WO2013072544A1 - System for eliminating overpressures in hydraulic transients - Google Patents

Abstract

System for eliminating overpressures in hydraulic transients for use in hydraulic lines, which incorporates a non-return valve (1) and a bypass (2) that includes a speed-check valve (3) for damping and suppressing overpressures induced in hydraulic lines through the effect of transients generated by sudden interruptions of impulsion units or for other reasons, such as rapid valve closures, etc.

Description

 OVERPRESSURE ELIMINATION SYSTEM

 IN HYDRAULIC TRANSITORIES

OBJECT OF THE INVENTION

The object of the present invention patent is to present a new system for damping and suppressing the overpressures induced in the hydraulic lines due to the effect of the transients generated by abrupt stops of the drive groups or for other causes such as rapid closing of valves, etc.

BACKGROUND OF THE INVENTION

So far, the control of the variations of pressure by transients in hydraulic systems of closed lines in pressure, is carried out with elements that provide the flow (water, air) in the phase of falling of the pressure (depressions) of regime when they occur a transient effect due to pump shutdown and / or sudden valve closure, and the damping of the return wave by volume absorption (equilibrium chimney) or air compression (boiler).

As a summary we cite the most characteristic:

 • Balancing chimney: cushions depressions and overpressures.

(Water)

 • Unidirectional tank: dampens depressions, (water)

 • Calderín: cushions depressions and overpressures. (Water)

 • Suction cups: cushions depressions, (air)

 • Abductors: cushions depressions, (air)

 • Relief valves: dampens overpressures. (Water)

 • By-pass in pumps: dampens depressions, (water)

All these existing systems cushion depressions or overpressures but do not eliminate them as in the case of the system described below. DESCRIPTION OF THE INVENTION

The system of elimination of overpressures in hydraulic transients to limit the overpressures derived from transients in a pressure pipeline, is based on the provision of a non-return valve (1) that allows normal flow in the main line and a bypass (2) for the reverse flow of return that communicates the back part of the non-return valve with the front part and that incorporates an overspeed valve (3).

The mission of each element is as follows:

• The non-return valve (1) Allows the flow of normal flow (+) and prevents the return flow (-)

 • Bypass (2) allows the reverse flow of return to pass.

 • The overspeed valve (3) Limits the value of the flow rate through the bypass (2) to a fixed setting value.

TECHNICAL-MATHEMATICAL JUSTIFICATION

We take into account the following principles:

TRANSMISSION CONDITION

ENERGY CONSERVATION

b) Si Qo/Sa≥ Vümite => V₀ S_a Igualando energías se obtiene que: a) If Q ₀ / S _a <Visi _te => Pass the entire return flow through the bypass

b) If Qo / Sa≥ Vümite => V ₀ S _a Matching energies you get that:

4- ^■ -¾-AH = ¾ -f-

2 ¿} 2: S

Putting the losses according to the speed height.

of the bypass components

Thus:

¾ = ¾ + 2-s Zt Ec. [1] piezometric downstream

Being: V ₀ = Q ₀ / S Va = Q-¡/ Sa V _! = Q ^ S

Characteristic method: The meaning of the previous terms in the application of the characteristics method is presented below.

Continuity equation ^dt f- ^ ^& δϋ §H f. O. IQ \

Energy conservation dt * ^"" §x 2. & .Λ They are obtained by using the flow rate instead of the velocity as the basic variable, and by neglecting the fluid velocity to the value of the speed "a" (v «« a ). This simplification is equivalent to not considering the variations of kinetic energy along the duct during transient regimes. DESCRIPTION OF THE DRAWINGS

To complete the description and for a better understanding of the claimed invention, the corresponding figures are attached in which the following is represented:

Figure 1.- A view of the system with the different components is represented. - Figure 2.- The same view of the system is represented with the different components and flows as well as the explanation of the different parameters.

Figure 3.- A chart with a graph resulting from the calculation is represented by a software program for the calculation of transients in which the overpressures are appreciated in a case that does not incorporate the system proposed in the present invention.

Figure 4.- A chart with a graph equal to the previous one is represented in a case that incorporates the overpressure elimination system proposed in the present invention.

PREFERRED EMBODIMENT OF THE INVENTION

As can be seen in Figure 1, which basically contemplates the design of a homogeneous device, although the system can be installed in a compact device or not, using a non-return valve (1) for direct flows and a by- pass (2) with a speed limiting valve (3) to dampen and control the reverse flows of return. The versatility is wide, since conceptually it allows great elasticity in its practical application. In a more concrete case study, it is considered a conduit consisting of a pumping of 320 m of geometric height and 329.75 m of manometric height for a flow of 280 l / s with a pipeline of 0600 mm of 8370 m in length, being the Hydraulic features the following:

• Celerity = 1300 m / s

 • Pump shaft dimension = 330 m

 • Dimension of the intake tank = 331 m

 • Arrival deposit level = 651 m

 • Length increase = 418.50 m

 • Manning No. = 0.0091

 • Geometric height = 320 m

The pump has as characteristic equations:

Hm = 463.3991-630.4681 Q + 540.7562 Q ²

Cr = 4.9083 Q - 7.5727 Q ²

The following overpressure elimination systems have been arranged:

D. Origin Diameter Long V. max.

 System 1, 5000.00 0.050 4.00 3.00 432,500

 System 2, 6000.00 0.050 4.00 3.00 461,000

 System 3, 7000.00 0.050 4.00 3.00 502,000

 System 4, 8000.00 0.050 4.00 3.00 558,000

Next, the calculation was carried out by means of a software program for the calculation of hydraulic transients in conduits in two hypotheses; A) Without overpressure elimination system B) With 4 overpressure elimination systems of 050 mm and speed limiters of 3 m / s whose results are shown in the graphs represented in figures 3 and 4 respectively.

Once the nature of the present invention has been sufficiently described, as well as a way of putting it into practice, it only remains to be added that said invention may undergo certain variations in form and materials, as long as said alterations do not substantially vary the characteristics claimed below.

Claims

1.- System of elimination of overpressures in hydraulic transients characterized in that it consists of a non-return valve (1) placed in the normal flow pipe and a bypass (2) for the reverse return flow that communicates the part before and after the non-return valve (1) incorporating an overspeed valve (3).