Issues regarding the dilution steam generator in ethylene plants
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What if the on-site level gauge fails, and the level gauge in the control room shows that the tank is full? How to determine the actual liquid level in the tank?
Critical liquid level indicators – there should be two of them on site, right? If there is only one, it can be determined using the pump inlet pressure or the bottom of the tower pressure gauge!
A steam drum usually has two level indicators; there is also a glass level gauge on site, making it easy to see the water level clearly and allowing for accurate determination. If the tank is full, switch to manual control first and turn on the fixed discharge to lower the liquid level. It should be noted that boilers exhibit a phenomenon known as \"false level.\" This occurs when the pressure in the steam system drops suddenly and significantly; the bubbles in the liquid phase expand, causing the liquid level to rise artificially, which leads to boiling. In cases where the instrumentation is used for automatic control, the presence of three control signals helps to prevent the boiler from running out of liquid. However, when manual control is used, it is important to avoid a sharp reduction in the water supply rate.
Also, maintain the valve position indicated by the control valve switch during normal operation at its current value. This can be maintained for a while first.
Experience can indeed help us sometimes, but it’s still important to first find a way to restore the on-site indications!
Can it be determined through tank drain monitoring? Inject water, then open the drain valve; once a liquid phase appears in the drain, it indicates that the liquid level has reached that level
It will take too long to do this; I’m afraid we won’t have enough time. Boilers have what’s known as the water-calling method; if the parameters of the drum are low and it is located on the ground, this method can be tried. However, in the case of boilers with high parameters, the drum is usually at a very high position, so there’s no time to use the water-calling method – the boiler should be shut down immediately.
Of course, during maintenance, one can proceed in this way by relying on experience.
It can be done this way, as long as it is a method that helps in determining the water level.