More and more reports from industry reflect the presence of elemental sulfur deposition in pipelines, regulators, flow meters, and downstream process equipment.
Sulfur Absorbent Technology
PROBLEMS INCLUDE:
- Erratic flow meter readings
- Turbine damage
- Plugged control valves and regulators leading to
- Regulator failure (pilot or main valve)
- System overpressure if the valve fails to close
- Heavy maintenance requirements to prevent a shutdown of operations
The problem cannot be filtered out because the elemental sulfur is dissolved in the vapor phase. It is not a particulate or dust, but is dissolved in the vapor phase much like water or CO2. After the pipeline particulates have been removed, further filtration only induces a pressure loss and accompanying Joule-Thompson cooling. This lowers the solubility of elemental sulfur and causes additional elemental sulfur to leave the vapor phase and deposit on downstream equipment. It is not uncommon to see a filter housing with a clean inlet and an outlet that is coated with a yellow colored dust. The Bechtel Sulfur Adsorbent Technology (BSAT) solves the root cause of this problem.
The BSAT system is located downstream of any pipeline pig collection system, slug catcher, and the primary filter separator. The first particulate filter catches any small pipeline particulates that might plug the adsorbent; the second particulate filter after the Adsorbent is to catch any adsorbent fines that might slip out of the adsorbent vessel.
SAT System
Due to the low concentrations of sulfur in natural gas, the vessel size is governed by pressure loss rather than capacity. The unit design results in an expected life of 3-5 years based on a sulfur saturated inlet gas.
BENEFITS
- Under pipeline conditions, the sulfur adsorbs onto the active surface area and stays on the adsorbent until pressure is reduced or temperature is increased.
- No chemicals needed for processing other than the adsorbent, which is changed about every 3-5 years
- Filters are the only regular consumables
- No heating, cooling, or pumping required
- Minimal operator attention
- Treats the real problem (the presence of sulfur) instead of treating symptoms (plugged equipment)