Leak detection method on a fluid machine located on a fluid transfer line
The method addresses unreliable leak detection in fluid machines by using pressure monitoring and balancing to ensure timely maintenance and prevent unexpected machine failures.
Patent Information
- Application Number
- FR2023000229
- Authority / Receiving Office
- FR · FR
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2023-01-10
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2033-01-10
AI Technical Summary
Existing leak detection methods for fluid machines on transfer lines are unreliable, fail to anticipate maintenance needs, and do not effectively detect wear in sealing elements, leading to unexpected machine stoppages and inefficient maintenance schedules.
A method involving pressure measurements upstream and downstream of the fluid machine, with multiple follow-up stages to monitor valve states and pressure balancing, allowing for precise leak detection and wear assessment.
Enables reliable and proactive leak detection and maintenance scheduling, reducing unexpected machine stoppages and improving operational efficiency by accurately identifying valve wear.
Smart Images
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Abstract
Description
Title of the invention: Method for detecting a leak on a fluid machine arranged on a fluid transfer line
[0001] The invention relates to a method for detecting a leak on a fluid machine arranged on a fluid transfer line. The fluid machine may be a compressor or a positive displacement pump.
[0002] A fluid machine generally comprises a cylinder and a piston which is slidably mounted within the cylinder. It also comprises at least one first valve configured to allow flow of fluid into the cylinder through a first opening of the cylinder and at least one second valve configured to allow exit of fluid from the cylinder through a second opening of the cylinder.
[0003] Valves are sealing elements intended to prevent any leakage during operation of the machine integrated on a fluid transfer line. Valves, like many other sealing elements of the fluid machine, wear out after a certain period of operation and are therefore considered as spare parts that can be replaced in the event of wear.
[0004] Wear of the sealing elements may be the result of one or more of the following factors: high temperature, high pressure, linear speed, surface damage, incompatibility with the fluid to be treated, etc. As a general rule, to ensure proper operation of the fluid machine in the face of these factors, which are numerous and whose influence on the service life of the sealing elements is not always controlled, fluid machine manufacturers recommend a maintenance plan with periodic replacement of the sealing elements.
[0005] According to this maintenance plan, even if the machine is used very little between two planned maintenance operations, the sealing elements must be replaced at the deadline provided for this purpose. Thus, this maintenance plan may lead to the replacement of parts still in working order correctly. Furthermore, in the event of abnormal operation of the machine between two planned maintenance operations, premature wear of the sealing elements may occur, leading to significant leaks before the maintenance deadline. This requires the emergency replacement of the defective elements, resulting in an unexpected shutdown of the machine.
[0006] In a known manner, a method for detecting leaks on a fluid machine installed on a transfer line consists of recording, on the transfer line, the average flow rate at the outlet of the fluid machine. According to this method, there is a leak on the fluid machine when the flow rate decreases by 20 to 30% at the outlet of the machine. With such a range of flow values, this method remains unreliable for detecting the start of a leak.
[0007] Furthermore, there is a leak monitoring method based on the use of a pressure switch or a flow switch. While such a method can be very accurate (10-60 NL / min), the result obtained can fluctuate depending on the operating conditions of the machine, not to mention the fact that the flow detection range is narrow and does not allow for better anticipation of maintenance operations. In addition, such a method generates an alarm or a shutdown late, without any preventive message. Finally, such a method does not allow for the detection of wear of non-return valves.
[0008] One aim of the invention is to at least partially overcome the drawbacks listed above.
[0009] To this end, the invention proposes a method for detecting leaks on a fluid machine as described in the preamble and arranged on a fluid transfer line, the method comprising: - an initial step consisting of carrying out, on the transfer line which has been shut down, a first pressure measurement on a portion of the transfer line located upstream of the fluid machine and a second pressure measurement on a portion of the transfer line located downstream of the machine, - a first monitoring step consisting of monitoring, over a determined period, called the first monitoring period, a change in the first pressure measurement and a change in the second pressure measurement, to determine a state of the first valve and a state of the second valve.
[0010] Thus, by providing detection on a transfer line that is shut down, the invention makes it possible to overcome the operational difficulties posed by leak detection during operation of the fluid machine.
[0011] Embodiments of the invention may include one or more of the following features: - the first monitoring stage indicates an absence of leakage on the fluid machine when, during the first monitoring period, the first pressure measurement remains constant and the second pressure measurement increases to a maximum value greater than a value of the first pressure measurement, - the method comprises a second monitoring step consisting of monitoring during a determined period, called the second monitoring period, a change in the first pressure measurement and / or a change in the second pressure measurement, - the second monitoring stage indicates a leak at the first valve when, during the second monitoring period, the first pressure measurement decreases from the constant value recorded during the first monitoring stage, - the second monitoring stage indicates a leak at the second valve when, during the second monitoring period, the second pressure measurement decreases from the maximum value reached at the end of the first monitoring stage, - the first monitoring stage indicates a leak at the first valve when, during the first monitoring period, the first pressure measurement increases to a value of the second pressure measurement, - the method comprises a pressure balancing step in the fluid machine and in the portions of the transfer line located on either side of the fluid machine, the balancing step being implemented at the end of the first monitoring step when the first pressure measurement indicates a value greater than or equal to a value given by the second pressure measurement, - the method comprises a third monitoring step subsequent to the balancing step, the third monitoring step consisting of monitoring during a determined period, called the third monitoring period, a change in the first pressure measurement and a change in the second pressure measurement to determine a state of the first valve and a state of the second valve, - the third monitoring stage indicates a leak at the piston sealing rings when, during the third monitoring period, the first pressure measurement decreases, - the third monitoring stage indicates a leak at the second valve and piston sealing rings when, during the third monitoring period, the second pressure measurement decreases.
[0012] Other features and advantages will appear on reading the description below, given with reference to the following figures in which:
[0013] [Fig-1] is a schematic view of a transfer line incorporating a machine fluid
[0014] [Fig.2] illustrates the steps of the detection method according to the invention.
[0015] The invention relates to a method for detecting a leak on a fluid machine 1 arranged on a fluid transfer line 10.
[0016] In particular, the machine 1 comprises a cylinder 2 and a piston 3 which is slidably mounted inside the cylinder 2. The cylinder 2 and the piston 3 form a chamber 4 which has an opening 5 for the fluid to enter the chamber 4 and an opening 6 for the fluid to exit the chamber 4. The inlet opening 5 and the outlet opening 6 are each equipped with a non-return valve CV1, CV2.
[0017] In other words, the valve CV1 is configured to allow a flow of fluid into the cylinder 2 through the first opening 5 of the cylinder 2. The valve CV2 is configured to allow an exit of the fluid from the cylinder 2 through the second opening 6 of the cylinder 2.
[0018] The transfer line 10 ensures a flow of fluid from a fluid source 7 to a reservoir 8 to be filled, passing through the fluid machine 1. The transfer line 10 thus comprises a first portion 10a located upstream of the fluid machine 1 and a second portion 10b located downstream of the fluid machine 1. In the following, the first portion 10a will be referred to as the “upstream portion” and the second portion 10b as the “downstream portion”.
[0019] Each portion 10a, 10b is equipped with a valve HV10, HV20. In addition, each portion 10a, 10b is equipped with a pressure sensor PT1, PT2. As a variant or in addition to a pressure sensor PT1, PT2, each portion 10a, 10b of the transfer line 10 may be equipped with a temperature sensor not shown.
[0020] Advantageously, the transfer line 10 comprises at least one bypass line connected to a buffer storage B1, B2. The at least one bypass line is provided with a regulating valve HV11, HV21. Here, two bypass lines, two buffer storages B1, B2 and two regulating valves HV11, HV21 are arranged on either side of the fluid machine 1.
[0021] The pressure and / or temperature sensors PT1, PT2, the valves HV10, HV20, HV11, HV21 are connected to a programmable electronic control PLC unit.
[0022] To detect a possible leak on the fluid machine 1 installed on the transfer line 10 described above, the method according to the invention comprises an initial step S0 consisting of carrying out, on the transfer line 10 which is stopped, a first pressure measurement M1 on the upstream portion 10a of the transfer line 10 and a second pressure measurement M2 on the downstream portion 10b of the transfer line 10. The first pressure measurement is given by the pressure sensor PT1. The second pressure measurement is given by the pressure sensor PT2.
[0023] The method also comprises a first monitoring step SI consisting of monitoring during a determined period, called first monitoring period T1, a change in the first pressure measurement M1 and a change in the second pressure measurement M2, to determine a state of the first valve CV1 and a state of the second valve CV2.
[0024] Thus, when during the first monitoring period T1, the first pressure measurement M1 remains constant and the second pressure measurement M2 increases to a maximum value greater than a value of the first pressure measurement M2, the method indicates an absence of leakage on the fluid machine 1.
[0025] On the other hand, when during the first monitoring period T1, the first pressure measurement M1 increases until it reaches a value of the second pressure measurement M2, the method indicates a leak at the first valve CV1.
[0026] At the end of the first monitoring period T1, a new monitoring step S2 is carried out to monitor the evolution of the pressure measurements M1, M2. The second step S2 is executed during a specific period, called the second monitoring period.
[0027] Thus, when, during the second monitoring period T2, the first pressure measurement M1 decreases from the constant value recorded during the first monitoring step SI, the method suggests a leak at the first valve CV1. Similarly, when the second pressure measurement M2 decreases from the maximum value reached at the end of the first monitoring step SI, the method suggests a leak at the second valve CV2.
[0028] It should be noted that at the end of the first monitoring step SI, when the first pressure measurement M1 indicates a value greater than or equal to a value given by the second pressure measurement M2, the method according to the invention implements a pressure balancing step SE in the fluid machine 1 and in the upstream and downstream portions 10a, 10b of the transfer line 10. More specifically, the balancing step SE aims to balance the pressure between a volume V0 of the machine 1, a volume VI of the upstream portion 10a and a volume V2 of the downstream portion 10b of the transfer line. For the purposes of this balancing step SE, at least one of the buffer storages B1, B2 can be used.
[0029] It should be noted that the balancing step is executed over a determined period, called the balancing period, at the end of which the valve HV11, HV21 of the buffer storage B1, B2 previously used is closed. Advantageously, the balancing period is set at 5 seconds.
[0030] At the end of the balancing period, the method provides a new monitoring step S3 consisting of monitoring, during a determined period, called the third monitoring period T3, a change in the first pressure measurement M1 and a change in the second pressure measurement M2 to determine a state of the first valve CV1 and a state of the second valve CV2.
[0031] Thus, when, during the third monitoring period T3, the first pressure measurement M1 decreases, the method suggests a leak at the first valve CV1. Similarly, when, during the third monitoring period T3, the second pressure measurement M2 decreases, the method suggests a leak at the second valve CV2.
[0032] Advantageously, the pressure measurements M1, M2 can be replaced or supplemented by temperature measurements carried out on the upstream 10a or downstream 10b portions of the transfer line.
Claims
Claims
1. Method for detecting a leak on a fluid machine (1) arranged on a fluid transfer line (10), the machine (1) comprising a cylinder (2) and a piston (3) which is slidably mounted inside the cylinder (2), the machine (1) also comprising at least one first valve (CV1) configured to allow a flow of the fluid into the cylinder (2) through a first opening (5) of the cylinder (2) and at least one second valve (CV2) configured to allow an exit of the fluid from the cylinder (2) through a second opening (6) of the cylinder (2), the method comprising: - an initial step (S0) consisting of carrying out, on the transfer line (10) stopped, a first pressure measurement (M1) on a portion of the line (10) located upstream of the fluid machine (1) and a second pressure measurement (M2) on a portion of the line (10) located downstream of the machine (1),- a first monitoring step (SI) consisting of monitoring during a determined period, called the first monitoring period (Tl), a change in the first pressure measurement (Ml) and a change in the second pressure measurement (M2), to determine a state of the first valve (CV1) and a state of the second valve (CV2).,
2. A method according to claim 1, wherein the first monitoring step (SI) indicates an absence of leakage on the fluid machine (1) when, during the first monitoring period, the first pressure measurement (Ml) remains constant and the second pressure measurement (M2) increases to a maximum value greater than a value of the first pressure measurement (M2).
3. Method according to claim 1, in which the first monitoring step (SI) indicates a leak at the first valve (CV1) when, during the first monitoring period, the first pressure measurement (Ml) increases until it reaches a value of the second pressure measurement (M2).
4. Method according to claim 2, comprising a second monitoring step (S2) consisting of monitoring during a determined period, called second monitoring period (T2), a change in the first pressure measurement (M1) and / or a change in the second pressure measurement (M2).
5. A method according to claim 4, wherein the second step (S2) monitoring indicates a leak at the first valve (CV1) when, during the second monitoring period, the first pressure measurement (Ml) decreases from the constant value recorded during the first monitoring stage (SI).
6. Method according to any one of claims 4 or 5, in which the second monitoring step (S2) indicates a leak at the second valve (CV2) when, during the second monitoring period, the second pressure measurement (M2) decreases from the maximum value reached at the end of the first monitoring step (SI).
7. Method according to claim 1, comprising a step (SE) of balancing pressure in the fluid machine (1) and in the portions (10a, 10b) of the transfer line (10) located on either side of the fluid machine (1), the balancing step (SE) being implemented at the end of the first monitoring step (SI) when the first pressure measurement (M1) indicates a value greater than or equal to a value given by the second pressure measurement (M2).
8. Method according to claim 7, comprising a third monitoring step (S3) subsequent to the balancing step (SE), the third monitoring step (S3) consisting of monitoring during a determined period, called the third monitoring period (T3), a change in the first pressure measurement (M1) and a change in the second pressure measurement (M2) to determine a state of the first valve (CV1) and a state of the second valve (CV2).
9. Method according to claim 8, in which the third monitoring step (S3) indicates a leak at the first valve (CV1) when, during the third monitoring period (T3), the first pressure measurement (Ml) decreases.
10. Method according to any one of claims 8 or 9, in which the third monitoring step indicates a leak at the second valve (CV2) when, during the third monitoring period (T3), the second pressure measurement (M2) decreases.