Patent Application
20230078864
The present invention relates to direct air displacement pumping systems for liquids.
Direct 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. 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:
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, electrical, supersonic, etc.) mounted inside the pump body provides the information that the pump is 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 methods.
The float: In this case, a float can slide inside the (vertical) pump body 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 body and sets the air valve to exhaust mode. The pump starts filling with water. The float gradually comes up until it reaches the top end of the pump body and sets the air valve to pressure mode. Compressed air enters the pump 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 body. 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 clean water the servicing intervals are acceptable, but in harsh conditions (salty water, iron bacteria, leachate, grit) they are useless. 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 mounted inside the pump body. 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 fill (exhaust mode) or discharge the water from inside the pump body (pressure mode). As the probes are sensitive, a slight change to the water salinity can change the water conductivity and the pump will not function. If the water is contaminated and oil sits on the probes, they form a film of insulation and the pump will not function. The setup is complicated, as a cable is located downhole and has to 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 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).
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 fork which is mounted inside the pump body, 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 has to be installed downhole and be connected via a 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 body close to the top end. This switch opens/closes a contact when the pump fills. A controller 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 has to be installed downhole and be connected via a waterproof plug to the floating level switch. The floating switch operation can be affected by high salinity water or iron bacteria built up. The electric signal required from the floating switch feedback must be fed through intrinsic safe barriers if it is 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 direct air displacement pump for liquids with a smart controller that overcomes, or at least minimises, the problems associated with the current systems.
With the present invention, there is no need to have any sort of liquid level sensors inside the pump body. All the critical components (sensors, smart controller, air valve, etc) are 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 combination of this pump body design and the smart controller allow us to indirectly monitor the pump state (full or empty) by measuring the airline and discharge line pressures. The smart controller reads data from both pressure sensors (05, 13) and after calculations it changes the air valve (06) state to pressure or exhaust. The pump operation is not affected by any changes of the water salinity, can be used to pump contaminated liquids and can operate in inclined bores.
The smart controller can operate in two modes depending on the application requirements. The operation in each mode can be better understood by explaining the system setup first.
In
According to a first aspect, as shown in
The compressed air passes through a line restriction or orifice (04) and then continues to a larger sized tube. The compressed air is connected to port No1 of a 3-way, 2-position air valve (06). Port No2 of the air valve (06) is connected at the top port of the pump body (11).
The pump body (11) is submersed in liquid (12) and has two ports, the top port and the bottom port. Inside the pump body there is a floating ball which acts as a check valve at the top port when the pump is full of liquid and as a check valve at the bottom port when the pump is empty. The bottom port of the pump serves as both liquid intake and discharge.
When the pump is in exhaust mode (the top port is in atmospheric pressure) the pump body is filled with liquid through the check valve (09); check valve (10) is closed as a result of the head pressure at the discharge line.
When the pump is in pressure mode (the top port is being fed with compressed air) the pump body discharges liquid through the check valve (10); check valve (09) is closed as a result of high pressure at the discharge line.
The liquid in the discharge line (continuous line) is fed to the customer network (or free flow) through a line restriction or orifice (14). The discharge line pressure just before the restriction (14) is being monitored continuously by the pressure sensor (13).
According to a second aspect, as shown in
The compressed air passes through a line restriction or orifice (04) and then continues to a larger sized tube. The pressure sensor (05) continuously measures the airline pressure at that point. The compressed air is connected to port No1 of a 3-way, 2-position air valve (06). Port No2 of the air valve (06) is connected at the top port of the pump body (11).
The pump body (11) is submersed in liquid (12) and has two ports, the top port and the bottom port. Inside the pump body there is a floating ball which acts as a check valve at the top port when the pump is full of liquid and as a check valve at the bottom port when the pump is empty. The bottom port of the pump serves as both liquid intake and discharge.
When the pump is in exhaust mode (the top port is in atmospheric pressure) the pump body is filled with liquid through the check valve (09); check valve (10) is closed as a result of the head pressure at the discharge line.
When the pump is in pressure mode (the top port is being fed with compressed air) the pump body discharges liquid through the check valve (10); check valve (09) is closed as a result of high pressure at the discharge line.
The liquid in the discharge line (continuous line) is fed to the customer network (or free flow) through a line restriction or orifice (14). The discharge line pressure just before the restriction (14) is being monitored continuously by the pressure sensor (13).
According to a third aspect, as shown in
One branch of the compressed air line (dotted line) passes through a line restriction or orifice (04). The pressure sensor (05) continuously measures the airline pressure at that point. This compressed air line is connected to the bottom port of the pump body (11).
The second branch of the compressed air line (dashed line) is connected to the port No1 of a 3-way, 2-position air valve (06). The port No2 of the air valve (06) is connected to the top port of the pump body (11).
The pump body (11) is submersed in liquid (12) and has two ports, the top port and the bottom port. Inside the pump body there is a floating ball which acts as a check valve at the top port when the pump is full of liquid and as a check valve at the bottom port when the pump is empty. The bottom port of the pump serves as both liquid intake and discharge.
When the pump is in exhaust mode (the top port is in atmospheric pressure) the pump body is filled with liquid through the check valve (09); check valve (10) is closed as a result of the head pressure at the discharge line.
When the pump is in pressure mode (the top port is being fed with compressed air) the pump body discharges liquid through the check valve (10); check valve (09) is closed as a result of high pressure at the discharge line.
The liquid in the discharge line (continuous line) is fed to the customer network (or free flow) through a line restriction or orifice (14). The discharge line pressure just before the restriction (14) is being monitored continuously by the pressure sensor (13).
According to the first aspect, (
We turn on the smart controller. The smart controller gets a reading of the pressure sensor (13) and then sends a command to the air valve (06). The air valve (06) state goes to pressure mode and a slug of air rushes downhole (dashed line). As a result of the restriction (04), it takes some time to the indication of the pressure sensor (13) to increase, as indicated in
change to the liquid level (12), blockage to the foot valve (09), bacteria build up in the pump inner body (11), change in the liquid viscosity, etc. As the pump starts discharging liquid, the pressure sensor (13) indication rises as a result of the restriction (14), even with a free flow. As the pump vessel empties, the floating ball drops down until it reaches the bottom end and plugs the pump bottom port. At this time, we notice a drop at the pressure sensor (13) indication (pump is empty). The controller sends a command to the air valve (06) and changes its state to exhaust mode (pump is filling). The controller waits for x amount of seconds (as calculated above) to fill the pump and then the same process is repeated.
The first inventive step is the way the smart controller of the first aspect (
According to the second aspect, (
We turn on the smart controller. The smart controller gets a reading of the pressure sensor (05) and then sends a command to the air valve (06). The air valve (06) state goes to pressure mode and a slug of air rushes downhole (dashed line). As a result of the restriction (04), the indication of the pressure sensor (05) drops and then increases, as indicated in
The second inventive step is the way the smart controller of the second aspect (
According to the third aspect, (
Compressed air is trying to go downhole (dotted line), but as the pump body is full of liquid and the floating ball has reached the top end, the top port has been blocked and the pressure sensor (05) indicates the airline pressure as set up by the pressure regulator (03).
We turn on the smart controller. The smart controller sends a command to the air valve (06). The air valve (06) state goes to pressure mode and compressed air rushes downhole (dashed line). The pump starts discharging liquid and the pressure sensor (13) indication rises as a result of the restriction (14), even with a free flow. As the pump vessel empties, the floating ball drops down until it reaches the bottom end and plugs the pump bottom port. At this time, we notice a drop at the pressure sensor (13) indication (pump is empty). The controller sends a command to the air valve (06) and changes its state to exhaust mode (pump is filling).
During filling, a tiny amount of compressed air is flowing through the line restriction (04) (dotted line), enters the pump body (11) from the bottom port, exits the pump body (11) from the top port, flows towards the air valve (06) (dashed line) and finally escapes to the atmosphere through the exhaust (07). The amount of pressure drawn in the dotted airline branch is proportional to the level of liquid build inside the pump body (11). However, as the floating ball inside the pump body (11) reaches the top end, it blocks the top port and the pressure sensor (05) indication continues to increase until it reaches the pressure regulator (03) set pressure.
As a result of this pressure increase, the smart controller senses that the pump body is full of liquid and sends a command to the air valve (06) to change to pressure mode and then the same process is repeated.
The third inventive step is the way the dotted airline (known also as a bubbler line) informs the smart controller of the liquid level inside the pump body. This bubbler line is mounted outside the pump body and provides information on the liquid level inside the pump body. In conjuction with the floating ball inside the pump body (11), when the pump gets full and the floating ball reaches the top end of the pump body it blocks the top port. The pressure indication of the pressure sensor (05) is no more proportional to the liquid level inside the pump body (11), but ramps up until reaches the maximum airline pressure as set up by the pressure regulator (03). This ramp up of the pressure indication of the pressure sensor (05) provides enough information to the smart controller to sense that the pump body is full and it is time to change the air valve (06) to pressure state.
The fourth inventive step is the way the smart controller of all the above aspects can estimate when the pump is empty. Let's assume that the air valve (06) is in exhaust mode and the pump body (11) is filling with liquid. The indication of the pressure sensor (13) equals the static head pressure after that point (which can be the atmospheric pressure if we have free flow). As the air valve (06) state changes to pressure mode the pump starts discharging liquid through the discharge line (solid line). If we have a free flow, the indication of the pressure sensor (13) increases as a result of the line restriction (14) as shown in
