RU2756396C1 - Method for suppressing pressure pulses in pipelines - Google Patents

Abstract

FIELD: pipes.

SUBSTANCE: invention relates to methods and means for suppressing pressure pulsations of a liquid (water hammer) or a gas in pipelines. The method consists in the fact that the liquid or gas flow of the pipeline wherein the pressure pulses act is divided into N parts further directed to channels with different delays due to the different lengths thereof, therefore, pulses from different channels with a power reduced by N are summed up at the output, coming in succession due to the different times of passage through the channel. Accordingly, the pulse front is spread and the undesirable impact on the pipeline is reduced. The delay of each channel is calculated by the formula Tn=T+delta*(N-l), wherein T is the delay of the shortest channel, Tn is the delay in the N^th channel, delta is the increment of the channel delay when the number thereof is increased by one, N is the number of the channel.

EFFECT: levelled rising rate of the pressure pulse front of a liquid or a gas in a pipeline and a corresponding reduction in the negative impact on the pipeline.

1 cl, 2 dwg

Description

The invention relates to heat supply facilities, oil, gas, chemical, nuclear industries, as well as to aerospace technology, and can be used as a means of protecting pipelines from destruction as a result of impulses and pressure pulsations in a liquid or gas accompanying a hydraulic shock that occurs when turning on, running and turning off pumps, opening and closing valves, gate valves and other devices.

Known traditional methods of damping oscillations in pipelines, which consist in the fact that the flow of liquid or gas is divided into parts, and the flows diverted from the pipeline are introduced into damping chambers with elastic elements, in which the volume changes under the influence of a pressure drop, due to the use of the potential energy of impulses [12].

The disadvantage of this method is the limited frequency range of the suppressed pressure pulses, which depends on the stiffness of the elastic elements and the limited volume of the expansion chambers.

The closest in technical essence to the claimed invention (prototype) is a method that is implemented in a method and device for damping pressure pulses in main pipelines [3]. The method of dissipation of pressure pulses consists in the fact that the flows of liquid or gas of the main pipeline, in which the pressure pulses act, are divided into parts, and the diverted parts are led through the expansion chambers into the damping chamber, in which the flows are directed oppositely to the liquid or gas in the chamber so that the pressure impulses change their density and pressure due to the potential energy of the impulses themselves and simultaneously twist the flows in opposite directions, slowing down the speed of the liquid or gas due to the kinetic energy of interaction of the counter flows.

The advantage of the described method for damping pressure pulses is an increase in the efficiency of damping pressure pulses due to the simultaneous dissipation of both potential and kinetic energies of the pulses themselves by changing the density, pressure, and velocity of counter flows of liquid or gas in the damping chamber.

The disadvantage of this method of damping pressure pulses is low efficiency and the absence of an analytical tool for calculating the effectiveness of the method.

The objective of the method of the invention is to improve the efficiency of damping pressure fluctuations in pipelines by stretching the energy and the front of the pressure pulse in time.

The specified technical effect in the method of increasing the efficiency of damping fluctuations of pressure pulses is that the flow of liquid or gas of the pipeline is divided into parts, which are inserted into channels of different lengths, where the flows move at the same speed, but at different times. When the channels are combined into a common flow, the front of the pressure pulse is stretched (smoothed) the more, the greater the number of channels used.

Different delay times of the pressure pulse in different channels are determined by the fact that all channels have different lengths determined by the formula Tn = T + delta * (N-1), where T is the delay of the shortest channel, Tn is the delay of channel number N, delta is increment of the channel delay with increasing its number by one, N is the channel number.

The essence of the proposed technical solution is illustrated by drawings, which show:

in fig. 1 - dividing the stream into channels with different delay times,

1 - incoming stream,

2 is the shortest channel,

3 - the longest canal,

4 - outgoing stream,

in fig. 2 - time diagram of the front of the pressure pulse in the inlet stream and in the outflow stream after combining the channels,

5 - pressure axis,

6 - front pressure pulse in the incoming stream,

7 - front pressure pulse in the outgoing flow,

8 - time axis,

9 - delay in the shortest channel,

10 - delay in the longest channel.

The method for damping pressure pulses in the main pipeline works as follows.

In a steady-state steady-state mode, the flow of liquid or gas passing through a section of the main pipeline has a constant pressure at the inlet 1 and outlet 4 of all channels (Fig. 1). In this case, a constant pressure is established in all channels.

The front of the arising pressure impulse (water hammer) reaches the inputs of all channels at the same time, but at the output of each channel it appears with an N times reduced energy (in accordance with the number of channels used) and with a delay that depends on the channel length. As a result, the duration of the leading edge of the pulse at the output will be longer than at the input (Fig. 2). The more channels are used, the stronger will be the smoothing of the front of the pressure pulse and, accordingly, the less negative effect of the pressure pulse (water hammer) on the pipeline.

Thus, the proposed method for damping pressure pulses in a pipeline makes it possible to increase the efficiency of damping pressure pulses by stretching the front of the pressure pulse in time, similarly to how an integrator works in electrical circuits.

Sources used

1. B.B. Nekrasov. Hydraulics and its application in aircraft. Publishing house "Mechanical engineering", M., 1967, p. 202.

2. RF patent No. 2386889, cl. F16L, 55/04 for 2010

3. RF patent No. 2645860, cl. F15D, 1/00 (2006.01) (prototype).

Claims (1)

The method of damping pressure pulses in pipelines, which consists in the fact that the flow of liquid or gas of the pipeline, in which the pressure pulses act, is divided into parts moving in separate channels, which are then combined into a common flow, characterized in that the pressure pulse in each channel is delayed by time by an amount determined by the formula Tn = T + delta * (N-1), where T is the delay in the shortest channel, Tn is the delay in the channel number N, delta is the increment in the channel delay with increasing its number by one, N is channel number.

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