蒸汽管道水击简介

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So how do you remove the condensate from the lower leg without water hammer? First, check and see if the line has sub-cooled condensate. This is best done by using a temperature gun. If the bottom of the line is more than 40°F cooler than the steam, you have sub-cooled condensate.
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蒸汽管路水击简介
A closer look at the condensate lying in the line reveals the contents are layered by differences in temperature. However, when the hot condensate layer is disturbed and the steam contacts the sub-cooled condensate, the steam rapidly condenses.
Vacuum Steam Header Pressure
As discussed earlier, when steam This results in an immediate flow of contacts sub-cooled condensate, condensate toward the vacuum at a it rapidly condenses. very high rate (100+ mph).
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蒸汽管道内水击的处理：
• 开启过热器集箱和蒸汽管道上的疏水阀，进行疏水。 • 锅筒水位过高时，应适当排污，保持正常水位。 • 加强水处理工作，保证给水和锅水质量，避免汽水共腾。
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温馨提示：
To所
PPE是我们最后一道保护 防线。 工作之前确保良好的准备， 所有的烧伤和烫伤都是可 以避免的。
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Next, since the magnitude of condensation-induced water hammer is directly related to the difference in up-stream pressure and the vacuum created by the sub-cooled condensate, we need to reduce this differential pressure. In other words, isolating the line from the steam header and depressuring it to the atmosphere will reduce the diffierential pressure to almost zero.
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This forms a pocket of steam surrounded by cooler condensate.
The wave expands and forms a seal around the pipe.
Steam is isolated from the sub-cooled condensate by the hot condensate layer. This allows the steam to slowly condense into hot condensate which slowly cools into sub-cooled condensate.
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Steam can easily condense where there is no flow. In this example, steam is flowing in the top line (steam header) from left to right, but the lower leg is blocked; therefore there is no flow in the lower leg. Heat is continuously lost through piping, and without the flow of steam delivering heat, the steam in the lower leg cools and condenses.
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Now that the line is drained, steam can be introduced to warm the line.
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Once the line is has been heated for the designated time, the line can be placed back in service.
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After the impact, a rebounding wave is formed, pushing condensate back in the opposite direction.
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Since water does not compress, the slug of condensate in a 50 psi system can easily exceed 1000 psi at the point of impact (the valve you opened) or anywhere along the shockwave.
Also, with the steam isolated from the line, the vapor space left when draining the sucondensate will pull air from the atmosphere. The steam contacting sub-cooled condensate is the cause of the water hammer. With air taking the place of the steam, this driving force is eliminated.
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However, doing this will almost certainly result in water hammer. Possibly severe enough to cause the line or valve to fail, resulting in personnel injury or death.
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Next, open a bleeder at the highest point of the line to depressure line.
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蒸汽管道内水击的原因：
• 在送汽前未进行疏水和暖管。 • 送汽时主汽阀开启过快或过大。 • 锅炉负荷增加过急或发生满水、汽水共腾等事故，蒸汽 严重带水进入管道。
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Now that the line is about 0 psig, if a vacuum is formed by the contact of sub-cooled condensate and steam, the strength of any water hammer will be minimal.
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蒸汽管路水击简介
The following example shows what happens when this valve is opened to drain the condensate.
Steam to User
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This rush of steam flowing above the condensate, results in a wave of condensate to form.
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Since the wave of condensate has sealed the line, the rapidly condensing steam pulls a vacuum
Now if we take a close look at the hot condensate layer, you’ll notice it has been disturbed and no longer insulates the steam from the sub-cooled condensate.
蒸汽管路的水击简介
庄家文
蒸汽管路水击简介
• 水击的定义
• 造成水击的原因
• 水击现象的避免和处理
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蒸汽管路水击简介
水击
水击又称水锤，是由于蒸汽或水突然产生冲击力，使锅筒或管道发生 音响和震动的一种现象。例如，当输出的蒸汽与管道内的积水相遇时 ，部分热量被水迅速吸收，使少量蒸汽冷凝成水，体积突然缩小，造 成局部真空，因而引起周围介质高速冲击，发生巨大音响和震动。当 水击的管道被空气或蒸汽阻塞时，水不能畅通，也会发生音响和振动 。