What are the disadvantages of fully closing a double-acting spool valve?
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It must affect the smooth operation of the smoke extractor, right?
Take a look at this post: What are the hazards of having no clearance in a double-acting spool valve? What will happen if there is no pressure-reducing orifice plate behind the double-acting slide valve? https://bbs.hcbbs.com/thread-1016008-1-1.html (Source: Haichuan Chemical Industry Forum)
Whether there is a margin or not, once it is fully closed, there is no more room for adjustment; how is the regeneration pressure controlled?
Under normal operation, if the double-acting slide valve is closed completely while the main air flow rate remains unchanged, this will cause the pressure in the regenerator to rise rapidly. The main fan will experience pressure buildup and surge, which in turn will trigger the main air protection system to activate.
With it fully closed and in two-position operation, the slide valve is prone to getting stuck. Moreover, this is the last line of defense for controlling the pressure in the regenerator; if it gets stuck when fully closed, do you want it to explode?
It’s okay to turn it off completely, right? Set the regenerator pressure so that it opens automatically when the pressure rises; this won’t affect the regenerator pressure
I am not in favor of fully closing the double-acting slide valve; it’s too dangerous. If the pressure becomes excessively high, the catalyst in the regenerator could flow back into the settler, posing a risk of explosion.
The designs of the main fan and the exhaust fan are complementary to each other. During normal operation, the double-acting slide valve is set to automatic mode; a complete closure for a short period of time or intermittently has little impact. The exhaust fan generates more power, so safety must be the top priority during long-term operation, with appropriate control parameters in place. In the event of an accident, the double-acting slide valve should be switched to manual mode immediately so that the valve position can be increased rapidly to reduce pressure and ensure safety. If the double-acting slide valve operates slowly in automatic mode, it can lead to many negative consequences
During normal operation, the double-acting slide valve operates in automatic mode; brief periods of complete closure or intermittent full closure have little impact. The smoke extractor should operate at maximum efficiency, and safety must be prioritized during long-term operation. It is necessary to maintain the valve within appropriate control parameters. When the double-acting slide valve is in automatic mode, its operation is slow, and an emergency situation can lead to various negative consequences; in such cases, it is essential to switch to manual control immediately, increase the valve opening degree, and make adjustments based on the pressures in the two relevant systems to ensure the safety of those systems as well as the entire unit
Why is everything shut down during normal production?
Firstly, the function of the double-acting slide valve is to control the pressure in the regenerator and prevent overpressure there; closing it completely poses a risk of pressure buildup. Additionally, if the system is used suddenly while it is fully closed, a sudden rise in temperature can cause significant damage to the equipment