# US 2013/0154644 A1 · Low-field nmr device for measuring the water content of solids and slurries > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154644 A1 - Document ID: US20130154644A1 - Status: Published application - Kind: A1 - Application number: 13/818,712 - Filed: 2011-08-30 - Published: 2013-06-20 - Earliest claimed: 2010-08-31 - Assignees: Metso Automation Oy - Inventors: Sami Virtanen; Veli-Pekka Viitanen - Web page: https://patentgrep.com/patent/US20130154644A1 ## CPC - G01R 33/28: Details of apparatus provided for in groups G01R33/44 - G01R33/64 - G01N 24/08: by using nuclear magnetic resonance (G01N24/12 takes precedence) - G01N 24/081: {Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity} - G01N 24/082: {Measurement of solid, liquid or gas content} - G01N 24/085: {Analysis of materials for the purpose of controlling industrial production systems} - G01R 33/381: using electromagnets - G01R 33/44: using nuclear magnetic resonance [NMR] (G01R33/24, G01R33/62 take precedence) - G01R 33/445: {MR involving a non-standard magnetic field B0, e.g. of low magnitude as in the earth's magnetic field or in nanoTesla spectroscopy, comprising a polarizing magnetic field for pre-polarisation, B0 with a temporal variation of its magnitude or direction such as field cycling of B0 or rotation of the direction of B0, or spatially inhomogeneous B0 like in fringe-field MR or in stray-field imaging} - Y02A 90/30: Assessment of water resources - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE ## Abstract A Nuclear Magnetic Resonance (NMR) apparatus and method for measuring the water content of samples has a device to produce a main magnetic field; a sample receiving space within a main magnetic field; a device to excite a measurable RF magnetization to a sample placed into the sample receiving space at an operating frequency defined by the main magnetic field; a device to measure the RF signal produced by the excited sample; and a device to determine the water content in the sample based on the RF signal. The sample receiving space is capable of accommodating a sample having a volume of at least 0.5 dm3, and the device to produce a main magnetic field has a resistive electromagnet which is adapted to produce a main magnetic field corresponding to an operating frequency of 400-2000 kHz. ## Claims ### Claim 1 A Nuclear Magnetic Resonance (NMR) apparatus for measuring the water content of samples, such as solids and slurries, comprising: means for producing a main magnetic field, a sample receiving space within said main magnetic field, means for exciting a measurable RF magnetization to a sample placed into said sample receiving space at an operating frequency defined by said main magnetic field, means for measuring the RF signal produced by the excited sample, and means for determining relative water content in the sample based on the RF signal, wherein the means for measuring the RF signal being configured to measure the RF signal of the excited sample after a predetermined dead time after the excitation u se the sample receiving space is capable of accommodating a sample having a volume of at least 0.5 dm3, and the means for producing a main magnetic field comprise a resistive electromagnet which is adapted to produce a main magnetic field corresponding to an operating frequency of 400-2000 kHz. ### Claim 2 (depends on 1) The apparatus according to claim 1, wherein the electromagnet is passively cooled. ### Claim 3 (depends on 1) The apparatus according to claim 1, wherein by further comprising means for actively cooling the electromagnet, preferably by forced air circulation. ### Claim 4 (depends on 1) The apparatus according to claim 1, wherein the operating frequency of the device is 400-950 kHz. ### Claim 5 (depends on 1) The apparatus according to claim 1, wherein the operating frequency of the device is 950-2000 kHz. ### Claim 6 (depends on 1) The apparatus according to claim 1, wherein by further comprising means for measuring the mass of the sample while the sample is in the sample receiving space, said means for determining the water content of the sample being adapted to utilize the mass of the sample in determining the relative water content of the sample. ### Claim 7 (depends on 1) The apparatus according to claim 1, wherein said means for measuring the RF signal are adapted to start measuring of the RF signal after a predetermined dead time after the excitation, and said means for determining the water content of the sample are adapted to extrapolate the RF signal value to the time at the excitation pulse based on the measured RF signal and adapted to utilize said extrapolated signal value in determining the water content of the sample. ### Claim 8 (depends on 1) The apparatus according to claim 1, wherein the volume of the sample receiving space is 0.5-5 dm3. ### Claim 9 An NMR-based method for measuring the water content of a sample, comprising: producing a main magnetic field, subjecting the sample to said main magnetic field in order to produce a net magnetization to the sample, exciting a measurable RF magnetization to a sample at an operating frequency defined by said main magnetic field, measuring the RF signal produced by the excited sample, and determining the water content in the sample based on the RF wherein by measuring the RF signal of the excited sample after a predetermined dead time after the excitation pulse, using a sample having a volume of at least 0.5 dm3, and producing said main magnetic field using a resistive electromagnet adapted to produce a main magnetic field corresponding to an operating frequency of 400-2000 kHz. ### Claim 10 (depends on 1) The method according to claim 1, wherein the sample is a biomass sample. ### Claim 11 (depends on 1) The method according to claim 1, wherein the sample is in a solid or slurry form. ### Claim 12 (depends on 9) The method apparatus according to claim 9, wherein by using a passively cooled electromagnet and an operating frequency of 400-950 kHz. ### Claim 13 (depends on 9) The method according to claim 9, wherein by using an actively cooled electromagnet and an operating frequency of 950-2000 kHz. ### Claim 14 (depends on 9) The method according to claim 9, wherein by measuring the mass of the sample while the sample is in the sample receiving space and determining the water content of the sample based on the mass of the sample. ### Claim 15 (depends on 9) The method according to claim 9, wherein by measuring of the RF signal only after a predetermined dead time after said excitation, estimating the RF signal value at the time of the excitation pulse based on the measured RF signal, and utilizing said estimated RF signal value in determining the water content of the sample.