TD thermal degasser

Dissolved O₂ and CO₂ in feedwater corrode boiler walls, steam piping and the machines that run on steam. In the TD, a spray nozzle breaks the feedwater into fine droplets that mix with steam and heat up to saturation; CO₂ leaves the water at around 60 °C and O₂ above 100 °C. The water then enters a stainless mixing chamber made of two concentric perforated shells, where rising steam scrubs it a second time, and the released gases are vented through the gas outlet valve. A thermostatic valve on the lower vessel holds the temperature at 102 °C, which prevents thermal shock.

TSB builds two modern types, both handling 1–50 t/h without the degasser having to be mounted high up. In the pressurised type, degasser and condensate tank share a single tank at floor level; feedwater is atomised under pressure and heated to 102 °C by low-pressure steam, with a degassing efficiency of 96–100 %. Because the system is closed to atmosphere, no flash steam escapes; condensate lines see a back pressure of around 0.5 atm (gauge), and the tank is designed for 3 bar. The atmospheric type serves open condensate systems: water is kept at 90 °C, flash steam and steam escaping from traps are put to use, and degassing efficiency is 90–95 %.

A classic degasser has to stand at least 4 m above the pumps to avoid cavitation, which calls for boiler houses 7–8 m high and steel support structures; the modern types remove that cost. Shell and dished ends are P355GH plate to EN 10028-2, nozzle tubes P235GH or P265GH, the degasser dome AISI304 and the cascade plates AISI316 stainless steel. The PLC supervises staged water level safeguards, steam temperature and emergency shutdown, and pressure is set according to site altitude to avoid needless energy loss. On request, a version certified to ATEX for Ex zone 1 is built.