Application of the refractometer in the measurement and monitoring of brown stock washing

Riku Kopra

Application of the refractometer in the measurement and monitoring of brown stock washing

Julkaisun otsikon käännös: Refraktometrin soveltaminen ruskean massan pesun mittauksessa ja seurannassa

Riku Kopra

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Sellun pesussa massasuspensiosta poistetaan liuenneet epäpuhtaudet. Samalla otetaan talteen keittokemikaalit ja poltetaan orgaaniset ainekset energiaksi. Suureet, joita käytetään pesun onnistumisen tai tehokkuuden kuvaamiseen on perinteisesti jaettu kahteen osaan: pesuhäviöön, joka kuvaa pestävissä olevien komponenttien määrää massasuspensiossa ja laimennuskertoimeen, joka ilmoittaa nettomäärän vettä, mitä on lisätty pesun aikana. Ruskean massan pesun onnistumisella on vaikutuksia moneen sellutehtaan osaprosessiin, kuten haihdutukseen, happidelignifiointiin, valkaisuun ja jätevedenkäsittelyyn. Pesutuloksella voi olla joko positiivisia tai negatiivisia vaikutuksia näihin osaprosesseihin. Tästä syystä on tärkeää löytää oikea optimaalinen toimintapiste ruskean massan pesulle, koska ilman tehokasta pesua kemiallisen massan tuotanto ei ole taloudellisesti mahdollista. Tämän tutkimuksen lähtökohtana oli kehittää reaaliaikainen mittaussovellus kemiallisen massan pesuun, jolla voitaisiin mitata pestävissä olevia komponentteja tai niiden summaparametreja neste- ja massavirroista. Kokeita suoritettiin sekä laboratorio- että tehdasmittakaavassa. Seuraavassa vaiheessa tutkittiin liuennutta kuiva-ainetta mittaavan refraktometrin soveltuvuutta pesuhäviön mittaamiseen ja seurattiin ruskean massan pesun onnistumista systemaattisesti ja näin otettiin prosessi haltuun käyttämällä riittävä määrä kyseisten mittausten mittaustuloksia. Lisäksi erilaisten pesureiden toimintaparametreja tutkittiin askelvastekokeiden avulla ja tuloksia seurattiin refraktometreilla. Tulokset osoittivat, että refraktometri toimi riittävällä tarkkuudella hyvin haastavissa prosessiolosuhteissa ja kykeni luotettavasti mittaamaan neste- ja massavirtojen liuennutta kuiva-ainetta. Täten luotettava pesuhäviömittaus voidaan toteuttaa refraktometreilla, kunhan kalibrointi tehdään kullekin käytettävälle puulajille ja huomioiden kulloisenkin asennuspaikan pitoisuusalue. Hyödyntämällä kolmen refraktometrin mittaustuloksia sekä sakeus- ja virtausmittauksia, oli mahdollista luoda mittaussysteemi, jolla voitiin laskea yksittäisen pesurin tehokkuus reaaliajassa riittävän tarkasti. Refraktometreja voidaan käyttää myös yksittäisten pesureiden optimaalisen toimintapisteen määrittämisessä. Säätämällä pesurin toimintaa kohti optimaalista toimintapistettä onnistuttiin vähentämään pesuhäviön määrää happivaiheeseen ja valkaisuun sekä lisäämään kuiva-ainepitoisuutta haihduttamoon ja siten saavuttamaan merkittäviä taloudellisia säästöjä. Tämän työn jatkoksi tulevissa pesututkimuksissa on ajateltu sovittaa nestetaseet pesurin yli käyttämällä kolmea - neljää reaaliaikaista mittausta. Lisäksi olemme miettineet refraktometrin hyödyntämistä valkaisun pesussa ja kemikaalien kulutuksen optimoinnissa. Tulevaisuuden suunnitelmiin kuuluu myös refraktometrin hyödyntäminen alhaisissa pitoisuuksissa jätevedenkäsittelyn alueella.

Julkaisun otsikon käännös	Refraktometrin soveltaminen ruskean massan pesun mittauksessa ja seurannassa
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Dahl, Olli, Vastuuprofessori
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-6135-1
Sähköinen ISBN	978-952-60-6134-4
Tila	Julkaistu - 2015
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

sellun pesu
refraktometri
pesuhäviö
reaaliaikainen prosessin kontrollointi

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-6134-4Lisenssi: Määrittelemätön

Biotalousinfrastruktuuri
Seppälä, J. (Manager)
Kemian tekniikan korkeakoulu
Laitteistot/tilat: Facility

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@phdthesis{449c58222e8c4d85868c3bc8f11368fa,

title = "Application of the refractometer in the measurement and monitoring of brown stock washing",

abstract = "Brown stock kraft pulp washing removes soluble impurities from a pulp suspension, recovers cooking chemicals and incinerates organics for energy recovery (steam and electricity generation). The parameters used to describe the performance of washing or its effectiveness fall into two categories: wash loss, which describes the amount of washable compounds in the pulp suspension which could have been removed in washing, and the dilution factor which represents the net amount of water that is added during washing. The performance of brown stock washing has an effect on many sub-processes like evaporation, oxygen delignification, bleaching and waste water treatment. Washing results can have positive or negative effects on these sub-processes. It is important to find the correct optimal operating point for washing, because without effective washing of kraft pulp production is not economically viable. The starting point for this study was to develop a real-time measurement application for brown stock kraft pulp washing by which means it would be possible to measure washable compounds or their sum parameters in the liquid and pulp streams on a laboratory and mill scale. The next step was to study the feasibility of using a real-time refractometer, which measures dissolved dry solids, to measure wash loss and monitor the performance of brown stock washing systematically, and then be able to take control of the process by using the results of enough such measurements. In addition, different washers' operational performance were studied by performing stepwise tests and monitoring the results using refractometers. The results show that refractometer measurement works with enough accuracy under very demanding process conditions to reliably measure liquid and pulp streams' dissolved dry solids. Therefore, reliable wash loss measurement can be undertaken using refractometers, once calibration is carried out for the wood species and the installation's characteristics. By utilising the results from three refractometers' consistency and flow rate measurements, it was possible to create a measurement system able to calculate the effectiveness of a single washer accurately and in real time. These refractometers can also be used to determine a washer's optimal operating point. Adjusting a washer's operation towards more efficient operation succeeded in reducing the amount of wash loss to the oxygen delignification and bleaching stages, increasing the dry solids content to the evaporation stage and thus achieving significant economic savings. As continuation has considered to match the filtrate balances over the washers by using four or at least three real-time measurements. Moreover, utilising the refractometer in bleaching washing and calculating the wash loss effects on the bleaching costs has been considered. The work also involves utilising refractometers for very low concentrations in WWTP.",

keywords = "pulp washing, refractometer, wash loss, real-time process control, sellun pesu, refraktometri, pesuh{\"a}vi{\"o}, reaaliaikainen prosessin kontrollointi, pulp washing, refractometer, wash loss, real-time process control",

author = "Riku Kopra",

year = "2015",

language = "English",

isbn = "978-952-60-6135-1",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "39",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Application of the refractometer in the measurement and monitoring of brown stock washing

AU - Kopra, Riku

PY - 2015

Y1 - 2015

N2 - Brown stock kraft pulp washing removes soluble impurities from a pulp suspension, recovers cooking chemicals and incinerates organics for energy recovery (steam and electricity generation). The parameters used to describe the performance of washing or its effectiveness fall into two categories: wash loss, which describes the amount of washable compounds in the pulp suspension which could have been removed in washing, and the dilution factor which represents the net amount of water that is added during washing. The performance of brown stock washing has an effect on many sub-processes like evaporation, oxygen delignification, bleaching and waste water treatment. Washing results can have positive or negative effects on these sub-processes. It is important to find the correct optimal operating point for washing, because without effective washing of kraft pulp production is not economically viable. The starting point for this study was to develop a real-time measurement application for brown stock kraft pulp washing by which means it would be possible to measure washable compounds or their sum parameters in the liquid and pulp streams on a laboratory and mill scale. The next step was to study the feasibility of using a real-time refractometer, which measures dissolved dry solids, to measure wash loss and monitor the performance of brown stock washing systematically, and then be able to take control of the process by using the results of enough such measurements. In addition, different washers' operational performance were studied by performing stepwise tests and monitoring the results using refractometers. The results show that refractometer measurement works with enough accuracy under very demanding process conditions to reliably measure liquid and pulp streams' dissolved dry solids. Therefore, reliable wash loss measurement can be undertaken using refractometers, once calibration is carried out for the wood species and the installation's characteristics. By utilising the results from three refractometers' consistency and flow rate measurements, it was possible to create a measurement system able to calculate the effectiveness of a single washer accurately and in real time. These refractometers can also be used to determine a washer's optimal operating point. Adjusting a washer's operation towards more efficient operation succeeded in reducing the amount of wash loss to the oxygen delignification and bleaching stages, increasing the dry solids content to the evaporation stage and thus achieving significant economic savings. As continuation has considered to match the filtrate balances over the washers by using four or at least three real-time measurements. Moreover, utilising the refractometer in bleaching washing and calculating the wash loss effects on the bleaching costs has been considered. The work also involves utilising refractometers for very low concentrations in WWTP.

AB - Brown stock kraft pulp washing removes soluble impurities from a pulp suspension, recovers cooking chemicals and incinerates organics for energy recovery (steam and electricity generation). The parameters used to describe the performance of washing or its effectiveness fall into two categories: wash loss, which describes the amount of washable compounds in the pulp suspension which could have been removed in washing, and the dilution factor which represents the net amount of water that is added during washing. The performance of brown stock washing has an effect on many sub-processes like evaporation, oxygen delignification, bleaching and waste water treatment. Washing results can have positive or negative effects on these sub-processes. It is important to find the correct optimal operating point for washing, because without effective washing of kraft pulp production is not economically viable. The starting point for this study was to develop a real-time measurement application for brown stock kraft pulp washing by which means it would be possible to measure washable compounds or their sum parameters in the liquid and pulp streams on a laboratory and mill scale. The next step was to study the feasibility of using a real-time refractometer, which measures dissolved dry solids, to measure wash loss and monitor the performance of brown stock washing systematically, and then be able to take control of the process by using the results of enough such measurements. In addition, different washers' operational performance were studied by performing stepwise tests and monitoring the results using refractometers. The results show that refractometer measurement works with enough accuracy under very demanding process conditions to reliably measure liquid and pulp streams' dissolved dry solids. Therefore, reliable wash loss measurement can be undertaken using refractometers, once calibration is carried out for the wood species and the installation's characteristics. By utilising the results from three refractometers' consistency and flow rate measurements, it was possible to create a measurement system able to calculate the effectiveness of a single washer accurately and in real time. These refractometers can also be used to determine a washer's optimal operating point. Adjusting a washer's operation towards more efficient operation succeeded in reducing the amount of wash loss to the oxygen delignification and bleaching stages, increasing the dry solids content to the evaporation stage and thus achieving significant economic savings. As continuation has considered to match the filtrate balances over the washers by using four or at least three real-time measurements. Moreover, utilising the refractometer in bleaching washing and calculating the wash loss effects on the bleaching costs has been considered. The work also involves utilising refractometers for very low concentrations in WWTP.

KW - pulp washing

KW - refractometer

KW - wash loss

KW - real-time process control

KW - sellun pesu

KW - refraktometri

KW - pesuhäviö

KW - reaaliaikainen prosessin kontrollointi

KW - pulp washing

KW - refractometer

KW - wash loss

KW - real-time process control

M3 - Doctoral Thesis

SN - 978-952-60-6135-1

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Application of the refractometer in the measurement and monitoring of brown stock washing

Abstrakti

Tutkimusalat

Pääsy asiakirjaan

Sormenjälki

Laitteet

Biotalousinfrastruktuuri

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