Which type is better for naphtha/aromatic unloading truck pumps?

When the volume of material unloaded from tank cars per year is not high, I used to employ centrifugal pumps for unloading aromatic compounds; the standard flow rate for such pumps is 30 cubic meters (the flow rate is determined based on the size of the tank car, the outlet of the material from the tank car, and the requirements of the production process). For the unloading of organic materials, I have not used variable frequency control; I only resorted to it when there were significant changes in flow rate. For the rest, check the answers below

Thank you! But I have a question: when unloading with a centrifugal pump, gas-liquid mixing can occur later on; isn’t that not good for the centrifugal pump?

For bottom discharge, use air locking and stop the pump. There is an impact, but I haven’t heard from the owners that it affects production. 1. Some companies use pumps for pumping directly, and the tank trucks are weighed to determine the payment amount; there should be some amount of liquid remaining in the tank trucks, as over time vapor is generated, which causes gas entrapment and leads to the pump stopping. 2. Some companies prefer to let the liquid flow from the tank truck into the sump by gravity, and then use submersible pumps to transfer it to the receiving tank. Unloading time is short, and the tank truck does not hold any material. However, special attention must be paid to safety measures in underground tanks, as they are prone to accumulating flammable gases, and also to ensuring the tanks’ resistance to floating and leakage. (It is also possible to arrange a low-level tank for gravity unloading based on the actual terrain.) 3. In some cases, a buffer tank is installed between the tank truck and the pump (about 1 cubic meter in size, above ground level); attention should be paid to the height difference between the tank truck, the buffer tank, and the pump. This way, there is no need for an underground tank, and the tank truck will not hold any material. Production operations are also convenient.

Take a look at the working principle of the positive displacement pump, as well as the applicable analysis for related situations. There are differences in prices, as well as differences in operating flow rates, etc. You can also consult the technical staff from the pump manufacturer. In some cases, positive displacement pumps have also been used.