High pressure strippers for use in urea plants

1. A shell-and-tube stripper for stripping a urea/carbamate mixture,

the stripper comprising a top end in fluid connection with a bottom end through a plurality of tubes disposed within a shell;

the top end comprising an inlet for a urea/carbamate mixture and an outlet for a gas mixture comprising a stripping gas and one or more stripped compounds;

the bottom end comprising an outlet for a urea/carbamate stream concentrated in urea;

the shell-and-tube stripper further comprising a heating fluid inlet and a heating fluid outlet in fluid connection with a shell-side space disposed between the plurality of tubes and the shell, and a steam belt distributor and an inlet deflector for homogenizing a flow of steam near the heating fluid inlet;

the shell-and-tube stripper having a longitudinal direction and lateral cross sections, the longitudinal direction being parallel to the tubes and the lateral cross sections being perpendicular to the longitudinal direction;

wherein a plurality of baffles are arranged in the shell-side space, the baffles defining a multi-pass crossflow in the shell-side space, wherein the baffles are parallel with the lateral cross sections within a margin of error of less than 1°; and

wherein the stripper further comprises a plurality of deflectors positioned in a flow path, wherein the deflectors are at oblique or right angles with respect to the baffles.

2. The shell-and-tube stripper according to claim 1 , wherein at least 80% of the deflectors are associated with a baffle of the plurality of baffles.

3. The shell-and-tube stripper according to claim 2 , wherein the deflectors which are associated with a baffle of the plurality of baffles are physically attached to the baffle they are associated with.

4. The shell-and-tube stripper according to claim 1 , wherein the stripper comprises more than 3000 tubes.

5. The shell-and-tube stripper according to claim 1 , wherein the deflectors are at an angle between 10.0° and 90.0° with the baffles; and/or

wherein the deflectors describe an arc between 10.0° and 80.0° along a cross section through the shell-and-tube stripper which is parallel to the longitudinal direction and/or wherein the deflectors describe an arc between 10.0° and 80.0° along a lateral cross section through the shell-and-tube stripper.

6. The shell-and-tube stripper according to claim 5 , wherein the angle which the deflectors are at with the baffles is between 45.0° and 90.0°.

7. The shell-and-tube stripper according to claim 1 , wherein the deflectors are arched.

8. The shell-and-tube stripper according to claim 1 , wherein the deflectors and/or the baffles are perforated.

9. The shell-and-tube stripper according to claim 8 , wherein the perforations are circular.

10. The shell-and-tube stripper according to claim 1 , wherein the baffles are single segmental baffles, each single segmental baffle being shaped as a circular segment having a chord, wherein the single segmental baffles are perpendicular to the longitudinal direction within a margin of error of less than 1.0%, wherein the single segmental baffles are consecutively positioned along the longitudinal direction of the shell-and-tube stripper, wherein an orientation of the single segmental baffles varies along the longitudinal direction of the shell-and-tube stripper, and wherein deflectors are positioned between consecutive single segmental baffles.

11. The shell-and-tube stripper according to claim 1 , wherein the baffles are disk-and-doughnut baffles comprising disk baffles and doughnut baffles, each disk baffle being shaped as a disk, and each doughnut baffle being shaped as a ring comprising a hole, a diameter of the disk baffles being equal to or bigger than the diameter of the hole in the doughnut baffles within a margin of error of less than 10.0%, the disk baffles and the doughnut baffles being positioned perpendicular to the longitudinal direction within a margin of error of less than 1.0%, the disk baffles and the doughnut baffles being consecutively and alternatingly positioned along the longitudinal direction of the shell-and-tube stripper, wherein the deflectors are positioned between adjacent disk baffles and doughnut baffles.

12. The shell-and-tube stripper according to claim 1 , wherein the baffles are double segmental baffles comprising outer baffles and inner baffles, each outer baffle being shaped as a circular segment having a chord, two outer baffles being arranged on opposing sides of a lateral cross section through the shell-and-tube stripper, the inner baffles being shaped as a mirror symmetrical area between the two outer baffles, two outer baffles and an inner baffle being positioned perpendicular to the longitudinal direction within a margin of error of less than 1.0%, wherein two outer baffles and an inner baffle are alternatingly positioned along the longitudinal direction of the shell-and-tube stripper, and wherein the deflectors are positioned between adjacent inner baffles and outer baffles.

13. The shell-and-tube stripper according to claim 1 , wherein a second heating fluid inlet is in fluid connection with the shell-side space and is installed between the aforementioned heating fluid inlet and the heating fluid outlet.

14. The shell-and-tube stripper according to claim 1 , wherein at least 90% of the deflectors are each associated with a baffle of the plurality of baffles.

15. The shell-and-tube stripper according to claim 1 , wherein the stripper comprises more than 7000 tubes.

16. The shell-and-tube stripper according to claim 1 , wherein the stripper comprises 3000 to 7000 tubes.

17. The shell-and-tube stripper according to claim 1 , wherein the stripper comprises 5000 to 10000 tubes.

18. A system for production of urea comprising:

a carbamate condenser;

a urea reactor; and

a shell-and-tube stripper for stripping a urea/carbamate mixture, the stripper comprising a top end in fluid connection with a bottom end through a plurality of tubes disposed within a shell; the tope end comprising an inlet for a urea/carbamate mixture and an outlet for a gas mixture comprising a stripping gas and one or more stripped compounds; the bottom end comprising an outlet for a urea/carbamate stream concentrated in urea; the shell-and-tube stripper further comprising a heating fluid inlet and a heating fluid outlet in fluid connection with a shell-side space disposed between the plurality of tubes and the shell, and a steam belt inlet; the shell-and-tube stripper having a longitudinal direction and lateral cross sections, the longitudinal direction being parallel to the tube and the lateral cross sections being perpendicular to the longitudinal direction; wherein a plurality of baffles are arranged in the shell-side space, the baffles defining a multi-pass crossflow in the shell-side space, wherein the baffles are parallel with the lateral cross sections within a margin of error of less than 1°; and wherein the stripper further comprises a plurality of deflectors positioned in a flow path, wherein the deflectors are at oblique or right angles with respect to the baffles.

19. A method for stripping a urea/carbamate mixture, the method comprising steps of:

providing a shell-and-tube stripper for stripping a urea/carbamate mixture, the stripper comprising a top end in fluid connection with a bottom end through a plurality of tubes disposed within a shell; the top end comprising an inlet for a urea/carbamate mixture and an outlet for a gas mixture comprising a stripping gas and one or more stripped compounds; the bottom end comprising an outlet for a urea/carbamate stream concentrated in urea; the shell-and-tube stripper further comprising a heating fluid inlet and a heating fluid outlet in fluid connection with a shell-side space disposed between the plurality of tube and the shell, and a steam belt distributor and an inlet deflector for homogenizing a flow of steam near the healing fluid inlet; the shell-and-tube stripper having a longitudinal direction and lateral cross sections, the longitudinal direction being parallel to the tubes and the lateral cross sections being perpendicular to the longitudinal direction; wherein a plurality of baffles are arranged in the shell-side space, the baffles defining a multi-pass crossflow in the shell-side space, wherein the baffles are parallel with the lateral cross sections within a margin of error of less than 1°; and wherein the stripper further comprises a plurality of deflectors positioned in a flow path, wherein the deflectors are at oblique or right angles with respect to the baffles;

providing the urea/carbamate mixture to the inlet for the urea/carbamate mixture;

providing a heating fluid to the shell-side space by means of the heating fluid inlet;

contacting the urea/carbamate mixture and the stripping gas in a tube-side space disposed within the tubes, and heating the urea/carbamate mixture by means of the heating fluid, thereby obtaining a urea/carbamate stream concentrated in urea;

extracting the urea/carbamate stream concentrated in urea at the outlet for the urea/carbamate stream concentrated in urea;

extracting a gas mixture comprising one or more stripped compounds at the outlet for the gas mixture, the one or more stripped compounds comprising NH 3 , CO 2 , and water; and

extracting the heating fluid at the heating fluid outlet.