RU2369798C1 - Corrugated gas line with noise and vibration reduction (versions) - Google Patents

Abstract

FIELD: construction industry.

SUBSTANCE: invention refers to corrugated tubes (including hoses) designed for transporting gases and gas liquid mixtures. The effect is achieved by two version of the invention. As per the first version, the specified effect is achieved by the fact that gas pipeline consists of at least one pair of corrugated pipe lengths, the ratio of corrugation pitches of which is within 0.3-0.9, and amplitude ratio - within 0.8-1.2; at that, each specified length of the pipe consists of at least one corrugation pitch. As per the second version, the specified result is achieved by the fact that gas pipeline consists of at least one corrugated pipe length with the corrugation profile formed by adding at least two periodic functions of the distance along the pipe axis; at that, ratio of periods of the above functions is within 0.3-0.9, and amplitude ratio - within 0.8-1.2.

EFFECT: reduction of noise and vibration, which appear owing to turbulence of internal medium flow in corrugated gas line without any loss of efficiency caused by decrease of transportation speed.

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Description

Technical field

The proposal relates to corrugated pipes (i.e., pipes, including hoses containing corrugated sections) intended for the transport of gases or gas-liquid mixtures.

State of the art

Flexible natural gas pipelines (hoses) are required for the delivery of produced natural gas from subsea wells to floating gas production platforms and from floating gas production platforms to onshore gas facilities (gas storages or gas pumping stations), the flexibility of which is provided by running the gas pipeline from corrugated pipes (corrugated gas pipelines).

In addition, pieces of corrugated pipes are used as flexible parts of air ducts made mainly of inflexible smooth pipes (for example, inlet or outlet units).

For corrugated gas pipelines, there is an acute problem of the so-called “singing corrugated pipe”, caused by the fact that the gas flow (in particular, air) or the flow in the pipe when it reaches a speed of 1.5-2.0 m / s generates a high noise level in the corrugated gas pipeline and vibrations that reduce the reliability of the gas pipeline. This effect is also preserved in the presence of a liquid phase in the transported stream (i.e., when transporting a gas-liquid mixture).

The problem is so acute that it has to be solved at existing floating gas producing stations (for example, in Norway) by significantly reducing the gas pumping rate, which leads to a decrease in the productivity of gas producing stations and huge economic losses during gas transportation. This problem should be distinguished from the VIV (Vortex Induced Vibrations - vibration caused by the breakdown of vortices), which has many patented solutions. Problem VIV is relevant for vibrations caused by external flow around pipes underwater flows, and is usually solved by forming stiffeners of various configurations on the outer surface of the non-corrugated pipe [1].

The results of research and the search for a solution to the problem of noise and vibration in flexible corrugated gas pipelines are presented in [2] and [3]. In this case, theoretically and experimentally tested the possibility of reducing noise and vibration by changing the geometric shape and size of the corrugations, the degree of reflection of sound waves from the end of the pipe, the geometry of the pipe and the effective speed of sound in it. However, no solution was found.

Known silencer containing a housing in the form of a corrugated pipe, which is equipped with a sound-absorbing insert placed with a gap relative to the inner surface of the body and repeating the shape of the latter, and perforated rings of rigid porous sound-absorbing material installed between the insert and the body in its minimum sections [4].

The disadvantage of this solution in relation to a corrugated gas pipeline is the clutter of the gas pipeline cavity with sound-absorbing elements (insert and rings), which reduces its performance.

Known flexible corrugated pipe having sections with different pitch corrugation [5]. However, this solution is aimed at improving the operability (reliability) of the pipe under conditions of vibration overload transmitted from its nozzles, but does not suppress the noise and vibrations arising from the turbulence of the medium flow inside the pipe.

Disclosure of the invention

The objective of the invention is to reduce noise and vibration arising from the turbulence of the internal flow of the medium in a gas pipeline containing corrugated sections, without loss of productivity of the gas pipeline.

The technical result achieved by using the invention is the suppression of noise and vibration arising in the corrugated parts of the pipeline, without loss of productivity of the pipeline, caused by a decrease in the speed of transportation. This technical result is achieved in two embodiments of the invention.

In the first embodiment, this result is achieved in that the gas pipeline contains at least one pair of corrugated pipe sections, the ratio of the corrugation steps of which lies in the range of 0.3-0.9, and the ratio of amplitudes is in the range of 0.8-1.2 wherein each said pipe section contains at least one corrugation pitch.

The corrugated pipe sections forming the indicated pair can be divided by a non-corrugated pipe section or a section with other corrugation parameters.

In the second embodiment, this result is achieved in that the gas pipeline contains at least one corrugated pipe segment with a corrugation profile formed by the sum of at least two periodic distance functions along the pipe axis, while the ratio of the periods of these functions lies within 0, 3-0.9, and the ratio of amplitudes is in the range of 0.8-1.2.

Brief Description of the Drawings

Figure 1 presents the experimental dependence of the energy loss in the corrugated pipe from the Strouhal number.

Figure 2 illustrates the discovered by the authors of the effect of suppressing vibrations in a corrugated pipe having two sections.

Figure 3 shows examples of the designs of the proposed corrugated gas pipeline according to the first embodiment.

Figure 4 is an example of execution according to the second embodiment.

The implementation of the invention

Theoretical and experimental prerequisites for the implementation of the invention are presented in [6], according to which the acoustic processes accompanying the flow of a gas (including air) medium in a corrugated pipe are characterized by the function D (f, L, U), which reflects the dependence of the total energy losses D at a frequency f from the corrugation step L and the medium flow velocity U. Positive values of D correspond to attenuation of acoustic vibrations in the corrugated pipe, and negative values correspond to their generation. The total losses D include a sign-changing component associated with the profile of the inner surface of the corrugation, and a positive component related to the viscosity and thermal conductivity of the medium.

, называемой числом Струхаля, воспроизведены на фиг.1. Кривые а, б и в соответствуют скоростям потока 5, 10 и 15 м/с. Используя кривые фиг.1, можно получить зависимости величины D от частоты, показанные на фиг.2. Здесь, как и на фиг.1, положительные значения D соответствуют затуханию колебаний, а отрицательные - их генерации.The experimental dependences of D on the dimensionless quantity given in [6]

, called the Strouhal number, are reproduced in FIG. Curves a, b and c correspond to flow rates of 5, 10 and 15 m / s. Using the curves of FIG. 1, it is possible to obtain the dependences of D on frequency shown in FIG. Here, as in FIG. 1, positive values of D correspond to damping of oscillations, and negative values correspond to their generation.

The values of the loss function D (f) of two segments of the same pipe at each frequency are summed. At the same time, the authors found that with an appropriate ratio of the corrugation steps on two pipe sections, the vibrations generated by one pipe section dampen in the other.

Figure 2 illustrates this effect. It shows the frequency dependences D (f) for a gas pipeline having two pipe sections with uneven corrugation steps L ₁ and L ₂ at a gas flow velocity of 15 m / s.

Curves D (f) for a segment with a smaller step L ₁ corrugation are marked with a symbol □, and for a segment with a large step L ₂ corrugation is marked with an O. Fig. 2a corresponds to the relation

L ₁ / L ₂ equal to 0.5, fig.2b - the ratio of L ₁ / L ₂ equal to 0.4, and figv - ratio L ₁ / L ₂ equal to 0.6. The resulting curves D (f) are shown by thickened lines.

As can be seen from figure 2, the oscillations of the same frequency in one segment of the pipe correspond to the generation region, and in the other to the damping region.

With the selected ratios of the corrugation steps, the oscillations generated by one section of the pipe damp in another. From figure 2 it can be seen that in a composite corrugated pipe with selected ratios of the steps of the corrugations, the resulting vibrations are largely suppressed in the entire practically significant region of sound frequencies.

Shown in figure 3, examples of structures of the proposed corrugated gas pipeline contain a pair of corrugated pipe sections: section 1 and section 2. The amplitude (height) of the corrugation in section 1 is equal to h ₁ , in section 2 is equal to h ₂ . The ratio of amplitudes (heights) h ₁ / h _{2 is} close to unity. The corrugation step on segment 1 is equal to L ₁ , and on segment 2 is equal to L ₂ . The ratio of steps L ₁ / L _{2 is} close to 0.5.

On figa shows an example of a gas pipeline from two sections with a sinusoidal profile, on figb - from two segments having cylindrical sections.

Figure 4 shows an example of a gas pipeline construction according to the second embodiment, with a corrugation profile formed by the sum of at least two periodic distance functions along the pipe axis, the amplitude ratio of which is close to unity, and the ratio of periods is close to 0.5.

The lengths of segments 1 and 2 are selected from technological considerations, but are limited by the condition D> Dmin, where Dmin is the specified minimum value (for example, equal to zero). Verification of the fulfillment of this condition for a corrugated pipe segment with specific parameter values at a given maximum medium flow rate is performed using the dependencies shown in Fig. 1.

The above is confirmed by experimental tests, in which it was found that the effect of mutual suppression of the oscillations of the flow of the medium flowing sequentially through segments 1 and 2 is preserved in the range of ratios L ₁ / L ₂ equal to 0.3-0.9, and ratios h ₁ / h ₂ , equal to 0.8-1.2.

Information sources

1. Pat. USA US 6948884, IPC F15D 1/10, F16l 57/00, op. 09/27/2005.

2. U. Kristiansen, T. Reinen, G.A. Wiik. Proc. of lnter-noise, 2005, p. 220-221.

3. U. Kristiansen, T. Reinen, G.A. Wiik. Journal of Acoustic Society of America, 2007, v. 121, No. 3.

4. Pat. RU 2298668, IPC F01N 1/00, op. 05/10/2007

5. Pat. RU 2028535, IPC F16L 11/11, op. 02/09/1995.

6. V.F. Kopiev, M.A. Mironov, B.C. Solntseva, Acoust. Zh., 2008, v. 54, No. 2, 237-243.

Claims (2)

1. A gas pipeline containing at least one pair of corrugated pipe segments, the ratio of the corrugation steps of which lies in the range of 0.3-0.9, and the ratio of amplitudes is in the range of 0.8-1.2, with each specified section the pipe contains at least one step of the corrugation. 2. A gas pipeline containing at least one corrugated pipe segment with a corrugation profile formed by the sum of at least two periodic distance functions along the pipe axis, while the ratio of the periods of these functions lies in the range 0.3-0.9, and the ratio of amplitudes is in the range of 0.8-1.2.

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