Level Control Applications for the Chemical Processing Industry

The chemical processing industry is dependent on proper level control to ensure safety and efficiency. Storage and processing technologies such as waste sumps, neutralization, liquids storage and liquefied gas storage can benefit from level instrumentation and improve their performance. In this article, part of Magnetrol’s series on the chemical processing industry, we will explore the impact that level control instrumentation can have on chemical manufacturing and storage. If you missed the previous posts in the series, be sure to catch up on them, from February 10, February 17, March 3, and March 10. 

Waste Sump

chemical_processing_industryApplication: Industrial chemical plants generate large volumes of liquid wastes and runoffs that are collected in large open-atmosphere sumps—concrete lift stations, in-ground pits or reservoirs. When the collected liquid reaches a pre-determined level it is discharged for transport to waste storage, treatment, or disposal facilities.

Challenges: Level controls typically actuate a pump to automatically control sump level between two set points. The control can be configured to activate an alarm and a pump shutdown to avoid overfill or pump cavitation in the event of too high or too low levels. Sump level controls must often be robust enough to contend with corrosive media, high solids content and very punishing weather.

Level Technologies:
– Model A10 Displacer-Actuated Level Switch for point level
– Echotel® Model 338 Ultrasonic Transmitter for continuous level

Neutralization

Application: To protect neighboring water systems, industrial wastewater must be neutralized so that it is neither acidic nor chemical_processing_industry_2alkaline prior to its discharge. The neutralization process takes place in a tank where aqueous solutions of an acid and a base are added to wastewater. Sulfuric acid, sodium hydroxide and calcium carbonate are most commonly used.

Challenges: Level is measured in the neutralization and chemical regeneration tanks, which typically involve agitation and aggressive chemicals. Ideally, the tank level monitoring system should be easily removable for frequent cleaning. Contact level sensors should be single rod types to avoid media buildup.

Level Technologies:
– ECHOTEL Model 961 Ultrasonic Level Switch for point level
– Pulsar® Model RX5 Pulse Burst Radar Transmitter or ECHOTEL Model 338 Ultrasonic Transmitter for continuous level
– Orion Instruments® Atlas™ or Aurora® Magnetic Level Indicators for visual indication

Liquids Storage

chemical_processing_industry_3Application: Liquids stored at chemical plants include water (potable, demineralized, fire, cooling), ingredients and finished product storage. Hazardous chemicals include inorganic acids, buffers, ammonia, chlorine, and solvents. Tanks range in size from small plastic totes to large steel tanks. The chemical stored and the tank type largely determine the level control used.

Challenges: Level instruments indicate inventory levels and protect against tank overfills and underfills that cavitate pumps. As some chemicals are corrosive enough to destroy contact sensors, or can crystallize and coat sensors to render them ineffective, non-contact level monitoring, resistant materials, by-pass chambers and redundant controls are sometimes used.

Level Technologies:
– Model A10 Displacer-Actuated Level Switch for point level
– PULSAR Model RX5 Pulse Burst Radar Transmitter or ECHOTEL Model 338 Transmitter for continuous level
– ORION Instruments ATLAS or AURORA Magnetic Level Indicators for visual indication

Liquified Gas Storage

Application: Gases are frequently converted to a liquid to facilitate convenient storage. chemical_processing_industry_4Many liquefy by cooling at normal atmospheric pressure while others require pressurization as well. Industrial gases commonly stored in this fashion include liquid oxygen, liquid nitrogen, liquefied chlorine, LPG and LNG. Gases are re-vaporized through an application of heat.

Challenges: Above or below ground insulated storage tanks are built to specifically hold liquefied gases and minimize the amount of evaporation. Liquefied gas tank level monitoring typically contends with pressurization, extremely low temperatures and low dielectric media. Contact and non-contact measurement sensors may require a standpipe.

Level Technologies:
– Series 3 Float-Actuated External Cage Switch or Tuffy® II Float- Actuated Switch for point level
– Eclipse® Model 706 Guided Wave Radar or PULSAR Model RX5 Pulse Burst Radar Transmitter for continuous level
– ORION Instruments ATLAS or AURORA Magnetic Level Indicators for visual indication

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