US2709064A - Valve apparatus - Google Patents

Description

y 4, 1955 K. A. SMITH 2,709,064

VALVE APPARATUS Filed Oct. 14, 1950 2 Sheets-Sheet 2 FLOW 35 INVENTOR ffi/wvsTh' A. SMITH BY MjrWMW/Iefi ATTORNEYS United States Patent VALVE APPARATUS Kenneth A. Smith, Forest Park, 111., assignor to Sinclair Refining Company, New York, N. Y., a corporation of Maine Application October 14, 1950, Serial No. 190,216

3 Claims. (Cl. 251-120) My invention relates to a novel type valve for use in the control of flow of finely divided solid materials, and more particularly, for use in the control of flow of finely divided solid catalyst in fluid catalytic cracking units.

In the operation of a fluid catalytic cracking unit, large quantities of finely divided solid catalyst are circulated through the unit by aeration. This finely divided solid catalyst must pass between regenerator and reactor and through supplementary equipment at tremendous flow rates and in closely controlled quantities in order to establish and maintain the desired operating conditions, e. g., catalyst to oil ratio, catalyst level in the reactor, and temperature in the regenerator by circulation through recycle steam generators. The how of this finely divided solid catalyst is controlled by valves placed in the fluid catalyst lines, 1. e., the regenerator standpipe for control of flow of regenerated catalyst to the reactor, reactor standpipe for control of flow of spent catalyst to the regenerator, and in supplementary equipment, as for example, the regenerator standpipe leading to recycle steam generators. These valves are normally installed in pairs Wherever control is required. Usually the upper valve of the pair is maintained as a reserve, in case of failure of the lower, operating valve.

The conventional valves presently in general use in fluid catalytic cracking units are slide valves which include a valve body, a liner or throat, a slide plate, and actuating means to position the slide plate with respect to the liner or throat to control the flow of the solid catalyst. The slide plate is positioned in the catalyst standpipe on the downstream side of the liner or throat. Slide guides are provided to maintain the slide plate in this position and to allow the slide plate to be moved in a plane perpendicular to the flow of catalyst to control the rate of catalyst fiow.

The passage of tremendous quantities of finely divided solid catalyst through these' conventional slide valves causes erosion of the valve parts because of the 0bstruction type of control effected by the valves. The leading edges of the slide plate and the liner or throat show intense wear. More important, however, these valves cause irregularities in stream flow of the finely divided solid catalyst resulting in serious erosion of the valve bodies and of the catalyst standpipe when the valves are used to establish less than maximum rate of flow. This is particularly true when these valves are less than 50% open. This erosion is so severe thatit leads to a wearing through of the wall of the valve body or of the catalyst standpipe and results in a shutdown of, the entire unit or requires periodic shutdown for replacement of parts so that actual failures will not occur. The cause of the most severe valve body and catalyst standpipe wear is the deviation from straight line flow of the stream or" finely divided solid catalyst emerging from these conventional valves when the valves are partially closed. The partial closure of the valve deflects the stream away from the slide plate. The deice flected stream impinges on the valve body or catalyst standpipe below the slide plate and erodes the valve body or standpipe wall. Because the slide valves are normally maintained at a substantially constant opening once unit operation has been established, this erosion tends to be concentrated and, therefore, presents a serious problem. While maintaining the valves in substantially full open position tends to minimize Wear on the valve bodies and catalyst standpipes, because of the required flow control it is not always possible to maintain the valves in substantially full open position, i. e., to have valves designed with respect to throat area so that dun ing continuous operation the valves would always be positioned in full open or substantially full open posii101].

Because of the erosion caused by the finely divided solid catalyst stream, valve design for flow control of finely divided solid catalyst presents a serious problem and a problem which is not encountered in normal flow control design or operation with liquids or gases.

I have developed a novel type valvefor control of flow of finely divided solid catalyst in fluid catalytic cracking units which minimizes wear on the valve parts and eliminates erosion of the wall of the valve body or the catalyst standpipe caused by irregularities of flow or deviation from straight line flow. The valve of my design accomplishes this latter result by maintaining straight line flow of the finely divided solid catalyst emerging from the valve exit so that catalyst does not impinge on the wall of the valve body or the catalyst standpipe. Wear of the valve parts is minimized by the control of flow patterns leading into the valve and by the shape of the valve parts.

A preferred embodiment of the valve of my design includes as control elements a flow plate, positioned in the path of catalyst flow, containing an orifice which forms and directs a rectangular stream of catalyst between a stationary member and a movable member, the upstream surfaces of the members being positioned adjacent to the downstream surface of the flow plate, the two members being on opposite sides of the rectangular exit of the flow plate, and the flow control surface of each member being elongated in the direction of flow and sloping away from the line of flow. The remaining pair of sides of the rectangular exit of the orifice in the flow plate are provided with flow control surfaces extending downstream from the exit side of the flow plate by the inside wall of a hollow valve body in which the control elements are positioned. Control of flow is obtained by positioning the movable member with respect to the stationary member to vary the area of the rectangular exit of the fiow plate. I have found that a valve includingthese control elements produces a catalyst stream with straight line flow characteristics. In addition, the control elements, while subject to some wear, are not subject to the intense erosion at the critical control edges or surfaces which is encountered in the use of the conventional slide valve, and therefore the ability to control flow is not seriously affected.

The function and design of my valve will be more fully explained in the following description with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic illustration of a fluid catalytic cracking unit showing the principal pieces of apparatus and the position of the valves for control of the catalyst flow;

Figure 2 is a side-view in section of a valve of my design;

Figure 3 is a top-view of the valve partly in section taken along line 33 of Figure 2; and

Figure 4 is a side-view of the valve in section taken along line 4-4 of Figure 3.

Referring to Figure l, a conventional fluid catalytic cracking unit is comprised of a reactor 1 and a regenerator 2 as primary elements. Recycle steam generators are usually provided, as illustrated at 3 to control regeneration temperatures in the regenerator 2. Other supplementary equipment is not shown, the diagram being restricted in scope to the major paths of flow of the finely divided catalyst. The operation of fluid catalytic cracking equipment of the type illustrate in Figure 1 is Well known, and the following description is limited to the flow of the finely divided solid catalyst.

Hydrocarbon charge stock and regenerated catalyst are supplied to the reactor 1 through a riser 4. The hydrocarbon charge is introduced into the riser 4 at 5 and regenerated finely divided catalyst is introduced into the riser 4 at 6 from a regenerated catalyst standpipe 7 in regulated quantity controlled by a valve which is one of a pair of valves located in the regenerated catalyst standpipe 7 at 8. The hydrocarbon charge and re generated finely divided catalyst flow as a stream through the riser 4 and enter the reactor 1 through a grid 9. The finely divided catalyst forms a dense phase body in the lower portion of the reactor 1, while the hydrocarbon vapors, cracked during contact with the catalyst in the reactor, pass up through the reactor and leave the reactor through the vapor line 10. Spent catalyst, catalyst coated with coke formed during the cracking of the hydrocarbon charge, collects in the bottom of the reactor at 11 and is withdrawn from the reactor through a spent catalyst standpipe 12.

The spent catalyst from spent catalyst standpipe 12 is introduced into the regenerator riser 13 in regulated quantity controlled by a valve which is one of a pair of valves located in the spent catalyst standpipe 12 at 14. Air is introduced into the regenerator riser 13 at 15 and the air and spent catalyst flow as a stream through the regenerator riser 13 and enter the regenerator 2 through a grid 16. The finely divided catalyst forms a dense phase body in the lower portion of the regenerator 2, while the flue gases, formed by the oxidation of the coke layer on the catalyst, pass up through the regenerator 2 and out the flue gas line 17. In general practice both the reactor 1 and regenerator 2 are provided with cyclone separators to return to the system catalyst fines which are carried up to the chamber outlet by the efiiuent gases.

Regenerated catalyst collects in the bottom of the regenerator 2 at 18 and is withdrawn as required through regenerated catalyst standpipe 7 and introduced into the reactor in regulated quantity controlled by the valve at 8 as described above.

In addition to controlling the quantity of air introduced into the regenerator 2, one or more recycle steam generators 3 are usually provided to control the temperature and rate of regeneration of the spent catalyst in the regenerator 2. Regenerated catalyst is withdrawn from the regenerator 2 through a regenerated catalyst standpipe 19 and introduced into recycle steam generator riser 20 in regulated quantity controlled by a valve which is one of a pair of valves located in the standpipe 19 at 21. Air is introduced into the riser 20 at 22 and the air and finely divided catalyst flow as a stream through the recycle steam generator 3 giving up heat to produce steam. The air-catalyst stream passes out of the recycle steam generator 3 through line 23 and is returned to the regenerator 2 where the cooled catalyst serves to control regenerator temperature and the air supplies additional oxygen for regeneration of spent catalyst.

The control of the whole unit operation is dependent on the close control of the flow of the finely divided catalyst by means of the valves located at 8, 14 and r 21. The excessive wear of the critical valve parts, i. e., the slide plate and the liner or throat, encountered in the use of the conventional slide valve decreases the accuracy and speed of control possible when a change in the rate of flow of finely divided catalyst to a particular unit is necessary. The valve of my design, in addition to establishing a substantially straight line flow so that valve body and catalyst standpipe erosion are virtually eliminated, is superior to the conventional slide valve in regard to wear of the critical valve parts. The parts of my valve which are subject to wear are easily replaced or repaired and do not, even in worn condition, affect the ability to control the flow of the finely divided catalyst as greatly as do the wearing parts of the conventional valve.

Referring now to Figures 2, 3 and 4 which illustrate a preferred embodiment of the valve of my invention, my valve is formed generally of a valve body 30, a flow plate 31, a stationary member 32 and a movable member 33 with suitable control means 42 connected to the movable member 33 to position it for flow control.

Flanges 34 are provided at each end of the hollow valve body so that the valve body 30 may be inserted into and connected to a catalyst standpipe 35. Connection is suitably made with bolts 36 so that the valve body 30 can be removed readily for replacement of parts or repair. Suitable packing material 37 is provided at the connections to insure an effective seal between the valve body 36 and catalyst standpipe 35.

The flow plate 31 is secured in the valve body 30 on the upstream side of the flow control parts of the valve and the orifice in the flow plate 31 is designed to cstablish a flow pattern which will minimize wear on the valve parts and aid in establishing straight-line fiow from the valve into the catalyst standpipe 35. The orifice in the flow plate 31 is circular in horizontal crosssection on the upstream side of the flow plate 31, while on the downstream side of the flow plate 31 the orifice is rectangular in horizontal cross-section. This change from circular to rectangular cross-section produces a flow pattern which is desirable both from the stand,- point of wear on the valve parts and with regard to establishing straight-line flow.

The stationary member 32 is fastened to the valve body wall with fastenings 38 and with the upstream surface of the member 32 adjacent to the downstream surface of the flow plate 31. The upper and inner edge of stationary member 32 is a straight edge equal in length to the side of the rectangular exit of the orifice in fiow plate 31 with which it is adjacent. The inner surface of stationary member 32 is blended from the straight upper edge to a curved bottom edge and this surface slopes away from the line of catalyst flow through the valve.

The movable member 33 has a flow control surface which is the same as the surface of the stationary member 32, i. e., in full open position (as shown in solid lines in Figure 2) the upper and inner edge of the movable member 33 coincides with a side of the rectangular exit of the orifice in the flow plate 31 which is opposite the side of the rectangular exit adjacent to the stationary member 32 and the straight upper edge of the movable member 33 blends into a curved bottom edge with the flow control surface sloping away from the line of catalyst flow through the valve. To the upper surface of movable member 33 is fastened a slide plate 39 with suitable fastenings 40 so that the movable member 33 is free to slide, the upper surface of the slide plate 39 being in loose bearing contact with the lower surface of the flow plate 31. The slide plate 39 is of greater width than the movable member 33, i. e., greater in width than the side of the rectangular exit of the orifice in the flow plate 31 with which the movable member is coincident when in full open poisition, and this extra width is provided as slides on each side of member 33 parallel to the direction of movement of member 33. The slides formed by slide plate 39 move in slide guides 41 which are formed in the valve body 30 immediately below flow plate 31 or may be contained in a removable insert fastened into the valve body by suitable means.

The inner surface of the 'hollow valve body 30 is formed to provide control surfaces 50 and 51 extending downstream from the two remaining sides of the rectangular exit of the orifice on the flow plate 31. The control surfaces 50 and 51 are substantially plane surfaces elongated in the direction of fiow and sloping away from the line of flow through the valve. While the control surfaces 50 and 51 are not theoretically necessary to maintain straight line flow of the catalyst stream emerging from the valve, i. e., the horizontal forces imparted to the catalyst stream by this pair of sides of the rectangular exit of the orifice in flow plate 31 are equal and opposite in all positions of the movable member 33 and thereby tend to cancel, it is advantageous to have the catalyst stream emerging from the orifice inthe fiow plate 31 completely enclosed to insure that deviation from straight line flow does not occur. The complete enclosure of the catalyst stream subsequent to the actual flow control point by the elongated control surfaces of the stationary member 32 and the movable member 33 and the surfaces 50 and 51 assures straight line flow of the catalyst stream in that any deviation from straight line flow at the point of control is confined and corrected by these surfaces before the catalyst stream emerges into the valve body 30 and catalyst standpipe 35. This is particularly true of the function of the elongated surfaces of the stationary member 32 and movable member 33. The action of the movable member 33 in controlling flow, i. e., in partially closed positions, tends to deflect the stream away from the movable member 33 and toward the surfaces of the stationary member 32. Actual deviation from straight line flow is prevented by the elongated surfaces of these members.

The surfaces of members 32 and 33 are suificiently elongated in the direction of flow to correct any devia' tion from straight line flow in any position of the movable member 33. I have found that by having the control surfaces of these members equal in length to about one to two times the distance between the control surfaces of the movable member 33 and stationary member 32 when the movable member 33 is in full open position any deviation from straight line flow at the point of flow control will be corrected before the stream emerges from the control surfaces of the valve. However, since the greatest tendency toward deviation from straight line fiow occurs when the movable member 33 is in positions less than 50% open, if operation will allow maintaining the valve in positions greater than 50% open, the length of the control surfaces of these members can be decreased.

In addition, by providing a complete enclosure around the catalyst stream for a short distance in the manner described, a venturi efiect is produced.

The action of the control surfaces of the movable member 33 and the stationary member 32 and the surfaces 50 and 51 in overcoming any deviation from straight line flow of the catalyst stream before the stream emerges into the valve body 30 and catalyst standpipe makes it possible to omit the flow plate 31 as a control element of the valve. However, I prefer to include the flow plate 31 in the construction of my valve because of its advantageous function of reducing wear on the control surfaces by aiding in establishing straight line flow.

While the valve body 31 could also be formed to provide the control surface supplied by the stationary member 32, I prefer to include the replaceable stationary member 32 in the construction of my valve for the reason of economic maintenance of the valve. Some wear of the surface provided by the stationary member 32 does occur. This wear is chiefly at the upstream end of the control surface of the stationary member 32 where the horizontal component of How of the catalyststream, imparted to the streamby the movable member 33 'when the movable member is in a partially closed position, intersects this surface. By providing this control surface by means of replaceable stationary member 32, the valve body wall is protected from even the slightest wear.

The movable member 33 is positioned for flow control by means of a double acting hydraulic cylinder 42 or other suitable actuating means. The piston of the actuating cylinder 42 is connected to the movable member 33 by means of links 43 and 44 and connecting shaft 45. The connecting shaft 45 is provided with a flange 46 which fits into a slot in the end of the movable member 33. The shaft 45 is held in position in a housing 47, which is connected to the valve body 30, by means of a bearing insert 48 anda gland 49.

In operation the movable member 33 of my valve is moved from the closed position (as shown by dotted lines jin Figure 2), or from any operating position, tothe desired operating position, i. e., to a position' 'yielding the desired rate of flow of finely divided catalyst, by means of the actuating cylinder42 and the links connecting the piston of the actuating cylinder 42 to the movable member 33. The slides provided by slide plate 39 move in the slide guides 41 and maintain the movable member 33 in loose bearing contact with the downstream surface of the flow plate 31. The catalyst from catalyst standpipe 35 flows into the valve body 30, through the orifice in flow plate 31 and between the control surfaces of stationary member 32 and movable member 33. The quan; tity of catalyst passing between these control surfaces' is determined by the open area of the rectangular exit of the orifice in flow plate 31 which is controlled by the position of the movable member 33 with respect to the stationary member 32.

Regardless of the rate of flow of catalyst, i. e., the area of the rectangular exit in orifice plate 31, the exit is always of a general rectangular shape and the stream of catalyst emerges from the control surfaces of the members 32 and 33 in straight-line flow. Because of the flow patterns established by the flow plate 31, thelbontrol edges of the movable member 33 and the stationary member 32 are not subject to intense erosion. The wear that does occur on these members does not, because of the shape of the members, seriously afiect the control of flow or allow any deviation from straight-line HOW.

I claim:

1. An assembly suitable for use in fluid catalytic cracking units to control the flow of finely divided solid catalyst which comprises a flow plate extending across the path of catalyst flow, an orifice through said flow plate having a circular entrance merging into a rectangular exit, a valve member having a valve surface abutting the exit face of said flow plate greater in dimensions and area than the rectangular exit of the flow plate, said valve member being transversely slidable across said exit with an inner edge of said valve surface parallel to one edge of said rectangular exit, means forming a part of said valve member defining an elongated fiow control surface extending in the direction of flow from said inner edge of said valve surface, a flow control member fixed in abutting position against the exit face of said flow plate and defining a second elongated flow control surface extending in the direction of flow from the edge of the rectangular exit in said flow plate opposite said valve member, means defining a third and a fourth elongated fiow control surface extending respectively from opposite edges of the rectangular exit in. said flow plate adjacent to said flow control member and abutting opposite lengthwise edges of said first and second elongated flow control surfaces, and means for sliding the valve surface-of said valve member transversely across the exit face of said flow plate relative to said fixed flow control member between said third and fourth flow control surfaces.

I 2. An assembly suitable for use in fluid catalytic cracking un its to control the flow of finely divided solid catalystwhich comprises; an open ended hollow body positioned inthe path of catalyst flow,' a flow plate extending across theipath of catalyst flow Within said hollow body, an orifice through said flow plate having a circular entrance merging into a rectangular exit, a valve member having a valve surface abutting the exit face of said flow plate greater in dimensions and area than the rectangular exit of fthe flow plate, said valve member being transversely slidable acrosssaid exit with an inner edge of said valvei surface parallel to one edge of said rectangular exit, rn eans forming a part of said valve member dean elongated flow control surface extending in the directionof flow, from said inner edge of said valve surface, a flow control member fixed in abutting position against the exit face of saidfiow plate and defininga second elongated flow control surface extending in the" Cir 8 exit face of said flow plate greater in dimensions and area than the rectangular exit of the flow plate, said valve member being transversely slidable across said exit with an inner edge of said valve surface parallel to one edge of said rectangular exit, means forming a part of said valve member defining an elongated flow control surface extending in the direction of fiow from said inner edge of said valve surface, a flow control member fixed in abutting position against the exit face of said flow plate and defining a second elongated flow control surface ex.- tending in the direction of flow from the edgeofthe rectangularexit in said flow plate opposite-said valve member, means defining a third and a fourth elongated substantially plane flow control surface extending respectively from opposite edges of the rectangular exit in said flow plate adjacent to'said flow control member and abutting opposite lengthwise edges of said first and second I How control surfaces, and means for sliding the valve directi m'got flow from the edge of the rectangular exit in said flow plate opposite said valve member, said hol- Iow body defining a third and a fourth elongated flow control surface extending respectively from opposite edges of;the rectangular exit in said flow plate adjacent to said flow control member'and abutting opposite lengthwise edges of said first and second flow control surfaces,

andmeans for sliding the valve surface of said valve member transversely across the exit face of said flow plate relative to said-fixed flow control member between said third and fourth flow control surfaces.

, 3. An assembly suitable for use in fluid catalytic cracking units to control the flow of finely divided solid catalyst which comprises a flow plate extending across the p athrof catalyst flow, an orifice through said flow plate having a circular entrance merging into a rectangular exit, a valve member having a valve surface abutting the surface of said valve member transversely across the exit face of saidflow plate relative to said fixed flow control member between said third and fourth flow control surfaces.

References Cited in the file of this patent UNITED STATES PATENTS Germany

Claims (1)

1. AN ASSEMBLY SUITABLE FOR USE IN FLUID CATALYTIC CRACKING UNITS TO CONTROL THE FLOW OF FINELY DIVIDED SOLID CATALYST WHICH COMPRISES A FLOW PLATE EXTENDING ACROSS THE PATH OF CATALYST FLOW, AN ORIFICE THROUGH SAID FLOW PLATE HAVING A CIRCULAR ENTRANCE MERGING INTO A RECTANGULAR EXIT, A VALVE MEMBER HAVING A VALVE SURFACE ABUTTING THE EXIT FACE OF SAID FLOW PLATE GREATER IN DIMENSIONS AND AREA THAN THE RECTANGULAR EXIT OF THE FLOW PLATE, SAID VALVE MEMBER BEING TRANSVERSELY SLIDABLE ACROSS SAID EXIT WITH AN INNER EDGE OF SAID VALVE SURFACE PARALLEL TO ONE EDGE OF SAID RECTANGULAR EXIT, MEANS FORMING A PART OF SAID VALVE MEMBER DEFINING AN ELONGATED FLOW CONTROL SURFACE EXTENDING IN THE DIRECTION OF FLOW FROM SAID INNER EDGE OF SAID VALVE SURFACE, A FLOW CONTROL MEMBER FIXED IN ABUTTING POSITION AGAINST THE EXIT FACE OF SAID FLOW PLATE AND DEFINING A SECOND ELONGATED FLOW CONTROL SURFACE EXTENDING IN THE DIRECTION OF FLOW FROM THE EDGE OF THE RECTANGULAR EXIT IN SAID FLOW PLATE OPPOSITE SAID VALVE MEMBER, MEANS DEFINING A THIRD AND A FOURTH ELONGATED FLOW CONTROL SURFACE EXTENDING RESPECTIVELY FROM OPPOSITE EDGES OF THE RECTANGULAR EXIT IN SAID FLOW PLATE ADJACENT TO SAID FLOW CONTROL MEMBER AND ABUTTING OPPOSITE LENGTHWISE EDGES OF SAID FIRST AND SECOND ELONGATED FLOW CONTROL SURFACES, AND MEANS FOR SLIDING THE VALVE SURFACE OF SAID VALVE MEMBER TRANSVERSELY ACROSS THE EXIT FACE OF SAID FLOW PLATE RELATIVE TO SAID FIXED FLOW CONTROL MEMBER BETWEEN SAID THIRD AND FOURTH FLOW CONTROL SURFACES.

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