Abstract:
This present application discloses an improved valve configuration such that an indicator port is incorporated directly within the valve allowing a sensing device to be mounted directly to the valve or within the valve body, this application being directed to both suction and discharge valves which sense at least one condition within a compressor comprising a cylinder, a piston, at least one discharge valve, and at least one suction valve, the valve further including a valve guard, a valve seat, a hollow area adapted and configured for housing a sensing device and a sensing device disposed within the hollow area.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 60/170,176, filed Dec. 10, 1999, and is related to commonly owned U.S. Pat. No. 5,567,121, issued on Oct. 22, 1996, both of which are incorporated herein by reference to the extent that they are not inconsistent with the present application. 
    
    
     BACKGROUND OF THE INVENTION 
     The present application relates to stationary compressors as used in power plants, refineries, pipeline compression of natural gas, and other installations where gasses are compressed for industrial purposes, and more particularly to the in-service monitoring and analysis, such as electronic analysis, of the condition and performance of such compressors, and most particularly to suction and discharge valves that are adapted and configured for facilitating in-service monitoring. 
     An industrial reciprocating gas compressor is a positive-displacement machine wherein the gas to be compressed is trapped in an enclosed space and then squeezed into a small volume by the action of a piston moving inside a cylinder. The gas is compressed to a pressure sufficient to overcome the discharge pressure plus the spring tension holding the discharge valve closed, at which time the discharge valve opens and allows the compressed gas to leave the cylinder. Because of the nature of the reciprocating piston, compression ceases at the limits of its stroke, the discharge valve again closes due to the action of the springs on the valve, the piston reverses direction, and the small amount of gas remaining in the cylinder expands, increasing in volume and decreasing in pressure. When the inlet pressure is higher than the pressure inside the cylinder plus the spring tension holding the suction valve closed, the suction valve then opens, allowing gas to flow into the cylinder. At the opposite limit of the piston stroke, the suction valve closes due to the springs acting on the valve, the piston again reverses direction, and the compression cycle begins anew. 
     The rate of pressure rise with respect to piston position in the cylinder, the exact moment of valve actuation, actual pressures attained, and other information concerning the compression, discharge, re-expansion, and inlet events taking place in the cylinder have long been recognized to be of value to engineers in assessing the operating condition of compressors. The first instrument used to record such information was a mechanical device which comprised a stylus attached to a pressure indicator and a rotating drum which was activated in proportion to the movement of the piston by a string attached to the crosshead of the compressor. The instrument was attached to the cylinder with a three-way valve, and sensed pressures inside the cylinder via passages (indicator ports) drilled during manufacture of the compressor. 
     The state of the analyzing art advanced during the 1960s with the introduction of the BETA 100, an oscilloscope device that utilized pressure transducers to sense pressure through indicator ports, and determined piston location from the angle of the crankshaft of the compressor. Further refinements of such electronic analyzers have been based on the principles of the early devices, and now include displays of pressure/volume or pressure/time, automatic calculation of horsepower consumed by the cylinder, and volumetric efficiency of the cylinder, as well as analysis of each valve event. Data from vibration transducers and ultrasound detectors (for analyzing the behavior of individual valves) are routinely superimposed on the pressure-volume trace to pinpoint operational problems and to determine the need for maintenance. Data from the analyzer may be sent to a personal computers for the automatic generation of reports. Significant savings in operational expenses and maintenance costs are attainable if the information is analyzed at routine intervals. 
     There was a time gap between the use of the drum-and-stylus instruments and the modem electronic instruments, however, and during that time gap manufacturers stopped providing indicator ports in cylinders and usually did not list indicator ports as an option when ordering a new machine. As a result, many compressors currently in operation do not have indicator ports and therefore cannot be analyzed properly. 
     Detailed description of a more or less contemporary monitoring system for reciprocating piston machines, including the use of pressure transducers, is given by Wiggins in U.S. Pat. No. 4,456,963, the disclosure of which is herein incorporated by reference. Other references to the use of pressure monitoring are given by Rice in U.S. Pat. No. 4,111,041 and Abnett et al in U.S. Pat. No. 4,325,128, the disclosures of which are incorporated herein by reference. However, none of these references utilize pressure transducers to sense the cylinder pressure through the center bolt of a suction or discharge valve or disclose indicator ports incorporated within the valve body, as disclosed herein. 
     Installation of indicator ports after the manufacture of the compressor traditionally involves the complete disassembly of the compressor and tedious machine shop work to locate and drill the indicator ports. During this process, the compressor must remain out of service for extended periods of time with lost production costs accumulating. Often, the cylinder casting does not have provisions for adding an indicator port, and installing one may entail penetration and sealing the water jacket surrounding the cylinder. Without indicator ports, much of the intelligence necessary for analysis is lost. Thus, there is clearly a need for a simple and effective system and method to equip compressors that have not been manufactured with indicator ports with means for monitoring compressor cylinder condition and performance. Such systems and methods should provide a means for monitoring compressor performance without significantly increasing the space required to house the compressor and at the same time should provide adequate protection for the sensitive monitoring equipment. 
     SUMMARY OF THE INVENTION 
     This present application discloses an improved valve configuration such that an indicator port is incorporated directly within either a suction or a discharge type valve thereby allowing a sensing device to be mounted directly to the valve or within the valve body. It is generally understood that suction and discharge valves used in certain applications such as compressors, can be interchangeable and therefore, this application is directed to both of these types of compressor valves and the disclosure herein is applicable to both suction and discharge valves. 
     An object of the present application is to provide a simple and effective system and method to equip compressors with means for monitoring compressor cylinder condition and performance. Yet another object of the present application is to provide a location within the valve for the sensing device that inherently protects it from damage, enabling the device to function properly and increasing its expected service life. 
     Still yet another object of the present application is to simplify the installation of the sensing device by allowing it to be provided as part of a complete assembly. The sensing device can be provided already installed within a replacement valve for an existing compressor, or it can be provided as part of a valve assembly to be installed in a new compressor. 
     In accordance with these and further objects, one aspect of the present application includes a valve for sensing at least one condition within a compressor comprising a compressor cylinder, a piston, at least one discharge valve, and at least one suction valve. The valve includes a valve guard defining outlet flow ports and having a central aperture being disposed therein. The valve further includes a valve seat defining inlet flow ports and having a central aperture. An elongated structure such as an elongated stud is operatively engaged in the central aperture of the valve guard and valve seat and defines a central axis for the valve. The elongated structure has a hollow core which creates an indicator port extending from the interior of the compressor cylinder to an exterior terminus at the exterior of the valve. Additionally, a sensing device is operatively connected to the exterior terminus of the indicator port. The sensing device may comprises a pressure transducer for sensing pressure in the interior of the compressor cylinder. Alternatively, the sensing device may comprise a means for sensing the temperature, vibration, gas flow or the position of the piston within the compressor. 
     The present application is also directed to a valve for sensing at least one condition within a compressor comprising a compressor cylinder, a piston, at least one discharge valve, and at least one suction valve. The valve includes a valve seat defining inlet flow ports through which gas enters the valve and a valve guard defining outlet flow ports through which the gas exits the valve. A hollow area is operatively positioned in the valve guard or valve seat which is adapted and configured for housing a sensing device. 
     The valve further includes a bore in the valve seat for facilitating electrical communication with the sensing device. Electrical signal communicating structure, such as wiring, extends through this bore and connect the sensing device to a monitoring device. The monitoring device translates the signal received from the sensing device to data which can be interpreted by an operator, engineers or maintenance personnel in order to evaluate the condition and performance of the compressor. Preferably, the sensing device is a pressure transducer for sensing pressure in the interior of the compressor cylinder. Alternatively, the sensing device can be a means for sensing temperature or other condition within the interior of the compressor cylinder. 
     The present application is also directed to a system for sensing at least one condition within a compressor comprising a compressor cylinder, a piston, at least one discharge valve, and at least one suction valve. The valve includes a valve guard defining outlet flow ports, a valve seat defining inlet flow ports, a hollow area operatively positioned in the valve guard or valve seat, a sensing device operatively positioned within the hollow area, and a monitoring device located exterior to the valve in communication with the sensing device. 
     Other objects, features and advantages of the present application will be apparent from the following description, the accompanying drawings and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectioned view of a reciprocating compressor which includes a cylinder, a piston, a piston rod, two suction valves, two discharge valves, a sensing device, and a monitoring device; 
     FIG. 2 is a cross-sectioned view of a suction valve having an elongated stud centered therein, the stud having a hollow core defining an indicator port and also having a sensing device operatively connected to the exterior terminus of the indicator port; 
     FIG. 3 is a cross-sectioned view of a discharge valve having an elongated stud centered therein, the stud having a hollow core defining an indicator port with a sensing device operatively connected to the exterior terminus of the indicator port; 
     FIG. 4 is a cross-sectioned view of a suction valve having a valve guard having a hollow area in which a sensing device is housed; and 
     FIG. 5 is a cross-sectioned view of a discharge valve having a valve guard which includes a hollow area in which a sensing device is housed and a valve seat defining an indicator port. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings where like reference numerals identify similar structural elements of the subject invention and flow arrows designated as I and O represent the direction of gas flow into and out of the valve respectively. 
     Illustrated in FIG. 1, is a system for sensing at least one condition within a reciprocating compressor constructed in accordance with the present application and designated generally by reference numeral  100 . Compressor  100  includes suction valves  110  and  120 , discharge valves  130  and  140 , compressor cylinder  150 , piston rod  160 , piston  170 , sensing device  132 , and monitoring device  190 . 
     In operation, gas  180  is trapped in an enclosed space between piston  170  and the compressor cylinder  150  and then squeezed into a small volume by the action of a piston  170  moving inside cylinder  150  as indicated by directional arrow D. The gas  180  is compressed to a pressure sufficient to overcome the discharge pressure plus the spring tension holding the discharge valve  130  closed, at which time the discharge valve  130  opens and allows the compressed gas to leave cylinder  150 . Because of the nature of the reciprocating piston  170 , compression ceases at the limits of its stroke, the discharge valve  130  again closes due to the action of springs on the valve  130 , the piston  170  reverses direction, and the small amount of gas  180  remaining in the cylinder  150  expands, increasing in volume and decreasing in pressure, until the inlet pressure is higher than the pressure inside the cylinder  150  plus the spring tension holding the suction valve  110  closed. The suction valve  110  then opens, allowing gas  180  to flow into the cylinder  150 . At the opposite limit of the piston  170  stroke, the suction valve  110  closes due to springs acting on the valve  110 , the piston  170  again reverses direction, and the compression cycle begins anew. 
     As shown in FIG. 1, discharge valve  140  has a sensing device  132  disposed therein and wires or electrical signal communicating structure  134  operatively connected to sensing device  132  and monitoring device  190 . The rate of pressure rise with respect to piston  170  position in the cylinder  150 , and other information concerning the compression, discharge, and re-expansion taking place in the cylinder  150  is measured by sensing device  132  and transmitted to monitoring device  190 , allowing engineer, operators or maintenance personnel to assess the operating condition and performance of compressor  100 . 
     Referring now to FIG. 2, a specific valve for installation in a compressor that facilitates monitoring at least one condition within a compressor constructed in accordance with one embodiment and designated generally by reference numeral  200 . As shown in FIG. 2, valve  200  operates as a suction valve for compressor  100  (see FIG.  1 ), allowing gas to be drawn into the compressor cylinder, and includes a valve guard  210  defining outlet flow ports  212   a - 212   e  and a central aperture  214 . Valve guard  210  is operatively associated with the compressor cylinder at surface  238 . 
     Valve  200  also includes a valve seat  220  defining inlet flow ports  222   a - 222   e  and a central aperture  224  adapted and configured for receiving elongated stud or elongated structure  230 . Elongated structure  230  is positioned within central apertures  214  and  224  and provides a central axis for valve  200 . Nut  252  is engaged on exterior terminus  234  of elongated structure  230  and connects valve guard  210  to valve seat  220 . Elongated structure  230  has a hollow core  232  creating an indicator port  236  extending from surface  238  to exterior terminus  234  at the exterior of valve  200 . Sensing device  240  is operatively connected to exterior terminus  234  of indicator port  236 . Indicator port  236  allows sensing device  240  to sense at least one condition within the compressor  100  (see FIG. 1) by providing a conduit for the gas within the cylinder to reach sensing device  240 . Sealing member  250  is operatively positioned between sensing device  240  and exterior terminus  234  and prevents the gas within indicator port  236  from escaping to the exterior of valve  200 . In a preferred embodiment, sensing device  240  is a pressure transducer for sensing pressure internal to the compressor. 
     Referring now to FIG. 3, a valve for installation in a compressor that facilitates sensing at least one condition within a compressor constructed in accordance with a second embodiment and designated generally by reference numeral  300 . As shown in FIG. 3, valve  300  operates as a discharge valve for compressor  100  (see FIG.  1 ), allowing compressed gas to be discharged from the cylinder, and includes a valve guard  310  defining outlet flow ports  312   a - 312   e  and a central aperture  314 . 
     Valve  300  also includes a valve seat  320  defining inlet flow ports  322   a - 322   e  and a central aperture  324  adapted and configured for receiving elongated stud  330 . Elongated stud  330  is positioned within central apertures  314  and  324  and provides a central axis for valve  300 . Valve seat  320  is operatively associated with the compressor cylinder at surface  338 . As illustrated previously for suction valve  200  (see FIG.  2 ), elongated stud or elongated structure  330  has a hollow core  332  creating an indicator port  336  extending from surface  338  to exterior terminus  334 . Also, sensing device  340  is operatively connected to exterior terminus  334  of indicator port  336 . Indicator port  336  allows sensing device  340  to sense at least one condition within the compressor  100  (see FIG. 1) by providing a conduit for the gas within the compressor to reach sensing device  340 . 
     Referring now to FIG. 4, there is illustrated a valve for sensing at least one condition within a compressor constructed in accordance with a third embodiment and designated generally by reference numeral  400 . The valve  400  illustrated, operates as a suction valve for a compressor, allowing gas to be drawn into the compressor cylinder, and includes a valve guard  410  defining outlet flow ports  412   a - 412   e  and having a hollow area  414  disposed therein. Valve guard  410  is operatively associated with the compressor cylinder at surface  438 . 
     Valve  400  also includes a valve seat  420  defining inlet flow ports  422   a - 422   e  and a central aperture  424 . The hollow area  414  in valve guard  410  is adapted and configured for housing sensing device  440 , hollow area  414  having a hole extending from its base, creating indicator port  416  and allowing sensing device  440  to sense conditions within the compressor cylinder at surface  438 . Engagement pin  460  secures valve seat  420  to valve guard  410 . 
     Valve  400  further includes a sealing member  450  operatively positioned in the space between sensing device  440  and hole  416 . The sealing member  450  prevents gas internal to the compressor cylinder from entering into the hollow area  414  and exiting valve  400  through central aperture  424 . 
     Presently it is preferred that sensing device  440  includes a transducer means for generating at least one signal as a function of pressure within the compressor cylinder. Alternately, the sensing device  440  may include a transducer for sensing the timing of the opening and closing of valve  400 . Wires or electrical signal communicating structure  442  are in electrical connectivity with sensing device  440  and pass through central aperture  424  to a monitoring device  190  (see FIG.  1 ), transmitting a signal which is a function of the pressure within the compressor. 
     Referring now to FIG. 5, there is illustrated a valve for sensing at least one condition within a compressor constructed in accordance with an fourth embodiment of the present application and designated generally by reference numeral  500 . Valve  500  operates as a discharge valve for a compressor, allowing compressed gas to exit the compressor cylinder, and includes a valve seat  520  defining inlet flow ports  522   a - 522   e  and having an indicator port  524  disposed therein. Valve seat  520  is operatively associated with the compressor cylinder at surface  538 . 
     Valve  500  also includes a valve guard  510  defining outlet flow ports  512   a - 512   e  and hollow area  514 . Hollow area  514  in valve guard  510  is adapted and configured for housing sensing device  540 , hollow area  514  having hole  516  which allows wires or other electrical signal communicating structure  542  to connect sensing device  540  to monitoring device  190  (see FIG.  1 ). Indicator port  524  allows sensing device  540  to sense conditions from within the cylinder of compressor  100  (see FIG.  1 ). Engagement pin  560  secures valve seat  520  to valve guard  510 . Presently, it is preferable that sensing device  540  comprises a transducer means for generating at least one signal as a function of pressure within the compressor cylinder. Alternatively, sensing device  540  may include a transducer for measuring temperature, vibration, flow or the position of the piston within the compressor cylinder as would be understood by those skilled in the art. 
     It should be clear that the system, including the valve, and the methods disclosed herein have met the objectives of the present application. Specifically, the incorporation of indicator ports within a valve provide a simple and effective method for equipping compressors with means for monitoring compressor cylinder condition and performance. Additionally, locating the sensing devise within the valve inherently protects the device from being damaged as a result of a variety of conditions that may exist on the exterior of the compressor, thus increasing the sensors service life. 
     Still yet by providing indicator ports within the valve thereby allowing the sensing device to be installed directly on the valve stud or within the valve itself, the installation of the sensing device is simplified. These configurations allow it to be provided as part of a complete assembly with either a replacement valve or as part of a valve assembly to be installed in a new compressor. 
     While the articles and methods described herein constitute preferred embodiments of the present application, it is understood that the present application is not limited to the precise articles and methods and that changes may be made therein without departing from the scope of the present application which is defined by the appended claims.