Tube air preheaters are widely used and considered to be conventional heat exchangers for air preheating. Tube heat exchanger builds up a system of steel pipes, inside of which the hot gases produced during combustion process move. The incoming air passes through this system and receives thermal energy through the surface of the pipes, after which it is fed into the combustion chamber and improves the combustion of the energy carrier in the boiler.
The main disadvantage of tube units is a low heat transfer coefficient, for this reason, a large heat transfer surface is needed, as a result of which tube air preheaters with a large thermal capacity is characterized by large dimensions.
Air preheaters of this type have a rather simple structure and are reliable in operation, but they are highly susceptible to corrosion due to condensate formed at a low wall temperature (temperature difference). Heated incoming air helps to reduce the moisture.
OPT air preheaters
OPT air heaters with innovative design has no such disadvantages. In OPT units, air and exhaust gases pass through a module that consists of steel panels. ribbed panels are heat transfer elements and separate medium flows, forming alternating sealed channels, the cross section of which can vary depending on the performance requirements of the air heater. For the manufacture of panels, heat-resistant and corrosion-resistant steel are used, the steel grade is selected depending on the operating conditions.
Due to the design features, OPT air preheaters are compact in combination with high efficiency. They can be installed where the installation of traditional tube air preheaters is not possible due to their large size. Increase or decrease in power can be carried out without changing the dimensions of the device. Air preheating for OPT is also not required, and maintenance is easy and simple.
Thus, it is obvious that the tube air preheaters are significantly inferior to OPT heat exchangers at almost all positions.