What causes abnormal noises in the steam heating pipes of power plants?
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This post was last edited by Heat exchanger or Plate heat exchanger on 2023-12-29 at 16:19. In a project in the north, waste heat from a power plant is utilized; superheated steam is used as the heat source (the hot side), and after heat exchange through a heat exchanger, it is supplied to the water supply/return system (the cold side) for heating purposes. The steam pipeline (DN200) coming from the power plant is about 3 kilometers long. After pressure reduction, it enters the steam distribution cylinder, where the operating pressure is 2–3 kilograms and the temperature is around 200 degrees. The pipes leading from the steam distribution cylinder go into the heat exchanger; on the pipes before entering the heat exchanger, the steam pressure gauge shows almost no pressure, with a temperature of around 95 degrees. The system operates smoothly under normal conditions, with good heat exchange performance, and there are no unusual noises. However, sometimes there is a sound like “thud”! Bang! Bang! The sound lasts for a few minutes, sometimes over ten minutes, resembling the impact sound of a water hammer. A steam trap is installed on the steam distribution cylinder, and a drain valve is also installed on the steam inlet pipe (DN150). The steam condensate drain valve of the heat exchanger is normally open, but this noise still occurs from time to time. and cause damage to the heat exchanger. At the very end of the steam inlet of the heat exchanger, the weld has cracked, resulting in steam leakage and water spraying out. Why does this phenomenon occur in working conditions with low stress and low temperature? What are some ways to solve it? I would appreciate your advice. :handshake
Unusual noises in the steam heating pipes of power plants may be caused by water hammer phenomenon. Water hammer usually occurs when steam and condensed water mix abnormally; the rapid cooling of the steam leads to sudden changes in pressure inside the pipes, thereby generating a knocking sound. The reasons for this phenomenon may include improper operation of the steam trap, poor drainage leading to water accumulation in the steam pipes, or the accumulation of non-condensable gases such as air inside the pipes. Solutions can be approached from the following aspects: checking and maintaining steam traps to ensure their proper functioning, removing water and air accumulated inside the pipes, adding exhaust facilities, and installing shock absorption measures in the piping system to reduce the impact of water hammer. At the same time, the heat exchanger needs to be inspected and maintained to prevent further damage caused by water hammer. .
2-3 kilograms of pressure, around 200°C?
It would be best for the poster to draw a flow diagram, indicating the pipes, steam parameters of the heat exchangers, and the locations of vibrations, to facilitate problem analysis. The steam used in heat exchangers is mostly saturated steam, and the temperature and pressure reducing devices for superheated steam pipelines are usually installed near the user end. “The working pressure is 2-3 kilograms, and the temperature is around 200 degrees. The steam enters the heat exchanger through connecting pipes to the cylinder; on the pipeline before it reaches the heat exchanger, the steam pressure gauge shows almost no pressure, with a temperature of around 95 degrees. There are likely issues with this description. Before the steam distributor, it is low-pressure superheated steam (the parameters seem to be incorrect); after passing through the steam distributor, it becomes 95°C waste steam with no pressure (the heater shouldn’t be used in this way?) Vibration in steam pipes is related to water presence inside the pipes ； Heater vibration is related to internal water accumulation; the steam condensate drain valve of the heat exchanger remains open. It is advisable to have an automatic condensate drainage system – otherwise, one has to keep the valve wide open (closing it too much prevents proper drainage, while opening it too wide results in steam waste).
1. Identify the section of the pipeline where the water hammer noise is occurring, and ensure that there is no water accumulation at the lowest point of that section (the drain valve should be installed at the lowest point of the pipeline)； 2. Check whether the selection and installation location of the heat exchanger are appropriate, whether the heat exchanger is clogged, whether the drainage of condensate water from the heat exchanger is unobstructed, and whether there is no back pressure ； 3. Is the selection of the pressure gauge appropriate (mainly regarding the range)? ；
Thank you for the reply: handshake
Thank you for the reply. The reason, as analyzed, is likely water hammer, but I haven’t figured out what caused it.
Thanks for the reply. 1. The steam is superheated steam from the power plant. When the heat exchanger was originally designed, it was planned for steam at temperatures above 200 degrees. However, after installation by the user, as the fluid passes through the pressure-reducing device, then into the steam distribution cylinder and further into the heat exchanger, the temperature indicated by the thermometer at the front end is around 95 degrees. This is the actual situation on site. 2. The impact sound was heard inside the semi-circular bulge at the steam inlet of the heat exchanger, not in the steam pipeline; our heat exchanger’s steam inlet features a semi-circular bulge. This phenomenon does not occur in any of the various soda water heat exchange conditions (saturated steam). This is the only case discovered so far. 3. The steam condensate outlet and the steam inlet both have a DN150 size; there is no trap, only one globe valve that remains open at all times. 4. The installation company installed multiple normally open steam traps on the steam pipes. I believe that the steam released after pressure reduction is unstable, which leads to condensation water forming during pipeline transport; incomplete drainage by the steam traps results in water hammer. But it’s indeed strange that this phenomenon occurs.