Patent Publication Number: US-2022219888-A1

Title: Self-Cleaning Tank

Description:
This application is a divisional of U.S. application Ser. No. 16/459,285, filed on Jul. 1, 2019 entitled “Self-Cleaning Tank”, which is a divisional of U.S. application Ser. No. 15/172,941, filed on Jun. 3, 2016 entitled “Self-Cleaning Tank”, which is a continuation of U.S. application Ser. No. 14/255,778, filed on Apr. 17, 2014 entitled “Self-Cleaning Tank”, which claims priority to U.S. Provisional Application No. 61/820,009, filed on May 6, 2013, and entitled “Self-Cleaning Tank,” both of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Tanks exist that have sloped bottoms to help empty and/or clean solids from the bottom of the tank. However, because these solids adhere to the bottom of the tank, some of the solids do not slide out of the tank. Thus, removal and/or cleaning of the deposited solids from the bottom of the tank is labor intensive, time consuming, and costly. Moreover, because workers must enter the confined space of the tanks to remove and/or clean the deposited solids from the bottom of the tank, the workers entering the confined space are exposed to hazardous confined space conditions and atmosphere. 
     Accordingly there remains a need in the art for a tank that is less labor intensive to clean, takes less time to clean, and does not require workers to enter the tank at any time. 
     SUMMARY 
     This summary is provided to introduce simplified concepts of a self-cleaning tank and method, which is further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter. 
     In one example, a container comprising a tank for holding a product includes a scraper blade assembly slideably coupled to a bottom surface of the tank. The scraper blade assembly includes a blade arranged to displace solids deposited on the bottom surface of the tank through an aperture arranged in a wall of the tank to clean the tank. In another example, the blade may comprise a scraping member arranged to interfere with a wall and/or the bottom surface of the tank. The scraping member may displace solids out through the aperture arranged in the tank. 
     In another example, a container comprising a tank having a bottom surface having a non-zero slope relative to a horizontal support surface includes a scraper blade assembly slideably coupled to the sloped bottom surface of the tank. The tank may include an aperture arranged at the lowest portion of the slope of the bottom surface of the tank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. 
         FIG. 1A  illustrates a front view of an example self-cleaning tank. 
         FIG. 1B  illustrates a side view of the example self-cleaning tank shown in  FIG. 1A . 
         FIG. 2  illustrates a partial cutaway perspective view of the self-cleaning tank shown in  FIGS. 1A and 1B . 
         FIG. 3  illustrates a detail view of an example scraper blade assembly shown through a partial cutaway in the side of the self-cleaning tank. 
         FIG. 4  illustrates a perspective view of an example scraper blade assembly shown slideably coupled to a bottom surface of a tank. 
         FIG. 5  is a flow diagram illustrating an example process of using a self-cleaning tank having an example scraper blade assembly. 
         FIG. 6  and  FIG. 7  illustrate perspective views of an alternative example scraper blade assembly coupled to a bottom surface of a tank. 
         FIG. 8  illustrates a perspective view of a portable hydraulic power unit removeably coupled to a hydraulic motor disposed underneath a solid bottom surface of a tank. 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     This disclosure is directed to self-cleaning tanks that are less labor intensive to clean and take less time to clean than ordinary tanks, and do not require workers to enter the self-cleaning tanks at any time during the cleaning process. The self-cleaning tank may include a scraper blade assembly slideably coupled to the self-cleaning tank, which provides the necessary displacement of solids deposited on a bottom surface of the self-cleaning tank to clean out the self-cleaning tank, and which eliminates the need for any workers to enter the self-cleaning tank at any time. For example, a user may simply open a gate on the self-cleaning tank, and activate the scraper blade assembly. The activated scraper blade assembly displaces solids deposited on the bottom surface of the self-cleaning tank through the open gate and out of the self-cleaning tank, but without any worker entering the tank at any time. Stated otherwise, the scraper blade assembly may be activated by a worker outside of the self-cleaning tank to remove the solids deposited inside the self-cleaning tank, thus eliminating any need for workers to enter the self-cleaning tank to remove the solids. 
     The scraper blade assembly may include a blade having a leading edge opposite a trailing edge. The leading edge of the blade may displace solids deposited on the bottom surface of the self-cleaning tank through an aperture arranged in a wall of the self-cleaning tank to clean the self-cleaning tank. For example, the leading edge of the blade may slideably rotate on the bottom surface of the self-cleaning tank and push the solids out through an aperture arranged flush with the bottom surface of the self-cleaning tank. 
     The scraper blade assembly may include a blade having a portion of the leading edge and/or trailing edge of the blade that interferes or interfaces with the bottom surface of the self-cleaning tank. Moreover, the scraper blade assembly may include a portion of the leading edge and/or trailing edge of the blade that interferes or interfaces with a wall of the self-cleaning tank. For example, the scraper blade assembly may include one or more scraping members fixed to the blade, or formed integral with the blade, that interferes or interfaces with a wall and/or a bottom surface of the self-cleaning tank. 
     The portion of the leading edge and/or trailing edge of the blade that interferes with the wall of the self-cleaning tank may protrude out of the aperture when the blade passes along the aperture. For example, the portion the blade that interferes with the wall of the self-cleaning tank may be in a deflected or deformed state when interfering with the wall, and when passing along the aperture the portion of the blade that interferes with the wall of the self-cleaning tank may not be in a deflected or deformed state, penetrating the aperture. Stated otherwise, the portion of the blade that interferes with the wall is deflected back along the wall of the tank until the blade enters the aperture, at which point the blade juts out past the wall and into the aperture. In this way the portion of the blade that interferes with the wall of the self-cleaning tank may push the solids out of the opening as the portion of the blade that interferes with the wall of the self-cleaning tank passes along the aperture. 
     The scraper blade assembly may be rotatably coupled to a self-cleaning tank having a sloped bottom surface. The self-cleaning tank may include an aperture arranged in a wall of the self-cleaning tank. The aperture arranged in the wall having a portion arranged at a lowest portion of the slope of the bottom surface of the tank. For example, the self-cleaning tank may include an aperture at the bottom and flush with the bottom of the self-cleaning tank for removing the solids from the self-cleaning tank. 
     Illustrative Self-Cleaning Tank 
       FIG. 1A  illustrates a front view of an example self-cleaning tank  102 . The tank  102  may be fermentation tank, for example. For example, the tank  102  may be a red wine fermenter for holding a juice. The tank  102  may be a self-emptying or self-cleaning tank. For example, once the fermentation process has been completed, and the wine (juice) removed, the pomace remains in the bottom of the tank (e.g., tank  102 ). The pomace consists of grape skins, seeds, and spent yeast. This must be removed from the tank  102  where it will be subsequently pressed of any remaining juice and disposed of. Typically the pomace is removed manually with rakes and shovels, requiring considerable time and manpower. Moreover, typically a worker must enter a tank to manually rake and shovel the pomace out of the tank, presenting considerable hazardous conditions for the workers entering the tank. However, the self-cleaning tank  102  is faster, less labor intensive, and safer to empty the pomace from the self-emptying tanks  102  than traditional tanks. The tank may include a manway gate assembly  104  coupled to the tank  102 . Any suitable manway gate may be used. By way of example and not limitation, suitable manway gate assemblies are disclosed in U.S. Provisional Patent Application No. 61/755,416, filed on Jan. 22, 2013, titled “Sliding—Locking Below Liquid Manway Door,” which is incorporated by reference herein in its entirety. The tank  102  may have an outside diameter  106  of about 177 inches. The tank  102  may have a volume of about 29,100 gallons. While  FIG. 1A  illustrates a tank having an outside diameter  106  of about 177 inches and a volume of about 29,100 gallons, the tank may be of any size and or shape. 
       FIG. 1B  illustrates a side view of the example self-cleaning tank  102  shown in  FIG. 1A .  FIG. 1B  illustrates the tank  102  including a bottom surface  108  opposite a top surface  110 . In some examples the bottom surface  108  may be a substantially solid bottom surface. For example, the solid bottom surface may be void of perforations, cracks, filters, grates, or any other apertures. The bottom surface  108  may have a slope  112 . For example, the bottom surface  108  may have a relatively steep slope (e.g., a rise of at least about 0.26 inches or a rise of at least about 47 inches over a run of about 177 inches) to provide for the pomace having somewhat the consistency of jam to slide out easily. In another example, the bottom surface  108  may have a relatively gentle slope (e.g., less than 0.26 inches). In some specific examples, relatively gentle slopes may include slopes from about a 0.1 inch rise to a 12 inch run to slopes of about a 2 inch rise to a 12 inch run to limit the length of an elliptical perimeter of the bottom surface. The bottom surface  108  has a perimeter and defines a first plane. The perimeter of the bottom surface  108  may depend on the diameter of the tank. For example, the perimeter of the bottom surface  108  may include a substantially curvilinear shape having a diameter of about 177 inches. The bottom surface  108  may have a substantially circular shape, elliptical shape, parabolic shape, etc. For example, the bottom surface may have an elliptical perimeter having a major axis longer than a minor axis. The first plane may have substantially the same slop as the bottom surface  108 . For example, the first plane may have a steep slope (e.g., a rise of at least about 0.26 inches or a rise of at least about 47 inches over a run of about 177 inches) or have a gentle slope (e.g., less than 0.26 inches). While  FIG. 1B  illustrates the bottom surface  108  having a steep slope  112 , the bottom surface  108  may have any slope. For example, the bottom surface  108  may be substantially horizontal (e.g., a rise of substantially 0 inches over a run of about 177 inches). 
       FIG. 1B  illustrates the tank  102  having a height  114  of about 362 inches from surface of ground  116  to a top  118  of the tank  102 . While  FIG. 1B  illustrates the tank  102  having a height of about 362 inches, the tank  102  may have any height. The lowest portion  120  of the slope  112  of the bottom surface  108  of the tank  102  may be arranged a distance  122  above the ground  116 . For example, the lowest portion  120  of the slope  112  of the bottom surface  108  of the tank  102  may be arranged about 42 inches above the ground  116  to provide for placing a receptacle (e.g., box, container, bin, and/or conveyor) under the manway gate assembly  104 . While  FIG. 1B  illustrates the tank  102  having a lowest portion arranged about 42 inches above the ground, the lowest portion of the ground may be arranged at any height above the ground. The manway gate assembly  104  may be fixed to the tank  102  proximate to the lowest portion  120  of the slope  112  of the bottom surface  108  of the tank  102  to provide for controlling the flow rate of product (e.g., pomace) emptying from the tank  102  to the receptacle. 
       FIGS. 1A and 1B  illustrates a wall  124  fixed between the bottom surface  108  and the top surface  110 . For example, the wall  124  may be fixed to an elliptical perimeter of the bottom surface  108  and between the bottom surface  108  and the top surface  110 . An aperture  126  may be arranged in the wall  124  of the tank  102 . The aperture  126  having a portion proximate to the lowest portion  120  of the slope  112  of the bottom surface  108  of the tank  102 . In one example, the aperture  126  may be arranged in the wall  124  of the tank  102  and aligned with the major axis of the elliptical perimeter of the bottom surface of the tank  102 .  FIGS. 1A and 1B  illustrate the manway gate assembly  104  arranged around the aperture  126  to empty the product held in the tank  102 . For example, the aperture  126  and the manway gate assembly  104  may both be arranged flush with the lowest portion  120  of the slope  112  of the bottom surface  108  of the tank  102  to provide for displacing solids out of the tank  102 . Stated otherwise a bottom portion of the manway gate assembly  104 , a bottom portion of the aperture  126 , and the lowest portion  120  of the slope of the bottom surface  108  of the tank  102  may form a substantially smooth planar surface to provide for displacing solids out of the tank  102 . 
       FIG. 1B  illustrates a motor and gear reduction  128  disposed underneath the bottom surface  108  of the tank  102 . The motor and gear reduction  128  may be used to power a scraper blade assembly slideably coupled to the tank  102  (discussed in detail below with regard to  FIG. 2 ). The motor may be about a 15 horsepower motor and the gear reduction may comprise a  400  to  1  gear reduction. In another example, the motor may be about a 7.5 horsepower motor and the gear reduction may comprise a  900  to  1  gear reduction. In yet another example, the motor may be a hydraulic motor and a separate (e.g., free standing and/or portable) hydraulic power unit (e.g., power pack) may removeably couple with the hydraulic motor. 
       FIG. 2  illustrates a cutaway view  202  of the self-cleaning tank  102  shown in  FIGS. 1A and 1B . The cutaway view  202  illustrates a scraper blade assembly  204  slideably coupled to the tank  102 . For example, the cutaway view  202  illustrates the scraper blade assembly  204  slideably coupled to the bottom surface  108  of the tank  102 . The scraper blade assembly  204  may be rotatably coupled to the bottom surface  108  of the tank  102  to sweep the bottom surface  108  of the tank  102 . For example, the scraper blade assembly  204  may be rotatably coupled proximate to a center of the bottom surface  108  of the tank  102 , and powered by the motor and gear reduction  128  that sweeps a blade along the bottom surface  108  of the tank  102 . While  FIG. 2  illustrates the scraper blade assembly  204  rotatably coupled to the center of the bottom surface  108  of the tank  102 , the scraper blade assembly  204  may be rotatably coupled to a perimeter of the tank  102 . For example, the scraper blade assembly  204  may be slideably coupled to a track system arranged around a perimeter of the bottom surface  108 . Moreover, the scraper blade assembly  204  may not be rotatably coupled to the tank  102 . For example, the scraper blade assembly  204  may slide linearly on the bottom surface  108  of the tank  102 . For example, the scraper blade assembly  204  may slide linearly from front to back of the tank  102 . Depending on the desired esthetic and mechanical properties of the scraper blade assembly  204  and/or the tank  102 , components may comprise metal, plastic, and/or ceramic. For example, the scraper blade assembly  204  and/or the tank  102  may comprise steel (e.g., stainless), copper, titanium, rubber, silicone, and/or Teflon. 
       FIG. 3  illustrates a detail view  302  of the example scraper blade assembly  204  shown in the cutaway view  202  of  FIG. 2 .  FIG. 3  illustrates the bottom surface  108  having a perimeter  304  and defining a first plane  306 . The wall  124  may be fixed to the perimeter  304  of the bottom surface  108 . In one example, the bottom surface  108  may have an elliptical perimeter defining the first plane  306  and the wall  124  may be fixed to the elliptical perimeter of the bottom surface and between the bottom surface and the top surface. The scraper blade assembly  204  may include a blade  308  defining a second plane  310  parallel to the first plane  306 . The blade  308  may include a leading edge  312  opposite a trailing edge  314 . The blade  308  may rotate in a direction  316  towards the leading edge  312 .  FIG. 3  illustrates a portion  318  of the leading edge  312  of the blade  308  interfering with the bottom surface  108  of the tank  102 . While  FIG. 3  illustrates the portion  318  of the leading edge  312  of the blade  308  interfering with the bottom surface  108  of the tank  102 , the portion  318  or another portion, different from the portion  318 , may interfere with the bottom surface  108  of the tank  102 .  FIG. 3  illustrates a portion  320  of the leading edge  312  of the blade  308  may interfere with the wall  124  of the tank  102 . While  FIG. 3  illustrates the portion  320  of the leading edge  312  of the blade  308  interfering with the wall  124  of the tank  102 , the portion  320  or another portion, different from the portion  318 , may interfere with the wall  124  of the tank  102 . 
     The portions  318  and  320  of the blade  308  may be scraping members formed of a material different from a material forming the blade  308 . For example, the blade may be formed of metal (e.g., steel, stainless steel, aluminium, copper, brass, etc.) and the portions  318  and/or  320  may be scraping members formed of a plastic (e.g., a polyamide (PA), Acrylonitrile butadiene styrene (ABS), Poly(methyl methacrylate) (PMMA), Polyethylene terephthalate (PET), etc.). Moreover, the scraping member portions  318  and  320  and the blade  308  may be of formed of a single unit of material. For example, the scraping member portions  318  and  320  and the blade  308  may be formed of a single unit of metal, a single unit of plastic, a single unit of composite or the like. Further, the scraping member portions  318  and  320  may be the same or different material than the tank. For example, the scraping members could be chosen of a material softer than the tank material so that the scraping members don&#39;t wear through the bottom surface and/or wall of the tank. In one example, the portion  320  may be an extendable scraping member arranged at an end of the leading curvilinear surface to maintain contact with a wall fixed to an elliptical perimeter of the bottom surface of the tank. For example, when the blade is rotatably displaced in the second plane the extendable scraping member may recede to follow the wall of the tank when displaced along a minor axis of the elliptical perimeter of the bottom surface of the tank and may extend outward to maintain contact with the wall of the tank when displaced along a major axis of the elliptical perimeter of the bottom surface of the tank. The extendable scraping member may extend toward the wall of the tank when displaced along a major axis of the elliptical perimeter of the bottom surface of the tank to displace solids deposited along the elliptical perimeter of the bottom surface of the tank through the aperture arranged in the wall of the tank to clean the tank. The scraping member may, in some examples, protrude slightly from the aperture to ensure complete displacement of solids from the tank. 
       FIG. 3  illustrates the blade  308  having a substantially curvilinear shape. For example,  FIG. 3  illustrates the blade  308  having a substantially elongated s-shape. The elongated s-shaped blade  308  having a first end  322  opposite a second end  324 .  FIG. 3  illustrates the substantially elongated s-shaped blade  308  spanning a width of the bottom surface  108  of the tank  102 , and the first and second ends  322  and  324  disposed proximate to the wall  124  of the tank  102 . While  FIG. 3  illustrates the blade  308  having only one scraping member portion  320  fixed to the first end  322  of the blade  308 , the blade  308  may include another scraping member fixed to the second end  322  of the blade  308 . Moreover, while  FIG. 3  illustrates the blade  308  having a curvilinear shape, the blade may have any shape suitable for displacing solids out of the tank  102 . For example, the blade  308  may have a substantially rectilinear shape, x-shape, y-shape, u-shape, triangular shape, etc. The first and/or second ends  322  and  324  of the blade  308  may be made of a “spring” or “elastically deformable” material. A support member may be fixed between the pivot of the blade  308  and the first and/or second ends  322  and  324 . For example, a rigid bar may be fixed between the first and/or second ends  322  and  324  to structurally support the first and/or second ends  322  and  324  against a high torque load. 
       FIG. 4  illustrates a perspective view  402  of the scraper blade assembly  204  shown slideably coupled to the bottom surface  108  of a tank  102 .  FIG. 4  illustrates the leading edge  318  of the blade  308  arranged to displace solids deposited on the bottom surface  108  of the tank  102  through the aperture  126  arranged in the wall  124  of the tank  102  to clean the tank  102 . For example,  FIG. 4  illustrates the blade  308  rotating in the direction  316 , and pushing the leading edge  318  of the blade  308  in the direction of the aperture  126 . The blade  308  displaces the solids deposited on the bottom surface  108  of the tank  102  in a direction  404  towards the aperture  126 . The scraping member portion  320  fixed to the first end  322  of the blade  308  displaces the solids out through the aperture  126 . For example, the scraping member portion  320  fixed to the first end  322  of the blade  308  rotates in the direction  316  along the wall  124  in a deflected or deformed state until the scraping member portion  320  fixed to the first end  322  of the blade  308  penetrates the aperture  126 . When the blade  308  rotates the scraping member portion  320  into the aperture  126 , the scraping member portion  320  of the blade  308  may penetrate (i.e., protrude slightly from) the aperture  126 . When the blade  308  rotates the scraping member portion  320  along the aperture  126  the scraping member portion  320  may extend out past the wall  124  of the tank  102  to displace the solids in a direction  406  out through the aperture  126 . In another example, the scraping member may recede to follow the wall of the tank when displaced along a minor axis of the elliptical perimeter of the bottom surface of the tank and extend outward to maintain contact with the wall of the tank when displaced along a major axis of the elliptical perimeter of the bottom surface of the tank to displace the solids in a direction  406  out through the aperture  126 . In another example, when the blade  308  rotates the scraping member portion  320  along the aperture  126  the scraping member portion  320  may not extend out past the wall  124  of the tank  102 . 
       FIG. 4  illustrates a portion  408  of the aperture  126  arranged flush with the bottom surface  108  of the tank  102  to provide for displacing solids out of the tank  102 . For example,  FIG. 4  illustrates the bottom portion  408  of the aperture  126  and the bottom surface  108  of the tank  102  forming a substantially smooth planar surface to provide for the scraping member portion  320  to extend to and/or out past the wall  124  and displaces the solids in the direction  406  out through the aperture  126 . The aperture  126  may have a substantially same radius as the wall  124  of the tank  102 . Moreover, the aperture  126  may have a substantially planar shape. 
     Example Method of Using a Self-Cleaning Tank 
       FIG. 5  illustrates an example method  500  of using an example self-cleaning tank (e.g., self-cleaning tank  102 ) based at least in part on a scraper blade assembly (e.g., scraper blade assembly  204 ) slideably coupled to the tank. For instance, this process may be performed to empty and/or clean a self-emptying or self-cleaning tank, which has a bottom surface (e.g., bottom surface  108 ) having a slope (e.g., slope  112 ) and the scraper blade assembly slideably coupled to the bottom surface, which provides for a more efficient removal of pomace in the bottom of the tank. While  FIG. 5  illustrates a method of using a self-cleaning tank configured to provide a faster, less labor intensive, and safer removal of pomace, this method may apply to using self-cleaning tanks configured for removal of other types of solids. For example, the self-cleaning tank may be used to provide efficient removal of petroleum solids, a septic solids, yeast solids etc. 
     Method  500  may include an operation  502 , which represents opening an aperture (e.g., aperture  126 ) arranged in a tank to clean the tank. For example, operation  502  may include selectively opening a manway gate assembly (e.g., manway gate assembly  104 ). For example, a user may selectively slide the gate to an open position to open the tank. Method  500  may proceed to operation  504 , which represents actuating a scraper blade assembly. For example, subsequent to opening the manway gate assembly, and while the aperture of the tank is open, a user may selectively activate the scraper blade assembly. In one example, the actuating of the scraper blade assembly, may include remotely actuating a motor (e.g., motor and gear reduction  128  or motor and gear reduction  606 ) coupled to the solid bottom surface of the tank, and rotating a shaft of the motor protruding from the solid bottom surface of the tank at substantially a right angle relative to the sloped bottom surface of the tank and substantially at an obtuse angle relative to a substantially planar surface of ground the tank stands on. In another example, the actuating of the scraper blade assembly, may include removeably coupling a separate (e.g., free standing and/or portable) hydraulic power unit (e.g., power pack) may to a hydraulic motor disposed underneath the bottom surface of the tank and/or energizing (e.g., turning on) the separate hydraulic power unit. Method  500  may include operation  506 , which represents displacing a scraping member (e.g., scraping member portion  320 ) along a portion (e.g., portion  408 ) of the aperture arranged proximate to a lowest portion (e.g., lowest portion  120 ) of a slope (e.g., slope  112 ) of a bottom surface (e.g., bottom surface  108 ) of the tank. Method  500  may include operation  508 , which represents displacing solids deposited on the bottom surface of the tank in a direction (e.g., direction  404 ) towards the aperture, via a blade (e.g., blade  308 ) rotatably coupled to the bottom surface of the tank. 
     Method  500  may be complete at operation  510 , which represents displacing, via the scraping member, solids deposited on the bottom surface of the tank through the portion of the aperture arranged proximate to the lowest portion of the slope of the bottom surface of the tank. 
     Alternative Example Scraper Blade Assembly 
       FIG. 6  and  FIG. 7  illustrate perspective views of an alternative example, scraper blade assembly coupled to a bottom surface of a tank.  FIG. 6  illustrates a scraper blade assembly  602  slideably coupled to a bottom surface  604  of a tank with the wall of the tank omitted for clarity. Similar to the bottom surface  108  discussed above with regards to  FIG. 1B , in some embodiments, the bottom surface  604  may have a non-zero slope  112 . For example, the bottom surface  604  may have a relatively gentle slope (e.g., at least about a 0.1 inch rise to a 12 inch run up to at most about a 2 inch rise to a 12 inch run). The relatively gentle slope limits the length of an elliptical perimeter of the bottom surface, and maximizes a volume of the tank. For example, the relatively gentle slope of the bottom surface  604  reduces the height and/or outside diameter (e.g., height  114  and/or outside diameter  106 ) of the tank as compared to a relatively steep slope where the height and/or outside diameter would have to be larger to accommodate the same volume of the tank. 
     Similar to the scraper blade assembly  204  discussed above with regards to  FIG. 3 , in some embodiments, the scraper blade assembly  602  may be rotatably coupled to the bottom surface  604  of the tank to sweep the bottom surface  108  of the tank. For example, the scraper blade assembly  602  may be rotatably coupled proximate to a center of the bottom surface  604  of the tank. The scraper blade assembly  602  may, for example, be powered by a motor and gear reduction  606  that sweeps a blade  608  along the bottom surface  604  of the tank. In some examples, the motor and gear reduction  606  may be coupled to the solid bottom surface  604  of the tank. For example, a gearbox of the motor and gear reduction  606  may be fastened via mechanical fasteners to a portion of an underside of the bottom surface  604  of the tank. In one example, the gearbox may be fastened to a portion of the stand adjacent to the underside of the bottom surface  604  of the tank. Further, a gasket (e.g., a dry seal) may be arranged around a drive shaft extending from the gearbox and protruding through the stand and into the bottom surface  604  of the tank. Stated otherwise, a gasket may be arranged between the drive shaft and the bottom surface  604  of the tank. 
     In other examples, other drive mechanisms may be used to drive the scraper blade assembly  602 . For example, a hydraulic motor disposed underneath the bottom surface of the tank may drive the scraper blade assembly  602  when a separate hydraulic power unit, removeably coupled to the hydraulic motor and arranged proximate to the tank, is energized or turned on. 
     The bottom surface may have an elliptical perimeter  610  defining a first plane  612  and the blade  608  may define a second plane  614  parallel to the first plane  612 . The blade  608  may include a leading edge  616  opposite a trailing edge  618 . The blade  608  may rotate in a direction  620  towards the leading edge  616 . A portion  622  of the leading edge  312  of the blade  608  may interfere with the bottom surface  604  of the tank. Similar to the scraper blade assembly  204  discussed above with regards to  FIG. 3 , in some embodiments, the portions  622  of the blade  608  may be scraping members formed of a material different from a material forming the blade  608 . For example, the blade  608  may be formed of metal (e.g., steel, stainless steel, aluminium, copper, brass, etc.) and the portions  622  may be scraping members formed of a plastic (e.g., a polyamide (PA), Acrylonitrile butadiene styrene (ABS), Poly(methyl methacrylate) (PMMA), Polyethylene terephthalate (PET), etc.). The blade  608  may include an extendable scraping member  624  arranged at an end of a leading curvilinear surface  626  to contact a wall (not shown) fixed to the elliptical perimeter  610  of the bottom surface  604  of the tank. For example, when the blade  608  is rotatably displaced the extendable scraping member  624  may recede to follow the wall of the tank when displaced along a minor axis  628  of the elliptical perimeter  610  of the bottom surface  604  of the tank and may extend outward to maintain contact with the wall of the tank when displaced along a major axis  630  of the elliptical perimeter  610  of the bottom surface of the tank to displace solids deposited along the elliptical perimeter of the bottom surface of the tank through the aperture arranged in the wall of the tank to clean the tank. In one example, the minor axis  628  may be about 177 inches, and the major axis  630  may be about 178 inches. In another example, the blade  608  may not include an extendable scraping member  624 . For example, the blade  608  may not include the extendable scraping member  624 , and when the blade  608  is rotatably displaced the blade  608  may be free of contact with the wall of the tank. 
       FIG. 6  illustrates examples in which the motor and gear reduction  606  have a drive shaft  632  protruding from the solid bottom surface  604  of the tank at a substantially right angle relative to the slope of the solid bottom surface. The drive shaft  632  may couple with the blade  608  of the scraper blade assembly  602 . In other examples however, a hydraulic motor may be disposed underneath the solid bottom surface  604  of the tank and the hydraulic motor may have the drive shaft  632  protruding from the solid bottom surface  604 . In the example where a hydraulic motor has a drive shaft  632  protruding from the solid bottom surface  604  of the tank at a substantially right angle relative to the slope of the solid bottom surface, a portable hydraulic power unit may removeably couple with the hydraulic motor to power the hydraulic motor to rotate the blade  608  in a direction  620  towards the leading edge  616 . 
       FIG. 7  illustrates the scraper blade assembly  602  may include a trailing support structure  702  arranged behind the leading curvilinear surface  626  of the blade  608 . For example, a rigid plate may be fixed behind the leading curvilinear surface  626  of the blade  608  to structurally support leading curvilinear surface  626  against a high torque load. The leading curvilinear surface  626  of the blade  608  may have a slope steep enough to push the deposited solids in a direction towards an aperture arranged in the wall of the tank but not too steep to trap deposited solids against the wall of the tank. For example, the slope of the leading curvilinear surface  626  may be at least about a 6 degree angle from a centerline of the blade  608  to at most about a 24 degree angle from a centerline of the blade. In one example, the slope of the leading curvilinear surface  626  may be at least about a 12 degree angle from a centerline of the blade  608 . In another example, the slope of the leading curvilinear surface  626  may be at least about a 15 degree angle from a centerline of the blade  608 . While  FIG. 7  illustrates the scraper blade assembly  602  including a leading curvilinear surface  626 , the leading surface of the blade  608  may be substantially rectilinear. 
       FIG. 8  illustrates examples in which a hydraulic power unit  802  may be coupled to a hydraulic motor  804  disposed underneath the solid bottom surface  604  of a tank with the wall of the tank omitted for clarity. The hydraulic power unit  802  may be a portable hydraulic power unit and may be positioned adjacent to the tank and removeably coupled to the hydraulic motor  804  via one or more hydraulic lines  806 (A) and  806 (B). In one example, the one or more hydraulic lines  806 (A) and  806 (B) may removeably couple with the portable hydraulic power unit  802  and/or the hydraulic motor  804  via quick disconnect hydraulic fittings. In examples where the portable hydraulic power unit  802  is removeably couplable to a hydraulic motor  804  disposed underneath the solid bottom surface  604  of a tank, the portable hydraulic power unit  802  may be used to power other hydraulic motors  804  disposed underneath other tanks. For example, a single portable hydraulic power unit may be used to power a first hydraulic motor of a first tank and then used to power a second hydraulic motor of a second tank. For example, after the first tank is clean, the portable hydraulic power unit may be disconnected from the first hydraulic motor and subsequently connected to the second hydraulic motor on the second tank to clean the second tank. 
     In another example, a hydraulic power unit  802  may be used to power a plurality of hydraulic motors  804  disposed underneath a plurality of tanks. For example, one or more manifolds and/or valves may be communicatively coupled with a single hydraulic power unit  802 , and communicatively coupled to the plurality of hydraulic motors  804  disposed underneath the plurality of tanks. The hydraulic power unit  802  may be fixed at a central location proximate to the plurality of tanks. Hydraulic lines (e.g., hydraulic lines  806 (A) and  806 (B)) may be coupled with each of the hydraulic motors  804  disposed underneath each of the tanks and the one or more banks of manifolds and/or valves. For example, hydraulic lines from each of the individual hydraulic motors  804  may be communicatively coupled to a manifold mounted on the hydraulic power unit. A front portion of the one or more manifolds and/or valves may be communicatively coupled to the hydraulic power unit  802 . The front portion of the one or more manifolds and/or valves may be communicatively coupled with a main hydraulic pressure supply line and a main hydraulic pressure return line. A back portion of the one or more manifolds and/or valves may include one or more hydraulic servo valves. For example, the back portion of the one or more manifolds and/or valves may include the same quantity of hydraulic servo valves as the quantity of tanks. Any number of tanks could be communicatively coupled to the hydraulic power unit  802 . For example, one hydraulic power unit  802  may be utilized to operate about 20 tanks. A programmable logic controller (PLC) may be used to control the one or more manifolds and/or valves. For example, a PLC may be used to control one or more hydraulic servo valves. Further, the PLC may be used to control the hydraulic power unit  802 , a manway gate assembly (e.g., the manway gate assembly  104  coupled to the tank  102 ), a conveyor arranged with the manway gate assembly, a pump (e.g., a water pump), or other equipment arranged with the tanks. In one example, an operator may program the PLC to operate and engage a scraper blade assembly (e.g., scarper blade assembly  204  and/or scraper blade assembly  602 ). The programmed PLC may open the appropriate servo valve, allowing pressurized fluid to flow to the scraper blade assembly and turn the scraper blade assembly. In another example, an operator may manually operate the appropriate servo valve to engage a scraper blade assembly. Speed and torque of the scraper blade assembly may be controlled via the servo valves. A pump of the hydraulic power unit  802  may be a constant flow and pressure, or the pump of the hydraulic power unit  802  may be a more efficient variable pump. The direction of rotation of the scraper blade assembly may be controlled by the pump of the hydraulic power unit  802  and/or the one or more manifolds and/or valves. The size of the hydraulic power unit, pump, and/or hydraulic lines may vary depending on a quantity of the tanks, a size of each of the tanks, and/or the scraper blade assemblies. 
     CONCLUSION 
     Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the invention. For example, while embodiments are described having certain shapes, sizes, and configurations, these shapes, sizes, and configurations are merely illustrative.