Patent Publication Number: US-8535018-B2

Title: Balancing liquid pumping system

Description:
TECHNICAL FIELD 
     This present disclosure relates to the field of liquid pumping systems, and more specifically, to a pump and a system for pumping liquid using a gas and liquid balancing effect. 
     BACKGROUND 
     Liquid and energy are precious resources. In many geographical areas, the most accessible source of liquid is in the form of liquid. A ground water table, defined as a level at which the groundwater pressure is equal to atmospheric pressure, may be found within depths of a few tens of meters in many areas, including in locations that are otherwise far remote from any lake or river. Ground water is generally extracted using electric pumps that are located at the bottom of wells dug into the ground. 
     Energy, including electrical energy, is costly and may be of limited availability in areas where groundwater needs to be extracted. In some areas, groundwater availability may actually be high while electrical resources are limited and costly. Pumping liquid from other sources, such as a river or a lake also requires energy, which can sometimes be scarce. 
     Therefore, there is a need for economical techniques for pumping liquid and for generating energy. 
     SUMMARY 
     Therefore, according to the present disclosure, there is provided a system for pumping liquid comprising two liquid columns for reaching a body of liquid at their bottom. Each liquid column comprises a liquid level detector and a one-way valve allowing liquid to flow upward. An upper conduit is for sealably connecting at both ends to the top of the two liquid columns. The upper conduit comprises a sealable gas valve for extracting gas from the upper conduit. An actuated conduit is for connecting, at each end, to one of the two liquid columns above its one-way valve. The actuated conduit also comprises, at each end, a one-way valve allowing liquid to flow inward from each of the two liquid columns. The actuated conduit further comprises, between its two one-way valves, a switched valve allowing liquid to flow out of the system from each one-way valve at a time. A controller is for connecting to the liquid level detectors and for controlling the switched valve. As gas is extracted from the upper conduit, liquid in each of the two liquid columns raises to a starting level. As the gas valve is sealed, liquid from one of the liquid columns flows out of the system through the actuated conduit and through the switched valve. Then, as the liquid level in one of the liquid columns reaches a minimum level, the switched valve switches to allow liquid to flow from the other liquid column. 
     According to the present disclosure, there is also provided a balancing liquid pump. The pump comprises a sealable gas-liquid balancing conduit, two inlet conduits for connecting to a body of liquid at their bottom in unidirectional upward direction and for connecting to the gas-liquid balancing conduit at their top, and two unidirectional inward outlet conduits. Each outlet conduit is for connecting at one end to one of the inlet conduits and at another end to a common switched valve allowing liquid to flow out of the pump from one of the two inlet conduits at a time. A starting system is used for initiating a flow of liquid from the body of liquid and for raising a level of liquid in at least one of the inlet conduits. As liquid flows out of the pump from one of the inlet conduits, a level of liquid that inlet conduit goes down, and gas in the gas-liquid balancing conduit follows the level of liquid in that inlet conduit. This movement of the gas in the gas-liquid balancing conduit pumps liquid from the body of liquid into the other inlet conduit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure will be described by way of example only with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram of an exemplary balancing liquid pumping system; 
         FIG. 2  is a schematic diagram of an exemplary one-way valve; and 
         FIG. 3  is a schematic diagram of an alternative liquid pumping system coupled to an electric generator. 
     
    
    
     DETAILED DESCRIPTION 
     A system for pumping liquid using a balancing effect, also called a balancing liquid pump, comprises two liquid columns reaching a body of liquid at their bottom and connected at their top by a sealable upper connecting conduit that contains gas. The term ‘gas’ is used throughout the present specification and claims for simplicity purposes, but it is used to refer to any of the following: ambient air, filtered air, an inert gas, or any other gas. Gas within the upper connecting conduit moves as liquid levels change within the liquid columns. The liquid columns may be formed of pipes dug into the ground, for example steel or plastic pipes, similar to those used for pumping liquid using underground pumps. The liquid columns constitute inlet conduits connected to the body of liquid, for bringing liquid into the system. These conduits may have a circular perimeter or any other perimeter shape. Whether vertical or angled relative to the ground, whether straight, bent or curved, any inlet conduit shape may form a suitable liquid column. The liquid columns are upwardly unidirectional for a substantial part of their length, one-way valves within the liquid columns allowing liquid to flow upwards in the liquid columns between the body of liquid and an actuated conduit. The actuated conduit contains liquid, connects the liquid columns and further connects to an output conduit. Additional one-way valves allow liquid to flow unidirectionally inward into the actuated conduit from each of the liquid columns. A switched valve within the actuated conduit, between the additional one-way valves, allows liquid coming from one of the liquid columns at a time to flow into the output conduit and out of the system. The switched valve has two reversible sides; one open side faces one of the liquid columns for allowing liquid to flow therefrom, and one closed side faces the other liquid column and blocks any liquid flow therefrom. The switched valve is controlled by liquid level detectors located near the top of each liquid columns. A starting system comprising a gas valve allows extracting gas from the upper connecting conduit. This action starts up the system by bringing liquid up in the liquid columns. Once the system is started, liquid flows down into the actuated conduit and into the output conduit, from one of the liquid columns facing the open side of the switched valve, as determined by a position of the switched valve. Because the two liquid columns are sealably connected by the upper connecting conduit that comprises gas, lowering of the liquid level at that liquid column creates a movement of the gas and a balancing effect, pumping liquid from the body of liquid through the other liquid column. When the liquid level at the top of the liquid column from which liquid is flowing down reaches a minimum level, the switched valve changes its position, allowing liquid to continue flowing into the actuated conduit and into the output conduit, this time from the other liquid column. Liquid is now drawn into the system from the body of liquid through the liquid column facing the side of the switched valve that is closed at that time. 
     Pumping liquid using a balancing effect may be applicable to various types of liquid sources. A body of liquid may comprise a lake, a river, an underground liquid table, or a reservoir. In some applications, liquid may be contaminated or polluted. The term ‘liquid’ is used throughout the present specification and claims for simplicity purposes, but it is not limited to pure or clean liquid. Referring to  FIG. 1 , there is shown a schematic diagram of an exemplary balancing liquid pumping system. The balancing liquid pumping system of  FIG. 1  as illustrated is installed on solid ground and is used for pumping liquid from a liquid table. Application of the balancing liquid pumping system to this specific type of liquid body is solely for purposes of illustration and is not limiting, as the balancing liquid pump may be used for pumping from any body of liquid. 
     In  FIG. 1 , a system  100  comprises two liquid columns  102 ,  104  and an output conduit  106 . The liquid columns  102 ,  104  are dug into the ground  108  and reach groundwater in the liquid table  110 . For realizing the liquid columns  102 ,  104 , solid pipes may be inserted into the ground, down to a level where they connect to the liquid table. As the liquid columns  102 ,  104  are dug, solid rock may be encountered, in which case a hollowed-out portion of the rock may substitute at least in part for the solid pipes. In an embodiment, insulation  103 ,  105  may be added onto the liquid columns  102 ,  104 , in order to prevent winter damage to the liquid columns  102 ,  104 . The insulation  103 ,  105  may extend below a lowest ground freeze line, for example up to 5 feet into the ground  108 , and may cover any above ground part of the liquid columns  102 ,  104 . Of course, additional insulation material (not shown) may cover any conduit being exposed to adverse climate conditions The liquid columns  102 ,  104  are sealably connected at their top to an upper connecting conduit  112  and near their top to an actuated conduit  114 . The upper connecting conduit  112  is sealable and acts as a gas-liquid balancing conduit between the liquid columns  102  and  104 . In a non-limiting embodiment, air is present in the upper connecting conduit  112 . The actuated conduit  114  is also connected to the output conduit  106 , optionally via a buffer reservoir  116  and a regulating valve  118  that together regulate a flow of liquid exiting the system  100 . Liquid may only flow upward through these liquid columns  102 ,  104 , which are inlet conduits allowing liquid to flow unidirectionally from the liquid table, because the liquid columns contain one-way valves  120 ,  122 . As shown on  FIG. 1 , arrows on the valves  120 ,  122  indicate that liquid flow is only possible in the upward direction. Liquid drawn up from the liquid columns  102 ,  104  reach into lower parts the upper connecting conduit  112  that do not contain gas. For example, liquid may flow upward within the liquid column  102 , through the valve  120 , thereby filling in part the upper connecting conduit  112 . 
     The actuated conduit  114  is formed of two unidirectional inward outlet conduits  114   a  and  114   b , containing one-way valves  122 ,  126  allowing liquid to flow in the direction shown by arrows, and joining at a common switched valve  128 . Liquid may for example flow downward from the upper connecting conduit  112  through the valve  122  and into the outlet conduit  114   a . The actuated conduit  114  opens in one direction and closes in an opposite direction depending on a position of the switched valve  128 . The switched valve  128  has two dual-purpose positions as one position (as shown in solid line) is at once opened toward the liquid column  102  and closed toward the liquid column  104  while another position (as shown in dashed line) is opened toward the liquid column  104  and closed toward the liquid column  102 . The switched valve  128  may be under the control of a controller  130 , which is itself connected to liquid level detectors  132 ,  134 , located respectively proximate to the top ends of the liquid columns  102 ,  104 . The liquid level detectors  132 ,  134  may for example be level float switches. In an embodiment, gas detectors may detect the presence of gas when the liquid level is below the detectors. In yet an embodiment, the detectors  132 ,  134  may be float switched having sufficient leverage to actuate cables (not shown) that directly actuate the switched valve  128 , without control from a controller. The system  100  may operate with any suitable mechanism for detecting a liquid level and for actuating the switched valve  128 . The controller  130 , if present, may also control the regulating valve  118  via a signal going through a line A. 
     Three distinct reference liquid levels are shown, comprising a maximum liquid level  136 , a minimum liquid level  138 , and a starting liquid level  140 . The same reference liquid levels apply on both sides of the system  100 . Gas  142  is present within the upper connecting conduit  112 , above liquid at any level. A gas valve  144  allows extracting some of the gas  142  from the upper connecting conduit  112 , for starting and restarting the system  100 . When the system  100  is not being started or restarted, the gas valve  144  may be tightly sealed. Because it is sealed, except when the gas valve  144  is opened, the upper connecting conduit  112  maintains a balance of gas and liquid in the system. An embodiment presented hereinbelow shows that the gas valve  144  may, in an aspect, be operated outside of starting or restarting phases. 
     The system  100  of  FIG. 1  is shown in schematic form for illustration purposes and is not to scale. For example, an underground length of the liquid columns  102 ,  104  is sufficient to reach the liquid table  110  and is expected, in most cases, to be longer than an above ground height of any remaining parts of the system  110 . Diameters of the output conduit  106 , of the upper connecting conduit  112  and of the actuated conduit  114  may or may not be similar to those of the liquid columns  102 ,  104 . Also, the actuated conduit  114  is shown in horizontal position, having a straight shape, the switched valve  128  being shown in its mid-length. The switched valve  128  could be positioned closer to one of the one-way valves  122  or  126 , so the two outlet conduits  114   a  and  114   b  may have different lengths. The one-way valves  102 ,  124  are shown near the top of the liquid columns  102 ,  104 , but may be located at any lower point within the liquid columns  102 ,  104 . The actuated conduit  114  could have a curved shape and may be oriented downwards from its extremities towards the switched valve  128 . The upper connecting conduit  112  may have other shapes than the illustrated semi-circular shape. Other variations of various shapes of elements of the system  100  will come to mind to those of ordinary skill in the art. 
     In operation, the system  100  may be started by using a gas pump (not shown) for extracting some of the gas  142  from the upper connecting conduit  112  via the gas valve  144 . This gas aspiration creates a negative pressure within the system  100 , whereby groundwater from the liquid table  110  is pumped upwards within the liquid columns  102 ,  104  and through the one-way valves  120 ,  124  until the starting liquid level  140  is reached. Those of ordinary skill in the art of liquid wells will appreciate that other starting systems may alternatively be used to raise liquid level in at least one of the liquid columns  102 ,  104 , during a starting phase of the system  100 . Assuming that switched valve  128  is initially in the position as shown (solid line), some liquid may flow through the one-way valve  126  into the actuated conduit  114  (into the outlet conduit  114   b ), but the switched valve  128  blocks liquid coming through the one-way valve  126  from flowing any further. More liquid may flow through the one-way valve  122 , into the actuated conduit  114  (through the outlet conduit  114   a ), and then through the switched valve  128 , which is open on that side of the actuated conduit  114 , filling the buffer reservoir  116 . At that time, the controller  130  may keep the regulating valve  118  in a closed position, preventing liquid from flowing out of the system through the output conduit  106 . 
     In an embodiment, the one-way valves  122 ,  126  may be calibrated such that they remain closed and prevent any liquid from entering the actuated conduit  114  while there exists a negative gas pressure within the upper connecting conduit  112 . In another embodiment, the one-way valves  122 ,  126  may be electrically controlled and the controller  130  may control opening and closing of the one-way valves  122 ,  126 , maintaining them closed during the starting phase of the system  100 . In yet another embodiment, the actuated conduit  114  and the switched valve  128  may be substituted by two separate conduits and valves (not shown) that both connect to the buffer reservoir  116  but not to each other. In that case, the valves within the separate conduits may have one open and one closed position, being controlled by the controller  130  to remain both closed during the starting phase. In these embodiments, the controller  130  does not control the regulating valve  118 . The buffer reservoir  116  and the regulating valve  118  may then be absent or may be used for smoothing the flow of liquid exiting the system through the output conduit  106 . 
     When liquid reaches the starting liquid level  140 , as detected by the two liquid level detectors  132 ,  134 , the controller  130  closes the gas valve  144  via a signal going through a line B, thereby sealing the upper connecting conduit  112 . The controller  130  also opens the regulating valve  118 , creating a liquid flow down from the buffer reservoir  116  through the output conduit  106 . Because of the position of the switched valve  128 , liquid then flows through the one-way valve  122  into the actuated conduit  114  and into the buffer reservoir  116 . As mentioned hereinabove, in some embodiments, it is the end of the starting phase of the system  100  that causes opening of the one-way valve  122 , either by the action of liquid pressure within the column  102 , in the absence of gas aspiration at the gas valve  144 , or under control of the controller  130 . In another embodiment, valves within separate conduits instead of the actuated conduit  114  are opened and closed as required based on measurements from the liquid level detectors  132 ,  134 . As a consequence of the opening of the regulating valve  118  or other effect from the end of the starting phase, the liquid level at the top of the liquid column  102  goes down. Because the upper connecting conduit  112  is sealed, this lowering of the liquid level at the top of the liquid column  102  moves gas within the upper connecting conduit  112 , creating a compensation effect by pumping liquid coming from the liquid table  110 , upwards into the liquid column  104  and through the one-way valve  124 . Hence, as the liquid level goes down near the top of the liquid column  102 , this is balanced by the liquid level going up near the top of the liquid column  104 . The liquid level detector  132  eventually detects that the liquid level of the liquid column  102  has reached the minimum level  138 . The controller  130 , based on a reading from the liquid level detector  132 , switches the switched valve  128  from one position (solid line) to an opposite position (dashed line). As mentioned hereinabove, in an embodiment, the liquid level detector  132  may actuate the switched valve  128  using a cable (not shown), in the absence of a controller. Liquid stops flowing through the one-way valve  122  and starts flowing through the one-way valve  126 . The liquid level goes down at the top of the liquid column  104  and this is compensated by liquid coming from the liquid table  110  through the liquid column  102 . 
     Liquid is thus pumped up through the liquid columns  102 ,  104 , one after the other, and exited through the output conduit  106  for a few cycles, until this balancing sequence stops due to inherent losses within the system  100  or losses at an interface between the system  100  and the liquid table  110 . For example, the cycle may be attenuated when the switched valve  128  moves between its two positions, as liquid may transitionally flow through both one-way valves  122  and  126  at the same time. The two liquid level detectors  132 ,  134  may eventually both signal low liquid levels to the controller  130 . At that time, the controller  130  closes the regulating vale  118  and commands renewed gas aspiration at the gas valve  144 , thereby restarting the system  100 . 
     Those of ordinary skill in the art will readily appreciate that the system  100  requires some modest energy input in order to maintain its operation. Energy may be input into the system  100 , upon starting or restarting phases, by way of gas aspiration at the gas valve  144 . In an embodiment, the system  100  may further comprise a gas pressure detector  145 , operably connected to the controller  130 . The gas pressure detector  145  monitors an average differential gas pressure, indicative of a difference between a negative pressure within the upper connecting conduit  112  and an atmospheric pressure. The gas pressure detector  145  reports its reading to the controller  130 . The controller  130  may initiate starting or restarting of the system  100  based on a low differential gas pressure signal received from the gas pressure detector  145 . Alternatively, while the balancing sequence is under way, the controller  130  may command some gas aspiration at the gas valve  144  upon a reduced differential gas pressure reading from the gas pressure detector  145 . Compensation for gas or liquid leaks may thus occur without stopping the balancing sequence, thereby providing substantially continuous pumping in the system  100 , without need for frequent restarts. 
     Referring now to  FIG. 2 , there is shown schematic diagram of an exemplary one-way valve. A one-way valve  200  comprises a rubber ring  204  mounted within a frame  210  and a ball  202 , capable of moving on one side of the rubber ring  204 , in the direction shown by the arrow. The rubber ring  204  maintains, on its outer edge  206 , a sealing contact with an internal perimeter of a conduit (not shown) in which it is inserted. An inner edge  208  of the rubber ring  204  sealably connects with the ball  202  when in closed position. The inner edge  208  of the rubber ring  204  hermetically mates with the ball  202  to seal the one-way valve  200 . The rubber ring  204  also serves in absorbing shocks when coming in contact with the ball  202 . The frame  210  maintains the ball  202  within proximity of the rubber ring  204  when in open position. In a vertically oriented conduit such as the liquid columns  102 ,  104  of  FIG. 1 , in which liquid is only allowed to flow upwards, gravity and/or liquid pressure above the one-way valve  200  may return the ball  202  in the closed position when no liquid flow is present. Still in the particular case of a vertically oriented conduit, the ball  202  may, in an embodiment, have a lesser density than liquid so that it can float upward, allowing an easy liquid flow, unless liquid pressure above the one-way valve  200  forces closing of the valve. For better sealing or for other orientations, a spring  212  may return the ball  202  in closed position, against the rubber ring  204 , in the absence of a liquid flow. 
     Referring back to  FIG. 1 , in an embodiment and in the case of the one-way valves  122 ,  126  located within the actuated conduit  114 , the spring  212  may be calibrated so that the ball  202  remains in closed position, in contact with the rubber ring  204 , while the system  100  is in a starting phase. While gas is being extracted through the gas valve  144 , the net liquid pressure applied on the one-way valves  122 ,  126  is relatively low and springs  212 , in each of these valves, maintain the valves in their closed positions. Liquid pressure within the system  100  reaches equilibrium as soon as the starting phase has ended. One of the one-way valves  122 ,  126 , facing an open side of the switched valve  128 , opens and lets liquid flow through. The other one-way valve is facing a closed side of the switched valve  128  so no liquid may flow through. 
     Liquid exiting from the output conduit  106  of  FIG. 1  may be used for domestic, industrial or agricultural purposes. A variant of the system  100  may be used for energy production.  FIG. 3  shows a schematic diagram of an alternative liquid pumping system coupled to an electric generator. A system  300  is similar to the system  100  of  FIG. 1 , in which an output conduit  306  is connected to a liquid turbine  302 , which is itself connected to an electric generator  304 . The liquid turbine  302  is actuated by liquid flow coming down through the output conduit  306 . The output conduit  306  optionally returns groundwater to the liquid table  110 . This non-limitative embodiment of the system  300  prevents depletion of this natural resource. Other cases may apply wherein liquid may be used for other domestic, industrial or agricultural purposes, in which cases the output conduit  306 , the liquid turbine  302  and the electric generator  304  remain above the ground  108 . Of course, a higher liquid pressure is achieved at the liquid turbine  302  when it is located immediately above the liquid table  110 . 
     Electrical energy consumed by the system  300  is limited to the starting phase, when gas is extracted through the gas valve  144  or when an alternate starting system is in use, save for negligible energy spent in the controller  130 , in the liquid level detectors  132 ,  134 , in the switched valve  128 , and in the regulating valve  118  if applicable. A net energy budget from electricity generated at the electric generator  304  minus the energy spent in the system  300  is positive, much like in the case of a heat pump producing more heat energy than an amount of electrical energy required to drive its compressor. The system  300  extracts natural energy and converts it into electrical energy, much like a windmill does. 
     Those of ordinary skill in the art will realize that the description of the balancing liquid pump and system for pumping liquid are illustrative only and are not intended to be in any way limiting. Other embodiments will readily suggest themselves to such skilled persons having the benefit of this disclosure. Furthermore, the disclosed system can be customized to offer valuable solutions to existing needs and problems of liquid pumping systems and apparatuses. 
     In the interest of clarity, not all of the routine features of the implementations of the balancing liquid pump and system for pumping from a body of liquid are shown and described. It will, of course, be appreciated that in the development of any such actual implementation of the balancing liquid pump and system for pumping liquid, numerous implementation-specific decisions must be made in order to achieve the developer&#39;s specific goals, such as compliance with application-, system- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the field of liquid pumping systems having the benefit of this disclosure. 
     Although the present disclosure has been described hereinabove by way of non-restrictive illustrative embodiments thereof, these embodiments can be modified at will within the scope of the appended claims without departing from the spirit and nature of the present disclosure.