US1619440A - Pressure still - Google Patents

Description

1927. March 1 A. $51.01!

PRESSURE STILL Filed Sept. 15

INVENTOR "5%: e ATTORNEYS sure stillis provided with Patented Mar. 1, 1927.

UNITED STATES PATENT @FFIGE.

ALFRED J. SLOAN, OF KANSAS CITY, KANSAS, ASSIGNOR TO SINCLAIR BEFINING' COM- PAN Y, OF CHICAGO, ILLINOIS, A CORPORATION OF MAINE.

. PRESSURE STILL.

Application filed September 15, 1923. Serial No. 662,797.

This invention relates to in iprovements in pressure stills for cracking heavier hydrocarbons to'produce lighter hydrocarbons, such as gasoline or pressure distillate, therefrom. p

The invention includes, in addition to the improved pressure still construction, an improved automatic relief valve specially adapted for use therewith.

in pressure stills for cracking heavier hydrocarbons. the oil is heated in the still to a cracking temperature under a high pressure, and the vapors resulting from the cracking operationeither with or without refluxing, are withdrawn to a condenser. Such pressure stills are operated at high pressures, for example, at pressures around 90 to 125 lbs. per square inch. where gas oil is subjected to cracking. whilemuch higher pressures may be used where lighter oils such as kerosene are subjected to cracking, pressures around 300 to 32-5 pounds being sometimes used. and even much higher pressures, around 600 to 700 pounds per square inch.

In order to protect such stills in case ex-' cessive pressure develops therein. a safety valve is usually provided which will dis- (liar-grv into the atmosphere in case of abnormal rise in pressure, thus relieving the 'iressure and reducing the danger ofexplosion and its attending hazards. The vapors contained in such pressure stills are heated to such a hightemperature that they will take fire siontaneouslv if dischar 'ed directly into the air. and precautions are aceordingly necessary to cool the vapors to prevent their spontaneous ignition in case relief of vapors through the safety valve should. take place.

lVhere the condensers for the pressure stills are maintained at atmospheric pressure, or at a predetermined pressure. between that of the pressure still and at1nospheric,-a pressure reducing and regulating valve is usually provided between the still and condenser. and this valve is operated to regulate the pressure in the still and to promote the withdrawal of the 'craclied vapors in regulated amount therefrom. \Vhere the presa reflux tower,

this pressureregulating valve is commonly provided between the reflux tower and the condenser.

In the operation of the pressure stills such pressure regulating and reducing, valves require more or less constant observation and attention on the part of the operator, who adjusts the valve to maintain a substantially constant pressure in the still and to release the 'apors in regulated amount therefrom. In case of lack of attention on the part of the operator an abnormal pressure may be built up in the pressure still, and, in case this pressure becomes excessive release of vapors through the safety valve to the at mosphere will take place. The release of pressure in this way is not only wasteful, but it seriously interrupts the proper operation of the still, as it usually results in a diminution of pressure to a point consider ably below that of normal operation, with the result that a larger amount of heavier hydrocarbon vapors than the vapor system of the still is designed to handle is immediately vaporized and a considerabl: amount may be lost to the atmosphere. and the still will then require to be again brought up to normal operating condition.

The present invention provides an improved PlOrSllll still coilstructhm inwhich.

a by-pass is provided around the pressure reducing or regulating valve. with an antematic pressure reduringyalve in such bypass which will operate upon a predetermined increase in pressure above -=that of normal operation. and which will serve to relieve the excess pressure by the discharge of vapors from the high pressure side of the regulating valve to the/low pressure side. Such vapors as are discharged from the still to relieve the excess pressure will accordingly he passed to the condenser and will be recovered alone; with the pressure distillate. although they may be separately recovered by providingthe automatic pressure reduc ing valve with a separate discharge line and condenser.

The automatic pressure relief valve is advantageously enclosed entirely within the. casing". so that there are no stufiing boxes or outside connections or adjustments through which leakage can take place. When such adjustments or outside connec-' tions are provided, they are arranged on the discharge side of the valve where a rela-' tively low pressure will exist even during the operation of the valve.

The improved automatic relief valve of i the invention is specially designed and contion thereof, it bein structed so that when opened it will give a quick release of the excess pressure but so that it will be quickly closed when the excess pressure has been relieved.

The automati relief valve is moreover so adjusted as to open before the usual safety valve on the still so that, except in the case lowing claims in which I have endeavored to distinguish it from the prior: art as known to me, it being my purpose to cover the novelty disclosed in the broadest possible scope.

In the drawings, Fig. 1 is -a diagrammatic view of a still embodying the invention.

Fig. 2 is a vertical cross sectional view of the automatic release valve of the invention. -.F1g. 3 IS a cross section on the line 3-3 of Fig. 2.

Fig. i is a view similar to Fig. 2 of a g valveliead 24. This valve head has formed modified form of construction.

Referring to the drawings, the still proper is indicated at 5 and may be of any suitable type of construction, such as a shell still or a tube still, heated ,either directly or by circulating the oil through heating tubes. The drum illustrated is of the general type disclosed in U. S. Letters Patent No..1,285,200 granted to the Sinclair Refining- Company upon an application of Edward lV. Isom, and oil is heated by circulation from the drum 5 through heating tubes (not shown) and back to thedrum 5. The drum is shown as provided with a safety valve 6 which may be of the usual construction.

The pressure still is provided with a reflux tower 9 connected with the vapor drum of the still through a vapor line 8 and having a return pipe 7 for the.return of reflux to the still. The reflux tower 9 is shown as a battle tower with a feed line for fresh feed entering the top of the tower. The vapors from the top of the tower escape from the vapor line 10 having the pressure reducing and regulating valve 11 therein, to the condenser shown conventionally at 12, and the pressure distillate is collected in the receiver 13 and drawn off thi'ough the pipe 14, while the permanent gas and any unpipe 15. Valves in the pipes 14 and 15 permit the maintenance of a pressure greater than atmospheric on the condenser and receiver, although this pressure may be substantially atmospheric.

A by-pass 17 is provided around the pres sure reducing and rcgulating' valve, and-this by-pass contains an automatic relief valve of a special construction described below. This byass leads from the high pressure side of t e pressure regulating valve to the line connecting the discharge side of the valve with the condenser. Normally this bypass valve will be closed, butupon a predetermined'rise in pressure above normal this "valve is designed to open sulficiently to permit the release of the excess pressure while closin before the pressure falls to any considera le extent below normal.

Referring to the construction of the improved automatic relief valve shown in 1. 1g. 2 it will be noted that the casing 21 which encloses the relief valve terminates in two flanges by which the casing can be directly connected to a similar flange 19 on the bypass pipe 17, and to a similar pipe on the outlet end. It will also be noted that ,except for these two openings the casing 21 is en tirely closed and that no moving parts extend outwardly therethrough.

The-u er flange 20 of the casing is provided with an opening 22 in which is threaded a bushing 23 serving as a seat for a The piston 26 may be provided with the,

usual piston rings. The diameter of the piston is also slightly less than the diameter of the valve head, the difi'erence in condensed vapors are drawn oil through the Ill) area being the effective area upon which the excess pressure operates. That is, the high pressure'in the pipe 17 above the automatic relief-valve also acts upon the piston 26 through the restricted opening in the valve stem and the pressure acting upwardly upon the piston partly counter-balances the preshead. 7

Mounted in suitable bosses 29 of the cas ing is a pintle 30 having a threaded portion 31 by means of which it is secured in sure acting downwardly upon the valve lease the excess place and having a square end 32 extending beyond the casing by. which it may be tightly screwed in the casing with suitable packing to insure a tighter fit if necessary.

Pivotally mountedon this pintle within the casing is a lever having a short arm 33 which bears against a collar 3% formed on the valve stem 25, and having a long arm 35 extending in the opposite direction, To the end of this long arm 35 a weight 36 is secured by a supporting rod 37 and nut 38. The casing is so formed and the long arm 35 is so is free to move up and down in the onset portion 39 of the casing, which tern'iinates in a flange 40, and an'outlet opening ll, this flange being bolted to a similar flange on the vapor line.

The action of the weight will be to counteract or offset the pressure upon the valve head during the normal operation of the pressure still. The slightfditfcrence in area between the piston and thevalve head constitutes the effective operating area of the" valve upon which the high pressure of the still operates, and this pressure is normally counter-balanced by the weight so as to keep the valve closed. However, upon .1 l the occurrence of a predetermined excess pressure in the pressure still, this excess pressure will act upon the valve and force it from its seat and permit the release of vapors therethrough to the low pressure side 01' the pressure control valve 11.

The construction of the "iiston 26 is not only such as to partlycounter-balance the valve but it is also such as to give-a dashpot effect upon sudden increases in pressure. The restricted opening through the valve stem will require an appreciable time for the pressure above the valve to he communicated to the under side of the piston, and

with sudden increase in pressure above the valve, this valve will open quickly, and, since the valve head is relatively large, an annular opening of appreciable size will be provided for the escape of vapors-thcrethrough. The pressure below the piston 20 will, however, serve to retard the opening of the valve and to help close the valve when the pressure falls below the predetermined pr asure. Y i

With a. valve having a valve head of two inches diameter,

15 lbs., which the weight will be required to counter-balance. suflicicntly upon a pre-determined small pressure of a few A valye so constrmrlcd. is

increase in pounds and serve to repressure without\perniitting the pressure to drop toan objectionably low arranged therein that the weight side increases to a pro-determined .above' normal, at reacts on the valve and the piston may have an effective diameter of il inches. lVith a sensitive so that it will open'] preferred construction pointbelow that desired in the pressure still.

Additional means may he provided for preventing or reducing the chattering ot the relief valve. A modified construction show ing such added means is In this figure the casing 21 is shown as provided with a hollow boss 42 in which is located a plunger rod 43 carrying a plunger at its upper end and terminating in a forked arm 44 at its'lower end bearing against the In the operation of the automatic relict' valve it will be evident that it functions so as to relieve the vapors 'roni the inlet or I the pressure-regulating' pressure side of valve to tho-outlet or low pressure side thereof. The valve will normally be hcld against its seat, bcin-g accurately guided by the projections or guides and by the equalizing piston. .lVhen the pressure on the inlet degree equalizing piston and scrves to opeirthc valve. When the pressure in the inlet pipe again becomes normal, the weight will function and over-balance the pressure in the inlet pipe, thereby rc-seating the valve in the valve seat and closing oil the release of vapors;

In the normal operation of the pressure still, the pressure will be regulated by manipulation of the hand-operated pre control valve 1.1 and the still pressure will be held at an approximately constant working pressure, for example, of lbs. The vaporwill be released through the pressure regulating and'reducing valve 11 lo the-condenser and receiver which may be maintaincd at atmospheric pressure or at a predctermined pressure above atmospheric, for example, a working pressure of lbs, If the pressure regulating valve 11 docs not function the pressure in the still will build 'up above the normal working pressure of 95 lbs, causing the automatic relief valve ample, "when tained.

It will be noted that the construction of the automatic relictvalve has no outside connection of stuiling boxes, etc, on the iigh pressure side of the valve, and, in the v of Fig. 2, there are no such connections on the low pressure side of the valve, except for the opening t irough which the pintle 30 enters the castn 111.

a pressure of lbs. is atshown in Fig; -l-'.

pulley 47 extending plate ure fi l

, Fig.1 the adjusting screw 47 extends (made sufiiciently tig t to prevent through a threaded o ening; but this can be a age, andithere will be less danger of ealrage becapse'of the low pressure maintained on the outlet side of the valve. All the working parts of the valve and adjustments are enclosed in one continuous 'casing and there are no adjustments which can be accidentally changed to prevent the automatic relief valve from operating.

vention provides an improvement in pressurestill construction according to which an auxiliary relief valve is provided around the manually controlled pressure regulatin'g. valve of the still and that this automatic relief valve discharges into the low pressure line so that any vapors discharged therethrough can be condensed and recovered. It will also be seen that the invention provides an improved construction of automatic relief valve in which all operating parts are enclosed in a single casing and-that a positive and reliable operationof the relief valve is thereby obtained. m.I claim: 1. A pressure still for cracking hydrocars having a pressure reducing valvefor regulating the escape of vapors from the pressure still to a condenser at a lower pressure, a by-pass around said pressure reducvalve, and an automatic relief valve in said-by-pass. adapted to open upon a predetermined increase in pressure in the still and. to relieve the excess 'pressure'by discharging gases therethrough to the condenser.

2. A pressure still for cracking hydrocarbons, having a pressure reducing valve for regulating the escape of vapors from the pressure still to a condenser at a lower pressure, a by-pass around said pressure reducing valve, and an automatic relief valve in said by-pass adapted to open upon a pre determined increase in pressure in the still and to relieve the excess pressure by discharging gases therethrough to the condenser, said automatic relief valve beluga weighted valve entirely enclosed within its casing.

3. A. pressure still for cracking hydrocarhons, having a condenser maintained at a lower pressure than the pressure in the still,

a vapor line leading from the still to the condenser, a pressure reducing valve in the vapor line, and a lay-pass around this valve which includes an automatic self-contained relief valve. i

' 4. In a pressure still for cracking hydrocarbons, the combination with a vaporizing chamber, a reflux tower connected therewith, a condenser and a vapor line leading from the tower to the condenser, of a pressure valve in the vapor linc'and. a bypass around this valv including a self-contained relief valve. i q

5. In a pressure still for cracking hydrocarbons, the combination with a vaporizing chamber, a reflux tower connected therewith, a condenser and a vapor line leading from the tower to the condenser, of a pressure valve in the vapor line and a by-pass around this valve including a self-contained reliefvalve operable upon a predetermined differ ence in ressure between the va'por'line and It will thus be seen that the present 1n' the con enser. r r p 6. In a pressure still for cracking hydrocarbons, the combination with a vaporizing chamber, a condenser and a vapor line lead ing from the still to the condenser, of a pressure valve in the vapor line and a bypass around this valve including a self-contained relief valve operable upon a predetermined difference in pressure between the vapor line and the condenser, the relief valve hav ing' its effective operating area less than the cross-sectional area of its face.

7. in a pressure still for cracking hydrocarbons, the combination with a vaporizing chamber, a reflux tower connected therewith, a condenser and a vapor line leading from the tower to the condenser, of a pressure valve in the vapor line, a bypass around the pressure valve, a relief valve in the icy-pass and mechanism wholly within the relief valve casing for forcing said relief valve toward its seat.

8. In a pressure still for cracking hydrocarbons, the combination with' a vaporizing chamber, a condenser and a vapor line lcad ing from the still to the condenser, of a pressure valve in the vapor line, a by-pass around the pressure valve, a relief valve in the by} pass and mechanism wholly within the relief valve casing for forcing said relief valve toward its seat, said mechanism including a differential piston and a weighted lever cooperating therewith.

9. In a pressure still for cracking hydrocarbons, the combination with a mporizing chamber, a condenser and a vapor line leading from the still to the condenser, of a pres sure valve in the vapor line, a by-pass around the pressure valve, a self-contained relief valve in the by-pass and means within the casing of the relief valve for damping the movements of the latter.

10. A ressure still for cracking hydrocarbons, aving a vapor line leading to a condenser at a lower pressure, a pressure reducing and regulating valve in the vapor line, a by-pass around this valve, and an au tomatic pressure reducing valve in said bypass, said automatic valve being a weighted valve and having the weight and operating connections in the bypass on the low pressure side of the valve. V

11. A pressure still for cracking hydrocan bons, having a vapor dine leading to a own till demeruta lower pressure, a press'ure reducing and regulating valve in the vapor line a by-puss around this valve, and an au tomatic pressure reducing valve insaid by pass, said automatic valve being a valve rm.-

ing A counterbalancing weight for holding the valve to its seat during normal operation ALFRED J. SLOAN.

Images