Why does the temperature of biomass particle rise so slowly?

Hello, everyone!
I was running a case of biomass combustion and had a problem with the temperature of the biomass particle rising very slowly, I tried to change parameters like thermal conductivity and heat of reaction but to no avail!
Can someone check my case for me and tell me what parameters can be adjusted?I’d appreciate it. Attached is my case.
b0802.mfx (30.2 KB)
usr_rates.f (4.9 KB)
usr_rates_des.f (5.9 KB)

What is the rate of change of biomass temperature you are getting and what is the value you are expecting?

The rate of change I get for biomass is a 60K rise in temperature in 10 seconds, but what I want is a rise of about 200-300K.