Belonging to the field of
coalbed methane exploitation, the invention discloses a
measurement device and method for
free expansion volume of
coal rock adsorption. The device includes a
sample chamber (1), a heating and
thermal insulation device (2), a confining pressure tracking pump (3), a
back pressure buffer container (4), a liquid holding container (5), a balance (6) and a
back pressure valve (7). The
sample chamber (1) is fixed in the heating and
thermal insulation device (2), the confining pressure tracking pump (3) is connected to an annular space (1-3), the
back pressure buffer container (4) is respectively connected to the confining pressure tracking pump (3) and the back pressure valve (7), the other end of the back pressure valve (7) is connected to the annular space (1-3), and the liquid holding container (5) and the balance (6) are placed at another
branch outlet. The method measures the
mass of liquid discharged by
coal sample expansion deformation and then performs conversion to obtain the expansion quantity and expansion coefficient of
coal rock. With the device and the method provided by the invention, the
free expansion volume and expansion coefficient of the coal
rock sample can be obtained, the measurement accuracy is high, and no complicated conversion is needed.