specifying separators
TRANSCRIPT
-
7/23/2019 Specifying Separators
1/33
Specifying Separators
Basic parameters: temperature, pressure, flow rates, physicalproperties of the fluids as well as degree of separation
Define time frame of separation occurrence
For known fluids, specify type and amount, also state ie. mist, freeliquid or sludge
Select worst case scenario and apply safety factors: safer to ewrong on the right side!
A compressor suction scrubber designed for 70-150 MMscfd gas at 400-600 psig
and 65-105 oF would require the separator manufacturer to offer a unit sied for the
worst conditions! ie" 150 MMscfd at 600 psig and 105 oF
-
7/23/2019 Specifying Separators
2/33
ecifying Separators
Basic design equations for
separators with mist
e"tractors #$ertical%:
critical #elocit$ %ma&'
correlation
b$ (ounders and )rown
*m+ ma&imum allowable gas mass-#elocit$
necessar$ for particles of sie ,pto drop or
settle out of gas
sec)/()(ftKV
g
gl
t
=
)./()( 2fthrlbCG glgm =
Separator TypeK factor
(ft/sec)
C factor
(ft/hr)
Horizontal (w/verticalpad)
0.4 50 0.5 1440 to1800
Spherical 0.2 to 0.35 720 to
1260
ertical or Horizontal(w/horiz. !ad)
"at# pre$$%re
"300 p$i&
"600 p$i&
"'00 p$i&
"1500 p$i&
0.18 to0.36
0.36
0.33
0.30
0.27
0.21
648 to1260
1260
1188
1080
'72
756
et Stea# 0.25 '00
o$t apor %nder vac%%# 0.20 720
Salt and *a%$tic+vaporator$
0.15 540
,ote-
(1) 0.35 "100 p$i& $%tract 0.01 or ever100 p$i aove 100 p$i&
(2) or &lcol and a#ine $ol%tion$ #%ltipl 0.6 0.8
(3) picall %$e one hal o the aove or *val%e$ or approi#ate $izin& o vertical$eparator$ witho%t woven de#i$ter$
(4) or co#pre$$or $%ction $cr%er$ andepander inlet $eparator$ #%ltipl 0.70.8
-
7/23/2019 Specifying Separators
3/33
-
7/23/2019 Specifying Separators
4/33
-
7/23/2019 Specifying Separators
5/33
Specifying Separators
1ass flow rates:
0n most instances it is con$enient to use mass flow rate for
si'ing purposes. 2hen handling gas flows, the flow is gi$en in
$olume flow rate #11S+FD%
3he fraction of the total area a$ailale for gas flow
can e found using the following tale
gtVM 3600=
FMdm 2785.0=
h/D F
0 1
0.0
5
0.'8
1
0.1 0.'48
0.15
0.'06
0.2 0.858
0.25
0.804
h/D F
0.30
0.748
0.35
0.688
0.40
0.626
0.45
0.564
0.5
0
0.5
0.5 0.43
:
h
-
7/23/2019 Specifying Separators
6/33
-
7/23/2019 Specifying Separators
7/33
8"ample
A horiontal gra#it$ separator % without mist e&tractor' is required to
handle 60 MMscfd %"2 .b3s' of 0"75 specific gra#it$ gas %M
1"7' at a pressure of 500 psig and a temperature of 100 F"
compressibilit$ is 0"! #iscosit$ is 0"01 cp and liquid specific
gra#it$ is 0"50" .t is desired to remo#e all entrainment greater than
150 microns in diameter" o liquid surge is required"
ote8
1 micron 0"00007 in
MMscfd 1000000 ft3da$
-
7/23/2019 Specifying Separators
8/33
-
7/23/2019 Specifying Separators
9/33
8"ample
(olution
Assume a diameter! ,# "5 ft
?essel
-
7/23/2019 Specifying Separators
10/33
-
7/23/2019 Specifying Separators
11/33
-
7/23/2019 Specifying Separators
12/33
Separators with 2ire 1esh 1ist 8"tractors
-
7/23/2019 Specifying Separators
13/33
Separators with 2ire 1esh 1ist 8"tractors
8"ample 9
2hat si'e of $ertical separator equipped with a wire mesh mist
e"tractor is required for conditions used in the pre$ious e"amples
From tale for $alues: ; 5.9 ft
-
7/23/2019 Specifying Separators
14/33
Separators with 2ire 1esh 1ist 8"tractors
= ; >.4 ft-
7essel 0D ; >5 in
ftDv 59.4=
-
7/23/2019 Specifying Separators
15/33
Separators with 7ane 3ype 1ist 8"tractors
?o draining ack through rising gas stream
= downcomer is used to routes
liquid out to drain
0nertia forces liquid droplets
against the $ane walls
@ffer similar separation performance to wire mesh with the addedad$antage of higher resistance to plugging and cane e easily
installed in smaller $essels
3he dependence on inertial forces can e a disad$antage at
reduced production rates
-
7/23/2019 Specifying Separators
16/33
Aetention 3ime in Separators
Liquid retention time
6 ;etention ti#e i$ avera&e ti#e a li
-
7/23/2019 Specifying Separators
17/33
Aetention 3ime in Separators
Oi/!ater retention time
6 ,eed certain a#o%nt o oil $tora&e $o that oil reache$e
-
7/23/2019 Specifying Separators
18/33
-
7/23/2019 Specifying Separators
19/33
-
7/23/2019 Specifying Separators
20/33
-
7/23/2019 Specifying Separators
21/33
-
7/23/2019 Specifying Separators
22/33
)iquid)iquid Separators
Di$ided into - road separation categories: gra$ity and coalescing
&ori'ontal and $ertical separators share the same principles of
separationG hori'ontal separators ha$e the ad$antage of a larger
surface area
- factors affecting gra$ity separation in the liquid phase:
6 e"tra fine particles with random mo$ement
6 electric charge from dissol$ed ions #repelling instead of
coalescing%
Separator si'ing is ased on StokesH )aw
-
7/23/2019 Specifying Separators
23/33
-
7/23/2019 Specifying Separators
24/33
)iquid)iquid Separators
7alues of +I
"musion
Charactersitics
Dropet
diameter(microns)
C#
ree li
-
7/23/2019 Specifying Separators
25/33
-
7/23/2019 Specifying Separators
26/33
Separators with +entrifugal 8lements
8"ample 4
Determine the si'e of a $ertical separator to handle >55 pd of 44 o=0 condensate
and 45 pd of produced water. =ssume the water particle si'e is -55 microns.
@ther operating conditions are as follows:
@perating temperature ; 5 F@perating pressure ; 555 psig
2ater specific gra$ity ; .5
+ondensate $iscosity ; 5.44 cp J 5 F
+ondensate specific gra$ity for 44o=0 ; 5.K>
For -55 microns, +I ; 55
2*
)785.0(
)(v
llhl
cl D
SS
CW
=
-
7/23/2019 Specifying Separators
27/33
Separators with +entrifugal 8lements
8"ample 4
Csing manufacturerHs std si'e $essels might result in specifying a -5! @D
separator
2)785.0(55.0
)76.001.1(1100/600 vDdaybbl
=
ftDv 24.1=
-
7/23/2019 Specifying Separators
28/33
Separators: +onstruction =spects
Farication specifications:
go$erned y specific codes and standards
=S18 pressure $essel code # the most widely used: Di$ and -%
BS
-
7/23/2019 Specifying Separators
29/33
Separators: +onstruction =spects
7essel Shell 3hickness
as specified y =S18 7000, Di$ #sect C3-K%
PSE
PR
t
6.0=
t thicEne$$;i internal radi%$ o $hell (ec. *orro$ion allowance)
;o eternal radi%$ o $hell
! worEin& pre$$%reS #ai#%# allowale $tre$$+ Foint eGcienc
:o%le elded D%tt oint%ll radio&raphed 1.0Spot radio&raphed 0.85
,o radio&raphed 0.70
Sin&le elded D%tt oint%ll radio&raphed 0.'Spot radio&raphed 0.80,o radio&raphed 0.65
PSE
PRt
!
4.0+=
PSE
PRt
2.0=
Sphere$-
-
7/23/2019 Specifying Separators
30/33
Separators: +onstruction =spects
2eight and Deck =rea calculations
3he weight of the internals #2i% may e estimated from the following tale:
dtWb 15= #a$$ per %nit len&th (C#/t)d internal dia#eter int wall thicEne$$ (inc. corro$ion allowance) in
For skidded equipment the following factors ha$e een
found satisfactory for preliminary estimates:
iping, 2p6 /5M of 2$8lectrical and 0nstumentation, 2e6 M of 2$
Skid Steel, 2s6 5M of 2$2skid ; 2$( 2p( 2e( 2s
-
7/23/2019 Specifying Separators
31/33
Separators: +onstruction =spects
3he total weight of the $essel can now e estimated using:
2$; 2) ( 20( 2?
-
7/23/2019 Specifying Separators
32/33
-
7/23/2019 Specifying Separators
33/33
Separators: 0nstrumentation and +ontrols
)iquid residence time and control