AU2006274301A1

AU2006274301A1 - Compressor, in particular piston compressor

Info

Publication number: AU2006274301A1
Application number: AU2006274301A
Authority: AU
Inventors: Robert Adler
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2005-07-26
Filing date: 2006-07-04
Publication date: 2007-02-01
Also published as: JP5065267B2; KR20080025059A; JP2009503321A; WO2007012384A1; CN101233318B; US20080199327A1; DE102005034907A1; EP1907701B1; CN101233318A; EP1907701A1

Description

ox 259. HynGton. VIc 3444 AUSTRALIRA www.ocodemvXL.com * InfoOocademyXL.com o a business of Tonco Sorvicos Pty Ltd RABN 79 892 315 097 Free M 1800637640 Intrdr +61 3 54 232558 Fax a 03 54 232677 Inter 8 +61 3 54 232677 TRANSLATION VERIFICATION CERTIFICATE This is to certify that the attached document is an English translation of the -- German-language Patent Application PCTIEP2006/006520 and Academy Translations declare that the translation thereof is to the best of their knowledge and ability true and correct. Rcademy Translaotions PO Box 259, Kyneton VIC 3444 AUSTRAUA January 17, 2008 Date StamplSignature: AT Ref.: ddc-2061 Multilingual Technical Documentation Translation from German of PCTAppolication PCT/EP2006/006520 Compressor, especially piston compressor 5 The invention relates to a compressor, especially a piston compressor, for compressing a gaseous medium, having a low pressure stage for compressing the medium from an inlet 10 pressure to an intermediate pressure, and having a high pressure stage for compressing the medium from the intermediate pressure to a high pressure. In compressors for gaseous media that are designed as piston 15 compressors, the stage pressure ratio is determined by the cylinder dimensions. For a piston compressor with two stages, comprising a low pressure stage and a high pressure stage, and a stage pressure ratio in the range of 17, for example, a medium can be compressed in the low pressure stage, which has 20 a stage pressure ratio of 17, from an inlet pressure of 1 bar to an intermediate pressure of 17 bar, and in the high pressure stage, which has a stage pressure ratio of 17.6, to a high pressure of 300 bar. 25 Piston compressors of this type are designed for a specific inlet pressure, whereby the inlet pressure of the medium can vary only within narrow limits. If a piston compressor according to the state of the art that is designed for an inlet pressure of 1 bar is operated with an inlet pressure of 30 5 bar, an intermediate pressure of 85 bar would result after the low pressure stage, with a stage pressure ratio of 17, which would cause the low pressure stage to overheat. From DE 199 33 989 Al, a two-stage piston compressor is known 35 that is suitable for different inlet pressures. Separate drives are provided for the low pressure stage and the high 2 pressure stage in order to accomplish this. A two-stage piston compressor of this type, with one drive for the low pressure stage and a separate drive for the high pressure stage, however, requires a great deal of effort to build. 5 The object of the present invention is to provide a compressor of the type indicated above that is suitable for different inlet pressures, and can be built with little effort. 10 This object is achieved according to the invention in that a compensating volume with an adjustable dead volume is connected upstream of the high pressure stage. With a compensating volume of this type, connected upstream of the high pressure stage, it is possible to provide an adjustable 15 dead volume for the high pressure stage in a simple manner. During the compression cycle of the low pressure stage, gaseous medium is partially fed into the compensating volume. When the medium is then fed from the compensating volume into the high pressure stage during the next intake cycle of the 20 high pressure stage, the gaseous medium expands adiabatically and thereby cools to below the inlet temperature of the low pressure stage. With this type of compensating volume, the inlet volume of the high pressure stage can thus be modified in a simple manner, while the compressor is also 25 simultaneously additionally cooled. This makes it possible to operate the compressor with different inlet pressures in a simple manner, while preventing the compressor from overheating. 30 It is especially advantageous if, according to an embodiment of the invention, the dead volume formed by the compensating volume can be adjusted depending on the inlet pressure. This allows the compensating volume to be used to control the dead volume of the high pressure stage, depending on the inlet 35 pressure, with minimal effort.

3 It is especially advantageous if the compensating volume is set to minimum dead volume for the maximum inlet pressure, and can be adjusted in the direction of maximum dead volume as the inlet pressure decreases. This means that, as the inlet 5 pressure falls, the additional cooling effect from the compensating volume increases in a simple manner. As the inlet pressure decreases, the stage pressure ratio of the high pressure stage increases, while the thermal load on the compressor simultaneously increases. Through a compensating 10 volume that is connected to the high pressure stage and forms a dead volume for the high pressure stage, the cooling effect of which increases due to the enlargement of the dead volume as the inlet pressure decreases, the compressor temperature can be lowered in a simple manner for a compressor that is 15 used with different inlet pressures. According to a preferred design of the invention, the cylinder is conveniently designed as a staged piston with a first control surface that is located in the compensating volume, 20 and is subjected to the intermediate pressure, and features a second control surface that is subjected to the inlet pressure. With a cylinder of this type, designed as a staged piston, by selecting the dimensions of the first and second control surfaces appropriately, the cylinder can, in a simple 25 manner, be acted upon in the direction of the minimum dead volume at maximum inlet pressure, and in the direction of maximum dead volume with decreasing inlet pressure. According to a further development of the invention, the 30 compensating volume is provided with a cooling mechanism, whereby the medium located in the compensating volume can be cooled in a simple manner, and thus the cooling effect from the compensating volume can be further increased. 35 According to a preferred embodiment of the invention, the cooling mechanism comprises cooling fins located on the 4 housing, whereby a cooling mechanism for the compensating volume can be manufactured with little effort. According to an advantageous embodiment of the invention, the 5 compressor features a piston that can be moved axially in a housing, which can be hydraulically driven. The lower pressure stage conveniently includes a first pressure chamber and a second pressure chamber, through which 10 the piston actuates two pressure chambers in the low pressure stage. With the use of two pressure chambers, pulsations in the pressure lines can be reduced with little additional space requirement. 15 According to a further development of the invention, the high pressure stage includes a first pressure chamber and a second pressure chamber, through which the piston actuates two pressure chambers in the high pressure stage. With the use of two pressure chambers, pulsations in the pressure lines can be 20 reduced with little additional space requirement. The compressor can be cooled in the area of the low pressure stage and the high pressure stage in a simple manner if an external cooling system is provided on the housing. 25 For improved cooling, an internal cooling system is conveniently provided for the piston. The piston is hereby advantageously provided with at least one 30 axial bore that is connected to a drive pressure chamber. The piston can thus be internally cooled in a simple manner by the hydraulic pressure medium that drives the compressor. When the compressor is built with a high pressure stage with 35 two pressure chambers, it is advantageous if each pressure chamber in the high pressure stage has a compensating volume.

5 It is especially advantageous if a compressor is used to compress hydrogen, especially hydrogen at a hydrogen fuelling station. 5 Additional advantages and details of the invention are clarified in more detail in the application example shown in the schematic illustrations. Shown are: Figure 1 an axial cross section of a compressor 10 according to the invention, and Figure 2 a detail from Figure 1, shown enlarged. Figure 1 shows an axial cross section of a compressor designed 15 according to the invention as a linear piston compressor. The piston compressor 1 features an axially moveable, staged piston 4 in a housing bore 2 of a housing 3, whereby a low pressure stage 5 and a high pressure stage 6 are formed 20 between the piston 4 and the housing bore 2. The high pressure stage 6 is formed in the middle area of the piston compressor 1, and features two pressure chambers 6a, 6b, which are formed between a sealing element 7 in the middle 25 area of the housing 3 and the piston 4. For this purpose, piston sections 8a, 8b are located in the area of the diameter transition on the staged piston 4, whereby the pressure chambers 6a, 6b of the high pressure stage 6 are formed in the area of the increased diameter of the piston 4. In the 30 position shown, where the piston 4 is acted upon to the right in Figure 1, the left pressure chamber 6a has minimal displacement body volume, and the right pressure chamber 6b has maximal displacement body volume. 35 The low pressure stage 5 is formed on both sides of the high pressure stage 6 in the area of the decreased diameter of the 6 piston 4, and features two pressure chambers Sa, 5b that are formed between the housing bore 3 and the piston sections 8a, 8b located on the piston 4 in the area of the decreased diameter of the piston 4. 5 In the position of the piston 4 shown, the left pressure chamber 5a has maximal displacement body volume, and the right pressure chamber 5b has minimal displacement body volume. 10 The piston compressor 1 can be hydraulically driven, whereby hydraulically pressurisable drive pressure chambers 9a, 9b are formed on the piston 4 on the outer areas, adjacent to the low pressure stage 5. In the position of the piston rod shown, the drive pressure chamber 9a is acted upon by a hydraulic 15 pressure medium. When the drive pressure chamber 9b is acted upon, the piston rod 4 is driven to the left as depicted in Figure 1. To control the piston compressor, the pressure chambers 5a, 5b 20 of the low pressure stage 5 are each provided with a low pressure inlet valve 10a, 10b, and a low pressure pressure valve lla, llb. The pressure chambers 6a, 6b of the high pressure stage 6 are each similarly provided with a high pressure inlet valve and a high pressure pressure valve, 25 whereby only the high pressure inlet valve 12a and high pressure pressure valve 13a on the pressure chamber 6a are shown in Figure 1. In the area of the low pressure stage 5 and the high pressure 30 stage 6, on the outer perimeter of the housing 2, an external cooling system 15a, 15b is provided. For additional cooling of the piston compressor, the piston 4 has axial bores 16a, 16b, designed as blind holes, which are 35 connected to the drive pressure chambers 9a, 9b, by means of 7 which the pressure medium that drives the piston compressor 1 acts to internally cool the piston compressor 1. In addition, the piston compressor 1 is provided with a 5 displacement measurement system 17. According to the invention, a compensating volume 20a, 20b with an adjustable dead volume is connected upstream of each pressure chamber 6a, 6b of the high pressure stage. 10 In figures 1 and 2, the compensating volume 20a connected upstream of the pressure chamber Ga is shown in an axial cross section. The compensating volume 20b connected to the pressure chamber 6b is of identical construction. 15 The compensating volume 20a is designed as a compensating cylinder 21, which features an axially movable cylinder 23 in a housing bore 28 of a housing 22, whereby the adjustable dead volume formed by the compensating volume 20a is formed between 20 the housing bore 28 of the housing 22 and the cylinder 23, which is connected to the inlet of the pressure chamber Ga via a line 26, in particular to the connecting line between the pressure chamber 5a of the low pressure stage 5 and the pressure chamber Ga of the high pressure stage 6, downstream 25 of the high pressure inlet valve 12a of pressure chamber 6a of the high pressure stage 6. The cylinder 23 is designed as a staged piston, and features a first control surface 24 on a front side that is located in the compensating volume 20a, which is subjected to the intermediate pressure in the 30 compensating volume, generated by the low pressure side. On the opposite face of the cylinder 23, a second control surface 25 is formed that is subjected to the inlet pressure of the low pressure stage. The second control surface 25 is larger than the first control surface 24. 35 8 By adjusting the cylinder 23 appropriately in the housing bore 28, the compensating volume 20a thus forms an adjustable dead volume for the pressure chamber 6a of the high pressure stage 6. 5 A cooling mechanism 27 is located on the housing 22 in the area of the compensating volume 20a, which is formed, for example, by cooling fins located on the outside perimeter of the housing 22. 10 In the position shown, with minimal inlet pressure of the piston compressor 1, the compensating volume 20a has a maximal dead volume with the cylinder 23 extended as shown in Figure 2. With increasing inlet pressure of the low pressure stage 5 15 acting on the second control surface 25 of the cylinder 23 formed as a staged piston, the cylinder 23 is acted upon from below as shown in Figure 2, whereby the compensating volume 20a is acted upon in the direction of minimal dead volume at maximal inlet pressure of the piston compressor 1. 20 When the piston compressor 1 is in operation, after the inlet cycle in the compression cycle, a gaseous medium is fed from the pressure chamber 5a of the low pressure stage 5 via the pressure valve 11a and the inlet valve 13a into the pressure 25 chamber Ga of the high pressure stage 6, which is in the inlet cycle. Through the connection of the compensating volume 20a to the connecting line that leads from the low pressure stage 5 to the high pressure stage 6, downstream of the high pressure inlet valve 13a of the high pressure stage 6, the 30 medium compressed by the low pressure stage 5 to the intermediate pressure is also fed into the compensating volume 20a, and thus into the adjustable dead volume, and is cooled by the cooling mechanism 27. During the next inlet cycle of the high pressure stage 6, whereby the medium is drawn in from 35 the compensating volume 20a to the pressure chamber 6a of the high pressure stage 6, the gaseous medium expands 9 adiabatically from the compensating volume 20a that forms the dead volume, and thereby cools to below the inlet temperature. With the compensating volume 20a that is controlled depending 5 on the inlet pressure, it is possible to modify the inlet volume of the high pressure stage 6, and thus to operate the compressor at different inlet pressures, whereby the additional cooling of the medium via the compensating volume 20a and especially the cooling mechanism 27 can reduce the 10 temperature of the compressor, especially after the low pressure stage 5 with decreasing inlet pressure, whereby the stage pressure ratio and thus the thermal load on the high pressure stage 6 increases.

Claims

1. Compressor, especially piston compressor, for compressing a gaseous medium, having a low pressure stage for 5 compressing the medium from an inlet pressure to an intermediate pressure, and having a high pressure stage for compressing the medium from the intermediate pressure to a high pressure, characterised in that a compensating volume (20a; 20b) with an adjustable dead volume is 10 connected upstream of the high pressure stage (6).

2. Compressor as in claim 1, characterised in that the dead volume formed by the compensating volume (20a; 20b) can be adjusted depending on the inlet pressure. 15

3. Compressor as in claim 2, characterised in that the compensating volume (20a; 20b) is set to minimal dead volume at maximal inlet pressure, and can be adjusted in the direction of maximal dead volume with decreasing inlet 20 pressure.

4. Compressor as in one of the claims 1 through 3, characterised in that the compensating volume (20a; 20b) is designed as a compensating cylinder (21) that features 25 a cylinder (23) that can be moved in a housing (22).

5. Compressor as in claim 4, characterised in that the cylinder (23) is provided with a first control surface (24) as a staged piston, which is located in the 30 compensating volume (20a; 20b) and is subjected to the intermediate pressure, and features a second control surface (25) that is subjected to the line pressure (control surface on the upper end) (automatic increase of the dead volume with decreasing inlet pressure). 35 11ii

6. Compressor as in one of the claims 1 through 5, characterised in that the compensating volume (20a; 20b) is provided with a cooling mechanism (27). 5

7. Compressor as in claim 6, characterised in that the cooling mechanism (27) is formed by cooling fins located on the housing (22).

8. Compressor as in one of the claims 1 through 7, 10 characterised in that the compressor features a piston (4) that is axially movable in a housing (3) and can be hydraulically driven.

9. Compressor as in one of the claims 1 through 8, 15 characterised in that the low pressure stage (5) features a first pressure chamber (5a) and a second pressure chamber (5b).

10. Compressor as in one of the claims 1 through 9, 20 characterised in that the high pressure stage (6) features a first pressure chamber (6a) and a second pressure chamber (6b).

11. Compressor as in one of the claims 1 through 10, 25 characterised in that an external cooling system (15a; 15b) is provided on the housing (3).

12. Compressor as in one of the claims 8 through 11, characterised in that an internal cooling system is 30 provided for the piston (4).

13. Compressor as in claim 12, characterised in that the piston (4) is provided with at least one axial bore (16a; 16b) that is connected to a drive pressure chamber (9a; 35 9b). 12

14. Compressor as in one of the claims 10 through 13, characterised in that each pressure chamber (6a; 6b) of the high pressure stage (6) is connected to a compensating volume (20a; 20b). 5

15. Use of a compressor according to one of the preceding claims for compressing hydrogen, especially at a hydrogen fuelling station.