A case study is presented in which several articles and patents suggested a specific outcome. Whe... more A case study is presented in which several articles and patents suggested a specific outcome. When the actual experimental work was performed, the results were found to be several orders of magnitude away from predicted values. Close re-inspection of the literature suggested that most of the authors actually extrapolated the results to conditions that were not applicable to their specific studies, resulting in the reporting errors. It is important to use literature to assist in research, but it is equally important not to blindly follow it either.
This paper will present several successful case studies where scale has been eliminated in mills ... more This paper will present several successful case studies where scale has been eliminated in mills including calcium carbonate scale in a white liquor strainer, calcium oxalate scale in the D0 stage, enzymatic treatment of brown stock to eliminate oxalate scale, and control of barium sulfate scale. Introduction Over the course of a single day of operation, thousands of pounds of calcium pass through a pulp mill and bleach plant. If process conditions are not properly maintained throughout the entire pulping and bleaching process, relatively small amounts of these materials may precipitate onto various process surfaces. Even though only small percentages of these minerals precipitate in troublesome areas to form process scale, extensive upsets in process operation and increases in operating costs result. Ironically, typical minor adjustments in operational conditions may be required to substantially reduce or eliminate scale formation. It is possible to predict what these process chang...
Within the past 15 years, at least three bleach plants in North America experienced catastrophic ... more Within the past 15 years, at least three bleach plants in North America experienced catastrophic equipment failures associated with the use of 50 wt% peroxide. People were badly injured in two instances, and these mills were fortunate to have avoided fatalities in these events. Hydrogen peroxide can be and has been used safely for many years, but like any strong oxidant, it must be handled with respect. This paper evaluates safety concerns associated with the use of hydrogen peroxide in the bleach plant. Several safety practices are suggested to address issues identified by these explosions and minimize the risk associated with use of peroxide.
Mineral scale problems are not new to pulp mills and bleach plants. The liquor recovery system en... more Mineral scale problems are not new to pulp mills and bleach plants. The liquor recovery system ensures that white liquor is saturated in calcium carbonate, and this mineral will precipitate when heated to cooking temperatures in the digester [1,2]. The original single-vessel continuous digesters sold by Kamyr had an extra liquor heater as standard equipment to enable the mill to take one heater out of service for acid cleaning without impacting production [3]. Although lime scale in the digester is generally the most routine scaling problem in pulp mills, various other scales are common in the chemical recovery area [4,5], and several types of mineral scale can turn up in bleach plants or on the paper machines. Efforts to reduce wastewater discharge using countercurrent filtrate recycle schemes in the bleach plant [6,7] certainly increased problems with mineral scale, but except with direct countercurrent filtrate management [8], scale problems were usually not severe. Mechanical pu...
Natural and renewable polymer-based barrier materials play an inevitable role in a sustainable ec... more Natural and renewable polymer-based barrier materials play an inevitable role in a sustainable economy. Most commercially available barrier materials are either based on multiple layers of synthetic polymers or petroleum-based chemicals. Tremendous amounts of research are being done in academia and industry to replace these synthetic barrier materials with natural and environmentally friendly materials. The current work summarizes the application of starch-based materials for various barrier applications, such as water vapor, oxygen, liquid water, oil, and grease. Also, exotic starch-based barrier materials for the application of sound, ultraviolet, and thermal barrier applications are reviewed. The potential of starch-based materials to offer antimicrobial and antiviral properties is discussed. Finally, commercially available starch-based barrier materials have been summarized.
A modified kraft pulping process has been developed that successfully breaks the traditional hard... more A modified kraft pulping process has been developed that successfully breaks the traditional hardwood kraft pulp yield barrier. The process produces fully bleached, high brightness hardwood kraft pulp with a yield of greater than 53% on wood. Details of the development and processing steps, along with various recovery cycle impacts, are discussed.
The MeadWestvaco mill in Evadale, TX, USA, in conjunction with VOW Resources LLC, has constructed... more The MeadWestvaco mill in Evadale, TX, USA, in conjunction with VOW Resources LLC, has constructed and commissioned a green biogas skid-mounted pilot plant to evaluate the potential of various organic waste streams to produce high-quality biogas. It is the fourth plant in the world incorporating this technical approach to biogas production. At initial startup, the plant used cow manure as organic feedstock. To commission the plant for verifying the VOW bioaugmentation process, the transition was made to using brown grease. After the brown grease commissioning trials are completed, the plant will be transitioned to a number of paper mill-generated organic wastes to acquire the design parameters and engineering data that will aid in construction of a full-scale biogas facility.
Several mills in North America have been successful in using xylanase enzymes expressed from Tric... more Several mills in North America have been successful in using xylanase enzymes expressed from Trichoderma reesei (a fungus) as part of their bleaching sequence for many years. These mills process hardwood and softwood species, with and without oxygen delignification. These mills also use three-, four-, and five-stage bleaching sequences. North American mills tend to report increased pulp brightness ceilings and decreased bleaching costs as benefits associated with the application of enzymes in the bleaching process. Laboratory testing suggests that eucalyptus pulp is highly susceptible to fungal- and bacterial-derived enzyme bleaching and should result in significant cost savings in South American mills. At least four different mills in South America have attempted to perform enzyme bleaching trials using bacterial-derived enzymes. Each of these mill trials resulted in significantly increased operating costs and/or unsustainable operating conditions. More recently, one of these South...
Optimization of the lime kiln requires an examination of the entire lime cycle. To increase the e... more Optimization of the lime kiln requires an examination of the entire lime cycle. To increase the energy efficiency of the lime kiln, all auxiliary unit operations must function properly. It is also imperative that the lime and liquor in the system is of acceptable quality. We detail a kiln energy efficiency study performed by MWV Corp.’s Covington, VA, USA, mill. From a recausticizing standpoint, lime quality is much easier to control than liquor quality because liquor passes through many operations that are not under the lime kiln operator’s control. Recausticizing is a fairly closed cyclical process where lime is concerned, so saturation of impurities to the point of operational issues must be considered. Specific cycle performance indicators (e.g., lime mud solids entering the kiln) must be viewed from a perspective that does not exclude their potential impact. To get a true picture of the cost of operating the lime cycle, all inputs must be considered. The four main inputs are po...
The current trend to further reuse water within paper mills has resulted in more accumulated salt... more The current trend to further reuse water within paper mills has resulted in more accumulated salts, as reflected by increased conductivity values. Although conductivity measurement is widely used in paper mills, its fundamental principles and interpretation are not often fully understood. This keeps papermakers from reaching the full benefits of using conductivity measurements to help manage the wet end chemistry of paper or board machines. High and variable conductivity affects the intrinsic properties of pulps, the performance of chemical additives, and the interaction between them. This paper reviews principles of conductivity; its measurement; its effect on important aspects of papermaking operations, such as retention, drainage, sizing, strength development and deposit control; and the fundamentals behind the effects of conductivity on the papermaking process. Specific mill examples are also provided. Potential solutions for operating a mill under high and variable conductivity...
Several articles have been published during the past 30 years on different methods to produce mic... more Several articles have been published during the past 30 years on different methods to produce micro- to nanosize cellulose particles from pulp. Unfortunately, a general lack of information exists on the impact of differing manufacturing process methods upon the product properties obtained from these differing methods. Literature data show that wet processing of small-sized cellulosic fibers generates handsheets with approximately equal or higher density and modulus of elasticity than controls for a given amount of added microcellulose. The current work evaluated small particle generation from pulp fibers via dry processing methods and compared the physical properties of dry versus wet processed particles. Dry processing to obtain microcellulose gave considerably lower sheet density and modulus as compared with wet processed microcellulose. The lower modulus can be compensated for by refining base fibers more aggressively to obtain higher density and higher modulus sheets. Dry proces...
During the late 1980’s and early 1990’s, researchers determined that bleach plants were releasing... more During the late 1980’s and early 1990’s, researchers determined that bleach plants were releasing potentially significant quantities of chlorinated organics into receiving waters. Extensive research efforts were made to develop bleaching chemicals to enable the elimination of chlorine and hypochlorite from the bleaching sequence. The cost of some of these new chlorine free bleaching sequences were extremely high while other bleaching options were on a par with existing chlorine based bleaching. Once the industry tended to settle upon 100% chlorine dioxide substitution for chlorine as the industrial standard (today’s ECF Bleaching), research efforts shifted from the development of new bleaching chemistries towards the chemical optimization of the ECF bleaching sequence with chlorine dioxide. Several delignification stage and brightening stage models were developed. Once good models were developed, it was possible to employ these models in bleach plant simulations to optimize chemical...
The mineral scale that deposits in digesters and bleach plants is formed by a chemical precipitat... more The mineral scale that deposits in digesters and bleach plants is formed by a chemical precipitation process. As such, it is accurately described or modeled using the solubility product equilibrium constant. Although solubility product identifies the primary conditions that need to be met for a scale problem to exist, the acid base equilibria of the scaling anions often control where in the process scale will occur and are the primary control method to minimize or prevent scale in a bleach plant. As equilibrium processes, both the acid/base equilibrium and solubility product are influenced by temperature and ionic strength. In this paper, the chemistry of precipitation and acid/base equilibria will be reviewed. The use of the Gibbs Free Energy expression that connects equilibrium constants to enthalpy entropy and temperature will be discussed. The affect of ionic strength on ion activity and how it influences these processes will also be presented. Terms and general principals There...
The nature of chlorine dioxide substitution for chlorine in the chlorination reaction sequence of... more The nature of chlorine dioxide substitution for chlorine in the chlorination reaction sequence of pulp bleaching in not well understood. Multiple results may be obtained by simply altering the order of chlorine-chlorine dioxide addition and the amount of chlorine dioxide substitution. Kinetic curves for chlorine, chlorine dioxide, and various levels of chlorine dioxide substitution were generated. The effects of these various processes on delignification (kappa number reduction) and Adsorbable Organic Halogen (AOX) generation were investigated. More than half of the AOX was found to be generated within the first one minute of any reaction sequence. Similar portions of the delignification were also found to occur within the first one minute of chlorination. The work examines the assumption that chlorine and chlorine dioxide react with different portions of the lignin. Thus chlorine and chlorine dioxide compete for only a part of the lignin molecule. The order of chemical addition dictates which chemical mo...
Below are the 24 publications authored or co-authored by Alan W. Rudie sorted by year. You may re... more Below are the 24 publications authored or co-authored by Alan W. Rudie sorted by year. You may re-sort the listing by: Title, Category, Date Posted -or-Publication Year. ... Category: Journal Articles File size: 429 kb(s) Abstract: Three pulp mills in North America using 50% ...
A new‐generation continuous digester model has been developed based on first principles of fundam... more A new‐generation continuous digester model has been developed based on first principles of fundamental material, energy, and momentum balances. The modeling approach considers all of the important physical and chemical phenomena that are pertinent to digester operations: notably, chip size distribution, dynamics of chip column compaction, diffusion and reaction fluxes between entrapped and free liquor, and relative velocity differences between chip column and liquor flows. The model calculates time‐dependent behavior of process conditions including but not limited to chip levels, residual EA (effective alkali) density and Kappa (a measure of the extent of reaction) progression through the digester, temperature and dissolved solids profiles, conversion, and blow consistency. The model emulates real operational conditions as closely as possible so that all process decision variables available to an operator are also similar input variables to the model. The model is fast, nearly 300 t...
A case study is presented in which several articles and patents suggested a specific outcome. Whe... more A case study is presented in which several articles and patents suggested a specific outcome. When the actual experimental work was performed, the results were found to be several orders of magnitude away from predicted values. Close re-inspection of the literature suggested that most of the authors actually extrapolated the results to conditions that were not applicable to their specific studies, resulting in the reporting errors. It is important to use literature to assist in research, but it is equally important not to blindly follow it either.
This paper will present several successful case studies where scale has been eliminated in mills ... more This paper will present several successful case studies where scale has been eliminated in mills including calcium carbonate scale in a white liquor strainer, calcium oxalate scale in the D0 stage, enzymatic treatment of brown stock to eliminate oxalate scale, and control of barium sulfate scale. Introduction Over the course of a single day of operation, thousands of pounds of calcium pass through a pulp mill and bleach plant. If process conditions are not properly maintained throughout the entire pulping and bleaching process, relatively small amounts of these materials may precipitate onto various process surfaces. Even though only small percentages of these minerals precipitate in troublesome areas to form process scale, extensive upsets in process operation and increases in operating costs result. Ironically, typical minor adjustments in operational conditions may be required to substantially reduce or eliminate scale formation. It is possible to predict what these process chang...
Within the past 15 years, at least three bleach plants in North America experienced catastrophic ... more Within the past 15 years, at least three bleach plants in North America experienced catastrophic equipment failures associated with the use of 50 wt% peroxide. People were badly injured in two instances, and these mills were fortunate to have avoided fatalities in these events. Hydrogen peroxide can be and has been used safely for many years, but like any strong oxidant, it must be handled with respect. This paper evaluates safety concerns associated with the use of hydrogen peroxide in the bleach plant. Several safety practices are suggested to address issues identified by these explosions and minimize the risk associated with use of peroxide.
Mineral scale problems are not new to pulp mills and bleach plants. The liquor recovery system en... more Mineral scale problems are not new to pulp mills and bleach plants. The liquor recovery system ensures that white liquor is saturated in calcium carbonate, and this mineral will precipitate when heated to cooking temperatures in the digester [1,2]. The original single-vessel continuous digesters sold by Kamyr had an extra liquor heater as standard equipment to enable the mill to take one heater out of service for acid cleaning without impacting production [3]. Although lime scale in the digester is generally the most routine scaling problem in pulp mills, various other scales are common in the chemical recovery area [4,5], and several types of mineral scale can turn up in bleach plants or on the paper machines. Efforts to reduce wastewater discharge using countercurrent filtrate recycle schemes in the bleach plant [6,7] certainly increased problems with mineral scale, but except with direct countercurrent filtrate management [8], scale problems were usually not severe. Mechanical pu...
Natural and renewable polymer-based barrier materials play an inevitable role in a sustainable ec... more Natural and renewable polymer-based barrier materials play an inevitable role in a sustainable economy. Most commercially available barrier materials are either based on multiple layers of synthetic polymers or petroleum-based chemicals. Tremendous amounts of research are being done in academia and industry to replace these synthetic barrier materials with natural and environmentally friendly materials. The current work summarizes the application of starch-based materials for various barrier applications, such as water vapor, oxygen, liquid water, oil, and grease. Also, exotic starch-based barrier materials for the application of sound, ultraviolet, and thermal barrier applications are reviewed. The potential of starch-based materials to offer antimicrobial and antiviral properties is discussed. Finally, commercially available starch-based barrier materials have been summarized.
A modified kraft pulping process has been developed that successfully breaks the traditional hard... more A modified kraft pulping process has been developed that successfully breaks the traditional hardwood kraft pulp yield barrier. The process produces fully bleached, high brightness hardwood kraft pulp with a yield of greater than 53% on wood. Details of the development and processing steps, along with various recovery cycle impacts, are discussed.
The MeadWestvaco mill in Evadale, TX, USA, in conjunction with VOW Resources LLC, has constructed... more The MeadWestvaco mill in Evadale, TX, USA, in conjunction with VOW Resources LLC, has constructed and commissioned a green biogas skid-mounted pilot plant to evaluate the potential of various organic waste streams to produce high-quality biogas. It is the fourth plant in the world incorporating this technical approach to biogas production. At initial startup, the plant used cow manure as organic feedstock. To commission the plant for verifying the VOW bioaugmentation process, the transition was made to using brown grease. After the brown grease commissioning trials are completed, the plant will be transitioned to a number of paper mill-generated organic wastes to acquire the design parameters and engineering data that will aid in construction of a full-scale biogas facility.
Several mills in North America have been successful in using xylanase enzymes expressed from Tric... more Several mills in North America have been successful in using xylanase enzymes expressed from Trichoderma reesei (a fungus) as part of their bleaching sequence for many years. These mills process hardwood and softwood species, with and without oxygen delignification. These mills also use three-, four-, and five-stage bleaching sequences. North American mills tend to report increased pulp brightness ceilings and decreased bleaching costs as benefits associated with the application of enzymes in the bleaching process. Laboratory testing suggests that eucalyptus pulp is highly susceptible to fungal- and bacterial-derived enzyme bleaching and should result in significant cost savings in South American mills. At least four different mills in South America have attempted to perform enzyme bleaching trials using bacterial-derived enzymes. Each of these mill trials resulted in significantly increased operating costs and/or unsustainable operating conditions. More recently, one of these South...
Optimization of the lime kiln requires an examination of the entire lime cycle. To increase the e... more Optimization of the lime kiln requires an examination of the entire lime cycle. To increase the energy efficiency of the lime kiln, all auxiliary unit operations must function properly. It is also imperative that the lime and liquor in the system is of acceptable quality. We detail a kiln energy efficiency study performed by MWV Corp.’s Covington, VA, USA, mill. From a recausticizing standpoint, lime quality is much easier to control than liquor quality because liquor passes through many operations that are not under the lime kiln operator’s control. Recausticizing is a fairly closed cyclical process where lime is concerned, so saturation of impurities to the point of operational issues must be considered. Specific cycle performance indicators (e.g., lime mud solids entering the kiln) must be viewed from a perspective that does not exclude their potential impact. To get a true picture of the cost of operating the lime cycle, all inputs must be considered. The four main inputs are po...
The current trend to further reuse water within paper mills has resulted in more accumulated salt... more The current trend to further reuse water within paper mills has resulted in more accumulated salts, as reflected by increased conductivity values. Although conductivity measurement is widely used in paper mills, its fundamental principles and interpretation are not often fully understood. This keeps papermakers from reaching the full benefits of using conductivity measurements to help manage the wet end chemistry of paper or board machines. High and variable conductivity affects the intrinsic properties of pulps, the performance of chemical additives, and the interaction between them. This paper reviews principles of conductivity; its measurement; its effect on important aspects of papermaking operations, such as retention, drainage, sizing, strength development and deposit control; and the fundamentals behind the effects of conductivity on the papermaking process. Specific mill examples are also provided. Potential solutions for operating a mill under high and variable conductivity...
Several articles have been published during the past 30 years on different methods to produce mic... more Several articles have been published during the past 30 years on different methods to produce micro- to nanosize cellulose particles from pulp. Unfortunately, a general lack of information exists on the impact of differing manufacturing process methods upon the product properties obtained from these differing methods. Literature data show that wet processing of small-sized cellulosic fibers generates handsheets with approximately equal or higher density and modulus of elasticity than controls for a given amount of added microcellulose. The current work evaluated small particle generation from pulp fibers via dry processing methods and compared the physical properties of dry versus wet processed particles. Dry processing to obtain microcellulose gave considerably lower sheet density and modulus as compared with wet processed microcellulose. The lower modulus can be compensated for by refining base fibers more aggressively to obtain higher density and higher modulus sheets. Dry proces...
During the late 1980’s and early 1990’s, researchers determined that bleach plants were releasing... more During the late 1980’s and early 1990’s, researchers determined that bleach plants were releasing potentially significant quantities of chlorinated organics into receiving waters. Extensive research efforts were made to develop bleaching chemicals to enable the elimination of chlorine and hypochlorite from the bleaching sequence. The cost of some of these new chlorine free bleaching sequences were extremely high while other bleaching options were on a par with existing chlorine based bleaching. Once the industry tended to settle upon 100% chlorine dioxide substitution for chlorine as the industrial standard (today’s ECF Bleaching), research efforts shifted from the development of new bleaching chemistries towards the chemical optimization of the ECF bleaching sequence with chlorine dioxide. Several delignification stage and brightening stage models were developed. Once good models were developed, it was possible to employ these models in bleach plant simulations to optimize chemical...
The mineral scale that deposits in digesters and bleach plants is formed by a chemical precipitat... more The mineral scale that deposits in digesters and bleach plants is formed by a chemical precipitation process. As such, it is accurately described or modeled using the solubility product equilibrium constant. Although solubility product identifies the primary conditions that need to be met for a scale problem to exist, the acid base equilibria of the scaling anions often control where in the process scale will occur and are the primary control method to minimize or prevent scale in a bleach plant. As equilibrium processes, both the acid/base equilibrium and solubility product are influenced by temperature and ionic strength. In this paper, the chemistry of precipitation and acid/base equilibria will be reviewed. The use of the Gibbs Free Energy expression that connects equilibrium constants to enthalpy entropy and temperature will be discussed. The affect of ionic strength on ion activity and how it influences these processes will also be presented. Terms and general principals There...
The nature of chlorine dioxide substitution for chlorine in the chlorination reaction sequence of... more The nature of chlorine dioxide substitution for chlorine in the chlorination reaction sequence of pulp bleaching in not well understood. Multiple results may be obtained by simply altering the order of chlorine-chlorine dioxide addition and the amount of chlorine dioxide substitution. Kinetic curves for chlorine, chlorine dioxide, and various levels of chlorine dioxide substitution were generated. The effects of these various processes on delignification (kappa number reduction) and Adsorbable Organic Halogen (AOX) generation were investigated. More than half of the AOX was found to be generated within the first one minute of any reaction sequence. Similar portions of the delignification were also found to occur within the first one minute of chlorination. The work examines the assumption that chlorine and chlorine dioxide react with different portions of the lignin. Thus chlorine and chlorine dioxide compete for only a part of the lignin molecule. The order of chemical addition dictates which chemical mo...
Below are the 24 publications authored or co-authored by Alan W. Rudie sorted by year. You may re... more Below are the 24 publications authored or co-authored by Alan W. Rudie sorted by year. You may re-sort the listing by: Title, Category, Date Posted -or-Publication Year. ... Category: Journal Articles File size: 429 kb(s) Abstract: Three pulp mills in North America using 50% ...
A new‐generation continuous digester model has been developed based on first principles of fundam... more A new‐generation continuous digester model has been developed based on first principles of fundamental material, energy, and momentum balances. The modeling approach considers all of the important physical and chemical phenomena that are pertinent to digester operations: notably, chip size distribution, dynamics of chip column compaction, diffusion and reaction fluxes between entrapped and free liquor, and relative velocity differences between chip column and liquor flows. The model calculates time‐dependent behavior of process conditions including but not limited to chip levels, residual EA (effective alkali) density and Kappa (a measure of the extent of reaction) progression through the digester, temperature and dissolved solids profiles, conversion, and blow consistency. The model emulates real operational conditions as closely as possible so that all process decision variables available to an operator are also similar input variables to the model. The model is fast, nearly 300 t...
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