Excellent signal focusing makes radar level measurement successful in butane sphere
The innovative VEGAPULS 64 is creating exciting new opportunities to use radar for liquid level measurement where it was thought to be impossible. The story below details how a refinery discovered that the non-contact radar sensor was the best available solution for accurate measurement in its butane storage sphere.
The Problem: Large sphere plus a small valve equals unreliable level measurement
A large facility in Ontario refines between 50,000 and 100,000 barrels of oil per day to manufacture a variety of products including propane, diesel fuel, and heavy oils. One of the hydrocarbons the plant produces is butane, a low-DK compound that refineries often use for gasoline blending or as a feedstock for other products.
The refinery stores butane in an enormous sphere, approximately 55-feet in diameter. One feature of the immense vessel is a mounting nozzle, on which sits a two-inch process connection where a guided wave radar (GWR) sensor was installed to measure the butane inside the sphere. The GWR cable probe came with a float to reflect the signal due to the extremely low dielectric properties of butane. Unfortunately, the GWR/float combination did not provide proper reliable measurement from the time of installation. The refinery wasn’t in any danger of a shut down or an overfill—it has a backup system in place—but the guided wave radar and float were a source of constant frustration. After seven years of inconsistent readings and frequent repair, operators used a period of routine maintenance to find a more reliable level measurement solution.
The Solution: VEGAPULS 64 is the last sensor standing
The refinery refused to settle for another unreliable measurement technology, so users in the plant searched for a non-contact radar sensor that could measure butane without using a float. There was just one catch: The device would have to be mounted on a two-inch ball valve.
A valve that small on a sphere that large may provide a challenge for any radar sensor. Ball valves contain many interior surfaces that reflect radar signals, and given that these valves are often used in combination with a bleed ring to trap any gas leftover after the valve is closed, signal noise is often amplified. All of these reflections make it difficult to discern which signals are from the valve and which are from the media. Perhaps that is why two of VEGA’s competitors, both larger firms with more resources, declined the opportunity to test a radar sensor in this application.
VEGA Americas recommended a VEGAPULS 64, the first 80 GHz radar sensor for liquid level measurement. The instrument’s high transmission frequency creates a narrow radar beam, so fewer signals are created by the valve’s interior. This minimized noise creates an easier experience for users who now have a clearer picture of the level inside the sphere. By comparison, a conventional radar sensor with 26 GHz transmission frequency has a beam angle approximately three times the size of a VEGAPULS 64, making it a non-starter in the tight confines of a ball valve.
Another reason VEGA felt confident the VEGAPULS 64 would succeed in this application is its large dynamic range. This increased sensitivity to small signals makes the sensor compatible with poorly-reflective products like butane. The VEGAPULS 64 also features enhanced STC, so it ignores interference from condensation. From a signal-focusing and software perspective, the VEGAPULS 64 was the right level instrument for the application.
After seven years of unreliable level measurement in its butane sphere, a high volume of maintenance calls, and a mountain of frustration, users in the refinery were starved for an accurate, durable process instrument. The VEGAPULS 64 exceeds all expectations. The radar level sensor’s hyper-focused beam is the ideal in combination with a ball valve because it minimizes signals reflected from the valve’s surface, giving users a clear measurement reading.
The sensor’s 98-foot measuring span means it has no trouble in the large sphere, and the instrument’s sensitivity means it receives consistent, reliable signals from butane, a low-DK liquid. Gone are the days of frequent maintenance calls, and users in the refinery enjoy accurate level measurement in a once-trying application.