Abstract: A continuous synthesis system of urea, including: a reactor, a mixing buffer tank for accommodating a first raw material, a feeding pump for pumping the first raw material to the reactor, a pressure regulating valve connected to the reactor to transfer a second raw material and regulate a pressure of the second raw material, a first heat exchanger connected to the reactor to regulate a temperature inside the reactor to a first preset temperature, and a back pressure valve connected to an end of the reactor away from the feeding pump to maintain a pressure of the continuous synthesis system at a preset pressure. The second raw material is gaseous. The second raw material is fed to the reactor through the pressure regulating valve to react with the first raw material in the reactor to generate a target product.

Abstract: A continuous-flow synthesis method of 13C-urea, including: (S1) mixing sulphur and a methanol solution containing NH3 in a feed kettle to obtain a slurry; or mixing ammonia gas, sulphur and methanol in a feed kettle to obtain a slurry; (S2) feeding the slurry into a mixing unit; and feeding 13CO into the mixing unit to obtain a three-phase mixture; (S3) mixing the three-phase mixture in the mixing unit evenly; feeding the three-phase mixture into a continuous-flow reactor for reaction to obtain a reaction product; and (S4) feeding the reaction product into a gas-liquid separator for gas-liquid separation, and collecting a liquid phase as a crude product solution; and subjecting the liquid phase to purification to obtain the 13C-urea.