CN-122029397-A - Shell-and-tube heat exchanger

Abstract

The present disclosure provides a vertical top-down shell-and-tube heat exchanger and a method for condensing a gas stream comprising water, ammonia, and carbon dioxide.

Inventors

• Lino Giovanni polo
• Tan Chaocheng

Assignees

• 雅苒国际有限公司

Dates

Publication Date

20260512

Application Date

20241220

Priority Date

20231220

Claims (13)

1. 1. A vertical top down shell and tube heat exchanger for condensing a gas stream, the heat exchanger comprising a main body, a distribution section, a heat exchange section comprising a set of vertical tubes, a cooling medium inlet, a cooling medium outlet and a collection section comprising a cooling fluid outlet, wherein: -the distribution section and the heat exchange section are separated by a top tube sheet comprising a plurality of openings configured to receive the vertical tubes; -the distribution section comprises a gas inlet for a gas stream to be condensed, a liquid inlet for a liquid comprising a passivating agent and a distribution tray located below the liquid inlet, wherein the distribution tray is adapted to distribute both the gas stream and the liquid comprising a passivating agent, the distribution tray comprises two sets of through holes perforated to the distribution tray, a first set of through holes being configured to distribute the liquid comprising a passivating agent across the top of the top tube sheet, and a second set of through holes being configured to allow the gas stream to reach the vertical tubes; -the axis of each through hole of the second set of through holes is located directly above the axis of the vertical tube of the distribution section; -the dispensing tray comprises a plurality of hollow tubes fastened to the dispensing tray, wherein the hollow tubes are configured to prevent liquid from reaching the through holes in the second set of through holes.
2. 2. The heat exchanger of claim 1, wherein an axis of at least one through-hole of the first set of through-holes is directly above an axis of a center of the regular triangular arrangement of tubes.
3. 3. The heat exchanger according to claim 1 or 2, further comprising a distribution pipe, in particular an L-shaped distribution pipe, wherein one end of the distribution pipe is connected to the liquid inlet and the other end is located above the non-perforated portion of the distribution tray.
4. 4. A heat exchanger according to claim 3, wherein the ends of the distribution tube are located above the non-perforated portion of the distribution tray at a distance of 10.0 mm to 100.0 mm from the distribution tray.
5. 5. The heat exchanger according to claim 3 or 4, wherein the end of the distribution pipe is located above a non-perforated portion of the distribution tray, surrounded by a perforated wall extending from the distribution tray, in particular wherein the wall is cylindrical.
6. 6. The heat exchanger of claim 5, wherein the wall has a height of 100.0 mm to 300.0 mm.
7. 7. The heat exchanger of claim 5 or 6, wherein the wall is cylindrical and the distance between the center of the wall and the center of the distribution tray is 0.0 mm to 25% of the diameter of the distribution tray.
8. 8. The heat exchanger according to any one of claims 1 to 7, wherein the hollow tube has a height of 200.0 mm to 500.0 mm.
9. 9. The heat exchanger according to any one of claims 1 to 8, wherein a diameter of a through hole in the first set of through holes is smaller than a diameter of the through hole in the second set of through holes.
10. 10. The heat exchanger according to any one of claims 1 to 9, wherein the hollow tube is fastened on top of the distribution tray.
11. 11. The heat exchanger according to any one of claims 1 to 9, wherein the hollow tube is fastened inside the through holes in the second set of through holes.
12. 12. A method for condensing a gas stream comprising water, ammonium and carbon dioxide in a heat exchanger according to any one of claims 1 to 11: a) Directing a liquid comprising a passivating agent to a liquid inlet of the heat exchanger, in particular, wherein the passivating agent is oxygen or peroxygen; b) Directing a flow of cooling liquid, such as water, to a cooling medium inlet of the heat exchanger; c) Directing a gas stream comprising water, ammonium and carbon dioxide to a gas inlet of the heat exchanger; d) A fluid comprising liquid condensate is collected from a cooling fluid outlet of the heat exchanger.
13. 13. Use of a vertical top down shell and tube heat exchanger according to any one of claims 1 to 11 for condensing a gas stream, in particular wherein the gas stream comprises water, ammonia and carbon dioxide.

Description

Shell-and-tube heat exchanger Technical Field The present disclosure relates to shell and tube heat exchangers. Background In chemical plants, a heat exchanger is a device that allows heating or cooling a fluid (i.e., liquid or gas) without direct contact with the cooling or heating medium. Such devices are of different designs, one of which is a falling film shell and tube heat exchanger, hereinafter referred to as falling film heat exchanger. A shell and tube heat exchanger is a device comprising a distribution section wherein a fluid to be cooled or heated is introduced into the device and divided into sub-streams, a heat exchange section comprising a body and a plurality of vertical tubes wherein the plurality of vertical tubes direct the fluid to be cooled or heated from the distribution section to a collection section wherein the cooled or heated fluid is recovered. The distribution section and the heat exchange section are separated by a top tube sheet that includes holes to accommodate the vertical tubes. The heat exchange section comprises two spaces, a shell space being a continuous space between the main body and the plurality of vertical tubes in which a heating or cooling medium is circulated, and a tube space being a discontinuous space assembled from the inside of each tube. Typically, in a shell and tube heat exchanger, the tubes are evenly distributed across the cross-section of the shell. Shell and tube heat exchangers are widely used in a variety of industries, such as the fertilizer industry. In some cases, the fluid to be cooled or heated may be a single-phase fluid (liquid or gas) or a two-phase fluid (mixture of liquid and gas). The fluid may contain liquid phase components (such as ammonia, carbon dioxide, water, and urea) and gaseous phase components (such as ammonia, carbon dioxide, and water). The fluid to be cooled or heated may contain corrosive compounds that may react with the heat exchanger. To protect the apparatus, a passivating agent (such as oxygen-containing air or hydrogen peroxide) may be injected in the exchanger or in a section upstream of the apparatus to protect the apparatus that oxygen always moves downstream and thus remains in the liquid solution to be treated. For effective protection of the device it is important that the liquid solution containing the passivating agent is evenly distributed into the vertical tubes of the heat exchanger, that an appropriate distribution of the liquid solution ensures an even distribution of the passivating agent over the exposed surfaces, including the top tube sheet. It has been found that it can be difficult to achieve uniform distribution of the passivating agent-containing liquid over the plurality of vertical tubes and top tube sheet of the heat exchanger, in which case the vapor may condense on the unpassivated surfaces resulting in corrosion. Disclosure of Invention A new shell-and-tube heat exchanger is designed to improve the distribution of a liquid containing a passivating agent. The heat exchanger includes a distributor plate positioned above the top tube sheet of the heat exchanger, wherein the distributor plate is configured to distribute the liquid evenly across the tube sheet, ensuring that each tube of the exchanger receives a portion of the liquid containing the passivating agent and that the area of the top tube sheet between the holes for receiving the vertical tubes is properly and evenly wetted. In a first aspect, the present disclosure provides a vertical top-down shell-and-tube heat exchanger for condensing a gas stream, the heat exchanger comprising a main body, a distribution section, a heat exchange section comprising a set of vertical tubes, a cooling medium inlet, a cooling medium outlet, and a collection section comprising a cooling fluid outlet, wherein: -the distribution section and the heat exchange section are separated by a top tube sheet comprising a plurality of openings configured to receive the vertical tubes; -the distribution section comprises a gas inlet for the gas stream to be condensed, a liquid inlet for the liquid comprising the passivating agent and a distribution tray located below the liquid inlet, wherein the distribution tray (14) is adapted to distribute both the gas stream and the liquid comprising the passivating agent, wherein the distribution tray (14) comprises two sets of through holes perforated to the distribution tray, a first set of through holes being configured to distribute the liquid comprising the passivating agent across the top of the top tube sheet, and a second set of through holes being configured to allow the gas stream to reach the vertical tubes; -the axis of each through hole of the second set of through holes is located directly above the axis of the vertical tube of the distribution section; The dispensing tray comprises a plurality of hollow tubes fastened to the dispensing tray, wherein the hollow tubes are configured to prevent liquid from reach