Process flow and type of steam heater

Process flow and type of steam heater

Compared with small and medium-sized steam heaters, large steam heaters have the same process flow and overall structural type. However, in terms of local structural treatment, there are special aspects that require special treatment of certain structures to meet the heat transfer performance of large gas volumes.

The main structural form is: a vertical structure is adopted as a whole, with the upper tube plate fixed to the flat cover of the shell, and the lower tube plate movable to allow the heat exchange tube to freely expand and contract when heated. The heat exchange tube adopts an integral rolling plate type, and the connection between the heat exchange tube and the tube plate adopts strength welding and adhesive expansion.

The process flow is as follows: saturated steam (or superheated steam) condenses from top to bottom in a vertical finned tube (or condenses again after sensible heat cooling of superheated steam), and the condensed saturated water flows back to the subcooled zone under the action of steam pressure after passing through the vapor-liquid separator. It flows from bottom to top in the finned tube of the subcooled zone for sensible heat exchange. The heated gas flows perpendicular to the finned tube and sweeps across the tube bundle, exchanging heat with the steam inside the tube to achieve the purpose of heat transfer.

The purpose of setting up a vapor-liquid separator is mainly to separate non condensable gases in the steam and avoid the vapor-liquid interface generated in the heat exchange tube under non design working conditions, ensuring that the medium inside the tube entering the subcooled zone is completely saturated with water, and reducing the amount of vapor-liquid

The corrosion caused by the interface on the heat exchange tube and welded joints to improve the service life of the product.

3. Heat transfer calculation:

The purpose of heat transfer calculation is to obtain the total heat transfer coefficient K by calculating the heat transfer coefficients of the inner and outer films of the heat exchange tube, in order to determine the required heat transfer area.

For steam heaters with atmospheric volume, the calculation of heat transfer must fully consider the distribution of process gas flow channels, so that theoretical calculations are more in line with actual operating conditions. We have accumulated rich experience through extensive calculations of small and medium-sized steam heaters, adopted the Rukauska correlation equation and made corrections, and obtained reasonable values.

Www.superbheater.com