Magnetostrictive Sensor for Blockage Detection in Pipes Subjected to High Temperatures

Abstract

The use of solar thermal power plants is considered a cost-effective alternative to produce renewable energy. Unlike other energy installations, in this type of plants the transfer and storage of energy has been solved by using molten salts. These salts run between two tanks through the steam generation system that feeds the turbine. Although the use of salts as a heat transfer fluid is considered an adequate solution, they are not without problems. One of them is the formation of blockages in the pipes due to a partial solidification of the salt, which leads to the shutdown of the installation, with the consequent economic losses. Fast location of these blockages in a minimally intrusive way is the objective pursued in this work. The method to achieve this is based on the use of a new magnetostrictive sensor that simplifies previous designs.

Finite Element and Experimental Analysis of an Axisymmetric Electromechanical Converter with a Magnetostrictive Rod

“…Magnetomechanical Equations (7), (8) are solved using the FE method, where the same mesh of elements is used for both magnetic and elastic computations. Therefore, the deformations determined on the mechanical grid accompanied by a change of dimensions are automatically transferred to a model describing the magnetic field.…”

“…The Joule effect makes the GMM usable in actuation, while the Villari effect is useful for sensing. The GMM are widely employed nowadays as the main components of actuators [4][5][6], sensors [1,7,8], energy harvesters [9,10] or some other devices [1,3,11,12]. The GMM can also be used to build unconventional motors, so-called vibromotors [13,14].…”

Estimation of Blockage Position, Geometry, and Solidity in Molten Salt Pipelines

“…Figure 1 shows the arrangement of the sensor on the pipe. The permendur strips were placed at a 45-degree angle, so that the deformation generated would cause a torsional wave to travel along the entire surface of the pipe [ 19 , 20 ].…”

“…Among the acoustic waves used to analyze the condition of the pipeline, guided waves have been widely used in the past years [ 11 , 12 ]. This technique allows for the inspection of pipelines over many tens of meters up to 120 m [ 16 , 17 ], and has therefore been proposed as capable of detecting blockages in the pipeline [ 18 , 19 ]. However, the guided-wave technique is not without its difficulties.…”

“…Additionally, the contact between the permendur strip and the pipe does not require high pressure and metal flanges are typically used for this purpose. In [ 19 ], the construction details of the magnetic head used for the magnetic polarization of the permendur strips can be found. This magnetic head, which produces torsional guided waves, will be the one used in the tests shown in Section 3.3 .…”