How to perform rapid blowdown of the differential pressure transmitter for the boiler drum water level?
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This post was last edited by yunrun on 2018-3-5 at 16:26. The differential pressure transmitter for the boiler drum water level is an important instrument in the measurement and control system of the drum water level; to ensure the unobstructed flow of the pressure guiding tubes, it is essential to conduct regular inspections and cleanings of these tubes as well as to perform drain operations as part of the maintenance routine. Waste discharge involves flushing the pressure guide tube with steam, and the instruments can only be put into operation once there is sufficient condensed water available; this process usually takes over an hour. To save time, manual addition of water is sometimes employed. Is there a better way? Yes, Changhui Instruments details it in this post. By using the hot water in the boiler drum to flush the pressure guiding tubes, and relying on the water pressure in the drum to add water to the two-chamber balance vessel, it is possible to carry out immediate waste discharge and immediate activation of the instruments. By referring to the diagram below and following the corresponding methods and steps, it is possible to quickly set up the differential pressure transmitter for the water level in the steam drum. http://yunrun.com.cn/upload/201607/19/201607191745139072.jpg ① First, close the positive and negative pressure valves 5 and 6 of the three valve assemblies simultaneously, and open the balance valve 7. ② Close the liquid-phase valve 2 of the two-chamber balance vessel, open the gas-phase valve 1, and alternately open and close the drain valves 3 and 4. The steam from the drum enters the two-chamber balance vessel through valve 1; first, the positive and negative pressure guiding pipes as well as the drains are flushed with steam. ③ Close the vapor-phase valve 1 of the two-chamber balance vessel, open the liquid-phase valve 2, and alternately open and close the drain valves 3 and 4. The hot water from the drum enters the two-chamber balance vessel through valve 2, which is then used to flush the positive and negative pressure guide tubes as well as the drains. ④ First close drain valve 3, then close drain valve 4; this way, the positive and negative pressure chambers of the two-chamber balanced container as well as the pressure guide tubes are all filled with hot water. ⑤ Open the positive pressure valve 5 of the three-valve assembly, close the balance valve 7, open the negative pressure valve 6 of the three-valve assembly, and then open the vapor phase valve 1; the drum water level differential pressure transmitter can then be put into operation
Good experience, thanks for sharing. We usually let it condense naturally after flushing, which takes a long time.....
The design is truly ingenious! Worth learning from!
The method is good; it’s a bit troublesome to handle the differential pressure transmitter on the ground floor.
In the diagram shown by the poster, the bottom of the two-chamber balanced vessel is missing an outlet that leads to the connected pipeline. Doing this does not ensure that the density of the water in the double-chamber balanced container is the same as that in the drum, which affects the measurement accuracy! By connecting the bottom of the two-chamber balance container to the parallel pipeline, it is ensured that the water in the container is continuously replaced, which maintains a constant water temperature within the container and thus ensures measurement accuracy.
I just followed the method from floor 1, and it works well!