JPH06103238B2 - Pressure pulsation analyzer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure pulsation analyzer for analyzing pressure pulsations in a pipe based on pressure fluctuations caused by a pressure source such as a reciprocating compressor and a pump. .

[Prior art]

The fluid that is intermittently sucked in / discharged from the pressure source such as the reciprocating compressor or pump described above serves as a pulsating vibration source, and the fluid in the pipe vibrates. If the vibration of the fluid becomes large due to resonance with the vibration cycle of the pressure source, the piping may be vibrated and damaged, or the performance of the pressure source such as the compressor or pump may be deteriorated. Therefore, considering the coupling between the fluid in the cylinder of the pressure source such as the compressor and pump and the fluid in the pipe, the dimensions of the pipe so that the vibration due to the above-mentioned pressure source and the pressure fluctuation in the pipe do not resonate. In order to determine the design, it is necessary to analyze the pressure pulsation in the pipe that considers the above fluid coupling.

The pressure pulsation analysis method that does not consider fluid coupling as described above is
Already (pressure pulsation analysis of reciprocating compressor piping system, Kobe Steel Engineering Reports
Vol.37 No.1) has a long history and track record, and is well known.

[Problems to be Solved by the Invention]

However, in the conventional pressure pulsation analysis method as described above, fluid coupling is not taken into consideration, and the accuracy of pulsation analysis is not sufficient.

Further, the pressure pulsation analysis method is roughly classified into a method performed in the frequency domain and a method performed in the time history as disclosed in the above document. The method performed in the time history is compared with the calculation method in the frequency domain. Therefore, there was a problem in terms of calculation cost, etc.

Therefore, the present invention is to provide a pressure pulsation analysis device capable of efficiently performing highly accurate pressure pulsation analysis in consideration of fluid coupling in the frequency domain.

[Means for Solving the Problems]

In order to achieve the above object, the first invention is a pressure pulsation Δ in a pipe in a frequency region based on the impedance Z _n of the pipe.
P and pressure fluctuation in the cylinder in the frequency domain of the pressure source Δ
From P _c , n of the volume of fluid flowing into and out of the cylinder
A means for obtaining the complex amplitude X _{n of the} next component, a means for obtaining the vibration flow rate Q _n of the fluid in the pipe considering the fluid coupling using the above X _n, and a fluid coupling in the frequency domain using the above Q _n. And a means for determining pressure pulsation ΔP in the pipe in consideration of the formation of the pressure pulsation analyzer.

The second invention is the assumed impedance Z _{n of} the pipe.
And pressure pulsation [Delta] P in the pipe in the frequency domain based on, more and the pressure variation [Delta] P _c in the cylinder in the frequency domain of the pressure source,
Means for determining the n-th order components complex amplitude X _n of the volume of fluid flowing into and out into the cylinder, means for determining the vibration rate Q _n of the pipe the fluid in consideration of coupling fluid with the X _n, Above Q _n
Means for obtaining the pressure pulsation ΔP in the pipe in consideration of fluid coupling in the frequency domain, and the corrected pressure pulsation ΔP for the corrected pipe impedance Z _n ′, and the correction with Z _n ′. Means for comparing the previous impedance Z _n , repeating the above-mentioned means until the difference is within a predetermined range, and obtaining the corrected pressure pulsation ΔP in the pipe at the time when the difference is within the predetermined range. It is configured as a pressure pulsation analysis device provided.

〔Example〕

Next, an embodiment embodying the present invention will be described with reference to the flowchart showing the calculation procedure shown in FIG.

Incidentally, the method of analyzing the pressure pulsation in the frequency domain which does not take fluid coupling into consideration is well known from the above-mentioned literatures and others, but its detailed description is omitted.

The pressure pulsation analysis method in the embodiment described below is summarized as follows. That is, the fluid coupling is the specific gravity of the fluid,
Related to viscosity, volume, etc., which is the impedance of the pipe Z _n
It is achieved by considering When the impedance Z _n of such a pipe is known, the pressure pulsation ΔP in the pipe in the frequency region based on this Z _n and the pressure fluctuation ΔP _c in the cylinder in the frequency region of the pressurization source are used to determine the cylinder First, the complex amplitude X _n of the n-th component of the volume of the fluid flowing in and out is obtained. Then, using the above X _n , the vibration flow rate of the fluid in the pipe
Find Q _n . Since this vibration flow rate Q _n is based on the impedance Z _{n of the} pipe, fluid coupling is naturally taken into consideration.

Next, the pressure pulse ΔP in the pipe in which the fluid coupling in the frequency domain is taken into consideration is obtained by using the above-mentioned vibration flow rate Q _n .

As described above, in a relatively simple system such as a single pressurizing source, the impedance Z _n of the pipe can be accurately estimated, so that the calculation method is relatively simple.

However, for example, if the pressure source is a plurality, the impedance when such as is a function of the Z _n is vibrating flow Q _n, the impedance Z _n is not known, it is first assumed value It is necessary to repeat the correction after giving it as. That is, in this case, from the pressure pulsation ΔP in the pipe in the frequency region based on the appropriately assumed pipe impedance Z _n , and the pressure fluctuation ΔP _c in the cylinder in the frequency region of the pressurization source, The complex amplitude X _n of the n-th component of the volume of fluid flowing in and out of is calculated. Next, using the above X _n , the fluid flow rate Q _n
Ask for. Subsequently, the pressure pulsation ΔP in the pipe corrected by taking into account the fluid coupling in the frequency domain is obtained by using the above-mentioned vibration flow rate Q _n . Further, the corrected pressure pulsation ΔP
The corrected impedance Z _n ′ of the pipe is calculated from
Z _n ′ is compared with the uncorrected impedance Z _n, and the above calculation procedure is repeated until the difference is within the predetermined range. The pressure in the pipe at the time when the impedance difference is within the predetermined range Adopt pulsation ΔP as the corrected pressure pulsation.

The above procedure will be described in detail below.

First, in step S1 in FIG. 1, constants required for calculation are input. Factors required for calculation are (1) factors related to fluid characteristics: sound velocity, density, average pressure, viscosity coefficient, bulk modulus, index of state change, etc. (2) factors related to piping characteristics, pipe length, pipe diameter, etc. (3) Factors related to characteristics of pressure source such as compressor When the piston movement, piston diameter, rotation speed and other constants are input, the complex amplitude X _n of the nth component of the volume of fluid flowing into and out of the pressure source cylinder is calculated ( S2). The complex amplitude _Xn is calculated based on the following calculation method.

Pressure fluctuation in the cylinder of the pressure source such as compressor, pump ΔP _c
Is It is represented by.

Here, γ is an index representing a change in the state of the fluid, P _o is the average pressure of the fluid in the pipe, V is the volume in the cylinder chamber, x is the volume of fluid flowing in and out of the cylinder chamber, y is the volume displacement of the piston.

On the other hand, expression of the Fourier expansion of the pressure variation [Delta] P in the pipe is expressed by ^{_{ΔP = ΣjnωZ n e jnωt ... (}} 2).

Where j ... Imaginary number n ... Order of Fourier expansion ω ... Rotation speed of pressure source such as compressor Z _n ... Impedance of piping X _n ... Complex amplitude of n-th order component of fluid flowing into cylinder t ... At time is there.

Here, ΔP _c = ΔP when the pipe and the pressure source are in communication with each other as described above, and when x is represented by Fourier expansion, x = ΣX _n e ^jnωt. Equation 3) is obtained.

The impedance Z _n of the pipe used in the above equations (1), (2), and (3) should be treated as known in a simple system or when Z _n is not a function of Q _n. However, if there are multiple pressure sources or if Z _n is a function of Q _n , it cannot be completely determined.

Therefore, in this embodiment, the impedance Z _n used in the equations (2) and (3) has a value that is initially assumed to be appropriate. The other values y, V, and ω are determined according to the specifications of the pressurizer, and γ and P _o are uniquely determined if the piping, fluid, and operating conditions are determined.

When the (3) is obtained, than this volume of fluid flowing into and out into the cylinder n th component complex amplitude X _n is obtained.
This procedure is step S2.

Since then vibrating flow Q _n of the pipe the fluid is a differential value of the x, = a ^ΣjnωX _n e jnωt, vibrating flow Q _n are obtained from the _{Q n = jnωX n ... (4} ) (S3) .

The vibration flow rate Q _n obtained in this way is based on fluid coupling, and by substituting this into the calculation method of the pressure pulsation value in the piping in the well-known frequency range, the piping considering the above-mentioned piping coupling is considered. The pressure pulsation value ΔP inside is calculated (S
Four).

Here, if the assumed Z _n is a proper value, the above S4
The corrected impedance Z _n ′ (S5) obtained by substituting the pressure pulsation Δ and the like obtained in step (2) into the equation (2) should be equal or approximate to the uncorrected impedance Z _n .

Therefore, when the piping system is simple or when Z _n is not a function of Q _n , the pressure pulsation value Δ
P may be output as the final result.

However, the if Z _n is not known, since the first assumed Z _n is not necessarily the proper value, by comparing the Z _n before modification and impedance Z _n 'obtained in step S5 (S6) If the difference between the two is larger than the predetermined range, the procedure from S2 to S6 is repeated using the corrected Z _n ′ as the newly assumed pipe impedance. The impedance Z _{n of} the pipe thus assumed is gradually corrected, and when it becomes suitable for the system, the Z _n before and after the correction match. The pressure pulsation value ΔP at this time is output as the final result.

When the pressure pulsation value ΔP is larger than the predetermined standard as a result of the calculation in this way, for example, the layout of the pipe (pipe inner diameter, pipe length, etc.) is changed, or a damping function (accumulator, orifice, etc.) is added. By doing so, pulsation can be attenuated.

〔The invention's effect〕

Since the present invention is configured as described above, it is possible to perform efficient and highly accurate analysis in consideration of coupling in the frequency domain.

[Brief description of drawings]

FIG. 1 is a flow chart showing a processing procedure of a pressure pulsation analyzer according to an embodiment of the present invention. [Explanation of symbols] Z _n … Piping impedance ΔP… Pressure pulsation in the pipe ΔP _c … Pressure fluctuation in the cylinder X _n … Nth-order component of the volume of fluid sucked into the cylinder Complex amplitude Q _n … of the fluid in the pipe Excitation flow rate Z _n ′… Impedance of modified pipe

Front Page Continuation (72) Inventor Kensuke Murai 8-16-8 Minoh, Minoh City, Osaka Prefecture (72) Inventor Shigetoshi Sato 2-3-1 Shinohara Aki Nonomachi, Nada-ku, Kobe City, Hyogo Prefecture

Claims (2)

[Claims] 1. A fluid flowing in and out of the cylinder based on pressure pulsation ΔP in the pipe in the frequency region based on the impedance Z _n of the pipe and pressure fluctuation ΔP _c in the cylinder in the frequency region of the pressure source. means for determining the volume of n-th order components complex amplitude X _n, means for determining the vibration rate Q _n of the fluid in the pipe in consideration of coupling fluid with the X _n, the frequency domain using the Q _n A pressure pulsation analysis device comprising: means for determining pressure pulsation ΔP in a pipe in consideration of fluid coupling in 2. Outflow into the cylinder due to pressure pulsation ΔP in the pipe in the frequency region based on the assumed impedance Z _n of the pipe and pressure fluctuation ΔP _c in the cylinder in the frequency region of the pressurization source. Nth-order component of the volume of the entering fluid complex amplitude X _n
And a means for determining the vibration flow rate Q _n of the fluid in the pipe considering the fluid coupling using the above X _n, and a fluid in the piping considering the fluid coupling in the frequency domain using the above Q _n . means for determining the pressure pulsation ΔP of 'seeking, the Z _n' impedance Z _n of the pipe that have been modified from the modified pressure pulsation ΔP before correction impedance
Means for comparing Z _n with each other, repeating the above-mentioned means until the difference is within a predetermined range, and obtaining a corrected pressure pulsation ΔP in the pipe at the time when the difference is within the predetermined range. Pressure pulsation analyzer.