Vane Type Inlet Devices

Construction Materials

• Stainless steels
• Duplex steels
• Special alloys
• Typical Applications
• Compressor suction drums
• Two- and three-phase separators
• Knock-out drums
• TEG contactors

Characteristics and benefits

Vane Type Inlet Devices are designed in such a way to ensure that the feed is entering the vessel in an ideal manner.

When a fluid stream strikes a solid surface, it reduces its momentum by exerting a force on that surface, and an equal but opposite force is exerted on itself. If this force is too great, liquid shatter can occur when the surface
tension forces of the liquid are overcome. In order to avoid liquid shatter, different types of inlet devices have been developed which can reduce the momentum. The sizing of nozzles is normally judged by the maximum ?.v² value, which depends on the type of inlet device that’s applied. Some examples of currently used values of ?v² throughout the industry for some of these types of inlet devices are as follows:
 

• No inlet device or simple baffle: ρv² ≤ 1,000 kg/ms²
• Half-open pipe inlet device: ρv² ≤ 1,500 kg/ms²
• V-baffle: ρv² ≤ 2,500 kg/ms²
• Vane-type inlet device: ρv² ≤ 15,000 kg/ms²

The reason that a Vane Type Inlet Device has a much higher maximum .v² value than for example a plain nozzle, half-open pipe or V-baffle, is that it combines several positive effects:

Prevents liquid shatter

The surfaces which the inlet stream strikes are gently curved and the open area available for it increases as the flow passes through it. This gradual increase in area steadily reduces the stream velocity, and therefore the required rate of change of momentum, or exerted force, thus leading to a fall in the probability of liquid shatter.
 

Evenly distributes the gas over the vessel area

If an uneven distribution is present on the upstream face of the mist eliminator, it could flood due to a combination of localized high gas and liquid loading, and lead to possible excessive liquid carryover.
 

Avoids re-entrainment

The gas will be diverted towards the vessel shell and upwards (not downwards as for example is the case with a half-open pipe), thereby avoiding turbulence in the liquid sump and liquid pick-up from the sump.
 

Enhances pre-separation of bulk liquid

As the stream velocity is reduced, the liquid will enter the vessel in a calmer manner which will reduce the possibility of entrainment and therefore the liquid loading towards downstream separation equipment.