Pneumatic energy harvesting device

Abstract

The invention relates to a pneumatic energy harvesting device, comprising a closed circuit of liquid, with an upper chamber (1) from the base of which extend one or more descending tubes (2), which are angled to connect to one or more ascending tubes (3) connected to the upper chamber (1), above the base, a gas injector (4) being arranged in each ascending tube (3), and one or more turbines (6) being arranged in each descending tube (2) or elbow. The upper chamber (1) may comprise a gas suction conduit (5). Ideally, the ascending tube (3) has a cross-section that increases with height.

Description

[0001] DESCRIPTION

[0002] PNEUMATIC ENERGY HARNESSING DEVICE

[0003] TECHNICAL SECTOR

[0004] This application relates to a device for harnessing energy stored or generated by a compressor in the form of pressurized air or gases.

[0005] STATE OF THE ART

[0006] The state of the art is known as "airlift" pumps, developed by Cari Loscher. These pumps introduce a gas into a fluid, causing it to drop in density and rise through a pipe, also carried by the bubbles. This system has some disadvantages but requires very little energy to operate. The most common uses of this pump are wastewater treatment plants, the extraction of liquid hydrocarbons in the petroleum industry, well drilling and mineral extraction from the ocean, as well as in aquaculture, where large volumes of water need to be moved at minimal cost.

[0007] In current applications, the riser pipe discharges the liquid / gas mixture at atmospheric pressure, with its pressure range from atmospheric at the discharge to hydrostatic at the gas injection point.

[0008] On the other hand, compressed air is safe, easy to store and transport, and can be used whenever necessary. Its collection and release do not pose environmental or pollution problems, nor do they pose explosion accidents due to chemical reactions or flames.

[0009] The applicant is not aware of any device similar to the invention.

[0010] BRIEF EXPLANATION OF THE INVENTION

[0011] The invention relates to a pneumatic energy harvesting device according to the claims. Its embodiments improve and solve technical problems. In open-cycle airlifts, the gas compressor only provides the excess pressure necessary to overcome the hydrostatic pressure at the injection point. The airlift's operating requirements require the liquid to be released into other locations, such as tanks, reservoirs, ponds, etc., usually at atmospheric pressure.

[0012] To this end, the pneumatic energy harnessing device comprises a closed fluid circuit, with an upper chamber from the bottom of which one or more downpipes extend, which are bent and connect to one or more riser pipes. The riser pipes are in turn connected to the upper chamber above the bottom. Each riser pipe has a gas injector. The device has one or more turbines in each downpipe or bend.

[0013] The gas pressure required to overcome the hydrostatic pressure at the injection point is determined by the pressure exerted on the liquid column, which, in an open cycle, is atmospheric. However, when operating in a closed cycle, the pressure on the liquid column can be adjusted as desired: if the pressure in the discharge zone, in the upper chamber, is lower than atmospheric, then the pressure at the injection point can be lower, since the negative pressure is applied to the entire liquid contained in the closed circuit (Pascal's laws).

[0014] The most important thing is the pressure gradient between the upper chamber and the injection point, which will determine the maximum height of the liquid column, the efficiency of the compressor and the flow rate of recirculated liquid per m 3of gas. A difference of 100 mbar is equivalent, in the case of water, to 1 m in the liquid column. A gradient of 400 mbar would be equivalent to a column 4 m high.

[0015] Therefore, it is highly advantageous for the upper chamber to have a gas suction duct.

[0016] In one embodiment, the upper chamber is connected to one or more downcomers connected to a lower chamber from which the risers emerge. That is, the elbow is replaced by a lower chamber shared by one or more downcomers. In this case, the turbine will be located in the downcomers or at the connection to the lower chamber.

[0017] Preferably, the riser tube has a cross-section that increases in height. The remainder of this specification describes other specific embodiments.

[0018] DESCRIPTION OF THE FIGURES

[0019] For a better understanding of the invention, a section of drawings is included containing the following:

[0020] Figure 1: Diagram of an example of implementation.

[0021] Figure 2: View of a second embodiment.

[0022] Figure 3: Detail of the riser tubes, the upper chamber and the lower chamber in the embodiment of figure 2.

[0023] Figure 4: Front view of one of the modules of the part shown in Figure 3.

[0024] Figure 5: View of another embodiment where the turbine type has been changed.

[0025] Figure 6: Section of an example of an implementation where the turbine is at a remote point.

[0026] Figure 7: View of another embodiment with a turbine similar to Figure 5.

[0027] MODES OF EMBODIMENT OF THE INVENTION

[0028] Below, a brief description is given of an embodiment of the invention, as an illustrative and non-limiting example thereof.

[0029] The embodiment shown in the figures comprises a closed circuit formed by an upper chamber (1 ) from the bottom of which a downcomer (2) extends, which is bent to connect to a riser (3). The riser (3) is introduced into the upper chamber (1 ) with its mouth above the level of the bottom. That is to say, the mouth of the downcomer (2) is at a lower level than the mouth of the riser (3). Furthermore, in use the mouth of the riser (3) will be set above the liquid level in the upper chamber (1 ) to avoid backflow. The shape of the upper chamber (1 ) may be a “V” with the mouth of the riser (3) on the upper sides of the “V”. At one point in the riser (3) there is a gas injector (4) from a pressurised gas source. Normally this will be a compressed gas tank, but it may be a compressor. This causes the “airlift” pump to operate in the riser.When the mixture reaches the upper chamber (1), the gas and liquid are separated.

[0030] The upper chamber (1) is connected to a suction line (5) that removes the accumulated gas. This suction line (5) allows the pressure in the upper chamber to be lower than atmospheric. Consequently, the hydrostatic pressure in the upper layer of liquid is lower than atmospheric. This is a closed gas / liquid circuit operating at subatmospheric pressure. The remaining pressures can be calculated according to Bernoulli's theorem!

[0031] The suction tube (5) can be connected to the compressor (8) that feeds the injector (4), regardless of how the compressor (8) moves.

[0032] A turbine (6) is arranged at one point in the circuit to take advantage of the movement of the liquid. The turbine (6) is preferably arranged in the downcomer (2) or in the lower elbow, so that it works with the liquid without gas. The turbine can be of any type, for example Kaplan or axial vortex turbines, Pelton, Francis... In any case, it can be at a remote point, provided that the branches are arranged in the downcomer (2) or in the lower elbow (Figure 6).

[0033] The riser tube (3) can be cylindrical, prismatic, or even rectangular, but preferably has a section that increases in height. Thus, the upper opening has a larger section than the lower part.

[0034] It should be noted that the device may comprise any number of tubes (2,3) forming a closed cycle and reaching the same upper chamber (1). The downpipes (2) may be connected to a lower chamber (7) from which the riser tubes (3) emerge or directly to a riser tube (3). In Figure 2, a single downpipe (2) and several riser tubes (3) are arranged to reduce losses.

[0035] This device offers significant savings in external compressed gas, compared to the large volume of gas required by current technologies for energy recovery contained in, for example, compressed air, liquid air, or other liquefied gases. Furthermore, other technologies have very complex technical requirements, which translates into a risk of failure and high costs. This is because the external compressed gas input in the invention is provided at very low pressure, just enough to overcome the absolute hydrostatic pressure and relative flow rate.

Claims

CLAIMS 1- Device for harnessing pneumatic energy, characterized in that it comprises a closed liquid circuit, with an upper chamber (1) from the bottom of which one or more downpipes (2) start, which are bent to connect with one or more riser pipes (3) connected to the upper chamber (1) above the bottom, having a gas injector (4) in each riser pipe (3), and one or more turbines (6) in each downpipe (2) or elbow. 2- Device for harnessing pneumatic energy, according to claim 1, characterized in that the upper chamber (1) has a gas suction duct (5). 3- Device for harnessing pneumatic energy, according to claim 1, characterized in that the upper chamber (1) is connected to one or more downpipes (2) connected to a lower chamber from which the rising pipes (3) emerge. 4- Device for harnessing pneumatic energy, according to claim 1, characterized in that the rising tube (3) has a section that increases in height.

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