CA1036509A - Valve means - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An improved method of cleaning gas filter bags and more particularly an improved method of opening the exhaust passage of a baghouse upon the completion of the cleaning of the filter bags therein. A valve is provided in the exhaust passage and a first portion of the valve is moved from the exhaust passage to fully open only a restricted passageway between the compartment and the exhaust passage to allow a relatively restricted flow of gas through the restricted passageway. Thereafter n second portion of the valve is moved from the exhaust passage to fully open the exhaust passage to allow a relatively unrestricted flow of gas.

Description

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Various types of known gas filtering apparatus often have included valve means such as flap or swing valve mechanisms to control gas flow therewithin as prescribed for normal system operation, for example to selectively control the opening and closing of a clean gas outlet port or a ~`
collapsing air inlet port in a baghouse filtering apparatus.
Although isuch valve means generally have served the purposes intended, they have nonetheless been sub;ect to certain undesirable shortcomings. For example, the relatively large flow channel areas typically required in high capacity gas filtering apparatus and the need for economical construction of such apparatus have necessitated the use of relatively impreclse valve means to open and clos~e such flow channels.
Consequently, preclse incrcmentaL Plow control by incremen~al ad~ustment of known valve means has heretofore been difficult or impossible. Such flow control difficulties and the problems precipitated thereby are exemplified by a conventional baghouse filtering system wherein the initial openlng of the clean gas outlet port by conventional valve means at the conclusion of a bag collapsing and cleaning cycle may sub;ect the collapsed . .
filter bags to a very rapid and harsh reinflation thereby excessively stressing the bags and precipitating premature failure thereof. Additionally, in an apparatus of the type -~
specified known valve means may require an excessively large and powerful valve actuator solely to overcome the relatively `
large difPerential pressure typically encountered only during initial stages of valve opening.
The present invention is used in a method oE exhausting gas from a bag Eilter compartment into an exhaus~ passage of a fllter unit, wherein a solids laden gas is passed Erom a primary source through filter bags located in the bag ilter compartment and the resultant filtered gas is exhalJsted ~ I _ I _ ..
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1~)3~5~9 through the exhaust passage which is controllable by valve means. The Yalve means is periodically moved to close ~he exhaust passage and a cleaning gas is passed from a secondary ij source through the bags countercurrent to the flow of the solids laden gas and at an elevated pressure wïth respect to the solids laden gas, after which the valve means is mGved to open the exhaust passage and the flow of cleanlng gas is terminated. The invention comprises the steps of: moving a first portion of the valve means from the exhaust passage '!'~
to fully open only a restricted passageway between the com-partment and the exhaust passage to allow a first predetermined relatively restricted flow of gas through the restricted passageway from the compartment to the exhaust passage. and thereafter moving a second portion of the valve means Erom ~, the exhaust passage to eully opcn the exhau~t pa~age to allow ~, a relatively unrestricted second predetermined flow of gas '~
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These and other ob~ects and advantage~ of the present 19 invention are more fully specified in the following description - ' ,,,.

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Fig. l illustrates partly in section a baghouse gas filtering apparatus including valve means constructed in accordance with the principles of the present invention;
Fig. 2 illustrates in section the valve means of this invention substantially as seen from line 2--2 of Fig. 3; and `
Fig. 3 is a section of the valve of Fig. 2 as seen from line 3--3 of Fig. 2.
There is generally indicated at 10 in Fig. 1 a baghouse gas filtering apparatus including a gas flow control valve means ;~
23 constructed in accordance with the principles of the present invention. Those versed in the art will recognize that the apparatus 10 is merely illustrative of one application of the present invention. Valve 23 may in fact be adapted ~or u9e in other known gas iltering apparatus and additionally in vArious other fluid flow control applicatio~s such as in ventilating e~uipment.
As shown, the apparatus 10 includes two baghouse filtering units 12 both suitably supported by a rigid structural frame 14 and each including a box-like enclosure 13 which carries .i . ~ .
therewithin a plurality of well known tubular filter bags 16 disposed in any suitable arrangement such as a plurality of rows ¦~
and columns of vertically oriented bags 16. Each unit 12 together with yet to be described adjunctive components comprises in '-~
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effect an independent filtering system. It is to be understood 1 that inasmuch as such filtering systems as the apparatus lb may commonly comprise a large plurality of substantially identical unlts 12 operating in parallel, the description hereinbelow re~ers to only one of the units 12.
~ 3~ The enclosure 13 includes a lower portion thereof Eormed ~;
;J as a hopper 18 which openly communicates with the inner con~ines of bags 16 in the customary fashion for receiving accumulated i,.`

dust therefrom during bag cleaning. Hopper 18 has conveying _..

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means 21 adapted to convey such dust therefrom to.a disposal bin 22 via a passaye 24. The open communication between hopper -. ~ . ". , 18 and the inner confines of bags 16 also provides a flow path `~
into the bags 16 for dust laden gaseous effluent delivered to hopper 18 via a duct 28 and inlets 26 as shown. ~
The unit 12 further includes: one of valves 23 disposed . :
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atop the enclosure 13 and commilnicating with the inner confines thereo via a port 44; a suitably driven exhaust fan 32 disposed atop the enclosure 13 and having the inlet thereof communicating ~
with valve 23 via a duct 36 and the outlet thereof communicating ~...
with the atmosphere via a stub stack 34; and a suitably driven ,. .
collapsing air fan 38 shown as having the inle~ thereof communi- , cating with the inner confines of enclosure 13 via a duc~ ~0 and ;;
having the outlet thereo~ communicating with valvc 23 via a duct 42. As shown the ducts ~0 and 4~ include suitable valve means 63 and 65, respectivelyjfor controliing communication therethrough. :: ..
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In the operation of apparatus 10 a stream of particulate :
laden gaseous effluent admitted into hopper 18 of enclosure 13 ;. ~ .
via the duct 28.and the respective inlets 26 is impelled by a negative pressure differential provided by fan 32 upwardly into .. .
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the inner confines-of bags 16 and through the fabric of the bags :.`

~: . 16 to filter dust or other particulates from the effluent stream. :~

The cleansed gas stream is thence impelled further upwardly ^-,~ .
within enclosure 13 and to the atmosphere via port 44, valve 23, - duct 36, fan 32 and stack 34. The substantially continuous f1ltering operation is periodically interrupted by a filter bag . cleaning aycle during which the valves 23, 63 and 65 are ...

actuated to direct a flow of collapsing fluid such as cleansed gas from an alternate filtering unit.l2 via one leg of duct 40, fan 38, one leg of duct ~2, valve 23 and port 44 into enclosure 13 to collapse bags 16 and thereby dislodge the accumulated dust cake therewithin in the conven~ional and well known manner. ;;
- Thereupon the dislodged dust cake falls perforce in~o hopper 18 . _3_ .
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and is thence conveyed by means 21 via passage 24 into bin 22 '~
for ultimate disposal thereof.
Inasmuch as the structure and operation of the apparatus 10 as described heretofore are well known in the art, and inasmuch as further detailed description thereof is not necessary for an understanding of the present invention, such additional des-cription is omltted herefrom. Applicant hereby refers to U. S.
Patent 3,057,137 for further description of such a baghouse filtering apparatus. ' `
By reference to Figs. 2 and 3 it will be seen that valve 23 of this invention comprises a rigid, yenerally rectangu-lar or box-like housing 31 having therewithin- a gas outlet space 33 which communicates with fan 32 via duct 36; a collapsing air inle~ spac~ 3S which oommunicates with ~an 38 vla duct 42; and a valve operating space 37 located generally intermediate the , spaces 33 and 35 and separated therefrom by intervening interior ', wall portions 39 and 41, respectively. The space 37 communicates with spaces 33~35 solely by means of respective ports 46-48 formed with respective wall portions 39-41, and additionally ~ 20 communicates with the respective enclosure L3 via the port 44. '-i The wall portions 39 and 41 are rigidly affixed within ! ' . ':
',, ~ housing 31 in a generally downwardly and outwardly diverging configuration as viewed in Fig. 2 to form a dow,nwardly opening ;
, ' angle having its apex within housing 31 adjacent a horizontal ,, 'I pivot axis indicated at 53. An elongated shaft 54 disposed , l ' aoincidentally with axis 53 is pivotally secured thereat as by ;ll shaft bearing portions 29 of housing 31 such that a swing or flap -, valve assembly 20 rigidly retained by the shaft 54 is movable ~ through an axcuate path within space 37 laterally intermediate i 30 extreme positions thereo~ ad~acent wall portions 39 and 41 to ;~
I selecti~vely close or open the respective ports 46 and 48 in a "', '~ ~ manner to be described hereinbelow. In Fig. 2 the assembly 20 is ; shown intermediate the extreme positions thereof. ;
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365C~9 The assembly 20 comprises: a rigid frame 52 secured to the shaft 54; a pair of axially aligned convex or dome-like ' circular valve portions 56 and 57 carried adjacent opposite sides o-' of the frame 52 and adapted to be sealingly engageable with respective ports 46 and 48; and an elongated retaining assembly , 58 which is rigidly secured to frame 52 and extends coaxially '~
intermediate portions 56 and 57 to captively retain the portions ~' 56 and 57 in the respective operating positions thereof.
As best shown in Fig. 3 the frame 52 includes a pair ,1' ' of elongated members 60 disposed in parallel, laterally spaced 3' , relation ana rigidly secured together by an elongated cross member 62 extending laterally therebetween intermediate the . .
longitudinal ends thereo and rigidly,afixed thereto as by weld- , ments (not shown). The frame 52 is rigidly secured to shaft 54 "',"
, adjacent one l,onyitudinal end o~ members 60 as by set screws (not '~, shown) or other suitable arrangement. The member 62 includes ~'' , . , ,.~, intermediate the longitudinal ends thereof a transversely extend- `
~" ing through bore 75 to receive the assembly 58. ~
, '' As shown the assembly 58 comprises a rigid elongated ;' ~ ,~, . .
member 76 which is suitably rigidly secured as by weldments (not ' shown) intermediate the axial ends thereof within the bore 75 ` ' ~, .
such that respecti,ve end portions 76a and 76b thereof extend in '' opposing directions outwardly of the plane of frame 52 to retain ;
`respective portions 56 and 57.
The portion 57 includes a circular and generally out-, wardly convex or dome-like valve plate 70 having an axial bore 'l . .
77 which receives end portion 76b whereby the portion 57 is , captively retained by assembly 58 intermediate an annular shoulder ,~ portion 79 of end 76b and a fastener 72 threadingly engaging end 76b outwardly adjacent shoulder 79.
I The valve portion 56 includes: a circular and generally ,1 outwardly convex or dome-like perforated main valve plate 86;
a generally disc-like secondary valve plate 88 disposed coaxially ;~' -5- , ' ", ' , , ' , . :.

365~9 inwardly from or on the concave side of plate 86 and axlally movable with respect thereto; and a helical spring member 90 extending coaxially intermediate the plates 86 and 88 so as to provide a parting or disjunctive biasing force therebetween.
The plate 86 includes an axial bore 74 adapted to receive end portion 76a, and a plurality of circumferentially spaced ports 92 which communicate openly intermediate axially opposed sides of plate 86. The plate 88 includes an axial bore 71 to receive the end portion 76a and an annular flange portion 96 which is suitably formed so as to be sealingly engageable with a mating peripheral portion of the inner or concave side of plate 86 radially outwardly adjacent the ports 92 to close the ports 92 in a manner to be described hereinbelow. In assembly the end 76a is received within bores 71 and 7~ o~ respective plates 88 ancl 86, and additionally coaxially within the spring 90 extending coaxially therebetween such that the portion 56 is captively retained by assembly 58 intermediate a faskener 73 which thread-ingly engages an outermost extremity of end portion 76a, and a cylindrical spacer 78 which encompasses end 76a adjacent member 62.
Ideally there is provided suitable spacing intermediate frame 52 and~respective portions 56 and 57, and additionally a suitable degree of looseness in the retention of portions 56 and 57 by the assembly 58 such as by radial clearance intermediate bores 71, 74, and 77 and member 76, that the plates 70, 86 and , 88 are rendered adjustable within limits to enhance sealing i` capability of the portions 56 and 57 with respective ports 46 and 48 by providing for automatic correction of minor misalign- -ment therebetween.
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In practice the valve 23 as described is operable by ' any suitable means such as an elongated link 64 rigidly afixed ,' adjacent one longitudinal end thereof to the shaft 54 and pivoted adjacent the opposing Longitudinal end thereof to one end of a .. , ~ .
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well known fluid operable cylinder assembly 50 carried exter-nally of the housing 31. Actuation of the assembly 50 powers valve assembly 20 through an arcuate path within space 37 ~ ' intermediate extreme positions thereof to provide sealing closure or opening of respective ports 46 and 48. To enhance such closing and opening operations the ports 46 and 48 include respective cylindrical flange portions 47 and 82 having respective annular seating surfaces 49 and 84 which are adapted to be seal-ingly engageable by the respective portions 56 and 57 as follows.
During normal filtering operations the assembly 20 is ;~
positioned to maintain clasure of port 48 by sealing engagement of a peripheral portion of the domed or convex side of plate 70 with annulus 84 as shown in Fig. X whereby collapsing air flow from ~;
fan 38 to unit 12 i8 interrupted and the clean gas flow path to the atmosphere via port 46 is fully open. Periodically as bags 16 accumulate therewithin a dust cake, a filter bag cleaning cycle is initiated during which the assembly 50 is operated to move assembly 20 to the opposite extreme position thereof (not shown) thereby opening the port 48 to a flow therethrough of collapsing air and closing the port 46. The closing of port 46 initially comprises the seating of plate 86 adjacent annulus 48 in substantially the manner described hereinabove for the i closure of port 48. The annulus 49 engages plate 86 radially outwardly adjacent ports 92 whereby the available 10w area inter~
` mediate spaces 37 and 33 is limited to the aggregate area of the ports 92 which is substantially less than the flow area of the , port 46. Subsequent continued operation of assembly 50 urges .
the plate 88 toward the seated plate 86 against the bias of ' spring 90 until flange 96 contacts the inner or conaave surface of plate 86 radially outwardly adjacent ports 92 thereby sealing the ports 92 from space 37 and thus interrupting clean gas flow to the atmosphere. It is of course to be understoo~ that by ( prudent selection of the spring rate for spring 90 or be `
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1~365Q9 adjusted withln a wide range of values.
Upon termination of the bag cleaning cycle the assembly 50 is operated to open port 46 and close port 48 by cycling ~ssembly 20 to the position illustrated in Fig. 1. The consequent opening of port 46 includes a first stage of valve opening during which the biasing force of spring 90 disengages flange 96 from plate 86 and maintains the plate 86 in sealing engagement with annulus 49 thereby reestablishing the flow of clean gas from unit 12 to the atmosphere at a relatively low flow rate through ports 92 to reinflate the collapsed filter i bags gently and without undue stress thereupon. Spring 90 urges plates 86 and 88 axially apart to the maximum possible extent as determined by the axial distance intermediate nut 73 and spacer 78 whereupon a second stage o~ valve openiny commences duriny which plate 86 disengages annulus 49 to provide an incremental !
increase in clean gas flow to the atmosphere. Further actuation of assembly 20 of course ~uickly restores full flow through port 46 and ultimately brings plate 70 into sealing engagement with annulus 84 once again to close *he port 48 and thereby complete a cycle of operation of the valve 23.
By virtue of the structure described hereinabove there is provided a valve means which is operable to seal a collapsing air inlet port and a clean gas outlet port and which is further operable to permit gradual opening of the clean gas outlet port ~`
'I by degrees to produce incremental increases in clean gas flow l therethrough to reinflate the collapsed filter bags gradually and . . .
gently.
Notwithstanding the reference hereinabove to a specific ~ structure of the valve disclosed it is to be understood that the ;~
`! 30 invention herein may be constructed in accordance with various other embodiments and with numerous modifications thereto without ; `
' I i ` ~ departing from the broad spirit and scope thereof. For example:
the valve means disclosed herein may be used in conjunction with , . . .

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a wide variety of gas cleansing equipment or in other applications :.~.
~elated to control of gas flow, and may be mounted in numerous configurations, for example to swing in a vertical or horizontal :; -arc or to move linearly under the impetus of an axial push rod actuator; it is contemplated that the flow area of ports 92 may be varied as by means o~ adjustable slide valves carried by :.: .
plate 86 or the like to add a further dimension of flow control : , to khe valve disclosed herein; it is additionally contemplated that the structure of valve portion 56 could include a plurality of nested plates having successively smaller flow ports and being separated by successively stronger spring member to provide a capability for increasing or decreasing flow therethrough in a plurality of incremental steps during valve actuation; and the like. These and other embodiment~ having been envisioned and anticipated it is re~uested that this invention be interpreted broadly and limited only by the scope of the claims appended ..
hereto.

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Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a method of exhausting gas from a bag filter com-partment into an exhaust passage of a filter unit, wherein a solids laden gas is passed from a primary source through filter bags located in the bag filter compartment and the resultant filtered gas is exhausted through the exhaust passage which is controllable by valve means, and wherein the valve means is periodically moved to close the exhaust passage and a cleaning gas is passed from a secondary source through said bags countercurrent to the flow of the solids laden gas and at an elevated pressure with respect to said solids laden gas, after which the valve means is moved to open the exhaust passage and the flow of cleaning gas is terminated, the improvement comprising the steps of: moving a first portion of said valve means from said exhaust passage to fully open only a restricted passageway between said compartment and said exhaust passage to allow a first predetermined relatively restricted flow of gas through said restricted passageway from said compartment to said exhaust passage and thereafter moving a second portion of said valve means from said exhaust passage to fully open said exhaust passage to allow a relatively unrestricted second predetermined flow of gas from said com-partment to said exhaust passage.

2. The improved method as specified in claim 1 including the additional step of: subsequent to moving said second portion of said valve means to fully open said exhaust passage, moving said valve means to a position to block flow of said cleaning gas from said secondary source to said compartment.