Stuffing box with degradation monitoring function

Abstract

A method of monitoring degradation of a seal of a stuffing box includes: receiving a signal from a first temperature sensor (170) mounted at a first location in a housing of the stuffing box; receiving a signal from a second temperature sensor (172) mounted at a second position in the housing of the stuffing box; calculating a temperature difference between the first temperature sensor (170) and the second temperature sensor (172) at two or more times from the signals; and determining a deterioration indicator of at least one of the seals (138a-138d) of the stuffing box at least partially from the temperature differences at the two or more times.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Patent Serial No. 63 / 417,931, filed October 20, 2022, and U.S. Application Serial No. 63 / 422,233, filed November 3, 2022, under 35 U.S.C.§119, the content of each application is hereby incorporated by reference. Technical field

[0003] The present invention relates to a sealed shaft of high - pressure gas handling equipment (such as a reciprocating compressor), particularly a sealed shaft having a progressive sealing system. Background art

[0004] When a high pressure differential needs to be maintained (such as between the atmosphere and a high - pressure inner cavity into which a moving shaft extends), a progressive sealing system or a multi - stage sealing system is typically employed. Effective and reliable sealing often requires a sealing system in which the pressure drops in stages along the shaft or progressively along a labyrinth. The compression industry strives to increase the maximum allowable operating pressure and system speed according to higher customer specifications. However, increasing the pressure differential generally makes it more difficult to contain the gas within the system and also places greater stress on the associated sealing elements, resulting in increased pressure pulsations within the system, increased lubricant consumption, and poor venting of gas to the atmosphere. The pressures encountered during operation can cause the seals to wear and reduce reliability.

[0005] The packing box for a reciprocating compressor operates with a series of rod rings in a separate housing. The compressor stroke of a reciprocating compressor is a dynamic event that occurs within a very short time frame (e.g., 20 times per second for a 1200 RPM compressor).

[0006] The service life of the sealing components of a progressive sealing system (such as a packing box) varies depending on load conditions, seal material properties, environmental conditions, and other factors. The risk of seal failure can be partially addressed by performing regular maintenance to replace the seals before they fail. Nevertheless, the uncertainty in the actual performance of a given sealing system during operation can lead to premature maintenance of a particular system or, in a worse - case scenario, late maintenance. Summary of the invention

[0007] In the context of a packing box for a gas - handling system (such as a reciprocating compressor), the embodiments described herein may have particular utility.

[0008] In one aspect of the present disclosure, a method for monitoring the deterioration of a stuffing box seal includes: receiving a signal from a first temperature sensor mounted at a first location in the housing of the stuffing box; receiving a signal from a second temperature sensor mounted at a second location in the housing of the stuffing box; calculating a temperature difference between the first temperature sensor and the second temperature sensor at two or more times from these signals; and determining a deterioration index of at least one of the seals of the stuffing box at least in part from the temperature differences at the two or more times.

[0009] In some embodiments, the stuffing box defines a cylinder side and a driver side, the first location is on the cylinder side of one of the seals of the stuffing box, and the second location is on the driver side of one of the seals of the stuffing box.

[0010] In some embodiments, the first temperature sensor and the second temperature sensor are axially spaced apart from each other along the length of the stuffing box.

[0011] In some embodiments, at least one of the temperature sensors is embedded in an opening in the housing of the stuffing box.

[0012] In some embodiments, the deterioration index is at least in part based on an increase in the temperature difference over time between the first temperature sensor and the second temperature sensor.

[0013] In some embodiments, the deterioration index is at least in part based on one or more changes in the temperature difference over time between the first temperature sensor and the second temperature sensor.

[0014] In some embodiments, the deterioration index is at least in part based on the maximum temperature difference between the first temperature sensor and the second temperature sensor.

[0015] In some embodiments, the deterioration index is at least in part based on an increase in the temperature difference over time in the first temperature sensor.

[0016] In some embodiments, at least one of the deterioration indices is at least in part based on a derived leakage flow rate.

[0017] In some embodiments, the method includes: sensing the pressure in the stuffing box and determining a deterioration index of at least one of the seals of the stuffing box from at least one sensed pressure.

[0018] In some embodiments, the pressure is sensed on the cylinder side of at least one of the temperature sensors.

[0019] In some embodiments, the pressure is sensed on the driver side of at least one of the temperature sensors.

[0020] In some embodiments, the pressure is sensed in the lubricating oil line of the stuffing box.

[0021] In some embodiments, the pressure is sensed in the ventilation line of the stuffing box.

[0022] In some embodiments, the method includes providing a notification to a user based on the degradation metric.

[0023] In another aspect of the present disclosure, a stuffing box monitoring system includes a first temperature sensor, a second temperature sensor, and a computing device. The stuffing box has two or more seals and defines a cylinder side and a driver side. The first temperature sensor is coupled to the housing of the stuffing box and is configured to sense the temperature of the cylinder side of one of the seals. The second temperature sensor is coupled to the housing and is configured to sense the temperature of the driver side of one of the seals. The computing device is communicatively coupled to the first temperature sensor and the second temperature sensor. The computing device is configured to: receive signals from the first temperature sensor and the second temperature sensor; calculate a temperature difference between the first temperature sensor and the second temperature sensor at two or more times from the signals; and determine a degradation metric of at least one of the seals of the stuffing box at least in part from the temperature difference at the two or more times.

[0024] In some embodiments, the two or more seals include a breaker, a first seal, a second seal, and a third seal. The first seal is axially disposed on the driver side of the breaker. The second seal is axially disposed on the driver side of the first seal. The third seal is axially disposed on the driver side of the second seal. One of the seals is the third seal. The first temperature sensor is axially disposed between the second seal and the third seal.

[0025] In some embodiments, the second temperature sensor is axially disposed between the third seal and an end plate seal.

[0026] In some embodiments, the two or more seals include a second seal that is axially disposed on the cylinder side of one of the seals. The system further includes a third temperature sensor that is axially disposed on the cylinder side of the second seal. The computing device is communicatively coupled to the third temperature sensor. The computing device is configured to calculate a temperature difference between the third temperature sensor and at least one of the first temperature sensor and the second temperature sensor.

[0027] In some embodiments, the monitoring system includes a pressure sensor configured to sense the pressure on the cylinder side of one of the seals.

[0028] In some embodiments, the monitoring system includes a pressure sensor coupled to the lubricating oil line of the stuffing box.

[0029] In some embodiments, the monitoring system includes a pressure sensor configured to sense the pressure on the driver side of one of the seals.

[0030] In some embodiments, the monitoring system includes a pressure sensor coupled to the ventilation line of the stuffing box.

[0031] In some embodiments, the stuffing box monitoring system is communicatively coupled to a cylinder side pressure sensor, wherein the stuffing box monitoring system is configured to determine a degradation index from the information received from the cylinder side pressure sensor.

[0032] In some embodiments, the stuffing box monitoring system is communicatively connected to a driver side pressure sensor, wherein the stuffing box monitoring system is configured to determine a degradation index from the information received from the driver side pressure sensor.

[0033] In some embodiments, the stuffing box monitoring system is configured to provide a notification of the degradation index to the user.

[0034] In some embodiments, the stuffing box monitoring system is configured to provide a notification to the user regarding the degradation of one or more of the seals.

[0035] In some embodiments, the stuffing box monitoring system is configured to provide a notification to the user regarding the maintenance event time setting of one or more of the seals of the stuffing box, at least in part based on the degradation index.

[0036] In some embodiments, the stuffing box monitoring system is configured to provide a warning to the user regarding seal failure in the stuffing box, at least in part based on the degradation index.

[0037] In some embodiments, the stuffing box monitoring system is configured to provide a predictor for one or more of the seals of the stuffing box to the user, at least in part based on the degradation index.

[0038] In another aspect of the present disclosure, a stuffing box assembly includes a plurality of seals, a housing, an end plate, a first temperature sensor, and a second temperature sensor. The housing is configured to accommodate at least two of the seals. The end plate is coupled to the housing. The first temperature sensor is coupled to the housing of the stuffing box and is configured to sense the temperature on the cylinder side of one of the seals. The second temperature sensor is coupled to the housing and is configured to sense the temperature on the driver side of one of the seals.

[0039] In another aspect of the present disclosure, a reciprocating compressor system includes a compression cylinder, a driver, a rod, a stuffing box through which the rod passes, and a stuffing box monitoring system. The compression cylinder defines a compression chamber. The rod is coupled between the driver and the compression cylinder. The driver is operable to reciprocate the rod such that gas is compressed in the compression chamber. The stuffing box is located between the compression cylinder and the driver. The stuffing box defines a cylinder side and a driver side. The stuffing box includes a plurality of seals through which the rod passes; a housing configured to accommodate at least two of the seals; and an end plate coupled to the housing. The stuffing box detection system includes a stuffing box monitoring system that includes a first temperature sensor, a second temperature sensor, and a computing device. The first temperature sensor is coupled to the housing of the stuffing box and is configured to sense the temperature on the cylinder side of one of the seals. The second temperature sensor is coupled to the housing and is configured to sense the temperature on the driver side of one of the seals. The computing device is communicatively coupled to the first temperature sensor and the second temperature sensor. The computing device is configured to: receive signals from the first temperature sensor and the second temperature sensor; calculate a temperature difference between the first temperature sensor and the second temperature sensor at two or more times from the signals; and determine a degradation index for at least one of the seals of the stuffing box at least in part from the temperature difference at the two or more times.

[0040] In another aspect of the present disclosure, a method of monitoring degradation of a stuffing box seal includes: receiving signals from one or more temperature sensors mounted in the housing of the stuffing box; receiving signals from one or more pressure sensors coupled to the housing of the stuffing box; calculating a temperature at two or more times and a pressure at two or more times from the signals; and determining one or more degradation indices for at least one of the seals of the stuffing box from at least one of the temperatures and at least one of the pressures.

[0041] In some embodiments, at least one of the degradation indices is determined from two or more temperatures.

[0042] In some embodiments, at least one of these degradation metrics is determined from two or more pressures.

[0043] In some embodiments, at least one of these degradation metrics is determined from a derived leakage flow rate.

[0044] In some embodiments, at least one of these degradation metrics is an early degradation metric.

[0045] In some embodiments, at least one of these degradation metrics is a mid - stage degradation metric.

[0046] In some embodiments, at least one of these degradation metrics is a late - stage degradation metric.

[0047] In another aspect of the present disclosure, a stuffing box monitoring system includes one or more temperature sensors, one or more pressure sensors, and one or more computing devices. The one or more temperature sensors are coupled to the housing and are configured to sense the temperature at at least one location in the stuffing box. The one or more pressure sensors are fluidly coupled to one or more spaces in the stuffing box and are configured to sense the pressure at at least one location in the stuffing box. The computing device is communicatively coupled to at least one of the one or more temperature sensors and at least one of the one or more pressure sensors. The computing device is configured to: receive signals from the at least one temperature sensor and the at least one pressure sensor; and calculate a degradation metric for at least one of the seals of the stuffing box from the signals from at least one of the temperature sensors and at least one of the pressure sensors.

[0048] In some embodiments, the one or more temperature sensors include two or more temperature sensors, wherein the computing device is configured to calculate a temperature difference at two or more times based on signals from the temperature sensors.

[0049] In some embodiments, at least one of the pressure sensors is coupled to the ventilation line of the stuffing box.

[0050] In some embodiments, at least one of the pressure sensors is coupled to the lubricating oil line of the stuffing box.

[0051] In another aspect of the present disclosure, a stuffing box assembly includes a plurality of seals, a housing, an end plate, one or more temperature sensors, and one or more pressure sensors. The housing is configured to accommodate at least two of the seals. The end plate is coupled to the housing. The one or more temperature sensors are mounted in the housing of the stuffing box and are configured to sense the temperature in the stuffing box. The one or more pressure sensors are coupled to the housing and are configured to sense the pressure in one or more spaces in the stuffing box.

[0052] In another aspect of the present disclosure, a method for detecting seal wear in a progressive seal system includes: receiving signals from one or more temperature sensors coupled to the housing of the progressive seal system; calculating temperatures associated with the temperature sensors at two or more times from the signals; and determining a degradation metric for at least one of the seals in the progressive seal system at least in part from the temperatures calculated at the two or more times.

[0053] In some embodiments, the method includes: sensing the pressure in one or more spaces in the progressive seal system and determining a degradation metric for at least one of the seals in the progressive seal system at least in part from the sensor pressures at the two or more times.

[0054] Details of one or more embodiments of the subject matter of the present disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Schematically depicts a single-stage gas processing system having a multi-stage seal system.

[0056] Figure 2 Is a perspective view of a part of a reciprocating shaft compressor.

[0057] Figure 3 Is an end view of the compressor section of the gas processing system.

[0058] Figure 4 And Figure 5 Are cross-sectional views of the shaft shown at opposite ends of the stroke of the shaft.

[0059] Figure 6 Is Figure 3 An exploded view of the compressor section of.

[0060] Figure 7 Is a block diagram of a compressor system having a stuffing box monitoring system according to some embodiments.

[0061] Figure 8 A cross-sectional view of a stuffing box including a temperature sensor according to some embodiments.

[0062] Figure 9 The temperature sensor in the stuffing box is shown.

[0063] Figure 10 The reverse side of the end plate of the stuffing box is shown, and the end plate includes a channel for the temperature sensor wire.

[0064] Figure 11 A pressure sensor for sensing dynamic pressure according to some embodiments is shown.

[0065] Figure 12 A pressure sensor for sensing dynamic pressure according to some embodiments is shown.

[0066] Figure 13 A graph showing temperature monitoring performed in a compressor stuffing box using a temperature sensor installed in the stuffing box housing.

[0067] Figure 14 A process for monitoring a stuffing box using temperature measurement according to some embodiments is shown.

[0068] Figure 15 A process for monitoring a stuffing box using temperature measurement and pressure measurement according to some embodiments is shown.

[0069] Figure 16 A stuffing box having temperature sensors between each seal in the seals of the stuffing box according to some embodiments is shown.

[0070] Like reference numerals in different figures indicate like elements. Detailed Description

[0071] In various embodiments, a gas treatment system includes a monitoring system for a progressive seal system of the gas treatment system. The monitoring system can use measurements of temperature, pressure, or both to determine an indicator of seal condition and estimate or predict the service life stage of these seals in the progressive seal system.

[0072] Figures 1 to 6 A compressor is shown that can be provided with instrumentation for monitoring the condition of seals in a gas treatment system as described herein.

[0073] For ease of explanation, when describing the relative position of system components or features, the "driver side" may also be referred to herein as the "crank side" or the "outer side". The "cylinder side" may also be referred to as the "head side".

[0074] First, refer to Figure 1, the gas processing system 100 includes a compressor 102 having a container 104 and a driver 106. The container 104 defines an inner cavity having a process gas inlet 108 and a process gas outlet 110. The compressor 102 can be, for example, a positive displacement compressor. In some cases, the compressor 102 is a reciprocating compressor, such as a double-acting compressor. The container 104 is configured to house the process gas and is operably connected to a shaft extending into the compressor. A multi-stage seal system 114 (represented herein by a series of boxes along the shaft) inhibits the leakage of process gas along the shaft. In some embodiments, adjacent seals are adjacent portions of a continuous labyrinth seal. The shaft transfers mechanical energy to the process gas in the container 104 (e.g., by translating through its longitudinal axis or along its longitudinal axis) and extends into the inner cavity through the multi-stage seal system 114.

[0075] The driver 106 supplies mechanical energy to operate the gas processing system 100. In some embodiments, the driver 106 can be, for example, an internal combustion engine having a crankshaft, or an electric motor that drives the shaft of the compressor 102.

[0076] Next, referring to Figure 2 , the cylinder of the compressor 102 has a housing 118 and an end plate 120 that is bolted to the housing and through which the shaft 122 extends. In some cases, the housing 118 is in two pieces, with a cast iron piece forming the main cylinder and a steel diaphragm bolted to the end of the cylinder to house the seal system. The compressor 102 can be a linear reciprocating compressor having two inlets 108 and two outlets 110. The shaft 122 can be operably connected to the driver.

[0077] Figure 3 is an end view of the compressor section of the gas processing system. The compressor 102 includes an end plate 120, an inlet 108, and an outlet 110. The shaft 122 passes through the end plate 120.

[0078] Next, referring to Figure 4 and Figure 5 , a piston 124 is disposed at the end of the shaft 122. The housing 118 defines a cylinder chamber 126. The end of the shaft 122 opposite the piston 124 can be connected to the driver. In operation, the piston 124 and a portion of the shaft 122 can be driven to reciprocate, for example, between the positions shown in Figure 4 and Figure 5 in the cylinder chamber 126 (the shaft of the compressor 102 that carries the piston 124 can also be referred to as a "rod").

[0079] A multi-stage seal system 114 is disposed around the shaft 122. In Figure 4 and Figure 5In [the example], the progressive sealing system 114 is implemented by means of the stuffing box 130. In this example, the multi-stage sealing system 114 includes six seals 132 spaced along the shaft, and a burst pressure rod ring 134. The multi-stage sealing system 114 can be configured in the form of the stuffing box of the compressor 102. Each seal can include a plurality of sealing elements or rod rings, which are tightly stacked together on the shaft to form a series of tightly sealed interfaces with the shaft. In this case, the burst pressure rod ring 134 is a unitary seal that forms the first seal of the multi-stage sealing system. The burst pressure rod ring 134 can control leakage to regulate the backflow into the cylinder during the suction stroke and prevent damage to the rings and their detachment from the rod. The burst pressure rod ring 134 can also reduce the gas flowing out of the cylinder during the exhaust stroke. In certain embodiments, the burst pressure rod ring 134 can be modified to provide an optimal effective orifice relative to the expected flow returning to the inlet from behind the rod rings, as discussed below. The term "seal" does not imply a zero clearance at the shaft surface nor does it imply no leakage through the seal. As those skilled in the art of high-pressure gas machinery will understand, some leakage is expected through high-pressure differential seals, and such leakage may even be necessary to avoid high friction and premature seal failure. Gas expansion between the seal and the shaft surface can provide beneficial cooling to the shaft, thereby reducing seal wear.

[0080] As shown in these cross-sections, the multi-stage sealing system includes a burst pressure rod ring housing 136 and a plurality of seal housings 138, which are stacked along the shaft and disposed within the openings of the housing 118. The innermost seal housing is sealed against the cylinder housing surface by a nose gasket 140. Each seal housing 138 houses a corresponding seal 132, with the outermost seal (double-acting ring) housed within the end plate 120. Each seal 132 can be a stack of multiple elements, such as a sealing ring clamped between two other rings that support the sealing function.

[0081] The compressor cylinder inlets 108 and outlets 110 of the gas treatment system 100 each have a check valve that allows flow into (inlet) or out of (outlet) the compressor cylinder while inhibiting flow in the opposite direction. Each valve may have multiple parallel flow-through orifices. These inlets and outlets operate in pairs, each pair operating in a respective stroke direction of the shaft. For example, during the piston stroke from right to left, at different points during that stroke, the right inlet 108 and the left outlet 110 will open. Similarly, during the return stroke from left to right, at different points during that stroke, the left inlet 108 and the right outlet 110 will open, while the right inlet and the left outlet remain closed. During the return stroke from left to right, the sealed end of the cylinder will experience a pressure increase, at least up to the outlet pressure of the compressor. This high pressure will start at the pressure rupture rod ring 134 and decrease progressively along the shaft through the various stages. During the stroke from right to left, the instantaneous pressure at the pressure rupture rod ring can sometimes be lower than the compressor inlet pressure or suction pressure, and the flow direction can be reversed, towards the sealing system. Therefore, the sealing system not only needs to withstand high pressures, but must also accommodate extreme pressure waves or cycles that can fluctuate rapidly.

[0082] Next, referring to Figure 6 , the end plate 120 and its attached stacked seal housings 138 (aligned and held together by tie rods 142) are inserted into the opening in the compressor housing 118 and held in place by housing bolts 144. The seal housings are all axially connected to the end plate 120 by tie rods 142 that are screwed into the distal seal housing that houses the pressure rupture rod ring to hold the stacked seal housings together for transportation and assembly. The tie rods 142 can also provide an alignment function.

[0083] Figure 7 is a block diagram of a compressor system with a stuffing box monitoring system according to some embodiments. System 160 includes a compressor 102 and a stuffing box monitoring system 161. Compressor 102 includes a stuffing box 130. The stuffing box monitoring system 161 includes a computing device 162, a monitoring application 163, a user device 164, and a sensor 165.

[0084] The computing device 162 includes one or more processors 166, a memory 167, and a network interface controller 168. The memory 167 provides data storage of appropriate size and format. The network interface controller 168 can facilitate communication of the computing device 162 with other devices (e.g., external monitoring devices and / or sensors) via one or more wired or wireless networks.

[0085] Temperature sensors 170 and 172 and pressure sensors 174 and 176 emit signals that include sensor data describing the conditions in or associated with the stuffing box 130. The sensor data is transmitted from temperature sensors 170 and 172 and pressure sensors 174 and 176 to the computing device 162. In some embodiments, temperature sensors 170, 172, pressure sensors 174, 176, and system sensor 177 digitize the signals transmitting the sensor data before sending the signals to the computing device.

[0086] Calculations and analyses based on the sensor data can be performed at least in part by the computing device 162, such as by a process executed on the processor 166. In some embodiments, the calculations and analyses of the sensor data are performed by one or more computing systems coupled to the computing device 162 (such as a remote device connected to the computing device 162 via a network).

[0087] The computing device 162 can provide a notification to the operator regarding the condition or maintenance of the stuffing box 130. For example, the computing device 162 can provide a notification regarding seal degradation in the stuffing box 130.

[0088] In some embodiments, the computing device 162 provides the notification by means of a monitoring application 163. The monitoring application 163 is coupled to the user device 164. The user device 164 can include a display that allows the user to view temperature and pressure readings, notifications, and other information.

[0089] In some embodiments, the stuffing box monitoring system 161 obtains data regarding the life of the seal stuffing box. The information obtained by the monitoring system can be used to set a maintenance schedule for the compressor system.

[0090] Figure 8 is a cross-sectional view of a stuffing box including a temperature sensor according to some embodiments. The stuffing box 130 includes seals 132a, 132b, 132c, and 132d. The rupture pressure rod ring 134 is held in the rupture pressure rod ring housing 136. Each of the seals 132a, 132b, 132c, and 132d can include one or more sealing elements and one or more support rings. Each of the seal housings 138a, 138b, and 138c can be a cup-shaped member having a through-hole for receiving the shaft 122 and a larger opening for receiving the rod ring of its corresponding seal.

[0091] The stuffing box 130 defines a pressure space along the shaft surface bounded by the respective seals. Moving from the high-pressure end to the atmospheric pressure end of the sealing system, the high-pressure process gas leaking through the rupture pressure rod ring first reaches the intermediate pressure space between the rupture pressure rod ring 134 and the first seal 132a.

[0092] Further leakage past seal 132a reaches a pressure space, which may be at a pressure of, for example, about 500 psig. Thus, in operation, the multistage seal system defines a series of pressure spaces with a progressive decrease in pressure along the shaft, where each seal creates a pressure differential between two pressure spaces. The operating leakage rate past the seals and the pressure differential across the seals are interrelated. Generally, the higher the pressure differential across the seal, the greater the operating friction of the seal and the greater the heat generated at the seal.

[0093] Temperature sensors 170 and 172 are axially spaced from each other along stuffing box 130. Temperature sensor 170 is mounted in housing 136c. Temperature sensor 172 is mounted in plate 178. Plate 178 is held in end plate 120. In this example, 170 and 172 are located on opposite sides of seal 132c. Temperature sensor 170 is located between the second and third seals on the cylinder side of rupture disk 134.

[0094] Temperature sensors 170, 172 may provide signals to a computing device (e.g., computing device 162 as described above with respect to Figure 7 The data from temperature sensors 170 and 172 can be used to provide an indication related to the condition of one or more of seals 132a, 132b, 132c, and 132d.

[0095] In Figure 7 the example shown, temperature sensors 170 and 172 are respectively mounted in radially opening holes in housing 138c and plate 178. Each of these holes terminates near the inner surface of the housing (e.g., near the annular space between shaft 122 and housing 138c). Each of these holes is adjacent to seal 132c. Temperature sensor 172 is located on the cylinder side. In some embodiments, temperature sensors 170 and 172 are thermocouples.

[0096] Figure 9 A temperature sensor in the stuffing box is shown. Seal housing 132c of stuffing box 130 includes a groove 180 on the outer surface of the housing. Groove 180 extends axially along housing 138c into an abutment hole 182 in end plate 120. Temperature sensor wire assembly 184 is located in groove 180. Figure 10 The back side of end plate 120 is shown, where hole 182 allows temperature sensor wire assembly 184 to pass through.

[0097] Figure 11Illustrated is a pressure sensor for sensing dynamic pressure according to some embodiments. System 100 includes a lubricating oil line 202 and a pressure sensor 204. The lubricating oil line 202 includes an internal passage 206 and an external line 207. The external line 207 is coupled to the internal passage 206 via a port 208 in an end plate 120. Oil can be fed into the lubricating oil line 212 through a fitting 202. The pressure sensor 204 is fluidly coupled to the lubricating oil line 202 by means of a T-connector 210.

[0098] The sensor 204 can be used to sense the dynamic pressure in the stuffing box 130. In some embodiments, the pressure sensor 204 senses the pressure on the cylinder side of the temperature sensors in the stuffing box (e.g., the temperature sensors 170 and 172 described above with respect to Figure 8 ).

[0099] Figure 12 Illustrated is a pressure sensor for sensing dynamic pressure according to some embodiments. System 100 includes a ventilation line 220 and a pressure sensor 222. The ventilation line 220 includes an internal ventilation passage 224, a first external ventilation line 226, and a second external ventilation line 228. The first external ventilation line 226 and the second external ventilation line 228 are in fluid communication with the internal ventilation passage 224. In this example, the first external ventilation line 226 is used to allow the stuffing box to ventilate to the atmosphere. The internal ventilation passage 224 is coupled to the pressure sensor 222 via a port 230 and the second external ventilation line 228. The pressure sensor 222 can be used to sense the static pressure in the stuffing box 130. In some embodiments, the pressure sensor 222 senses the pressure on the driver side of the temperature sensors (e.g., temperature sensors 170 and 172) in the stuffing box.

[0100] Figure 13 Is a graph 260 showing temperature monitoring performed in a compressor stuffing box using temperature sensors mounted in the stuffing box housing. In this example, curve 262 can correspond to the temperature sensed by temperature sensor 170 (TC1) on the Figure 8 cylinder side of the third seal (132c) shown. Curve 264 can correspond to the temperature sensed by temperature sensor 172 (TC2) on the Figure 8 driver side of the third seal (132c) shown. Curve 266 can represent a trend line calculated from the temperature sensed by TC1. Curve 268 can represent a trend line calculated from the temperature sensed by TC2.

[0101] Initially, the compressor is in a normal operating phase. At time 270, the monitoring system can detect a start of an increase in TC1 and / or a divergence of TC1 from TC2. The increase in TC1 is reflected in an increase in temperature of curve 266.

[0102] Time 270 can be associated with one or more notifications (such as warnings) provided to the user. At stage 274, the operator can be alerted and pre-planned intervention can be carried out. Stage 274 can be associated with an assumed approximate remaining life (in this example, 30% remaining life).

[0103] Throughout stage 272, the system can continue to sense the temperature and calculate the temperature difference between the sensors. During this stage, the temperatures may continue to diverge from each other.

[0104] At time 274, the system detects that the maximum temperature difference has been reached. The maximum temperature difference is indicated by the maximum temperature difference 275 between curve 266 and curve 268.

[0105] Time 274 can be associated with one or more additional notifications (such as a maintenance alert) provided to the user. Stage 276 can be associated with an assumed approximate remaining life (in this example, 10% remaining life). Stage 276 can correspond to the ideal MRO period for the seal in the stuffing box.

[0106] Throughout stage 276, the system can continue to sense the temperature and calculate the temperature difference between the sensors. During this stage, the temperatures may converge until a crossover point is reached. Also during this stage, the temperature variations of each temperature sensor from one time to another may become increasingly variable.

[0107] At time 278, the system can detect a temperature change that exceeds a predetermined threshold. For example, the temperature change is reflected in the larger swings (visible at 277, for example) in each of curves 262 and 264.

[0108] Time 278 can be associated with one or more additional notifications (such as a warning of a high risk of failure provided to the user). Stage 280 can be associated with an assumed approximate remaining life (in this example, end of life). Stage 280 can correspond to a high ventilation leak and a risk of complete failure. During this stage, the temperatures may converge until a crossover point is reached. The temperature variations of each temperature sensor from one time to another may become increasingly variable. In some cases, although the actual temperature / measured temperature varies greatly with respect to the ambient conditions and operating conditions, the temperature measurement variations at any given time can closely track each other.

[0109] Figure 14 Process 300 for monitoring a stuffing box using temperature measurements according to some embodiments is shown. The temperature difference between two or more temperature sensors at locations within the stuffing box is calculated (302). For example, the temperature sensors can be installed in the stuffing box as described above with respect to Figure 8 the stuffing box described.

[0110] Based on the calculation, the system determines whether the temperature difference diverges (304). If the temperature difference does not diverge, the system continues to measure the temperature (306). If the temperature difference diverges (and / or if the TC1 temperature starts to rise), the system provides a first seal life stage alert (308). In one example, the divergence of the temperature difference corresponds to Figure 13 time 270 on.

[0111] As the compressor system continues to operate (e.g., Figure 13 in stage 272), the system continues to calculate the temperature difference. Based on the calculation, the system determines whether the maximum temperature difference has been reached (310). If the maximum value has not been reached, the system continues to measure the temperature (312). If the maximum temperature difference has been reached, the system provides a second seal life stage alert (314). In one example, the maximum temperature difference corresponds to Figure 13 time 274 on. The second stage indicator can trigger an operation for maintenance personnel to replace the stuffing box seal.

[0112] As the compressor system continues to operate (e.g., Figure 13 in stage 276), the system continues to calculate the temperature difference. Based on the calculation result, the system determines whether the temperature change is higher than a predetermined threshold. If the threshold has not been reached, the system continues to measure the temperature (318). If the threshold has been reached, the system provides a third seal life stage alert (320). In one example, the maximum temperature difference corresponds to Figure 13 time 278 on. The third stage indicator can be associated with the end of life of the seal.

[0113] Figure 15 Process 400 for monitoring a stuffing box using temperature measurement and pressure measurement according to some embodiments is shown. In one embodiment, temperature sensors and pressure sensors can be installed in the stuffing box as described above with respect to Figure 8 , Figure 9 and Figure 10 described stuffing box.

[0114] Dynamic pressure is measured (402) and calculated in the stuffing box (e.g., cylinder side, lubricating oil line). Based on the calculation result, the system determines whether the dynamic pressure exceeds a predetermined threshold (404). If the dynamic pressure does not exceed the threshold, the system continues to measure the dynamic pressure (406). If the dynamic pressure exceeds the threshold, the system provides an early life deterioration indicator (408).

[0115] As the compressor system continues to operate, the system calculates the temperature difference between two or more temperature sensors. Based on the calculation, the system determines whether a mid-life trigger point (410) has been reached. If the mid-life trigger point has not been reached, the system continues to measure the temperature (412). If the mid-life trigger point has been reached, the system provides a mid-term degradation indicator (414). This mid-term indicator can trigger an operation for maintenance personnel to replace the stuffing box seal.

[0116] As the compressor system continues to operate, the system measures the static pressure in the stuffing box. Based on the calculation, the system determines whether a static pressure threshold (416) has been reached. If the static pressure threshold has not been reached, the system continues to measure the pressure (418). If the static pressure threshold has been reached, the system provides a late-stage degradation indicator (420). This late-stage indicator can be associated with the end of life of the seal. In various embodiments, this late-stage indicator is based on a derived leakage flow rate, a pressure measurement, or a combination of both.

[0117] In some embodiments, the early degradation indicator is obtained from internal instrument data (such as dynamic pressure measured using a pressure sensor fluidly connected to the lubricating oil line). In some embodiments, the late-stage degradation indicator is obtained from internal instrument data (such as static pressure measured using a pressure sensor fluidly connected to the ventilation line). The late-stage degradation indicator can also be determined based on a derived leakage flow rate.

[0118] In some of the above processes, the system determines a seal condition indicator based on temperature data generated by temperature sensors connected to the stuffing box. In some embodiments, the seal condition indicator is determined based on data from a pressure sensor connected to the stuffing box. In some embodiments, the seal condition indicator is determined based on a combination of data from a temperature sensor and a pressure sensor connected to the stuffing box.

[0119] In some of the above processes, the system determines a seal degradation indicator.

[0120] In the above regarding Figure 8 In the described embodiments, a pair of sensors are located on both sides of the third seal from the stuffing box breaker. The temperature sensors are axially spaced apart from each other, with each sensor located on one side of the seal. In other embodiments, the monitoring system includes temperature sensors located at other positions in the housing. In certain embodiments, the stuffing box monitoring system includes only one temperature sensor or more than two temperature sensors.

[0121] These temperature sensors can also be circumferentially spaced apart from each other. For example, the first temperature sensor can be located between the first seal and the second seal at the bottom of the stuffing box, while the second temperature sensor is located between the second seal and the third seal at the top of the stuffing box.

[0122] Figure 16 A stuffing box is shown having temperature sensors between each seal in the seals of the stuffing box, according to some embodiments. The stuffing box 500 includes temperature sensors 502a, 502b, 502c, 502d, and 502e. The temperature sensors 502a, 502b, 502c, 502d, and 502e are axially spaced from each other along the length of the stuffing box 500, with one temperature sensor between each pair of adjacent seals. The temperature sensor 502f is circumferentially spaced from the temperature sensor 502d. The temperature sensor 502g is circumferentially spaced from the temperature sensor 502e.

[0123] The above system has been described with respect to a reciprocating compressor, where shaft power acts on a process gas to produce a high-pressure gas stream that can do work elsewhere in the system. The progressive seal monitoring system as described herein can also be implemented in other processing systems, such as reciprocating pumps. Additionally, a monitoring system such as that described herein can be applied to some engines. For example, the progressive seal monitoring system can be included in a linear reciprocating gas engine that uses a high-pressure gas stream to drive a shaft back and forth in a reciprocating manner.

[0124] Monitoring systems, instrumentation, and methods (such as the stuffing box monitoring system 161 described above with respect to Figure 7 can be implemented in electronic circuitry, computer hardware, firmware, software, or a combination of these elements. The apparatus can include input and output devices, a computer processor, and a computer program product implemented in a machine-readable storage device for execution by a programmable processor. The techniques can be performed by a programmable processor executing an instruction program to perform the desired functions by operating on input data and generating appropriate outputs. The techniques can be implemented in one or more computer programs executable on a programmable system including at least one programmable processor, at least one input device, and at least one output device, the at least one programmable processor being coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system. For example, suitable processors include general and special purpose microprocessors. In general, the processor will receive instructions and data from read-only memory and / or random access memory. The storage device can include all forms of non-volatile memory, including, for example, semiconductor memory devices such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and compact disc read-only memory (CD-ROM). Any of the foregoing can be supplemented by, or incorporated in, specially designed application specific integrated circuits (ASICs).

[0125] In one aspect of the present disclosure, a stuffing box monitoring system includes one or more temperature sensors, one or more pressure sensors, and a computing device. One or more of these temperature sensors are mounted in a housing and configured to sense the temperature at at least one location in the stuffing box. One or more of these pressure sensors are fluidly coupled to one or more spaces in the stuffing box and configured to sense the pressure at at least one location in the stuffing box. The computing device is communicatively coupled to at least one of the one or more temperature sensors and at least one of the one or more pressure sensors. The computing device is configured to: receive signals from the at least one temperature sensor and the at least one pressure sensor; and calculate a degradation index for at least one of the seals of the stuffing box from the signals from at least one of the temperature sensors and at least one of the pressure sensors.

[0126] In some embodiments, the one or more temperature sensors include two or more temperature sensors. The computing device is configured to calculate a temperature difference at two or more times based on signals from the temperature sensors.

[0127] In some embodiments, at least one of the pressure sensors is coupled to a ventilation line of the stuffing box.

[0128] In some embodiments, at least one of the pressure sensors is coupled to a lubricating oil line of the stuffing box.

[0129] In some embodiments, a stuffing box assembly includes a plurality of seals, a housing configured to accommodate at least two of the seals, an end plate coupled to the housing, one or more temperature sensors, and one or more pressure sensors. The one or more temperature sensors are coupled to the housing of the stuffing box and configured to sense the temperature in the stuffing box. The one or more pressure sensors are coupled to the housing and configured to sense the pressure in one or more spaces in the stuffing box.

[0130] In some embodiments, a method of detecting seal wear in a progressive seal system includes: receiving signals from one or more temperature sensors coupled to the housing of the progressive seal system; calculating temperatures associated with the temperature sensors at two or more times from the signals; and determining a degradation index for at least one of the seals of the progressive seal system at least in part from the temperatures calculated at the two or more times.

[0131] In some embodiments, the method further includes: sensing the pressure in one or more spaces of the progressive sealing system and determining, at least in part from the sensor pressures at two or more times, a deterioration indicator for at least one of the seals of the progressive sealing system.

[0132] As used herein, in the context of a sealing system, "deterioration" includes any change in one or more seals that reduces the effectiveness of the sealing system or that brings the seal closer to the end of its useful life.

[0133] As used herein, "indicator" includes a numerical value, number, code, symbol, description, or other novel item that indicates or describes the condition, state, or level of a component, system, or device. For example, a seal condition indicator may describe the life stage of a sealing system (e.g., normal operation, recommended replacement, end-of-life critical, impending failure) or the percentage of remaining life of a sealing system.

[0134] As used herein, "predictor" includes an indicator that predicts or estimates an outcome or effect associated with a system, component, or device.

[0135] As used herein, "chamber" includes a space that is at least partially enclosed.

[0136] As used herein, "driver" includes a device that supplies mechanical energy to operate a system.

[0137] As used herein, "housing" may completely or only partially enclose the components it houses.

[0138] As used herein, "progressive" means that the sealing system has multiple sealing members between a high-pressure point and a low-pressure point. In many cases, such a system progressively reduces the pressure at each level between the high-pressure point and the low-pressure point.

[0139] Specific embodiments of the subject matter have been described. It will be apparent to those skilled in the art that other embodiments, variations, and permutations of the described embodiments are within the scope of the following claims. Although the operations are described in a particular order in the figures or claims, this should not be construed as requiring that the operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed to obtain the desired result.

[0140] Accordingly, the previously described exemplary embodiments do not limit or restrict the present disclosure. Other changes, substitutions, or alterations may be made without departing from the spirit and scope of the present disclosure.

Claims

1. A method for monitoring the deterioration of a seal in a stuffing box, comprising: receiving a signal from a first temperature sensor mounted at a first location in the housing of the stuffing box; receiving a signal from a second temperature sensor mounted at a second location in the housing of the stuffing box; calculating a temperature difference between the first temperature sensor and the second temperature sensor at two or more times from the signals; and determining, at least in part from the temperature difference at the two or more times, a deterioration index for at least one seal in the seal of the stuffing box.

2. The method according to claim 1, wherein: the stuffing box defines a cylinder side and a driver side, the first location is on the cylinder side of one of the seals in the stuffing box, and the second location is on the driver side of one of the seals in the stuffing box.

3. The method according to claim 1 or 2, wherein the first temperature sensor and the second temperature sensor are axially spaced apart from each other along the length of the stuffing box.

4. The method according to any one of the preceding claims, wherein at least one of the temperature sensors is embedded in an opening in the housing of the stuffing box.

5. The method according to any one of the preceding claims, wherein the deterioration index is at least partially based on an increase in the temperature difference over time between the first temperature sensor and the second temperature sensor.

6. The method according to any one of the preceding claims, wherein the deterioration index is at least partially based on one or more changes in the temperature difference over time between the first temperature sensor and the second temperature sensor.

7. The method according to any one of the preceding claims, wherein the deterioration index is at least partially based on the maximum temperature difference between the first temperature sensor and the second temperature sensor.

8. The method according to any one of the preceding claims, wherein the deterioration index is at least partially based on an increase in the temperature difference over time in the first temperature sensor.

9. The method according to any one of the preceding claims, further comprising: sensing the pressure in the stuffing box; and determining, from at least one sensed pressure, a deterioration index for at least one seal in the seal of the stuffing box.

10. The method according to any one of the preceding claims, wherein the pressure is sensed on the cylinder side of at least one of the temperature sensors.

11. The method according to any one of the preceding claims, wherein the pressure is sensed on the driver side of at least one of the temperature sensors.

12. The method according to any one of the preceding claims, wherein the pressure is sensed in the lubricating oil line of the stuffing box.

13. The method according to any one of the preceding claims, wherein the pressure is sensed in the ventilation line of the stuffing box.

14. The method according to any one of the preceding claims, further comprising: providing a notification to the user based on the deterioration index.

15. A monitoring system for a stuffing box, the stuffing box having two or more seals and defining a cylinder side and a driver side, the monitoring system comprising: a first temperature sensor coupled to an outer casing of the stuffing box and configured to sense a temperature of the cylinder side of one of the seals; a second temperature sensor coupled to the outer casing and configured to sense a temperature of the driver side of one of the seals; and a computing device communicatively coupled to the first temperature sensor and the second temperature sensor, the computing device being configured to: receive signals from the first temperature sensor and the second temperature sensor; calculate a temperature difference between the first temperature sensor and the second temperature sensor at two or more times from the signals; and determine a degradation index of at least one of the seals of the stuffing box at least in part from the temperature difference at the two or more times.

16. The monitoring system according to claim 15, wherein the two or more seals include a pressure breaker; a first seal axially disposed on the driver side of the pressure breaker; a second seal axially disposed on the driver side of the first seal; and a third seal axially disposed on the driver side of the second seal, wherein one of the seals is the third seal, and wherein the first temperature sensor is axially disposed between the second seal and the third seal.

17. The monitoring system according to claim 16, wherein the second temperature sensor is axially disposed between the third seal and an end plate seal.

18. The monitoring system according to any one of claims 15 to 17, wherein: the two or more seals include a second seal axially disposed on the cylinder side of one of the seals, the system further includes a third temperature sensor axially disposed on the cylinder side of the second seal, the computing device is communicatively coupled to the third temperature sensor, and the computing device is configured to calculate a temperature difference between the third temperature sensor and at least one of the first temperature sensor and the second temperature sensor.

19. The monitoring system according to any one of claims 15 to 18, further comprising: a pressure sensor configured to sense a pressure of the cylinder side of one of the seals.

20. The monitoring system according to any one of claims 15 to 19, further comprising: a pressure sensor coupled to a lubricating oil line of the stuffing box.

21. The monitoring system according to any one of claims 15 to 20, further comprising: a pressure sensor configured to sense a pressure of the driver side of one of the seals.

22. The monitoring system according to any one of claims 15 to 21, further comprising: a pressure sensor coupled to a ventilation line of the stuffing box.

23. The monitoring system according to any one of claims 15 to 22, wherein the stuffing box monitoring system is communicatively coupled to a cylinder-side pressure sensor, wherein, the stuffing box monitoring system is configured to determine a degradation index from information received from the cylinder-side pressure sensor.

24. The monitoring system according to any one of claims 15 to 23, wherein the stuffing box monitoring system is communicatively connected to a driver-side pressure sensor, wherein, the stuffing box monitoring system is configured to determine a degradation index from information received from the driver-side pressure sensor.

25. The monitoring system according to any one of claims 16 to 25, wherein the stuffing box monitoring system is configured to provide a notification of the degradation index to a user.

26. The monitoring system according to any one of claims 15 to 25, wherein the stuffing box monitoring system is configured to provide a notification to the user regarding degradation of one or more of the seals.

27. The monitoring system according to any one of claims 15 to 26, wherein the stuffing box monitoring system is configured to provide a notification to the user regarding a maintenance event time setting for one or more of the seals of the stuffing box, at least in part based on the degradation index.

28. The monitoring system according to any one of claims 15 to 27, wherein the stuffing box monitoring system is configured to provide a warning to the user regarding seal failure in the stuffing box, at least in part based on the degradation index.

29. The monitoring system according to any one of claims 15 to 28, wherein the stuffing box monitoring system is configured to provide a predictor for one or more of the seals of the stuffing box to the user, at least in part based on the degradation index.

30. A stuffing box assembly, comprising: a plurality of seals; a housing configured to accommodate at least two of the seals; an end plate coupled to the housing; a first temperature sensor coupled to the housing of the stuffing box and configured to sense the temperature of the cylinder side of one of the seals; and a second temperature sensor coupled to the housing and configured to sense the temperature of the driver side of one of the seals.

31. A reciprocating compressor system, comprising: a compression cylinder defining a compression chamber; a driver; a rod coupled between the driver and the compression cylinder, wherein the driver is operable to reciprocate the rod such that gas is compressed in the compression chamber; a stuffing box through which the rod passes between the compression cylinder and the driver, the stuffing box defining a cylinder side and a driver side, and the stuffing box comprising: a plurality of seals through which the rod passes; a housing configured to accommodate at least two of the seals; and an end plate coupled to the housing; and a stuffing box monitoring system, the stuffing box monitoring system comprising: A first temperature sensor coupled to the housing of the stuffing box and configured to sense the temperature on the cylinder side of one of the seals; A second temperature sensor coupled to the housing and configured to sense the temperature on the actuator side of one of the seals; and A computing device communicatively coupled to the first temperature sensor and the second temperature sensor, the computing device being configured to: Receive signals from the first temperature sensor and the second temperature sensor; Calculate a temperature difference between the first temperature sensor and the second temperature sensor at two or more times from the signals; and Determine a degradation index of at least one of the seals of the stuffing box at least in part from the temperature difference at the two or more times.

32. A method for monitoring degradation of seals of a stuffing box, comprising: Receiving signals from one or more temperature sensors mounted in the housing of the stuffing box; Receiving signals from one or more pressure sensors coupled to the housing of the stuffing box; Calculating a temperature at two or more times and a pressure at two or more times from the signals; and Determining one or more degradation indices for at least one of the seals of the stuffing box from at least one of the temperatures and at least one of the pressures.

33. The method according to claim 32, wherein at least one of the degradation indices is determined from two or more temperatures.

34. The method according to claim 32 or claim 33, wherein at least one of the degradation indices is determined from two or more pressures.

35. The method according to any one of claims 32 to 34, wherein at least one of the degradation indices is an early degradation index.

36. The method according to any one of claims 32 to 34, wherein at least one of the degradation indices is a mid-term degradation index.

37. The method according to any one of claims 32 to 34, wherein at least one of the degradation indices is a late degradation index.

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