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Publication numberUS3901062 A
Publication typeGrant
Publication dateAug 26, 1975
Filing dateJun 28, 1974
Priority dateJun 28, 1974
Publication numberUS 3901062 A, US 3901062A, US-A-3901062, US3901062 A, US3901062A
InventorsHarrison Charles W, Kimtantas Charles L, Lynch Charles R, White William D
Original AssigneeTexaco Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Vapor pressure measuring apparatus
US 3901062 A
Abstract
Apparatus measures the vapor pressure of raw crude oil entering a flash tower by measuring operating parameters of the flash tower and its output streams. Flow rates of light component vapor provided by the flash tower and of the flashed crude oil are provided to a vapor pressure sensing network, which also receives signals corresponding to the pressure within the flash tower, to the temperature of the liquid in the flash tower and to the molecular weight and specific gravity of the flashed crude oil. The pressure of the flashed crude oil is then determined utilizing the received signals and equations hereinafter described. The vapor pressure of the flashed crude oil and the vapor pressure of the light component stream, which is substantially constant, is then apportioned according to the relation of the mole flow rates of the light hydrocarbon vapor and the flashed crude oil. The sum of the apportionment is then used to determine the vapor pressure of the raw crude oil.
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Description  (OCR text may contain errors)

United States Patent [1 1 laynch et a1.

[ 1 Aug. 26, 1975 VAPOR PRESSURE MEASURING APPARATUS [75] Inventors: Charles R. Lynch, Arthur; Charles W. Harrison, Nederland; Charles L. Kimtantas, Groves; William D. White, Nederland, all of Tex.

[73] Assignee: Texaco Inc., New York, NY.

[22] Filed: June 28, 1974 [21] Appl. N0.: 484,003

Primary Examiner-Jerry W. Myracle Assistant Examiner.loseph W. Roskos Attorney, Agent, or Firm-T. H. Whaley; C. G. Ries; Ronald G. Gillespie 5 7 ABSTRACT Apparatus measures the vapor pressure of raw crude oil entering a flash tower by measuring operating parameters of the flash tower and its output streams. Flow rates of light component vapor provided by the flash tower and of the flashed crude oil are provided to a vapor pressure sensing network, which also receives signals corresponding to the pressure within the flash tower, to the temperature of the liquid in the flash tower and to the molecular weight and specific gravity of the flashed crude oil. The pressure of the flashed crude oil is then determined utilizing the received signals and equations hereinafter described. The vapor pressure of the flashed crude oil and the vapor pressure of the light component stream, which is substantially constant, is then apportioned according to the relation of the mole flow rates of the light hydrocarbon vapor and the flashed crude oil. The sum of the apportionment is then used to determine the vapor pressure of the raw crude oil.

9 Claims, 2 Drawing Figures L|GHT COMPONENTS VAPQR RECORDING MEANS -"'4O [52] US. Cl. 73/64.2

[51] Int. Cl. G0ln 7/16 [58} Field of Search 73/642, 53, 61.3, 36, 73/29 [56] References Cited UNITED STATES PATENTS 2,126,052 8/1938 Smith 73/36 2,949,768 8/1960 Ryant, Jr. et a1, 73/53 3.037.375 6/1962 Jacobs ct a1. 74/642 1191,4128 6/1965 Piros 73/53 3,247,708 4/1966 Luthcr 73/53 3,332,856 7/1967 Hart 73/53 X FLASH VAPOR TOWER PRESSURE L ssnsms RAW CRUDE I6 OIL SIGNAL MEANS SOURCE v4 OF 00 VOLTAGE 6 7 8 FLASHED CRUDE OIL PATENTED AUG26I975 SH ER '& L|GHT COMPONENTS VAPOR SIGNAL MEANS RECORDING MEANS 40 l v VAPOR 2 5| V3 MEANS gQ I30 L V5 v0 E v 22 6 V7 5T V8 VAPOR PRESSURE MEASURING APPARATUS BACKGROUND OF THE INVENTION Field of the Invention The apparatus of the present invention relates to measuring apparatus in general and, more particularly, to measuring apparatus for refinery units.

SUMMARY OF THE INVENTION Apparatus provides a signal corresponding to the vapor pressure of a feed hydrocarbon entering a process vessel which yields a vapor and a processed hydrocarbon liquid. The apparatus includes a network which samples the processed hydrocarbon liquid and provides signals corresponding to the molecular weight and the specific gravity of the processed hydrocarbon liquid. Sensors sense the flow rates of the vapor and of the processed hydrocarbon liquid and provide corresponding signals. Other sensors provide signals corresponding to the sensed pressure of vapor in the vessel and the sensed temperature of the hydrocarbon liquid in the vessel. A circuit receiving signals from the network and from the sensors provides the feed hydrocarbon vapor pressure signal in accordance with the received signals.

The objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings, wherein one embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration purposes only, and are not to be construed as defining the limits of the invention.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a simplified block diagram of apparatus, constructed in accordance with the present invention, for determining the vapor pressure of crude oil which is being flashed by a flash system also shown in partial schematic form.

FIG. 2 is a block diagram of the vapor pressure sensing means shown in FIG. I.

DESCRIPTION OF THE INVENTION Referring to FIG. 1, a flash tower 1 receives raw crude oil through a line 5. The crude oil separates into light components vapor and into flashed crude oil. The light components vapor is removed from flash tower l by way of a line 8 while the flashed crude oil is removed from flash tower l by way of a line 10. Flow rate sensors 12, 14 provide signals F and F respectively, corresponding to the flow rates of the light components vapor and the flashed crude oil, respectively, to vapor 7 pressure sensing means 16.

A conventional type pressure transmitter 20 provides a signal P corresponding to the sensed pressure in flash tower I to vapor pressure sensing means 16 while a conventional type temperature trnasmitter 22 provides a signal T, corresponding to the sensed temperature of the liquid in flash tower l, to vapor pressure sensing means 16.

Signal means 24 samples the flashed crude oil in line and provides signals M and G, corresponding to the average molecular weight and to the specific gravity,

respectively, of the flashed crude oil. Signal means 24 may be of the same type shown as signal means 24 in US. Pat. No. 3,733,476. Signals M, G are provided to vapor pressure sensing means 16.

Equations 1 through 5 describe the various relationships that vapor pressure sensing means 16 uses in determining the vapor pressure of the raw crude oil in line MRO MRV where K through K are constants having values of 9.97606, 100, 460, 14.7, 350, 2.6385, 20.0 and 0.46 for a particular process system; AHVP is an adjusted hydrocarbon vapor pressure in the flash tower corrected to 100F; MRO is a molar rate of the flashed crude oil in units of lb. moles of liquid per hour; MRV is the molar rate of the vapor in units of lb. moles of gas per hour and RVP is the Reid Vapor Pressure of the raw crude oil.

Vapor pressure sensing means 16 receives direct current voltages V to V from a source 30 of direct current voltages and provides a signal E corresponding to the vapor pressure of a petroleum fraction to recording means 40. Voltages V to V correspond to the constants K, through K described in Equations 1 through 5, above. Recording means 40 records signal E, from vapor pressure sensing means 16.

Referring now to FIG. 2 vapor pressure sensing means 16 includes summing means 50 which sums pressure signal P with voltage V, to provide a signal corresponding to the term P+K to a natural log function generator 53. Generator 53 provides a signal corresponding to the term ln(P+K to summing means Summing means 60 and subtracting means 63 sums signal T with voltage V;, and subtracts signal T from voltage V respectively. Summing means 60 provides a signal, corresponding to the term (T-l-K to a divider 68 while subtracting means 63 provides a signal, corresponding to the term (K -T), to a multiplier 70. Multiplier 70 multiplies voltage V with the signal from subtracting means 63 to provide a signal to divider 68. Divider 68 divides the signal from multiplier 70 with the signal from summing means 60 to provide a signal to summing means 54.

Summing means 54 sums the received signals to provide a signal, corresponding to the term A, to a convention type exponential function generator which in turn provides a signal corresponding to the term AHVP in equation 1.

A multiplier multiplies flow rate signal F with specific gravity signal G to provide a signal to a multiplier 81. Multiplier 81 multiplies the signal from multiplier 80 with voltage V; to provide a signal to divider 82. Divider 82 divides the signal from multiplier 81 with signal M to provide a signal corresponding to the molar rate MRO of the flash crude oil. A multiplier 84 multiplies the signal from divider 82 with the signal from generator 75 to provide a signal corresponding to the term (AHVP)(MRO) in equation 5.

A multiplier 87 multiplies flow rate signal F with voltage V to provide a signal corresponding to the molar rate MRV for the vapor in line 8. Summing means 90 sums the signal from divider 82 with the sig nal from multiplier 87 to provide a signal corresponding to the term (MRO+MRV). A divider 93 divides the signal provided by multiplier 84 with the signal from summing means 90 to provide a signal corresponding to the term (AHVP) (MRO) (MRO) (MRV) A multiplier 95 multiplies the signal from multiplier 87 with voltage V to provide a signal corresponding to the term (K )MRV in equation 5. A divider 98 divides the signal provided by multiplier 95 with the signal provided by summing means 90 to provide a signal corresponding to the term (MRO MRV) Summing means 100 sums the signals from dividers 93, 98 to provide a signal to subtracting means 103. Subtracting means 103 subtracts voltage V from the signal provided by summing means 100 to provide signal E corresponding to the Reid Vapor Pressure RVP of the raw crude oil.

The apparatus of the present invention as hereinbefore described provides an output corresponding to the Reid Vapor Pressure of raw crude oil entering a flash tower while monitoring the operation of the flash tower so as to provide an on-line determination of the Reid Vapor Pressure. The apparatus of the present invention as heretofore described is not restricted to the determination of the Reid Vapor Pressure of raw crude oil but is also applicable to the vapor pressure of any hydrocarbon liquid entering a process vessel which provides a vapor and a processed hydrocarbon liquid as well as other chemical processes.

It would be obvious to one skilled in the art that a general purpose digital computer could be utilized to determine the Reid Vapor Pressure of the raw crude oil. Signals F F T, G, M and P would be converted to digital signals using conventional type analog-todigital converters. The digital computer may provide its own record or output digital signals. The output digital signals would then be converted to signal E by a digital-to-analog converter.

What is claimed is:

1. Apparatus for providing an output signal corresponding to the vapor pressure of a feed fluid entering a process vessel which yields a vapor and a processed liquid, comprising means for sampling the processed liquid and providing signals corresponding to the molecular weight M and the specific gravity G of the processed liquid, means for sensing the flow rates F and F of the vapor and the processed liquid and providing signals corresponding thereto, means for sensing the pressure P of vapor in the vessel and providing a corresponding signal, means for sensing the temperature T of liquid in the vessel, and means connected to sampling means and to all the sensing means for providing the output signal corresponding to the vapor pressure of the feed fluid in accordance with the F F P, T, M and G signals from the sampling means and the sensing means.

2. Apparatus as defined in claim 1 in which the feed fluid is a hydrocarbon liquid, and the processed liquid is a processed hydrocarbon liquid.

3. Apparatus as defined in claim 2, in which the output signal means includes means connected to the pressure and temperature sensing means for providing a signal corresponding to a term A in accordance with the P and T signals from the pressure and temperature sensing means and the following equation:

where K through K are constants, and network means connected to the A signal means for providing the AHVP signal in accordance with the A signal and the following equation:

4. Apparatus as defined in claim 3 in which the output signal means includes means connected to the sampling means and to the flow rate sensing means for providing a signal corresponding to the molar rate MRO of the processed hydrocarbon liquid in accordance with M and G signals from sampling means and the F signal from the flow rate sensing means, and means connected to the flow rate sensing means for providing a signal corresponding to the molar rate MRV of the vapor in accordance with the F signal from the flow rate sensing means.

5. Apparatus as defined in claim 4 in which the MRO signal means provides the MRO signal in accordance with the F M and G signals and the following equation:

(m (K5) MRO M where K is a constant, and the MRV signal means provides the MRV signal in accordance with the F signal and the following equation:

where K is a constant.

6. Apparatus as defined in claim 5 in which the out put signal means includes summing means connected to the MR0 and the MRV signal means for providing the output signal in accordance with the sum of the MRV and MR0 signals.

7. Apparatus as defined in claim 6 further comprising means connected to the summing means for recording the output signal.

8. Apparatus as defined in claim 6 in which the process vessel is a flash tower, the feed hydrocarbon is raw crude oil, the processed hydrocarbon is flashed crude oil, and the vapor is light components gas.

9. Apparatus as defined in claim 5 in which the constants K through K have values of 9.97606, 100, 460, 350 and 2.6385, respectively.

UNITED STATES PATENT AND TRADEMARK OFFICE QEIFICAT 9F CGRRECTIQN PATENT NO. 3901062 DATED AUGUST 26, 1975 INVENTOR(S) 2 CHARLES R. LYNCH; CHARLES W HARRISONgCHARLES L KIMTANTAS; WILLIAM D. WHITE It Is certrfred that error appears m the above-ldentrfred patent and that sad Letters Patent are hereby corrected as shown below:

Claim 3, line 25 "AHVP=e should read --AHVP=e Signed and Scaled this finest:

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner 0] Patent: and Trademarks

Patent Citations
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3964975 *Aug 19, 1974Jun 22, 1976Texaco Inc.Means for controlling the temperature of a depropanizer tower
US4522056 *Aug 26, 1983Jun 11, 1985Chevron Research CompanyMethod and apparatus for measuring Reid Vapor Pressure
US4578151 *Jul 23, 1982Mar 25, 1986Phillips Petroleum CompanyReid Vapor Pressure determination and control in fractional distillation
US4667508 *Dec 11, 1985May 26, 1987Phillips Petroleum CompanyReid vapor pressure determination
US4739699 *Aug 14, 1986Apr 26, 1988Steeltin Can CorporationApparatus for pasteurizing or sterilizing edible foodstuffs
US4788871 *Dec 3, 1987Dec 6, 1988Steeltin Can CorporationProbe for sensing temperature and/or pressure
US4889600 *Feb 16, 1988Dec 26, 1989Conoco Inc.Fractionating column control apparatus and methods
US5022259 *Apr 20, 1990Jun 11, 1991Lee William LAutomated vapor pressure analyzer
US5047125 *Aug 25, 1989Sep 10, 1991Conoco Inc.Fractionating column control apparatus and methods
US5327779 *Sep 24, 1992Jul 12, 1994Ethyl CorporationVapor pressure measurement by gas saturation for mixture
US5499531 *Mar 17, 1995Mar 19, 1996The Mitre CorporationSystem and method for determining volatile constituents, vapor pressure and vapor emissions of liquids
EP0199861A1 *Apr 23, 1985Nov 5, 1986Chevron Research CompanyMethod and apparatus for measuring reid vapour pressure
WO1996029588A1 *Mar 15, 1996Sep 26, 1996Mitre CorpSystem and method for determining volatile constituents, vapor pressure and vapor emissions of liquids
Classifications
U.S. Classification73/64.45
International ClassificationG01N7/00, G01N7/16
Cooperative ClassificationG01N7/16
European ClassificationG01N7/16