JP2016537558A - Piston compressor and method for compressing cryogenic gaseous media, especially hydrogen - Google Patents

Abstract

The present invention relates to a piston compressor (1) for compressing a cryogenic fluid medium, in particular a cryogenic fluid medium in the form of hydrogen. According to the present invention, the first gap in the circumferential direction between the first piston (31) and the inner side (300a) of the first cylinder (30) facing the first piston (31). (S) is sealed as follows by at least one seal (32) provided on the first piston (31), that is, a leakage medium (M ′) is contained in the first cylinder inner chamber ( 300) through the first gap (S) to reach the internal chamber (100) of the housing (11) and are sealed to flow around the mover (20) and in particular around the stator. In this case, the permanent magnet (P) is coated (B) for protection from the medium (M ′), in particular for protection from hydrogenation when the medium (M ′) is in the form of hydrogen. ) Is given. The invention further relates to a method for compressing a cryogenic fluid medium (M), in particular hydrogen.

Description

  The invention relates to a piston compressor according to claim 1 and a method according to claim 8 for compressing a fluid medium, in particular a gaseous, especially cryogenic medium, in particular a cryogenic medium in the form of hydrogen.

  In the context of the present invention, a cryogenic fluid medium is to be understood as a fluid medium having a temperature in particular in the range from 0K to 130K. The fluid medium here is a gaseous or liquid medium or a phase mixed medium composed of a gas phase and a liquid phase. In any case, the piston compressor according to the invention operates at a relatively high inlet side temperature, in particular up to 320K, ie an inlet side temperature in the range from 0K to 320K.

  The gas under the specified conditions is much less dense than other energy carriers. In order to store this gas effectively, it is necessary to increase the mass of the gas in a usable storage space.

  Effective storage of gas is often achieved by increasing the gas pressure. Compressed systems such as reciprocating piston compressors such as ion compressors, screw compressors or diaphragm compressors are currently used as the most frequently used methods and devices for compressing gaseous media. ing. Furthermore, methods for the compression and discharge of liquid cryogenic media are known and this method is mainly realized by a piston compressor system.

  The method and apparatus according to the superordinate concept of the present invention can be used in a natural gas station or a hydrogen compressor station, for example, as realized in a gas station.

  From German Patent No. 102006060147 as a prior art, for example, a fluid machine driven by a linear motor is known. In this machine, for example, a stator and a mover in a linear motor are connected to a gap pipe and a static machine. It is separated by a seal.

  Such compressors typically operate at a gas inlet temperature in the range of the ambient temperature of the installation site. Therefore, in the case of a compressor system to which liquid gas is supplied, it is necessary to shift the liquid to a gaseous state. The adaptation of the gas inlet temperature in the compressor takes place via an evaporator. The energy required for increasing the temperature of the medium in the evaporator is obtained, for example, by extracting heat from the surrounding environment or for each electrical heating device.

  On the other hand, a cryopump having a high discharge capacity must be supplied in liquid form. The liquid tank required for this supply is extremely uneconomical based on the limited thermal insulation and the loss of liquid hydrogen as a result of wasted boil-off gas under long residence times.

  Based on the temperature difference generated in the compressor, for example, for a piston compressor, it is structurally required to provide a length tolerance, which is accompanied by an increase in dead space. And the re-expansion of gas that is caused by a relatively large dead space means a decrease in discharge capacity.

  In a compressor without dead space (for example, an ion compressor), the crystallization temperature of the ionic liquid is limited to use at a low temperature. Further, the ion compressor requires a horizontal assembly position to maintain the liquid column.

  Furthermore, piston compressors known from the prior art are often difficult to structure with pressure tightness. Therefore, some leakage to the surrounding environment of the medium to be compressed must be considered. Of course, static seals can only tolerate a limited leak-free seal. In the case of hydrogen discharge and compression with the system disclosed in DE 102006060147, the person skilled in the art is further faced with the problem of permanent magnet hydrogenation by leaking gases.

  Based on this, the object of the invention is to provide an improved piston compressor and a corresponding method for compressing fluids (eg gaseous), in particular cryogenic media, in particular hydrogen.

  The object is solved by a piston-type compressor described in the characterizing portion of claim 1. Advantageous embodiments of the piston compressor according to the invention are described in the corresponding dependent claims and are further described in the following specification.

  A piston type compressor for compressing a cryogenic fluid medium, particularly a cryogenic fluid medium in the form of hydrogen, according to the present invention according to claim 1, wherein the piston compressor comprises a linear motor, , A stator, and a mover including a permanent magnet, the stator being configured to form a magnetic field for driving the mover, whereby the mover Reciprocates relative to the stator along a longitudinal axis extending along the axis. The piston compressor further includes a housing of the linear motor, a first cylinder of the piston compressor connected to the housing, and a first cylinder head of the first cylinder, , Defining an internal chamber in which the mover and the stator are disposed, wherein the first cylinder defines a first cylinder internal chamber starting from the internal chamber, and the first cylinder head is The medium can be introduced into the first cylinder internal chamber through the suction port, and the compressed medium can be introduced into the first cylinder through the discharge port. One cylinder internal chamber can be discharged. Further, the piston type compressor has a first piston projecting into the first cylinder inner chamber and extending along the longitudinal axis, and the first piston is joined to the mover. Thus, the first piston is reciprocated along the longitudinal axis in conjunction with the mover, wherein the first piston is connected to the first cylinder head by the first piston. The medium existing in the first cylinder inner chamber is compressed when moved in the direction. According to the invention, here, a first circumferential gap between the first piston and the inside of the first cylinder facing the first piston is provided in the first piston. Sealed by at least one seal provided, that is, the medium from the first cylinder inner chamber reaches the inner chamber of the housing through the first gap, and The permanent magnet is coated to flow around the mover and for protection from the medium, especially for hydrogenation when the medium is in the form of hydrogen. Propose that.

  That is, at least one seal provided on the first piston should seal the first cylinder interior chamber, however, usually some leakage at the seal portion cannot be avoided. The same applies to the second piston (see below).

  Preferably, the piston compressor according to the invention or the method described below is constructed or designed to compress the fluid medium. That is, the medium may be purely gaseous or may exist as a mixture of gaseous and liquid phases. Furthermore, this medium may be present as a liquid.

  According to a preferred embodiment of the piston compressor according to the invention, the aforementioned permanent magnet comprises or is made of a neodymium-iron-boron alloy.

  In general, materials for permanent magnets according to the present invention include ferrites, zinc and / or nickel and compounds with manganese, strontium ferrite, cobalt ferrite, barium ferrite, and alloys from samarium-cobalt and aluminum-nickel-cobalt. Is suitable.

  According to a further preferred embodiment of the piston compressor according to the invention, it is proposed that the permanent magnet coating is provided by a nickel-copper-nickel coating. In other words, the permanent magnet is covered with a coating in which a copper layer is laminated on a nickel layer and a nickel layer is laminated (particularly on the outermost side). The NiCuNi coating according to the invention can be produced, for example, in a galvanic manner.

  Further, the permanent magnet coating for protecting the permanent magnet may comprise one of the following substances or compounds: That is, any of aluminum oxide, tungsten, molybdenum, gold, platinum, chromium, cadmium, tin, aluminum, silicates from tungsten and molybdenum, or nickel-aluminum compounds.

  Further, the coating may be an oxide layer of a permanent magnet substrate. This oxide layer is produced in particular before hydrogenation / embrittlement. Such an oxide layer can be produced, for example, by washing an unprotected permanent magnet, residence in atmospheric oxygen, or preferably by pressing a permanent magnet in oxygen (especially of high purity).

  The total layer thickness of each coating, preferably in the direction normal to the extended surface of the coating or in the direction normal to the individual layers, is preferably in the range between 3 μm and 500 μm.

  More preferably, the internal chamber is in fluid communication with a supply path to an inlet in the first cylinder head via a first leak return line, whereby the internal chamber is in the supply path. In this case, in particular, the first leak return pipe branches from the first end of the internal chamber, and in particular, the first cylinder internal chamber Starting from the first end of the chamber.

  According to yet another preferred embodiment of the invention, it is proposed that the piston compressor comprises a second cylinder connected to the housing. By using such a second cylinder, a two-stage compression of the medium to be compressed can be performed. Preferably, the second cylinder has a second cylinder internal chamber starting from the internal chamber of the housing of the linear motor and a second cylinder head of the second cylinder, wherein the second cylinder head The cylinder head has a suction port, and the medium can be introduced into the second cylinder internal chamber through the suction port. Further, the second cylinder head has a discharge port, and the medium compressed in the second cylinder internal chamber can be discharged from the second cylinder internal chamber through the discharge port. More preferably, a second piston is provided, which projects into the second cylinder internal chamber and extends along the longitudinal axis. This second piston is also preferably joined to the mover, whereby the second piston reciprocates along the longitudinal axis in conjunction with the mover, in which case the second piston The piston is configured to compress the medium present in the second cylinder internal chamber when the second piston moves in the direction toward the second cylinder head.

  More preferably, a second gap in the circumferential direction is provided between the second piston and the inside of the second cylinder facing the second piston, and the second gap is , Is sealed as follows by at least one seal provided on the second piston, i.e. only a part of the medium from the second cylinder internal chamber (this is also referred to as leaking medium in the present invention). ) Through the second gap to reach the internal chamber of the housing and is sealed so that it also flows around the mover and in particular around the stator (see above).

  More preferably, the internal chamber is in fluid communication with a supply path to a suction port in the first cylinder head via a second leak return line, and in particular, the second leak return line is Branching off from the second end of the internal chamber, in particular the second cylinder internal chamber starts from the second end of the internal chamber. In other words, the two cylinders are provided on both sides of the linear motor, so that the medium is sucked into the internal cylinder chamber and the medium is discharged from the other cylinder inner chamber.

  Accordingly, the position of the first and / or second piston is preferably used in order to be able to influence the movement of the piston and in particular to be able to control the stroke of the first and second piston. A position detecting means for detecting is provided. Here, a sensorless method may be applied. In these methods, for example, position-specific inductance characteristics resulting from structural conditions in the vertical and horizontal directions that are the central axis of the linear motor are used. Furthermore, the method according to EP 1746718 or WO1992019038 may be applied.

  According to an embodiment of the present invention, the position detecting means includes a distance sensor connected to the first or second piston, and the distance sensor forms a first magnetic field ( The distance sensor may be formed by a magnet, for example, and a measuring element (which has a pressure-resistant rod, for example) is disposed or attached in a magnetic body that can be elastically deformed. The distance sensor is here configured such that a longitudinal magnetic field is formed in the measuring element. Furthermore, the position detecting means is configured such that a current signal can be applied by the measuring element, whereby a second magnetic field is formed around the measuring element in the radial direction. When the two magnetic fields overlap, the magnetic material is deformed, whereby a torsional wave is formed by the measuring element. This is detected by the position detecting means. The position of the piston is inferred along with the position of the distance sensor via the time difference between the current pulse and the arrival of the torsional wave.

  Furthermore, the object of the invention is solved by the method according to the invention, in particular using a piston compressor according to the invention to compress a cryogenic fluid medium, in particular a cryogenic fluid medium in the form of hydrogen. In this case, according to the present invention, the medium is compressed using at least the first piston in the first cylinder inner chamber, wherein a part of the medium (also referred to as a leaking medium) It reaches the interior chamber of the housing through the gap and flows around the mover and in particular the stator, in particular the permanent magnet is protected from the medium by the permanent magnet coating, in particular from hydrogenation and embrittlement. The

  According to a preferred embodiment of the method according to the invention, the medium compressed in the first cylinder inner chamber is discharged from the first cylinder inner chamber and a second piston is used in the second cylinder inner chamber. In this case, in particular, only a part of the medium from the second cylinder inner chamber reaches the inner chamber of the housing via the second gap, where it flows around the mover, in particular the stator. Also flows around.

  More preferably, the medium that has reached the internal chamber is returned to the inlet of the first cylinder head via the first leakage return line and / or the second leakage return line. Thereby, the internal chamber of the housing is pressure-loaded or pressurized as described above, allowing the leakage medium to return to the inlet of the first cylinder head (the first compression stage of the piston compressor).

  More preferably, as already described above, the position of the mover and the positions of the first and / or second pistons are preferably detected, and in particular, detected by the position detecting means described above. Preferably, the stroke of the first and / or the second piston is controlled such that the dead space in the first and / or second cylinder internal chamber is reduced, thereby increasing the efficiency of the piston compressor. Rises. In this case, each dead space is a volume defined by the end surface side of each piston together with the inner peripheral surface of each cylinder and the inside facing each piston of each cylinder head. When this dead space has disappeared, the piston or its end face comes into contact with each cylinder head.

  According to a particularly preferred embodiment of the method according to the invention, the first medium is supplied in liquid form to the piston compressor, typically just before being introduced into the first cylinder internal chamber. In this case, the ambient heat and / or the waste heat of the linear motor are preferably used for vaporizing the medium.

  For compression purposes, the intake temperature of the medium to be compressed is just above the corresponding intake pressure equilibrium point. In addition to the liquid supply, a gaseous cryogenic supply is also possible, in which case the medium to be compressed is conveyed from the medium source into the first cylinder internal chamber at a gaseous cryogenic temperature.

  Further features and advantages of the invention will become apparent in the following description of embodiments of the invention based on the drawings.

Partial sectional view of a piston compressor according to the present invention Further partial sectional view of the piston type compressor according to the present invention shown in FIG.

FIG. 1 shows a piston compressor 1 according to the present invention in connection with FIG. The piston compressor 1 includes a linear motor 10 having a stator and a mover 20 that can reciprocate along a longitudinal axis L by the stator. This stator interacts with the permanent magnet P of the mover 20 to generate a magnetic field, and the mover reciprocates along the longitudinal axis L by this magnetic field. In the present invention, the stator and the mover 20 of the linear motor 10 configured as a cylindrical linear motor are disposed in the housing 11 of the linear motor 10, and the housing 11 is an internal chamber 100 of the linear motor 10. Is defined. The piston compressor 1 includes a first cylinder 30 and a second cylinder 70 along the longitudinal axis L on both sides of the housing 11, and these cylinders 30, 70 are connected to the first cylinder inner chamber 300 or the second cylinder 70. Two cylinder internal chambers 700 are enclosed. These two cylinder inner chambers 300, 700 start along the longitudinal axis L from the first end 100 a or the second end 100 b of the inner chamber 100 of the housing 11. These two end portions 100a and 100b oppose each other along the longitudinal axis L.

  In the first cylinder inner chamber 300, the first piston 31 slides. Here, the first piston 31 and the first cylinder inner chamber 300 facing the first piston 31 are arranged. A circumferential gap S is formed between the inner side and the inner side, and this gap S is sealed by at least one, preferably a plurality of, in particular slit (groove) seals 32. The seal 32 is hermetically sealed in dynamic operation, but is not hermetically sealed in a static state. This type of slit-like seal 32 is characterized in particular by having separation characteristics that can occur at one point due to a parallel, skewed or three-dimensional separation section with respect to the cylindrical axis of the seal. The seal 32 is configured with such separation characteristics, or separation characteristics occur after formation of the seal 32.

  In a similar manner, a second piston 71 slides in the second cylinder inner chamber 700, and this second piston 71 also has at least one, preferably a plurality of particularly slit-shaped seals 72 together with the second piston 71. The second piston 71 abuts against the inner surface of the second cylinder 70, whereby a second circumferential gap S ′ between the second piston 71 and the inner surface 700 a of the second cylinder 70 is formed. Sealed.

  The two pistons 31 and 71 of the compression stage thus formed reciprocate along the longitudinal axis L between the turning points in the two cylinders 30 and 70 during operation, and the cylindrical linear motor 10 The piston rod or the device on the mover 20 is centered and restrained. Here, one centering adapter 21, 23 is placed on each free end of the mover 20. Each of these centering adapters 21 and 23 has a screw thread. The opposing rings 22, 24 are provided with corresponding opposing threads, and are screwed to the corresponding centering adapters 21, 23, respectively. In this case, the centering adapters 21 and 23 are screwed to the mover 20 on the one hand, and the pistons 31 and 71 are clamped between the centering adapters 21 and 23 and the opposing rings 22 and 24, thereby moving. A firm joint is formed between the child 20 and the pistons 31 and 71.

  Here, the second piston 71 is divided into two parts, and has two sections 710 and 720. Here, the first section 710 is fixed to the movable element 20, and in detail, is fixed through the centering adapter 23 and the corresponding counter ring 24, and the second section of the second piston 71 is further fixed. 720 refers from the internal chamber 100 to the second cylinder 70, where the medium M sucked into the second cylinder internal chamber 700 is compressed.

  The two cylinders 30 and 70 are sealed on the end face side by the first or second cylinder heads 40 and 80, respectively, through which the medium M to be compressed is introduced into the cylinders 30 and 70, Furthermore, it discharges | releases from each cylinder compression part.

  Further, the cylinders 30 and 70 are respectively centered with respect to each flange 12 via the centering surface of the flange 12, and in this case, each flange 12 is also centered with respect to the housing 11 of the linear motor 10 via the centering surface. The two flanges 12 are respectively screwed to the housing 11 on the end face side, whereby the cylinders 30 and 70 are also fixed to the housing 11. In this case, the housing 11 or the cylinders 30, 70 are sealed against the surrounding environment via one static seal in the form of O-rings 101, 102 arranged between the flange 12 and the housing 11, respectively. As a result, the housing 11 becomes pressure-resistant and airtight. The linear motor 10 itself is fixed to each installation surface via the flange mount 13 of the housing 11.

  Furthermore, each piston 31, 71 has an annular guide belt 33, 73 in the circumferential direction at each piston for receiving radial stress. As already described, under the swinging motion of the two pistons 31 and 71, a part of the medium M existing in each of the cylinder inner chambers 300 and 700 passes through the gaps S and S ′ described above to the housing 11. Can reach into the internal chamber 100. In this case, this seal leak is returned to the inlet side of the piston compressor 1 via first and second leak return lines 51, 52 in the form of conduits. In this case, the first leak return pipe 51 branches off from the first end 100 a of the internal chamber 100 and is in fluid communication with the supply path 61. The medium M to be compressed can be supplied to the suction port 41 of the first cylinder head 40 via the supply path 61. This suction port 41 can be closed via a valve in the form of a suction valve 410. The stator and the movable element 20 of the linear motor 10 are loaded with a pressure corresponding to the pressure on the inlet side of the piston compressor 1 at the suction port 41 by the pressure-tight sealing structure and the above-described leakage return configuration. The leakage gas M 'flows correspondingly around the stator and the mover 20, and heat is transferred to the leakage gas M' during operation. In the first cylinder inner chamber 300, the medium M compressed using the first piston 31 is discharged through the discharge port 42 of the first cylinder head 40, and the discharge port 42 is closed by the discharge valve 420. Is possible.

  The first cylinder head 40 including the intake and discharge valves 410 and 420 is disposed at one end of the first cylinder 30 and is connected to the cylinder via a coupling ring (union nut) of the first cylinder 30. Screw fixed. Similarly, the opposite end of the second cylinder 70 of the second cylinder head 80 is also fixed by a coupling ring. In this case, the second cylinder head 80 also has a suction port 81 and a discharge port 82, which can be closed using a suction valve 810 or a discharge valve 820. From the discharge port 42 of the first cylinder head 40, a connection pipe (not shown) is connected to the suction port 81 of the second cylinder head 80. In this case, the supply path 61 and this connection pipe are Preferably each is heat-insulated.

  When compressing the hydrogen-containing medium M, the permanent magnet P of the linear motor 10 must be protected from hydrogen molecules. The high-performance magnet used in the high-performance linear motor 10 is preferably made of a compound containing a neodymium-iron-boron element. In this case, neodymium is a rare earth metal. Rare earths are applied to metal hydrides for hydrogen storage. The adsorption action utilized in this case and the subsequent deposition of hydrogen atoms in the metal lattice are not particularly desirable in the linear motor 10 and may permanently destroy the permanent magnet P. Protecting the permanent magnet P from such hydrogen deposition is preferably done by a nickel-copper-nickel coating of the permanent magnet P.

  The positioning of the two pistons 31, 71 in the corresponding cylinder interior chamber 300, 700 is preferably performed via the position detection means 90. This position detection means 90 may be an appropriate distance measurement system or a sensorless control system. As a result, according to the drive invention using the cylindrical linear motor 10, it is possible to perform a high degree of dynamic intervention in the course of movement of the piston compressor 1 during the compression process, and thus the piston compressor 1 can be changed. It is possible to perform stroke adaptation adjustment according to the length change caused by the configuration and thermal expansion. In addition, the adjustment of the piston stroke adjustment of the pistons 31 and 71 also realizes the minimization of the dead space. This also has a positive effect on the discharge capacity of the piston compressor 1.

  The compression of the gaseous cryogenic medium M, particularly the medium M in the form of hydrogen, using the piston compressor 1 according to the present invention is preferably carried out as follows. That is, the hydrogen M is sucked into the first compression chamber or the first cylinder inner chamber 300 through the supply passage 61 which is suitably insulated from the hydrogen supply portion, through the suction valve 410 of the first cylinder head 40. In the next cycle, the sucked-in hydrogen M is compressed by the first piston 31 (in this case, the first piston 31 moves toward the first cylinder head 40). It is discharged through the discharge valve 410. The discharged and compressed gaseous medium M is sucked in through the suction valve 810 of the second cylinder head 80 of the second compression stage via the above-mentioned connecting pipe which is preferably insulated, and continues. Compressed by the corresponding movement of the second piston 71 in the second cylinder internal chamber 700 and discharged through the discharge valve 820. For hydrogen, this increase in pressure again leads to an increase in density. Based on the configuration, the first stage compression and the second stage inhalation are performed reversibly at the same time.

  The compression at the low temperature level according to the present invention results in a slight enthalpy difference of the medium M from the inhaled state to the compressed state compared to a higher temperature process using an equivalent pressure potential (eg, gas at room temperature). That means the same way. This reduces the amount of work required for compression, which appears as an extreme reduction in power demand.

  The compression at a low temperature level according to the present invention eliminates the need for heat exchange in the intervening path. This is because the temperature of the intervening path remains below the ambient temperature normally detected at the place of use, following the temperature rise based on the compression process by the first compression stage.

  The compression at the cold level according to the invention is further associated with a high specific density of the medium M, whereby a relatively particularly high discharge capacity is achieved for a pure gas compressor.

  The preferred fully enclosed structure of the piston compressor system 1 eliminates the need for dynamic sealing of the movable member with respect to the surrounding environment. This makes it possible to take advantage of the technical advantages of known static seals.

  Furthermore, the completely sealed structure of the piston type compressor system 1 can also contain contamination of the housing 11 by ambient air. This is achieved by the housing 11 being always loaded with an excess pressure corresponding to the inlet pressure of the first compression stage. This allows the gas leakage medium M 'of the dynamic piston seals 32, 72 to return into the intake pipe or cylinder internal chamber 300, 700.

  The above-described device for fixing the piston in the linear motor piston rod or the so-called movable element 20 enables easy replacement of the two pistons 31 and 71 in maintenance. Furthermore, simultaneously with the adaptation of the cylinder diameter, it is possible to change the piston diameter in order to obtain a higher final compression pressure or to improve the discharge capacity.

  In the compression station 1 supplied in a liquid state, it is also possible to absorb evaporative gas generated in the tank as a result of heat input and reuse it for compression.

  Despite the high discharge capacity achievable due to the process of the compressor system 1, the required space is maintained slightly compared to conventional gas compressor systems.

  The above-described compressor system 1 can be advantageously operated both in the horizontal direction and in the vertical direction.

  According to one embodiment of the piston compressor 1 for hydrogen compression, it is proposed that the first piston 31 has a diameter of 42 mm and the second piston 71 has a diameter of 16 mm. The frequency of the piston motion is preferably 10 Hz in this case, and the mass flow rate of the working medium M is preferably 10 kg / h, and the inertial force or inertial mass (moving element 20, centering adapters 21, 23, opposing) The combined stress from the individual oscillating inertia forces of the oscillating members such as the rings 22 and 24, the pistons 31 and 71, the seals 32 and 72, and the guide bands 33 and 73) is preferably 50 kg. The stroke of the pistons 31 and 71 is preferably 120 mm. Piston motion preferably fills a sine function. The resulting compression force is 10 kN, and the footprint of the compressor 1, that is, the projected area in plan view, is about 2.5 m × 1 m. The maximum capacity that can be achieved by the linear motor 10 is 13.8 kN, and the maximum speed that can be achieved by the linear motor 10 is 4.1 m / s. The rated output of the linear motor 10 is 26.6 kW.

  Hydrogen is preferably supplied and compressed in the first cylinder inner chamber 300 at a temperature of 60K and a pressure of 6 bar in this case and discharged at a temperature of 184K and a pressure of 133 bar and compressed in the second cylinder inner chamber 700. The Here it is compressed again and discharged at a temperature of 288 K and a pressure of 600 bar.

DESCRIPTION OF SYMBOLS 1 Piston type compressor 10 Linear motor 11 Housing 12 Flange 13 Flange 20 Movable element 21 Centering adapter 22 Opposed ring 23 Centering adapter 24 Opposed ring 30 1st cylinder 31 1st piston 32 Seal 33 Guide belt 40 1st cylinder head 41 Suction Port 42 Discharge Port 51 First Leak Return Pipe Line 52 Second Leak Return Pipe Line 61 Supply Path 70 Second Cylinder 71 Second Piston 72 Seal 73 Guide Belt 80 Second Cylinder Head 81 Suction Port 82 Discharge port 90 Position detection means 91 Distance sensor 92 Measuring element 100 Internal chamber 100a First end portion 100b Second end portion 101 O-ring 102 O-ring 300 First cylinder internal chamber 300a Inner surface 400 Housing 410 Lube (inlet valve)
420 Valve (Discharge valve)
700 Second cylinder inner chamber 700a Inner surface 810 Valve (suction valve)
820 Valve (Discharge valve)
M medium (eg hydrogen)
M 'Leakage medium P Permanent magnet (mover)
B coating L longitudinal axis S first gap S 'second gap

Claims (12)

A piston compressor that compresses a cryogenic fluid medium, in particular a cryogenic fluid medium in the form of hydrogen, wherein the piston compressor is
A linear motor (10);
A housing (11) of the linear motor (10);
A first cylinder (30) connected to the housing (11);
A first cylinder head (40) of the first cylinder (30);
A first piston (31),
The linear motor (10) has a stator and a mover (20) including a permanent magnet (P), and the stator forms a magnetic field for driving the mover (20). So that the mover (20) is relative to the stator along a longitudinal axis (L) extending along the mover (20). Reciprocating,
The housing (11) defines an internal chamber (100) in which the mover (20) and the stator are disposed,
The first cylinder (30) defines a first cylinder inner chamber (300) starting from the inner chamber (100);
The first cylinder head (40) has a suction port (41) and a discharge port (42), and the medium (M) is passed through the suction port (41) to the first cylinder internal chamber. (300) can be introduced, and the compressed medium (M) can be discharged from the first cylinder inner chamber (300) through the discharge port (42).
The first piston (31) protrudes into the first cylinder inner chamber (300), extends along the longitudinal axis (L), and is joined to the mover (20). Thus, the first piston (31) reciprocates along the longitudinal axis (L) in conjunction with the mover (20). At this time, the first piston (31) When one piston (31) moves in the direction of the first cylinder head (40), the medium (M) existing in the first cylinder inner chamber (300) is compressed. In the piston type compressor,
A first circumferential gap (S) between the first piston (31) and the inner surface (300a) of the first cylinder (30) facing the first piston (31), It is sealed as follows by at least one seal (32) provided on the first piston (31), that is, the medium (M ′) from the first cylinder inner chamber (300) is Is sealed to such an extent that it reaches the internal chamber (100) of the housing (11) through the first gap (S) and flows around the mover (20),
For protection from the medium (M ′), in particular for protection from hydrogenation when the medium (M ′) is in the form of hydrogen, a coating (B) is applied to the permanent magnet (P). A piston type compressor characterized by that. The permanent magnet (P) is neodymium has an alloy containing iron and boron, in particular Nd 2 _Fe 14 has a composition of _B, the piston type compressor according to claim 1. Said coating (B) comprises the following coatings:
A nickel-copper-nickel coating, the coating comprising at least one nickel layer, a laminated copper layer, a laminated nickel layer, and in particular the total coating thickness is in the range of 3 μm to 500 μm Coating,
A coating containing aluminum oxide, tungsten, molybdenum, gold, platinum, chromium, cadmium, tin, aluminum, tungsten and molybdenum, or a nickel-aluminum compound,
Or
A coating comprising at least one oxide of a permanent magnet material, preferably a coating formed by contacting oxygen with a permanent magnet;
The piston type compressor according to claim 1 or 2.   The internal chamber (100) is in fluid communication with a supply path (61) to a suction port (41) in the first cylinder head (40) via a first leak return pipe (51). Thereby, the internal chamber (100) is pressurized with a pressure corresponding to the pressure in the supply passage (61), and in this case, in particular, the first leak return pipe (51) is connected to the internal chamber (100). ) From the first end (100a), in particular the first cylinder inner chamber (300) starts from the first end (100a) of the inner chamber (100), The piston type compressor according to any one of claims 1 to 3. The piston compressor (1) further includes:
A second cylinder (70) connected to the housing (11);
A second cylinder head (80) of the second cylinder (70);
A second piston (71),
The second cylinder (70) defines a second cylinder inner chamber (700) starting from the inner chamber (100);
The second cylinder head (80) has a suction port (81) and a discharge port (82), and the medium (M) passes through the suction port (81) and the medium (M) is in the second cylinder internal chamber. (700) and the compressed medium (M) can be discharged from the second cylinder internal chamber (700) via the discharge port (82);
The second piston (71) protrudes into the second cylinder inner chamber (700), extends along the longitudinal axis (L), and is coupled to the mover (20). Accordingly, the second piston (71) reciprocates along the longitudinal axis (L) in conjunction with the mover (20). At this time, the second piston (71) When the second piston (71) moves in the direction of the second cylinder head (80), the medium (M) existing in the second cylinder inner chamber (700) is compressed. And, more particularly, a second circumferential gap between the second piston (71) and the inner surface (700a) of the second cylinder (70) facing the second piston (71) ( S ′) is provided on the second piston (71). The at least one seal (72) is sealed as follows, that is, the medium (M ′) from the second cylinder inner chamber (700) is in contact with the second gap (S ′). The piston according to any one of claims 1 to 4, wherein the piston is sealed to such an extent that it reaches the internal chamber (100) of the housing (11) through and flows around the mover (20). Type compressor.   The internal chamber (100) is in fluid communication with a supply path (61) to an inlet (41) in the first cylinder head (40) via a second leak return pipe (52). In particular, the second leak return line (52) branches off from the second end (100b) of the internal chamber (100), and in particular the second cylinder internal chamber (700) 6. A piston compressor according to claim 4 or 5, starting from the second end (100b) of an internal chamber (100).   Position detecting means (90) for detecting the position of the first and / or the second piston (31, 71) is provided, and in particular, the position detecting means (90) is the first or the second. A distance sensor (91) connected to the pistons (31, 71), the distance sensor (91) forms a first magnetic field and the reciprocating motion of the mover (20). And is configured to move along a measuring element (92) that moves along the longitudinal axis (L) within the internal chamber (100), the measuring element (92) being elastically deformable. The position detecting means (90) generates a second magnetic field around the second measuring element (92) by applying a current signal to the second measuring element (92). Is configured to be formed and thereby A torsional wave is formed in the elastically deformable magnetic body based on the interaction of two magnetic fields. In this case, the position detecting means (90) detects the torsional wave and applies the current signal and the torsional wave. The piston type compressor according to any one of claims 1 to 6, wherein the piston type compressor is configured to detect the position based on a time difference from detection of a wave. A method for compressing a cryogenic fluid medium, in particular a cryogenic fluid medium in the form of hydrogen, using the piston compressor (1) according to any one of claims 1 to 7,
The medium (M) is compressed using at least a first piston (31) in at least a first cylinder inner chamber (300), wherein a part of the medium (M ′) is a first gap ( Through S) to the interior chamber (100) of the housing (11) and flow around the mover (20), in particular the permanent magnet (P) by the coating (B) of the permanent magnet (P) A method characterized in that it is protected from said medium (M '), in particular from hydrogenation when said medium (M') is in the form of hydrogen.   The medium (M) compressed in the first cylinder inner chamber (300) is discharged from the first cylinder inner chamber (300), and the second piston in the second cylinder inner chamber (700). (71), in which case a part of the medium (M ′) from the second cylinder internal chamber (700) in particular in the housing (11) via the second gap (S ′). The method according to claim 8, wherein the method reaches into the inner chamber (100) and flows around the mover (20).   The medium (M ′) that has reached the internal chamber (100) passes through the first cylinder head (40) via the first leakage return line (51) and / or the second leakage return line (52). 10. The method according to claim 8 or 9, wherein the inlet is returned to the inlet (41).   The position of the mover (20) and the position of the first and / or second pistons (31, 71) are detected, especially in the first and / or second cylinder internal chambers (300, 700). 11. The method according to claim 8, wherein a stroke of the first and / or the second piston is controlled such that a dead space is reduced.   The medium (M) is supplied in liquid form to the piston compressor (1) and is transferred to a gaseous state before being introduced into the first cylinder internal chamber (300), in particular 12. The method according to any one of claims 8 to 11, wherein ambient heat and / or waste heat of the linear motor (10) are used for vaporizing the medium.

Images