Hydrogeneration as an end product of a closed loop gaslift process employing LNG

A chemical compound or composition such as liquified natural gas or LNG with a critical temperature less than that of water is pumped into a subterranean well for injection near the bottom of the well. The chemical compound or composition changes to gas phase and rises in a column of water segregated in the well from an opposing column of water without gas. The water is heated to facilitate or effect the gasification of the chemical compound or composition. In one embodiment, such heating is accomplished by use of cooling water heated in cooling a refinery or heavy manufacturing operation, the column then serving as a cooling tower for the water to prepare it for recycling as cooling water in the refinery or heavy manufacturing operation. The gas/water mixture in the column forms a fluid of reduced density thereby being of less total weight than the column of water without gas. The difference in weight of the two columns provides a lifting force on the gas water mixture such that the effluent from the gas water mixture column will be elevated in relation to the free surface of the water only column. Such elevated quantities of water possess potential energy which can be converted into electrical or mechanical energy to be utilized as desired. Gas separated from the water is preferably collected and used for other purposes or recycled within the system.

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Description
RELATED APPLICATION

This application is a continuation-in-part of U.S. patent application Ser. No. 11/227,304, filed Sep. 15, 2005, pending, entitled “Hydrogeneration as an End Product of a Closed Loop Gaslift Process,” which is a continuation-in-part of U.S. patent application Ser. No. 11/197,081, filed Aug. 4, 2005, pending, entitled “Hydrogeneration as a By-Product of Electrolysis of Water” by Melvin Coddou.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to economical and environmentally compatible methods and apparatuses or systems for generating energy. In preferred embodiments, the present invention more particularly relates to improved methods and apparatuses or systems for hydrogeneration (the creation of electrical power by capturing the energy of falling water).

2. Description of Relevant Art

Hydrogeneration, hydropower and hydroelectric power are terms commonly used interchangeably within the electrical power industry. Hydrogeneration is a known and used form of generating electricity, and is considered especially valuable to the public because it is renewable, efficient, clean, reliable and flexible. (U.S. Army Corps of Engineers “Hydropower-Value to the Nation,” http://www.corpsresults.us/hydro/default.htm).

However, new hydrogeneration facilities are rare today even though public demand for electrical power continues to increase. Naturally occurring locations which provide the desired combination of water flow rates and elevation change (head) have been identified and, for the most part, utilized. For those sites which have not been exploited to date, environmental concerns created by the requisite damning of streams or rivers for hydrogeneration has further reduced the number of viable sites for development.

Nevertheless, interest remains in hydrogenation because it is clean energy. Moreover, considerable interest remains in developing new and efficient ways of generating pollutant-free energy.

SUMMARY OF THE INVENTION

In the present invention, a form of “gaslift” is combined with a preferably self-contained reservoir of fluid in a subterranean borehole, such as, for example, a cased water well, to create a synergistic process that affords a unique and flexible design for new hydrogeneration facilities. The process may be conducted at atmospheric pressure or in whole or in part under pressure greater than atmospheric pressure.

“Gaslift” refers to the lifting of a fluid, a liquid, by injecting and/or pumping compressed gas or liquid gas, such as for example liquified natural gas or LNG, at lower levels into a vertical column of the liquid, within a vertical column of liquid without gas. Liquid gas is converted into the gaseous state by heating after injection into the column. After original initiation of the process of the invention, the energy generated by the process itself will supply the energy for the heating. Generally, the injected gas (when in the gaseous state) creates upward movement of the liquid in the column as a result of the reduced weight of the gas/liquid column when compared to the normal hydrostatic head of the liquid without the gas. The buoyancy of the gas and the delta between the hydrostatic head of the liquid column without the gas and the hydrostatic head of the liquid column with the gas provides the energy to lift the liquid column with the gas up and beyond the liquid column without the gas.

The apparatus or system of the present invention requires a vertical column or tank of some height or depth most preferably in the form of a well or borehole drilled into the earth, and preferably capable of being at least partially pressurized. The well typically or preferably contains round conventional tubulars and has a diameter and casing suitable for effecting the purpose of the process of the invention as further described below.

Most preferably, the well is self-contained or closed (as opposed to being open to, or tapping, a natural aquifer or other liquid fluid source in the earth). Fluid, preferably water, is added to the well from a first reservoir with a free water surface at an elevation convenient to persons. This first reservoir may also be called the “lower reservoir,” or when water is the fluid being used, the “lower water reservoir.” Internal to the well is a tube (or tubes), of diameter smaller than the casing of the well, which extends to, or approaches, the bottom of the well and rises above the free surface of the lower reservoir. This internal tube (or tubular) is hereinafter referred to as the “production column” and it also contains fluid like or from the lower reservoir.

Just below the production column, a small injection port is provided. According to the invention, a specialized chemical compound or composition in liquid phase, such as for example liquified natural gas, is injected into the production column (and into the fluid such as water already in the production column). In the production column, the specialized chemical undergoes a phase change to gas created by the influx of heat from the fluid (water). This gas rises through the production column. The heat in the fluid (water) is provided by the compression/condensation processing of the specialized chemical, external heat sources such as oceans, rivers, other external process units, dedicated fueled heaters, dedicated electric resistance heaters (submersed in the water in the lower reservoir), and/or any combination thereof. In the case of heat provided by external process units, the invention may in one embodiment be used in conjunction with refinery or heavy manufacturing operations to provide a cooling tower for same. In this embodiment, cooling water is circulated amongst the process area of the refinery or heavy manufacturing facility to provide cooling, i.e., remove heat, and the heated water is then cycled into the process of the invention for heating and converting injected liquid gas into gaseous state gas. The water cools again as it rises in the production column, where it becomes ready again to circulate to the process area of the refinery or heavy manufacturing facility.

In some embodiments of the present invention, a mandrel may be used to create an annulus within the production column for containing the gas (mixed with the liquid fluid such as water) in the production column. Alternatively, in some other embodiments of the invention, a combination of production column tubulars which increase in diameter as the production column approaches the gas/liquid separation vessel may be used to change the gas/water ratio. If used, the mandrel or the changing production column sizes are preferably designed to adjust (at certain depths or periodically) the available volume of the gas/fluid flowing up the tubular so as to create a somewhat or relatively constant density of the gas/fluid mixture, and to thereby compensate for the constantly rising and therefore expanding gas. When the gas/fluid flowing up the tubular is under pressure (greater than atmospheric pressure), a mandrel or similar volume compensating device, element or design will not likely be needed.

The rising gas reduces the density of the gas/fluid or gas/water column when compared to the density of the fluid in the first reservoir, and in the fluid only (or water only) column. This reduction in density provides lift to the gas/fluid (or the gas/water) column. The two columns, that is, the gas/fluid column (or the gas/water column) and the fluid only column (or the water only column), in effect form the two legs of a manometer. The fluid (or water) that is lifted through the production column supplies a second free surface reservoir at an elevated height above the first reservoir. The gas which has risen with the fluid is preferably separated from the fluid, captured, and either returned to a liquid phase and reinjected into the production column or routed for other uses. That is, the gas may be cycled in a closed loop process to optimize the utilization of heat transfers available from the fluid or water for phase change of the specialized chemical from a gas to a liquid and then back to a gas. Alternatively, the process may be an economical and environmentally compatible way of returning certain gases such as liquefied natural gas back into their gaseous state for other uses.

In providing a “lift” gas source for the present invention, it is critical that the specialized chemical: (1) phase change from liquid to gas at the bottom and inside the production column and (2) phase change from gas to liquid at or above the second or upper reservoir. Gas collection and compression (and if desired re-liquefication) occur at the second or upper reservoir elevation. The specialized chemical compound or composition in liquid phase follows a liquid hydrostatic column between the second or upper reservoir and the bottom of the production column. Most preferably, a small, well-insulated tubular provides the means to inject small quantities of the specialized chemical in liquid phase into the bottom of the production column.

Preferably, in the process of the invention, the temperature of the water or fluid in the production column is greater than the critical temperature of the specialized chemical compound or composition so that, upon injection, the liquid phase of the chemical will quickly change to the gas phase, extracting the heat for the phase change from the water. When liquified natural gas is used as the specialized chemical, typically being delivered at −260° F. at atmospheric pressure, considerable heating of the water is needed to facilitate the gasification. However, the electrical power generated by the process of the invention will provide more than enough heat for this purpose.

The method or process of the invention is particularly unique in that it can be used to generate energy without creating or causing pollutants typically associated with energy generation processes requiring petroleum, coal or nuclear fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view schematically representing the apparatus of the invention providing for the gaslifting of a fluid such as water by utilization of a specialized chemical compound or composition.

FIG. 2 is a schematic of the bottom portion of the apparatus of FIG. 1 showing the arrangement of the injection point for the specialized chemical compound or composition relative to the production column such that gas will be generated within the annulus between the production column and its mandrel, or such that gases will rise and enter the annulus between the production column and its mandrel, and further showing that the annulus between the well casing and the production column remains void of generated gases and thus maintains its ambient condition of hydrostatic head.

FIG. 3 is a schematic of the upper portion of the apparatus of FIG. 1 showing the effluent of the gas/fluid (or water) mixture flowing out of the production column into a vessel designed to separate the gas from the fluid or water with the fluid or water being released to the upper reservoir.

FIG. 4 is a schematic of a tapered internal mandrel for the apparatus of FIG. 1 which will maintain the gas/fluid ratio as the gas expands during its rise to the top of the production column.

FIG. 5 is a schematic showing an embodiment of the apparatus of the invention where an attachment inside the production column will cause the rising bubbles of gas to break apart and immediately reform into a multitude of smaller bubbles thereby reducing the formation of slug flow.

FIG. 6 is a schematic showing an embodiment of the apparatus of the invention where an attachment inside the production column will collect rising small bubbles of gas, coalescing them into larger bubbles which are periodically released to travel further upward thus promoting slug flow.

FIG. 7 is a schematic showing an embodiment of the apparatus of the invention where an internal arrangement to the production column will retard and disburse the gas bubbles into smaller individual units as the bubbles travel upwards and pass through a bed of granulated particles.

FIG. 8 is a schematic of an embodiment of the invention showing the path of water as it recycles within a closed loop, a portion of which provides the potential energy of elevated water for utilization in a hydrogeneration process.

FIG. 9 is a sectional view schematically representing an apparatus of the invention similar to the one schematized in FIG. 1 providing for the gaslifting of a fluid such as water by utilization of a specialized chemical compound or composition, but particularly adapted for use with specialized chemicals such as liquified natural gas having a lower density than water and being delivered at extremely cold temperatures such as minus 260° F. typical for LNG, showing a pump which may be useful in injecting the fluid at the desired depth and showing an electric resistance heater for heating the water.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In preferred embodiments, the present invention employs a closed loop gaslift of water to obtain usable energy. Other liquids could be substituted for water without violating the basic principals of the invention. The present invention focuses on water as the preferred liquid to be lifted because water is common, inexpensive, benign under normal conditions, and well understood.

The gaslift process of the invention is initiated by injecting a “specialized” chemical compound or composition in liquid phase near the bottom of a subterranean, preferably closed or contained water well. The chemical compound or composition is “specialized” because it is selected, prepared or synthesized to have certain properties for use in the present invention. Although these properties are discussed in more detail below, one such property is critical temperature. The specialized chemical should have a critical temperature below that of water so the chemical undergoes a phase change in the water from liquid to gas. The gas rises in a column of water (called the “production column”) segregated in the well from an opposing column of water without gas. The gas/water mixture has less density and less total weight than the column of water without gas. The difference in weight of the two columns provides a lifting force on the gas/water mixture such that the effluent from that gas/water mixture column is elevated in relation to the free surface of the water only column. Ideally, this flow upwards of the gas/water mixture continues as long as gas is formed at the bottom of the production column and the well continues to have a lower reservoir of water and a separate column of water without gas. The elevated gas/water mixture possesses potential energy which, preferably after or upon removal or separation of the gas, can be converted into electrical or mechanical energy to be used as desired. The water, with the gas removed, is preferably returned to the lower reservoir for further recycling through the closed well system. The gas may be recycled as well, preferably by returning it to a liquid state for re-injection into the well and then repeat of the cycle for energy generation. In some alternative embodiments, however, the gas may not be recycled or may be used for other purposes. Liquefied natural gas (LNG) is an example of a specialized fluid that would likely be delivered from an external remotely located liquefaction facility for use in the process of the invention. As the LNG is passed through the apparatus of the invention and gasified, the gas will be exported from the apparatus for external distribution.

Typically, when the gas is to recycled in the invention, a compressor/condenser positioned at or near the top of the production column is used to convert the specialized chemical compound or composition from its gas phase to its liquid phase. For recycling into the well for generating energy, this liquid is routed to a vertical column, parallel to but separate from the production column, which connects to the bottom of the closed well casing and enters the production column. When liquid gas, such as liquefied natural gas, that has not been used previously in the invention, is to be used, it is also routed to this vertical column. This vertical routing causes the specialized chemical in liquid form to have a hydrostatic head possibly equal to or greater than the hydrostatic head of the parallel water column. As the specialized chemical enters the production column (already containing water), the chemical converts back to its gas phase as a result of absorbing heat from the water. As a gas, the specialized chemical rises with the water, forming a gas/water mixture within the production column, and returns to the top of the column, elevating the water to the gas/water separation vessel.

The chemical properties of the specialized chemical are key to the efficiencies of this present invention. Of particular interest to the technical feasibility of the present invention are the following properties:

a. Latent heat of vaporization—This property determines the amount of energy required to cycle the specialized chemical between its liquid and gas phases. Chemicals requiring lower amounts of energy are preferred;

b. Critical temperature—Critical temperature is the lowest temperature that the fluid will remain in the gaseous state regardless of pressure. The closer this temperature is to ambient atmospheric conditions, the more practical the specialized chemical's phase change from liquid to gas; the phase change of the specialized chemical is triggered by or dependent on the temperature of the water (or other fluid) in the subterranean well, including the production column. When the specialized chemical has a lower critical temperature than the critical temperature of fluid (such as water) in the well, the well fluid will “heat” the specialized chemical sufficiently to cause it to phase change from a liquid to a gas;

c. Liquid density—This property relates to the hydrostatic head of the fluid (or water) column with respect to the hydrostatic head of the column containing only specialized chemical in liquid form (the injection line) and also with respect to the hydrostatic head of the column containing fluid (or water) and specialized chemical. If the liquid density of the specialized chemical is equal to or greater than that of the fluid (or water), the hydrostatic head of the liquid column of the specialized fluid will always be greater than the head of the water column. If the liquid density of the specialized chemical is less than that of the fluid (or water) as is the case with liquefied natural gas, the specialized fluid may require mechanical assistance such as provided by pumps to obtain the required pressure to effectively enter the production column;

d. Gas density—Lighter gases are preferred because they provide more buoyancy and a greater reduction in the density of the gas/fluid mixture;

e. Solubility in other liquids, particularly water—Specialized chemicals that are less soluble in water (or other fluid in the subterranean well) are more effective and efficient in the present invention.

One example (without limitation) of a known fluid that functions well as a specialized chemical for purposes of the present invention is liquified natural gas or LNG. Another example is tetrafluoromethane (R14). R14 has the following properties:

a. Latent heat of vaporization—58.34 BTU/lb

b. Critical temperature—−49.9° F.

c. Liquid density—100.072 lb/ft3

d. Gas density—0.232 lb/ft3 @ standard temperature and pressure

e. Solubility in water—0.00122 lb/ft3

The height of lift for the fluid (or water) in the production column in the gaslift cycle of the invention is limited by the practical and economical configurations of the apparatus. As the depth of the subterranean well increases, and more particularly as the design depth of the apparatus of the invention increases, so increases the associated height which the fluid (or water) may be lifted from the well by way of the production column. Generally, the combination of quantity of elevated fluid (or water) and its relative height determines the potential energy which can be captured from the system. The potential energy of the lifted fluid (or water) can be converted to usable energy, preferably in a hydrogeneration or hydroelectric generation scheme with the fluid (or water) being preferably returned to the lower reservoir for recycling through the well system again and again.

In preferred embodiments of the present invention, water cycles in a closed loop as illustrated in FIG. 8. In addition to providing the mass required for the creation of the potential energy at the elevated reservoir, water also provides the means and mass to transfer the necessary heat associated with the phase change of the specialized chemical. During the liquid-to-gas phase change of the specialized chemical, water is utilized to add heat to the specialized chemical causing it to vaporize into a gas. In embodiments where the gas is to be returned to its liquid phase (for example for recycling in the process of the invention), the water is utilized to take heat away from the gas, gas compression and condensation equipment to promote or facilitate phase change of the gas back to its liquid phase.

A number of variables may be optimized to maximize the preferred performance of the gaslift process of the invention. These variables include closed well casing diameter and depth, upper and lower reservoir elevations and size, water flow rates, gas production rates, operating pressure of the gas/water separation vessel, production column diameter and shape, internal devices to enhance gas lifting such as a mandrel internal to the production column, gas bubble dispersion or coalescing devices and or chemical modifications to the water. The design basis will define the relationships of the variables such that they are supportive of each other with respect to the process of the invention.

Referring again to the Figures for further understanding of the invention, FIG. 1 depicts a cross sectional elevation view of a closed well system of the invention for gaslift of water comprising conventional circular (round) tubulars 52 and well casing 55, a gas/water separation vessel 22, a gas compressor 24, a heat exchanger 26, a condenser 28, specialized chemical injection line 30, and the hydrogenation apparatus 44. Schematic arrow 1 represents the flow of the specialized chemical as it leaves the gas/water separator 22 as a gas and goes into the compression/condensation process to be phase changed to a liquid. The specialized chemical in liquid phase is injected into the production column 52 wherein it phase changes to gas at or near schematic arrow 2. Schematic arrows 3 and 4 represent the flow of water being warmed, wherein the water absorbs heat from the compression and condensation process of liquefying the special chemical, while providing the required cooling for the gas as it is compressed and condensed. The water coming from the production column has been cooled by the expanding gas, then the cool water is used to cool the compressors (refrigeration compressors and gas compressors) which are necessary in this embodiment to liquefy the gas for recycling to the bottom of the production column. (The closed loop for the refrigerant cycle associated with the condenser is not shown nor is the cooling water routing for this equipment.) Schematic arrows 5 and 6 represent the water leaving the gas/separation vessel and entering the upper reservoir 40. Schematic arrows 7 and 8 represent the water in the upper reservoir 40 passing through the hydrogeneration apparatus 44 as it is routed to the lower reservoir 42 to be recycled through the closed well system.

Injection of the liquid specialized chemical into the production column 52 will not require any mechanical device such as a pump provided the liquid density of the specialized chemical (ρl) is greater than the density of water (ρw) times the height of the water column (D) divided by D plus the height between the reservoirs (H).

    • ρl>ρw(D/D+H)
      This relationship is important in establishing the basis of design for a closed well system. The hydrostatic head of the specialized chemical will provide the data for designing or planning the depth and or requirement for pumping of the specialized chemical to the injection quill 34 to optimize the water lift rate.

The amount or extent of elevation of the upper reservoir 40 will be determined by the gas to water ratio (density), operating pressure of the gas/water separation vessel 22, the flow rate, and the depth of the injection quill 34 within the production column 52, which are all part of the basis of design for the particular system. The column of gas/water within the production column 52 has a total weight less than that of the water column 54. This variation in hydrostatic pressure (weight) creates the upward lift of the production column 52. This lift will continue to some height greater than the free surface of the lower reservoir 42 causing the gas/water mixture to rise above the free surface of the upper reservoir 40. As the water emits from the production column 52 at its upper limit and falls or flows under pressure from the gas/water separation vessel 22 into the upper reservoir 40, the gas having been separated from the mixture and captured by a gas/water separation vessel 22 for removal or further processing.

The relationship amongst the injection quill 34, closed well casing 55, production column 52 and the mandrel 36 is illustrated in FIG. 2, a sectional view of the closed well. The rate of liquid injection and subsequent gas formation and the depth at which the gas is created forms the basis of design for the cross sectional area contained within the production column 52. At the bottom of the well immediately above the point of injection of the specialized chemical, the gas volume will be its smallest as the hydrostatic pressure containing the gas will be its largest. As the gas rises within the annulus created by the production column 52 and the mandrel 36, the gas will experience decreased hydrostatic pressure and will thereby increase in volume. The mandrel 36 creates a decreasing cross sectional area resulting in an increase in cross sectional area of the annulus as the depth decreases. This in effect will offset the changes in gas volume such that the density of the mixture of gas and water remains somewhat constant in accord with the basis of design for the particular apparatus. Water flow schematic arrows 62 and 64 indicate the direction of the water flow before the water enters the production column and mixes with the gas 60 which is produced at injection quill 34. As the gas 60 mixes with the water, the density of the water is reduced, causing the gas/water mixture to flow upward as represented by schematic arrow 66. The mandrel 36 is shaped such that its cross sectional area gets progressively smaller going upward. This reduction in the cross sectional area of the mandrel 36 facilitates a progressively larger cross sectional area of the annulus between the mandrel 36 and the production column 52. This increase in area accommodates the increase in gas 60 volume which results from the reduction in hydrostatic pressure as the gas 60 moves upward, thus providing for a reasonably constant density along the entire height of the production column 52.

FIG. 3 is a sectional view of the upper portion of a closed well system of the invention showing the gas/water mixture entering the gas/water mixture separation vessel 22 which allows the gas to separate from the water. The gas is then piped away from the closed well system to be recycled. The water falls to the bottom of the separation vessel 22 and exits the vessel by way of a P-trap, or pressure control valve, for example, into the upper reservoir 40. The top of the closed well casing 55 is below the surface of the lower reservoir 42 and open to the water in the lower reservoir 42 such that a constant supply of water and its inherent hydrostatic head is present in the closed well system. The mandrel 36 concludes close to but below the top of the production column 52 as the gas volume is maximum at the top of the production column 52. Not shown in this FIG. 3 but illustrated in FIG. 1, the upper reservoir 40 releases a flow of water as represented by schematic arrow 7 to the lower reservoir 42 by way of an apparatus such as a hydrogenerator 44, for example, which will convert the potential energy into electrical power.

FIG. 4 is a sectional view of the lower portion of a closed well system depicting the formation of gas 60 at the injection quill 34. The bubbles will rise with, and in relationship to, the flow of the water 66. That is, the bubbles will travel faster towards a higher elevation than the water. The gas/water mixture is of lower density than the water without the gas. A direction of flow is created which is downward for the water only, or the water without the gas, as represented by the schematic arrow 62 in the annulus between the closed well casing 55 and the production column 52. The flow changes direction at the bottom of the well as represented by schematic arrow 64 and the flow proceeds upward inside the production column as a gas/water mixture represented by schematic arrow 66.

FIG. 5 shows an embodiment wherein a device such as a fine mesh screen 70 or other mechanical device is inserted periodically internally along the height of the production column 52 to cause the rising bubbles of gas 60 to break apart and reform into much smaller and more numerous bubbles as the bubbles pass through the device 50. These devices 50 and their resulting bubble configuration may or may not utilize the mandrel 36. This embodiment may prove more effective in combination with or without the mandrel 36.

FIG. 6 shows an embodiment wherein an internal device 72 traps smaller individual bubbles of rising gas and prevents their rising further until such time as a sufficient quantity of gas is accumulated which will open a weighted gate upward releasing the coalesced gas bubble 60. This trap 72 will be located periodically internally along the height of the production column 52 such that the slug flow promoted by larger bubbles may increase the efficiency of the invention by elevating larger quantities of water to a predetermined elevation than achieved with smaller bubbles as envisioned in FIG. 5. This embodiment may be more effective in combination with or without the mandrel 36.

FIG. 7 shows an embodiment wherein the mandrel 36 shown in FIGS. 2-6 is not used. Instead of a mandrel, a bed of fine particles 76 (such as sand) is periodically placed or spaced internally along the height of the production column 52. These beds of sand 76 rest on porous support structures 74 internal to the production column 52 such that water and gas bubbles can flow through easily. As the bubbles 60 congregate at the bottom of the sand and collect enough buoyancy to raise and locally disperse the sand bed 76 either in its entirety or by forcing pathways through the sand bed 76, the sand bed 76 becomes “quick” and very fluid. This allows a gas bubble to pass through, and the passing of the gas bubble through the sand causes the bubble to break apart into many smaller bubbles 60 as it rises upward. The sand particles will reform into a bed 76 on support 74 pending further gas collection wherein the process will repeat itself. The newly formed bubbles 60 will immediately begin increasing in size with their rise. Additional support structures 74 and sand beds 76 are placed periodically along the height of the production column 52 so that the density of the gas/water mixture will be optimized for maximizing water flow and upper reservoir 40 elevation.

FIG. 8 is a sectional elevation view schematically representing the utilization of the potential energy from the water having been elevated by the gaslift process and then falling through a hydrogeneration apparatus 44. Water 82 elevated by the gaslift process is temporarily held in the upper reservoir 40 pending its flow downward and into a hydrogenerator 44. As the water 82 passes through the hydrogenerator 44, the water's potential energy is converted to electrical energy before the water is returned to the lower reservoir 42 as the water 84 exits the hydrogenerator 44. The power generated 80 could be exported to other end users and/or routed as energy to power or help power the compression and condensation of the specialized chemical compound or composition.

FIG. 9 depicts a cross sectional elevation view of a closed well system of the invention for gaslift of water similar to that shown in FIG. 1 but adapted for specialized chemical compositions or compounds such as liquefied natural gas being delivered to the apparatus in a liquid state and having a liquid density less than the liquid density of water. In this embodiment, a specialized fluid pump 29 is provided to pump the chemical into the well for injection in the column. In this particular example, an electric resistance heater 86 is provided for heating the water in the column to effect the phase change of the liquefied natural gas into a gaseous state. As stated above, other means can be alternatively used to heat the water. In this embodiment when liquefied natural gas is the specialized chemical, recycling of the liquefied natural gas (or return of the liquefied natural gas to a liquid) is not intended, as the gasification of the liquefied natural gas is a desired product of the process of the invention. Equipment associated with the liquefication of the specialized chemical is thus not needed for this embodiment.

All of the Figures are without scale in any direction. The Figures are intentionally dimensionless as the design of the system requires specific interrelationships among depth, diameters, pressures, flow rates, reservoir elevations and component shapes.

Mathematical Model

A mathematical model is utilized to further describe the present invention and to explain some of the relationships among the key components. As noted on FIG. 1, “H” represents the height between the upper reservoir 40 and the lower reservoir 42. This “H” also represents the height available for the water to fall for its conversion from potential energy to electrical energy. H must be limited, to allow the outward flow of water at the top, to a height slightly less than that which can be obtained by the gas/water mixture in the production column 52 as influenced by the hydrostatic head of the water column 54 in the closed well casing 55. The “D” represents the depth from the free water surface of the lower reservoir 42 to the injection quill 36 or more specific, the hydrostatic head of the water only column.

Important values are:

    • a. ρw=specific density of water=62.4 #/ft3
    • b. ρg=specific density of specialized fluid gas phase=0
      • (Relative to ρw, ρg is treated as 0)
    • c. ρm=specific density of gas/water mixture
    • d. Vw=Volume of water in production column
    • e. Vg=Volume of gas in production column
    • f. Vt=Volume of gas/water mixture in production column
    • g. PE=Potential energy of water in upper reservoir
      • PE=Vw*ρw*H

Solving PE in terms of D requires the following steps:

a. Analogous to a manometer, depth of the closed well times the specific density of water must equal the height of the production column 52 (closed well plus the height of the elevated reservoir) times the specific density of the gas/water mixture:

    • D*ρw=(H+D)*ρm

b. Solving equation “a” above for H yields:

    • H=D*((ρw/ρm)−1)

c. Solving ρ in terms of V:

    • ρm=(ρw*Vw+ρg*Vg)/(Vg+Vw)
    • Vg+Vw=Vt
    • ρg*Vg goes to 0 since gas density is considered 0
    • ρm=(ρw*Vw)/(Vt)
    • ρw/ρm=Vt/Vw

d. Solving line b above for H in terms of V:

    • H=D*((Vt/Vw)−1)

By substituting the value for H according to line d above into the formula PE=Vw*ρw*H (from line g paragraph [0050]), you have Potential Energy of the elevated reservoir in terms of D and V:

a. PE=Vw*ρw*D*((Vt/Vw)−1)

b. PE=D*ρw*(Vt−Vw)

Since ρw is a constant, it is dropped from the formula and since Vt−Vw equals Vg, the shortened formula for potential energy of the water in the elevated reservoir is:

a. PE=D*Vg

The formula PE=D*Vg is counter-intuitive to the basic idea of potential energy. This formula says the potential energy of this present invention is dependent on the depth of the well and the volume of virtually weightless gas rather than the height of the upper reservoir and its volume of water with its inherent weight. In other words, the amount of Potential Energy that can be made available from the elevated upper reservoir 40 is dependent theoretically or primarily upon the amount of gas (Vg) available to the system and the depth (D) of the well.

Vg, as part of a closed loop, is a basis of design constant which requires a definitive amount of input energy to maintain its availability. Since the closed loop cycles between gas phase and liquid phase the theoretical energy requirements are those for (1) heat of condensation and (2) heat of vaporization. The energy required to go from gas phase to liquid phase and the other is the reverse of going from liquid phase to gas. They are equal but opposing values, i.e. negative versus positive numerical values.

Provided the specific density of the liquid phase of the specialized fluid is such that its value times the total height of its supply routing is greater than the specific density of water times the height of the closed cased well 55, the liquid phase of the specialized fluid will flow into the production column 52 without external energy. In other words, the hydrostatic head of the specialized fluid liquid phase is greater than the hydrostatic head of the water column 54 and therefore the specialized fluid liquid phase will flow into the water column 54 on its own accord. Additional pressure may be required for operational efficiency and or to compensate for low liquid density of certain specialized chemicals. This additional pressure can be created by including a pump(s) in the liquid leg of the specialized chemical process cycle.

The present invention creates and captures through gaslift usable energy from the phase change and flow of a specialized chemical between the chemical's liquid phase and gas phase. This energy can itself be used for powering the process and/or can be used for other general purposes. The invention enables electrical power to be produced at a more economical cost than prior art methods and provides a power generation scheme that is simplified and relatively safe. Further, the power generating scheme will not result in significant detrimental effects on the environment and/or nearby personnel in the event of operator error which results in unexpected system upset or even shutdown. Accidental or sabotaged release of the primary components, a specialized fluid (which is preferably non-toxic) and water, of the scheme is relatively benign when compared to high pressure steam systems fired by fossil or nuclear fuels.

The invention allows for the design of smaller, localized, electrical power generation facilities. Providing an electrical power supply closer to the end user reduces the “line loss” inherent in long power transmission systems and reduces overall pollutants associated with prior art electrical power generation systems. The facilities can be integrated into urban areas close to end users.

The invention should significantly advance the reduction of “greenhouse gases” and other pollutants associated with contemporary methods of electrical power generation. In addition, the present invention reduces: (a) capital expenditure for the design and construction of new power generation facilities; (b) maintenance expenses as documented by comparative analysis of various schemes with hydroelectric power generation unit maintenance costs being orders of magnitude less than gas, nuclear, coal or others; (c) operational expenditures for personnel, fuel, insurance, and overhead required for contemporary power generation; and (d) production loss of electrical energy by long distance transmission typically required by contemporary power generation facilities.

The invention also provides an economical and environmentally compatible way to re-gasify liquidized natural gas (liquidized for ease of transport but more useful in gaseous form). Further, the invention provides a use for water heated in cooling certain refinery and heavy manufacturing operations and a way to cool the water for further use in such operations

The invention has been generally described with respect to embodiments comprising a single well with a single production column demonstrating the cause and effects of the gaslift and how gaslift can be utilized to produce usable electrical power. The invention is also applicable to multiple wells and to single wells with multiple production columns.

In an embodiment employing multiple wells, the wells are constructed in close proximity to each other to create a collective system wherein the elevated water is collected into a common elevated reservoir thus increasing the size and output of the hydroelectric generation system. Such multiple wells allow a system design to optimize selection of the most economical hydroelectric generator by adjusting water volumes by the number of closed wells and individual capabilities of each well.

Similarly, a single closed well could be constructed of sufficient diameter to include multiple production columns 52. The output of elevated water from these production columns could then be collected to a common elevated reservoir.

The foregoing description of the invention is intended to be a description of preferred embodiments. Various changes in the details of the described methods and apparatuses for accomplishing the methods can be made without departing from the intended scope of this invention as defined by the appended claims.

REFERENCE NUMBERS

    • 1 Gas leaving the separation vessel
    • 2 Specialized fluid entering production column
    • 3 Water entering cooling process
    • 4 Water leaving cooling process
    • 5 Water leaving separation vessel
    • 6 Water entering upper reservoir
    • 7 Water entering hydrogeneration process
    • 8 Water leaving hydrogeneration process
    • 22 Gas/water mixture separation vessel
    • 24 Gas compressor
    • 26 Heat exchanger
    • 28 Gas condenser
    • 30 Specialized fluid liquid delivery tubular (injection line)
    • 32 Check Valve
    • 34 Injection quill
    • 36 Mandrel
    • 40 Upper reservoir
    • 42 Lower reservoir
    • 44 Hydrogeneration equipment
    • 52 Production column
    • 54 Water column (without gas)
    • 55 Closed well casing
    • 60 Gas bubble
    • 62 Schematic arrow showing direction of flow
    • 64 Schematic arrow showing direction of flow
    • 66 Schematic arrow showing direction of flow
    • 70 Mechanical device to disburse bubbles
    • 72 Mechanical device to coalesce bubbles
    • 74 Mechanical device to support particle bed
    • 76 Bed of fine particles such as sand
    • 80 Electrical power outlet
    • 82 Water leaving production column
    • 84 Water leaving hydrogeneration process

Claims

1. A method for generating energy comprising:

providing a tank or well containing at least two columns of the same fluid;
injecting a chemical having a critical temperature less than that of the column fluid, in liquid phase, near the base of one column;
allowing the temperature of the well fluid to cause said chemical to change from liquid phase to gas phase;
allowing the gas to rise in the column, thereby elevating the column of the fluid with the gas above the column of well fluid without the gas, thereby creating potential energy;
capturing said potential energy;
converting at least a portion of said potential energy into electrical or mechanical energy; and
separating the gas from the column fluid at the surface of the well.

2. The method of claim 1 wherein the well is a closed well and the well fluid is added to the well prior to injection of the chemical liquid.

3. The method of claim 1 wherein the column fluid is water and the chemical has a density less than water, and wherein the method further comprises means for heating the water and means for pumping the chemical into the column.

4. The method of claim 3 wherein the chemical is liquified natural gas.

5. The method of claim 2 wherein said columns are pressurized and at least a portion of the step of gas rising in the column is conducted at pressure greater than atmospheric pressure.

6. The method of claim 1 wherein the steps are repeated in multiple wells constructed in sufficient proximity to each other to create a collective system wherein the elevated fluid is collected into a common reservoir.

7. The method of claim 1 wherein there are three or more columns of the same fluid and the chemical having a critical temperature less than that of the column fluid, in liquid phase, is injected near the base of multiple column, leaving at least one column to have column fluid only.

8. A system for generating energy using a chemical which changes from its liquid phase to its gas phase, wherein said chemical has a critical temperature less than water, said system comprising:

a well or external columnar tank having a supply of water at its base;
at least two separate internal columns extending substantially the depth of the well or external columnar tank and extending into the water;
an injection means at or near the base of one of the columns in the water;
a pump for pumping liquid phase gas to the injection means;
means for heating the water to facilitate the transition of the chemical from its liquid phase to its gas phase;
means for channeling gas mixed with water through said one column, such that said gas and water mixture can be brought to the surface of the well by gaslift;
means for capturing the energy from said gaslift;
means for employing at least some of said captured energy in creating electricity; and
a separator for separating gas from said water at or near the surface of said well.

9. The system of claim 8 further comprising means for pressurizing said columns of water.

10. The system of claim 9 wherein said means for capturing the energy of elevated water from said gaslift comprises a hydrogenerator for converting water energy to electricity.

11. The system of claim 8 wherein said means for heating the water is provided by cooling water heated from use in cooling a refinery or heavy manufacturing operation.

12. The system of claim 11 wherein said column acts as a cooling tower for said heated water.

Patent History
Publication number: 20070039728
Type: Application
Filed: Dec 22, 2005
Publication Date: Feb 22, 2007
Inventor: Melvin Coddou (Houston, TX)
Application Number: 11/315,872
Classifications
Current U.S. Class: 166/244.100
International Classification: E21B 41/02 (20060101);