Practical Exercise on Purification Technology Version [051]
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Short answer: Why is it necessary to warm up the main steam pipeline before putting it into use? Answer: Before being put into use, the main steam pipeline is at a very low temperature. It is long in length and has a complex shape, with significant differences in thickness between the pipes and other accessories. If a large amount of high-temperature, high-pressure steam is suddenly introduced into the pipeline, this will generate considerable thermal stress in the pipes and accessories. If expansion is hindered, the pipes may be damaged. When steam enters a cold pipeline, condensate water is formed; if this condensate water is not removed promptly, it can cause severe water hammer effects, leading to the failure or damage of the pipes. Coalification Region Purification Technology Edition – 2017 Coal Chemical Industry “My Technical Upgrades” Contest (Large prizes available) http://bbs.hcbbs.com/thread-1786290-1-1.html Registration for Chemical Engineers – Experience Sharing Event “Learning from Others’ Experiences” http://bbs.hcbbs.com/thread-1808158-1-1.html
It prevents a large amount of high-temperature, high-pressure steam from suddenly entering the pipes, which could cause stress-induced damage. Additionally, when steam enters cold pipes, condensate water is generated; if this water is not removed promptly, it can lead to water hammer
Main steam pipes are characterized by their long length and complex shape. There are significant variations in the thickness of the pipe flanges, valves, and other components, which means it takes time to heat these pipes. Therefore, before putting them into use, a small amount of steam is used to preheat them, allowing the pipe temperature to rise gradually. This prevents excessive thermal stress and water hammer damage to the metal pipes and other accessories due to differences in expansion.
Before being put into use, the main steam pipes are at very low temperatures. Moreover, they are long and have complex shapes, with significant differences in thickness between the pipes and other fittings. If a large amount of high-temperature, high-pressure steam is suddenly introduced into these pipes, it will generate considerable thermal stress in the pipes and fittings. If expansion is hindered, the pipes can be damaged. When steam enters cold pipes, condensate water is formed; if this condensate water is not removed promptly, it can cause severe water hammer effects, leading to the pipes collapsing or being damaged.
Before operation, since the main steam pipes as well as various valves and flanges were at a cold state, the pipes were first warmed up at a pressure of 2 kg/cm3, allowing them to heat up gradually and expand evenly. This prevented excessive thermal stress and water shock, thus avoiding pipe deformation, cracks, as well as leaks in the valves and flanges.
Before being put into use, the main steam pipeline is at a very low temperature. It is long in length and has a complex shape, with significant differences in thickness between the pipes and other accessories. If a large amount of high-temperature, high-pressure steam is suddenly introduced into the pipeline, it will generate considerable thermal stress in the pipes and accessories. If expansion is hindered, the pipeline may be damaged
To reduce thermal stress in pipelines, prevent water hammer, and protect equipment. When warming up the pipeline, it is essential to strictly control the rate of temperature rise in the pipeline. Especially at the initial stage of warming, when the wall temperature is low, the steam inlet valve (warming valve) should be opened only slightly to slowly increase the pressure in the pipeline. The pressure increase rate can be raised only once the wall temperature exceeds the saturation temperature of the steam inside the pipeline ； In warm pipes, proper drainage should be ensured to prevent the accumulation of water.
Since the pipeline remains unused for long periods at room temperature, condensation water is generated when steam enters it. When steam and water coexist inside the pipeline and flow together, water hammer occurs. The energy of such water hammer is extremely high; sometimes it can crack the pipelines and damage the pipe supports
Answer: Before being put into use, the main steam pipeline is at a very low temperature. It is long in length and has a complex shape, with significant differences in thickness between the pipes and other fittings. If a large amount of high-temperature, high-pressure steam is suddenly introduced into the pipeline, it will generate considerable thermal stress in the pipes and fittings. If expansion is hindered, the pipes can be damaged. When steam enters a cold pipeline, condensate water is formed; if this condensate water is not removed promptly, it can cause severe water hammer effects, leading to the failure or damage of the pipes.
Steam pipelines must be thoroughly warmed up before use. When used for the first time or after being out of use for some time, failure to heat the pipeline can lead to its damage due to uneven thermal expansion. If the steam condensate is not discharged in time, water hammer can occur, causing damage to pipelines, pipe supports, and other components. The medium-pressure steam pipelines should be warmed up for at least 2 hours, while the high-pressure steam pipelines should be warmed up for at least 5 hours. Confirm that no water is discharged from each drain valve.
Main steam pipes are characterized by their long length and complex shape. There are significant variations in the thickness of the pipe flanges, valves, and other components, which means it takes time to heat these pipes. Therefore, before putting them into use, a small amount of steam is used to preheat them, allowing the pipe temperature to rise gradually. This prevents excessive thermal stress and water hammer damage to the metal pipes and other accessories due to differences in expansion. Therefore, the pipes need to be warmed up before the boiler is connected to the steam system.