98 Sulfuric acid unloading problem
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Sulfuric acid is unloaded from the unit by connecting a dip pipe to the bottom of a tank truck, and it is then pumped into the vertical sulfuric acid storage tank using a shielded pump. The head and flow rate of this shielded pump are designed for 98% concentration sulfuric acid, both being 20. The suction inlet of the pump is equipped with a ball valve, while the outlet valve is a globe valve. When unloading sulfuric acid, vacuum is continuously created in the storage tank; the shielded pump is started, but if the outlet globe valve is opened only slightly, the pressure at the pump outlet drops from 4 kilograms to 0.5 kilograms. Is this problem caused by the pump itself, or is it due to the vacuum created in the storage tank that results in such a significant drop in pump outlet pressure?
Unloading is very slow; it seems that the pump isn’t working effectively. If the outlet shut-off valve of the pump is opened, the pressure at the pump’s outlet fluctuates around 0.01 MPa
1. What is the head difference from the pump outlet to the tank inlet? If this head difference is not high, it may be similar to a situation where the pump discharges directly into the air; in such a case, the pump flow rate will be higher than the rated value, but the head will be very low； 2. It’s hard to explain whether to evacuate the vacuum first or to open the shut-off valve first; it’s like blowing air on one end while sucking in air on the other – when the amount of air being sucked in is large, there is no sensation of resistance from the end where air is being blown out
This post was last edited by *aowu0515 on 2019-11-16 08:35. Measure the current of the pump; the outlet pressure of the pump is related to the resistance downstream. When the tank is evacuated, the outlet pressure of the pump should not be too high. It is recommended to adjust the pump outlet valve according to the pump’s operating current in order to keep it at the pump’s rated current.
Is the breather valve of the tank truck open?
Is your pressure before or after the pump outlet valve?
The pressure at the pump outlet is created by the resistance in the pipes downstream; without any resistance, there is naturally no pressure (system pressure). It’s normal for the pressure to drop when the outlet valve is opened. It’s similar to a pump with a head of 100 meters: if the outlet is open, the liquid won’t be ejected to a height of 100 meters……
Check if there’s a problem with the filter, whether the pump is getting hot, etc. What’s the liquid level in your tank? Check each of these possibilities one by one. The sliding graphite bearings of shielded pump unloading systems tend to break easily