Vertical vapor generator
OwnerGiovanni Manentiinventor
Life of this patent
Estimating the term…
Abstract
Vertical vapor generator of shell-and-tube type, for an indirect heat exchange between a tube-side fluid to be cooled and a boiling shell-side fluid, and operating method thereof. The vertical vapor generator includes shell-side baffles having a slope to promote the upward outflow of vapor from the lower surface of the baffles and the downward outflow of gravity deposits from the upper surface of the baffles. In embodiments, the vertical vapor generator mitigates or eliminates overheating and corrosion phenomena near the baffles and provides increased reliability and operating life. Operating methods are also disclosed.
Claims15
Vertical shell-and-tube vapor generator (G1,G2,G3,G4), with substantially cylindrical geometry and longitudinal axis (1) orthogonal to a horizontal ground (30), for indirect heat exchange between a tube-side fluid (F2) to be cooled and a shell-side fluid (F1) to be vaporized, the generator configured for the shell-side fluid having ascending flow, comprising:
- at least one tube-sheet (3,4) parallel to the ground (30) and provided with a plurality of bores,
- a plurality of exchanging tubes (2) connected to said bores and forming a tube-bundle,
- a shell (5) enveloping said tube-bundle,
- a tube-side distributor (6,7) connected to said tube-sheet (3,4) on a side of said tube-sheet opposite said tube-bundle and in fluid communication with said exchanging tubes (2),
- inlet and outlet shell-side connections (10,11) on said shell (5) for introducing and extracting said shell-side fluid (F1) respectively at a bottom and from a top of the tube-bundle,
- inlet and outlet tube-side connections (10,11) on said tube-side distributor (6,7) for introducing and extracting said tube-side fluid (F2) respectively,
- a set of shell-side baffles intersecting at least portions of said exchanging tubes (2) to support said exchanging tubes (3) and to deviate said ascending flow,
- wherein each baffle presents at least a symmetry plane containing said longitudinal axis (1) so to develop on shell-side a substantially two-dimensional flow, wherein said baffles are staggered and/or alternate along said longitudinal axis (1), wherein said baffles have a lower and an upper surface (15,16) and have either only a first portion of perimeter or a first and a second portion of perimeter, wherein said first portion of perimeter crosses the tube-bundle and said second portion of perimeter at least partially circumscribes the tube-bundle, wherein said first portion of perimeter forms a cut corresponding to an opening for the passage of said shell-side fluid (F1), wherein one or more baffles (12,17,18,20,21) of said set form an angle (α) relative to the ground (30) so to be sloped and have said first portion of perimeter (14,31,33) that lays on a plane orthogonal to the longitudinal axis (1) and that is upwardly facing so to correspond to the top of said sloped baffles (12,17,18,20,21), wherein said sloped baffles (12,17,18,20,21) develop on the lower surface (15) a vertical and upward component of the shell-side flow to promote a detachment and upward outflow of vapor pockets and bubbles and to promote on the upper surface (16) a detachment and downward outflow of deposits accumulated by gravity.
Operating method for a shell and tube vertical vapor generator (G1,G2,G3,G4), the generator having substantially cylindrical geometry and longitudinal axis (1) orthogonal to the ground (30), for indirect heat exchange between a tube-side fluid (F2) to be cooled and a boiling shell-side fluid (F1) having ascending flow, wherein said vertical vapor generator (G1,G2,G3,G4) comprises:
- at least one tube-sheet (3,4) parallel to the ground (30) and provided with a plurality of bores,
- a plurality of exchanging tubes (2) connected to said bores and forming a tube-bundle,
- a shell (5) enveloping said tube-bundle,
- a tube-side distributor (6,7) connected to said tube-sheet (3,4) on a side opposite said tube-bundle and in fluid communication with said exchanging tubes (2),
- inlet and outlet shell-side connections (10,11) on said shell (5) for introducing and extracting said shell-side fluid (F1) respectively at a bottom and from a top of the tube-bundle,
- inlet and outlet tube-side connections (10,11) on said tube-side distributor (6,7) for introducing and extracting said tube-side fluid (F2) respectively,
- a set of shell-side baffles crossed by portions of said exchanging tubes (2) and to support said exchanging tubes (3) and to deviate said ascending flow,
- wherein each baffle presents at least a symmetry plane containing said longitudinal axis (1), wherein said baffles are staggered and/or alternate along said longitudinal axis (1), wherein said baffles have a lower and an upper surface (15,16) and have either only a first portion of perimeter or a first and a second portion of perimeter, wherein said first portion of perimeter crosses the tube-bundle and said second portion of perimeter at least partially circumscribes the tube-bundle, wherein said first portion of perimeter forms a cut corresponding to an opening for the passage of said shell-side fluid (F1) and wherein one or more baffles (12,17,18,20,21) of said set form an angle (α) relative to the ground (30) so to be sloped and have said first portion of perimeter (14,31,33) that lays on a plane orthogonal to the longitudinal axis (1) and that is upwardly facing so to correspond to the top of said sloped baffles (12,17,18,20,21),
- the method comprising the following steps:
- introducing said shell-side fluid (F1) at the bottom of the tube-bundle;
- developing an ascending substantially two-dimensional shell-side flow across the tube-bundle;
- introducing said tube-side fluid (F2) into the tube-side distributor, and carrying out indirect heat transfer from said tube-side fluid (F2) to said shell-side fluid (F1) to heat and optionally boil said shell-side fluid (F1);
- developing on the lower surface (15) of said sloped baffles (12,17,18,20,21) a vertical and upward component of the shell-side flow for promoting the detachment and upward outflow of steam pockets and bubbles from said lower surface (15);
- extracting said shell-side fluid (F1) from the top of the tube-bundle to form an extracted shell-side fluid with a higher vapor fraction relative to inlet.
Dependencies are inferred from the claim text.