Molar Transfer Device

Abstract

A device for use in analytical instruments is provided that provides continuous transfer of known molar amounts of gas from a source having an unknown gas mixture and fluctuating pressure. In addition to the upstream and downstream paths of a typical flow control device, the device has a midstream path for introducing a carrier gas at a known high pressure. The device has at least three equal-volume ballast vessels and a valve arrangement for cycling the ballast through at least three states: filled, equilibrated, and empty. The ballast is filled with upstream gas, pressurized and equilibrated at midstream pressure, and emptied into the downstream path. The cycle of each ballast is timed with the other ballasts in a phase relationship to ensure relatively uninterrupted flow. As one fills, the other equilibrates and the other empties.

Description

[Technical Field]

[0001] The present invention relates to a molar transfer device, in particular to a molar transfer device for an elemental analyzer. [Background technology]

[0002] The determination of elements such as carbon, hydrogen, and nitrogen in organic materials is desirable for many reasons. In recent years, the food market has become interested in determining the amount of protein in a sample, which can be determined by the nitrogen content. Therefore, determining nitrogen is important in providing useful information to the nutrition market. Carbon-to-hydrogen ratios are desirable in characterizing coal and coke samples, as are carbon, hydrogen, and nitrogen ratios in various other organic materials. Therefore, elemental analyzers have been used for these and other applications for some time.

[0003] In the present elemental analyzer, a combustion or reduction furnace may be provided to combust or reduce the sample material so that the combustion gases produced thereby may be analyzed. One such analyzer system is described in commonly assigned U.S. Patent No. 7,070,738. U.S. Patent Nos. 7,497,991, 4,622,009, 6,291,802, and 6,270,727 also disclose combustion system components.

[0004] Some elemental analyzers feature a carrier gas sweeping through a combustion or reduction furnace, carrying gases evolving from the sample material at unknown rates. At other locations along the flow path, selected gases are removed or transformed. It is often necessary or desirable to control the flow rate in regions downstream of such events, where the relative concentrations of gas components are unknown and fluctuating. The variation in gas composition poses a problem for conventional flow controllers, which rely on at least one gas property, such as viscosity or thermal conductivity, remaining constant. These properties change as the gas mixture changes, thereby affecting the flow rate.

[0005] U.S. Patent No. 4,525,328 describes an analyzer that abandons attempts to control flow rate and instead collects combustion gases from sample combustion in a large ballast vessel. The minimum oxygen flow rate and maximum sample burn time required to support combustion determine the ballast size requirements. For samples requiring shorter burn times, combustion is completed long before the ballast is filled. The remainder of the ballast is filled with expensive, high-purity oxygen carrier gas, which dilutes the analytical gas and worsens detection limits. After filling, the vessel is equilibrated, and an aliquot is taken from the contents for further downstream analysis. The ballast is then emptied and purged. Analysis times can be two to four times longer than the burn time for some samples. This method provides repeatable results but suffers in terms of sensitivity, cost, and speed.

[0006] U.S. Patent No. 9,435,758 discloses a bidirectional ballast system that extends the ballast idea by cyclically filling one side of a smaller ballast volume and emptying the other. This approach reduces gas consumption, dilution, and analysis time, but does not allow for complete mixing of the gases before emptying, and upstream combustion events can cause ballast pressure fluctuations that reduce accuracy.

[0007] Various pumps are used to deliver combustion gases at a constant rate. However, variations in the gas mixture and therefore gas viscosity cause the pressure drop at the pump inlet to vary. This and the pressure variations cause the pump to deliver gases at varying rates during the analysis. Summary of the Invention

[0008] The disclosed invention overcomes the above-mentioned limitations of transferring a known molar amount of gas from an upstream source with an unknown mixture of gases at varying pressures. The device has three gas connections: upstream, downstream, and midstream. The midstream path introduces a carrier gas at an elevated pressure relative to the upstream pressure. The device has at least three rechargeable ballasts and a valve arrangement for cyclically directing the three gas streams to the ballasts. Means for measuring or controlling the device temperature are also provided.

[0009] Each ballast cycles through at least three states: filled, equilibrium, and empty. The ballasts are cycled phase-wise relative to one another so that upstream and downstream flow rates are relatively uninterrupted. In the filled state, gas from the upstream path fills the ballast. In the equilibrium state, the carrier gas pressurizes the ballast to a reproducible level while the gases in the ballast mix. In the final state, the contents of the ballast are emptied into the downstream path.

[0010] The ideal gas equation of state states that if the pressure, temperature, and volume are known, the number of moles transferred per cycle of the device is known regardless of the gas mixture.

[0011] According to one aspect of the present invention, there is provided a mole transfer device comprising a ballast mechanism including a first ballast cylinder, a passive piston provided in the first ballast cylinder that divides the first ballast cylinder into a first ballast and a second ballast, a first ballast port that allows gas to flow into and out of the first ballast, and a second ballast port that allows gas to flow into and out of the second ballast. The molar transfer device further comprises a valve device including a valve body including an upstream gas port, a midstream gas port, and a downstream gas port, and a valve included in the valve body coupled to the first ballast port and the second ballast port for sequentially (a) directing gas from the upstream gas port into the first ballast while emptying the second ballast into the downstream gas port, (b) coupling the first ballast port to the midstream gas port to equilibrate the gas in the first ballast, (c) directing gas from the upstream gas port into the second ballast while emptying the first ballast into the downstream gas port, and (d) coupling the second ballast port to the midstream gas port to equilibrate the gas in the second ballast.

[0012] According to another aspect of the present invention, there is provided a mole transfer device including a ballast mechanism and a rotary valve, the ballast mechanism including a first ballast cylinder, a passive piston disposed in the first ballast cylinder that divides the first ballast cylinder into a first ballast and a second ballast, a first ballast port that allows gas to flow into and out of the first ballast, and a second ballast port that allows gas to flow into and out of the second ballast.The rotary valve includes a valve body having a cylindrical bore communicating with an upstream gas port, a midstream gas port, and a downstream gas port; a rotating cylindrical chamber positioned within the cylindrical bore to rotate therein, the rotating cylindrical chamber having a first axial port, a second axial port, a third axial port, a first radial port communicating with the first axial port, a second radial port communicating with the second axial port, and a third radial port communicating with the third axial port, the outer cylindrical wall of the rotating chamber being spaced from the inner wall of the cylindrical bore to allow the first radial port, the second radial port, and the third radial port to communicate with the upstream gas port, the midstream gas port, and the downstream gas port, respectively, regardless of the rotational position of the rotating cylindrical chamber; and a rotating cylindrical chamber connected to a first ballast port depending on the rotational position of the rotating cylindrical chamber, and the first axial port, the second axial port, and the third radial port and the third axial port, and a second cap port connected to the second ballast port and extending inward to align with another one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; and a motor that rotates the rotating cylindrical chamber to different rotational positions to change which of the first axial port, the second axial port, and the third axial port are aligned with the first cap port and the second cap port, so that each of the first and second ballasts is sequentially filled with gas from the upstream gas stream, equilibrated with the midstream gas stream, and emptied into the downstream gas stream, such that as the first ballast is filled, the second ballast is emptied, and as the second ballast is filled, the first ballast is emptied.

[0013] According to another aspect of the present invention, there is provided a mole transfer device comprising a ballast mechanism including a first ballast cylinder, a passive piston provided in the first ballast cylinder that divides the first ballast cylinder into a first ballast and a second ballast, a first ballast port that allows gas to flow into and out of the first ballast, and a second ballast port that allows gas to flow into and out of the second ballast.The molar transfer device is a rotary valve including a valve body having a cylindrical bore and a rotating cylindrical chamber positioned in the cylindrical bore for rotation therein, the rotating cylindrical chamber having a first port, a second port, a third port, a fourth port in communication with the first port, a fifth port in communication with the second port, and a sixth port in communication with the third port, the rotating cylindrical chamber having a first end and a second end at opposite ends of the cylinder, the first port opens at a first end, the fourth, fifth, and sixth ports open at a second end, the second end having a first annular groove in communication with the fourth port and one of the upstream gas port, the midstream gas port, and the downstream gas port regardless of the rotational position of the rotating cylindrical chamber, the second end further including a second annular groove in communication with the fifth port and another one of the upstream gas port, the midstream gas port, and the downstream gas port regardless of the rotational position of the rotating cylindrical chamber, a first valve end cap including: a rotating cylindrical chamber having a first port opening at a center of a second end and communicating with yet another one of the upstream gas port, the midstream gas port, and the downstream gas port; a first cap port extending internally to align with one of the first port, the second port, and the third port depending on a rotational position of the rotating cylindrical chamber; and a second cap port extending internally to align with another one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber; and a motor that rotates the rotating cylindrical chamber to different rotational positions to change which of the first port, the second port, and the third port are aligned with the first cap port and the second cap port, such that each of the first cap port and the second cap port is sequentially connected to the upstream gas port, the midstream gas port, and the downstream gas port.

[0014] According to another aspect of the present invention, a ballast mechanism includes a first ballast cylinder; a passive piston disposed in the first ballast cylinder, the passive piston dividing the first ballast cylinder into a first ballast and a second ballast; a first ballast port allowing gas to flow into and out of the first ballast; a second ballast port allowing gas to flow into and out of the second ballast; a second ballast cylinder; a second passive piston disposed in the second ballast cylinder, the second passive piston dividing the second ballast cylinder into a third ballast and a fourth ballast; a third ballast port allowing gas to flow into and out of the second ballast; and a fourth ballast port allowing gas to flow into and out of the fourth ballast.

[0015] According to another aspect of the present invention, a rotary valve includes a valve body having a cylindrical bore in communication with an upstream gas port, a midstream gas port, and a downstream gas port; and a rotating cylindrical chamber positioned within the cylindrical bore for rotation therein, the rotating cylindrical chamber having a first axial port, a second axial port, a third axial port, a first radial port in communication with the first axial port, a second radial port in communication with the second axial port, and a third radial port in communication with the third axial port, an outer cylindrical wall of the rotating chamber spaced from an inner wall of the cylindrical bore to allow the first radial port, the second radial port, and the third radial port to communicate with the upstream gas port, the midstream gas port, and the downstream gas port, respectively, regardless of the rotational position of the rotating cylindrical chamber. a first valve end cap including a first cap port extending therein to align with one of a first axial port, a second axial port, and a third axial port depending on the rotational position of the chamber, and a second cap port extending therein to align with another one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; and a motor that rotates the rotating cylindrical chamber to different rotational positions to change which of the first axial port, the second axial port, and the third axial port are aligned with the first cap port and the second cap port, such that each of the first cap port and the second cap port is sequentially connected to an upstream gas port, a midstream gas port, and a downstream gas port.

[0016] According to another aspect of the present invention, a rotary valve includes a valve body having a cylindrical bore and a rotating cylindrical chamber positioned in the cylindrical bore for rotation therein, the rotating cylindrical chamber having a first port, a second port, a third port, a fourth port in communication with the first port, a fifth port in communication with the second port, and a sixth port in communication with the third port, the rotating cylindrical chamber having a first end and a second end at opposite ends of the cylinder, the first port opens at a first end, the fourth, fifth, and sixth ports open at a second end, the second end having a first annular groove in communication with the fourth port and one of the upstream gas port, the midstream gas port, and the downstream gas port regardless of the rotational position of the rotating cylindrical chamber, the second end further including a second annular groove in communication with the fifth port and another one of the upstream gas port, the midstream gas port, and the downstream gas port regardless of the rotational position of the rotating cylindrical chamber, and the sixth port a first valve end cap including a rotating cylindrical chamber having a port opening at a center of a second end and communicating with yet another one of an upstream gas port, a midstream gas port, and a downstream gas port; a first cap port extending inwardly to align with one of the first port, the second port, and a third port depending on a rotational position of the rotating cylindrical chamber; and a second cap port extending inwardly to align with another one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber; and a motor that rotates the rotating cylindrical chamber to different rotational positions to change which of the first port, the second port, and the third port are aligned with the first cap port and the second cap port, such that each of the first cap port and the second cap port is sequentially connected to the upstream gas port, the midstream gas port, and the downstream gas port.

[0017] These and other features, objects, and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0018] In the drawings, [Figure 1] FIG. 1 is a perspective view of a molar transport device. [Figure 2] FIG. 2 is a perspective view of a ballast mechanism used in the molar transport device shown in FIG. 1. [Figure 3] FIG. 2 is a perspective view of a rotary valve used in the molar transfer device shown in FIG. 1. [Figure 4] FIG. 4 is a perspective view of a rotating cylindrical chamber used in the rotary valve shown in FIG. 3. [Figure 5] FIG. 4 is a partial cross-sectional perspective view of the rotary valve shown in FIG. 3. [Figure 6] FIG. 4 is a perspective view of a valve body used in the rotary valve shown in FIG. 3. [Figure 7A] 2A-2C are schematic diagrams of the molar transport device shown in FIG. 1 during a series of operating cycles. [Figure 7B] 2A-2C are schematic diagrams of the molar transport device shown in FIG. 1 during a series of operating cycles. [Figure 7C] 2A-2C are schematic diagrams of the molar transport device shown in FIG. 1 during a series of operating cycles. [Figure 7D] 2A-2C are schematic diagrams of the molar transport device shown in FIG. 1 during a series of operating cycles. [Figure 7E] 2A-2C are schematic diagrams of the molar transport device shown in FIG. 1 during a series of operating cycles. [Figure 7F] 2A-2C are schematic diagrams of the molar transport device shown in FIG. 1 during a series of operating cycles. [Figure 7G] 2A-2C are schematic diagrams of the molar transport device shown in FIG. 1 during a series of operating cycles. [Figure 7H] 2A-2C are schematic diagrams of the molar transport device shown in FIG. 1 during a series of operating cycles. [Figure 8] 2 is a perspective view of an alternative rotary valve that can be used in the molar transfer device shown in FIG. 1. [Figure 9]FIG. 9 is a partial cross-sectional perspective view of the rotary valve shown in FIG. 8. [Figure 10] FIG. 9 is a partial cross-sectional perspective view of the rotary valve shown in FIG. 8. [Figure 11] FIG. 9 is a perspective view of a rotating cylindrical chamber used in the rotary valve shown in FIG. 8. [Figure 12] FIG. 12 is a perspective view of the rotating cylindrical chamber shown in FIG. 11. [Figure 13] FIG. 12 is a bottom view of the rotating cylindrical chamber shown in FIG. 11. [Figure 14] FIG. 14 is a cross-sectional view of the rotating cylindrical chamber shown in FIG. 11 taken along line XIV-XIV. [Figure 15] FIG. 12 is a cross-sectional view of the rotating cylindrical chamber shown in FIG. 11 taken along line XV-XV. [Figure 16] FIG. 9 is an exploded perspective view of the rotary valve shown in FIG. 8. [Figure 17] FIG. 2 is a block diagram of an elemental analyzer using the molar transfer device shown in FIG. 1. [Figure 18] 10 is a graph showing sample analysis over time of a device using one large 4.5 liter ballast and a device with a 200 ml ballast. DETAILED DESCRIPTION OF THE INVENTION

[0019] Referring initially to FIG. 1 , a mole transfer device 10 is shown. In one embodiment, the mole transfer device 10 is used in an elemental combustion analyzer 200 (FIG. 8) with an oxygen carrier gas. The mole transfer device 10 has a ballast mechanism 20 including at least a first ballast cylinder 21 with a movable piston 23. The piston 23 divides the first ballast cylinder 21 into individual ballasts, thereby providing a first ballast 25 and a second ballast 26. The second ballast cylinder 22 may have a movable piston 24 that divides the second ballast cylinder 22 into a third ballast 27 and a fourth ballast 28. The first and second ballast cylinders 21 and 22 may be of equal volume.

[0020] Molar transfer device 10 is connected to three gas streams: upstream gas stream A, midstream gas stream B, and downstream gas stream C. Rotary valve 50 is used to cyclically connect the three streams A, B, and C to four ballasts 25, 26, 27, and 28. Molar transfer device 10 can be placed in a constant temperature oven so that the molar amount of gas transferred per cycle of the device is constant.

[0021] Ballast Description 1 and 2, the ballast system 20 includes a first ballast end cap 30 and a second ballast end cap 32 with an internal nozzle for dispersing gas entering the volume. A first ballast port 33a allows gas to enter and exit the first ballast 25, a second ballast port 34a allows gas to enter and exit the second ballast 26, a third ballast port 35a allows gas to enter and exit the third ballast 27, and a fourth ballast port 36a allows gas to enter and exit the fourth ballast 28. The first and third ballast ports 33a and 35a connect nozzles to the exterior of the first ballast end cap 30, where connectors 33 and 35 may be provided for connection to a rotary valve 50. Similarly, second ballast port 34a and fourth ballast port 36a connect the nozzle to the exterior of second ballast end cap 30, where connectors 34 and 36 may be provided for connection to rotary valve 50.

[0022] Piston velocity is controlled by the pressure difference between the upstream and downstream paths. As the pistons 23, 24 move within the cylinders 21, 22, the ballast 25, 27 on one side fills and the ballast 26, 28 on the other side empties. The upstream pressure is held relatively constant, but this pressure is expected to fluctuate somewhat due to combustion events. The midstream carrier pressure is precisely maintained at a level above the maximum expected upstream pressure so that it always determines the equilibrium pressure of the ballast. An adjustable restriction, such as a proportional valve, in the downstream path is present to control the piston velocity and, thereby, the desired filling rate of the molar transfer device 10. Valve timing is determined to transfer the desired molar amount of gas per unit time. The rotary valve 50 is intended to cycle immediately after the pistons 23, 24 reach the end of their travel. Due to upstream pressure fluctuations during combustion, the pistons 23, 24 may not reach the end of their travel before the valve 50 is cycled. In the valve, means are provided to allow the pistons 23, 24 to complete their movement during equilibrium without affecting the molar transport rate of the device 10.

[0023] Ballasts 25, 26, 27, and 28 cycle through four states: fill, balance, empty, and standby. Rotary valve 50 arranges ballasts 25, 26, 27, and 28 in a phase relationship with one another so that there is always one fill, one balance, one empty, and one standby.

[0024] Ballast size is determined by the oxygen flow rate required to sustain combustion and the time required to thoroughly mix the gases. One analyzer requires an oxygen flow rate of 5 lpm, and the gases are considered mixed after 5 seconds. Because the shortest burn time for this analyzer is approximately 10 seconds, the volume is filled with approximately half the amount of combustion gas at peak combustion to avoid over-dilution. The resulting ballast volume is approximately 0.4 liters.

number

[0025] If one large ballast (e.g., 4.5 liters) is used to collect all of the products of a longer combustion event, the ballast may be larger than needed when the combustion event is shorter, which then results in dilution of the collected gases with the carrier gas (typically high-purity oxygen). Replacing the single large ballast with a smaller ballast (e.g., 200-400 ml) prevents dilution and reduces the amount of expensive oxygen required.

[0026] Pistons 23 and 24 may be constructed of a low friction material so that the pistons do not require seals or grease, thereby reducing maintenance costs.

[0027] Rotary Valve Description Rotary valve 50 is used to cyclically direct gas between three streams A, B, and C and four ballasts 25, 26, 27, and 28. As shown in Figures 1, 3, and 5, rotary valve 50 consists of a rotating cylindrical chamber 60, a valve body 70, a first valve end cap 80, a second valve end cap 90, a first end seal 85, a second end seal 95, rotary seals 71, 72, 73, 74, and a motor 98.

[0028] As shown in FIG. 4, the rotating cylindrical chamber 60 has flat end faces 61 and 62 with three internal axial ports 63, 64, and 65 extending axially the length of the chamber 60 and opening on both chamber faces 61 and 62. The axial ports 63, 64, and 65 are located at fixed radii from the centers of the faces 61 and 62 and are positioned 90° from each other. Channels 66 and 67 on each cylinder face 61 and 62 extend the third axial port 65 to a fourth 90° position 68. This feature allows the pistons 23 and 24 to complete their travel during equilibrium, as needed. There is a non-circular feature 69 in the center of one cylinder face 61 designed to engage a similarly shaped mating coupling on the shaft of the motor 98.

[0029] 4 and 5, three radial ports 63a, 64a, and 65a in the chamber sidewall intersect with three axial ports 63, 64, and 65, respectively. Radial ports 63a, 64a, and 65a are located in spaced-apart relationship along the length of cylindrical chamber 60 and align with similarly spaced ports 75, 76, and 77 on valve body 70, which connect to three gas paths A, B, and C, respectively. This arrangement allows gas entering radial port 63a or 64a to flow to either chamber end face 61, 62, and gas exiting radial port 65a to flow from either chamber end face 61, 62.

[0030] Valve body 70 has a large cylindrical bore 78 to receive rotary chamber 60. Three radial ports 75, 76, and 77 in valve body 70 align with three radial ports 63a, 64a, and 65a on chamber 60 and provide connection to three gas streams A, B, and C. There are four rotary seals 71, 72, 73, and 74 located along the length of bore 78 that seal the three radial ports 63a, 64a, and 65a from each other and from the outside environment. These rotary seals 71, 72, 73, and 74 also center chamber 60 inside bore 78. Bore 78 is designed to allow the three gas streams to flow easily between the interior of valve body 70 and rotary chamber 60. In this way, regardless of the rotational position of chamber 60, upstream gas may flow from the first radial port 75 of the valve body 70 to the first radial port 63a and therefore to the first axial port 63 of chamber 60, midstream gas may flow from the second radial port 76 of the valve body 70 to the second radial port 64a and therefore to the second axial port 64 of chamber 60, and downstream gas may flow from the third axial port 65 to the third radial port 65a and therefore to the third radial port 77 of the valve body 70.

[0031] The rotating cylindrical chamber 60 is axially retained by a first valve end cap 80 and a second valve end cap 90, both of which are fastened to the valve body 70. As shown in FIGS. 1 and 3 , the first valve end cap 80 has a first cap port 81 and a second cap port 82 at locations that interconnect with any one of the axial ports 63, 64, and 65 of the rotating chamber 60. Similarly, the second valve end cap 90 has a third cap port 91 and a fourth cap port 92 at locations that interconnect with any one of the axial ports 63, 64, and 65 of the rotating chamber 60. The cap ports 81, 82, 91, 92 are located 90° apart from each other, and the cap ports 81 and 82 on the first valve end cap 80 are located 180° apart from the cap ports 91 and 92 on the second valve end cap 90. In this manner, axial ports 63 and 64 can be aligned with only one cap port 81, 82, 91, 92 at a time. Cap ports 81, 82, 91, 92 extend to the exterior of caps 80 and 90, where connectors 33, 34, 35, and 36 are provided for connecting the four cap ports 81, 82, 91, 92 to four ballasts 25, 26, 27, and 28. Specifically, as shown in FIG. 1 , first cap port 81 is connected by first connector 33 to first ballast port 33a, and thus to first ballast 25. Third cap port 91 is connected by second connector 34 to second ballast port 34a, and therefore to second ballast 26. Second cap port 82 is connected by third connector 35 to third ballast port 35a, and therefore to third ballast 27. The fourth cap port 92 is connected by the fourth connector 36 to the fourth ballast port 36 a and therefore to the fourth ballast 28 .

[0032] Motor 98 is secured to one of the valve end caps 80, 90. As shown in FIGS. 3-5, in first valve end cap 80 there is a hole 69b (FIG. 3) that aligns with hole 69a (FIG. 5) in first end seal 85 for the motor shaft to engage through non-circular port 69 in the center of rotation chamber 60 (FIGS. 4 and 5).

[0033] As shown in FIG. 5, first and second end seals 85 and 95 between first and second valve end caps 80 and 90 and rotating chamber end faces 61 and 62 are preferably constructed from two materials: an elastomeric material 87 and 97 in contact with the valve end caps 80 and 90, and a low-friction material 86 and 96, such as PTFE, in contact with the rotating chamber end faces 61 and 62. The elastomeric materials 87 and 97 provide a spring force to seal the low-friction sealing surfaces 86 and 96 against the chamber end faces 61 and 62. The end seals 85 and 95 are held between the valve end caps 80 and 90 and the valve body 70 to prevent them from rotating with the chamber 60. Openings 81 a, 82 a, 91 a, and 92 a ( FIG. 6 ) in the end seals 85 and 95 align with the respective cap ports 81, 82, 91, and 92, respectively.

[0034] Although the four cap ports 81, 82, 91, and 92 are disclosed above as being divided between the first and second valve end caps 80 and 90, the cap ports can all be located on the same valve end cap 80 or 90. Furthermore, although the four cap ports 81, 82, 91, and 92 are described and shown as exiting different sides of the valve end caps 80 and 90, the cap ports can all exit on one side. Such modifications may allow for the use of a manifold to connect various components. Some or all of the connectors 33, 34, 35, and 36 may be provided as ports through a common substrate used to form the ballast end caps and rotary valve, eliminating potential leak points.

[0035] Additionally, although the three radial ports 75 , 76 , and 77 are shown on the same side, they may be on different sides of the valve body 70 .

[0036] Although the rotary valve 50 is described and shown in combination with a particular ballast mechanism 20, the rotary valve 50 is a novel structure and may be used with any other ballast mechanism.

[0037] To achieve the functionality of the rotary valve 50 described herein, either 12 two-way valves, 4 three-way valves, or complex stem valves that can result in undesirable dead volume (carryover from the last sample, scaling of the current sample) would be required. The rotary valve 50 provides no dead volume and therefore no carryover from the last sample analyzed. The rotary valve 50 offers several advantages over the prior art in that it eliminates gripping tubes and stem valves that require maintenance.

[0038] Although rotary valve 50 is shown redirecting flow to three gas streams or from three gas streams to four ballasts, the rotary valve may be constructed to connect to any number, N, of gas streams by using N axis ports, or to any number, M, of ballasts or other devices by including M cap ports.

[0039] operation 7A-7H show schematic diagrams of the molar transfer device 10 in various states of operation. In the schematic diagrams, the rotary valve 50 is shown on its side with all four cap ports 81, 82, 91, and 92 shown at one end for ease of explanation of operation.

[0040] 7A shows a first condition in which the first axial port 63 is aligned with the first cap port 81 so that upstream gas flow A from the furnace is directed through the first radial port 75 of the valve body, the first axial port 63, the first cap port 81, and the first ballast port 33a into the first ballast 25. The second axial port 64 is aligned with the fourth cap port 92 so that midstream gas B (such as oxygen) is directed through the second radial port 76 of the valve body 70, the second axial port 64, the fourth cap port 92, and the fourth ballast port 36a into the fourth ballast 28. The third axial port 65 is aligned with the third cap port 91 such that gas empties from the second ballast 26 through the second ballast port 34 a, the third cap port 91, the third axial port 65, and the third radial port 77 of the valve body 70 into the downstream gas flow (or exhaust). Pressure from the upstream gas filling the first ballast 25 pushes the piston 23, which in turn pushes gas out of the second ballast 26. The second cap port 82 is aligned with the channel 66 such that gas empties from the third ballast 27 through the third ballast port 35 a, the second cap port 82, the channel 66, the third axial port 65, and the third radial port 77 of the valve body 70 into the downstream gas flow (or exhaust). Pressure from the midstream gas filling the fourth ballast 25 pushes the piston 24, which in turn pushes gas out of the third ballast 27. Thus, in this first state, the first ballast 25 is filled with upstream gas A, the second and third ballasts 26 and 27 are emptied into downstream gas C, and the fourth ballast 27 is balanced with midstream gas B.

[0041] FIG. 7B shows the molar transfer device 10 when the first ballast 25 is filled with upstream gas A, the second and third ballasts 26 and 27 are completely emptied into downstream gas C, and the fourth ballast 27 is completely equilibrated with midstream gas B.

[0042] During the fill cycle, nozzles in the ballast facilitate mixing as the ballast fills, and exhaust restrictions, such as the use of a proportional valve, can adjust piston speed.

[0043] During the equilibration cycle, the temperature and pressure inside the ballast are equilibrated. As mentioned above, the analyte fill pressure can fluctuate due to external disturbances. The midstream carrier gas pressure can be isolated from these disturbances, thus providing a constant pressure equilibrium that is repeatable within 0.002 psi and 0.1 torr. The midstream carrier gas pressure terminates piston movement, if necessary, limiting analyte dilution. The equilibration cycle also improves gas homogeneity.

[0044] The exhaust cycle empties the ballast into the downstream gas path, where the exhaust path may be restricted to set the piston speed. As described below, the exhaust gas may be sampled by a dosator for nitrogen measurement. The termination cycle terminates the piston pump stroke as needed, leaving the ballast connected to the downstream path so that the ballast can be emptied.

[0045] The motor 98 is activated to rotate the rotary chamber 50 a quarter turn (or 90 degrees), as shown in FIG. 7C. The motor is activated at preset intervals, such as 3 seconds. The intervals should be selected to allow sufficient time for equilibration. In this state, the first axial port 63 is aligned with the second cap port 82 so that upstream gas flow A from the furnace is directed through the first radial port 75 of the valve body, the first axial port 63, the second cap port 82, and the third ballast port 35a into the third ballast 27. The second axial port 64 is aligned with the first cap port 81 so that midstream gas B (e.g., oxygen) is directed through the second radial port 76 of the valve body 70, the second axial port 64, the first cap port 81, and the first ballast port 33a into the first ballast 25. The third axial port 65 is aligned with the fourth cap port 92 so that gas empties from the fourth ballast 28 through the fourth ballast port 36 a, the fourth cap port 92, the third axial port 65, and the third radial port 77 of the valve body 70 into the downstream gas flow (or exhaust). Pressure from the upstream gas filling the third ballast 27 pushes the piston 24, which in turn forces gas out of the fourth ballast 28. The third cap port 91 is aligned with the channel 66 so that gas empties from the second ballast 26 through the second ballast port 34 a, the third cap port 91, the channel 66, the third axial port 65, and the third radial port 77 of the valve body 70 into the downstream gas flow (or exhaust). Pressure from the midstream gas filling the first ballast 25 pushes the piston 23, which in turn pushes any remaining gas out of the second ballast 26. Thus, in this second state, the third ballast 27 is filled with upstream gas A, the second and fourth ballasts 26 and 28 are emptied into downstream gas C, and the first ballast 25 is balanced with midstream gas B.

[0046] FIG. 7D shows the mole transfer device 10 when the first ballast 25 is fully balanced with midstream gas B, the second and fourth ballasts 26 and 28 are fully emptied into downstream gas C, and the third ballast 27 is fully filled with upstream gas A.

[0047] The motor 98 is then actuated to rotate the rotary chamber 50 by 90 degrees, as shown in FIGURE 7E. In this state, the first axial port 63 is aligned with the third cap port 91 so that upstream gas flow A from the furnace is directed through the first radial port 75 of the valve body, the first axial port 63, the third cap port 91, and the second ballast port 34a into the second ballast 26. The second axial port 64 is aligned with the second cap port 82 so that midstream gas flow B is directed through the second radial port 76 of the valve body 70, the second axial port 64, the second cap port 82, and the third ballast port 35a into the third ballast 27. The third axial port 65 is aligned with the first cap port 81 such that gas empties from the first ballast 25 through the first ballast port 33 a, the first cap port 81, the third axial port 65, and the third radial port 77 of the valve body 70 into the downstream gas flow (or exhaust). Pressure from the upstream gas filling the second ballast 26 pushes the piston 23, which in turn forces gas out of the first ballast 25. The fourth cap port 92 is aligned with the channel 66 such that gas empties from the fourth ballast 28 through the fourth ballast port 36 a, the fourth cap port 92, the channel 66, the third axial port 65, and the third radial port 77 of the valve body 70 into the downstream gas flow. Pressure from midstream gas filling third ballast 27 pushes piston 24, which in turn pushes any remaining gas out of fourth ballast 28. Thus, in this third state, second ballast 26 is filled with upstream gas A, first and fourth ballasts 25 and 28 are emptied into downstream gas C, and third ballast 27 is balanced with midstream gas B.

[0048] FIG. 7F shows the mole transfer device 10 when the third ballast 27 is fully balanced with midstream gas B, the first and fourth ballasts 25 and 28 are fully emptied into downstream gas C, and the second ballast 27 is fully filled with upstream gas A.

[0049] The motor 98 is then activated again to rotate the rotary chamber 50 by 90 degrees, as shown in FIG. 7G. In this state, the first axial port 63 is aligned with the fourth cap port 92 so that upstream gas flow A from the furnace is directed through the first radial port 75 of the valve body, the first axial port 63, the fourth cap port 92, and the fourth ballast port 36a into the fourth ballast 28. The second axial port 64 is aligned with the third cap port 91 so that midstream gas flow B is directed through the second radial port 76 of the valve body 70, the second axial port 64, the third cap port 91, and the second ballast port 34a into the second ballast 26. The third axial port 65 is aligned with the second cap port 82 so that gas empties from the third ballast 27 through the third ballast port 35 a, the second cap port 82, the third axial port 65, and the third radial port 77 of the valve body 70 into the downstream gas flow (or exhaust). Pressure from the upstream gas filling the fourth ballast 28 pushes the piston 24, which forces gas out of the third ballast 27. The first cap port 81 is aligned with the channel 66 so that gas empties from the first ballast 25 through the first ballast port 33 a, the first cap port 81, the channel 66, the third axial port 65, and the third radial port 77 of the valve body 70 into the downstream gas flow. Pressure from the midstream gas filling the second ballast 26 pushes the piston 23, which in turn forces any remaining gas out of the first ballast 25. Thus, in this fourth state, the fourth ballast 28 is filled with upstream gas A, the first and third ballasts 25 and 27 are emptied into downstream gas C, and the second ballast 26 is balanced with midstream gas B.

[0050] FIG. 7H shows the mole transfer device 10 when the second ballast 26 is fully balanced with midstream gas B, the first and third ballasts 25 and 27 are fully emptied into downstream gas C, and the fourth ballast 28 is fully filled with upstream gas A.

[0051] The above process may then be repeated as many times as desired to transport the fully combusted gases from the furnace. Below is a state table for the four states above. [Table 1]

[0052] Note that states 1 and 5 are the same as states 2 and 6. The six states are shown to illustrate a complete cycle in which all four ballasts are filled, balanced, then emptied and terminated.

[0053] Because conventional devices use larger ballasts, on the order of 4.5 liters, to collect all of the products of a combustion event, protein analysis can take anywhere from 2 minutes 40 seconds to 3 minutes, depending on the amount of overlap between different samples analyzed. Using the molar transfer device 10 described herein with a smaller ballast, analysis times approach approximately 1 minute. By collecting smaller samples using ballasts 25, 26, 27, and 28, overdilution can be avoided and an improvement in signal-to-noise ratio of approximately 3:1 to 5:1 can be achieved. Furthermore, aliquot size can be reduced, which conserves reagents and can provide better detection limits at the same cost per analysis as conventional techniques, or the same detection limits at a lower cost per analysis.

[0054] Combustion pressures can create different products. For example, at low pressures, CO may be created instead of CO2, while at high pressures, more SO3 may be created than SO2. This is undesirable because the SO2 creates the need to convert SO3, while the SO3 cannot be measured. Thus, the mole transfer device 10 has the advantage of providing a constant combustion pressure of approximately 2 psi, instead of the non-constant pressures of 0-8 psi found in some prior art devices.

[0055] Alternative Rotary Valve Description 8-16 illustrate an alternative design for rotary valve 50'. Rotary valve 50' is similar in function to rotary valve 50. The reference numbers used to describe rotary valve 50' are the same as those for rotary valve 50, except for the prime (') used in each number. Structurally, rotary valve 50' differs in that all four of cap ports 81', 82', 91', and 92' are located in first valve end cap 80' and upstream gas port 75', while midstream gas port 76' and downstream gas port 77' are all located in second valve end cap 90' rather than on the side of valve body 70'. Additional differences will become apparent from the following description.

[0056] The rotary valve 50' includes a valve body 70' having a cylindrical bore 78' and a rotating cylindrical chamber 60' positioned in the cylindrical bore 78' for rotation therein. The rotating cylindrical chamber 60' has a first port 63', a second port 64', a third port 65', a fourth port 63a' in communication with the first port 63', a fifth port 64a' in communication with the second port 64', and a sixth port 65a' in communication with the third port 65'. The rotating cylindrical chamber 60' has a first end 61' and a second end 62' at opposite ends of the cylinder. First, second, and third ports 63', 64', and 65' open at the first end 61', and fourth, fifth, and sixth ports 63a', 64a', and 65a' open at the second end 62'. The second end 62' has a first annular groove 101 that communicates with the sixth port 65a' and one of the upstream gas port 75', midstream gas port 76', and downstream gas port 77', regardless of the rotational position of the rotating cylindrical chamber 60'. In the example shown, the first annular groove 101 communicates with the sixth port 65a' and the downstream gas port 77'. The second end 62' further includes a second annular groove 102 that communicates with the fifth port 64a' and another one of the upstream gas port 75', midstream gas port 76', and downstream gas port 77', regardless of the rotational position of the rotating cylindrical chamber 60'. In the example shown, the second annular groove 102 communicates with the fifth port 64a' and the midstream gas port 76'. The fourth port 63 a′ opens at the center of the second end 62′ and communicates with one of the upstream gas port 75′, the midstream gas port 76′, and the downstream gas port 77′. In the example shown, the second annular groove 102 communicates with the fourth port 63 a′ and the upstream gas port 75′.

[0057] The rotary valve 50' further comprises a first valve end cap 80' including a first cap port 81' extending therein to align with one of the first port 63', the second port 64', and the third port 65' depending on the rotational position of the rotating cylindrical chamber 60', and a second cap port 82' extending therein to align with another one of the first port 63', the second port 64', and the third port 65' depending on the rotational position of the rotating cylindrical chamber 60'. Optionally, the first valve end cap 80' may further include a third cap port 91' extending therein to align with one of the first port 63', the second port 64', and the third port 65' depending on the rotational position of the rotating cylindrical chamber 60', and a fourth cap port 92' extending therein to align with another one of the first port 63', the second port 64', and the third port 65' depending on the rotational position of the rotating cylindrical chamber 60'.

[0058] Unlike rotary valve 50, rotary valve 50' does not include channels 66 and 67 provided to allow pistons 23 and 24 to complete their travel during the equilibrium state, if desired. However, it has been found that pistons 23 and 24 complete their travel during the equilibrium state, thereby eliminating the need for this fourth ("end") state in which the ballast opposite the ballast undergoing balance is connected to downstream port 77'.

[0059] The rotary valve 50' further includes a motor (not shown, but similar to motor 98) that rotates the rotary cylindrical chamber 60' to different rotational positions to change which of the first port 63, the second port 64', and the third port 65' are aligned with the first cap port 81' and the second cap port 82' (and optionally, the second cap port 91' and the fourth cap port 92'), so that each of the cap ports is sequentially connected to the upstream gas port 75', the midstream gas port 76', and the downstream gas port 77'.

[0060] The motor 98 is secured to one of the valve end caps 80', 90'. As shown in the example of Figures 8-16, in the first valve end cap 80', there is a hole 69b' (Figure 16) that aligns with the hole 69a' in the first end seal 85' for the motor shaft to engage through the non-circular port 69' in the center of the rotary chamber 60'.

[0061] As also shown in FIG. 16 , first and second end seals 85′ and 95′ between first and second valve end caps 80′ and 90′ and rotational chamber end faces 61′ and 62′ are preferably constructed from two materials: an elastomeric material 87′ and 97′ in contact with the valve end caps 80′ and 90′, and a low-friction material 86′ and 96′, such as PTFE, in contact with the rotational chamber end faces 61′ and 62′. The elastomeric material 87′ and 97′ provides a spring force to keep the low-friction material 86′ and 96′ pressed against the chamber end faces 61′ and 62′. The end seals 85′ and 95′ are retained between the caps 80′ and 90′ and the valve body 70′ to prevent them from rotating with the chamber 60′. Openings 81a', 82a', 91a', and 92a' (FIG. 16) in end seal 85' align with each of cap ports 81', 82', 91', and 92', respectively. Openings 75a', 76a', and 77a' (FIG. 16) in end seal 95' align with each of upstream gas port 75', midstream gas port 76', and downstream gas port 77', respectively.

[0062] Description of the first use A first application of the mole transfer device 10 is in a combustion analyzer 200, as shown in FIG. 17. The mole transfer device is connected to a combustion furnace 202 to receive upstream gas A therefrom and to a pressurized oxygen carrier gas to receive midstream gas B. The upstream combustion pressure may be set to produce the desired gas composition during combustion, approximately 2 psi for some analyzers. The midstream pressure can be set to 3 psi, sufficiently higher than the maximum expected upstream pressure during sample combustion. The downstream path C exhausts to atmospheric pressure through a proportional valve (not shown) and a dosator 210. The timing of the proportional valve and motor 98 can be adjusted to achieve the desired flow rate.

[0063] The dispenser 210 is preferably a rotary dispenser such as that disclosed in U.S. Patent Application No. 17 / 335,540 (Attorney Docket No. LEC001 P507A), filed June 1, 2021, by Peter Willis et al., entitled "ROTARY DOSING DEVICE." The rotary dispenser 210 is advantageous in that it allows the user to select aliquot sizes in small increments without sacrificing accuracy. Previous dispensers used 3 and 10 cc aliquot loops, limiting the user to selecting only one of these two dose sizes. The rotary dispenser 210 receives a carrier gas, such as He, from a He source 220 via a mass flow controller 222 and delivers the aliquot to a scrubber / detector, such as an IR cell 224, a Cu+ scrubber 226, and a thermal conductivity (TC) cell 232, which may receive He, via a flow controller 230. Scrubber / detectors are generally known in the art.

[0064] In operation, when rotary valve 50 is used, motor 98 aligns ports 63, 64, and 65 and channel 66 with cap ports 81, 82, 91, and 92, and repeatedly rotates chamber 60 to four 90° positions, as described above, to cycle ballasts 25, 26, 27, and 28 through four states. When alternative rotary valve 50' is used, motor 98 aligns ports 63', 64', and 65' with cap ports 81', 82', 91', and 92', and repeatedly rotates chamber 60' to four 90° positions, as described above, to cycle ballasts 25, 26, 27, and 28 through four states.

[0065] Providing a molar transfer device 10 with combustion analyzer 200 allows the user to select the sensitivity of the analyzer. Figure 18 shows a comparative graph of the analysis of samples taken using a single 4.5 liter ballast compared to samples taken using molar transfer devices 10 with 200 ml ballasts 25, 26, 27, and 28. As is readily apparent, the larger ballast effectively averages the analytes over the time it takes to fill and equilibrate the ballast volume, while the smaller ballast takes many separate samples over that time, indicating the extent to which the analyte composition changes over that time.

[0066] Another advantage that combustion analyzer 200 has over prior art combustion analyzers is that it can use low-purity O2 instead of the high-purity O2 used in prior art analyzers to reduce peaks in the blank that would otherwise be caused when using low-purity O2. Lower-purity O2 contains contaminants such as argon, which is difficult to clean and produces larger peaks in the blank. Therefore, higher-purity O2 was used to reduce the presence of argon. However, in current systems, the baseline shifts up, so there is no blank. This allows the use of low-purity O2, saving costs. Furthermore, in some countries, high-purity O2 is not readily available.

[0067] Because the molar transfer device 10 does not dilute the sample with as much O2 as previous devices, less O2 is removed, so the Cu scrubber may be eliminated or otherwise less Cu may be used. As noted above, analysis time may be as fast as 0.5 to 1.5 minutes. This reduces equipment costs and maintenance costs.

[0068] Secondary Use Description In a second application, the device 10 is located downstream of a fusion analyzer or in the secondary inert stream of a combustion analyzer. In this application, the mole transfer device 10 is designed to handle a helium or argon flow rate of approximately 350 ml / min. The device 10 has all the features of the first application, except that in these applications, precise control of piston speed is desirable because the downstream path flows directly to a gas detector. The pistons 23 and 24 can be controlled by various means, but preferably by contactless magnetic actuation. The magnets are driven either by complementary magnets embedded in the pistons 23 and 24 and attached to external mechanical actuators, or by external stationary electrical windings that can be energized in a manner to move the piston magnets in either direction at a constant velocity.

[0069] With smaller ballast volumes, equilibration times are expected to be less than 2 seconds. Therefore, the ballast is designed to fill in approximately 2 seconds, resulting in the following ballast volumes:

number

[0070] In these applications, mass flow controllers or mechanical flow controllers have traditionally played a role. However, when the gas composition changes, these traditional flow controllers change their flow rates, distorting the signal at the detector. The mole transfer device 10 used in these applications does not change its flow rate, so the signal at the detector is not distorted.

[0071] It will be apparent to those skilled in the art, in view of the teachings herein, that multiple bidirectional or unidirectional ballasts can be used to improve analyzer performance, and it will also be apparent to those skilled in the art that these and other modifications can be made without departing from the spirit or scope of the present invention, as defined by the appended claims.

Claims

1. 1. A molar transport device comprising:

1. A ballast mechanism comprising: a first ballast cylinder; a passive piston disposed in the first ballast cylinder, the passive piston dividing the first ballast cylinder into a first ballast and a second ballast; a first ballast port that allows gas to flow into and out of the first ballast; a second ballast port that allows gas to flow into and out of the second ballast; and 1. A valve device, comprising: a valve body including an upstream gas port, a midstream gas port, and a downstream gas port; and a valve device including valves included in the valve body coupled to the first ballast port and the second ballast port for sequentially: (a) directing gas from the upstream gas port into the first ballast while emptying the second ballast into the downstream gas port; (b) coupling the first ballast port to the midstream gas port to equilibrate the gas in the first ballast; (c) directing gas from the upstream gas port into the second ballast while emptying the first ballast into the downstream gas port; and (d) coupling the second ballast port to the midstream gas port to equilibrate the gas in the second ballast.

2. The ballast mechanism a second ballast cylinder; a second passive piston disposed in the second ballast cylinder, the second passive piston dividing the second ballast cylinder into a third ballast and a fourth ballast; a third ballast port that allows gas to flow into and out of the second ballast; 10. The molar transport device of claim 1, further comprising a fourth ballast port that allows gas to flow into and out of said fourth ballast.

3. 3. The molar transfer device of claim 2, wherein the valve is further coupled to the third ballast port and the fourth ballast port to sequentially: (a) directing gas from the upstream gas port into the third ballast while emptying the fourth ballast into the downstream gas port; (b) coupling the third ballast port to the midstream gas port to balance the gas in the third ballast; (c) directing gas from the upstream gas port into the fourth ballast while emptying the third ballast into the downstream gas port; and (d) coupling the fourth ballast port to the midstream gas port to balance the gas in the fourth ballast.

4. 1. A molar transport device comprising:

1. A ballast mechanism comprising: a first ballast cylinder; a passive piston disposed in the first ballast cylinder, the passive piston dividing the first ballast cylinder into a first ballast and a second ballast; a first ballast port that allows gas to flow into and out of the first ballast; a second ballast port that allows gas to flow into and out of the second ballast; and A rotary valve, a valve body having a cylindrical bore communicating with an upstream gas port, a midstream gas port, and a downstream gas port; a rotating cylindrical chamber positioned within the cylindrical bore for rotation therein, the rotating cylindrical chamber having a first axial port, a second axial port, a third axial port, a first radial port in communication with the first axial port, a second radial port in communication with the second axial port, and a third radial port in communication with the third axial port, an outer cylindrical wall of the rotating chamber spaced from the inner wall of the cylindrical bore to allow the first radial port, the second radial port, and the third radial port to communicate with the upstream gas port, the midstream gas port, and the downstream gas port, respectively, regardless of the rotational position of the rotating cylindrical chamber; a first valve end cap including: a first cap port connected to the first ballast port and extending inwardly to align with one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; and a second cap port connected to the second ballast port and extending inwardly to align with another one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; a motor that rotates the rotating cylindrical chamber to different rotational positions to change which of the first axial port, the second axial port, and the third axial port are aligned with the first cap port and the second cap port, such that each of the first and second ballasts is sequentially filled with gas from the upstream gas stream, equilibrated with the midstream gas stream, and emptied into the downstream gas stream, the second ballast emptied as the first ballast is filled, and the first ballast emptied as the second ballast is filled.

5. The ballast mechanism a second ballast cylinder; a second passive piston disposed in the second ballast cylinder, the second passive piston dividing the second ballast cylinder into a third ballast and a fourth ballast; a third ballast port that allows gas to flow into and out of the second ballast; 5. The molar transport device of claim 4, further comprising a fourth ballast port that allows gas to flow into and out of said fourth ballast.

6. The rotary valve is a second valve end cap including: a third cap port connected to the third ballast port and extending inwardly to align with one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; and a fourth cap port connected to the fourth ballast port and extending inwardly to align with another one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; 6. The molar transfer device of claim 5, wherein the motor rotates the rotating cylindrical chamber to four different rotational positions to change which of the first axial port, the second axial port, and the third axial port are aligned with the first cap port, the second cap port, the third cap port, and the fourth cap port, such that each of the first, second, third, and fourth ballasts is sequentially filled with gas from the upstream gas stream, equilibrated with the midstream gas stream, and emptied into the downstream gas stream, the fourth ballast empties as the third ballast is filled, and the third ballast empties as the fourth ballast is filled.

7. 7. The molar transfer device of claim 6, wherein the third axial port includes channels at both ends of the rotating cylindrical chamber for connecting the third axial port, and therefore the downstream gas port, to one of the first, second, third, and fourth cap ports at two of the four rotational positions of the rotating cylindrical chamber.

8. 8. A molar transfer device according to claim 6 or 7, wherein the four rotational positions of the rotating cylindrical chamber are spaced 90 degrees apart.

9. A molar transfer device according to any one of claims 4 to 8, wherein the pressure at the midstream gas port is maintained at a level higher than the maximum expected pressure at the upstream gas port.

10. 1. A molar transport device comprising:

1. A ballast mechanism comprising: a first ballast cylinder; a passive piston disposed in the first ballast cylinder, the passive piston dividing the first ballast cylinder into a first ballast and a second ballast; a first ballast port that allows gas to flow into and out of the first ballast; a second ballast port that allows gas to flow into and out of the second ballast; and A rotary valve, a valve body having a cylindrical bore; a rotating cylindrical chamber positioned in a cylindrical bore for rotation therein, said rotating cylindrical chamber having a first port, a second port, a third port, a fourth port in communication with said first port, a fifth port in communication with said second port, and a sixth port in communication with said third port, said rotating cylindrical chamber having a first end and a second end at opposite ends of said cylinder, said first, second, and third ports open at said first end, and said fourth, fifth, and sixth ports open at said second end, said second end being spaced apart from said rotating cylindrical chamber; a rotating cylindrical chamber having a first annular groove communicating with the fourth port and one of an upstream gas port, a midstream gas port, and a downstream gas port regardless of the rotational position of the rotating cylindrical chamber, the second end further including a second annular groove communicating with the fifth port and another one of the upstream gas port, the midstream gas port, and the downstream gas port regardless of the rotational position of the rotating cylindrical chamber, and the sixth port opening at the center of the second end and communicating with yet another one of the upstream gas port, the midstream gas port, and the downstream gas port; a first valve end cap including: a first cap port extending inwardly to align with one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber; and a second cap port extending inwardly to align with another one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber; a motor that rotates the rotating cylindrical chamber to different rotational positions to change which of the first port, the second port, and the third port are aligned with the first cap port and the second cap port, such that each of the first cap port and the second cap port is sequentially connected to the upstream gas port, the midstream gas port, and the downstream gas port; and a rotary valve including:

11. The ballast mechanism a second ballast cylinder; a second passive piston disposed in the second ballast cylinder, the second passive piston dividing the second ballast cylinder into a third ballast and a fourth ballast; a third ballast port that allows gas to flow into and out of the second ballast; 11. The molar transport device of claim 10, further comprising a fourth ballast port that allows gas to flow into and out of the fourth ballast.

12. The rotary valve is a second valve end cap through which the upstream gas port, the midstream gas port, and the downstream gas port extend; the first valve end cap further includes a third cap port extending inwardly to align with one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber, and a fourth cap port extending inwardly to align with another one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber; 12. The molar transfer device of claim 11, wherein the motor rotates the rotating cylindrical chamber to different rotational positions to change which of the first port, the second port, and the third port are aligned with the third cap port and the fourth cap port, such that each of the third cap port and the fourth cap port is sequentially connected to the upstream gas port, the midstream gas port, and the downstream gas port.

13. 13. The molar transfer device of claim 12, wherein the four rotational positions of the rotating cylindrical chamber are spaced 90 degrees apart.

14. A molar transfer device according to any one of claims 10 to 13, wherein the pressure at the midstream gas port is maintained at a level higher than the maximum expected pressure at the upstream gas port.

15. 1. A ballast mechanism comprising: a first ballast cylinder; a passive piston disposed in the first ballast cylinder, the passive piston dividing the first ballast cylinder into a first ballast and a second ballast; a first ballast port that allows gas to flow into and out of the first ballast; a second ballast port that allows gas to flow into and out of the second ballast; a second ballast cylinder; a second passive piston disposed in the second ballast cylinder, the second passive piston dividing the second ballast cylinder into a third ballast and a fourth ballast; a third ballast port that allows gas to flow into and out of the second ballast; a fourth ballast port that allows gas to flow into and out of the fourth ballast.

16. 16. The ballast arrangement of claim 15, wherein the first ballast, the second ballast, the third ballast, and the fourth ballast have equal volumes.

17. 17. The ballast arrangement of claim 16, wherein the first ballast, the second ballast, the third ballast, and the fourth ballast have a volume of between about 200 ml and 500 ml.

18. A rotary valve, a valve body having a cylindrical bore communicating with an upstream gas port, a midstream gas port, and a downstream gas port; a rotating cylindrical chamber positioned within the cylindrical bore for rotation therein, the rotating cylindrical chamber having a first axial port, a second axial port, a third axial port, a first radial port in communication with the first axial port, a second radial port in communication with the second axial port, and a third radial port in communication with the third axial port, an outer cylindrical wall of the rotating chamber spaced from the inner wall of the cylindrical bore to allow the first radial port, the second radial port, and the third radial port to communicate with the upstream gas port, the midstream gas port, and the downstream gas port, respectively, regardless of the rotational position of the rotating cylindrical chamber; a first valve end cap including: a first cap port extending inwardly to align with one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; and a second cap port extending inwardly to align with another one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; a motor that rotates the rotating cylindrical chamber to different rotational positions to change which of the first axial port, the second axial port, and the third axial port are aligned with the first cap port and the second cap port, such that each of the first cap port and the second cap port is sequentially connected to the upstream gas port, the midstream gas port, and the downstream gas port.

19. 20. The rotary valve of claim 18, wherein each of the first axial port, the second axial port, and the third axial port extends the length of the rotational cylindrical chamber and is open at opposite ends thereof, including a first end and a second end, the first end opening at the first valve end cap.

20. a second valve end cap including: a third cap port extending inwardly to align with the second end of one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; and a fourth cap port extending inwardly to align with the second end of another one of the first axial port, the second axial port, and the third axial port depending on the rotational position of the rotating cylindrical chamber; 20. The rotary valve of claim 19, wherein the motor rotates the rotating cylindrical chamber to different rotational positions to change which of the first axial port, the second axial port, and the third axial port are aligned with the third cap port and the fourth cap port, such that each of the third cap port and the fourth cap port is sequentially connected to the upstream gas port, the midstream gas port, and the downstream gas port.

21. 21. A rotary valve according to any one of claims 18 to 20, further comprising four rotary seals located at spaced locations along the length of the bore to seal the three radial ports from each other and from the external environment.

22. 22. The rotary valve of claim 18, wherein the third axial port includes channels at opposite ends of the rotating cylindrical chamber for connecting the third axial port, and therefore the downstream gas port, to one of the first, second, third, and fourth cap ports at two of the four rotational positions of the rotating cylindrical chamber.

23. A rotary valve, a valve body having a cylindrical bore; a rotating cylindrical chamber positioned in the cylindrical bore for rotation therein, the rotating cylindrical chamber having a first port, a second port, a third port, a fourth port in communication with the first port, a fifth port in communication with the second port, and a sixth port in communication with the third port, the rotating cylindrical chamber having first and second ends at opposite ends of the cylinder, the first, second, and third ports opening at the first end, the fourth, fifth, and sixth ports opening at the second end, and the second end opening to the rotating cylindrical chamber; a rotating cylindrical chamber having a first annular groove communicating with the fourth port and one of an upstream gas port, a midstream gas port, and a downstream gas port regardless of the rotational position of the rotating cylindrical chamber, the second end further including a second annular groove communicating with the fifth port and another one of the upstream gas port, the midstream gas port, and the downstream gas port regardless of the rotational position of the rotating cylindrical chamber, the sixth port opening at the center of the second end and communicating with yet another one of the upstream gas port, the midstream gas port, and the downstream gas port; a first valve end cap including: a first cap port extending inwardly to align with one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber; and a second cap port extending inwardly to align with another one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber; a motor that rotates the rotating cylindrical chamber to different rotational positions to change which of the first port, the second port, and the third port are aligned with the first cap port and the second cap port, such that each of the first cap port and the second cap port is sequentially connected to the upstream gas port, the midstream gas port, and the downstream gas port.

24. a second valve end cap through which the upstream gas port, the midstream gas port, and the downstream gas port extend; the first valve end cap further includes a third cap port extending inwardly to align with one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber, and a fourth cap port extending inwardly to align with another one of the first port, the second port, and the third port depending on the rotational position of the rotating cylindrical chamber; 24. The rotary valve of claim 23, wherein the motor rotates the rotating cylindrical chamber to different rotational positions to change which of the first port, the second port, and the third port are aligned with the third cap port and the fourth cap port, such that each of the third cap port and the fourth cap port is sequentially connected to the upstream gas port, the midstream gas port, and the downstream gas port.

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