FEATURE FLOW, LEVEL & CONTROL Non-contact level sensors ensure safety in HAZARDOUS AREAS
A waste incineration plant has turned to VEGA Controls for non-contact level sensors to accurately measure level in chemical tanks, increasing safety and reliability
costs. They also pose a security risk. The stored chemicals, especially those that are highly acidic or alkaline, are usually highly toxic, corrosive substances that can leave residues and easily outgas. Any contact with or release of such substances into the atmosphere can quickly become dangerous for personnel. At the Belvedere plant, these chemical substances are carefully monitored. Accurate level measurement helps avoid overfilling and ensures that there are enough raw materials for the process. “The previous level measuring system caused a lot of problems. These have been completely eliminated by the new sensors,” explains the responsible engineer. VEGA suggested using its non-contact
isposal of chemicals requires specialised, well thought-out disposal solutions that are in accordance with current standards and ecological responsibility. If the degree of pollution allows it, incineration of the materials can be the most sustainable option. In the EU Waste Directive, this disposal method ranks below recovery and has two main objectives: reducing the volume of waste and destroying potentially dangerous substances. This poses considerable challenges for waste disposal companies: from the bulk handling of incoming waste to the careful monitoring and control of substances entering the environment. Special chemicals are used to purify, optimise and neutralise the process streams and residual materials. They are stored in large storage tanks at strategic points in the respective waste incineration plants. The town of Belvedere, near London, is
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the site of such a waste incineration plant. Four polypropylene tanks filled with sodium hydroxide are located on site. Every process medium is stored in large containers for long-term supply and in small day tanks for process- critical dosing and neutralisation. All tanks were originally supplied with a low-cost bubbler level measuring
10 JUNE 2018 | INSTRUMENTATION
system, which eventually failed due to corrosion and buildup. Vapours and gases escaped through the housing. Moreover, the systems were unreliable, inaccurate and very unsafe. To ensure a lasting function,
the sensor must be made of the right materials, usually expensive alloys, and equipped with special elastomer seals. When installing or de-installing a sensor, the workforce has to wear extensive protective equipment. In addition, the surrounding area must be closed off during such a procedure. These measures are necessary and involve high
The signal focusing of VEGAPULS 64 makes reliable measurement possible even through small windows
radar technology, VEGAPULS 64, i.e. externally mounted sensors that “look” right through the top of the tank, to measure the level inside. A radar sensor can transmit signals through plastic and other non-conductive materials such as glass and ceramic. The signals are only reflected when they strike the liquid surface. And thanks to the good dynamic range of the sensor, even liquid condensate or deposits on the ceiling inside the vessel do not interfere with the measurement.
With its large selection of process fittings, VEGAPULS 64 is suitable for a wide variety of applications in the chemical industry
The radar sensors at the waste
Radar sensors are mounted above all small day tanks containing acids and alkalis. They measure the liquid level from the outside
incineration plant in Belvedere are now measuring successfully through the tops of chemical tanks. They are mounted on simple frames with holders supplied by VEGA. The instruments required only basic settings for the minimum and maximum levels. Using radar technology to measure through plastic tanks and even glass windows in reactors offers great advantages: increased safety and reliability, chemical compatibility and time-saving installation. Not to mention savings in sensor data.
VEGA Controls
www.vega.com
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