Abstract:
A bladder surge tank includes a liquid port, and a bladder disposed therein for providing a surge absorbing interface between liquid and pressurized gas within the tank. The bladder surge tank can be horizontally or vertically oriented. In a horizontal embodiment, the surge tank includes a nozzle system disposed horizontally therein that is separate from the liquid port and that is integrally joined to the interior wall. Such nozzle system includes a nozzle member positioned between the liquid port and the bladder, and comprises a plurality of perforations disposed therethrough. In a vertical embodiment, the surge tank includes a nozzle system disposed vertically therein that is part of the liquid port and that includes a nozzle member having a plurality of perforations disposed therethrough. In both embodiment, the perforations define a total area that is greater than a total area of the liquid port, and the perforations are distributed throughout the nozzle member such that liquid entering the tank body through the liquid port is dispersed uniformly into the tank body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional application No. 60/301,732, filed on Jun. 27, 2001. 

   FIELD OF THE INVENTION 
   The present invention relates to a surge tanks, and more specifically, bladder surge tanks having a nozzle adapted to allow liquid to uniformly enter and exit the bladder surge tank. 
   BACKGROUND OF THE INVENTION 
   Surge tanks are designed to control pressure surges or transients in pipelines, which are created when the flow of the fluid is abruptly changed. Pressure transients can be either positive or negative and are potentially destructive and may result in damage to piping, pumps, instruments, fittings, or other system components. 
   Surge tanks have been used for years as a means for controlling pressure transients. Some surge tanks employ a bladder design and are well known having applications within various industries, including fire protection systems, municipal water and sewage systems, desalination facilities, fuel systems, and chemical and petrochemical facilities. 
   During a pump start up, for example, a high transient of pressure is created at the pump discharge. Installation of a bladder surge tank at the pump discharge absorbs the fluid from the pump until the fluid achieves steady state velocity, then the surge tank discharges the fluid into the system to balance the pressure and eliminate the pressure transient. Pressure transients may also be created where there is a sudden and abrupt cessation of liquid flow, hereto, bladder surge tanks can eliminate the pressure transient. Bladder surge tanks also have application as a deluge surge tank where the instantaneous discharge of fluid is required in, for example, fire protection systems. 
   Regardless of the application, the shape of the bladder during gas precharge or fluid discharge is not totally controllable. In systems where the flow rate exceeds 500 gpm, the bladder may actually seal the tank&#39;s fluid inlet/outlet opening during liquid discharge and prevent the tank from emptying its liquid contents. To prevent this, some bladder surge tank manufacturers have placed a wire screen in the tank&#39;s inlet/outlet opening. Unfortunately, such a screen actually impedes the liquid flow and is not totally effective in preventing the bladder from blocking the tank&#39;s fluid inlet/outlet opening during fluid discharge. 
   Where there is a sudden flow of fluid into a bladder surge tank, the force of the incoming fluid is concentrated and assumes the shape of the tank&#39;s fluid inlet/outlet opening. Such a column of fluid and its associated force is directed towards that portion of the bladder directly above the tank&#39;s inlet/outlet opening and can cause damage to the bladder. 
   There remains a need for a bladder surge tank that eliminates the likelihood of having the bladder block the tank&#39;s inlet/outlet opening during fluid discharge and thus interfere with the flow of fluid out of the bladder surge tank. There also remains a need for a bladder surge tank which can redirect the fluid entering the bladder surge tank in a more uniform pattern, thus reducing the possibility of bladder damage from the force of the incoming fluid. 
   SUMMARY OF THE INVENTION 
   High flow nozzle systems of this invention are provided for use with bladder surge tanks for the purpose of overcoming the aforementioned bladder blockage and bladder damage problem in the prior art bladder surge tanks. The nozzle systems of this invention comprise a uniquely designed nozzle member that is configured to cover the surge tank&#39;s fluid inlet/outlet opening. The nozzle member is designed to allow fluid to quickly and uniformly enter and exit the tank while at the same time reducing or eliminating the possibility of having the bladder block the tank&#39;s inlet/outlet fluid opening during fluid discharge. 
   The inventive nozzle member is provided in the form of a diffusor having multiple perforations, which act to disperse the fluid as it enters the tank, thereby redirecting the force of the incoming fluid and reducing damage to the bladder. Two embodiments of this inventive nozzle system include a horizontal nozzle member for use in a horizontal bladder surge tank, and a vertical nozzle member for use in a vertical bladder surge tank. The nozzle member can be integral with the tank&#39;s fluid inlet/outlet port, i.e., be provided as part of the inlet/outlet port itself, or can be non-integral with the inlet/outlet port, i.e., be separate from the inlet/outlet port. 
   In the case of applications within both the vertical and horizontal surge tanks, the inventive nozzle member is located between the tank&#39;s bladder and the tank&#39;s fluid inlet/outlet opening. The nozzle member has numerous perforations or openings therethrough that are arranged in a unique pattern. The perforation design also allows fluid to rapidly and uniformly enter or exit the surge tank, thereby eliminating unwanted pressure transients. The location, size, pattern, and number of openings through the nozzle member are mathematically determined to greatly reduce, if not eliminate altogether, the possibility of having the bladder collapse and block the tank&#39;s inlet/outlet opening before all of the fluid has been discharged. The openings also operate to disperse and redirect the flow of fluid entering the bladder surge tank, such that the force exerted by the incoming fluid is not directed towards a single portion of the bladder. 
   High flow nozzle systems of this invention are suitable for use in bladder tanks used in virtually every industry, including waste water and sewage systems, fuel-loading systems, petrochemical and chemical systems, desalination, and fire protection systems. Horizontal and vertical bladder surge tanks, fabricated with the nozzle system of this invention, provide a means for redirecting and more uniformly distributing the fluid entering the tank, thereby reducing the possibility of damage to the bladder caused by the force of the fluid during a sudden inflow. Further, upon a sudden dispensement of fluid from the tank, the inventive nozzle system virtually eliminates the possibility of having the bladder block the tank&#39;s inlet/outlet opening before all of the fluid has been discharged. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a cross-sectional side elevation of a horizontal surge tank comprising a high flow nozzle system of this invention; 
       FIG. 2  is a top perspective view of a nozzle member taken from the nozzle system of  FIG. 1 ; 
       FIG. 3  is a side view of the horizontal nozzle member end tab of  FIG. 2 ; 
       FIGS. 4A and 4B  are cross-sectional side elevations of the horizontal surge tank of  FIG. 1 , illustrating the position of a bladder at different liquid levels within the tank (FIG.  4 A—as the tank is being filled with liquid; and FIG.  4 B—when the tank is full of liquid); 
       FIG. 4C  is a fragmentary sectional view of the nozzle system of  FIG. 1 , illustrating the position of the nozzle member within the horizontal bladder surge tank and the flow of liquid through the nozzle member; 
       FIG. 5  is a cross-sectional side elevation of a vertical bladder surge tank comprising a high flow nozzle system of this invention; 
       FIG. 6  is a cross-sectional side elevation of a nozzle member taken from the nozzle system of  FIG. 5 ; 
       FIG. 7  is a fragmentary sectional view of one of the openings through the nozzle system nozzle member of  FIGS. 5 and 6 ; and 
       FIG. 8  is a fragmentary perspective view of the nozzle system nozzle member of FIG.  6 . 
   

   DETAILED DESCRIPTION 
   In accordance with the present invention, there is provided improved bladder surge tanks comprising high flow nozzle systems suitable for use in various systems such as fire protection systems, waste water and sewage systems, fuel loading systems, desalination systems, and chemical and petro-chemical facilities. In particular, bladder surge tanks comprising high flow nozzle systems of this invention have specific application as deluge tanks, where the immediate discharge of liquid is required, in for example fire retardation. 
     FIG. 1  illustrates a horizontal bladder surge tank  10  comprising a high flow nozzle system  11  of this invention. The horizontal bladder surge tank  10  is a pressure vessel which contains a bladder  13 , a liquid port or a fluid inlet/outlet port  15 , and a nozzle system  11  positioned within the tank adjacent a terminal end of the inlet/outlet port  15 . The horizontal bladder surge tank  10  comprises a body  16  having a bladder access opening  18  disposed therethrough at one end of the tank  10 . Opposite the bladder access opening  18  is a gas charging valve  24 , a rupture disc  17 , and a pressure gauge  19 . Other components of the surge tank may be added or deleted depending upon need. 
   Horizontal surge tanks can vary in size from about 250 gallons to more than 5,000 gallons or more. Surge tanks used with high flow nozzle systems of this invention may be constructed from a variety of materials, so long as the material has sufficient strength to support the load and operating pressures and is chemically resistant to the fluid being pumped. In the preferred embodiment, the material of construction is epoxy-coated carbon steel or stainless steel. 
   The horizontal bladder surge tank  10  is shown supported by two saddles  21 . It is understood that the horizontal surge tank  10  may also be supported by legs. The bladder surge tank  10  may also be fitted with lift tabs  14 , which allows the tank to be suspended and placed at the desired location with ease. 
   The bladder  13  is located within and adjacent to an interior wall of the surge tank body  16  and nozzle system  11 . The bladder  13  may be constructed from a variety of materials which are suitable to contain gas under pressure as well as being resistant to attack from the liquid within the system. The bladder  13  must also be strong enough to withstand the pressure or force exerted upon it by the incoming fluid. In the preferred embodiment, the bladder  13  is made of a synthetic nitrile rubber, such as buna-n. 
   The tank&#39;s liquid inlet/outlet opening  15  is located at the base of tank  11  and allows fluid to enter and exit the tank  10 . The dimensions of fluid inlet/outlet  15  opening may vary depending upon system needs. 
   The high flow nozzle system  11  of this invention includes a nozzle member  12  that is positioned adjacent a terminal end of the inlet/outlet port  15  within the tank. The nozzle member  12  is generally rectangular in shape, and is generally flat with rounded ends. In this particular embodiment, configured for placement within a horizontal surge tank, the nozzle member  12  is nonintegral and provided as a system element that is separate from the inlet/outlet port. 
   The nozzle member  12  is positioned a discrete distance above the tank body  16  interior wall, and is located above the tank&#39;s liquid inlet/outlet port  15 , forming a floor plate within the tank above the port. The nozzle member  12  is placed into its position within the tank by a number of support posts  20 , which operate to elevate the nozzle member  12  a desired distance above the fluid&#39;s inlet/outlet port  15 . The location, number and size of support posts  20  that are used is important as the posts  20  must be of sufficient strength to uniformly support the nozzle member  12  under the pressure of either the bladder precharge or the tank&#39;s fluid. 
   In a preferred embodiment, the nozzle member  12  is supported by approximately sixteen support posts  20 . The distance that the nozzle member  12  sits above tank&#39;s fluid inlet/outlet port  15  is calculated to allow optimum flow rate into and out of the tank. The nozzle member  12  is connected to the support posts  20  by any means sufficient to secure the two nozzle system members together, and sufficient to withstand the force exerted upon the connection by the fluid entering or exiting the surge tank  10 . In a preferred embodiment, the nozzle member  12  is attached to the support posts  20  by screws. 
   In the tank  10  of  FIG. 1 , gas is introduced into bladder  13  by way of the gas charging valve  24 . The bladder  13  is filled with a predetermined volume of gas, and typically the bladder  13  is filled to 85% capacity. In a preferred embodiment, the gas is nitrogen. 
     FIG. 2  illustrates a top plan view of the nozzle member  12 , of the high flow nozzle system of this invention, showing the sides  32  positioned at each end nozzle member, both comprising a plurality of perforations  31  disposed therethrough. The size, number and location of the perforations  31  are determined by a series of mathematical equations that are presented in detail below. The total surface area of all perforations  31  through the nozzle member  12  is desired to exceed the total surface area of the tank&#39;s inlet/outlet port  15 . The exact size of the perforations  31  will vary depending upon the operating pressure of the system. 
   In a preferred embodiment, approximately 77% of the perforations  31  in the nozzle member  12  are located directly above the tank&#39;s fluid inlet/outlet port  15 . The balance of the perforations  31  are equally spaced throughout the remaining surfaces of the nozzle member  12 . Approximately 23% of the perforations  31  through the nozzle member are not directly over the tank&#39;s fluid inlet/outlet port, and therefore act to disperse and redirect the incoming fluid throughout tank  11 . 
   The nozzle member  12  may be made from a variety of materials so long as they are chemically resistant to the liquid being pumped, and are capable of withstanding the operating pressures of the system. In a preferred embodiment, the nozzle member  12  is made of stainless steel. 
     FIG. 3  is a side view of the nozzle member  12  showing one of the nozzle member sides  32 , and illustrating the location and position of perforations  31  therethrough. The nozzle member side  32  is configured to conform with the interior dimensions of tank  10 , such that the nozzle member  12  fits with an adjacent portion of the tank body  16  interior wall. 
     FIG. 4A  illustrates the position of the bladder  13  against the interior wall surface in the horizontal bladder surge tank  11  after the bladder  13  has been charged with pressurized gas, but no liquid is in tank  11 .  FIG. 4B  illustrates the position of the bladder  13  in the horizontal bladder surge tank  10  after the bladder  13  has been charged and after liquid has entered the tank  11 . The liquid entering the tank causes the portion of the bladder above the inlet/outlet port  15  to be displaced outwardly away from a bottom portion of the tank interior wall surface, and inwardly into the tank. The position of the bladder  13  in  FIG. 4B  is clearly above the nozzle member  12 . 
     FIG. 4C  is a fragmentary sectional view of the inventive nozzle member  12  of this invention  12  as it is disposed just above the tank&#39;s inlet/outlet port  15 .  FIG. 4C  shows the location of some of the support posts  20 , interposed between the tank body wall  16  and the nozzle member  12 , as well as some of the nozzle member perforations  31 . Dual headed arrows illustrate the flow path of the liquid as it enters and exits the tank  10  through nozzle member perforations  31 . 
   A series of mathematical formulas are used to determine the number and placement of the perforations  31  in the nozzle member  12  as configured for use in the horizontal surge tank  10 . In an example embodiment, the following mathematical formulas are used to determine the number and placement of perforations in a 500 gallon horizontal surge tank having an 8-inch diameter inlet/outlet port, and having an operating pressure of approximately 275 psi. 
   Horizontal Surge Tank Nozzle System Mathematical Formulas 
   Number of holes in nozzle member located above the inlet/outlet port=333 
   Approximate hole diameter=0.375 in. 
   Surface area of holes located above the inlet/outlet port=333×π/4(0.375) 2 =36.8 in. 2    
   Number of holes around the inlet/outlet port=98 
   Approximate hole diameter=0.375 in. 
   Surface area of holes around the inlet/outlet port=98×ρ/4(0.375) 2 =10.8 in. 2    
   Total opening area through surge tank=36.8+10.8=47.6 in. 2    
   Percentage of openings above the inlet/outlet port=36.8/47.6×100=77% 
   Inlet/outlet port area (8 in. Sch 80 pipe)=45.7 in. 2 . 
   The total surface area of the nozzle member perforations  31  for this example application is approximately 47.6 square inches, and the total area of the tank&#39;s fluid inlet/outlet port  15  is approximately 45.7 square inches. 
     FIG. 5  illustrates a vertical bladder surge tank  40  comprising a high flow nozzle system  50  of this invention adapted for use in the same. The vertical bladder surge tank  40  has a fluid inlet/outlet port  43  located at a base portion of the tank, which allows fluid to enter or exit the tank  40 . The vertical tank&#39;s fluid inlet/outlet port  43  may vary in size depending upon tank application and system needs. 
   In this example embodiment, the vertical bladder surge tank  40  is a pressure vessel having a bladder  41  which rests between an interior wall  42  of the tank and the inventive nozzle system  50 . Thus, unlike the nozzle system configured for use in a horizontal surge tank (where the nozzle system is disposed outside of the bladder, between a portion of the tank interior wall and the bladder), the nozzle system as adapted for use in this vertical surge tank is actually disposed within the bladder itself. 
   The nozzle system  50  for this vertically oriented surge tank application includes a nozzle member  51  that is provided as an integral part of the inlet/outlet port  43 . Specifically, the nozzle member  51  is positioned adjacent a terminal end of the inlet/outlet port  43 . The nozzle member  51  is positioned vertically above the inlet/outlet port  43  such that any fluid entering or exiting the tank through the port  43  must also pass through nozzle system nozzle member  51 . 
   The vertical bladder surge tank  40  is supported by four legs  44 , only two of which are shown. The vertical bladder surge tank  40  is also configured with lift tabs  45  that may be used to facilitate ease of placement. The vertical bladder surge tank  40  is also designed to include a pressure gauge  46 , a gas valve  47 , and a rupture disk  48 , or other components as may be required. 
   The inlet/outlet port  43  is disposed through an opening at the base of the tank, and the nozzle system  50  is positioned within the tank interior chamber, and within the bladder itself. The bladder includes a flange-type attachment that is secured to the tank body by conventional means concentrically around the inlet/outlet port  53 . 
   Vertical bladder surge tanks  40  can vary in size from about 250 gallons to more than 5000 gallons, and may be made from a variety of materials, so long as the material has sufficient strength to support the load and operating pressures and is chemically resistant to the fluid being pumped. In a preferred embodiment, the material of construction is epoxy-coated carbon steel or stainless steel. 
   The bladder  41  may be made from a variety of materials so long as each is suitable to contain gas under pressure as well as being resistant to attack from the liquid within the system. The bladder  41  must also be sufficiently strong enough to withstand the pressure or force exerted upon it by the incoming fluid. In a preferred embodiment, bladder  41  is made of synthetic nitrile rubber, such as buna-n. 
   In the vertical surge tank of  FIG. 5 , gas is introduced into the tank&#39;s interior cavity by way of gas charging valve  47 . The bladder  41  is filled with the surge liquid, and typically the bladder  41  is filled to between about 80% to 85% capacity. In a preferred embodiment, the gas is nitrogen. 
     FIG. 6  is an enlarged view of the nozzle system  50  of this invention illustrating the relationship between the nozzle member  51  and the inlet/outlet port  43 . The nozzle member  51  has a generally cylindrical cross section, is column shaped, and includes a plurality of perforations  54  therethrough that are located at predetermined locations. The nozzle member  51  covers the tank&#39;s inlet/out port  43 , and is attached to the vertical bladder surge tank  40  by way of a flange  56  and bolts (not shown). The nozzle member  51  includes a closed and rounded end  55  opposite the tank&#39;s fluid inlet/outlet port  43  to prevent damage to bladder  41 . 
   The nozzle member  51  includes two internal baffles  53 , which are placed at predetermined locations diametrically within the nozzle member to provide a consistent pressure drop which results in a laminar flow of liquid. The location of the perforations  54  along the wall surface of the nozzle member also acts to disperse the incoming liquid uniformly over a wide area so as to minimize any damage to the bladder which could occur were the force of the incoming liquid focused upon one area of the bladder. The total area of perforations  54  preferably exceeds the total area of the tank&#39;s fluid inlet/outlet port  43 . The size, number and location of perforations  54  are determined by a series of mathematical calculations better described below. The size of the perforations  54  will also vary depending upon the operating pressure of the system. 
     FIG. 7  is a fragmentary sectional view of one of the perforations  54  of the nozzle member  51  as seen in  FIGS. 5 and 6 .  FIG. 8  is a fragmentary perspective view of a portion of the nozzle member  51  showing the perforations  54 . 
   A series of equations is used in calculating the number and placement of each perforation  54  in the nozzle system nozzle member  51  for use in a vertical bladder surge tank application. In an example embodiment, the following mathematical equations are used to calculate the number and placement of perforations for use within a 500 gallon vertical surge tank having an 8-inch diameter inlet/outlet opening at an operating pressure of 250 psi. 
   Vertical Surge Tank Nozzle System Mathematical Formulas 
   Three sections of holes 
   Nine rows in each section 
   Sixteen holes in each row 
   Number of holes in nozzle member=3 sections×9 rows×16 holes=432 
   Approximate hole diameter=0.50 in. 
   Surface area of holes in nozzle member=432×π/4(0.50) 2 =84.8 in. 2    
   Inlet/outlet nozzle system area (8 in. Sch 40 pipe)
         ID=7.981 in.; π/4(7,981) 2 =50.0 in 2          

   The total surface area of the perforations  54  in the vertical nozzle system nozzle member  51  is approximately 84.8 square inches; and the total surface area of the tank&#39;s fluid inlet/outlet port is approximately 50 square inches. 
   The above-described embodiments of the present invention are merely descriptive of its principles and are not to be considered limiting. The scope of the present invention instead shall be determined from the scope of the following claims including their equivalents.