Heat exchanger for preheating an oxidizing gas

• US 6,273,180 B1
• Filed: 12/23/1998
• Issued: 08/14/2001
• Est. Priority Date: 12/23/1998
• Status: Expired due to Fees

• Current Assignee: American Air Liquide Incorporated (L'Air Liquide SA), L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Original Assignee: American Air Liquide Incorporated (L'Air Liquide SA), L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Inventors: Tsiava, Remi Pierre, Fossen, Arnaud, Joshi, Mahendra L., Charon, Olivier, Borders, Harley A.
• Primary Examiner(s): Ford, John K.
• Application Number:
  US09/220,559
• Time in Patent Office: 965 Days
• Field of Search: 165/11.1, 165/70, 165/158, 165/159
• US Class Current: 165/11.1
• CPC Class Codes: F28D 7/06 the conduits having a single U-bend F28D7/10 takes precedenceF28D7/0016 and F28D7/0033 take precedence
• CPC Class Codes: F28D 7/1607 with particular pattern of flow of the heat exchange media, e.g. change of flow direction F28D7/1623, F28D7/1638, F28D7/1661, F28D7/1676, F28D7/1692 take precedence
• CPC Class Codes: F28F 13/08 by varying the cross-section of the flow channels
• CPC Class Codes: F28F 2265/16 for preventing leakage
• CPC Class Codes: F28F 2275/20 with threaded elements
• CPC Class Codes: F28F 27/00 Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus control arrangements in general G05
• CPC Class Codes: F28F 9/0219 Arrangements for sealing end plates into casing or header box; Header box sub-elements F28F9/0236 takes precedence
• CPC Class Codes: F28F 9/0229 Double end plates; Single end plates with hollow spaces
• CPC Class Codes: F28F 9/0236 floating elements
• CPC Class Codes: F28F 9/26 Arrangements for connecting different sections of heat-exchange elements, e.g. of radiators connecting different sections in water heaters F24H9/14 , connecting headers with inlet or outlet fittings F28F9/0246

Abstract

A heat exchanger useful for preheating oxidizing gases in a combustion process includes a shell having an inlet and an outlet for the ingress and egress of a first heat exchange fluid, such as a flue gas or preheated air. A first tube manifold couples an inlet end-cap to the first end of the shell. The inlet end-cap has an inlet for receiving a second heat exchange fluid, such as an oxidizing gas. In one embodiment, a second manifold couples an outlet end-cap to the second end of the shell. The second manifold includes an outlet tube therein extending from the second manifold through an outlet opening in the outlet end-cap. A tube bundle is disposed within the shell for transporting the oxidizing gas through the heat exchanger and is coupled to the first and second tube manifolds. The outlet tube collects oxidizing gas flowing through the tube bundle for discharge to a combustion system. The outlet end-cap is pressurized with an inert atmosphere and houses a chemical detector to detect the presence of oxidizing gas within the outlet end-cap.

Claims

1. A heat exchanger for preheating an oxidizing gas comprising:

a shell having an inlet and an outlet for respectively permitting the ingress and the egress of a first heat exchange fluid comprising a gas selected from the group consisting of flue gas and preheated air;

a first chamber having an inlet for receiving a second heat exchange fluid, the second heat exchange fluid comprising an oxidizing gas;

an innertube;

a first manifold configured to transfer the second heat exchange fluid from the first chamber to the inner tube;

a second chamber having an outlet tube extending through an opening therein;

a second manifold configured to transfer the second heat exchange fluid from the inner tube to the outlet tube,

wherein the second chamber contains a gas different from the second heat exchange fluid; and

a chemical detector configured to detect the presence of the oxidizing gas.

2. The heat exchanger of claim 1, wherein the inner tube comprises a multi-pass tube bundle disposed about a longitudinal axis within the shell,

wherein the tube bundle includes a plurality of tubes arranged about the longitudinal axis, each tube characterized by a tube diameter, and

wherein tubes positioned proximal to the longitudinal axis have a larger tube diameter than tubes positioned distal to the longitudinal axis.

3. The heat exchanger of claim 2, wherein the tube bundle includes first, second, and third pass tubes and, wherein first and second pass tubes are positioned distal to the longitudinal axis, and wherein third pass tubes are positioned proximal to the longitudinal axis.

4. The heat exchanger of claim 3, wherein the first manifold comprises:

a first transverse segment adjacent to a second transverse segment, the first transverse segment having a plurality of holes therethrough proximal to the longitudinal axis, and a plurality of passageway therein distal to the longitudinal axis,

wherein the second transverse segment includes a first plurality of holes therethrough for receiving the first pass tubes, a second plurality of holes for receiving the second pass tubes, and a third plurality of holes for receiving the third pass tubes, and

wherein the first transverse segment is aligned with the second transverse segment so as to form a fluid pathway from the first end-cap to the first pass tubes, and to form a reversing fluid pathway from the second pass tubes through the plurality of passageways and into the third pass tubes.

5. The heat exchanger of claim 3, wherein the second manifold comprises:

a first transverse segment adjacent to a second transverse segment, the first transverse segment having a first plurality of holes therethrough for receiving the first pass tubes, a second plurality of holes therethrough for receiving the second pass tubes, and a third plurality of holes therethrough for receiving the third pass tubes; and

the second transverse segment having a plurality of passageways distal to the longitudinal axis and a hole therethrough proximal to the longitudinal axis for receiving the outlet tube,

wherein the first transverse segment is aligned with the second transverse segment so as to form a reversing fluid pathway from the first pass tubes to the second pass tubes and to form a fluid pathway from the third pass tubes to the outlet tube.

6. The heat exchanger of claim 1 further comprising:

a first flange at an inlet end of the inner tube;

first and second gaskets adjacent to either side of the flange; and

a coupling portion of the first manifold having a bore therein for receiving the first flange and the first and second gaskets.

7. The heat exchanger of claim 6, wherein the first gasket resides at a location distal to the first chamber and the second gasket resides at a location proximal to the first chamber, and wherein the first gasket is comprised of alumina-silica ceramic fiber, and the second gasket is comprised of a material selected from the group consisting of a metal fiber and copper.

8. The heat exchanger of claim 6 further comprising:

a second flange at an outlet end of the inner tube;

first and second gaskets adjacent to either side of the second flange; and

a coupling portion of the second manifold having a bore therein for receiving the second flange and the first and second gaskets.

9. The heat exchanger of claim 6, wherein the first gasket resides at a location distal to the second chamber and the second gasket resides at a location proximal to the second chamber, and wherein the first gasket is comprised of alumina-silica ceramic fiber, and the second gasket is comprised of a material selected from the group consisting of a metal fiber and copper.

10. A heat exchanger for preheating an oxidizing gas comprising:

a shell having a first manifold at a first end and a second manifold at a second end, and having an inlet and an outlet for respectively permitting the ingress and egress of a first heat exchange fluid;

at least one tube disposed within the shell for transporting the second heat exchange fluid therethrough and engaging the first manifold and the second manifold at a first side of the first manifold and at a first side of the second manifold;

an inlet chamber adjacent to a second side of the first manifold, the inlet chamber having an opening for receiving a second heat exchange fluid, the second heat exchange fluid comprising an oxidizing gas;

an outlet chamber adjacent to a second side of the second manifold, the outlet chamber having an outlet opening therein;

an outlet tube coupled to the second side of the second manifold passing through the outlet opening in the outlet chamber and configured to receive the second heat exchange fluid,

wherein the outlet chamber contains an inert atmosphere; and

a gas analyzer in communication with the inert atmosphere and configured to detect the oxidizing gas.

11. The heat exchanger of claim 10, wherein the at least one tube comprises a multi-pass tube bundle disposed about a longitudinal axis within the shell,

wherein the tube bundle includes a plurality of tubes arranged about the longitudinal axis, each tube characterized by a tube diameter, and

wherein tubes positioned proximal to the longitudinal axis have a larger tube diameter than tubes positioned distal to the longitudinal axis.

12. The heat exchanger of claim 11, wherein first and second pass tubes are positioned distal to the longitudinal axis, and wherein third pass tubes are positioned proximal to the longitudinal axis.

13. The heat exchanger of claim 11, wherein the gas analyzer comprises an oxygen detector.

14. The heat exchanger of claim 10 further comprising a thermocouple mounted to an instrument port on the outlet chamber and configured to measure the temperature of the outlet tube.

15. The heat exchanger of claim 10, wherein the inert gas is selected from the group consisting of nitrogen, argon, and mixtures thereof.

16. A heat exchanger for preheating an oxidizing gas comprising:

a shell having an inlet and an outlet for permitting the ingress and egress of a gas selected from the group consisting of flue gas and preheated air;

at least one tube longitudinally disposed within the shell and configured to receive an oxidizing gas,

an inlet manifold transversely positioned at an inlet end of the shell and configured to receive a first end portion of the at least one tube;

an outlet manifold transversely positioned at an outlet end of the shell and configured to receive a second end portion of the at least one tube;

an inlet end-cap positioned around the segmented inlet manifold and coupled to the inlet end of the shell; and

an outlet end-cap having an axial opening therein, the end-cap positioned around the segmented outlet manifold and sealed to the outlet end of the shell;

an outlet tube partially inserted into an opening in the segmented outlet manifold and passing through the axial opening of the outlet end-cap,

wherein the outlet tube is in communication with the at least one tube;

an inert atmosphere within the outlet end-cap;

means in communication with the inert atmosphere for detecting the presence of the oxidizing gas within the inert atmosphere; and

means mounted to the outlet end-cap for measuring the temperature of the outlet tube.

17. The heat exchanger of claim 16 further comprising an expansion bellows integral with the shell.

18. The heat exchanger of claim 16, wherein a tube bundle is longitudinally disposed within the shell, and wherein the tube bundle includes a plurality of parallel spaced tubes.

19. The heat exchanger of claim 18, wherein the plurality of parallel-spaced tubes have inner tube walls of iron nickel chromium alloy lined with a ceramic material, and wherein the oxidizing gas comprises oxygen.

20. The heat exchanger of claim 18, wherein the plurality of parallel-spaced tubes comprise first pass tubes, second pass tubes, and third pass tubes, and wherein the first and second pass tubes are alternatingly arranged about a longitudinal axis at a first radial distance, and wherein the third pass tubes are arranged about the longitudinal axis at a second radial distance, and wherein the first radial distance is greater than the second radial distance.

21. The heat exchanger of claim 20, wherein each of the first, second, and third pass tubes are characterized by a diameter, and wherein the diameter of the first pass tubes is less than the diameter of the second pass tubes, and wherein the diameter of the second pass tubes is less than the diameter of the third pass tubes.

22. The heat exchanger of claim 16, wherein the means for measuring the temperature comprises a thermocouple.