US3451402A - Blending monitor - Google Patents

Description

June 24, 1969 w. A. HOWARD BLENDING MONITOR Sheet 'Original Filed March 22, 1965 Nun; Qhl Nm,

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INVENTOR BY Way/7 A HOM/0rd A! Or/ey Sheet June 24, 1969 w. A. HOWARD BLENDING MONITOR Original Filed March 22, 1965 United States Patent O 3,451,402 BLEN DIN G MONITOR Wayne A. Howard, Paris, France, assigner to Mobil Oil Corporation, a corporation of New York Continuation of application Ser. No. 453,858, Mar. 22, 1965. This application Sept. 6, 1966, Ser. No. 577,539 Int. Cl. E03b .7 /00; G05d 1.7/00; G0111 33/22 U.S. Cl. 137-3 14 Claims ABSTRACT OF THE DISCLOSURE A method of continuously blending a gasoline by operating a first engine on a target fuel and operating a second engine on a sample of the blended gasoline. The knock intensities of the target and sample fuels are compared to generate an error signal, and the error signal provides a basis for adjusting the relative proportions of the components forming the blended gasoline.

This application is a continuation of S.N. 453,858, filed Mar. 22, 1965, now abandoned, and a continuationin-part of S,N. 174,552, filed Feb. 20, 1962, now abandoned.

This invention relates to an improved method for automotive fuel evaluation, blending and control. More particularly, the present invention relates to a method for the formation of finished gasoline blends on a continuous basis and under conditions of constant control. By means of this method a desired correspondence may be achieved between selected characteristics of a finished gasoline product and a target fuel.

As presently practiced, the blending of gasolines and ladditives therefor for the purpose of producing a finished fuel are generally carried on as a batch process. RaW or stock gasolines Vary considerably as to volatility, which encompasses such characteristics as flash and fire point, vapor pressure, distillation and evaporation. Other significant variations of the quality of fuels as they emerge from the refining streams reside in the combustion characteristics of the gasoline as a motor fuel. Among these are such characteristics as octane number or anti-knock quality, heat of combustion and autogenous ignition temperature. The viscosity of the fuel as Well as its consistency and solidification characteristics also enter significantly into the evaluation of the material and its 'blending capability with other raw stock materials, as Well as its ultimate utility. An additional evaluation which is desirable and at time essential is the determination of the corrosion characteristics of the fuel material through measurement of hydrogen sulfide, mercaptan sulfur and corrosive sulfur content as well as the overall sulfur involved. Additional tests which may directly or indirectly aid in the determination of the corrosion characteristics of the fuel are denominated as tests for rust prevention, acidity and neutralization value and saponification. In addition to the foregoing, the determination of additional physical and chemical characteristics involves tests for the evaluaton of gravity and density, analine point, precipitation num-ber, ash and carbon residue.

The foregoing tests are essentially of a laboratory nature and are indirect indicators of the ultimate road performance of the fuel in commercial engines. These tests have in large measure been standardized by the American Society for Testing Materials and the tests are carried on by means of prescribed methods.

The necessity for the extensive testing of raw and finished gasoline stocks arises from a number of factors involving the Wide variation in the physical and chemical composition `and characteristics `of the crude material as well as the extensive variations involved in the processing methods and conditions to which the raw materials are subjected during the conversion process.

Of the foregoing tests, those directed to a determination of volatility index, combustion characteristics and sulfur content `are of prime relevance. The volatility index is related to the ability of the finished gasoline fuel to accomplish fast starting, Warm-up and smooth performance as well as the prevention of vapor lock. The combustion tests are on the other hand directed to heat content or mileage produced by the fuel as well as its antiknock or detonation characteristics. Sulfur content is in turn related to the minimization of corrosion and wear on the engine parts.

As heretofore stated, all of these properties vary initially 'with the source of the crude oil stock as Well as with the processing methods and conditions employed during the refining process. The consequent variation in the characteristics of the refinery stream requires the blending of the raw stocks so as to achieve the target specifications for the finished commerci-ally useful gasoline. Given the same crude, nevertheless Wide variations in the volatility, anti-knock or octane rating and sulfur content of the ultimate refinery product result from the employment of the lvariety of processing techniques available to the industry. Thus, the raw gasoline may be the result of simple distillation which produces straight run gasoline, or thermal or catalytic cracking may have 'been employed to produce a raw gasoline having entirely different characteristics. In addition, such gasoline may have been reformed or subjected to a polymerization process.

A significant example of this variation in raw gasoline characteristics which results from the choice of crude stock as Well as processing procedures is the anti-detonation quality or octane number of the fuel. The accompanying table taken from Conversion of Petroleum by A. N. Sachenen, Reinhold Publishing Corporation, 1940, page 325, illustrates this point.

TABLE 14s.-0CTANE NUMBERS 0F STRAIGHT-RUN AND CRACKED GASOLINES UNTREATED FROM THE SAME CRUDES (C.F.R. MOTOR METHOD) A.P.I. Octane Octane No. of

No. of straightmixed-phase run gasoline cracked gas- Crude (400 F.) oline (400 F.)

Pennsylvania, Michigan 42 65 Oklahoma City 48 68 East Texas 54 68 West Texas, Wink1er 60 71 Gulf Coast, mixed 66 74 California, Huntington Beach- 57 70 California, Midway. 68 74 Illinois 54 67 Arkansas, Smackov 68 73 Venezuela, Cumarebo.. 52 63 Venezuela, La Rosa 58 70 Mexico, Poza Rica. 44 65 Russia, Grozny 42 64 Russia, Baku-Surachany. 60 66 Iran 52 69 Iraq 45 67 Similar data with' reference to octane numbers of synthetic fuels is found in Table at page 327.

'I able 150.-Octane numbers of synthetic gasolines produced by various methods (EP. 400 F. C.F.R. Motor Method) 3 Table 150. (Continued)-Octane' numbers of synthetic gasolines produced by various methods (E.P. 400 F. C.F.R. Motor Method) Process: Octane number of cracked gasoline Selective polymerization and hydrogenation 90-99 Catalytic alkylation 85-92 It is significant that even when given the same crude stock and general Iprocessing method, nevertheless wide variations in yield and octane rating may result from relatively minor variations in the processing conditions. It is obvious therefore that in order to achieve a gasoline corresponding to a target specification, blending of the raw gasoline stocks is required. IIn addition to the blending of the raw gasolines, additives may have to be introduced depending upon the target specifications, as well as upon economic, marketing and technical factors. The additives introduced into the refinery output stocks may be for the purpose of upgrading the gasoline to provide higher octane ratings such as anti-detonants or the additives may constitute substances which improve other characteristics of the ultimate commercial product. These may take the form of oxidation inhibitors, rust preventives, or anti-foam agents, etc.

Blending of raw gasolines and additives is presently accomplished as a batch process. Using blending value charts based largely on laboratory data, an appropriate mixture of refinery output streams is calculated which will satisfy the target specifications as to octane rating, volatility, sulfur content, etc. The calculations are used for metering into a blending tank the required proportions of straight-run gasoline, catalytic gasoline, etc. depending upon the types of refinery streams available. Calculated proportions of additives such as anti-knock agents, volatility improvers, etc. are also incorporated in the blend. These calculations can only be approximate with respect to octane number. After complete mixing of the components has been accomplished through circulation in large blending tanks, a process which may at times take hours, samples are withdrawn for laboratory tests particularly as to primary values such as octane number. If the target specifications are not met, additional quantities of the components calculated to be necessary to meet the specification are added and circulation in the blending tank is resumed. The process may be repeated several times before a satisfactory finished gasoline is produced. It is quite apparent that a blending and testing method of this type is time-consuming and expensive and ties up valuable blending and storage facilities for extended periods thereby limiting plant output. Slight errors in the use of one product or another or in the incorporation of additives can lead to large economic penalties. In order to be certain that all blends will at least meet the minimum specifications, operators tend to lean to the high side as a safety factor. This procedure may avoid frequent re-blending, adjustment and further testing, which adds significantly to product costs. The testing of the actual finished blend is essential because of the variations in the crude oil, the processing conditions, inaccuracies of the calculations, control systems and measurements. In many instances, the testing procedures are themselves time-consuming and contribute significantly to the inactivation of tank facilities.

The difficulties inherent in the evaluation and test procedures heretofore employed in the art are well illustrated in connection with the formation of finished gasolines meeting predetermined target characteristics as to knock rating or octane number. The standard test methods for evaluating the knock characteristics of motor fuels below 100 octane number as generally commercially employed is set forth in ASTM Manual for Rating Motor Fuels by Motor and Research Methods, published by the American Society for Testing Materials (Fourth Edition 1961), Test Method D35747 being designated the Motor Method and D908-47T as the Research Method. Other meth- 4 ods are also available, such as the Road Method which is conducted under entirely different conditions.

By definition, the ASTM Motor Octane Number of a fuel is given as the whole number nearest the percentage by volume of iso-octane (2,2,4-trimethylpentane equals in a blend with normal heptane (equals 0) that matches the knock characteristics of the fuel when compared by this method. In general outline: The motor octane number of a fuel is determined by comparing its knocking tendency with those for blends of the reference fuels of known octane number at 900 r.p.m. under standard operating conditions. This is done by varying the compression ratio for the sample to obtain the standard knock intensity as defined by a guide curve and as measured by an electronically controlled knockmeter. When the knockmeter reading for the sample is bracketed between those for two reference blends differing by no more than two octane number, the rating of the sample is calculated by interpolation.

Testing procedures include the preparation of a first bracketing reference fuel blend which is expected to approximate the knock rating of the sample under test. A second bracketing reference fuel is similarly prepared and knockmeter readings are taken of the reference fuels and the sample under test after the knockmeter and test engine have been properly adjusted and have reached equilibrium conditions. If sample under test does not fall between the reference fuel ratings, additional fuel blends are prepared and substituted and a predetermined sequence of readings is followed until the readings on two reference fuel blends bracket the sample readings, or until the reading on the sample matches the reading of one of the reference fuel blends. The complexity and time consuming character of the test procedure is in part demonstrated by the prescribed reading requirements of the ASTM Manual as set forth in part in paragraph 14(d) of the Motor Test Method (D357):

The number of readings required for a test and acceptable limits of ratings based on the readings obtained are as follows:

(l) Two readings on the sample and two readings on each bracketing reference fuel constitute a test, provided that the difference in ratings calculated from the first and second series of readings is no greater than 0.3 octane number and the average reading on the test sample is within the specified limits of 55i5 scale divisions.

(2) Three readings on the sample and three readings on each bracketing reference fuel constitute a test, provided that the difference in ratings calculated from the first and second series of readings is no greater than 0.5 octane number, the rating calculated from the third series of readings is between the ratings calculated from the first and second series of readings, and the average reading on the test sample is within the specified limits of 55 i5 scale divisions.

If the difference in ratings calculated from the first and second series of readings is greater than 0.5 octane number, or the rating calculated from the third series of readings is not between the ratings calculated from the first and second series of readings, discard all readings and start over with the test.

Furthermore, this test must be carried on in a specially designed single cylinder test engine of continuously variable compression ratio with suitable accessory equipment and instruments. The specified engine requires meticulous installation adjustment and maintenance. Means are provided for sensing the detonation conditions of the fuel in the cylinder which conditions are then indicated on a specified knockmeter.

The test engine must be operated under critical conditions of adjustment and corrections must be made for variations in environmental conditions under which the tests are carried out. These adjustments and corrections` ture, intake air humidity, barometric pressure, intake air temperature, mixture temperature, fuel air ratio and carbureter venturi. Additional adjustment and corrections must be made in connection with the knockmeter. It is quite apparent that many of these conditions may change during the course of a test posing serious problems as to the validity of the results and their reproducibility and repeatability.

In view of th-e foregoing difficulties inherent in the present procedures, it is an object of this invention to provide a lmethod and means for the evaluation of automotive fuels, particularly with reference to octane rating or number in a simple, expeditious and continuous manner and without delay or interruption of the refining process.

It is an additional object of this invention to provide a method and means of the character indicated whereby a desired correspondence between a reference fuel and the finished refinery product may be readily achieved and any deviation therefrom readily detected and indicated.

A further object of this invention is to provide a method and means which is adapted to detect any deviation of the performance characteristics of a blended motor fuel from the characteristics of a reference fuel and which is capable of automatically initiating corrective action in the blending procedure so as to restore the correspondence between the product and the target fuel particularly with reference to detonation characteristics or octane number.

A still further object of this invention is the provision of a method and means of the character indicated wherein such corrective action for any deviation from the target fuel is automatically initiated and executed in accordance with a predetermined program.

These and other objects will be more clearly disclosed in the following detailed description of the invention, which is to be read in conjunction with the attached figures.

` FIGURE l is a diagrammatic illustration of an arrangement and circuitry for the practice of the present invention; and

FIGURE 2 is a diagrammatic view of an arrangement and circuitry for the practice of another form of the present invention wherein a fuel blend is automatically modified in accordance with a predetermined program in order to duplicate the octane characteristics of a target fuel.

Referring to the drawing, FIGURE 1 illustrates one form of arrangement suitable for practicing the instant invention. Assuming a finished gasoline to be formulated from raw refinery blending stocks A and B to which a requisite amount of TEL (tetraethyl lead) is to lbe added in order to establish a correspondence between detonation or octane characteristics or number of the finished blend and a target or reference fuel. Preliminary calculations are made in order to establish the proportions of the blending stocks and TEL additive which would result in a fuel approximating the octane rating or detonation characteristics of the reference or target fuel. Such calculations can be made upon the basis of available laboratory data and blending charts. Although the procedure and apparatus described in connection with this particular embodiment utilizes only two blending stocks and one additive, it will be understood that the invention is equally applicable when the finished product is to comprise more than this number of type of ingredients.

`Conduits and 12 through which the refinery stocks flow are connected to a source of blending stocks A and B. Valves 14 and l16 are interposed in the fiow paths of conduits 10 and 12 and are subject to adjustment by means of rate of flow controllers 18 and Ztl which are initially set at the required proportions to approximate the target fuel as determined by blending chart and laboratory calculations to which reference has been made. The thus metered flow through conduits 10 and 112 enters the pre- Y liminary blending tank 22 wherein the components are intermixed to form a homogeneous blend. The output of the preliminary blending tank 22 is fed through pumping unit 32 and conduit 24 to the final blending zone or tank 26.

An additive supply tank 28 is provided, which in this particular embodiment, stores a supply of the TEL additive. TEL tank 28 is connected to the final blending zone 26 by means of feed line 30. It will lbe noted that an adjustable valve 38 coupled with a rate of flow controller `4() is interposed in feed line 30` between the additive supply tank 28 and the final blending zone. The finally blended output product flows from blending zone 26 through pumping unit 34 and output conduit 36. This output flow may advantageously be connected to a storage tank not shown. A sampling bleed line `42 draws off a small quantity of the finished blended fuel and feeds the same to the carbureter fuel intake of test engine S to Ibe more particularly herinafter described. A valve 46 is interposed in bleed line y42 adjacent test engine S and is normally in open condition to permit flow of a sampling portion of the finished fuel to said engine fuel intake. A similar conduit 50 leads from reference fuel tank 52 to the fuel intake of test engine S and is provided with a valve 54 interposed in the ow path thereof. Valves 46 and 54 are provided with operating members 48 and 56 respectively which are mechanically coupled to each other by means of a coupling shaft or the like indicated by the broken line 58. Valve 54 is normally closed in operation and the coupling arrangement is `such that as said valve is opened, valve 46y is simultaneously closed so that the fuel supply source to said engine S may be readily transferred from the blended fuel output through bleed line 42 to the reference fuel supply through conduit 50; The purpose of this transfer arrangement will be more particularly hereinafter indicated.

Reference fuel tank I52. comprises a storage supply source for a fuel having the target characteristics, in this case octane number, intended to be duplicated in the finished fuel blend. This target or reference fuel may in such a case comprise a mixture of isooctane and normal heptane in the appropriate proportions for the desired octane number, or it may constitute an actual gasoline fuel with which it is desired to establish an octane number correspondence. In operation, the reference fuel is fed into the fuel intake of test engine R through conduit 60. Test engine `R is identical with test engine S and is located in physical proximity thereto so that both engines are `subjected to and `operated under identical environmental conditions, including ambient temperature, atmospheric humidity and Ibarometric pressure.

For the purposes of the embodiment of the invention herein particularly described, test engines of the type specified in the ASTM manual and specifications above referred to may be advantageously employed. The engine more particularly described in Appendix: I et seq. of the aforesaid manual is designated as the ASTM-CFR engine and has been especially developed for the purpose of determining octane numbers or detonation characteristics of motor fuels. The authorized form of the ASTM-CFR engine is available from Waukesha Motor Co., Waukesha, Wis. Although the invention is particularly described with reference to an engine of this type, it will be understood that other form-s of engine arrangement can be used with varying degrees of advantage, it being understood that in all engine arrangements the combustion, detonation or octane characteristics of a target fuel are to be sensed simultaneously with the corresponding character istics of a reference fuel under identical although not necessarily constant operating and environmental conditions. Thus, the fuels may be fed to pairs of other types of engines of identical design or to two cylinders of a single engine wherein the pistons are coupled to a single shaft. An engine of differing type may be also employed, such as for example, a free piston engine. In each case, the combustion or detonation of the reference fuel and the blended fuel is simultaneously and continuously subjected to almost identical combustion conditions and these conditions are sensed by means of appropriate instrumentation and the instrument outputs or indications are then compared so that any differential therebetween may be detected and the composition of the blended fuel altered to counteract the deviation and restore the equivalence between the fuels, all without interruption of the refinery stream.

Referring again more particularly to the use of engines of the type characterized by the ASTM-CFR engine, it should be pointed out that such engine is of single cylinder type of continuously variable compression ratio with suitable loading and accessory equipment. The appendices to the aforesaid manual also set forth in full detail the nature of the apparatus, reference materials and blending accessories, operation, maintenance, installation and assembly as well as the building and utility requirements. There is also described and provided a detonation pickup for sensing the combustion conditions and knock intensity within the cylinder as well as detonation metering equipment from which knockmeter readings may be taken. The knockmeter readings are of course proportional to the knock intensity of the fuel in the particular combustion chamber being sensed. In the Motor and Research Methods, the knock intensity readings are taken with the principal operating conditions of the test engine being adjusted in accordance with the following table:

ASTM MOTOR AND RESEARCH METHODS OF TESTING ANTI-KNOCK PROPERTIES OF FUELS 1 Varies with compression ratio.

For the purpose of this invention, the pair of test engines may be operated under either of these conditions although the Research Method is preferred. It will be understood however that other operating conditions may be selected so long as they are maintained as close to identical for both engines as possible.

Referring again to the drawings, it will be seen that a portion of the output of the detonation meters 64 and 66 which are provided with knockmeter indicators 68 and 70 respectively is tapped off by means of associated conductors 76 and 78. This output is advantageously fed to amplifiers 72 and 74. The DC control signal output of amplifier 72 is fed to coil 82 of the differential relay indicated generally by the numeral 80 with current flow in the direction indicated by its associated arrow. Similarly, the DC control signal output of amplifier 74 is fed to the coil `84 of said relay 80, current flow being in a direction opposed to the current ow of coil 82 as indicated by the 4associated arrow. It will be apparent that when the knock intensity developed by the fuel in both engines is equal, the current flowing in coils 82 and `84 will also be equal but in opposite directions thereby cancelling any effect on armature -86 which consequently retains its neutral position intermediate the contacts 88 and 90. A change in the knock intensity developed in either engine will however disturb this balance causing the armature to swing and make contact with one or the other of said contact vpoints 88 and 90I in accordance with the associated engine developing the higher knock level. Thus, for example, if the knock intensity developed in the sample fuel engine S should exceed that developed in the reference fuel engine R, the increase of current flow in coil 84 will cause armature 86 to swing to the right and close its circuit with Contact point I88. If the knock level of engine S should however be reduced below that of engine R the circuit with the opposing contact 90 would be closed. Contact points 88 and 90 are each electrically connected to a winding of a forward and backward stepping motor, relay or actuator designated generally by the numeral `92. Said actuator 92 comprises the coil 94 connected in series with contact point 88 and the coil 96 connected in series with contact point 90. The other ends of said coils are connected together at 116 and to a common or ground potential point through interval timing switch 98. Each of coils 94 and 96 is provided with an associated armature and 102 and each armature carries a pawl 104 and 106. Ratchet wheels 108 and 110 are mounted on a common shaft 112 and are each in juxtaposition with a pawl so that when coil 94 is energized it will actuate armature 100, causing pawl 104 to move ratchet wheel 108 and shaft 112 one step or increment in a clockwise or forward direction. Energization of coil 96 on the other hand will result in a movement of the ratchet wheel 110 and shaft 112 one step in the counterclockwise or backward direction. It will be noted that armature 86 of relay 80 is connected to the positive pole of a source of current, such as for example, battery 114, while the negative pole is grounded. As a consequence of this arrangement current will not be supplied to either of coils 94 and 96 when the armature 86 is in its illustrated neutral position. An increase in the knock intensity of the test engine S indicating a reduction in the octane number of the blended fuel will however swing armature 86 to the right completing the circuit from the positive pole of power source 114 to contact point 88, energizing coil 94 and causing shaft 112 to be rotated or advanced through one step. When the knock intensity developed by the fuel in test engine S falls below the level of that developed by the reference fuel in test engine R, indicating an increase in the octane number of the blended fuel, over that of the reference fuel, the closing of the circuit of armature 86 with contact point 90 will cause a corresponding incremental rotation of shaft 112 in the opposing or `backward direction.

Shaft 112 is coupled to the setting member 118 of rate of flow controller 40 so that stepwise rotation of said shaft by the clockwise movement of ratchet wheel 108 will cause an incremental increase in the flow rate of TEL from tank 28 through valve 38 to the final blending zone 26. On the other hand, the rotation of said shaft one step in the opposing direction will decrease the flow rate of TEL by a similar increment. It will be apparent that as one or the other of the coils is energized, the ow of TEL will be increased or decreased by one increment for each period of energization. The foregoing operation of the circuit is predicated upon the assumption that the coil circuits are completed from juncture 116 to ground through the timing switch 98, However, the timing switch 98, which may be of conventional design, serves to periodically open and close the circuit between the common coil connection 116 and ground. It will be apparent that only a single step movement of the actuator 92 can occur during each on interval of the interval timing switch and that no stepping action can occur during the off or circuit interrupting intervals of said switch. Furthermore, no stepping action will occur so long as the differential relay 80 is in balance and the armature is in its neutral position. The purpose of this arrangement will be more particularly hereinafter indicated.

The general operation of the instant continuous monitoring and blending arrangement will now be described. As an initial step, a target or reference fuel is introduced into reference fuel tank S2. The valve operating members 56 and 58 are then operated so that valve 46 is closed and valve 54 is opened. As a consequence of this setting the reference fuel will be fed simultaneously to both test engines. Test engine R thus receives its fuel through conduit 60 and test engine S receives the same fuel through conduit 50. Both engines may be thus initially adjusted for identical performance in every respect and under these conditions identical readings should appear on knockrneters 68 and 70, it being preferred to adjust the engine performance to a standard knock intensity. Under these conditions, the relay 80 will be in balance and armature 86 will be disposed in its central or neutral positionl As previously indicated, a blend of stocks A, B and the additive TEL is calculated from laboratory data to approximate the combustion characteristics of the target or reference fuel. With the proportion of the ingredients thus determined, the flow controllers 18, 20 and 40 are initially set for corresponding flow rates so that the blend in the calculated proportions is preliminarily formed of stocks A and B in preliminary blending tank 22 and the blend is completed with the calculated proportion of TEL in the final blending zone 26. A finished blend approximating the reference fuel thus flows through output conduit 36. A small portion of this output flow is fed through bleed line 42. When test engines R and S as heretofore indicated have reached identical equilibrium conditions, valves 46 and 54 are again actuated by means of the member 58 and the condition of the valves is reversed. Valve 46 being now open permits the bleed sample of the finished blend to flow into sample test engine S while the flow of reference fuel through conduit 50 is cut off. The reference engine R continues to operate on the reference fuel. With test engine S operating with the blended sample, the action of the timing switch 98 is initiated permitting the circuit to be initially completed therethrough. At this point, the armature 86 of differential relay 80 may be in one of three positions depending upon the octane characteristics of the blended sample as cornpared with the reference fuel. lf the octane number of the sample equals that of the test fuel, the knock meter readings will be identical and the armature will remain in its neutral position, In this case, the blending of the gasoline will continue on the basis of the initial proportion of the components until a deviation occurs. If, however, the octane number of the test fuel is lower than that of the reference fuel, the resultant increase in knock intensity will cause the relay armature 86 to move into engagement with contact 88 and as timing switch passes through an on interval, coil 94 of relay 92 will be energized thereby causing the ratchet wheel 108 to step clockwise. This `action rotates the setting member 118 one step forward thereby causing the rate of flow controller 40 to increase the fiow rate of TEL to the final blending zone by one increment. The on interval of the timing switch is of sufficient duration to allow this single incremental adjustment to be made. The timing switch then enters its off interval, breaking the circuit to ground. During this off interval sufiicient time is allowed for thoroughly blending the additional TEL in the blending zone and for the new blend to reach test engine S through the bleed line so that the knock-meter output and indication can reflect the increased octane number of the fuel in the form of reduction in knock intensity. If such reduction in knock intensity is equivalent to the knock intensity developed by the reference fuel indicating similar octane numbers, the armature 86 will return to its balanced or neutral position and as the timer switch again enters the on portion of its cycle, the blending action in the system will continue with the newly established proportion of TEL additive until a deviation occurs. If the single additional increment of TEL is inadequate to restore the balance, the armature will remain in closed circuit with contact point 88 and as the timer switch again enters its on cycle, the relay will again step forward one step to cause correspondng additional incremental increase in the flow of TEL. This process is repeated until the correspondence in knock intensities between the sample and reference fuels is restored. By the same token, if the blend of raw stock emerging from the refinery increases in octane value during the course of the blending operation, a corresponding decrease in the amount of TEL additive flow will be accomplished as the imbalance of the relay 80 closes the circuit with contact 99, thereby resulting in a step backward to decrease the rate of TEL flow by one increment for each cycle of the timer switch that the unbalanced condition continues. The off intervals ofthe timer switch are so adjusted that the change in the proportion of TEL being added is reflected in the performance of test engine S before a succeeding on interval occurs.

It will be apparent, therefore, that the instant 4arrangement provides a convenient and effective means for constantly comparing a reference fuel with a sample of the finished product. Such comparison is made in engines of identical structure and adjustment, and while being subjected to identical environmental variations so that a Valid comparison and correspondence can be maintained between the sample and reference fuels. The arrangement further permits any deviation from said correspondence to be detected and means are provided for automatically adjusting the blend proportions to restore the equivalence between the sample and target fuels. All of the foregoing is accomplished in a continuous manner and without interruption of the output stream of finished product.

It will be understood that although the invention iS here described in connection with a sensing device to detect variations in detonation characteristics, other characteristics -of the reference and blended fuel may be sensed and variations detected and utilized to modify the blend without interrupting the blending stream. A significant feature of the instant invention is that each of the operating cylinders is instrumented so that it will continuously detect deviations between the sample bled from the output fuel and the reference fuel and will translate these deviations into terms of variation of relative flow of one or more of the blending ingredients so that the finished fuel blend will exactly match the reference fuel. This method makes it unnecessary at any time to determine the exct octane number of either fuel in the system and no precise knowledge of the blending characteristics of the blending stocks is required. Both engines are constantly operating under identical conditions and under identical environments of ambient temperature, barometric pressure and humidity and speed, etc. and are simultaneously subject to the same deviations in these factors so that the match in the performance of the fuels is retained. This would not be the case Where the tests and readings are as heretofore run sequentially instead of simultaneously in accordance herewith. If a deviation between the performance of the two engines is suspected to be due to cause other than the differences in the fuels, the S engine can be readily switched to operate on the reference fuel in the manner heretofore indicated by the operation of vales 46 and 54 so that the operation of both engines with the same fuel may be observed and the deviation in performance can thus be immediately detected by -a difference in knockmeter readings. I

Although the invention has heretofore been described with reference to the control of the proportion of a single blending agent or additive which is introduced into the overall blend, the arrangement is also Well adapted for automatically and continuously controlling the proportions of a number of such additives or blending stocks in accordance with a predetermined program in order to continuously maintain a correspondence between the finished output product and a reference fuel insofar as it pertains to such characteristics as octane number. Thuis, FIGURE 2 illustrates a blending tank 200 into which iS introduced the blending ingredients for the nished fuel. Conduits 202 to 210 are connected to suitable sources of blending stocks or additives. Thus, for example, conduit 210 may be connected to a source of the raw base blending stock BBS. Similarly, conduit 208 may be connected to a source of high octane blending stock HOS, while conduit 206 would carry a blending stock LOS of lower octane value. In addition to the fuel blending stocks, the composition of the finished fuel may include an additive, such as tetraethyl lead TEL, supplied through conduit 202 and a tetraethyl lead susceptibility improver TSI fed through conduit 204. Each of the conduits 202 to 208 is provided with an adjustable valve 212 to 218, as well as with a settable rate of flow controller 222 to 228 inclusive. Each of the settable rate of ow controllers is coupled to its associated adjustable valve as heretofore described in connection with valve 38 of the first embodiment of this invention. The rate of flow controllers 222 to 228 are each additionally provided with a settable member 252 to 258 and each of the settable members is coupled for simultaneous movement with its associated wheel and shaft assembly designated 232S to 2388 of the forward and backward stepping actuators designated 232 to 238. The actuators are similar in construction and operation to the actuator designated by the numeral 92 in FIGURE l. It will be apparent that when the righthand coil 232R to 238R of any of said actuators is energized, the ratchet wheel and shaft assembly will be actuated and rotated through one step forward or clockwise there-by setting the rate of flow adjustment of its associated flow controller to increase the rate of tiow. On the other hand, energization of any of the left-hand coils 232L to 238L of any of the actuators 232 to 238 will cause a one-step rotation of the ratchet wheel shaft in a backward or counter clockwise direction, thereby reducing the rate of fiow permitted by its associated rate of iiow controller by a corresponding increment. The actuators are under the control of the programming commutator elements 242 to 248. These commutators are mounted upon a common shaft 272 for simultaneous rotation therewith. Each of the commutators is further provided with conductive sectors 242A to 2488, as well as with upper stationary contacts 242B to 248B and lower stationary contacts 242L to 248L. The lower contacts are connected to a common conductor 274 which is in turn connected to ground through timer switch 98. The upper contacts 242B to 248B are connected to the upper terminals 262 to 268 of the coils of the actuators. The lower terminals of the left- hand coils 232L, 234L and 236L are connected to the conductor 276, while the lower terminals of the right- hand coils 232R, 234R and 236R are connected to the conductor 278. In the case of actuator 238, the lower coil connections are reversed and the right-hand coil 238R thereof is connected to conductor 276, while lefthand coil 238L is connected to the conductor 278. The conductors 276 and 278 are connected in turn to contacts 90 and 88 respectively of the differential relay 80'. The ratchet wheels have, for convenience of illustration, been shown with six teeth, however it should be understood that in actual practice it would be advantageous to provide a larger number of teeth so as to reduce the angle of rotation of the ratchet wheels shafts of all of the actuators for each step.

The test engine monitoring and control arrangement is in all other respects similar to the arrangement heretofore described in connection with FIGURE l and the parts are herein similarly designated with the addition of a prime mark. The description of these parts will therefore not be repeated. It should be noted, however, that the ratchet wheel shaft 112 of the stepping relay 92 is coupled for common rotation With the commutator shaft 272.

As a consequence of the foregoing arrangement, if the knock intensity in test engine S rises above the level of the knock intensity developed by the reference fuel in test engine R', the armature 86 will make contact with 88 thereby advancing ratchet wheel and shaft 112' one step. The commutator discs 242 to 248 will be correspondingly rotated to the same degree. The circuit made with contact 88' will permit current to flow through conductor 278, right-hand coil 232R of actuator 232, contact 242B, the conductive sector 2428 and thence through contact 242L and conductor 274 to ground through the timer switch 98. Coil 232K will thus be energized rotating its associated shaft clockwise and correspondingly increasing the rate of flow through valve 212 as controlled by controller 222. It will be noted that none of the other actuators will be affected by the closure of this circuit in view of the fact that none of the other commutator sectors is in contact position. If, on the other hand, the knock intensity of the fuel test engine S' falls below the intensity developed by the reference fuel in test engine R', indicating that the octane number of the finished blend is above the required value, a reverse action will take place. In this case, the armature 86 will contact 90 thereby completing the circuit through the left-hand coil 232L of actuator 232 and rotating its associated shaft counterclockwise thereby diminishing the ow of TEL through valve 212 by means of the iiow controller 222. It should also be noted that in this situation ratchet wheel 110 of actuator 92', will rotate the commutator shaft 272 in a counterclockwise direction one step. As the commutator shaft is thus rotated stepwise, different sectors come into electrical continuity with thebrushes and only the actuator associated with the commutator sector through which continuity is established will be actuated, the direction of actuation, whether to increase or decrease flow being determined by Ithe left or righthand position of the armature 86. It should however be noted that with reference to actuator 238, the connections of the coils are reversed and since the actuation of the right-hand coil 238R is accomplished through contact this will result in an increase rather than a decrease of flow of LOS through the associated valve 218, while actuation of the left-hand coil 238L by the contact through 88' will cause the controller 238 to be rotated one step counterclockwise causing a diminution of flow through valve 218. Additionally, it should be noted that the conductive sectors 2465 and 248s on commutators 246 and 248 extend through the same arc, so that they will be simultaneously disposed between their associated contacts and actuators 236 and 238 will therefore be simultaneously actuated but in reverse directions.

The relative angular disposition of the conductive sectors of the commutators determines the sequence in which the actuators will be rendered operative to adjust the valves while the length of the arc subtended by each of said sectors determines the duration or number of said operative periods and the number of steps or increments of the associated valve will be adjusted thereby.

The entire arrangement is intended to exemplify the manner in which the instant invention may be used, not only for sensing deviations between finished product and reference fuel characteristic, but will also reflect this deviation into the blending system and initiate corrective action in accordance with a predetermined program for restoring the equivalence between the fuels. For purposes of example, the control program illustrated is intended to operate as follows:

If the fuel being produced falls below the requisite octane rating as determined in the test engines, the following blending sequence will be established. Additional increments of TEL will be introduced into the blending stream by means of the arrangement associated with TEL commutator 242. When the quantity of TEL added to the stream reaches an upper limit, as determined by the conductive sector of said commutator, without the fuel reaching the required octane number, the arrangement associated with the conductive sector of TSI commutaftor 244 controlling the iiow of the TEL susceptibility improver will begin to be incrementally actuated until the proper octane number is reached and the knock intensity balance is again restored. If this is not accomplished by the predetermined limit of TSI added, the continued stepwise rotation of the commutator shaft will render the control arrangement associated with the commutators 246 and 248 operative for valves 216 and 218 controlling the flow of the low and high octane blending stocks LOS and HOS respectively. In this connection, it should be noted that although both commutators rotate in the same direction, the effect on the flow of the high octane 13 blending stock through valves 216 and 218 is effected in opposite directions so that as flow of high octane stock HOS valve 216 increases, a corresponding diminution of the flow of the LOS low octane blending stock through valve 218 is accomplished, so that the total ow remains constant while the proportion of high octane blending stock increases. However, if the octane number of `the resultant fuel blend becomes higher than the reference fuel, as by reason of a change in the character of the blending stocks, the reduced knock intensity in test engine S will cause a reversal of this sequence, thereby reducing the octane number of the blend automatically until the point of equilibrium is reached. In the use of this system, the proportion of the ingredients is generally precalculated from laboratory data, as heretofore indicated, to approximate the reference fuel and corrections will be made in accordance with the aforesaid predetermined programmed sequence to increase or decrease the proportions of the ingredients as required. The entire arrangement operates automatically and continuously monitoring the system, indicating deviations from the reference fuel and correcting the mixture in accordance with a predetermined program. Variations in the characteristics of the blending stocks will thus be automatically compensated for and readily tolerated without changing the quality of the ultimate product. As in the case of the embodiment of the invention described in FIGURE 1, the timing switch determines the period of activation and allows for quiescence of the control system so as to permit the changes in the -blend composition to be reflected in 'the operation of the test engine S. It Will of course be understood that the programming arrangement is given by way of example only and that the system is susceptible of use in connection with any desired sequence and quantity of ingredients. The increments by which the `additions are made may of course vary for the various components.

Moreover, the zero leve of the detonation meter 64 may be offset with respect to that of the detonation meter 66 so that, for equal knock intensities in the engines R and S, the detonation meters 64 and 66 produce unequal outputs and the differential relay 80 is not in balance but is energized to move the armature 86 into engagement with the` contact 88 or 90. The differential relay 80 of course becomes and remains de-energized when the knock intensity detected by the detonation meter 64 differs from the knock intensity detected by the detonation meter 66 by a given constant amount, and the apparatus is adapted to maintain the octane number of the blended fuel product at a level which differs from that of the reference fuel by a given constant amount. For example, a reference fuel having an octane number of 90 may be used to control blending of a fuel product having an octane number of 95.

There has been described and shown preferred embodiments of the invention. It will be apparent, however, that this invention is not limited to these embodiments and that many changes, additions and modifications can be made in connection therewith without departing from the spirit and scope of the invention as herein disclosed and hereinafter claimed.

What is claimed is:

1. The method of controlling a characteristic of a motor fuel blended of a plurality of components during the course of the blending process which method comprises supplying said fuel to an operating combustion chamber for said fuel, said chamber having variable compression ratio,

simultaneously supplying a reference fuel having the desired characteristic to another operating combustion chamber having variable compression ratio under identical combustion conditions,

sensing the desired characteristic of each of said fuels under combustion conditions in order to obtain an indication proportional to the presence of said characteristic in each of said fuels,

comparing the magnitudes of said indications in order to determine the existence of a differential in the magnitude of said characteristic for each of said fuels and obtaining an output proportional to said differential, and

applying said output to the blending apparatus to vary the quantity of at least lone component being introduced into said fuel blend in order to reduce the degree of differential in said characteristic as between said fuels.

2. The method of continuously monitoring and controlling the operation of a motor fuel blending system utilizing a plurality of components in order to produce an output fuel having a detonation rating corresponding to the detonation rating of a target fuel comprising forming a blend of motor fuel components having a detonation rating approximating the detonation characteristics of said target fuel, continuously sampling said blended fuel as it is produced and feeding the sample to an operating combustion chamber having variable compression ratio,

sensing the detonation characteristics of said sample in said combustion chamber toobtain an output signal indicative thereof,

preparing a target fuel having a predetermined detonation rating desired to be duplicated in the output fuel of said blending system, feeding said target fuel to a second combustion chamber having variable compression ratio and sensing the detonation characteristics of said target fuel in order to obtain an output signal indicative thereof, the blended fuel and the target fuel being fed simultaneously to their respective combustion chambers,

comparing the detonation characteristics of said fuels Iby comparing the output signals thus obtained and obtaining a third output signal indicative of the relative detonation characteristics of said fuels, and

applying said third output signal to adjust the quantity of at least one of said components being introduced into said blend in order to reduce the difference between the output product 4of the system and the target fuel.

3. The method according to claim 2 wherein said sample of output fuel and said target fuel are simultaneously fed into the combustion chambers of internal combustion engines of identical construction and operational characteristics.

4. The method according to claim 3 wherein said internal combustion engines are simultaneously operated under the same environmental conditions and subjected to the same variations thereof.

5. In the method of continuously monitoring and controlling a detonation characteristics of a first motor fuel in relation to a similar characteristic of a reference motor fuel, the steps comprising continuously feeding said first fuel to an operating internal combustion engine, simultaneously feeding said reference fuel to an internal combustion engine of identical construction operating under identical environmental conditions,

sensing, by means of first and second .sensing devices, the magnitudes of the detonations produced by each of said fuels in said engines and obtaining first and second outputs from said sensing devices respectively proportional to the magnitudes of the detonations in each of said engines, p

offsetting said second output with respect to said first output by a given constant amount,

controlling a differential relay by said first output and said offset output to de-energize said relay when said first and second outputs differ from each other by said given amount and energize said relay when said first and second outputs fail to differ from each other by said given amount, and

Varying the composition of said rst fuel in accordance with the state of said relay to maintain the detonation characteristic of said first fuel at a level which differs from the similar characteristic of said reference fuel by a given constant amount.

6. The method of continuously monitoring and controlling the operation of a motor fuel blending system utilizing a plurality of components in order to produce an output fuel having a dentonation rating corresponding to the detonation rating of a target fuel comprising forming a blend of motor fuel components having a detonation rating approximating the detonation characteristics of said target fuel,

continuously sampling said blended fuel as it is produced and feeding the sample to an operating combustion chamber,

comparing the detonation characteristics of said fuel by comparing the output signals thus obtained and obtaining a third output signal indicative of the relative detonation characteristics of said fuels, and

Sensing the detonation characteristics of said sample in said combustion chamber to obtain an output signal indicative thereof,

preparing a target fuel having predetermined detonation rating desired to be duplicated in the output fuel of said blending system,

feeding said target fuel to a combustion chamber and sensing the detonation characteristics of said target fuel in order to obtain an output signal indicative thereof, the blended fuel and target fuel being fed simultaneously to their respective combustion chambers,

applying said third output signal to adjust the flow rate of a plurality of components as they are introduced into said blend and in order to reduce the difference in detonation characteristics between the blended output product of this system and the target fuel and to establish a correspondence between the detonation ratings of said fuels.

7. The method according to claim 6 wherein the adjustment of the flow rates of said components in response to the third output signal is effected by a control means in accordance with a predetermined program.

8. The method according to claim 7 wherein the control means adjusts different ones of said flow rates depending upon said third output signal.

9. The method according to claim 6 wherein the flow rates of said components are adjusted periodically by predetermined increments in accordance With said predetermined program.

10. Apparatus for determining the detonation octane I rating of a motor fuel comprising a first internal combustion engine,

a second internal combustion engine of substantially identical construction disposed in close physical proximity to said first engine so as to be subjected to the same conditions of environment and variations thereof,

means for feeding a sample of said motor fuel to one of said engines,

means for feeding a reference fuel to the other of said engines,

means associated with each of said engines for providing an output signal indicative of the octane rating of the fuel fed thereto,

whereby said engines may be simultaneously operated under similar conditions and the octane ratings of said fuels may be compared, and

means for comparing said output signal in a substantially continuous manner.

11. Apparatus for determining the detonation octane rating of a motor fuel comprising a first internal combustion engine,

a second internal combustion engine of substantially identical construction disposed in close physical proximity to said first engine so as to be subjected to the same conditions of environment and variations thereof,

means for feeding a sample of said motor fuel to one of said engines,

means for feeding a reference fuel to the other of said engines,

means associated with each of said engines for producing an output signal indicative of the octane rating of the fuel fed thereto,

whereby said engines may be simultaneously operated under similar conditions and the octan'ce ratings 0f said fuels may be compared, and

means for selectively feeding said reference fuel to both engines in order to determine the equivalence in the performance of both said engines.

12. Apparatus for determining the detonation octane rating of a motor fuel comprising a first internal combustion engine,

a second internal combustion engine of substantially identical construction disposed in close physical proximity to said first engine so as to be subjected to the same conditions of environment and variations thereof,

means for feeding a sample of said motor fuel to one of said engines,

means for feeding a reference fuel to the other of said engines,

means associated with each of said engines for providing an output signal indicative of the octane rating of the fuel fed thereto,

whereby said engine may be simultaneously operated under similar conditions and the octane ratings of said fuels may be compared, and

means for comparing said output signals and deriving a third signal characteristic of the difference between said output signals. l

13. Apparatus according to claim i12 including means for actuating the controls of a fuel blending system in response to said third signal.

14. Apparatus according to claim 12 wherein said third means derives said third signal only at predetermined intervals.

References Cited UNITED STATES PATENTS 2,903,417 9/ 1959 Beaugh et al.

3,238,765 3/1966 Beal.

3,312,102 4/ 1967 Traver.

2,306,372 12/ 1942 Banks 73-35 3,000,812 9/1961 Boyd 73-35 X OTHER REFERENCES Amber et al., Data Control-Special Purpose Computers in the Control of Continuous Processes, from Automatic Control, vol. 7-8, May 1958, pp. 43-48.

Sisk Automation for Gas Blending, Oil and Gas Journal, vol. 58, No. 25, June 1960, pp. 108-111.

ASTM Manual for Rating Motor Fuels by Motor and Research Methods; 1956; pp. 5-7.

Petroleum Refiner; issue of August 1960; Automatic Blending Lives up to Goal, by Bruce Butler; pp. 97-100.

ALAN COHAN, Primary Examiner.

U.S. Cl. X.R. 73-35; 137-88 PO-050 UNITED STATES PATENT OFFICE 569 CERTIFICATE 0F CGRRECTION Patent No. BILLS-nop Dated June 9).; 1969 Inventor(s) Wvne A. Howard It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, at line 13, for "particularly" read --specifically--g in the table beginning at line 32, for "$90" read 900. Column l0, at line 35, for "exct read exact-- at line 50, for "vales" read -va.lves. Column l, line 55, for "characteristics" read "characteristic". Column l5, line ll, for "dentonation" read detonation.

SIGNED AND SEALED MAH 101970 (SEAL) Attest:

Edward M. Fletcher, Ir.

. WILLIAM E. PSGHUYIER, JR

Attesung Offlcer Comissioner of Patents

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