Cooling tower with indirect heat exchanger

1. A method of exchanging heat comprising the steps of:

providing a direct evaporative heat exchange section and an indirect heat exchange section,

the indirect heat exchange section conducting a fluid stream within a plurality of pathways,

the direct heat exchange section comprising a top and a bottom,

the indirect heat exchange section comprising a top and a bottom,

the indirect heat exchange section being placed generally above the direct heat exchange section,

distributing an evaporative liquid generally downward onto and through the indirect heat exchange section such that indirect heat exchange occurs between the fluid stream within the plurality of pathways and the evaporative liquid, and hence indirectly exchanging heat with the fluid stream within the plurality of pathways in the indirect section,

distributing substantially all of the evaporative liquid leaving the indirect heat exchange section generally downward onto the direct heat exchange section,

wherein the indirect heat exchange section is comprised of a plate type heat exchanger,

the plate type heat exchanger comprised of a series of adjacent plate cassettes forming an alternating arrangement of first series of flow passages and a second series of flow passages,

an inlet header and an outlet header operatively connected to the first series of flow passages such that the fluid stream can pass into the first series of flow passages and out from the first series of flow passages,

the second series of flow passages arranged such that the evaporative liquid can pass through the second series of flow passages.

2. The method of exchanging heat of claim 1 , further comprising:

collecting substantially all of the evaporative liquid that exits the direct heat exchange section, and

pumping the collected evaporative liquid upwardly such that it can be distributed generally downward onto and through the indirect heat exchange section.

3. The method of exchanging heat of claim 1 wherein in the plate type heat exchanger comprised of a series of adjacent plate cassettes

forming an alternating arrangement of a first series of closed loop flow passages and

a second series of open loop flow passages,

each plate cassette in the series of adjacent plate cassettes includes an enhanced surface pattern

to increase plate surface area, to increase the sensible heat transfer from the fluid stream within the closed loop first series of flow passages to the evaporative liquid.

4. The method of exchanging heat of claim 1 wherein in the plate type heat exchange comprised of a series of adjacent plate cassettes

forming an alternating arrangement of a first series of closed loop flow passages and

a second series of open loop flow passages,

a second inlet header and a second outlet header are operatively connected to a third series of closed loop flow passages in the plate heat exchanger

such that a second fluid stream can pass into the third series of flow passages and

out from the third series of flow passages.

5. The method of exchanging heat of claim 1

wherein two direct heat exchange sections and two indirect heat exchange sections are provided, with one indirect heat exchange section located generally above one direct heat exchange section, with the second indirect heat exchange section located generally above the second direct heat exchange section.

6. The method of exchanging heat of claim 1

wherein two direct heat exchange sections are provided,

with the indirect heat exchange section located generally above both direct heat exchange sections.

7. The method of exchanging heat of claim 1

further comprising moving air through the indirect section and through the direct section,

the air moving through the indirect heat exchange section exchanging both heat and mass with the evaporative liquid moving through the indirect heat exchange section and hence indirectly exchanging heat with the fluid stream within the plurality of pathways in the indirect section the air moving through the direct heat exchange section exchanging heat and mass with the evaporative liquid moving through the direct heat exchange section.

8. A method of exchanging heat comprising the steps of:

providing an indirect heat exchange section,

the indirect heat exchange section conducting a fluid stream within a plurality of pathways,

the indirect heat exchange section comprising a top and a bottom,

distributing an evaporative liquid generally downward onto and through the indirect heat exchange section such that indirect heat exchange occurs between the fluid stream within the plurality of pathways and the evaporative liquid, and

within the plurality of pathways in the indirect section,

wherein the indirect heat exchange section is comprised of a plate heat exchanger,

the plate heat exchanger comprised of a series of adjacent plate cassettes forming an alternating arrangement of a first series of flow passages and

a second series of flow passages,

an inlet header and

an outlet header operatively connected to the first series of flow passages such that the fluid stream can pass into the first series of flow passages and out from the first series of flow passages,

the second series of flow passages arranged such that the evaporative liquid can pass through the second series of flow passages, and wherein in the plate heat exchanger comprised of a series of adjacent plate cassettes forming an alternating arrangement of a first series of closed loop flow passages and

a second series of open loop flow passages,

a second inlet header and a second outlet header are operatively connected to a third series of closed loop flow passages in the plate heat exchanger

such that a second fluid stream can pass into the third series of closed loop flow passages and

out from the third series of flow passages.

9. The method of exchanging heat of claim 8 , further comprising:

collecting substantially all of the evaporative liquid that exits the indirect heat exchange section, and

pumping the collected evaporative liquid upwardly such that it can be distributed generally downwardly onto and through the indirect heat exchange section.

10. The method of exchanging heat of claim 8 wherein

each plate cassette in the series of adjacent plate cassettes includes an enhanced surface pattern

to increase plate surface area and to increase the sensible heat transfer from the fluid stream within the closed loop first series of flow passages to the evaporative liquid moving

through the second series of flow passages in the plate heat exchanger.

11. A method of exchanging heat comprising the steps of:

providing a direct evaporative heat exchange section and an indirect heat exchange section, the indirect heat exchange section conducting a fluid stream within a plurality of pathways,

the direct heat exchange section comprising a top and a bottom,

the indirect heat exchange section comprising a top and a bottom,

the direct heat exchange section being placed generally above the indirect heat exchange section,

distributing an evaporative liquid generally downward onto and through the direct heat exchange section such that direct heat exchange occurs,

distributing substantially all of the evaporative liquid leaving the direct heat exchange section generally downward onto the indirect heat exchange section,

wherein the indirect heat exchange section is comprised of a plate type heat exchanger,

the plate type heat exchanger comprised of a series of adjacent plate cassettes forming an alternating arrangement of first series of flow passages and a second series of flow passages,

an inlet header and an outlet header operatively connected to the first series of flow passages such that the fluid stream can pass into the first series of flow passages and out from the first series of flow passages,

the second series of flow passages arranged such that the evaporative liquid can pass through the second series of flow passages, and wherein in the plate type heat exchange comprised of a series of adjacent plate cassettes

forming an alternating arrangement of a first series of closed loop flow passages and

a second series of open loop flow passages,

a second inlet header and a second outlet header are operatively connected to a third series of closed loop flow passages in the plate heat exchanger

such that a second fluid stream can pass into the third series of flow passages and

out from the third series of flow passages.

12. The method of exchanging heat of claim 11 , further comprising:

collecting substantially all of the evaporative liquid that exits the indirect heat exchange section, and

pumping the collected evaporative liquid upwardly such that it can be distributed generally downward onto and through the direct heat exchange section.

13. The method of exchanging heat of claim 11 wherein

each plate cassette in the series of adjacent plate cassettes includes an enhanced surface pattern

to increase plate surface area, to increase the sensible heat transfer from the fluid stream within the closed loop first series of flow passages to the evaporative liquid.

14. The method of exchanging heat of claim 11

wherein two direct heat exchange sections and

two indirect heat exchange sections are provided, with one direct heat exchange section located generally above one indirect heat exchange section, with the second direct heat exchange section located generally above the second indirect heat exchange section.

15. The method of exchanging heat of claim 11

wherein two indirect heat exchange sections are provided,

with the direct heat exchange section located generally above both indirect heat exchange sections.

16. The method of exchanging heat of claim 11 further comprising moving air through the indirect section and through the direct section,

the air moving through the indirect heat exchange section exchanging both heat and mass with the evaporative liquid moving through the indirect heat exchange section and hence indirectly exchanging heat with the fluid stream within the plurality of pathways in the indirect section the air moving through the direct heat exchange section exchanging heat and mass with the evaporative liquid moving through the direct heat exchange section.

17. A method of exchanging heat comprising the steps of:

providing a direct evaporative heat exchange section and an indirect heat exchange section, the indirect heat exchange section conducting a fluid stream within a plurality of pathways,

the direct heat exchange section comprising a top and a bottom,

the indirect heat exchange section comprising a top and a bottom,

the direct heat exchange section being placed generally above the indirect heat exchange section,

distributing an evaporative liquid generally downward onto and through the direct heat exchange section such that direct heat exchange occurs,

distributing substantially all of the evaporative liquid leaving the direct heat exchange section generally downward onto the indirect heat exchange section,

wherein the indirect heat exchange section is comprised of a plate type heat exchanger,

the plate type heat exchanger comprised of a series of adjacent plate cassettes forming an alternating arrangement of first series of flow passages and a second series of flow passages,

an inlet header and an outlet header operatively connected to the first series of flow passages such that the fluid stream can pass into the first series of flow passages and out from the first series of flow passages,

the second series of flow passages arranged such that the evaporative liquid can pass through the second series of flow passages, wherein two direct heat exchange sections and

two indirect heat exchange sections are provided, with one direct heat exchange section located generally above one indirect heat exchange section, with the second direct heat exchange section located generally above the second indirect heat exchange section.

18. The method of exchanging heat of claim 17 , further comprising:

collecting substantially all of the evaporative liquid that exits the indirect heat exchange section, and

pumping the collected evaporative liquid upwardly such that it can be distributed generally downward onto and through the direct heat exchange section.

19. The method of exchanging heat of claim 17 wherein

in the plate type heat exchanger comprised of a series of adjacent plate cassettes

forming an alternating arrangement of a first series of closed loop flow passages and

a second series of open loop flow passages,

each plate cassette in the series of adjacent plate cassettes includes an enhanced surface pattern

to increase plate surface area, to increase the sensible heat transfer from the fluid stream within the closed loop first series of flow passages to the evaporative liquid.

20. The method of exchanging heat of claim 17 wherein

in the plate type heat exchanger comprised of a series of adjacent plate cassettes

forming an alternating arrangement of a first series of closed loop flow passages and

a second series of open loop flow passages,

a second inlet header and a second outlet header are operatively connected to a third series of closed loop flow passages in the plate heat exchanger

such that a second fluid stream can pass into the third series of flow passages and

out from the third series of flow passages.

21. The method of exchanging heat of claim 17

wherein two indirect heat exchange sections are provided,

with the direct heat exchange section located generally above both indirect heat exchange sections.

22. The method of exchanging heat of claim 17 further comprising

moving air through the indirect section and through the direct section,

the air moving through the indirect heat exchange section exchanging both heat and mass with the evaporative liquid moving through the indirect heat exchange section and hence indirectly exchanging heat with the fluid stream within the plurality of pathways in the indirect section the air moving through the direct heat exchange section exchanging heat and mass with the evaporative liquid moving through the direct heat exchange section.

23. A method of exchanging heat comprising the steps of:

providing a direct evaporative heat exchange section and an indirect heat exchange section, the indirect heat exchange section conducting a fluid stream within a plurality of pathways,

the direct heat exchange section comprising a top and a bottom,

the indirect heat exchange section comprising a top and a bottom,

the direct heat exchange section being placed generally above the indirect heat exchange section,

distributing an evaporative liquid generally downward onto and through the direct heat exchange section such that direct heat exchange occurs,

distributing substantially all of the evaporative liquid leaving the direct heat exchange section generally downward onto the indirect heat exchange section,

wherein the indirect heat exchange section is comprised of a plate type heat exchanger,

the plate type heat exchanger comprised of a series of adjacent plate cassettes forming an alternating arrangement of first series of flow passages and a second series of flow passages,

an inlet header and an outlet header operatively connected to the first series of flow passages such that the fluid stream can pass into the first series of flow passages and out from the first series of flow passages,

the second series of flow passages arranged such that the evaporative liquid can pass through the second series of flow passages, wherein two indirect heat exchange sections are provided,

with the direct heat exchange section located generally above both indirect heat exchange sections.

24. The method of exchanging heat of claim 23 , further comprising:

collecting substantially all of the evaporative liquid that exits the indirect heat exchange section, and

pumping the collected evaporative liquid upwardly such that it can be distributed generally downward onto and through the direct heat exchange section.

25. The method of exchanging heat of claim 23 wherein

in the plate type heat exchanger comprised of a series of adjacent plate cassettes

forming an alternating arrangement of a first series of closed loop flow passages and

a second series of open loop flow passages,

each plate cassette in the series of adjacent plate cassettes includes an enhanced surface pattern

to increase plate surface area, to increase the sensible heat transfer from the fluid stream within the closed loop first series of flow passages to the evaporative liquid.

26. The method of exchanging heat of claim 23 wherein

in the plate type heat exchanger comprised of a series of adjacent plate cassettes

forming an alternating arrangement of a first series of closed loop flow passages and

a second series of open loop flow passages,

a second inlet header and a second outlet header are operatively connected to a third series of closed loop flow passages in the plate heat exchanger

such that a second fluid stream can pass into the third series of flow passages and

out from the third series of flow passages.

27. The method of exchanging heat of claim 23

wherein two direct heat exchange sections and two indirect heat exchange sections are provided, with one direct heat exchange section located generally above one indirect heat exchange section, with the second direct heat exchange section located generally above the second indirect heat exchange section.

28. The method of exchanging heat of claim 23 further comprising

moving air through the indirect section and through the direct section,

the air moving through the indirect heat exchange section exchanging both heat and mass with the evaporative liquid moving through the indirect heat exchange section and hence indirectly exchanging heat with the fluid stream within the plurality of pathways in the indirect section the air moving through the direct heat exchange section exchanging heat and mass with the evaporative liquid moving through the direct heat exchange section.