Tube-in-tube condenser

Tube-in-tube condenser structure
The tube-type condenser is primarily composed of the shell, tube sheet (also known as the header), tube bundle, and top cover (also referred to as the head). Parallel tube bundles are fitted inside the circular shell, with the ends of the tubes fixed to the tube sheet. The method of fixing tubes to the tube sheet is generally by welding or胀管法 (expansion fitting method). The top cover, equipped with inlet or outlet tubes, is connected to the shell ends with bolts. It forms a fluid distribution chamber between the top cover and the tube sheet. It is widely used due to its simple and sturdy structure, ease of manufacturing, broad range of materials, high processing capacity, and strong adaptability.
During heat exchange, cooling water enters through the connection pipes at the top cover, flows within the pipes, and this path is called the tube side; harmful vapors flow within the gap between the tube bundle and the shell, and this path is called the shell side; the surface area of the tube bundle is the heat transfer area. In the condensation recovery process, whether it is the condensation of saturated vapor or the condensation containing non-condensable gas, generally speaking, condensation occurs in the shell side of the horizontal condenser because it is more reasonable in terms of heat transfer, pressure drop, and cleaning.

Tube-in-tube condenser types
(1) Fixed tube sheet heat exchangers: Simple and compact structure, capable of withstanding high pressure, low cost, easy to clean in the tube side, and easy to block or replace tubes when damaged.
(2) Floating Head Heat Exchanger: Easy to clean inside and between tubes, and does not produce thermal stress.
(3) U-tube Heat Exchanger: Consists of a single tube plate with the tube bundle made up of multiple U-shaped tubes. The ends of the tubes are fixed on the same tube plate, allowing for free expansion and contraction. No thermal stress is generated when there is a temperature difference between the shell and the U-tube heat exchanger.
(4) Sliding tube sheet heat exchangers: Simple structure, low cost, and can add baffles to the tube box as needed to enhance heat transfer.

Features of Tube-in-Tube Condensers
(1) The horizontal shell-side condensing film heat transfer coefficient is several times higher than that of the vertical tube internal or external film heat transfer coefficient, and non-condensibles do not accumulate in dead corners, making them easier to排出.
(2) The cooling water flows through the pipes for easy scaling removal. Water flow within the pipes ensures a higher velocity, which is beneficial for reducing scaling formation rate and enhancing the heat transfer coefficient of the water film.
(3) Tube-in-tube condensers are designed to keep the lower tubes at the cooling water inlet, allowing condensate to accumulate at the bottom for temperature reduction. In surface condensing systems, it is crucial to further cool the condensate. If the condensing system temperature is high, organic gases will volatilize significantly upon contact with air. Generally, the outlet temperature of the condensate should be 60°C or lower. Of course, an additional cooler can be added, but this will increase costs.