Dry Cooling - A-Tube Hot dip galvanized steel fin tubes
GEA's hot dipped galvanized fin tubes (A-Tube) provide reliable long-term performance, which is an essential criterion of the condensing system. These fin tubes with elliptical core tubes and rectangular fins were developed specifically for vacuum steam condensing service for power stations and provide the following essential features required for this application:
Durable carbon steel materials
(30+ year service life.)
All carbon steel construction (core tubes and fins) provide reliable long term performance matching the plant's service life and are extremely durable, capable of withstanding high-pressure water spray for periodic cleaning as well as localized loads applied by personnel stepping on the fins during normal erection or maintenance procedures. These fin tubes also have the capability to sustain impact of hail or other falling debris. Elliptical tube (2 rows) with
individual rectangular fins.
The A-Tube design utilizes an elliptical shaped tube with an efficient air foil shape to minimize air-side flow resistance resulting in improved performance characteristics compared to round tube types. The use of a double tube row allows for effective fin tube cleaning since each tube row is accessible to direct water spray and the individual rectangular steel fins provide a straight through flow path, unlike helically wrapped fins.  Steel fins flanged to tube before galvanizing.
With GEA's hot dip galvanized elliptical fin tube design, the rectangular carbon steel fins are attached to the core tube with a mechanical bond. The steel fin features an L-shaped collar, providing a conical gap between the core tube and fin collar. During the galvanizing process, the zinc fills the interspace between the fin flange and the core tube creating a connection that is mechanically strong, as well as creating a high conductivity connection between fin and tube. This strong, high conductivity connection withstands temperature changes and vibrations, and ensures constant heat transfer performance during its entire service life.
Superior corrosion protection
from HDG process.
During the galvanizing process, a zinc coating of uniform thickness is applied over the entire exterior surface of the fin tube providing long-term cathodic protection against corrosion. Following installation at site and commiss-ioning, a zinc oxide layer rapidly forms on the outer surfaces of the fin tubes. This non-toxic outer layer prevents loss of zinc from the galvanized surfaces and helps maintain the protection of the fin tubes from corrosion throughout the service life. Superior cleanability using
high-pressure water.
GEA's galvanized steel fins can withstand water spray pressure in excess of 3,000 psig. This high pressure cleaning is sufficient to dislodge any dirt or particulates  deposited on our two rows of galvanized steel fin tubes with minimum water usage. GEA has developed a semi-automatic fin tube bundle cleaning system designed exclusively to thoroughly clean the external surface of the fin tubes. Based on the extremely rugged construction, resistance to corrosion and superior cleanability of the proposed galvanized steel fin tubes, GEA air-cooled condensers can maintain full thermal capability for the life of the plant. Compact design with high extended
surface area ratio (> 117:1).
Due to the superior performance characteristics of the A-Tube with a very high extended surface ratio of 117 to 1, the air-cooled condenser results in an extremely compact design compared to 3 and 4 tube row systems. Based on its high heat transfer coefficient at moderate to high air velocities across the heat exchanger surface, the A-Tube will typically provide the most economical solution (lowest capital cost) in standard noise applications where a high fan power density is required. When a high value is placed on fan power consumption or when extreme low noise emission is required, GEA's ALEX technology is usually the most economical solution.
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