Technologies for Generation and Heat Exchange
Sadiq J. Zarrouk
Senior Lecturer (Geothermal Engineering)
Talk Outlines
• Challenges in Conventional Steam Plants (Separators)
• New Directions in Surface Facility
(Total Flow Machines)
• Heat Exchangers in Geothermal Development.
Geothermal System
From Moon (2012)
Role of Geothermal Separator
Production Well
Separator
CondensateReinjection Well
Scrubber
2-Phase Fluid
G
BrineReinjection Well
Steam Turbine
Condenser
Cooling Tower
Hot Well Pump
NCGRemoval
Reinjection Pump
Circulation Pump
Early Separators in Wairakei
U-Bend Separator
(From Grigg, 1956)
Vertical Separators
Steam Outlet
Inlet
Water Outlet
De
D
Db
z
β
Dt
α
LT
LB
Spiral Two Phase Inlet
Tangential Two Phase Inlet
TOC BOC From Zarrouk and Purnanto (2014)
Horizontal Separator
E-12E-10E-6
L
D
Mixture fluid in Steam out
Brine out
Water
Baffles
A
A
A A
Mist EliminatorSteam out
Ball Check
Valve
Baffles
Water
Ball Check
Valve
From Zarrouk and Purnanto (2014)
Separation Quality
98.8
99
99.2
99.4
99.6
99.8
1000
0.2
0.4
0.6
0.8
1
1.2
0 10 20 30 40 50 60 70 80 90
Ou
tlet
Ste
am Q
ual
ity
( %
)
Mas
s W
etn
ess
of
Ou
tlet
Ste
am (
%)
Steam Velocity at Separator Inlet (m/sec)
WK 30 (Bangma, 1960)
WK 44 (Bangma, 1960)
Lazalde-Crabtree (1984)
From Zarrouk and Purnanto (2014)
The Location of the Separator?
• Well head, Satellite or Centralised?
Production Well
Separator
CondensateReinjection Well
Scrubber
2-Phase Fluid
G
BrineReinjection Well
Steam Turbine
Condenser
Cooling Tower
Hot Well Pump
NCGRemoval
Reinjection Pump
Circulation Pump
11
Total Flow (BiPhase) Machines
Simple Total Flow System
12
TFC System Using a Working Fluid
From Smith et al (2005)
Screw Expander
Simple System
Modular Units
1-3 MWe Units
Waste Heat Steel Mile (China)
2 X 1 MWe Units at the Yangbajain Geothermal Field in Tibet running since 2008 and 2010
Heat Exchangers
Plate Heat Exchanger
Do
wn
ho
le Pu
mp
Production well
Re-Injection well
Main Plate Heat Exchangers Secondary
Plate Heat Exchangers
Primary fluid line (Geo)
Secondary fluid line
Master Valve
Secondary water circulating pumps
Problems in Plate Type Heat Exchanger
GI Records
DHE
Steins and Zarrouk (2012)
Improving DHE Performance with airlift
Types of geothermal system 22 Steins and Zarrouk (2012)
Shell and Tube Heat Exchanger
Two Shell Passes and Four Tube Passes
24
Large size Heat Exchangers
• Large Shell and Tube heat Exchanger tubes may fail due to excessive vibration generated by the shell-side fluid flow around and between tubes. There are several mechanisms that can cause vibration, but fluid-elastic instability is the most sever mechanism, which can cause tube damage in a very short time.
Erosion corrosion of
an inner shell wall
of a heat exchanger
26
Tongonan field, Philippines, Angcoy et al. (2005)
Multi-pass Flow Arrangement
27 Steins and Zarrouk (2012)
Silt Build-up
Steins and Zarrouk (2012)
29
Silica Deposition (shark skin) in Binary Plant Heat Exchanger Tubing
From Zarrouk et al (2014)
Scanning electron microscope micrograph
30
From Zarrouk et al (2014)
High density vitreous silica scale
31 From Zarrouk et al (2014)
Impact on Generation (Shark Teeth)
0
5
10
15
20
25
30
35
0
500
1000
1500
2000
2500
3000
3500
July 2005 July 2006 July 2007 July 2008 July 2009 July 2010 July 2011
Gro
ss P
ow
er
Ou
tpu
t (M
W)
Flo
w R
ate
(to
nn
e/h
r)
Date
Flow Through Both Power Plants Total Power Generated
From Zarrouk et al (2014)
Thank you
Questions ?
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