Abstract This disclosure teaches a finned tube (or studded tube or the like) for convection sections of process heaters or boilers to improve heat transfer and reduce pressure drops of both process streams and flue gas. Tubes in this service are preferably of carbon steel which is, within this context, a relatively-high heat-conducting but relatively-low heat-resisting material. The finned tube is made of at least two materials organized proximally and distally relative the tube wall to which it is connected and from which it projects outwardly. The distal portion is made of a relatively-high heat-resisting but relatively-low heat-conducting material such as stainless steel. The proximal portion may be of a material the same as that of the tube wall or it may be of a material with heat-conducting and heat-resisting properties intermediate those of the tube wall and of the distal portion.
A heat-transfer tube, for use in a convection section of a process heater or boiler and arrangeable therein for passage of a fluid therethrough in noncontact heat-exchange relationship with a relatively-hot gas having a temperature of from 1000* to 2000*F., and characterized by: a tube wall provided with at least one fin connected thereto and projecting outwardly therefrom; the fin having a proximal portion integrally secured to the tube wall and a distal portion remote from the tube wall; the distal portion continuous from the proximal portion and joined integrally thereto; the tuBe wall and the proximal portion made of low carbon steel; the distal portion made of a material selected from a group consisting of No. 410, No. 430, E2, No. 304 and No. 316 stainless steels.
Claim 2
Dependent Claim
128 words
A heat-transfer tube, for use in a convection section of a process heater or boiler and arrangeable therein for passage of a fluid therethrough in noncontact heat-exchange relationship with a relatively-hot gas having a temperature of from 1000* to 2000*F., and characterized by: a tube wall provided with at least one fin connected thereto and projecting outwardly therefrom; the fin having a proximal portion integrally secured to the tube wall and a distal portion remote from the tube wall; the distal portion continuous from the proximal portion and joined integrally thereto; the tuBe wall and the proximal portion made of low carbon steel; the distal portion made of a material selected from a group consisting of No. 410, No. 430, E2, No. 304 and No. 316 stainless steels.
Claim 3
Dependent Claim
15 words
The tube of claim 1 with the distal portion made of No. 410 stainless steel.
Claim 4
Dependent Claim
15 words
The tube of claim 1 with the distal portion made of No. 430 stainless steel.
Claim 5
Dependent Claim
14 words
The tube of claim 1 with the distal portion made of E2 stainless steel.
Claim 6
Dependent Claim
15 words
The tube of claim 1 with the distal portion made of No. 304 stainless steel.
Claim 7
Dependent Claim
15 words
The tube of claim 1 with the distal portion made of No. 316 stainless steel.
Claim 8
Dependent Claim
29 words
The tube of claim 1 with the proximal portion made of a material having heat-conducting and heat-resisting properties each intermediate those of the tube wall and the distal portion.