel for the introduction of a medium by which the less dense liquid may be ejected therefrom, means of communication between the first and second vessels by which the less dense liquid ejected from the first vessel may pass to the second vessel and means for respectively discharging the two vessels of the solid matter and the denser and less dense liquids, substantially as hereinbefore described.

8. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a plurality of series of pairs of mixing and separating vessels disposed at the same level, means of communication between the mixing and separating vessels of each pair for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities, means for effecting the transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in one direction, means for effecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in the direction opposite to that followed by the less dense liquid, means for efiecting the return fiow of the denser liquid from the separating vessel to the mixing vessel of each pair of vessels and independently of the counter fiow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels and tanks connected between certain of the separating vessels and thesucceeding mixing vessel in the directionof flow of the less dense liquid through the respective pairs of vessels, the said tanks being connected for the passage of the less dense liquid from the one vessel to the other vessel and secure a settlement of denser liquid therein, substantial- 1y iereinheiore described.

9. Apparatus for the treatment. of a liquid, more especially petroleum distillate with another immiscible liquid, comprising a series of pairs of iixing and separating vessels disposed at the ie level, means of communication between inixing and separating vessels of each pair for the passage of intermixed liquids from the; mixing to the separating vessels in which the liquids separate according to their relative densities, means for effecting the transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succos-son in one direction, means for effecting the transfer of the denser liquid in the separating vessels to the in ng vessels of the pairs of vessels next in succession in the direction opposite that followed by the less dense liquid, agitating devices provided in the said mixing vessels for effecting intermixture of the denser and less dense liquids and means for eifecting the return flow of the denser liquid from the separating vessel to the mixing vessel of each pair of vessels and independently or" the counter-low of the two liquids thrcugh the series of pairs of vessels resulting from the head in the separating vessels, substantially as hereinbefore described.

10. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a series of pairs of mixing and separating vessels disposed at the same level, means of communication between the and separating vessels of each pair for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities, means for efiecting the transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in one direction, means for effecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in the direction opposite that followed by the less dense liquid, vertical spindles disposed eccentrically within the mixing vessels, mixing blades provided fixedly upon said vertical spindles, means for effecting the rotation of the vertical spindles and means for effecting the return flow of the denser liquid from the separating vessel to the mixing vessel of each pair of vessels and independently of the counter-flow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels, substantially as hereinbefore described.

11. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, according to claim. 10, having means for effecting rotation of the vertical spindles provided in the mixing vessels comprising driven members fixed upon the said spindles, corresponding driving members co-operating with the said driven members and a common driving member transmitting movement to the said driving members of the respective vertical spindles, substantially as hereinbefore described.

12. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a series of pairs of mixing and separating vessels disposed at the same level, means of communication between the mixing and separating vessels of each pair for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities, means for efiecting the regulated transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in one direction, means for effecting the regulated transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succemion in the direction opposite that followed by less dense liquid, and means for effecting the regulated return flow of the denser liquid from the separating vessel to the mixing vessel of each pair of vessels, and independently of the counter-fiow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels substantially as hereinbefore described.

13. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, comprising a series of pairs of mixing and separating vessels disposed at the same level, means of communication between the mixing and separating vessels of each pair for the passage of intermixed liquids from the mixing to the separating vessels in which the liquids separate according to their relative densities, means for eiiecting the transfer of the less dense liquid in the separating vessels to the mixing vessels of the pairs of vessels next insuccession in one direction, mean for effecting the transfer of the denser liquid in the separating vessels to the mixing vessels of the pairs of vessels next in succession in the direction opposite that followed by less dense liquid, and means for effecting the regulated return flow of the denser liquid from the separating vessel to the mixing vessel or" each pair of vessels, and independently of the counter-flow of the two liquids through the series of pairs of vessels resulting from the head in the separating vessels substantially as hereinbefore described.

14. Apparatus for the treatment of a liquid, more especially a petroleum distillate with an other immiscible liquid, according to claim 8, comprising a plurality of tanks connected in succession and on the one hand to the separating vessel of one pair of vessels, and to the mixing vessel of the adjacent succeeding pair of vessels for the flow therethrough or" the less dense liquid and means for the return of denser liquid separating out in the said tanks to the mixing vessel corresponding to the said separating vessel of the first pair of vessels, substantially as hereinbefore described.

15. Apparatus for the treatment of a liquid, more especially a petroleum distillate with another immiscible liquid, according to claim 10, comprising a worm wheel on each vertical spindle, a driving worm engaging said worm wheel, said worm being mounted upon a spindle, said vertical spindle together with the worm wheel and worm spindle being supported independently of the corresponding mixing vessel, a driving shaft common to a number of mixing vessels, pulleys provided respectively on a common driving shaft and upon the worm spindles and belts for transmitting the drive from the driving shaft 165 to the worm spindles, substantially as hereinbefore described,

16. A process for the treatment of a liquid, more especially a petroleum distillate, with another immiscible liquid, consisting in mixing the 11;] liquids, causing the liquids to separate out by reason of their relative densities in a location other than that in which mixing occurs and under the head of the separated liquids produced causing the transfer of the less dense liquid in one direction of a path of fiow and of the denser liquid in the other direction of the path of flow and simultaneously and independently returning a portion of the denser liquid from the location of separation to the location of mixing, the said 121) steps of mixing and separation with a return flow being continued repeatedly throughout the path of flow.

ALFRED EWART HOLLEY.

OWEN EDWIN MO'IT. 125