Supersonic gas-liquid separation is considered as one of the novel methods for natural gas conditioning that removes either water or heavy hydrocarbons from the natural gas without using chemical ingredients. The expansion of natural gas stream in a supersonic nozzle increases the fluid velocity to supersonic level and makes low pressure and temperature conditions in which nucleation of the liquid phase and condensation initiate. The process includes two isentropic processes with an intermediate shockwave. This research is the first serious attempt for controlling the supersonic separation units and applies the stability concept for actual conditions and disturbances in the gas pressure and composition during the lifecycle of a gas well. The article explores how the optimal performance of a supersonic nozzle can be saved with variations in the nozzle input gas pressure or composition. As the phase change and condensation are mainly occur at the shockwave position, the geometry configuration of supersonic nozzle is of high importance so that the drain location should be aligned with the shockwave location. An algorithm is employed to find a control function to compensate the backpressure of the nozzle within the feed pressure variation. It guarantees the equipment to be kept effectively in the optimal operating condition. In a case study, it is explained how the proposed solution enables the system to keep the dew point within ±2.5 °C drift from the desired criteria following a ±18% disturbance in the inlet pressure. Moreover, investigation on the effect of natural gas composition shows that the separation system is intrinsically robust to variations in the main natural gas composition.
|Number of pages||6|
|Journal||Journal of Natural Gas Science and Engineering|
|Early online date||4 Apr 2017|
|Publication status||Published - Jul 2017|
Bibliographical notePublisher Copyright:
© 2017 Elsevier B.V.
- Dew point conditioning
- Dynamic simulation
- Gas composition
- Pressure compensation
- Stability control
- Supersonic nozzle
ASJC Scopus subject areas
- Energy Engineering and Power Technology