Material density (kg/m3) and required rate (te/hr) would help. ■

You're going to be banging 250 chips per minute along the pipe. To avoid bridging at the feed point your pipe will be disproportionatey large compared to the number of particles conveyed. 100mm pipe is just not enough. That is unless you can align/lay the particles flat..like a pack of cards... before you drop them into the airstream. Then you could blow the stuff along a line of RHS, why are they always cylindrical? and drastically reduce your airflow demand.

Any normal dilute phase pneumatic conveying calculation will give you a start with the airflow requirement. After that you play with the vee belts and throttle valve to your heart's content until you are satisfied with the throughput. Some might say you need an inert conveying gas...and probably say a lot more besides...but its a thought process.

The feed hopper is your problem item; which is often the case. ■