When natural gas is extracted from the earth, it naturally contains a variety of other substances, many of which can impact the usability of the gas if not removed or modified. In particular, pipeline specifications require removal of the harmful acid gases carbon dioxide (CO2) and hydrogen sulfide (H2S). H2S is highly toxic and corrosive to carbon steels. CO2 is also corrosive and reduces the British thermal unit (BTU) value of natural gas.
Gas sweetening processes remove these acid gases and make natural gas marketable and suitable for pipeline distribution. One of the most common processes for sweetening gas is amine treatment, which removes acid gases through absorption and chemical reaction.
This blog post, part of the Magnetrol® series on natural gas processing applications, explores the components of amine treatment and how level instrumentation can help ensure all harmful gases are removed.
Level Measurement Challenges and Considerations
Each of the four common amines (MEA, DEA, DGA and MDEA) offers distinct advantages in specific applications. In the absorber, the concentrated amine solution is introduced to absorb the acid gases. Once these sour gases are removed, the sweetened natural gas is lifted out. The amine solution, now rich in acid gases, flows into a flash drum and then to a regeneration unit, where the acid gases are separated from the solution. The separated amine solution is then reused, while the acid gases are transferred to a sulfur recovery unit.
At each step of this process, there are multiple level control applications. Reliable instrumentation throughout will keep acid gases from re-entering the natural gas, ensure that the separated amine solution can be properly reused, and prevent leaks and spillage.
Level Measurement Solutions
MAGNETROL has produced level measurement solutions for amine treatment:
- For point level:
Echotel® Model 961 ultrasonic gap switch or Thermatel® TD1/TD2 thermal dispersion switch
- For continuous level:
Eclipse® Model 706 guided wave radar transmitter
- For visual indication:
Atlas or Aurora® magnetic level indicators
For more information on level measurement solutions for amine treatment and other natural gas processing applications, download the natural gas processing brochure.