VFAC drives can be used to "soft start" pumps if needed. This is more common in the smaller size pumps, often the drive is less $ than a soft start. As they get bigger, the drives get more expensive than the soft start.
Mikes right - flow curves should come from the vendor at the different...
I have seen gas injection on the suction side of a centrifugal pump before - would not recommend doing that again. I like Checman's idea of a venturi, but on the discharge of the pump. It can be a small venturi (in a sidestream - then remix back into the main flow) to keep from buying a big...
I've never found a good written reference on Fluidized beds. But I have worked with a company call Applied Chemical Design out of Florence Alabama that provided good input. They helped us retrofit a couple of driers that weren't working well and also have mobile bench driers that can be used...
Adding solids through an open hatch make solving the problem more difficult. A few potential options to consider.
1) Can the nitrogen purge rate be reduced and still do the job? Sounds like you may be flowing a high rate of N2.
2) Is there a non flammable liquid that the solid can be mixed...
I agree with the advice to talk to your supplier. Get an expert to review the system, all materials of construction, and cleaning/passivating procedures before any H2O2 goes in.
I just designed a system to handle 70% H2O2. The supplier was FMC. FMC provided a really good, extensive design...