Air operated pumping system for liquids

Abstract

Abstract An air operated pumping system for liquids, comprising of an air displacement submersible pump, which does not require a liquid level sensor mounted inside the pump vessel. It includes a weighing scale mounted above ground surface which is able to identify the pump vessel status (full or empty) by measuring the weight of the pump. It also includes a controlling device which controls the pump cycling (filling or emptying) by using the information provided from the above mentioned weighing scale. 5 Abstract An air operated pumping system for liquids, comprising of an air displacement submersible pump, which does not require a liquid level sensor mounted inside the pump vessel. It includes a weighing scale mounted above ground surface which is able 5 to identify the pump vessel status (full or empty) by measuring the weight of the pump. It also includes a controlling device which controls the pump cycling (filling or emptying) by using the information provided from the above mentioned weighing scale. 20 25 20 23 71 02 A pr 2 02 5 2 0 2 5 2 0 2 3 7 1 0 2 A p r 2 0 2 5 1 / 1 Figure 1 1 / 1 3 P PT1 2 4 A A 5 6 13 7 12 11 10 8 9 Figure 1 20 25 20 23 71 02 A pr 2 02 5 0 2 A p r 2 0 2 5 P T 2 4 2 0 2 5 2 0 2 3 7 1 5 6 7 1 1 1 0 8 9

Description

Field of the invention The present invention relates to air displacement pumping systems for liquids. 5                          Background of the invention Air displacement pumps are mainly submersible pumps for pollution recovery, dewatering and pumping liquids from wells, bores, sumps, ponds, pits and building foundations. References on how to build such a pump can be found in the book entitled, “Tools for mining - Techniques and processes for small scale mining”, by M. 10 Priester, T. Hentschel and B. Benthin, which was published in 1993 and includes a description of this particular pump (section 4.1) based on C. H. Fritzsche’s work entitled, “Landtechnik Weichenstephan” (circa 1960). Section 4.1 of Priester et.al. states that “the air displacement pump as per C. H. Fritzsche, consists of a displacement chamber with two check valves: 15 “An intake check valve and a discharge check valve with an uptake on the delivery side of the pump. The intake and discharge are located at the bottom of the pump housing, where a stand pipe is serving as the outlet. A compressed airline, externally controlled by means of a three-way cock, is connected to the pump chamber. Water from the bore / sump flows through the intake check valve into the 20 pump chamber. When the pump chamber is full, the three-way cock is turned to allow compressed air to flow into the chamber. The intake check valve closes and the discharge check valve starts to open. The compressed air drives the water out through the standpipe, outlet check valve and uptake pipe. After all the water has been discharged, the three-way cock is switched open, the air pressure drops, the 25 outlet check valve closes, the intake check valve begins to open and water again flows into the pump chamber.” The existing products on the market and their problems In order to automate the pumping process different methods of control have been employed by different manufacturers. In all cases, a type of sensor (mechanical, 30 electrical, supersonic, etc.) mounted inside the pump body provides the information that 2025202371   02 Apr 2025 the pump ivessel s empty or full, so the air valve can change state (pressure - exhaust). This sensor requires maintenance after a certain period depending on the water quality (salinity, acidity, bacteria build up, etc) which is expensive and time consuming (the pump has to be removed from the bore). Let’s take a quick look at some of the existing 5 methods. The float: In this case, a float can slide inside the (vertical) pump vessel and is connected to an air valve with means of levers, latches, etc. When the pump is empty, the float sits at the bottom end of the pump vessel and sets the air valve to exhaust mode. The pump starts filling with water. The float gradually comes up until it reaches 10 the top end of the pump vessel and sets the air valve to pressure mode. Compressed air enters the pump vessel and as a result, the pump starts discharging water until empty. The float gradually drops down until it returns to the bottom of the pump vessel. The air valve state changes to exhaust and the pump starts filling with water. The sliding float, the latching mechanism and the air valve pistons are all working under water. In 15 clean water the servicing intervals are acceptable, but in harsh conditions (salty water, iron bacteria, leachate, grit) they become out of order after few cycles. If the bore is inclined (as in most landfill sites), the float becomes ineffective and the pump does not cycle. The probes: In this case, three probes (ground probe, top probe, bottom probe) are 20 mounted inside the pump vessel. These probes provide a signal (pump is full, pump is empty) to a controller usually mounted above ground. This controller changes the air valve state in order to let the pump vessel fill (exhaust mode) or discharge the water from inside the pump vessel (pressure mode). As the probe signal must be sensitive, a slight change to the water salinity can change the water conductivity and the pump will 25 not function. If the water is contaminated and oil sits on the probes, they form a film of insulation reducing their conductivity and the pump will not function. The installation is complicated, as an electric cable is running downhole and must be connected via a waterproof plug to the probes which are mounted in a high pressure area. A tiny leak is enough to short circuit the conductors and put the pump out of order. The electric signal 30 required for the probes operation must be fed through intrinsic safe barriers if the intention is to use it in explosive environments (e.g. leachate wells). 2025202371   02 Apr 2025 The dual timer: In this case, the air valve state is switching based on a preset timer program (filling time, emptying time). This is an open loop system and has poor efficiency as it can lead to high compressed air consumption per unit of delivered water. The tuning fork level switch: An electronic circuit continuously stimulates the tuning 5 fork which is mounted inside the pump vessel, causing it to mechanically vibrate. When the prongs of the fork contact anything with substantial mass (water in our case), the resonant frequency of the fork decreases. The circuit detects this frequency change and indicates the presence of mass contacting the fork. This is an expensive solution as it uses advanced electronics. A cable must be installed downhole and be connected via a 10 waterproof plug to the tuning fork. The tunning fork can also be affected by iron bacteria build-up and must be fed through intrinsic safe barriers if it is to be used in explosive environments (e.g. leachate wells). The floating level switch: A floating switch is mounted inside the pump vessel close to the top end. This switch opens / closes a contact when the pump fills. A controller 15 usually mounted above ground detects the signal from the floating level switch and sets the air valve state to pressure mode. The pump starts discharging. As the pump emptying time is unknown it works on a timer basis. With this solution a cable must be installed downhole and connected via a waterproof plug to the floating switch. The floating switch operation can be affected by high salinity water or iron bacteria built up. 20 The electric signal required from the floating switch feedback must be fed through intrinsic safe barriers if it is intended to be used in explosive environments (e.g. leachate wells). If the bore is inclined (as in most landfill sites), the float becomes ineffective and the pump will not cycle. As such, the desired object of the invention is to provide an alternate system of air 25 displacement pump for liquids with a controller that overcomes, or at least minimises, the problems associated with the current systems. Brief description of the invention With the present invention, there is no need to have any sort of liquid level sensors inside the pump vessel. All the critical components (sensor, controller, air valve, etc) are 2025202371   02 Apr 2025 mounted above ground, making maintenance and servicing easy and at the same time, the pump vessel becomes more reliable as it contains less components that could fail. The pump state (full or empty) can be monitored by measuring the pump weight with a weighing scale. The controller reads the weight and changes the air valve state to 5 pressure or exhaust as required. The pump operation is not affected by any changes of the water salinity and can be used to pump contaminated liquids. The invention may be better understood with reference to the illustrations of embodiments of the invention. 10                         Detailed description of the drawings Figure 1 is a schematic representation of the invention. An air compressor (1) supplies compressed air to the network. The compressed air is connected to port (P) of a 3-way, 2-position air valve (2). Port (A) of the air valve (2) is connected at the top port of the pump vessel (7) through the air line (5). Port (T) of the air valve (2) is exhausting to the 15 atmosphere. When port (A) of the air valve (2) is connected to port (P) we can say that the valve is in pressure mode. When port (A) of the air valve (2) is connected to port (T) we can say that the valve is in exhaust mode. The pump vessel (7) is submersed in liquid (9) inside the sump or bore casing (8) and has two ports, the top port and the bottom port. The top port of the pump vessel (7) 20 serves as both air intake and discharge. The bottom port of the pump vessel (7) serves as both liquid intake and discharge. The pump is comprising of the pump vesel (7), the intake check valve (11) and the discharge line check valve (12). The pump is suspended from the weighing scale (4) through a suspending line (6). The liquid can enter the pump vessel through the liquid 25 intake (10) and then passing through the intake check valve (11). The liquid can exit the pump vessel through the discharge line check valve (12) and then ends at the discharge line (13). The weighing scale (4) is weighing the pump weight through the suspending line (6) and forwards this information to the controller (3) through electric signal. The weighing scale 30 (4) indication has a minimum value when the pump vessel (7) is empty and a maximum value when the pump vessel (7) is full of liquid. The controller (3) is monitoring the weighing scale (4) indication and changes the air valve (2) position through electric signal as required. 2025202371   02 Apr 2025 Detailed description of the invention According to figure 1, we assume that the pump vessel (7) is submersed in the liquid (9) and the air valve (2) is in exhaust mode. The pressure inside the pump vessel (7) is lower than the liquid (9) pressure and as a result the liquid (9) is filling the pump vessel 5 (7) flowing through the intake (10) and the check valve (11). The discharge line check valve (12) is closed as a result of the head pressure at the discharge line. The weighing scale (4) indication is gradually increasing as a result of the increasing tension at the suspending line (6). The controller (3) is continiously monitoring the weighing scale (4) indication which reaches the maximum value when the pump vessel (7) is full of liquid. 10 At this moment the controller (3) changes the air valve (2) state from exhaust to pressure. Compressed air is fed from the air valve port (A) to the air line (5) and to the pump vessel (7) through it’s top port. When the pressure inside the pump vessel (7) becomes greater than the pressure of the liquid (9), the intake check valve (11) is closing and no liquid can flow in either direction. When the pressure inside the pump 15 vessel becomes greater than the head pressure at the discharge line (13), the discharge line check valve (12) opens, allowing liquid to flow through the discharge line. The pump vessel (7) is gradually emptying, the pump becomes lighter, the tension at the suspending line (6) is decreasing and as a result, the weighing scale (4) indication is decreasing too. When the weighing scale (4) indication reaches the minimum value, the 20 pump vessel (7) is empty. At this moment the controller (3) changes the air valve (2) state from pressure to exhaust. The compressed air accumulated inside the pump vessel (7) feds to the atmosphere through the air valve (2) port (T). When the pressure inside the pump vessel (7) drops below the liquid (9) pressure, the liquid starts filling the pump and the same process is repeated. 25 The inventive step is the way the controller (3) can identify when the pump is empty or full. As there is no sensor mounted inside the pump body, the weighing scale (4) indication is used by the controller (3) to identify the pump vessel (7) status and drive the air valve (2) as required to make the pump cycle. Minimum weight indication means the pump vessel (7) is empty. Maximum weight indication means the pump vessel (7) is 30 full. The difference between the minimum and maximum weight idications equals the pump vessel displacement.

Claims

1. An air operated pumping system for liquids comprising:A gas operated submersible pump, submersed in the liquid which we want to pump, which is usually expected to be underground, including5 an elongated liquid—retaining vessel having a top end and a bottom end, a gas entry port at the top end allowing the gas to enter or exit the pump vessel, a liquid entry port at the bottom end including a check valve allowing liquid to enter the pump vessel with gravity when the pump vessel is in exhaust mode and preventing liquid to exit the pump vessel when the pump vessel is in pressure mode,10 a liquid discharge port at the bottom end including a check valve, allowing the liquid to flow from the pump vessel towards the discharge line when the pump vessel is in pressure mode and preventing the discharged liquid to flow from the discharge line towards the pump vessel when the pump vessel is in exhaust mode.A high pressure conduit said gas line, with the first end connected to the air valve and 15 the second end connected to the pump gas entry port.A control apparatus, usually located above ground, for selectively actuating and deactuating the air valve, said the controller, including an electronic device e.g. a smart relay, loaded with a data logic suitable to decide when the pump has to be in exhaust or pressure mode, depending on the input readings of the weighing scale connected to it, 20 an analog weighing scale from which the submersible pump is hanging with means of a suspending line and the analog signal port connected to the smart relay input, a 3-way 2-position valve with the electrical port(s) connected to the smart relay output(s), the first hydraulic port connected to the main compressed gas supply, the second hydraulic port connected to the gas line and the third hydraulic port not25 connected and as such being able to vent any compressed gas in the environment.

2. An air operated pumping system as claimed in claim 1, the controller including a programmable logic controller (PLC) instead of a smart relay.

3. An air operated pumping system as claimed in claim 1, the controller including an electronic circuit based on a PROM, EPROM or EEPROM processor instead of a smart 30 relay.

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