GB2185302A - Valve for use with hot gas containing entrained particles - Google Patents

Abstract

A large valve for hot gases containing entrained solids comprises a chest (14), a bonnet (15) upstream and, downstream connections (11, 13) parallel guides (27) one on each side of the chest, a valve plate (26) slidingly engaged in the channels for sealing movement between a first position in which one edge (30) registers against part (29) of the chest and obturates the gas flow path and a second position in which it is located within the bonnet. The part (29) is substantially free of ridges and recesses to avoid solids accumulations thereon. A transverse sealing member (34) at the junction of the bonnet and connection 11 slidingly cooperates with the plate 26. Because the valve plate and guides are always exposed to the gases in the valve, distortion and inoperability thereof are thereby avoided. <IMAGE>

Description

SPECIFICATION Valve for use with hot gas containing entrained particles The present invention relates to a large valve for use with hot gas containing entrained particles, and in particular (but not exclusively), for throttling or interrupting the flow of relatively large volumes of such hot gas.

Many types of valve are available for use with hot gas, but the combination of hot gas with entrained particles produces special problems which limitthe choice of valve. The choice is still further limited when the volume of gas which isto be controlled or regulated bythevalve is large.

Hot gas containing entrained particles is produced by the regenerator of a fluidized catalytic cracking unit, the combustororgasifierofa continuous fluid- ized petroleum coking unit and also byfurnaces used in oil refining, chemicals manufacture, electrical power generation, steel manufacture, inter alia. It is necessary to provide a valve to control or interrupt the flow of such gas either four maintenance of equipmentto which the gas passes or because the gasdemand of such equipmentvaries.

Valves which have hitherto been used forthe fore- going duties are butterfly valves and guillotine valves.

Butterfly valves comprise a valve chest in which a disc is pivotted for movement between one extreme position in which the edges ofthe disc register against a valve seat around the periphery of the chest and another extreme position in which the disc is substantially parallel tothe direction ofgasflow through the chest. Drawbacks of butterfly valves include, inter alia, their high cost, the relatively large amount of space they occupy, and the tendency for entrained solids to accumulate around the valve seat thereby preventing adequate sealing of the disc against the seat.

Guillotine valves are cheaper and occupy less space than butterfly valves. They comprise a valve chestthroughwhich gas flows and a bladeordisc which slides across the valve chest from outside the chest to throttle or close the passageway there- through. The blade or disc is outside the chest, and therefore at approximately ambient temperatures, when not in use. When it is introduced into the valve chest, the relatively sudden exposure to high temperatures causes distortion, and distortion may also be caused on withdrawing the hot blade from the chest due to its relatively sudden exposureto ambienttemperatures. Such distortion affects the ability ofthe blade to slide and to form an adequate seal.Another problem with existing guillotine valves used with hot gas containing entrained particles is that the bottom edge ofthe blade is received in a channel-like member or recess in or on the bottom wall ofthe chest so as to cooperate with the edgeto provide a gas-sealing effect, but entrained particles from the hot gas accumulate in the channel or recess thereby preventing adequate sealing ofthe edge of blade in the channel.

In some designs of guillotinevalve,there is provision to pass a gas into thewhole ofthe bottom ofthe channel in order to blow accumulated solids away.

However,this expedient, beside being inconvenient, has been found to cause accelerated erosion ofthe bottom channel and the internal surfaces of the valve. Such erosion ofthe internal surfaces ofthe valve, in time, requires the shut-down of the valve for repair, and this may, in turn, cause the shut-down of the equipment upstream and/or downstream of the valve with high costs in terms of lost productivity.

It is an object ofthe present invention to provide a valveforusewith hotgascontaining entrained particles which is not subject two at least some of the foregoing drawbacks.

The present invention provides a valve for interrupting theflowfrom an upstream conduit to a downstream conduit of a hot gas (e.g. atatem- perature in the range of up to 850"C, e.g. from 650 to 850"C) containing entrained particles and/or noxious components, the valve comprising:: (a) a hollow valve body adapted to be attached at its opposite ends to the respective ends of the upstream and downstream conduits, the valve body comprising an upstream hollow trunk, a downstream hollowtrunk and a valve chest between the saidtrunks,thetrunks and the valve chestcommunicating to provide an axial flow passagethrough the chest and at least the adjoining parts ofthe trunks, the valve chest having a substantially smooth internal wall bounding part ofthe said flow passage; (b) a hollowvalve bonnetattached tothevalve body and extending radially outwardly from the valve chest, the interior ofthe bonnet communicating freely with the interior of the chest;; (c) a valve memberwhich is movable along a predetermined path substantially radially relative to the axis of the valve chest between a first position in which it is substantially wholly received in the valve bonnet and a second position in which it substantially wholly obturates the said flow passage and in which position one edge of the valve member remote from the valve bonnet abuts against a portion of the substantially smooth wall facing the hollow in- teriorofthebonnet,thesaid portionofthewall part being substantially devoid of a ridge and/or a recess and being substantially flush with, or approximately flush with, the adjacent regions of the said wall part, the said edge of the valve member being shaped two cooperate with the said portion to form a relatively gas-tight seal; (d) guide means extending substantially parallel to the said predetermined path at least within said valve chest and adapted to cooperate with side regions ofthevalve memberto constrainthevalve member for movement along at least part of said predetermined path between the said first and second positions and to cooperate with said side regions to form a relatively gas-tight seal therewith; and (e) seal means projecting into the valve chest from one of the hollowtrunks at a positionatoradja- centtothejunction of the bonnet and the said one trunk and extending between the guide means to cooperate with a face of the valve member which is directedtowardsthesaid oneofthehollowtrunksto form a relativelygas-tightseal.

Preferably, the clearance between each side region ofthe valve member and the respective guide means is substantially no more than sufficientto permit re lativelyfree movement ofthevalve member relative to the guide means and to accommodate relative thermal expansion and contraction ofthevalve member and the guide means.

Preferably, the clearance between each seal means and the said face of the valve member is substantially no more than sufficientto permit relatively free movement of the valve member relative to the seal meansandto accommodate relativethermal contraction and expansion thereof.

Preferably, the said one edge of the valve member is substantially flat in axial cross sectional planes of the valve chest and is substantially devoid of a ridge and/or a recess.

The valve chest may be of rectangular cross- section in radial planes relative to the axis thereof, and the valve member may be rectangular. Each of the hollow trunks may be of rectangular crosssection in radial planes relative to the axis thereof.

The valve may comprise an operating rod attached tothevalve member and extending through a gland in the bonnet for moving thevalve memberto and from itsfirstand second positions.

There may be provided an orifice through the said wail portion of the valve chest and a valve for preventing the escape of gas via said orifice, said valve being operableto admitan elongated solid member to push againstthe said one edge ofthevalve member.

Preferably, valve parts exposed to the flow of hot gas are formed of and/or lined with refractory material.

Preferably, at least part of the regionswhichare cooperable to form relatively gas-tight seals are provided with erosion-resisting surfaces.

The bonnet may be detachably attached to the valve chest.

The bonnet may be vertically above the valve chest and the said predetermined path may be substanti- ally vertical.

The actual or effective cross-sectional flow area for gas through the valve may be at least 1 x 104cm2, preferably at least 1.4 x 104cm2, e.g. about 1.9 x 1 104 Cm2 Or greater.

The invention is now described with reference to some non-limitative embodiments thereof and with reference to the accompanying diagrammatic drawingstowhich: Figure 1 is an isometricview of one type ofvalve according to the invention showing the principal features visible in an external view, the valve being suit ablefor interrupting orthrotting the flow of hotgas having a temperature in the range offrom 650 to 850"C (e.g.from 700 to 770 C) containing entrained particles, and in particular(but not exclusively) hot gases from the regenerator of a catalytic cracker, which gas usually contain entrained catalyst particles and carbon monoxide (inter alia);; Figure2 is a vertical cross-sectional elevation of the valve of Figure 1, which vertical section is taken in a plane of Figure 1 and shows the principalfeatures oniy ofthe valve; Figure 3 is a horizontal plan view of part of the valve taken in the horizontal planeA-AofFigure2; Figure 4 is a horizontal plan view of part of the valve taken in the horizontal plane B-B of Figure 2; and FigureS is a vertical cross-sectional elevation of the valve of Figure 2 in the vertical plane C-C showing the principal features of the valve.

Referring first to Figure 1, it will be seen thatthe valve, generally indicated by reference 10, comprises a valve body having an upstream hollow tru nk 11 into which hot gas (e.g. from the regenerator of a catalytic cracker) passes, as indicated by arrow 12, a downstream hollowtrunk 13 out of which hotgas leaves the valve 10, and a valve chest 14 between the upstream trunk 11 and downstream trunk 13. Above the level ofthetrunks 11,13 and the chest 14isa valve bonnet 15, and superposed on the top of the bonnet 15 is a frame 16 supporting guides 17 through which an operating spindle 18 can slide up and down to raise and lower a valve plate (notvisible in Figure 1) attached thereto at its lower end.The spindle 18 is in two sections within the frame 16, and the sections are attached end-to-end by means of couplings 19. The spindle 18 is received abovethe frame 16 in a tube 20, and the raising and lowering of the spindle 18 and the attached valve plate is effected bysuitablewinding gear. As shown in Figure 1,the winding gear comprises a manual winding wheel 21 which operates on the spindle 1 8via intermeshing toothed gearwheels (not shown) in casing 22. The raising and lowering ofthespindle 18 mayalternatively be effected by pneumatic, hydraulic or electric means, or by any combination of any oftheforegoing.

Aswill be seen from Figure 1,theupstream hollow trunk 11 (and its connecting flange at its open end) is of square or rectangular cross-sectional shape and the downstream hollowtrunkl3 (and its connecting flange at its open end) is of circular cross-sectional shape. However these shapes are merely for illustration and those skilled in the artwill appreciate that both trunks may have the same shape, and the actual shape will depend on the cross-sectional shape of the conduit to which each trunk is to be attached when the valve 10 is installed for use.

Reference is now made to Figure 2from which it will be seen that the interior ofthe bonnet 15 is substantially completely open to the chest 14 via opening 24 so that hot gas passing through the valve 10 can pass freely between the interior of the chest 14 and the interior of the bonnet 15.

The spindle 18 passes through suitable sealing means such as a packing ring 25 atthetop ofthe bonnet adjacent to guide 17 to prevent the escape of gas from the valve 10 in the region where the spindle is received through the top of the bonnet.

The bottom of the spindle 18 is attached to a valve plate 26 which is adjacent to one or other of the ends ofthe valve chest 14; in the illustrated embodiment, the valve plate 26 is adjacent to the upstream end of the valve chest 14. The valve plate 26 has a shape which is substantiallythe same as the upstream end ofthevalve chest 14 (i.e. substantially the same as the downstream end of upstream trunk 11) and of substantially the same horizontal width but of slightly greatervertical height for reasons which will be apparent herefrom.

The valve plate 26 is received with a very small clearance at each vertical side in a respective vertical channel-like guide 27 which is substantially Ushaped in horizontal cross-section. Each guide extends upwardly substantially from the bottom of the valve chest 14to a position in the valve bonnet 15 neartothetop, and is located partially in a respective vertical side wall ofthe valve chest 14, as will be seen by reference to Figure 3 and on (or, if desired, part ially in) the corresponding respective side wall of the valve bonnet 15 as will be seen by reference to Figure 4.

With reference to Figure 2 and 5, it will be seen that the bottom edge or face 29 ofthe valve chest 14 between the guides 27 is free of ridges and recesses (which promote the accumulation of deposits of solids from the solids-containing gas passing through the valve) and has a shape which is suitable to cooperate with the bottom edge 30 of the valve plate 26. Preferably, as shown, the bottom edge 30 of the valve plate is free of ridges and recesses to avoid accumulations of deposited solids thereon from the solids-containing gas passing through the valve.

The bottom face 29 ofthevalve chest 14 and the bottom edge 30 of the valve plate 26 have substantially the same shape so that they will cooperate, when the valve plate 26 is lowered by operation ofthe winding wheel 21 to engage thereagainstto form a relatively gas-tight seal therewith. In the illustrated embodiment, the said shape is planar, although it will be appreciated that othershapes may be employed.

The vertical edges 32 (see Figures 3 and 4) ofthe downstream face of the valve plate 26 engage against the cooperable upstream faces 33 (Figure 2) of the g uides 27 to form a relativelygas-tightseal therewith.

At the region of the junction ofthe upstream side of the bonnet 15 and the upstream side ofthevalve chest 14, a substantially horizontal seal member 34 (shown in vertical cross-sectional elevation in Figure 2 and in broken lines in Figure 5) extends between the guides 27 and protrudes in the downstream dir ectiontowardsthe location of the upstream face of the valve plate 26 so as to provide a relatively gas tightsliding fitwhen thevalve plate 26 is located op polite the seal member 34.

Thus, when the valve plate 26 is located by operation of the winding wheel 21 so that its bottom edge 30 engages against the bottom face 29 ofthevalve chest 14, a relatively gas-tightseal is provided: (a) at the bottom of the valve plate 26 by cooperation with the bottom face 29 ofthe valve chest 14; (b) at the vertical side regions of the downstream face of the valve plate 26 by cooperation against the upstreamfacing parts ofthe guides 27; and (c) at the upper region ofthe upstream face ofthevalve plate 26 by cooperation against the horizontal seal member 34.

In a practical embodiment of a valve 10asshown in the accompanying drawings in which the vertical height and horizontal width of the flow area through the upstream trunk 11 are both 1340 mm (52.75 inch), it is calculated that when the valve plate 26 is lowered into its closed position so that its bottom edge 29 abuts against the bottom face 29 of the valve chest with good qualityfinishing ofthesurfaces (e.g. 50to 70 microinch root mean square roughness height, e.g. about 60 microinch root mean square roughness height, where one microinch equals 2.54 x 106cm.) which cooperate to form the seals around the valve plate, a seal of at least 99.0% of the periphery of the cooperating surfaces should normally be possible.

The edge regions of all the surfaces ofthevalve 10 which participate in forming a seal are likely to be subject to erosion by entrained solids in the gas. In order to minimize the effects of such erosion, all such edge regions are formed with a hard surface finish. A suitable hard-surfacefinish is provided by the alloys of cobalt, chromium and tungsten sold by Union Carbide Company of 270 ParkAvenue, NewYork City, New York 10017, USA underthe name "Stellite" (RTM).Edge regions which are provided with a hardsurface finish, such as the vertical edge regions of the valve plate 26 and the close fitting adjacent regions ofthe channel-like vertical guide means 27, are illustrated in the drawings as a thickened black edg- ing. In addition, the valve chest are formed with a hard-surface finish, such as that sold underthe name "Stellite".

In the embodiment of the valve as described herein, it will be appreciated that because the interior ofthe bonnet 15 communicatesfreelywiththein- terior of the valve chest 14 via the opening 24, all parts ofthe guides 27 and the valve plate 26 are ex posed to the gas passing through the valve 10 and are all, therefore, substantially in thermal equi librium therewith. Accordingly, there is substantially no distortion of, or differential expansion between, the valve plate 26 and the parts ofthe valve 1 0with which it cooperates to form a relatively gas4ight seal or relative to which it can be slidden.The valve plate 26 can therefore be moved relatively freely to and from the positions in which it closes the valve 10 by abutting the bottom face 29 and the fully open position in which it is raised substantially wholly into the bonnet 15 as shown in Figures 2 and 5.

The illustrated embodiment incorporates means to operate the valve lOin the event ofa failure, or inoperability, ofthe means for raising and lowering the valve plate 26. At the cenre of the bottom face 29 is provided an orifice 38 which forms the top opening of a vertical conduit 39 through the bottom ofthe valve chest 14. The conduit 39 is normally closed buy a valve 40. If the means provided for raising and lowering the valve plate 26 fails or is inoperable (e.g. because it is undergoing maintenance), an operating rod (not shown) is passed through a suitable packing gland (not shown) and via the valve 40 and conduit 39 so as to register against the centre of the bottom edge 30 of the valve plate 26. The operating rod may be pushed in the conduit 39 to a greater or lesserex- tent to raise and lowerthe valve plate 26 as required.

The movement ofthe operating rod may be effected by any suitable means. Thus, the valve is available forfull service at times when the equipment for raising and lowering the valve plate 26 is inoperable be cause it is undergoing maintenance work.

In orderto avoid any tendency for entrained solids to accumulate at the base ofthe interior ofthe valve 10, the whole of the interior base of the valve is substantiallyfree of projections, ridges and grooves, and the bottom face 29 is set into the base so that its top surface is substantiallyflush therewith.

Theflowofsolids-containing hotgasthroughthe valve 10 will expose the interiorthereofto highly erosive conditions. In orderto mitigate erosion of the interiorofthe valve 10 as far as possible, the valve chest 14 and the upstream and downstream trunks 11,13 are formed with an erosion-resistant refrac toryandthermal insulating lining material 42. The valve chest 14 is formed with a refractory lining 43 of chemical setting erosion-resistant refractory suppor- ted and reinforced by a suitable steel wire reinforcement. In the illustrated embodiment, the steel wire reinforcement is preferably stainless-steel linked- wire mesh of the type commercially available under the trade name "Hexmesh".The refractory and erosion resistant linings 42 are supported on substantially rigid steel plates and sheets 46 which are welded together to form a substantially rigid assembly, and maintained in position relative thereto by suitable means such as V-studs (not shown) attached to the steel plates and projecting into the mass of refractory.

The base 43 and vertical sides of the valve chest 14, including the "Hexmesh" reinforced refractory material, are supported by steel plates 47 which are sandwiched between the reinforced refractory material and external refractory insulation 49 (as shown in Figures2and3).

The inside of the bonnet 15 is formed from vertical steel plates 50 at the sides (Figures 2,4 and 5) and a top removable steel plate 51 (Figures 2 and 5) which is attached by bolts passing through, and engaging with, a peripheral flange 52 of the top plate 51 and a cooperating flange 53 at the top end of the side plates 50. A gasket (not shown) is preferably provided between the cooperating flanges 52,53. The exterior of the bonnet 15 is clad in a mineral wool fibre orsimilarthermal insulating material 54 which, for con- venience, may be the same type of thermal insulation as that (referenced 49 in Figure 2) beneath the steel plate 47 supporting the base 29 and reinforced refractory 43 on each side thereof.The total thick ness of the walls of the valve 10 may be about 20.2 cm (about4inch)for a valve having aflowarea through the upstream trunk 11 of 1340 mm width by 1340 mm height, which thickness includes the thickness of the refractory, steel plating, lining, inter alia.

The main intended use for the valve according to the invention isforthe interruption oftheflow of hot gas containing entrained solids. However, the valve can also be employed forthrottling the flow of such gases.

Although the invention has been particularly des- cribedwith reference to the illustrated embodiment, the invention is not limited thereto but embraces other embodiments falling within the scope of the appended claims. Moreover, although certain described features or combinations of features may not be specified in the claims, they may nevertheless fall within the ambit of the invention as defined in the

Claims (15)

claims. CLAIMS

1. Avalve for interrupting the flow from an upstream conduitto a downstream conduitofa hot gas (e.g. at a temperature in the range of up to 850"C, e.g.

from 650 to 850"C) containing entrained particles and/or noxious components, the valve comprising: (a) a hollow valve body adapted to be attached at its opposite endsto the respective ends oftheup- stream and downstream conduits,thevalve body comprising an upstream hollow trunk, a downstream hollowtrunkand a valve chest between the said trunks, the trunks and thevalve chest com- municating to provide an axial flow passage through the chest and at least the adjoining parts ofthe trunks, the valve chest having a substantially smooth internal wall bounding partofthe said flow passage;; (b) a hollow valve bonnet attached to the valve body and extending radially outwardly from the valve chest, the interior of the bonnet communicating freely with the interior ofthe chest; (c) a valve member which is movable along a predetermined path substantially radially relative to the axis ofthe valve chest between a first position in which it is substantiallywholly received in the valve bonnet and a second position in which it substanti allywholly obturates the said flow passage and in which position one edge of the valve member remote from the valve bonnet abuts against a portion ofthe substantially smooth wall facing the hollow in teriorofthe bonnet, the said portion of the wall part being substantially devoid of a ridge and/or a recess and being substantially flush with, or approximately flush with, the adjacent regions ofthe said wall part, the said edge of the valve member being shaped to cooperate with the said portion to form a relatively gas-tightseal; (d) guide means extending substantially parallel to the said predetermined path at least within said valve chest and adapted to cooperate with side regions of the valve member to constrain the valve memberfor movement along at least part of said predetermined path between the saidfirstand second positions and to cooperate with said side regions to form a relatively gas-tight seal therewith; and (e) seal means projecting into the valve chest from one of the hollow trunks at a position at oradjacent to the junction ofthe bonnet and the said one trunk and extending between the guide means to cooperate with a face of the valve memberwnich is directedtowardsthesaid oneofthehollowtrunksto form a relatively gas-tight seal.

2. Avalve as in claim 1 in whichtheclearance between each side region ofthevalve member and the respective guide means is substantially no more than sufficientto permit relativelyfree movement of the valve member relative to the guide means and to accommodate relative thermal expansion and contraction ofthe valve member and the guide means.

3. Avalveasinclaim 1 or claim 2 in which the clearance between each seal means and the said face ofthevalve memberissubstantially no morethan sufficient to permit relatively free movement of the valve member relative to the seal means and to accommodate relative thermal contraction and expansion thereof.

4. Avalveas in any one of claims 1 to 3 in which the said one edge of the valve member is substantially flat in axial cross sectional planes ofthevalve chest and is substantially devoid of a ridge and/or a recess.

5. Avalve as in any one of claims 1 to 4 in which the valve chest is of rectangular cross-section in radial planes relative to the axis thereof, and the valve member is rectangular.

6. Avalve as in any one of claims 1 to 5 in which each ofthe hollowtrunks isof rectangularcross- section in radial planes relative to the axis thereof.

7. Avalve as in any one of claims 1 to 6 comprising an operating rod attached to the valve member and extending through a gland in the bonnet for moving the valve member to and from its first and second positions.

8. Avalve as in any one of claims 1 to 7 compris inganorificethroughthesaidwall portionofthe valve chest and a valve for preventing the escape of gas via said orifice, said valve being operable to admitan elongated solid memberto push against the said one edge ofthe valve member.

9. Avalve as in any one of claims 1 to 8 in which parts exposed to the flow of hot gas are formed of and/or lined with refractory material.

10. Avalve as in any one of claims 1 to 9 in which at least part of the regionswhich are cooperableto form relatively gas-tight seals are provided with erosion-resisting surfaces.

11. Avalve as in any one of claims 1 to 10 in which the bonnet is detachably attached to the valve chest.

12. Avalveas in anyoneofclaims 1 to 11 in which the bonnet is vertically above the valve chest and the said predetermined path is substantially ver- tical.

13. Avalve asin anyoneofclaims 1 to 12in which the cross-sectional flow area for gas is at least 1 x 1 04 cm2, preferably at least 1.4 x 1 04cm2.

14. Avalve as in any one of claims 1 to 13 sub- stantially as described.

15. Avalve substantially as shown intheac- companying drawings.