1. A bimetallic tube for fired heater tubes andor transfer line exchangers for the transport of hydrocarbon feedstocks in petrochemical process andor refinery process units, comprising:
i) an outer tube layer being formed from a steam cracker alloy comprising at least 18.0 wt. % Cr and at least 10.0 wt. % Ni;
ii) an inner tube layer being formed from an alumina forming bulk alloy comprising 5.0 to 10.0 wt. % of Al, 18.0 wt. % to 25.0 wt. % Cr, less than 0.5 wt. % Si, and at least 35.0 wt. % Fe with the balance being Ni, wherein the inner tube layer is formed by plasma powder welding the alumina forming bulk alloy on the inner surface of the outer tube layer; and
iii) an oxide layer formed on the surface of the inner tube layer, wherein the oxide layer comprises alumina, chromia, silica, mullite, spinets, or combinations thereof.
2. The bimetallic tube of claim 1, wherein the outer tube layer comprises at least 20.0 wt. % Cr and at least 30.0 wt. % Ni.
3. The bimetallic tube of claim 1, wherein the outer tube layer is a steam cracker alloy chosen from HP45Nb, HP16Nb, HN10NiNb, HP 40 Mod, Pompey HP 40W, Pompey Manaurite XM, Manaurite XTM, and Kubota KHR 45A.
4. The bimetallic tube of claim 3, wherein the outer tube layer is a steam cracker alloy of HP45Nb or HP16Nb.
5. The bimetallic tube of claim 1, wherein the inner tube layer comprises 5.0 wt. % to 8.0 wt. % of Al, 19.0 wt. % to 24.0 wt. % Cr, less than 0.5 wt. % Si, and at least 35.0 wt. % Fe with the balance being Ni.
6. The bimetallic tube of claim 1, wherein the inner tube layer further comprises less than 0.01 wt. % carbon.
7. The bimetallic tube of claim 1, wherein the inner tube layer further comprises 0.1 wt. % to 2.0 wt. % of at least one element chosen from Ga, Ge, As, In, Sn, Sb, Pb, Pd, Pt, Cu, Ag, Au and combinations thereof.
8. The bimetallic tube of claim 1, wherein the inner tube layer further comprises 0.1 wt. % to 2.0 wt. % of at least one element chosen from Re, Ru, Rh, Ir, Pd, Pt, Cu, Ag, Au and combinations thereof.
9. The bimetallic tube of claim 1, wherein the inner tube layer further comprises 0.01 wt. % to 2.0 wt. % of at least one element chosen from Sc, La, Y, Ce and combinations thereof.
10. The bimetallic tube of claim 1, wherein the inner tube layer further comprises 0.01 wt. % to 2.0 wt. % of oxide particles of at least one element chosen from Al, Si, Sc, La, Y, Ce and combinations thereof.
11. The bimetallic tube of claim 1, wherein the inner tube layer further comprises 0.01 wt. % to 4.0 wt. % of at least one element Chosen from Mn, Ti, Zr, Hf, V, Nb, Ta, Mo, W, and combinations thereof.
12. The bimetallic tube of claim 1, wherein the inner tube layer further comprises 0.1 wt. % to 30.0 wt. % of at least one intermetallic precipitate chosen from Ni3Al, NiAl, sigma-phase, and combinations thereof.
13. The bimetallic tube of claim 1, wherein the inner tube layer further comprises 0.01 wt. % to 5.0 wt. % of at least one inclusion chosen from an oxide, a carbide, a nitride, a carbonitride, and combinations thereof.
14. The bimetallic tube of claim 1, wherein the alumina forming bulk alloy has a porosity of less than 2.0 vol. %.
15. The bimetallic tube of claim 1, wherein the alumina forming bulk alloy has an average interior surface roughness (Ra) of less than 1.1 \u03bcm.
16. The bimetallic tube of claim 1, wherein the oxide layer formed on the surface of the inner tube layer comprises alumina.
17. The bimetallic tube of claim 1, wherein the oxide layer is a mono-layer or a multi-layer structure.
18. The bimetallic tube of claim 1, wherein the oxide layer ranges from 1 nm to 100 \u03bcm in thickness.
19. A method of making a bimetallic tube for fired heater tubes andor transfer line exchangers for the transport of hydrocarbon feedstocks in petrochemical process andor refinery process units, comprising the steps of:
i) providing an outer tube layer, wherein said outer tube layer is formed from a steam cracker alloy comprising at least 18.0 wt. % Cr and at least 10.0 wt. % Ni;
ii) plasma powder welding an inner tube layer on the inner surface of the outer tube layer, Wherein the inner tube layer is formed from an alumina forming bulk alloy comprising 5.0 to 10.0 wt. % of Al, 18.0 wt. % to 25.0 wt. % Cr, less than 0.5 wt. % Si, and at least 35.0 wt. % Fe with the balance being Ni; and
iii) forming an oxide layer on the surface of the inner tube layer, wherein the oxide layer comprises alumina, chromia, silica, mullite, spinets, or combinations thereof.
20. The method of claim 19, wherein the forming of the oxide layer on the surface of the inner tube layer occurs in-situ during use of the alumina forming bulk alloy when exposed to hydrocarbon process streams in petrochemical or refining process units.
21. The method of claim 19, wherein the forming of the oxide layer on the surface of the inner tube layer occurs prior to use by exposing the bimetallic tube material to a controlled low oxygen partial pressure environment.
22. The method of claim 21, wherein the controlled low oxygen partial pressure environment is chosen from refinery plant steam, petrochemical plant steam, a gaseous H2O:H2 mixture, and a gaseous CO2:CO mixture.
23. The method of claim 21, wherein the controlled low oxygen partial pressure environment further includes one or more other gases chosen from CH4, NH3, N2, O2, Ar, hydrocarbons and combinations thereof.
24. The method of claim 21, wherein the controlled low oxygen partial pressure environment temperature is from 500\xb0 C. to 1200\xb0 C.
25. The method of claim 21, wherein the controlled low oxygen partial pressure environment exposure time is from 1 hour to 500 hours.
26. The method of claim 19 further including densifying the inner tube layer by a method Chosen from post-annealing, tempering, laser melting and combinations thereof.
27. The method of claim 19 further including reducing the surface roughness of the inner tube layer by a method chosen from mechanical polishing, electro polishing, lapping and combinations thereof.
28. The method of claim 19, wherein the outer tube layer comprises at least 20.0 wt. % Cr and at least 30.0 wt. %.
29. The method of claim 19, wherein the inner tube layer comprises 5.0 wt. % to 8.0 wt. % of Al, 19.0 wt. % to 24.0 wt. % Cr, less than 0.5 wt. % Si, and at least 35.0 wt. % Fe with the balance being Ni.
30. A method of reducing corrosion, coking andor fouling in fired heater tubes and transfer tine exchangers for the transport of hydrocarbon feedstocks in refinery and petrochemical process operations comprising:
providing bimetallic tubes for the fired heater tubes andor the transfer line exchangers, wherein the bimetallic tubes comprise:
i) an outer tube layer being formed from a steam cracker alloy comprising at least 18.0 wt. % Cr and at least 10.0 wt. % Ni;
ii) an inner tube layer being formed from an alumina forming bulk alloy comprising 5.0 to 10.0 wt. % of Al, 18.0 wt. % to 25.0 wt. % Cr, less than 0.5 wt. % Si, and at least 35.0 wt. % Fe with the balance being Ni, wherein the inner tube layer is formed by plasma powder welding the alumina forming bulk alloy on the inner surface of the outer tube layer; and
iii) an oxide layer formed on the surface of the inner tube layer, wherein the oxide layer comprises alumina, chromia, silica, mullite, spinets, or combinations thereof.
31. The method of claim 30, wherein the out tube layer comprises at least 20.0 wt % Cr and at least 30.0 wt % Ni.
32. The method of claim 30, wherein the inner tube layer comprises 5.0 wt % to 8.0 wt. % of Al, 19.0 wt. % to 24.0 wt. % Cr, less than 0.5 wt. % Si, and at least 35.0 wt. % Fe with the balance being Ni.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A folding mechanism, comprising:
a first main body;
a second main body;
a hinge assembly fixed between the first main body and the second main body, the hinge assembly comprising a sleeve member and a fixing shaft, the sleeve member comprising a fixing portion and a sleeve portion, the fixing portion mounted on the first main body, the sleeve portion extending from an end of the fixing portion adjacent to the second main body, the fixing shaft inserted into the sleeve portion, and mounted to the second main body, at least one elastic strip protruding from the fixing portion towards the sleeve portion, at least one ridge protruding from the fixing shaft corresponding to the at least one elastic strip, the at least one elastic strip abutting against the fixing shaft.
wherein when the first main body is rotated relative to the second main body, the at least one elastic strip moves from one side of the ridge to another side of the ridge by slidably crossing over the ridge.
2. The folding mechanism of claim 1, wherein the fixing portion defines at least one opening corresponding to the at least one elastic strip, the at least one elastic strip extends from an inner surface of the opening towards the sleeve portion.
3. The folding mechanism of claim 2, wherein the at least one elastic strip is substantially arc-shaped.
4. The folding mechanism of claim 1, wherein an outer sidewall of the fixing shaft comprises a planar surface extending along an axis of the fixing shaft and an arcuate surface extending along the axis of the fixing shaft, the arcuate surface is connected to the planar surface, the ridge is a connecting edge portion between the planar surface and the arcuate surface.
5. The folding mechanism of claim 4, wherein the at least one elastic strip resists on the planar surface when in a closed state; and the at least one elastic strip slidably crosses over the ridge to reach to the arcuate surface, and elastically resist the arcuate surface when in an open state.
6. The folding mechanism of claim 1, wherein the first main body comprises a base body, and a mounting member extending from the base body towards the second main body, the mounting member defines a receiving groove, two ends of the mounting member each defines a containing groove communicating with the receiving groove, the sleeve member is received in the receiving groove, and the fixing shaft is received in the containing groove.
7. The folding mechanism of claim 6, wherein the first main body further comprises a resisting member integrated with the mounting member, and received in the receiving groove, the resisting member comprises a blocking plate, a first resisting portion, and a second resisting portion, the blocking plate is positioned along the longitudinal direction of the receiving groove, and separates the receiving groove into a first receiving groove and a second receiving groove, the first resisting portion and the second resisting portion interconnect the blocking plate and an inner sidewall of the second receiving groove, and are received in the second receiving groove, the fixing portion of the sleeve member is received in the first receiving groove, and positioned with an inner sidewall of the first receiving groove, the sleeve portion is received in the second receiving groove, and resists on the first resisting portion and the second resisting portion.
8. The folding mechanism of claim 7, wherein the first resisting portion comprises a first contacting surface, the second resisting portion comprises a second contacting surface, the first contacting surface and the second contacting surface are substantially arcuate, the sleeve member resists the first contacting surface and the second contacting surface.
9. The folding mechanism of claim 6, wherein the second main body defines a mounting groove, the mounting member is received in the mounting groove, each of two opposite ends of the second main body defines a fixing groove communicating with the mounting groove, the fixing shaft is fixed within the fixing grooves.
10. A hinge assembly, comprising:
a sleeve member comprising a fixing portion and a sleeve portion extending from an end of the fixing portion, at least one elastic strip protruding from the fixing portion towards the sleeve portion; and
a fixing shaft inserted into the sleeve portion, at least one ridge protruding from the fixing shaft corresponding to the at least one elastic strip, the at least one elastic strip abutting against the fixing shaft,
wherein when the sleeve member is rotated relative to the fixing shaft, the at least one elastic strip moves from a side of the ridge to another side of the ridge by crossing over the ridge.
11. The hinge assembly of claim 10, wherein the fixing portion defines at least one opening corresponding to the at least one elastic strip, the at least one elastic strip extends from an inner surface of the opening towards the sleeve portion.
12. The hinge assembly of claim 11, wherein the at least one elastic strip is substantially arc-shaped.
13. The hinge assembly of claim 10, wherein an outer sidewall of the fixing shaft comprises a planar surface extending along an axis of the fixing shaft and an arcuate surface extending along the axis of the fixing shaft, the arcuate surface is connected to the planar surface, the ridge is a connecting edge portion between the planar surface with the arcuate surface.
14. A folding mechanism, comprising:
a first main body;
a second main body;
a hinge assembly fixed between the first main body and the second main body, the hinge assembly comprising a sleeve member and a fixing shaft, the sleeve member comprising a fixing portion and a sleeve portion, the fixing portion mounted on the first main body, the sleeve portion extending from an end of the fixing portion adjacent to the second main body, the fixing shaft inserted into the sleeve portion, and mounted to the second main body, at least one elastic strip protruding from the fixing portion towards the sleeve portion, an outer sidewall of the fixing shaft comprising a planar surface and an arcuate surface connecting with the planar surface, the at least one elastic strip abutting against the outer sidewall of the fixing shaft.
wherein when the first main body is opening relative to the second main body, the at least one elastic strip moves from the planar surface to the arcuate surface via crossing over a connecting edge portion between the planar surface and the arcuate surface, when the first main body is closing relative to the second main body, the at least one elastic strip moves from the arcuate surface to the planar surface via crossing over the connecting edge portion between the planar surface and the arcuate surface.
15. The folding mechanism of claim 14, wherein the fixing portion defines at least one opening corresponding to the at least one elastic strip, the at least one elastic strip extends from an inner surface of the opening towards the sleeve portion.
16. The folding mechanism of claim 15, wherein the at least one elastic strip is substantially arc-shaped.
17. The folding mechanism of claim 14, wherein the connecting edge portion between the planar surface with the arcuate surface is a ridge.
18. The folding mechanism of claim 17, wherein the at least one elastic strip resists on the planar surface in a close state; and the at least one elastic strip crosses over the ridge to reach to the arcuate surface, and elastically resist the arcuate surface in an open state.