Schubert & Salzer develops a new kind of desuperheater by integrating a segmented disc valve with four injection nozzles on the lance – the 5090 Desuperheater. The advantages of this valve technology can be used for the finely tuned regulation of steam networks.
The main flow control element for the injected water - segment discs that slide over and mutually seal each other - are positioned perpendicular to the direction of flow in the body of the segmented disc valve. On a non-rotating segment disc with four segment openings, a movable disc with the same number of segments rotates so that the four segment openings open precisely and continuously in sequence. Each segment opening is connected to an injection nozzle by a lance so that the four injection nozzles - depending on the control requirements – increase their flow rate. The four serial nozzles in the system offer a wide control range and ensure that the water pressure in the nozzles remains almost constant. This enables a much finer atomization of the water and optimal control of the steam. At the same time, the risk of accumulations of water in the steam system is minimized.
With this design, segmented disc valves combine precise control under extreme operating conditions with high seal tightness, lower noise emissions and low wear. Another advantage of the Schubert & Salzer desuperheater is the control unit consisting of segmented disc valves with proven 8049 digital positioners is located outside of the flow of steam. This means the amount of water injected is controlled outside of the hot steam pipe. Thermal distortion due to the temperature difference is thus eliminated and leaks are minimized. The temperature of the injection medium can be up to +220°C. The immersion depth of the spraying nozzle lance is between 150 and 900 mm and can be adapted exactly to the requirements of the system.
The segmented disc valve offers a rangeability Kvs/Kvmin of 60:1 with a modified linear characteristic. The leakage rate is < 0.001% of the Kvs value. The nominal size of the injection valve on the input is DN 25 or DN 50. The nominal size of the cooling water connection is DN 100. The nominal pressure is PN 40 or ANSI 300. The entire desuperheater is manufactured from stainless steel. The sealing towards the control actuator uses a preloaded PTFE packing set. An attachment of positioners according to the NAMUR recommendation is also possible as an option.