Method for obtaining p-V diagram of reciprocating compressor by measuring piston rod strain

Abstract

The invention discloses a method for obtaining a p-V diagram of a reciprocating compressor by measuring the piston rod strain. A rod load is obtained according to the measured piston rod strain, a change curve of gas force resultant force is obtained by subtracting reciprocating inertial force from the rod load, then the curve of the gas force resultant force is subjected to nonlinear regression through a Fourier series form, a fitting function of the gas force resultant force is obtained, then an axial side air pressure function is expressed in the Fourier series form to obtain a cover side air pressure function, then an equation where the gas force resultant force is the sum of axial side gas force and cover side gas force is solved, and coefficients of air pressure function are obtained, then the axial side and the cover side pressure functions (p-theta diagram) are obtained, and thus the p-V diagram is obtained. According to the method for obtaining the p-V diagram of the reciprocating compressor by measuring the piston rod strain, on the one hand, punching on the compressor is avoided, and the problem of destroying a compressor body in the prior art is avoided; and on the other hand, through data collection, calculation and fitting, the curve can reflect the processes of suction, exhaust, expansion and compression, and fault diagnosis and operation status monitoring can beconducted according to the p-V diagram.

Description

technical field [0001] The invention belongs to the technical field of reciprocating compressors, and in particular relates to a method for obtaining a p-V diagram of a reciprocating compressor by measuring the strain of a piston rod. Background technique [0002] Reciprocating compressors have a wide range of applications. In theory, they can compress all gases. Regardless of the flow rate, the required pressure can be reached. The volumetric efficiency is high, and it can adapt to oil and oil-free conditions. It is considered to be the most efficient gas compression equipment and is widely used. It is used in various fields of the national economy such as refrigeration and air conditioning, air power, petrochemical and natural gas industries. Once the reciprocating compressor fails, it will affect the entire process and cause serious or even catastrophic consequences. In order to prevent accidents, it is very important to monitor the condition of the compressor and diagno...

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Problems solved by technology

[0004] Nowadays, the compressors manufactured according to the API618 standard are equipped with pressure measuring holes, and most of the old compressors still in service have no pressure measuring holes, so measuring the pressure change in the cylinder needs to process the cylinder, and some special compression It is not allowed to process pressure measuring holes on the cylinder of the process compressor of the medium. In addition, the opening of the cylinder wall will also affect the strength of the cylinder, posing a potential threat. Such an intrusive measurement method seriously limits the popularization and application of the p-V diagram diagnostic method

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