In a cascade system, blow-through is re-used as make-up steam supply in a different steam section(s) operated at lower make-up pressure. A primary limitation of cascade systems is that the maximum make -up pressure obtainable in cascade pressure group is capped based on the steam make-up pressure and required differential pressure of the upstream pressure group. Thus, the pressure groups cannot be independently controlled. In addition, blow-through from at least one pressure group cannot be cascaded into a downstream section, creating inherent steam waste.
Each coil drainage unit is designed and optimized using Deublin Process Simulation. This simulates performance of the system at all conditions of operation. Process Simulation ensures that all separators, thermocompressor, valves, and lines are sized properly, and that operation of the system is optimized.
Deublin’s proprietary design for high-efficiency steam coil drainage optimizes heat transfer efficiency by providing a constant pressure drop across the coils, in addition to gravity. An inherent inefficiency of traditional designs is the reliance on gravity alone for drainage of the coils (differential pressure is available across the steam trap, not the coils).
Condensing rates vary and are inconsistent from tube to tube due to irregular airflow across the tubes within the coil bank. Gravity tends to help the heavily condensing tubes while the resultant pressure head produced by these tubes impedes the flow of condensate from the lighter-condensing tubes. Consequently, heat transfer efficiency is reduced. The Deublin design solves this problem and improves overall heat transfer by using a thermocompressor to maintain a moderate pressure drop across the coils. A small amount of condensate from the coils is separated and flashed to become recirculation steam. The thermocompressor creates suction of this recirculation steam and recompresses it to the coil supply steam pressure using a small amount of higher-pressure motive steam. Within the coils, the vapor state is retained over a greater area of the coil bank. Thus, heat transfer is maximized, and proper drainage is assured for all the tubes within the bank of coils.