Abstract:
A mobile heat dispersion system for preventing liquid conduits from freezing in cold environments, such as on frac pads, including a self-contained heating system formed of a forced air heater operatively connected to a fabric heat duct system and a heat entrapment cage enclosing both the liquid conduit to be protected and the fabric heat duct system, and a process for use thereof.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to an apparatus system for providing heat for conditioning outdoor systems which might otherwise freeze during cold environmental conditions, and processes for use thereof. More specifically, the present invention provides a means for preventing conduits, valves, manifolds, hoses and similar elements conveying aqueous-based liquids which could thicken and/or freeze in cold climates from becoming clogged with thickened and/or frozen liquid. The apparatus system of the present invention is portable, constructed of readily-available components and temporary in nature so that it can be quickly erected at the onset of cold temperatures and later quickly disassembled and stored during warmer weather for reuse the following fall and/or winter. 
         [0002]    The present invention is especially useful on frac pads which operate year round and are often erected in areas subject to cold and extremely cold temperatures during a significant part of the year. The fracing operation involves the use of water and water mixtures under pressure for fracturing underground formations for releasing entrapped oil and gas. Although the large tanks which hold water-based fluids tend not to freeze up due to their volumetric holding capacity, this is not the case for the conduits and associated valves and pumps which move the aqueous-based liquids around the frac pad. The frac piping is a few inches in diameter, not providing a sufficient volume of liquid for preventing freezing. The present invention is directed to solving this problem by providing a mobile heat dispersion apparatus and a process for providing the heat necessary for preventing the freezing of liquid within these small frac pad conduit elements. 
         [0003]    The prior art can be divided into two classes. First, there exist fabric air ducts usable to condition indoor spaces. The prior art in the fabric heat duct area is considered in the Detailed Description of the Invention section, hereinbelow, for exemplifying one component of the present invention. Second, there exist duct systems for preventing frost from forming on plants and for preventing the freezing of large ground areas such as sports fields. Concerning the latter, see GB 864,372 directed to a system for prevention of frost in orchards, or to protect sports grounds or dog or race tracks from frost. The GB &#39;372 system comprises a flexible tubular duct system connected to a heat source and having air outlets therein. The main ducts may be formed of a double skin to reduce heat loss there through. When used to protect sports grounds from frost, a covering such as a layer of paper or plastic may be laid over the duct work to maintain a blanket of warm air in contact with the ground. U.S. Pat. No. 3,727,345 is directed to a system usable for protecting plants from frost. The system comprises plastic film tubes having aperture walls and disposed between crop rows. In one modification, water-ballasted heat tubes support an overall covering sheet of thin plastic film. Air is vented by the covering sheet to maintain a desired positive pressure within the covering. 
       SUMMARY OF THE INVENTION 
       [0004]    An object of the present invention is to provide an apparatus system and process for preventing aqueous-based fluids from freezing within conduit systems conveying such fluids. 
         [0005]    Another object of the present invention is to provide an apparatus system and process for preventing aqueous-based fluids from freezing within conduit systems for conveying such fluids on frac pads. 
         [0006]    A further object of the present invention is to provide a two part apparatus system including fluid conduits carrying aqueous-based liquids subject to freezing during cold weather conditions and means for protecting the fluid conduits from clogging due to freezing of the carried aqueous-based liquids, and a process for use thereof. 
         [0007]    Still another object of the present invention is to provide a frac pad installation including one or more conduit systems for conveying aqueous-based liquids around the frac pad and a mobile heat dispersion apparatus for covering the conduit systems. 
         [0008]    Another object of the present invention is to provide a frac pad installation including one or more liquid conduit systems for carrying aqueous-based liquid(s) around the frac pad and a mobile heat dispersion apparatus for covering the conduit system(s) and providing heat for preventing the aqueous-based liquid(s) from freezing during cold environmental conditions. 
         [0009]    Still a further object of the present invention is to provide a mobile heat dispersion system which can be quickly erected for use during the advent of cold weather conditions and then quickly dismantled upon the approach of warmer weather conditions, and stored for reuse as cold weather again approaches. 
         [0010]    Still another object of the present invention is to provide a heat duct system usable outdoors and including means for entrapping heat within an enclosed environment, and a process for use thereof. 
         [0011]    Another object of the present invention is to provide a heat duct system usable outdoors plus means (1) for enclosing both the heat duct system and liquid conduits to be protected from freezing temperatures, and (2) for entrapping heat within the formed enclosure, and a process for use thereof. 
         [0012]    Thus, in accordance with the present invention, there is provided a mobile heat dispersion apparatus comprising a duct system for dispersing heat and a heat entrapment cage for entrapping the dispersed heat. More particularly, the present invention provides a mobile heat dispersion system comprising a self-contained fabric heat duct system positioned adjacent fluid conduits subject to freezing and a heat entrapment cage covering both of the self-contained fabric heat duct system and the fluid conduits as a single enclosed unit. In accordance with these embodiments of the invention, there are also provided processes for protecting a liquid within a conduit from cold temperatures by positioning the duct system adjacent the conduit and enclosing both the conduit and the duct system within the heat entrapment cage for trapping heat within the heat cage for protecting the liquid from cold temperatures. In these apparatus and process embodiments, a forced air heater is operatively connected to a self-contained fabric heat duct system also containing heat vent holes for releasing heated air to be contained within the heat entrapment cage for protecting the liquid within the conduit from cold temperatures. 
         [0013]    In specific embodiments, the present invention provides a frac pad installation including fluid conduits such as pipes, hoses, manifolds, valves and pumps, which need to be protected from freezing temperatures during the cold weather months, and a mobile heat dispersion system comprising (1) a self-contained fabric heat duct system positioned adjacent the fluid conduits and (2) a heat entrapment cage enclosing both of the fluid conduits to be protected and the self-contained fabric heat duct system. The fabric heat duct system is operatively connected to a forced air heater. 
         [0014]    In preferred embodiments of the present invention, the self-contained fabric heat duct system is formed of a material through which heat will disperse. In other preferred embodiments of the present invention, the self-contained fabric heat duct system contains vent holes through which heat will disperse. In still other preferred embodiments of the present invention, the self-contained fabric heat duct system both is formed of a material through which heat can disperse and also contains vent holes for releasing heat. 
         [0015]    In other preferred embodiments of the present invention, the heat entrapment cage is a three-sided covered metal frame enclosure as the fluid conduits and the self-contained fabric heat duct system are proximate to or rest upon the ground. In these embodiments, the three-sided heat entrapment cage sits on the ground enclosing both the fluid conduits to be protected and the fabric heat duct system. In these embodiments and where desired, the interior and/or exterior wall of the heat cage may be insulated for increased heat efficiency. Further, as related to these embodiments, if desired the heat entrapment cage can be four-sided so as to also enclose the underneath areas of the fluid conduits and of the fabric heat duct system, for example, where the fluid conduits are elevated off of the ground. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING 
         [0016]      FIGS. 1 through 8  illustrate the present invention, including various embodiments thereof. 
           [0017]      FIG. 1  depicts a typical frac pad installation. 
           [0018]      FIG. 2  depicts an expanded view of a typical frac pad installation including typical locations of heaters and heat dispersion systems in accordance with the prior art and the present invention. 
           [0019]      FIG. 3  illustrates a typical 70 foot run of fabric heat duct for use in the present invention and showing the components thereof. 
           [0020]      FIG. 4  is an expanded view of the framing for a heat entrapment cage of the present invention. 
           [0021]      FIG. 5  is a cross-sectional view of the heat dispersion system of the present invention, including both components of the fabric duct system and the heat entrapment cage. 
           [0022]      FIG. 6  depicts the standard fabric duct component parts used to form fabric heat duct runs described herein. 
           [0023]      FIGS. 7 and 8  respectively illustrate typical 30 and 170 foot runs of fabric heat duct, similar to  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    The present invention will be primarily described with respect to its employment on and in conjunction with a frac pad installation. Even so, the skilled artisan will appreciate and understand that the concept of the present invention is applicable to other environments where it is necessary and/or desirable to protect fluid handling conduit systems from freezing temperatures, such as liquid conveying conduits found on airport tarmacs or in conjunction with work over rigs and the like. Another area of use for the present invention is in agriculture for protection of ground level irrigations systems, such as in orange groves. 
         [0025]      FIG. 1  depicts a typical frac pad installation. A typical fracking pad consists of a well head, a data monitoring station, frac pumps, a frac blender, chemical storage tanks, sand storage units and a number of hydro tanks. The latter are usually arranged side-by-side, forming a rectangular configuration. A typical frac pad may contain about 4 hydro tanks, although more or less hydro tanks can be present based on the degree of activity of the fracking operation. See  FIG. 1  in which  81  represents a data monitoring van,  82  represents the frac pumps,  83  represents the wellhead,  84  represents the frac blender,  85  represents the chemical storage tanks,  86  represents the frac hydro tanks in a series and  87  represents sand storage units. 
         [0026]    In  FIG. 2 , the positioning of the heat dispersion system of the present invention is depicted by solid lines  2 ,  4 ,  6 ,  8 ,  10  and  12 . Each of these solid lines represents a fabric duct heat dispersion unit set within a heat entrapment cage, with the heat cage also enclosing a liquid conduit. Four heaters  14 ,  16 ,  18  and  20  are set at the beginning of 1 or 2 heat dispersion duct runs as depicted. These six systems of the present invention, employing four heaters, would take the place of 10 heaters of larger size than needed with the present invention for this typical frac pad, at a substantial savings in energy costs. These 10 heaters are shown as normally positioned in the prior art and are designated as elements  1 ,  3 ,  5 ,  7 ,  9 ,  11 ,  13 ,  15 ,  17  and  19 . “FW” is an abbreviation for “fresh water.” Heaters  10  and  18  supply heat for two runs of fabric heat duct. A suitable connecting device, as known in the art, is used for operatively connecting a single heater to the inlets of two duct runs. 
         [0027]    The fabric duct system which forms part of the present invention is known in the prior art and is taught for use within enclosed rooms such as warehouses and the like. See U.S. Pat. No. 5,655,963; U.S. Pat. No. 5,769,708; U.S. Pat. No. 6,280,320; U.S. Pat. No. 6.425,417 and U.S. 6,558,250 regarding descriptions of fabric heat duct components and uses thereof. These fabric heat duct systems are sold under the SimpleSox™ and Duct Sox™ tradenames and marks. The SimpleSox™ fabric heat duct system, usable in the practice of the present invention, is an adjustable fabric air dispersion system assembled with pre-made components. The system is versatile in that both the volume and direction of air, as well as the location where air will be dispersed, can be adjusted during set-up. The SimpleSox™ system consists of 8 standard parts available in 5 diameters (12, 16, 20, 24 and 28 inches) to deliver up to 6000 CFM per run. The SimpleSox™ system is configurable up to 14 airflow volumes and a total of 63 combinations considering orifice size, orientation and the number of orifices activated. The eight standard elements of the fabric duct system used to exemplify the present invention are depicted in  FIG. 6  of the present invention in which  60  represents a one foot inlet which is operatively connected to the heater outlet,  62  represents a fabric mesh damper adjustable flow device,  64  represents a fifteen foot section,  66  represents a two foot adjustable air outlet,  68  represents a five foot section,  69  represents a 1.5 foot section,  72  represents a 90 degree elbow and  74  represents a 0.5 foot endcap. 
         [0028]    The adjustable air outlet provides a mechanism for changing both the direction of and volume of the air flow. Air flow volume can range up to 920 CFM per adjustable air flow outlet. Submitted herewith as part of an Information Disclosure Statement is a SimpleSox™ product brochure available from DuctSox™ of Dubuque Iowa, a subsidiary of Rite-Hite Holding Corporation, explaining how to calculate the number and setting of the adjustable air outlets for typical installations having 0.5″ w.g. inlet static pressure. Two additional brochures are included with the Information Disclosure Statement which discuss pressure within the fabric duct system and the employment of the adjustable flow device. 
         [0029]      FIGS. 3 ,  7  and  8  illustrate typical 70, 30 and 170 foot runs of fabric heat duct for use on a frac pad in accordance with the present invention, and showing the components thereof. The element numbering of  FIG. 6  is used to show like components or elements in the fabric duct runs of  FIGS. 3 ,  7  and  8 . In these depicted systems, the duct diameter is 20 inches and the heater used is the Allmand Maxi Heat heater available from Allmand Brothers of Holdrege, Nebr. and which has an outlet which can be mated to the 20 inch diameter fabric duct system. Other heaters are usable in the practice of the present invention as long as the selected heater has an outlet which can be mated with the inlet of the selected fabric duct system. Normal sheet metal enclosures may be needed with a selected heater. With respect to the Allmand Maxi Heat MH-1000 heater, the heater output for each heater unit is up to 2850 CFM and BTU output for each heater unit is 500,000 BTU/hr. This heater contains twin heater units which may be operated independently, each heater unit being rated at the CFM and BTU values above noted. With this heater and the exemplified 30, 70 and 170 foot fabric duct runs, the inlet static pressure is 0.5″ w.g. 
         [0030]    In the 30 foot and 170 foot runs, one adjustable flow device (fabric mesh damper) is used and is positioned at about the center point of the run, to aid in controlling pressure in the run. The adjustable flow device is set at the half to open position in each of these two illustrated fabric duct runs. The adjustable flow device can be set at fully open, ½ open or fully closed positions, or something in between these settings, where desired. Routine experimentation determines the placement and adjustment for the adjustable flow device. 
         [0031]    A number of adjustable air outlets are positioned as shown in each of the three illustrated fabric duct runs. These adjustable air outlets contain four orifices which can be used to disperse heated air, which is also dispersed to a lesser degree through the air permeable fabric of the fabric heat duct system. In the exemplified runs, the adjustable air outlets are configured with the four orifices facing upward. Adjustable sleeves are provided with the adjustable air outlets which can be used where desired to reduce air flow by blocking 1 or more of the 4 orifices and/or reducing the diameter size of the orifices contained in the adjustable air outlets. The sleeves, when used, slide over and rotate around the adjustable air outlet. Thus, in addition to heated air being dispersed through porosity of the fabric of the fabric duct system, additional heat can be released at about evenly spaced positions along the duct run through use of the adjustable air outlets. Of course, the adjustable air outlets, which release a significantly greater amount of heated air than the volume of air released through the porosity of the fabric itself, can be placed at various positions, within a balanced system, if more heat is needed at one location than another location. Preferably, the adjustable air outlets are fairly evenly spaced along the fabric run as shown in the exemplified 30, 70 and 170 foot runs. In these exemplified runs substantially all of the adjustable air outlets are in the fully open position. On-site manual adjustment can be made using the adjustable sleeves for reducing air release if needed at a given location. In the system of the present invention, the adjustable sleeves are used sparingly, only for making a manual adjustment of decrease in air flow at a given point during on-site installation of the system of the invention including the heat entrapment cage. 
         [0032]    The “fabric” of the fabric heat duct component of the invention can be any pliable sheet material that is air permeable to some degree and examples thereof are woven or knit cloth, fiber reinforced plastic, non-woven air permeable flexible plastic sheeting and so forth, as known in the art. In some cases, the constructing engineer could decide to use non-air permeable fabric and rely only on the adjustable air outlets for release of the heated air. A non-air permeable plastic sheeting or plastic impregnated cloth could be employed as the fabric in such an instance. In the exemplified embodiments, the standard air permeable fabric duct components available as the above-described SimpleSox™ system are employed. 
         [0033]    In  FIG. 5 , as shown in cross-section, element  53  is an air impermeable, substantially non-porous plastic sheeting enclosing the heat entrapment cage, while element  51  is the fabric heat dispersion unit and element  52  represents a fluid conduit to be protected from freezing temperature conditions. 
         [0034]    In  FIG. 4 , showing an expanded view of the frame for a heat entrapment cage  50 , the heat entrapment cage is formed of skeletal extruded aluminum elements  40  connected to one another by connectors  42  to form rectangular frames to be enclosed for forming the entrapment heat cage. As noted above, the heat cage can be insulated. In the exemplified embodiment, the extruded aluminum framing is covered by air impermeable nylon sheeting on all sides. Other materials such as canvas or other types of non-porous plastic sheeting including impregnated plastic sheeting could be used as a covering for the heat entrapment cage. Another cover possibility instead of sheet material is plexiglass. The dimensions of a typical heat entrapment cage for use on a frac pad are about 5 feet wide at its base adjacent the ground, about 40 inches high and about 3 feet across at its top, forming a trapezoidal shape in cross-section. The size, shape and configuration of the heat entrapment cage can be adjusted based on the fluid conduit to be encased. For example, if a larger manifold is to be encased, the heat entrapment cage can be suitably enlarged and even reduced from the above typical dimensions when a small diameter run of piping is to be enclosed. 
         [0035]    Variations of the invention will be apparent to the skilled artisan.