ASME PTC 12.1:2015 pdf free download

ASME PTC 12.1:2015 pdf free download.Closed Feedwater Heaters.
(a) Venting. Noncondensable gas accumulation in both the condensing and drain cooling zones of the heater may degrade the performance of the heater by blanketing some heat transfer surface area. It may also lead to corrosion of heater internals. If a heater is not performing properl the venting system design and operation should be checked. Depending on water chemistry control on the generating unit to be tested, the vent operation strategy should be determined by agreement by the parties of the test.
Troubleshooting the entire venting system design is beyond the scope of this Code; however, a simple test to determine whether the vent orifice is properly sized and free of obstruction may be performed as follows. With the heater venting normally, and the cycle at steady-state conditions, conduct a preliminary test run. When this is complete, open the heater vent flow orifice bypass valve to ensure increased vent flow. This mode should be maintained for approximately ! hr to sufficiently purge the heater of noncondensables. Once this purging is complete, repeat the run. Comparison of the feedwater outlet temperatures of these two runs should yield close agreement. If there is a significant difference, an improperly sized or obstructed orifice should be suspected and corrective actions taken. If the heater is being continuously vented at no more than 0,5% of design steam flow, this will have negligible effect on the thermal performance
(b) Water L.erxl. It is important that the normal water level at the drain cooling zone inlet is maintained as close as possible to the optimum set point. Keep in mind that the location of liquid level taps shall reflect the level at the zone inlet since the heater liquid level, front to back, is not flat, 11 the water level is higher than optimum, some additional heat transfer surface area in the condensing zone may be flooded; this may reduce the heat transfer capability, and may, in turn, cause the TTI) to be adversely affected. The DCA will decrease slightly when water level in the heater is higher than optimum. If the water level in the heater is such that it allows steam to enter the drain cooling zone, the DCA will significantly increase, and may cause drain cooling zone damage. The lTD will decrease slightly when water level in the heater is lower than optimum.
The following method may be used to establish the optimum normal liquid level set point for horizontal.