What is meant by Shell and tube Steam Condenser?
Shell and Tube Steam Condenser is the most common and practical type of Surface Condenser used in major power plants and industrial applications.
It’s essentially the detailed engineering description of the “surface condenser” we discussed earlier. The name comes from its fundamental construction: a large shell containing a bundle of tubes.
A Shell and Tube Steam Condenser is a heat exchanger where exhaust steam flows around the outside of a bundle of tubes (the shell side) while cooling water flows inside these tubes. The steam transfers its heat to the cooling water through the tube walls and condenses, without the two fluids ever mixing.
1. Shell
- This is the large, cylindrical outer body of the condenser that acts as a pressure vessel.
- It is designed to withstand the internal high vacuum and the external atmospheric pressure.
- The exhaust steam from the turbine enters this space.
2. Tube Bundle
- This is the core of the heat exchanger, consisting of hundreds or thousands of metal tubes (often made of brass, stainless steel, or titanium for corrosion resistance) running through the shell.
- The tubes provide a large surface area for heat transfer between the steam and the cooling water.
3. Tube Sheets
- These are thick metal plates fixed at both ends of the shell. The ends of the tubes are expanded or welded into the tube sheets, creating a leak-proof seal that separates the shell side (steam) from the water box side (cooling water).
4. Water Boxes
- These are chambers attached to the inlet and outlet sides of the tube sheets.
- Function: They distribute the cooling water to the tube bundle and collect it after it has passed through the tubes. They often have internal partitions to create multiple passes.
5. Hot well
- The bottom portion of the shell acts as a reservoir where the condensed steam (now called condensate) collects.
6. Air Cooling Section
- A dedicated section of the tube bundle, often shielded by baffles, where the non-condensable gases (like air) are cooled down. This helps to separate any remaining water vapor from them before they are extracted, improving the efficiency of the vacuum system.