AIR DRYING AND PURIFICATION SYSTEM

Abstract: An air drying and purification system for compressed air from a compressor is disclosed. The air drying and purification system comprises a separator chamber for at least partially drying and purifying compressed air from the compressor by separating moisture and entrained particulate material and other contaminants from the compressed air. The separator chamber has an inlet for compressed air; a contact surface facing the inlet and forming an impact zone for separating moisture and entrained particulates and other contaminants from compressed air entering the separator chamber via the inlet; an outlet for at least partially dried and purified compressed air; and an adjustable valve member for controlling the flow of compressed air from the separator chamber via the outlet.

Description: AIR DRYING AND PURIFICATION SYSTEM The present invention relates to an air drying and purification system for compressed air and to a compressor incorporating the air drying and purification system. The term "compressor" is understood herein to include oil-free and oil compressors. According to the present invention there is provided an air drying and purification system for compressed air from a compressor, the system comprising, a separator chamber for at least partially drying and purifying compressed air from the compressor by separating moisture and entrained particulate material and other contaminants from the compressed air, the separator chamber having: (i) an inlet for compressed air; (ii) a contact surface facing the inlet and forming an impact zone for compressed air entering the separator chamber via the inlet; (iii) an outlet for at least partially dried and purified compressed air; and (iv) an adjustable valve member for controlling the flow of compressed air from the separator chamber via the outlet. The impact zone defined by the contact section enables effective separation of water vapour and entrained particulate material and other contaminants from the compressed air. It is noted that the term "contaminants" may include oil vapour. The adjustable valve member enables effective control of the pressure conditions within the separator chamber. In particular, the valve member enables adjustment of the flow of compressed air through the separator chamber to be matched to that of a given compressor output to minimise the pressure drop between the inlet and the outlet of the separator chamber. It is preferred that the separator chamber comprises a vertically disposed cylindrical side wall and upper and lower end walls. It is preferred particularly that the compressed air inlet be located in an upper section of the side wall. It is preferred that the compressed air outlet be in the upper end wall. It is preferred that the separator chamber comprises a cylindrical partition which extends downwardly into the separator chamber from the upper end wall and terminates at a lower end that is below the level of the compressed air inlet, the partition thereby dividing an upper region of the separator chamber into an outer annular section and a central cylindrical section. With this arrangement, the lower end of the partition defines an opening to the central section. Furthermore, with this arrangement, in use, compressed air circulates downwardly through the annular section and, via the opening defined by the lower end of the partition, into the central section, and thereafter upwardly through the central section to the compressed air outlet. It is preferred that the valve member comprises a head which is movable to selectively close or open the opening to the central section thereby to control the flow of compressed air to the compressed air outlet. It is preferred that the head be supported for vertical movement toward and away from the opening. It is preferred that the head be formed with an upper surface that is angled with respect to a central vertical axis of the central section so that, in use, movement of the head towards the opening progressively closes the opening. It is preferred particularly that the upper surface taper outwardly and downwardly toward the side wall of the separator chamber. It is preferred more particularly that the upper surface define a contact surface for compressed air circulating downwardly from the annular section of the separator chamber. Such a contact surface further contributes to effective separation of water vapour and entrained particulate matter and other contaminants from the compressed air. It is preferred that the head be an arrow-head profile in vertical section. It is preferred that the system comprises a drying chamber for further drying the compressed air from the separator chamber, the drying chamber containing an absorbent material for absorbing moisture from the compressed air, the drying chamber having an inlet for compressed air, and an outlet for dried and purified compressed air. It is preferred that the system comprises an assembly for ventilating the chambers to regenerate the absorbent material in the drying chamber and to remove contaminants from the separator chamber, the regeneration assembly comprising an inlet for compressed air in the drying chamber, a vent outlet in the separator chamber, and a valve assembly for opening and closing the vent outlet. With this arrangement, in use, in a regeneration cycle, during which the system is isolated from the compressor with the compressed air inlet of the separator chamber and the compressed air outlet of the drying chamber closed, compressed air supplied via the inlet in the drying chamber flows first through the drying chamber and then through the separator chamber and thereafter through the vent outlet. It is preferred that the regeneration valve assembly be solenoid operated or pneumatic operated. It is preferred that the regeneration value assembly comprises a flow control valve to minimise consumption of compressed air during regeneration and to maintain the dew point of compressed air subsequently processed by the system. It is preferred that the system further comprises a storage tank for dried and purified compressed air. It is preferred particularly that the regeneration assembly be connected to the storage tank. It is preferred that the system comprises a first expansion chamber for further drying the compressed air from the separator chamber. The purpose of the first expansion chamber is to allow compressed air from the separator chamber to cool and allow entrained water vapour to condense from the compressed air. In this connection, in many instances, compressed air flowing through the separator chamber is heated by virtue of impact with sections of the separator chamber, and the undesirable effect of the heating is to retain water vapour in the compressed air. It is preferred that the expansion chamber be between the separator chamber and the drying chamber. In the case of an oil compressor it is preferred that the system further comprises a second expansion connected to the first expansion chamber for removing oil from the compressed air from the first expansion chamber. According to the present invention there is also provided a compressor comprising: (a) a compressor assembly for compressing air; (b) the air drying and purification system described in the preceding paragraphs for drying and purifying the compressed air; and (c) a storage tank for storing the dried and purified compressed air. The present invention is described further by way of example with reference to the accompanying drawings in which: Figure 1 is a partially vertical cross-section of a preferred embodiment of an air drying and purification system for an oil-free compressor in accordance with the present invention; Figure 2 is an enlarged vertical cross-section of the separator chamber shown in Figure 1; and Figure 3 is a partially vertical cross-section of a preferred embodiment of an air drying and purification system for an oil compressor in accordance with the present invention. The purpose of the air drying and purification systems shown in the drawings is to dry and purify compressed air from oil-free or oil compressors {not shown) so that the dried and purified compressed air can be re-used in the compressors. Under normal circumstances, compressed air from an oil-free or an oil compressor is hot, typically 260°C, and it is preferable that the hot compressed air be cooled prior to being supplied to the air drying and purification system. This can be achieved by any suitable means, such as a heat exchanger (not shown) . The air drying and purification system ("the system") shown in the Figures 1 and 2 receives cooled compressed air from an oil-free compressor (not shown) via an inlet line 3 and discharges dried and purified compressed air via an outlet line 5 to a storage tank (not shown) . The system comprises a separator chamber 9 for separating moisture and entrained contaminants, such as particulate material and oil vapour, from the cooled compressed air. The separator chamber 9 is defined by a vertically disposed cylindrical side wall 11, an upper end wall 12, and a lower end wall 14. The separator chamber 9 comprises an inlet 16 for cooled compressed air, an outlet 13 for at least partially dried and purified compressed air in the upper end wall 12, and an outlet 15 for moisture and contaminants separated from the compressed air in the lower end wall 14. The outlet 15 transfers the moisture and contaminants separated from the compressed air into a tapered discharge chamber 17. The separator chamber 9 further comprises a cylindrical partition 21 which divides an upper region of the separator chamber 9 into a central section 23 and an annular section 25. The partition 21 extends downwardly into the separator chamber 9 from the upper end wall 12 and terminates below the level of the inlet 16 and above the lower end wall 14. The lower end of the partition 21 defines an opening 18 to the central section 23. The separator chamber 9 further comprises an adjustable valve member, generally identified by the numeral 6, for controlling the flow of compressed air from the separator chamber 9 via the outlet 13. The principal purpose of the valve member 6 is to enable the flow of compressed air through the separator chamber 9 to be matched to that of the output of a given compressor to minimise the pressure across the separator chamber 9. As can best be seen in Figure 2, the valve member 6 comprises a head 61 mounted on a shaft 63 which is received for vertical movement in a sleeve 65 that extends through the lower wall 14 of the separator chamber 9. The head 61 has an arrow-head profile in vertical section, and comprises a tip 66, a conical surface 65 that extends downwardly and outwardly from the tip 66, and a frusto-conical surface 67 that extends downwardly and outwardly from a trailing edge 69 of the conical surface 65. The head 6 further comprises a mounting sleeve 75 which locates the head 61 onto the shaft 63 and frusto-conical undercut surfaces 71, 73 which connect a trailing edge 68 of the conical surface 65 to the mounting sleeve 75. The head 61 is formed so that there is a relatively small annular gap G between the trailing edge 68 of the frusto-conical surface 67 and the side wall 11. It can readily be appreciated that vertical movement of the head 61 progressively opens or closes the annular opening 18 to the central section 23. In this connection, in the preferred embodiment the vertical position of the valve member 6 is adjusted manually. The shaft 63 of the valve member 6 and the support sleeve 65 are screw threaded, and the lower end of the shaft 63 is formed to receive a tip of a screw driver. With this arrangement, the valve member 6 can be adjusted manually prior to connection to a compressor by disconnecting temporarily the discharge chamber 17 from the separator chamber 9 to allow access to the lower end of the shaft 63. It can also readily be appreciated that, in use of the system, cooled compressed air entering the separator chamber 9 through the inlet 16 in the side wall 11 contacts a section 7 of the partition 21 that directly faces the inlet 16. After being deflected by the section 7 the compressed air circulates downwardly through the annular section 25 and contacts the conical and frusto-conical surfaces 65, 67 of the head 61 of the valve member 6. Thereafter, the compressed air flows upwardly through the opening 18 into the central section 23 and through the compressed air outlet 13. It can also readily be appreciated that the section 7 of the partition 21 and the conical and frusto-conical surfaces 65, 67 of the head 61 of the valve member 6 define impact zones which are effective means of separating moisture and entrained contaminants from the compressed air. The applicant has found in extensive experimental work that the contact of compressed air with the section 7 can remove up to 60% of the entrained moisture according to the psychrometric humidity chart. After separation from the compressed air, the moisture and entrained contaminants drop downwardly through the gap G and the outlet 15 into the discharge chamber 17. It is noted that the upwardly angled surface of the frusto-conical undercut 71 inhibits reverse flow of water vapour and contaminants into the separator chamber 9. The system further comprises expansion chamber 30 connected to the compressed air outlet 13 for drying compressed air from the separator chamber 9. The expansion chamber 30 is provided to allow compressed air flowing from the separator chamber 9 via the outlet 13, which is heated due to impacts in the separator chamber 9, to expand and cool and thereby allow water vapour retained in the compressed air to condense from the compressed air. The system further comprises a chamber 29 connected to the expansion chamber 30 for absorbing any remaining moisture retained in the compressed air. The drying chamber 29 is defined by an essentially elongate cylindrical column 31 which has: (i) an inlet 33 at a lower end thereof defined by a mesh filter through which compressed air flows directly from the expansion chamber 30, and (ii) an outlet 35 at an upper end thereof defined by a microfilter 45. The drying chamber 29 further comprises a bed 43 of granular molecular sieve material, such as Rhone- Poulenc molecular sieve 13X, or other suitable material, substantially filling the cylindrical column 31. The system further comprises an assembly for ventilating the system periodically. The ventilation system comprises an inlet 81 for compressed air in an upper section of the drying chamber 29 and an outlet 19 at a lower end of the discharge chamber 17. The inlet 81 is connected to the compressed air storage tank (not shown) . It can readily be appreciated that, in use, compressed air flowing from the storage tank through the inlet 81 flows into the drying chamber 29 and downwardly through expansion chamber 30, the separator chamber 9 and the discharge chamber 17 to the outlet 19. In such a situation, with the system isolated (with the compressed air inlet 16 in the separator chamber 9 and the compressed air outlet 35 in the drying chamber 29 closed) , moisture and contaminants in the drying chamber 29, the expansion chamber 30, the separator chamber 9, and the discharge chamber 17 are flushed from the system via the outlet 19. With reference to Figure 3, the preferred embodiment of the system for an oil compressor comprises an identical separator chamber 9 and an identical expansion chamber 30 to those of the preferred embodiment for an oil-free compressor shown in Figures 1 and 2. However, with reference to Figure 3, the system for an oil compressor further comprises a second expansion chamber 61 connected to the expansion chamber 30 for separating oil from the compressed air flowing from the expansion chamber 30. The second expansion chamber 61 is defined by an essentially elongate cylindrical column 31 which has: (i) an inlet 63 at a lower end thereof defined by a mesh filter; and (ii) an outlet 65 at an upper end thereof defined by a microfilter 45. In use, the flow of compressed air in the expansion chamber 30 is relatively turbulent, and the turbulence increases as the compressed air flows through the mesh filter inlet 65. The effect of the turbulent flow is to cause oil contained in the compressed air to be forced against the side wall of the second expansion chamber 61 and retained on the side wall. The separation of oil from the compressed air is enhanced by further cooling of the compressed air as it flows through the second separation chamber. Any residual oil is retained on the microfilter 45 that forms the outlet of the second expansion chamber. The system further comprises a drying chamber 71 containing a bed of granular molecular sieve material connected to the second separation chamber 61 for absorbing any remaining moisture retained in the compressed air. Finally, the system further comprises an assembly for ventilating the system periodically. The ventilation system is similar to that of the system for an oil-free compressor shown in Figures 1 and 2. The ventilation system comprises an inlet 91 for compressed air in an upper section of the drying chamber 71 and the outlet 19 at the lower end of the discharge chamber 17. In use, compressed air flowing through the inlet 91 flows successively through the drying chamber 71, the second expansion chamber 61, the expansion chamber 30, the separator chamber 9 and the discharge chamber 17 to the outlet 19. The compressed air flow flushes moisture and contaminants in the various chambers and retained on the various filters from the system via the outlet 19. Many modifications may be made to the preferred embodiment of the present invention without departing from the spirit and scope thereof. For example, whilst in the preferred embodiments the section 7 of the partition 21 forms the impact zone that faces the compressed air inlet 16 to the separator chamber 9, it can readily be appreciated that the present invention is not limited to such an arrangement and the impact zone may be formed from any suitable means.

Claims: CLAIMS : 1. An air drying and purification system for compressed air from a compressor, which system comprises, a separator chamber for at least partially drying and purifying compressed air from the compressor by separating moisture and entrained particulate material and other contaminants from the compressed air, the separator chamber having: (i) an inlet for compressed air; (ii) a contact surface facing the inlet and forming an impact zone for separating moisture and entrained particulates and other contaminants from compressed air entering the separator chamber via the inlet; (iii) an outlet for at least partially dried and purified compressed air; and (iv) an adjustable valve member for controlling the flow of compressed air from the separator chamber via the outlet. 2. The system defined in Claim 1 wherein the valve member is adjustable to match the flow of compressed air through the separator chamber to that of a given compressor output to minimise the pressure drop between the inlet and the outlet of the separator chamber. 3. The system defined in Claim 1 or Claim 2 wherein the separator chamber comprises a vertically disposed cylindrical side wall and upper and lower end walls. 4. The system defined in Claim 3 wherein the compressed air inlet is located in an upper section of the side wall. 5. The system defined in Claim 3 or Claim 4 wherein the compressed air outlet is in the upper end wall. 6. The system defined in Claim 5 wherein the separator chamber comprises a cylindrical partition which extends from the upper end wall downwardly into the separator chamber and terminates at a lower end that is below the level of the compressed air inlet, the partition thereby dividing an upper region of the separator chamber into an outer annular section and a central cylindrical section, with the lower end of the partition defining an opening to the central section and the compressed air outlet being located in the central cylindrical section, and whereby, in use, compressed air can circulate downwardly through the annular section and, via the opening defined by the lower end of the partition, into the central section, and thereafter upwardly through the central section to the compressed air outlet. 7. The system de ined in Claim 6 wherein the valve member comprises a head which is movable to selectively close or open the opening to the central section thereby to control the flow of compressed air to the compressed air outlet. 8. The system defined in Claim 7 wherein the head is supported for vertical movement toward and away from the opening. 9. The system defined in Claim 8 wherein the head is formed with an upper surface that is angled with respect to a central vertical axis of the central section so that, in use, movement of the head towards the opening progressively closes the opening. 10. The system defined in Claim 9 wherein the upper surface tapers outwardly and downwardly toward the side wall of the separator chamber. 11. The system defined in Claim 10 wherein the upper surface defines a contact surface for compressed air circulating downwardly from the annular section of the separator chamber to further contribute to separation of water vapour and entrained particulate matter and other contaminants from the compressed air. 12. The system defined in any one of the preceding claims further comprises a drying chamber for further drying the compressed air from the separator chamber, the drying chamber containing an absorbent material for absorbing moisture from the compressed air, the drying chamber having an inlet for compressed air, and an outlet for dried and purified compressed air. 13. The system defined in Claim 12 further comprises an assembly for ventilating the chambers to regenerate the absorbent material in the drying chamber and to remove contaminants from the separator chamber, the regeneration assembly comprising an inlet for compressed air in the drying chamber, a vent outlet in the separator chamber, and a valve assembly for opening and closing the vent outlet. 14. The system defined in Claim 13 wherein the regeneration valve assembly is solenoid operated or pneumatic operated and comprises a flow control valve to minimise consumption of compressed air during regeneration and to maintain the dew point of compressed air subsequently processed by the system. 15. The system defined in any one of Claims 12 to 14 further comprises an expansion chamber for further drying the compressed air from the separator chamber. 16. The system defined in Claim 15 wherein the expansion chamber is between the separator chamber and the drying chamber. 17. A compressor comprising: (a) a compressor assembly for compressing air; (b) the air drying and purification system defined in any one of the preceding claims for drying and purifying the compressed air; and (c) a storage tank for storing the dried and purified compressed air.

Inventors: BELLOMO ERASMO MIMMO, BELLOMO, ERASMO, MIMMO
Applicants: AP SYSTEMS AUSTRALIA, BELLOMO ERASMO MIMMO, A P SYSTEMS (AUSTRALIA) PTY. LTD., BELLOMO, ERASMO, MIMMO
Application year: 1997
Main classification: B01D53
IPC codes: B01D45, B01D50, B01D53