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 .
Response to Amendment
Applicant’s amendment filed on March 18, 2026 has been received. Claim 15 is canceled. Claims 18-23 are new. Claims 1-14 and 16-23 are under consideration.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-4, 8, 16, 17, and 19-23 are rejected under 35 U.S.C. 103 as being unpatentable over Møllerhøj (WO 2018/108739 A1) in view of Hughes (US 779,941), Rogers-A (US 1,339,137), and Kassab et al. (International Journal of Heat and Fluid Flow 30 (2009) 88-98).
Regarding claim 1, Møllerhøj discloses a sulfuric acid recirculation loop (see FIG. 2 and corresponding description) comprising:
an (optional) sulfuric acid condenser column (11; see, e.g., page 7, lines 25-32);
a concentrator column (55; see, e.g., page 8, lines 14-30);
an acid pump (i.e., a hot acid recirculation pump 49) having a liquid inlet fed with hot concentrated sulfuric acid (i.e., in line 48) from an outlet of a sulfuric acid reservoir downstream of the concentrator column 55, wherein the sulfuric acid reservoir is located at a lower elevation than the concentrator column 55 (i.e., “To ensure that the acid pump does not run dry, a reservoir or tank is preferably located at the suction side of the pump. It can either be integrated in the acid concentrator column or be a separate tank, located between the outlet of the concentrator column and the inlet to the acid recirculation pump (49),” see page 9, lines 21-26), and an outlet (i.e., an outlet of the acid pump 49 which discharges acid to be recirculated to an acid circulation stream pipe 56); and
inlet piping comprising an inlet pipe (i.e., a pipe 54), said inlet piping directing recirculated sulfuric acid to an inlet of the sulfuric acid recirculation loop (i.e., to an inlet of the concentrator column 55).
The sulfuric acid recirculation loop of Møllerhøj is the same as the claimed apparatus, except that Møllerhøj fails to disclose the recited air lift pump system (i.e., instead of the mechanical, acid recirculation pump 49) for elevating the hot concentrated sulfuric acid from the outlet of the sulfuric acid reservoir to the inlet of the sulfuric acid recirculation loop.
Hughes discloses an air lift pump system (see FIG. 1) for pumping acids, such as sulfuric acid (see page 1, lines 11-15; page 2, lines 42-44), from a lower elevation (i.e., an acid supply tank 2) to a higher elevation (i.e., an acid receiving tank 3), wherein the system comprises:
an air lift pump including a mixing point (i.e., a point near a lowest portion of a pipe 1, at which compressed air supplied by a pipe 5 mixes with acid that flows through the pipe 1) and a riser pipe (i.e., an upward, vertically extending portion of the pipe 1, downstream from the mixing point, through which a mixture of the acid and the compressed air rises); wherein the mixing point has a liquid inlet (i.e., via a U-bend at the lowest portion of the pipe 1) fed with acid from an outlet of an acid supplying reservoir (i.e., from an outlet of the acid supply tank 2), a gas inlet (i.e., a discharge end of the compressed air supply pipe 5) fed with a carrier fluid (i.e., compressed air) having a lower density than the acid, and an outlet (i.e., downstream from the mixing point); the mixing point configured to combine the acid and the carrier fluid;
wherein the acid supplying reservoir 2 is located at a higher elevation than the gas inlet of the air lift pump (i.e., the acid supply tank 2 is located above the discharge end of the compressed air supply pipe 5);
wherein the acid flows in a downcomer pipe (i.e., a downward extending portion of pipe 1) leading down from the acid supplying reservoir 2 to the liquid inlet of the air lift pump; and
wherein the riser pipe 1 leads up from the mixing point to an outlet for directing the acid to an acid receiving reservoir (i.e., the acid receiving tank 3) located at the higher elevation.
It would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to substitute an air lift pump system, as taught by Hughes, for the acid pump in the sulfuric acid recirculation loop of Møllerhøj because the sulfuric acid could be pumped and effectually elevated simply by use of compressed air, as taught by Hughes, and the substitution of one known element for another involves only ordinary skill in the art, and the results of the substitution would have been predictable. See MPEP § 2143, I, B.
The combination of Møllerhøj and Hughes fails to teach that the riser pipe leads up from the mixing point to inlet piping comprising an inlet pipe having an inlet and an outlet and an increased diameter compared to the riser pipe, said inlet piping being configured to allow a liquid flow from the inlet to the outlet and at least partially separate recirculated sulfuric acid and carrier fluid, said inlet piping directing all of both fluids to the inlet of the recirculation loop.
Rogers-A discloses an air lift pump system for pumping liquids from a lower elevation to a higher elevation, wherein the system (see FIG. 1) comprises: an air lift pump including a mixing point (i.e., a point near a lower end of a lower air-lift pipe P, at which air supplied by a device A from a compressed-air source mixes with liquid that flows into the lower air-lift pipe P) and a riser pipe (i.e., the lower air-lift pipe P, downstream from the mixing point); the mixing point having a liquid inlet (i.e., via a lower end of the lower air-lift pipe P) fed with liquid, a gas inlet A fed with a carrier fluid (i.e., compressed air) having a lower density than the liquid, and an outlet (i.e., downstream from the mixing point); the mixing point configured to combine the liquid and the carrier fluid; wherein, specifically, the riser pipe P leads up from the mixing point to inlet piping (i.e., piping which includes a de-aeration chamber C and an upper air-lift pipe P2), the inlet piping comprising an inlet pipe (i.e., the upper air-lift pipe P2) for supplying the liquid to a liquid reservoir located at a higher elevation, said inlet pipe P2 having an inlet (i.e., via a lower end of the upper air-lift pipe P2) and an outlet (i.e., via an upper end of the upper air-lift pipe P2) and an increased diameter compared to the riser pipe P (i.e., “… the cross-sectional area of the upper pipes P2,P5, may be made proportionately larger than the lower pipes P,P4, this arrangement providing for the same, or nearly the same, upward velocity of the aerated fluid in the lower part of the pipes P,P4, and P2, P5,” see page 2, lines 128-126), said inlet piping being configured for allowing a liquid flow from the inlet to the outlet and configured for at least partially separating the liquid and carrier fluid (i.e., within the de-aerating chamber C; see page 1, lines 57-92), said inlet piping C,P2 directing all of both fluids (i.e., both the liquid and air) to the outlet of the inlet pipe P2, located at the higher elevation.
It would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to further configure the riser pipe to lead up from the mixing point to inlet piping which comprises an inlet pipe having an inlet and an outlet and an increased diameter compared to the riser pipe, said inlet piping being configured for allowing a liquid flow from the inlet to the outlet and configured for at least partially separating recirculated sulfuric acid and carrier fluid, and said inlet piping directing all of both fluids to the inlet of the concentration column, in the modified sulfuric acid recirculation loop of Møllerhøj, because the recited configuration of the inlet piping would improve the efficiency of the air lift pump system by reducing “slippage” and surface friction as the liquid and the carrier fluid are elevated by the system, and the liquid and carrier fluid would be elevated at the same or nearly the same upward velocity in both the lower and upper portions of the system, as taught by Rogers-A (see page 2, lines 22-96 and lines 118-125).
Lastly, the new limitation “wherein the ratio of carrier fluid to hot concentrated sulfuric acid is from 6 to 20 Nm3 per ton hot concentrated sulfuric acid” is directed to an intended manner of operating the apparatus which does not structurally differentiate the claimed apparatus from the prior art. See MPEP § 2114. However, in any event, Rogers-A (at column 1, lines 40-48; with emphasis) discloses,
“… the total submergence effect should correspond, substantially as in ordinary practice, to the total height to which the fluid is to be elevated and the quantity of air used for aerating the uptake column to sufficiently reduce the weight thereof as compared with the weight, or gravity effect, of the submergence column.”
Kassab et al. further describes the performance characteristics of air-lift pumps under two-phase flow conditions. Kassab et al. (see FIG. 2 and 4; and 3.1. Water flow rate) noted that for all submergence ratios (ratios Hs/L, see FIG. 1), the water mass flow rate (kg/hr) increases as the air mass flow rate (kg/hr) increases, until the water mass flow rate reaches a maximum value. Also, for a fixed value of the air mass flow rate (kg/hr), the water flow rate (kg/hr) increases with the increase of the submergence ratio (Hs/L). For reference, the density of air at normal conditions (depending on the standard used for the temperature and pressure) is about 1.2 to 1.3 kg/Nm3. Also, 1 ton equals 907.185 kg.
Therefore, the specific ratio of the carrier fluid to the sulfuric acid would have been considered a result effective variable by one of ordinary skill in the art. Accordingly, it would have been obvious for one having ordinary skill in the art before the effective filing date of the claimed invention to routinely optimize the ratio of the carrier fluid to the hot concentrated sulfuric acid during the operation of the modified sulfuric acid recirculation loop of Møllerhøj (i.e., by controlling the quantity or mass flow rate of the air admitted to the lower end of the air-lift pump, for a predetermined submergence ratio Hs/L of the air-lift pump) in order to obtain the desired liquid flow of the sulfuric acid through the recirculation loop.
Regarding claim 2, Møllerhøj (see page 11, lines 6-10) discloses, “In a further embodiment of the invention, the product acid stream (51) is withdrawn upstream the acid circulation pump (49), such that the product acid flow can be controlled with a simple overflow or liquid level control in the acid reservoir or tank.” Therefore, it would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to further configure the sulfuric acid product to be withdrawn through an overflow pipe in the sulfuric acid reservoir in the modified sulfuric acid recirculation loop of Møllerhøj because the product acid flow can be controlled with a simple overflow from the sulfuric acid reservoir.
Regarding claim 3, Møllerhøj discloses a sulfuric acid heater (i.e., an acid heater 53; see FIG. 2; page 9, line 28, to page 10, line 4) between the outlet of the pump 49 and the inlet of the sulfuric acid recirculation loop (i.e., the inlet to concentrator column 55); wherein the heater 53 is operable to heat the acid to a temperature of 200-270 °C. Therefore, It would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to further provide a sulfuric acid heater between the outlet of the mixing point and the one or multiple inlets to the recirculation loop, such that the combined sulfuric acid and carrier fluid are heated, in the modified loop of Møllerhøj, because the heater would allow for the recirculated sulfuric acid to be heated so that sufficient energy can be imparted to the acid to facilitate the stripping of the water from the acid in the concentrator column.
Regarding claim 4, Hughes discloses that the carrier fluid is air (i.e., air supplied by the pipe 5 connected to a source of compressed air; see FIG. 1; page 1, lines 34-40).
The modified sulfuric acid recirculation loop of Møllerhøj meets the claim because the further provision of a carrier fluid heater, upstream of the mixing point and configured to heat the carrier fluid, is optional. In any event, Møllerhøj discloses that sufficient energy can be imparted to the stripping process in the column 55 through the use of heaters, including a carrier fluid heater 44 for heating the air used for the stripping, wherein the carrier fluid heater 44 is operable to heat the carrier fluid to a temperature of 100-700 °C, preferably 300-700 °C, and most preferably 350-600 °C (see page 4, lines 29-30); and an acid heater 53 for heating the recirculated sulfuric acid, wherein the acid heater 53 is operable to heat the acid to a temperature of 200-270 °C, preferably 230-260 °C (see page 4, line 31, to page 5, line 3). It would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to provide a carrier fluid heater upstream of the mixing point in the modified sulfuric acid recirculation loop of Møllerhøj because it would have been evident to one of ordinary skill in the art that the sulfuric acid should be maintained at an elevated temperature during its passage through the recirculation loop, so that sufficient energy can be imparted to the stripping process in the concentrator column, and one of ordinary skill in the art would have recognized that the provision of a carrier fluid heater for heating the air supplied as the carrier fluid to the mixing point would ensure that the acid was maintained a desired elevated temperature. Obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art.
Regarding claim 8, Møllerhøj discloses an inlet for a stream of cold sulfuric acid, colder than the hot concentrated sulfuric acid (i.e., an inlet for condensed acid stream 47 from the bottom of the condenser column 11, which is colder than the hot sulfuric acid in line 48; see FIG. 2; page 11, lines 19-29); the loop being configured to mix the stream of cold sulfuric acid 47 with the hot concentrated sulfuric acid 48 in a position upstream of the inlet to the acid pump 49. Therefore, it would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to further provide an inlet for a stream of cold sulfuric acid, wherein the loop is configured to mix the stream of cold sulfuric acid with the hot concentrated sulfuric acid in a position upstream of the mixing point in the modified sulfuric acid recirculation loop of Møllerhøj, because the cold sulfuric acid from the condenser column could be delivered to the elevation of the inlet of the concentrator column, and the condenser column would not have to be elevated above the concentrator column to provide gravity flow of the cold sulfuric acid to the concentrator column (see Møllerhøj, page 11, lines 19-29).
Regarding claim 16, Møllerhøj (see FIG. 2) discloses that the sulfuric acid circulation loop comprises the optional sulfuric acid condenser 11, and the sulfuric acid recirculation loop is configured to direct sulfuric acid vapor originating in the concentrator column 55 (i.e., via lines 46, 46a, and 10a) to a bottom of the optional sulfuric acid condenser 11.
Regarding claim 17, the specific temperature of the hot concentrated sulfuric acid is considered a process limitation that does not structurally differentiate the claimed apparatus from the prior art. In any event, Møllerhøj discloses that stripping media (i.e., hot, dried air 45; FIG. 2) is admitted to the concentrator column 55 at a temperature from 100-700°C (see page 4, lines 29-30; page 5, lines 23-25), such that the hot concentrated acid (i.e., leaving via line 48, after exchanging heat with the stripping media) can be heated to a temperature above 70 °C.
Regarding claims 19 and 20, in the modified sulfuric acid recirculation loop of Møllerhøj, the inlet piping (i.e., corresponding to pipe 54, see FIG. 2) would direct both fluids to an inlet of the concentration column 55. Alternatively, the recirculation loop can be configured such that the inlet 54 is at a bottom of the optional sulfuric acid condenser 11 (see FIG. 1, 3, and 4).
Regarding claim 21, Møllerhøj discloses that the recirculation loop can be configured such that the inlet piping (i.e., corresponding to pipe 54) directs the recirculated sulfuric acid to a position above the concentrator column 55 (i.e., a bottom of the sulfuric acid condenser 11, which is a position above the column 55, see FIG. 1, 3, 4; or a position above the column, based on the interpretation that the column 55 is the packed bed itself, see FIG. 2).
Regarding claim 22, in the modified sulfuric acid recirculation loop of Møllerhøj, the inlet piping (i.e., corresponding to pipe 54) would be configured to direct the recirculated sulfuric acid to a position above the concentrator column (i.e., a bottom of the condenser 11, which is a position above the column 55, see FIG. 1, 3, 4; or a position above the concentrator column, based on the interpretation that the column is the packed bed itself, see FIG. 2) and the carrier fluid to a position in the sulfuric acid recirculation loop (i.e., compressed air is admitted to the air-lift pump that was substituted for the acid pump 49).
Regarding claim 23, Møllerhøj (see FIG. 2) discloses that the inlet piping 54 directs the recirculated sulfuric acid to a liquid distributor of the concentrator column 55 (i.e., “On the top of the column is a liquid distributor, ensuring that the acid being fed to the packed bed of the concentrator column is evenly distributed”, see page 8, lines 15-20).
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Møllerhøj (WO 2018/108739 A1) in view of Hughes (US 779,941), Rogers-A (US 1,339,137), and Kassab et al. (International Journal of Heat and Fluid Flow 30 (2009) 88-98), as applied to claim 1 above, and further in view of Daum et al. (WO 2015/169395 A1).
The combination of Møllerhøj, Hughes, Rogers-A, and Kassab et al. fails to teach two or more air lift pumps arranged in parallel.
Daum et al. discloses an apparatus (see FIG. 1; page 10, line 23, to page 11, line 25) comprising a packed bed gas-liquid contact column (i.e., a packed bed absorption tower 1) and a recirculation loop for circulating a liquid acid from a sump region 3,3a of the column to an acid supply system 4 positioned above a packed bed 2 in the column. Specifically, Daum et al. discloses that the recirculation loop comprises two pumps 16, 17 arranged in parallel for pumping the liquid acid through the loop (see page 11, lines 17-19). However, Daum et al. also discloses that, obviously, a single pump can be used (see page 11, lines 23-24).
It would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to provide two or more air lift pumps arranged in parallel in the modified sulfuric acid recirculation loop of Møllerhøj because either a single pump or a plurality of parallel pumps would have been suitable for circulating liquid acid through a recirculation loop of a gas-liquid contact column, as taught by Daum et al., and furthermore, the duplication of parts to predictably provide a multiplied effect (i.e., in this case, an increase in the liquid acid pumping capacity) would have been obvious. See MPEP § 2144.04, VI, B.
Claims 6, 7, and 18 are rejected under 35 U.S.C. 103 as being unpatentable over Møllerhøj (WO 2018/108739 A1) in view of Hughes (US 779,941), Rogers-A (US 1,339,137), and Kassab et al. (International Journal of Heat and Fluid Flow 30 (2009) 88-98), as applied to claim 1 above, and further in view of Rogers-B (US 1,491,822).
Regarding claim 6, Møllerhøj discloses that the inlet of the concentrator column can be at a position above the concentrator column (i.e., interpreted as a position above the packed bed in the column 55; see FIG. 2), or, alternatively, the inlet can be at a position at a bottom of the optional sulfuric acid condenser 11 (see FIG. 1, 3, 4).
Rogers-A (FIG. 1) further discloses that the inlet piping comprises the inlet pipe P2, wherein the inlet piping is configured to direct both the liquid and the carrier fluid to the outlet, which is located at the higher elevation.
The combination of Møllerhøj, Hughes, Rogers-A , and Kassab et al., however, fails to teach that the inlet piping comprises: the inlet pipe, being a dedicated pipe for sulfuric acid, and a dedicated pipe for carrier fluid; wherein the two pipes are configured to direct their fluids to the inlet of the concentrator column.
Rogers-B discloses an air lift pump system (see FIG. 5) comprising:
an air lift pump including a mixing point (i.e., a point near a lower end of a lower air-lift pipe P, at which compressed air supplied by an air pipe 21 mixes with liquid that flows through the lower air-lift pipe P) and a riser pipe (i.e., the lower air-lift pipe P, downstream from the mixing point); the mixing point having a liquid inlet (i.e., via the bottom of the lower air-lift pipe P) fed with liquid, a gas inlet (i.e., via the discharge from the air pipe 21) fed with a carrier fluid (i.e., air) having a lower density than the liquid, and an outlet (i.e., downstream from the mixing point); the mixing point configured to combine the liquid and the carrier fluid;
the riser pipe P leading up from the mixing point to inlet piping, wherein the inlet piping comprises: an inlet pipe (i.e., an upper air-lift pipe P2) having an inlet and an outlet, the inlet piping being configured for allow a liquid flow from the inlet to the outlet of the inlet pipe and configured for at least partially separating the liquid and the carrier fluid (i.e., within a segregating part G10 defining a chamber M), said inlet piping directing all of both fluids to the outlet for the discharge of both fluids, to a destination at a higher elevation.
Specifically, Rogers-B (see page 3, lines 60-93) discloses that the inlet piping comprises the inlet pipe being a dedicated pipe for the liquid (i.e., a liquid stream conduit R), and a dedicated pipe for the carrier fluid (i.e., an air stream conduit S); wherein the two pipes R,S direct their fluids to the outlet for the discharge of the fluids, at the higher elevation.
Rogers-B (see page 1, lines 10-13) further discloses that the air lift pump system is an improvement over the prior air lift pump system that was described in Rogers-A.
It would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to further configure the inlet piping to comprise the inlet pipe, being a dedicated pipe for sulfuric acid, and a dedicated pipe for carrier fluid, wherein the two pipes are configured to direct their fluids to the inlet of the concentrator column, in the modified sulfuric acid recirculation loop of Møllerhøj, because the provision of two dedicated pipes for the sulfuric acid and the carrier fluid, respectively, would enhance the separation of the sulfuric acid and the carrier fluid by the inlet piping and improve upon the efficiency of the air lift pumping system, as taught by Rogers-B.
Regarding claim 7, Møllerhøj discloses that the inlet of the concentrator column can be at a position above the concentrator column (i.e., interpreted as a position above the packed bed in the column 55; see FIG. 2) or, alternatively, the inlet can be at a position at a bottom of the optional sulfuric acid condenser 11 (see FIG. 1, 3, 4).
Rogers-A further discloses that the inlet piping (see FIG. 1-3) comprises:
a separator vessel or a separator pipe (i.e., a separator vessel comprising the de-aerating chamber C, see FIG. 1; or, in another embodiment, a separator pipe comprising the de-aerating chamber C2, see FIG. 3), the separator vessel C or pipe C2 being configured to carry out the separation of the liquid and the carrier fluid coming from the riser pipe P,P4; and
a connecting outlet (i.e., an outlet of the de-aerating chamber C,C2) connected to the inlet pipe (i.e., upper air-lift pipe P2,P5), wherein the inlet pipe P2,P5 is a pipe for conveying both the liquid and the carrier fluid, wherein the inlet piping is configured to direct both the liquid and the carrier fluid to the outlet, located at the higher elevation.
The combination of Møllerhøj, Hughes, Rogers-A, and Kassab et al., however, fails to teach that the inlet piping comprises: two connecting outlets connecting to the inlet pipe, being a dedicated pipe for sulfuric acid, and a dedicated pipe for carrier fluid; wherein the two pipes are configured to direct their fluids to the inlet of the concentrator column.
Rogers-B discloses an air lift pump system (see FIG. 5) comprising:
an air lift pump including a mixing point (i.e., a point near a lower end of a lower air-lift pipe P, at which compressed air supplied by an air pipe 21 mixes with liquid that flows through the lower air-lift pipe P) and a riser pipe (i.e., the lower air-lift pipe P, downstream from the mixing point); the mixing point having a liquid inlet (i.e., via the bottom of the lower air-lift pipe P) fed with liquid, a gas inlet (i.e., via the discharge from the air pipe 21) fed with a carrier fluid (i.e., air) having a lower density than the liquid, and an outlet (i.e., downstream from the mixing point); the mixing point configured to combine the liquid and the carrier fluid;
the riser pipe P leading up from the mixing point to inlet piping, wherein the inlet piping comprises: an inlet pipe (i.e., an upper air-lift pipe P2) having an inlet and an outlet, the inlet piping being configured for allow a liquid flow from the inlet to the outlet of the inlet pipe and configured for at least partially separating the liquid and the carrier fluid (i.e., within a segregating part G10 defining a chamber M), said inlet piping directing all of both fluids to the outlet for the discharge of both fluids, at a higher elevation.
Specifically, Rogers-B discloses that the inlet piping (see page 3, lines 60-93) comprises:
a separator vessel or a separator pipe (i.e., the segregating part G10 defining the chamber M) with an inner diameter larger than the inner diameter of the riser pipe P, the separator vessel or separator pipe G10,M being configured to carry out the separation of the liquid and the carrier fluid coming from the riser pipe P; and two connecting outlets (i.e., two outlets from segregating part G10) connecting to the inlet pipe P2, being a dedicated pipe for the liquid (i.e., a liquid stream conduit R), and a dedicated pipe for the carrier fluid (i.e., an air stream conduit S); wherein the two pipes R,S are configured to direct their fluids to the outlet for discharge of the fluids, at the higher elevation.
Rogers-B (see page 1, lines 10-13) further discloses that the air lift pump system is an improvement over the prior air lift pump system that was described in Rogers-A.
It would have been obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to further configure the inlet piping to comprises two connecting outlets connecting to the inlet pipe, being a dedicated pipe for sulfuric acid and a dedicated pipe for carrier fluid, wherein the two pipes direct their fluids to the inlet of the concentrator column, in the modified sulfuric acid recirculation loop of Møllerhøj because the two connecting outlets and two dedicated pipes for the sulfuric acid and the carrier fluid, respectively, would enhance the separation of the sulfuric acid and the carrier fluid by the inlet piping and improve upon the efficiency of the air lift pumping system, as taught by Rogers-B.
Regarding claim 18, the same comments with respect to Rogers-B (see claims 6-7 above) apply. In particular, Rogers-B (see page 3, lines 60-93) disclosed that the inlet piping comprises the inlet pipe being a dedicated pipe for the liquid (i.e., a liquid stream conduit R), and a dedicated pipe for the carrier fluid (i.e., an air stream conduit S); wherein the two pipes R,S direct their fluids to the outlet for the discharge of the fluids. Thus, in the modified sulfuric acid recirculation loop of Møllerhøj, the inlet piping would be configured to calm the flow of the sulfuric acid before the outlet (i.e., by having the dedicated pipe for the liquid stream).
Response to Arguments
Applicant's arguments filed on March 18, 2026 have been fully considered.
Applicant (at page 13) argues,
“Møllerhøj employs a centrifugal pump to recirculate sulfuric acid in a wet gas sulfuric acid plant. The stream delivered by that pump is a single-phase liquid stream with inherently stable hydraulic behavior. Møllerhøj does not confront the hydrodynamic consequences of delivering a two-phase sulfuric acid/carrier gas mixture from an air-lift pump back into a component of the recirculation loop.
Hughes and Rogers disclose air-lift pumps used to elevate liquids. In those systems, air is used as a lifting medium and is not described as being integrated into a sulfuric acid concentration column or otherwise fed back to the sulfuric acid recirculation loop.”
The Office respectfully disagrees.
In the sulfuric acid recirculation loop of Møllerhøj, a mechanical pump (i.e., an acid pump 49; see FIG. 2) performs the function of raising the acid from a lower elevation (i.e., from an acid reservoir below the column 55) to a higher elevation (i.e., to an inlet 54 proximate an upper end of the column 55). Møllerhøj does not disclose an air-lift pump for this purpose.
Hughes, however, discloses an air lift pump system (see FIG. 1) that is specifically designed for elevating acids, and, in particular, sulfuric acid from a sulfuric-acid making process (see page 1, lines 11-19; page 2, lines 38-44), wherein sulfuric acid is raised from a lower elevation (i.e., from an acid supplying tank 2) to a higher elevation (i.e., to an acid receiving tank 3) using the air-lift pump.
Therefore, it would have been obvious for one of ordinary skill in the art to substitute the air-lift pump of Hughes for the acid pump 49 in the sulfuric acid recirculation loop of Møllerhøj, given that the air-lift pump was specifically designed for elevating acids, and, in particular, sulfuric acid from a sulfuric-acid making process.
Applicant (at page 15) further argues,
“Hughes and Rogers disclose air-lift apparatuses for elevating liquids, but the air in those systems functions solely as a lifting medium. Neither reference describes the carrier gas as containing sulfuric acid vapor that must be recovered, nor do they describe directing the carrier gas back to the sulfuric acid recirculation loop. The air associated with the air-lift operation in those references is not integrated into a sulfuric acid recovery system and is not treated as a process gas that affects condenser loading, acid mist formation, or sulfuric acid vapor handling.
Accordingly, the claimed flow of the carrier fluid back to the sulfuric acid recirculation loop, and, e.g., to a sulfuric acid condenser column, represents a process-integration feature absent from Hughes and Rogers. It reflects the fact that, in the claimed system, the carrier gas is not merely a pumping medium but is part of the sulfuric acid concentration process and must be handled in a manner consistent with sulfuric acid vapor recovery. The cited art does not teach or suggest this feature.”
The Office respectfully disagrees.
The test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981).
In this case, the sulfuric acid recirculation loop of Møllerhøj was modified by simply replacing the mechanical acid pump 49 (see FIG. 2) with an air-lift pump as taught by Hughes and Rogers, for the same purpose of elevating the sulfuric acid from a lower elevation, i.e., corresponding to the sulfuric acid reservoir below the column 55, to a higher elevation, corresponding an inlet at a discharge end of the piping 54, proximate an upper end of the column 55. Therefore, the carrier fluid (air) admitted to the air-lift pump for elevating the sulfuric acid would be fed along with the sulfuric acid to the inlet, and any acidic vapor entrained with the carrier gas would be condensed upon its passage through the condenser 11. The condensed sulfuric acid would then be returned by means of gravity to the column 55, and a cleaned carrier fluid would be discharged from the condenser 11 to a stack 14.
Applicant (at pages 15-16) further argues that the prior art fails to disclose or teach the new limitation of claim 1, wherein the ratio of carrier fluid to hot concentrated sulfuric acid is from 6 to 20 Nm3 per ton hot concentrated sulfuric acid.
However, the new limitation is directed to an intended manner of operating the apparatus which does not structurally differentiate the claimed apparatus from the prior art. See MPEP § 2114. Furthermore, Rogers-A (at column 1, lines 40-48; with emphasis) discloses,
“… the total submergence effect should correspond, substantially as in ordinary practice, to the total height to which the fluid is to be elevated and the quantity of air used for aerating the uptake column to sufficiently reduce the weight thereof as compared with the weight, or gravity effect, of the submergence column.”
Kassab et al. also describes the performance characteristics of air-lift pumps under two-phase flow conditions. Kassab et al. (see FIG. 2 and 4; 3.1. Water flow rate) noted that for all submergence ratios (ratio Hs/L, see FIG. 1), the water mass flow rate (kg/hr) increases as the air mass flow rate (kg/hr) increases, until the water mass flow rate reaches a maximum value. For a fixed value of the air mass flow rate (kg/hr), the water flow rate (kg/hr) also increases with the increase of the submergence ratio (Hs/L). For reference, the density of air at normal conditions (depending on the standard used for the temperature and pressure) is about 1.2 to 1.3 kg/Nm3. Also, 1 ton equals 907.185 kg.
Therefore, the specific ratio of the carrier fluid to the sulfuric acid would have been considered a result effective variable by one of ordinary skill in the art. Accordingly, one having ordinary skill in the art would have routinely optimized the ratio of the carrier fluid to the hot concentrated sulfuric acid during operation of the modified sulfuric acid recirculation loop of Møllerhøj (i.e., by controlling the quantity or mass flow rate of compressed air admitted to the lower end of the air-lift pump for a given submergence ratio Hs/L) in order to obtain the desired liquid flow of sulfuric acid through the recirculation loop.
Applicant (at page 17, last paragraph) further argues that one of ordinary skill in the art would not have been motivated to replace a centrifugal pump with an air-lift pump, given that,
“Centrifugal pumps, such as in Møllerhøj, are energy-efficient and provide stable flow. Air-lift pumps require compressed gas and are less energy efficient. In hot concentrated sulfuric acid service, materials of construction must be highly corrosion-resistant and are expensive. One skilled in the art would therefore not be inclined to introduce additional gas flow or replace a centrifugal pump with an air-lift pump without a clear process advantage in the system of Møllerhøj.”
The Office respectfully disagrees.
The fact that the pump is to be used in a highly corrosive environment would have presented the motivation for selecting an air-lift pump over a centrifugal pump for elevating the sulfuric acid, despite its lower efficiency. In particular, Kassab et al. (see Abstract) discloses,
“Air-lift pumps are finding increasing use where pump reliability and low maintenance are required, where corrosive [fluids]… must be handed and when a compressed air is readily available…”.
Kassab et al. (see 1. Introduction, third paragraph) further discloses,
“In comparison with other pumps, the particular merit of the air-lift pump is the mechanical simplicity. Moreover, they can be used in a corrosive environment… Thus, theoretically, the maintenance of this kind of pumps has a lower cost and higher reliability.”
Therefore, the mechanical simplicity, lower maintenance costs, and higher reliability inherent of air-lift pumps would have motivated one of ordinary skill in the art to utilize an air lift pump for elevating the sulfuric acid in the sulfuric acid recirculation loop of Møllerhøj, despite its lower efficiency when compared to a centrifugal acid pump.
Allowable Subject Matter
Claims 9-14 are allowed.
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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/JENNIFER A LEUNG/Primary Examiner, Art Unit 1774
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