Patent Publication Number: US-6220830-B1

Title: High efficiency blower and solar-powered soil remediation system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Provisional Patent Application Ser. No. 60/118,596 filed Feb. 4, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     Soils contaminated by, for example, hydrocarbons can often be remediated, that is cleaned, by forcing air (and thus oxygen) through wells into the contaminated underground regions. This injection may be in conjunction with the introduction of other gases, liquids or micro-organisms. 
     Soil remediation systems may also use forced air venting, also called soil vapor extraction (SVE). With this technique gas within the unsaturated contaminated soil matrix is extracted using vacuum applied at one or more extraction wells. Pressure gradients within the unsaturated zone induce a convection air flow through the porous soil matrix. The extent of the vacuum influence is determined by the soil properties. As the contaminated soil gas is removed, clean air from the surface is drawn into the contaminated zone; thus organic compounds to be volatilized, depending upon their vapor pressures. 
     Current SVE methods use gasoline, electric or hydraulically-driven positive displacement blower systems to pull the air and volatilized compounds from the wells. The typical blower system consists of a positive-displacement blower driven by a drive motor, a vacuum breaker, pressure relief valve, temperature switches, pressure and temperature gauges, intake filters and exhaust silencers. These SVE systems are typically mounted on skids since they are very heavy and they will only be left in place for a short period of time. There are several problems with conventional SVE systems. The blowers are noisy, and they are notorious for their inefficiency. Conventional SVE systems are expensive to purchase, to operate and to maintain. At the end of the clean-up procedure, SVE&#39;s must be disposed of. Vapor exhausted from the blower is above about 180° Fahrenheit, posing a safety concern. Conventional SVE systems require large diameter piping between the blower skid and the wells. This above ground piping creates obstacles as well as being unsightly. Below grade piping is expensive and may require cutting through concrete slabs. A conventional SVE system often requires use of a crane to set up the system and typically entails a complicated startup procedure. Because of their many problems and drawbacks, potential users often decide against installing skid mounted SVE systems. 
     Conventional air injection systems suffer from many of the same drawbacks as conventional SVE systems. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a high efficiency blower finding particular utility for use with a solar-powered soil remediation system, as well as other end uses. The high efficiency is created by mounting a motor fan assembly within a venturi surface and by the use of flow-straightening supports aligned along the flow axis through the body of the blower. 
     The blower includes a body having an inner venturi surface aligned with a flow axis through the body. The venturi surface has first and second ends and a throat between the two ends. A motor/fan assembly is mounted within the body by at least one flow-straightening support. The motor/fan assembly includes a motor and a fan blade assembly mounted to a shaft extending from the motor. The fan blade assembly has at least one fan blade. The support extends between the motor/fan assembly and the body. The fan blade is preferably located generally at the throat of the venturi surface. The flow-straightening support has leading and trailing edges and first and second lateral sides extending between the edges. The lateral sides are oriented generally parallel with the flow axis. 
     Another aspect of the invention relates to the high efficiency blower being powered by a solar panel through an electric storage and control assembly. This permits operations, such as soil remediation, to be conducted using a relatively simple, inexpensive, self-contained system which requires no external source of power and very little upkeep. In one embodiment the high-efficiency blower is capable of moving at least 170 cfm of air at about 2000 fpm using no more than about 7.5 watts of power. 
     One of the primary advantages of the invention is that it can be quite inexpensive to purchase and use. For example, assume six wells will be needed at a site. The total cost for purchasing, operating and maintaining six soil remediation systems, one for each of the six wells, made according invention is estimated to be about $20,000.00 over two years of operation. This can be compared with a total cost of about $240,000.00 to operate a single conventional SVE system connected to the six wells and operated for two years. This cost saving is largely because with a soil remediation system made according to the invention, a major cost will be the soil remediation system itself and the cost for the six wells. There are very few other costs involved. The simplicity of the soil remediation system made according to the invention can eliminate the need for regular maintenance; it can be installed by a single operator at an existing well in a relatively short period of time. Using solar power instead conventionally generated electricity not only eliminates the cost of the electricity itself but also pollution created in generating and transmitting the electricity. By using a separate soil remediation system for each well, the need for pipes from several wells to a single system is eliminated resulting in substantial cost savings. 
     The housing for a solar-power blower system can be fabricated from a structural frame covered with UV protected ABS plastic. The ABS plastic is economical and dent resistant. Other materials, such as anodized aluminum sheet, can also be used. The structural frame can be made from square steel tubing; other materials, such as aluminum or stainless steel in the same or other shapes could also be used meet various site requirements. The housing may be designed to hold a solar panel at an appropriate angle, which may be fixed or adjustable. The housing preferably acts as a container for the electronics and the blower. 
     The solar panel and electricity storage and control assembly may be conventional components using a deep charge/deep discharge battery. It is preferred that the system be designed such that the blower is supplied with uninterrupted power for night and overcast day operation. During normal daylight operation the system is preferably designed to not only operate the blower, but also trickle charge a backup battery for night time operation to offer the operator extended use performance. 
     The blower can be connected to more than one well. However, the relatively low cost of the invention makes it most suited for using a system for each well; this eliminates the need for long lengths of above ground or below ground piping from the various wells to the system, together with the cost associated with such piping. 
     Other features and advantages of the invention will appear from the following description in which the preferred embodiment has been set forth in detail in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an overall view of a solar-powered soil remediation system with a side panel removed; 
     FIG. 2 shows the system of FIG. 1 with portions broken away to illustrate the interior; 
     FIG. 3 is an enlarged side cross-sectional view of the blower of FIG. 1; 
     FIG. 4 is an end view of the blower of FIG. 3 with the motor/fan assembly removed; and 
     FIG. 5 an electrical schematic diagram of the system of FIG.  1 . 
    
    
     DESCRIPTION OF THE SPECIFIC EMBODIMENTS 
     FIG. 1 illustrates a solar-powered soil remediation system  2  made according to the invention. System  2  includes a housing  4 , a front panel of the housing being omitted in FIG. 1 to illustrate some of the components of system  2 . Housing  4  includes a tubular frame  6  made of square steel tubes welded together to form the frame. Sheets or panels of UV-protected ABS plastic material  8  are used to cover frame  6 . Housing  4  can be made of other materials and in other ways, such as using an all metal construction, all plastic construction with an integral framework. Materials other than steel for tubular frame  6 , such as stainless steel or aluminum, could also be used. Housing  4  typically has an open bottom  10  to permit housing  4  to be mounted over an upstanding pipe  9  extending from a remediation well  11 , pipe  9  and well  11  shown in FIG. 2 only. System  2  is connected to the upstanding pipe of the well by a clamp  12  mounted to one end of a blower  14 , the other end of the blower coupled to the ambient atmosphere through a conduit  16  by a second clamp  17 . Housing  4  also includes a pair of ambient air vents  19  near the peak of the housing. 
     A key component of system  2  is blower  14 , shown in more detail in FIGS. 3 and 4. Blower  14  includes a generally cylindrical body  18  defining a cylindrical outer surface  20  and a tapered, inner venturi surface  22 . Venturi surface  22  extends from a first end  24  to a second end  26 , the venturi surface tapering radially inwardly from the ends towards a throat  28  at first and second angles  30 ,  32  respectively. In a preferred embodiment body  18  is about 8 inches (20 cm) long and about 4 inches (10 cm) in diameter with a wall thickness at each end  24 ,  26  of about 0.060 inch (1.5 mm). Also, in a preferred embodiment angles  30  and  32  are about 8° and 3°, respectively. Other sizes and proportions may also be use. 
     Blower  14  also includes a motor/fan assembly  36  mounted centrally within the interior of blower  14  along a flow axis  38  by three evenly spaced apart, flow-straightening supports  40  extending upwardly from a mounting plate  44 . Assembly  36  also includes a motor  42  mounted to mounting plate  44  at one end and a fan blade assembly  46  mounted to a motor drive shaft  48 , extending from motor  42 . Shaft  48  and assembly  46  are aligned with and centered on flow axis  38 . Each flow straightening support  40  includes a leading edge  50 , a trailing edge  52 , both oriented at angles to flow axis  38 , an inner edge  54  and an outer edge  56 , both generally parallel to flow axis  38 . In a preferred embodiment mounting plate  44  and supports  40  are made of 6061 aluminum plate ⅛ inch (3.2 mm) thick while body  18  is also made of 6061 aluminum. Motor  42  is bolted to plate  44  with shaft  48  passing through a hole  58  formed in plate  44  as shown in FIG.  4 . Plate  44  is secured to supports  40  at tips  60 , typically by welding, while supports  40  along outer edges  56  are housed with an appropriately sized and positioned slots formed in body  18  and are welded to the body. 
     Motor/fan assembly  36  can be assembled from conventional components chosen for their high efficiency. For example, motor  42  can be one made by Portescap U.S. Inc. of Hauppauge, N.Y. Fan blade assembly  46  can be one purchased from Advanced Air Mid-America of Murfreesboro, Tenn. As can be seen in FIG. 3, the profile of motor  42  is such that it is relatively long and narrow and thus creates a very small obstruction to the flow of air or other fluids parallel to flow axis  38 . In the preferred embodiment leading edge  50  forms an included angle with outer edge  56  of about 122° while trailing edge  52  forms an included angle with outer edge  56  of about 23°. In appropriate cases these may be changed so that, for example, leading and outer edges  50 ,  56  are at a right angle to one another. 
     Supports  60  provide both support for assembly  36  and also help to straighten out the otherwise turbulent flow created by the moving blades  62  of the fan blade assembly  46 . While this straightening is most pronounced and most effective when the air moves from the left to the right in FIG. 3, that is entering at first end  24  and exiting at second end  26 , flow-straightening supports  40  also provide a certain amount of flow-straightening and increased efficiency when motor  42  is reversed to cause air to flow from second end  26  through first end  24 . Supports  40  are preferably quite thin, ⅛ inch (3.2 mm) thick in the preferred embodiment. Flow-straightening supports  40  also have relatively large lateral sides  64 , which extend between leading and trailing edges  50 ,  52 . Outer edge  56  will preferably be about one third (⅓) to about two thirds (⅔) (one half (½) in the preferred embodiment) the length of body  18 , and inner edge  54  will preferably be about one sixteenth ({fraction (1/16)}) to about three sixteenths ({fraction (3/16)}) (in the preferred embodiment about one eight (⅛)) the length of body  18 . This is expected to create a range of sizes of surface areas for lateral sides  64  to provide the desirable flow-straightening without creating unacceptable drag. 
     As shown in FIG. 3, fan blades  62  are generally aligned with throat  28  of venturi surface  22 . Such fan blades  62  have a first fan blade side  66  and a second fan blade side  68 . The fan blade sides  66 ,  68  are typically sized so that each has a surface area which is are equal to or smaller than the surface area of the lateral side  64  of a support  40 . In other words, the lateral side  64  of a support  40  has a surface area at least equal to the surface area of a fan blade side. In the preferred embodiment the inside diameter of throat  28  is about 3.83 inches (9.7 cm) while the tip diameter  72  and root diameter  74  of fan blade assembly  46  are about 3.75 inches (9.5 cm) and 1.5 inches (3.8 cm), respectively. Mounting plate  44  has an outside diameter of about 1.125 inches (2.86 cm) while motor  42  has a somewhat smaller diameter of about 1 inch (2.54 cm). Typically, the center  70  of fan blade assembly  46  is located from about 2.25 inches (5.7 cm) forward, that is towards first end  24 , to about 5.75 inches (14.6 cm) rearward, that is towards second end  26  of throat  28 , with blower  14  of the size described. 
     FIG. 5 is an electrical schematic showing the various components of system  2 . A solar panel  76 , such as a 2 feet×4 feet (60 cm×120 cm) solar panel manufactured by Siemens, is mounted to housing  4  and forms one of the walls of the housing. Solar panel  76  is coupled to a charge controller/regulator  78  through a solar panel switch  80  and a terminal strip  82 . A battery  84  is also coupled to controller/regulator  78  through a battery switch  86  and terminal strip  82 . Battery  84  and controller/regulator  78  comprise an electricity storage and control assembly. Motor  42  is connected to controller/regulator  78  through a double pole double throw blower switch  88 , terminal strip  82  and a connector  90 . Connector  90  simplifies the installation of and replacement of motor  42 . With the exception of motor/fan assembly  36 , the components shown in schematic FIG. 5 can be and typically are conventional components. 
     In use, solar-powered soil remediation system  2  is mounted over the upstanding end of a remediation well and clamp  12  is secured to the open upper end of the well. Blower switch  88  is placed in the proper position to cause fan blade assembly  46  to rotate in a chosen direction. Assuming there is sufficient sunlight to power motor  42  or that battery  84  is sufficiently charged to do so, or both, solar panel switch  80 , and battery switch  86  are actuated which causes motor  42  to rotate fan blade assembly  46  in the chosen direction. Switching blower switch  88  to the opposite position causes motor  42  to reverse direction, this causing fan blade assembly  46  to rotate in the opposite direction. This permits blower  14  to act as either a blower or an exhaust fan according to what type of soil remediation is desired. With the exception of brief periodic inspections, system  2  should not require ongoing service or maintenance. 
     A comparison test was conducted to get an idea of the magnitude of the increase in efficiency which results from using venturi surface  22  and flow-straightening supports  40 . In one test a conventional 4 inch (10 cm) in-line blower rated for 240 cfm at 12 volts dc was selected. The motor from the conventional blower was used with a similar fan blade assembly to create a blower similar to that shown in FIG.  3 . Using a Tri-Sense anemometer (Cole-Porter, model 37000-00), the flow rate at 12 vdc was measured at 481 cfm at about 4100 fpm, about a 100% increase. 
     The invention has been described as it relates to blower  14  used with a solar-powered remediation system. The system is light enough that two people can pick it up and place it over the well pipe, typically a 4 inch diameter pipe 6 inches tall. However, blower  14  and all or parts of the remainder of system  2  maybe useful in other circumstances, such as remote sampling of air for determining levels of air pollution, a fan system for a bathroom vent, and blowing fresh air into confined areas such as mines, valve boxes, storage lockers, etc. 
     Modification and variation can be made to the disclosed embodiment without departing from the subject of the invention as defined in the following claims.