Method and apparatus for measuring steam quality

Apparatus for measuring the bulk density of a flowing two phase fluid, comprising:

• two parallel tubes, each of said tubes having a first end and a second end with the first ends of the respective tubes being adjacent each other and the second ends of the respective tubes being adjacent each other;
• first common mass means positioned at the first ends of said tubes for providing a common first node for said first ends of said tubes, the first ends of said tubes being rigidly anchored to said first common mass means;
• second common mass means positioned at the second ends of said tubes for providing a common second node for said second ends of said tubes, the second ends of said tubes being rigidly anchored to said second common mass means;
• conduit means connected to said tubes for directing the flowing two phase fluid through said tubes;
• vibration inducing means positioned between said tubes for causing said respective tubes to vibrate in opposition to each other while said two phase fluid is flowing therethrough;
• and
• vibration measuring means associated with said tubes for measuring the frequency of vibration of the tubes.

The method of determining steam quality of flowing two phase wet steam, comprising the steps of:

• flowing the wet steam through a chamber;
• inducing the chamber structure to vibrate;
• measuring the resonant frequency of the chamber with the wet steam therein, and determining the bulk density of the wet steam as a function of the resonant frequency of the chamber structure;
• measuring the wet steam temperatue in the chamber, and determining the vapor density as a function of the temperature;
• and
• determining steam quality as a ratio of the vapor density to the bulk density of the wet steam.

Apparatus for measuring steam quality of flowing wet steam on a real-time basis, comprising:

• two hollow elongated tubes of the same size and shape positioned in parallel relation spaced apart from each other, wherein one end of one tube is connected together in fluid flow relation to the adjacent end of the other tube and the opposite ends of both tubes are anchored in a common mass;
• vibration inducing means positioned between said tubes for causing said tubes to vibrate in respectively opposite directions from the vibrations in the other such that there is a node of no vibration at the connection of one tube to the other and another node of no vibration in the common mass;
• an inlet flow line connected in fluid flow relation to the end of one of said tubes that is anchored in the common mass, and an outlet flow line connected in fluid flow relation to the end of the other of said tubes that is anchored in the common mass, such that there is a continuous flow path for fluid extending from said inlet flow line through one of said tubes and then through the other of said tubes and out the outlet flow line;
• vibration sensing means connected to one of said tubes for sensing the frequency and magnitude of vibrations of said tube;
• temperature sensing means in said flow path for sensing the temperature of a fluid flowing in the flow path;
• and
• computer means connected to said vibration sensing means and to said temperature sensing means for determining resonant frequency of the vibrating tube and outputting the steam quality value as a ratio of the temperature to the resonant frequency.