Patent Application
20120291338
This invention relates to an apparatus and a method for producing an emulsion of a fuel and an emulsifiable component. The invention has particular, but not exclusive, application in producing emulsions for marine diesel engines and power plants.
A way of increasing fuel efficiency in engines, including diesel engines, and improving the ecological characteristics of their operation is the use of emulsions, such as water-fuel emulsions, although other emulsifiable components may also be used. Devices for producing an emulsion of fuel and water by cavitational treatment are already known. Cavitation is defined as the phenomenon of formation of vapour bubbles in a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure. Subsequently, when the bubbles flow into a high pressure zone, the bubbles shrink and collapse, causing a sharp increase in the localized temperature and pressure which gives rise to pressure waves. The pressure waves cause the break up of globules of fuel and the emulsifiable component into smaller globules. This enables an improved distribution of micro globules of the emulsifiable component in the fuel resulting in the formation of an emulsion. An emulsion is defined as the suspension of micro globules of a first liquid in a second liquid, in which the first will not mix. An emulsion obtained by cavitation is such that there is a film of fuel surrounding a micro globule of the emulsifiable component. When such an emulsion burns, the fuel-coated emulsifiable component globules are heated, expand and then explode causing even smaller fuel-coated emulsifiable component globules to be formed. This cycle of continuous micro explosions result in an increase in the overall surface area of the fuel, leading to an easier and complete combustion of fuel.
Depending on the physical and chemical properties of the fuel and the emulsifiable component, some emulsions may be easily formed by passing the mixture through a cavitation chamber or a similar apparatus to form emulsions. Some emulsifiable components and fuels may be difficult to mix owing to their incompatible physical properties such as viscosity and other chemical properties.
Typically, on forming emulsion by cavitation, a mixture of the fuel and the emulsifiable component is first formed which is then subjected to cavitation. The mixture may not be homogenous, with the concentration of fuel and the emulsifiable component differing in different volumetric zones of the mixture. When the mixture is subjected to cavitation and emulsified, the non-homogeneity will be manifested in the emulsion also, thus leading to a decrease in the quality of the emulsion. Decrease in quality can translate into a decrease in the efficiency of the fuel also.
The invention is described in the independent claim. Some optional features of the invention are described in the dependent claims.
In an apparatus for producing an emulsion of a fuel and an emulsifiable component where the first and second cavitation chambers and the nozzle outlet from the first cavitation chamber to the second cavitation chamber are positioned in coaxial alignment, the first fluid from the first cavitation chamber is introduced into the centre of the second cavitation chamber, so that the first fluid may be distributed uniformly in the second fluid. Moreover, a coaxial positioning of the outlet with respect to the second cavitation chamber reduces the risk of any disruption of the vortex of the second fluid that is generated in the second cavitation chamber.
When swirling flows of the fuel and the emulsifiable component are established in opposite directions, a mixture of improved homogeneity is obtained. A homogenous mixture is one where the components of the mixture are distributed uniformly throughout the volume of the mixture. Improved homogeneity is desirable and influences the combustion efficiency of the mixture of the fuel and emulsifiable component.
The apparatus can have the outlet from the first cavitation chamber projecting into the second cavitation chamber to a distance that is determined with respect to the diameter of the second cavitation chamber. The apparatus can also have the distance of projection of the outlet from the first cavitation chamber into the second cavitation chamber being determined with respect to the position of the inlet to the second cavitation chamber. This arrangement prevents the flow of the first fluid from the outlet interfering with the formation of the swirling flow of the second fluid in the second cavitation chamber.
The diameter of the outlet from the first cavitation chamber is preferably in the range of 0.7 to 0.75 times the diameter of the first cavitation chamber to provide turbulent flow conditions in the apparatus as turbulence is preferred for cavitation to occur.
The apparatus can have a check valve on the inlet to the first cavitation chamber, wherein the check valve is arranged to be opened only if the pressure in the discharge zone of the second cavitation chamber reaches a threshold, thus enabling to achieve stability of pressure in the second cavitation chamber, so that when the first fluid is introduced into the second cavitation chamber from the first chamber, an effective pressure gradient is obtained.
The cross-sectional area of the second cavitation chamber is preferably greater than or equal to 1.25 times the cross-sectional area of the outlet, to provide an increased uniformity in the distribution of the first fluid from the first cavitation chamber in the second fluid of the second cavitation chamber.
The accompanying drawings illustrate the invention, by way of example only and together with the description, serve to explain the principles of the invention.
A first apparatus 100 for producing an emulsion of a fuel and an emulsifiable component is illustrated in
A swirling flow is one which establishes a vortex. As is illustrated in
Similarly, the second cavitation chamber 20 has an inlet 4 through which the second chamber 20 receives the second fluid. The second fluid may be a second one of the fuel and the emulsifiable component. In the example of
It is evident from the above that either chamber may receive either the fuel or the emulsifiable component. The fuel may be heated up to a required temperature before it is introduced into any one of the first and second cavitation chambers. The temperature is dependent on the rheological properties of the fuel. The rheological properties of a fluid are properties like viscosity and elasticity which affect the flow characteristics of a fluid. The purpose of heating and the extent of heating the fuel is to bring the rheological properties of the fuel to a desired value, so as to facilitate a desired mixing of the fuel and an additive.
Referring again to
The direction of swirling flows in the first cavitation chamber 10 and the second cavitation chamber 20 may be the same or opposite. The motion of the first fluid in the first chamber 10 takes on a first direction and the motion of the second fluid in the second chamber 20 takes on a second direction. In the example of
As illustrated in
Having the first direction and the second direction of the swirling flow in opposite directions and in contact with each other enhances turbulent flows of the mixture, where the respective flows interrupt and interact with one another, leading to increased mixing of the first and second fluids. In other words, increased mixing leads to improved homogeneity of the emulsion. Additionally, turbulent flow helps to assist cavitation in the fluids. Turbulent flows result in rapid pressure and velocity gradients in space and time. These rapid gradients of pressure result in higher frequency of oscillation of the pressure waves in the cavitating mixture of fuel and the emulsifiable component. A higher frequency of oscillation of pressure waves contribute to the creation of numerous cavitation bubbles which are unstable and break up the emulsifiable component into very small droplets/globules, leading to a higher surface area of the fuel being available for combustion thereby providing improved combustion efficiency of the emulsion.
A second apparatus 200 as illustrated in
The inlets in the second chamber may be arranged such that they are at different levels in the second chamber. The advantage of having the tangential inlets in the second chamber at different levels is to provide improved uniformity of pressure distribution in the second cavitation chamber. This is illustrated in
The first chamber 10 and the second chamber 20, by virtue of their producing a swirling flow of the first fluid and the second fluid are vortex cavitational devices. The principle of working of a vortex cavitation device is by imposing rotational speed components on the vortex, the device produces pressure variations according to Bernoulli's principle. The pressure variations lead to alternate high and low pressure in the first and second fluids. The initial cavitation which occurs in the first chamber and the second chamber due to the above leads to cracking of the fluids. Cracking is the breakdown of the fluids on a molecular level which is a preferable step prior to intense cavitation and mixing of fluids. Higher molecular chains of hydrocarbons are disrupted. The process of cracking may be termed as activation of the fluids. This is advantageous especially when the fuel and the emulsifiable component are difficult to mix and emulsify owing to their physical and chemical properties under normal conditions.
The first chamber 10 has a first radius r and the second chamber 20 has a second radius R. In the example of
The pressure gradient (pressure differential) between the first chamber 10 and the second chamber 20, which is denoted by ΔP, contributes to the effectiveness of the working of the apparatus. Where the pressure in the first chamber 10 is P1 and the pressure in the second chamber 20 is P2, the pressure gradient ΔP can be deduced as follows:
ΔP=P1−P2
The first fluid flowing from the first chamber 10 having pressure P1 to the second chamber 20 experiences a pressure drop which is equivalent to ΔP. The pressure P2 is maintained lower than P1 to achieve the pressure drop. This pressure drop induces cavitation as cavitation inception occurs when the pressure of the flowing fluid goes below the vapour pressure of the flowing fluid. So if the pressure drop is higher, the greater is the intensity of cavitation which translates to a higher effectiveness of the system.
A greater pressure drop induces a higher velocity of the flow of the first fluid from the first chamber 10 to the second chamber 20, the higher velocity translating into higher frequency of oscillation of pressure waves resulting from cavitation. Thereby, a higher value of ΔP is desirable. ΔP can be increased by either increasing P1 or decreasing P2.
The first fluid from the first chamber 10 is introduced into the second chamber 20 through the nozzle 8. The nozzle 8 is situated downstream the inlet 4 of the second chamber 20. In the case of a plurality of inlets 4, the tip 12 of nozzle 8 is situated downstream the plurality of inlets 4.
Downstream of the inlet is defined as a position which is at a distance farther from the inlet in a direction from the first chamber to the second chamber.
The distance of projection of the outlet into the second cavitation chamber 20 with respect to the base 6 of the first cavitation chamber 10 is determined with respect to a diameter of the second cavitation chamber. Preferably, the distance above is the distance of projection of the tip 12 of nozzle 8 into the second cavitation chamber 20. The optimum distance is in the range of 0.1 to 0.15 times the diameter of the second cavitation chamber 20.
The distance of projection of the outlet into the second cavitation chamber 20 and a position of the inlet 4 of the second cavitation chamber 20 are determined with respect to tone another.
Preferably, the tip 12 of nozzle 8 projects into the second cavitation chamber 20 to a first distance H from a first end 7 of the second cavitation chamber 20. In the example of
Preferably, for the second apparatus 200 with multiple inlets in the second cavitation chamber 20, as illustrated in
One advantage arising from a nozzle arrangement as explained above is that it may help to prevent flow of the first fluid from the tip 12 of the nozzle 8 from interfering with the formation of the swirling flow of the second fluid in the second cavitation chamber 20.
The first apparatus 100 can have either of the nozzle arrangements described above or both of them. Similarly, the second apparatus 200 can have either of the nozzle arrangements described above or both of them.
The first chamber 10 has a first diameter and the outlet of the first chamber 10 has a second diameter. One useful range for the second diameter is for it to be around 0.7 to 0.75 times of the first diameter. The advantage of this is to provide turbulent flow conditions, as turbulent flow conditions are preferred for cavitation. This is because if the turbulence is higher, the lesser is the globule size resulting from the cavitated fluid. Smaller globule sizes are preferred in the emulsion.
There is a discharge zone 13 in the second cavitation chamber 20 near the tip 12 of the nozzle 8. Accordingly, the second cavitation chamber 20 is arranged to receive the first fluid through the nozzle 8 in the discharge zone. Once the first fluid is introduced into the second cavitation chamber 20, it then mixes with the second fluid, which is either rotating in the same direction or in the opposite direction.
When the first fluid is introduced continuously into the second chamber at a controlled rate, this assists the second fluid in mixing uniformly and continuously with the first fluid as the second fluid enters the second chamber through the second inlet or the plurality of second inlets, succeeded by intense cavitation of the mixture. A continuous mixing, arising from continuous introduction of fluid flow into the first and/or second chambers 10, 20 can help to provide a homogeneous emulsion.
Where water is used as the emulsifiable component, the percentage of the emulsifiable component by weight may be kept below 70%. If the percentage of the emulsifiable component exceeds 70%, there is a tendency for the emulsion to gel which may not be desirable.
The mixture subsequently passes through the resonance chamber 30, in which the pressure waves at certain frequencies which are close to the resonant frequencies of the resonating chamber are amplified leading to intense cavitation and homogenization of the mixture. The mixture after passing through the resonance chamber either goes to another working vessel for further treatment or goes directly to the consumer for combustion.
The construction described above for the first and second apparatus is a relatively simple arrangement with minimal numbers of component parts, imparting a compact nature to the apparatus. The absence of any moving parts and provision of a simple mechanical design leads to simplified maintenance requirements as well. The above advantages also provide a reduction in the associated costs.
In the examples of
The pressure inside the second cavitation chamber 20 is measured with a suitable pressure measurement device 32 fitted inside the cavitation chamber 20. The pressure measurement device 32 may be a suitable pressure sensor such as a piezoelectric pressure sensor. As illustrated in
The amount of fuel and the emulsifiable components supplied to the apparatus 100 and 200 may be controlled through metering pumps installed in the pipelines leading to the first cavitation chamber and second cavitation chamber.
In
Provided that the flow rate through first inlet 2 of the first chamber is f1, then the equivalent diameter d2 of at least one inlet 4 is determined by the following expression:
R≧d
2
≧d
1√(f2/f1)
wherein d1 is an equivalent diameter of first inlet 2, d2 is an equivalent diameter of at second inlet 4, R is the radius of second chamber 20, f1 and f2 are flow rates through inlets 2 and 4, correspondingly, d1=√(4S1/π), d2=√(4S2/π), where S1 is the total cross-sectional area of the first inlets and S1 is the total cross sectional area of the second inlets.
It is to be understood that the foregoing description is intended to be purely illustrative of the principles of the disclosed techniques, rather than exhaustive thereof, and that changes and variations will be apparent to those skilled in the art, and that the present invention is not intended to be limited other than as expressly set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201000404-2 | Jan 2010 | SG | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/SG11/00026 | 1/19/2011 | WO | 00 | 7/20/2012 |
