US2010294472A1PendingUtilityA1
Use of a duplex stainless steel in a phosphoric acid production system
Assignee: SANDVIK INTELLECTUAL PROPERTYPriority: Oct 26, 2007Filed: Oct 24, 2008Published: Nov 25, 2010
Est. expiryOct 26, 2027(~1.2 yrs left)· nominal 20-yr term from priority
F28F 21/08C22C 38/58C22C 38/54C22C 38/52C22C 38/44C22C 38/42F28F 21/083C22C 38/001
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Claims
Abstract
The present disclosure relates to the use of a duplex stainless steel as heat exchanger material in a phosphoric acid production system using the wet method. The steel has the following composition in percent by weight: C max 0.03 Si max 0.5 Mn max 3 Cr 26-29 Ni 4.9-10 Mo 3-5 N 0.35-0.5 B max 0.0030 Co max 3.5 W max 3 Cu max 2 Ru max 0.3 balance Fe and normal occurring impurities.
Claims
exact text as granted — not AI-modified1 . Heat exchanger for use in environments containing phosphoric acid, said heat exchanger comprising at least one tube of a duplex stainless steel with the following composition in percent by weight:
C
max 0.03
Si
max 0.5
Mn
max 3
Cr
26-29
Ni
4.9-10
Mo
3-5
N
0.35-0.5
B
max 0.0030
Co
max 3.5
W
max 3
Cu
max 2
Ru
max 0.3
balance Fe and normal occurring impurities.
2 . Heat exchanger according to claim 1 wherein the tube is a seamless tube.
3 . Heat exchanger according to claim 1 wherein the duplex stainless steel comprises 26.5-28% Cr.
4 . Heat exchanger according to claim 1 wherein the duplex stainless steel comprises max 1.2% Cu.
5 . Heat exchanger according to claim 1 wherein the duplex stainless steel comprises 0.5-3.5% Co.
6 . Heat exchanger according to claim 1 wherein [wt-% Cr]+3.3([wt-% Mo]+0.5[wt-% W])+16[wt-% N] is at least 45.
7 . Heat exchanger according to claim 1 wherein it is adapted to be in direct contact with a process solution containing phosphoric acid.
8 . Phosphoric acid production system comprising an evaporator having a heat exchanger, said heat exchanger comprising at least one tube of a duplex stainless steel with the following composition in percent by weight:
C
max 0.03
Si
max 0.5
Mn
max 3
Cr
26-29
Ni
4.9-10
Mo
3-5
N
0.35-0.5
B
max 0.0030
Co
max 3.5
W
max 3
Cu
max 2
Ru
max 0.3
balance Fe and normal occurring impurities.
9 . Phosphoric acid production system according to claim 8 wherein the heat exchanger is adapted to be in direct contact with a process solution containing phosphoric acid.
10 . Phosphoric acid production system according to claim 8 wherein the tube is a seamless tube.
11 . Phosphoric acid production system according to claim 8 wherein the duplex stainless steel comprises 26.5-28% Cr.
12 . Phosphoric acid production system according to claim 8 wherein the duplex stainless steel comprises max 1.2% Cu.
13 . Phosphoric acid production system according to claim 8 wherein the duplex stainless steel comprises 0.5-3.5% Co.
14 . Phosphoric acid production system according to claim 8 wherein [wt-% Cr]+3.3([wt-% Mo]+0.5[wt-% W])+16[wt-% N] is at least 45.
15 . Use of a duplex stainless steel with the following composition in percent by weight:
C
max 0.03
Si
max 0.5
Mn
max 3
Cr
26-29
Ni
4.9-10
Mo
3-5
N
0.35-0.5
B
max 0.0030
Co
max 3.5
W
max 3
Cu
max 2
Ru
max 0.3
balance Fe and normal occurring impurities in environments containing phosphoric acid.
16 . Use of a duplex stainless steel with the following composition in percent by weight
C
max 0.03
Si
max 0.5
Mn
max 3
Cr
26-29
Ni
4.9-10
Mo
3-5
N
0.35-0.5
B
max 0.0030
Co
max 3.5
W
max 3
Cu
max 2
Ru
max 0.3
balance Fe and normal occurring impurities as a tube in a heat exchanger in environments containing phosphoric acid.
17 . Use according to claim 16 wherein the heat exchanger is a heat exchanger in an evaporator in a phosphoric acid production system using the wet method.
18 . Use according to claim 15 in environments containing 30-80% H 3 PO 4 , up to 2000 ppm Cl″ and up to 2% F″.
19 . Use according to claim 15 at temperatures up to 110° C.
20 . Use according to claim 15 in fertilizer production plants.Join the waitlist — get patent alerts
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