Abstract:
A fluid injector system for use in tank cleaning is provided, the injector system including an injector head block housing two disc-shaped injectors which may be rotated inside of the injector head block to change the orientation of bores extending through the disc-shaped injectors, which discharge pressurized fluid therethrough. The injector head block depends downwardly from a housing, and is rotatable relative to the housing by rotating a drive tube assembly housed partially within the housing and connected to the injector head block. The disc-shaped injectors are rotated by a vertical movement of the injector head block by virtue of a linkage assembly linking the injectors to a portion of the structure that is vertically stationary when the injector head block is moved vertically.

Description:
This application is directed to an invention that has been described and depicted in U.S. Provisional Application Ser. No. 60/112,946, filed Dec. 18, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a fluid injector system for use in cleaning industrial tanks. 
     Material handling units, such as holding tanks or the like, are used in a wide range of industries, such as the pulp and paper industries, chemical industries, mining and refining industries, and the steel industry. One problem that exists in connection with the use of such holding tanks is that, over time, the liquid in the holding tank can no longer hold the solids suspended therein in solution, and the solids fall out, or are precipitated, and load the bottom of the tank. The settled solids reduce tank capacity, can clog pumps, and, in some instances, lock in valuable capital costs of material. 
     In order to avoid excessive solids buildup, such industrial tanks must periodically be cleaned. Various tank cleaning methods and devices have heretofore been proposed for use. One such apparatus is disclosed in U.S. Pat. No. 5,253,812. Other techniques have also been used. 
     Pressure washing of industrial tanks to remove settled sludge from the bottom of the tank has been performed in the past. However, known pressure washing systems have required that the tank be taken offline, or out of service, and drained, in order to expose the sludge for spraying and removal by pressurized fluid. This results in expensive downtime for the tank, presents the problem of where to temporarily store the liquid in the tank (if it has economic value), and presents other scheduling and logistics problems. 
     The problem to be solved is thus to provide a tank cleaning system that can be used to clean sludge out of the tank without the need to take the tank out of service and/or drain the existing liquid from the tank. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an injector system capable of injecting pressurized fluid into a sludge layer settled in a tank, to break up the sludge into pieces small enough to be pumped out of the tank by a slurry pump or to be removed by other removal equipment. The injector system is capable of being used even when liquid is present in the tank above the surface of the sludge 
     The injector system includes a housing having an injector head disposed at a lower side thereof, and the housing has a fluid feed tube extending therethrough which supplies a fluid to the injector head from a fluid supply source. The injector head is capable of being rotated through 360° in a horizontal plane, and has two injectors retained therein which can each be rotated through approximately 90°, from pointing in a substantially horizontal orientation, wherein the injectors oppose each other, to pointing in a substantially vertical downward orientation. 
     The housing of the injector system houses a hydraulic system or subsystem including a hydraulic motor and hydraulic cylinder, that powers the rotation of the injector head and the injectors through various mechanical couplings. The housing may be in either a “stand up” (vertical orientation) or a “lay down” (horizontal orientation) configuration. The injector system is preferably positioned and maneuvered around in the tank by a wire based guidance system of the type disclosed in U.S. Pat. No. 5,526,989. 
     The injector system is designed to deliver pressurized liquid through the nozzles directed at the sludge layer, to break up the sludge into pieces of a size such that the sludge can be removed by a separate slurry pump or other removal equipment. The pressurized liquid may be water or the liquid present in the tank above the settled sludge, or a combination of the two. Alternatively, a liquid which is soluble with the contents of the tank, may be employed. As an illustrative example, diesel fuel may be used in cleaning an oil tank. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of the present invention and the attendant advantages will be readily apparent to those having ordinary skill in the art and the invention will be more easily understood from the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings wherein like reference characters represent like parts throughout the several views. 
     FIG. 1 is a cutaway view of a tank illustrating the injector system of the present invention in substantially schematic form. 
     FIG. 2 is a cross-sectional view of a preferred embodiment of the injector system of the present invention. 
     FIG. 3 is a side elevation view of the injector head of the injector system illustrated in FIG.  1 . 
     FIG. 4 is a front elevation view of one-half of the injector head. 
     FIG. 5 is a front elevation view of an injector according to a preferred embodiment of the present invention. 
     FIG. 6 is a side elevation view of an injector according to a preferred embodiment of the present invention. 
     FIG. 7 is a cross-sectional view of an alternative preferred embodiment of the injector system of the present invention. 
     FIG. 8 is a front elevation view of an alternative preferred embodiment of an injector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to FIG. 1, a tank  100  is illustrated in a cutaway, or a substantially schematic cross-section. A layer of settled solids or sludge  102  is shown in the bottom of the tank, and, as is typical, the liquid  104  stored in the tank occupies the space above the sludge. The injector system  10  of the present invention is illustrated in schematic form as being suspended from the roof  106  of the tank  100  by a guidance system  108  using wire, cable or chain, or other suitable material. 
     The guidance system, termed a positive guidance system  108 , is fully disclosed in U.S. Pat. No. 5,526,989, the disclosure of which is hereby expressly incorporated by reference. The injector can be moved around in the tank  100 , and may be maintained at the desired level, namely riding on the top of the layer of sludge or hovering in close proximity to the top of the sludge, by the positive guidance system. The positive guidance system has the advantage of not requiring a worker to be inside the tank while the tank is being cleaned, and the positive guidance system can be installed without the necessity of emptying the liquid out of the tank. As also noted in the referenced patent, the guidance system also provides the ability to connect the cleaning device, here, the injector system, to the guidance system outside of the tank, and to lower the cleaning device into the tank through a manway or other opening in the roof, to the desired position and height. 
     The injector system  10  has a sling strap  12  secured at an upper portion of the system housing  14 , with the sling strap  12  connecting to fasteners  110  on the cables of the positive guidance system. The sling strap operates in conjunction with the cables to retain the injector system in a substantially upright or vertical orientation, to the extent practicable. 
     Turning now to FIG. 2, the injector system according to a preferred embodiment is shown in greater detail in the cross-sectional view of that drawing figure. The housing  14  of the injector system may preferably be a length of 12 inch diameter pipe, or a fabricated steel box, or similar housing structure. The housing has a top plate  16  and a bottom plate  18  closing off the upper and lower ends of the housing. 
     A fluid feed tube  20 , which may preferably be a small diameter pipe capable of withstanding high pressure, extends through an opening  22  in the center of the housing. The fluid feed tube has a fluid tight seal  24 , which seals off the interior of the housing from the external environment. 
     The fluid feed tube is not rigidly fixed to the housing, but rather may be rotated about the longitudinal axis of the tube and may be moved upwardly and downwardly relative to the housing, along its axial direction. A top bearing  26  disposed in the opening under the seal is secured to the top plate  16  of the housing to facilitate such relative movement. 
     Bottom plate  18  is affixed at or near the lower extent of the housing  14 , and may preferably be welded in place. Where desired to increase the stability of the housing in an upright position, space is provided underneath bottom plate  18  in the housing for placement of additional weight plates  28 , which may be retained in place by bolts  30  threaded into tapped bores in the bottom plate. 
     A lower bearing assembly  32  is secured to bottom plate  18  at a central opening in the bottom plate. The additional weight plates  28  have an opening sized to closely surround the outer surface of bearing  32 . Fluid feed tube  20  protrudes downwardly through the inner opening in the bearing  32 , and is threaded onto injector head block  202  of injector head assembly  200 , the details of which will be discussed later in this specification. 
     Surrounding the fluid feed tube  20  at the region where the tube exits the housing  14 , is a rotary drive tube  34  that forms a fluid-tight seal with the bearing  32  through O-rings  36 , and forms a fluid-tight seal against the outer surface of fluid feed tube  20  through the use of O-rings  38 . Rotary drive tube  34  is secured inside housing  14  to a ring gear drive plate  40 , which has a ring gear  42  fastened thereto by bolts  44 . A hydraulic motor  46 , shown outside housing  14  for the sake of clarity, is mounted to an interior wall of housing  14  by way of mounting bracket  47  in the final assembled unit, and has a drive gear  48  which engages and drives ring gear  42  as desired. 
     Housing  14  also contains one or more (two shown) two-way hydraulic cylinders  50 , which are preferably secured to the inner surface  52  of top plate  16 . The cylinders are linked to the outwardly extending ears  54  of a trunnion assembly  56  by pins  58 . The trunnion assembly has a bearing assembly  60  at its inner extent, to facilitate relative rotational movement of the fluid feed tube  20 . The trunnion assembly is retained in a fixed axial position relative to the fluid feed tube  20  by upper and lower stop collars  62 ,  64 , respectively. As will be discussed in more detail in the discussion of the operation of the injector head and injectors, the piston arms  66  of the hydraulic cylinders may be made to travel upwardly and downwardly through a predetermined range of travel, thereby raising and lowering fluid feed tube  20  along its axial direction. 
     Housing  14  further has an oil plug  68  threaded into an opening in the side wall of the housing at a position above the gearing, as it is preferred that the lower portion of the housing be filled with oil to lubricate at least the lower internal parts contained in the housing. Housing  14  is further shown as having a hydraulic line  70  extending through the upper plate  16 , and connected to the hydraulic motor and hydraulic cylinders. Hydraulic power for operating the motor and hydraulic cylinders is provided by a hydraulic power system (not shown) that is preferably to be disposed outside the tank. FIG. 1 shows the hydraulic line entering the tank, and extending down to the injector system  10 . 
     The injector head assembly  200  of injector system  10  according to a preferred embodiment of the present invention is illustrated in FIGS. 2-6. Injector head block  202  is preferably formed of two half-blocks  204 ,  206  that are bolted together in the final assembly. The injector head block  202  houses one or more (two shown) injectors  208 , preferably made of thick (approximately 1-2½ inch) steel discs, as best seen in FIGS. 5 and 6. The injectors preferably each have a tapered, essentially frustoconical, bore  210  extending through the center thereof, having an orientation defined by a central axis about which the bore is symmetrical, with the central axis preferably extending along a diameter of the disc. 
     While a tapered bore appears to be preferred for most expected uses, an alternative preferred embodiment, as shown in FIG. 8, employs a substantially cylindrical bore  410  which is tapped (i.e., provided with female threading) at one end of the bore. The injector  408  in this embodiment will receive an injector tip  412  having male threads for threadingly engaging the tapped end of bore  410 . Injector tips  412  of varying sizes, shapes, or degrees of internal taper may thus be provided with the unit. The tips may be changed as necessary to have specific tip configurations used for specific types of cleaning jobs. 
     Referring to FIG. 4 especially, the manner in which the injectors are retained in the injector head block  202  will be discussed. Each of the half-blocks  204 ,  206  are preferably machined, or possibly cast, having mating surfaces  212  at the upper corners and along a portion of the lower edge of the half-blocks. A threaded connection region  214  is formed between the upper corner mating surfaces, although this may preferably be formed by tapping a rough-cut opening after the two half-blocks are assembled into the block. Openings  216  are machined to the same diameter as the diameter of injector discs  208 . 
     The portion of the half-block that does not form part of the mating surfaces  212  nor the threaded connection region  214 , and that is not fully removed in creating openings  216 , is machined down to approximately one-half of the original block thickness, or by a somewhat greater amount (see, e.g., FIG.  3 ). O-ring grooves  218 ,  220  are formed in the half-blocks as well, in order to provide a fluid-tight seal between the injector discs  208  and the injector head block  202 . The O-ring grooves may alternatively be placed in the injector disc  208 . It can be seen in FIG. 4 especially that the area  222  in head block  202  will receive the pressurized fluid from fluid feed tube  20 , and distribute the fluid to the two injectors  208 . 
     The injector head block is assembled by placing O-rings  224 ,  226 , or other suitable seals, in grooves  218 ,  220 , in each half-block, positioning the injectors  208  in alignment with their respective openings on each half-block, and then bolting together the two half-blocks to form the injector head block  202 . The assembled head block  202  is threaded onto the lower threaded end  72  of the fluid feed tube  20 . Final connections of the injector head block  202  to the injector assembly  10  are made by securing pivotable link arms  74  to the injectors  208  and to anchors  76  extending downwardly from a drive plate  78 , which itself is threaded onto the lower end of rotary drive tube  34 . 
     Thus, as the ring gear drive plate  40  is rotatingly driven by the hydraulic motor  46  and ring gear  42 , rotary drive tube and drive plate  34  and  78 , respectively, rotate the entire injector head through a full 360° sweep in a horizontal plane. It should be noted that, as used herein, the term “horizontal” is used as shorthand to describe the orientation of the injector head and drive plate, or an orientation perpendicular to the axis of rotation. If the injector system is tilted in operation, the rotation will obviously not be in a true horizontal plane, but will be in a plane described herein as horizontal. Drive plate  78  is preferably provided with a left-hand thread for its connection to drive tube  34 , whereas vertical fluid shaft  20  is provided with a right-hand thread. This results in a self-tightening connection once all components are assembled, and the connection prevents either threaded unit from coming loose. 
     This rotation of the injector head in turn causes fluid feed tube to rotate within the housing  14 , and accordingly, along its entire extent. A rotary swivel connector, shown schematically by reference numeral  80  in FIG. 2, may preferably be provided at an upper extent of fluid feed tube  20 , to connect the fluid feed tube to a fluid feed line  112  (FIG.  1 ), such that the rotary movement is taken up in the connector. 
     It is presently contemplated that the injector system will be controlled such that the hydraulic motor runs constantly while the unit is in operation, such that the horizontal rotation of the injector head  200  is constant. The orientation of the injector bores may, in addition, be adjusted through preferably nearly 90°, or from pointing essentially along an axis parallel to the fluid feed tube  20 , to pointing along an axis substantially perpendicular to the axis of the fluid feed tube. This is accomplished by the construction and linkages discussed above with respect to, especially, FIGS. 2 and 3. 
     When it is desired to adjust the orientation of the injector bores, the hydraulic cylinders  50  are adjusted to extend or retract the piston arms  66 , as appropriate, which in turn moves trunnion assembly  56  and fluid feed tube  20  upwardly (pistons retracting) or downwardly (pistons extending) relative to housing  14 . Fluid feed tube accordingly moves within the drive tube  34  and pulls (when moving upwardly) or pushes (when moving downwardly) on injector head block  202 . This causes the block to move in response to the force, and causes injectors to rotate about their pivotable linkages, thereby changing the orientation of the bores  210  extending through the injectors. 
     In the alternative preferred embodiment illustrated in FIG. 7, the injector head assembly (not shown in FIG. 7, numeral  200  in FIG. 2) is preferably identical to that shown in FIGS. 2-6. In the FIG. 7 embodiment, housing  300  is of a flatter, more horizontal, configuration. This embodiment may perform better is some circumstances that the previously discussed embodiment, such as, for example, where the consistency of the sludge to be broken up makes it difficult to maintain the more vertically oriented embodiment of FIG. 2 in its upright orientation. 
     Housing  300  is preferably of a short inverted frustoconical or inverted truncated square pyramid shape, having a side wall  302  and a top and bottom plate  304 ,  306 , respectively. Fluid feed tube  308  extends through the housing, as in the previous embodiment, having a fluid-tight engagement with top bearing assembly  310 , which facilitates both rotational and axial movement relative to the housing. Fluid feed tube  308  extends outwardly through the lower end of the housing though the interior of rotary drive tube  312 . A lower bearing assembly  314  surrounds the rotary drive tube  312  and is secured to a section of plate  316  that is connected in fluid-tight engagement to the bottom plate  306  of the housing. 
     The desired rotary motion of the injector head ( 200 , FIG. 2) secured to the lower end of fluid feed tube  308  is accomplished by a hydraulic motor  318  mounted horizontally within housing  300  by a motor mount bracket  320  secured to the housing  300 . The hydraulic motor drives a beveled drive gear  324  of a bevel gear pair  322 , and driven gear  326  of the gear pair is secured to the upper end of rotary drive tube  312 . Thus, the motor drives the gear pair, which converts the horizontal rotary motion to vertical rotary motion, and the gear pair drives the rotary drive tube, which, as in the previous embodiment, is coupled to the lower drive plate which is linked to the injector head (see FIG.  2 ). 
     The adjustment of the injectors to orient the injector bores as desired is accomplished in the FIG. 7 embodiment by a linkage assembly that includes a horizontally oriented two-way hydraulic cylinder  330  pivotably anchored to a cylinder brace  332 , which itself is secured to an inner wall of the housing  300 . The piston arm  334  of the cylinder is pivotably connected to an L-shaped arm  336 , which itself is pivotably secured to a lever bracket  338  connected to and extending upwardly from the bottom plate of the housing. 
     At a distal, or far, end of the L-shaped arm  336 , the arm is retained between upper and lower stop collars  340 ,  342 , respectively, with the collars being secured to the fluid supply tube. The L-shaped arm  336  is either forked at its distal end to straddle the fluid supply tube, while still permitting rotation thereof, or a cam follower bracket may be employed. Details of this arrangement are not illustrated, as such connections are well understood in the art. 
     The fluid supply tube is thus raised or lowered, to bring about the desired reorientation of the injector bores, by controlling the hydraulic cylinder to retract or extend the piston arm, which in turn forces the L-shaped arm pivoting about the pinned connection at lever bracket  338 , to either raise or lower the fluid supply tube. Because the injector head and its connection to the fluid supply tube and drive plate are to be identical to that shown in FIG. 2, the action of raising and lowering the fluid supply tube relative to the housing will operate in the same manner to reorient the injector bores. 
     Thus, by positioning the hydraulic motor and the hydraulic cylinder in a horizontal orientation, the housing  300  can be made to have a shorter profile, which, as noted above, can provide improved operation in certain tank cleaning environments. 
     By providing a liquid-tight housing containing all parts that might be sensitive to the external environment, the injector assembly of the present invention can be used in a submerged or semi-submerged position relative to liquid contained in a tank to be cleaned. Further, by providing a fluid injector arrangement that has injectors introducing pressurized cleaning fluid though a continuous 360° sweep, and at an orientation relative to the surface of the sludge selected and adjusted to be optimized for the specific conditions found in the tank, a highly efficient approach to breaking up sludge and achieving the optimum fluidization of the material to be cleaned from the tanks is obtained. 
     The injector assembly may operate to inject liquid at pressures typically in the range of 400-500 psi, at fluid flow rates of about 300-600 gallons per minute. The injector assembly should further be suitable for use at much higher pressures, such as 20,000 psi, if the particular cleaning operation requires the use of higher pressures. 
     The fluid supply may be an external source of water supplied at 600 psi through fluid supply line  112 , which may be a 2″ hose pressure rated at 800 psi. While this reflects the current pressure levels employed, the fluid injector is expected to be capable of handling operating pressures of 20,000 psi and higher, and the hose used for such applications may preferably be rated at 32,000 psi. The fluid may be pressurized by using a pumping unit equipped with a diesel engine located outside the tank, preferably at the base of the tank. The pump may be set up to use only water, or to use fluid retrieved from, and recirculated to, the tank, or a combination of the two fluids. This is generally determined by the needs of the tank operator, in terms of, for example, the need for higher or lower solids content in the slurry formed by the injector system. 
     The slurry produced from the sludge and other material broken up by the injector system is generally removed from the tank by a separate system, such as a hydraulically driven slurry pump. 
     It is also possible to employ more than two injectors on the injector assembly, if desired, although, with the 360° rotation, the additional cost and complexity may not be warranted. Three, four or even more injectors may be disposed in the injector head assembly, preferably being oriented at evenly spaced increments around said injector head. It is further possible to provide two or more injector head assemblies depending downwardly from the housing of the injector system. 
     It is to be recognized that the foregoing preferred embodiments are depicted and described for illustrative purposes, and the invention is not to be limited only to such embodiments. Various modifications and changes may become apparent to those of ordinary skill in the art upon studying this disclosure, and such modifications and changes do not depart from the spirit and scope of the invention. Accordingly, the scope of the invention herein is to be determined by reference to the appended claims.