Storage of various chemicals in tanks. Image Credit: VEGA
It takes thoroughly thought-out solutions in accordance with current standards and ecological responsibility to dispose of chemicals
Incineration of the materials can be the most sustainable option if the degree of pollution permits it. This disposal method ranks below recovery in the EU Waste Directive and has two main objectives.
Challenges Encountered in Waste Disposal
The first, reducing the volume of waste, and the second, destroying potentially dangerous substances. This poses significant 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, optimize and neutralize the process streams and residual materials. These are kept at the respective waste incineration plants in large storage tanks.
With its large selection of process fittings, VEGAPULS 64 is suitable for a wide variety of applications in the chemical industry. Image Credit: VEGA
The British town of Belvedere, near London, is such a site. It is the site of four polypropylene tanks filled with sodium hydroxide. Every process medium is stored in large containers for long-term supply, and also in small day tanks for process-critical dosing and neutralization. Originally, all tanks were supplied with a low-cost bubbler level measuring system. However, this eventually failed due to corrosion and build-up. There was also the issue of vapors and gases escaping through the housing. Moreover, the systems were unreliable, inaccurate and overall, very unsafe.
Chemical tanks for storing acids and alkalis. Image Credit: VEGA
The sensor must be made of appropriate materials to ensure a long working life. These are usually expensive alloys that are equipped with special elastomer seals, and personnel have to wear extensive protective equipment when installing or de-installing a sensor.
Additionally, the surrounding area must be closed off during the procedure. While these measures are necessary, they do incur high costs, as well as posing a security risk.
Ensuring Safety with Hazardous Substances
The stored chemicals, especially those that are highly acidic or alkaline, are usually highly toxic, corrosive substances that can easily leave residues and outgas. Any contact with these substances, or any release of these substances into the atmosphere can rapidly become dangerous for personnel.
These chemical substances are carefully monitored at the Belvedere plant. Accurate level measurement helps to avoid overfilling containers and guarantees that there are enough raw materials for the process.
A VEGAPULS 64 radar sensor, mounted above a storage tank on a boom, measures the level of hydrochloric acid right through the top of the tank. Image Credit: VEGA
"The previous level measuring system caused a lot of problems. These have been completely eliminated by the new sensors," explains the responsible engineer.
Radar sensors are mounted above all small day tanks containing acids and alkalis. They measure the liquid level from the outside. Image Credit: VEGA
Non-Contact Radar Technology
VEGA’s suggestion to use non-contact radar technology eliminated these problems. It would include using externally mounted sensors that can “see” directly through the top of the tank to measure the level inside. Plastic, glass and ceramic are just some of the non-conductive materials that a radar sensor can transmit through, and its signals are only reflected when they strike the liquid surface.
Even liquid condensate or deposits on the ceiling inside the vessel do not interfere with the measurement, due to the sensor’s good dynamic range.
Belvedere’s radar sensors at the waste incineration plant are now measuring successfully through the tops of chemical tanks, which are mounted on simple frames with holders also supplied by VEGA. The instruments required basic settings for the minimum and maximum levels.
Benefits of Radar Technology
There are a number of benefits to using radar technology to measure through plastic tanks and even glass windows in reactors. Not only does it increase safety and reliability, but it also improves chemical compatibility and the time it takes at the point of installation, not to mention savings in sensor data.
As the operators of the Belvedere plant summed it up, "VEGAPULS 64 radar level measuring instruments give us real flexibility and security in operating our chemical storage tanks and controlling the processes."
The excellent signal focusing of VEGAPULS 64 makes reliable measurement possible even through small windows. Image Credit: VEGA
This information has been sourced, reviewed and adapted from materials provided by VEGA Grieshaber KG.
For more information on this source, please visit VEGA Grieshaber KG.