Energy Risk Engineering Insights

Let’s discuss steam hammer in a power boiler cold reheat line due to leaking attemperator spray valves and accumulation of water on the extraction check valve.

A steam hammer in a power boiler’s cold reheat line can occur due to various factors, including leaking attemperator spray valves and the accumulation of water on the extraction check valve. Let’s break down these components and understand how they contribute to the steam hammer phenomenon.

1. Attemperator Spray Valves: Attemperators are devices used in power boilers to regulate and control steam temperature. They inject a controlled amount of water into the superheated steam to reduce its temperature. If the spray valves that control the water flow are leaking, an excessive amount of water may enter the steam flow. This can cause rapid condensation of steam and lead to water droplets being carried with the steam flow.
2. Accumulation of Water on Extraction Check Valve: The extraction check valve is a critical component that controls the flow of steam extracted from the turbine for various processes, such as heating or feedwater heating. If there is a leakage or accumulation of water near the extraction check valve, it can disrupt the proper functioning of the valve. This may result in an uneven flow of steam, leading to pressure fluctuations and subsequent steam hammering.

Steam hammer refers to the occurrence of sudden pressure transients or shockwaves in a steam system. When water droplets or liquid slugs are carried with high-velocity steam, they can rapidly condense and cause pressure waves. These pressure waves can lead to severe stress on the piping system, resulting in loud banging noises and potential damage to equipment.

To address steam hammer in the power boiler’s cold reheat line, the following measures can be taken:

1. Maintain and inspect attemperator spray valves regularly to ensure they are functioning correctly. Leaking valves should be repaired or replaced promptly to prevent excessive water from entering the steam flow.
2. Check and rectify any issues related to the extraction check valve. Ensure that there is no accumulation of water or leakage around the valve, which can disrupt the steam flow.
3. Implement proper steam system design and layout, considering factors such as pipe sizing, drainage, and control mechanisms. This helps to minimize the chances of water carryover and subsequent steam hammering.
4. Install additional safeguards, such as steam traps and separators, to remove any water or condensate from the steam flow. These devices help prevent water droplets from reaching critical components and causing steam hammer.

It is essential to consult with qualified engineers and professionals who specialize in power boiler systems to assess the specific situation and recommend appropriate solutions to mitigate steam hammering issues effectively.