US1947303A - Gas analyzing process and apparatus - Google Patents

Description

.Feb. 13, 1934- J. D. MORGAN 1,947,303

GAS ANALYZING PROCESS AND APPARATUS Filed March 14. 1932 8 Elk-w 74 i: ,l. H W v 0 x H 7 JOHN D.MOR6AN Patented Feb. '13, 1934" 1,947,303 GAS ANALYZING PROCESS AND APPARATUS John D. Morgan, South Orange, N. 1., asslgnor to Dohe'rty Research Company, New York, N. Y., a corporation of Delaware Applieatlon March 14, 1932 Serial No. 598,607

15 Claims. 236-15) This invention relates to combustion control and more especially it relates to a method and apparatus for rapidly and accurately controlling the supply to a combustion zone of one or more elements of combustion. It has special utility in the control of combustion in an internal combustion engine of the automotive type, although it is adapted'for use in the various types of heating,and heat-treating furnaces when op-' erated' either over-ventilated or under-ventilated. It has long been known that a diffusion cell made up of two chambers separated by a porous gas pervious wall can be used for indicating the presence in the air of mines of a small amount of certain gases such as flre damp or gas damp.

When thus used, one of the chambers, after being filled with air, is placed in the mine at. the point where the air is to be tested. It is now known that the rateof diffusion of a gas through 2 a porous diaphragm at a given temperature and pressure is inversely proportional to the square root of the density of such gas. Therefore the lighter gases in the mixture will penetrate through the porous wall in one direction more readily than the heavier gases flow in the opposite direction through the wall, resulting in an increase in pressure in one chambenwhich may be measured directly or may be employed for giving a suitable warning signal. The diffusion 520 in apparatus of this type heretofore known has been slow and the rate of pressure increase therein has been low, making it unsatisfactory for the.

. determination of combustion eificiencies where quick determinations are. necessary in order to permit prompt adjustment of the-air and fuel flowing to the combustion zone. Furthermore it required manual operation, and great care "was needed if comparable results were desired, since the time of exposure of the fluid to the dia- 40 phragm is an important element.

The'gases normally formed in combustion operationscontain varying mixtures .of carbon monoxide, carbon dioxide, hydrogen, methane, nitrogen, oxygen, and sometimes other lwdrocar bone in small amounts. For instance, in the exhaust gases flowing from an internal combustion engine of the automotive type, the percentages ."of the above gases therein vary about as follows:

Carbon dioxide 5.7% to 13.4% C0 13% to 1.2% Oxygen; -l 1.1% 1.1% Hydrogen 7% to 1.2% Nitrogen 71.5% to 84% CH4 1.7% to .1%

The first and second values given for each gas are those found in the exhaust gases from operations at 50% and 95% combustion eflici'ency respectively. The relative rates ofdifiusion of these gaseous components through a phragm are as follows:

Hydrog I i 1 porous dia- Carbon dioxide Carbon monoxide .267 Nitrog n .267 CH4--- .354 Oxyg n .250

Prior to thepresent invention, therefore, a determination of the amount of reducing gases in air required considerable time with the result that such methods were-not adaptedfor the continuous control of an element of combustion flowing to a combustion operation. Applicant has now succeeded in devising a method and an apparatus operating upon the diffusion principle for obtaining rapid indications of the amount of reducing gases present in a combustion gas mixturecontaining a number of different reducing gases, and he has likewise adapted apparatus of this type for continuously controlling the efliciency of a combustion operation.

' According to the present invention a sample of the gases from a combustion operation is continuously withdrawn from a motorexhaust or a furnace and, after being suitably filtered and cooled to a uniform preselected temperature,-- and preferably stripped of any condensed moisture,-is passedinto a compartment of a diffusion cell that is separated from another compartment of the cell by a porous diaphragm suitable composition such' as a mixture of asbestos and steatite molded and flred to the point of vitrification. The diaphragm and associated parts are so designed that 'there is relatively a very large diaphragm surface through which the diffusion may occur; while at the same time the space 'into which the reducing gases diffuse through the diaphragm is. very small, so that a very rapid diffusion of gases mm; small space is facilitated. In this manner, a rapid increase of pressure is developed within the interior space upon passing gases containing light reducing constituents along the opposite face of the dia-' phragm. This pressure then acts upon a suit-.

able manometer or equivalent device by'which it is possible, after suitable calibration, to measure the change in pressure developed within the second or inner chamber in terms of the percentage of reducing gases or combustible constituents in the combustion gases being examined. J

A scale may be associated with' or mounted on the manometer to indicate the amount of reducing gases in the-combustion gases in terms of combustion efliciency of the operation pro-- ducing them. When gasoline or like liquid fuel is combusted in an internal combustion engine of the automotive type the scale may be made in accordance with the following table:

Percent of Percent reducing ggggg:

gases money By suitable arrangements of parts, hereinafter described, the diifusion apparatus is operated intermittently at regular intervals of time and may be adjusted for varying the time interval as desired. Similarly provisions are made for automatically and periodically adjusting the flow of fuel and/or air to the combustion operation at frequent intervals, in accordance with the pressure existing within the diffusion apparatus at regular intervals synchronized with respect to the flow of combustion gases to the diffusion cell.

Such fuel or air adjustments are then maintained until the next adjustment is effected at the end of the succeeding diffusion period. Between each diffusion measurement the inner pressure-building chamber is purged with air or other gas selected as the standard.

By the proper design of difiusion cell so as to obtain as nearly as practicable a maximum of diaphragm surface and a minimum of space in the inner pressure compartment, these successive determinations may be completed and furnace condition adjustments made in periods as short as 30 seconds or one minute.

In the accompanying drawing illustrating more or less diagrammatically apparatus adapted for the practice of the process, Fig. 1 is a somewhat diagrammatic showing of one form of such an apparatus assembly, parts being broken away;

Fig. 2 is a horizontal section through the diffusion cell of Fig. 1 taken along the lines'2--2 thereof;

Fig. 3 is a somewhat diagrammatic showing of one form of apparatus for fuel and air control;

Fig. 4 shows in vertical section another form .of diffusion cell and interassociated parts, portions being broken away;

Fig. 5 is a view taken along the line 5-5 of Fig. 4; and

Fig. 6 is a horizontal section taken along the line 6-6-of Fig. 4.

Referring now to Fig. 1, numeral 10 designates a furnace provided with a fluid fuel inlet 12 and an air inlet 14, the latter being connected through suitable piping with the fan 16 driven by a variable speed motor 18.

For removing from the combustion zone a sample of gas to be examined and for preparing it for the difiusion operation, there is provided a combustion gas ofitake 20 leading from the furnace to a dry filter and drip trap 22, the latter of which may be filled with suitable filtering substance such as glass, steel wool or cotton. From vessel 22 a conduit 24 conducts the filtered gases through water-cooled condenser 26 and thence to a rotaryvalve 28, operated by a motor or the like (not shown) through suitable gearing adjusted to effect a complete rotation-of an inner member 30 of the valve ina preselected time, which maybe adjusted in accordance with the nature of the gases being examined but will generally range from one to one and one-half minutes and upward.

For the purpose of effecting the separation and isolation of different components of the gas mixture in accordance with their specific gravities, there is provided a cell or chamber 32 connected with the valve 28 through the conduits 34 and 36. A conduit. 38 connects the valve 28,with an aspirator 40, adapted to function under the effect of water discharged through the nozzle 42 direct from a source of supply under pressure through line 44,-or the water employed in condenser 26 may be utilized. The aspirator is provided with the usual outlet 46.

Valve 28 has provided therein a pair of passageways so constructed that the respective pairs of lines 24 and 34, and the lines 36 and 38 successively may be interconnected therethrough.

Mounted within the cell or chamber 32 is an annular porous diaphragm 48 separating the space within the cell into a pair of chambers including an outer chamber 50. The diaphragm is of such shape as to have as large as practicable an area of exposure to the gases flowing through chamber 50. In the form shown this diaphragm is star-shaped, A filler member 54, preferably hollow, is provided within the porous member 48, with its side walls spaced close to the inner walls of the latter, defining with these walls a narrow irregularly shaped inner chamber 56. The diaphragm 48 and member 54 may be corrugated to increase the surface for diffusion. The member 54 is made of gas-impermeable material such as metal or its equivalent.

The diaphragm 48 and member 54 are mounted on a base 58 in such manner as to prevent flow of gases between chambers 50 and 56, excepting through the diaphragm. A flat top portion or member 60 serves a similar purpose.

The chamber 56 is in communication at its top with a central tubular member 62 which extends upwardly through the filler member 54. This tubular member 62 extends tln'ough the base 58 of the cell and is then curved to form a leg of 12 manometer tube 64 of small diameter as shown.

The lower part of the chamber 56 is provided with valved outlet lines 66 for the periodic release of any pressure developed therein and for the purging of the chamber. Preferably the outlet 125 lines 66 are provided with valves operating in synchronism with the valve 28 whereby at that point in the path of travel of the inner valve member 30 immediately following the point reached when the combustion control device hereinafter described is actuated, the pressure in chamber 56 is released through the lines 66.

For this purposethe lines 66 lead to an automatic valve or valves 6'7 leading to waste, the said valves being operated in synchronism with the valves 30' through cams 73. A conduit connected with a source of air or other gas under pressure is connected with the upper part of the chamber 56 through a conduit 69 controlled by a valve 71 operated in synchronism with the valve 30 through cam 75.

The leg of the manometer 64 outside of the cell 32 is open-ended and is provided with a plurality of vertically-spaced pairs 'of electric contact members, here respectively designated 68, 70, '72, 74 and '76. Within the manometer is a body of a non-conducting liquid such as light hydrocarbon oil or other suitable organic fiuid, above the surface of which a member '78 is adapted to float. This float member is provided with suitable coni v 1,947,303 ducting material such as platinum foil for the respective solenoid-operated. valves 84 and- 86 having openings of different sizes, each of the valves 84 and 86 being under the control of respective pairs of solenoids 88 and 90, in an electric circuit which comprises a battery or other source of constant electric potential 92 and the various pairs of contacts 70, '72, 74 and 76. The arrangement is such that the solenoids 88, when actuated, act to move the valves associated therewith in the opposite direction to that in which they are moved by the solenoids 90 when the latter are actuated.

The lowermost pair of contacts 68 is in circuit with a solenoid 98 adapted to adjust the flow of current through the three-phase circuit for operating variable speed motor 18. The arrangement is such that upon the completion of the circuit through the pair of contacts 68, the solenoid 98 is actuated in well-known manner to increase the speed of the motor 18 above the normal rate and thus supply more air to the furnace.

For synchronizing the operation of the diffusion apparatus with the device controlling the flow of fuel and air to the furnace so as to make the latter responsive to conditions in the former at the moment immediately prior to the time at which the pressure built up in the inner pressure chamber 56 by diffusion thereto is released,-

the valve 28 is provided with a pair of electric contact members 100 adapted to be periodically,

interconnected through a conductor 102 mounted in the rotary member 30 of the valve. These elements 100 form part of an electric circuit comprising wires 104, 106 and the source of 'elec-- tric current 92. The arrangement is such that just prior to the moment at which'the pressure that has been built up in the chamber 56 is released through lines 66, the electric circuit containing the various solenoids is momentarily .closed and one of the solenoids is energized to adjust the fuel or air flow to the furnace.

Fig. 3 illustrates another formof mechanism adapted for energizing the various solenoids shown in Fig. 1. According to this modification, the free end of the manometer tube 64 isassociated with a-pressure=operated regulating apparatus 110 of well-known construction, having mounted therein a flexible diaphragm 112 of suitable material. The diaphragm 112 is operatively connected with a reciprocating member 114 through the lever member 116 and link 118. The

lever 116 is fulcrumed as 'at 120 and is counterbalanced so that a minimum of pressure is required beneath the diaphragm for actuating the member 114. The last-named member is movable in, guides 122 and has secured to it at spaced points slotted socket members 124, each adapted to house one end of respective levers 126, the

other end of each lever being connected with one of a pair of pivoted mercoid liquid-operated switches 128. The construction of this apparatus is such that when atmospheric pressure exists in the legs of the manometer 64, the respective switches 128 are horizontallydisposed but that I indicated;

as the pressure in the manometer varies from In Figs. 4 to 6 is illustrated a form of diffusion cell in which the inner or pressure-developing r chamber 56 is divided into a plurality of separate cells by the partition members 130. These members as shown extend from the outer wall of the cell 32 to the wall of tube 62; or they may extend from the outer cell wall to the casing 54. The chamber 56 is thereby divided into a number of spaces of equal volume 156, each being adapted to be separately and successively connected with the manometer tube 64. The construction is such as to prevent the escape of pressure developed in one space 156 into any of the other spaces.

l'n this modification, the tube 62 is in the form of a hollow sleeve valve 162 rotatable in an outer fixed valve tube 164/ the latter of which is in communication at its lower ends with the manometer 64. A slot 166 in the upper end of valve 162 is adapted to successively register'with' each of a number of slots in the tube 164, each leading to one of the respective spaces 156 for connecting each of the latter in turn with the manometer. A shaft 167 at the lower end of the rotary member 162 has mounted thereon cams 168 and 1'10, adapted successively to contact with yielding valves on the respective outlet lines .66, andon I the combustion gas inlet lines to the chambers 50. A cam 174 on an extension of member '162 coacts successively with yielding valves on air lines leading from a leader 175 to each inner space 156 opposite the outlet lines66. Gas inlets 15'? and gas outlets "159 to the respective outer chambers 50 are so connected respectively with the conduits 34 and 36 that while the gas mixture being tested is being passed through one of the compartments 50, it is cut off from the others. Alternatively a number of single diffusion cell units may be operatively interconnected in any other suitable manner to function in the manner By so designing the diffusion cell as to provide an inner pressurechamber of small volume and one which is under the pressure effect of gas diifusing through a porous diaphragm of very rextensive diffusion surface, this type of diffusion device has been successfully adapted for the control of a combustion operation where a quick response to changes in conditions within the combustion zone is necessitated. It is possible to build up sumcient pressure rapidly so as to make successive determinations at spaced intervals offrom 30 seconds to 1% minutes or more.

the valve 28. Thus any foreign matter and moisture is removed from the gases. The inner member ofthe valve is continuously rotated under the action of a constant speed motor or the like whereby intermittently for definite periods of time, the gases flow into and through the outer chamber of the difiusion cell and thence out through conduit 36, valve 28 and .conduit 38 to,

a point of discharge. During this period of operation the lighter gravity reducing constituents such as hydrogen and carbon monoxide present in the gases tend to diffuse through the porous diaphragm to the small inner chamber 56 more rapidly than the components of the air in the latter diffuse outwardly therefrom. There thus results a rapid increase of pressure in the inner vesse and in the small or capillary manometer tube 64 connected therewith. The floating electric contact 78 rides upon the top of the liquid in the manometer tube and as it reaches the level of each pair of contacts it is adapted, when contacts 100, 100 are interconnected, to close the electric circuit and energize a corresponding solenoid. As the inner member 30 of the valvecontrolling the flow of gases to the diffusion cell continues to rotate, the flow of gas to the diifusion cell 32 is cut ofi for a predeterminedperiod. Just prior.

to the resumption of gaseousflow through line 24 to the cell 32, the pressure developed in the inner chamber 56 is released by a yielding valve in line 66 which is periodically operated by a cam mounted on a shaft 180 interconnected by gearing (not shown) withthe mechanism rotating the inner valve member 30.

The arrangement of parts controlling the operation of rotary member 30 andthe valves in conduits 66 is such that just prior to the release of pressure'in the inner chamber '56 the main electric circuit is closed through the connector 102 in the rotating member 30. Thereupon a current flows through that pair of contactor members temporarily connected at the momentby the floating contactor 78. The solenoid in such circuit is then energized, either to open or to close a. needle valve controlling the flow of fuel to-the furnace, or to modify the volume'of air fiowin'g to the furnace'from fan 16. 'A moment later the circuit is again broken at the rotarymember 30, and the valves 67 are closed. The solenoid-operated valves are-so constructed that they hold their adjustment when the solenoids operating them are de-energized.

The fluid in the manometer tube may bean electric conductor such as mercury instead of the non-conductor described above. In such instance the contacts in the manometer tube' are so disposed that the current flowing in this case through the mercury of the manometer, when the main electric circuitmomentarily is closed, successively. energizes the solenoids to open or close one fuel valve afterthe other as needed. The'electric contacts 68 are located in the other leg of the manometer tube in this modification. One lead wire connects with the mercury at the lowermost point in the manometen Various other means than those shown may be employed for causing electric current to flow through the circuit at predetermined regular intervals, for the purpose stated.

In instances where the control of combustion Within an internal combustion motor is desired, the construction of the burner 14, fan 16 and associated parts may be modified in suitable manner to provide for. carburetion,-the usual air inlet and Venturi orifice being provided in line 12 between the valve 84 and the motor. The motor 18 under the control of the solenoid 98 may then be employed for operating a butterfly valve in the air inlet line.

While air is the gas generally employed as the standard gas within the inner chamber 56 when beginning the difiusion operation upon a gas being examined, it is within the scope of the present invention to employ in place thereof, hydrogen, helium or other gases having a low specific gravity and a high rate, of difiusibility,- or a high gravity gas such as carbon dioxide.

The invention is susceptible of modification within the seope'of the appended claims.

I claim:

1. In a porous diaphragm gas analyzer contaming an analyzer cell, automatic intermittently within the said cell, means for intermittently returning the pressure within the cell to a preselected standard, and automatic meansresponsive to the pressure within the cell at successive preselected periods and adapted to adjust the fiow of an element of combustion to a combustion chamber.

3. Apparatus for controlling a combustion operation which comprises means, including a porous diaphragm, responsive to the reducing "constituents in a gas mixture and tending to maintain the reducing constituents ,in such mixture at a constant minimum value, and periodically-functioning means responsive when so functioning to a departure of the said reducing constituents from the said minimum value for progressively adjusting the first-named means to restore the reducing constituents to the said minimum value.

4. Automatic means for controlling the flow of an element of combustion to a combustion chamber, which comprises in combination a cell, a porous diaphragm within the cell and adapted to divide the interior thereof into two gas chambers, means for flowing a fluid mixture through one of said chambers, pressure-responsive means op eratively associated with the other of said chambers, means for controlledly connecting the last named chamber with the atmosphere for displacing the gas in such chamber, a conduit leading to a combustion zone and adapted to conduct thereto an element of combustion, and means controlled by the said pressure-responsive means adapted to regulate the flow of the saidelement of combustion through the conduit.

for flowing a fluid mixture through one of said chambers, pressure responsive means operative- 1y associated with the other of said-chambers, means for controlledly connecting the last named chamber with a source of fluid of known composition, a conduit leading to a combustion zone and adapted to introduce thereto a'fluid element of combustion, and means including an electric circuit controlled by the said pressure responsive means for regulating the flow of the said element of combustion through the said conduit.

-6. Automatic means for controlling the efficiency of a combustion operation which comprises in combination a cell, a porous diaphragm asso-" 'ciated with the cell and adapted to divide the interior thereof into two gas chambers, means for withdrawing exhaust gases from a combustion chamber and for filtering the same and cooling them to-a preselected'temperature, means for introducing the filtered and'cooled gases into one oi the said gas chambers, pressure responsive means operatively associated with the other of said gas chambers, a conduit. connected with the combustion chamber and adapted to conduct an element of combustion thereto, and means controlled by the said pressure responsive means for regulating the how of the element'of combustion through the conduit, the said diaphragm and cell being of such shape andsize as to provide in the cell a very large diaphragm diflusion surface and a very small gas space in the last-named gas chamber.

7. Automatic means for controlling the flow of an element of combustion to a combustion ohame ber which comprises in combination a cell, a gas impermeable member withi'n the cell, 'aporous diaphragm within the cell-and surrounding and closely adjacent to'the last-named member and defining therebetween an inner gas'chamber on small volume, and defining with the cell walls an outer chamber, and means for flowing a fluid mixture to be tested through the said outer cham* ber in contact with the said diaphragm, pressure responsive fneans operatively associated with the said inner chamber. of small volume, means for controlledlyconnecting the last-named chamber with asource'oi fluid of known composition for displacing the gases present in the said chamber, a conduit leading to a combustion chamber and adapted to *convey thereto at least one fluid element of combustion, and means controlled by the said pressure responsive means for rjgulating the.

flow of fluid through the said cond 8. Automatic mechanism for controlling the efilciency of a combustion operation which comprises means for withdrawing exhaust gases from such combustion operation, means for cleaning and cooling such gases, and for removing condensed moisture therefrom, means for passing the cleaned and cooled gases under controlled conditions of pressure into contact with a gas pernieable diaphragm separating two gas zones, pressure responsive means'operatively associated with one of the said gas zones, means including an electric circuit controlled by the said pressure responsive means for regulating the flow of combustion supporting gas. to /the combustion zone, means for periodically discontinuing the flow of exhaust gases in contact with the said diaphragm and for releasing the'pressure on the gas zone'associated' with the pressure responsive means, and means for closing thefsaid electric circuit for a short period immediately prior to the said release of pressure. i

9.- Mechanism for regulating the flow of an ele-' tric switch, said switch being in a normally open electric circuitv adapted respectively to control the flow of air and fuel to the combustion chamber, means for periodically discontinuing the flow of gas through the outer chamber, and means associated with the last named means for peri odically closing the said electric circuit.

10. The method of controlling a combustion operation which comprises cleaning and cooling exhaust gases from a combustion operation,

bringing the gases into contact for a preselected period of time with a porous diaphragm surrounding a gas-tight space,and utilizing the pressure condition in the said space at the end of the said period of time for adjusting the flow of an element of combustion to the said combustion operation.

11. A gas analyzing method, comprising withdrawing'waste gases from a combustion opera-' tion, filtering" the same and cooling them to a uniform" regulated temperature, dii fusing the .flltered and cooled gases through a porous diaphragm into a small enclosed space containing a control gas, intermittently measuring the re-' sultant gas pressure within the saidenclosed space, and subsequently releasing the pressure within the enclosed space and purging the difiused gases from the latter with thesald control gas.

12. A gas analyzing method, comprising with-- drawing waste gases from a combustion operation, filtering the same and diffusing the filtered gases through aporous diaphragm into a small enclosed space containing a control gas, intermittently measuring the resultant gas pressure )ivithin the saidenclosed space, and thereafter purging the difiused gases from the latter.

13. In a porous diaphragm gas analyzer, in combination ,a cell, a porous diaphragm within the cell and adapted to divide the interior thereof into two gas-tight chambers, means for flowing a fluid-mixture at a, regulated rate through one or the said chambers, calibrated pressureresponsive means operatively connected with the other of'the said chambers, automatic means for controlledly connecting the last-named chamber with the atmosphereat spaced intervals ,and for displacing the gas in that chamber, and automatic means adapted periodically to flllthe lastnamed chamber with a standard gas.

1 4.In a'porous diaphragm gas analyzer, a gas tight analyzer cell divided into a large compartment and'a small compartment by a porous diaphragm having a large surface area, means adapted to conduct filtered combustion gases through thes'aid large compartment, meansfor interrupting the said gas flow at regulated intervals, means responsive to the pressure in the other of said compartments, means controlled by vthe said pressure-responsive means and adapted when energized to adjust the flow of an elementbi combustion to a combustionchamenergizing the last-named means.

15. In a porous diaphragm gas analyzer, an analyzer cell divided into a large compartment and a small compartment by a porous diaphragm ber, and automatic mechanismior periodica1lyof combustion to a combustion chamber, automatic mechanism for periodically energizing the last-named means, and means associated with the small compartment for periodically purging the latter of combustion gas components by means of a standard gas.

JOHN D. MORGAN.

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