The feed preheating section 1 includes a feed tank 5. The material is conveyed between the feed tank 5 and the microwave heating section 2 through a screw pump 8. Meanwhile, in order to accurately control the flow rate of flow liquids entering the microwave heating section 2, the flow meter 10 may be disposed in front of the microwave heating section 2. The feed tank 5 is structured as a jacket. That is, the feed tank 5 is placed in a heat preservation jacket 6, and the heat preservation jacket 6 is filled with hot water with a predetermined temperature for heating the flow liquids in the feed tank 5 to the preheating temperature. The flow liquids are uniformly stirred to make various parts of the flow liquids in the feed tank 5 have the same initial temperature while improving heating speed and uniformity.

The microwave heating section 2 includes a microwave generation system, a waveguide system, tuners, and a microwave absorption cavity.