A vapor recovery unit captures valuable volatile organic compounds and other rich gas streams that may otherwise be a significant environmental pollutant. Vapor recovery units are increasingly being used in natural gas processing facilities for a variety of reasons. Compounds recovered in these units can themselves be sold by the facility, increasing the profit and productive capabilities of the plant. In addition, using a vapor recovery unit reduces air pollution and emissions, recovering gases that would otherwise be released to the atmosphere or burned in a flare.
Vapor recovery units collect from storage and loading facilities, liquefy the vapors, and return the liquid hydrocarbons back to storage. Methods to recover vapors include absorption, condensation, adsorption and simple cooling. A new technology known as ejector vapor recovery creates a closed loop system to recover the gas vapor and reduce methane emissions. In every case, the simple, economical process unit provides EPA compliance and improves operating economies by capturing up to 95% of fugitive emissions.
This blog post, part of the Magnetrol® blog series on natural gas processing applications, discusses how level instrumentation plays a role in ensuring vapor recovery units operate effectively and recover as much of the emissions as possible.
Level Measurement Challenges and Considerations
Critical to the VRU is the flash drum where vapors are liquefied. Liquid level control of the flash drum is essential. Without reliable, accurate level instrumentation, the liquification process will be compromised and less efficient. In addition, flash drums such as those present in vapor recovery units require level measurement solutions that are able to withstand high temperatures and pressures.
Level Measurement Solutions
MAGNETROL has produced level measurement solutions for vapor recovery units:
- For point level:
Series 3 external cage level switch; Tuffy® II float-actuated switch; Echotel® Model 961 ultrasonic switch; or Thermatel® TD1/TD2 thermal dispersion switch
- For continuous level:
Eclipse® Model 706 guided wave radar transmitter or E3 Modulevel® displacer transmitter
- For visual indication:
Atlas or Aurora® magnetic level indicators
For more information on level measurement solutions for vapor recovery units and other natural gas processing applications, download the natural gas processing brochure.