EP1116513A2 - Gas mixing apparatus - Google Patents

Gas mixing apparatus Download PDF

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Publication number
EP1116513A2
EP1116513A2 EP01100767A EP01100767A EP1116513A2 EP 1116513 A2 EP1116513 A2 EP 1116513A2 EP 01100767 A EP01100767 A EP 01100767A EP 01100767 A EP01100767 A EP 01100767A EP 1116513 A2 EP1116513 A2 EP 1116513A2
Authority
EP
European Patent Office
Prior art keywords
gas
nitrogen
minor
major
oxygen
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01100767A
Other languages
German (de)
English (en)
French (fr)
Inventor
Jonathan P. Hanley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Praxair Technology Inc
Original Assignee
Praxair Technology Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Praxair Technology Inc filed Critical Praxair Technology Inc
Publication of EP1116513A2 publication Critical patent/EP1116513A2/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/10—Mixing gases with gases
    • B01F23/19—Mixing systems, i.e. flow charts or diagrams; Arrangements, e.g. comprising controlling means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/10—Mixing gases with gases

Definitions

  • This invention is generally related to an apparatus for producing a gaseous mixture. More specifically, this invention relates to a gas mixing panel which enables the creation of a controlled atmosphere for enhancing the performance of the electronic assembly process in reflow ovens.
  • a controlled atmosphere containing a specific gas characteristic is required to improve the performance of the electronic assembly process in reflow ovens. It is desirable to provide an economical and compact apparatus which can produce a controlled atmosphere.
  • the specific gas characteristic in the atmosphere for optimum reflow performance is preferably from between about 100 ppm and about 10,000 ppm of a minor gas in a major gas, and more preferably from between about 500 ppm to about 2,000 ppm of a minor gas in a major gas.
  • the minor gas may be oxygen or air
  • the major gas may be nitrogen. It is believed that the concentration of oxygen or air in nitrogen between this particular range helps to reduce defects such as tombstoning and solder splatter and improves solderability during the electronic assembly process, particularly in the manufacture of circuit boards. Below about 100 ppm oxygen or air in nitrogen, certain low oxygen defects may occur, and above about 10,000 ppm oxygen or air in nitrogen, certain high oxygen defects occur.
  • the desired concentration of oxygen or air typically between about 100 ppm and about 10,000 ppm in nitrogen which effectuates the optimum performance of reflow ovens is known as the "sweet spot".
  • U.S. Patent No. 6,614,655 discloses the combination of a test gas with a zero gas.
  • the zero gas could be either nitrogen or artificial oxygen; and the test gas (calibration gas) is unspecified.
  • the '655 patent discloses a reduction in the number of critical nozzles necessary to produce different concentrations of the feed streams in the product.
  • the mixing chamber of the gas mixing device in the '655 patent is connected to the outputs of the critical nozzles, which ensure that the outlet pressures are above a certain minimum pressure. Each critical nozzle increases in proportion of 1:2 from one to the next.
  • the critical nozzle receives either the test or zero gas.
  • Valves having two inlets, are placed upstream from the critical nozzles and the two inlets are capable of being alternatively open.
  • the four nozzles have cross sections with openings of 1:2:4:8.
  • the largest nozzle is placed opposite the output of the mixer.
  • a microprocessor activates the valves and monitors and regulates the gas pressures.
  • the gas mixing device in the '655 patent obtains sixteen linearly graduated concentrations of the test gas in the zero gas.
  • Japanese Patent No. 11,033,382 discloses a miniaturized and simplified gas mixing unit. This patent uses a pressure equalizing device to adjust two gases to the same pressure. The two gases are mixed in a gas passing area with a ratio that corresponds to a predetermined mixing ratio. The flow rate can be regulated by an adjusting valve.
  • An aspect of this invention is directed to a compact gas mixing apparatus for accurately mixing a plurality of gases.
  • This apparatus comprises a gas panel, pressure control valves to regulate differential pressures, flow meters and a static mixing chamber.
  • the plurality of gases may be a minor gas and a major gas, where, for example, the major gas is nitrogen and the minor gas is air or oxygen.
  • the major gas and the minor gas are preferably mixed to achieve a gas mixture of from about 100 ppm to about 10,000 ppm oxygen in nitrogen, more preferably in a proportion of from about 500 ppm to about 2,000 ppm oxygen in nitrogen.
  • the pressure control valves regulate the differential pressure to about ⁇ 5 inches of water column.
  • the apparatus is integrated with a reflow oven.
  • oxygen may at times be interchangeable with air. It is noted that oxygen constitutes about 20% content in air.
  • FIG. 1 is a general schematic diagram of the gas mixing apparatus utilizing a differential pressure gauge, flow meters and a static mixing chamber.
  • This invention provides a compact gas mixing apparatus which can produce a mixture of a minor gas and a major gas, preferably oxygen or air as the minor gas, and nitrogen as the major gas, in a concentration of from about 100 ppm to about 10,000 ppm of oxygen or air in nitrogen, and more preferably, from between about 500 ppm to about 2,000 ppm of oxygen or air in nitrogen using a static mixing chamber.
  • This apparatus consists of a fixed, in-line baffle, which causes the gases to shear and swirl, thus providing a homogeneous output.
  • This present invention provides a stable oxygen concentration in a gas mixture that is obtained by mixing nitrogen, and air or oxygen in a mixing panel where the pressure differential between the nitrogen supply and the oxygen supply is measured and controlled to vary by no more than about 5 inches water column.
  • the mixture is homogenized by passing it through a static spiral mixer.
  • the technique is particularly advantageous where the amount of oxygen or air mixed into the nitrogen is sufficient to give a final nitrogen concentration of preferably between about 100 ppm and about 10,000 ppm oxygen or air in nitrogen, more preferably between about 500 ppm and about 2,000 ppm oxygen or air in nitrogen.
  • This invention significantly differs from the prior art design which measures two gas streams, and mixes the gas streams in a surge tank.
  • the present invention uses a static mixing chamber.
  • static mixing chambers consist of fixed, in-line baffles which cause the gases to shear and swirl, providing a homogeneous output.
  • the use of the static mixing chamber offsets the cost of the differential pressure gauge, and contributes greatly to the compact size of the present gas mixing apparatus.
  • a differential pressure indicator is used to ensure that the two gas streams are regulated within 5 inches of water column pressure.
  • the regulated gas stream flows are controlled using a flow meter, such as a rotameter, and are adjusted to deliver the desired measured gas mixture.
  • the two gas streams are then mixed in a static mixing chamber, and the final gas mixture is then delivered to a reflow oven.
  • the present invention produces a stable gas mixture with an accuracy of ⁇ 1 ppm with a gas mixture of 100 ppm.
  • a simple differential pressure gauge produces a accuracy of a wide variety of flow ranges and gas mixtures of up to about ⁇ 1 ppm.
  • the accuracy was improved by assuring identical delivery pressure of the two gas streams to ⁇ 5 inches of water column.
  • the delivery pressure in this invention has been measured to up to about ⁇ 300 inches of water column.
  • a "flat plate” design was constructed to facilitate an in-situ installation in the reflow oven, which allows for a free standing installation.
  • the specification of the gas mixing panel of this invention is as follows: Dimension 24" high x 24" long x 12" deep (61 cm high x 61 cm long x 30.5 cm high) Weight Connections 65 lbs (29.2 kg) Nitrogen Inlet: 1 ⁇ 2" FPT Air Inlet: 1 ⁇ 4" FPT N 2 /Air Mix Outlet: 1 ⁇ 2" FPT N 2 /Air Mix Sample: 1 ⁇ 4" quick-connect Gas Requirement Clean Dry Air 50 scfh (100 psig) minimum Praxair Commercial Grade Nitrogen 3000 scfh (100 psig) minimum
  • Fig. 1 provides one embodiment of the flow scheme of this invention.
  • Nitrogen stream 12 (280-2800 scfh, 5 to 50 scfm) and air stream 14 (2 to 20 scfh) enter at 75 psig.
  • the pressure differential between the streams is measured by differential pressure gauge 24. If the pressure difference is too high, pressure regulator 20 and 22 will adjust until the pressure differences are within about ⁇ 5 inches column water.
  • the streams continue through pressure release valves 16 and 18 (set at 100 psi) prior to passing through flow meters 26 or 28.
  • Flow valves 30 and 32 monitor the flow of the streams depending on the particular composition chosen for the final stream.
  • Check valves 36 and 38 regulate the air and nitrogen gases prior to entering gas mixer 34, which is a static mixing chamber.
  • the gases are mixed and product stream 16 exits, having oxygen content of between about 10 ppm and about 10,000 ppm, depending on the chosen composition.
  • Sample valve 40 leads to flowing sample gases.
  • the differential pressure gauge with a pilot/slave regulator arrangement may be placed on the pure nitrogen and air supplies.
  • the nitrogen regulator would control the delivered nitrogen pressure, and provide a signal to pre-set the air regulator to substantially the same pressure as the nitrogen pressure.
  • Another variation contemplated by this invention is replacing the static mixing chamber with a compact surge tank and a diffuser nozzle on the inlet of the surge tank.
  • the diffuser nozzle would provide the necessary shear and swirl to properly mix the nitrogen and oxygen streams.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Accessories For Mixers (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
EP01100767A 2000-01-13 2001-01-12 Gas mixing apparatus Withdrawn EP1116513A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US48203500A 2000-01-13 2000-01-13
US482035 2000-01-13

Publications (1)

Publication Number Publication Date
EP1116513A2 true EP1116513A2 (en) 2001-07-18

Family

ID=23914375

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01100767A Withdrawn EP1116513A2 (en) 2000-01-13 2001-01-12 Gas mixing apparatus

Country Status (6)

Country Link
EP (1) EP1116513A2 (es)
KR (1) KR20010077978A (es)
CN (1) CN1323650A (es)
BR (1) BR0100060A (es)
CA (1) CA2330813A1 (es)
MX (1) MXPA01000430A (es)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2919725A1 (fr) * 2007-08-02 2009-02-06 Air Liquide Dispositif de dilution d'un fluide
CN102806045A (zh) * 2011-05-30 2012-12-05 上海朗仕电子设备有限公司 一种炉膛用的空气混合装置
JP2016117037A (ja) * 2014-12-22 2016-06-30 三菱化学株式会社 ガス混合装置及び可燃性ガスと酸素含有ガスの混合方法
CN106621870A (zh) * 2016-11-17 2017-05-10 桂林电子科技大学 一种水气浓度可调混合气体发生器
CN107714358A (zh) * 2017-10-30 2018-02-23 潍坊潍医医院 一种氦氧混合自动供气系统
AT521176A4 (de) * 2018-08-28 2019-11-15 Avl List Gmbh Gasmischvorrichtung zur Linearisierung oder Kalibrierung von Gasanalysatoren

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100458267C (zh) * 2007-01-15 2009-02-04 同济大学 一种配气装置
KR100867742B1 (ko) * 2007-10-31 2008-11-10 한국표준과학연구원 중량법을 이용한 혼합가스제조시스템
KR101006888B1 (ko) * 2008-07-10 2011-01-12 강진오 가스혼합장치
CN101507854B (zh) * 2009-03-23 2011-04-20 王中 带压缩空气的呼吸机空氧混合装置
US8445061B2 (en) * 2009-07-17 2013-05-21 Illinois Tool Works Inc. Metering system for hot melt adhesives with variable adhesive volumes
CN101940887A (zh) * 2010-08-27 2011-01-12 天津市华迈燃气技术发展有限公司 一种罗茨混气装置
CN102039092B (zh) * 2010-10-28 2013-08-14 中国石油化工股份有限公司 一种液相氧化工艺中富氧气体的配置方法
EP3476471A1 (de) * 2017-10-25 2019-05-01 Linde Aktiengesellschaft Verfahren und reaktor zur bildung und zur katalytischen umsetzung eines eduktgemischs
CN109469825A (zh) * 2018-12-19 2019-03-15 中石化中原石油工程设计有限公司 一种长输管道天然气加氢气装置及方法
CN109603598B (zh) * 2019-01-15 2021-12-28 南京市江宁医院 一种浓度波动小的气体混合装置

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2919725A1 (fr) * 2007-08-02 2009-02-06 Air Liquide Dispositif de dilution d'un fluide
CN102806045A (zh) * 2011-05-30 2012-12-05 上海朗仕电子设备有限公司 一种炉膛用的空气混合装置
CN102806045B (zh) * 2011-05-30 2014-11-26 上海朗仕电子设备有限公司 一种炉膛用的空气混合装置
JP2016117037A (ja) * 2014-12-22 2016-06-30 三菱化学株式会社 ガス混合装置及び可燃性ガスと酸素含有ガスの混合方法
CN106621870A (zh) * 2016-11-17 2017-05-10 桂林电子科技大学 一种水气浓度可调混合气体发生器
CN107714358A (zh) * 2017-10-30 2018-02-23 潍坊潍医医院 一种氦氧混合自动供气系统
AT521176A4 (de) * 2018-08-28 2019-11-15 Avl List Gmbh Gasmischvorrichtung zur Linearisierung oder Kalibrierung von Gasanalysatoren
AT521176B1 (de) * 2018-08-28 2019-11-15 Avl List Gmbh Gasmischvorrichtung zur Linearisierung oder Kalibrierung von Gasanalysatoren

Also Published As

Publication number Publication date
MXPA01000430A (es) 2003-06-19
CN1323650A (zh) 2001-11-28
BR0100060A (pt) 2001-08-21
KR20010077978A (ko) 2001-08-20
CA2330813A1 (en) 2001-07-13

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