System for continuous analysis and modification of characteristics of a liquid hydrocarbon stream

• US 5,663,492 A
• Filed: 06/05/1996
• Issued: 09/02/1997
• Est. Priority Date: 06/05/1996
• Status: Expired due to Term

• Current Assignee: Bryan H. Sonnier, Rama Rao Alapati, Shammai, Houman M.
• Original Assignee: Bryan H. Sonnier, Rama Rao Alapati, Shammai, Houman M.
• Inventors: Shammai, Houman M., Alapati, Rama Rao, Sonnier, Bryan H.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): POLITZER, JAY L
• Application Number:
  US08/658,640
• Time in Patent Office: 454 Days
• Field of Search: 73/19.01, 73/19.1, 73/19.12, 73/23.41, 73/61.41, 73/61.43, 73/61.59, 73/64.45, 73/863.12, 73/864.83, 73/864.84, 203/2
• US Class Current: 73/64.45
• CPC Class Codes: G01N 33/2823 raw oil, drilling fluid or polyphasic mixtures hydrocarbon content of earth materials G01N33/241; prospecting G01V; drilling per se E21B
• CPC Class Codes: G01N 33/2829 mixtures of fuels, e.g. determining the RON-number
• CPC Class Codes: G01N 7/00 Analysing materials by measuring the pressure or volume of a gas or vapour

Abstract

Apparatus and method for continuous analysis and/or modification of the vapor pressure characteristics of a hydrocarbon stream includes: liquid/gas separation chamber; constant flow liquid influent means; liquid level sensing means; temperature control means; constant pressure gaseous effluent means; liquid effluent means having a flow rate responsive to liquid level sensing means; and influent and effluent flow metering means. Means for sensing composition of gaseous effluent, and manifold means responsive to said composition for variable blending of differing liquid hydrocarbon streams, may also be provided. Influent may be heated or cooled prior to entering the separation chamber.

In the preferred embodiment, liquid influent rate is substantially constant. Temperature and pressure, which pressure may be made sub-atmospheric by vacuum means, are selected and maintained. In the separation chamber, components of the liquid influent having vapor pressures above the selected temperature and pressure of the separation chamber are volatized. Diffusion and mixing means in the chamber enhance rapid volatilization. Separated gas is flowed from the chamber and its composition analyzed by chromatography means. Effluent liquid is flowed from the chamber at a rate which maintains a constant liquid level in the chamber. By measurement and/or control of blending of influent streams, pressure, and/or temperature of the separation chamber responsive to vapor characteristics of liquid effluent, a stream of liquid hydrocarbons may be continuously analyzed and a liquid effluent having desired vapor pressure characteristics continuously produced and/or verified.

Claims

1. An apparatus for continuous measurement of the vapor pressure of a stream of liquid hydrocarbons, comprising:

a chamber having a lower portion substantially filled with hydrocarbons in liquid state and an upper portion substantially filled with vapors of said hydrocarbons, means for sensing the temperature of the hydrocarbons therein, means for sensing the level of liquid hydrocarbons therein, means for sensing the pressure of hydrocarbons therein, and, a heating element responsive to said temperature sensing means in thermal communication with the hydrocarbons in said chamber;

hydrocarbons influent line connected to a portion of said chamber which is above the level of liquid hydrocarbons therein;

hydrocarbons effluent line connected to a portion of said chamber which is below the level of liquid hydrocarbons therein;

hydrocarbons effluent pump responsive to said level sensing means for maintaining a constant level of liquid hydrocarbons in said chamber;

a vapor effluent line connected to a portion of said chamber which is above the level of liquid hydrocarbons therein; and

,

pressure control means in communication with a portion of the chamber which is above the level of liquid hydrocarbons in said chamber, said pressure control means responsive to the pressure of hydrocarbons in said chamber for maintaining said separation chamber at a selected pressure in a range below and above atmospheric pressure.

2. The apparatus of claim 1, wherein said pressure control means comprises a vacuum source and a valve, responsive to pressure of hydrocarbons in said chamber, in communication with said vaccuum source.

3. The apparatus of claim 2, further comprising liquid hydrocarbon diffusion means disposed within said chamber.

4. The apparatus of claim 3, wherein said hydrocarbon influent line further comprises a pump and an orifice disposed in said hydrocarbon influent line between said influent pump means and said separation chamber.

5. The apparatus of claim 4, further comprising a hydrocarbon flow meter disposed in said liquid influent line, a liquid flow meter disposed in said liquid effluent line, and a vapor flow meter disposed in said gas effluent line.

6. The apparatus of claim 5, wherein said pressure control means is disposed on said vapor effluent line.

7. The apparatus of claim 6, further comprising manifold means connected to said hydrocarbon influent line.

8. The apparatus of claim 7, further comprising influent temperature adjusting means disposed in said hydrocarbon influent line.

9. The apparatus of claim 8, further comprising means for continuously mixing of the liquid hydrocarbons in said chamber.

10. The apparatus of claim 9, further comprising vapor composition analysis means connected to said gas effluent line.

11. The apparatus of claim 10, wherein a microprocessor means receives data from said pressure sensing means, said level sensing means, said temperature sensing means, and said vapor composition analysis means, wherein said microprocessor processes said data to produce signals which control influent temperature, manifold means and pressure, level and temperature of hydrocarbons in said chamber so as to produce an effluent of liquid hydrocarbons having desired vapor pressure characteristics.

12. A method for continuous determination of the vapor pressure of a stream of liquid hydrocarbons, comprising the steps of:

a) providing an apparatus comprising;

a separation chamber having temperature sensor means, liquid level sensing means, and pressure sensor means therein, said separation chamber further having a heating element in thermal communication therewith, said heating element responsive to an output signal from said temperature sensor means;

selectable flow liquid influent means connected to a portion of said separation chamber which is above a liquid level in said separation chamber, said selectable flow liquid influent means having an output pressure capability greater than an expected vapor pressure of said liquid hydrocarbon;

a liquid effluent line connected to a portion of said separation chamber which is below said liquid level in said separation chamber, said liquid effluent line having effluent pump means responsive to said liquid level sensing means for maintaining a constant liquid level in said separation chamber;

a gas effluent line connected to a portion of said separation chamber which is above said liquid level in said separation chamber; and

means for controlling separation chamber pressure at a selected substantially constant value within a range of pressure values, said range having a first endpoint below atmospheric pressure and a second endpoint above atmospheric pressure;

b) flowing a liquid hydrocarbon through said separation chamber while maintaining a constant liquid level therein;

c) adjusting separation chamber temperature to a selected temperature; and

d) directly measuring separation chamber pressure with said pressure sensor means under substantially constant liquid level and separation chamber temperature conditions, said separation chamber pressure under said level and pressure conditions equal to the vapor pressure of said liquid hydrocarbon.

13. A method for continuous generation of a liquid hydrocarbon having a desired vapor pressure, comprising the steps of:

a) providing an apparatus comprising;

a separation chamber having temperature sensor means, liquid level sensing means, and pressure sensor means therein, said separation chamber further having a heating element in thermal communication therewith, said heating element responsive to an output signal from said temperature sensor means;

selectable flow liquid influent means connected to a portion of said separation chamber which is above a liquid level in said separation chamber, said selectable flow liquid influent means having an output pressure capability greater than an expected vapor pressure of said liquid hydrocarbon;

a liquid effluent line connected to a portion of said separation chamber which is below said liquid level in said separation chamber, said liquid effluent line having effluent pump means responsive to said liquid level sensing means for maintaining a constant liquid level in said separation chamber;

a gas effluent line connected to a portion of said separation chamber which is above said liquid level in said separation chamber;

means for controlling separation chamber pressure at a selected constant value within a range of pressure values, said range having a first endpoint below atmospheric pressure and a second endpoint above atmospheric pressure;

manifold means connected to said liquid influent line, said manifold means comprising a plurality of liquid inlet lines combining to a single discharge into said liquid influent line, each of said liquid inlet lines connected to a different liquid hydrocarbon source;

b) successively flowing a liquid hydrocarbon from each of said liquid hydrocarbon sources through said separation chamber at a current temperature of said liquid hydrocarbon while maintaining constant liquid level in said separation chamber, said control valve closed preventing any gas effluent flow from said separation chamber;

c) measuring a vapor pressure for each of said liquid hydrocarbons equivalent to the pressure in said separation chamber;

d) determining a ratio of flow rates of said different liquid hydrocarbon sources at said current temperature that yields a desired vapor pressure of a resulting mixture of different liquid hydrocarbons; and

e) combining said liquid hydrocarbon sources at the determined ratio to yield a liquid hydrocarbon effluent having a vapor pressure equal to said desired vapor pressure.

14. A method of determining a gas-oil ratio of a liquid hydrocarbon comprising the steps of:

a) providing an apparatus comprising;

a separation chamber having temperature sensor means, liquid level sensing means, and pressure sensor means therein, said separation chamber further having a heating element in thermal communication therewith, said heating element responsive to an output signal from said temperature sensor means;

selectable flow liquid influent means connected to a portion of said separation chamber which is above a liquid level in said separation chamber, said selectable flow liquid influent means having an output pressure capability greater than an expected vapor pressure of said liquid hydrocarbon;

a liquid effluent line connected to a portion of said separation chamber which is below said liquid level in said separation chamber, said liquid effluent line having effluent pump means responsive to said liquid level sensing means for maintaining a constant liquid level in said separation chamber;

a gas effluent line connected to a portion of said separation chamber which is above said liquid level in said separation chamber; and

pressure control means connected to said separation chamber, said pressure control means responsive to said pressure sensor means for maintaining said separation chamber at a selected pressure in a range below and above atmospheric pressure;

b) flowing a liquid hydrocarbon through said separation chamber at a desired separation chamber temperature and liquid level;

c) measuring a gas effluent rate and a liquid hydrocarbon effluent rate;

d) determining a gas-oil ratio of said liquid hydrocarbon by dividing said gas effluent rate by said liquid hydrocarbon effluent rate.

15. A method of determining shrinkage of a liquid hydrocarbon comprising the steps of:

a) providing an apparatus comprising;

a separation chamber having temperature sensor means, liquid level sensing means, and pressure sensor means therein, said separation chamber further having a heating element in thermal communication therewith, said heating element responsive to an output signal from said temperature sensor means;

selectable flow liquid influent means connected to a portion of said separation chamber which is above a liquid level in said separation chamber, said selectable flow liquid influent means having an output pressure capability greater than an expected vapor pressure of said liquid hydrocarbon;

a liquid effluent line connected to a portion of said separation chamber which is below said liquid level in said separation chamber, said liquid effluent line having effluent pump means responsive to said liquid level sensing means for maintaining a constant liquid level in said separation chamber;

a gas effluent line connected to a portion of said separation chamber which is above said liquid level in said separation chamber; and

pressure control means connected to said separation chamber, said pressure control means responsive to said pressure sensor means for maintaining said separation chamber at a selected pressure in a range below and above atmospheric pressure;

b) flowing a liquid hydrocarbon through said separation chamber at a desired separation chamber temperature and liquid level;

c) measuring a liquid hydrocarbon influent rate and a liquid hydrocarbon effluent rate;

d) determining a liquid hydrocarbon shrinkage by dividing said liquid hydrocarbon effluent rate by said liquid hydrocarbon effluent rate.

16. A method for determining a vapor pressure of a liquid hydrocarbon comprising the steps of:

a) providing an apparatus comprising;

a separation chamber having temperature sensor means, liquid level sensing means, and pressure sensor means therein, said separation chamber further having a heating element in thermal communication therewith, said heating element responsive to an output signal from said temperature sensor means;

selectable flow liquid influent means connected to a portion of said separation chamber which is above a liquid level in said separation chamber, said selectable flow liquid influent means having an output pressure capability greater than an expected vapor pressure of said liquid hydrocarbon;

a liquid effluent line connected to a portion of said separation chamber which is below said liquid level in said separation chamber, said liquid effluent line having effluent pump means responsive to said liquid level sensing means for maintaining a constant liquid level in said separation chamber;

a gas effluent line connected to a portion of said separation chamber which is above said liquid level in said separation chamber; and

pressure control means connected to said separation chamber, said pressure control means responsive to said pressure sensor means for maintaining said separation chamber at a selected pressure in a range below and above atmospheric pressure;

b) creating a pressure within said separation chamber lower than an expected vapor pressure of a liquid hydrocarbon;

c) closing said gas effluent line;

d) adjusting said pressure control means to permit a maximum separation chamber pressure greater than a maximum output pressure of said selectable flow liquid influent means;

e) flowing said liquid hydrocarbon through said separation chamber at a substantially constant separation chamber temperature and liquid level;

f) recording said separation chamber pressure with time-, said separation chamber pressure with time values defining a curve;

g) determining a vapor pressure of said liquid hydrocarbon equal to the pressure of an asymptote to said curve.