Air cooled condenser and related methods
A vertical bundle air-cooled heat exchanger, a finned tube assembly for an air cooled condenser and method for forming the same, and a system for removing thermal energy generated by radioactive materials. In one aspect, an air cooled condenser sized for industrial and commercial application includes an inlet steam distribution header for conveying steam, a condensate outlet header for conveying condensate, an array of tube bundles each having a plurality of finned tube assemblies having a bare steel tube with an exposed outer surface and a set of aluminum fins brazed directly onto the tube by a brazing filler metal. The steel tubes may be spaced apart by the aluminum fins and have an inlet end fluidly coupled to the inlet steam distribution header and an outlet end fluidly coupled to the outlet header. A forced draft fan may be arranged to blow air through the tube bundles.
1. A system for removing thermal energy generated by radioactive materials comprising:
an air-cooled heat exchanger comprising a vertically-elongated cylindrical shell defining a longitudinal axis;
a heat rejection closed-loop fluid circuit comprising a tube-side fluid path of the air-cooled heat exchanger, a coolant fluid flowing through the heat rejection closed-loop fluid circuit, the heat rejection closed-loop fluid circuit thermally coupled to the radioactive materials so that thermal energy generated by the radioactive materials is transferred to the coolant fluid; and
the air-cooled heat exchanger comprising a shell-side fluid path having a first air inlet, a second air inlet and an air outlet, the first air inlet located at a first elevation, the second air inlet located at a second elevation, and the air outlet located at a third elevation, the second elevation greater than the first elevation and the third elevation greater than the second elevation, the air-cooled heat exchanger transferring thermal energy from the coolant fluid flowing through the tube-side fluid path to air flowing through the shell-side fluid path;
wherein the tube-side fluid path comprises internal cavities of a plurality of heat exchange tubes defining a tube bundle located within the shell-side fluid path.
2. The system of claim 1 , wherein the shell-side fluid path comprises a venturi located at an elevation between the second air inlet and the air outlet.
3. The system of claim 2 , wherein the venturi is created by fins of the plurality of heat exchange tubes.
4. The system of claim 1 , wherein each of the fins of the plurality of heat exchange tubes comprise opposing surfaces that extend substantially parallel to the longitudinal axis.
5. The system of claim 4 , wherein the shell-side fluid path comprises a first free transverse cross-sectional area devoid of fins at the second elevation and a second free transverse cross-sectional area devoid of fins at an elevation between the second air inlet and the air outlet, the second free transverse cross-sectional area being less than the first free transverse cross-sectional area.
6. The system of claim 5 , wherein the shell-side fluid path comprises a third free transverse cross-sectional area devoid of fins at the third elevation, the third free transverse cross-sectional area being greater than the second free transverse cross-sectional area.
7. The system of claim 1 , further comprising:
an intermediate heat exchanger;
an intermediate closed-loop fluid circuit comprising, in operable fluid coupling, a pool of a liquid and a first fluid path of the intermediate heat exchanger, the radioactive materials immersed in the pool of the liquid, the liquid flowing through the intermediate closed-loop fluid circuit; and
the heat rejection closed-loop fluid circuit further comprising a second fluid path of the intermediate heat exchanger, the intermediate heat exchanger transferring thermal energy from the liquid flowing through the first fluid path to the coolant fluid flowing through the second fluid path.
8. The system of claim 7 , wherein the pool of the liquid and the intermediate heat exchanger are contained within a containment structure and the air-cooled heat exchanger is located outside the containment structure.
9. The system of claim 1 , wherein the plurality of heat exchange tubes are vertically oriented and linearly straight extending parallel to the vertical longitudinal axis.
10. The system of claim 9 , wherein the tube bundle comprises finned tube sections and a non-finned tube section arranged in axial alignment, the second air inlet transversely aligned with the non-finned tube section.
11. System of claim 10 , wherein the finned tube sections and the non-finned tube section alternate along the longitudinal axis.
12. The system of claim 11 , wherein each of the first air inlet, the second air inlet, and the air outlet are transversely aligned with one of the non-finned tube sections.
13. The system of claim 9 , further comprising:
the air-cooled heat exchanger comprising a top tube sheet and a bottom tube sheet, the plurality of heat exchange tubes extending vertically from the top tube sheet to the bottom tube sheet, the first air inlet located adjacent the bottom tube sheet and the air outlet located adjacent the top tube sheet; and
the tube-side fluid path of the air-cooled heat exchanger comprising a coolant fluid inlet header and a coolant fluid outlet header, the internal cavities of the plurality of heat exchange tubes forming passageway between the coolant fluid inlet header and the coolant fluid outlet header.
14. The system of claim 1 , wherein each of the first air inlet, the second air inlet, and the air outlet are formed through the shell and place ambient air in fluid communication with the shell-side fluid path.
15. The system of claim 14 , further comprising:
a vertically-elongated shroud forming a shroud cavity at an upper portion of the shell, a majority of the air-cooled heat exchanger located within the shroud cavity;
the shroud cavity comprising a shroud outlet plenum at top circumferentially surrounding and enclosing a top of air-cooled heat exchanger;
the air outlet of the shell located within the shroud outlet plenum and configured to discharge air exiting the air-cooled heat exchanger laterally into the shroud outlet plenum in a direction transverse to the longitudinal axis.
16. The system of claim 15 , wherein the shroud comprises a lower portion adjacent the first air inlet, a diametrically enlarged bulbous upper portion which defines the shroud outlet plenum, and a cylindrical intermediate portion extending between the lower and upper portions.
17. The system of claim 16 , wherein the lower portion is diametrically enlarged and outwardly flared in configuration.
18. The system of claim 15 , wherein a top portion of the shroud defines a chimney forming a vertical passageway from the shroud outlet plenum to an ambient environment.
19. The system of claim 18 , further comprising a blower disposed in chimney and operable to induce air flow through the shell-side fluid path by drawing air into the air-cooled heat exchanger through the first air inlet and the second air inlet.
20. The system of claim 13 , further comprising a transversely oriented top end closure enclosing a top of the shell, and a transversely oriented bottom end closure enclosing a bottom of the shell.