SE543854C2 - Cavitator for gas generation - Google Patents

Abstract

The invention relates to a cavitator (3) to be used in a gas generator. The cavitator (3) is provided with a cavitator inlet (301) and a cavitator outlet (302) having one or several cavitator channels (305, 305a, 305b) having a cavitator channel inlet (307a, 307b) and a cavitator channel outlet (308b).The cavitator channel or channels (305, 305a, 305b) are further provided with cavitation inducing means, e.g. flow guiding or restricting means, wave shaped channel walls (314 a-c), protrusions and widenings, surface irregularities such as cavitation generating indentations (313) or a combination thereof, for inducing a differentiated pressure within a liquid flowing through the cavitators (3). The cavitator (3) further comprises an outer cavitator stator (303) and an inner cavitator rotor (304) arranged to rotate by a liquid flow through the cavitator (3). The rotation of the inner cavitator rotor (304) will induce a differentiated pressure within the liquid in the cavitator (3) promoting cavitation in the liquid flowing through the cavitator channels (305). The invention also relates to a gas generator comprising such a cavitator (3) as described herein.

Description

CAVITATOR FOR GAS GENERATION FIELD OF INVENTION The invention relates to a cavitator for generating a gas by cavitation of a liquid, e.g.water. The invention also relates to a gas generator in which the cavitator is suitablyused. The invention could for example be used for desalination of sea water.

BACKGROUND ART Cavitation is a known method for gasification of liquids. Cavitation is generallyreferred to as the formation, growth and subsequent collapse of gas, e.g. vapour ifwater is used as the liquid, inside a liquid. ln general, there is a need for causingrapid and local changes in the hydrostatic and hydrodynamic conditions of the liquid.There are different ways known to cause cavitation of liquid such as adding highlevels of energy to the liquid by irradiation, e.g. by highly energetic waves such aslaser light or high energy particles such as electrons, or by subjecting the liquid tohigh mechanical forces and stress. ln general, the use of subjecting liquid to highlyenergetic irradiation is suitably used for small scale experiments but is costly to beused for industrial applications. Mechanically induced cavitation seems to be morepromising in order to be used for large scale cavitation of liquids. ln mechanicallyinduced cavitation, the liquid to be treated is generally subjected to high flow speedsand guided through a flow path including flow guides and flow restrictions, e.g.venturi passages, in order to subject the liquid to the desired hydrostatic and hydrodynamic conditions.

Regardless of how changes in hydrodynamic conditions are caused, different typesof constrictions may be employed to cavitate a fluid. However, movement of largevolumes of fluid at the requisite speed through each of these constrictions to effecthydrodynamic cavitation requires high energy input. As a result, achieving cavitationinduced evaporation from conventional hydrodynamic solutions remains impractical and unreasonably expensive.

A device used for cavitation of liquids by mechanically inducing cavitation in a fluid orliquid is for example disclosed in US 2016/ 185 624 which describes a multi-stage cavitation assembly. The liquid or fluid is subjected to a first cavitation inducingfeature followed by second cavitation feature which occurs after the fluid is subjectedto flow guiding means slowing down the speed of the fluid and is directed to thesecond cavitation feature. The device described in US 2016 / 185 624 is described tobe suitably used for fluid treatment such as water remediation.

DISCLOSU RE OF INVENTION The invention relates to a cavitator which may be suitably used in a gas generator.The cavitator is provided with a cavitator inlet and a cavitator outlet for a liquid to becavitated in the cavitator. The cavitator further comprises one or several cavitatorchannels having a cavitator channel inlet and a cavitator channel outlet. The cavitatorchannel or channels are designed with cavitation inducing means such as flowguiding or flow restricting means, bended or curved channels, wave shaped channelwalls, protrusions and widenings, surface irregularities such as cavitation generatingindentations or a combination thereof. The cavitation inducing means will contributeto provide a differentiated pressure within a liquid flowing through the cavitators. Thecavitator further comprises an outer cavitator stator and an inner cavitator rotorarranged to rotate relative said outer cavitator stator. The cavitator is furtherdesigned to induce a rotation of the inner cavitator rotor by a liquid flow through thecavitator. The rotation of the inner cavitator rotor will in turn induce a differentiatedpressure within the liquid in the cavitator promoting cavitation in the liquid flowingthrough the cavitator channels. Hence, the rotation of the rotor will together with thecavitation inducing means in the cavitator channels provide for a cavitation of a liquidflowing there through due to the inertia of the liquid and the centrifugal forces inducedby the rotation of the main rotor body. As the liquid flows through the cavitator, thecavitator inducing means will cause a liquid flowing through the cavitators to changedirections, at the macroscale or microscale, which will contribute to a differentiatedpressure within the liquid in the cavitator.

The cavitator channel or channels may be designed to be wave-, saw tooth- orcurvilinear shaped. According to a specific shape of the cavitator channel orchannels, they are designed to be shaped as sinus curves. A sinusoidal shape hasturned out to be advantageous in that it creates pressure difference in the cross- sectional and the longitudinal direction of the channels so as to increase cavitation.

The cavitator channel or channels, which are running along the axis of rotation of thecavitator rotor, may be subdivided in an inner cavitator channel located closer to theaxis of rotation of the cavitator rotor than a second outer cavitator channel. The firstinner channel is formed between a first, innermost wall and a second, middle wall inthe cavitator forming a first inner flow path for a fluid and the second, outer channel isformed between the second, middle wall and a third, outermost wall in the cavitatorforming a second outer flow path for the fluid. The cavitator may be designed suchthat the inner wall and intermediate wall forms part of the cavitator rotor while theouter wall forms part of the cavitator stator. ln case the cavitator is designed with an inner and outer channel as disclosed above,there may be capillary vanes between the first inner channel and the second, outerchannel. The capillary vanes are small channels formed in the intermediate wallbetween the outer and inner cavitator channels which provides for fluid communication between the inner and outer cavitator channels.

The capillary vanes may be designed to function as jets for causing a rotationalmovement of the inner cavitator rotor. Hence, by designing the capillary vanes to nothave a radial direction relative the axis of rotation, the flow of liquid through the capillary vanes may cause a rotational movement around the axis of rotation.

The capillary vanes could also be designed to increase cavitation for a liquid passingthrough the vanes. This may for example be achieved by designing the capillary vaneinlet and outlet such that the capillary vane outlet is wider than the capillary vaneinlet. Designing the capillary vane inlet more narrow than the capillary vane outlet willcontribute to create a change of the pressure within the fluid passing through thecapillary vanes. A liquid passing through the capillary vane and entering a narrowinlet and exiting a wider outlet will be subjected to a pressure decrease while flowingthrough the capillary vane and thus induce a cavitation of the liquid passing throughthe vane. The capillary vanes may be designed to have a step less change of thewidth, e.g. being funnel shaped, or designed to have an abrupt change of the widthbetween the capillary vane inlet and the capillary vane outlet, e.g. by having aconstant smaller capillary width in the inlet section and a constant, larger width of theoutlet section. ln order to cause a liquid to flow through the capillary vanes could the first innercavitator channel be provided with a dead end. The flow of liquid entering the innercavitator channel inlet must thus to pass through the capillary vanes from the innercavitator channel to the outer cavitator channel which is provided with an outletopening. At least the inner cavitator channel will have an inlet opening and there may also be an inlet opening in the outer channel.

A cavitator comprising an inner and an outer cavitator channel may be designed suchthat said first, innermost wall and said second intermediate wall in the cavitator formpart of said inner cavitator rotor while said, third, outer wall in the cavitator (3) formspart of said outer cavitator stator.

A cavitator designed with capillary vanes between the inner and outer channel forinducing a cavitation of the liquid passing through the capillary vanes shouldpreferably be designed to avoid the cavitation of the liquid to erode the cavitatorchannels. Cavitation is a known phenomenon which erodes and ruins a material if itoccurs on or adjacent to a surface, e.g. on boat propellers. The cavitator channelsshould thus be adapted such that the second outer cavitator channel is designed tohave a width adapted to provide a sufficient distant for the gas bubbles formed bycavitation of the fluid, when flowing from the first inner cavitator channel via thecapillary vanes to the second outer cavitator channel, to collapse inside the fluidbefore the cavitation bubbles reaches the outer wall of the second outer cavitator channeL The invention also relates to a gas generator for gasification of liquids in which acavitator as disclosed above may be suitably used. The liquid may for example bewater such that vapour is produced in the gas generator. The gas generator may forexample be used for vaporizing salt water in order desalinate the water to producepotable water. The gas generator comprises a main rotor body being rotatablymounted to a static support framework and the main rotor body is arranged to rotatearound a rotor body main axis. The main rotor body comprises one or several rotorbody channels having a rotor body channel inlet and a rotor body channel outlet. Thechannels are designed for guiding a flow of a liquid from the rotor body channel inlet,which is located at a distance R1 in the radial direction from the main axis, towards the rotor body channel outlet which is located at a distance R2 in the radial direction from the rotor body main axis. The rotor body channel outlet is located further awayfrom the rotor body main axis than the rotor body channel inlet, i.e. R2 > R1, suchthat a liquid in the rotor body is forced from the rotor body channel inlet towards therotor body channel outlet by centrifugal forces as the main rotor body rotates aroundthe main axis. Hence, the rotation of the main rotor body may be used to induce apumping effect in the rotor body channel. The main rotor body further comprises oneor several cavitators each one comprising one or several cavitator channels. The oneor several cavitator channels are provided with a cavitator channel inlet and acavitator channel outlet. The cavitator channel inlet is fluidly connected to the rotorbody channel outlet for guiding the liquid flow to the cavitator for cavitation of theliquid. The cavitator channel is designed to comprise cavitation inducing means, e.g.flow guiding or restricting means, wave shaped channel walls, protrusions andwidenings, bends, surface irregularities such as cavitation generating indentations ora combination thereof. The cavitation inducing means are present in order to inducea differentiated pressure within the liquid in the cavitator. A differentiated pressurewill arise from the inertia of the liquid and the centrifugal forces due to the rotation ofthe main rotor body as the liquid pass through the cavitation inducing means in thecavitator channel so as to induce cavitation in the liquid flowing through the cavitator.

Hence, the gas generator is designed to induce a fast flow of the liquid through themain rotor body and the cavitators by a fast rotation of the main rotor body in order toinduce cavitation in the liquid flowing in the cavitator. The cavitation inducing meanscould for example include that a cavitator channel is designed to comprise severalcurves or bends, e.g. a wave shaped pattern, causing a liquid flowing through thecavitator channel to change directions so as to cause a differentiated pressure withinthe liquid in the cavitator. Using a curved channel, e.g. a wave shaped channel, maynot usually have any major impact for inducing cavitation. However, at the very largespeed the main rotor body is intended to rotate, e.g. having a rotational speed of 000 rpm up to 30 000 rpm, there will be a considerable impact from the change ofdirections of the channel and flow of fluid there through. By designing the channelswith its curves and bends such that the change of directions will cause indifferentpressure profiles on a liquid flowing therein at different portions of the channel whensubjected to the centrifugal forces from the rotation of the main rotor body will induce cavitation in the fluid. At certain locations in the channel, there will be compressive forces acting on the fluid and its molecules and particles. At other locations there willbe forces acting to separate the liquid molecules and if these forces are made strongenough the formation of small bubbles will appear. These bubbles will generallyimplode shortly after they have been formed as long as the liquid is contained in arestricted environment such as the confined space of the cavitator channel. Hence,the strong forces enabling a differentiated pressure within the liquid in the cavitatorarises from the inertia of the liquid and the centrifugal forces caused by the rotation ofthe main rotor body at a sufficiently high speed thereby causing the water flowingthrough the cavitator to cavitate when subjected to flow restrictors, bends or other cavitation inducing means.

The main rotor body is preferably designed to comprise a multitude of cavitatorsbeing located equidistant from each other and from the main axis. A symmetric rotoris of importance due to the large forces arising from the high speed rotational motionof the main rotor body. Hence, there are preferably at least two equally designedcavitators comprised in the main rotor body being symmetrically located around the rotor body main axis.

The main rotor body may further be designed to comprise walls defining a rotatablecontainer having an interior main rotor body space to which the vaporized liquid isreleased from the cavitators. The interior space of the main rotor body could bedesigned to be bell shaped. This design could also be described as being shaped asthe lower half of an hour glass or as a truncated cone. This design could also bedescribed as having a cross sectional area of the main rotor body perpendicular to itslongitudinal axis which decreases towards the outlet at the top of the main rotor body.The main rotor body could for example be designed such that each cross section ofthe main rotor body perpendicular to the rotational axis forms a circular segment. Themain rotor body should have a rotational symmetric shape around its rotational axis in order to avoid unbalance in the main rotor body.

Even though it is disclosed above how a casing may be used for the gas generatorand a specific shape of such a casing may be designed, the gas generator functionsalso without a casing or having a casing of another shape.

The main rotor body casing forming part of the main rotor body may be designed tohave a main rotor body outlet at its upper portion. The main rotor body casing may be designed to have a reduced cross sectional area perpendicular to the rotor bodycentre axle in its upper part compared to a cross sectional area in lower part of themain rotor body casing, e.g. by designing the main rotor body casing such that themean cross sectional area of the rotatable container formed by the main rotor bodycasing will decrease in along its length from the lower part to the upper part. Thismay for example be achieved by having a bell or cone shaped main rotor casing.

The gas generator may be designed such that the main rotor body is comprised in aninner casing forming part of the static support structure. The inner casing could beused as a pressure chamber in order to provide a vacuum or low pressureenvironment in which the main rotor body is rotating. By providing a low pressureenvironment will the frictional forces acting on the main rotor body while rotating be decreased. lf the gas generator comprises a main rotor body casing, the casing may be designedto comprise a main rotor body outlet which is adapted to cooperate and fit into anouter container space gas inlet. lf the gas generator is further provided with an innercasing in which the main rotor body is located, the main rotor outlet could bedesigned to be comprised in an inner casing upper wall. The main rotor body outletand the outer container space gas inlet may be designed such that the openingshave an overlapping area. The outer container space gas inlet could be designed tohave a larger cross sectional area than the main rotor body outlet such that there is agap created between the outer container space gas inlet and the main rotor bodyoutlet. By designing the gas generator in this way, it may be possible to use the flowof gas from the main rotor body space to create and maintain a vacuum or lowpressure zone in the inner container space due to the venturi effect of the flowing gas.

The main rotor body space could further be designed to comprise a flow restrictorencircling the centre axle. The flow restrictor is intended to be located between themain rotor body gas feed openings, where gas produced in the cavitators enters themain rotor body space, and the main rotor body outlet. The purpose of including sucha flow restrictor is to cause solid matter contained in the gas to be separated from thegas flow. Particles entrained in the gas flow will be separated from the gas flow by the impact of hitting the flow restrictor.

The main rotor body space could be designed to comprise main rotor drainageoutlets (207). The drainage outlets could be located at in the bottom region of themain rotor body space, e.g. in a drainage reservoir running along the circumferenceat the bottom of the main rotor body space. The drainage outlets will discard solidmatter which has been separated from the gas flow and fallen down to the bottom ofthe main rotor body space together with a portion of the fluid.

The gas generator could be designed to comprise a fixed outer casing in which thefixed inner casing is comprised. The fixed inner casing defining an inner containerspace could be used as a vacuum or low pressure chamber for the main rotor body.The flow of gas produced by the cavitators could be guided from main rotor body viaan outer container space gas inlet to the outer container space. The outer container space may thus function as a reservoir for gas produced by the cavitators.

The outer container space may further comprise liquid supply conduits in which liquidto be fed to the main rotor body is preheated by the gas generated in the main rotorbody flowing through the outer container space. The system can be controlled suchthat the gas flowing through the outer container space is cooled down to condense inthe outer container space. The condensed gas may be collected from the outercontainer space via an outer container space outlet in order to be collected in tanks or further distributed via a piping system. ln order to establish a flow of liquid to be supplied to the gas generator, the mainrotor body may be designed as a pump unit such as a screw pump or Archimedeanscrew. A screw pump will provide for a pumping effect when the main rotor bodyrotates in order to pump a liquid from a liquid supply reservoir via pump channelsforming part of the main rotor body channels when the main rotor body is rotating.The pumping of liquid could of course be achieved by any other kind of pumpingarrangement if desired.

The main rotor body is preferably designed to include at least two cavitators in orderto balance the rotating main body. Any kind of cavitators could be used in order toproduce gas from cavitating the liquid. A particularly useful kind of cavitators to beused in the gas generator is designed to have an inner cavitator rotor arranged torotate relative an outer cavitator stator. The rotational movement of the cavitator rotor may be achieved by designing the cavitator to induce a rotational movement by the water flowing through the cavitator from the cavitator inlet to the cavitator outlet. Oneway of achieving a propelling force for rotating the cavitator rotor is to design thecavitator rotor with turbine blades. Still another way of producing a rotationaimovement is to design cavitator channels to direct the flowing liquid to provide arotationai force.

In case cavitators having a cavitator rotor and a cavitator stator is used, they can bearranged in the main rotor body such that their axis of rotation are essentiallyperpendicular to the main rotor body centre axle being the axis of rotation of the mainrotor body. The cavitators can also be arranged such that their axis of rotation isessentially perpendicular to the radial direction of the main rotor body centre axle. Incase the axis of rotation of the cavitator fulfils both the above described criteria, theaxis of rotation will be essentially parallel to the tangential direction of the circle alongwhich the cavitator rotates around the main rotor body centre axle.

The cavitator could be arranged such that the cavitator inlet is arranged at or close tothe leading end of the cavitator and said cavitator outlet arranged at or close to the trailing edge of the cavitators when the cavitators rotates with the main rotor body. lnthis case the flow of liquid through the cavitator will contribute to the propulsive force for rotating the main rotor body.

The gas generator described above discloses different features of how a gasgenerator according to the invention may be designed. However, there are manydifferent ways to design a gas generator within the scope of the invention. The basicprinciple is to provide a main rotor body with cavitators rotating with the main rotorbody.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 discloses an embodiment of a gas generator FIG 2 discloses embodiments of a main rotor body Fig. 3 discloses an embodiment of a cavitator FIG.4 discloses schematically the function of an embodiment of a cavitatorFIG. 5 discloses a gas generator comprising a waste collection tank DETAILED DESCRIPTION OF INVENTION ln figure 1 is disclosed an example of a gas generator 1 suitably used for a cavitatoraccording to the invention. The gas generator 1 exemplified in figure 1 comprises anouter casing 101 forming part of a static support framework. ln this case is the outercasing 101 designed as a cylinder having an envelope surface 101a, an upper wall101b and a bottom wall 101c defining a container space inside the outer casing 101.The static support structure further comprises a liquid supply conduit 102 for supplyof a liquid to the gas generator 1. The liquid is guided from the liquid supply conduit102 to a liquid supply reservoir 104 via the space inside the outer casing. ln figure 1b a portion of the envelope surface 101a has been removed in order toreveal the interior of the outer casing 101. lnside the outer casing 101 is an outercontainer space 105 formed between the outer casing 101 and an inner casing 106.The inner casing 106 also have a generally cylindrical shape. ln the outer containerspace 105 are provided transfer conduits 103. The transfer conduits 103 arepreferably designed and made from a material having high heat conductivity in orderto provide for an efficient heat exchange between the liquid inside the transferconduits and the outer container space 105. lt is further provided at least one outercontainer space outlet 107 in the bottom wall 101c of the outer casing 101 in theouter container space 105. The outer space container outlet 107 will serve as anoutlet for gas produced in the gas generator 1 which will condense in the outercontainer space105. ln figure 1c a portion of the envelope surface of the inner casing 106 has beenremoved in order to reveal the inside of the inner casing 106 defining an innercontainer space 108. ln the inner container space 108 is provided a main rotor body2 comprising a main rotor body casing 201. The main rotor body casing 201 is bellshaped. The main rotor body 2 is arranged to rotate along an axis along thelongitudinal extension of the cylinder shaped inner and outer casings 106, 101. Whenreferring to the rotational axis of the main rotor body in this description, the axis willbe referred to as the Y-axis. ln figure 1d a portion of the main rotor body casing 201 has been removed in order toreveal the interior of the main rotor body casing 201 defining a main rotor space 202.lt is inside the main rotor space 202 where the cavitators 3 (see figures 2 and 3) arelocated and where the liquid is transformed from liquid to gas. Liquid is guided fromthe liquid supply reservoir 104 beneath the outer casing 101 via a rotor body channel203 having a rotor body channel inlet 204 connected to the liquid supply reservoir104. The liquid will further be guided via the rotor body channel 203 to cavitators (notshown) comprised in a toroidal casing 208. The liquid will cavitate and be gasified inthe cavitators 3 and finally leave the toroidal casing 208 via the main rotor body gasfeed openings 210 in the toroidal casing 208. The gas flowing through the main rotor 11 body gas feed openings 210 in the toroidal casing will flow towards a main rotor bodyoutlet 205. The main rotor body outlet 205 has a circular cross sectional openingwhich is adapted to fit into an outer container space gas in|et 109 which is formed inan upper wall 106b of the inner casing 106. The outer container space gas in|et 109is funnel shaped and designed to encircle the main rotor body outlet 205 andpreferably designed such that the outer container space gas in|et 109 over|ap themain rotor body outlet 205 in the axial direction. There should be a gap between theouter container space gas in|et 109 and the main rotor body outlet 205. The gap willnot only prevent any undesired contact and friction between the rotating main rotorbody 2 and the stationary outer container space gas in|et 109 but also this design willcontribute to a venturi effect when gas at high speed flows through the main rotorbody outlet 205. This flow will strive to withdraw air from the inner container space108 such that an under pressure or vacuum is created in the inner container space108. The under pressure created in the inner container space 108 will thus contributeto a desired lower frictional loss when the main rotor body 2 is rotating at very highspeeds. ln figure 1d is also disclosed a centrally located flow restrictor 206. The flow restrictor206 will, together with the funnel shaped walls of the main rotor body casing 201,form a flow restriction for the gas flow in the passage from the main rotor body gasfeed openings 210 in the toroidal casing to the main rotor body outlet 205. Thisrestricting arrangement will cause particulate matter, even very small particles suchas salt, to be subject to centrifugal forces arising from hitting the flow restrictor 206 orthe walls of the main rotor body casing 201 which will make them deviate fromforming part of the main flow of gas directed to the main rotor body outlet 205 suchthat there will essentially only be gas leaving the main rotor space 202 while particlesand some of the gas will be falling down towards the bottom of the main rotor space,essentially along the walls of the main rotor body casing 202. ln case the gasgenerator 1 is used for desalination of salt water, there will be vapour essentially freefrom any salt (and other particles) leaving the main rotor body outlet 205 while therewill be a concentrated brine flowing along the walls of the main rotor body casing201.

The general flow of a liquid to be gasified and thereafter condensed once more whileimpurities are removed may be briefly described with reference to figures 1a to 1d asfollows. A liquid enters into the gas generator 1 from a liquid supply conduit 102 to aliquid supply reservoir 104 via transfer conduits 103 located in the outer containerspace. The liquid will be guided from the liquid supply reservoir 104 to the main rotorbody 2 via a main rotor body channel 203 and guided to cavitators (not shown) whichwill gasify the liquid by cavitation. The liquid flowing thorough the transfer conduits 12 103 will be preheated by heat exchange in the outer container space 105 with thegas produced by the gasified liquid from the main rotor body 2. The gasified liquid isflowing out from the main rotor space 202 via main rotor body outlet and 205 andouter container space gas inlet 107 to the outer container space 105. As the gas willcondense in the outer container space 105, it will fall down to the bottom wall of theouter casing 101c wherefrom the condensed gas is guided via the outer containerspace outlet 107 to a desired tank or reservoir. The impurities from the liquid,together with some of the liquid which not follow the gas flow from the main rotorspace 202 will flow towards the bottom of the main rotor space 202 where there areone or several main rotor drainage outlets 207 for draining the liquid separated fromthe gas. The main rotor drainage outlets 207 are guiding the liquid to a drainagecollector 110 in the inner container space 108 which is provided with liquid wasteconduits 111 for removal of the waste liquid from the main rotor body 2. ln figure 2a is shown a main rotor body 2 where the main rotor body casing 201 hasbeen removed to disclose the design on the inside of the main rotor body 2. Themain rotor body 2 comprises a circular toroidal casing 208 which rotates around acentre axle 209 which will correspond to the Y-axis in the following schematicallydescription of the rotational arrangement below. There are three cavitators 3arranged and evenly distributed in the toroidal casing 208 such that the main rotorbody 2 will be balanced. Hence, there should preferably be at least two cavitatorscomprised in the main rotor body 2 distributed equidistant from each other and on thesame radial distant from the centre axle 209 being the axis of rotation around whichthe main rotor body 2 rotates. Each cavitator 3 comprises a cavitator inlet 301 and acavitator outlet 302 which is located in connection with a main rotor body gas feedopenings 210 in the toroidal casing. To be noted, the portion of the toroidal casing208 which is missing at the location of the cavitator inlet 301 has only been removedin the drawing in order to make the cavitator inlet 301 visible in the drawing and thispart is covered by the toroidal casing 208 as shown for the other two cavitators. ln fig. 2b is disclosed a pump 211 in which the pump casing 212 has been partlyremoved in order to reveal the pump main body 213 covered by the pump casing212. The pump main body 213 has been provided with helically shaped cut-outswhich together with the pump casing 212 form pump channels 214 which thus form ascrew pump, also commonly referred to as an Archimedean screw. The pump 211 ispartly submerged into the liquid supply reservoir 104 such that the pump channelinlets 215 are located below the surface level of the liquid in the liquid supplyreservoir 104. As the main rotor body 2 starts to rotate, in this case clockwise, liquidwill be drawn upwards by the helically screw shaped channels 214 and guided furtherto the cavitator inlets 301 by the rotational movement of the main rotor body. An 13 additional pumping effect will also arise from the centrifugal forces acting on theliquid as it enters the pump 211. The liquid enters at or close to the centre axle 209and is thereafter guided upwards and outwards through the pump channels 214. Asis obvious from figure 2b, the liquid will follow the helical pattern of the pumpchannels 214 as the liquid rises up to the level of the toroidal casing 208 where afterthe channels will continue in an essentially radial direction towards the peripheralparts of the main rotor body 2 having an outlet in the toroidal casing 208 close to thecavitator inlet 301.

Hence, the above figures 1 a-d and 2 a-b disclose how a complete system forgasification by cavitation of a liquid may be designed. However, even though thesystem described have many beneficial features, the overall system according to theinvention may be designed in a more simplistic way. ln figure 2c is disclosed how amore basic system according to the invention may be designed. ln figure 2c is simplydisclosed a gas generator 1' comprising a main rotor body 2' provided with a centreaxle 209' which is provided with a hollow inside forming part of a channel 214' fordistribution of a liquid from a channel inlet 204' to a pair of cavitators 3' located atdiametrically opposite sides of the rotational axis. The device could be provided withan Archimedean screw or having an additional pump unit but may also be designedwithout any additional pump equipment and rely on the centrifugal forces acting onthe liquid as it flows through the channel 214'. Hence, the essential features forproviding a gas generator 1 according to the invention are disclosed in figure 2c. lnorder to function as desired, the gas generator 1' in figure 2c as well as the gasgenerator 1 described in figures 1a-d and 2a-b, shall be provided with a cavitator 3which is designed as a small turbine in order to subject the liquid to further centrifugalforces from additional rotation in the cavitator. An example of the design of such acavitator 3 will be described below with reference to figures 3 and 4.

With reference to figures 3a-3f the design of the cavitator 3 will be described. lnfigure 3a is disclosed a cavitator 3 having a generally cylindrical outer shape. Acavitator inlet 301 is located at a first axial end of the cylindrical cavitator 3 and acavitator outlet 302 at the second, opposite axial end of the cylindrical cavitator 3.There are further disclosed an inlet cap 301a with an inlet opening and an outlet cap302a provided with outlet openings. The inlet and outlet caps 301a, 301b may beused to direct and control the flow of fluid entering and leaving the cavitator 3.However, the inlet and outlet caps 301a, 302a could be designed different and thecavitator 3 will work also without these caps 301a, 301 b. ln the following figures 3b to3e, the caps have therefore been left out. ln figure 3b is disclosed an exploded view of the cavitator 3 in figure 3a but withoutcaps. The cavitator 3 comprises an outer stator 303 which forms a casing into which 14 a cavitator rotor 304 is fitted. The cavitator rotor 304 comprises an inner rotor piece304a and an outer rotor piece 304b which are designed to fit into each other and atleast partly overlap each other in the axial direction. ln figure 3c is shown a cross sectiona| view of the cavitator 3 (without caps) whereina cross sectiona| cut has been made dividing the cavitator stator 303 in ha|ves alongits longitudinal extension. Also the outer rotor piece 304b is shown in a crosssectiona| view where the cross sectiona| cut is dividing the outer cavitator rotor 304bin ha|ves along its longitudinal extension. However, the cross sectiona| cut of theouter cavitator rotor 304b has been rotated somewhat relative the cut of the cavitatorstator 303 such that the different parts are more easily recognized. ln the overlapping portion of the inner rotor piece 304a and the outer rotor piece304b, the outer rotor piece 304b is designed to enclose the inner rotor piece 304asuch that there is gap in the radial direction between the inner and outer rotor pieces304a, 304b. The gap is extending the full circle between the inner and outer rotorpieces 304a, 304b such that an annular shaped void space is created there between.The void space further extends in the longitudinal direction such that an innercavitator channel 305a is crated forming part of a cavitator channel 305 (see fig. 3eand 3f) for a fluid passing through the cavitator 3 from the cavitator inlet 301 to thecavitator outlet 302. ln a similar manner, a void space is created in the radialdirection between the outer rotor piece 304b and the cavitator stator 303 creating anouter cavitator channel 305b forming part of the cavitator channel 305.

The cavitator rotor in figure 3c further comprises rotor blades 306 located close to thecavitator inlet 301. The rotor blades 306 are designed to cause a rotation of thecavitator rotor 304 as the fluid flows through the cavitator 3. The fluid will pass therotor blades and be directed towards inner cavitator channel inlets 307a and outercavitator channel inlets 307b (see figure 3e). The inner cavitator channel is providedwith a closed end 308a while the outer cavitator channel is provided with an outlet308b close to the end of the cavitator 3 where the cavitator outlet 302 is located. Aliquid entering the inner cavitator channel 305a may thus not pass through an outletat the end of the inner cavitator channel. However, the inner cavitator channel 305 isseparated from the outer cavitator channel by an intermediate wall 310 which isprovided with capillary vanes 309 connecting the inner cavitator channel 305a withthe outer cavitator channel 305b. The fluid entering the inner cavitator channel 305awill thus be directed via the capillary vanes to the outer cavitator channel 305b to bemixed with the flow in the outer cavitator channel 305b to flow towards the outercavitator channel outlet 308a. The capillary vanes 309 will serve as generators forcavitation of the fluid passing through them. The shape of the capillary vanes 309disclosed herein has a narrow inlet 311 in the side of the intermediate wall 310 facing towards the inner cavitator channel 305a and is widening towards its outlet 312 in theintermediate wall 310 at its side facing towards the outer cavitator channel 305b. Thisshape will contribute to cavitation of the fluid passing through the capillary vanes asthere will be a reduced pressure as the capillary vane 309 widens towards thecapillary outlet 312.

Figures 3c and 3d differs in that there are rotor blades 306 provided on the cavitatorrotor 304 in figure 3c while there are no rotor blades present in figure 3d. Bydesigning the capillary vanes adequately they may function as jet streams inducing arotation of the cavitator rotor 304. Hence, there are not necessarily present rotorblades on the rotor 304 but it may also function with only the impulse from the fluidflowing through the capillary vanes in order to provide a rotation of the rotor. ln addition to the cavitation generated by the passage of the fluid through thecapillary vanes 309, also the sinusoidal shape of the cavitator channels 305a, 305btogether with the centrifugal forces from the rotation of the cavitator rotor 304 willcontribute to an increased cavitation. ln addition, there are also provided cavitationgenerating indentations 313 on the inner wall 314 of the cavitator inner channel 305aalso improving the generation of cavitation. lt shall be noted that the explicit design of the cavitator 3 in figures 3 a-f only servesas an example of how cavitator suitably may be designed according to the invention.However, the cavitator could be designed in another way. The important feature ofthe cavitator is that it is designed to include a cavitator stator 303 and a cavitatorrotor such that there will be rotation of the cavitator channel 305 causing the fluid inthe channel 305 to be subjected to centrifugal forces from the rotation of the rotor304. The theoretical theory beyond the design of the cavitator will be furtherexplained in figures 4a-d. ln figure 4a is disclosed how the forces acting on a liquid in a gas generator 1, 1'asdisclosed above are created and how they are used in the gas generator. Figure 4adescribes schematically how the cavitator 3 rotates when it is mounted in the mainrotor body 2 (see figure 2). The complete cavitator 3 rotates around the Y1-axis,which is parallel to the centre axle 209 in figure 2a and 2c, and is thus subjected to afirst centrifugal force from this first rotation. The cavitator 3, e.g. such a cavitator asdisclosed in figures 3a-3f, is further designed and comprised in the system such thatthe cavitator rotor 304 (see figure 3) rotates relative the cavitator stator 303 (seefigure 3) around a centre axis through the cavitator 3. The centre axis of the cavitatoris parallel with the Y0 ----Y2 axis in figure 4a. This second rotation will causecentrifugal forces acting outwards in a direction from the centre axis of the cavitatortowards the envelope surface of the cylindrical cavitator all around the cavitator. Due 16 to the construction of the cavitator and how it is integrated in the main rotor body asdisclosed in figures 2a and 2c, the centrifugal forces from the first and secondrotations will cooperate at different |ocations in different ways. The centrifugal forcesfrom the first rotation around the Y1-axis will be directed outwards from the Y1-axis ina direction perpendicular to the Y1-axis. The centrifugal forces from the secondrotation of the cavitator rotor 304 re|ative the cavitator stator 303 will be directedoutwards from the Y0----Y2-axis in a direction perpendicular to the Y0---Y2-axis. Onthe outside of the cavitator 3, i.e. the part furthest away from the Y1-axis, thecentrifugal forces from the first rotation around the Y1-axis will act in an outwarddirection from the Y1-axis. At this location, also the centrifugal forces from thesecond rotation of the cavitator rotor 304 will be directed outward from the Y1-axis.On the inside of the cavitator 3, i.e. the part c|osest to the Y1-axis, the centrifugalforces from the first rotation around the Y1-axis will still act in an outward directionfrom the Y1-axis while the centrifugal forces from the second rotation of the cavitatorrotor 304 will act in the opposite direction, i.e. towards the Y1-axis. Hence, theresulting centrifugal force from both rotations will change from being totally alignedon the outside to be working in opposite directions on the inside. The resulting forcewill gradually change and will also work in directions being along the Y1 axis alongthe circumference of the cavitator. For example, in the mid portion between theoutside and inside, the force from the second rotation by the cavitator rotor will bedirected along the Y1-axis but in different directions depending on if they are workingon the upside or downside. ln figure 4b is disclosed a cross sectional view of the cavitator 3 in a planeperpendicular to the centre axis through the cavitator 3, i.e. through the axis beingparallel to the Y0 Y2-axis in figure 4a. As can be seen in figure 4b, the capillaryvanes 309 are designed to be slanted in the cavitator rotor intermediate wall 310.The slanted capillary vanes 309 will contribute in providing a rotation of the cavitatorrotor 304 (see figure 2) when a liquid is forced to flow through the capillary vanes 309from the inner cavitator channel 305a to the outer cavitator channel 305b. The liquidflowing through the capillary vanes 309 will enter via a rather narrow capillary vaneinlet 311 in the inner cavitator channel 305a and will be exhausted from a rather widecapillary vane outlet 312 in the outer cavitator channel 305b. The design of thecapillary vanes 309 having a narrow inlet 311 and a wide outlet 312 will contribute tocavitation of a liquid passing through the capillary vanes 309. ln figures 4c and 4d is schematically disclosed how the mechanism of cavitationfunction in the cavitator 3. ln figure 4c is disclosed how a liquid passing through thecapillary vane 309 will cavitate due to the pressure difference created from having anarrow capillary vane inlet 311 and a wide capillary vane outlet 312. As the liquid 17 flows through the capillary vane, the pressure reduction occurring when the liquid thenarrow capillary vane inlet portion and entering the capillary vane outlet portion willcause some of the liquid to transform to gas phase and thus creates bubbles in theliquid flow passing through the capillary vanes 309. The creation of bubbles bycavitation is schematically disclosed in figure 4c where the somewhat larger dots inthe capillary vane outlet 312 zone represents molecules of a fluid which havecavitated and expanded from being in liquid phase to be in gas phase. As thesemolecules continue to flow into the liquid flow in the outer cavitator channel 305b, thegas phase bubbles will implode and form part of the liquid flow in the outer channel305b. ln figure 4d is schematically disclosed a pressure profile in the cavitator 3where the dots are intended to represent fluid molecules. As can be seen in figure4d, the curved regions of the wave shaped inner and outer channels 305a, 305bclosest to the centre rotation axis of the cavitator 3 have a less dense pattern ofmolecules indicating a lower pressure in these regions. ln particular, the capillaryvane outlet 312 zone has a very sparse occurrence of molecules indicating a verylow pressure. A fluid entering the cavitator channel inlet 301 as a liquid will thus flowvia the cavitator inner and outer channels 305a, 305b where the liquid will start tocavitate in the wave shaped channels 305a, 305b and be guided further to thecavitator outlet 302 where the fluid will expand to form a gas phase when leaving thecavitator. ln figure 5 is disclosed how the gas generator 1 according to an embodiment havebeen provided with a waste collector tank 112 to which the liquid waste conduits 111are connected in order to collect the waste flow from the main rotor body space 202.The waste conduit 111 is provided with a waste conduit valve arrangement 113 inorder to control the flow to and from the waste collector tank. The valve arrangement113 is important in order to be able to switch the collector tank 112 from being in afirst filling mode when the waste collector tank 112 is filled up with waste liquid and asecond discarding mode when the waste liquid is discarded from the tank. ln the firstfilling mode, the valve arrangement 113 is set to allow waste liquid from the mainrotor drainage outlet 207 to flow into the waste collector tank 112 via a waste tankpipe 114 while the outlet pipe 115 is closed. When the mode is switched to thesecond discarding mode, the waste conduit valve arrangement 113 should first beset to close the inlet flow from the rotor drainage outlet 207 where after the outletpipe 115 is opened up and allow the waste liquid to be discarded from the waste tank112 via the waste tank pipe 114 to the outlet pipe 115.

During the first filling mode will the waste collector tank 112 be connected to the mainrotor drainage outlet 207 via the liquid waste conduits 111 and will thus have thesame pressure as in the inner container space 108. As previously explained, the 18 pressure in the inner container space will be close to vacuum or at least considerablybelow the surrounding normal atmospheric pressure where the gas generator 1 islocated. Due to the low pressure in the tank when in filling mode, the control of thevalves to be opened and closed in the right order is essential to avoid a suddenpressure fluctuation in the waste collector tank 112. Hence, the valve arrangement113 should be controlled to never allow the waste liquid conduits 111 to be open atthe same time as the outlet pipe 115 is open in order to reduce possible pressurefluctuations in the inner container space 108. The low pressure generated andmaintained in the inner container space 108 is generated due to the high velocity flowof gas generated by the cavitators 3 attached to the main rotor body 2. The highvelocity gas will leave the cavitators 3 via the main rotor body gas feed openings 210in the toroidal casing and enter the main rotor body space 202. The gas will flowtowards the main rotor body outlet 205 while passing by a flow restrictor 206. Theflow restrictor 206 will, together with the funnel shaped outlet, cause the flow of gasto hit wither the flow restrictor 206 or the walls of the main rotor body casing 201causing impurities and particles withdrawn by the gas to flow downwards along thewalls of the main rotor body casing 201. The gas will continue to flow through thefunnel shaped outer container space gas inlet 109 and flow through the outercontainer space 105 and thus passing the transfer conduits 103 such that there willbe a heat exchange between the hot gas and the liquid flowing in the transferconduits 103. Preferably the heat exchanging is controlled such that the gas willcondense and be collected as liquid at the bottom wall 101c of the outer casing 101in order to be guided to the container outlet 107. The container outlet 107 may beconnected to a piping system for further transport of the condensed gas in the pipingsystem or having a tap for filling up storage tanks.

Claims (14)

1. _

2. A cavitator (3) to be used in a gas generator (1) wherein said cavitator (3) isprovided with a cavitator inlet (301) and a cavitator outlet (302), said cavitatorcomprising one or several cavitator channels (305, 305a, 305b) having acavitator channel inlet (307a, 307b) and a cavitator channel outlet (308b), saidcavitator channel or channels (305, 305a, 305b) provided with cavitationinducing means, e.g. flow guiding or restricting means, wave shaped channelwalls (314 a-c), protrusions and widenings, surface irregularities such ascavitation generating indentations (313) or a combination thereof, inducing adifferentiated pressure within a liquid flowing through the cavitator (3), saidcavitator (3) further comprising an outer cavitator stator (303) and an innercavitator rotor (304) arranged to rotate relative said outer cavitator stator(303), said cavitator (3) being arranged to induce a rotation of the innercavitator rotor (304) by a liquid flow through the cavitator (3) such that therotation of the inner cavitator rotor (304) will induce a differentiated pressurewithin the liquid in the cavitator (3) promoting cavitation in the liquid flowingthrough the cavitator channels (305) characterized in that the cavitatorchannel or channels (305) is subdivided in a first inner channel (305a), formedbetween a first, innermost wall (314a) and a second, middle wall (314b) in thecavitator (3) forming a first inner flow path for a fluid, and a second, outermostchannel (305b) formed between said second, middle wall (314b) and a third,outermost wall (314c) in the cavitator (3) forming a second outer flow path forthe fluid. _ A cavitator (3) according to claim 1 wherein said cavitator channel or channels (305, 305a, 305b) are designed to be wave-, saw tooth- or curvilinear shaped.

3. A cavitator (3) according to claim 2 characterized in that the cavitator channelor channels (305, 305a, 305b) are designed to be shaped as sinus curves.

4. . A cavitator (3) according to claim any previous claim characterised in that there are capillary vanes (309) between the first inner channel (305a) and the second, outer channel (305b).

5. A cavitator (3) according to claim 4 characterised in that the capillary vanes(309) are designed to function as jets for causing a rotationai movement of the inner cavitator rotor (304).

6. A cavitator (3) according to any of claims 4 or 5 characterised in that saidcapillary vanes (309) comprises a capillary vane in|et (311) and a capillaryvane outlet (312) which are designed such that the capillary vane in|et (311) ismore narrow than the capillary vane outlet (312) in order to create a change of the pressure within the f|uid passing through the capillary vanes (309).

7. A cavitator (3) according to claim 6 characterized in that said cavities aredesigned to have an abrupt change of the width between the capillary vanein|et (311) and the capillary vane outlet (312).

8. A cavitator (3) according to any of claim any previous claim characterised inthat the first inner cavitator channel (305a) is provided with a dead end (308a)causing the flow of liquid entering the inner cavitator channel in|et (307a) topass through the capillary vanes (309) from the inner cavitator channel (305a)to the outer cavitator channel (305b).

9. A cavitator (3) according to any of previous claim characterized in that saidfirst, innermost wall (314a) and said second intermediate wall (407b) in thecavitator (3) form part of said inner cavitator rotor (304) while said, third, outerwall (314c) in the cavitator (3) forms part of said outer cavitator stator (303).

10.A cavitator (3) according to any previous claim characterized in that said

11. Second outer cavitator channel (305b) is designed to have a width adapted toprovide a sufficient distance for the gas bubbles formed by cavitation of thef|uid, when flowing from the first inner cavitator channel (305a) via the capillaryvanes (309) to the second outer cavitator channel (305b), to collapse insidethe f|uid before the cavitation bubbles reaches the outer wall (314c) of thesecond outer cavitator channel (305b). .A gas generator (1 ) for gasification of liquids, e.g. vapour from water, said gas generator (1) comprising a main rotor body (2) being rotatably mounted to astatic support framework such that the main rotor body (2) is arranged torotate around a rotor body centre axle (209), said main rotor body (2) 21 comprising one or several main rotor body channels (203), provided with arotor body channel inlet (204) and a rotor body channel outlet (214), forguiding a flow of a liquid from said rotor body channel inlet (204) being locatedat a distance R1 in the radial direction from the rotor body centre axle (209)towards said rotor body channel outlet (214) being located at a distance R2 inthe radial direction from the rotor body centre axle (209) wherein R2 > R1such that a liquid in the rotor body channel is forced from the rotor bodychannel inlet (204) towards the rotor body channel outlet (214) by centrifugalforces as the main rotor body (2) rotates around the rotor body centre axle(209), said main rotor body (2) further comprising one or several cavitators (3)each one comprising one or several cavitator channels (305) provided with acavitator channel inlet (301) and a cavitator channel outlet (302), said cavitatorchannel inlet (301) being connected to the rotor body channel outlet (214) forguiding said liquid flow to the cavitator (3) for cavitation of the liquid,characterized in that said gas generator (1) comprises a cavitator according toany of claims1 to 10.

12.A gas generator (1) according to claim 11 wherein said main rotor body (2) comprises at least two cavitators (3) being located equidistant from each otherand from the rotor body centre axle (209).

13.A gas generator (1) according to claim 11 or 12 characterized in that the main rotor body comprises a main rotor body casing (201) defining a rotatablecontainer having an interior main rotor body space (202) to which thevaporized liquid is guided from the cavitators (3).

14.A gas generator (1) according to any of claims 11 to 13 characterized in that said main rotor body (2) is comprised in an inner casing (106) forming part ofthe static support structure, said inner casing (106) being used as a pressurechamber.