To provide a system of detecting blockage of fluid transportation piping which inhibits occurrence of solid clogging such as complete blockage in piping for transporting a solid-liquid mixed fluid from a storage tank for storing the fluid while maintaining the liquid surface of the fluid at a predetermined level to a separator for the solid-liquid separation of the fluid and can operate the apparatus in a stabilized transporting state for a long period.

The system of detecting blockage of fluid transportation piping has a liquid surface level detector for detecting the liquid level of the fluid in the storage tank, a controlling valve which is provided midway along the piping and adjusts the degree of opening of the valve based on the signal from the liquid surface level detector, and a blockage detector for detecting blockage which distinguishes whether or not blockage is progressing within the piping by comparing the input values consisting of the degree of opening of the controlling valve and the current value of a motor showing the operating state of the separator with preset conditions.