HK1021019B - Twin tower air dryer - Google Patents

Description

Double-tower air dryer

(1) Field of the invention

The inventions disclosed in this patent application are germane to U.S. patents nos. 5,423,129, 5,604,991, 5,662,727, and 5,685,896, and also to the following, yet unauthorized patent applications: U.S. patent application No. 08/976,649 entitled "E-1 twin tower air dryer for air compressor" filed on 26/11/1997; U.S. patent application serial No. 08/978,796, filed on 26/11/1997, "liquid separator for E-1 air dryer with baffle"; united states patent application serial No. 08/978,551 entitled "control valve for shaft seal" filed on 26/11/1997; U.S. patent application serial No. 08/979,198, entitled "shuttle valve mechanism for a twin tower air dryer", filed on 26/11/1997; U.S. patent application No. 08/979,197, entitled "exhaust duct with flapper valve for desiccant-containing air dryer", filed on 26/11/1997; and two applications simultaneously applied with the present invention: "shuttle valve for two column air dryer" serial No. 09/017,126 and "low level discharge check valve" serial No. 09/017,247. All of the above patents and patent applications are assigned to the assignee of the present invention. Further, the disclosure of each of the issued patents and the unauthorized patent applications is incorporated herein by reference.

The present invention relates generally to a dual tower air cleaning and drying system for an air compressor. More particularly, the present invention relates to a new and improved dual tower air cleaning and drying system for an air compressor.

(2) Background of the invention

It is well known that air dryers of westinghouse air brake companies are used in compressed air systems of railroad trains, transport trucks and the like to remove moisture from the compressed air, which is essential to operate the air brake system and the air valve. The aforementioned U.S. patent No. 5,423,129, assigned to the assignee of the present invention, discloses a system in which compressed air is cleaned and dried by passing the compressed air through a regeneration system containing a desiccant material to absorb moisture and filter out particulate matter. A small portion of the dried air is then passed back through the desiccant-containing regeneration system to absorb at least a portion of the moisture collected in the desiccant to regenerate the desiccant, and the moisture-absorbed dried air is exhausted.

In operation, the prior art air drying systems described above (now referred to as "single tower" systems) receive compressed air from a conventional air compressor, which typically contains unacceptably high amounts of moisture and other particulate matter suspended therein. This raw compressed air is passed upwardly through a desiccant material, typically in the form of a porous cartridge containing a porous desiccant medium. The desiccant plays a critical role within a single tower air drying system because it absorbs moisture and traps various particulates (e.g., dust, dirt, etc.) as the compressed air moves upward through the desiccant medium. Once the moisture and particles are separated from the air stream, the cleaned and dried compressed air continues to flow from the desiccant medium through a bleed check valve located near the top of the tower. This purified compressed air then passes through a side chamber, a portion of which finally reaches a discharge chute.

When the air compressor is cycled off, the system operates in a purge mode of operation. During the purge mode of operation, the purified compressed air contained in the exhaust slot passes in the reverse direction very slowly through a throttle valve in a bleed check valve and then back through the desiccant media. This slow flow of drying air re-absorbs a portion of the moisture previously collected in the desiccant medium. The moisture evaporates into the drying air stream flowing through, and the evaporated moisture is finally discharged to the atmosphere through a sump. The drying air is gradually returned to the system for drying and thus regenerating the desiccant medium. When the air compressor is operating in a recirculation mode, the column system is returned to a drying mode of operation, allowing the desiccant medium to be removed from the unpurified compressed air stream passing through the system.

Recently, a dual tower system has been proposed and developed in which a pair of desiccant containing chambers or towers are provided, each tower alternating between a drying mode of operation and a recirculation mode of operation. Thus, in operation at any one time, while one tower is operating in the air drying cycle, the other tower is operating in either the recirculation mode or the purge cycle. A pair of control valves are provided to automatically switch the air streams to reverse their flow direction for reverse cycling after a predetermined time to achieve continuous operation, each tower operating alternately in a drying mode to collect moisture in the desiccant medium and the other tower in a recirculation mode to remove the collected moisture from the desiccant material or medium. This unique system, which is clearly capable of greater moisture removal, also avoids the need to stop the circulation of the source of raw air before the moisture that has accumulated in the desiccant material can be removed, thereby avoiding the need to shut down the compressor and temporarily stop the pneumatic system from stably supplying clean and dry compressed air.

In addition to the advantages described above, the switching of the two drying apparatuses between drying and purge modes allows the two-tower system to dry the air stream more efficiently than previous single-tower systems. Two desiccant towers are employed in the air drying system instead of one, one of which absorbs moisture and the other removes moisture. Thus, the alternating transition between drying and purging modes of the two drying systems serves to continuously purge moisture from the double tower system. Thus, more fully dry air is supplied to the pneumatic system. And the amount, density and total surface area of the desiccant can be selected to suit different needs.

The double column system can be widely used in a variety of different pneumatic systems. Typical types of pneumatic systems to which the double tower system can be applied include pneumatic brake systems for passenger or freight trains, subway trains, and various other types of rail transport systems. Further examples of systems that can be used include pneumatic brake systems for various haul trucks. Furthermore, other types of pneumatic systems that can use a double tower system can also be found outside the transportation field.

Another disadvantage of single tower air drying systems is that only a certain limited amount of moisture can be removed in the purge mode of operation. Since the volume of the bulk of the raw air to be dried flowing into the system exceeds the volume of purified air used to purge the desiccant medium, the desiccant never dries adequately during operation of the single tower system. In fact, the desiccant medium is only sufficiently dry when the system is shut down for a predetermined amount of time sufficient to achieve proper drying.

While prior art two-tower systems work well, there is a need for improved compactness, serviceability and serviceability of two-tower desiccants for various compressors.

(3) Summary of the invention

It is a primary object of the present invention to provide a compact, easily serviced air dryer for supplying air from a compressor to a main reservoir while also providing a method of purifying and regenerating the desiccant material in the dual tower desiccant container of the air dryer.

The dual tower gas drying system of the present invention for cleaning and drying a gas stream from a source of raw compressed gas for use in a pneumatic system comprises:

a multiple connector with a plurality of ports,

a separator and sump connected to said manifold and to a port in said sump for first separating moisture and other particles from the raw gas stream before the gas stream is directed to a first port of said plurality of ports in said manifold,

a pair of containers containing a desiccant, threadably mounted on a surface of said multiconnector opposite the mounting surfaces of the separator and the sump via two threaded shuttle valves,

further, the container and the shuttle valve are respectively in fluid communication with a second port and a third port of the plurality of ports provided in the multiconnector to respectively supply and remove compressed air from the container,

a port for exhausting dry clean air from said multiconnector,

ports for discharging moisture-purged air from the multiconnector to the atmosphere, an

A port disposed in the sump for releasing liquid collected in the sump.

Easy serviceability is achieved by using disposable, easily removable and attachable air dryer vessels with low clearance, by using shuttle valves threadably connectable to and between the two vessels, a low manifold block pneumatically connecting them together, by connecting two such vessels together, by connecting the two vessels to an air compressor, and by connecting them to a system using air dried and cleaned by the vessels.

The present invention has broad applicability by using a standard size threaded hole provided on the dryer. Most air compressors can be connected to the dryer of the present invention with a simple hose having a standard fitting threaded into the threaded hole. Whereas the dryers of the prior art have so far required a complete set of accessories to connect them with the compressor.

(4) Description of the drawings

The invention, together with its advantages and objects, will be best understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an exploded view of the dryer system of the present invention; and

fig. 2 is a cross-sectional view of the dryer system of fig. 1.

(5) Detailed description of the preferred embodiments

Referring now to fig. 1, an exploded view of the dryer system of the present invention is shown and generally designated by the reference numeral 10. The system includes two disposable threaded containers 12, two low shuttle/vent valves 14 that are externally threaded to screw into the containers 12, thereby pneumatically connecting the containers 12 to a multiconnector 16 having a threaded bore 18 that receives the threaded valve 14. Thus, the container 12 can be easily attached to and detached from the multiconnector 16 via the screw valve 14, and the threaded valve 14 can also be easily attached to and detached from the container 12 and the multiconnector 16.

The low or short valve 14 has a clearance of about one inch to allow removal and installation of the container 12, whereas prior art dryers use desiccant bags that require a seven inch clearance for removal and installation.

Furthermore, when the container 12 of the present invention is screwed on and off the valve 14, i.e., the container 12 is removed and installed by simply rotating the container 12.

The compactness of the dryer system 10 is best seen in figure 2, where the container 12 is fully attached to one side or face of the multiconnector 16, and the sump housing 20 is suitably attached to the side or face of the multiconnector 16 opposite the container 12. The multiconnector 16 itself is relatively low in height, i.e., about 3.9 inches thick and about 5.5 inches wide. The total height of the dryer from the lower funnel 22 at the bottom of the sump 20 to the top of the container 12 is about eighteen inches.

As shown in fig. 2, the multiple connection body 16 is provided with a plurality of connection ports for connecting the respective components of the double tower drying system 10. The gas flow from a compressor (not shown) enters an inlet 30 provided in the sump 20 and enters the centrifugal separator, causing heavy water and impurities to impact the side walls of the separator and fall to the bottom of the sump. Air and any remaining moisture in the air enters the multiconnector 16 through a first port 32 disposed in the multiconnector 16, which first port 32 directs the air and moisture to two control (spool) valves 34. The two control valves 34 alternately direct such air and moisture into the respective containers 12 through ports 36 in the multiconnector 16, only one of the second ports 36 being visible in figure 2. The control valve 34 is operated by two solenoid valves 38, and the solenoid valves 38 are themselves energized by a timer (not shown). Thus, the direction of the "purge" and "dry" air flows in the compound connection 16 is directly controlled by the spool valve 34. During the drying process, moist air is introduced along the second port 36 into and through a coalescing agent means 39 located in the lower portion of each vessel 12, the means 39 removing oil and other fine impurities from the moist air. From this device 39 of spongy material, the air flows to the upper part of the container 12 and down through a desiccant material 40 in the container 12 to the shuttle valve 14 and to a third port 42 common to both the container 12 and the shuttle valve 14.

While the drying process is being carried out in one vessel 12, the other vessel is purged of moisture from its desiccant by a small portion of the drying air stream directed from the drying vessel through the common third port 42 to the shuttle valve 14 of the purge vessel. The shuttle valve 14 directs this small flow of air upwardly (in the drawing) through the desiccant 40 to remove moisture therefrom and out to the atmosphere through ports 44 (only one of which is visible in fig. 2) connecting the container to the spool valve 34.

The drying air from the drying vessel exits the manifold 16 through the third port 42 and the exhaust valve 46. From the outlet valve 46, the drying air is sent, for example, to a container (not shown), while a small portion of the drying air is sent to the solenoid valve 38 and a control timer (not shown) through a port 47 in the multiconnector 16.

The multiconnector 16 thus provides a compact structure for handling and directing compressed air to components mounted in the multiconnector 16 to remove water and other impurities from the air, and then directing relatively dry and clean air from the multiconnector 16. The material of the multiconnector 16 is preferably an aluminum alloy such as 6061, which is easily machined to provide suitable tolerances. Another advantage of the present invention is its wide applicability to a variety of air compressors and aftercoolers, if used. The sump housing 20 of the present invention has a standard sized threaded hole 30 in the wall thereof as shown in fig. 2 of the drawings. The aperture may receive a standard sized threaded fitting provided at the end of the hose so that substantially all air compressors requiring an air dryer can be directly connected to the air dryer system 10 of the present invention. The standard size of fittings used in the industry for compressor outlet ports today is 3/4 inches outside fit diameter, with a typical 1/2 inches inside diameter to direct the air flow. The dryer system 10 of the present invention can be connected to most air compressors employing dryer systems without the need for a kit or other components.

The liquid water is collected in the sump 20 and discharged to the atmosphere through the drain valve 50 and the funnel 22.

The air dryer assembly and system 10 of the present invention is compact and quick to service by rotating the dryer vessel 12 for removal and replacement with a one inch void space, and has wide applicability because most compressors can be easily and quickly connected to the dryer sump 20 of the system 10 by a standard size threaded hole in the sump wall.

While a preferred embodiment for carrying out the present invention has been described in detail, those skilled in the art of air drying and cleaning to which the present invention pertains will appreciate that numerous other embodiments and methods of practicing the present invention can be readily derived therefrom without departing from the spirit and scope of the appended claims.

Claims (7)

1. A dual tower gas drying system for cleaning and drying a gas stream from a source of raw compressed gas for use in a pneumatic system, said gas drying system comprising:

a multiple connector with a plurality of ports,

a separator and sump connected to said manifold and to a port (30) in said sump for first separating moisture and other particles from the raw gas stream before the gas stream is directed to a first port (32) of said plurality of ports in said manifold,

a pair of containers containing a desiccant, threadably mounted on a surface of said multiconnector opposite the mounting surfaces of the separator and the sump via two threaded shuttle valves,

further, the container and the shuttle valve are in fluid communication with a second port (36) and a third port (42), respectively, of the plurality of ports provided in the multiconnector for supplying compressed air to the container and for withdrawing compressed air from the container, respectively,

a port (47) for discharging dry clean air from the multiconnector,

ports (44) for discharging moisture-depleted air from the multiconnector to the atmosphere, and

a port (22) is provided in the sump to release liquid collected in the sump.

2. The dual tower gas drying system of claim 1, wherein a threaded hole is provided in a wall of the sump to directly connect the sump to a source of compressed air.

3. The twin tower gas drying system of claim 1, wherein two control valves are connected to the manifold and to ports provided in the manifold that are connected to the containers to control the flow of air into and out of the containers during the transition between the air moisture removal and drying functions of the two containers.

4. The twin tower gas drying system of claim 3, wherein the control valve is further connected to a moisture purged air vent for controlling the venting of air to the atmosphere.

5. The dual tower gas drying system of claim 1, wherein the desiccant container contains a coalescing agent material to remove oil and particulates from the gas stream.

6. The twin tower gas drying system of claim 1, wherein the manifold is made of a machinable material.

7. A twin tower gas drying system as defined in claim 6 wherein the material of the manifold is an aluminum alloy.