DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Status of Claims
This Office Action is responsive to the amendment and remarks filed by Applicant in reply to the Office Action mailed March 31, 2026. In the amendment, claims 1, 13, and 18–20 are amended, claim 21 is newly added, and claims 4–5, 7–12, and 15–16 are canceled. Claims 1–3, 6, 13–14, and 17–21 are pending and are examined herein.
Claim Objections
Claims 2 and 14 are objected to because of the following informalities:
Claim 2 recites "wherein the cryogen includes one of helium, hydrogen, neon, oxygen, nitrogen, and argon," and claim 14 recites "wherein the cryogen is one of helium, hydrogen, neon, oxygen, nitrogen, and argon." Their parent claims introduce the fluid only as "liquid cryogen" (claim 1: "storing liquid cryogen" and "the liquid cryogen"; claim 13: "a liquid cryogen"). For consistency of terminology, "the cryogen" in each of claims 2 and 14 should read --the liquid cryogen--. Appropriate correction is required.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 13, 14, 17, 18, and 21 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 13 recites "opening the gas supply line valve." Claim 13 introduces the valve on the vapor side of the recovery cryostat as "an on-off gas line supply valve" located on "a supply gas line," and the second and fourth steps of the method refer back to that valve as "the on-off gas line supply valve." Claim 13 does not previously recite a "gas supply line valve," and it does not recite a "gas supply line" at all; it recites a "supply gas line." The term "the gas supply line valve" therefore lacks antecedent basis. Because the final step words "supply" and "line” omits the "on-off" qualifier that the amendment added to the two other steps that operate the valve, one of ordinary skill in the art cannot determine with reasonable certainty whether the final step reopens the on-off gas line supply valve closed in the fourth step or operates a different valve located on an unrecited gas supply line. For purposes of examination, "the gas supply line valve" is interpreted as --the on-off gas line supply valve--.
Claims 14, 17, 18, and 21 are also rejected under 35 U.S.C. 112(b) for being dependent upon a rejected claim.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-3, 6, 13-14, and 17-21 are rejected under 35 U.S.C. § 103 as being unpatentable over Wang (US 2009/0049862 A1) in view of Zia (US 2007/0006597 A1) and further in view of Mackey (US 2013/0263609 A1).
In regard to claim 1, Wang teaches a cryogenic system (reliquifier with pulse tube cryocooler, together with cryostat or Dewar 31) for storing liquid cryogen (liquid helium stored within cryostat or Dewar 31) (¶ 0002, 0007, 0018; figs. 2–3), comprising:
a storage tank (cryostat or Dewar 31) that is configured to store the liquid cryogen (liquid helium) (¶ 0007, 0018; fig. 2); and
a recovery cryostat (vacuum insulated sleeve 35 enclosed by vacuum housing 32, with vacuum space 47 therebetween) connected to said storage tank (31, through tube 48 and liquid transfer tube 40) (¶ 0016, 0018; fig. 2), wherein the recovery cryostat (35) is configured to receive vapor (vapor 41 of the boiled-off cryogen) from the storage tank (31) through a supply gas line (tube 48 connecting cryostat 31 to sleeve 35) (¶ 0018; fig. 2), is coupled to a cryocooler (pulse tube cryocooler cold head 36 having first stage cooling station 38, second stage cooling station 46, and condenser 39 mounted to station 46) that is configured to condense into liquid the vapor (41) received from said storage tank (31) (¶ 0016–0018; fig. 2), and is configured to return the liquid to said storage tank (31) through a return liquid line (liquid transfer tube 40; straight transfer tube 50) (¶ 0018, 0020; figs. 2–3).
Wang does not explicitly teach that the storage tank is configured to deliver the liquid cryogen to an external component that comprises a pump and/or a filling container, or that the storage tank is configured to receive, at an upper portion of the storage tank, vapor from the liquid cryogen that boils off in said external component and connecting lines between the external component and the storage tank.
However, Zia teaches a cryogenic tank system comprising a storage tank (primary tank 1 having storage space 11) that is configured to store a liquid cryogen (cryogenic liquid 2, e.g., hydrogen, helium, neon, oxygen, nitrogen, or argon) and to deliver the liquid cryogen (through conduit 3, valve 4, and conduit 5) to an external component (pump 6) that comprises a pump (pump 6, which pumps the liquid to use points including liquid cylinder filling and dewar filling), said storage tank (1) configured to receive, at an upper portion of the storage tank (upper portion of storage space 11, which contains vapor), vapor from the liquid cryogen that boils off in said external component (pump 6) and connecting lines (lines 8, 10) between the external component and the storage tank (liquid vaporized by pump and line heat leak in the course of being processed through the warmer pump 6 is passed in line 8 through valve 9 and in line 10 into the upper portion of storage space 11) (¶ 0002, 0020–0022; sole FIGURE).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the cryogen storage and reliquefaction system of Wang to include a liquid delivery conduit from the storage tank to a pump and a vapor return line that carries the cryogen vaporized in the pump and its connecting lines into the upper, vapor-containing portion of the storage tank as taught by Zia, in order to deliver the stored liquid cryogen to use points such as liquid cylinder filling and dewar filling while returning to the storage tank, rather than losing, the cryogen that is vaporized by pump and line heat leak (Zia ¶ 0002, 0021–0022). One of ordinary skill would have been motivated to make this modification because Wang's stored cryogen is expensive and is recovered by drawing vapor from the storage cryostat through tube 48 into the reliquifier (Wang ¶ 0004, 0007, 0018), so that vapor returned to the tank's vapor space through Zia's return line would be recondensed by the same reliquifier instead of being lost. See MPEP § 2143(I)(G).
Wang as modified by Zia does not explicitly teach that the return liquid line has a liquid line return valve and is connected to a lower portion of the storage tank.
However, Zia further teaches a cryocooler-cooled vessel (auxiliary tank 13, connected through line 17 to cryocooler 16) configured to return liquid cryogen to the storage tank (primary tank 1) through a return liquid line (line 17 through cryocooler 16, and lines 14 and 3) having a liquid line return valve (valve 15), the return liquid line (14, 3) being connected to a lower portion of the storage tank (lower portion of primary tank 1, i.e., the section below the midpoint of the tank, which contains liquid) (¶ 0018, 0023, 0027; sole FIGURE).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the reliquefaction system of Wang, as modified by Zia, to include a return liquid line that is connected to the lower, liquid-containing portion of the storage tank and that has a liquid line return valve as taught by Zia, in order to introduce the cold returned liquid into the lower portion of the storage tank so that the tank contents are kept colder, the tank pressure is kept lower, and vapor loss from the storage tank is reduced (Zia ¶ 0027). One of ordinary skill would have been motivated to make this modification because Wang's returned liquid is freshly condensed at the coldest stage of the cryocooler (Wang ¶ 0018), and Zia teaches that returning such cold liquid through a valved line into the lower portion of the storage tank reduces the very vapor losses that Wang's reliquifier is provided to address (Zia ¶ 0023, 0027; Wang ¶ 0007). See KSR, 550 U.S. 398; MPEP § 2143(I)(G).
Wang as modified by Zia does not explicitly teach that the supply gas line has an on-off gas line supply valve.
However, Mackey teaches a cryogenic system in which two cryogenic vessels (bulk storage tank 3 and dispense tank 7) are connected by a gas line (vapor return line 6) extending between the upper regions of the vessels, the gas line (6) having an on-off gas line valve (valve 26, e.g., a ball valve or shutoff valve, capable of a first configuration allowing vapor to flow through line 6 along path "B" and a second configuration substantially preventing vapor from flowing through line 6), the valve (26) being closed by control system 34 to isolate one vessel from the other (¶ 0045–0046, 0050, 0053, 0055; figs. 1, 3).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the supply gas line of the modified Wang system, to include an on-off valve configurable between a configuration allowing vapor to flow through the line and a configuration substantially preventing vapor from flowing through the line, operated by a control system, as taught by Mackey, in order to selectively permit or stop vapor communication between two interconnected cryogenic vessels and to isolate one vessel from the other (Mackey ¶ 0046, 0053, 0055). One of ordinary skill would have been motivated to make this modification because Wang's reliquifier is a separate vessel connected to the storage cryostat through tube 48, through which vapor is drawn by the low pressure generated by condensation at condenser 39 (Wang ¶ 0018), and an on-off valve in that line is the known means of stopping that flow and isolating the two vessels from each other, yielding the predictable result of controllable vapor communication between them. See MPEP § 2143(I)(A).
In regard to claim 2, the modified Wang teaches the cryogenic system of claim 1, wherein Wang teaches that the cryogen includes one of helium, hydrogen, neon, oxygen, nitrogen, and argon (liquid cryogen, usually helium, stored within cryostat or Dewar 31) (¶ 0002, 0004, 0018).
In regard to claim 3, the modified Wang teaches the cryogenic system of claim 1, wherein Wang teaches that said recovery cryostat (vacuum insulated sleeve 35) is located above said storage tank (cryostat or Dewar 31) such that the condensed liquid returns to the storage tank by gravity (condensed liquid drips from condenser 39 into bottom end 35a of sleeve 35 and flows down through liquid transfer tube 40, 50, a leg of which inserts into neck 31a of cryostat 31) (¶ 0018, 0020, 0024–0025; figs. 2–3, 6).
In regard to claim 6, the modified Wang teaches the cryogenic system of claim 1, wherein Wang teaches that the cryocooler is one of a GM type cryogenic expander, a pulse tube, a Stirling type pulse tube, and a reverse Brayton type of cryocooler (two-stage pulse tube cryocooler having pulse tubes 51, 54 and regenerators 52, 53 powered by compressor 55; alternatively, single-stage pulse tube cryocooler having pulse tube 66 and regenerator 67) (¶ 0016–0017, 0023; figs. 2, 6).
In regard to claim 19, Wang in view of Zia and Mackey teaches the cryogenic system of claim 1, wherein the storage tank (cryostat or Dewar 31, as modified to receive through line 10, at its upper portion, the vapor generated in pump 6 and lines 8, 10) is configured to cause the liquid cryogen in the storage tank to become subcooled by maintaining increased pressure in the storage tank by the boiled-off vapor from the external component (pump 6) and the connecting lines (8, 10) (Wang ¶ 0018; Zia ¶ 0017, 0022; Mackey ¶ 0059–0063, 0071–0072).
Specifically, the storage tank of Wang, as modified by Zia, receives the vapor generated in the pump and its connecting lines into the upper, vapor-containing portion of the tank (Zia ¶ 0022; sole FIGURE), and that vapor leaves the tank only through the supply gas line to the recovery cryostat (Wang ¶ 0018). Mackey evidences that introducing vapor into the upper region of a cryogenic tank increases the pressure inside the tank (¶ 0071–0072), whereas warming of the liquid toward saturation occurs when heated fluid is instead introduced into the lower region of the tank (¶ 0059–0063). Zia defines subcooled liquid as liquid at a temperature lower than the saturation temperature of that liquid for the existing pressure (¶ 0017). Applicant's own specification likewise acknowledges, as the operation of existing systems, that in liquid hydrogen fueling stations the vapor generated in cooling down the liquid pump or the transfer lines is returned to the top of the storage tank, which increases the tank pressure, and that when the tank pressure is raised by introducing vapor above the liquid, the lower layers of liquid remain at approximately their original temperature and are therefore sub-cooled relative to the new, higher pressure (Spec. ¶ 0003, 0005). Statements in an applicant's specification identifying the work of others as prior art are admissions that may be relied upon. See MPEP § 2129. Because the boiled-off vapor enters the vapor space above the liquid, the tank pressure rises while the underlying liquid remains at a temperature below the saturation temperature corresponding to the increased pressure, so that the liquid is subcooled for as long as the increased pressure is maintained. The storage tank of the combination therefore has the structure the claim recites-a storage tank that receives the boiled-off vapor at its upper portion- and the claimed pressure increase and resulting subcooling are the natural result of that structure. Where the claimed and prior art apparatus are identical or substantially identical in structure, a recited property or function is presumed to be present. See In re Best, 562 F.2d 1252, 195 USPQ 430 (CCPA 1977); MPEP §§ 2112.01(I), 2114(I)–(II). Mackey and Applicant's admitted prior art are relied upon here as evidence of the pressure and subcooling effects of vapor introduced above the liquid.
The modification of Wang to return the vapor boiled off in the pump and its connecting lines to the upper portion of the storage tank would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention as taught by Zia, in order to deliver the stored liquid cryogen to use points such as liquid cylinder filling and dewar filling while returning to the storage tank, rather than losing, the cryogen that is vaporized by pump and line heat leak (Zia ¶ 0002, 0021–0022).
In regard to claim 20, Wang in view of Zia and Mackey teaches the cryogenic system of claim 1, including the recovery cryostat (35), the storage tank (31), and the liquid line return valve (valve 15 of Zia) in the return liquid line, as set forth in the rejection of claim 1 above. The modified Wang does not explicitly teach the following limitations:
(a) the recovery cryostat is located at a position that prevents the liquid in the recovery cryostat from being drained back by gravity to the storage tank; and
(b) the liquid line return valve is a check valve.
As to limitation (a), Zia teaches a cryocooler-cooled vessel (auxiliary tank 13) located at a position that prevents the liquid in the vessel from being drained back by gravity to the storage tank (primary tank 1) (auxiliary tank 13 is located below the bottom of primary tank 1): liquid flows from the bottom of primary tank 1 into auxiliary tank 13 whenever the pressure within auxiliary tank 13 falls below the pressure at the bottom of primary tank 1, and the liquid in auxiliary tank 13 returns through valve 15 and lines 14 and 3 into the lower portion of primary tank 1 only after auxiliary tank 13 is pressurized to a pressure above the pressure within primary tank 1 (¶ 0023, 0026–0027; sole FIGURE).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the reliquefaction system of Wang, as modified, to include a recovery cryostat located at a position from which its liquid does not drain back to the storage tank by gravity, the liquid instead being returned into the lower portion of the storage tank by pressurizing the cryostat above the storage-tank pressure, as taught by Zia, in order to return the cold liquid into the lower portion of the storage tank so that the tank contents are kept colder, the tank pressure is kept lower, and vapor loss from the storage tank is reduced (Zia ¶ 0027). One of ordinary skill would have been motivated to make this modification because an elevated placement such as Wang's requires space above the storage cryostat (Wang ¶ 0018, 0024; figs. 2–3, 6), whereas Zia shows that cold liquid is returned from a cryocooler-cooled vessel into the storage tank without any elevation requirement by pressurizing that vessel (Zia ¶ 0026–0027), so that the location of the recovery cryostat may be selected to suit the installation with the predictable result of pressure-driven liquid return. See KSR, 550 U.S. 398; MPEP § 2143(I)(C).
As to limitation (b), Mackey teaches that the valve (valve 27) in a liquid line (liquid supply line 5) interconnecting two cryogenic vessels (bulk storage tank 3 and dispense tank 7) may be a check valve (¶ 0042–0043; see also ¶ 0046; fig. 1).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the return liquid line of Wang, as modified, to include a check valve as the liquid line return valve as taught by Mackey, in order to use a valve known to be suitable for controlling cryogenic liquid flow in a line interconnecting two cryogenic vessels (Mackey ¶ 0043). One of ordinary skill would have been motivated to make this modification because, in the pressure-driven return taught by Zia, liquid is to flow from the recovery cryostat into the storage tank only when the cryostat pressure exceeds the storage-tank pressure (Zia ¶ 0027), which is the pressure condition under which a check valve opens, so that substituting a check valve for an actuated valve predictably permits the return flow while blocking reverse flow from the storage tank. See MPEP § 2143(I)(B).
In regard to independent claim 13, Wang teaches a method to recover vapor that boils off in a cryogenic system (recondensing boiled-off cryogen from cryostat or Dewar 31) (¶ 0007, 0018; figs. 2–3), the cryogenic system comprising:
a storage tank (cryostat or Dewar 31) containing a liquid cryogen (liquid helium) (¶ 0007, 0018; fig. 2); and
a recovery cryostat (vacuum insulated sleeve 35 enclosed by vacuum housing 32, with vacuum space 47 therebetween) configured to receive vapor (vapor 41 of the boiled-off cryogen) from the storage tank (31) through a supply gas line (tube 48 connecting cryostat 31 to sleeve 35) (¶ 0016, 0018; fig. 2), coupled to a cryocooler (pulse tube cryocooler cold head 36 having cooling stations 38, 46 and condenser 39) that is configured to condense into liquid the vapor (41) received from said storage tank (31) (¶ 0016–0018; fig. 2), and configured to return the liquid to said storage tank (31) through a return liquid line (liquid transfer tube 40; straight transfer tube 50) (¶ 0018, 0020; figs. 2–3);
the method comprising:
condensing the vapor (41) in the recovery cryostat (35) (vapor 41 is precooled by the cold head within sleeve 35 and condenses into liquid on the fins of condenser 39) (¶ 0018; fig. 2).
Wang does not explicitly teach the following limitations of claim 13:
(a) the storage tank is configured to deliver the liquid cryogen to an external component that comprises a pump and/or a filling container, said storage tank configured to receive, at an upper portion of the storage tank, vapor from the liquid cryogen that boils off in said external component and connecting lines between the external component and the storage tank;
(b) the recovery cryostat is configured to return the liquid to said storage tank or the external component through a return liquid line that is connected to a lower portion of the storage tank and has a liquid line return valve;
(c) the supply gas line has an on-off gas line supply valve;
(d) pressurizing the recovery cryostat by one or more of turning off the cryocooler, turning on a heater in the recovery cryostat, and pressurizing the recovery cryostat with the same gas as the vapor, and returning the liquid to the storage tank or the external component based on pressure in the recovery cryostat; and
(e) closing the liquid line return valve; opening the on-off gas line supply valve while keeping the liquid line return valve closed; closing the on-off gas line supply valve; opening the liquid line return valve based on pressure in the recovery cryostat; closing the liquid line return valve; stopping said pressurizing the recovery cryostat; and opening the gas supply line valve (interpreted, as set forth in the rejection under 35 U.S.C. § 112(b) above, as the on-off gas line supply valve).
As to limitation (a), Zia teaches a cryogenic tank system comprising a storage tank (primary tank 1 having storage space 11) that is configured to deliver a liquid cryogen (cryogenic liquid 2, e.g., hydrogen, helium, neon, oxygen, nitrogen, or argon; delivered through conduit 3, valve 4, and conduit 5) to an external component (pump 6) that comprises a pump (pump 6, which pumps the liquid to use points including liquid cylinder filling and dewar filling), said storage tank (1) configured to receive, at an upper portion of the storage tank (upper portion of storage space 11, which contains vapor), vapor from the liquid cryogen that boils off in said external component (pump 6) and connecting lines (lines 8, 10) between the external component and the storage tank (liquid vaporized by pump and line heat leak in the course of being processed through the warmer pump 6 is passed in line 8 through valve 9 and in line 10 into the upper portion of storage space 11) (¶ 0002, 0020–0022; sole FIGURE).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the cryogen storage and reliquefaction system used in the method of Wang to include a liquid delivery conduit from the storage tank to a pump and a vapor return line that carries the cryogen vaporized in the pump and its connecting lines into the upper, vapor-containing portion of the storage tank as taught by Zia, in order to deliver the stored liquid cryogen to use points such as liquid cylinder filling and dewar filling while returning to the storage tank, rather than losing, the cryogen that is vaporized by pump and line heat leak (Zia ¶ 0002, 0021–0022).
As to limitation (b), Zia teaches a cryocooler-cooled vessel (auxiliary tank 13, connected through line 17 to cryocooler 16) configured to return liquid to the storage tank (primary tank 1) through a return liquid line (line 17 through cryocooler 16, and lines 14 and 3) that is connected to a lower portion of the storage tank (lower portion of primary tank 1, below its midpoint, which contains liquid) and has a liquid line return valve (valve 15) (¶ 0018, 0023, 0027; sole FIGURE).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the reliquefaction system used in the method of Wang, as modified by Zia, to include a return liquid line that is connected to the lower, liquid-containing portion of the storage tank and that has a liquid line return valve as taught by Zia, in order to introduce the cold returned liquid into the lower portion of the storage tank so that the tank contents are kept colder, the tank pressure is kept lower, and vapor loss from the storage tank is reduced (Zia ¶ 0027).
As to limitation (c), Mackey teaches a cryogenic system in which two cryogenic vessels (bulk storage tank 3 and dispense tank 7) are connected by a gas line (vapor return line 6) extending between the upper regions of the vessels, the gas line (6) having an on-off gas line valve (valve 26, e.g., a ball valve or shutoff valve, capable of a first configuration allowing vapor to flow through line 6 along path "B" and a second configuration substantially preventing vapor from flowing through line 6), the valve (26) being closed by control system 34 to isolate one vessel from the other (¶ 0045–0046, 0050, 0053, 0055; figs. 1, 3).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the supply gas line of the modified Wang system, to include an on-off valve configurable between a configuration allowing vapor to flow through the line and a configuration substantially preventing vapor from flowing through the line, operated by a control system, as taught by Mackey, in order to selectively permit or stop vapor communication between two interconnected cryogenic vessels and to isolate one vessel from the other (Mackey ¶ 0046, 0053, 0055).
As to limitation (d), Zia teaches, for a cryocooler-cooled vessel (auxiliary tank 13) from which liquid is returned to a storage tank (primary tank 1), pressurizing the vessel with the same gas as the vapor (cryogen vaporized in pressure building coil 19 is passed in line 20 through valve 21 back into auxiliary tank 13, the volume expansion increasing the pressure within auxiliary tank 13; alternatively, compatible vapors are introduced into auxiliary tank 13 from external sources), and returning the liquid, based on pressure in the vessel, to the storage tank (liquid flow is reversed from auxiliary tank 13 through line 17, cryocooler 16, valve 15, and lines 14 and 3 into the lower portion of primary tank 1 as the pressure in auxiliary tank 13 increases to above the pressure within primary tank 1) (¶ 0026–0027; sole FIGURE).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the method of Wang, as modified, to include pressurizing the recovery cryostat with vapor of the same cryogen and returning the liquid through the return liquid line into the lower portion of the storage tank once the pressure in the recovery cryostat exceeds the pressure in the storage tank, as taught by Zia, in order to return the cold liquid into the lower portion of the storage tank so that the tank contents are kept colder, the tank pressure is kept lower, and vapor loss from the storage tank is reduced (Zia ¶ 0027).
As to limitation (e), Mackey teaches a method of operating a cryogenic vessel (dispense tank 7) that is connected to a storage tank (bulk storage tank 3) by a gas line (vapor return line 6) having an on-off gas line valve (valve 26) and that discharges liquid through a liquid line (drain line 11 and fill line 15) having a liquid line valve (dispense valve 31, capable of a first configuration allowing liquid to flow along path "E" and a second configuration substantially preventing that flow) (¶ 0045–0046, 0084; fig. 1), the method comprising:
closing the liquid line valve (dispense valve 31 is held in its second, flow-preventing configuration until dispensing is initiated, and is again closed at the end of each dispensing event) (¶ 0084, 0090);
opening the on-off gas line valve (26) while keeping the liquid line valve (31) closed (control system 34 configures valve 26 to allow vapor 9 to flow along path "B" while dispense tank 7 fills, before dispensing through valve 31 is initiated) (¶ 0053, 0083–0084);
closing the on-off gas line valve (26) (when dispense tank 7 reaches the desired fill level, control system 34 closes valve 26, isolating dispense tank 7 from bulk storage tank 3) (¶ 0055);
pressurizing the vessel (7) with the same gas as the vapor (LNG from dispense tank 7 is at least partially vaporized in heat exchanger 25 and returned along path "D" to the upper region of dispense tank 7, increasing the pressure inside dispense tank 7) (¶ 0070–0072);
opening the liquid line valve (31) based on pressure in the vessel (7) (once dispense tank 7 reaches the desired pressure, valve 31 is opened and LNG flows out of dispense tank 7 along the pressure gradient) (¶ 0072, 0076, 0083–0084, 0086);
closing the liquid line valve (31) (control system 34 closes valve 31 to stop dispensing) (¶ 0090);
stopping said pressurizing (pressure building may continue during dispensing and is ceased by closing valve 29) (¶ 0087–0089); and
opening the on-off gas line valve (26) (the steps are repeated as many times as desired, dispense tank 7 being refilled with valve 26 again configured to allow vapor to flow along path "B") (¶ 0053, 0091).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the method of Wang, as modified, to include operating the on-off gas line supply valve and the liquid line return valve in the cycle of holding the liquid line valve closed while the gas line valve is open and the vessel fills, closing the gas line valve to isolate the vessel, pressurizing the vessel with vapor of the same fluid, opening the liquid line valve once the vessel pressure is sufficient so that liquid is discharged along the pressure gradient, closing the liquid line valve, ceasing the pressurization, and reopening the gas line valve to repeat the cycle, as taught by Mackey, in order to transfer cryogenic liquid out of a vessel by pressure, without the use of a pump, while the vessel is isolated from the tank that supplies it, with the cycle repeatable as many times as desired (Mackey ¶ 0008–0009, 0032, 0055, 0091).
In regard to claim 14, the modified Wang teaches the method of claim 13, wherein Wang teaches that the cryogen is one of helium, hydrogen, neon, oxygen, nitrogen, and argon (liquid cryogen, usually helium, stored within cryostat or Dewar 31) (¶ 0002, 0004, 0018).
In regard to claim 17, the modified Wang teaches the method of claim 13, wherein Wang teaches that the cryocooler is one of a GM type cryogenic expander, a pulse tube, a Stirling type pulse tube, and a reverse Brayton type of cryocooler (two-stage pulse tube cryocooler having pulse tubes 51, 54 and regenerators 52, 53 powered by compressor 55; alternatively, single-stage pulse tube cryocooler having pulse tube 66 and regenerator 67) (¶ 0016–0017, 0023; figs. 2, 6).
In regard to claim 18, Wang in view of Zia and Mackey teaches the method of claim 13, wherein said opening the liquid line return valve comprises opening the liquid line return valve (dispense valve 31 of Mackey; valve 15 of Zia) when the pressure in the recovery cryostat is able to force the liquid out through the return liquid line (Mackey opens valve 31 once dispense tank 7 has reached the desired pressure, so that liquid flows out of dispense tank 7 along the pressure gradient; Zia returns the liquid through valve 15 as the pressure in auxiliary tank 13 increases to above the pressure within primary tank 1) (Mackey ¶ 0072, 0076, 0084, 0086; Zia ¶ 0027; sole FIGURE of Zia).
The modification of the method of Wang to pressurize the recovery cryostat and return the liquid through the return liquid line into the lower portion of the storage tank once the pressure in the recovery cryostat exceeds the pressure in the storage tank would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention as taught by Zia, in order to return the cold liquid into the lower portion of the storage tank so that the tank contents are kept colder, the tank pressure is kept lower, and vapor loss from the storage tank is reduced (Zia ¶ 0027).
The further modification of the method of Wang to open the liquid line valve once the vessel has reached a pressure sufficient to discharge the liquid along the pressure gradient would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention as taught by Mackey, in order to transfer cryogenic liquid out of a vessel by pressure without the use of a pump (Mackey ¶ 0008–0009, 0032, 0086).
In regard to claim 21, Wang in view of Zia and Mackey teaches the method of claim 13, wherein the liquid line return valve is an on-off valve or a check valve (Mackey's dispense valve 31 is capable of a first configuration allowing liquid to flow and a second configuration substantially preventing liquid flow, i.e., an on-off valve; Mackey further teaches that the valve in a liquid line interconnecting cryogenic vessels may be a check valve) (Mackey ¶ 0043, 0084, 0090; fig. 1).
The modification of the method of Wang to operate the liquid line return valve as an on-off valve that is held closed while the recovery cryostat fills, opened once the cryostat pressure is sufficient to discharge the liquid along the pressure gradient, and then closed again, would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention as taught by Mackey, in order to transfer cryogenic liquid out of a vessel by pressure, without the use of a pump, with the cycle repeatable as many times as desired (Mackey ¶ 0008–0009, 0032, 0084, 0090–0091). One of ordinary skill would have been motivated to make this modification because the pressure-driven return taught by Zia requires that liquid be held in the recovery cryostat while it accumulates and is pressurized and then released into the storage tank (Zia ¶ 0026–0027), which is the function of a valve having an open configuration and a closed configuration.
Response to Arguments
Applicant’s arguments with respect to the amended claims have been considered but are moot in view of the new ground(s) of rejections, unless otherwise noted below.
Applicant argues (regarding 35 U.S.C. § 112(a), claim 19) that the specification supports subcooling of the stored liquid by the increased tank pressure produced by the returned boil-off vapor.
In response, the argument is persuasive and the rejection of claim 19 under 35 U.S.C. § 112(a) is withdrawn.
Applicant argues (regarding 35 U.S.C. § 112(a), claim 20) that the specification supports a recovery cryostat positioned so that its liquid cannot drain back by gravity, with a check valve in the liquid return line.
In response, the argument is found persuasive. The specification describes the alternative in which the liquid cannot be drained back and liquid line return valve 33 may be a check valve (Spec. ¶ 0007, 0020), and amended claim 20 confines the positional limitation to drainage by gravity. The rejection of claim 20 under 35 U.S.C. § 112(a) is withdrawn.
Applicant argues that the amendments cure the indefiniteness of 35 U.S.C. § 112(b) of the claims.
In response, the argument is persuasive in part. The amendments supply the missing antecedent basis, identify the source of the boiled-off vapor, and limit the external component; those rejections are withdrawn. The final step of claim 13 was not corrected: it still recites "the gas supply line valve," which has no antecedent, while the two other steps that operate the same valve now recite "the on-off gas line supply valve."
Applicant argues that Mackey's valve 26 is on a vapor return line into the storage tank rather than on a line supplying vapor to a cryostat, and that Mackey teaches no cryostat.
In response, the allegation is not persuasive. Wang, not Mackey, supplies the recovery cryostat and the supply gas line (tube 48) that carries vapor from the storage tank to it (Wang ¶ 0016–0018). Mackey is relied upon only for the valve: a valve in a gas line joining the vapor spaces of two cryogenic vessels, movable between a configuration allowing vapor flow and a configuration substantially preventing it, and closed to isolate the vessels (Mackey ¶ 0046, 0055). That is an on-off valve, and placed in Wang's tube 48 it is an on-off gas line supply valve, whatever the direction of flow in Mackey's line. Applicant attacks the references individually rather than the combination. See MPEP § 2145(III)–(IV).
Applicant argues that Tyree's check valve 34a must remain a check valve because it responds to CO2 compressor 32.
In response, the argument is moot. The new ground, necessitated by the amendment, does not rely on Tyree.
Applicant argues that the prior Office Action applied apparatus intended-use case law to method claim 13 and did not address its steps.
In response, the argument is moot. The new ground does not rely on In re Sinex, Ex parte Masham, In re Danley, or Hewlett-Packard Co. v. Bausch & Lomb, Inc. Claim 13 was amended to limit the external component, to redefine the source of the boiled-off vapor, and to make the gas line supply valve, rather than the liquid line return valve, the on-off valve operated by the method steps. The rejection of amended claim 13 above maps each step.
Applicant argues that, because no reference teaches the on-off gas line supply valve, none teaches the steps of opening and closing that valve and the liquid line return valve.
In response, the argument is not persuasive. The premise fails for the reasons given in the response above. Mackey also teaches the recited sequence: holding the liquid line valve closed while the gas line valve is open, closing the gas line valve to isolate the vessel, pressurizing the vessel with vapor of the same fluid, opening the liquid line valve once the vessel pressure is sufficient, closing it, ceasing pressurization, and reopening the gas line valve to repeat (Mackey ¶ 0053, 0055, 0070–0072, 0084, 0087–0091).
Pertinent Art
The prior art made of record and not relied upon is considered pertinent to Applicant's disclosure:
Eckels (US 5,936,499) teaches a helium recondensing chamber located outside the helium pressure vessel that receives helium vapor through a gas passage, condenses it with a GM cryocooler, and returns the liquid through a return line by gravity, with an electric heater on the recondensing chamber controlled to regulate pressure.
Weiler et al. (US 5,937,655) teaches a cryogenic transfer tank filled from a bulk tank through solenoid-actuated valves while its outlet valve is closed, isolated by closing the fill valves, pressurized by an electric heater element, discharged under head pressure through the outlet valve, and refilled in a repeating cycle.
US 6,725,683 teaches an elevated cryogen storage tank that supplies liquid cryogen through transfer lines to an external load and receives the resulting vapor in the upper vapor region of the tank, where a cryorefrigerator recondenses it.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/W.M/Examiner, Art Unit 3763
/FRANTZ F JULES/Supervisory Patent Examiner, Art Unit 3763
