US1965225A - Fractionating tower control system - Google Patents

Description

J. H. `ERTER FRACTTONATING TOWER CONTROL SYSTEM A" 3 9 l 3., .W u J Filed March 14,1952 2 Sheets-sheet 1 WG QQQQ hv ATTORNEY.

2 Sheets-Sheet 2 J. H. ERTER FRACTIONATING TOWER CONTROL SYSTEM Filed March 14, 1932 July 3, 1934.

Patented July 3, 1934 y UNITED STATES PATENT lOFFICE- FRACTIONATING TOWER CONTROL SYSTEM John H. Erter, New York, N. Y., assigner to 'Alea Products Incorporated, a corporation of Dela- Application March 14, 1932, Serial No. 598,714

z claims. (cl. 2oz-159) My invention relates to an improvement in a control system for controlling the quality of the -V side streams being withdrawn from a fractionating tower of the bubble type wherein a liquid -5 product is withdrawn from one or more fractionating zones intermediate the top and bottom of the fractionating tower. It is known that the temperature at any point within a fractionating tower is dependent upon the quantity of reflux owing at that point, assuming that the entrance vapor temperature and exit vapor temperatures are'maintained constant. It follows, therefore, that if a constant temperature is maintained at a point within the tower, the quantity of reflux 16 liquid flowing at that point will be constant. By controlling the rate of withdrawal of a side stream by means of a control valve system, it is possible to control and maintain a uniform ternperature within the fractionating tower which 20 will give a constant reflux flow within the column.`

It is obvious that, if we maintain the temperae ture and rate of reflux flow at a constant, at a point within a fractionating tower, the quality of the side stream product being withdrawn from that point will necessarily be of a uniform nature.

It is known that control valves may b'e placed in the line through which a side stream is being withdrawn at a point in proximity to the tower. When this practice is followed, it is necessary for an operator to observe the temperature change resulting from manipulation of the control valve at the control board and then return to the remote position in proximity to the tower to 'make necessary adjustments. The control valves may be placed in the withdrawal line from the stripping tower where the side streams are being stripped by steam but, as in the practice of placing the control valves against the tower, this 'will necessitatev considerable Ashuttling by an op- 40 erator from the control board to the control valve and back again before satisfactory adjustment is achieved. Y

One object of my invention is to provide a method of controlling the rate of reflux flow Within the tower by varying the rate of withdrawal of a side stream from said tower.

Another object of my invention is to provide a method whereby a constant rate of withdrawal of a side stream is controlled at a point in proximity to a pyrometer.

A further object of my invention is to provide a system for controlling therate of ow of a side stream being withdrawn `from the fractionating tower in an expeditious and efficient manner.

Another object of my invention is to provide a means whereby an operator may make changes in the rate of vwithdrawal of a side stream from'a fractionating tower and observe the temperature change resulting from such change without leaving the control board and to enable furtherhnecessary adjustments to be made from the same point.

Another object of my invention is to provide an automatic means whereby'` the rate of ilow of a side stream being withdrawn from a fractionating tower will be automatically varied to maintain the temperature at a point within'the tower between given limits.

In the accompanying drawings which form partl of the instant specification which is to be read in connection therewith:

Figure 1 illustrates a schematic showing of one arrangement embodying a mode of carrying out my invention. r

Figure 2 is a detail View showing an arrange- 75 ment for operating a control valve from the control board.

Figure 3 is a schematic view of an automatic means for maintaining temperature.

In general, my invention is applied to a frac' 80 tionating system in which heated vapors are led to a fractionating tower where they are separated into various portions having a graduated series 0f boiling points. The fractionating tower is of the bubble type wherein the condensate collects in a series of pools and overflows downwardly while the vapors and light constituents rise upwardly and pass from the tower overhead. A number of side streams are withdrawn from respective* pools of condensate and led to respective stripping towers. The stripping towers are well known in the art and consist of a fractionating tower into which nconned, live superheated steam is introduced to strip the side stream of its lighter constituents. The residue of the side stream is withdrawn from the bottom of the stripping tower and condensed and collected for use in lubricating oils and the like.

I provide a means for controlling the rate of withdrawal of the stripped side stream, that is, the residue from the stripping tower. It will be appreciated that, if the outlet from the stripping tower is closed that the residueconsisting of the stripped side stream lwill collect in the bottom of the stripping tower and form a pool. I pro; vide a float controlled valve in the line which conducts the side stream from the fractionating tower to the stripping tower. It will be appreciated that as the level of the residue within the stripping tower rises the floatY of the float control valve will also rise. This action is used to close a valve in the line through which the side stream flows from the fractionating tower. Thus a variation of the rate of withdrawal of the residue from the stripping tower will be reflected in the height of level of the pool within the stripping tower which in turn will control the rate at which the side stream is being withdrawn from the fractionating tower. Within the fractionating tower at suitable points are placed a series of thermocouples which are connected to respective indicating pyrometers placed n appropriate positions upon the control board. If it be desired for example to produce a heavier fraction, it will be necessary to withdraw the side stream from the fractionating tower at a higher or greater rate. When a side stream is being Withdrawn at a slower rate, the amount of reflux flowingat that point will be increased and accordingly the temperature will fall resulting in a lighter product. It follows, therefore, that when a heavier cut is desired all that is necessary is to move the control valve to raise the temperature at a point within the tower. I place the control for the valve upon the control board and interconnect it with the valve in the line through which the stripping tower residuum ows by any suitable mechanical connection.

Thus it will be seen that from a position at the control board an operator may observe the temperature existing at a given point within the tower andat the same point control the system temperature in order to obtain a given quality of product and maintain it at a uniform quality.

' In connection with the method of control described it is to be understood that anim-portant feature of the operating control mechanism is the constant headmaintained by means of the liquid level controller which operates the valve controlling the infiowing liquid to the stripper tower. The variation in the liquid level within this tower has negligible effect on the total head of liquid forcing flow through the control valve 16. The theory of flow in this apparatus is dey pendent on this constant head with variable oriilce opening in the control valve. For any given orifice size with this constant head a constant uniform flow of liquid can be maintained which will, in turn, result in a constant temperature and a uniform quality product from the takeoff point on the fractionating tower.

Referring now to Figure 3: Instead of using an indicating pyrometer I may use an automatic arrangement in which the thermocouple, 3, is led to a galvanometer, 29. The galvanometer needle is connected to the negative pole of the battery, 36. The galvanometer is calibrated to register temperatures. On-the face o'f the galvanometer I provide a peripheral groove, 30, in which is slidably mounted a pair of spaced electrical contacts, 31 and 32, adapted 'to straddle the galvanometer needle, 33, and withA which the galvanometer needle is alternatively able to contact. The contacts are placed inseries with respective electromagnets, 34 and 35', and with the positive pole of the battery, 36. The magnets are disposed in opposed relationship. Between the adjacent opposing poles of the magnets I place a movable armature, 37, held in mid-position by springs, 38. It will be apparent that if the galvanometer needle contacts with one contact a circuit will be completed from the positive pole of the lbattery through one solenoid through the galvanometer needle and to the negative pole of the battery. A similar circuit will be completed when the S51- vanometer needle contacts with the other electrical contact.

It will be appreciated, furthermore, that the armature will be attracted to the energized solenoid. I provide two pairs of contacts disposed on opposite sides of the armature with which the armature is adapted to contact. It is to be understood that the armature is made of conducting material. A portion vof the armature is connected to one pole of a second battery, 39, or`

suitable source of electromotive potential. One pair of contacts, 46, is connected to one binding post, 40, of lan electric motor, 4l, The other pole, 43, of the electric motor is connected to the other pole of the said second battery, 39. It will be readily appreciated that, if the' armature contacts with either of said rst pair of contacts that a circuit will be completed through the electric motor whichwill cause it to operate` The motor shaft, 45, carries a slidably mounted fitting 54 having a pairv of integral bevel gears, 42 and 44. The fitting 54 is slidably mounted but prevented from relative rotation with shaft 45 by key 55. The second pair of contacts, 47, which are placed upon opposite sides of the armature are connected respectively to a pair of oppositely disposed solenoids, .48 and 49, so that when the armature contacts with one solenoid, it will be energized and when the armature contacts with the opposite contact, its respective solenoids will be energized. Between the second pair of oppositely disposed solenoids, I dispose a second armature, 50, adapted to swing back and forth depending upon the respective energization of the solenoids. This last named movable armature carries a fork, 5l. The fork embraces integral ring 56, which is integral with a fitting 54 which is adapted to slide on shaft 45 but is keyed to said shaft for rotation therewith. Thus bevel gears 42 and 44 are positioned to engage alternately bevel gear 52, which is keyed to the valve shaft 53. The shaft 53, upon which the bevel gear 52 is lgeyed, is the control shaft for the conl trol valve, 16.

From the foregoing, it will be understood that, A

when the temperature within the fractionating tower drops below a predetermined point, contact will be made by the galvanometer needle with 'one electric contact which will energize one solenoid to attract the armature. This will close two circuits, namely the motor circuit and the forked-armature circuit. The forked-armature will cause one of the two gears 42 or 44 to engage one side ofthe gear mounted on the valve shaft. The motor shaft then will drive the gearing to turn the control valve to decrease the rate of withdrawalof the bottom from the stripping tower. This will raise the level of the pool within the stripping tower which, in turn, will operate the float valve to decrease the rate oi withdrawal from the fractionating tower, which in turn will lower the temperature within the fractionating tower at a given point. When the temperature rises the opposite contact of the galvanometer will cause the solenoid to move the armature in the opposite direction to 'energize the opposite fork-actuating solenoid to move the fork in the opposite direction .to engagethe other side of the bevel gear on the motor shaft to turn the valve inlthe opposite direction to have the opposite eiect.

While I have described one method of effecting an automatic control of the rate of withdrawal of the side stream, any suitable method may be used.. f

The vaporized oil leaves a pipe still or suitable heat exchange apparatus and enters the fractionating tower, 1, through oil inlet, 2. It is to be understood that the fractionating tower may be of any suitable type and may be operated at any pressure, atmospheric or sub-atmospheric. Thermocouples, 3,' are placed within respective fractionating zones from which side streams are withdrawn through lines 4. It is to be understood that, while I have illustrated a single thermocouple and a single side stream line' that any number of side streams with' complementary thermocouples may be installed'.l 'I'he side stream may iiow directly into the stripping tower, 5, through line 4, in the event that it is not desired to use my control system. A U-branch line 6 is provided with the legs straddling. the valve 7. This last mentioned valve is normally closed when my control system is in operation. At the bend of the U, I provide a valve 8, controlled by a float 9, within the stripping tower 5. Superheated steam enters the stripping tower through pipe 10, and is allowed to escape to strip the side stream of its lighter constituents whichescape from the stripping tower through the overhead l1, whence they join the lighter vapors from the fractionating tower in line 12 andl flow to the condenser 13.v The residue that is the side stream stripped of its lighter fractions is withdrawn from the bottom of the stripping tower through line 14 and allowed to pass through cooler 15, which may be of any suitable construction, through control valve 16, to storage. In the drawings, it will be noted I have placed the cooler below the level of thel stripping tower so that the flow of the residue from the stripping tower will be effected by gravity. .The control valve 16 is connected by a shaft 1'1, through'suitable gearing 18, to a pointer arm 19. The pointer arm 19 carries a shaft 20 on which is mounted a hand wheel 2l. The shaft 20 carries a gear 22 which engages a segmental arcuate rack 23, mounted on the control board 24. The pointer is adapted to indicate a series of graduations 25 on the control board 24. Mounted in proximity to the hand wheel4 21 is a pyrometer 26 connected to thermocouple through suitable leads 27 and 28. It is to be understood that as many control Valves with their respective control wheels' and pyrometers are mounted on the control board as there are side streams.

It will be understood from the foregoing description that, when it is desired to take a heavier out all that is necessary is tomanipulate the control wheel on the control board to raise the temperature which will be indicated on the pyrometer 26 so that a closer control of the qualityv of the product may be effected from a single point. Closing the control valve partially restricts the rate of flow of the residue. 'Ihis will cause the level of the residue pool within the bottom of the stripping tower 29 to raise leaving the float 9 and partially closing the valve 8 and reducing the rate of ow of the side stream 4. v

It will be seen that I have provided a method for maintaining a uniform quality of the sidel stream product by means of a temperature control instead of by a reflux lcontrol within the tower as has been the customary practice. It will be appreciated that I have accomplished the objects of my invention.

It is to be understood that certain features, sub-combinations and operations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of my claims. It ris further obvious that Various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specic details shown and described.

Having thus described my invention, what I claim is: v

1. A fractionating control system including in combination a fractionating tower, a side stream eduction line, a valve interposed in said line, a stripping tower for said side stream, a reservoir in said stripping tower, a float-controlled valve -in said eduction line adapted to be actuated by the level in said reservoir and temperature controlled means for varying the level of liquid in said reservoir.

2. In a fractionating tower side stream control.' the combination including a fractionating tower and a stripping tower, trays in said fractionating tower on which pools of condensate are adapted to collect, a line connecting one of said trays with the stripping tower for withdrawing from said tray a side stream to be stripped, said line being connected to said fractionating tower4 solely at said tray, valve means in the withdrawal line for controlling the rate of condensate withdrawal from said tray, thermostatic means within the fractionating' tower adjacent said tray, and means responsive to said thermostatic means for opening said valve means as the temperature of said thermostatic means decreases and for closing said valve means as the temperature of said thermostatic means increases ,whereby a product of uniform quality is obtained.

JOHN H. ERTER.

DISCLAIMER New York, N. Y. FRACTIONATING TOWER CONTROL by the assignee, American comott've Company.

Herelbg'enters this disclaimer to claim 2 of said Letters Patent.

jcial Gazette January 80, 1940.]

The vaporized oil leaves a pipe still or suitable heat exchange apparatus and enters the fractionating tower, 1, through oil inlet, 2. It is to be understood that the fractionating tower may be of any suitable type and may be operated at any pressure, atmospheric or sub-atmospheric. Thermocouples, 3,' are placed within respective fractionating zones from which side streams are withdrawn through lines 4. It is to be understood that, while I have illustrated a single thermocouple and a single side stream line' that any number of side streams with' complementary thermocouples may be installed'.l 'I'he side stream may iiow directly into the stripping tower, 5, through line 4, in the event that it is not desired to use my control system. A U-branch line 6 is provided with the legs straddling. the valve 7. This last mentioned valve is normally closed when my control system is in operation. At the bend of the U, I provide a valve 8, controlled by a float 9, within the stripping tower 5. Superheated steam enters the stripping tower through pipe 10, and is allowed to escape to strip the side stream of its lighter constituents whichescape from the stripping tower through the overhead l1, whence they join the lighter vapors from the fractionating tower in line 12 andl flow to the condenser 13.v The residue that is the side stream stripped of its lighter fractions is withdrawn from the bottom of the stripping tower through line 14 and allowed to pass through cooler 15, which may be of any suitable construction, through control valve 16, to storage. In the drawings, it will be noted I have placed the cooler below the level of thel stripping tower so that the flow of the residue from the stripping tower will be effected by gravity. .The control valve 16 is connected by a shaft 1'1, through'suitable gearing 18, to a pointer arm 19. The pointer arm 19 carries a shaft 20 on which is mounted a hand wheel 2l. The shaft 20 carries a gear 22 which engages a segmental arcuate rack 23, mounted on the control board 24. The pointer is adapted to indicate a series of graduations 25 on the control board 24. Mounted in proximity to the hand wheel4 21 is a pyrometer 26 connected to thermocouple through suitable leads 27 and 28. It is to be understood that as many control Valves with their respective control wheels' and pyrometers are mounted on the control board as there are side streams.

It will be understood from the foregoing description that, when it is desired to take a heavier out all that is necessary is tomanipulate the control wheel on the control board to raise the temperature which will be indicated on the pyrometer 26 so that a closer control of the qualityv of the product may be effected from a single point. Closing the control valve partially restricts the rate of flow of the residue. 'Ihis will cause the level of the residue pool within the bottom of the stripping tower 29 to raise leaving the float 9 and partially closing the valve 8 and reducing the rate of ow of the side stream 4. v

It will be seen that I have provided a method for maintaining a uniform quality of the sidel stream product by means of a temperature control instead of by a reflux lcontrol within the tower as has been the customary practice. It will be appreciated that I have accomplished the objects of my invention.

It is to be understood that certain features, sub-combinations and operations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of my claims. It ris further obvious that Various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specic details shown and described.

Having thus described my invention, what I claim is: v

1. A fractionating control system including in combination a fractionating tower, a side stream eduction line, a valve interposed in said line, a stripping tower for said side stream, a reservoir in said stripping tower, a float-controlled valve -in said eduction line adapted to be actuated by the level in said reservoir and temperature controlled means for varying the level of liquid in said reservoir.

2. In a fractionating tower side stream control.' the combination including a fractionating tower and a stripping tower, trays in said fractionating tower on which pools of condensate are adapted to collect, a line connecting one of said trays with the stripping tower for withdrawing from said tray a side stream to be stripped, said line being connected to said fractionating tower4 solely at said tray, valve means in the withdrawal line for controlling the rate of condensate withdrawal from said tray, thermostatic means within the fractionating' tower adjacent said tray, and means responsive to said thermostatic means for opening said valve means as the temperature of said thermostatic means decreases and for closing said valve means as the temperature of said thermostatic means increases ,whereby a product of uniform quality is obtained.

JOHN H. ERTER.

DISCLAIMER New York, N. Y. FRACTIONATING TOWER CONTROL by the assignee, American comott've Company.

Herelbg'enters this disclaimer to claim 2 of said Letters Patent.

jcial Gazette January 80, 1940.]

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