- Email: [email protected]
Pulp and paper: Filtration prospects in wood products and paper making
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Feature Filtration+Separation May/June 2014
Pulp and paper
Filtration prospects in wood products and paper making I
n this article, Ken Sutherland reviews the current situation of the whole forest products sector and its uses for filtration and sedimentation equipment, not only in the manufacture of wood pulp and paper, but also for the case where wood can be considered to be playing its full part in a sustainable world.
Can we be looking at a major turn round in one of the less exciting equipment applications? Almost the whole forest products sector has taken a severe battering of late, the combination of a sharp fall in demand for paper, newsprint in particular, and the deep depression that hit most of the world from 2008 onwards. The result has been a decidedly split marketplace: with North America, Europe and Japan on the one hand, severely depressed, and the Developing World, led by China and India, on the other. There are definite signs that the losses recently suffered in the West by newspaper and other publishing are being more than made up, on the global scale, by the eager young readers in the growing populations of Asia. There was a time when wood was the main source of organic chemical products for all purposes, a function that it lost in the face of the greater availability, lower cost and easier processing, first of petroleum, and then of natural gas. Today, with the threat of an end to oil supplies as no longer unimaginable, there is talk of managed timber resources once more becoming a significant raw material for chemicals, especially if that management is undertaken sustainably.
and commercial activities using wood as a raw material, include the following applications: • the treatment of felled timber, including its weathering and preservation; • the manufacture of products from whole wood, from toothpicks to roof trusses; • the production of wood chips and the manufacture of wood particle boards and fibreboards; • the manufacture of chars and other fuel materials, and of biofuels; • the production of pure cellulose, regenerated cellulose, and viscose and rayon products; • the production of carbon products and other chemicals by the dry distillation or the solvent extraction of wood; • the manufacture of wood pulp, both firstrun and recycled, and from it, paper and paperboard of all kinds; and • the manufacture of articles from paper, paperboard and particleboard.
big users of heavy machinery, and as such the sector is a correspondingly large user of utility filters, on such services as hydraulic oil cleaning or pneumatic system filters. Boiler feed water and coolant system filters are also quite commonplace. As far as process filters are concerned, however, the sector is not a large user, with none at all required in the first two and the last of the above list of sub-sectors. Once the bulk timber needs to be reduced in size, however, for subsequent processing, there does begin to arise the need for process separation involvement, in the form of the machines required for the dry screening of the chipped wood granules, sending oversized particles back to the macerators, and diverting the undersize to fuel usage. By contrast, the processing of wood into pulp, and the conversion of that pulp into paper, use vast quantities of water: the pulp and paper industry is one of the largest industrial consumers of water, and uses more water per ton of product than any other industry. Filtration and other separation equipment have for some time been helping papermakers to reduce their environmental impact, but a major effort at improving efficiencies is still necessary to achieve some measure of sustainability in the industry.
The forest products industries
Of these subsectors, by far the largest in terms of interest to the filtration and sedimentation industry is that producing wood pulp and paper. This sub-sector is also unusual in that its main product, ie, cellulose pulp, is, so far as filtration is concerned, both a major sector product, with many uses, as well as being a key item in the whole technology of filtration, namely one of the most important types of filter medium.
The characteristics of wood
The full range of the forest products processing industries, i.e. all the industrial
With respect to the various types of filter, most parts of the forest products industry are
The chief feature of wood as far as its enduses are concerned is that it is largely made
Feature Filtration+Separation May/June 2014
There was a time when wood was the main source of organic chemical products.
up of cellulose, in the form of fibres that are embedded in a matrix of lignin, from which they are comparatively easily separated one from another, either chemically or mechanically. Wood is generally classified into hardwood (coming usually, but not entirely, from broadleaf, deciduous trees) or softwood (coming usually from coniferous, evergreen trees). The hardwoods are distinguished, in paper terms, by producing a pulp with very short fibres, which yield a weak paper, but impart a smooth finish to any paper made from them. Softwoods, on the other hand, have much longer fibres, which give a stronger paper, but with a rougher surface. Happily, an appropriate mix of pulps can usually give a paper with the required properties. The solid wood (ie, excluding bark) coming from an average tree is composed of four groups of materials: • firstly, and most importantly, there is the cellulose, making up about 45% of the dry weight of the wood, as a highly structured array of polymerised glucose chains, from which come the cellulose fibres; • secondly, there is hemi-cellulose, composed of several different sugar polymers in a much less well ordered array, making 20-25% of the dry weight, and for which there is still no economical use, except as fuel; • thirdly, and another polymer, there is lignin, also about 20-25% by weight, a complex dark-coloured compound, which binds the other components together, but which presents the major separation task in the paper production process, both to release the cellulose and to remove the colour from the final paper; and • finally, there are the extractives, a group of relatively simple organic chemicals that are recoverable by equally simple methods, such as dry distillation or solvent
One third of the world's wood pulp is now produced in China.
extraction, and include methanol, ethanol, and acetone.
The pulp and paper industry The global production of paper and paperboard (excluding merchant pulp) is now comfortably in excess of 400 million tonnes, with the slowing down in the USA and Europe more than offset by the growth in Asia. The Asian production is in excess of 40% of this, while close to 30% comes from Europe, and almost 25% from North America. China has pulled in front of the USA as the largest producing country, making over onethird of the world’s wood pulp. In individual company terms, the two largest companies in the paper business (by 2011 sales volume) were American. These were International Paper ($26bn) and Kimberly-Clark ($20.9bn), and they together represented over 13% of global sales. The top ten companies (by 2011 sales) also included six companies from Europe, two of these from Finland, and two from Japan. Together, these eight made up 40% of total global sales. Despite the large national production of pulp and paper in China, there are no very large Chinese companies as yet in this sector, although several are growing very fast, led by Nine Dragons Paper Company.
Pulp and paper making The pulp and paper industry is unusual among the end-use applications for filtration equipment in having just one main production process, which has two parts: the production of wood pulp and the manufacture of paper from it. These two parts may be contained in one plant on one site, the fully integrated mill, or quite separately as the non-integrated mill, one producing wood pulp, and the other converting pulp to paper. Apart from the need to dewater the produced pulp as thoroughly as possible, in a non-integrated pulp mill, so as to reduce the costs of transport between the two parts, there is no difference in operations between the fully integrated mill, and the two separate parts. The product of a pulp mill is a tradeable commodity, known as merchant pulp, which can be amalgamated from different sources into one paper mill to make particular kinds of paper. Although the bulk of paper originates from trees (55% from virgin pulp, and 38% from recycled wood-based paper – with 7% from non-tree sources), only about one fifth of all tree harvest goes into paper (the rest is fuel, wooden goods, particle board, etc.). It takes between two and three tons of timber to make one ton of paper, with the rest going to waste.
Production of wood pulp The total annual volume of sales of filtration and related process equipment, including filter media and membranes, to the whole forest products sector, is estimated to have been in the region of $2.5bn for the last three or four years. This total volume is only expected to rise significantly, in real (not inflated) terms, during 2014, as the Asian market starts to make up the continuing drop in the American and European markets. The three largest capital equipment companies in this sector are Andritz, Metso and Voith.
The paper production process begins with a whole tree, which needs to be separated into its component parts, either mechanically or chemically (to remove the lignin and other binders). The felled timber is first debarked, either mechanically, or by use of water jets. The separated bark is then dewatered and used on site as a fuel. There are primarily two ways of producing pulp: either mechanically,
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Feature Filtration+Separation May/June 2014
recycling is possible, unless a dark coloured product can be accepted. De-inking is a well-established process, involving separation equipment, but it creates another unpleasant waste stream, usually destined for landfill, so is the subject of much developmental work.
Separation equipment usage The prime use of filtration equipment in pulp and paper making relates to the sector’s need to close its water cycle as far as possible, for environmental as well as economic reasons. This move has benefited the filtration equipment suppliers, although there is still much to be done in the industry before the task is complete. The success of pulp and paper making relies on making a pulp with fibres of the correct size, and screens of one sort or another have a major role in this provision. Other uses for filtration equipment include the important recovery processes for black liquor, and bleaching and de-inking.
Wood as organic chemical raw material
Once felled, a tree is separated into its component parts either mechanically or by use of water jets.
From 2008, there has been a sharp decline in the demand for paper - newsprint in particular.
in which the whole logs are held against a grinding mechanism, which disintegrates the wood into its constituent fibres, but retains, in the product slurry, all the components of the original wood; or chemically, in which the logs are cut into chips, and the chips are dissolved in an alkaline solution, to produce a darkly coloured slurry of separated fibres.
create the correct mix for the paper quality required. This slurry is pumped into the head box (feed tank) from which a thin layer of slurry spreads out over the horizontal wire, running as a continuous roll away from the head box, and draining free of water as it does so. The wire is actually either a set of parallel strands, running the length of the machine (to produce laid paper), or, almost universally now, a fine wire mesh (to produce wove paper).
The steps that follow the main pulp producer are the refining of the slurry (to remove oversize particles) and then the bleaching of the fibres if a pale coloured or white paper is sought. Bleaching is a controversial process, in that it has relied upon chlorine or chlorine compounds, which find their way into the effluent. The industry has largely moved away from the use of free chlorine, and is now moving on to methods that do not use chlorine at all. The waste, so-called black liquors are processed to recover or remake the active chemical ingredients, which are then recycled in the mill. Potentially all of these chemicals can be recycled, although quite a significant quantity of noxious wastes is still produced. The reduction of these wastes is a continuing problem for the industry.
Papermaking The refined, and, if necessary, bleached, wood pulp is prepared as a thin slurry, together with a number of additives, especially fillers, to
The damp paper is picked up from the end of the wire and passed between sets of press and drying rolls, to bring the adsorbed water content down to that required in the finished paper. The final processes will usually include some kind of surface treatment such as calendering, to prepare it, mainly, to receive and hold ink on its surface.
Recycled paper Where recycled paper is to be used, this has to be done as a mixture of virgin and recycled pulp, because cellulose fibres cannot be recycled indefinitely – their quality decreases with each recycle process, and eight times is probably as often as can be expected. Recycled paper is much more easily pulped, and uses considerably less energy in doing so, than does the original pulping of wood. The main problem in paper recycling is the printing ink, which must be removed before
The potential use of wood as a source of organic chemicals has been mentioned, sufficient to show that a sizeable “wood refinery” could easily be developed, with perhaps as many product streams as a modern petroleum refinery. These products could include: • ethyl alcohol (from the same hydrolysis/ fermentation processes as currently yield the range of alcoholic spirit drinks, or industrial ethanol, from other raw materials); • methyl alcohol (from the same dry distillation process as first yielded charcoal and then methanol – which was initially called wood alcohol); • acetone and acetic acid (also by dry distillation); • -cellulose (a highly purified form of cellulose, which is a valuable product in its own right, as well as the precursor to a wide range of cellulose chemicals, such as the polymers cellulose acetate and cellulose nitrate); • regenerated cellulose (derived from -cellulose and a step in the formation of viscose materials, and rayon, both filament and film); and • ethers (such as ethyl cellulose, and carboxymethyl cellulose, also derived from -cellulose). With such a valuable list of products, and with wood of all kinds as raw material, it is tempting to ask why such a refinery does not exist – and the answer is easily found, namely: economics – it is just too expensive to try to make any of these products (except, of course, -cellulose) from wood as opposed to petroleum. However,
Feature Filtration+Separation May/June 2014
should the economic situation change, as might happen with the threatened “end of oil”, then the market may turn towards the forest for its organic chemicals. It is certain that, should this occur, a large market for separation equipment will be created, because many of the listed products are liquids, made in processes where feed solutions would be likely to be suspensions of wood fractions, needing separation.
Developments The complete change from a petrochemical basis for industrial activity to a wood-based one that was contemplated in the previous few paragraphs, is probably a bit far-fetched, but there are going to be some places in the world where wood pulp is abundant and petroleum as fuel is not, such that wood-based operations can be thought of sensibly, and suitable processes need to be developed. Continued increases in global paper consumption, once the effects of the recent recession have been overcome, are to be expected. Certainly the per capita consumption of paper among developing populations can be expected to cause the printing paper market to expand quite rapidly. Further progress can be expected on water and energy use efficiency in the pulping stage, on
still better waste paper recycling systems, and on wider use of timber from managed forests. The use of timber from a newly-felled tree is a fairly wasteful process, especially if it has to be transported any great distance to the pulp mill, so means whereby more of the tree can be used for top-grade applications will need to be developed. This may help to develop better quality papers, available at lower prices. There seems now to be good evidence that the electronic book reader is taking some “communication market” space away from printed paper, especially that for the daily newspaper. The production of paper from polymeric fibres, on the other hand, has been slow to take off. There is quite a lot of room in the wood fibre market before it becomes saturated, but there is also a lot of interest in alternative vegetable fibres: cotton rag (from which paper was made before wood fibre came along), jute, kenaf, and linen all have their protagonists. Jute is having a new lease of life as a supermarket bag, and eucalyptus wood is capturing a significant part of the paper market. Whatever the fibre, the paper making processes are much the same, and filters and other separation equipment will remain key components of the revamping of existing paper mills, and of the systems in ever-larger new mills to be built, especially to keep up with the demand in Asia and South America.
Separation equipment already has a good market in the construction industry’s need for particle board for coverage of new buildings to house the expanding populations in developed and developing regions. Any process, like particle board manufacture, which involves chipped wood and glue, offers a wide range of applications for such equipment, and here again the developing regions seem to present ideal conditions for market growth.
•
Contact Ken Sutherland Tel: +44 (0) 1737 218868 E-mail: [email protected]
Ken Sutherland has managed Northdoe, his process engineering and marketing consultancy, for over 35 years, most of that time being concerned with the marketing and technology of filtration and related processes. He has written numerous articles for Filtration + Separation, and for its sister publication Filtration Industry Analyst. He has also produced four books on filtration processes for Elsevier, including an A to Z of Filtration. He can be contacted at: Tel: +44 (0)1737 218868 or by e-mail on: [email protected] Images courtesy Shutterstock.com The editor is always pleased to receive news and articles for publication. To submit a feature please contact Alan Burrows: [email protected]
27
Feature Filtration+Separation May/June 2014
Pulp and paper
Filtration prospects in wood products and paper making I
n this article, Ken Sutherland reviews the current situation of the whole forest products sector and its uses for filtration and sedimentation equipment, not only in the manufacture of wood pulp and paper, but also for the case where wood can be considered to be playing its full part in a sustainable world.
Can we be looking at a major turn round in one of the less exciting equipment applications? Almost the whole forest products sector has taken a severe battering of late, the combination of a sharp fall in demand for paper, newsprint in particular, and the deep depression that hit most of the world from 2008 onwards. The result has been a decidedly split marketplace: with North America, Europe and Japan on the one hand, severely depressed, and the Developing World, led by China and India, on the other. There are definite signs that the losses recently suffered in the West by newspaper and other publishing are being more than made up, on the global scale, by the eager young readers in the growing populations of Asia. There was a time when wood was the main source of organic chemical products for all purposes, a function that it lost in the face of the greater availability, lower cost and easier processing, first of petroleum, and then of natural gas. Today, with the threat of an end to oil supplies as no longer unimaginable, there is talk of managed timber resources once more becoming a significant raw material for chemicals, especially if that management is undertaken sustainably.
and commercial activities using wood as a raw material, include the following applications: • the treatment of felled timber, including its weathering and preservation; • the manufacture of products from whole wood, from toothpicks to roof trusses; • the production of wood chips and the manufacture of wood particle boards and fibreboards; • the manufacture of chars and other fuel materials, and of biofuels; • the production of pure cellulose, regenerated cellulose, and viscose and rayon products; • the production of carbon products and other chemicals by the dry distillation or the solvent extraction of wood; • the manufacture of wood pulp, both firstrun and recycled, and from it, paper and paperboard of all kinds; and • the manufacture of articles from paper, paperboard and particleboard.
big users of heavy machinery, and as such the sector is a correspondingly large user of utility filters, on such services as hydraulic oil cleaning or pneumatic system filters. Boiler feed water and coolant system filters are also quite commonplace. As far as process filters are concerned, however, the sector is not a large user, with none at all required in the first two and the last of the above list of sub-sectors. Once the bulk timber needs to be reduced in size, however, for subsequent processing, there does begin to arise the need for process separation involvement, in the form of the machines required for the dry screening of the chipped wood granules, sending oversized particles back to the macerators, and diverting the undersize to fuel usage. By contrast, the processing of wood into pulp, and the conversion of that pulp into paper, use vast quantities of water: the pulp and paper industry is one of the largest industrial consumers of water, and uses more water per ton of product than any other industry. Filtration and other separation equipment have for some time been helping papermakers to reduce their environmental impact, but a major effort at improving efficiencies is still necessary to achieve some measure of sustainability in the industry.
The forest products industries
Of these subsectors, by far the largest in terms of interest to the filtration and sedimentation industry is that producing wood pulp and paper. This sub-sector is also unusual in that its main product, ie, cellulose pulp, is, so far as filtration is concerned, both a major sector product, with many uses, as well as being a key item in the whole technology of filtration, namely one of the most important types of filter medium.
The characteristics of wood
The full range of the forest products processing industries, i.e. all the industrial
With respect to the various types of filter, most parts of the forest products industry are
The chief feature of wood as far as its enduses are concerned is that it is largely made
Feature Filtration+Separation May/June 2014
There was a time when wood was the main source of organic chemical products.
up of cellulose, in the form of fibres that are embedded in a matrix of lignin, from which they are comparatively easily separated one from another, either chemically or mechanically. Wood is generally classified into hardwood (coming usually, but not entirely, from broadleaf, deciduous trees) or softwood (coming usually from coniferous, evergreen trees). The hardwoods are distinguished, in paper terms, by producing a pulp with very short fibres, which yield a weak paper, but impart a smooth finish to any paper made from them. Softwoods, on the other hand, have much longer fibres, which give a stronger paper, but with a rougher surface. Happily, an appropriate mix of pulps can usually give a paper with the required properties. The solid wood (ie, excluding bark) coming from an average tree is composed of four groups of materials: • firstly, and most importantly, there is the cellulose, making up about 45% of the dry weight of the wood, as a highly structured array of polymerised glucose chains, from which come the cellulose fibres; • secondly, there is hemi-cellulose, composed of several different sugar polymers in a much less well ordered array, making 20-25% of the dry weight, and for which there is still no economical use, except as fuel; • thirdly, and another polymer, there is lignin, also about 20-25% by weight, a complex dark-coloured compound, which binds the other components together, but which presents the major separation task in the paper production process, both to release the cellulose and to remove the colour from the final paper; and • finally, there are the extractives, a group of relatively simple organic chemicals that are recoverable by equally simple methods, such as dry distillation or solvent
One third of the world's wood pulp is now produced in China.
extraction, and include methanol, ethanol, and acetone.
The pulp and paper industry The global production of paper and paperboard (excluding merchant pulp) is now comfortably in excess of 400 million tonnes, with the slowing down in the USA and Europe more than offset by the growth in Asia. The Asian production is in excess of 40% of this, while close to 30% comes from Europe, and almost 25% from North America. China has pulled in front of the USA as the largest producing country, making over onethird of the world’s wood pulp. In individual company terms, the two largest companies in the paper business (by 2011 sales volume) were American. These were International Paper ($26bn) and Kimberly-Clark ($20.9bn), and they together represented over 13% of global sales. The top ten companies (by 2011 sales) also included six companies from Europe, two of these from Finland, and two from Japan. Together, these eight made up 40% of total global sales. Despite the large national production of pulp and paper in China, there are no very large Chinese companies as yet in this sector, although several are growing very fast, led by Nine Dragons Paper Company.
Pulp and paper making The pulp and paper industry is unusual among the end-use applications for filtration equipment in having just one main production process, which has two parts: the production of wood pulp and the manufacture of paper from it. These two parts may be contained in one plant on one site, the fully integrated mill, or quite separately as the non-integrated mill, one producing wood pulp, and the other converting pulp to paper. Apart from the need to dewater the produced pulp as thoroughly as possible, in a non-integrated pulp mill, so as to reduce the costs of transport between the two parts, there is no difference in operations between the fully integrated mill, and the two separate parts. The product of a pulp mill is a tradeable commodity, known as merchant pulp, which can be amalgamated from different sources into one paper mill to make particular kinds of paper. Although the bulk of paper originates from trees (55% from virgin pulp, and 38% from recycled wood-based paper – with 7% from non-tree sources), only about one fifth of all tree harvest goes into paper (the rest is fuel, wooden goods, particle board, etc.). It takes between two and three tons of timber to make one ton of paper, with the rest going to waste.
Production of wood pulp The total annual volume of sales of filtration and related process equipment, including filter media and membranes, to the whole forest products sector, is estimated to have been in the region of $2.5bn for the last three or four years. This total volume is only expected to rise significantly, in real (not inflated) terms, during 2014, as the Asian market starts to make up the continuing drop in the American and European markets. The three largest capital equipment companies in this sector are Andritz, Metso and Voith.
The paper production process begins with a whole tree, which needs to be separated into its component parts, either mechanically or chemically (to remove the lignin and other binders). The felled timber is first debarked, either mechanically, or by use of water jets. The separated bark is then dewatered and used on site as a fuel. There are primarily two ways of producing pulp: either mechanically,
25
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Feature Filtration+Separation May/June 2014
recycling is possible, unless a dark coloured product can be accepted. De-inking is a well-established process, involving separation equipment, but it creates another unpleasant waste stream, usually destined for landfill, so is the subject of much developmental work.
Separation equipment usage The prime use of filtration equipment in pulp and paper making relates to the sector’s need to close its water cycle as far as possible, for environmental as well as economic reasons. This move has benefited the filtration equipment suppliers, although there is still much to be done in the industry before the task is complete. The success of pulp and paper making relies on making a pulp with fibres of the correct size, and screens of one sort or another have a major role in this provision. Other uses for filtration equipment include the important recovery processes for black liquor, and bleaching and de-inking.
Wood as organic chemical raw material
Once felled, a tree is separated into its component parts either mechanically or by use of water jets.
From 2008, there has been a sharp decline in the demand for paper - newsprint in particular.
in which the whole logs are held against a grinding mechanism, which disintegrates the wood into its constituent fibres, but retains, in the product slurry, all the components of the original wood; or chemically, in which the logs are cut into chips, and the chips are dissolved in an alkaline solution, to produce a darkly coloured slurry of separated fibres.
create the correct mix for the paper quality required. This slurry is pumped into the head box (feed tank) from which a thin layer of slurry spreads out over the horizontal wire, running as a continuous roll away from the head box, and draining free of water as it does so. The wire is actually either a set of parallel strands, running the length of the machine (to produce laid paper), or, almost universally now, a fine wire mesh (to produce wove paper).
The steps that follow the main pulp producer are the refining of the slurry (to remove oversize particles) and then the bleaching of the fibres if a pale coloured or white paper is sought. Bleaching is a controversial process, in that it has relied upon chlorine or chlorine compounds, which find their way into the effluent. The industry has largely moved away from the use of free chlorine, and is now moving on to methods that do not use chlorine at all. The waste, so-called black liquors are processed to recover or remake the active chemical ingredients, which are then recycled in the mill. Potentially all of these chemicals can be recycled, although quite a significant quantity of noxious wastes is still produced. The reduction of these wastes is a continuing problem for the industry.
Papermaking The refined, and, if necessary, bleached, wood pulp is prepared as a thin slurry, together with a number of additives, especially fillers, to
The damp paper is picked up from the end of the wire and passed between sets of press and drying rolls, to bring the adsorbed water content down to that required in the finished paper. The final processes will usually include some kind of surface treatment such as calendering, to prepare it, mainly, to receive and hold ink on its surface.
Recycled paper Where recycled paper is to be used, this has to be done as a mixture of virgin and recycled pulp, because cellulose fibres cannot be recycled indefinitely – their quality decreases with each recycle process, and eight times is probably as often as can be expected. Recycled paper is much more easily pulped, and uses considerably less energy in doing so, than does the original pulping of wood. The main problem in paper recycling is the printing ink, which must be removed before
The potential use of wood as a source of organic chemicals has been mentioned, sufficient to show that a sizeable “wood refinery” could easily be developed, with perhaps as many product streams as a modern petroleum refinery. These products could include: • ethyl alcohol (from the same hydrolysis/ fermentation processes as currently yield the range of alcoholic spirit drinks, or industrial ethanol, from other raw materials); • methyl alcohol (from the same dry distillation process as first yielded charcoal and then methanol – which was initially called wood alcohol); • acetone and acetic acid (also by dry distillation); • -cellulose (a highly purified form of cellulose, which is a valuable product in its own right, as well as the precursor to a wide range of cellulose chemicals, such as the polymers cellulose acetate and cellulose nitrate); • regenerated cellulose (derived from -cellulose and a step in the formation of viscose materials, and rayon, both filament and film); and • ethers (such as ethyl cellulose, and carboxymethyl cellulose, also derived from -cellulose). With such a valuable list of products, and with wood of all kinds as raw material, it is tempting to ask why such a refinery does not exist – and the answer is easily found, namely: economics – it is just too expensive to try to make any of these products (except, of course, -cellulose) from wood as opposed to petroleum. However,
Feature Filtration+Separation May/June 2014
should the economic situation change, as might happen with the threatened “end of oil”, then the market may turn towards the forest for its organic chemicals. It is certain that, should this occur, a large market for separation equipment will be created, because many of the listed products are liquids, made in processes where feed solutions would be likely to be suspensions of wood fractions, needing separation.
Developments The complete change from a petrochemical basis for industrial activity to a wood-based one that was contemplated in the previous few paragraphs, is probably a bit far-fetched, but there are going to be some places in the world where wood pulp is abundant and petroleum as fuel is not, such that wood-based operations can be thought of sensibly, and suitable processes need to be developed. Continued increases in global paper consumption, once the effects of the recent recession have been overcome, are to be expected. Certainly the per capita consumption of paper among developing populations can be expected to cause the printing paper market to expand quite rapidly. Further progress can be expected on water and energy use efficiency in the pulping stage, on
still better waste paper recycling systems, and on wider use of timber from managed forests. The use of timber from a newly-felled tree is a fairly wasteful process, especially if it has to be transported any great distance to the pulp mill, so means whereby more of the tree can be used for top-grade applications will need to be developed. This may help to develop better quality papers, available at lower prices. There seems now to be good evidence that the electronic book reader is taking some “communication market” space away from printed paper, especially that for the daily newspaper. The production of paper from polymeric fibres, on the other hand, has been slow to take off. There is quite a lot of room in the wood fibre market before it becomes saturated, but there is also a lot of interest in alternative vegetable fibres: cotton rag (from which paper was made before wood fibre came along), jute, kenaf, and linen all have their protagonists. Jute is having a new lease of life as a supermarket bag, and eucalyptus wood is capturing a significant part of the paper market. Whatever the fibre, the paper making processes are much the same, and filters and other separation equipment will remain key components of the revamping of existing paper mills, and of the systems in ever-larger new mills to be built, especially to keep up with the demand in Asia and South America.
Separation equipment already has a good market in the construction industry’s need for particle board for coverage of new buildings to house the expanding populations in developed and developing regions. Any process, like particle board manufacture, which involves chipped wood and glue, offers a wide range of applications for such equipment, and here again the developing regions seem to present ideal conditions for market growth.
•
Contact Ken Sutherland Tel: +44 (0) 1737 218868 E-mail: [email protected]
Ken Sutherland has managed Northdoe, his process engineering and marketing consultancy, for over 35 years, most of that time being concerned with the marketing and technology of filtration and related processes. He has written numerous articles for Filtration + Separation, and for its sister publication Filtration Industry Analyst. He has also produced four books on filtration processes for Elsevier, including an A to Z of Filtration. He can be contacted at: Tel: +44 (0)1737 218868 or by e-mail on: [email protected] Images courtesy Shutterstock.com The editor is always pleased to receive news and articles for publication. To submit a feature please contact Alan Burrows: [email protected]
27