Abstract:
The invention provides method and system of controlling flow rate in a pipeline network for fluids. The system includes a demand management system to monitor fluid flow rate in the pipeline network ( 10 ) and a pump ( 34 ) to increase the fluid flow rate when the demand management system determines an increase in fluid flow rate is required.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a pipeline system for fluids and relates particularly, but not exclusively to controlling flow rate in a gravity fed irrigation pipeline system. 
       BACKGROUND OF THE INVENTION 
       [0002]    Traditionally pipeline fluid networks are energized by a source such as a pump. The energy supplied by the pump is often at a pressure head that ensures the hydraulic performance from the system such as required flows and pressures are more than adequately accommodated. These systems are often designed with the criterion that pressure levels should be over and above maximum design requirements. 
         [0003]    Low energy or gravity fed pipelines, on the other hand, need to operate within the capacity of a limited supply pressure head. As described in our International Patent Application PCT/AU2012/000907 (the entirety of which is herein incorporated), the use of a demand management system in combination with real-time control is described allowing for the tight management of demand to ensure that the system operates within the supply pressure head, but does not exceed it. The use of a combined flow meter and bi-foldable valve member as described in our International Patent Application PCT/AU2012/000328 (the entirety of which is herein incorporated), provides a configuration enabling one or more supply points as outlets from the pipe network. These supply points can then be connected to a real-time monitoring (flow and valve opening) and control (valve operation) SCADA (Supervisory Control and Data Acquisition) system similar in operation to that described in U.S. Pat. No. 7,152,001 (the entirety of which is herein incorporated). It would be expected that head conditions for the supply and delivery points of the pipe network be subject to some variation. 
       OBJECTS OF THE INVENTION 
       [0004]    It is an object of the invention to provide a method and system to have the ability to control flows at the outlets in order to manage within limited head conditions and avoid any compounding interactions from these head variations. 
         [0005]    A further object of the invention is to provide a method and system where pipelines can operate under gravity and can be assisted to meet additional pressure demands. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention in one aspect provides a method of controlling flow rate in a gravity fed or pressurised pipeline network for fluids, said method including the steps of monitoring fluid flow rate in said pipeline network and increasing said fluid flow rate when said monitoring step determines an increase in fluid flow rate is required. 
         [0007]    Preferably a pump is provided in said pipeline network, said pump being switchable between pumping and non-pumping modes by a demand management system providing said monitoring of fluid flow rate in said pipeline network. 
         [0008]    In a preferred embodiment at least one fluid control gate is provided at an inlet of said pipeline network, said at least one fluid control gate being movable between open and closed positions under control of said demand management system. 
         [0009]    In a practical embodiment said pump is an Archimedes screw type pump in said pipeline network allowing fluid to flow therethrough when said pump is in the non-pumping mode. 
         [0010]    In a further preferred aspect of the invention said pipeline network includes at least one main pipeline and a branch pipeline leading into said at least one main pipeline at one end and opening into a source of fluid to be pumped at the other end, said method further including the steps of installing said pump in said branch pipeline to allow said pump to force fluid under pressure into said at least one main pipeline in said pumping mode. 
         [0011]    Preferably said demand management system closes said at least one fluid control gate whilst said pump is in said pumping mode. 
         [0012]    In a further aspect of the invention there is provided a system of controlling flow rate in a gravity fed or pressurised pipeline network for fluids, said system including a demand management system to monitor fluid flow rate in said pipeline network and a pump to increase said fluid flow rate when said demand management system determines an increase in fluid flow rate is required. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The structure and functional features of preferred embodiments of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
           [0014]      FIG. 1  is a perspective partial cross-sectional view of an irrigation system in accordance with a first embodiment of the invention showing an undershot gate with the gate open and showing the flow of water through the gate in the unpressurized state; 
           [0015]      FIG. 2  is a similar view to that of  FIG. 1  with the undershot gate closed and showing the flow of water in the pressurized state; 
           [0016]      FIG. 3  is perspective partial cross-sectional view of an irrigation system in accordance with a second embodiment of the invention showing an undershot gate with the gate open and showing the flow of water through the gate in the unpressurized state; 
           [0017]      FIG. 4  is a graph of the pressure head against time for operation of the irrigation system. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    In order to avoid duplication of description, identical reference numerals will be shown, where applicable, throughout the illustrated embodiments to indicate similar integers. 
         [0019]    The embodiments describe the configuration of a pipeline network to exploit situations where there is limited available pressure head supplying water to the network and where pipelines operate under gravity and are supplied by reservoirs such as an open channel system. The invention is not limited to environments where pipelines operate under gravity as it is also applicable to pumped or pressurised pipeline networks. 
         [0020]      FIG. 1  shows an irrigation system  10  having a main open channel  12  for flow of water under gravity. The open channel  12  has angled sidewalls, of which only one  14 , is shown. Water flows in the direction of arrow  16  and enters one or more inlets  18 . Inlet  18  opens into a pipeline  20  through undershot gate  22  and flow measurement device  24 . The flow measurement device  24  is optional as flows can be measured elsewhere in the irrigation system  10 . The construction and operation of the undershot gate  22  and flow measurement device  24  is fully described in  FIGS. 28 to 36  of International Patent Application No. PCT/AU2010/001052 (the entirety of which is herein incorporated). This type of gate is preferred as it includes double seals as described which provides a barrier to flow either side of gate leaf  26 . It is evident to the man skilled in the art that the invention is not limited to such a gate construction and that other types of gates could be utilized. Water enters inlet  18  and flows through flow measurement device  24  and undershot gate  22  to exit through pipeline  20 . The exit  28  is typically coupled to a further pipeline  29  of and the further pipeline  29  has supply points  33  along its length for distribution of water to consumers. Each supply point  33  would preferably include a combined flow meter and bi-foldable valve member (not shown) as described in our International Patent Application PCT/AU2012/000328. Such a flow meter immediately upstream of the bi-foldable valve is possible due to the symmetrical velocity profile created by the bi-foldable valve member. These valves are a cost effective means of both controlling and measuring flow with minimal head loss, which is critical in these low head applications. Fluid head loss through a pipe fitting can be calculated by the following equation: 
         [0000]        h=K×v   2 /2 g    
         [0000]    where
 
h=pressure loss in terms of fluid head, i.e. fluid head loss
 
K=manufacturer&#39;s published ‘K’ factor for the fitting
 
v=velocity of fluid
 
g=acceleration due to gravity
 
         [0021]    The combined valve and meter has low energy loss because (i) it is suited to large diameter pipes, therefore large cross-sectional area; and therefore low velocity; and (ii) low K factor due to hydraulic characteristics of the valve design. 
         [0022]    Supply points  33  can then be connected to a real-time monitoring (flow and valve opening) and control (valve operation) SCADA system (not shown), similar in operation to that described in U.S. Pat. No. 7,152,001 and a demand management system (not shown) of the type described in our International Patent Application PCT/AU2012/000907. As previously described in U.S. Pat. No. 7,152,001 a model of the pipeline would be tuned using data from the SCADA system using the Systems Identification technique also described in U.S. Pat. No. 7,152,001. 
         [0023]    Typically, gravity supply of water along open channel  12  will satisfy much of the required demand from the pipeline  20 . However during small peak periods an additional pressure head is required. A pipeline  30  opens into pipeline  20  at  31  to provide pressurized water when required. Pipeline  30  has an inlet  32  opening into the open channel  12  below water level. A low head lift pump  34  can directly inject pressurized water into pipeline  30  with the suction side  32  of the pump taking water from open channel  12  with the delivery side of the pump connecting to low energy pipeline  20  through the connection at  31  to pipeline  20 . The gate  22  will act as a flow control device when operating under gravity supply mode as shown in  FIG. 1 . The gate leaf  26  would close off the pipeline entrance  18 , as shown in  FIG. 2 , when pump  34  operates, ensuring the pump pressure is maintained in the pipelines  20 ,  30 . No water will enter pipe  20  through gate  22 . Gate  22  has the ability to act as a sealing barrier to pressure from both sides of gate leaf  26  due to the double seal mechanism as previously described. Pump  34  will cease to operate when the demand management and control system determines that the demand has passed and gate leaf  26  will be raised so water flow only occurs through pipeline  20 . 
         [0024]    The embodiment shown in  FIG. 3  is similar to the embodiment shown in  FIGS. 1 and 2  but is simplified with the omission of pipeline  30  and pump  34 . The inclusion/insertion of an axial screw pump mechanism  36  within pipeline  20 . The axial screw concept is equivalent to the known concept of an ‘Archimedes’ Screw&#39; and used commercially in axial lift pumps. The screw mechanism  36  is located axially within the pipeline  30  and is connected to an electrical motor  38 . It is preferred to have the motor  38  directly coupled to and in-line with the screw&#39;s axial drive shaft  40 . The motor  38  would be sealed to prevent ingress of water. In gravity supply mode, the screw pump mechanism  36  would ‘free-wheel’ with minimal resistance and therefore minimal energy loss under gravity. In the activated pumping mode, the motor would drive the screw mechanism  36  which in turn would result in added energy and pressure to the water in the pipe  20  downstream of the screw pump mechanism  36 . 
         [0025]    The operation of the systems shown in  FIGS. 1 to 3  is shown in the graph of  FIG. 4 . The graph shows the demand for the majority of the time can be met from the gravity supply pressure head as indicated by line  42 . If the demand exceeds the gravity supply pressure head indicated by the plateau indicated by line  44 , the option is to either re-schedule the demand so that it does not exceed the gravity pressure head, or alternatively, invoke the pumping systems  34 ,  36  for this period of time. The effect of the invoking of the pumping systems  34 ,  36  are shown by line  46 . The time of operation is indicated by arrows  48  on the time line of the graph. This option may also be presented to a user of the system where a higher tariff could be charged if the pump option was selected. 
         [0026]    This invention describes a combined gravity and pressurized pipeline system where the pumped pressure supply is an adjunct to the gravity system and is only invoked when additional pressure head, is required. The demand management and control system ensures the desired operation of the auxiliary pump facility only during prescribed peak requirements. 
         [0027]    The invention will be understood to embrace many further modifications as will be readily apparent to persons skilled in the art and which will be deemed to reside within the broad scope and ambit of the invention, there having been set forth herein only the broad nature of the invention and certain specific embodiments by way of example.