US2971370A - Gasoline-rejecting mechanism for continuous flash point instrument - Google Patents

Description

Feb- 14,1961 B. JACOBS ETAL 2,971,370

R. GASOLINE-REJECTING MECHANISM FOR CONTINUOUS FLASH POINT INSTRUMENT Filed D60. l0, 1957 '3 Sheets-Sheet l @fm/veeg R. B. JACOBS ET AL Feb. 14, 1961 2,971,370 GAsoLINE-REJECTING MECHANISM FOR CONTINUOUS FLASH POINT INSTRUMENT 3 Sheets-Sheet 2 Filed DSC. l0, 1957 INVENTORS. @WEl/COS g lauff- Feb 14, 1961 R. B. JACOBS ETAL 2,971,370

GAsomNE-REJECTTNG MEcHANTsM FOR coNTINUoUs FLASH POINT INSTRUMENT Filed Dec. 10, 1957 SSheets-Sheet 3 d MO f@ PP//VPY A POI/VEB C/,QCU/T TE S T/ /V G COMPU/VEN 75 fwn/464:44

United States Patent Olice Patented Feb. 14, 1961 GASOLINE-REJECTING MECHANISM FOR CON- TINUUUS FLASH POINT INSTRUMENT Robert B. Jacobs, Homewood, and Dominic Daniel Lo Giurato, Oaklawn, Ill., assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana Filed Dec. 10, 1957, Ser. No. 701,800

Claims. (Cl. 73--36) This invention relates to the automatic determination of ilash points of liquids. More particularly the invention relates to a system for operating a llash point monitor on a products pipeline transporting both gasolines and burning oils.

In the marketing and transporting of hydrocarbon products such as burning oils, it is important to avoid the delivery of more volatile constituents. For example, it is important when a quantity of hydrocarbon liquid has been designated as fuel oil, that there be no inadvertent substitution of a more volatile material such as gasoline; accordingly, a rapid means for ascertaining whether a particular sample comes Within the prescribed minimum flash point specifications is desired.

In one such system a heated liquid stream is passed into an enclosed cup provided with an overflow. A preheated stream of air is also fed into the cup, comprising a tlash chamber, at a constant rate and uniform pressure. The oil and air are comingled and the combined stream exposed within the ilash chamber to an ignition means in the vapor space above the liquid. When the sample temperature, as controlled by an electric heater, is high enough to ilash the vapors are ignited by the sparking means and the occurrence of a llash actuates indicators, relays for controlling delivery valves for turning a product into tankage, and the like.

Thus a pipeline in Which burning oils are flowing can be monitored and when a burning oil has a satisfactory llash point it may be safely turned into tankage containing burning oils. Such operations are generally satisfactory but it is recognized that when such burning oils are shipped next to gasoline there is considerable contamination in the interface zone. It is also recognized that product pipelines are used, a large percentage of the time, for the shipment of gasolines which are of low llash point. and oil which no measurement is' desired in the pipeline stage of marketing. Therefore, it is desired, when operating a tlash point instrument continuously on a product pipeline, to make a test only when burning oils are passing the check point.

It is, therefore, an object of this invention to provide a system for discriminating between fluids flowing in a pipeline so that the desired measurements of a specification can be made automatically on only the fluid of interest. It is a further object of the invention to provide a system adapted for use with an automatic ilash point tester. Another object of the invention is to provide a mechanism adapted to reject gasoline from a llash point tester. An additional object of the invention is to provide a system for automatically turning olf the operation of a ilash point mechanism when gasoline is flowing in the pipeline and turning on the mechanism when burning oil is present.

A highly Volatile material, such as gasoline, could conceivably pass through an instrument of this type without igniting, Vthus giving an incorrect indication of the ilash point of the sampled product. Accordingly another important object of the invention is to provide a gasoline-rejecting mechanism which corrects this erroneous indication by detecting the presence of gasoline in the system.

In the interface zones the concentration of gasoline in burning oils will vary. Therefore, it is an object of this invention to provide a mechanism which cuts out the llash point instrument when the gasoline concentration exceeds a predetermined value and resumes the ilash point testing when the gasoline concentration again diminishes below the selected concentration.

Another object of the invention is to provide an apparatus which is rugged and compact and which can operate unattended for long periods of time. It is also an object of the invention to provide for a llushing of the ilash point instrument after it has tested gasoline so that the residual gasoline does not contaminate the burning oils which follow and erroneously indicate a lower llash point. A more specific object of the invention is to provide a system for turning off the mechanism for llash testing when gasoline is flowing through it since the repeated explosion of the gasoline-air mixture would otherwise result in unnecessary wear and tear on the instrument. AThese and other objects of the invention will become apparent as the description thereof proceeds.

Briefly, according to the invention we provide a system wherein a sample liquid is preheated, pumped through a fixed resistance such as a capillary tube. If the sample is a burning oil, it develops a sullicient pressure drop across the lixed resistance to actuate a pressure-switch on the sample line between the preheater and the fixed resistance.

When the pressure switch is actuated it supplies electrical power to the testing components and to the indicating circuits of the ilash tester which. permits the instrument to perform a continuous test on the sample.

On the other hand, if the sample is gasoline, it will not develop a sufficient pressure drop across the lixed resistance, the pressure switch is not actuated, and the instrument rejects the sample and no test is made.

The flash point instrument may be an essentially go, no-go testing apparatus operated on a continuous basis. The instrument does not measure tlash point as such but indicates whether the ilash point of a given sample is above or below a selected specification value.

Further details and advantages of the invention will be described by reference to the accompanying drawings wherein:

Figure 1 schematically illustrates an embodiment of the invention wherein the fluid not of interest is rejected;

Figure 2 is a schematic llow diagram of a system wherein the presence of a lluid not of interest shuts off the testing apparatus without interrupting flow; and

Figure 3 illustrates' in more detail an apparatus of the type contemplated in Figure 2.

Referring to Figure 1, the rejecting mechanism comprises a pressure switch 10 on sample feed line 11, a fixed fluid resistance 12, and a preheat coil 13. The preheat coil 13 and the fixed resistance 12 are mintained within a temperature controlled chamber or block 14. The size of resistance 12 'and the actuating point of the pressure switch 10 are adjusted so that the switch 10 is open when burning oils are llowing in line 11 and is closed when gasolines are flowing through sample line 11. This discrimination between gasoline on the one hand and burning oils on the other is possible because of the dilerences in viscosities betwen the two types of materials under controlled temperature and feed rate conditions.

When the switch 10 is in the open position, it permits operation of the flash instrument. When the switch 10 is in the closed position, it actuates two solenoid valves 16 and 17, valve 16 opening a bypass 1S to the drain 19,

thus providing a means whereby the sample no longer flows through the sample cup of the flash tester but goes directly to the waste line 19. The 4other solenoid valve 17 provides for a continuous flush of air from air supply line V20, flushing air line 21-discharging into the llash cup 22 of the tester, thus keeping it free from gasoline vapors and in condition to accurately measure the flash point of a burning oil when it is flowing in sample line 11.

As a specific example, heater oil flowing lat 60 cc./ min. `developed 27 psi. through a resistance 12 of 3 ft. of 0.031 inch inner diameter tubing and a mixture of 40% gasoline plus 60% furnace oil at the vsame flow rate developed 21 p.s.i. Therefore, when the pressure switch was set to actuate at 24 p.s.i., all materials with viscosities lower than the heater oil were rejected, including the 40% gasoline, 60% furnace oil mixture.

In the system illustrated by Figure 1, the flash tester makes no test when a sample is automatically rejected. Another embodiment of the invention utilizing the rejection device for cutting out the control and indicating circuits associated with the flash tester is shown in Figures 2 and 3,

Referring to Figure 2, the sample is introduced into the system by line 24 and passes pulsation damper 25 before lentering the preheater coil 29 maintained in the preheater vzone 26. If the sample is a burning oil sufficient pressure drop is developed across the iixed fluid resistance 30 to close the pressure switch 10, thereby supplying electrical power to the testing components and control circuit 49 which applies the current to the electrodes 55 and 56 and to the indicating circuit 54 associated with differential thermocouple 57 having junction 57a of high mass and 57b of relatively low mass. During the test air is introduced by line 43 and vapors land air 4are withdrawn from the fiash chamber 41 through vent 44 whereas excess liquid is discarded through overflow drain 42.

In Figure 3, further details of our apparatus are shown indicating a ilter 23 on feed line 24, which is 1/s inch outer diameter by .085 inch inner diameter copper tubing; pulsation damper 25 made of a diaphnagm within an enclosure is connected to line 24; a preheater block 26 comprises a copper cylinder approximately 2 inches in diameter by 6 inches high, a 50 watt cartridge heater 27 and a temperature-controlling thermostat 28.

A preheater ooil 29 comprising Ia section of copper tubing similar to feed line 24 is about 3 ft. long. A continuation of the same tubing extends to the fixed resistance capillary 30. A pressure switch 31 containing a diaphragm 32 land two pressure-actuated switches, a high pressure cut-out switch 33 and a low pressure cut-out switch 34, is connected to line 35 intermediate the preheater coil 29 and the resistance 30.

The fixed resistance capillary 30 is made from a 9 inch length of .035 inch inner diameter copper tubing and discharges into flash tester inlet line 36 also made of the same tubing as lines 24 and 35. A positive displacement pump 37 takes liquid sample from manifold line 38 and discharges the sample through filter 23 at a constant pulsating rate of 60 cc./rnin. into line 24 where the pulsating flow is dampened by the pulsation damper 25.

As the sample passes through the preheater coil 29 in the preheater Vblock 26, its temperature is raised to approximately 117 F. and flows through line 35 into the fixed resistance capillary 30. The line 36 carries the sample discharged from the capillary 30 to the main block 39 ofthe flash tester instrument and into the flash chamber 41. The sample is then discarded from the chamber 41 through the drain line 42. Air is supplied to the chamber 41 by 'air supply line 43 and it flows from the chamber 41, together with any hydrocarbon vapors and ignition products through the vent line 44 which in turn discharges through the drain line 42.

Power is supplied to the instrument at points 45 and 46 by an automatic phlone dial relay system (not shown). This energizes the primary power circuit 5,0 which includes the preheater cartridge heater 27, the preheater thermostat 28, the main block heater 47, the main block thermostat 48, the air pressure switch 51, and the inverse thermostat 52 which supplies power to tlie air pressure switch 51 when the main block 39 is sufiiciently heated. By this time all other heated components will have reached equilibrium.

If there is proper air pressure on line 43, the air pressure switch 51 will close and supply power to the line pressure switch 31. During the warm-up period, the pos1- tive diaplacement pump 37 pumps liquid sample through the fiash tester.

When liquid sample is passing through capillary 30, a pressure drop proportional to the viscosity of the sample occurs across it. If the pressure drop is larger than 7 p.s.i., which is the actuating point of the low pressure switch 34, in the line pressure switch 31, the switch 34 will be actuated or closed by diaphragm 32 and will carry power to the testing components control circuit 49, thus allowing the flash tester 40 to make a test. If the pressure drop is less than 7 p.s.i., no power will be supplied to the control circuit 49 and no test will be m-ade.

For example, when gasoline is -fed into line 24, by pump 37 from manifold line 38, a pressure drop of about 5 p.s.i. occurs across the capillary 30l and no test is made. However, when kerosene ows through the system, a pressure drop of 8 p.s.i. is observed and switch 34 is actuated andV a ash test is made on the kerosene.

It is an additional safety feature of the apparatus that, should capillary 30 become plugged, the pressure in line 35 will rise above 15 p.s.i. and actuate switch 33 and remove power from control circuit 49.

In a typical installation, the apparatus is placed adjacent a pipeline to be monitored. The apparatus ordinarily being arranged Within a housing (not shown) provided with a space heater and thermostat whichoperate continuously. To operate the apparatus, it is lonly necessary to connect the utilities, the sample line, and the drain. The operation is completely automatic and the information on iiash point can be used to automatically control the switching of normally closed valve 38C to permit flow to tankage via line 33b or to pipeline fiow in line 38a depending upon the signal from control circuit 49.

In each of the illustrated embodiments of the invention the ash detector is of the differential thermocouple type.

As the temperature rises in the flash chamber, the airvapor mixture therein `becomes richer and richer until it eventually reaches the lower explosive limit of the sample at which time it is ignited by the spark from electrodes 55 and 56 and the minor explosion occurs inside the test chamber. This explosion is detected by the differential thermocouple S7, one junction 57b having a small mass and thus a small heat capacity, the other junction 57a having a large mass and thus a large heat capacity.

For gradual temperature changes, such as the gradual increase in temperature of the air-vapor mixture during the heating period prior to the explosion, the two junctions 57a and 57h remain at approximately the same temperature but for sudden changes, such as the temperature change of the gases during the minor explosion, the temperature of the smaller junction 57b rises considerably above that of the larger junction 57a. This temperature difference furnishes a smal-l voltage from the differential thermocouple 57 and this voltage is applied to the ilash indicating circuit 54 to actuate suitable relay means (not shown).

The voltage furnished by the differential thermocouple 57 corresponds to a temperature difference between junctions of about 200 F. and the sensitive relay in the circuit 54 is designed to operate on a difference of about 50 F.

The signal from the indicating circuit 54 is fed to the testing components control circuit 49. A signal from control circuit 49 in turn operates the solenoid actuated iilling valve 38e and delivery to tankage is interrupted when a flash is detected.

Although our invention has been described in terms of preferred embodiments of the apparatus wherein tiash point determinations are to be made, it should be understood that these are by way of illustration and that the invention is not necessarily limited thereto. Other systems for detecting the occurrence of a flash may be used and other test systems may be substituted for the flash point determination device. Accordingly, alternative operating techniques and apparatus components will become apparent to those skilled in the art and accordingly, modiiications in the apparatus and in the mode of using the apparatus are contemplated without departing from the spirit of the invention.

What we claim is:

1. A ilash point apparatus for use in continuously monitoring a iirst fluid flowing batch-wise with at least one second uid in a pipeline, sample line means connected to said pipeline, flash point apparatus on said sample line, said flash point apparatus including a flash chamber, ignition means within said chamber, means for supplying air to said chamber, means for heating said chamber to a selected temperature correlated with the ash point specification of the rst iluid, and means responsive to the occurrence of a flash in said chamber, discriminating means interposed said pipeline and said flash point apparatus on said sample line, said discriminating means being adapted to permit the making of a ash point determination only when the concentration of the second iluid does not exceed a predetermined value and comprising preheater means on said sample line, ilow resistance means on said sample line downstream of said preheater means, and pressure responsive switch means on said sample line intermediate said preheater and said ow resistance, said switch means being adapted to cut out the Hash point apparatus when the concentration of said second uid exceeds the predetermined value and cut in the flash point apparatus when the second iluid concentration again diminishes below said predetermined value.

2. The apparatus of claim 1 wherein said switch means cuts out the ash point apparatus by controlling the actuation of the ignition means and the means responsive to the occurrence of the flash.

3. The apparatus of claim 1 wherein the said pressure responsive switch means cuts out the flash point apparatus by actuating a valve means on said sample line means for diverting ow in said sample line means away from said ilash chamber.

4. In a ilash point apparatus for indicating whether the flash point of a ilowing sample meets a selected specification, the apparatus which includes flash testing means comprising a llash chamber, ignition means within said chamber, sample line means for flowing a liquid stream into said chamber, means for supplying a stream of air to said chamber, means for heating the sample liquid to a selected temperature, means responsive to the occurrence of a ash in said flash chamber, the improvement which comprises sample discriminating means on said sample line means, said sample diriminating means including sample preheater means, tixed ow resistance means downstream of said preheater means, and pressure responsive switch means: on said line between said preheater means and said flow resistance means, said switch means controlling the operation of said ilash testing means.

5. In a flash point apparatus adapted to monitor a uid of interest llowing through a pipeline the improvement which includes a system for discriminating between two or more uids flowing in succession in a pipeline so that an automatic ilash determination can be made on only the uid of interest, said system including means for preheating a sample liquid, a conduit system, a iluid flow resistance in said conduit system, said resistance developing a pressure drop which is characteristic of the iluid of interest, and a pressure switch in said conduit system between said preheater and said fixed resistance, said pressure switch being adapted to control the tiash point determination whereby a flash point test is made only on the fluid of interest.

6. The apparatus of claim 5 which includes valve means on said conduit system, said valve means being solenoid-operated, the power to which is controlled by said pressure responsive switch.

7. The apparatus of claim S wherein said means responsive to the occurrence of a flash and includes an ,ignition means controlled by said pressure responsive switch means.

8. In apparatus for delivering only a selected iirst fluid from a pipeline through which first and second fluids flow, the improvement of controlling the delivery of only the selected rst iluid in response to the measurement of a quality specification of said irst fluid, diversion line means for delivery from said pipeline, sample line means continuously diverting a small representative portion of the uids ilowing in said pipeline, testing means on said sample line for determining whether the lluid liowing therethrough meets the specication being measured, and huid-discriminating means on said sample line between said pipeline and said testing means, and means responsive to said specification testing means for actuating said diversion line means when a sample meets the specification in question, said Huid-discriminating means including preheater means, fluid flow resistance means, and pressure responsive switch means actuated by the passage of the selected iirst liuid through the how resistance to control the testing means.

9. The apparatus of claim 8 wherein said switch means controls the ow of the sample fluid to the testing means.

10. The apparatus of claim 8 wherein said testing means comprises flash point apparatus having an ignition means and ilash responsive means and said switch means controls the power lto the said ignition and flash responsive means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,140,735 Clarke Dec. 20, 1938 2,392,662 Griesheimer Jan. 8, 1943 2,746,286 Greanias et a1. May 22, 1956 2,834,200 Rhodes et al. May 13, 1958

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