US2205793A - Compressor - Google Patents

Description

F. B. HUNT 4 COMPRESSOR Filcad Aug. 10, 1936 2 $hwts-Sheet 2 TToRNEYs.

Patented June 25, 1940 PATET OFFiCE COMPRESSOR Franklin B. Hunt, Chicago, Ill., assignor to lhe Liquid Carbonic Corporation, Chicago, 111., a corporation of Delaware Application August 10, 1936, Serial No. 95,083

5 Claims.

The present application relates to compressors, and more particularly to compressors of the multi-stage type.

The primary object of the invention is to provide means whereby the 5 number of stages of compression is greater than the number of Working pistons in the complete machine.

A further object of the invention is to provide, in a machine of the class described, means whereby, by a simple adjustment, the number of compression stages may be. varied, in a given machine.

To lated in the forms illustrated in the accompanying the accomplishment of the above and reobjects, my invention may be embodied drawings, attention being called to the fact, however, that the drawings are illustrative only, and that change may be made in the specific construction illustrated and described so long as the scope of the appended claims is not violated.

l is a diagrammatic view of a two cylinder multi-stage compressor,

Fig. 2 is a diagrammatic illustration of a three cylinder compressor connected in a car-- bon dioxide plant,

Fig.

3 is a view similar to Fig. 1, but showing a modified form of compressor, and

4 is a view similar to Fig. 2, illustrating illus- As is disclosed in the copending application of Franklin B. Hunt, Jabez E. Pratt, Henry S. Tirrell and Robert L. Turner, Serial Number 686,486, for Method of and apparatus for producing carbon dioxide, one advantageous method of manufacturing liquid and solid carbon dioxide involves the steps of compressing gaseous carbon dioxide, in a multiple stage compressor, to a pressure sufficient to cause liquefaction of gas, and passing the liquid through a series of successive evaporators, wherein portions of the liquid are evaporated to cool the remaining liquid; the final evaporating stepv illustrated in the copending application causing solidification of the remaining liquid. As is disclosed in said copending application, the gas evolved in the various evaporating chambers is returned to the compressor at the various stages, the stage at which gas from a given evaporator is reintroduced into the compressor depending upon the pressure of the gas evolved in each individual evaporating chamber.

the drawings, the primary evaporating Hit.

Gas is evolved inthis chamber at a pressure of 300 pounds per square inch. Gas is evolved in the secondary evaporating chamber IE2 at approximately 75 pounds per square inch; and, during a freezing operation, gas is evolved in the freezing chamber H63, likewise at a pressure of approximately '75 pounds per square inch absolute.

However, after a suitable quantity of solid has been formed, it is necessary to pump the freezing chamber pressure down to atmospheric pressure. Obviously, if gas at a pressure materially below '75 pounds per square inch absolute is to be led from the freezing chamber into the compressor, and into a cylinder of the compressor which normally receives gas at a pressure of 75 pounds, the compression ratio in that cylinder is greatly increased. When atmospheric conditions are reached in the freezing chamber, that ratio of compression will be approximately 20, which is excessive.

When a compressor of the type illustrated in Fig. 1 is used in connection with such a plant, gas is led from the primary evaporating chamber 16! to the high pressure cylinder H; and gas is led from the freezing chamber W3 and/or from the secondary evaporator I62 to the cylinder l2.

This compressor comprises a driving means, indicated generally at ill, the two cylinders ii and i2 being positioned, in alignment, upon opposite sides of the driving means. A piston i3 is operatively positioned in the cylinder ii and is connected by piston rod M, to the driving means it]. Similarly a piston I5 is operatively positioned in the cylinder I2 and is connected by a piston rod iii to the driving mechanism it.

The cylinder ii is provided with a valved inlet port ll and a valved outlet port it at its end adjacent the driving means; and with a valved inlet port l8 and a valved outlet port til at its end remote from the driving means. Ob,- viously, because of the presence of the piston rod M, the effective cross-sectional area of that end of the cylinder I I adjacent the driving means is less than the effective cross-sectional area of that end of the cylinder remote from the driving means.

Similarly, the cylinder I2 is provided with a valved inlet port 22 and a valved outlet port 2d at its end adjacent the driving means, and with a valved inlet port 2| and a valved outlet port 23 at its endremote from the driving means. In the same way the-eflective cross-sectional the driving means is smaller than the effective A conduit 29 is provided with branches com municating with the outlets 23 and it, and has a check valve 3% positioned therein, permitting flow away from the port 23, but preventing fiow toward said port.

The conduit 29 leads to and through an intercooler 3|, and a conduit 32 leads from the opposite end of said inter-cooler, being provided with branches communicating with the ports El and E8 of the cylinder ii. A conduit 33 connects the primary evaporator i8! with said conduit 32. A conduit 3d leads from the ports is and 2d of the cylinder H, through a condenser It! to the primary evaporator i6.

While the freezing operation is going on, and gas is being supplied from the freezing chamber Hi3 through the conduit 25 at a pressure of 2'5 pounds per square inch absolute, the compressor operates in a normal manner, both of the cylinders l l and I2 operating as double-acting compressors. This operation .will continue until the intake'pressure in the conduit 25 falls below a predetermined value, such, for instance, as 50 pounds per square inch absolute.

' A passage 35 communicates with the conduits 2i and 29; the point of communication with the conduit 27 being between the valve 28 and the port 22, and the point of communication with the conduit 29 being between the port 23 and the Valve 30. Flow through this passage 35 is controlled by a Valve 35, of any desired positively actuated type. When the pressure in the conduit 25 falls below the predetermined value, the valve 36 is opened; thereby converting the cylinder i2 into a two-stage compressor, instead of a doub1e-acting compressor. With the valve 35 open, gas will flow, upon movement of the piston 55 towardthe left, from the conduit 25 through the port 2! into the right hand end of the cylinder l2. Upon movement of the piston to the right, the gas in the right hand end of the cylinder will be forced through the port 23, conduit 29, passage 35, and conduit 27, and so through the port 22 into the left hand end of the cylinder i2. Upon movement of the piston 25 toward the left again, the gas so drawn through the port 22 will be forced through the port 2 and so through the intercooler 3i and to the cylinder H. Thus, gas is pumped from the right hand end of the cylinder l2 into the left hand end of said cylinder, which is of smaller volume because of the presence of the rod I6, and thence to the intercooler. Because of this difierence in the volumes of the respective ends of the cylinder l2, we get a two-stage compression which, when the intake pressure is 15 pounds per square inch and the pressure of discharge from the cylinder as a Whole is 300 pounds per square inch, involves a compression ratio of from 3 to 3 in the right hand end of the cylinder and a compression ratio of from 6 to 7 in the left hand end of the cylinder. Obviously, neither of these cylinder ratios is excessive, and instead of approaching a zero pumping capacity due to low volumetric efiiciency,

the right hand end, with more than half of the total cylinder volume, operating with a ratio of 3 to 3%, will have a volumetric efficiency of from 80 to 85%.

As soon as the pressure in the freezing chamber has reached approximately atmospheric value, the valve 36 will be closed and the normal operation of the organization Will continue. Suitable valves are, of course, provided to control the flow through the system.

The above organization is, of course, merely a recompressor arrangement, into which carbon dioxide is introduced either in the liquid phase through conduit It? or in the gaseous phase through conduit I53; In Fig. 2, there is shown a three cylinder combination compressor. In said Fig. 2, the reference numeral it indicates driving mechanism, with which are associated cylinders M, 2 and 43. All of the cylinders are in alignment, and the cylinder i2 is preferably positoned on one side of the driving mechanism, while the cylinders M and 43 are positioned on the other side thereof, the cylinder 575 being spaced from the driving mechanism by the cylinder M. A piston 44 is reciprocably positioned in the cylinder M and is carried upon a piston rod t5 connected to the driving mechanism. An extension 45 of the rod 45 carries the piston 46 which is reciprocably mounted in the cylinder 33. A piston i! is operatively positioned in the cylinder 12 and is connected to the driving mechanism by a piston rod 43.

Process gas (that is, gas which is'entering the conversion cycle for the first time) is led into the combination machine through the branched conduit 49 which communicates witn'the valved inlet ports 50 and 5! of the first cylinder M which, operating as a double acting compressor, compresses the gas and forces it out through the ports 52 and 53 and the branched conduit 54 to and through a first stage intercooler 55. Thence, the compressed and cooledgas, at 'a pressure of 50 to '75 pounds per square inch absolute, is led through the conduit 56 to the inlet port 5'! of the second cylinder 42.

Concurrently, gas from the freezing chamber I63 is led, through the conduit 58, to the valved inlet port 59 of the cylinder 32. An operating handle 53' is provided for manually holding open the valve in port 59, at times. The cylinder 12 operates as a double acting compressor, drawing gas for its left hand end from the cylinder ii, drawing gas for its right hand end from the freezing chamber H53 and secondary evaporator I62; and forcing gas drawn from both sources through the respective outlet ports 5i and 62 and thus through the conduits 63 and ii! to the second stage intercooler 58. A check valve 54 is interposed in the conduit 63, and a check valve 6i! is positioned in the conduit 58, for a purpose which will later appear.

A passage 65 communicates with the conduits 58 and 63, the point of communication with the conduit 58 being between the check valve E0 and the inlet port 51, and the point of communication with the conduit 63 being between the port 62 and the check valve 84. Flow through the passage 65 is permitted or prevented, depending upon the position of a control valve 66.

From the second stage intercooler 68, gas is led through the conduit 69, at a pressure of approximately 300 pounds per square inch absolute. Concurrently, gas is led from the primary evaporator i6! through a conduit 1i and the conduit 89 joins the conduit H1 before said conduit ll} ill) splits into branches II and I2 communicating, respectively, with valved inlet ports I3 and I4 of the cylinder 43. An operating handle I4 is provided for manually holding open the valve in port I4, at times. Said cylinder 43, operating as a double acting compressor, forces the gas so fed to it through the valved outlet ports I5 and I6 and the conduit branches II and III to the high-pressure descharge line 70, the gas flowing through said line I9 at a pressure of approximately 1,000 pounds per square inch.

When the complete organization is being operated to produce solid carbon dioxide, the above description applies properly. As in the case of the organization of Fig. 1, when it is desired to pump down the freezing chamber I63, the valve I50 is opened to provide an extra stage of compression in the cylinder 42.

If it is desired to operate the plant to make liquid carbon dioxide for sale, or if, for any other reason, the freezing chamber I03 is not in use, manually operable means is provided for holding permanently open the valves 59 and I4, thereby unloading the right hand end of the cylinder 42 and the left hand end of the cylinder 43, so that the organization comprises a double-acting firststage and single-acting second and third stages.

The desirability of this arrangement is increased by the fact that the cylinder 4I cannot, in many instances, be used to pump down the freezing chamber to atmospheric pressure. In many commercial applications, this first stage of compression has an intake pressure of 20 to 30 pounds per square inch absolute; and. of

.' course, in such cases, it would be impossible to pump the freezing chamber down to a pressure below this value. In all cases where the process gas is coming from a chemical process, it is absolutely necessary to avoid the building up of any increased suction pressure on the first stage, since such an increase would affect the chemical process. Thus, the combination disclosed in Fig. 2 not only eliminates the necessity for an additional cylinder in order to attain the advantages of four-stage compression, but permits the handling of both process gas and recompressed gas without affecting the chemical process supplying the process gas.

In Fig. 3, I have illustrated a modification of the organization of Fig. 1. Driving mechanism is illustrated at and cylinders 8| and 82 are arranged in alignment on opposite sides of the driving means. A piston 83 is operatively positioned in the cylinder III and is connected to the driving means by a piston rod 84; and a piston 85 is operatively positioned in the cylinder 82 and is connected to the driving means by a piston rod 06.

The cylinder BI is provided with valved inlet ports 01 and 38 positioned at its opposite ends, and with valved outlet ports 83 and 90, similarly arranged. In the same way, the cylinder 82 is provided with valved inlet ports 9! and 92 and with valved outlet ports 93 and 94.

Gas from the freezing chamber or the secondary evaporator is fed to the port 9| of the cylinder 82 through a conduit 95 and its branch I36 and to the inlet port 92 through the branch 31 in which is positioned a check valve 98. A

branched conduit 93 communicates with the ports 93 and 94 and leads gas, discharged from the I ports 93 and 94, into the intercooler IOI, a check valve I00 being positioned in the conduit 99. From the intercooler, gas flows through the conduit I02 to the inlet port 88 of the cylinder 8|,

being joined by gas flowing through the conduit I03 from the primary evaporator. In the left hand end of the cylinder BI, the gas is compressed and ejected through the port 00 and conduit I04 to and through the intercooler I and thence, through the conduit I06, which joins the conduit I0? leading from a sub-evaporator I60, to the inlet port 81 at the right hand end of the cylinder 0|. Thence, the gas is ejected at a pressure of from 1200 to 1400 pounds per square inch, through the port 89 and the discharge line I08.

As in the organization of Fig. 1, the cylinder 02 may be converted from a double-acting compressor to a two-stage compressor by opening the valve H0 in the passage I09 which leads from a point in the conduit 09 between the port 93 and the valve I00 to a point in the conduit 91 between the valve 30 and the port 92. And, as in the case of Fig. 1, carbon dioxide is introduced into the system either in the liquid phase through the conduit IGI or in the gaseous phase through the conduit I 68.

Fig. 4 is similar to Fig. 2, but incorporates the same modifications found in Fig. 3. Thus, the combination compressor of Fig. 4 comprises an operating means I20, a first cylinder I2I, a second cylinder I22, and a third cylinder I23, said three cylinders being aligned and the cylinder I22 being positioned on one side of the operating means, with the cylinders I2I and I23 positioned on the opposite side of said operating means, said cylinder I23 being spaced from the operating means by the cylinder I2I.

A piston I24 is reciprocable in thecylinder I2I, and is carried on a piston rod I25 connecting with the operating mechanism I20. A continuation I25 of the piston rod I25 carries the piston I26 which is reciprocable in the cylinder I23. A piston I2! is reciprocable in thecylinder I22 and is connected by a piston rod I28 with the operating means I20.

Process gas is led into the combination compressor through a conduit I20 having branches communicating respectively with the valved inlet ports I30 and I3I of the cylinder I2I. Said cylinder, operating as a double-acting compressor, discharges the gas through valved outlet ports I32 and I33 to a conduit I34 which leads the gas to and through a first-stage intercooler I35. Thence the gas, at a pressure of to 75 pounds per square inch absolute, is lead by a conduit I36 to the inlet port I3'I of the cylinder I22. Concurrently, gas from the freezing chamber IE3 or the secondary evaporator I02 is led through a conduit I38 tothe inlet port I39 of the cylinder I22. Said conduit I30 continues to join the conduit I30 at the inlet port I3I, a check valve I40 being positioned therein between the ports I39 and I31. I

The cylinder I22, operating as a double-acting compressor, drawing gas for its left hand end from the cylinder I2I and gas for its right hand end from the freezing chamber or secondary evaporator, forces the gas through the valved outlet ports MI and I42 and through the conduits I43 and I4? to and through the secondstage intercooler I48. A check valve I44 is positioned in the conduit I43 between the port I42 and the conduit I41. A passage I45 communicates with the conduit I43 at a point between the port I42 and the Valve I44, and with the conduit I38 at a point between the valve I40 and the port I31; flow of fluid through said passage being controlled by said valve I46.

Fromthe second-stage intercooler, the gas is led through a conduit M9, at a pressure of approximately 300 pounds per square inch absolute, to a conduit 550 leading from the primary evaporator IE! to the inlet port I52 of the cylinder 423. Gas entering the cylinder I23 through said port IE2 is compressed, upon movement of the piston 12$ toward the left, and forced through the outlet port I53 and conduit H54, thence through the third-stage intercooler M5, and through the conduit 956 which joins with a conduit l5! leading from the sub-evaporator I66 to the inlet port 158 of the cylinder 823, at a pressure of approximately 550 pounds per square inch absolute. Thence, by a further compression stage achieved in the right hand end of the cylin der I23, the gas is ejected through the outlet port I59 and the high pressure line I60, at a pressure of 1200-1400 pounds per square inch, to the condenser 564. The liquid there produced flows to the primary evaporator Nil.

As in previous examples, when it is desired to pump down the freezing chamber 463, the valve M6 is opened to provide two stages of compression in the cylinder I22.

If it is desired to operate the plant to make liquid carbon dioxide for sale, or if, for any other reason, the freezing chamber IE3 is not in use, manually operable means is provided for holding permanently open the valves I30 and I52, thereby unloading the right hand end of the cylinder H2 and the left hand end of the cylinder E23,, so that the organization comprises a double-acting first-stage and single-acting second and third stages.

While I have shown the piston rods of substantially uniform diameters in all the illustrated forms of my invention, it will be obvious that the rods in a given form may vary in size. For instance, in the embodiment of Fig. 4, the portion of rod I25 which is located in cylinder E23 might be larger than the portion thereof which is located in the cylinder l2 I. By this means, any desired ratio of cylinder size, within reasonable limits, may be obtained.

I claim as my invention:

1. A compressor comprising a cylinder, a piston reciprocable in said cylinder, a piston rod secured to one end only of said piston and projecting through the adjacent end of said cylinder, a first valved inlet port adjacent said end of said cylinder, a first valved outlet port adjacent said end of said cylinder, a second valved inlet port adjacent the opposite end of said cylinder, a second valved outlet port adjacent said opposite end of said cylinder, a first conduit connecting said first inlet port with said second inlet port, a valve in said first conduit preventing fluid flow from said first inlet port toward said second inlet port but permitting fluid fiow in the opposite direction, a second conduit connecting said first outlet port with said second outlet port, a valve in said second conduit preventing fluid flow from said first outlet port to said second outlet port but permitting fluid flow in the opposite direction, a third conduit communicating withv said first conduit between said first inlet port and said valve in said first conduit and communicating with said second conduit between said second outlet port and said valve in said second conduit, and-a valve controlling fluid flow in either direction through said third conduit.

2. In a device of the class described, a first cylinder, a first piston in said cylinder, a second cylinder, a second piston in said second cylinder, driving means interposed between said cylinders,

a third cylinder spaced from said driving means by said first cylinder, a third piston in said third cylinder, all of said cylinders being aligned, a piston rod carrying said second piston and connected to said driving means, apiston rod carrying said first and third pistons and connected to said driving means,-valved inlet and outlet ports ajacent each end of each of said cylinders, a first branched conduit leading from a fiuid source to both inlet ports of said first cylinder, a second branched conduit leading from both outlet ports of said first cylinder to theinlet port of said second cylinder adjacent said driving means,

a third branched conduit leading from a fluid source to the inlet port of said second cylinder remote from said driving means and, through a check valve, to the inlet port of said second cylinder adjacent said driving means, a fourth branched conduit leading from the outlet port of said second cylinder adjacent said driving means, and, through a check valve, from the outlet port of said second cylinder remote from said driving means, to the inlet portof said third cylinder remote from said driving means, a fifth conduit leading from a fluid source to said fourth conduit, a sixth conduit leading from a fluid source to the inlet port of said third cylinder adjacent said driving means, a seventh conduit leading from the outlet port of said third cylinder remote from said driving means to said sixth conduit, and an eighth conduit leading from the outlet port of said third cylinder adjacent said driving means. I

3. In a device of the class described, a first cylinder, a first piston in said cylinder, a second cylinder, a second piston in said second cylinder, driving means interposed between said cylinders, a third cylinder spaced from said driving means by said first cylinder, a third piston in said third cylinder, all of said cylinders being aligned a piston rod carrying said second piston and connected to said driving means, a piston rod carrying said first and third pistons and connected to said driving means, valved inlet and outlet ports adjacent each end of each of said cylinders, a first branched conduit leading from a fluid source to both inlet ports of said first cylinder, a second branched conduit leading from. both outlet ports of said first cylinder to the inlet port of said second cylinder adjacent said driving means, a third branched conduit leading from a fluid source to the inlet port of said second cylinder remote from said driving means and, through a check valve, to the inlet port of said second cylinder adjacent said driving means, a fourth branched conduit leading from the outlet port of said second cylinder adjacent said driving means, and, through a check valve, from the outlet port of said second cylinder remote from said driving means, to the inlet port of said third cylinder remote from said driving means, a valve-controlled passage providing, at times, communication between a point in said third conduit intermediate the check valve therein and the inlet port of said second cylinder adjacent said driving means, and a point in said fourth conduit intermediate the outlet port of said second cylinder remote from said driving means and the check valve in said fourth conduit, a

fifth conduit leading from a fluid source to said.

fourth conduit, a sixth conduit leading from a fluid source to the inlet port of said third cylinder adjacent said driving means, a seventh conduit leading from the outlet port of said third cylinder remote from said driving means to said sixth conduit, and an eighth conduit leading from the outlet port of said third cylinder adjacent said driving means.

4. In a device of the class described, a first cylinder, a first piston in said cylinder, a second cylinder, a second piston in said second cylinder, driving means interposed between said cylinders, a third cylinder spaced from said driving means by said first cylinder, a third piston in said third cylinder, all of said cylinders being aligned, a piston rod carrying said second piston and connected to said driving means, a piston rod carrying said first and third pistons and connected to said driving means, valved inlet and outlet ports adjacent each end of each of said cylinders, a first branched conduit leading from a fluid source to both inlet ports of said first cylinder, a second branched conduit leading from both outlet ports of said first cylinder to the inlet port of said second cylinder adjacent said driving means, a thirdbranched conduit leading from afiuidsource to the inlet port of said second cylinder remote from said driving means and, through a check valve, to the inlet port of said second cylinder adjacent said driving means, a fourth branched conduit leading from the outlet port of said second cylinder adjacent said driving means, and, through a check valve, from the outlet port of said second cylinder remote from said driving means, to the inlet port of said third cylinder remote from said driving means, a fifth conduit leading from a fluid source to said fourth conduit, a sixth conduit leading from a fluid source to the inlet port of said third cylinder adjacent said driving means, a seventh conduit leading from the outlet port of said third cylinder remote from said driving means to said sixth conduit, and an eighth conduit leading from the outlet port of said third cylinder adjacent said driving means, and manually operable means associated with said inlet valve of said second cylinder remote from said driving means and with said inlet valve of said third cylinder remote from said driving means, and operable independently to hold said respective valves open, at Will.

5. In a device of the class described, a first cylinder, a first piston in said cylinder, a second cylinder, a second piston in said second cylinder, driving means interposed between said cylinders, a third cylinder spaced from said driving means by said first cylinder, a third piston in said third cylinder, all of said cylinders being aligned, a piston rod carrying said second piston and connected to said driving means, a piston rod carrying said first and third pistons and connected to said driving means, valved inlet and outlet ports adjacent each end of each of said cylinders, a first branched conduit leading from a fiuid source to both inlet ports of said first cylinder, a second branched conduit leading from both outlet ports of said first cylinder to the inlet port of said second cylinder adjacent said driving means, a thirdbranched conduit leading from afiuidsource to the inlet port of said second cylinder remote from said driving means and, through a check valve, to the inlet port of said second cylinder adjacent said driving means, a fourth branched conduit leading from the outlet port of said second cylinder adjacent said driving means, and,

through a check valve, from the outlet port of said second cylinder remote from said driving means, to the inlet port of said third cylinder remote from said driving means, and a fifth conduit leading from the outlet port of said third cylinder remote from said driving means to the inlet port of said third cylinder adjacent said driving means.

' FRANKLIN B.'HUNT.

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