US-12625058-B2 - Method and apparatus for controlling cellulose processing

US12625058B2US 12625058 B2US12625058 B2US 12625058B2US-12625058-B2

Abstract

A solution for controlling cellulose processing comprises performing ( 200 ) optically first measurements of the cellulose during the processing, performing ( 202 ) second measurements of the cellulose by directing ( 204 ) optical radiation to the cellulose, the radiation comprising at least one beam that is polarized and at least one separate beam is non-polarized, measuring ( 206 ) attenuations and parameters of polarization of the radiation interacted with the cellulose and determining size of particles in the cellulose based on at least one comparison of the parameters of polarization and the attenuations. The processing is controlled ( 208 ) based on the first measurements until a given threshold of the first measurements has been reached and thereafter controlling the processing based on the second measurements.

Inventors

Juha-Pekka Huhtanen
Ismo Joensuu
Juha Ojanen

Assignees

VALMET AUTOMATION OY

Dates

Publication Date: 20260512
Application Date: 20221222
Priority Date: 20211223

Claims (12)

1 . A method for controlling cellulose processing, characterized by performing first measurements of the cellulose during the processing, including: measuring drainability of the cellulose during the processing and monitoring a variation of drainage measurements, or measuring optically a size of particles in the cellulose during the processing; performing second measurements of the cellulose, including: first, directing optical radiation to the cellulose, the radiation comprising at least one beam that is polarized and at least one separate beam is non-polarized; second, measuring attenuations and parameters of polarization of the radiation interacted with the cellulose; and determining the size of particles in the cellulose based on at least one comparison of the parameters of polarization and the attenuations; and controlling the processing based on the first measurements until a given threshold of the first measurements, including the variation of drainage measurements or a predetermined size of the particles, has been reached and thereafter controlling the processing based on the second measurements.
2 . The method of claim 1 , wherein the cellulose is processed mechanically by refining the cellulose in a refiner between a set of refiner segments and the processing is controlled by adjusting a gap between the refiner segments and/or a time of process and/or revolutions per minute of the refiner segments.
3 . The method of claim 1 , wherein the cellulose is processed chemically, and the processing is controlled by adjusting an amount and type of chemicals and/or enzymes used in the process and/or a temperature and/or time used in the processing.
4 . The method of claim 1 , wherein the cellulose is processed with micro fluidizer and the processing is controlled by adjusting a pressure of the micro fluidizer.
5 . The method of claim 1 , wherein the cellulose is processed with homogenizer and the processing is controlled by adjusting a pressure of a fluid.
6 . The method of claim 1 , wherein the cellulose is processed with a disperser, and the processing is controlled by adjusting a gap between a disperser segments and/or a time of process or revolutions per minute of a segments.
7 . The method of claim 1 , the second measurements comprising: taking a sample of cellulose being processed; directing wave motion to the sample, a flow of the sample causing particles in the sample to be sorted on the basis of their sizes; directing optical radiation to the sample, the radiation comprising at least one beam that is polarized or a plurality of beams at least one of which is polarized and at least one separate beam is non-polarized; measuring attenuations of an electromagnetic radiation interacted with a flowing suspension; measuring parameters of polarization of the electromagnetic radiation interacted with the suspension; the measurements of attenuations and the parameters of polarization being synchronized; forming the at least one comparison of the parameters of polarization and the attenuations, each of the parameters and each of the attenuations of a comparison corresponding to each other on the basis of synchronization, the comparison depending on physical properties of the particles of the flowing suspension.
8 . The method of claim 1 , the first measurements comprising: measuring drainability of the cellulose during the processing and monitoring the variation of drainage measurements and the given threshold is reached when variation of the drainage is below a given threshold.
9 . The method of claim 1 , the first measurements comprising: measuring optically the size of particles in the cellulose during the processing and the given threshold is reached when the size of particles corresponds to a resolution of an optical measurement.
10 . The method of claim 1 , further comprising: performing first measurements until a given threshold of an optical measurements has been reached; thereafter performing second measurements.
11 . The method of claim 1 , wherein the given threshold is reached when variation of the drainage is below a predetermined threshold.
12 . The method of claim 1 , wherein the given threshold is reached when the size of particles corresponds to the resolution of the optical measurement.

Description

FIELD The invention relates to cellulose processing and especially controlling cellulose processing. BACKGROUND Microfibrillar cellulose refers to cellulose microfibrils or microfibril bundles separated from lignocellulose-containing fibre raw material, such as wood material. Microfibrillar cellulose is characterized by a large specific surface area and a strong ability to form hydrogens bonds. In water dispersion, micro-fibrillar cellulose appears as colourless, gel-like material. Microfibrillar cellulose may be utilized for example as an additive in manufacturing of new biobased products. Typically, the producing of microfibrillar cellulose by refining involves a high-degree grinding, i.e. a high-degree refining, of the lignocellulose-containing fibre material. The grinding or refining generally refers to comminuting material mechanically by work applied to material particles, which work may be grinding, refining, crushing or shearing, or any combination of these, or another corresponding action to reduce the particle size. The refining is performed at a low consistency of a mixture of the fibre material and water, called also for example fibre suspension, fibre pulp or pulp. In addition to this mechanical treatment of the lignocellulose-containing fibre material, the producing of microfibrillar cellulose may also comprise chemical or enzymatic processing of the lignocellulose-containing fibre material. A problem relating to the producing of microfibrillar cellulose by re-fining is an excessive amount of energy used in the refining. Energy taken by the refining is typically expressed in terms of energy per processed raw material quantity, typical unit being kWh/T, i.e. kWh/ton, or a unit proportional to that. As said above, microfibrillar cellulose is gel-like material, thereby having a high apparent viscosity because of which frictional forces affecting in blade elements of a refiner are very high and which, in turn, causes a high energy consumption in the producing of the nanofibrillar cellulose. The high energy consumption increases production costs of the microfibrillar cellulose and thereby for example limits applications of the microfibrillar cellulose that are economically feasible. Thus, there is a need for improvement. BRIEF DESCRIPTION The present invention seeks to provide an improvement in controlling cellulose processing. According to an aspect of the present invention, there is provided a method of claim 1. According to an aspect of the present invention, there is provided an apparatus of claim 11. In an embodiment, the cellulose is processed mechanically by refining the cellulose in a refiner between a set of refiner segments and the processing is controlled by adjusting the gap between the refiner segments and/or the time of process and/or revolutions per minute of the refiner segments. In an embodiment, the cellulose is processed chemically, and the processing is controlled by adjusting the amount and type of chemicals and/or enzymes used in the process and/or the temperature and/or time used in the processing. In an embodiment, the cellulose is processed with micro fluidizer and the processing is controlled by adjusting the pressure of the micro fluidizer. In an embodiment, the cellulose is processed with homogenizer and the processing is controlled by adjusting the pressure of the fluid. In an embodiment, the cellulose is processed with a disperser, and the processing is controlled by adjusting the gap between the disperser segments and/or the time of process or revolutions per minute of the segments. LIST OF DRAWINGS Example embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which FIG. 1 shows schematically a cellulose processing arrangement for producing microfibrillar cellulose; FIGS. 2, 3A and 3B are flowcharts illustrating embodiments; FIG. 4A illustrates an example of principle of fractionation; FIG. 4B illustrates an example of attenuation of intensity caused by scattering; FIG. 5 illustrates an embodiment of utilizing the second measurements; FIGS. 6A, 6B, 6C and 6D illustrate examples of the performing measurements; FIG. 7A illustrates an example of an apparatus for measuring; FIG. 7B illustrates an example of a data processing unit; FIG. 7C illustrates an example of a general measurement configuration of the measurement apparatus; and FIG. 7D illustrates an example of a control arrangement. DESCRIPTION OF EMBODIMENTS The following embodiments are only examples. Although the specification may refer to “an” embodiment in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words “comprising” and “including” should be understood as not limiting the described embodiments to consist of only tho