Heat transfer enhancement pipe as well as cracking furnace and atmospheric and vacuum heating furnace including the same
The present invention relates to the field of fluid heat transfer, and discloses a heat transfer enhancement pipe as well as a cracking furnace and an atmospheric and vacuum heating furnace including the same. The heat transfer enhancement pipe ( 1 ) includes a pipe body ( 10 ) of tubular shape having an inlet ( 100 ) for entering of a fluid and an outlet ( 101 ) for said fluid to flow out; the internal wall of the pipe body ( 10 ) is provided with a fin ( 11 ) protruding towards the interior of the pipe body ( 10 ), the fin ( 11 ) spirally extends in an axial direction of the pipe body ( 10 ), wherein at least one of a heat insulator ( 14 ) and a heat insulating layer ( 17 ) is provided at the outside of the pipe body ( 10 ). The heat transfer enhancement pipe can reduce thermal stress of itself, thereby increasing service life of the heat transfer enhancement pipe.
1 . A heat transfer enhancement pipe comprising:
a pipe body of tubular shape having an inlet for entering of a fluid and an outlet for the fluid to flow out;
wherein:
an internal wall of the pipe body is welded at a welding site with a fin protruding towards an interior of the pipe body,
the fin spirally extends in an axial direction of the pipe body,
the heat transfer enhancement pipe is configured to conduct heat transfer between the interior and the outside of the pipe body, and
at least one of a heat insulator and a heat insulating layer is provided outside of the pipe body and configured to reduce thermal stress of the fin at the welding site during operation, wherein the fin comprises a first end surface closest to the inlet and a second end surface closest to the outlet, the first end surface or the second end surface of the fin having a concave shape in a cross-section of the fin parallel to the axial direction of the pipe body and configured to reduce thermal stress at the welding site during operation.
2 . The heat transfer enhancement pipe according to claim 1 , wherein the heat insulator at least partially surrounds an external circumference of the pipe body.
3 . The heat transfer enhancement pipe according to claim 2 , wherein the heat insulator has a tubular shape and is configured to be sleeved on the outside of the pipe body.
4 . The heat transfer enhancement pipe according to claim 3 , wherein a gap is left between the heat insulator and an external wall of the pipe body.
5 . The heat transfer enhancement pipe according to claim 4 , wherein a connector for connecting the heat insulator and the pipe body is arranged between the heat insulator and the pipe body.
6 . The heat transfer enhancement pipe according to claim 5 , wherein the connector comprises:
a first connecting piece that extends in an axial direction parallel to the pipe body.
7 . The heat transfer enhancement pipe according to claim 2 , wherein the heat insulator comprises:
a straight pipe section having a first end and a second end;
a first tapered pipe section; and
a second tapered pipe section, the first tapered pipe section and the second tapered pipe section configured to be respectively connected to the first end and second end of the straight pipe section;
wherein the first tapered pipe section is tapered in a direction from close to the first end to away from the first end; and
the second tapered pipe section is tapered in a direction from close to the second end to away from the second end.
8 . The heat transfer enhancement pipe according to claim 1 , wherein a heat insulating layer is provided on an external surface of the pipe body.
9 . The heat transfer enhancement pipe according to claim 8 , wherein the heat insulating layer comprises a metal alloy layer outside of the external surface of the pipe body and a ceramic layer outside of the metal alloy layer.
10 . The heat transfer enhancement pipe according to claim 9 , wherein the heat insulating layer comprises an oxide layer between the metal alloy layer and the ceramic layer.
11 . The heat transfer enhancement pipe according to claim 10 , wherein the thickness of the oxide layer is 3-5 μm; and/or the oxide layer is prepared and formed by alumina, silica, titania, or a mixture of any two or more materials selected from alumina, silica, and titania.
12 . The heat transfer enhancement pipe according to claim 9 , wherein the thickness of the metal alloy layer is 50-100 μm; and/or the metal alloy layer is prepared and formed by metal alloy materials including M, Cr, Al, and Y, wherein M is selected from one or more of Fe, Ni, Co, and Al.
13 . The heat transfer enhancement pipe according to claim 12 , wherein the metal alloy layer further comprises one or more additive materials selected from Si, Ti, Co, and Al 2 O 3 .
14 . The heat transfer enhancement pipe according to claim 9 , wherein the thickness of the ceramic layer is 200 to 300 μm; and/or the ceramic layer is prepared and formed by one or more materials selected from yttria-stabilized zirconia, magnesia-stabilized zirconia, calcia-stabilized zirconia, and ceria-stabilized zirconia.
15 . The heat transfer enhancement pipe according to claim 8 , wherein the heat insulating layer comprises:
a straight section having a first end and a second end;
a first tapered section; and
a second tapered section, the first tapered section and the second tapered section configured to be respectively connected to the first end and second end of the straight section,
wherein the first tapered section is tapered in a direction from close to the first end of the straight section to away from the first end of the straight section; and
the second tapered section is tapered in a direction from close to the second end of the straight section to away from the second end of the straight section.
16 . The heat transfer enhancement pipe according to claim 1 , wherein a height of the fin gradually increases from one end for at least a partial extension of the fin.
17 . The heat transfer enhancement pipe according to claim 1 , wherein a first end surface of the fin facing the inlet is formed as a first transition surface along a spirally extending direction and has a concave shape.
18 . The heat transfer enhancement pipe according to claim 1 , wherein a second end surface of the fin facing the outlet is formed as a second transition surface along a spirally extending direction and has a concave shape.
19 . The heat transfer enhancement pipe according to claim 1 , wherein a top surface of the fin facing a central axis of the pipe body is formed as a third transition surface of a concave shape.
20 . A cracking furnace or atmospheric and vacuum heating furnace, comprising:
a radiation chamber, in which at least one furnace pipe assembly is installed;
wherein the at least one furnace pipe assembly comprises a plurality of furnace pipes arranged in sequence and a heat transfer enhancement pipe communicating adjacent furnace pipes; and
the heat transfer enhancement pipe is the heat transfer enhancement pipe according to claim 1 .
21 . The heat transfer enhancement pipe according to claim 6 , wherein the connector comprises a second connecting piece that extends spirally along the external wall of the pipe body.
22 . The heat transfer enhancement pipe according to claim 21 , wherein the connector comprises a connecting rod with two ends respectively connected to the external wall of the pipe body and an internal wall of the heat insulator.