Difference between revisions of "Cellulose, chemical pulp"
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Favorable travel temperature range: no lower limit - 30°C. At higher temperatures, the risk of mold attack increases. | Favorable travel temperature range: no lower limit - 30°C. At higher temperatures, the risk of mold attack increases. | ||
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| − | During cargo handling and transport, the cargo must be protected from all forms of moisture and excessive relative humidity. Chemical pulp has a high swelling capacity (i.e. may increase in volume by > 50%) if it absorbs moisture and the risk of mold attack and mustiness increases, especially at elevated temperatures. Mold spoils the pulp and causes disintegration. Seawater causes problems, since it leads to chemical reactions and rust spots. Technical developments in recent years implicate that processing [[plants]] react more sensitively to seawater due to closed water circuits and because most operations are carried out at neutral pH. Seawater damaged bales may be rejected. | + | During cargo handling and transport, the cargo must be protected from all forms of moisture and excessive relative humidity. Chemical pulp has a high swelling capacity (i.e. may increase in volume by > 50%) if it absorbs moisture and the risk of mold attack and mustiness increases, especially at elevated temperatures. Mold spoils the pulp and causes disintegration. Seawater causes problems, since it leads to chemical reactions and rust spots. Technical developments in recent years implicate that processing [[plants]] react more sensitively to seawater due to closed water circuits and because most operations are carried out at neutral pH. Seawater damaged bales may be rejected, but may yet be used in (degraded) papermaking. |
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Chemical pulp must be carefully ventilated, to dissipate the gases generated in production. Wet pulp should be ventilated immediately after the start of the voyage, as considerable quantities of condensation may arise due to constant water vapor release. Where wet pulp is transported in standard containers, large amounts of condensation form on the internal container skin(s). <br><br> | Chemical pulp must be carefully ventilated, to dissipate the gases generated in production. Wet pulp should be ventilated immediately after the start of the voyage, as considerable quantities of condensation may arise due to constant water vapor release. Where wet pulp is transported in standard containers, large amounts of condensation form on the internal container skin(s). <br><br> | ||
Revision as of 11:25, 4 June 2012
| Infobox on Cellulose, chemical pulp | |
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| Example of Cellulose, chemical pulp |  |
| Facts | |
| Origin | This table shows only a selection of the most important countries of origin and should not be thought of as exhaustive.
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| Stowage factor (in m3/t) |
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| Humidity / moisture |
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| Ventilation | Recommended ventilation conditions: - for dry pulp: air exchange rate: 6 changes/hour (airing) - for wet pulp: air exchange rate: 10 - 20 changes/hour (airing) See text for more particulars |
| Risk factors | Chemical pulp is highly flammable, so protect from sparks, cigarette ends, fire and naked lights. Smoldering fires are also a risk.(see also text) |
Cellulose, chemical pulp
Contents
Description
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.
Chemical pulp is subdivided into the following groups:
- sulfate pulp
- sulfite pulp
- semichemical pulp
- linters
- mechanical pulp (MP, TMP, CTMP)
in each case fully bleached, semibleached or unbleached.
During production, the cellulose fibers are separated from one another, either by pressure boiling (chemical pulping) or by mechanical comminution:
1. alkaline pressure boiling = sulfate pulp
2. acidic or neutral pressure boiling = a) sulfite pulp or b) semichemical pulp
3. mechanical comminution = mechanical pulp (MP and TMP)
4.CTMP is subjected initially to chemical/thermal pretreatment and is then mechanically comminuted, thereby assuming an intermediate position.
Pressure boiling is followed by multi-stage bleaching. Unbleached chemical pulp is brown. Once dried, chemical pulp is traded commercially in sheets, pressed blocks or rolls.
A distinction is drawn between papermaking pulps and special pulps. Special pulps are individually produced for their particular field of use, the important factor generally being chemical purity.
The most important features of papermaking pulps are whiteness, strength and cleanness. In paper and cardboard production, papermaking pulps are either used in the pure state or mixed with secondary fibers.
- Newsprint: more or less chemical pulp or mechanical pulp depending on waste paper content
- Rotogravure paper: moderate to high chemical pulp content depending on quality
- Hand-made paper: pure chemical pulp
- Imitation parchment paper: pure sulfite pulp
- Insulating paper: pure sulfate pulp, though mixtures with waste paper also possible
- Kraft sack paper: sulfate pulp
- Kraft packing paper: sulfate pulp, possibly also mixed with a small proportion of waste paper
- Toilet paper: sulfite pulp, mixed with waste paper, 100% waste paper also possible
Applications
Chemical pulps are used in the manufacture of paper and cardboard, among other things in the production of newsprint, rotogravure paper, hand-made paper, imitation parchment paper, insulating paper, kraft sack paper, kraft packing paper and toilet paper.
Shipment/storage
Chemical pulp is chiefly supplied in bales (e.g. 120 x 80 cm) weighing approx. 200 or 250 kg and rolls weighing 250 - 400 kg. The bales may also weigh between 120 and 160 kg. Packaging generally consists of white or brown paper with a high cellulose content or of actual sheets of chemical pulp. Bales of chemical pulp are held together with wires or steel strapping. For loading/unloading handling, the individual bales are generally strapped together in units of 6 or 8 or even 12.
Dry pulp may be transported in standard containers, subject to compliance with limits for water content of goods, packaging and flooring. If there is too much moisture present in the container, there is a risk that condensation wetness may deposit. When containers are not watertight, there is a risk of extraneous moisture ingress (precipitation, seawater), causing losses. Therefore it is generally better to stow the containers below deck.
Wet pulp is very susceptible to losses in standard containers, since the high water content of the goods may cause condensation wetness to deposit. The cargo must also be protected from moisture (rain, snow) and defilement.
Papermaking pulp may also be stored in the open air in the short term, provided that it is well covered and the floor is clean. It is usually set down on squared lumber or pallets. Special pulp should be stored in warehouses where possible. Chemical pulp is contaminated by fibrous materials and it is therefore important, to use wire rope or chains during cargo handling. Before the cargo is accepted, holds or containers must be absolutely clean and dry, in particular in the case of viscose pulp (silk pulp).
In the case of transport by ship, pipework must be leak-free, bilges must be inspected and hatch covers must be watertight. Where possible, dry pulp should not be stored on deck. Wet pulp may be transported on deck, but it must then be carefully protected from contact with seawater, to prevent blue discoloration. To minimize risks, it is therefore best to avoid stowage on deck.
Favorable travel temperature range: no lower limit - 30°C. At higher temperatures, the risk of mold attack increases.
During cargo handling and transport, the cargo must be protected from all forms of moisture and excessive relative humidity. Chemical pulp has a high swelling capacity (i.e. may increase in volume by > 50%) if it absorbs moisture and the risk of mold attack and mustiness increases, especially at elevated temperatures. Mold spoils the pulp and causes disintegration. Seawater causes problems, since it leads to chemical reactions and rust spots. Technical developments in recent years implicate that processing plants react more sensitively to seawater due to closed water circuits and because most operations are carried out at neutral pH. Seawater damaged bales may be rejected, but may yet be used in (degraded) papermaking.
Chemical pulp must be carefully ventilated, to dissipate the gases generated in production. Wet pulp should be ventilated immediately after the start of the voyage, as considerable quantities of condensation may arise due to constant water vapor release. Where wet pulp is transported in standard containers, large amounts of condensation form on the internal container skin(s).
Risk factors
Self-heating / Spontaneous combustion
Odor
Contamination
Mechanical influences
Toxicity / Hazards to health
Shrinkage/Shortage
Insect infestation / Diseases
Note:(Source including Transport Information Service of the GDV)