In-situ, real-time and continuous measurement device and method for volume change of chemical reaction with participation of gas

The invention belongs to the technical field of detection instruments, and particularly discloses an in-situ, real-time and continuous measurement device and method for the volume change of a chemical reaction in which gas participates, the device comprises at least two gas cylinders, a valve positioner, a gas pipeline and a true density instrument; measurement gas is arranged in one gas cylinder, reaction gas is arranged in the other gas cylinders, the true density instrument is communicated with the gas cylinders through gas pipelines, the valve positioner is arranged on the gas pipelines, and the true density instrument comprises a sample bin, an additional bin, a pressure sensor, a first valve, a second valve and a third valve. The input end of the sample bin is communicated with the gas pipeline; the additional bin is communicated with the sample bin; the first valve is installed at the input end of the sample bin, the second valve is arranged between the sample bin and the additional bin, and the pressu