US3672840A

US3672840A - Determination and control of a composition characteristic while blending a multi-component combustible fluid

Info

Publication number: US3672840A
Application number: US37614A
Authority: US
Inventors: Ellsworth R Fenske; Robert W Sampson
Original assignee: Universal Oil Products Co
Current assignee: Honeywell UOP LLC; Universal Oil Products Co
Priority date: 1970-05-15
Filing date: 1970-05-15
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27

Abstract

A BLENDING PROCESS WHEREIN A PLURALITY OF COMPONENT FLUIDS IS CONTINUOUSLY INTRODUCED INTO A BLENDING ZONE PRODUCING A COMBUSTIBLE FLUID MIXTURE, A METHOD AND APPARATUS FOR CONTINUOUSLY DETERMINING AND CONTROLLING A COMPOSITION CHARACTERISTIC OF THE COMBUSTIBLE FLUID MIXTURE, SUCH AS THE OCTANE RATING OF A GASOLINE BLEND. A SAMPLE OF THE FLUID MIXTURE AND A SAMPLE OF A REFERENCE FUEL ARE SIMULTANEOUSLY OXIDIZED IN AN ANALYZER COMPRISING A STABILIZED COOL FLAME GENERATOR WITH A SERVO-POSITIONED FLAME FRONT, EACH FUEL BEING BURNED IN AN INDIVIDUAL COMBUSTION CHAMBER. THE POSITION OF EACH FLAME FRONT IS AUTOMATICALLY DETECTED AND UTILIZED TO MANIPULATE A COMBUSTION PARAMETER IN THE ASSOCIATED COMBUSTIONN CHAMBER IN A MANNER SUFFICIENT TO IMMOBILIZE THE FLAME FRONT GENERATED THEREIN. MEANS IS PROVIDED FOR SENSING THE MANIPULATED COMBUSTION PARAMETER OF EACH COMBUSTION CHAMBER, AND DEVELOPING THEREFROM A CONDITION OUTPUT SIGNAL WHICH IS FUNCTIONALLY REPRESENTATIVE OF AND CORRELATABLE WITH COMPOSITION CHARACTERISTIC FOR THE FLUID MIXTURE SAMPLE. MEANS IS ALSO PROVIDED FOR ADJUSTING THE CONDITION OUTPUT SIGNAL RESPONSIVE TO ANALYZER TEMPERATURE FLUCTUATIONS AND COMPONENT CHANGES IN THE BLENDING ZONE. THUS, THE CONDITION OUTPUT SIGNAL IS COMPENSATED FOR COMBUSTION EFFECTS NOT INDICATIVE OF COMPOSITION CHARACTERISTIC, AND IS THEREBY RENDERED FUNCTIONALLY REPRESENTATIVE OF AND CORRELATABLE WITH THE TRUE COMPOSITION CHARACTERISTIC OF THE FLUID SAMPLE OF BLENDED PRODUCT.

Description

.Bum 27, E972 E. R. FENSKE ETAL 3,672,840

DETERMINATION AND CONTROL OF A COMPOSITION CHARACTERISTIC WHILE BLENDING A MULTI-COMPONENT COMBUSTIBLE FLUID Filed May l5, 1970 2 Sheets-Sheet l A TTOR/VEYS I uw IT \m\ /t Smm P I mw/ I on s 0, 0 nv m /mk ummlmm T F I I N RS J@ E /S /L Vmw @w NW MM/ 22g. E@ MM .I D H o I/ 2 .NQ /K k ESG PQ vn /S TQ B vm. GSQQS I RIE@ I. I J mw Q\ S Nm m I w A I .I||. umbm I/ I: I/ I www mK Nk.\ /LAQ BSL I al .L IWI I. b 2G RSQ vk MNH I: .I i NN IMU .www I mm|\ /ISQEQQ k\ Q0, III w. .III GSQQ Mm. mm u .um f v/ I: u.) I I. I. QT@ /I mutans@ PGPG km. Nm G I/ I.: I/ I .I /I .I vmL /Ewmw n I. Il WW mEmmm S EG, mQmQ w @NIU mv AQQ @SNES QQ M f I: I bv eww. I Nr /Imcmum 2258@ Il WN @IN vv June 27, 1972 E. R. Fr-:NsKE ETAL 3,672,840

DETERMINATION AND CONTROL OF A COMPOSITION CHARACTERISTIC WHILE BLENDING A MULTI-COMPONENT COMBUSTIBLE FLUID Filed May l5, 1970 2 Sheets-Sheet 2 Inl .r (E t mw/ /nl SEIS mt /V VE N T0 R S.- E /lsworfh Fenske Robe/f W. Sampson ATTORNEYS United States Patent ce 3,672,840 Patented June 27, 1972 3,672,840 DETERMINATION AND CONTROL OF A COM- POSITION CHARACTERISTIC WHILE BLENDING A MULTI-COMPONENT COMBUSTIBLE FLUID Ellsworth R. Fenske, Palatine, and Robert W. Sampson,

Arlington Heights, Ill., assignors to Universal Oil Products Company, Des Plaines, Ill.

Filed May 15, 1970, Ser. No. 37,614 Int. Cl. F23n 5/00; G01n 25 /46, 33/32 U.S. Cl. 23-230 PC 19 Claims ABSTRACT OF THE DISCLOSURE A blending process wherein a plurality of component fluids is continuously introduced into a blending zone producing a combustible uid mixture, a method and apparatus for continuously determining and controlling a composition characteristic of the combustible fluid rnixture, such as the octane rating of a gasoline blend. A sample of the fluid mixture and a sample of a reference fuel are simultaneously oxidized in an analyzer comprising a stabilized cool flame generator with a servo-positioned ame front, each fuel being burned in an individual combustion chamber. The position of each flame front is automatically detected and utilized to manipulate a combustion parameter in the associated combustion chamber in a manner suicient to immobilize the flame front generated therein. Means is provided for sensing the manipulated combustion parameter of each combustion chamber, and developing therefrom a condition output signal which is functionally representative of and correlatable with composition characteristic Ifor the iluid mixture sample. Means is also provided for adjusting the condition output signal responsive to analyzer temperature fluctuations and component changes in the blending zone. Thus, the condition output signal is compensated for combustion effects not indicative of composition characteristic, and is thereby rendered functionally representative of and correlatable With the true composition characteristic of the fluid sample of blended product.

BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for determining a composition characteristic of a combustible fluid mixture. It further relates to an improx/ement in the method and apparatus for determining a composition characteristic of a combustible fluid mixture utilizing a stabilized cool ame generator with a servo-positioned flame front. It particularly relates to an improvement in the method and apparatus for determining a composition characteristic of a combustible fluid mixture produced by blending a plurality of component fluids, and for controlling the blending process to produce a mixture having a constant predetermined value of composition characteristic. It more specifically relates to an improved method and apparatus for determining the octane number of a gasoline blend produced from a plurality of blending components, and for controlling the blending operation to produce a gasoline product ofcoustant octane rating.

Those skilled in the art are familiar with the phenomenon of cool ame generation. Briey, when a mixture of hydrocarbon vapor and oxygen at a composition Within the explosion limit is held at conditions of pressure and temperature below the normal ignition point, partial oxidation reactions occur which generally result in the formation of by-products, such as aldehydes, carbon monoxide, and other partially oxidized combustion products.

These products are apparently produced via a chain reaction which, it is believed, also produces ions which then in some manner continue the reaction chain. If such a mixture of hydrocarbon vapor and oxygen is isolated and compressed and/or heated so that these chain reactions proceed at significant reaction rates, then cool flames are observed within the chamber. The cool flames are characterized as light emissions accompanied by the evolution or relatively minor amounts of heat.

Implicit in this definition is the fact that the phenomenon of cool flame generation is short of total combustion and short of total ignition and explosion. The work of Barusch and Payne in Industrial and Engineering Chemistry, volume 43, pages 2329-2332, 1951, describes in detail the results which can be obtained from continuous or stabilized cool flames.

Basically, the utilization of this phenomenon in the practice of the present invention is one of manipulating a combustion parameter in a manner suicient to immobilize the cool ame relative to one end of the combustion chamber. The manipulated combustion parameter is sensed and utilized to develop a condition output signal which is functionally representative of and correlatable with the composition of the uid being oxidized in the combustion chamber.

A more complete explanation and description of the basic apparatus and basic method for detecting composition characteristics utilizing cool ames is contained in U.s. Pat. 3,463,613, issued on Aug. 26, 1969, to E. R. Fenske and J. H. McLaughlin. The contents of said patent are incorporated herein by reference so that a greater detailed discussion need not be presented in this application. Those skilled in the art are referred directly to the entire teaching contained in said patent for additional and specific details as to the construction of a preferred embodiment of the basic apparatus and method of operation thereof. As will be more fully developed hereinafter, the present invention describes and claims an improvement in the basic method and apparatus disclosed and claimed in said patent.

One of the difficulties encountered in the method an apparatus disclosed in U.S. Patent 3,463,613 is concerned with calibration of the apparatus to compensate for combustion effects which are not indicative of composition characteristics of the fluid being analyzed.

For example, it has been found that when the apparatus disclosed in the U.S. Pat. 3,463,613 has been operated on a combustible uid for a substantial length of time, the apparatus occasionally begins to produce condition output signals which reflect aging of the apparatus. This aging may be introduced due to plugging of preheaters or plugging of a flow difiusor element which is mounted in the interior of the combustion chamber a short distance above the combustion nozzle. Additionally, it has been found that where a leaded gasoline is the combustible iiuid being analyzed, deposits of lead oxides Within the combustion chamber may introduce combustion effects which are not indicative of the composition characteristic of the gasoline fraction being burned Within the chamber.

It has further been discovered that Ifluctuations in the oxidizer passing into the combustion chamber will introduce combustion effects which will result ina condition output signal containing an error which is not correlatable with the composition characteristics of the fluid being burned within the chamber. For example, the typical oxidizer passing into the combustion chamber is derived from a compressed air system, and the compressed air will contain microscopic quantities of entrained lubricating oil which have been picked up at the air compressor. Additionally, it has been found upon occasion that a shift in the wind direction will introduce flue gas from nearby furnace stacks so that the air compressor is periodically picking up air containing combustion products. This results in an oxidizer passing into the combustion chamber ofv the instant analyzer which is not only deficient in oxygen, but which also may contain a considerable proportion of further combustible material such as the carbon monoxide and the unburned hydrocarbons contained in the fiue gas.

Furthermore, it is typical in the art to place the cornbustion analyzer of the instant invention in a local mounting near the product stream which is to be analyzed, and to transmit condition output signals therefrom to the control house in the refinery or chemical plant wherein the apparatus is utilized for monitoring or controlling service. Consequently, the combustion chamber of the apparatus is located out-of-doors and is subject to thermal fluctuations due to atmospheric conditions, These iiuctuations in atmospheric conditions produce thermal effects within the combustion chamber which are not indicative of the cornposition characteristic of the fiuidbeing analyzed therein.

Additionally, it is known that the specific nature of the correlation between the condition output signal generated by the apparatus and the actual value of composition characteristic is a function of the actual molecular composition of the fluid being analyzed by the combustion producing the cool fiame. For example, where the fiuid being analyzed comprises a hydrocarbon mixture, the correlation between the condition output signal and the composition characteristic will be a function of the hydrocarbon tiuid composition and the carbon number of the hydrocarbon constituents present therein. Furthermore,

Athe correlation is further inuenced by the presence or absence of paraffins, isoparafiins, olefins, diolefins, polyolefins, aromatics, long-chain substituted aromatics, polynuclear aromatics, etc. Thus, as normally operated in commercial practice, the apparatus of the present invention is capable of continuously analyzing a particular type of hydrocarbon blend or sample fluid, and relatively small deviations due to fluctuations in molecular species can be accounted for.

However, where the apparatus of the present invention is utilized in a blending process wherein a plurality of component fiuids are blended together in varying proportions to produce iluid mixtures of varying composition characteristics, wide tiuctuation in the molecular species contained within the final mixture may result in combustion effects which are not indicative of the true composition characteristic of the resutling blend. For example, in a typical gasoline blending system, blends will be made to produce various qualities of gasoline having different octane ratings and different volatility characteristics from season to season, and even from day to day or hour to hour. Thus where a 98 octane rating is desired, the gasoline blend may be high in reformate gasoline and thereby highly aromatic, and it will typically contain some anti-knock agent such as tetraethyl lead or tetramethyl lead. On the other hand, when a 98 octane rating is desired but reformate gasoline is not always available in a sufiicient quantity, the resulting blend may periodically be higher in paraflinic constituents such as straight-run gasoline, and it will then be higher in anti-knock agents. Similarly, at some periods in the blending operation the gasoline blend may contain a substantial amount of isoparatiinic gasoline, such as motor alkylate, and at other periods it may contain none. Furthermore, the apparatus of the present invention may be utilized in making more than one gasoline blend during a given day, each blend meeting a different specification and composition effects from blend to blend may introduce deviations in the conditions output signal developed by the apparatus Which are not actually due `to changes in composition characteristic such as octane rating, but which are due to changes in the component distribution of molecular species within the blend sample being burned to produce the stabilized cool flame.

4 SUMMARY OF THE INVlhI'TlONY Accordingly it is an object of the present invention to provide an improved method and apparatus for analyzing a combustible fluid mixture. A y

It is another object of the present invention to provide an improved method and apparatus'for determining a composition characteristic of a combustible `fluid mixture in a stabilized cool flame generator with a servo-positioned r flame front.

It is a further object of the present invention to provide a method and apparatus for determining a composition characteristic of a combustible fluid mixture produced by blending a plurality of component iiuids, and for controlling the blending process to produce the mixtureat a constant predetermined value of composition characteristic.

It is a particular object of the present invention to provide an improved method and apparatus for determining the octane rating of a gasoline blend produced from a plurality of blending components, and for controlling the blending operation to produce a gasoline blend having a constant octane rating, Y

Therefore in its method aspects, a broad embodiment of the present invention provides a method for detecting'a composition characteristic of a combustible fluid mixture produced by combining a plurality of component fluids which comprises: (a) introducing a sample stream of said fluid mixture and a stream of oxygen-containing gas into a first end of a first combustion chamber containing a first induction section maintained at elevated temperature; (b) simultaneously introducing a stream of reference fuel having a known composition characteristic, and a stream of oxygen-containing gas into a second end of a second combustion chamber containing a second induction section maintained at elevated temperature; (c) partially oxidizing said 'sample stream in said first combustion zone under conditions sufficient to generate and maintain therein, a first cool flame characterized by arelatively narrow well-defined iiame front spaced Yfrom said first end; (d) partially oxidizing said stream of reference fuel in said second combustion zone under conditions sufficient to generate and maintain therein a second cool flame characterized by av relatively narrow well-defined flame front spaced from said second end; (e) sensing the position of said first llame front relative to said first end, and developing therefrom a first control signal; (f) sensing the position of said second flame front relative to said second end, and developing therefrom a second control signal; (g) utilizing said first control signal to adjusta combustion parameter selected from the group consisting of combustion zone pressure, induction section tempera.- tu-re, sample stream flow rate, and oxygen-containing gas stream ow rate, in a manner sufficient to immobilize said first flame front relative to said first end regardless of fluctuations in the composition characteristic of said sample stream; (h) utilizing said second control signal to adjust a combustion parameter selected from the group consisting of combustion zone pressure, induction section temperature, reference fuel flow rate, and oxygenoontaining gas stream flow rate, in a manner sufficient to immobilize said second fiame front relative to said second end regardless of fluctuations in the combustion of said reference fuel; (i) sensing the adjusted parameter of said first combustion chamber and developing therefrom a first parameter signal responsive to changes in said composition characteristic of said sample stream; (j) sensing the adjusted parameter of said second combustion chamber and developing therefrom a second parameter signal functionally representative of the known composition characteristic of said reference fuel; (k) developing a component signal representative of the relativeI amount of a first component fiuid of said plurality contained in said combustible fluid mixture; and, (l) passing saidfirst parameter signal, said second parameter signal, and 'said component signal into signal conditioning means, and producing therefrom a condition output 'signal compensated for sample stream combustion effects not indicative of composition characteristic, whereby said condition output signal is functionally representative of the composition characteristic of said combustible fluid mixture.

Furthermore. in its method aspects, a particular broad embodiment of the present invention provides the method of the above defined broad embodiment wherein said combustion chambers are commonly confined in an elevated temperature zone, a temperature of said elevated temperature zone is sensed and a temperature signal is developed therefrom, and said temperature signal is passed to said signal conditioning means, whereby said condition output signal is rendered representative of the composition characteristic of said fluid mixture as corrected for temperature deviations.

In addition, in its apparatus aspects, a broad embodiment of the present invention provides a composition analyzer for detecting a composition characteristic of a cornbustible fluid mixture produced by combining a plurality of component fluids, which comprises in combination: (a) a first combustion chamber containing a first induction section; (b) a second combustion chamber containing a second induction section; (c) means for generating within said first combustion chamber, a cool flame characterized by a relatively narrow Well-defined ame front, utilizing as fuel therefor said combustible fluid mixture to be analyzed, said generating means including means passing a stream of said fluid mixture and a stream of oxidizer into said first combustion chamber; (d) means for generating Within said second combustion chamber, a cool ame characterized by a relatively narrow well-defined llame front, utilizing as fuel therefor a reference fuel having a known value of composition characteristic, said generating means including means passing a stream of saidreference fuel and a stream of oxidizer into said second combustion chamber; (e) first position sensing means sensing the physical position of said flame front within said first combustion chamber; (f) second position sensing means sensingthe physical position of said flame frontrwithin said second combustion chamber; (g) rst control means coupled to said first position sensing means, and adapted to adjust a combustion parameter selected from the group consisting of combustion pressure, induction section temperature, fluid stream flow rate, and oxidizer flow rate, in a manner sufiicient to immobilize said first ame front in a constant position relative to said first combustion chamber; (h) second control means coupled to said second position sensing means, and adapted to adjust a combustion parameter selected from the group ,consisting ofcombustion pressure, induction section temperature, reference fuel stream flow rate, and oxidizer flow rate, in a manner sufficient to immobilize said second flame front in a constant position relative to said second combustion chamber; (i) means sensing the adjusted parameter of saidufirst combustion chamber and developing a first parameter signal functionally representative of the `composition characteristic of said fluid stream; (j) means sensing the adjusted parameter of said second combustion chamber and developing a second parameter signal functionally representative of the known compsition characteristic of said reference fuel; (k) means developing a component signal representative of the relative amount of a first component liuid of said plurality contained in said combustible fluid mixture; and, (l) signal conditioning means receiving said first parameter signal, said second parameter signal, and said component signal, and producing therefrom a condition output signal functionally representativel of and correlatable with the composition characteristic of said fluid mixture.

Still further, in its apparatus aspects, a particular broad embodiment provides the above defined broad embodiment of composition analyzer wherein there is provided an outer chamber confining said combustion chambers in an elevated temperature zone, means sensing a temperature in said elevated temperature zone and developing a temperature signal, and means transmitting said temperature signal to said signal conditioning means, whereby said condition output signal is rendered functionally representative of composition characteristic as corrected for temperature deviations.

In essence therefore, the present invention provides a method and apparatus which determines the composition characteristic of a combustible fluid mixture by oxidizing the fluid in a stabilized cool flame generator with a servoposition flame front to develop a condition output signal which is compensated for fluctuations in the relative proportion of component fluids passing into the blending system which produces the mixture, and which is continuously recalibrated to compensate for deviations in parameter output signal generated by a reference fuel of known composition characteristic. Furthermore, the condition output signal is compensated for temperature fluctuations occurring within the inventive apparatus. In this manner then, the condition output signal is continuously compensated for combustion effects which are not indicative of composition characteristic, and the condition output signal is thereby rendered functionally representative of and correlatable with the true composition characteristic of the combustible fluid blend being analyzed. Thus as shall be set forth more fully hereinafter, the apparatus of the present invention is readily adaptable for controlling the blending process to produce a final product having a constant predetermined value of composition characteristic, such as octane number in a gasoline blending operation.

As used herein, the term composition characteristic does not refer to a compound by compound analysis of the type presented by instruments such as mass spectrometers of vapor phase chromatographs. Rather, the composition characteristic s represented by a continuous, or substantially continuous, output signal which is responsive to and indicative of the fluid composition, and which is more specifically, emperically correlatable with one or more conventional composition identifications or specifications. For example, when the fluid to be analyzed is a hydrocarbon composition, the composition characteristic which is represented by the condition output signal may be a conventional identification or specification such as the Reid Vapor Pressure, ASTM or Engler distillation, initial boiling point, end boiling point, etc. In particular, when the fluid being analyzed comprises gasoline boiling range hydrocarbon, the composition characteristic which is functionally `represented by the condition output signal will typically comprise a knock characteristic such as research octane number or motor octane number As `used herein, the terms output signal, condition output signal and parameter signal are to be construed in their most meaningful sense and include analog signals of all types, such as amplitude-modulated, phasemodulated, or frequency-modulated electrical signals or pressure signals by conventional pneumatic transmission media, as well as digital representations thereof. These terms are further intended to include simple mechanical motion or displacement of a transducer member (whether or not mechanically, electrically, or pneumatically coupled to a physical display means, such as an indicating arm, recorder pin, or digital display board)v including by way of illustration, the expansion or contraction of a Bourdon tube, pressure spiral or helix, the displacement of a bellows-dapper, nozzle-diaphragm, or differential transformer-core assembly, the movement of a bimetallic temperature responsive element, the motion of a slider of a self-balancing potentiometer, etc.

The condition output signal may be transmitted without physical display directly to reset a final control unit, such as a diaphragm motor valve or a sub-control loop in a cascade system. More commonly, however, the condition output signal will pass to a readout device which will comprise or will be coupled to an indicating or recording means, the scale or chart of which may be by the thermocouple means activates appropriate control means for adjusting a combustion zone parameter or condition so as to immobilize the cool flame front at a position generally between the two spaced thermocouples. A most satisfactory combustion condition which can be used as the control means is the combustion zone pressure.

Test samples which can be continuously analyzed by this invention include normally 4gaseous and normally liquid combustible chemicals. In a particularly preferred embodiment, the test samples comprise hydrocarboncontaining mixtures. These mixtures typically comprise at least one hydrocarbon containing from 1 to about 22 carbon atoms per molecule in admixture with one or more non-hydrocarbons such as hydrogen, nitrogen, carbon monoxide, carbon dioxide, water, and hydrogen sulfide. Alternatively, these mixtures will comprise at least two different hydrocarbons containing fromvl to about 22 carbon atoms per molecule. The upper limit oncarbon number is fixed generally by the preferred operational procedure whereby the test sample and the reference fuel sample are vaporized in an air stream under combustion conditions without undergoing any substantial thermal decomposition prior to the oxidation thereof.

Therefore, in the context of the present invention, the terms combustible fluid mixture and combustible fluid are intended to embody all forms of combustible fluids which are capable of vaporization within the apparatus, and particularly hydrocarbon mixtures in which hydrocarbons predominate, but which may also contain significant amounts of non-hydrocarbon materials. In particular, the hydrocarbon fiuids may contain such items as tetraethyl lead, tetramethyl lead, and other known anti-knock compounds for use in motor fuel compositions. In the preferred and practical embodiment of this invention, wherein the determined composition characteristic is the measurement of octane rating, the feedstocks or test samples of unknown octane number whichare chargeable to the apparatus of the present invention include those Within the gaseoline boiling range produced by blending such component fiuids as straight-run gasoline cracked gasoline motor alkylate, catalytically reformed gasoline, thermally reformed gasoline, hydrocracker gasoline, etc.

As noted hereinabove, the apparatus of the present invention will be continuously recalibrated and compensated for combustion effects which are not indicative of the composition of the fluid being analyzed or of the composition characteristic being developed as the condition output signal. In order to achieve thisfcompensation in the condition output signal, there is provided means for continuously comparing the blended'liuid with a reference fuel of known composition characteristic. Those skilled in the art are familiar with the procedures for obtaining reference fuels of known composition. Since the reference fuel is being compared to the unknown blended fluid, it is desirable that the hydrocarbon species of the reference fuel be similar to those of the unknown fluid being tested. Thus for example, if" the fluid being analyzed is a hydrocarbon comprising a gasoline blend having an octane number of about 95 and consisting primarily of a reformate gasoline, it is'particularly desirable, but not essential, that the reference Afuel also have an octane rating ofabout 95 and that it primarily comprise a reformate gasoline.

The oxidizer or oxidizing agent utilized inthe apparatus of the present invention is preferably an oxygencontaining gas, suchas air, substantially pure oxygen, etc. or it may be a synthetic blend of oxygen with an inert or equilibrium effecting diluent, such as nitrogen, carbon dioxide or steam.

-The generation of the stabilized cool ame is effected 'under combustion conditions generally-including superatmospheric pressure and elevated temperature, although in some cases, it may be Vdesirable to .use atmospheric pressure or sub-atmospheric pressure. For example, the pressure may be in the range from about l5 p.s.i.a. to about V p.s.i.a. with a maximum iiame front temperature in the range of 600 F. to 1000 F. For measuring the composition of a gasoline boiling range fraction it is preferable' to employ pressures in the range from 16 p.s.i.a. to 65 p.s.i.a., more preferably, in the range from 16 p.s.i.a. to 30 p.s.i.a., together with an induction zone temperature of'from about 550 F'. to about 850 F. Control of induction zone temperature can be effected by the amount of preheat imparted to the air or oxidizer stream and to the incoming sample stream, including the test'fsa'mple and the reference sample. Furthermore, in-

duction zone temperature may be manipulated by adjusting the input of heat from an external source to the combustion zone proper. In any case, the permissible limits within which temperature and pressure may be individually .varied without departure from stable operation, even outside of the specific operational limits referred to herein, can be determined by simple experiment for a particular type and quantity of combustible uid sample.

As previously mentioned, the detection of the position within the combustion chamber for the test sample and for the reference sample is preferably effected by temperature responsive thermoelectrical means, although, other equivalent means can be used. The thermocouple-sensing device many be placed within the combustion chambers, as discussed hereinabove, or outside of the combustion chamber, and may be either fixed or-maybe movable-in such a manner as to completely'and substantially traverse the length-wise direction of the combustion chamber in order to locate the position of the stabilized cool' flame within the combustion chamber. j

The Aoutput signalY from the thermocouple sensing means is fed through signal means to suitable control Vmeans such as a motor activated control valve for regulating, preferably, the pressure within the combustion zone. Generally, the output signal from the thermocouple vsensing means is not sent to a readoutdevice, such as a strip c hart` or x-y recorder,A for to do so would deplete the strength of the signal to` such an extent that operational efficiency might be impaired. Preferably, the thermocouple sensing device comprisesa pair of axially spaced thermocouple leads which are inserted into thin-walled thermaltypepencil wells and may be constructed of any materials known to thosek skilled in the art, such yas for example., iron-constantan. The lead wires from, the ther- VKmowells are connectedto a suitable differential ltemperature controller. Suchgcontroller maybe a ,conventional `self-balancing potentiometerin combination with pneumatic control means. A suitable input span for the controller may be from -5 to y-l-S millivolts and the output signal lthereof Vtransmitted may be a conventional 3-15 p.s.i.a. air. signal. This control signal is used, for example, to reset the set point on a back pressure'controller or can be used to directly control the pressure within the combustion zone. t 'The present inventionlmay be more fully understood by nowreferring'to the accompanying drawings.

lFIG. 1 comprises a simplified schematic representation of the" apparatus Vfor practicing the present invention in a typical'gasoline blending system wherein the signal con- 9 ditioning means is a computer means, which may be an analog computer or a digital computer.

FIG. 2 illustrates a schematic representation of the apparatus for practicing the present invention in a typical gasoline blending system wherein the signal conditioning means comprises an analog or a digital network.

DESCRIPTION OF THE DRAWINGS With reference now to the accompanying FIG. 1, there is shown a typical blending system wherein a plurality of gasoline blending components are passed into a blending zone to produce a finished blended gasoline having a predetermined composition characteristic, such as octane rating. A reformate gasoline stream enters the blending process .via line 1 and a straight-run gasoline stream enters line 1 via line 2. Typically, the gasoline blending system will blend at least two component gasolines, but for illustrative purposes various component gasoline fractions are shown in FIG. 1, in order to illustrate the various types of hydrocarbon constituents which may be blended together. Thus, there is shown in FIG. 1 an alkylate gasoline fraction entering line 1 via 'line 3, a cracked gasoline fraction entering line 1 via line 4, a volatility component such as butane and/or pentane entering line 1 via line S, and an anti-knock agent such as a lead alkyl entering line 1 via line 6.

The reformate gasoline fraction is a highly aromatic stock, while the straight-run gasoline fraction is a blending component which is high in normal paraffins and in naphthenes. The alkylate gasoline fraction is a blending component which is high in isoparafflns, while the cracked gasoline fraction is a stock which is high in olefins. Therefore, the relative amount of each component passing into the blend, and fluctuations thereof, will produce individual combustion effects in the analyzer of the present invention which introduce deviations in the condition output signal which are not indicative of the blended composition characteristic being determined.

The combination of blending components passes via line 1 into a mixing or blending zone, which for illustrative purposes is shown in FIG. l as an in-line blender 7. The final gasoline blend is discharged from in-line blender 7 via line 8 and a sample of the finished blend is withdrawn therefrom via line 9.

The test sample of line 9 continuously flows into line 11 wherein it is contacted with an oxidizer, such as compressed air, entering line 11 via line 10. The test sample of gasoline blend and the oxidizer mix in line 11 as they flow into the analyzer of the present invention.

The apparatus of the present invention comprises in combination a canister 12 enclosing two combustion chambers 13 and 14. Chamber 13 is provided for the combustion of the test sample and chamber 14 is provided for combustion of reference fuel as shall be set forth hereinafter. The canister has means for introducing a heat transfer fluid to surround the combustion chambers so that proper temperature conditions may be maintained within the combustion zones by controlling temperature in an elevated temperature zone 38 which is confined between the canister 12 and the combustion chambers 13 and 14. The configuration of the apparatus will be similar to that described in the cited U.S. Pat. 3,463,613. Thus, the temperature within the elevated temperature zone 38 may be maintained by a constant circulation of a heat transfer fluid from an external source, or by conduction and natural convection of the heat transfer fluid as provided by immersion heaters contained within the canister and within the zone 3S, or heating elements encompassing the canister. If desired, the exterior of the enclosing canister 12 may be encased in one or more layers of insulation, not shown, and typically this will be done since the canister is normally located out-of-doors and exposed to atmospheric conditions. Those skilled in the art being familiar with the teachings presented herein and with the teachings presented in the cited patent will l0 understand the appropriate manner of enclosing the combustion chamber in a suitable canister having appropriate temperature control means and having appropriate thermal insulation in order to minimize the thermal effects of atmospheric conditions.

With reference to the combustion chamber 13, there is provided temperature sensing means 15 and 16 which are capable of sensing the location of the stabilized cool flame front generated within the combustion chamber 13 'by the oxidation of the sample being introduced therein. The combustion chamber 13 is provided with inlet means 11 which introduces the mixture of air, and the combustible test sample into a burner nozzle, not shown, contained within the lower section of the combustion chamber 13. The net combustion products are ultimately discharged therefrom via line 17.

The mixture of air and combustible uid passing into the chamber 13 is thereupon spontaneously ignited due to the elevated temperature. The region of the combustion chamber 13 which is located between the inlet line 11 and the temperatureY sensing means 15 is known as the induction section. The induction section is defined as that portion of the combustion zone wherein oxidation of the combustible fluid is initiated. Therefore the induction section more particularly comprises that portion of the combustion chamber 13 located between the burner nozzle and the cool flame front which is generated by the combustion.

In a preferred embodiment of the present invention, the apparatus shown in the attached FIG. 1 is utilized to detect the octane number of a gasoline blend of unknown composition. The air and the gasoline blend sample pass into the combustion cham-ber 13 via line 11. The mixture of air and gasoline passes through the burner nozzle at the bottom of chamber 13, not shown, and enters the induction section of the combustion chamber. The temperature of the induction section is about 630 F. and is maintained thereat by the heated fluid medium which completely surrounds the combustion chamber in the elevated temperature zone 38. The oxygen and the gasoline react within the induction section producing an exothermic reaction resulting finally in a temperature elevation to a peak of about 750 F., whereat there is developed a cool flame front. At this point, the temperature of the combustion mixture falls off rapidly to about 640 F. When the cool flame front is stabilized, the temperature sensing means 15 and 16 will sense an identical temperature due to the fact that the combustion produces a peak temperature with a rapid tailing off of temperature. The exhaust gases from the combustion then leave the combustion chamber 13 via line 17.

With reference to the combustion parameter which is manipulated and adjusted in order to stabilize or immobilize the cool flame front between temperature sensing means 15 and 16, the preferred embodiment is to adjust the pressure within the combustion zone, as was previously mentioned hereinabove. In other words, an increase in pressure will cause the llame front to recede towards the burner end of com-bustion chamber and a decrease in pressure will cause the flame front to advance away from the 'burner end of the chamber and more closely approach the discharge end thereof. Therefore, if the flame front attempts to move toward the burner end of the chamber, the temperature sensing means 15 will reflect a temperature rise. Temperature sensing means 15 and 16 will transmit the sensed temperatures via transmitting means 18 and 19 to a differential temperature controller 20, which will then activate a pressure controller 22 by passing a pressure control signal thereto via line 21. The pressure controller will be activated in order to decrease combustion pressure until the flame front is restored to its original position between the axially spaced temperature sensing means 15 and 16. Conversely, if the hydrocarbon composition changes so that the flame front attempts to move away from the burner end of the chamber, tem-pera- `pressure until the front is restored to the original position.

Although the preferred embodiment of the invention comprises the manipulation of pressure as the controlled combustion parameter, other combustion conditions may be adjusted, with equally satisfactory results, in a manner sufficient to immobilize the flame front to a constant position within the combustion chamber. Thus, as disclosed in the cited U.S. Pat. 3,463,613 a combustion parameter which may be adjusted by the control signal 21 from the differential temperature controller 20 includes the hydrocarbon sample flow rate in line 9, the oxygen containing gas flow rate in line 10, and the induction zone temperature. In either case, regardless of which combustion condition parameter is manipulated, the apparatus operates with the selected combustion parameter being adjusted in a manner to immobilize the flame front relative to its position within the combustion chamber 13, regardless of changes in the test sample composition. Thus the combustion parameter is sensed and utilized to develop an output signal which is then indicative of the composition characteristic of the combustible fluid being analyzed, which in a preferred embodiment is the octane number of a blended gasoline sample.

The temperature sensing means for determining the location of the stabilized cool flame is preferably a thermalelectric means such as a pair of axially spaced thermocouples 15 and 16. However, other means for determining the flame position will be apparent to those skilled in the control arts and are deemed embraced in the broad scope of this invention. For example, one may employ spaced resistance bulbs or simply a pair of spaced resistance wires stretched tightly across the combustion zone, connected in a standard bridge circuit, instead of the previously described thermalelectric elements. Alternatively, optical-electric means, such as radiation pyrometers may be used. Since the ame front contains an appreciable concentration of organic radicals and ions, its position may also be detected by ion sensitive means such as a capacitor in the tank circuit of a high frequency oscillator whereby linear displacement of the flame will change the dielectric constant of the capacitor and hence, the resonance characteristic of the oscillator. Or the flame region may comprise a direct-current ionization gap. Those skilled in the art may readily determine the appropriate sensing means for determining the position of the stabilized cool flame in the combustion zone of the present invention.

In a preferred embodiment of the inventive apparatus, the cool ame front for the combustible fluid sample is positioned between a pair of thermocouples 15 and 16 placed in the combustion zone. Both thermocouples will be at about the same temperature and the voltage appearing at the input of the differential temperature controller 20 will be approximately zero. However, equally satisfactory operation con be achieved by having a net voltage difference if the positive or negative corresponding to a temperature differential is in the order of F. to 40 F. This means that the flame front in the combustion chamber 13 is then slightly asymmetrical with respect to the thermocouples 15 and 16. While this mode achieves greater sensitivity, it is not a critical requirement and one may'still get good results with the apparatus if a zero temperature differential is maintained within the device 20.

In any event, the sensing means 15 and 16, the transmitting means 18 and 19, and the differential temperature controller 20 will enable one to determine the exact position of the cool ame front by a differential temperature measurement. Controller 20 will then activate the pressure control means 22 in order to adjust the flame front to a position where there is, as previously mentioned, typically a zero temperature differential.

12 Therefore, the change in combustion pressure which is required to immobilize the flame front in its predetermined location,`is a correlatable function with the composition of the Vfuel which is being oxidized within the combustion chamber 13.

Accordingly, then, there is provided within the apparatus a pressure sensing means 23 which develops a continuous pressure signal transmitted via line 24 to a transducer 90. The transducer converts the pneumatic or mechanical pressure signal 24 into an electrical signal which may be a voltage signal or an amperage signal. The transducer 90 transmits a convertedparameter output signal via line 91 into a signal conditioning means 41, which in this embodiment comprises a' digital or an analog computer means. Computer means 41 contains an internal computer program by which the converted parameter signal 91 is continuously converted into a pair of output signals 78 and 80, which are functionally representative of and correlatable with the octanerating of the combustible sample of gasoline blend introduced into the system via line 9.

While the test sample is continuously oxidized within combustion chamber 13 to develop the converted parameter signal 91, a reference fuel of known composition characteristic having molecular constituents similar to that of the finished blend or test sample is simultaneously partially oxidized within combustion chamber 14. Referring again to FIG. 1, there is shown the reference fuel sample entering the apparatus via line 26. Simultaneously an oxidizer, such as compressed air, enters the apparatus via line 27. Preferably, the air or oxidizer of line 27 is derived from the same source that the air or oxidizerl of line 10 is derived from. In this manner then, combustion effects due to extraneous matter contained in the oxidizer or due to fluctuations in percentage of oxygen in the oxidizer, are automatically compensated for bycancelling out any combustion influences due to the oxidizer between the two combustion chambers 13 and 14.

The reference fuel and the air stream enter the combustion chamber 14 via line 25 and in a manner similar to that described for combustion chamber 13, the combustible reference fuelis partially oxidized therein in a mannervsufficient to generate a stabilized cool flame of the type described hereinabove. Temperature sensing means 29 and 30 are provided for location of the stabilized cool flame within the combustion chamber. The temperature signals are transmitted from

means

29 and 30 via transmittng means 31 and 32 to a differential temperature controller 33. Controller 33 transmits a differential temperature signal via line 34 to a pressure control means 35, or to any other suitable combustion parameter manip-l ulatlng means of the type hereinabove discussed.

The pressure controller 35 controls the pressure within the combustion chamber 14 by throttling the discharge of combustion products leaving the chamber 14 via line 28. The combustion pressure is sensed by a pressure sensing means 36 which develops a pressure signal transmitted via line 37 to a transducer 92. Transducer 92 converts the pneumatic or mechanical signal of line 37 into an electrical signal which is transmitted via line 93 to the signal conditioning means 41.

Signal conditioning means 41 receiving the converted parameter signal 93 compares signal 93 with an internally contained signal value which is representative of the composition characteristic of the reference fuel. By means of the internal computer program, any deviation of signal 93 from the known value of signal corresponding to the actual known value of composition characteristic for the 13 value of composition characteristic for the reference fuel. In this manner, then, the computer means 41 -generates condition output signals 78 and 80 which are indicative .of the composition characteristic of the finished blend test sample as corrected for deviations in the combustion of reference fuel which are sensed by the apparatus of the present invention.

, The condition output signal 78, typically, is thereupon transmitted to an octane display device 79 which may comprise a recording chart device, or a tape printout device, or any other type of indicating means. In addition, the octane display device 79 may comprise a control system whereby an output signal for control of octane number is transmitted to means 81, to be discussed hereafter, for controlling the octane rating of the blend which provides the test sample entering via line 19. However, in the embodiment of FIG. ll, control means 81 is adjusted by condition output signal 80.

As previously noted, the apparatus of the present invention is typically located out-of-doors. Accordingly, it is subject to combustion effects created by changes in atmospheric conditions. In order to compensate for changing atmospheric conditions, there is provided within the apparatus of the present invention a temperature sensing means 39 which is capable of sensing any uctuations in temperature within the elevated temperature zone 38. Temperature sensing means 39 passes a temperature output signal via transmitting means 40 to the signal conditioning means 41. The internal program of the computer means 41 thereupon makes a temperature correction to the condition output signals passing via

lines

78 and 80. Thus, the octane value thereafter indicated by octane display device 79 is continuously compensated for any error in the indicated composition characteristic which is due to temperature fluctuations caused by changes in atmospheric conditions.

In addition, the method and apparatus of the present invention provides for a continuous compensating adjustment to condition output signals 78 and 80 which reflects and compensates for uctuations in the relative proportion of the various component fluids which are entering the blending system to produce the finish blend, a test sample of which is passed into the apparatus via line 9.

' In order to make compensating adjustments to the condition output signals 78 and 80 which are reective of the varying proportions of components passing into the blending process, there is provided means for sensing the ow of each component fluid passing into the blending system. In order to sense the ow of reformate gasoline, there is provided in line 1 a flow sensngmeans such as an orifice 42 which transmits a ow signal via line 43 to a transducer 44. The differential pressure signal developed by the fluid passing through orifice 42 and transmitted via line 43, is converted by transducer 44 into an electrical signal which is passed via line 45 into the computer means 41. The ow of straight-run gasoline is sensed by a ow sensing means 48 which transmits a AP flow signal via line 49 to transducer 50, which thereafter passes an electrical flow signal via line 51 into computer means 41. VIn a similar manner, the rate of ow of alkylate gasoline into the blending process is sensed by orifice 54 which transmits a AP ow signal via means 55 to transducer 56, which in turn transmits an electrical flow signal to computer means 41 via line 57. Additionally, the cracked gasoline flow rate is sensed and transmitted by means 60, 61, '62, and 63 to deliver an electrical input signal of cracked gasoline flow to computer' means 41. The volatility component ow is similarly sensed and transmitted by

means

66, 67, 68, and 69 to deliver an electrical 'flow signal of volatility component to computer means 41. `Finally, the flow rate of lead alkyl entering the blending process is similarly sensed and transmitted by

means

72, 73, 74, and 75,'whereby an electrical flow signal is delivered to computer means 41.

fComputer means 41, now continuously receiving the rate of flow for each component entering the blending process, takes the information into the internal program of the computer, whereby the relative influence of each component upon the combustion within the combustion chamber 13 is determined. In this manner, the relative rate of ow of each component provides a direct measurement of the relative combustion effect of the aromatic component entering the process, the normal paratinic component entering the process, the naphthenic component entering the process, the isoparaiiinic component entering the process, the olenic component entering the process, the volatility component entering the process, and the anti-knock agent entering the process. Computer means 41 is able by means of the internal computer program, to make compensating adjustments to the resulting condition output signals 78 and 80 which reflect a correction to these output signals for the effects of the various components entering the gasoline blend.

Thus, condition output signals 78 and 80 are continuously compensated for combustion effects which are not indicative of the composition characteristic being determined, such as blend octane rating.

As noted hereinabove, the signal conditioning means 41 delivers a condition output signal via transmitting means 80 to a controlling means, which for illustrative purposes is shown as a valve means 81 located in line 6. In this manner, then, the computer means 41 will adjust the input flow of one or more components entering the blending process, whereby the condition output signal generated by the analytical apparatus of the present iuvention is utilized to control the blending system in a manner sufficient to produce a constant value of composition characteristic for the final finished blend product. As noted hereinabove, in the preferred embodiment of the present invention, the blending process wherein the apparatus of the present invention is utilized is a gasoline blending process. Accordingly, therefore, it is preferable that the condition output signal 80 and the control means 81 be utilized to control the input of at least one high octane blending component such as the reformate gasoline entering the blending system via line 1, or to control the input of an anti-knock agent such as the lead alkyl entering the system via line 6. Alternatively, the input of a low octane component such as the straight-run gasoline could be controlled. In this manner then, the apparatus and controlsystem will produce a controlled iinished gasoline blend which has a constant octane rating in accordance with the specification which is set for the given blend which is being produced and analyzed.

Referring now to FIG. 2, there is shown a second ernbodiment of the present invention wherein the signal conditioning means of FIG. l, the computer means 41 and its internally contained program, is replaced by a signal conditioning means preferably comprising a network of analog elements, although a network of digital elements may be used. The basic elements of the analytical apparatus and the blending system which are disclosed' in FIG. l are again illustrated in FIG. 2.

In the embodiment of FIG. 2, however, the parameter output signal 24 and the parameter output signal 37 are passed to a transducer 83 which is, in fact, a differential pressure transducer. Transducer 83 converts the differential pressure sensed between the test sample parameter signal and the reference fuel parameter signal into a net electrical signal representative of the difference between vthe two pressure signals 24 and 37. This pressure difference as transmitted via means 84, has a direct correlation to the difference of the test sample composition characteristic from the known value of composition characteristic of the reference fuel.

The resulting differential pressure signal 84 is transmitted to a signal conditioning network 85. The signal conditioning network 85 is a type of apparatus which iS resulting electrical output signal which is representative of the composition characteristic being analyzed and which is passed to the signal conditioning network. The conditioning network 85 either multiplies, or it adds and subtracts to the received transducer signal 84 in order to produce a net output signal which is correlatable with the octane rating or other composition characteristic being determined for the test sample. In the preferred embodiment, signal conditioning network 85 will add and subtract to the differential pressure signal 84. The resulting pressure output signal, which is novvfunctionally representative of the composition characteristi: of thetest sample, is transmitted from signal conditioning network 85 via transmitting means 86 into a summingmeans 87.

4In addition, in the embodiment illustrated in FIG. `2, the temperature signal which is sensed in the elevated temperature zone 38 by the sensing means '39, is transmitted via line 40 into a signal conditioning network 88. Again, the signal conditioning network 88 is a type of network is well known in the art. The temperature signal has a fixed correlation 4between the temperature in the elevated temperature zone 38 and the octane rating or other composition characteristic being determined within the combustion chambers of the analytical device of the present invention. The conditioning network 88 therefore, adds or substracts to the signal 40 in a manner suicient to compensate for any temperature deviations from a fixed temperature which is the standard base temperature for the elevated temperature zone 38. The resulting signal is passed from the signal conditioning network 88, with a compensation for any temperature deviation, into summing means 87 via transmitting means 89.

Furthermore, in the embodiment of FIG. 2, the converted flow signal 45 which is representative of the flow of reformate gasoline passing into the blending process is transmitted to a signal conditioning network 46. Again the signal conditioning network 46 is a type of network which is well known in the art. There is a fixed correlation between the actual flow of the reformate gasoline and the resulting octane contribution to the final blended gasoline product octane number. Consequently,'the signal conditioning network 46 develops a continuous octane correction factor for the flow of aromatic iiuid passing through the orifice 4Z. The aromatic or reformate octane correction factor is passed via transmitting means 47 to the summing means 87.

In a similar manner, there is a provision for passing the converted flow signal 51, which is representative of the flow of straight-run gasoline, into the blending process to a signal conditioning network 52. This signal conditioning network is similar to that of netwonk 46. There is a fixed correlation between the actual dow of the straight-run gasoline and the resulting octane contribution of the straight-run gasoline to the final blended gasoline product octane number. Consequently, signal conditioning network 52 develops a continuous octane correction factor for the flow of this normal paraffinic fiuid passing through the orifice 48. 'Ihis normal paranic or straight-run gasoline octane correction factor is transmitted vvia means 53 to the summing means 87.

-In a similar manner, the alkylate gasoline component fiow signal 57 is passed to a signal conditioning network 58 which develops an octane correction factor for the isoparaflinic component passing to the'gasoline blend. The octane correction factor is passed from signal conditioning means 58 via transmitting means 59 to the .summing means 87.

A correction to the octane contribution of the cracked gasoline is also provided for in the apparatus as set forth in IFIG. 2. Flow signal 63 passes into a signal conditioning network which thereafter transmits an octane cor- 16 rection factor for the olefinic component via transmitting means 65 into the summing means 87; Similarly, a correction for the octane contribution of the volatility component is provided by sending the flow signal 69 to afsignal conditioning network 70 which thereupon'develops an octane correctionv factor signal passing via means 71 to the summing means 87. Finally there is indicated in FIG." 2,

an octane correction for the lead alkyl component passing into the blending process. This 'is provided by sending the anti-knock agent :liow signal 75 into the signal conditioning network 76 which in turn develops an octane correction factor transmitted via means 77 to the summing n means 87.

Summing means 87 receiving the temperature signal 89, the differential pressure signal 86, and the component octane correction factor signals 47, 53, 59, 65, 71,v and 77, thereupon algebraically sums the signals. The net result of the algebraic summation accomplished bysumming means 87l is a modified differential parameter signal which is in fact the net condition output signal which is indicative of the Vactual composition characteristic as compensatedfor any component and temperature liuctuations. Thus when the test sample of line 9 is oxidized in combustion chamber 1G', the summing means 87 sends a condition' output signal 78 to the octane displaydevice 79 which gives the correct octane rating of the testsample of the finished blended gasoline product.

In the embodiment illustrated in FIG. 2, the octane display device 79 contains a control system which not only gives an indication of the actual octane of the test sample but which also develops a control output signal 82 passing to the control valve 81. The control set point contained Within means 79 is set to the desired specification composition characteristic, in this instance the octane rating of the finished blend, and the control output 82 thereupon throttles the valve 81 to admit a sufficient amount lof antiknock agent (lead alkyl) to control the octane rating of the finished blend to the specification set point. Of course, as noted hereinabove, the control outputsignal 82 could alternatively be utilized to control the input of a high octane blending component such as the reformate gasoline in order to control the octane rating of the finished blend to the set point value. Similarly, signal 82 could be utilized to controll the input of a low octane blending component such as the straight run gasoline.

PREFERRED EMBODIMENTS contains an internal computer program for making compensating adjustments to producethe corrected condition output signal. Referring to FIG. 2, the signal conditioning means comprises the network of elements which is, in fact, a computing system for making the compensating adjustments, T hus, the signal conditioning`

networks

85, 88, 46, 52, 58, 64, 70, and V76whicl1 are disclosed in FIG. 2, are individual elements contained within the signal conditioningV means of that embodiment. ,y

Furthermore, it is to `be noted thatfthe composition characteristic 'being determined by thepresent invention, typically octane rating, is indicated by a' `condition output signal which is a function of and correlatable with the composition characteristic being determined. However, those skilled in the art will realize that the condition output signal, as illustrated by the

elements

78, 80, and

17 82, is in fact a modified parameter output signal which in the preferred embodiment is a pressure signal, and more particularly, a differential pressure signal.

Therefore, from the above description it may now be summarized that one preferred embodiment of the present invention provides a method for controlling the composition characteristic of a combustible fluid mixture produced by continuously blending a plurality of component fluids, which comprises: (a) introducing a sample stream of said uid mixture and a stream of oxygen-containing gas into a first end of a first combustion chamber containing a first induction section maintained at elevated temperature; (b) simultaneously introducing a stream of reference fuel having a known composition characteristic, and a stream of oxygen-containing gas into a second end of a second combustion chamber containing a second induction section maintained at elevated temperature; (c) partially oxidizing said sample stream in said first combustion zone under conditions sufficient to generate and maintain therein, a first cool flame characterized by a relatively narrow well-defined flame front spaced from said first end; (d) partially oxidizing said stream of reference fuel in said second combustion zone under conditions suilicient to generate and maintain therein a second cool flame characterized by a relatively narrow well-defined flame front spaced from said second end; (e) sensing the position of said first flame front relative to said first end, and developing therefrom a first control signal; (f) sensing the position of said second flame front relative to said second end, and developing therefrom a second control signal; (g) utilizing said first control signal to adjust a combustion parameter selected from the group consisting of combustion zone pressure, induction section temperature, sample stream flow rate, and oxygen-containing gas stream flow rate, in a manner sufiicient to immobilize said `first flame front relative to said first end regardless f fluctuations in the composition characteristic of said sample stream; (h) utilizing said second control signal to adjust a combustion parameter selected from the group consisting of combustion zone pressure, induction section ternperature, reference fuel flow rate, and oxygen-containing gas stream flow rate, in a manner sufficient to immobilize said second flame front relative to said second end regardless of fluctuations in the combustion of said reference fuel; (i) sensing the adjusted parameter of said first combustion chamber and developing therefrom a first parameter signal responsive to changes in said composition characteristic of said sample stream; (j) sensing the adjusted parameter of said second combustion chamber and developing therefrom a second parameter signal functionally representative of the known composition characteristic of said reference fuel; (k) developing a component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible fluid mixture; (l) passing said first parameter signal, said second parameter signal, and said component signal into signal conditioning means, and producing therefrom a condition output signal compensated for sample stream combustion effects not indicative of composition characteristic; and, (m) passing said condition output signal to means controlling the relative amount of a second component uid being blended in said plurality to produce said combustible fluid mixture, whereby the composition characteristic of said combustible uid mixture iS controlled to a predetermined value responsive to the combustion of said sample stream.

Furthermore, in its apparatus aspects, a preferred embodiment of the present invention resides in a blending process wherein a plurality of component fluids is continuously introduced into a blending zone producing a resulting combustible fluid mixture, each component fluid having associated therewith conduit means passing the associated fluid into said blending zone, a control system for maintaining a composition characteristic of said combustible fluid mixture at a predetermined level, which comprises in combination: (a) a first combustion chamber containing a first induction section; (b) a second combustion chamber containing a second induction section; (c) means for generating within said first combustion chamber, a cool flame characterized by a relatively narrow well-defined flame front, utilizing as fuel therefor said combustible fluid mixture to be analyzed, said generating means including means passing a stream of said fluid mixture and a stream of oxidizer into said first combustion chamber; (d) means for generating within said second combustion chamber, a cool flame characterized by a relatively narrow well-defined flame front, utilizing as fuel therefor a reference fuel having a known value of composition characteristic, said generating means including means passing a stream of said reference fuel and a stream of oxidizer into said second combustion chamber; (e) first position sensing means sensing the physical position of said flame front within said first combustion chamber; (f) second position sensing means sensing the physical position of said flame front within said second combustion chamber; (g) first control means coupled to said first position sensing means, and adapted to adjust a combustion parameter selected from the group consisting of combustion pressure, induction section temperature, fluid stream flow rate, and oxidizer flow rate, -in a manner sufficient to immobilize said first llame front in a constant position relative to said first combustion chamber; (h) second control means coupled to said second position sensing means, and adapted to adjust a combustion parameter selected from the group consisting of combustion pressure, induction section temperature, reference fuel stream flow rate, and oxidizer flow rate, in a manner sufficient to immobilize said second flame front in a constant position relative to said second combustion chamber; (i) means sensing the adjusted parameter of said first combustion chamber and developing a first parameter signal functionally representative of the composition characteristic of said fluid stream; (j) means sensing the adjusted parameter of said second combustion chamber and developing a second parameter signal functionally representative of the known composition characteristic of said reference fuel; (k) means developing a component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible fluid mixture; (l) signal conditioning means receiving said first parameter signal, said second parameter signal, and said component signal, and producing therefrom a condition output signal functionally representative of and correlatable with the composition characteristic of said fluid mixture; (m) means controlling the relative amount of a second component fluid of said plurality contained in said combustible uid mixture; and, (n) means transmitting to said control means (c), said condition output signal,V whereby said resulting combustible fluid mixture is controlled at a constant predetermined level of combustion characteristic.

The invention claimed:

1. In a method for detecting composition characteristic of a combustible uid mixture produced by combining a plurality of component fluids and including the steps of (a) introducing a sample stream of said fluid mixture and a stream of oxygen-containing gas into one end of a combustion zone including an induction section maintained at elevated temperature;

(b) partially oxidizing said sample stream in said combustion zone under conditions sufllcient to generate and maintain therein, a cool llame characterized by Ya relatively narrow well-defined flame front spaced from said one end;

(c) sensing the position of llame front relative to said one end, and developing therefrom a control signal;

(d) utilizing said control signal to adjust a combustion parameter selected from the group consisting of combustion zone pressure, induction section temperature, sample stream flow rate, and oxygen-containing 19 7gas stream ow rate, in a manner suicient to immobilizev said llame front relative to said one end regardless of fluctuations in the composition characteristic of said sample stream; -f(e)-sensing the adjusted parameter land developing a parameter signal responsive to changes in said composition characteristic; (f) developing a component signal representative of "1 the relative amount of a first component iluid of said plurality .contained in said combustible uid mixture; and, f (.g) thereafterutilizing said parameter signal and said vr component signal to obtain a condition voutput signal functionally representative of the composition characteristic of said sample stream of fluid mixture, said condtion output signal being indicative of said composition characteristic as corrected for deviationsin said lparameter signal caused by the relative amount of said first component fluid -in said combustible fluid mixture; t v

the'improvement which comprises:

,j (h) simultaneously with step (a) above introducing a stream of reference fuel having arknown composition characteristic, and a stream of oxygen-containing gas into one end of a second combustion zone containing a secod induction section maintained at elevated (i) lpartially oxidizing said stream of referenceffuel in said second combustion zone under conditions sufcient to generate and maintain therein a second cool llame characterized by a relatively narrow well-deiined flame front spaced from said end thereof;

(j) sensing the position of said second llame front relative to said end of said second zone and developing therefrom a second control signal;

' (k) utilizing said second control signal to adjust a combustion parameter selected from the group consisting of combustion zone pressure, induction section temperature, reference fuel llow rate, land oxy-V gen-containing gas stream flow rate, in a manner sufficient to immobilize said flame front in said one endof said second zone regardless of fluctuations in the combustion of said reference fuel;

(l) sensing the adjusted parameter of said second combustion zone and developing therefrom a second parameter signal functionally representative of the known composition characteristic of said, reference fuel;

(m) passing thepaarmeter signal developed in step i (e), the second parameter signal, and the component signal into signal conditioning means, and producing therefrom a condition output signal compensated -for sample stream combustion effects not indicative of composition characteristic, whereby said condition output signal is functionally representative of the composition characteristic of said combustible fluid mixture.

'-2. Method of claim 1 wherein said combustion chambers are commonly coninedin an elevated temperature zone, a temperature of said elevated temperature zone is sensed and a temperature signal is developed therefrom, and said temperature signal is passed to said lsignal conditioning means, whereby said condition outputsignal is rendered representative of composition characteristic as corrected for temperature deviations. f

v'3. Method of claim 1 wherein said combustiblev uid mixture comprises gasoline boiling range hydrocarbons and said composition characteristic is octane rating. p

4. In a method for controlling the composition characteristic of a combustible liuid mixture produced vby continuouslyblending a plurality of component lluids and including the steps of: s

(a) introducing a sample stream of said iiuid mixture CFI and a stream of oxygen-containing gas into one end of a combustion zone including an induction section maintained at elevated temperature;

(b) partially oxidizing said sample stream in said combustion zone under conditions sufficient to `generate and maintain therein, a cool ilame characterized-by a relatively narrow well-defined ame front spaced from said one end;

(c) sensing the position of said flame front relative to said one end, and developing therefrom a control signal; v Q l -(d) utilizing said control signal to adjust a combustio parameter selected from the group consisting of combustion zone pressure, induction section temperature, sample stream flow rate, and oxygen-containing gas stream liow rate, in a mannersufcient to immobilize said llame front relative to said one end regardless of fluctuations in the composition characteristic of said sample stream; A.

(e) sensing the adjusted parameter and developing a first parameter signal responsive to changes in csaid composition characteristic;

(f) developing a component signal representative o the relative amount of a first component fluid being blended in said plurality to produce said combustible fluid mixture; and, t

(g) thereafter utilizing said rst parameter signal yand said component signal to control the relative amount of a second component fluid being blended in said plurality to produce saidy combustible fluid mixture;

the improvement which comprises:

(h) simultaneously with step (a) above introducing a stream of reference fuel having a known composition characteristic and a stream of oxygen-containing gas into one end of a second combustion zone containing a second induction section maintained at elevated temperature;

(i) partially oxidizing said stream of reference fuelin said second combustion zone under conditions'suiicient to generate and maintain therein a second cool flame characterizedv by a relatively narrow well-deiined flame front spaced from said end thereof;

(j) sensing the position of said second flame front re1- ative to such end, and developing therefrom `a second control signal;

(k) utilizing said second control signal toi adjust a combustion parameter selected-from th'e group consisting of combustion zone pressure, induction section temperature, reference fuel ow rate, and oxygencontaining gas stream ow rate, in a mannerv suicient to immobilize said second flame "front relativer to said end of said second combustion zone regardless of fluctuations in the combustion of said reference fuel; (l), sensing the adjusted parameter of said second combustion zone and developingA therefrom a second parameter signal functionally representativefof the known composition characteristic of said reference fuel;

(m) passing the parameter signal developed in' step l (a), the second parameter signal, andthe component signal into signal conditioning means and producing ytherefrom a condition output signal compensated for sample. stream combustion effects not indicative of composition characteristic; and, Y j H (n) passing said condition output signal to means, conxtrolling Athe relative amount of second component fluid being blended in said plurality to produce `said combustible uidtmixture, whereby the composition characteristic of said combustible fluid mixture vis controlled to a predetermined value responsive to the combustion of said sample stream,'

5; Method of claim 4 wherein said second component uid'is said iirst component fluid. f y

21 6. Method of claim 4 wherein said combustible fluid mixture comprises gasoline boiling range hydrocarbons and said composition characteristic is octane rating.

7. Method of claim 6 wherein said second component iluid comprises an anti-knock agent.

8. Method of claim 4 wherein said combustion chambers are commonly confined in an elevated temperature zone, a temperature of said elevated temperature zone is sensed and a temperature signal is developed therefrom, and said temperature signal is' passed to said signal conditioning means, whereby said condition output signal is rendered representative of composition characteristic as corrected for temperature deviations.

9. In a composition analyzer for detecting a composition characteristic of a combustible fluid mixture produced by combining a plurality of component fluids, and which includes: l

(a) a combustion chamber, including an induction section;

(b) means for generating within said combustion chamber, a cool llame characterized by a relatively narrow well-defined flame front, utilizing as fuel therefor said combustible fluid mixture to be analyzed, said generating means including means passing a stream of said fluid mixture and a stream of oxidizer into said combustion chamber;

(c) means sensing the physical position of said llame front within said combustion chamber;

(d) control means coupled to said position sensing means, and adapted to adjust a combustion parameter selected from the group consisting of combustion pressure, induction section temperature, uid stream ow rate, and oxidizer stream flow rate in a manner sucient to immobilize said arne front in a constant physical position relative to said combustion chamber;

(e) means sensing the adjusted parameter and developing a parameter output signal which is functionally representative of the composition characteristic of said uid stream; and,

(f) means developing a component signal representative of the relative amount of a first component iluid of said plurality contained in said combustible lluid mixture, said parameter output signal and said component signal, thereafter being utilized to derive a condition output signal,

the improvement which comprises in combination therewith:

(g) a second combustion chamber containing a second induction section;

(h) means for generating within said second combustion chamber, a cool ame characterized by a relatively narrow Well-deiined flame front, utilizing as fuel therefor a reference fuel having a known value of composition characteristic, said generating means including means passing a stream of said reference fuel and a stream of oxidizer into said second combustion chamber;

(i) second position sensing means sensing the physical position of said ilame front within said second combustion chamber;

(j) second control means coupled to said second position sensing means, and adapted to adjust a combustion parameter selected from the group consisting of combustion pressure, induction section temperature, reference fuel stream ilow rate, and oxidizer ow rate, in a manner sull'icient to immobilize said second llame front in a constant position relative to said second combustion chamber;

(k) means sensing the adjusted parameter of said second combustion chamber and developing a second parameter signal functionally representative of the known composition characteristic of said reference fuel;

(l) signal conditioning means receiving the parameter signal developed in step (e), the second parameter signal, and the component signal, and producing therefrom a condition output signal functionally representative of and correlatable with the composition characteristic of said lluid mixture.

10. Apparatus of claim 9 wherein there is provided an outer chamber confining said combustion chambers in an elevated temperature zone, means sensing a temperature in said elevated temperature zone and developing a temperature signal, and means transmitting said temperature signal to said signal conditioning means, whereby said condition output signal is rendered functionally representative of composition characteristic as corrected for temperature deviations.

11. Apparatus of claim 9 wherein said signal conditioning means comprises computer means.

12. Apparatus of claim 9 wherein there is provided means transmitting to said signal conditioning means, a plurality of component signals, each component signal being functionally representative of the relative amount of a. component fluid of said plurality of contained in said combustible uid mixture.

13. In a blending system wherein a plurality of component fluids are continuously introduced into a blending zone producing a resulting combustible fluid mixture, each component iluid has in association therewith conduit means passing the associated tluid into said blending zone, and a control system is utilized therein for maintaining a composition characteristic of said combustible fluid mixture at a predetermined level, which includes:

(a) a combustion chamber, including an induction section;

(b) means for generating within said combustion chamber a cool llame characterized yby a relatively narrow well-defined llame front, utilizing as fuel therefor said combustible lluid mixture to be analyzed, said generating means including means passing a stream of said fluid mixture and a stream of oxidizer into said combustion chamber;

(c) means sensing the physical position of said flame front Within said combustion chamber;

(d) control means coupled to said position sensing means, and adapted to adjust a combustion parameter selected from the group consisting of combustion pressure, induction section temperature, iluid stream flow rate, and oxidizer stream ilow rate in a manner suflicient to immobilize said flame front in a constant physical position relative to said combustion chamber;

(e) means sensing the adjusted parameter and developing a parameter output signal which is functionally representative of-the composition characteristic of said fluid stream; and,

(f) means developing a component signal representative of the relative amount of a iirst component iluid of said plurality contained in said combustible iluid mixture, whereby said parameter signal and a component signal can thereafter be utilized to derive a condition output signal wherein the improvement which comprises in combination with said control system:

(g) a second combustion chamber containing a second induction section;

(h) means for generating within said second combustion chamber, a cool llame characterized by a relatively narrow well-defined llame front, utilizing as fuel therefor a reference fuel having a known value of composition characteristic, said generating means including means passing a stream of said reference fuel and a stream of oxidizer into said second combustion chamber;

(i) second position sensing means sensing the physical position of said llame front within said second combustion chamber;

(j) second control means coupled to said second position sensing means, and adapted to adjust a combustion parameter selected from the group consisting of combustion pressure, induction section temperature, reference fuel stream ow rate, and oxidizer ow rate, in a manner sutlicient to immobilize said sec ond flame front in a constant position relative to said secondv combustion chamber;

, (k) means sensing the adjusted parameter of said second combustion chamber and developing a second parameter signal functionally representative of the lknown composition characteristic of said reference fuel;

(l) `signal conditioning means receiving the parameter signal developing in step (e), the second parameter signal, and the component signal, Y, and producing therefrom a condition output signal functionally representative of and correlatable with the composition characteristic of said uid mixture;

v (m) means controlling the relative amount of a V second component fluid of said plurality containedin said combustible uid mixture; and,

(n) means transmitting said condition voutput signal to said second control means, Iwhereby said resulting combustible fluid mixture is controlled at a constant predetermined level of combustion characteristic.

14. System of claim 13 wherein there is provided an outer chamber confining said combustion chambers in' an elevated temperature zone, means sensing a temperature in said elevated temperature zone and developing a temperature signal, and means transmitting said temperature signal to said signal conditioning means, whereby said condition output signal is rendered functionally representative of composition characteristic as corrected for temperature deviations.

1S. System of claim 13 wherein said signal conditioning means comprises computer means.

24 16. System of claim 13 wherein said means (k) comprises means sensing the` flow. of Aiirstcomponent fluid passing to said blending zone inthe associated rst conduit means. v

17. System of claim 13 wherein said means `(m) comprisesy meansrcontrolling the Aow ofsecondl component fluid passing to said blendingzone inthe associated second conduit means. 18. System of. claim 13 wherein said` second-component luid is said first component uid,.said.means (k) comprises means sensing the iioW-.of first component fluid passingto said blending zone in the associated first conduit means, and said means (m) comprises means con: trolling. the ow of said `iirst component fluid passing through said associatediirst conduit means.

2 19. System of claim 13 wherein there is provided means transmitting to said signal conditioning means, a plurality of component signals, eachcomponent ,signal being functionally representative of the relative amount of a component Huid of said plurality contained in said combustible-duid mixture. .f i

* References ,Citedl K Y UNITEDA STATES PATENTS 3,533,746 10/1970 -Fenske 237-230 A 3,582,280 6/1971 Fenske 23-254 E `3,582,281 6/1971 Penske v v' 23-254 E MORRIS O. WOLK, Primary Examiner R. E. 4SERWIN, Assistant Examiner Us. C1. Xn.

23-232 R, 253 PC. 254 'RZ 721-345; 208-17.. 431-75