LEAK DETECTION FROM DIAPHRAGM COMPRESSOR

A diaphragm compressor having a compressor head with a hydraulic fluid plate having a fluid plate contact plane and a process fluid plate having a process plate contact plane, the plates forming a compression chamber when contact therebetween is established, the compression chamber being divided in an upper chamber and a lower chamber by a multi-layered diaphragm where a controller is configured for controlling an alternating movement of the multi-layered diaphragm towards the upper and the lower chambers respectively, a process fluid plate seal is positioned in a process fluid seal groove provided in the contact plane, the process fluid plate seal forms a process fluid seal between an upper side of the multi-layered diaphragm and the contact plane, and the process fluid plate includes a process fluid leak groove system fluidly connected to a process fluid plate leakage passage provided in the process fluid plate.

TECHNICAL FIELD

The disclosure relates to a diaphragm compressor having a multi-layered diaphragm having means for detection gas and oil leaks and to a method of detection of oil and gas leaks from a diaphragm compressor.

BACKGROUND

Leakage detection from multi-layered diaphragm compressors is known in the art e.g. from Chinese patent application No. CN110529370, French patent application No. FR2764344 and U.S. Pat. No. US5501577. As described therein, either gas leaks or a mix om leaking working fluid and “gas fluid” are detected. Based on a sensor measurement of the amount of leaked gas or mixed “gas fluid” and working fluid a controller may stop the operation of the diaphragm compressor. However, no prior art leakage detection systems describe how to continue detecting leakage if e.g. the sensor fails or how to determine the amount of leaked gas in the mix of leaked working fluid and “gas fluid”.

BRIEF SUMMARY

The present disclosure addresses the deficiencies with prior art leakage detection systems by a diaphragm compressor having a compressor head comprising a hydraulic fluid plate having a fluid plate contact plane and a process fluid plate having a process plate contact plane, the fluid plate and the process plate forms a compression chamber when contact between the fluid plate contact plane and the process plate contact plane is established, the compression chamber is divided in an upper chamber and a lower chamber by a multi-layered diaphragm,wherein a controller is configured for controlling an alternating movement of the multi-layered diaphragm towards the upper and the lower chambers respectively,wherein a process fluid plate seal is positioned in a process fluid seal groove provided in the contact plane, the process fluid plate seal forms a process fluid seal between an upper side of the multi-layered diaphragm and the contact plane, andwherein the process fluid plate comprises a process fluid leak groove system fluidly connected to a process fluid plate leakage passage provided in the process fluid plate.

This is advantageous in that it has the effect, that process fluid leaking at the seal is separated from potential leaks of hydraulic fluid making detection of leaking process fluid easier compared to detection hereof leaks of process fluid and hydraulic fluid are mixed as described in the prior art. Accordingly, the present disclosure ensures that leaking gas is not contaminated by hydraulic fluid.

The movement of the diaphragm is controlled by the controller controlling, preferably with viable speed, a motor that is driving a crankshaft connected to a piston, which via a working fluid facilitates the alternating reciprocating movement of the diaphragm towards the upper and lower chambers. Hence, the concept of establishing movement of the diaphragm and thereby compression of the process fluid is known in that art and is therefore not described in further details.

According to an exemplary embodiment, the process fluid leak groove system comprises an inner groove and an outer groove connected with a plurality of connection grooves.

This is advantageous in that it has the effect that this design allows high pressure in the chamber and still ensuring fixed position of the seal in the seal groove. The risk of the seal being pushed out into the outer leakage groove is thereby eliminated. Accordingly, the distance between the outer groove and the seal ensures that pressure up to and even above 1000 bar in the chamber can be established at the same time as leakage can be detected.

The higher pressure required in the chamber, the larger distance between the seal groove / inner leakage groove is required in order to ensure fixation of the seal in the seal groove. However, the process and fluid plates are made of metal and the two planes are therefore flat planes of metal tightened very fast against each other making it difficult for leaked process fluid to escape without the leakage groove system. Hence, the process fluid leak groove system is advantageous in that it has the effect, that the connecting grooves and the inner groove together guides leaked process fluid to the outer groove. Thereby establishing a pathway for leaked process fluid from the seal to the process fluid plate leakage passage between or though the two planes of the process and fluid plates when these are fastened tight together.

The division of the compressor head in upper / lower head parts and process / hydraulic fluid plates is advantageous in that it has the effect, that the if anything happens to a groove or chamber, the fluid plates can be replaced and not the entire upper / lower parts of the compressor head.

According to an exemplary embodiment, the geometric shape of the compression chamber in a top view is oblong shaped.

The oblong shaped geometry is advantages in that it has the effect, that it is possible to obtain a larger chamber volume with the same material as compared to other shapes such as traditional circular shaped chambers. Hence due to increased clamping force and improved gas and heat distribution the pressure vs material volume ratio, obtained by an oblong shaped chamber is higher than with traditional circular chamber designs.

According to an exemplary embodiment, the process fluid plate and the upper head part are manufactured as one inseparable part.

According to an exemplary embodiment, the hydraulic fluid plate and the lower head part are manufactured as one inseparable part.

Having only one upper / lower head part including the process / hydraulic fluid plate contact planes and the process / hydraulic fluid leak groove systems is advantageous in that then only one upper and one lower manufacturing piece has to be designed and no additional connections between compressor head parts are need but between the upper and lower head parts.

According to an exemplary embodiment, a hydraulic fluid plate seal is positioned in a hydraulic fluid seal groove provided in the contact plane, the hydraulic fluid plate seal forms a hydraulic fluid seal between a lower side of the multi-layered diaphragm and the contact plane, and wherein the hydraulic fluid plate comprises a hydraulic fluid leak groove system fluidly connected to a hydraulic fluid plate leakage passage provided in the hydraulic fluid plate.

This is advantageous in that it has the effect, that hydraulic fluid leaking at the hydraulic seal is not mixed with potential leaks of process fluid making detection of leaking hydraulic fluid easier compared to detection of leaks of hydraulic fluid mixed with process fluid.

Further, an advantage of the separation of leaked hydraulic fluid and leaked process fluid is that the system volume of the of grooves in the hydraulic fluid system can be made larger than the system volume of the grooves of the process fluid system. This is advantageous in that it has the effect, that it allows effective detection of a hydraulic leak due to the lack of expansion of hydraulic fluid when it leaks. The system volume of the process fluid grooves is not as critical because the process fluid, which is typically a gas, expands significantly in volume upon decompression (leakage).

According to an exemplary embodiment, the hydraulic fluid leak groove system comprises an inner groove and an outer groove connected with a plurality of connection grooves.

The hydraulic fluid leak groove system is advantageous in that it has the effect, that the it allows high pressure in the lower chamber without risk of the hydraulic fluid seal being forced out to the outer groove. The is because the outer groove is spaced from the inner groove / seal groove by a part of the material of the hydraulic plate. The part being determined by the desired pressure in the lower chamber.

According to an exemplary embodiment, the number of connection grooves in the hydraulic fluid plate is higher than the number of the connection grooves in the process fluid plate.

This is advantageous in that it has the effect, that because the viscosity of the hydraulic fluid is higher than of the process fluid, it moves slower in the grooves than the process fluid and therefore to detect hydraulic leakage as fast or at least close to as fast as detection of process fluid leakage, the number of connections grooves in the hydraulic fluid plate has to be higher than in the process fluid plate.

According to an exemplary embodiment, the multi-layered diaphragm comprises a leak detection diaphragm positioned between a process fluid diaphragm and a hydraulic fluid diaphragm, wherein the leak detection diaphragm comprises one or more process side diaphragm grooves provided in the side of the leak detection diaphragm facing the process fluid diagram.

According to an exemplary embodiment, the leak detection diaphragm furthermore comprises one or more hydraulic side diaphragm grooves provided in the side of the leak detection diaphragm facing the hydraulic fluid diagram.

This is advantageous in that it has the effect, that it allows process / hydraulic fluid leaked through cracks in the respective diaphragms to escape to the process / hydraulic fluid leak groove system primarily, but not necessarily only during the intake stroke where the diaphragm is pulled downwards allowing process / hydraulic fluid to escape between the process fluid diaphragm and leakage detection diaphragms and / or between the hydraulic diaphragm and the leakage detection diaphragm.

Having a leakage detection diaphragm together with a process and / or a hydraulic fluid seal and the process side and / or hydraulic side fluid leak groove systems is advantageous in that it has the effect, that both leakage via the diaphragm and via the seal(s) can be detected. This can be done without leakages of process and hydraulic fluid is mixed.

According to an exemplary embodiment, the number of hydraulic side diaphragm grooves is higher than the number of process side diaphragm grooves.

This is advantageous in that it has the effect, that it increases the speed with which leaked hydraulic fluid with higher viscosity than process fluid can escape the volume between the leak diaphragm and the fluid diaphragm in case of a leak in the hydraulic fluid diaphragm.

According to an exemplary embodiment, the one or more process side diaphragm grooves extends between a first end and a second end,wherein the position of the first end is located in non-clamped part of the leak detection diaphragm, andwherein the position of the second end is located in the clamped part of the multi-layered diaphragm, preferably in the part of the leak detection diaphragm that is aligned with the outer groove when the compressor head is assembled.

According to an exemplary embodiment, the process fluid diaphragm comprises one or more holes wherein at least one hole is located in a position so that when the process fluid diagram and the leakage detection diaphragm is mounted and forming part of the multi-layered diaphragm, the at least one hole is aligned with the second end of one of the one or more process side diaphragm grooves and thereby configured to allow process fluid to travel from the first end via the process side diaphragm grooves to the second end and through the at least one hole into the outer groove.

According to an exemplary embodiment, the one or more hydraulic side diaphragm grooves extends between a first end and a second end,wherein the position of the first end is located in non-clamped part of the leak detection diaphragm, andwherein the position of the second end is located in the clamped part of the multi-layered diaphragm, preferably in the part of the leak detection diaphragm that is aligned with the outer groove when the compressor head is assembled.

According to an exemplary embodiment, the hydraulic fluid diaphragm comprises one or more holes wherein at least one hole is located in a position so that when the hydraulic fluid diagram and the leakage detection diaphragm is mounted and forming part of the multi-layered diaphragm, the hole is aligned with the second end of one of the one or more hydraulic side diaphragm grooves and thereby configured to allow hydraulic fluid to travel from the first end via the hydraulic side diaphragm grooves to the second end and through the hole into the outer groove.

The process side and hydraulic side grooves are advantageous in that it has the effect, that leaks of process / hydraulic fluid through the diaphragm is guided by the grooves in the leakage detection diaphragm to the holes in the process / hydraulic fluid diaphragm and through one or more of these holes. The leaked process / hydraulic fluid is then further, via one or more connection grooves, guided into the outer groove to the process / hydraulic fluid plate leakage passage. Hence, process / hydraulic fluid leaking via the diaphragm is detectable and further it is not mixed with leaked hydraulic / process fluids making detection of process / hydraulic fluid leakages possible or at least easier.

In an exemplary embodiment, the grooves in both sides of the leakage detection diaphragm takes the shortest way between the first and second ends i.e. making the travel path for leaked process / hydraulic fluid between the non-clamped part of the diaphragm to the outer groove shortest.

According to an exemplary embodiment, the process fluid plate leakage passage is fluidly connected to a process fluid leakage detection system, the process fluid leakage measurement detection system comprises a process fluid leakage conductor, a process fluid leakage valve and a process fluid leakage sensor, wherein the controller is configured to open the process fluid leakage valve periodically, and stop operation of the diaphragm compressor if the measurement received from the process fluid leakage sensor exceeds a predetermined process fluid leakage conductor threshold pressure.

According to an exemplary embodiment, the hydraulic fluid plate leakage passage is fluidly connected to a hydraulic leakage detection system, the hydraulic fluid leakage detection system comprises a hydraulic fluid leakage conductor, a hydraulic fluid leakage valve and a hydraulic fluid leakage sensor, wherein the controller is configured to open the process fluid leakage valve periodically, and stop operation of the diaphragm compressor if the measurement received from the hydraulic fluid leakage sensor exceeds a predetermined hydraulic fluid leakage conductor threshold pressure.

This is advantageous in that it has the effect, that leaked process fluid can be collected and vented at predetermined time intervals. If the pressure increases in the process or hydraulic leakage detection system above a threshold pressure between two subsequent openings of the leakage valves, a warning is set by the controller that a leakage might exist or the controller may simply stop operation of the compressor.

Periodically should be understood as a time interval between any period of time between 10 minutes and 4 hours, such as 30 minutes or 60 minutes. The time interval may be longer in the hydraulic fluid system compared to the process fluid system.

According to an exemplary embodiment, the process fluid plate leakage passage and the hydraulic fluid plate leakage passage is fluidly connected into a process and hydraulic fluid leakage detection system, configured to detect leakages from both the fluid plate leakage passage and from the hydraulic fluid plate leakage passage simultaneously.

This is advantageous in that it has the effect, that the only one detection system is needed and thereby the leakage detection system is simplified

According to an exemplary embodiment, the process fluid plate leakage passage is fluidly connected to a process fluid leakage detection system,wherein the controller is communicatively connected to the process fluid leakage valve and to the process fluid leakage sensor, andwherein the controller is configured for controlling the status of the process fluid leakage valve in response to a measurement received from a process fluid leakage sensor.

This is advantageous in that it has the effect, that pressure established in the leakage conductor due to leaked process fluid can be monitored and vented when reaching a threshold pressure. Further, the controller is able to change mode of operation of the compressor in response to the measured leakage.

The process fluid leakage sensor is preferably a pressure sensor and is preferably part of the process fluid leakage detection system.

Communicatively connected should be understood as an analogue or digital connection facilitating communication of measurements from the sensor and control of status of the valve.

According to an exemplary embodiment, the controller is configured to keep the process fluid leakage valve closed for a predetermined process fluid period of time, andwithin the predetermined process fluid period of time, compare the measured pressure of the process fluid leakage conductor with a predetermined process fluid leakage conductor threshold pressure, andstop operation of the compressor if, within the predetermined process fluid period of time, the measured pressure exceeds the predetermined process fluid leakage conductor threshold pressure.

This is advantageous in that it has the effect, that during the period of time where the process fluid leakage valve is closed, it is possible to monitor if process fluid that is expected to leak is leaking via the leakage conductor. If the expected leakage is not registered in the leakage conductor, it may indicate that it leaks elsewhere in the compressor leak detection system. Hence by analyzing the development in the pressure increase established in the time period and corelated with operation state (e.g. start or continuous operation) of the compressor, it is possible to determine or predict if the compressor is leaking or is starting to leak from an unexpected part of the compressor leak detection system or compressor system in general.

According to an exemplary embodiment, the predetermined process fluid period of time is within the range of 10 - 45 minutes, preferably within 20 - 40 minutes and most preferably within 25 - 35 minutes.

According to an exemplary embodiment, the process fluid leak conductor threshold, is selected in the range of 0.1 bar to 2 bar, preferably in the range of 0.2 bar to 1 bar and most preferably in the range of 0.3 to 0.5 bar.

According to an exemplary embodiment, the controller is configured for stopping the operation of the compressor if, within the predetermined process fluid period of time, the pressure increases above an upper process fluid alarm threshold pressure.

This is advantageous in that it has the effect, that the operation of the compressor stops if pressure leaked process fluid from leaking seal or diaphragm is detected.

According to an exemplary embodiment, the upper process fluid alarm threshold pressure, is selected in the range of 0. 1 bar to 2 bar, preferably in the range of 0.5 bar to 1.5 bar and most preferably in the range of 0.75 to 1.25 bar.

According to an exemplary embodiment, the controller s configured for stopping the operation of the compressor if, within the predetermined process fluid period of time, the pressure does not increase above a lower process fluid alarm threshold pressure.

This is advantageous in that it has the effect, that in this way it is detected if leaked process fluid escapes via the leakage detection system of the present disclosure and thereby if the leakage detection system is completely tight.

According to an exemplary embodiment, the lower process fluid alarm threshold pressure, is selected in the range of 0 bar to 1 bar, preferably in the range of 0.1 bar to 0.5 bar and most preferably in the range of 0.1 to 0.3 bar.

It is not unusually, that in case the process fluid is in a gaseous state e.g. is a hydrogen gas, a small and insignificant leak of process fluid at the process fluid plate seal happens at start up and / or during operation. Hence, in exemplary embodiments leak of process fluid is expected. Accordingly, in the event that the amount of leaked process fluid is known by the controller, it can be calculated how long time it takes to reach a certain determined leak threshold pressure in the process fluid leakage conductor. The process fluid leakage detection system is advantageous in that it has the effect, that the situation, where the threshold pressure is not reached within the expected time, this indicates, that something is wrong with the process fluid system. Such error could be a leakage outside the process fluid leakage detection system / process fluid leak groove system. Further, in the situation, where the threshold pressure is reached faster than expected, this also indicates that something is wrong with the process fluid system. Such error could be a leak in the process fluid leakage detection system / process fluid leak groove system.

According to an exemplary embodiment, the process fluid leakage detection system further comprises a process fluid leakage overpressure safety valve, and wherein the process fluid leakage overpressure safety valve has a cracking pressure below 5 bar, preferably below 4 bar and most preferably below 2 bar.

A process fluid leakage overpressure safety valve is advantageous in that it has the effect, that if the pressure sensor, timer or process fluid leakage valve fails and the process fluid leaks, it can always escape through the overpressure safety valve when the pressure in the process fluid leakage conductor is above the cracking pressure (also sometimes referred to as opening pressure) of the overpressure safety vale (also sometimes referred to as relief vale) . Typically, the overpressure safety valve is a mechanically spring type valve the load to open can be adjusted.

According to an exemplary embodiment, the hydraulic fluid plate leakage passage is fluidly connected to a hydraulic leakage detection system, the hydraulic fluid leakage detection system comprises a hydraulic fluid leakage conductor and a hydraulic fluid leakage valve,wherein the controller is communicatively connected to the hydraulic fluid leakage valve and hydraulic fluid leakage sensor, andwherein the controller is configured for controlling the status of the hydraulic fluid leakage valve in response to a measurement received from a hydraulic fluid leakage sensor.

According to an exemplary embodiment, the controller is configured to keep the hydraulic fluid leakage valve closed for a predetermined hydraulic fluid period of time, andwithin the predetermined hydraulic fluid period of time, compare the measured pressure of the hydraulic fluid leakage conductor with a predetermined hydraulic fluid leakage conductor threshold pressure, andstop operation of the compressor if, within the predetermined hydraulic fluid period of time, the measured pressure exceeds the predetermined hydraulic fluid leakage conductor threshold pressure.

According to an exemplary embodiment, the predetermined hydraulic fluid period of time is within the range between 3 - 2 hours, preferably between 2 - 1.5 hours and most preferably below 1.5 hours.

No hydraulic fluid is expected to leak outside the hydraulic system, hence the time period is higher than the time period used on the process fluid side. Leakage is determined if within the period of time leaked hydraulic fluid builds up a pressure exceeding the threshold pressure.

According to an exemplary embodiment, the hydraulic fluid leakage detection system further comprises a hydraulic fluid leakage overpressure safety valve, and wherein the process fluid leakage overpressure safety valve has a cracking pressure below 5 bar, preferably below 4 bar and most preferably below 2 bar.

The hydraulic fluid measurement system has the same effects and advantages as the process fluid measurement system.

Moreover, the disclosure relates to a method of monitoring leaked process fluid from a diaphragm compressor, wherein the process fluid plate leakage passage is fluidly connected to a process fluid leakage detection system, comprising a process fluid leakage conductor, a process fluid leakage valve and a process fluid leakage sensor. Wherein the controller is communicatively connected to the process fluid leakage valve and to the process fluid leakage sensor. Wherein the controller keeps the process fluid leakage valve closed for a predetermined process fluid period of time, and within the predetermined process fluid period of time, compare the measured pressure of the process fluid leakage conductor with a predetermined process fluid leakage conductor threshold pressure, and stop operation of the diaphragm compressor if, within the predetermined process fluid period of time, the measured pressure exceeds the predetermined process fluid leakage conductor threshold pressure.

According to an exemplary embodiment, the controller keeps the process fluid leakage valve open for 0.5 - 3.5 seconds before closing it again.

This period of time is advantageous in that it has the effect, that pressure built up in the process fluid leakage conductor is equalized with its surroundings. Preferably vented via a tube to a safe location. According to an exemplary embodiment, the controller stops the operation of the diaphragm compressor if, within the predetermined process fluid period of time, the pressure of the process fluid does not increase above a lower process fluid alarm threshold pressure.

According to an exemplary embodiment, the diaphragm compressor comprises a hydraulic fluid plate leakage passage fluidly connected to a hydraulic leakage detection system, the hydraulic fluid leakage detection system comprises a hydraulic fluid leakage conductor, a hydraulic fluid leakage valve and a hydraulic fluid leakage sensor. Wherein the controller is communicatively connected to the hydraulic fluid leakage valve and hydraulic fluid leakage sensor. Wherein the controller keeps the hydraulic fluid leakage valve closed for a predetermined hydraulic fluid period of time and within the predetermined hydraulic fluid period of time, compare the measured pressure of the hydraulic fluid leakage conductor with a predetermined hydraulic fluid leakage conductor threshold pressure, and stop operation of the compressor if, within the predetermined hydraulic fluid period of time, the measured pressure exceeds the predetermined hydraulic fluid leakage conductor threshold pressure.

DETAILED DESCRIPTION

A schematic overview of a diaphragm compressor1according to an exemplary embodiment of the disclosure is shown inFIG.1.

The compressor1comprises an upper head part2aand a lower head part2b. The upper head part2ais also referred to as a process fluid plate4. The upper head part2aand the process fluid plate4may be two separate parts (illustrated) or one single part (not illustrated). The process fluid plate4is having a process plate contact plane4a. Similarly, the lower head part2bis also referred to as a hydraulic fluid plate3. The lower head part2band the hydraulic fluid plate3may be two separate parts (illustrated) or one single part (not illustrated). The hydraulic fluid plate3is having a hydraulic plate contact plane3a. When the two head parts2a,2b/ plates4,3are attached they form a compressor head2.

Inside the compressor head2, the surfaces of the upper head part2aand the lower head part3a, respectively, together form a compression chamber5. This chamber5is divided into two compartments by a multi-layered diaphragm8arranged in the same plane defined by planes3a,4a, in which the upper head part2aand the lower head2bare assembled to form the compressor head2.

The compression chamber5comprises an upper chamber6and a lower chamber7. The upper and lower chambers6,7are formed in the upper / lower head parts2a,2bor in the process and hydraulic fluid plates3,4and defined therein partly by help from the multi-layered diaphragm8as illustrated inFIG.1. The upper chamber6is generally referred to as process fluid chamber and the lower chamber7is generally referred to as the hydraulic fluid chamber.

As seen fromFIG.1a hydraulic system32is in fluid connection with the lower chamber7via hydraulic input33and hydraulic output34. An electric motor is driving a piston35via a crankshaft and thereby the piston is pumping hydraulic fluid to and from the lower chamber7and thereby controlling the movement of the multi-layered diaphragm8. Alternative methods of controlling the diaphragm exists and is known by the skilled person.

In an exemplary embodiment, the diaphragm movement is controlled as follows. When hydraulic fluid is pumped into the lower chamber7, the diaphragm8is pressed towards the upper chamber6and the volume of the upper chamber6decreases. This causes the pressure of the process fluid enclosed therein to increase, and when a certain pressure has been reached, a process fluid discharge check valve36also referred to as outlet valve mounted in the upper head opens and releases the process fluid into a second fluid system37such as a second storage vessel.

When hydraulic fluid is sucked out of the lower chamber7at the backstroke or discharge stroke of the piston35, the discharge valve36closes, the diaphragm8follows the hydraulic fluid level down, the volume of the upper chamber6increases and the pressure therein decreases. When the pressure in the upper chamber6has fallen below the inlet pressure of the process fluid, a process fluid inlet check valve38also referred to as inlet valve mounted in the upper head2aopens and process fluid flows into the upper chamber6from a first fluid system39such as a first storage vessel as long as the hydraulic piston35moves back and the volume of the upper chamber6increases. When the hydraulic piston35starts moving forward again (inlet stroke), the inlet valve38closes, and the cycle is repeated.

The first fluid system39may be a gaseous fluid system such as a hydrogen storage system having a pressure of e.g. 20-50 MPa and the second fluid system37may also be a gaseous fluid storage such as a hydrogen storage system having a pressure of e.g. 50-100 MPa. The first fluid system39may be part of a hydrogen refuelling station such as a supply storage and the second fluid system37may be a hydrogen storage of a vehicle or of the refuelling station.

FIG.1further illustrates the external part of a process fluid leakage detection system22which serves the purpose of detecting if any of the process fluid leaks from the chamber5. The leakage detection system22may be implemented as a combination of valves24,26and a sensor25. No matter how fluid escapes the chamber5it is preferred that the leakage detection system22detects it. Alternatively, more than one leakage detection system22are used. The systems may be substantially identical. It should be noted, that the illustrated hydraulic system32may include additional components than what is illustrated onFIG.1.

The compressor1and measurement system22may be connected to and controlled by the same controller9. The controller9may be a standard industrial controller typically in the art referred to as a programmable logic controller (PLC).

FIG.2illustrates an exemplary embodiment of the disclosure where the compressor comprises a replaceable hydraulic fluid plate3and a process fluid plate4and a multi-layered diaphragm8.

The hydraulic and process fluid plates3,4, are as mentioned, in this embodiment mounted to the upper and lower head part2a,2brespectively. The two head parts2a,2bare preferably connected to each other and to the fluid plates3,4by means of bolts and nuts / thread. Hence, in the circumference of the fluid plates3,4, a series of not illustrated holes would be present to facilitate this way of fastening, the bolt hole40are illustrated onFIGS.3,4aand4b.

The upper chamber6is defined by the process fluid plate seal10when the seal10is pressed against the diaphragm8. The seal10is positioned in a not illustrated seal groove. If for some reason the seal is leaking, the process fluid enters the inner groove12aof the process fluid leak groove system12. From this inner groove12a, the leaked process fluid follows the connection grooves12cto the outer groove12band further follows the outer groove12bto the process fluid plate leakage passage13. From there, the leaked process fluid enters the process fluid leakage conductor23which will be explained in further details with reference toFIG.5.

The reason for having an inner and an outer groove12a,12bis to ensure strength enough in the construction of the process fluid plate to facilitate a pressure of 1000 bar in the upper chamber6. In a non-limiting example, the distance between the inner and outer grooves12a,12bis less than 10 millimeters, preferably between5and 10 millimeters.

As illustrated on the hydraulic fluid plate3, if detection of hydraulic fluid leakage is required, it can be done by the same principles as described above with reference to the process plate4. The hydraulic fluid plate3may also comprise a not illustrated seal groove in which a hydraulic fluid plate seal16is positioned. Right next to the seal16outwards, an inner groove17ais established in the hydraulic fluid plate3. Hydraulic fluid leaked at the seal16end in the inner groove17awhere it is guided via connection grooves17cand the outer groove17bto the hydraulic fluid plate leakage passage19.

The volume / size of the outer groove17bis preferably larger than the volume / size of the outer groove12b. The volume / of the grooves in the systems12,17should be large enough to conduct leaked fluid and maintain strength of the construction. The larger volume, the longer time it takes to pressurize the volume and the longer time it takes to detect a leakage. On the other hand, the volumes should be large enough to let the leaked fluid pass through i.e. the volume of the hydraulic grooves may be larger than the process grooves.

In addition, to the above, the process and hydraulic fluid plates3,4may include a leakage seal groove and associate leak seal. This leak seal arrangement12d,17dis implemented to ensure that leaked process / hydraulic fluid only is allowed to escape via the outer grooves12c,17cand the process / hydraulic leak measurement systems22,27.

The principles of the above described seal leakage guiding systems i.e. the hydraulic and process fluid leak groove systems12,17are the same only dimensions of spaces and grooves may differ. The distance and grooves may be designed to particular fluids such as hydrogen (process fluid) and hydraulic oil (hydraulic fluid). One difference that may exist between the two plates3,4is the number of connection grooves12cand17c. As illustrated, on the hydraulic fluid plate3the distribution or density of connection grooves17cis higher than in the process fluid plate4. The reason of the higher number of connection grooves17cis that e.g. hydrogen gas needs less space to spread quickly compared to thicker hydraulic oil.

OnFIG.2, a multi-layered diaphragm8having three layers8-1,8-2,8-3is illustrated according to an exemplary embodiment. In principle the compressor1could be functioning with a one layered diaphragm, however then the leakage detection system of the present disclosure could not be made. Leakages caused by a defect diaphragm and trapped between the diaphragms8-1,8-2,8-3are guided to the monitoring systems22,27as follows.

The process fluid diaphragm8-1may be developed to a particular process fluid i.e. the material or coating of the diaphragm material may be determined by the type of process fluid to be handled by the compressor1. The same is true for the hydraulic fluid diagram 8.2. The middle diaphragm, the so-called leakage detection diaphragm8-3is specifically designed and used to ensure separation of the process and hydraulic fluids in case of one or both leaks from their respective chambers6,7. Further, the leakage diaphragm is designed to guide leaked fluid from the center towards the edge as will be described.

As indicated and described further with respect toFIGS.4aand4b, grooves or scores are established on both sides (process15and hydraulic side21) of the leak detection diaphragm8-3. Process / hydraulic fluids leaking via the process / hydraulic diaphragms8-1,8-3respectively are guide from a first end15a,21aof a score15,21located in the non-clamped part of the diaphragm8cto a second end15b,21bof the score located in the clamped part of the diaphragm8c. Typically, the leaked fluid is pushed from the first end15a,21athrough the clamped part of the diaphragm8cvia the score15,21to the second end15b,21bduring a discharge stroke of the piston35. However, fluid may also leak during intake strokes and while the compressor is not in operation.

The number of diaphragm grooves15,21may not be the same in that the process fluid typically is a gas which travels faster than a hydraulic fluid. Further, the number of diaphragm grooves do not have the match the number of connection grooves12c,17c.

As illustrated onFIG.2, the process / hydraulic fluid diaphragms8-1,8-3are equipped with holes14,20. When the three diaphragm layers8-1,8-2,8-3are put on top of each other the holes14and the second ends15bare aligned and the holes20and the second ends21bare aligned. Further, the holes14,20are aligned with the outer grooves12c,17cso fluid leaked through the diaphragms8-1,8-3is guided towards the outer grooves12c,17cat least during a discharge stroke. The diameter of the holes14,21are preferably smaller than the width of the outer grooves12b,17bmeasured in the plans3a,4ato ensure leaked fluid has easy passage to the outer grooves12b,17b.

InFIG.2, the hydraulic side diaphragm grooves21are illustrated by stipulated lines in that they are made in the side of the leakage diaphragm8-2facing downward towards the hydraulic plate3. The process side diaphragm grooves15are illustrated by solid lines in that they are made in the side of the leakage diaphragm8-2facing upwards towards the process plate4.

From the outer grooves12c,17c, the leaked fluid enters the process / hydraulic fluid plate leakage passages13,19respectively and via these passages enters the process / hydraulic fluid leakage detection systems22,27respectively.

As illustrated, the plates3,4may also include leak seal arrangements12d,17d. These leak seal arrangements12d,17dare in an exemplary embodiment implemented as a groove in which a seal is positioned. The purpose of the leak seal arrangements12d,17dis to ensure that leaked fluid escapes the compressor head2via the plate leakage passages13,19.

FIG.3(cut-through view of the plates3,4at a location including the non-clamped part of the diaphragm8-3),4a(view towards the process plate4) and4b(view towards the hydraulic plate3) illustrates the leak groove systems12,17in further details. Because the leak groove systems12,17are identical only the process fluid leak groove system12is described in the following, the hydraulic fluid leak groove system17works similar and is designed based on the same principles.

The plates3,4may be connected by bolt, the bolt holes40of which are illustrated onFIGS.3,4aand4b.

Leakages from a defect seal10,16are guided to the process / hydraulic fluid leakage detection systems22,27via the outer grooves12c,17c. As illustrated in the exemplary embodiment ofFIG.3, the process and hydraulic fluid plates3,4includes similar leak groove systems12,17. In the embodiment, where only leakages of process fluid are relevant to monitor, only the leak groove system12is necessary and vice versa. When leakage detection of both process and hydraulic fluids are needed the present disclosure is advantageous in that separation of the two types of leaked fluids are facilitated.

Right next to the seal10outwards an inner groove12ais established in the plate4. The inner groove12aand the connection grooves12cshould only be large enough to be able to guide leaked fluid to the outer groove12b. The connection grooves12care used to guide leaked fluid from the inner groove12ainto the outer groove12b.

Generally, the grooves are as small as possible to hold an appropriate seal and to form sufficient passage for leaked fluid in order to maintain as much strength in the plates3,4as possible.

It should be noted, that in an exemplary embodiment, the number of connection grooves17cin the hydraulic fluid plate3is higher than the number of connection grooves12cin the process fluid plate4. This is due to the fact that the hydraulic fluid has a higher viscosity than the process fluid and therefore needs additional paths to increase speed with which it escapes into the outer groove17b.

Note that even though the figures illustrate an oblong shaped chamber5, the present disclosure could be implemented having the same advantages on a compressor having circular chamber.

FIG.4aillustrates the process plate4in a top view, the process side of the leakage diaphragm8-2i.e. the side facing the process plate4when the compressor head is assembled and the process fluid diaphragm8-1. Only the coating may be different from the two sides of the process fluid diaphragm8-1. The stipulated line inside the seal10indicates where the clamped part of the multi-layered diaphragm8cstops. Hence from the stipulated line and outwards, the multi-layered diaphragm8is clamped between the two plates3,4. The bolts used to clamp the diaphragm8between the two plates3,4may pass through bolt holes40provided both in the plates3,4and in all the diaphragms8-1.8-2and8-3.

To reduce the number of parts, the process and hydraulic fluid diaphragms8-1,8-3can be made of the same material and possibly coated different according to their use as process or hydraulic fluid diaphragms8-1,8-3. Therefore, the number of holes14,20in the two diaphragms may be the same even though not all are used in the process diaphragm.

FromFIG.4a, it is illustrated, that the first end of the process side diaphragm groove15astarts in the process side of the leakage diaphragm8-2in the non-clamped part hereof. This has the effect, that process fluid leaked through a crack in the diaphragm8-1e.g. during an intake stroke, when the leakage diaphragm8-2and the process fluid diaphragm separates a bit, can enter the process side diaphragm groove15during the subsequent discharge stroke.

The second end of the process side diaphragm groove15bis as illustrated aligned with the outer groove12bso that through the clamped part of the diaphragm8cand holes14, leaked fluid can travel through the groove15to the outer groove12b.

Note that the hatched part of the leak diaphragm8-2is the clamped part of the leak diaphragm8cand hence on this illustration when the layers of the diaphragm8-1and8-2are assembled the layers are assembled so that the stipulated lines are placed on top of each other.

FIG.4billustrates the hydraulic plate3in a top view, the hydraulic side of the leakage diaphragm8-2i.e. the side facing the hydraulic plate3when the compressor is assembled and the hydraulic fluid diaphragm8-3. Only the coating may be different from the two sides of the hydraulic fluid diaphragm8-3. As described with reference toFIG.4a, the hatched part of the leakage diaphragm8-2is the clamped part of the diaphragm8c. The hydraulic fluid side diaphragm grooves are also as described starting at a first end21ain the non-clamped part and ends aligned with the outer groove17bat its second end21b. Thereby, hydraulic fluid leaked through a crack in the hydraulic fluid diaphragm8-3can escape as described above to the hole21and outer groove17b.

It is noted that only two process sides grooves15and ten hydraulic side grooves21are illustrated. This only served the purpose of illustrating the number grooves15,21on each side of the leakage diaphragm8-3does not have to be the same. Hence,3,4,5,6-10grooves15can be used on the process side and2-20and any number therebetween of grooves21can be used without compromising the principles of the present disclosure.

FIG.5illustrates a very simplified compressor1comprising an electric motor42driving the piston35by means of a belt43. The leakage detection system of the present disclosure can be implemented on other configurations and designs of the compressor1than what is illustrated in the figures. In the circle defined by the stipulated line, the process fluid plate leakage passage13and hydraulic fluid plate leakage passage19is illustrated as being connected to process fluid leakage conductor23and hydraulic fluid leakage conductor28respectively.

The passages13,19are established in the material of the plates3,4(or upper / lower head parts if no replaceable plates are included in the compressor design) whereas the conductors23,28may be any type of piping including flexible plastic or metal pipes. The measurements systems22,27are based on the same principles and therefore only the process fluid leakage detection system22is described.

Beside the leakage conductor23, the process fluid leakage detection system22comprises a leakage valve24, leakage sensor25and leakage overpressure safety valve26.

The purpose of the overpressure safety valve26is to ensure that if the pressure in the measurement system22increases to and above a overpressure safety valve threshold, the overpressure safety valve26opens and the pressure is reduced i.e. the measurement system is protected from failure e.g. in control of the valve24. Even though not illustrated, the overpressure safety valve26may communicate with the controller9e.g. to inform the controller9, that the overpressure safety valve26has been activated.

The status of the process fluid leakage valve24is preferably determined by a timer of the controller9. Upper and lower process fluid alarm threshold pressures are defined and during a predetermined process fluid period of time, the controller9compares the pressure readings received from the sensor25with the upper and lower threshold pressures.

In an exemplary embodiment, the predetermined process fluid period of time is set to 30 minutes, the upper process fluid alarm threshold pressure is set to 0.9 bar and the lower process fluid alarm threshold pressure is set to 0.2 bar. The valve24is not opened within the 30 minutes and if the pressure in the conductor23does not exceed the lower threshold of 0.2 bar within the 30 minutes, an alarm is set. Similarly, if the pressure within the 30 minutes increases above the upper threshold of 0.9 bar, an alarm is also set.

Alternatively, the time before an alarm is triggered due to lower pressure than the lower process fluid alarm threshold can be set to several hours e.g. between 1 and 5 hours. As an example, if no pressure reading above 0.2 has been made by the sensor25for a period of 3 hours, a warning may be provided. Then, if not pressure reading above 0.2 bar has been made for a period of another 3 hours, an alarm may be provided.

Note that the first time the, the valve24change status to open, after starting up the compressor, could be initiated by a pressure reading between the two alarm thresholds i.e. 0.2 bar and 0.9 bar. The valve24could be opened e.g. in 2 seconds.

The reason for not reaching the lower threshold within the time period could be, that process fluid is leaking outside the leakage detection system. The reason for increasing the upper threshold within the time period could be, that either the seal or the diaphragm is leaking. In any case, the controller may react on the alarm by changing mode of operation preferably to perform a safe shutdown of the compressor.

Parallel to this, the leakage detection system22comprises an overpressure safety valve26. The overpressure safety valve26may be implemented as a mechanical spring-loaded relief type valve having an adjustable threshold pressure for when to open for flow through the overpressure safety valve26i.e. the overpressure safety valve would then be a normally closed valve opening at a pressure of e.g. 2 bar, 3 bar, 4 bar, 5 bar or even higher. This is advantageous in that it has the effect, that if the process fluid leak continues e.g. at each cycle of the diaphragm, the pressure in the conductor23will increase only to it reaches the predetermined overpressure safety valve threshold pressure. Hence, the overpressure safety valve26ensures safety of the process leak detection system of the diaphragm compressor.

Opening the process leak valve24in response to a pressure signal from the process leak sensor25is advantageous in that it has the effect, that it is ensured, that the process leak sensor25or process leak valve24is not failing. Hence, if the pressure continues to increase above the upper alarm threshold value, it indicates that something is wrong e.g. the gas leakage valve may be failing.

Accordingly, the diaphragm compressor1of the present disclosure is expected to leak some small quantity of process fluid during operation which is monitored by the process leak sensor25. Hence, if this pressure in the leakage conductor23is not increasing during operation including stat-up it indicates that the leakage detection system is compromised i.e. the ability to seal pressure within the leakage detection is compromised. In any event appropriate actions can be taken such as stopping the operation of the diaphragm compressor via the controller9.

Accordingly, the pressure leakage detection system22of the present disclosure is advantageous in that it is able to detect leakage from the process seal10, the diaphragm8-1and monitor if the compressor including the leakage detection system22is tight. Furthermore, the leakage detection system22and the design of seals and grooves are advantageous in that it together it constitutes a leakage detection system design that is tight and able to maintain seal integrity and seal pressure in the chambers / in the leakage detection system.

The hydraulic fluid leakage detection system27is as mentioned similar to the process leakage detection system22. With this said, since no leaking of hydraulic fluid is expected, so the control and monitoring is not completely the same. In an exemplary embodiment, the valve29may open for the first time when a pressure of e.g. 0.2 bar is reached. The valve29may be open for e.g. 2 seconds. Then a time period of e.g. 1 hour passes in which the valve29is not allowed to open. If, in this time period, the pressure reaches e.g. 0.4 bar, the valve is opened, and an alarm is activated. Typically, in this situation, the controller9will react on such alarm by initiate a safe stop of the operation of the compressor.

The leakage detection system27also comprises an overpressure safety valve31, which serves the same purpose as the overpressure safety valve26described above. The opening pressure may be different or the same as that of the overpressure safety valve26.

An advantage of the separation of two leakage detection systems described above is that the hydraulic system volume (volume in the grooves17) can be smaller which allows effective detection of a hydraulic leak due to the lack of expansion of hydraulic fluid when it leaks. The process system volume (volume in grooves12) is not as critical because the process fluid which is typically a gas expands significantly in volume upon decompression (leakage). Therefore, a larger process system volume may be preferred for process fluid leak detection.

Beside the advantage of being able to separate leakages of process fluid from hydraulic fluid and vice versa, the present disclosure is advantages in that by the above describe compressor and measurement system, the controller9is able to determine if the leakage groove systems12,17and measurement systems22,27are failing. This is at least true for the process leakage groove system12and for the process measurement system22. Failing could be understood as having a leak which is not measure by the measurement system22i.e. if e.g. the leak seal arrangement12dare leaking.

Since a certain leakage is expected via the process plate seal10, at least each time the compressor starts up, a certain pressure increase is expected in the conductor23. If no pressure increase is detected within a given period of time, this is an indication that a leak is happening which is not caught by the leak groove system12or by the measurement system22.

Similarly, since a leakage of a certain size is expected within a certain period of time, then if for some reason the pressure increase in the conductor23due to a leak increases more than expected within a certain period time, it is an indication that either the seal10or the diaphragm8-1is leaking.

An example of expected pressure increases in the conductor23caused by expected leaking process fluid is illustrated onFIG.6. With reference to the above exemplary embodiment, at time T0 the compressor is started and reaching 0.4 bar at time T1. Then valve24opens, reducing the pressure which starts to build up again. At time T2, 30 minutes has passed since last opening at time T1. At time T3, the pressure in the conductor23increases above 0.9 bar and the controller stops the compressor. If this is not the case, the pressure increases to 1.7 bar at T4, where the overpressure safety valve26opens and reduces the pressure.

Finally, in case the process leakage detection system23does not comprise a pressure sensor25, it is possible to perform an alternative leakage detection by means of a timer. Hence, a timer of the controller may be used as trigger for the opening and closing of the process fluid leakage valve e.g. every 30 minutes. In this case however, the valve opens no matter if there has been a leakage or not. The drawback of this approach is that it is not possible to determine if the system is completely sealed / tight. This is because it is expected to leak a bit of process fluid e.g. during start up and it cannot in this way be detected if this expected leakage escapes via the leakage detection system or via a leak elsewhere on the compressor. Hence it is not, as possible in the present disclosure, possible to detect a leakage trend i. e. to spot if the compressor is leaking a bit and the evolution of such leakage. The same alternative is available for the hydraulic fluid side.

From the above description it is now clear that the present disclosure relates to a leakage detection system for a diaphragm compressor1. A leakage of process fluid is not mixed with a leakage of hydraulic fluid making the leakage easier to detect compared to the situation where leaked process fluid and hydraulic fluid are mixed. Hence the present disclosure is a non-contaminated system where process fluid is not contaminated with hydraulic fluid if a leak event occurs.

A leak through a crack in a diaphragm is guided from the crack to the outer groove12b,17bvia a groove15,21in the leak diaphragm8-2to a hole14,20in the respective diaphragm8-1and / or8-2. A leak via the seal10,16will enter the inner groove12a,17aand via the connection grooves12c,17cend in the outer groove12b,17b.

From the outer groove12b,17b, the leaked fluid is guided via a leakage passage13,19to a leak measurement system22,28where the leakage is monitored by a controller. The monitoring is facilitated by a pressure sensor25,30measuring the pressure in a leak conductor23,28. The measured pressure is, preferably by the controller, compared to an expected pressure leak range defined by an upper and a lower pressure threshold. If the measured pressure is outside the expected pressure leak range, something may be wrong, and the controller would stop the operation of the compressor.

Hence, the advantages are that leaks are separated for easier measurement and it is detected if no leaks are measured and if leaks above a leak threshold is measured.