Field of the Invention

The present invention concerns a steam-driven water pump of the kind indicated in the preamble of claim 1.

Background of the Invention

In principle, the invention originates from a pump envisioned and described by the Englishman Thomas Sawery in 1702. The pump action is achieved by utilising the interaction between the steam pressure for performing the pump stroke and condensation of the steam (formation of vacuum) for filling the pump. Thomas Sawery developed the pump primarily for emptying coal mines in England of water. After each pump stroke, the pump housing was poured over with cold water with the object of condensing the steam and forming the required vacuum - suction underpressure.

US patent 943 911 discloses a steam and vacuum pump including a pump chamber with inlet and outlet connections which via check valves are connected with the pump chamber, a steam generator, a steam pipe connection connecting the steam generator with the pump chamber, a water conduit supplying water to the generator and automatic means for intermittently feeding a certain amount of water - less than the volume content of the generator - with the object of immediately converting the entire amount of water into steam.

Object of the Invention

On that background it is the object of the invention to indicate a new and improved water pump of the type indicated in the introduction where the function of the pump has been optimised according to modern techniques and conditions, and where the number of possible applications of the pump has been substantially increased.

Description of the Invention

The steam-driven water pump according to the invention . is peculiar in that the discharge pipe originates from a lower part of the pump chamber or an upper part of the access connection, and that the pump chamber has a lower steam/water trap having a flow connection opening into the pump chamber as well as a flow connection opening into the discharge pipe, as the steam/water trap is connected with a riser connection which is preferably arranged inside the discharge pipe.

By means of simple technical measures it is achieved that the operation of the pump can be optimised according to modern techniques and materials and that the number of possible applications of the pump can be substantially increased. The particular effect of the pump relies on the short-circuiting taking place when the steam via the steam/water trap encounters the cold water and is condensed (absorbed in the cold water) because of the short-circuiting between the pump chamber and the discharge pipe. This function is supported by the fact that the density of the steam is extremely lower than the density of water, i.e. the steam will try to escape upwards via the short-circuit connection through the water in the discharge pipe.

In other words, the U-pipe alternates between acting as a short-circuit and as a water trap. With the intention of enabling minimising the external dimensions of the pump simultaneously with having an optimal pump chamber volume, it may be advantageous that the water pump according to the invention is designed such that it includes a separate condenser connected with the discharge pipe and which is disposed above the pump chamber. By separating the condenser from the pump chamber and the discharge pipe, possible optimisation of the pump function is improved and possible application of various materials for pump chamber, discharge pipe and condenser, respectively, is enabled.

Minimising the outer diameter of the pump is important in the cases where the pump is to be lowered into and operate in standard well pipes which have relatively small diameter. In those cases it will be desirable to design the pump such that the length of the pump chamber is considerably longer than the diameter of the pump. If the pump is to be lowered into a well boring and function as a submersible pump, the length of the pump will typically be 15-25 times as long as the diameter of the pump. The water pump according to the invention is suitably designed such that the discharge pipe extends up through the pump chamber and coaxially therewith. Alternatively, the water pump according to the invention is designed such that the discharge pipe extends up through the pump chamber spaced apart from the centre thereof.

In both cases it will be possible to minimise the outer diameter of the water pump, i.e. optimising for installation in a narrow well boring.

Another possibility will be to dispose the discharge pipe or the U-pipe, or both the discharge pipe and the U-pipe, outside the pump chamber. With the object of rapidly forming a hot, thin layer of water for counteracting condensation of the incoming steam (steam piston) in the pump chamber, it may be expedient if the steam-driven water pump according to the invention is designed such that at the top of the pump chamber there is arranged a diffuser plate for distributing the incoming steam across approximately the whole cross-sectional area of the pump chamber so that the desired pump action occurs rapidly.

The steam-driven water pump according to the invention can alternatively be designed for the same purpose such that at the top of the pump chamber there is arranged an annular distribution chamber with steam nozzles.

Another option, which is particularly suited for pump chambers with larger diameters, is to design the steam-driven water pump according to the invention such that a predominantly disc-shaped floating body which acts as a pump piston when steam is introduced over it is arranged internally of the pump chamber

With the object of avoiding too large amounts of steam being used for heating the pump chamber after being introduced at the top of the pump chamber, it can be advantageous that at least an uppermost part of the wall of the pump chamber consists of material with small thermal conductivity and heat capacity. The steam-driven water pump according to the invention is suitably designed such that it is dimensioned to be lowered as a unit into a conventional well boring, e.g. with a diameter of 160 mm. According to an alternative embodiment, the water pump according to the invention can be designed with a pump chamber with larger diameter and adapted to be erected or mounted upon the ground - e.g. at a lake or on a river bank - and provided with a hose-like access connection with bottom valve and suction branch for insertion either into a bored hole in the ground or into a lake or a stream. Description of the Drawing

The invention is explained more closely in the following with reference to the drawing, on which:

Fig. 1 shows a plan view of an embodiment of pump according to the invention in the form of a sectional drawing;

Fig. 2 shows a plan view of a second embodiment of pump according to the invention in the form of a predominantly sectional drawing; Fig. 3 shows a plan view of a further embodiment of pump according to the invention in the form of a predominantly sectional drawing;

Fig. 4 shows a plan view of a watering system with a steam-driven water pump according to the invention;

Figs. 5-10 show views for describing the function of a steam-driven water pump according to the invention;

Fig. 1 1 shows a plan view of an alternative embodiment of a pump according to the invention;

Fig. 12 shows a perspective view of a vacuum pipe solar panel;

Fig. 13 shows a perspective view of a modern parabolic solar collector; Fig. 14 shows an exploded perspective view of a pump according to the invention, cf. the embodiments shown in Figs. 2 or 3;

Fig. 15 shows a sectionalised view of a pump according to the invention, cf. the embodiment shown in Fig. 2; and

Fig. 16 shows a plan view of an alternative embodiment of a pump according to the invention.

Detailed Description of Embodiments of the Invention

The embodiment of a steam-driven water pump 2 according to the invention shown in Fig. 1 includes a pump chamber 4 with a volume content of the magnitude 20-50 1, preferably about 30 1, and at the top of the pump chamber 4 there is connected a steam feeding pipe 6 with a steam valve 8 such that steam can be supplied from a not shown steam supply. At the bottom, the pump chamber 4 is connected with a suction pipe 10 which lowermost has a bottom valve 12 and a suction branch 14 with a filter strainer 16 sothat contaminants do not get access to the suction pipe 10 together with the water. Under the pump chamber 4, the suction pipe 10 is connected with a discharge pipe 18 by a bend 20, as the discharge pipe 18 extends up through the pump chamber 4 while spaced apart from centre axis of the chamber.

At the top of the discharge pipe 18 is mounted a top valve 22 which opens when the steam pressure is greater than the pressure required to drive the water out of the pump chamber, that is determined by the actual head required during the pump stroke for drawing the water out at the ground level. Internally of the pump chamber 4 is arranged a U-shaped steam/water trap 24 with a riser pipe 26 which is disposed inside the pump chamber 4, and riser pipe 28 disposed inside the discharge pipe 18.

Figs. 2, 14 and 15 show a second embodiment of a steam-driven water pump 30 with a pump chamber 32 which is connected at the bottom with a suction pipe 10 which lowermost has a bottom valve 12 and a suction branch 14 with a filter strainer 16. An annular distributor 15 is. arranged at the top of the pump chamber 32 with a number of steam nozzles 17 which have the task of providing steam supplied through a steam supply pipe 6 with associated steam valve 8 to be evenly distributed internally of the pump chamber 32 as a disc-shaped steam piston.

The pump chamber 32 is made of a material with small thermal conductivity, for example of a suitable plastic material. This plastic material can e.g. be a plastic material where core parts of the wall consist of foamed plastic, e.g. integral foam, meaning a non-waterabsorbing core with a closed cell structure.

A discharge pipe 34 is arranged at the centre of the pump chamber 32 coaxially therewith. At the top, the discharge pipe 34 is connected with a cylindrical condenser 36 which in turn is connected at the top with a secondary discharge pipe 38 with a check valve (top valve) 40. Internally of the pump chamber 32, a steam/water trap 42 in the form of a angularly bent pipe section 44 is arranged, mounted at the side of he discharge pipe 34. The pipe section 44 is connected with a short hose 46 disposed inside the pump chamber 32, and a longer hose 48 disposed inside the discharge pipe 34.

Unlike the pump chamber 32, which as mentioned is made of a plastic material with small thermal conductivity, the condenser 36 can be made of a material with good thermal conductivity, e.g. of copper.

The embodiment of a steam-driven water pump 50 shown in Fig. 3 is largely designed as the above described water pump 30, only that here a steam/water trap is constituted by an angularly bent pipe section 45, one end of which is connected with a longer hose piece 48 disposed inside the discharge pipe 34, whereas an opposite end of the pipe section 45 is connected with a thin-walled riser pipe 47 surrounding a lower part of the discharge pipe 34, i.e. disposed inside the pump chamber 32 and connected therewith.

Fig. 4 shows a watering system 52 comprising a steam-driven water pump 54 which is mounted in a common vertical well boring 56 at a depth of 60 m, for example. In principle, the water pump can operate at a pressure of the magnitude 10-12 bars, corresponding to a theoretical maximum head of 100-120 m.

The water pump 54 is supplied with steam from a steam storage tank 58 with built-in heat exchanger which is operationally connected with a vacuum pipe solar panel 60. The pumped water is conducted to a water tank 62 and from there to a watering trough 64. The shown vacuum pipe solar panel 60 can be substituted by another source of energy for steam production, e.g. a parabolic solar collector (Fig. 13). The pumped water can of course be used as drinking water for humans, livestock, flooding or irrigation as well. This use of the water can take place directly from the pump or via collection in a hollow/reservoir or the water tank 62.

Operation of the water pump 54 will now be described with reference to Figs. 5-10, where Fig. 5 shows the situation immediately before a pump stroke, i.e. where pump chamber 32 is filled with water, At the top of the pump chamber 32 there is arranged a plate-shaped diffusor 9 which as described above has the task of distributing the steam evenly across the entire cross-section and forming a steam piston inside the pump chamber 32.

Fig. 6 illustrates the situation where the pump stroke is commenced, i.e. where steam valve 8 and top valve 20 are open while bottom valve 12 is closed. Top valve 40 is a check valve which opens automatically when the pressure in the pump chamber 32 is high enough to press the water out of the pump chamber 32.

As the steam displaces the water downwards in the pump chamber 32, the water will flow upwards through the discharge pipe 34 and further up through condenser 36 and the secondary discharge pipe 38, e.g. to water tank 62 (Fig. 4). In Fig. 7, the pump stroke is about to be finished and the steam has displaced almost all water and has reached the bottom of the pump chamber 32, i.e. it is opposite steam/water trap 42 such that a short-circuiting takes place, where the steam can rise up through the discharge pipe 34 and be condensed by the cold water. The pressure drops in the pump chamber 32, and vacuum is formed. The top valve 40 closes hereby since the pressure in the pump is lower than the pressure of the water column present over the top valve 40. When the vacuum in the pump chamber 32 is sufficiently large for the pressure outside the pump chamber 32 (atmospheric pressure) to fill the pump chamber 32 again, bottom valve 12 opens automatically and refilling of the pump chamber starts. Fig. 8 illustrates this condensation at the end of the pump stroke where steam valve 8 is closed.

In Fig. 9, the condensing is finished, top valve 40 is closed and bottom valve 12 is open such that refilling of the pump chamber is commenced.

In Fig. 10, the filling of the pump chamber 32 continues with water which is sucked in through the suction line 10, steam/water trap 42 is filled with water again and is thus ready for a new pump stroke. When the pump chamber 32 is filled again with water, cf. Fig. 5, the described pump operation is repeated, etc.

In other words, the pump stroke continues to the point at which the connection between the pump chamber and the discharge pipe is filled with water. The steam can now escape from the pump chamber and bubble up in the discharge pipe and here be met with the cold water, resulting in instantaneous condensation of the steam. The condensation of the steam causes an immediate pressure drop in the pump chamber, the pressure drop is detected by a pressure transducer in the pump chamber, thereby causing closure of the steam valve (solenoid valve) and consequently termination of the steam supply. When the pressure in the pump chamber has dropped to a partial vacuum, the bottom valve with open due to the atmospheric pressure outside the pump chamber, and a filling of the pump chamber and the pipe connection between pump chamber and discharge pipe with water will take place. The pressure in the pump chamber will again be close to atmospheric pressure which is detected by the pressure transducer, the steam valve (solenoid valve) opens and a new pump stroke is initiated.

Alternatively, at the top of the pump chamber and at the bottom of the U-pipe there can be provided temperature sensors with the following function: During the pump stroke, the temperature sensor at the top of the pump chamber is influenced by the high steam temperature while the temperature sensor at the bottom of the U-pipe is influenced by the water temperature. When the short-circuiting occurs, the temperature sensor at the bottom of the U-pipe is influenced by the steam temperature, causing immediate closure of the steam valve (solenoid valve). The temperature sensor at the top of the pump chamber is not affected by this. When the pump chamber is filled with water, the temperature sensor at the top of the pump chamber is suddenly cooled, the steam supply is opened again and a new pump stroke is commenced.

A further alternative could be to let control of the opening and the closing, respectively, of the steam valve be determined by the water level in respective parts of the pump.

Fig. 1 1 shows an alternative embodiment of a steam-driven water pump 66 including a pump chamber 68, a suction pipe 70 with bottom valve 72, a discharge pipe 74 connected with a condenser 76 and a secondary discharge pipe 78, a steam/water trap 80 inserted between the pump chamber 68 and the condenser 76. At the top of the pump chamber 68 is arranged a plate-shaped diffuser 80 opposite a steam supply 82 which includes a steam valve 84.

As described above, the start of the pump operation depends on the fact that the pump chamber 68 is filled with water from the beginning. The pump chamber 68 above is also connected with a make-up water line 86 with associated valve 88 so that water can be supplied to the pump chamber 68. This is provided inside with a predominantly plate-shaped floating body 90 which has the task of acting as a piston and to constitute and provide a separation between the cold water and the steam such that an untimely condensation to the detriment of the efficiency of the water pump does not occur.

Fig. 12 shows a vacuum pipe solar panel 60 where e.g. thermal oil is used as the high pressure in the vacuum pipe solar panel 60 otherwise occurring when using water is hereby avoided. Fig. 13 shows a parabolic solar collector. Figs. 14 and 15 are explained above. Fig. 16 shows a draft of an alternative embodiment of a surface pump 92 with a pump chamber 93, a steam supply 94, an access connection 95, a discharge pipe 96 where the U-pipe/steam short-circuit 97 is disposed inside an expanded part 98 of the discharge pipe 96, i.e. the expanded part 98 of the discharge pipe 96 at the same time constitutes a condenser as condensing occurs inside the expanded part 98 of the discharge pipe 96.

The water trap/steam short-circuit is, as mentioned, important to the operation of the pump. If the pump was not equipped with the water trap/steam short-circuit, the steam would go up through the discharge pipe instead of escaping through the U-pipe. Hereby, condensation would commence, and the water that would go up into the pump chamber would immediately block and prevent the remaining steam from escaping. A steam plug would then be formed in the pump which only slowly would condense as condensation only will occur by the steam being cooled by the top and sides of the pump chamber and the water in the pump.

Disposition of the water trap/steam short-circuit is important. The water trap/steam short-circuit is to be disposed at a distance above the lower end of the discharge pipe. If the water trap/steam short-circuit was disposed under the lower end of the discharge pipe, the steam would also and in the same way as if the pump did not have a water trap/steam short-circuit escape up through the discharge pipe instead of through the water trap/steam short-circuit of the U-pipe which consequently never will come into action because the level is lower than that of the end of the discharge pipe. It is to be noted that the steam when reaching the U-pipe bend will immediately rise up in the discharge pipe through the U-pipe (difference in density). Hereby, the pressure drops in the pump chamber, and the pump stroke stops instantly. When the steam supply is closed at the same time, the pressure will continue to drop until reaching so low pressure (vacuum) that the bottom valve will open and the pump chamber be filled with water again. The new water is quickly sucked in and easily condenses the residual steam that may be present in the pump chamber.

The length/height of the two legs of the U-pipe relative to the bottom of the discharge pipe and the top of the pump chamber is also essential for the operation of the pump. The length of the leg disposed in the pump chamber itself is to ensure that at the time where the pump is about to be filled with water the steam can still escape into the discharge pipe and up into the condenser. If the end of the leg is disposed too close to the bottom of the discharge pipe, the leg will be filled with water too early when the pump chamber is about to be refilled with water. It is thereby prevented that the "remaining" steam can escape.

If the end of the U-pipe is disposed too close to the top of the pump chamber, there will not be sufficient time for the U-pipe to be filled with water, and to function as water trap again. The length of the leg of the U-pipe disposed inside the discharge pipe is critical for the condensing process as the latter depends on the ratio between the amount of water to be condensed and the amount water in which condensation is to take place.

A very short leg in the U-pipe and an end of the leg disposed close to the bottom of the discharge pipe will function when the amount of steam to be condensed does not entail a rise in temperature of the water in the discharge pipe of more than 20°C.

In theory, there is desired a very short leg in order to let the condensing start as quickly as possible. In theory, the condensing should rather be more or less finished before the steam reaches into the condenser. If the condensing is finished before the steam reaches the condenser, the condenser can be completely done without as the discharge pipe would perform the function of the condenser.

In that connection it is immaterial if the volume in which the steam is to condense is labelled discharge pipe or condenser. The end of the leg of the U-pipe which is disposed inside the discharge pipe is, however, not to be disposed too close to the bottom of the discharge pipe as in that case there is a risk that instead of penetrating up through the water in the discharge pipe and condensing therein the steam will penetrate down and out of the discharge pipe and back into the pump chamber. The end of the leg in the U-pipe terminating inside the discharge pipe can possibly be provided with a kind of steam spreader, i.e. a device which will "fragmentise" the outflowing steam. By fragmenting the steam, the steam will be absorbed faster into the water and the volume of the condenser can hereby be minimised.

The steam-driven water pump according to the invention will be suited for application in third world countries as it is a technology with a minimum of replacement parts, minimal operation, great robustness (reliability) and without need of external energy supply. The pump can be used everywhere in the world where there is need for water and where the required amount of solar energy is available.