Patent Application
20110085920
The field of the invention relates generally to reciprocating compressors, and more specifically to simulating attenuation of an impulse signal of a reciprocating compressor.
At least some known reciprocating compressors are capable of providing high pressure along with variable loading and are favored for many gas process applications in various manufacturing industries. Increased compressor reliability targets have highlighted a need for identification of problems that may be associated with such compressors, such as wear of the reciprocating drive train.
For example, the mounting of seismic transducers to a reciprocating compressor is a standard method of monitoring the health of its machine train components. The attenuation of impulse signals over a period of time is a sign that the components are beginning to wear. However, there is a problem of not being able to effectively demonstrate a change in impulse signal, generated by the mechanical components of a reciprocating compressor in a timely manner.
In one aspect, a method of simulating attenuation of an impulse signal of a reciprocating compressor is provided. The method includes providing a reciprocating compressor that includes a motor, a crank connected to the motor, a compression chamber, a reciprocating piston positioned in the compression chamber, and a connecting rod attached to the piston. The method also includes connecting the connecting rod to the crank with a first crank pin, mounting at least one transducer on the reciprocating compressor, running the compressor for a first predetermined time, measuring a first impulse signal with the at least one transducer, replacing the first crank pin with a second crank pin, the second crank pin having a diameter different than the diameter of the first crank pin, running the compressor for a second predetermined time, measuring a second impulse signal with the at least one transducer, comparing the first impulse signal to the second impulse to determine an amount of attenuation between the first and second impulse signals.
In another aspect, a reciprocating compressor demonstration apparatus is provided. The demonstration apparatus includes a compression chamber, a piston movable within said compression chamber, a crank connect to and turned by a motor, a connecting rod attached at a first end to said piston and at an opposing second end to said crank, and a first crank pin and a second crank pin. The first crank pin or the second crank pin is used to connect the connecting rod to the crank. The demonstration apparatus also includes at least one transducer positioned to detect an impulse signal.
In another aspect, a method of simulating attenuation of an impulse signal of a reciprocating compressor is provided. The compressor includes a crank connected to a motor, and a connecting rod connected to a piston at one end and the crank at an opposing end. The method includes connecting the connecting rod to the crank with a first crank pin, mounting at least one transducer on the reciprocating compressor, measuring a first impulse signal with the at least one transducer while the reciprocating compressor is running, and replacing the first crank pin with a second crank pin. The second crank pin has a diameter different than the diameter of the first crank pin. The method also includes measuring a second impulse signal with the at least one transducer while the reciprocating compressor is running, and comparing the first impulse signal to the second impulse to determine an amount of attenuation between the first and second impulse signals.
A method of simulating attenuation of an impulse signal of a reciprocating compressor and a reciprocating compressor demonstration apparatus is described below in detail. The demonstration apparatus permits a user to attenuate the impulse signal of the reciprocating compressor drivetrain by inducing radial clearance between the connecting rod crank-end bearing bushing and the crank pin. A radial clearance between the bearing bushing and the crank pin is induced by removing the crank pin and installing a different crank pin having a different diameter. The crank pin is a direct interface between the crank and the connecting rod. A larger clearance between the bearing bushing and the crank pin creates a “louder” mechanical impulse event signal. The method permits a user to effectively demonstrate a change in the impulse signal generated by the mechanical components of the reciprocating compressor in a user friendly and timely manner.
Referring to the drawings,
A piston 22 is positioned in compression chamber 14 and includes a piston head portion 24 and a piston rod portion 26. Piston 22 is movable in a reciprocating motion within compression chamber 14 to suction air into compression chamber 14 during an “out” stroke, and to compress the air during an “in” stroke. The distal end 27 of piston rod portion 26 is attached to a crosshead 28 positioned in a crosshead frame 30. Crosshead 28 includes a threaded cavity 32 sized to threadedly receive a threaded portion 34 of distal end 27 of piston rod portion 26. Cross head 28 is coupled to a proximate end 38 of connecting rod 40 by a crosshead pin 36. A distal end 42 of connecting rod 40 is attached to a crank 44 that is operatively coupled to a motor 12.
Referring also to
The diameter 64 of crank pin center portion 60 is approximately equal to the inside diameter 66 of bushing 52 to facilitate a minimum radial clearance between bushing 52 and the crank pin center portion 60. A second crank pin 70, similar to crank pin 56, includes a threaded end portion 72, a cylindrical center portion 74 and a head portion 76. The diameter 78 of second crank pin center portion 74 has a smaller diameter than the inside diameter 66 of bushing 52. The smaller diameter of center portion 74 creates a radial clearance between bushing 52 and crank pin center portion 74.
The radial clearance between the bearing bushing and the crank pin is induced by removing crank pin 56 and installing second crank pin 70 having a diameter 78 that is smaller than the diameter 64 of crank pin 56. The smaller diameter of second crank pin 70 creates a radial clearance between second crank pin 70 and bushing 52. When installed, crank pins 56 and 70 are a direct interface between crank 44 and connecting rod 40. A larger clearance between bushing 52 and second crank pin 70 creates a “louder” mechanical impulse event signal during the operation of reciprocating compressor demonstration apparatus 10. At least one transducer 80 is coupled to demonstration apparatus 10 to detect the impulse signal.
Reciprocating compressor demonstration apparatus 10 is used to simulate the attenuation of impulse signals as a sign that components of a reciprocating compressor are beginning to wear. To simulate the attenuation of impulse signals, connecting rod 40 is attached to circular end portion 48 of crank 44 by inserting crank pin 56 through bushing 52 and threading end portion 58 of crank pin 56 into threaded opening 50 of circular end portion 48 of crank 44. Reciprocating compressor demonstration apparatus 10 is then run and a first impulse signal is detected by transducers 80 for measurement. Then, crank pin 56 is removed and second crank pin 70 is used to attach connecting rod 40 to circular end portion 48 of crank 44. Second crank pin 70 is inserted through bushing 52 and end portion 72 of crank pin 70 is threaded into threaded opening 50 of circular end portion 48 of crank 44. Reciprocating compressor demonstration apparatus 10 is then run and a second impulse signal is detected by transducers 80 for measurement. The larger clearance between bushing 52 and second crank pin 70 simulates component wear of the crank to connecting rod juncture. Comparing the first and the second impulse signal will show that the second impulse signal is larger or “louder” than the first impulse signal which demonstrates worn compressor components.
In another embodiment, shown in
To simulate the attenuation of impulse signals, connecting rod 40 is attached to circular end portion 48 of crank 44 by inserting crank pin 56 through bushing 52 and threading end portion 58 of crank pin 56 into threaded opening 50 of circular end portion 48 of crank 44. Reciprocating compressor demonstration apparatus 10 is then run and a first impulse signal is detected by transducers 80 for measurement. Then, bushing 54 is removed and second bushing 82 is positioned in opening 54 of connecting rod 40. Crank pin 56 is inserted through bushing 82 and end portion 58 of crank pin 56 is threaded into threaded opening 50 of circular end portion 48 of crank 44. Reciprocating compressor demonstration apparatus 10 is then run and a second impulse signal is detected by transducers 80 for measurement. The larger clearance between bushing 82 and crank pin 56 simulates component wear of the crank to connecting rod juncture. Comparing the first and the second impulse signal will show that the second impulse signal is larger or “louder” than the first impulse signal which demonstrates worn compressor components. In another embodiment, bushing 52 has an adjustable inside diameter so that the impulse event signal can be affected by adjusting the inside diameter of bushing 52 to create different clearances between bushing 52 and crank pin 56.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
