Method and apparatus for monitoring the condition of the piston rod sealing system of a piston compressor

Abstract

The present invention relates to a method for monitoring the condition of a piston rod sealing system (12) of a reciprocating compressor, wherein the piston rod sealing system (12) comprises at least two grooved annexes (12a) arranged sequentially along a longitudinal direction (L) and each having at least one sealing element (12b) disposed therein, wherein a piston rod (16) extending through the sealing element (12b) and the grooved annexes (12a) is movable longitudinally and sealed by the sealing element (12b), wherein the piston rod sealing system (12) has an inlet side (E) and an outlet side (A) with a pressure difference between them, the pressure difference having a static pressure component (D). S ) and dynamic pressure component (D D The leaking gas is located in the grooved annulus (12a), and the dynamic pressure component of the leaking gas is at least measured in the piston rod sealing system (12) as a percentage (D). D ), by the dynamic pressure component (D) D The state change of at least one of these sealing elements (12b) over time is determined.

Description

Technical Field

[0001] This invention relates to a method and apparatus for monitoring the condition of the piston rod sealing system of a reciprocating compressor. Background Technology

[0002] Document DE202014102844U1 discloses a piston rod sealing device for a reciprocating compressor. This piston rod sealing system is used, for example, to seal the compression chamber of the reciprocating compressor relative to atmospheric pressure. The reciprocating piston rod is connected to a driver on one side and to the piston of the reciprocating compressor on the other. The piston rod passes through the piston rod sealing system, thereby reducing the pressure between the compression chamber and the environment within the piston rod sealing system. To achieve high sealing performance or low leakage in the piston rod sealing system, this pressure sealing device preferably includes a friction sealing element whose sealing surface contacts the piston rod and thus withstands wear. A disadvantage of this piston rod sealing system is that leakage increases over operating time. The operator of this reciprocating compressor requires reliable operation over a long operating period, such as at least 8000 hours, without unacceptably large amounts of leakage in the piston rod sealing system, or without high wear, significant damage, or even large elastic-plastic deformation of the sealing element. Summary of the Invention

[0003] The object of this invention is to provide a method and apparatus that allow for more reliable operation of a reciprocating compressor.

[0004] This objective is achieved, in particular, by a method for monitoring the condition of a piston rod sealing system of a reciprocating compressor comprising a compression chamber, wherein gas is compressed from a suction pressure to a discharge pressure in the compression chamber of the reciprocating compressor, wherein the piston rod sealing system comprises at least two grooved annexes arranged longitudinally in succession and each having at least one sealing element disposed therein, wherein a piston rod extending through the sealing element and the grooved annexes moves longitudinally back and forth and is sealed by the sealing element, wherein the piston rod sealing system has an inlet side and an outlet side, the pressure of the compression chamber is applied to the inlet side, a pressure difference exists between the inlet side and the outlet side, the pressure difference having a static pressure component and a dynamic pressure component, wherein the dynamic pressure component varies with respect to crankshaft angle, wherein leaking gas is located in the grooved annexes, wherein at least the dynamic pressure component of the leaking gas is measured in the piston rod sealing system, and wherein the change in the state of at least one of the sealing elements is determined by the change in the dynamic pressure component with respect to time.

[0005] This objective is also achieved, in particular, by a method for monitoring the condition of a piston rod sealing system of a reciprocating compressor, wherein the piston rod sealing system comprises at least two grooved annexes arranged longitudinally in succession, each grooved annexes having at least one sealing element disposed therein, wherein a piston rod extending through the sealing element and the grooved annexes moves longitudinally back and forth and is sealed by the sealing element, wherein the piston rod sealing system has an inlet side and an outlet side, wherein a pressure difference exists between the inlet side and the outlet side, wherein the pressure difference has a static pressure component and a dynamic pressure component, and wherein leaking gas is located in the grooved annexes, wherein at least the dynamic pressure component of the leaking gas is measured in the piston rod sealing system, and wherein the change in the state of at least one of the sealing elements is determined by the change in the dynamic pressure component with respect to time.

[0006] This objective is also achieved, in particular, by a monitoring system for monitoring the condition of a piston rod sealing system of a reciprocating compressor, wherein the piston compressor includes a piston and a compression chamber, wherein gas can be compressed from a suction pressure to a discharge pressure by means of the piston in the compression chamber, wherein the piston rod sealing system includes at least two grooved annexes arranged longitudinally in succession, each grooved annexes having at least one sealing element disposed therein, wherein a piston rod capable of longitudinally moving back and forth extends through the sealing element and the grooved annexes, wherein the piston rod is connected to the piston, wherein the piston rod sealing system has an inlet side and an outlet side, wherein pressure from the compression chamber is applied to the inlet side, wherein at least one pressure sensor is provided for measuring at least a dynamic pressure component of leaked gas within the grooved annexes, and wherein a storage and evaluation unit stores a plurality of measured dynamic pressure components, and wherein the evaluation unit monitors the change of dynamic pressure components with respect to time and infers the state change of at least one of the sealing elements therefrom.

[0007] Furthermore, this objective is achieved, in particular, by a monitoring system for monitoring the condition of a piston rod sealing system of a reciprocating compressor, wherein the piston rod sealing system comprises at least two grooved annexes arranged longitudinally in succession, each grooved annexes having at least one sealing element disposed therein, wherein a piston rod capable of moving back and forth longitudinally extends through the sealing element and the grooved annexes, wherein the piston rod is connected to the piston, wherein the piston rod sealing system has an inlet side and an outlet side, and wherein a pressure sensor is arranged in at least one of the grooved annexes to measure at least the dynamic pressure component of leaked gas in the grooved annexes, wherein a storage and evaluation unit stores a plurality of measured dynamic pressure components, and wherein an evaluation unit monitors the change of dynamic pressure components over time and derives from the state change of at least one sealing element.

[0008] The method for monitoring the condition of a piston rod sealing system in a reciprocating compressor according to the invention has the advantage of being able to monitor the condition of the piston rod sealing system or the wear of the sealing elements in the piston rod sealing system in a simple, low-cost, and highly accurate manner. The condition of the sealing elements can be monitored, for example, several times a minute or several times a day, or at specified intervals, such as several minutes, and particularly preferably continuously. This means that the piston rod sealing system is continuously monitored for approximately one year, for example, by a specified uninterrupted operating time of at least 8000 hours. The condition monitoring system according to the invention detects the sealing effect of at least one individual sealing element from measurements, and preferably the sealing effect of multiple or all sealing elements of the piston rod sealing system, thereby enabling the determination of the condition of the corresponding sealing element involved in its sealing effect, and preferably the individual condition of each sealing element. Furthermore, the condition monitoring according to the invention has the advantage that partial or complete failure of one or more sealing elements can preferably be predicted based on the corresponding determined condition and preferably detected with a sufficiently long lead time, so that the monitoring system can advantageously issue warnings or condition information before the sealing element completely fails, thus providing sufficient time for planning the maintenance of the piston rod sealing system. The operational reliability advantageously obtained by the condition monitoring system according to the invention also allows the piston rod sealing system to operate without maintenance for more than 8,000 hours if desired. Furthermore, multiple failures in the piston rod sealing system, such as cracks or elastic-plastic deformation of the sealing elements, can be clearly detected, thereby enabling maintenance planning and, for example, allowing, the remaining feasible and reliable operating time of the piston rod sealing system before maintenance to be calculated, if absolutely necessary.

[0009] In the method according to the invention, the condition or sealing effect of the sealing element of the piston rod sealing system arranged in a reciprocating compressor is detected. The reciprocating compressor includes a reciprocating piston and a compression chamber, the piston acting on the compression chamber causing gas to be compressed from a suction pressure to a discharge pressure within the compression chamber. The piston rod sealing system includes at least two grooved annexes arranged longitudinally in succession, each grooved annexes having at least one sealing element disposed therein, wherein a piston rod extending through the sealing element and the grooved annexes and connected to the piston moves longitudinally back and forth and is sealed by the sealing element. The piston rod sealing system has an inlet side and an outlet side, the pressure of the compression chamber is applied to the inlet side, and a pressure difference exists between the inlet side and the outlet side. Preferably, an external pressure or ambient pressure of 1 bar is applied to the outlet side. The existing pressure difference has a static pressure component (preferably suction pressure) and a dynamic pressure component, the dynamic pressure component varying with the position of the piston or the crankshaft angle of the crankshaft driving the piston or piston rod. Leaking gas exists in the grooved annexes and, if necessary, in the space between two grooved annexes, the pressure of which can be measured or determined by a corresponding sensor. Because the static pressure is constant or changes very slowly, it is preferable that the same static pressure exists inside all the grooved rings, as the static pressure is preferably released at the last sealing element facing the outlet side. Since all the grooved rings preferably have substantially the same static pressure, when using sealing elements designed as friction sealing rings, no indication of the condition of the corresponding sealing element can be derived from the static pressure. According to the invention, the pressure applied between the inlet and outlet sides of the piston rod sealing system is divided into static pressure and dynamic pressure. The condition of the sealing element can be inferred from the dynamic pressure. The sealing elements arranged in the piston rod sealing system and designed as friction sealing rings, with the sealing element facing the inlet side experiencing wear first, is essentially the entire dynamic pressure applied to one of the sealing elements. Due to the increasing wear of the sealing elements from the inlet side towards the outlet side, the dynamic pressure can be measured further and further away from the inlet side towards the outlet side within the piston rod sealing system; in other words, the dynamic pressure penetrates deeper and deeper into the piston rod sealing system. Compared to static pressure, the dynamic pressure provides useful information about the condition of the corresponding sealing elements arranged within the piston rod sealing system. Particularly preferably, the dynamic pressure of the piston rod sealing system is used, measured, and / or calculated to infer the state or state change of at least one sealing element, and preferably multiple sealing elements, by observing the change of the value over time.

[0010] Leaking gas in the piston rod sealing system causes static and / or dynamic pressure drops in the various sealing elements of the piston rod sealing system. This leaking gas has static pressure and dynamic pressure components. According to the invention, by monitoring the change of the dynamic pressure component over time, conclusions can be drawn about a change in the state of at least one sealing element, which is typically caused by changes in sealing performance, such as wear, damage, or elastic-plastic deformation of the sealing element. Attached Figure Description

[0011] The accompanying drawings are for illustrative purposes and show:

[0012] Figure 1 A schematic simplified longitudinal section of a reciprocating compressor;

[0013] Figure 2 Longitudinal section of the piston rod sealing system;

[0014] Figure 3 The diagram shows the pressure variation at the inlet of the piston rod sealing system with respect to the crankshaft angle.

[0015] Figure 4 The suction pressure and dynamic pressure in the grooved rings arranged in succession with new sealing rings;

[0016] Figure 5 The suction pressure and dynamic pressure in the grooved rings with sealing rings arranged one after the other cause some sealing rings to wear.

[0017] Figure 6 Another longitudinal section of the piston rod sealing system;

[0018] Figure 7 Another example of monitoring the condition of a piston rod sealing system;

[0019] Figure 8 The dynamic pressure curve varies with crankshaft angle;

[0020] Figure 9 Another example of monitoring the condition of a piston rod sealing system;

[0021] Figure 10 A schematic simplified longitudinal section of another example of a cylinder with a piston and piston rod sealing system.

[0022] In principle, the same reference numerals should be assigned to the same parts in the accompanying drawings. Detailed Implementation

[0023] Figure 1A reciprocating compressor 1 for compressing gas is shown, comprising a cylinder 2 extending in a horizontal direction, and a piston 3 capable of moving within the cylinder 2 in a longitudinal direction L or along the extension direction of the cylinder 2. The reciprocating compressor 1 also includes a piston rod 16, a piston rod sealing system 12, a crosshead 17 with a linear guide 18, a push rod 19, a crank 20, and a drive shaft 21. In the illustrated embodiment, the piston 3 is a double-acting design and includes a sealing ring 4 and a guide ring 5, which divides the interior of the cylinder 2 into a first internal space 6 and a second internal space 7, or a first compression chamber 6 and a second compression chamber 7, respectively, with inlet valves 8 and 9 and outlet valves 10 and 11. The cylinder 2 is connected to a housing 15 via an intermediate section 14, within which the piston rod sealing system 12 is also arranged. At least one sensor 26 is arranged in the piston rod sealing system 12 to detect pressure within the piston rod sealing system 12 at at least one location. The monitoring system 22 detects, for example, the displacement s(t) of the piston 3 in the cylinder 7 over time t, the displacement s(t) of the piston rod 16 over time t, and the rotation angle α(t) of the drive shaft 21 over time t via signal line 24 and other sensors not shown in detail. The monitoring device 22 also detects the value of at least one sensor 26 used to measure the pressure in the piston rod sealing system 12 via signal line 25.

[0024] Figure 2 A longitudinal section of an embodiment of a piston rod sealing system 12 is shown, which includes six grooved rings 12a, each grooved ring 12 defining an inner cavity, a so-called groove K, facing outward. The piston rod sealing system 12 has an inlet side E and an opposing outlet side A, the inlet side being as follows: Figure 1As can be seen, the compression chamber 6 facing inwards or towards cylinder 2 typically experiences atmospheric pressure at the outlet side A. The inlet side E is preferably located close to the compression chamber 6 and preferably forms the boundary of the compression chamber 6, thereby fluidly connecting the compression chamber 6 and the piston rod sealing system 12 via the inlet side E. Starting from the inlet side E, the illustrated piston rod sealing system 12 includes six grooved rings 12a arranged longitudinally in succession. The first four grooved rings 12a form a first groove K1, a second groove K2, a third groove K3, and a fourth groove K4. Each groove contains a sealing element 12b, and each sealing element 12b includes a sealing ring 12e, a support ring 12c, and a cover ring 12d. The sealing elements 12b can also have different design configurations. A pressure sensor 26 is arranged between the third and fourth grooves K3 and K4 to measure the pressure of leaked gas in the intermediate space between the third groove K3 and the fourth groove K4, corresponding to the pressure in the inner chamber of the fourth groove K4. A second pressure sensor 26a is also arranged in the third groove K3 to measure the pressure of the leaking gas in this groove K3. Pressure sensors 26 and 26a are connected to the monitoring system 22 via electrical wires 25 and 25a. Following the fourth grooved ring 12a with groove K4, the fifth and sixth grooved rings 12a are arranged on the left side, with two damping rings 12j arranged in groove K of the fifth and sixth grooved rings, respectively. The fifth grooved ring 12a also includes a gas leakage channel 12g, which is located at the outlet of the fifth grooved ring leading to the atmospheric pressure environment, so that this outlet can be referred to as the outlet side A. The piston rod 16 extends through the damping ring 12j, the sealing element 12b, and the grooved ring 12a. The piston rod sealing system 12 also includes a portion of the housing 12h. The piston rod sealing system 12 is arranged in the intermediate member 14 and connected to the drive housing 15. The sealing element 12b is designed as a wear-resistant friction ring, and its sealing surface abuts against the surface of the piston rod 16 to achieve very low leakage. To maintain the high sealing performance of sealing elements 12b for as long as possible during operation, the sealing elements 12b are designed so that their sealing surfaces maintain as much full contact as possible with the piston rod even as wear gradually increases, thereby minimizing the area of ​​air leakage channels. Sealing elements 12b thus provide wear compensation. According to... Figure 2 The piston rod sealing system 12 includes four hermetically sealed elements 12b arranged in series, each element 12b being disposed within a separate grooved ring 12a. Another embodiment is consistent with... Figure 2 The embodiment differs in that it does not have a gas leakage channel 12g, whereby the sealing element 12b is arranged in place of the damping ring 12j within the last two grooved rings on the left side, so that the outlet side A is located on the left side in the region of the piston rod 16, as... Figure 2 As shown.

[0025] Figure 3The following example illustrates the possible variation curve of the pressure in the first compression chamber 6 as a function of crankshaft angle; this pressure is also referred to as cylinder pressure D. K Or it can be referred to as the pressure difference D between the inlet side E and the outlet side A. K During the operation of the reciprocating piston, this pressure difference D exists on the inlet side of the piston rod sealing system 12 or in the first groove K1 of the first grooved ring 12a. K The change curve is caused by the fluid compressed by piston 3 inside cylinder 2. The fluid to be transferred is pumped at a suction pressure D. A The air is drawn in by piston 3 and compressed in cylinder 2 to exhaust pressure D. E During this suction and subsequent compression processes, the pressure at the inlet side E of the piston rod sealing system 12, as a function of the crankshaft angle α, is respectively expressed as the cylinder pressure D. K Or pressure difference D K The curves showing the changes in pressure. The outlet side A and the gas leakage channel 12g, for example, represent the pressure of the subsequent compression stage or, in this example, the ambient pressure D at 0 bar. U The pressure present in the piston rod sealing system 12 can be divided into a static pressure component D. S and dynamic pressure component D D ,like Figure 3 As shown. Static pressure component D S Preferred pressure equal to suction pressure D A Dynamic pressure component D D The pressure component D varies with time or crankshaft angle, and the dynamic pressure component D at the inlet side E. D These correspond to the cylinder pressure D applied to the piston rod sealing system 12. K and suction pressure D A or static pressure D S The difference between them. Static pressure component D S The suction pressure D during the compression phase is taken into account. A and the pressure D applied to the outlet side A U The difference between them, where in this example, pressure D U Corresponding to atmospheric pressure, the static pressure component corresponds to the suction pressure D. A .

[0026] Figure 4 The monitoring data is shown. Figure 2 An example of the condition of the piston rod sealing system 12. A first grooved ring 12a forms groove K1, a second grooved ring 12a forms groove K2, a third grooved ring 12a forms groove K3, and a fourth grooved ring 12a forms groove K4. Figure 4In the example shown, each of the four slots is equipped with a pressure sensor 26, 26a, which allows for the measurement of the pressure in the corresponding slot. The pressure sensors 26, 26a can be arranged in various ways to measure the pressure in the corresponding slot, for example, they can be located inside the slot-shaped annulus 12a or outside the slot-shaped annulus 12a, forming a fluid-conducting connection with the corresponding slot. Figure 4 For each of the four slots K1, K2, K3, and K4, the static pressure D present in the corresponding slot is shown. A and the maximum pressure D that occurs Max The maximum pressure D Max Composed of static pressure component Ds and dynamic pressure component D D Composition. In the example shown, the static pressure component Ds corresponds to the suction pressure D. A Pressure D K Or pressure difference D K The variation curves over time depend, in principle, on the crankshaft angle or the piston position. The maximum pressure D corresponding to the grooves K1, K2, K3, and K4 is... Max Or static pressure component D S and dynamic pressure component D D The sum, on the other hand, depends on the sealing effect or the condition or wear of the corresponding sealing element 12b. When it is a new part, the piston rod sealing system 12 only has a high maximum pressure D in the groove K1. Max Because the entire dynamic pressure component D D The first friction seal element 12b is located in the groove K1 for sealing. As operating time increases, the seal element 12b undergoes wear, such as… Figure 5 The figure shows the maximum pressure D. Max It is possible to enter other internal grooves K2, K3, K4 of the grooved annulus 12a from the inlet side E, or to propagate from the inlet side E into these other grooves K2, K3, K4, thereby, for example, measuring in a single groove K1 to K4, the following: Figure 5 The maximum pressure D shown in the figure Max The condition of the piston rod sealing system 12 can now be monitored using the following methods, for example:

[0027] A) Measure the pressure of the leaking gas in the single tank furthest from the inlet side E (i.e., in tank K4). This is provided that the pressure measured there substantially corresponds to the suction pressure D. A Therefore, it can be determined that at least one of the sealing elements 12b arranged upstream towards the inlet side E in grooves K1, K2, and K3 satisfies its sealing effect, and thus no increased pressure will be measured in groove K4. From this, the dynamic pressure component D can be determined. D Preferably, it is completely sealed by one of the sealing elements 12a located in grooves K2, K3, and K4. According to... Figure 5In one embodiment, the maximum increased pressure D was measured in tank K4. Max From this, it can be seen that all the sealing elements 12b arranged in the grooves K1, K2 and K3 can no longer achieve a complete sealing effect due to their wear.

[0028] B) Measure the pressure of the leaking gas in each of tanks K1, K2, K3, and K4, and then divide by the maximum pressure amplitude D in each tank. Max In addition to the numerical values, it is also possible to measure the dynamic pressure components D of individual slots K1 to K4. D Compare the pressures of different tanks, or distribute the pressure across them. Figure 5 The distribution shown in the figure indicates that, due to the measured, increased maximum pressure D... Max The sealing element 12b in grooves K1, K2 and K3 has significant wear, and the dynamic pressure component D D It is basically sealed only by the sealing element 12b located in the groove K4.

[0029] C) If daily measurements are taken over a longer period, such as a month or a year, then Figure 5 The measurement results shown are particularly useful for providing information, storing these results, and analyzing them if they change over time. As the operating time of the piston rod sealing system 12 increases, the maximum pressure D... Max Or dynamic pressure component D D That is, the maximum pressure D measured in a single tank K1, K2, K3, K4. Max static pressure D A The difference between them will increase from groove K1 in the direction toward the outlet side A, thus from Figure 5 The measurement results shown indicate which sealing element 12b still contributes to the seal and to what extent that single sealing element 12b still contributes to the seal, or to what extent that single sealing element 12b has been damaged. In other words, the maximum pressure D Max Or dynamic pressure component D D As operating time increases, the pressure penetrates deeper into the piston rod sealing system 12 or into subsequent grooves K2, K3, and K4, thereby increasing the dynamic pressure component D in a single groove. D The changes over time can determine the condition changes of the sealing element 12b. The condition of the piston rod sealing system 12, and especially the condition or wear of individual sealing elements 12b (at least one of the sealing elements 12b), can thus be determined or observed very precisely, thereby enabling, for example, whether the piston rod sealing system 12 is still reliably sealing, or to infer how long the piston rod sealing system 12 can continue to reliably seal, or to assess which sealing element 12b and preferably when these individual sealing elements 12b should be replaced or maintained.

[0030] Figure 7 Another example of monitoring the condition of the piston rod sealing system 12 is shown. Figure 7 The maximum pressure D of tanks K1 to K6 shown in the figure Max The measured value was obtained in the piston rod sealing system 12, which is compared to... Figure 2 The piston rod sealing system shown has six slots K1 to K6 arranged sequentially along the longitudinal direction, each slot having a sealing element 12b disposed therein, wherein the sealing element 12b is relative to the piston rod sealing system shown in the figure. Figure 2 The embodiment does not contact the piston rod 16 or only makes slight contact with the piston rod 16, thus creating at least a partial gap between the end face of the sealing element 12b and the piston rod 16. Through a series of connections of this frictionless sealing element 12b, the pressure difference is distributed to all grooves K1 to K6 at different values. The method according to the invention is also applicable to monitoring the condition of this piston rod sealing system 12. Figure 7 The values ​​U1 to U6 indicate the maximum pressure D present in the corresponding grooves K1 to K6 under the condition of the new piston rod sealing system 12. Max . Figure 7 The values ​​V1 to V6 represent the maximum pressure D present in the corresponding tanks K1 to K6 after a certain operating phase, for example, after 2000 hours of operation. Max The difference between values ​​such as U1-V1 or U2-V2 indicates the dynamic pressure component D that has occurred during this operating phase. D The changes in the condition of the piston rod sealing system 12 or individual sealing elements 12b in the corresponding slots K1 to K6 can be monitored, thereby enabling the detection of necessary maintenance of the sealing elements 12b at an early stage, ensuring the safe operation of the piston rod sealing system 12 and defining the time window for any necessary maintenance.

[0031] Figure 6 A longitudinal section of another piston rod sealing system 12 is shown, which includes a first partial seal 12x and a second partial seal 12y. The first partial seal 12x includes and Figure 4 The same grooved ring 12a with grooves K8, K9, K10, and K11 shown herein, and friction sealing elements 12b arranged in these grooves, each friction sealing element 12b including a sealing ring 12e, a support ring 12c, and a cover ring 12d. According to Figure 6The piston rod sealing system 12 also includes a gas leakage passage 12g and two grooved rings 12a arranged downstream toward the outlet side A, in which damping rings 12j are arranged. The second partial seal 12y comprises seven grooved rings 12a arranged continuously along the longitudinal direction L and having grooves K1, K2, K3, K4, K5, K6, and K7, with a pressure relief ring 12i arranged as a sealing element 12b in each of these grooves. This pressure relief ring 12i has the property that it does not completely seal the gas leakage along the longitudinal direction L, but rather reduces the dynamic pressure component D. D The amplitude. In the illustrated embodiment, sensor 26 is arranged to monitor the pressure in groove K11, and sensor 26a is arranged to monitor the pressure in groove K7. This arrangement is again applicable to monitoring the condition of the piston rod sealing system 12 or the condition of the sealing element 12b located therein. Figure 9 The maximum pressure D in grooves K7 and K11 of the new piston rod sealing system 12 is shown. Max The measured values ​​V7 and V11 are shown, along with the values ​​W7 and W11, which represent, for example, the maximum pressure D in tanks K7 and K11 after 5000 hours of operation. Max The measured values ​​also show the values ​​X7 and X11, which are, for example, the maximum pressure D in tanks K7 and K11 after 10,000 hours of operation. Max The measured values ​​show that the piston rod sealing system 12 still operates reliably after 5,000 hours of operation; however, value X7 shows that the pressure relief ring 12i or the second partial seal 2y no longer provides sufficient sealing effect after 10,000 hours of operation, while the sealing effect of the first partial seal 12x still meets the requirements.

[0032] In other advantageous embodiments, in accordance with Figure 6 In the piston rod sealing system 12, starting from the inlet side E, the pressure sensor 26a can be arranged in the last grooved ring 12a in which the pressure relief ring 12i is arranged, and thus in the groove K7, the pressure sensor 26 can be arranged in the first grooved ring 12a in which the friction sealing ring 12e is arranged, and thus in the groove K8, to detect the state or state change of the pressure relief ring 12i arranged in the groove 7 in the most probable way.

[0033] exist Figure 4 , 5 In the embodiment shown in Figure 7, the pressure in the corresponding groove K is monitored by measuring the maximum pressure that appears in the corresponding groove K. Next, the pressure in the corresponding groove K is measured. Instead of the maximum pressure, a pressure curve varying with the crankshaft angle can also be measured. Figure 8 This pressure curve D is shown as a function of crankshaft angle. VThe increase during the rising phase can be used to deduce the maximum value, the crankshaft angle at which the maximum value is reached, or the decrease during the falling phase, and can also be used to deduce the condition of the sealing element at 12h.

[0034] It is advantageous, for example, to use an infrared sensor to measure the temperature T in the piston rod sealing system 12, particularly the temperature of the piston rod 16, at at least one location. A healthy, functioning friction ring can cause the piston rod 16 to overheat due to friction. Temperature detection at a location in the piston rod sealing system 12, particularly at the piston rod 16, provides additional indication of the condition of the sealing element 12b. Furthermore, a damaged sealing element 12b and / or an elastically-plastically deformed sealing element 12 can also cause the piston rod 16 to overheat; this condition can be detected by measuring the temperature.

[0035] Figure 10 A simplified longitudinal section of another embodiment of a cylinder 2 with a bidirectional piston 3 is schematically shown, which divides the interior into a first compression chamber 6 and a second compression chamber 7. (Compared to...) Figure 1 Unlike the embodiment, another piston rod sealing system 12 is arranged on the end face of the second compression chamber 7, wherein, according to... Figure 1 Compared to the previous embodiment, the piston rod 16 extends from the piston 3 in the direction of the longitudinal axis L, extends through another piston rod sealing system 12, and is mounted such that it can be displaced in the direction of the longitudinal axis L. Thus, both piston rod sealing systems 12 have an inlet side E and an outlet side A, and at least one, and preferably both, piston rod sealing systems 12 can operate according to the condition monitoring method according to the invention.

[0036] In the example shown, the piston compressor 1 is typically depicted as a horizontal piston compressor. However, piston compressors can also operate in different directions, and in particular, can be designed to operate vertically with a vertically extending piston rod.

[0037] All illustrated embodiments show a double-acting piston 3, but the piston may also have a single-acting design, in which the cylinder 2 has only one compression chamber 6.

[0038] Multiple piston compressors 1 or multiple cylinders 2 can also be connected in series, such as 2, 3, 4 or 5, where the final pressure of the preceding cylinder forms the suction pressure of the next cylinder. In this series arrangement, for example, the suction pressure D of one of the cylinders... A The final pressure D of this cylinder can be 80 bar. E The pressure can be 300 bar. At least one of the reciprocating compressors 1 connected in this manner, and preferably all of the compressors or the cylinders 2 connected in sequence, can operate according to the method of the invention or have the means according to the invention.

Claims

1. Method for monitoring the condition of a piston rod sealing system (12) of a reciprocating compressor (1) comprising a compression chamber (6, 7), wherein a gas is compressed in the compression chamber (6, 7) of the reciprocating compressor (1) from a suction pressure (D A ) to a discharge pressure (D E ), the piston rod sealing system (12) comprising at least two groove rings (12a) arranged one after the other in a longitudinal direction (L) and each having at least one sealing element (12b) arranged therein, wherein a piston rod (16) extending through the sealing elements (12b) and the groove rings (12a) is movable in the longitudinal direction (L) and is sealed by the sealing elements (12b), wherein the piston rod sealing system (12) has an inlet side (E) and an outlet side (A), wherein a pressure of the compression chamber (6, 7) is applied to the inlet side (E), and wherein a pressure difference (D K ) exists between the inlet side (E) and the outlet side (A), the existing pressure difference (D K ) having a static pressure component (D S ) and a dynamic pressure component (D D ), wherein the dynamic pressure component (D D ) varies with respect to a crank angle, and wherein a leakage gas is located in the groove rings (12a), wherein at least the dynamic pressure component (D D ) of the leakage gas is measured in the piston rod sealing system (12), and wherein a change in the state of at least one of the sealing elements (12b) is determined from a change in the dynamic pressure component (D D ) with respect to time.

2. The method of claim 1, wherein, said static pressure component (D S ) corresponds to said suction pressure (D A ), said dynamic pressure component (D D ) is determined as a difference between said pressure difference (D K ) and said static pressure component (D S ).

3. The method according to claim 1 or 2, characterized in that, The sealing element (12b) is configured to form a gas seal by abutting to a friction seal ring (12e) of the piston rod (16), the friction seal ring (12e) being sealed by means of friction present between the friction seal ring (12e) and the piston rod (16).

4. The method of claim 1 wherein, The sealing element (12b) comprises at least one pressure relief ring (12i) which is not completely sealed.

5. The method of claim 3 wherein, At least in the slot ring (12a) farthest from the inlet side (E) in the longitudinal direction, the dynamic pressure component (D D ) of the leakage gas is measured.

6. The method of claim 4 wherein, The piston rod sealing system (12) comprises along the longitudinal direction (L) from the entry side (E) a number of groove rings (12a) with a pressure relief ring (12i) arranged therein and subsequently a number of groove rings (12a) with a friction sealing ring (12e) arranged therein, the dynamic pressure component (D D ) of the leakage gas being measured in the last groove ring (12a) with a pressure relief ring (12i) arranged therein or in the first groove ring (12a) with a friction sealing ring (12e) arranged therein.

7. The method of any one of claim 1, characterized in that, The dynamic pressure component (D D ) of the leaked gas is measured in a plurality of grooved rings (12a), and the state of the sealing element (12b) located in the corresponding grooved ring (12a) is determined based on the maximum amplitude (D Max ) measured in each grooved ring (12a).

8. The method of claim 7, wherein, The maximum amplitude (D max1 , D max2 , D max3 ) of the dynamic pressure component (D D ) existing in the corresponding groove-shaped torus (12a) increases from the inlet side (E) towards the outlet side (A) with increasing operating time of the piston rod sealing system (12), and wherein the state of the sealing element (12b) located in these groove-shaped tori (12a) is determined by the difference of the maximum amplitudes (D max1 , D max2 , D max3 ) of two adjacent groove-shaped tori (12a).

9. The method according to the preceding claim 1, characterized in that, The dynamic pressure component (D D ) is monitored for changes over a period of at least 2000 hours.

10. The method according to the preceding claim 1, characterized in that, The temperature (T) is measured at at least one location in the piston rod sealing system (12).

11. Monitoring system for monitoring the condition of a piston rod sealing system (12) of a reciprocating compressor (1), wherein the reciprocating compressor (1) comprises a piston (3) and a compression chamber (6, 7), wherein a gas can be compressed from a suction pressure (D A ) to a discharge pressure (D E ) by means of the piston (3) in the compression chamber (6, 7), wherein the piston rod sealing system (12) comprises at least two groove rings (12a) arranged one behind the other in the longitudinal direction (L), each with at least one sealing element (12b) arranged therein, wherein a piston rod (16) movable back and forth in the longitudinal direction (L) extends through the sealing elements (12b) and the groove rings (12a), wherein the piston rod (16) is connected to the piston (3), wherein the piston rod sealing system (12) has an inlet side (E) to which the pressure of the compression chamber (6, 7) is applied and an outlet side (A), wherein at least one pressure sensor (26, 26a) for measuring at least the dynamic pressure component (D D ) of the leakage gas in the groove ring (12a) is provided, and wherein a storage and evaluation unit (22) stores a plurality of measured dynamic pressure components (D D ), and wherein the evaluation unit (22) monitors the change in the dynamic pressure component (D D ) over time and from this infers a change in the state of at least one of the sealing elements (12b).

12. The monitoring system of claim 11, wherein, The monitoring system determines the difference between the pressure difference (D K ) and the static pressure component (D S ) as the dynamic pressure component (D D ).

13. The monitoring system of claim 11 or 12, characterized in that The sealing element (12b) is designed as a friction ring against the piston rod (16), and wherein a pressure sensor is arranged at least in the groove ring (12a) closest to the outlet side (A) to measure at least the dynamic pressure component (D D ) of the leaking gas in the groove ring (12a).

14. The monitoring system of claim 13, wherein, Along the running direction (L) of the piston rod (16), starting from the inlet side (E), first a sealing element (12b) designed as a pressure relief ring (12i) is arranged, and wherein next towards the outlet side (A) a sealing element (12b) designed as a friction ring is arranged, and wherein at least one pressure sensor (26) is arranged in the longitudinal direction (L) between the pressure relief ring (12i) and the sealing element (12b) designed as a friction ring.

15. A reciprocating compressor operated by the method according to any one of claims 1 to 10.

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