US-20260124782-A1 - METHOD AND ARRANGEMENT FOR FEEDBACK BASED CONTROL IN CHEMICAL REFINING OF WOOD

US20260124782A1US 20260124782 A1US20260124782 A1US 20260124782A1US-20260124782-A1

Abstract

Method and control system are provided for controlling values of process parameters of a pretreatment process of wood particles. A sampler is used to obtain a sample of a product flow of said pretreatment process after said wood particles have undergone steam explosion in a hemihydrolysis reactor. A particle measurement device is used to measure one or more characteristics of particles in said sample and to produce one or more pieces of measurement information indicative of the measured characteristics. Said one or more pieces of measurement information are used to select one or more values of one or more of said process parameters.

Inventors

Sami Turunen
Mika Laitila
Juha Tamper

Assignees

UPM-KYMMENE CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251229
Priority Date: 20190129

Claims (15)

1 . Method for controlling values of process parameters of a pretreatment process of wood particles, comprising: using a sampler to obtain a sample of a product flow of said pretreatment process after said wood particles have undergone steam explosion in a hemihydrolysis reactor, using a particle measurement device to measure one or more characteristics of particles in said sample and to produce one or more pieces of measurement information indicative of the measured characteristics, and using said one or more pieces of measurement information to select one or more values of one or more of said process parameters; wherein said one or more of said process parameters comprise at least a second residence time of said product flow in an impregnating vessel that precedes said hemihydrolysis reactor in said pretreatment.
2 . A method according to claim 1 , wherein said one or more of said process parameters comprise at least one of: a temperature in said hemihydrolysis reactor, a pressure difference between an input and output of said hemihydrolysis reactor, a first residence time of said product flow in said hemihydrolysis reactor.
3 . A method according to claim 2 , wherein: said particle measurement device is configured to measure particle size or particle size distribution in said sample as one of said one or more characteristics of particles, the measured particle size or particle size distribution is compared to a default size or a default size distribution respectively to produce at least a first piece of said one or more pieces of measurement information, and value for at least one of said temperature, said pressure difference, or said first residence time is increased to increase reaction severity in said hemihydrolysis reactor in response to said first piece of measurement information indicating larger than default particles in said sample.
4 . A method according to claim 2 , wherein: said particle measurement device is configured to measure particle size or particle size distribution in said sample as one of said one or more characteristics of particles, the measured particle size or particle size distribution is compared to a default size or a default size distribution respectively to produce at least a first piece of said one or more pieces of measurement information, and value for at least one of said temperature, said pressure difference, or said first residence time is decreased to decrease reaction severity in said hemihydrolysis reactor in response to said first piece of measurement information indicating smaller than default particles in said sample.
5 . A method according to claim 1 , wherein said one or more of said process parameters comprise additionally at least one of: acid content of an impregnating solution used to impregnate said product flow in said impregnating vessel third residence time of said product flow in a first soaking silo that precedes said impregnating vessel in said pretreatment, fourth residence time of said product flow in a pre-steaming silo that precedes said impregnating vessel in said pretreatment, fifth residence time of said product flow in a second soaking silo that is between said impregnating vessel and said hemihydrolysis reactor in said pretreatment.
6 . A method according to claim 5 , wherein: said particle measurement device is configured to measure shive content in said sample as one of said one or more characteristics of particles, the measured shive content is compared to a default shive content to produce at least a second piece of said one or more pieces of measurement information, and value for at least one of said second residence time or said acid content is selected to intensify impregnation of wood particles in said impregnating vessel in response to said second piece of measurement information indicating larger than default shive content.
7 . A method according to claim 5 , wherein: said particle measurement device is configured to measure shive content in said sample as one of said one or more characteristics of particles, the measured shive content is compared to a default shive content to produce at least a second piece of said one or more pieces of measurement information, and value for at least one of said third residence time or said fifth residence time is selected to intensify impregnation of wood particles in said first or second soaking silo respectively in response to said second piece of measurement information indicating larger than default shive content.
8 . A method according to claim 1 , wherein said one or more of said process parameters comprise at least one of: rotation rate of a mixer that succeeds said hemihydrolysis reactor in said pretreatment, sixth residence time of said product flow in said mixer.
9 . A method according to claim 8 , wherein: said particle measurement device is configured to measure homogeneity in said sample as one of said one or more characteristics of particles, the measured homogeneity is compared to a default homogeneity to produce at least a third piece of said one or more pieces of measurement information, and value for at least one of said rotation rate or said sixth residence time is increased to intensify homogenizing of said product flow in said mixer in response to said third piece of measurement information indicating lower than default homogeneity.
10 . A method according to claim 1 , wherein said particle measurement device is configured to directly measure presence and size of particles in said sample with an optical measurement method.
11 . A method according to claim 1 , wherein said particle measurement device is configured to measure one or more characteristics of particles in said sample through an indirect measurement method not measuring directly the presence and size of particles in the sample.
12 . A method according to claim 11 , wherein said particle measurement device is configured to measure drainability of said sample.
13 . A method according to claim 1 , comprising: using a measurement device to measure content of one or more chemical constituents in said product flow after wood particles in said product flow have undergone said steam explosion, and to produce one or more pieces of chemical constituent information indicative of the measured content, and using said one or more pieces of chemical constituent information to select one or more values of said one or more process parameters.
14 . A method according to claim 13 , wherein said chemical constituents comprise at least one of: furfural, lactic acid.
15 . A control system for controlling a pretreatment process of wood particles, the control system comprising: one or more measurement information inputs for receiving measurement information indicative of measured characteristics of samples of a product flow in said pretreatment process, one or more control information outputs for setting values for one or more process parameters of said pretreatment process, and a processing engine coupled to said measurement information inputs and said control information outputs; wherein said processing engine is programmed to use a sampler to obtain a sample of a product flow of said pretreatment process after said wood particles have undergone steam explosion in a hemihydrolysis reactor, use a particle measurement device to measure one or more characteristics of particles in said sample and to produce one or more pieces of measurement information indicative of the measured characteristics, and use said one or more pieces of measurement information to select one or more values of one or more of said process parameters; and wherein said one or more of said process parameters comprise at least a second residence time of said product flow in an impregnating vessel that precedes said hemihydrolysis reactor in said pretreatment.

Description

FIELD OF THE INVENTION The invention concerns the general technical field of converting biomass into chemical bioproducts in industrial scale. In particular the invention concerns the technology of maintaining appropriate quality of the product that comes through various pretreating stages. BACKGROUND OF THE INVENTION The production of biomass-based chemicals may use for example wood particles as the main raw material. In a biomass-to-sugar process the wood particles may be subjected to various kinds of pretreatment such as washing and impregnating with water and/or other liquids, and subjected to elevated temperature and pressure, in order to prepare the material for the later stages of the process. A pretreatment process may involve soaking the wood particles in steam or hot water, then soaking them in dilute acid, and subsequently taking the acid-impregnated wood particles into a hemihydrolysis reactor where a steam explosion reaction breaks the particles into reaction products such as cellulose, hemicellulose (so-called C5 sugar), and lignin. Mechanical conveyors such as screw feeders transfer the impregnated wood particles between the stages of the pretreatment process. The quality of the product that comes out of pretreatment depends on a number of factors, such as the physical and chemical conditions in the various pretreatment stages for example. The nature and implementation of the pretreatment process should be such that it allows continuous running for extended periods, so that the quality of the product that comes out of pretreatment is and can be constantly maintained within predetermined limits. A prior art document EP 2 759 597 A1 discloses image analysis based process control of processes for production of sugar from lignocellulosic biomass, and a corresponding system. The method comprises steps like pretreating, saccharification, analyzing particles, and controlling process parameters on the basis of analysis data. Another prior art document WO 2017/066042 A1 discloses NIR measurements in the production of a target chemical from cellulose. The method comprises steps like pretreating, analyzing with NIR spectroscopy, simultaneous saccharification and fermentation, analyzing anew with NIR spectroscopy, and controlling process parameters on the basis of the NIR analysis data. SUMMARY According to a first aspect there is provided a method for controlling values of process parameters of a pretreatment process of wood particles. The method comprises using a sampler to obtain a sample of a product flow of said pretreatment process after said wood particles have undergone steam explosion in a hemihydrolysis reactor, using a particle measurement device to measure one or more characteristics of particles in said sample and to produce one or more pieces of measurement information indicative of the measured characteristics, and using said one or more pieces of measurement information to select one or more values of one or more of said process parameters. According to a second aspect there is provided a control system for controlling a pretreatment process of wood particles. The control system comprises one or more measurement information inputs for receiving measurement information indicative of measured characteristics of samples of a product flow in said pretreatment process. The control system comprises one or more control information outputs for set-ting values for one or more process parameters of said pretreatment process, and a processing engine coupled to said measurement information inputs and said control information outputs. The processing engine is programmed to execute a method of the kind described above. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the described embodiments and constitute a part of this specification, illustrate various advantageous features and examples of their combinations. In the drawings: FIG. 1 illustrates a chemical refining process on a general level, FIG. 2 illustrates an example of process stages in pretreatment, and FIG. 3 illustrates an example of a method and an arrangement for feedback based control of process parameter values. DETAILED DESCRIPTION Numerical attributes such as first, second, third, and so on are used in this description and the appended claims for the purpose of giving unambiguous names to concepts. They do not refer to any particular order, unless otherwise explicitly stated. In the context of this description the term wood particles refers to a material that consists mainly of pieces of wood formed by cutting or chipping larger pieces of wood such as trees, branches, logging residues, stumps, roots, and wood waste. The size of the wood particles may vary in a wide range from a few millimetres to a few centimetres, so the wood particles meant here are typically larger than those meant with the term sawdust. The wood used to make wood particles may be debarked or it ma