Heat Exchanger For Steam Heating

Materials of Construction

Materials of construction for the Immersion Coil Heat Exchanger consists of either polypropylene, PVDF, or PTFE for the frame, and either FEP, PFA, or PTFE for the tubing. Custom designs may include other fluoropolymer materials such as ETFE, ECTFE or PCTFE.

Advantages

The advantages of our heat exchanger products over alternative designs include:

Low operating cost - The operating cost includes maintenance such as inspection, cleaning, downtime, and repair. This is primarily due to the relatively simple design that involves no plastic welding joints

No weld joints - Unlike metals that are subject to more rapid degradation under aggressive pickle bath conditions, Fluorotherm’s heat exchangers withstand aggressiveness

Off the shelf repair kits - In case of an unlikely event of accidental tube damage, these kits enable a quick repair of the tubing

No tube bundling - The strong tubing coils are optimally spaced so acid flow and therefore heat transfer is maintained without fouling.

Constant operating efficiency - Fluoropolymers such as PTFE, FEP or PFA, are inherently “non-stick”, so fouling by scale deposition is minimized, assuring a constant operating efficiency that does not decrease over time. No other material, except natural diamond, inhibits sticking of the pickle bath particulates more than fluoropolymers

Today, Immersion Coils for heating and cooling are available in a variety of shapes, materials, designs and assemblies from various manufacturers. Polymer (Polyethylene, High Performance fluoropolymer), common and exotic metal alloys, pancake coil shapes, racetrack coils, grid structures, spaghetti tube U bends, welded and non-welded tube terminations, and tube ends connected to a manifold are among the many options available. Less than fully informed decisions lead to suboptimal or wrong choices (for example, based on purchase price only). Such choices end up in faster than expected deteriorating performance or even catastrophic failure. Among materials, fluoropolymer coils have been around for 40+ years, and have secured a unique position in a multitude of diverse industries that use heat exchangers for temperature control of corrosive chemicals and ultrapure liquids.

What are Fluoropolymers?

Fluoropolymers are thermoplastics with fluorine as part of their chemical structure. Most common plastics such as polyethylene and polypropylene have hydrogen in their structure. The substitution of hydrogen with fluorine imparts some unique properties, such as chemical inertness, high use temperature, flame resistance, low coefficient of friction, and “non-stick” characteristic, among others. FEP, PFA PVDF, PTFE are among the more popular polymers, in addition to some others such as ETFE, PCTFE etc. The maximum use temperature, pressure rating, thermal conductivity, and FLUOROTHERM flexibility are some of the properties that determine the best resin for use in a specific application.

Why Fluoropolymers instead of metals for heat exchangers?

While metal heat exchangers (made of carbon and stainless steel, copper, aluminum), and now low temperature plastic (polyethylene) are utilized in many commercial and household products, air conditioners and space heating for example, where corrosion or contamination may not be a serious concern, many industrial and specialty applications require the heating and/or cooling of corrosive acids, alkalis, organics. Radiant floor heating is an exception, and there is new interest in using fluoropolymers because of their long life – the low temperature rated tubes turn brittle are not readily accessible for repair after installation. Fluoropolymers are ideally suited for facilitating heat transfer in chemically aggressive environments., common metal heat exchangers will not last very long when exposed to the liquid or vapor.

The primary reasons dictating the choice of fluoropolymer heat exchangers are the following

• They are corrosion resistant, unlike their metal and other material counterparts

• They can handle reasonably high bath temperatures, up to about 310 F

• Steam at pressures up to 80 psi can be used as a heating medium

• Fluoropolymers are ultrapure materials, their innate chemical inertness makes them unreactive to most chemicals, including organics.