CN101737229A - Elliptical draft tube flow expansion method and high-efficiency power generation system - Google Patents

Abstract

The invention discloses an elliptical draft tube flow expansion method and a high-efficiency power generation system. The elliptical draft tube flow expansion method is characterized in that: a draft tube is an elliptical draft tube; and the calibre of a water outlet of the draft tube is more than that of a water inlet of the draft tube. The method and the system increase electric energy converted from kinetic energy component in water power by increasing the difference between flow rates of a pressure water conduit and the draft tube, and improve generating efficiency.

Description

Elliptical draft tube flow expansion method and efficient power generation system

Technical field

The present invention relates to a kind of elliptical draft tube flow expansion method and efficient power generation system, belong to the hydroelectric power field.

Background technique

The water power plant utilizes reservoir to come retaining, and the water yield of the big more storage of reservoir capacity is big more, and the water that reservoir stores can be just many more.Current with certain flow rate contain kinetic energy, and the high more kinetic energy that has of flow velocity is just big more; The current that are in certain altitude have potential energy, and the big more potential energy that has of relative height is just big more.Current flow to lower from eminence, potential energy can be converted into kinetic energy, and current obtain higher speed.The water of saving in the reservoir obtains high speed under action of gravity, move along pressure diversion conduit is defeated downwards, obtains higher speed at the water turbine jointing.Water current driven water turbine with certain speed rotates, and makes water turbine obtain mechanical energy; The water wheels machine driving generator is converted into electric energy with mechanical energy.Water power plant hydraulic generator unit output Power Calculation formula all adopts following mathematical formulae traditionally ^[1]-[3]:

P＝9.80ηQH (1)

P is a hydraulic generator unit output power (kW) in the formula, and Q is a generating flow, and H is a productive head, and η is the water turbine generating efficiency.

Formula (1) is to draw under hypothesis pressure diversion conduit ingress water velocity, pressure and prerequisite that water turbine water outlet place water velocity, pressure equate.That is to say that the Traditional calculating methods of hydraulic generator unit output power includes only potential energy, and do not comprise kinetic energy, pressure energy.Traditional calculating methods, do not consider that water flow dynamic energy and pressure energy move at reservoir, pressure diversion conduit, water turbine, the defeated of draft tube, therefore on structure and technology, reservoir, pressure diversion conduit, water turbine, draft tube are not carried out specific aim improvement and optimization yet, make that water can not obtain fully and efficiently utilizing.

The electric energy that the hydraulic generator unit is transformed from reservoir water body potential energy, kinetic energy and pressure energy main and reservoir drop, pressure diversion conduit ingress water velocity and reservoir filling water level etc. have relation.

HYDROELECTRIC ENERGY is to be the main resource of taking into account other comprehensive utilizations with the generating, in order to carry out reasonable optimizing to its utilization, must obtain its total amount by mathematical method, sets up functional model.HYDROELECTRIC ENERGY is the Conversion of energy of being contained by natural water resources, mainly is to be present in the energy that pressure energy, potential energy, impact kinetic energy and water body gravity acting in the water body are produced.

(1) energy that has of water inlet water body infinitesimal

Suppose that water power plant unit pressure deferent is cylindrical, one of water inlet little length on the x direction is the water body infinitesimal of dx, and then the stressed of this water body infinitesimal has gravity, hydraulic pressure to reach reservoir level Four water body weight force component by force to its active force.Under these active force actings in conjunction, the water body infinitesimal to the outlet campaign and promote the water wheels unit and rotate, is finally realized the coupling conversion of water energy-mechanical energy-electric energy along the pressure diversion conduit import, and the hydraulic generator unit produces electric energy output.

Pressure along the pressure diversion conduit durection component to water body infinitesimal institute's work or the energy W that had _IFor:

$W_I=P_I{V}_W=(H-H_I)\mathrm{\&rho;}\&CenterDot;\frac{1}{4}\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\mathrm{dx}=\frac{1}{4}\mathrm{\&pi;\&rho;}{D}^2(H-H_I)\mathrm{dx}---\left(2\right)$

P wherein _I, V _W, H _I, D is volume, pressure, water level, the diameter of pressure diversion conduit ingress water body infinitesimal, H is the reservoir filling water level, ρ is the proportion of water, α is the pressure diversion conduit tilt angle.

Water body infinitesimal weight at the formed pressure in pressure diversion conduit ingress along component institute's work of pressure diversion conduit direction or the energy that is had is:

$M_I=p_M{V}_M=\frac{1}{4}\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\mathrm{\&rho;}\&CenterDot;{\mathrm{dx}}^2---\left(3\right)$

If weight is m _W, volume is V _WThe speed of water body infinitesimal in the pressure diversion conduit water inlet be v _{I, j, i}, then its kinetic energy that has is:

$k_I=\frac{1}{2g}{m}_W{v}_{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">I</figure-callout>}}^2=\frac{1}{2g}\&CenterDot;\frac{1}{4}\mathrm{\&pi;\&rho;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\mathrm{dx}\&CenterDot;v_{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">I</figure-callout>}}^2=\frac{1}{8g}\mathrm{\&pi;\&rho;}{D}^2{v}_{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">I</figure-callout>}}^2\mathrm{dx}---\left(4\right)$

Weight is m _W, volume is V _WThe water body infinitesimal have potential energy in pressure diversion conduit water intake place and be:

$E_I=m_W\&CenterDot;H_I=\frac{1}{4}\mathrm{\&pi;\&rho;}{D}^2{H}_I\&CenterDot;\mathrm{dx}---\left(5\right)$

(2) energy that has of water outlet place water body infinitesimal

To moving to the water body infinitesimal in downstream after the water turbine acting, suppose that the pressure of water power plant hydraulic generator unit at water turbine water outlet place is p _O, then this pressure is m to weight _W, volume is V _WThe water body infinitesimal done be:

$W_O=p_O\&CenterDot;V_W=\frac{1}{4}\mathrm{\&pi;}{D}^2{P}_O\mathrm{dx}---\left(6\right)$

Weight is m _WThe water body infinitesimal at the formed pressure in cross section, water turbine water outlet place be along component institute's work of pressure deferent direction or the energy that is had:

$M_O=M_I=\frac{1}{4}\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\mathrm{\&rho;}\&CenterDot;d^{2}x---\left(7\right)$

If weight is m _W, volume is V _WThe speed of water body infinitesimal at water turbine water outlet place be v _O, then its kinetic energy that has is:

$K_O=\frac{1}{2g}{m}_W{v}_{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">O</figure-callout>}}^2=\frac{1}{2g}\&CenterDot;\frac{1}{4}\mathrm{\&pi;\&rho;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\mathrm{dx}\&CenterDot;v_{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">O</figure-callout>}}^2=\frac{1}{8g}\&CenterDot;\mathrm{\&pi;\&rho;}{D}^2{v}_{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">O</figure-callout>}}^2\mathrm{dx}---\left(8\right)$

Weight is m _W, volume is V _WThe water body infinitesimal at the potential energy that water turbine water outlet place has be:

$E_O=m_W\&CenterDot;H_O=\frac{1}{4}\mathrm{\&pi;\&rho;}{D}^2{H}_O\&CenterDot;\mathrm{dx}---\left(9\right)$

H wherein _OElevation for water turbine water outlet place, water power plant.

(3) the unit electric energy calculates

Acting moves to the aqueduct outlet to upstream water body infinitesimal through water turbine, and according to law of conservation of energy, energy or merit that water turbine obtains are:

$E_G=W_I+K_I+E_I+M_I-W_O-K_O-E_O-M_O$

$=\frac{{\mathrm{\&pi;<figure-callout\; id="2"\; label="D"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\cos \mathrm{\&alpha;}[\mathrm{\&rho;}(H-H_I)-P_o]\mathrm{<figure-callout\; id="4"\; label="dx"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">dx</figure-callout>}}{4}+\frac{\mathrm{\&pi;\&rho;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="H2009101145168E0000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\cos \mathrm{\&alpha;}[v_I^2-v_o^2]\mathrm{dx}}{8g}$

$+\frac{\mathrm{\&pi;\&rho;}{D}^2(H_I-H_o)\mathrm{dx}}{4}---\left(10\right)$

Make k _pBe the ratio of Hydropower Plant water turbine water outlet place with pressure deferent water inlet water body pressure:

$k_P=\frac{p_O}{p_I}---\left(11\right)$

k _vBe the ratio of step power station unit water turbine water outlet place with pressure deferent water inlet water volume flow rate:

$k_v=\frac{v_O}{v_I}---\left(12\right)$

H _DBe the drop between Hydropower Plant pressure deferent water inlet and the water turbine water outlet place:

H _D＝H _I-H _O (13)

Energy or function electric power that water turbine obtains are represented, then step power station j i platform unit with kW be unit (1kW=102kg.m/s) in period dt, produced exert oneself and can represent:

$N_G=\frac{1}{102}[(1-k_p)p_I+\frac{1}{2g}{v}_I^3(1-k_v)+H_D]Q_G---\left(14\right)$

Q wherein _GBe the unit generation flow, $Q_G=\frac{1}{4}\mathrm{\&pi;}{D}^2{v}_I,$ $v_I=\frac{\mathrm{dx}}{\mathrm{dt}}.$

To formula (14) arrangement:

$N_G=9.8[(1-k_p)p_I+\frac{1}{2g}{v}_I^3(1-k_v)+H_D]Q_G---\left(15\right)$

From formula (15) as can be seen, the available water of Hydropower Plant Reservoir can comprise water body pressure energy, kinetic energy, potential energy, the electric energy that utilizes the hydraulic generator unit to be obtained is relevant with water power plant drop, generating flow, and also the parameters such as storage capacity feature of importing and exporting pressure, speed, aqueduct inclination angle and the water power plant of water body with pressure diversion conduit have substantial connection.

Traditional hydraulic generator unit all is to adopt the Traditional calculating methods of above-mentioned formula (1) to determine its electric motor power.

Author of the present invention draws as drawing a conclusion through research for many years:

1) hydroelectric generator can be converted into mechanical energy by reservoir, pressure diversion conduit, water turbine, generator and draft tube with water and be converted into electric energy again, and electric energy comprises three kinds of components such as kinetic energy, potential energy and pressure energy.

2) the kinetic energy component is directly proportional with the difference of two squares of pressure diversion conduit water inlet place and water turbine water outlet place water velocity.Pressure diversion conduit water inlet place water velocity is controlled water turbine water outlet place water velocity little greatly, and the kinetic energy component will increase; If pressure diversion conduit water inlet place and water turbine water outlet place water velocity equate that the kinetic energy component is 0 so.

3) the pressure energy component is directly proportional with the difference of pressure diversion conduit water inlet place and water turbine water outlet place current pressure.Current suffered pressure in pressure diversion conduit water inlet place controls water turbine water outlet place current pressure little greatly, and the pressure energy component will increase; If pressure diversion conduit water inlet place and water turbine water outlet place water velocity equate that the pressure energy component is 0 so.

Summary of the invention

Based on above-mentioned analysis, technical problem to be solved by this invention is, a kind of generating power effectively by hydroelectric generator method and system are provided, and makes full use of the kinetic energy component, and the kinetic energy transformation efficiency is improved, and realizes hydroelectric power more efficiently.

Technological scheme of the present invention is as follows:

The generating power effectively by hydroelectric generator method is made elliptical shape with draft tube, and the water outlet caliber of draft tube is greater than reservoir water intake caliber.Its role is to,, obtain pressure diversion conduit water inlet water velocity v by enlarging draft tube water outlet caliber _IWith the water velocity v of water turbine water outlet place _OBetween bigger difference.At water turbine water outlet v _OUnder the situation less, that caliber is bigger, make draft tube can transport the generating flow the same, make kinetic energy be converted into electric energy more with pressure diversion conduit.

The generating power effectively by hydroelectric generator system comprises reservoir, pressure diversion conduit, water turbine, generator, draft tube, it is characterized in that: draft tube is an elliptical draft tube, and the water outlet caliber of draft tube is greater than the water intake caliber.

The invention has the advantages that: carry out innovative design by draft tube system to hydroelectric power system, increase the difference of pressure diversion conduit and elliptical draft tube water velocity, the kinetic energy component is converted into electric energy in the water energy thereby increase, and improves generating efficiency, and the utilization ratio of water energy is also just higher.

Description of drawings

Accompanying drawing is the schematic representation of elliptical draft tube flow expansion method of the present invention and efficient power generation system.

Embodiment

As shown in the figure, 1 is reservoir, and 2 is pressure diversion conduit, and 3 is water turbine, and 4 is generator, and 5 is draft tube.The water intake of pressure diversion conduit 2 is connected with reservoir 1, and the water outlet of pressure diversion conduit 2 is connected with the water intake of water turbine 3.The water outlet of water turbine 3 directly is connected with the water intake of big caliber draft tube 5.

Pressure diversion conduit 2 with bore 8m is an example, flow velocity degree for water turbine 3 pressure diversion conduit water 2 is 8m/s, under situation about not considering through the influence of the variation of water turbine 3 back water velocities and other factors, if elliptical draft tube 5 water intake bores are 8m, water outlet aperture is the twice of the bore of pressure diversion conduit 2, elliptical draft tube 5 is when transporting the generating flow condition the same with pressure diversion conduit 2 so, and the water velocity of the elliptical draft tube 5 of flowing through can be changed into 4m/s.If consider that part kinetic energy component is converted into mechanical energy by water turbine 3 in the water energy, the water velocity of elliptical draft tube 5 will be less than 4m/s so, even can be below 1-2m/s.

For new unit, as long as balance technology and economic effect, the k that the elliptical draft tube water outlet aperture is designed to the pressure diversion conduit bore doubly just can make the elliptical draft tube water velocity reduce 1/k in when design.Reducing of elliptical draft tube water velocity just can increase the difference of pressure diversion conduit and elliptical draft tube water velocity, thereby makes that bigger water flow dynamic energy component is converted into electric energy, improves waterpower utilization rate, the high efficiency of strong water-energy generating electricity.

And,, just can realize technique effect of the present invention as long as existing draft tube is carried out structure and technologic technical innovation for old unit.

Claims (3)

1. elliptical draft tube flow expansion method is characterized in that, the draft tube caliber is greater than the pressure diversion conduit caliber.

2. based on the efficient power generation system of elliptical draft tube boosting method, comprise reservoir, pressure diversion conduit, water turbine, generator, draft tube, it is characterized in that the draft tube caliber is greater than the pressure diversion conduit caliber.

3. the efficient power generation system based on the elliptical draft tube boosting method as claimed in claim 2 is characterized in that, described big caliber draft tube sectional shape is oval.

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