Care must be taken to correctly design and size the upstream piping, inlet nozzle and of course the inlet device of a separator as these are all of paramount importance for the correct operation of the “total” separator.

Literally hundreds of separators worldwide suffer unnecessary problems with regards to separation performance, due to undersized upstream piping (often sized based on the choice / size of inlet device / nozzle) or the incorrect choice of inlet device or inlet devices that are operating well beyond their respective design points.

There are many different types of inlet devices available on the market for insertion into separator vessels, each having its own operational parameters, attributes and efficiency; historically the most common types have been “deflector plates”, “simple baffle type”, “inverted dished heads”, “pall ring boxes” and “half open pipes” amongst many others. Today though, more Contractors and Operators are moving away from these types of inlet devices towards the more advanced designs, as they understand the importance of a correctly designed inlet device and the functions undertaken by the different types.

Inlet devices are installed in both horizontal and vertical separators to;
	Minimise the size of the upstream piping and inlet nozzle.
	Minimise Droplet Shatter.
	Reduce the feed stream’s momentum.
	Separate “bulk” liquids.
	De-foam the incoming fluid.
	Ensure good gas and liquid distribution onto the downstream equipment.
	Prevent re-entrainment of liquid from the gas / liquid interface.
	Prevent mixing at the liquid / liquid interface.

Applying a momentum criteria “pv²”, to size the inlet nozzle and inlet device, commonly overcomes the problem of under sizing, i.e. the momentum of the incoming feed shall not exceed a “prescribed level” for an inlet nozzle designed with a generic type of inlet device (erosional velocities are also reviewed).

This method is a very common design parameter used by many operators, contractors and “process houses” in determining the correct size of the inlet nozzle. Dependant on the application, the higher the pv², then the smaller the inlet nozzle and in many cases the upstream piping, thus, a correctly designed inlet device can lead to a reduction in Capital Expenditure (CAPEX) as well as increasing the performance of the separator.

It is obviously important however to choose the correct type of inlet device and the correct values of the momentum criteria “pv²”, for the design. If not, then there is the likelihood that the upstream piping and inlet device, may actually cause problems such as droplet shatter and mal-distribution over the downstream equipment leading to a dramatic drop in the performance of the separator. Whilst mal-distribution of the liquids can cause severe turbulence in the liquid separation section thus reducing the separation efficiency, in the majority of horizontal vessels, an “inlet-processing zone” is created with the correct choice of an accompanying distribution baffle. Whilst the definitive sizing criteria is proprietary, we summarise the general attributes of commonly supplied inlet devices below.

Type of Inlet Device	Attributes of the Inlet Devices
None	V. Poor	V. Poor	Av.	Poor	V. Poor	V. Poor	V. Poor	V. Low
Simple Baffle	V. Poor	V. Poor	Av.	Poor	V. Poor	V. Poor	V. Poor	V. Low
Half Open Pipe	V. Poor	Av.	Av.	Av.	Poor	V. Poor	Poor	V. Low
Standard Vane Inlet Device	Good	V. Good	Good	Good	Av.	Good	Good	High
Adapted Vane Inlet Device + CFD (note 2)	Good +	V. Good	Good	Good	Av.	Good	Good	V. High
Inlet Cyclones	V. Good	V. Good	V. Good	V. Good	V. Good	V. Good	V. Good	V. High
ZPV Inlet Device (Rainmaker) (note 3&4)	V. Good	V. Good	V. Good	Good	Av.	V. Good	Good	V. High
ZSQ Inlet Device (Squirrel) (note 5)	V. Good	V. Good	V. Good	N/A	N/A	Good	N/A	V. High
ZLE Inlet Device (note 4)	V. Good	V. Good	V. Good	Good	Av.	V. Good	Good	V. High

Note 1: Downstream Distribution Baffles should ideally be added in horizontal vessels
Note 2: Computational Fluid Dynamics (CFD)
Note 3: For Horizontal Designs of Separators Only
Note 4: Low GOR
Note 5: For Degassing and Enhanced Oil Recovery Only