The welded heat exchangers cost less. However, they do not have such advantage as the possibility to be dismounted and cleaned. Cleaning of welded heat exchangers is performed by means of chemichal wash. However, the welded heat exchangers withstand higher pressure and temperature in comparison with dismountable ones.
Exceptional small size and self-cleaning ability make the spiral heat exchangers be the general-purpose equipment applied to liquid nonhomogeneous medium tending to deposit formation on the heat transfer surface as well as with vapour or gas condensation under the conditions of high vacuum.
Application. Spiral heat exchangers are used in alcohol, food, pharmaceutical, oil, chemical industries, housing and communal services as well as the other branches of industry where it is important to provide effective heat exchange. Application of spiral heat exchangers at the enterprises of alcohol industry gives opportunity to reduce water consumption substantially.
It is possible to use fluids that contain 20% of solids (saccharified wort, brew), as well as counter flows gas-liquid and gas-gas. Horizontal spiral heat exchangers are used for heat exchanging between two fluids. Vertical spiral heat exchangers are used for heat exchanging between condensable vapour and liquid. Such heat exchangers are used as condensers and steam heaters for heating fluids.
The Advantages of Spiral Heat Exchangers:
High heat transfer coefficient that can reach 3820 kcal/m2×hr×0C which is two times or three times higher than the coefficient of the tube-type heat exchangers.
Dependable design, due to the sealing of both channels counter currents do not interflow.
Comparing to the tube-type heat exchangers, spiral heat exchangers (SHE) occupy less space.
Possibility to treat media containing pulp, fiber, solid residue (up to 20%) as well as viscous fluids.
The advantages of spiral heat exchangers are: compact design, the low pressure drop and efficient heat transfer at the increased rate of heat transfer medium.
Easy access to internal surfaces and channels. Due to their detachable covers, the spiral heat exchangers are easy to be maintaned. It is pretty enough to remove the covers in order to get access to the channel surface to perform inspection and cleaning.
Possibility to treat media at temperature above 200-300°Ñ, which is very important when applied in chemical industry.
Design Features. In spiral heat exchangers the heating area is formed by two thin metal strips welded to the split center (core) and coiled. Self-reinforced fittings are welded to the both sides of the metal strips to fix the distance between them and reinforce them. Rectangular spiral channels are limited by the end covers. Spiral heat exchangers can be vertical and horizontal; they are often installed in blocks of two, four and eight units.
Nowadays, spiral heat exchangers are determined to be the most reliable and easy-to-operate. All mentioned above proves wide application experience of heat exchangers both in Ukraine and Russia.
Having installed spiral heat exchangers in recuperative cycles and process improvement at the state owned enterprise Chervonoslobodskoy Alcohol Plant, we reached 3,9-4,2 m3 of gas per one dal of pure alcohol which is in average 35%-40% less comparing to the previous period.