Method and apparatus for dynamic gas mixture production

Abstract

The present invention relates to a method for producing and delivering a gas mixture having a selected composition of a first gas and at least one second gas, comprising the following steps: (a) providing a main gas flow comprising the first gas in a main conduit, (b) separating the main gas flow into a first plurality of secondary gas flows, (c) guiding each secondary gas flow through a secondary conduit, (d) adding at least one second gas to at least one of the first plurality of secondary gas flows in the respective secondary conduit through a delivering conduit, said delivering conduit protruding into the secondary conduit, and (e) combining the first plurality of secondary gas flows to the gas mixture. With the technical teaching of the present invention a dynamic gas bottle filling is possible wherein the second gas components may have a concentration form some ppb to percent.

Claims

1. A method for producing and delivering a gas mixture having a selected composition of a first gas and at least one second gas comprising the following steps: a) providing a main gas flow comprising the first gas in a main conduit (1), b) separating the main gas flow into a first plurality of secondary gas flows, c) guiding each secondary gas flow through a secondary conduit (2), d) adding at least one second gas through a delivering conduit (3) to at least one of the first plurality of secondary gas flows in the respective secondary conduit (2), said delivering conduit (3) protruding into the secondary conduit (2), e) combining the first plurality of secondary gas flows to form a first gas mixture, f) separating the first gas mixture into a second plurality of secondary gas flows, g) guiding each secondary gas flow through a secondary conduit (2), h) adding at least one other second gas through a delivering conduit (3) to at least one of the second plurality of secondary gas flows in the respective secondary conduit (2), said delivering conduit (3) protruding into the secondary conduit (2), i) combining the second plurality of secondary gas flows to form a second gas mixture, wherein the amount of the at least one other second gas in step h) is greater than the amount of the at least one second gas in step d).

2. The method according to claim 1, wherein the at least one second gas is added to the secondary gas flow through a respective delivering conduit (3) to the center of the secondary gas flow.

3. The method according to claim 1, wherein a flow rate of the second gas in the delivering conduit (3) is adjusted by supplying the second gas to the delivering conduit (3) using a supplying frequency.

4. The method according to claim 1, wherein a gas flow rate of the second gas in the delivering conduit (3) is grossly adjusted by the opening of a valve (10) in a first step and wherein the gas flow rate of the second gas in the delivering conduit (3) is precisely adjusted by altering the pressure at the inlet of the valve (10) in a subsequent step.

5. The method according to claim 1, wherein a gas flow rate of the second gas in the delivering conduit (3) is grossly adjusted by the opening of a valve (10) in a first step and wherein a flow rate of the second gas in the delivering conduit (3) is precisely adjusted by withdrawing some of the second gas out of the conduit leading to the inlet of the valve (10).

6. The method according to claim 1, wherein the second gas is initially a fluid and is atomized and advanced through the delivering conduit (3) by an atomizing gas.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Particularly preferred variants of the invention and also the technical field will now be explained in more detail on the basis of the figures. It should be noted that the exemplary embodiments shown in the figures are not intended to restrict the invention and are schematically shown in:

(2) FIG. 1 illustrates a first embodiment of the inventive apparatus,

(3) FIG. 2 illustrates a cross sectional view of the first embodiment of the inventive apparatus,

(4) FIG. 3 illustrates a valve operated by a Piezo actuator,

(5) FIG. 4 illustrates a valve operated by a step motor,

(6) FIG. 5 illustrates a second embodiment of the inventive apparatus,

(7) FIG. 6 illustrates a third embodiment of the inventive apparatus, and

(8) FIG. 7 illustrates a dynamic mixer according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

(9) FIG. 1 displays schematically a first embodiment of an inventive apparatus 5. The apparatus 5 comprises a main conduit 1 with a first section 6, a second section 7 and a third section 8. Both the first section 6 and the second section 7 and the second section 7 and the third section 8 are connected by a connecting piece 13, respectively. The connecting pieces 13 comprise holes 12 which form secondary conduits 2. Within each secondary conduit 2 ends a delivering conduit 3 with an end 11 protruding into the respective secondary conduit 2. Temperature control elements 32 are connected to the connecting piece 13 to keep the temperature of the connecting piece 13 constant at a predetermined temperature.

(10) In operation a first gas is provided in the first section 6 of the main conduit 1 and flows in the figure from top to bottom as a main gas flow. The main gas flow is separated into secondary conduits 2 in connecting piece 13 forming a first plurality of secondary gas flows having a secondary gas flow direction 4. A second gas is added to at least a part of the secondary gas flows within the secondary conduits 2 through one or more delivering conduits 3. As the overall cross section of the holes 12 is smaller than the cross section of the main conduit 1 the flow velocity within secondary conduits 2 is larger than the flow velocity in the main conduit 1. The added second gas blends with the secondary gas flow and is advanced into the second section 7 of the main conduit 1. The blended gas mixture is again separated into the secondary conduits 2 of the downstream connecting piece 13 forming a second plurality of secondary gas flows. The inner diameter of the secondary conduits 2 and the inner diameter of the delivering conduits 3 ending in the downstream secondary conduits 2 are larger than the inner diameters of the respective parts of the upstream connecting piece 13. This way the concentration of the second gas in the final gas mixture added in the downstream connecting piece 13 can be larger than the concentration of the second gases added in the upstream connecting piece 13.

(11) In FIG. 2 a cross sectional view through a connecting piece 13 of the embodiment in FIG. 1 is depicted. A connecting piece 13 comprises holes 12, which form secondary conduits 2. Within each of the six outer secondary conduits 2 ends a delivering conduit 3 protruding into the secondary conduit 2, wherein each delivering conduit 3 extends from a valve 10 to an end 11 of the delivering conduit 3 within the secondary conduit 2.

(12) FIG. 3 discloses schematically a valve 10 being operated by a Piezo actuator 20. The valve 10 comprises a valve needle 21 which is pressed against a valve seat 22. A working gas is introduced through valve inlet 23 and can be conducted through the valve 10 to a valve outlet 24. A valve seat opening 25 is opened and closed by the Piezo actuator 20 so that the amount of gas guided through the valve 10 can be regulated by an opening time of valve seat opening 25 and opening frequency, which are also called supplying frequency and supplying time.

(13) In FIG. 4 a high precision valve 10 is depicted. The valve 10 is adjustable by a step motor 14 which operates the valve needle 21, which has an inclination to the vertical of less than 1. The step motor 14 may force the valve needle 21 away from the valve seat 22 so that a second gas may advance from the valve inlet 21 to the valve outlet 24.

(14) FIG. 5 depicts schematically a second embodiment of the apparatus 5. The apparatus 5 comprises a main conduit 1 which is connected to a connecting piece 13, in which secondary conduits 2 are formed. Delivering conduits 3 end within the secondary conduits 2. A second gas is introduced into the secondary conduit 2 by at least one of the delivering conduits 3. The gross adjustment of the amount of second gas supplied by delivering line 3 is adjusted by a valve 10. The fine adjustment of the amount of second gas delivered through delivering line 13 is adjusted by a bellows 15 which is connected to the delivering line 3. The fine adjustment of the flow rate of the second gas in conduit 3 is achieved by withdrawing or adding the second gas by the bellows 15 connected to the delivering conduit 3.

(15) FIG. 6 displays a third embodiment of an apparatus 5 which is similar to the apparatus shown in FIG. 5. In this embodiment a fluid source 16 is connected to one of the delivering conduits 3. The fluid within the fluid source 16 can be pressurized. The fluid is advanced to the valve 10 below the fluid source 16 where it is atomized by a gas which is supplied through a supplying conduit 9 connected to gas source 17. The gas atomizes the fluid from the fluid source 16 and advances the atomized fluid to the secondary conduit 2. A temperature control element 32 is connected to the delivering conduit 3 to keep its temperature constant, which would otherwise be reduced by the evaporating fluid.

(16) FIG. 7 depicts a dynamic mixer 18 with several inventive apparatuses 5. Gases from feed lines 30 can be applied over a evaporator 26 as a first gas to the apparatuses 5, thus forming a main gas flow in the apparatuses 5. Alternatively the gases supplied by feed line 30 can be conducted as second gases to the apparatuses 5 and thus be dosed according to the inventive method. Furthermore, second gases in gas bottles 31 may be applied to the apparatuses 5 to be added to the main gas flow according to the present invention. The gases may be supplied as second gases with a concentration between ppb and percent depending on the delivering conduit 3 and secondary gas flow properties in the secondary conduits 2. The gas mixture is further guided to a mixer 28. A sample of the gas mixture is taken by analyzer 27 for evaluating the concentration of the gases in the gas mixture. The gas mixture is further compressed in compressor 29 and filled in bottles. The temperature of the gas mixture can be measured by temperature sensor 33.

(17) A control unit 19 is connected to the analyzer 27, to the apparatuses 5, the temperature sensor 33 and to the feed lines 30. The control unit 19 operates these elements to generate a gas mixture with predetermined composition to be filled in the bottles. This is achieved by permanently analyzing the gas mixture and resetting the amount of added gases so that the final gas composition has the desired composition.

(18) With the technical teaching of the present invention a dynamic gas bottle filling is possible wherein the second gas components may have a concentration from ppb to percent.

REFERENCE SIGNS

(19) 1 main conduit 2 secondary conduit 3 delivering conduit 4 secondary flow direction 5 apparatus 6 first section 7 second section 8 third section 9 supplying conduit 10 valve 11 end 12 hole 13 connecting piece 14 step motor 15 bellows 16 fluid source 17 gas source 18 dynamic mixer 19 control unit 20 piezo actuator 21 valve needle 22 valve seat 23 valve inlet 24 valve outlet 25 valve seat opening 26 evaporator 27 analyzer 28 mixer 29 compressor 30 feed line 31 gas bottle 32 temperature control element 33 temperature sensor 34 connecting rod