US3440863A - Continuous flash point recording - Google Patents

Continuous flash point recording Download PDF

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Publication number
US3440863A
US3440863A US472576A US3440863DA US3440863A US 3440863 A US3440863 A US 3440863A US 472576 A US472576 A US 472576A US 3440863D A US3440863D A US 3440863DA US 3440863 A US3440863 A US 3440863A
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United States
Prior art keywords
liquid
flash
chamber
temperature
flash point
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Expired - Lifetime
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US472576A
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English (en)
Inventor
Leslie D Livingston
John K Rowland
George T F Crespin
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Shell USA Inc
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Shell Oil Co
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/50—Investigating or analyzing materials by the use of thermal means by investigating flash-point; by investigating explosibility
    • G01N25/52—Investigating or analyzing materials by the use of thermal means by investigating flash-point; by investigating explosibility by determining flash-point of liquids

Definitions

  • the invention relates to an instrument for determining the flash point of a liquid, more particularly, to an instrument for determining and recording the flash point of a continuous stream of liquid. Further, the invention concerns a method of controlling a process such as a distillation, dewaxing, an extraction or a deasphalting process, on the basis of the flash point of a product of this process.
  • One instrument of the prior art utilizes in combination a flash chamber and means exterior of said chamber for heating a stream of liquid and for heating an oxygen-containing gas (e.g., air).
  • the heated liquid and gas are introduced into the flash chamber, and a pool of the liquid is maintained at a constant or substantially constant level in the said chamber.
  • An ignition spark is supplied to the flash chamber above the level of the pool in the presence of the gas.
  • the temperature of the liquid pool in the flash chamber is measured, and the occurrence of a flash within the chamber is detected.
  • the temperature of the liquid may be measured automatically upon the occurrence of a flash in the vapor space of the flash chamber.
  • the heating means is designed to progressively increase the temperature of the liquid supplied to the flash chamber with the heating means being regulated by the said flash detecting means.
  • the instrument will thus maintain the temperature of the liquid at least substantially at the level at which flashing occurs.
  • the flash point temperature of the stream of liquid may be continually measured in a relatively rapidly repetitive way.
  • the instrument described above is used for measuring the flash points of light petroleum products, such as gasoline and kerosene, with flash points up to about 85 C. It has been found, however, that the known instrument is unsuitable for testing liquids with flash points higher than the said limit, since irregular flashing occurs in experiments carried out with liquids with such higher flash point temperatures.
  • the present invention provides an instrument for measuring the flash point of liquids that is equipped with im- 3,440,863 Patented Apr. 29, 1969 proved heating means for the vapors generated and/or for the liquid to be tested.
  • the instrument is provided with a separate heating means for the vapor space of the flash or vapor chamber.
  • the vapor chamber is adjacent to and preferably situated above the liquid chamber.
  • the liquid and vapor chambers together form the flash chamber and usually a splash shield (e.g., a tray with a bubble cap) is fixed between the two chambers.
  • control means responsive to flashing detected by the flash detector are utilized for temporarily decreasing or switching off the separate heating of the vapor chamber. The decrease or the switching off may be effected for a predetermined time interval, which may be related (but not necessarily so) to the spark time interval.
  • the second of the above features concerns the application of a preheater for the incoming liquid stream in combination with control means dependent on the temperature difference across the aforesaid main heating means of the liquid (or liquid and gas, if they are heated together in the main heater).
  • the temperature difference is maintained at a constant or at least substantially constant value. In the preferred embodiment of the instrument both features are present simultaneously.
  • the liquid and the gas streams are heated in a combined heater (saturator) which is close to and integral with the flash chamber.
  • a combined heater saturator
  • the saturator which is usually heated inside, e.g., by means of a cartridge heater, may consist of a helical channel that discharges into the liquid chamber.
  • the known instrument for determining the flash point of a liquid is equipped with a. heater arranged for progressively increasing the temperature of the liquid.
  • a control means regulated by the flash detector maintains the temperature of the liquid at least substantially at the level at which flashing occurs.
  • the heating is increased progressively as long as no flashing occurs; as soon as flashing is detected the heating is progressively decreased during the flashing period; when flashing stops the heating is again progressively increased.
  • a new device consisting of a housing with a diaphragm, preferably formed of tetrafluoroethylene resin known as Teflon.
  • the diaphragm is subject on one side to the vapor space pressure and on the other to atmospheric pressure.
  • the occurrence of a pressure wave generated by a flash results in a displacement of the diaphragm, which is utilized, e.g., mechanically optically or electrically, to generate a signal that may be indicated, recorded and/0r transformed into a control signal.
  • the other side of the diaphragm affects an electrical circuit, e.g., :by actuating a switch.
  • the chamber containing the diaphragm is connected to the vapor space by a short line. The use of a short line prevents the diaphragm from being fouled by the products of combustion produced in the vapor space.
  • the instrument measuring the flash point temperature may be used for controlling a process on the basis of the flash point of a product of that process.
  • a sample stream of the said product is fed to the instrument, the flash point temperature is measured and a signal corresponding to the measured temperature is supplied to a controller.
  • the output signal of the controller is used to control the process in such a Way as to make the product of the process assume at least approximately a constant flash point.
  • the control may be effected to prevent the products flash point from exceeding a given limit.
  • Such a control may, inter alia, be applied in propane deasphalting or asphalt-containing residues and in the extraction, for example, the furfurol extraction, or in the solvent dewaxing of lubricating oils.
  • the solvents used have to be removed from the several phases in these processes and the flash point of these phases is a sensitive indication of the degree of solvent removal.
  • the stripping of the solvents in the phases may be controlled by means of the present instrument in the way set forth above.
  • FIGURE 1 is an elevation partly in section of one embodiment of this invention.
  • FIGURE 2 is a schematic drawing of a second embodiment of this invention.
  • FIGURE 3 is a graph of the measured temperature and the operation of the heater with respect to time.
  • the instrument is built up mainly of two parts: a flash chamber 1, and a heater (saturator) 2 which is close to and integral with the flash chamber.
  • the flash chamber consists of a liquid chamber 3 and a vapor chamber 4 situated immediately above the liquid chamber.
  • the vapor chamber is provided with spark ignition means 5 connected at 6 to a source of high tension voltage or spark generator (not shown).
  • the flash chamber is also provided with an outlet for vapor 7.
  • a spark is produced at regular time intervals, e.g. every seconds. Usually a direct current spark is used, but an alternating current spark may be applied instead.
  • the vapor chamber is also connected via a short line 8 with a flash detector 9.
  • the flash detector 9 consists essentially of a diaphragm 10 acting upon an electric switch 1].
  • the diaphragm is preferably made of tetrafluoroethylene known as Teflon and may have a diameter of about 5 inches. Shock waves generated by a flash in the vapor chamber are detected by the diaphragm which thereupon actuates the switch 11.
  • the switch 11 may be either opened or closed by the movement of the diaphrgam 10.
  • the feed inlet of the liquid to be tested is at 12.
  • Normally liquid is supplied at a fixed or metered rate by means of a constant displacement pump or a metering orifice disposed in the inlet 12.
  • a metered flow of the oxygen-containing gas, normally air, is introduced at 13 and mixed with the liquid before heating in the saturator 2 takes. place.
  • the rate of flow of the liquid (oil) was about 4.5 liters per hour and the rate of flow of the oxygen-containing gas (air) was about 14 liters per hour.
  • these flow rates may generally vary between wide limits, depending on the nature of the liquid to be tested and of the oxygen-containing gas used.
  • the saturator is built up of a cartridge heater 14 situated inside a helical channel 15.
  • the heater receives its electrical supply through terminals 16.
  • the heated liquid forms a pool in the liquid chamber 3.
  • a constant level of the pool is maintained by providing the liquid outlet through liquid overflow pipe 19 with a weir 20
  • a temperature measuring means 21, for example, a thermocouple, is located in the saturator outlet 17 to measure the temperature of the test liquid under test conditions. The measured temperature may be displayed on a recorder 22.
  • the vapor chamber 4 is provided with separate heating means 23.
  • the separate heating means 23 may be a collar heater with terminals 24 for connection with an electrical power supply.
  • the heat supplied to the heater 23 is decreased, preferably switched off, as soon as flashing occurs. When flashing stops the heat input to the heater is restored.
  • a preheater for the incoming liquid stream is provided in line 12; this preheater is schematically indicated at 25 and its construction may be similar to that of the saturator, i.e., consist mainly of a housing, a helical channel for the liquid and a cartridge heater mounted inside the helical channel.
  • a temperature measuring means 27 for example, a thermocouple, is disposed at the inlet to the saturator unit 2.
  • the measured temperatures at 21 and 27 are supplied to a controller 26.
  • the controller 26 controls the heat input to the preheater 25 to maintain a constant temperature differential across the saturator unit 2.
  • the value of the temperature differential across the saturator unit is set by means of the set point 28 on the controller 26. Normally a 15 to 30 degree Centigrade temperature differential is satisfactory.
  • the complete instrument is usually housed in an explosion-proof box, that may, but need not, be temperaturecontrolled.
  • the instrument so far described may be used for testing the flash point of liquids, e.g. for indicating whether or not a liquid surpasses a certain predetermined flash point temperature.
  • the heating of the saturator may be controlled (not shown in the figure) in this case in such a way that the liquid-gas mixture delivered to the flash chamber is continuously maintained at the said predetermined temperature.
  • the means for heating the liquid are arranged for progressively increasing the temperature of the liquid supplied to the liquid chamber and additional control means for said heating means are provided to maintain the temperature of the liquid at least substantially at the level at which flashing occurs.
  • the power to cartridge heater 14 is decreased or increased, depending on whether the vapor in the vapor chamber ignites or not.
  • FIGURES 2 and 3 The complete control system of the preferred embodiment of the instrument capable of measuring the flash point temperature is illustrated in FIGURES 2 and 3.
  • the numerical indications correspond to those used in FIGURE 1 although some elements are shown in a simplified form.
  • the system shown in FIGURE 2 includes all of the elements shown in FIGURE 1 and additional controls for the cartridge heater 14, collar heater 23 and spark 5.
  • the terminal 6 of the spark 5 is connected to a direct current spank source 29.
  • the direct current spark source 29 is controlled by means of a motor 30 that is adjusted to cause the source 29 to energize the spark 5 once every 10 seconds.
  • the cartridge heater 14 is controlled by a variable transformer 31 driven by a reversible motor 32.
  • the motor 32 should be connected to the variable transformer through a gear train that provides a slow rotation of the transformer control. A suitable speed would be in the range of one revolution every forty minutes.
  • the motor should be adjusted to normally rotate the transformer control to increase the voltage supplied to the cartridge heater.
  • the collar heater 23 is connected to a source of power by means of normally closed contacts on relay 33.
  • the relay 33 is energized by the flash detector 9 to open the normally closed contact and remains energized for a period of 9 seconds.
  • the 9-second period is controlled by a switch 34 that is actuated by the motor 30.
  • the motor 30 closes the switch 34 at the same time that it actuates the spark source 29.
  • the relay 33 also contains a second set of contacts that close when the relay is energized. The second set of contacts serve to reverse the direction of rotation of the motor 32. When the motor 32 reverses the voltage supplied to the cartridge heater 14 will be reduced.
  • a direct current spark is generated in the vapor chamber 4 once every seconds by means of a spark generator 29 connected to terminal 6. If the test liquid is below its flash point, no ignition occurs and the heat input to the cartridge heater 14 is gradually increased by the variable transformer 31. As soon as flashing starts the flash detector 9 energizes a relay 33. This relay is held in the energized state for a period of 9 seconds, determined by a switch 34 actuated by the same motor 30 which initiates the spark generator. The relay 33 carries contacts which for the said period of 9 seconds reverse the variable transformer drive motor 32 and switch off the heating of the collar heater 23. After the period of 9 seconds the relay is de-energized, the collar heater is switched on and the variac drive is reversed. One second later a new spark is generated and, if another flash should occur, the process just described will be repeated.
  • FIGURE 3 shows a horizontal time scale 35 running from 0-140 seconds. It is assumed that the first six and the last two sparks give rise to flashing (indicated by short vertical lines).
  • the two lines under the time scale represent schematically the condition of the vapor chamber collar heater 23 (upper line 36) and of the cartridge heater 14 (lower line 37) respectively.
  • the heater 23 is either in the on or in the off position. From the 60th to the 130th seconds the heater is continuously on.
  • Line 37 shows the movement of the variable transformer drive motor; from the start to the 60th second the variac output voltage is decreased continuously with the exception of the one-second periods at the end of each time interval of 10 seconds between two successive sparks.
  • the temperature as measured by the thermocouple 21 and recorded on the recorder 22 will be the flash point of the liquid being tested. By continuously obtaining a large number of flash points of the liquid and the average temperature can be determined. The average temperature will acurately reflect the true flash point of the liquid.
  • An instrument for measuring the flash point of a liquid comprising:
  • a flash chamber including a liquid chamber and a vapor chamber adjacent to and situated above the liquid chamber;
  • flash detecting means in communication with the flash chamber for detecting a flash occurring within the flash chamber
  • aliquid supply means for said flash chamber an oxygen containing gas supply means, said oxygen supply means communicating vvith said liquid supply means to supply an oxygen liquid mixture to said flash chamber;
  • a preheater means at least said liquid supply means passing through said preheater;
  • first temperature measuring means being disposed to measure the temperature of the oxygen liquid mixture at the inlet to said first heating means
  • flow control means communicating with said liquid chamber for maintaining a constant liquid level in said liquid chamber
  • thermo measuring means being disposed to measure the temperature of the liquid in said liquid chamber
  • first and second temperature measuring means being coupled to said first control means, said first control means being coupled to said preheater to maintain a constant temperature rise across said first heating means;
  • control means being coupled to said flash detecting means, and said first and second heating means, said control means being responsive to said flash detecting means to control said first and second heating means to maintain the liquid in said liquid chamber and the vapor in said vapor chamber at substantially the flash temperature of the liquid.

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  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Immunology (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)
  • Devices For Use In Laboratory Experiments (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
US472576A 1964-08-07 1965-07-16 Continuous flash point recording Expired - Lifetime US3440863A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB32358/64A GB1068375A (en) 1964-08-07 1964-08-07 Flash point testing or measuring instrument and method

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US3440863A true US3440863A (en) 1969-04-29

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US (1) US3440863A (enrdf_load_stackoverflow)
DE (1) DE1623002A1 (enrdf_load_stackoverflow)
GB (1) GB1068375A (enrdf_load_stackoverflow)
NL (1) NL6510165A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3748894A (en) * 1972-06-15 1973-07-31 Texaco Inc Means and method for an on-line determination of the flash point of lube oil fractions
US4831559A (en) * 1986-07-25 1989-05-16 Phillips Petroleum Company Method and apparatus for periodically determining the flash point of a flammable liquid
EP0305206A3 (en) * 1987-08-27 1989-12-06 Nippon Oil Co., Ltd. Apparatus for measuring flash point of petroleum intermediate fraction and method for controlling flash point

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111766269B (zh) * 2020-08-11 2022-11-04 合肥国轩高科动力能源有限公司 一种锂离子电池电解液闭口闪点的自动测试系统及方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2746285A (en) * 1951-03-09 1956-05-22 Standard Oil Co Flash point measurement apparatus
US2746286A (en) * 1951-03-09 1956-05-22 Standard Oil Co Apparatus for automatic flash point testing
US2971370A (en) * 1957-12-10 1961-02-14 Standard Oil Co Gasoline-rejecting mechanism for continuous flash point instrument
US3186213A (en) * 1963-10-15 1965-06-01 Sun Oil Co Flash point analyzer
US3293905A (en) * 1964-04-27 1966-12-27 Gulf Research Development Co Flash-point detector for pipeline operation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2746285A (en) * 1951-03-09 1956-05-22 Standard Oil Co Flash point measurement apparatus
US2746286A (en) * 1951-03-09 1956-05-22 Standard Oil Co Apparatus for automatic flash point testing
US2971370A (en) * 1957-12-10 1961-02-14 Standard Oil Co Gasoline-rejecting mechanism for continuous flash point instrument
US3186213A (en) * 1963-10-15 1965-06-01 Sun Oil Co Flash point analyzer
US3293905A (en) * 1964-04-27 1966-12-27 Gulf Research Development Co Flash-point detector for pipeline operation

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3748894A (en) * 1972-06-15 1973-07-31 Texaco Inc Means and method for an on-line determination of the flash point of lube oil fractions
US4831559A (en) * 1986-07-25 1989-05-16 Phillips Petroleum Company Method and apparatus for periodically determining the flash point of a flammable liquid
EP0305206A3 (en) * 1987-08-27 1989-12-06 Nippon Oil Co., Ltd. Apparatus for measuring flash point of petroleum intermediate fraction and method for controlling flash point

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DE1623002A1 (de) 1970-04-16
DE1623002C3 (enrdf_load_stackoverflow) 1974-12-19
DE1623002B2 (enrdf_load_stackoverflow) 1974-05-16
GB1068375A (en) 1967-05-10
NL6510165A (enrdf_load_stackoverflow) 1966-02-08

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