US3582281A - Determination and control of a composition characteristic while blending a multicomponent combustible fluid - Google Patents

Abstract

IN 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 IS OXIDIZED IN AN ANALYZER COMPRISING A STABILIZED COOL FLAME GENERATOR WITH A SERVOPOSITIONED FLAME FRONT. THE POSITION OF THE FLAME FRONT IS AUTOMATICALLY DETECTED AND UTILIZED TO MANIPULATE A COMBUSTION PARAMETER IN A MANNER SUFFICIENT TO IMMOBILIZE THE FLAME FRONT REGARDLESS OF FLUCTUATIONS IN COMPOSITION CHARACTERISTIC OF THE FLUID SAMPLE. CHANGES IN COMBUSTION PARAMETER WHICH ARE REQUIRED TO IMMOBILIZE THE FLAME FRONT ARE CORRELATABLE WITH CHANGES IN COMPOSITION CHARACTERISTIC, AND MEANS IS PROVIDED FOR SENSING THE MANIPULATED COMBUSTION PARAMETER AND DEVELOPING THEREFROM A CONDITION OUTPUT SIGNAL WHICH IS FUNCTIONALLY REPRESENTATIVE OF AND CORRELATABLE WITH COMPOSITION CHARACTERISTIC. A SUITABLE REFERENCE FUEL OF KNOWN COMPOSITION CHARACTERISTIC IS PERIODICALLY PASSED TO THE ANALYZER IN PLACE OF THE FLUID SAMPLE, AND MEANS IS PROVIDED TO COMPENSATE THE CONDITION OUTPUT SIGNAL FOR ANY DEVIATION IN THE SIGNAL BETWEEN APPARENT REFERENCE FUEL SIGNAL AND A SIGNAL CORRESPONDING TO THE TRUE KNOWN VALUE OF REFERENCE FUEL COMPOSITION CHARACTERISTIC. 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.

D R A W I N G

Description

June l, 1971 E R. FENsKE ETAL y 3,582,281

' DETERMINATION AND CONTROL OF A COMPOSITION CHARACTERISTIC WHILE BLENDING 'A MULTI-COMPONENT COMBUSTIBLE FLUID Filed may 15, 1970 2 Sheets-Sheet 1 EMMA,

TTR/VEYS June 1., 1971 E, R, FENSKE ETAL 3,582,281

DETERMINATION AND CONTROL OF A COMPOSITION CHARACTERISTIC WHILE BLENDING A MULTI-COMPONENT COMBUSTIBLE FLUID Filed May 15, 1970 2 Sheets-Sheet I E//sworfh R. Fens/ra Robert W. Sampson A TTOR/VE YS United States Patent O 3,582,281 DETERMINATION AND CONTROL OF A COMPO- SITION CHARACTERISTIC WHILE BLENDING A MULTICOMPONENT 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. 37,640 Int. Cl. F23m 5 00; G01n 25/46, 33/32 U.S. Cl. 23-230 24 Claims ABSTRACT OF THE DISCLOSURE In a blending process wherein a plurality of component fluids is continuously introduced into a blendingzone 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 is oxidized in an analyzer comprising a stabilized cool flame generator With a servopositioned flame front. The position of the flame front is automatically detected and utilized to manipulate a combustion parameter in a manner sufllcient to immobilize the flame front regardless of fluctuations in composition characteristic of the fluid sample. Changes in combustion parameter which are required to immobilize the flame front are correlatable with changes in-composition characteristic, and means is provided for sensing the manipulated combustion parameter and developing therefrom a condition output signal which is functionally representative of and correlatable with composition characteristic. A suitable reference fuel of known composition characteristic is periodically passed to the analyzer in place of the fluid sample, and means is provided to compensate the condition output signal for any deviation in the signal between apparent reference fuel signal and a signal corresponding to the true known value of reference fuel composition characteristic. 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 com-bustion 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 improvement in the method and apparatus for determining a composition characteristic of a combustible fluid mixture utilizing a stabilized cool flame 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 lgasoline blend produced from a plurality of blending components, and for controlling the blending operation to produce a gasoline product of constant octane rating.

Those skilled in the art are familiar with the phenomenon of cool flame generation. Briefly, 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 oxida- 3,582,281 Patented June 1 1971 tion 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 of 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 sufficient to immobilize the cool llame 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 fluid 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 flames is contained in U.S. Pat. 3,463,613, issued on Aug. 26, 1969, to E. R. Penske and I. 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 and apparatus disclosed in U.S. Pat. 3,463,612, is concerned with calibration of the apparatus to compensate for cornbustion 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 fluid for a substantial length of time, the apparatus ocassionally 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 diflusor element which is mounted in the interior of the combustion chamber a short Idistance above the combustion nozzle. Additionally, it has been found that where a leaded gasoline is the cornbustible fluid 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 fluctuations in the oxidizer passing into the combustion chamber will introduce combustion effects which will result in a 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 ue 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 of 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 ue gas.

Furthermore, it is typical in the art to place the com bustion 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-door and is subject to thermal uctuations due to atmospheric conditions. These fluctuations in atmosperic conditions produce thermal effects within the combustion chamber which are not indicative of the composition characteristic of the fluid being analyzed therein.

Additionally, it is known that the specic 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 flame. For example, where the uid being analyzed comprises a hydrocarbon mixture, the correlation between the condition output signal and the composition characteristic will be a function of the hydrocarbon fluid composition and the carbon number of the hydrocarbon constituents present therein. Furthermore, the correlation is further influenced by the presence or absence of parafns, isoparains, olefins, diolens, polyoleiins, 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 fluids are blended together in varying proportions to produce fluid mixtures of varying composition characteristics, wide fluctuation 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 resulting 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 antiknock 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 sufficient 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 isoparafnic `gasoline, such as motor alkylate, and at other periods it may contain none. Furtheromer, 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 specication, and composition effects from blend to blend may introduce deviations in the condition 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 cornponent distribution of molecular species within the blend sampling being burned to produce the stabilized cool flame.

SUMMARY OF THE INVENTION in a stabilized cool flame generator with a servo-posif tioned 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 iluid mixture produced by blending a plurality of component fluids, and for controlling the blending process to produce the mixture at 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.

Therefore in its method aspects, a broad embodiment of the present invention provides a method for detecting a composition characteristic of a combustible uid mixture produced by combining a plurality of component uids which comprises: (a) introducing a sample stream of said uid 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 sufcient to generate and maintain therein, a cool flame characterized by a relatively narrow Well-defined flame 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; (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 gas stream flow rate, in a manner sufficient to immobilize said flame front relative to' said one end regardless of uctuations in the composition characteristic of said sample stream; (e) sensing the adjusted parameter and developing a parameter signal responsive to changes in said composition characteristic; (f) developing a component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible uid mixture; and, (g) passing said parameter signal and said component signal into signal conditioning means, and producing therefrom a condition output signal functionally representative of the composition characteristic of said sample stream of fluid mixture, said condition output signal being indicative of said composition characteristic as corrected for deviations in said parameter signal caused by the relative amount of said first component fluid in said combustible fluid mixture.

Furthermore, in its method aspects, an additional 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 lluids which comprises: (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 sufficient to generate and maintain therein, a cool llame characterized by a relatively narrow well-defined ame front spaced from said one end; (c) sensing the position of said ame 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 gas stream flow rate, in a manner sullicient to immobilize said flame front relative to said one end regardless of fluctuations in the composition characteristic of said sample stream; (e) sensing the adjusted parameter and developing a first parameter signal responsive to changes in said composition characteristic; (f) developing a first component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible fluid mixture; (g) passing said first parameter signal and said first component signal into signal conditioning means, and producing therefrom a first condition output signal functionally representative of the composition characteristic of said sample stream of fluid mixture, said condition output signal being indicative of said composition characteristic as corrected for deviations in said parameter signal caused by the relative amount of said first component fluid in said combustible fluid mixture; (h) periodically isolating said sample stream from said combustion zone, and simultaneously passing a stream of reference fuel having a known value of composition characteristic, into said zone in a manner sufficient to continue the generation of said immobilized flame front, (i) sensing the adjusted parameter during the period of isolation and passing a second parameter signal into said signal conditioning means, said second parameter signal being functionally representative of the apparent composition characteristic of said reference fuel; (fj) comparing said second parameter signal with a reference value of parameter signal functionally corresponding to the actual known value of composition characteristic of said reference fuel; (k) adjusting said signal conditioning means in a manner suilicient to produce a second condition output signal which is compensated to reflect the elimination of the difference between 'said second parameter signal and said reference value parameter signal, and which is thereby functionally representative of the actual known composition characteristic of said reference fuel; and, (l) periodically isolating said reference fuel stream from said combustion zone while retaining the signal conditioning adjustment of step (k), and simultaneously passing said fluid sample stream into said zone in a manner sufficient to maintain said flame front, whereby said signal conditioning means receives a third parameter signal and a second component signal representative of the relative amount of said first component fluid, and said signal conditioning means therefrom develops a third condition output signal compensated for combustion effects not indicative of composition characteristic, and said third condition output signal is thereby functionally representative of the actual composition characteristic of said sample stream.

In addition, in its apparatus aspects, a broad embodiment of the present invention provides a composition analyzer for detecting a composition characteristic of a combustible fluid mixture produced by combining a plurality of component fluids, which comprises in combination: (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 cornbustion 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 temperatrue, fluid stream flow rate, and oxidizer stream flow 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 functio-nally representative of the composition characteristic of said fluid stream; (f) means developing a component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible fluid mixture; and, (g) signal conditioning means receiving said parameter output signal and said component signal, and producing therefrom a condition output signal which is functionally representative of and correlatable with said composition characteristic of the combustible fluid mixture, said condition output signal being indicative of said composition characteristic as corrected for deviations in said parameter signal caused by the relative amount of said first component fluid in said combustible fluid mixture.

Still further, in its apparatus aspects, a broad embodiment of the present invention provides a composition analyzer for detecting a composition characteristic of a combustible fluid mixture produced by combining a plurality of component fluids which comprises in combination: (a) a combustion chamber, including an induction section; (b) means for generating within said combustion chamber, a cool flame characterized by `a relatively narrow well-defined llame 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 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, fluid stream flow rate, and oxidizer stream flow rate in a manner sufficient 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; (f) means developing a component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible fluid mixture; (g) signal conditioning means receiving said parameter output signal and said component signal; (h) condition signal generating means Within said signal conditioning means producing a condition output signal functionally representative of said composition characteristic; (i) means periodically isolating said fluid stream from said flame generating means, and simultaneously passing a stream of reference fuel having a known value of composition characteristic, into said flame generating means in a manner suflicient to continue the generation of said immobilized flame front; (j) means passing to said signal conditioning means, a timing signal indicative of the passage of reference fuel to said flame generating means; (k) comparison means within said signal conditioning means, responsive to said timing signal, adapted to compare the condition output signal generated due to reference fuel flame front with a reference value signal functionally corresponding to the actual known value of composition characteristic of said reference fuel, and therefrom developing a comparison signal; (l) adjusting means within said signal conditioning means, responsive to said comparison signal, and adapted to adjust said condition signal generating means to compensate for deviations between the condition output signal generated due to reference fuel flame front and said reference value signal; and, (m) means for retaining said adjustment to said condition signal generating means when said isolation period is ended and said fluid stream is returned to said flame generating means in place of said reference fuel, `whereby the condition output signal generated by said fluid stream flame front is compensated for combustion effects not indicative of composition characteristic, yand said condition output signal is thereby functionally representative of and correlatable with the actual composition characteristic of said combustible fluid mixture.

In essence therefore, the present invention provides a method and apparatus which determines the composition characteristic of a combustible fluid mixture by oxidizing the lluid 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 periodically recalibrated to compensate for deviations in condition output signal generated by a reference fuel of known composition characteristic. Furthermore as shall be set forth hereinafter, 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 in- .vention 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 or vapor phase chromatographs. Rather, the composition characteristic is represented by a continuous, or substantially continuous, output signal which is responsive to and indicative of the fluid composition, and which is more specifically, empirically 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 lluid 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 signal 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) includin-g by way of illustration, the expansion or contraction of a Bourbon 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 nal 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 calibrated in terms of the desired identifying composition characteristic of the fluid sample, such as octane num- `8 ber, initial boiling point, 90% boiling point, vapor pressure, and the like.

In the practice of this invention the location of the cool flame front is, preferably, determined by temperature sensing devices, such as a pair of axially spaced thermocouples fixed at a known distance from one end of the combustion zone and at a known and fixed distance from each other, e.g. one (l) inch. As will be more fully developed hereinbelow, the signal developed by the thermocouple means activates appropriate control means for adjusting a combustion zone parameter or condition so as to immobilize the cool llame 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 gaseous and normally liquid combustible chemicals. In a particularly preferred embodiment, the test samples comprise hydrocarbon-containing 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 from 1 to about 22 carbon atoms per molecule. The upper limit on carbon number is xed 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 fluids 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 which are chargeable to the apparatus of the present invention include those within the gasoline boiling range produced by blending such component fluids 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 this compensation in the condition output signal, there is provided means for periodically isolating the blended fluid being tested from the combustion chamber of the apparatus, and for simultaneously introducing therein a sample of a reference fuel. Those skilled in the art are familiar with the procedures for obtaining reference fuels of known composition. Since vthe 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 iluid 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 fuel also have an octane rating of about 95 and that it primarily comprise a reformate gasoline.

The oxidizer or oxidizing agent utilized in the apparatus of the present invention is preferably an oxygen-containing gas, such as 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.

'Ille generation of the stabilized cool flame is effected under combustion conditions generally including superatmospheric pressure and elevated temperature, although in some cases, it may be desirable to use atmospheric pressure or sub-atmospheric pressure. For example, the pressure may be in the range from about 15 p.s.i.a. to about 165 p.s.i.a. with a maximum flame front temperature in the range of 600 F. to l000 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 sample and the reference sample. Furthermore, induction 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 fluid sample.

As previously mentioned, the detection o 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 may be placed within the combustion chambers, as discussed hereinabove, or outside of the combustion chamber, and may be either fixed or may be 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.

The output signal from the thermocouple sensing means is fed through signal means to suitable control means such as a motor activated control valve for regulating, perferably, the pressure within the combustion zone. Generally, the output signal from the thermocouple sensing means is not sent to a readout device, such as a strip chart or x-y recorder, 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 comprises a pair of axially spaced thermocouple leads which are inserted into thin-walled thermal type pencil wells and may be constructed of any materials known to those skilled in the art, such as for example, iron-constantan. The lead wires from the thermowells are connected -to a suitable `differential temperature controller. Such controller may be a conventional selfbalaucing potentionmeter in combination with pneumatic control means. A suitable input span for the controller may be from to +5 milivolts and the output signal thereof transmitted 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.

The present invention may be more fully understood by now referring to the accompanying drawings.

FIG. l comprises a simplified schematic representation of the apparatus for practicing the present invention in a typical gasoline blending system wherein the signal conditioning 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 10 gasoline blending system wherein the signal conditioning means comprises an analog or a digital network.

DESCRIPTION 0F THE DRAWINGS With reference now #to the accompanying FIG. l, there is shown the apparatus of the present invention which comprises in combination a canister 1 enclosing a combustion cham-ber 2. The Icanister has means for lintroducing a heat transfer fluid to surround the combustion chamber so that proper temperature conditions may be maintained within the combustion zone, by controlling temperature in an elevated temperature zone 3 which is confined between the canister 1 and the combustion chamber 2. 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 3 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 3, or heating elements encompassing the canister. If desired, the exterior of `the enclosing canister 1 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 understand the appropriate manner of enclosing the cornbustion 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 2, there is provided temperature sensing means 4 and 5 which are capable of sensing the location of the stabilized cool flame front generated within the combustion chamber by the oxidation of the sample being introduced therein. The combustion chamber 2. is provided with inlet means 6 which introduces a mixture of air, or other oxidizing agent, and a combustible fuel into a burner nozzle, not shown, contained within the lower section of the combustion chamber 2. The air or oxidizing agent is introduced into the system via line 8 and the combustible fluid s introduced into the system via line 7. The net combustion products are ultimately discharged from the combustion chamber via line 9.

The mixture of air and combustible fluid passes into the chamber 2 via line 6 wherein it is ignited due to the elevated temperature. The region of the combustion chamber 2 which is located between the inlet line 6 and the temperature sensing means 5 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 2 located between the lburner 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 yattached FIG. 1 is utilized to detect the octane number of a gasoline blend of unknown composition. The gasoline fraction is introduced into the analytical system via line 19 from a gasoline blending process which will be described more fully hereinaf-ter. A sample of blend is passed via line 19 through control means 21, and the sample then enters line 7 wherein it is contacted with a stream of air passing into the system via line 8. The air and the gasoline sample pass into the combustion chamber 2 via line 6. 'Ihe mixture of air and gasoline passes through the -burner nozzle at the bottom of chamber 2, 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 3. 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 4 and 5 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 `cornbustion chamber 2 via line 9- 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 4 and 5, 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 flame front to recede towards the burner end of combustion chamber and a decrease in pressure will cause the flame front to advance away from the Iburner 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 5 will reflect a temperature rise. Temperature sensing means 5 will reflect a temperature rise. Temperature sensing means 4 and 5 will transmit the sensed temperatures via transmitting means and 11 to a differential temperature controller 12, which will then activate a pressure controller 14 by passing a pressure control signal thereto via line 13. 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 4 and 5. Conversely, if the hydrocarbon composition changes so that the flame front attempts to move away from the burner end of the chamber, temperature sensing element 4 will sense a temperature rise and the differential temperature controller will activate the pressure controller 14 to increase combustion chamber 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 lwithin 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 13 from the differential temperature controller 12 includes the hydrocarbon sample flow rate in line 7, the oxygen containing gas flow rate in line 8, 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 lin a manner to immobilize the flame front relative to its position within the combustion chamber 2, 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 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 4 and 5. 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 flame 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 flame front for the combustible fluid sample is positioned between la pair of thermocouples 4 and 5 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 12 will be approximately zero. However, equally satisfactory operation can be achieved by having a net voltage difference if the positive or negative corresponding to a temperature differential is .in the order of 10 F. to 40 F. This means that the flame front in the combustion chamber 2 is then slightly asymmetrical with respect to the thermocouples 4 and 5. 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 12.

In any event, the sensing means 4 `and 5, the transmitting means 10 and 11, :and the differential temperature controller 12 will enable one to determine the exact position of the cool flame front by a differential temperature measurement. Controller 12 will then activate the pressure control means 14 4in order to ladjust the flame front :to a position where there is, as previously mentioned, typically a zero temperature differential. 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 fuel which is being oxidized within the combustion chamber 2.

Accordingly, then, there is provided within the apparatus a pressure sensing means 15 which develops a continuous pressure signal transmitted via line 1'6 to a transducer 17. The transducer 17 converts the pneumatic or mechanical pressure signal 16 into an electrical signal which may be a voltage signal or an amperage signal. The transducer 17 transmits a converted parameter output signal via line 18 into a signal conditioning means 25, which in this embodiment comprises a digital or an analog computer means. Computer means 25 contains an internal computer program by which the converted parameter signal 18 is continuously converted into a pair of output signals 26 and 84, which are functionally representative of and correlatable with the octane rating of the combustible sample of gasoline `blend introduced into the system via line 1'9. The condition output signal 26, typically, is thereupon transmitted to an octane display device 27 which may comprise a recording chart device, or a tape print-out device, or any other type of indicating means. In addition, the octane display device 27 may comprise a control system whereby an output signal for control of octane number is transmitted to means 85, 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. 1, control means is adjusted by condition output signal 84.

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 28 which is capable of sensing any fluctuations in temperature Awithin the elevated temperature Zone 3.

Alternatively, temperature sensing means 28 may be positioned within combustion chamber 2 in order to sense actual uctuations in induction section temperature. Temperature sensing means 28 passes a temperature output signal via transmitting means 29 to the signal conditioning means 25. The internal program of the computer means 25 thereupon makes a temperature correction to the condition output signals passing via lines 26 and 84. Thus, the octane value thereafter indicated by octane display device 27 is continuously compensated for any error in the indicated composition characteristic which is due to temperature fluctuations in the induction section of chamber 2 or in the elevated temperature zone 3, 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 26 and 84 which reflects and compensates for fluctuations in the relative proportion of the various component uids which are entering the blending system to produce the finish blend, a test sample of which is passed into the apparatus via line 19.

Referring again to 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 nished blended gasoline having a predetermined composition characteristic, such as octane rating. A reformate gasoline stream enters the. blending process via line 40 and a straight-run gasoline stream enters line 40 via line 41. Typically, the gasoline blending system will blend at least two component gasolines, but for illustrative purposes various component gasoline fractions are shown in FIG. l, inv order to illustrate the various types of hydrocarbon constituents which may be blended together. Thus, there is shown in FIG. l an alkylate gasoline fraction entering line 40 via line 42, a cracked gasoline fraction entering line 40 via line 43, a volatility component such as butane and/or pentane entering line 40l via line 44, and an anti-knock agent such as a lead alkyl entering line 40 via line 45.

The reformate gasoline fraction is a highly aromatic stock, while the straight-run gasoline fraction is a blending component which is high in normal paraiiins and in naphthenes. The alkylate gasoline fraction is a blending component which is high in isoparaiins, 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 eects 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 40 into a mixing or blending zone, which for illustrative purposes is shown in FIG. l as an in-line blender 46. The inal gasoline blend is discharged from in-line blender 46 via line 47 and a sample of the linished blend is withdrawn via line 19 as discussed hereinabove.

In order to make compensating adjustments to the condition output signals 26 and 84 which are reflective of the varying proportions of components passing into the blending process, there is provided means for sensing the flow of each component fluid passing into the blending system. In order to sense the flow of reformategasoline, there is provided in line 40 a ow sensing means such as an orifice 48 which transmits a flow signal via line 49 to a transducer 50. The differential pressure signal developed by the iiuid passing through orilice 48 and transmitted via line 49, is converted by transducer 50` into an electrical signal which is passed via line 51 into the computer means 25. The flow of straight-run gasoline is sensed by a flow sensing means 54 which transmits a AP flow signal via line 55 to transducer 56, which thereafter passes an electrical flow signal via line 57 into computer means 25. In a similar manner, the rate of ow of alkylate gasoline into the blending process is sensed by orifice 60 which transmits a AP ow signal via means 61 to transducer 62, which in turn transmits an electrical ow signal to computer means 25 via line '63. Additionally, the cracked gasoline ow rate is sensed and transmitted by means 66, 67, 68, and 69 to deliver an electrical input signal of cracked gasoline ow to computer means 25. The volatility component flow is sensed and transmitted by means 72, 73, 74, and 75 to deliver an electrical flow signal of volatility component to computer means 25. Finally, the flow rate of lead alkyl entering the blending process is sensed and transmitted by means 78, 79, and 81, whereby an electrical flow signal is delivered to computer means 25.

Computer means 25, now continuously receiving the rate of ow for each component entering the blending process, takes the information into the internal program of the computer, whereby the relative inuence of each component upon the combustion within the combustion chamber 2 is determined. In this manner, the relative' rate of iiow of each component provides a direct measurement of the relative combustion effect of the aromatic component entering the process, the normal paraffnic component entering the process, the naphthenic component entering the process, the isoparaflinic component entering the process, the olelinic component entering the process, the volatility component enteringthe process, and the anti-knock agent entering the process. Cornputer means 25 is able by means of the internal computer program, to make compensating adjustments to the parameter input signal 18, and thereby render a correction to the resulting condition output signals 26 and 84 which reflect a correction to these output signals for the effects of the various components entering the gasoline blend.

Thus, condition output signals 216 and 84 are conltinuously compensated for combustion effects which are not indicative 0f the composition characteristic being determined, such as blend octane rating.

As noted hereinabove, the signal conditioning means 25 delivers a condition output signal via transmitting means 84 to a controlling means, which for illustrative purposes is shown as a valve means 85 located in line 45. In this manner, then, the computer means 25 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 invention is utilized to control the blending system in a manner suicient to produce a constant value of composition characteristic for the final flinished 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 84 and the control means 85 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 40, or to control the input of an anti-knock agent such as the lead alkyl entering the blending system via line 45. Alternatively, the input of a low octane component such as the straightrun gasoline could be controlled. In this manner, then, the apparatus and control system will produce a controlled nished 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.

In addition, the apparatus of the present invention provides for a recalibration or a re-izeroing of the system for deviations created by other combustion eects which are not reflective of the composition characteristic of the blended fuel being tested. Accordingly, there is provided means for periodically passing into the combustion chamber 2 a reference fuel by which the system may be recalibrated.

Thus, there is shown in FIG. 1 a reference fuel passing into the system via line 20. A timing device 23 passes a timing signal via line 22 into a control valve 21. During the period of isolation, the control valve 21 receives a timing signal by which the test sample of line 19 is switched out of the system and the reference fuel of line 20 is switched into the system. Thereafter, during the isolation or reference period, reference fuel passes via line 7 into line 6 in admixture with the air entering via line 8.

The reference fuel produces a stabilized cool flame which is indicative of the octane rating, or other composition characteristic being determined, of the reference fuel. The temperature sensing means 4 and 5 transmit the sensed temperature signals via means 10 and 11 into the differential temperature controller 12, whereupon differential temperature controller 12 passes a control signal via line 13 to pressure control means 14. The pressure sensing means 15 passes the pressure signal via line 16 into transducer 17 which in turn passes a converted parameter sig-nal |18 into the computer means 25. The internal program of computer means 25 compares the signal 18 with a reference signal contained within the program. The reference signal is indicative of the known actual octane rating of the reference fuel. The timing device 23 sends a signal via line 24 to the computer means 25 during those periods of time when the reference fuel is being burned within combustion chamber 2.

Accordingly, then, the computer program Will make a compensating adjustment to the condition output signal 26 in order to eliminate any deviation of converted parameter signal 18 from the known signal which is reflective of the actual composition characteristic or octane number of the reference fuel. When the period of isolation is ended, timer 23 sends a signal via line 22 to valve 21 to swing the valve in a manner sufficient to isolate the reference fuel of line from the system and to continue the introduction of test sample via line 19. At this point then, the timing signal passing via line 24 to computer means 25, informs the computer means that the reference fuel has been cut out of the system and that the test sample has been reintroduced. The internal computer program of the computer means 25 at this point retains any reference fuel correction which was made within the system. Consequently, the resulting condition output signal passing via line 26 to octane display device 27 when the test sample is being tested, will reflect a cornpensation or recalibration of the system for the reference fuel.

Of course, those skilled in the art will readily perceive that during the isolation or reference period when the test sample of line 19 is replaced by the reference fuel of line 20, the condition output signal l84 cannot be utilized to control the valve means 85 and thereby maintain a constant predetermined value of octane rating for the iinished blend. During this isolation period the converted parameter signal 18 passing into the signal conditioning means 25 will not be indicative of the composition characteristic of the finished blend since the signal 18 is produced by the combustion of the reference fuel. Accordingly therefore, when the timing signal 24 which passes into the computer means 25 relates to the internal program that reference fuel is passing into the combustion chamber 2, the internal program of computer means 25 will provide that the condition output signal 84 will be locked in, so that the valve means 85 will be held at a constant throttling position. Therefore, during the short period of recalibration or of re-zeroing the apparatus of the present invention to compensate for aging effects in the combustion tube as indicated by the combustion of the reference fuel, the finished blend will be produced at a constant predetermined octane rating in accordance with the last setting which was provided by the combustion of the test sample.

Accordingly then, when the timing device 23 again cuts the test sample of line 19 back into the apparatus of the present invention and simultaneously isolates the preference fuel of line 20 therefrom, the indicated octane num- 16 ber of the test sample which is thereafter produced during the testing period Will have been corrected for component proportions, for temperature conditions, and for other combustion effects which were not truly indicative of the composition characteristic such as octane number. Accordingly then, the indicating condition output signal 26, as well as the controlling condition output signal 84, will be truly indicative of and directly correlatable with the octane number or other composition characteristic of the test sample being oxidized .in combustion chamber 2.

Referring now to FIG. 2, there is shown a second embodiment of the present invention wherein the signal conditioning means of FIG. 1, the computer means 25 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 transducer output signal leaving transducer 17 is transmitted via means 18 into a signal conditioning network 30. The signal conditioning network 30 is a type of apparatus which is well known in the art. The converted parameter signal 18 passing from transducer 17 has a fixed correlation between the pressure which is sensed in the combustion chamber 2 by the pressure sensing means 15, and the resulting electrical output signal which is passed through the signaling conditioning network The conditioning network 30 either multiplies, or it adds and subtracts to the received transducer signal 18 in order to produce a net output signal which is correlatable with octane rating or any other composition characteristic being determined. In the preferred embodiment, signal conditioning network 30 will add and subtract to the signal 18. The resulting pressure output signal is transmitted from signal conditioning network 30 via transmitting means 31 into a summing means 32.

In addition, in the embodiment illustrated in FIG. 2, the temperature signal which is sensed in the elevated temperature zone 3 by the sensing means 28 is transmitted via line 2 9 into a signal conditioning network 33. Again, the signal conditioning network 33 is a type of network which is well known in the art. The temperature signal has a fixed correlation between the temperature in the elevated temperature zone 3 and the octane rating or other composition characteristic being determined within the combustion chamber 2. The conditioning network 33, therefore, adds or subtracts to the signal 29 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 3. Alternatively, induction section temperature may be sensed by means 28, and network 33 may compensate for any deviation from the base induction section temperature. The resulting signal is passed from the signal conditioning network 33 with a compensation for any temperature deviation, into summing means 32 via transmitting means 34.

Furthermore, in the embodiment of FIG. 2, the converted flow signal 51 which is representative of the flow of reformate gasoline passing into the blending process, is transmitted to a signal conditioning network 52. Again the signal conditioning network 52 is a type of network which is well known in the art. There is a fixed correlation between the actual ilow of the reformate` gasoline and the resulting octane contribution to the final blended gasoline product octane number. Consequently, the signal conditioning network 52 develops a continuous octane correction factor for the flow of aromatic fluid passing through orifice 48. The aromatic or reformate octane correction factor is pased via transmitting means 53 to summing means 32.

In a similar manner, there is a provision for 4passing the converted flow signal 57, which is representative of the flow of straight-run gasoline into the blending process, to a signal conditioning network 58. This signal conditioning network is similar to that of network 52. There is a fixed correlation between the actual flow 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 58 develops a continuous octane correction factor for the flow of this normal paraffinic fiuid passing through the orifice 54. This normal parafiinic or straight-run gasoline octane correction factor is transmitted via means 59 to the summing means 32.

In a similar manner, the alkylate gasoline component flow signal 63 is passed to a signal conditioning network 64 which develops an octane correction factor for the isoparafiinic component passing to the gasoline blend. The octane correction factor is passed from signal conditioning means 64 via transmitting means 65 to the summing means 32.

A correction to the octane contribution of the cracked gasoline is also provided for in the apparatus as set forth in FIG. 2. Flow signal 69 passes into a signal conditioning network 70 which thereafter transmits an octane correction factor for the olefnic component via transmitting means 71 into the summing means 32. Similarly, a correction for the octane contribution of the volatility component is provided by sending the flow signal 75 to a signal conditioning network 76 which thereupon develops an octane correction factor signal passing via means 77 to the summing means 32. 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 flow signal 81 into the signal conditioning network 82 `which in turn develops an octane correction factor transmitted via means 83 to the summing means 32.

Summing means 32 receiving the temperature signal 34, the parameter output signal 31, and the component octane correction factor signals 53, 59, 65, 71, 77, and 83, thereupon algebraically sums the signals. The net result of the algebraic summation accomplished by summing means 32 is a modified parameter signal fwhich is in fact the net condition output signal which is indicative of the apparent composition characteristic as compensated for any component and temperature fluctuations. Thus when the test sample of line 19 is oxidized in combustion chamber 2, the summing means 32 sends a condition output signal 26 to the octane display device 27 which gives the apparent octane rating of the test sample of the finished blended gasoline product.

In the embodiment illustrated in FIG. 2, the octane display device 27 contains a control system Iwhich not only gives an indication of the actual octane of the test sample but which also develops a control output signal 86 passing to the control valve 85. The control set point contained within means 27 is set to the desired specification composition characteristic, in this instance the octane rating of the finished blend, and the control output 86 thereupon throttles the valve 85 to admit a sufficient amount of anti-knock agent (lead alkyl) to control the octane rating of the finished blend to the specification set point. Of course, as noted hereinabove, the control output signal 86 could alternatively be utilized to control the input of a high octane blending component such as theY reformate gasoline in order to control the octane rating of the finished blend to the set point value. Similarly, signal 86 could be utilized to control the input of a low octane blending component such as the vstraight-run gasoline.

When reference fuel is being oxidized in chamber 2, summing means 32 sends a condition output signal via transmitting means 35 to an error amplifier 36, as well as the condition output signal 26 to the display device 27. The error amplifier 36 is a device which is well known in the art. The error amplifier contains a manual set point which is representative of the actual known octane number of the reference fuel. Accordingly, the error amplifier receives the timing signal from timer 23 via transmitting means 24 when the reference fuel is being oxi dized within the combustion chamber 2. At this point then, the error amplifier compares the condition output signal 35 with the known set point which is correlatable with the known actual composition characteristic, such as octane number, of the reference fuel. Thereupon the error amplifier develops an output signal which is a function of the difference between the set point and the actual summation or condition output signal 35.

Simultaneously, the timer 23 sends an additional timing signal via transmitting means 87 to the octane display device 27. The timing signal 87 is passed to means 27 in order to lock the control signal 86 at a constant value during that period of time when the condition output signal 26 is no longer indicative of the octane rating of the blended product but instead is indicative of the octane rating indicated for the reference fuel. By this means, the system provides that the gasoline blending process will continue to make a gasoline blend meeting the octane specification in response to the test sample octane value and not in response to the currently develvoped octane value of the reference fuel. During the short period of time, which is typically from 3 to 5 minutes, during which the reference fuel is introduced into the apparatus, the gasoline blending process will continue to produce a gasoline blend which meets the specification responsive to the composition characteristic and the condition output signal 26 which is correlatable 1with the octane rating of the test sample as of the last moment when the test sample was passed into the combustion chamber.

Meanwhile, the error-amplifier 36 transmits its output signal via transmitting means 37 to a servo-amplifier 38. The servo-amplifier is a device which is well known in the art. The servo-amplifier upon receiving the erroramplifier output signal, reponds to the error output signal in order to make a correction to bring the condition output signal 35 -into balance with the set point contained within the error-amplifier. Accordingly, the servo-'amplifier 38 develops an output signal which is portional to the erroramplifier output signal which has been received. The servoamplifier is a power amplifier sending a power signal via means 39 to a servo-motor located within signal conditioning network 30. The servo-motor mechanically adjusts the signal conditioning network 30 to produce an ultimate summation or condition output signal 35 which is identical to the manual set point which is contained in the error-amplifier 36. Thus the system is corrected to the known octane value or other base line composition characteristic of the reference fuel.

The resulting pressure output signal transmitted via line 31 thereupon becomes directly correlatable 'with the octane number or other measured composition characteristic of the reference fuel being oxidized within combustion chamber 2. Summing means 32 thereupon develops an output signal 35 which passes to the error-amplifier and is therein indicated to be in balance with the manual set point. At this juncture then, the modified condition output signal which is transmitted via means 26 to the octane display device 27 will indicate the true octane number for the reference fuel as corrected for combustion effects which are not indicative of the composition characteristic being determined.

When the system reaches a time when the period of isolation is over, timer 23 will switch valve 21 by means of a signal passing via line 22 in order to cut out the reference fuel 20 and reintroduce the test sample 19 into the analyzer of the present invention. At this point then, the timer 23 sends a signal via transmitting means 24 to the error-amplifier which will enable the system to hold the compensating adjustment which was made in signal conditioning network 30 to balance out the reference fuel output signal 35 with `the manual set point. Simultaneously, timer 23 passes a signal via line 87 which releases the hold which was placed upon the control output signal 86 during the isolation or reference period. In this manner then, when the test sample of line 19 is being oxidized the modified condition output signal 26 passing to the display device 27 is indicative of the composition characteristic being measured, such as octane number, while being cornpensated for component flows and temperature fluctuations and for any deviations of the reference fuel signal from the known base reference signal. Thereafter, control signal 86 will adjust control means `85 in a manner sufficient to pass the lead alkyl anti-knock agent into the blending process at a rate controlled to produce a final gasoline blend which meets the required specification value of octane rating or any other composition characteristic being determined.

PREFERRED EMBODIMENTS Those skilled in the art will readily perceive the apparatus configuration of the present invention and the method of operation which have been disclosed hereinabove. Additionally, those skilled in the art can readily perceive the advantages of the present invention as disclosed hereinabove.

However, even though those skilled in the art -will easily recognize the distinction between the terms signal conditioning means and signal conditioning network, it is deemed advantageous to define and distinguish these terms as used herein. Referring to FIG. 1, the signal conditioning lmeans comprises the computer means 25, which contains an internal computer program for making compensating adjustments to produce the 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. Thus, the signal conditioning networks 30, 33, 52, 58, `64 70, 76, and 82 which are disclosed in FIG. 2, are individual elements contained Within the signal conditioning means of that embodiment.

Furthermore, it is to be noted that the composition characteristic being determined by the present 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 26, 35, and 84, is in tact a modified parameter output signal which in the preferred embodiment is a pressure signal. Thus, when the reference fuel is passing to the combustion chamber 2 and condition output signal 35 is compared with `the reference value signal in error-amplifier 36, the reference value signal is, in fact, being matched with a modified parameter signal 35.

Therefore, from the above description it may now be summarized that one preferred embodiment of the present invention provides a lmethod 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 fluid mixture and a stream of oxygencontaining 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 suflicient to generate and maintain therein, a cool flame characterized by a vrelatively narrow well-defined llame front spaced from said one end; (c) sensing the position of said 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 ilow rate, and oxygen-containing gas stream llow rate, in a manner suflicient to immobilize said llame front relative to said one end regardless of fluctuations in the composition characteristic of said sample stream; (e) sensing the adjusted parameter and developing a first parameter signal responsive to changes in said composition characteristic; (f) developing a first component signal representative of the relative amount of a first component fluid being blended in said plurality to produce said combustible fluid mixture; (g) passing said first parameter signal and said first component signal into signal conditioning means, and producing therefrom a first condition output signal functionally representative of the composition characteristic of said sample stream of fluid mixture, said condition output signal being indicative of said composition characteristic as corrected for deviations in said parameter signal/caused by the relative amount of said first component fluid in said combustible fluid mixture; (h) periodically isolating said sample stream from said combustion zone, and simultaneously passing a stream of reference fuel having a known value of cornposition characteristic, into said zone in a manner Sullicient to continue the generation of said immobilized flame front; (i) sensing the adjusted parameter during the period of isolation and passing a second parameter signal into said signal conditioning means, said second parameter signal being functionally representative of the apparent composition characteristic of said reference fuel; (j) comparing said second parameter signal with a reference value of parameter signal functionally corresponding to the actual known value of composition characteristic of said reference fuel; (k) adjusting said signal conditioning means in a manner suflicient to produce a second condition output signal which is compensated to reflect the elimination of the difference between said second parameter signal and said reference value parameter signal, and which is thereby functionally representative of the actual known composition characteristic of said reference fuel; (l) periodically isolating said reference fuel stream from said combustion zone while retaining the signal conditioning adjustment of step (k), and simultaneously passing said fluid sample stream into said zone in a manner suflicient to maintain said flame front, whereby said signal conditioning means receives a third parameter signal and a second component signal representative of the relative amount of said first component fluid, and said signal conditioning means therefrom develops a third condition output signal compensated for combustion effects not indicative of composition characteristic, and said third condition output signal is thereby functionally representative of the actual composition characteristic of said sample stream; and, (m) passing said third condition output signal to means controlling the relative amount of a second component fluid being blended in said plurality to produce said combustible fluid mixture, whereby the sample stream of fluid mixture produces a condition output signal functionally representative of a predetermined value of composition characteristic.

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 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 therefore 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, fluid stream flow rate, and oxidizer stream flow rate in a manner suflcient 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; (f) means developing a component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible fluid mixture; (g) signal conditioning means receiving said parameter output signal and said component signal; (h) condition signal generating means within said signal conditioning means producing a condition output signal functionally representative of said composition characteristic; (i) means periodically isolating said fluid stream from said flame generating means., and siunultaneously passing a stream of reference fuel having a known value of composition characteristic, into said flame generating means in a manner sufficient to continue the generation of said immobilized flame front; (j) means passing to said signal conditioning means, a timing signal indicative of the passage of reference fuel to said flame generating means; (k) comparison means within said signal conidtioning means, responsive to said timing signal, adapted to compare the condition output signal generated due to reference fuel flame front with a reference value signal functionally corresponding to the actual known value of composition characteristic of said reference fuel, and therefrom developing a comparison signal; (l) adjusting means within said signal conditioning means, responsive to said comparison signal, and adapted to adjust said condition signal generating means to compensate for deviation between the condition output signal .generated due to reference fuel flame front and said reference value signal; (m) means for retaining said adjustment to said condition signal generating means when said isolation period is ended and said fluid stream is returned to said flame generating means in place of said reference fuel, whereby the condition output signal generated by said fluid stream ame front is compensated for combustion effects not indicative of composition characteristic, and said condition output signal is thereby functionally representative of and correlatable with the actual composition characteristic of said combustible fluid mixture; (n) means controlling the relative amount of a second component fluid contained in said combustible fluid mixture; and, (o) means transmitting to said control means (m), said condition output signal, whereby said resulting combustible fluid mixture is controlled at a constant predetermined level of combustion characteristic.

The invention claimed is:

1. Method for detecting composition characteristic of a combustible fluid mixture produced by combining a plurality of component fluids, which compr1ses:

(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 sufficient to generate and maintain therein, a cool flame characterized by a 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 ow rate, and oxygen-containing gas stream flow rate, in a manner sufficient to immobilize said flame front relative to said one end regardless of fluctuations in the composition characteristic of said sample stream;

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

(f) developing a component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible fluid mixture; and,

(g) passing said parameter signal and said component signal into signal conditioning means, and producing therefrom a condition output signal functionally representative of the composition characteristic of said sample stream of fluid mixture, said condition output signal being indicative of said composition characteristic as corrected for deviations in said parameter signal caused by the relative amount of said first component fluid in said combustible fluid mixture.

2. Method of claim 1 wherein said combustion zone is confined in an elevated temperature zone, a temperature selected from the group consisting of a temperature in said induction section and a temperature in said elevated temperature zone is sensed and a temperature signal is developed therefrom, said temperature signal is passed into said signal conditioning means, and said condition output signal is thereby rendered functionally representative of said composition characteristic as corrected for temperature deviations.

3. Method of claim 1 wherein said combustible fluid mixture comprises gasoline boiling range hydrocarbons and the detected composition characteristic is octane rating.

4. Method for detecting composition characteristic of a combustible uid 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 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 llame characterized by a relatively narrow lwell-defined flame 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; t

y(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 gas stream flow rate, in a manner sufficient to immobilize said flame front relative to said one end regardless of fluctuations in the composition characteristic of said sample stream;

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

(f) developing a first component signal representative of the relative amount of a first component fluid of said plurality contained in said combustion fluid mixture;

(g) passing said first parameter signal and said first component signal into signal conditioning means, and producing therefrom a first condition output signal functionally representative of the composition characteristic of said sample stream of fluid mixture, said condition output signal being indicative of said composition characteristic as corrected for deviations in said parameter signal caused by the relative amount of said first component fluid in said combustible fluid mixture;

`(h) periodically isolating said sample stream from said combustion zone, and simultaneously passing a stream of reference fuel having a lknown value of 23 composition characteristic, into said zone in a manner sufficient to continue the generation of said immobilized flame front;

(i) sensing the adjusted parameter during the period of isolation and passing a second parameter signal into said signal conditioning means, said second parameter signal being functionally representative of the apparent composition characteristic of said reference fuel;

(j) comparing said second parameter signal with a reference value of parameter signal functionally corresponding to the actual known value of composition characteristic of said reference fuel;

(k) adjusting said signal conditioning means in a manner sufficient to produce a second condition output signal which is compensated to reflect the elimination of the difference between said second parameter signal and said reference value parameter signal, and which is thereby functionally representative of the actual known composition characteristic of said reference fuel; and,

(l) periodically isolating said reference fuel stream from said combustion zone while retaining the signal conditioning adjustment of step (k), and simultaneously passing said fluid sample stream into said zone in a manner sufficient to maintain said llame front, whereby said signal conditioning means receives a third parameter signal and a second component signal representative of the relative amount of said first component fluid, and said signal conditioning means therefrom develops a third condition output signal compensated for combustion effects not indicative of composition characteristic, and said third condition output signal is thereby functionally representative of the actual composition characteristic of said sample stream.

5. Method of claim 4 wherein said combustion zone is confined in an elevated temperature zone, a temperature selected from the group consisting of a temperature in said induction section and a temperature in said elevated temperature zone is sensed and a temperature signal is developed therefrom, said temperature signal is passed into said signal conditioning means, and each condition output signal is thereby rendered functionally representative of said composition characteristic as corrected for temperature deviations.

i6. Method of claim 4 wherein said combustible fluid mixture comprises gasoline boiling range hydrocarbons and the detected composition characteristic is octane rating.

7. 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 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 sufficient to generate and maintain therein, a cool flame characterized by a relatively narrow well-defined flame front spaced from said one end;

l(c) sensing the position of said flame 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 gas stream rflow rate, in a 'manner sufficient to'immobilize said flame front relative to said one end regardless of fluctuations in the composition characteristic of said sample stream;

(e) sensing the adjusted parameter and developing a 24 first parameter signal responsive to changes in said composition characteristic;

(1f) developing a first component signal representative of the relative amount of a first component fluid being blended in said plurality to produce said combustible fluid mixture;

(g) passing said first parameter signal and said first component signal into signal conditioning means, and producing therefrom a first condition output signal functionally representative of the composition characteristic of said sample stream of fluid mixture, said condition output signal being indicative of said composition characteristic as corrected for deviations in said parameter signal caused by the relative amount of said first component fluid in said combustible fluid mixture;

(h) periodically isolating said sample stream from said combustion zone, and simultaneously passing a stream of reference fuel having a known value of composition characteristic, into said zone in a manner suiiicient to continue the generation of said immobilized flame front;

(i) sensing the adjusted parameter during the period of isolation and passing a second parameter signal into said signal conditioning means, said second parameter signal being functionally representative of the apparent composition characteristic of said reference fuel;

(j) comparing said second parameter signal with a reference value of parameter signal functionally corresponding to the actual known value of composition characteristic of said reference fuel;

(k) adjusting said signal conditioning means in a manner sufficient to produce a second condition output signal which is compensated to reflect the elimination of the difference between said second parameter signal and said reference value parameter signal, and which is thereby functionally representative of the actual known composition characteristic of said reference fuel;

(l) periodically isolating said reference fuel stream from said combustion zone while retaining the signal conditioning adjustment of step (k), and simultaneously passing said fluid sample stream into said zone in a manner sufficient to maintain said llame front, whereby said signal conditioning means receives a third parameter signal and a second component signal representative of the relative amount of said first component fluid, and said signal conditioning means therefrom develops a third condition output signal compensated for combustion effects not indicative of composition characteristic, and said third condition output signal is thereby functionally representative of the actual composition characteristic of said sample stream; and,

I(m) passing said third condition output signal to means controlling the relative amount of a second component fluid being blended in said plurality to produce said combustible fluid mixture, whereby the sample stream of fluid mixture produces a condition output signal functionally representative of a predetermined value of composition characteristic.

8. Method of claim 7 wherein said combustion zone is confined in an elevated temperature zone, a temperature selected from the group consisting of a temperature in said induction section and a temperature in said elevated temperature zone is sensed and a temperature signal is developed therefrom, said temperature signal is passed into said signal conditioning means, and each condition output signal is thereby rendered functionally representative of said composition characteristic as corrected for temperature deviations.

9. Method of claim 7 wherein said second component fluid is said first component fluid.

10. Method of claim 7 wherein said combustible fluid mixture comprises gasoline boiling range hydrocarbons 25 and the detected composition characteristic is octane rating.

11. Method of claim wherein said second component uid comprises an anti-knock agent.

12. A composition analyzer for detecting a composition characteristic of a combustible uid mixture produced by combining a plurality of component fluids, which comprises in combination:

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

(b) means for generating within said combustion chamber, a cool ame 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 flame front within said combustion chamber; I

(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, fluid stream tow rate, and oxidizer stream flow rate in a manner suicient 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;

(ff) means developing a component signal representative of the relative amount of a first component fluid of said plurality contained in said combustible liuid mixture; and,

(g) signal conditioning means receiving said parameter output signal and said component signal, and producing therefrom a condition output signal which is functionally representative of and correlatable with said composition characteristic of the combustible uid mixture, said condition output signal being indicative of sad compositon characteristic as corrected for devations in said parameter signal caused by the relative amount of said first component fluid in said combustible fluid mixture.

13. Apparatus of claim 12 wherein said control means (d) comprises means adjusting said combustion pressure.

|14. Apparatus of claim 12 wherein said signal conditioning means comprises computer means.

15. Apparatus of claim 12 wherein said flame position sensing means comprises a pair of axially spaced temperature sensing elements.

16. Apparatus of claim 12 wherein there is provided an outer chamber encompassing said combustion chamber and confining a zone of elevated temperature thereinbetween, means sensing a temperature selected from the group consisting of a temperature in said induction section and a temperature in said elevated temperature zone, and means transmitting a temperature signal from said temperature sensing means to said signal conditioning means, whereby said condition output signal is rendered functionally representative of said composition characteristic as corrected for temperature deviations.

17. A composition analyzer for detecting a composition characteristic of a combustible fluid mixture produced by combining a plurality of component fluids which comprises in combination:

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

(b) means for generating within said combustion chamber, a cool flame characterized by a relatively narrow well-defined flame front, utilizing as fuel therefor said combustible uid 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 vcombustion chamber;

(d) control means coupled to said position sensingl 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 stream flow rate in a manner sufficient to immobilize said ame 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;

(f) means developing a component signal representative of the relative amount of a rst component iiuid of said plurality contained in said combustible fluid mixture;

(g) signal conditioning means receiving said parameter out-put signal and said component signal;

(h) condition signal generating means within said signal conditioning means producing a condition output signal functionally representative of said composition characteristic;

(i) means periodically isolating said lHuid stream from ,said flame generating means, and simultaneously passing a stream of reference fuel having a known value of composition characteristic, into said flame generating means in a manner sufficient to continue the generation of said immobilized flame front;

(j) means passing to said signal conditioning means,

a timing signal indicative of the passage of reference fuel to said llame generating means;

(k) comparison means within said signal conditioning means, responsive to said timing signal, adapted to compare the condition output signal generated due to reference fuel flame front with a reference Value signal functionally corresponding to the actual known value of composition characteristic of said reference fuel, and therefrom developing a comparison signal;

(l) adjusting means within said signal conditioning means, responsive to said comparison signal, and adapted to adjust said condition signal generating means to compensate for deviation between the condition output signal generated due to reference fuel flame front and said reference value signal; and,

(m) means for retaining said adjustment to said condition signal generating means when said isolation period is ended and said fluid stream is returned to said flame generating means in place of said reference fuel, whereby the condition output signal generated by said fluid stream llame front is compensated for combustion effects not indicative of composition characteristic, and said condition output signal is thereby functionally representative of and correlatable with the actual composition characteristic of said combustible fluid mixture.

18. Apparatus of claim 17 wherein said means (d) comprises means adjusting said combustion pressure.

19. Apparatus of claim 17 wherein said signal conditioning means comprises computer means.

20. Apparatus of claim 17 lwherein said flame position sensing means comprises a pair of axially spaced temperature sensing elements.

21. Apparatus of claim 17 wherein there is provided an outer chamber encompassing said combustion chamber and confining a zone of elevated temperature thereinbetween, means sensing a temperature selected from the group consisting of a temperature in said induction section and a temperature in said elevated temperature zone, and means transmitting a temperature signal from said temperature sensing means to said signal conditioning means, whereby said condition output signal is rendered functionally representative of said composition characteristic as corrected for temperature deviations.

22. 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 association therewith conduit means passing the associated iluid 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 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 lluid mixture to be analyzed, said generating means including means passing a stream of said uid 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, lluid stream ilow rate, and oxidizer stream flow rate in a manner sulcient to immobilize said llame 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;

(f) means developing a component signal representative of the relative amount of a rst component iluid of said plurality contained in said combustible fluid mixture;

(g) signal conditioning means receiving said parameter output signal and said component signal;

(h) condition signal generating means `within said signal conditioning means producing a condition output signal functionally representative of said composition characteristic;

(i) means periodically isolating said fluid stream from said llame generating means, and simultaneously passing a stream of reference fuel having a known value of composition characteristic, into said llame generating means in a manner sulllcient to continue the generation of said immobilized flame front;

(j) means passing to said signal conditioning means, a timing signal indicative of the passage of reference fuel to said llame generating means;

(k) comparison means within said signal conditioning means, responsive to said timing signal, adapted to compare the condition output signal generated due to reference fuel llame front With a reference value signal functionally corresponding to the actual known value of composition characteristic of said reference fuel, and therefrom developing a comparison signal;

'(1) adjusting means within said signal conditioning means, responsive to said comparison signal, and adapted to adjust said condition signal generating means to compensate for deviation between the condition output signal generated due to reference fuel llame front and said reference value signal;

(m) means for retaining said adjustment to said condition signal generating means when said isolation period is ended and said lluid stream is returned to said llame generating means in place of said reference fuel, whereby the condition output signal generated by said fluid stream llame front is compensated for combustion eifects not indicative of composition characteristic, and said condition output signal is thereby functionally representative of and correlatable with the actual composition characteristic of said combustible lluid mixture;

(n) means controlling the relative amount of a second component lluid contained in said combustible iluid mixture; and

(o) means transmitting to said control means (m), said condition output signal, whereby said resulting combustible lluid mixture is controlled at a constant predetermined level of combustion characteristic.

23. System of claim 22 `wherein said means (f) com prises llow indicating means sensing the flow of first component fluid passing to said blending zone in the associated rst conduit means.

24. System of claim 22 wherein said means (m) comprises ilow control means controlling the llow of second component fluid passing to said blending zone in the associated second conduit means.

References Cited t UNITED STATES PATENTS 3,463,613 8/1969 Penske et al. 23-254 3,533,746 10/1970 Fenske 23-230 MORRIS O. WOLK, Primary Examiner R. E. SERWIN, Assistant Examiner U.S. Cl. X.R.

Images