Method and apparatus for reverse circulating nuclear steam generator secondary fluid

• US 3,900,010 A
• Filed: 04/19/1974
• Issued: 08/19/1975
• Est. Priority Date: 04/19/1974
• Status: Expired due to Term

• Current Assignee: Fred Zwald Stiteler, Ronald Louis Honigmann
• Original Assignee: Fred Zwald Stiteler, Ronald Louis Honigmann
• Inventors: Stiteler, Fred Zwald, Honigmann, Ronald Louis
• Primary Examiner(s): Sprague, Kenneth W.
• Application Number:
  US05/462,270
• Time in Patent Office: 487 Days
• Field of Search: 122/32,33,34,378,382,397,396,401,46R
• US Class Current: 122/32
• CPC Class Codes: F22B 1/025 with vertical U shaped tubes carried on a horizontal tube sheet
• CPC Class Codes: F22B 37/483 specially adapted for nuclear steam generators

Abstract

A method and apparatus is disclosed for inducing reverse circulation of the fluid on the secondary side of a steam generator of the type including an outer vessel and a vapor generation chamber having an annular baffle means dividing the chamber into an outer annular downcomer passage and an inner riser section. A quantity of gas is introduced into the lower end of the annular downcomer passage and allowed to bubble up the downcomer passage, thus creating a region of fluid density in the downcomer less than the fluid density in the inner riser section. The density differential therebetween induces a natural circulation of the fluid down the riser section and up through the downcomer passage.

Claims

1. A method of inducing fluid circulation on the secondary side of a steam generator of the tupe including an outer vessel and a vapor generation chamber having an annular baffle means dividing the chamber into an outer annular downcomer passage and an inner riser section, wherein the fluid level is said steam generator is above said annular baffle means, comprising the step of:

introducing gas into the lower end of the annular downcomer passage, whereby said gas bubbles up the downcomer passage creating a region of fluid density in the downcomer passage less than the fluid density in the inner riser section, the density differential therebetween inducing a natural circulation of the fluid down the inner riser section and into and up through the downcomer passage.

2. A method according to claim 1 including venting out of the outer vessel gas which has risen through the annular downcomer and passed from the fluid into the region above the fluid level.

3. A method according to claim 2 including collecting the gas which is vented from the outer vessel and re-introducing said gas into said annular downcomer passage in said introducing step.

4. A method according to claim 1 wherein said gas introduced into the lower end of the annular downcomer passage is nitrogen gas.

5. A method of cleaning the secondary side of a steam generator of the type including an outer vessel and a vapor generation chamber having a annular gaffle means dividing the chamber into an outer annular downcomer passage and an inner riser section comprising the steps of:

removing the normal secondary fluid from the secondary side;

introducing sufficient fluid cleaning agent into the secondary side to bring the level of same to a level at least above said annular baffle plate; and

introducing gas into the lower end of the annular downcomer passage, whereby said gas bubbles up the downcommer passage creating a region of cleaning fluid density in the downcomer passage less than the cleaning fluid density in the inner riser section, the density differential therebetween inducing a natural circulation of cleaning fluid down the inner riser section and into and up through the downcomer passage.

6. Apparatus for inducing fluid circulation on the secondary side of a steam generator of the type including an outer vessel and a vapor generation chamber having an annular baffle means dividing the chamber into an outer annular downcomer passage and an inner riser section, wherein the fluid level is above said annular baffle means, comprising:

means for introducing gas into the lower end of the annular downcomer passage, whereby said gas bubbles up the downcomer passage creating a Region of fluid density in the annular downcomer passage less than the fluid density in the inner riser section, the density differential therebetween inducing a natural circulation of the fluid down the inner riser section and into and up through the downcomer passage.

7. Apparatus according to claim 6 wherein said means for introducing gas comprises and annular gas distribution pipe disposed within and at the lower end of said annular downcomer passage, said annular gas distribution pipe including a plurality of gas discharge openings on the upper side thereof;

and gas supply means in flow communication with said annular gas distribution pipe.

8. Apparatus according to claim 6 including means for venting out of the outer vessel, gas which has risen through the annular downcomer and passed into the region above the fluid level.

9. Apparatus according to claim 8 including means for collecting the gas vented from the outer vessel by said venting means;

and means for re-introducing said collected gas into said annular downcomer passage through said means for introducing gas.

10. Apparatus according to claim 6 wherein said annular downcomer passage has a region of larger cross sectional flow area adjacent the upper end thereof and wherein said means for introducing gas comprises:

an annular gas distribution within said region of larger cross sectional flow area; and

a plurality of gas distribution pipes extending vertically downward through said annular downcomer passage to a position adjacent the lower end thereof, each of said vertically extending gas discharge pipes including a gas discharge fitting at the lower end thereof, each of said fittings containing a plurality of gas discharge openings on the upper side thereof.