Corrosion-proof heat exchangers
Heat exchangers come in different designs depending on the application in which they will be used. In some cases, the media is corrosive, making plastic a good option for a durable, long-lasting and safe solution.
With higher energy prices, there is increasing interest in energy recovery. Using a heat exchanger to recover energy from industrial processes can save both money and resources.
Plastic heat exchangers
The most common is to have a metal heat exchanger, whether using gas/gas, gas/liquid or liquid/liquid to move thermal energy to or from one location to another. When working with corrosive fluids and media, a plastic heat exchanger is preferable as a metal one would most likely corrode.
Depending on the temperature range of the media, heat exchangers are available in Polyethylene (PE) or Polyvinylidene fluoride (PVDF). PE is cheaper, while PVDF can withstand temperatures up to 130°C and has a better chemical resistance.
Gas/air heat exchanger
The easiest application to heat exchange from is ventilation air. Usually there are thin pipes around the application where the air can be transported. The heat energy from the gas is transferred to the appropriate media and then sent to a heat pump or other place where it is needed.
If the corrosive media need to be cooled, for example to condense out certain elements in the gas, the heat exchanger can be run backwards. If you want to utilise sulphuric acid, for example, it is a great advantage to have the heat exchanger in plastic because it is resistant to the acid.
Other applications where cleanliness is important, such as fish farms, PVDF can be a good inert material.
Heat exchanger for heating
In pickling baths, the opposite problem is encountered, i.e. the need to add energy to the pickling bath in order to make the pickling process sufficiently fast. By placing flat gas/heat exchangers on the edge, and running steam through the gas section, aggressive media such as hydrofluoric acid, sulphuric acid, nitric acid solutions can be heated.
PE-RT tube/plate heat exchanger model HX from Calorplast.
Because the heat exchangers are modular, they can be easily adapted to the current power requirement. As the heat exchanger has a large number of channels, it does not matter if one of them breaks. By welding or plugging the broken channel, the rest of the heat exchanger can be operated as usual.
Liquid/liquid heat exchanger
If instead liquid/liquid is to be heat exchanged, the heat exchanger becomes more compact. The heat exchanger can be used to heat corrosive acids, cool down corrosive media or to utilise energy from corrosive processes. Here too, the heat exchangers are modular, which means that the length of the exchanger is adapted to the energy transfer requirements.
Applications
Gas/gas heat exchanger in glass fibre.
Common applications are pickling baths, where the baths need to be heated. Plastic heat exchangers are used in energy recovery from liquefaction processes. In biogas applications, sulphur needs to be removed from the gas before burning it.
The gas/liquid heat exchanger can be used industrially, to condense acids, but also on a smaller scale, for example for energy recovery in laboratories.
Salt water is also corrosive, whether it is seawater or salt water in fish farms or large aquariums.
Gas/gas heat exchangers completely eliminate the problem of corrosive joints and can be used up to 10,000 Nm3/h and maximum 120 °C.
Lyma has long experience with heat exchangers
At Lyma, we have been working with corrosive liquids for over 40 years. We have extensive experience in material selection and can help you to more easily combine the right material for your liquid. Contact us directly may receive personalised service or read more about us.