CLARIFIER COVER
FIELD OF THE INVENTION
This invention relates to flexible covers, and more in particular, the present invention relates to the sealing of a flexible cover over a clarifier to maintain the contents of the clarifier in a sealed environment.
BACKGROUND OF THE INVENTION
A typical industrial clarification facility comprises a plurality of reservoirs or holding tanks to be filled with industrial effluent. Clarification is usually done alternatively by agitating and allowing the effluent to settle, and lifting the floating layer from the surface of the effluent or discarding the sediments at the bottom of the deposit. These holding tanks are usually provided with mechanical equipment that must be accessible for inspection, maintenance or repair. The clarification process is often accompanied by a fermentation action and a generation of odoriferous biogases, and / or the release of volatile organic carbons. For environmental reasons, these gases must be collected and treated. Therefore, a deposit of
"._, TO . i _. , _ _ ^ __ »_, t _... _ ... . , ... _. _. _ _ ^ N j ^ Éfrfttfffftr clarification, or clarifier, covered and sealed to contain gases. In addition, a clarifier preferably has a pipe system for transporting the gases to a gas treatment plant. When a movable flexible cover is installed over a clarifier, the installation must resist the forces of the wind that tend to wave the portions of the cover and stretch it laterally. In addition, the union of a flexible cover must be strong enough to allow one or more workers to walk on the flexible cover to fix it, if necessary. A clarifier that has a movable flexible cover mounted on it, must also possess a certain level of security when the cover is removed. During maintenance activities, it is common to find mechanical tools, welding machines, oxiacelenic torch cars and maintenance wagons along the perimeter of the clarifier. Therefore, it is important to prevent workers and equipment from slipping into the warehouse. The following documents describe examples of different systems available to cover a deposit: Patent of E.U.A. 3,195,310 issued on July 20, 1965 for CE. Schroeder; Patent of E.U.A. 4,324,370 issued April 13, 1982 to W. Guard et al .; German Patent DE 2,938,496 published April 24, 1980;
_, __.__.._ __. i _, -..__ .. _., _- _... .. ...... .. .. . . . . .. _. _ _ ^ ^ ___ = _-French Patent FR 2,668,195 published on April 24, 1992. Although the flexible covers of the prior art deserve undeniable recognition, it is considered that these systems do not meet all the requirements for a clarification cover flexible which is installed carefully, that is movable and safe. It is believed that the need continues for a new movable flexible cover which can be fully sealed, which can support workers who walk on it, and which provides a safe work environment.
BRIEF DESCRIPTION OF THE INVENTION
In the present invention, however, a movable clarifier cover is provided, which has safety features incorporated therein, which is particularly efficient for sealing a clarifier in a manner that resists wind forces and supports workers who they walk on it. In a first aspect of the present invention, a movable cover is provided for retaining malodorous gases within a clarifier having first, second, third and fourth walls. The cover comprises a flexible sheet that extends through the clarifier and has first, second, third and fourth margins. Means are also provided for retaining and sealing the first margin towards the first wall, and means for releasably pulling and sealing the second, third and fourth margins towards the second, third and fourth
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f§ * walls respectively. The means for retaining and sealing the first margin towards the first wall comprises a first structural angle extending along the first wall and having a column element aligned upwards. The means for releasably pulling and sealing the second, third and fourth margins comprises spaced handles mounted within the second, third and fourth structural angles extending along the second, third and fourth walls respectively and each structural angle it has a column element aligned upwards. In this aspect of the present invention, the first, second, third and fourth walls, and the flexible sheet are useful for containing malodorous gases within the tank and the first, second, third and fourth structural angles constitute defense plates that enclose the clarifier to improve the safety of workers who work
15 around the clarifier. In another aspect of the present invention, the clarifier cover comprises a plurality of spaced beams mounted through the clarifier and the flexible sheet extends over the spaced beams. In this aspect of the invention, the flexible sheet is wound selectively
20 on spaced beams to access equipment inside the tank. According to another aspect of the present invention, the means for detachably pulling and sealing the seconds, third and fourths! margins, against the second, third and fourth walls respectively, also comprise cables attached to the second, third and fourth margins of the flexible sheet and individually joined to a respective puller. Each of the handles has a cable deflector bar that extends substantially at the same level as a mounting plane of the handle. These handles are advantageous for pulling the margins of the flexible sheet against the mounting surface of each handle to facilitate sealing of the flexible sheet against the second, third and fourth walls. According to another feature of the present invention, a movable cover is provided for retaining malodorous gases within a clarifier having opposite first and second side walls, and a pair of opposite end walls. A plurality of spaced beams is mounted through the first and second side walls. The beams comprise first and second external beams, each having an arcuate laminated structure joined thereto, and a series of intermediate beams disposed between the first and second external beams. The flexible sheet extends over the spaced beams and the external beams. The flexible sheet has first and second longitudinal margins and first and second transverse edges. The clarifier cover further has means for retaining and sealing the first longitudinal margin towards the first side wall; means for releasably pulling and sealing the second longitudinal margin towards the second side wall, and means for pulling the flexible sheet through the beams and for releasably sealing the first and second transverse edges towards the first and second ones.
______ external beams, respectively. The means for releasably pulling and sealing the second longitudinal margin against the second side wall further comprises a tube attached to the second longitudinal margin, a first series of handles mounted to the second wall and a flexible pad extending below and adjacent to the second wall. the first series of shooters. Each handle has means for pulling the tube and the second longitudinal margin down against the flexible pad to seal the second longitudinal margin against the second side wall. The means for pulling the flexible sheet through the beams and for releasably sealing the first and second transverse edges against the first and second external beams respectively, comprise washers along the first and second transverse edges of the flexible sheet. Cables are spread through the washers. The second and third series of handles are connected to the first and second external beams respectively. The handles have means for pulling the cables and the first and second transverse edges against the first and second external beams, respectively, to seal these transverse edges against the external beams. The first, second and third series of handles have ratchet type mechanisms that are easily worked to selectively release the flexible sheet to open the clarifier and expose the equipment inside the clarifier.
_____._ «-_ .. *. > The other advantages and novel features of the present invention will become apparent from the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, an embodiment of this invention is illustrated, in which similar numbers denote similar parts in all different views, and in which: Figure 1 is a perspective view of a clarification installation showing a clarifier that it has a pair of covers according to the preferred embodiment of the present invention mounted therein from end to end; Figure 2 is a cross-sectional view of the clarifier illustrated in Figure 1 as viewed along line 2-2 in Figure 1; Figure 3 is an enlarged partial view of the joining side of the clarifier cover taken from the left side of the cross-sectional view of Figure 2; Figure 4 is an enlarged partial view of the openable side of the clarifier cover taken from the right side of the transverse view in Figure 2; Figure 5 is a partial perspective view of a preferred beam element supporting the flexible sheet on a clarifier;
____ _ ___ Im- - »» - ».... * J ~ A. M ___________ E Figure 6 is a partial perspective view of a corner of the clarifier cover, taken along the openable side thereof; Figure 6A is an enlarged partial view of the tube extending along the openable side of the flexible sheet and illustrating a keyhole-like groove in this tube, as seen in detail in circle 6A in FIG. figure 6; Figure 7 is an anterior, top, and side perspective view of the preferred puller for retaining the clarifier cover in a sealed condition; Figure 8 is an enlarged cross-sectional view of the openable side of the clarifier cover as seen along line 8-8 in Figure 6; Figure 9 is an enlarged cross-sectional view along an edge of the clarifier cover, showing a first preferred sealing arrangement of the flexible sheet on the outer beam of the clarifier cover, as seen along the line 9-9 in figure 6; Figure 10 is a schematic illustration of a first preferred sealing arrangement, as generally seen along line 10 in Figure 9, for sealing the transverse edge of the cover; Figure 11 is an enlarged cross-sectional view along an edge of the clarifier cover, showing a second preferred sealing arrangement of the flexible sheet on the outer beam of the cover
»*» «* - * - * - - i- - * clarifier fr, as seen along a similar place to the view defined by line 9-9 in Figure 6; Figure 12 is a schematic illustration of the second preferred sealing arrangement, as generally seen along the line 12 in Figure 11; Figure 13 is a horizontal projection of a triangular cover segment to cover an opening in a circular clarifier; Figure 14 is a cross-sectional view of the triangular segment, as seen along line 14-14 in Figure 13. 10 DETAILED DESCRIPTION OF THE PREFERRED MODALITY
Although this invention is susceptible to modalities in many different forms, a specific embodiment is shown in the drawings and
15 will be described in detail herein, with the understanding that the present description will be considered as an example of the principles of the invention and is not intended to limit the invention to the illustrated and described embodiments. Figure 1 illustrates a clarification installation that
20 shows juxtaposed deposits 20 each being covered by a pair of clarifier covers 22 according to a preferred embodiment of the present invention. In a typical clarification installation, each deposit or clarifier 20 is divided into two or more sections by one or more aisles
It is necessary to provide an interfiber 24. In a preferred installation, each section is covered by a clarifier cover 22 according to the preferred embodiment of the present invention and can be opened individually, both covers 22 are symmetrical. and seal together the entire reservoir 20. Peripheral passages 26 are also provided along the perimeter of each reservoir 20. In the preferred installation, a suction tube 30 and a valve 32 are connected to the intermediate passage 24, to extract biogas from down the covers 22 and to transport the biogas through a main suction pipe 34 leading to a biogas treatment plant 36. Referring now to Figures 2-5, the structure of the clarifier cover is illustrated 22 according to the preferred embodiment The reservoir 20 illustrated therein has concrete perimeter walls 40, 42 each having a configuration Type I ion and forming the peripheral passageways 26. The clarifier cover 22 comprises a series of stencils 44 which are movably secured to the opposite side walls 40, 42 of the reservoir. The beams 44 are made of a simple arched aluminum tube having an external diameter of between about 38 mm to 50 mm for installation in clarifiers having a width of about 4.3 to 6 m. The space between adjacent beams is approximately 1.2 to 1.8 m. These beams 44 are covered by a sheet of gas-impermeable flexible fabric 46, which is referred to herein as the flexible sheet. This preferred flexible sheet is a nylon-based sheet of roughaged fiber having tensile strength properties to withstand shrinkage or bending and sufficient tensile strength to support several workers walking on it between the beams. Preferably, the flexible sheet is covered with polyvinyl chloride or polypropylene to resist a variety of toxic vapors and has properties to resist deterioration by ultraviolet sunrays. The preferred flexible sheet is foldable and also has fire retardant properties. The clarifier cover 22 has a fixed side 50 to which the flexible sheet 46 is permanently attached and an openable side 55, opposite the fixed side 50. The flexible sheet 46 is attached to the fixed side 50 to be held down to the peripheral passage 26 under a first structural angle 54 extending along the fixed side 50 of the clarifier cover 22. The flexible sheet 46 has a sheath 56 along the openable side 52 of the clarifier cover , and an aluminum tube 58 is mounted within the frame 56 and extends the full length of the clarifier cover 22. The tube 58 has an outer diameter of approximately 51-76 mm. An extended flexible pad 60 made of a flexible material such as, for example, soft rubber is provided along the openable side 52. A series of handles 70 is installed along the openable side 52, within a second attached structural angle 72.
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to the openable side, for pulling the tube 58 against the flexible pad 60 and for efficiently sealing the flexible sheet 46 to the openable side 52. Each beam 44 has right angle brackets 80, one at each end Of the same. Each angle bracket 80 has a slot 82 in its lower vertical segment and one or more holes 80 in its segment 84 in its upper horizontal segment. In the preferred installation, the flange wall 86 of each reservoir 20 has protruding fastening bolts 88 which coincide in size and location with the placement of the beams 44, so that each beam joins or moves from a fastening bolt. respective 88, when operating the bolt and when lifting the beam 44 out of the bolt 88. The collection tube 30, preferably it is connected to the upper portion of the passageway 24. Preferably, a valve 32 is mounted on the collection tube 30 to isolate a reservoir 20 from the main suction tube 34, to perform inspection, maintenance or repair work therein. deposit without affecting the operation of other deposits in the same clarification facility. Returning to Figure 1, the outer beam of a clarifier cover 22 is enclosed on one side thereof by an arcuate laminated structure 90 which extends and seals against the peripheral passage 26. The opposite external beam is mounted on the laminated structure arched 92 between two clarifier covers and constitutes, with the arched laminated structure 92, the intermediate corridor 24. The arched laminated structures__________________ 90, 92 may have one or more louvers therein (not shown) to admit air under the clarifier cover 22, or to allow visual inspection of the deposit. Turning to Figure 2, the clarifier cover can be opened by winding the flexible sheet 46 over the tube 58 and along the beams 44 as illustrated. The preferred tube 58 has a square or hexagonal boss 96 at each end. One of these protuberances 96 is partially illustrated in FIGS. 4 and 6. A turkish key, a manual wheel 98 or similar tool can be mounted on these protuberances 96 to facilitate
10 the winding of the flexible sheet in the tube 58. When using a pair of manual wheels 98, one of which is shown in figure 2, two workers, one standing on an intermediate aisle 24 and the other standing on the arcuate laminated structure 90 for example, can wind the flexible sheet 46 with ease. An extended tray 100 is defined by the first structural angle 54 for receiving and holding the flexible sheet 46 in a rolled-up manner. A series of reinforcement consoles 102 are welded into this first structural angle 54 to form a support for retaining the flexible sheet wound on the holding bolts 104. When it is necessary to do the inspection or repair work inside the tank 20, the flexible sheet 46 is easily removed as described and illustrated, and a number of beams 44 can be removed and stacked side
- _. «_ ..._. _ _to. '? "- - * -: side at one end of the reservoir 20 for example, thus providing unobstructed access to the equipment within the reservoir Referring now to Figure 6, a corner of the clarifier cover 22 is illustrated in accordance to the preferred embodiment An important feature of the clarifier cover according to the preferred embodiment is that defense plates enclosing each cover are provided.The defense plates are made of the first and second structural angles 54 and 72 and two arched structural angles 110, 112 mounted on the arcuate laminated structures 90 and 92 respectively.As illustrated, the structural angles are installed with one column element extending upwards and the other column element, referred to herein as the portion base, resting on the surface of the aisles 26 or the laminated structures 90, 92. The height of the defense plates or the dimension of the element of ascending column, preferably it is at least about 10 cm. The defense plates or structural angles 54, 72, 110 and 112 are advantageous to prevent a worker from slipping and falling into the tank, or to throw a mechanical tool or maintenance equipment into the tank when the maintenance work is performed around the Deposit. To further increase the safety of workers working around the clarifier, 120 handrails are provided mounted along the clarifier cover. These handrails 120 are mounted in a series of ferrules 122 attached to the angles
_____________________ .- • ______,, _. . -....- .. __. , .- .., - ____. - * .__.,. .. _. " .. . «___._. ._! * .. < ___ structural. The handrails 120 are movable from the ferrules to make maintenance maintenance within the reflector. Another important aspect of the clarifier cover according to the preferred embodiment is the use of handles 70 for sealing the flexible sheet 46 in the external beams 44 and the open side 52 of the clarifier cover. The preferred handle 70 has a frame 130, a main shaft 132 mounted within the frame 130. A ratchet wheel 134 is attached to the main shaft 132 outside the frame. A detent 136 is also mounted on the outside of the frame 130 and interferes with the movement of the ratchet wheel 134 to maintain a tension in a cable threaded on the main shaft 132. The main shaft 132 also has a square or hexagonal rod 138 projecting out of the frame 130 on the opposite side of the frame relative to the ratchet wheel 134 and the retainer 136. The Square or hexagonal rod 138 has dimensions to be coupled with a wrench to rotate by means of a wrench. The main shaft 132 also has therein a slot 140 and a fastener 142 extending through the slot for retaining a cable 144 towards the shaft. The preferred shooter 70 also has a pair of flanges 146, to join the base portion 148 of one of the structural angles 72, 110, 112, as illustrated in FIGS. 8 and 9 in particular. The handles 70 which are mounted along the openable side 52 of the cover, are preferably supported by fastening bolts 150 extending through the flanges 146, through the base portion 148 and through the
.-._-_..._ ._-.- * ..____._-.._ _- .., * - _______________ ..___... ._._ .., _.._ ._ flexible pad 60, to hold the pad 60 down against the surface of the aisle 26. When the handle 70 is mounted on the arcuate laminated structure 90 or 92, the handle 70 is retained towards the arched laminate structure by means of common bolts 152 which extend through the flanges 146, through the base portion 148 of the structural angle 110 or 112, and through the arcuate laminated structure 90 or 92. The preferred puller 70 also has a deflector bar 156 mounted in the frame , below the flanges 146. The baffle bar 156 is particularly advantageous for changing the force direction of the puller to pull the flexible sheet downwardly as illustrated and described hereinafter, to better seal the clarifier cover 22. Sealing the clarifier cover 22 along the openable side 52, is made by pulling the the tube 58 down against the flexible pad 60. This is done using different handles mounted along the structural angle 72, each having a cable 144 and a narrowed knob 158 at the end of that cable 144. The knobs 158 are inserted in keyhole grooves 160 which are illustrated in Figures 6 and 6A. The cables 144 are pulled from below the deflector bars 156 and towards the handles 70, to pull the tube 58 downwardly against the flexible pad 60 and to pull the longitudinal margin of the flexible sheet 46 along the beams 44 and through of the deposit. Preferably, the tube 58 is supported to the hem 56 by means of a plurality of fasteners 162
^^ g ^ = ^ U that extends across the longitudinal margin of the flexible sheet and to
• », - through the wall of the tube 58. The preferred space between the handles 70 along the openable side 52 is about 0.6 to 1.8 m for common clarifier installations. The release of the handles 70 to open the clarifier cover is performed by working the hexagonal rod 138 and the detent 136 as is normal with common ratchet type lathes. The sealing of the clarifier cover 22 along both outer beams 44 is performed with other series of handles 70 spaced at
10 along the arcuate structural angles 110 and 112 as illustrated in Figures 6 and 9. The flexible sheet 46 has washers 170 along each transverse edge thereof and a cable loop 172 extending through each washer. The locations of the washers 170 correspond to the locations of the handles 70 along the structural angles 110, 112. Each cable tie 172 engages below the deflection bar 156 and on the main shaft 132 of each handle 70. As illustrated in Figure 9, the baffle bar 156 is generally closer to the mounting structure 90 as is the upper segment 174 of each beam 44. Accordingly, the edge of the flexible sheet 46 is pulled down for each cable tie
20 172, as indicated by arrow 176 in FIGS. 9 and 10. In the first preferred arrangement, the cable ties 172 are part of a continuous cable 178 extending along the transverse edge of the flexible sheet 46 and through all the washers 170. The 178 cable has straight segments 180
& ^ ss | , ^ _ ^ _ g ^^ _ ^ _ ^. ^. ^. *. ^ __ ^ * ^ ._ ^^, _ * _____ .. _, ___ .. ».
S? Fel. which extend between adjacent loops 172. Therefore, when a loop 172 is pulled towards a handle 70, the tension of the wire is applied to the respective washer 170 in a downward direction 176 as indicated above, and also in a circumferential direction as indicated by 5 the arrows 182. These combined forces 176, 182 are advantageous for pulling the flexible sheet 46 against the beams 44 and to prevent the flexible sheet from slipping through the beams 44 in strong wind conditions for example, or when one or more workers walk on the flexible sheet by any
10 reason. The circumferential tension 182 of the cable 178 causes the arc defined by the straight segments 180 to have a radius smaller than the radius of the upper segment 174 of the external beam 44. This feature is advantageous to prevent the sliding of the flexible sheet through and through. on the external beam 44 in a variety of tension conditions. Referring now to Figures 11 and 12, there is illustrated a second preferred arrangement for sealing the edges of the flexible sheet 46 against the outer beam 44. In this second preferred arrangement, the defense plate along the arched laminate structures 90 or 92 is made of a curved flat bar 190 joined to a curved structural channel 192, whose
20 flanges are down. The mesh portion of the channel 192 has a series of slots 194 therein, the places and space of which correspond to the locations and space of the washers 196 along the transverse edge of the flexible sheet 46. The flexible sheet is attached to channel 192 through
| ^ __i_____li__ of a cable 198 extending into the channel and through the slots 194 and washers 196. The preferred cable 198 has along it a series of preformed loops 200. Each loop 200 is defined by a bracket 202. length "L" of each loop 200 is equal to a space "L" between two adjacent washers 196. This feature is advantageous for attaching the transverse edge of the flexible sheet to channel 192 by inserting each loop through a washer and into a adjacent loop, as illustrated in Figure 12. In this second preferred installation, both ends of the cable 198 are attached to a respective puller 70, one of which is shown in Figure 12. By tightening the puller 70, the cable 198 is stretched around the circumference of the arcuate laminated structure 90 or 92 as illustrated by the arrows 204 to further seal the transverse edge of the flexible sheet against the outer beam 44. Although it has been described in FIG. After a rectangular clarifier cover, it will be appreciated that the principles and structural arrangements of the present invention are not limited to rectangular clarifiers, but are also applicable to clarifiers having circular or polygonal perimeters. For example, Figures 13 and 14 illustrate partial details of a triangular cover segment 210 to cover an opening in a circular clarifier. The cover segment 210 consists of a sheet of flexible gas-impermeable fabric with washers along the sides thereof. The circular clarifier of interest in the present, has a rigid cover with a
_.-__._. . _ __ *, ti I) f 1 i "" "or more triangular openings, through which the inspection and repair work is carried out within the clarifier.The circular clarifier structure is not illustrated here as it is evident in the above description In this circular clarifier, each triangular opening is suitable for cover through a cover segment 210 and can be opened by winding the cover segment 210 in a flexible tube 212, similarly as described above for the rectangular clarifier The cover can be opened completely as described above for the rectangular clarifier, or partially as illustrated herein with portions of the cover segment 210 being securely attached to the clarifier structure. 210 is partially or completely supported on the frame 214 of the clarifier by different handles 70 mounted within the angles is 216, also as previously described and aligned along one or both sides of the triangular opening. The angles 216 are attached to the rigid portions of the clarifier cover (not shown) and constitute defense plates along both sides of the triangular opening. In this particular installation, the flexible tube 212 is preferably made of different straight sections joined together through flexible joints that transmit tension 218. The flexible tube 212 is therefore able to work between a straight way to wind the cover segment on the same, and a curved mode to better seal the cover segment 210 against Tt a circular clarifier wall 220. Although the flexible tube is illustrated herein! preferred 212 with the joints 218, it will be appreciated that it can be made for example of a single section of flexible plastic material. Another series of handles 70 is mounted on the outer surface 5 of the clarifier wall 220 and is used to retain the flexible tube 212 and the cover segment 210 in a closed manner. The structural angle 222 which retains the handles 70 towards the clarifier wall constitutes a counter to prevent damage to the cover segment 20 and the flexible tube 212 by equipment, such as lawn mowers that move near the wall of the wall.
10 clarifier. When the triangular cover segment is partially open, the fixed portion 224 is permanently secured to the clarifier structure by means of clamping rods 226 for example along both sides thereof. An intermediate tubular bar 228 preferably
15 is attached to the fixed portion 224 and rigidly supported by two handles 70 mounted on the clarifier structure 214. For convenience, the triangular cover segment 210 may also be retained to a channel and planar bar structure 230, as described in the present as the second preferred arrangement and
20 as e.e illustrated in Figures 11 and 12. In this case, the edge of the triangular segment is attached to the channel and to the flat bar structure 230 by a continuous suspension rope 232 as described and illustrated above.
_Hr__É__lri_ltlfcMfc '* - jt-'w - • * k - • * - • - - «• - - •'" • »• * * _ In view of the above, it will be appreciated that many changes and modifications can be made to the embodiments illustrated and described without departing from the spirit of this invention, Therefore, the foregoing description and illustrations should not be construed as limitations on the scope of the invention which is defined by the appended claims.
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