Frequent internal leakage of the XV shut-off valve
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The inner coiled tubes of the reactor are fed with circulating water and steam at 2.1 Mpa respectively. The circulating water serves as a part of the interlock protection system in case of an emergency. The XV valve used here is of DN100 size, with an EK code from Taiwan’s Zhongding Valve Company; it has experienced multiple instances of internal leakage. Since one side of the valve body is exposed to 220°C temperatures while the other side is in contact with circulating water, water hammer effects are very severe, and there is a constant risk that the pipes and gaskets might break. The current configuration consists of: a water distribution tank – a butterfly valve – a check valve – an XV valve (which has had multiple internal leaks and operates in a normally closed state) – and steam at 220°C. I’m wondering if there are any improvements that could be made. My personal idea is to adjust the position of the check valve and use a high-quality one; I’m not sure if this can help extend the lifespan of the XV. I’d appreciate some guidance
Install manual valves for technical upgrades; when necessary, use these manual valves to shut off the material flow
Manual valves can be controlled, but this inadvertently increases the frequency of manual operations, thereby inevitably reducing the interlock level. This valve opens only in an emergency situation to cool down the reactor; if operated manually, its reliability cannot guarantee the protective function of this setup
Manual valves can be controlled, but this inadvertently increases the frequency of manual operations, thereby inevitably reducing the interlock level. This valve opens only in an emergency situation to cool down the reactor; if operated manually, its reliability cannot guarantee the protective function of this setup
Manual valves can be controlled, but this inadvertently increases the frequency of manual operations, thereby inevitably reducing the interlock level. This valve opens only in an emergency situation to cool down the reactor; if operated manually, its reliability cannot guarantee the protective function of this setup
Can the steam be fed into the reactor after being depressurized, or could a better valve be used? Safety relief valves need to have a certain SIL rating depending on the level of risk in your operation; the current valve you have does not even meet the SIL1 requirement.
Install a manual relief valve that can be manually closed when not in use
Renovation idea: 1. Add two valves. When steam or water leaks into the short connection located between the valves, the steam heats up this water (or this water is actually condensate), thereby reducing the temperature difference gradient. 2. Install a burst disc; depending on the operating conditions, one burst disc is installed, which functions as a blind plate in normal situations. In the event of an emergency, when the valve needs to be opened or closed completely, the rupture disc will break apart (it is essential to take pressure into consideration; otherwise, internal leakage in the valve may cause the rupture disc to explode prematurely, resulting in no effect or failure to explode at a critical moment. I have encountered such situations, so it is necessary to conduct a thorough analysis of the operating conditions and the forces involved). 3. Add an additional check valve. It’s what you mentioned earlier: installing a check valve (check valves generally have limited sealing performance, so it’s important to choose one carefully)
Thank you. The idea is to ignore the first valve and leave it in a slightly leaking state; a section of straight pipe is used afterward as a buffer for the high-temperature water, and finally, a reliable XV valve is used for sealing. I think that over an extended period of time, the condensate in even the longest buffer sections will evaporate. Wouldn’t it be better if this buffer pipe could be made vertical? Also, is it possible to create a necking section before the check valve?
This post was last edited by shiwendong on 2017-7-13 at 23:33. Given the severe water hammer effect, it is highly recommended to install a constant flow valve: a constant flow valve is an automatic control valve that maintains a steady flow rate of the fluid in the pipeline, even when there are fluctuations in that flow rate. Installing a constant flow valve on the pipeline enables operation at a stable flow rate, and it prevents damage to other pipeline equipment caused by phenomena such as \"water hammer\" resulting from sudden changes in flow rate within the pipeline. There is internal leakage in the shut-off valve. I’m not sure whether you have chosen a hard-sealed ball valve or some other type of valve; soft-sealed ball valves, for example, cannot handle media at temperatures of 220 degrees. XV should be a soft-sealed V-ball valve
Whether the buffer pipe is made vertical or horizontal makes little difference. A longer buffer section can maintain balance on its own through heat dissipation, even when there is minimal steam leakage. Furthermore, when a water hammer occurs, pressure impacts the valve cores of both valves; however, if the original valve has leakage, it provides a pressure buffering effect. Another approach is to add a small pipeline to the buffer section (if cost savings are a concern, it’s also possible to omit the second valve); a self-acting control valve is installed on this pipeline, which automatically releases pressure when it’s too high (it functions similarly to a safety valve, but with fewer complex mechanisms). In winter, it is necessary to be careful to prevent freezing.