Magnet options for sensors for the pulp and paper industry

Abstract

The Lawrence Berkeley National Laboratory (LBNL) has been developing sensors for the pulp and paper industry that uses a magnetic field. The applications for magnetic sensors that have studied include I) sensors for the measurement of the water and ice content of wood chips entering the pulping mm, 2) sensors for measuring the water content and other constituents of the black liquor leaving the paper digester, and 3) sensors for measuring paper thickness and water content as the paper is being processed. These tasks can be done using nuclear magnetic resonance (NMR). The magnetic field used for doing the NMR can come from either permanent magnets or superconducting magnets. The choice of the magnet is dependent on a number of factors, which include the size of the sample and field strength needed to do the sensing task at hand. This paper describes some superconducting magnet options that can be used in the pulp and paper industry.

The use of a permanent magnet for water content measurements of wood chips

“…Other experiments not reported in this report indicate that water content can also be measured in brownstock and black liquor from the digester of a paper mill [2].…”

“…A good field region that is 150 mm in diameter will probably need a superconducting magnet to generate the magnetic field [2]. …”