GB2032008A - Method of and means for generating hydro-electric power - Google Patents

Abstract

A turbo-generating system in which the turbine and associated feed means are located beneath the surface of a body of water. Valve means operatively associated with such feed means provide metered flow of water to the turbine from the surrounding body of water which itself acts as a forebay for the system. A reservoir is disposed subjacent the exit port of the turbine in water-tight communication therewith. The reservoir is of sufficient capacity to permit free flow of water from the turbine while concurrently allowing for the build up within the reservoir of a head of water sufficient to effect discharge of water from the system through means disposed in flow communication with the reservoir. The discharge means is oriented in a plane generally parallel to the immediately overlying water surface and extends from the reservoir a distance sufficient to permit discharge of water from the system against a head less than that used to drive the turbine by utilizing the curvature of the earth to reduce the head against which the water must be discharged from the system. <IMAGE>

Description

SPECIFICATION Method of and means for generating hydroelectric power One of the principle problems facing this country within the next several decades is a potential energy shortage. Current efforts at solving this problem have been directed to the negative approach of having the country use less energy. While this may postpone the problem it in no way provides a solution. If a solution is not forthcoming in the immediate future the world faces an industrial slowdown which can only have dire socio-economic effect Qn ali peoples of the world. It has been forecasted by reliable sources that the world's need for oil, one of the primary sources of today's energy, will outrun the supply by the end of the century and possibly sooner. This makes the development of alternative sources of energy a national imperative.This invention is directed to the development of such an alternative source and provides a unique method and means for extracting energy from large bodies of water which is pollutionless, does not deplete or degrade our natural resources and is for all practical purposes limitless in its capacity for power generation.

The manner in which the foregoing, as well as other objectives and advantages of the invention may best be achieved will be more fully understood from a consideration of the following description, taken in light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a cross sectional elevation of a turbo-generating system utilizing principles of my invention; Figure 2 is a graph depicting the operating characteristics of a reaction turbine of the type preferably to be used in the disclosed system Figure 3 is a graph showing still other characteristics of a reaction turbine relevant to the method of operation comprising my invention; Figure 4 is a graph illustrating values of kinematic viscosity for water at various degrees of temperature; and Figure 5 is a plot of Reynolds numbers vs friction factors for a clean steel or wrought iron pipe.

DESCRIPTION OF THE PREFERRED EMBODIMENT With specific reference to the drawing there is shown in Figure 1 one structural arrangement utilizing my method of operation. A reaction turbine 10 is positioned beneath the surface 12 of a body of water 14 at a depth sufficient to provide a desired operating head of water. In the illustrated embodiment water is allowed to enter the system through a gate or control valve 16 located in the upper part of an inlet pipe or penstock 18 also positioned in its entirety beneath the surface of the water. A screen or filter 20 is interposed in the line between the inflowing water and the valve to insure that no sediment or debris enters the system. By manipulation of the valve 1 6 the quantity of water desired to drive the turbine 10 can be adjusted in accordance with demand placed on the turbine.In certain instances the valve can be used as a control means for achieving equilibrium between the rates of flow of water to and from the turbine. The arrangement, as will be seen, utilizes the overlying and surrounding body of water 14 as a forebay to furnish water to the system through the inlet pipe 18 in measured quantities as regulated by the control valve 1 6.

Water admitted to the system through operation of the control valve 16 flows down the inlet pipe 1 8 a distance corresponding to the operational head desired. In the illustrated embodiment the operating head has been chosen to be of the order of about 145 feet. Water entering the system through the control valve drops through this head impacting the turbine runners in the conventional manner. As in the operation of any such turbine, water under pressure enters the spiral casing 22 which encircles the unit Since water is flowing into the runner around its entire circumference the cross sectional area of the casing 22 decreases in proportion to the decreasing volume of water to be handled. By comparing the left and right hand sides of the drawing this decrease in area can be observed. It should be understood that use of the inlet pipe 18 is optional.The system can also operate by simply disposing the metering valve 16 in the inlet port of the turbine so as to communicate directly with the spiral casing 22. In such an arrangement the overlying body of water furnishes the operating head desired without the use of an inlet pipe. From the casing 22 the water flows through passageways between guide vanes 24 which serve to give the water a direction as near tangential to the turbine runners, or lead edges of the runner buckets 25, as is practicable thereby to extract maximum energy from the impacting water stream. Water exits from the runners through the draft tube 26. From here the water is directed into an underwater reservoir 28 from which it ultimately is discharged back to the surface of the water through an underwater pipeline 30. The system thus described forms the basic operational unit comprising the invention.

The pipeline extends from the reservoir in a direction generally parallel to the immediately overlying surface of the water above the reservoir and runs a distance which based on the curvature of the earth is designed to reduce the head against which the water must be lifted. The distance the pipe is extended from the reservoir is chosen so as to insure that the energy needed to discharge the water from the system is less than that generated by the system. By running the pipe in a generally north-south direction, when constructing the system in the northern hemisphere, the centrifugal force generated by the rotation of the earth can be used to assist in the discharge of-water from the system thereby to increase its efficiency. It should be understood that operation of the system is not dependent upon use of this force.It is simply a refinement for improving the operation of the system. A preferred arrangement is to build a reservoir 28 of sufficient size both to permit free exit of water from the draft tube 26 and build up of a head 32 within the reservoir sufficient to overcome flow losses within the pipeline 30 and to cause flow of water through the pipeline at the desired velocity. Alternatively or conjointly with such an arrangement one or more pumping stations 34 can be interspersed along the pipeline 30 at periodic intervals to keep the water moving at the required velocity and quantity of discharge.

It is essential to the operation of the system that the discharge end of the turbine be kept clear to permit free discharge of water from the turbine. By providing a reservoir of sufficient size this can readily be achieved along with the other objectives mentioned above.

Now turning to the specifics of such a system the operating characteristics of a reaction turbine of the type preferred for use in the abovedescribed system are shown in Figures 2 and 3. As seen in those figures a turbine running at a rotational speed of 600 rpm, under an operating head of about 142 feet, performs at near peak efficiency and delivers about 620 horsepower.

Referring to Figure 3 it will be seen that a turbine operating under these conditions has a discharge rate of about 45 cubic feet per second. To insure uninterrupted flow from the exit port of the turbine under these conditions of operation requires that water exit from the pipeline 30 at the same rate as water is being discharged from the turbine. As previously noted one manner of achieving this is ta maintain a head 32 within the reservoir sufficient both to push the water through the pipe at the required rate and to overcome friction losses in the pipeline. Alternatively a discharge pump 40 can be disposed within the pipeline 30 either to assist the head maintained within the reservoir or to replace the need for maintaining a driving head of water within the reservoir. To insure proper pump operation it is required to maintain a certain minimum head of water within the reservoir.

If it is assumed that the system will employ water having a temperature of 50 degrees fahrenheit it will be seen by reference to Figure 4 that its kinematic viscosity is given as .000015 square feet per second. If the diameter of the pipe 30 is selected to be 4 feet the velocity of flow required to discharge 45 cubic feet per second is given by the formula Q= AV. The velocity of flow given the above parameters of operation is 3.5828 feet per second. With the velocity and the kinematic viscosity known the Reynolds number for the system caji be determined from the formula R = LV/u. For a given length of pipe this calculates to be 238.853.33. If the material chosen for the pipe 30 is smooth steel, the graph shown in Figure 5 indicates that the friction factor for the above Reynolds number is .016.For long pipelines of uniform diameter, such as here contemplated, the formula for loss of head due to friction is hf = f (Lid) V2/2g. In the illustrated embodiment, with an operating head of approximately 142 feet, a turbine draft tube 8 feet long and a reservoir 28 having a depth of 100 feet the length of pipe 30 required to be used to insure that the water exits from the system at atmospheric pressure computes to be approximately 20 miles long. The formula used for this determination is that the vertical drop measured in feet due to the curvature of the earth is approximately 2/3 the distance in miles squared. For a depth of 250 feet the pipe will exit at atmospheric pressure if it is extended from the reservoir a distance of approximately 19.36 miles.

Using this length of pipe in the formula for the friction head the loss due to friction is about 81.37 feet. By maintaining a head of this value in reservoir 28 the rates of flow of water to and from the system can be maintained in equilibrium.

Since a discharge of 45 cubic feet per second is equivalent to 20,160 gallons per minute and since 7.48 gallons occupy 1 foot of space the size of the reservoir needed to accommodate this rate of flow, giving an operating head of 81.36 feet, is a cylinder of that depth having a diameter of 6.5 feet. The compactness of this arrangement makes possible the clustering of turbogenerating systems using a common reservoir having the requisite number of exit pipes. For example, four such units as described above could share a com mon discharge reservoir having a depth of 81.36 feet and a diameter of 13 feet To insure adequate clearance and to provide an air space 41 the reservoir depth was selected to be 100 feet. To prevent air lock the reservoir is vented by pipe 42 which extends above the surface of the body of water 14.By interposing a centrifugal pump 40 in the pipeline 30 the size of the operating head required to be maintained within the reservoir can be reduced. However either arrangement, or a combination of both, can be utilized to maintain satisfactory operation of the system. If it is desired to replace the need for a reservoir in its entirety a discharge pump of sufficient capacity can be placed in the line. The pump shown is an airbreathing centrifugal pump mounted on a base plate 44 affixed to an upper surface of the pipeline 30. The pump drive shaft extends down into the pipe through conventional gland means not shown. An air vent is provided for the pump as shown in Figure 1 the pipe 46 extending from the water-tight enclosure enclosure 48, which houses the pump motor drive, to a position above the surface of the water.

In instances where it is desired to use the pump alone, it must have a capacity of 20,1 60 gallons per minute in order to handle the volume of water discharged by the turbine and additionally must be capable of overcoming a friction head of 81.36 feet. Under the conditions of operation set out above this arrangement would produce only a marginal net balance of powder. A centrifugal pump capable of handling this volume of water and head would require a drive motor of about 51 7.75 horsepower. The formula utilized to compute the required horsepower, assuming an operating efficiency of 80% is HP = (GPM) (Head) (Specific gravity)/(3960) (Efficiency). To reduce the power consumed by the pump a head of water can be maintained within the reservoir to act in concert with the pump to effect discharge of water from the system.For example, if a reservoir head of 61.36 feet is maintained the pump horsepower requirements are reduced to about 127 horsepower. This leaves a net balance of power from the system of about 493 horsepower As previously noted the frictional losses can be further reduced by orienting the pipeline 30 in a generally north-south direction in the northern hemisphere and in a generally south-north direction in the hemisphere thereby to take advantage of the centrifugal forces developed by the earth's rotation. While these forces are small in the illustrated embodiment they nevertheless can be a more significant factor in systems operated at depth of 1000 feet or more and which utilize substantially greater volumes of water than the system chosen for illustration. In the illustrated embodiment these forces supplement the forces needed to effect discharge of water.

Having described my invention by way of specific example it will be appreciated that the method and means of achieving the objectives af the invention may be accomplished by mechanically equivalent means, the embodiment illustrated being but one exemplary construction for producing the desired results.

Claims (13)

1. The method of powering a turbine which comprises: providing a closed system including a turbine, means for admitting fluid to the turbine, and discharge means; disposing the system beneath the surface of a body of fluid a distance sufficient to provide an operating head for the turbine; admitting fluid into the turbine through control means permitting variation in the flow rate; interposing in the closed system as an integral part thereof, between the turbine exit and discharge means, a reservoir of sufficient capacity to permit maintenance of a fluid head while concurrently allowing free exit of fluid from the overlying turbine; and providing means to maintain a condition of equilibrium between incoming and outgoing rates of flow whereby to maintain an operating system.

2. The method of claim 1 wherein said means for admitting fluid to the turbine comprises a valve in fluid flow communication with the inlet casing of said turbine.

3. The method of claim 1 wherein said means for admitting fluid to the turbine comprises an inlet pipe and associated valve means for regulating the rate of flow of fluid to the turbine.

4. The method of claim 1 wherein said means for maintaining a condition of equilibrium between incoming and outgoing rates of flow includes the provision of a fluid head within the reservoir sufficient to overcome friction losses in the discharge means.

5. The method of claim 4 wherein the discharge means comprises a pipeline disposed in a plane substantially parallel to the fluid surface immediately overlying the reservoir and extending a distance which based on the curvature of the earth reduces the head against which fluid must be discharged from the system to a value wherein the net power deriving from the overall system is a positive value.

6. The method of claim 1 wherein said means for maintaining a condition of equilibrium between incoming and outgoing rates of flow includes the provision of a pump to assist in the discharge of fluid from the system.

7. The method of claim 1 wherein said means for maintaining a condition of equilibrium between incoming and outgoing rates of flow include the provision of both pump means and maintenance of a fluid head within the reservoir.

8. The method of claim 5 wherein said pipeline is oriented with respect to the earth's surface in such a manner as to utilize centrifugal forces generated by the earth's rotation as an aid in the discharge of fluid from the system.

9. The method of operation of claim 1 wherein the reservoir-discharge means includes an underwater pipeline through which water is caused to flow by a head of water maintained within the reservoir.

10. The method of claim 9 wherein said reservoir-discharge means includes pump means disposed within the pipeline and of a capacity sufficient to maintain the required rate of flow from the turbine to maintain an operating system.

11. A turbo-generating system which comprises: a turbine feed conduit disposed in generally verticai orientation beneath the surface of a body of water and of a length sufficient to provide an operating head of water for the turbine; flow control means operatively associated with said conduit to regulate the rate of flow of water therethrough; a turbine disposed at the lower end of said conduit the casing of which is interconnected in flow communication with said conduit; a reservoir in water-tight communication with the discharge port of said turbine and means associated with said reservoir for discharging water therefrom at a rate permitting free discharge of water from the turbine and at a rate which is equal to or greater than the rate of flow of water entering the system.

12. The system of claim 11 wherein said reservoir associated discharge means includes one or more pipelines in watertight communication with the reservoir disposed in generally parallel orientation to the water surface immediately overlying the reservoir and extending therefrom a distance sufficient to permit discharge of water at substantially atmospheric pressure.

13. A method of powering a turbine substantially as herein descrIbed.

14, A turbo-generating system substantially as herein described with reference to the accompanying drawings.