Shell-and-tube Heat Exchanger Designed for Steam Heating of Various Liquids

Shell-and-tube Heat Exchanger Designed for Steam Heating of Various Liquids

Working Principle

Steam Input and Condensation: High-temperature steam (typically saturated steam) enters the shell side of the exchanger (in rare cases the tube side), contacting the cooler outer surface of the heat transfer tubes.

Heat Transfer: The steam condenses on the outer tube wall, releasing substantial latent heat. The heat is transferred through the highly thermally conductive tube walls (often copper or carbon steel tubes) to the liquid being heated flowing in the tube side.

Liquid Heating and Condensate Drainage: The liquid in the tube side absorbs the heat, increasing in temperature, and eventually exits through the outlet. Meanwhile, the condensate formed from the condensed steam is promptly drained from the heat exchanger via a steam trap, preventing condensate buildup that could impair heat transfer efficiency.

Key Structural Design (Adapted for Steam Heating Applications)

To accommodate steam heating characteristics, the structural design emphasizes specific features:

Flow Path Allocation: Steam typically flows through the shell side, while the liquid to be heated flows through the tube side. The larger shell-side space facilitates steam diffusion and condensate drainage. The tube side employs multiple heat transfer tubes to increase the contact area between the liquid and tube walls, enhancing heating efficiency.

Heat Exchange Tubes: Primarily copper alloy tubes (high thermal conductivity) or carbon steel tubes (low cost, pressure-resistant) are used. In some scenarios, fins are applied to the tube walls to further expand the contact area with steam.

Drainage Device: A drain valve must be installed at the bottom of the shell side—this is a core component. It automatically discharges condensate while preventing leakage of uncondensed steam, ensuring continuous and efficient heat release from the steam.

Baffles and Deflectors: Bow-shaped baffles or deflector rods are installed within the shell side to force steam to change direction multiple times. This prevents “short-circuiting” of steam flow and ensures thorough contact between steam and heat exchange tubes.

Typical Application Areas

Due to their high heat transfer efficiency and compatibility with steam heat sources, these heat exchangers are widely used in scenarios requiring liquid heating:

Industrial Production: Heating reaction feedstocks in chemical plants, heating process liquids (e.g., milk, syrup) in food processing, and heating pharmaceutical solutions in drug manufacturing.

Commercial & Residential: Domestic hot water preparation in hotels and hospitals, water-side heating in large central air conditioning systems.

Energy & Environmental Protection: Preheating process water in power plants or factories, heating liquids in wastewater treatment processes (e.g., heating influent for anaerobic reactors).