Problems with methanol underground tank operation
Thread Content
This is a minor issue related to on-site operations, meant for discussion in our free time. Our underground channel is arranged as follows: 1. There is a 25mm nitrogen filling pipeline, equipped with a flow control orifice plate on it. 2. There is also a 50mm on-site high-point vent line, equipped with a stop valve. 3. No breather valve. Today I discussed with my colleagues the method of operating this underground tank. I believe it should be operated as follows: normally, the tank is emptied and its inlet is opened, while the nitrogen valve remains closed (since methanol is a volatile liquid, there is always a slight positive pressure inside the tank, preventing air from entering). The nitrogen valve is only opened when it is necessary to start the pump in the underground tank; this creates a nitrogen seal on the surface of the liquid, thereby preventing air from entering the tank. My colleague believes that the nitrogen valve and the vent valve should remain open at all times. Considering various factors such as safe operation and energy conservation, what do you think is the most reasonable way to proceed?
The nitrogen valve should be opened and the vent valve closed. Increasing the inlet pressure of the pump raises its head.
I would like to ask the person upstairs: Is there such a strong relationship between the pump’s head and the inlet pressure? ? The low-pressure nitrogen valve can be opened; the vent valve should remain closed! ! Hehe, there should be no problem
The nitrogen valve should remain open; even with a flow-limiting orifice plate, not much gas can escape； The vent valve should not be closed, otherwise the pressure in the underground tank will gradually become equal to the nitrogen pressure; underground tanks are generally designed to operate at atmospheric pressure ； In this way, there is no need to worry about air entering the system when starting or stopping the pump. Methanol is a volatile liquid, but it does not create a slightly positive pressure environment under normal conditions.