Microwave heating device and heating method

A microwave heating device comprising:

• a microwave generator for generating microwaves;
• a waveguide for propagating the microwaves generated by said microwave generator;
• a matching element for adjusting the impedance inside said waveguide;
• and
• a flow pipe disposed in said waveguide to pass a substance to be heated,
• wherein said flow pipe forms a double pipe heat exchanger capable of circulating a heat transfer medium for heat exchange around said flow pipe and said double pipe heat exchanger has an inlet port to which said heat transfer medium flows in and an outlet port from which said heat transfer medium flows out, and
• wherein said microwave heating device further comprises:
• a constant temperature bath for adjusting said heat transfer medium to a constant temperature;
• means for supplying said heat transfer medium to said inlet port;
• means for discharging said heat transfer medium from said outlet port and circulating it to said constant temperature bath;
• means for causing the heated substance to flow to said flow pipe;
• and
• means for causing said heated substance to flow out of said flow pipe.