Method and apparatus for measurement of steam quality
AssigneeConoco Inc.
InventorsPhilip W. Reed, John D. Alexander
Life of this patent
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Abstract
A method and apparatus for directly measuring steam quality in-line. A variable frequency capacitance cell receives a hybrid stream (one having both liquid and vapor phases). The resultant frequency of the electrical circuit of which the capacitance cell is an element, varies with the dielectric constant of the capacitance cell (i.e., the water vapor concentration in the cell). The resultant frequency of the cell is preferably beat with a reference frequency that is within about 15 MHz from the resultant frequency to facilitate measurement.
Claims19
A method of continuously measuring the quality of steam in a flow line containing a hybrid stream of both a gas phase and a liquid phase, said method comprising:
- providing an electrical circuit which operates at a resultant frequency exceeding 20 MHz;
- flowing said hybrid stream through an element of said electrical circuit to induce a change in capacitance within said circuit said change in capacitance producing a change in said resultant frequency of the electrical circuit;
- measuring the magnitude of the resultant frequency, said magnitude being a function of a variance in dielectric constant which is proportional to percent liquid in said hybrid stream;
- measuring the hybrid stream's temperature and pressure;
- calculating the steam quality of said hybrid stream.
Apparatus for continuously measuring the steam quality of a hybrid stream in a flow line containing both a gas phase and a liquid phase, said hybrid stream having a temperature and a pressure, said apparatus comprising:
- an electrical circuit operating at a resultant frequency exceeding 20 MHz;
- flow means for said hybrid stream passing through an element of said electrical circuit to induce a change in capacitance within said circuit which, in turn, produces a change in said resultant frequency;
- means for measuring the magnitude of said resultant frequency, said magnitude being a function of a variance in dielectric constant resulting from the fluctuation in said liquid phase;
- means for measuring the temperature or pressure of said hybrid stream;
- means for calculating the steam quality given the resultant frequency and the temperature or pressure of said hybrid stream.
Dependencies are inferred from the claim text.