Sep Era Tors System

8/4/2019 Sep Era Tors System

http://slidepdf.com/reader/full/sep-era-tors-system 1/14

Separator location (Piping Topology Design)

The separators can be located:

1) At the power station:

2) At satellite stations in the field:



3) At the wellheads (Separator for each well):



SepSepSepSepaaaaratorsratorsratorsrators

A vessel used to separate a mixed-phase stream into gas and liquid phases that are

“relatively” free of each other.

Separators are usually characterized by orientation as vertical or horizontal.



Regardless of shape, separation vessels usually contain four major sections plus the

necessary controls.

Sections:

A: Inlet device:

The inlet device is used to reduce the momentum of the inlet flow stream, perform aninitial bluk separation of the gas and liquid phases and enhance gas flow distribution.

B: Gas gravity separation

The gas gravity separation section is designed to utilize the force of gravity to separateentrained liquid droplets from the gas phases, preconditioning the gas for final polishingby the mist extractor. It consists of a portion of the vessel though which the gas moves ata relatively low velocity with little turbulence.

C: Liquid gravity separation

The liquid gravity separation section acts as a receiver for all liquid removed from thegas in the inlet, gas gravity and mist extraction sections. In two-phase separationapplications the liquid gravity separation section provides residence time for degassingthe liquid. Depending on the inlet flow characteristics, the liquid section should have acertain amount of surge volume or slug catching capacity in order to smooth out the flowpassed on the downstream equipment or processes.

D: Mist extration

The mist extraction section utilizes the mist extractor that can consist of a knitted wiremesh pad, a series of vanes or cyclone tubes. This section removes the very smalldroplets of the liquid from the gas by impingement on a surface where they coalesce intolarger droplets or liquid films.



Liquid droplets will settle out of a steam phase if the gravitational force acting on thedroplet is greater than the drag force of the gas flowing around the droplet.

Terminal or finite settling velocity,

= 2 −

= 4 − 3

where

droplet diameter′ drag coefficient of particle dimensionless



= 0.95 10! " − #

Droplet diameter:

= $%& ' # − (

Stoke’s law < 2

= 1488 − 18 #

= 2 = > $%& =0.025



Intermediate law 2 < < 5 0 0

= 3.49 ,.-

./

−

,.-

,. #,./" = 5 0 0 = > $%& =0.334

Newton’s law 500<<200000

=1.74 −

=200000=> $%& =18.13

Vertical separator Vertical separator Vertical separator Vertical separator

Two phase flow enters the cyclone separator tangentially.

Steam is collected from the center by a standpipe, emerging from the bottom.

Steam passes through a ball check valve (BCV) and flows to the power station.

Moisture remover is located directly outside the powerhouse.





Separator and moisture remover design guidelinesSeparator and moisture remover design guidelinesSeparator and moisture remover design guidelinesSeparator and moisture remover design guidelines

(Weber approach and Lazalde-Crabtree guidelines for high quality steam)

Figure: Cyclone separator

Figure: Cyclone moisture remover



Steam velocitySteam velocitySteam velocitySteam velocity

Void fraction is the ratio of the steam (gas) flow cross section to the total cross section,

=

Void fraction

- Homogenious:

- Lockhart and Mertinelli:

- The seventh power law:

where,

: Gas or steam density (kg/m3)# : Gas or steam viscosity (kg / ( m s))

6 : Liquid or water density (kg/m3)#6 : Liquid or water viscosity (kg / ( m s))

Steam velocity at the two phase inlet pipe,

= :;

where,

? : Total massflow (kg/s)@ : Steam quality

Upward annular steam velocity,

A = ? @ B − C where,

B = D/ E(

BSeparator diameter (m))

C = D/ C (C Outlet steam pipe diameter (m))



Gravity Settling Laws and Particle Characteristics:



Horizontal separatorHorizontal separatorHorizontal separatorHorizontal separator

Horizontal separators are more efficient when large volume of liquid are involves and

have certain advantages with respect to gravity separation performance in that liquid

droplets bubbles are moving perpendicular to the bulk phase velocity.



The length of the vessel required can be calculated by assuming that the time for the gas

flow from the inlet to the outlet be the same as the time for the liquid droplet of size

to fall to the liquid surface,

F = 4 GH I

G : Actual gas flow rate

I : Inside diameter of vessel



Wire meshWire meshWire meshWire mesh

The gas capacity of mesh pads is almost universally specified by a load or sizing factor $

= $ −

The required mist extractor area = G

Documents

Sep Era Tors System