![]() In cooling applications, systems can overheat if not adequately controlled. For heating temperature-sensitive instruments or process fluids, the reduced temperature available for tracing simplifies operations and eliminates overheating problems.īy relying on an automatically operated system to manage steam tracing, you can save thousands of dollars and eliminate errors associated with manual operations. HAT or TV/HAT valves act as steam traps and discharge condensate well below the steam temperature, eliminating live steam loss. US/A and US/S-X valves are available with NPT connections, and TV/SC-A and TV/US-X valves have tube fitting connection ends. US/S-X or TV/US-X valves regulate the flow of heating media in response to the process temperature or the pipe’s surface temperature to control heat trace lines. TV/SC-A and US/A valves can be used to turn on steam, air, gas, or liquids in response to ambient temperature change to protect lines from freezing. The system’s automatic response to temperature ensures your water lines are freeze protected while eliminating wasted steam. Then, they will turn it off whenever the ambient or surface temperature reaches the specified closing temperature. These highly durable self-actuating valves will automatically turn on steam to keep water lines from freezing. ThermOmegaTech’s thermally actuated steam control valves regulate the flow of steam, gas, or other fluid by sensing the ambient or surface temperature. While this eliminates the chance of freeze damage from forgetting to activate the steam on any particular day, it wastes a lot of steam on those days that temperatures are above freezing. Since temperatures fluctuate throughout the winter, many plants turn on the trace system at the beginning of their winter season and leave it on until spring. Typical winterization procedures at a plant require steam tracing to be turned on during periods of cold weather when temperatures could drop below freezing. Steam traced systems use a facility’s existing steam supply but can be costly because of the winterization procedures and unregulated steam. Steam has a high latent heat, thus making it an effective heating medium and does not create electrical sparks like its alternative, electric heat tracing. The expected flow reversal in the lowest tube layers during the simulated natural circulation phase was found also in the TRACE code calculations.Steam tracing is still the most common type of industrial pipe tracing used for freeze protection. ![]() Especially the timing of initiation of the superheating was better estimated. Therefore, more detailed modeling of the pipe layers increased the accuracy of the results. The steam superheating in the calculations was possible only after the uppermost cell on the secondary side had voided thoroughly. In the experiment the steam started to superheat immediately when the uppermost tube layer had uncovered. The calculations overestimated slightly this heat transfer. The heat transfer from the primary to the secondary side degraded gradually during the uncovery of the heat exchange tubes. However, at the final state the calculated secondary side collapsed level had decreased more than in the experiment. In the simulation of PACTEL loss-of-feedwater experiment LOF-10, the main parameters of the calculations in rather good agreement with the experiment. ![]() Different nodalization options were introduced. The phenomenon of heat transfer from primary to secondary side, steam superheating and flow reversal in the lowest heat exchange tubes were studied in detail. The calculation results showed that TRACE is capable in simulating horizontal steam generator behavior both in steady state and during loss-of-feedwater transient. PACTEL experiment LOF-10 was chosen for this assessment. ![]() The main objectives were to prepare a simulation model for its horizontal steam generator with the TRACE thermal hydraulic code and assess different modeling options of the code. Parallel Channel Test Loop (PACTEL) is an integral test facility for a VVER-440 type nuclear reactor. This paper describes the modeling of horizontal steam generator with the TRACE code and calculation results of a loss-of-feedwater (LOF-10) experiment at the PACTEL facility.
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