Pulp and Paper

Pulp and Paper Industry 

Pulp and Papers Manufacturing Industry | Pulp and Papers Manufacturing Industry In India | Pulp and Papers Training In Mumbai India

The pulp and paper industry comprises companies that make use of wood as raw material and produce pulp, paper, paperboard and other cellulose-based products.
 
The pulp and paper sector is a significant energy user and currently ranks fourth in the industrial sector for its energy use. In 2006, the sector consumed 6.7 EJ of energy, which represents 6% of global industrial energy use. Despite high energy use, the sector has a low CO2 intensity due to extensive use of biomass as fuel (in 2006, the emissions of the sector reached 184 Mt, representing only 3% of global emissions in 2006) The total energy saving potential in the sector through improved process efficiency and systems/life cycle improvements has been estimated to be in the range of 2.1-2.4 EJ/year.
 
TYPES OF PULPING
 
There are two types of Pulping i.e chemical pulping and mechanical pulping.
 
MECHANICAL PULPING
 
For the production of mechanical pulp, wood is ground against a water lubricated rotating stone. The heat generated by grinding softens the lignin binding the fibers and the mechanized forces separate the fibers to form groundwood. During the second half of the 20th century, newer mechanical techniques using ‘refiners' were developed. In a refiner, woodchips are subjected to intensive shearing forces between a rotating steel disc and a fixed plate. In subsequent modifications to this process, the woodchips are pre-softened by heat (thermo-mechanical pulp - TMP) to make the fibrillation more effective. The resulting pulp is light-colored and has longer fibers. A further development of the thermo-mechanical pulp is CTMP pulp, in which the wood chips are impregnated with a chemicals treatment with sodium sulfite before the grinding. The end result is an even lighter-colored pulp with better strength characteristics. After grinding, the pulp is sorted by screening to suitable grades. It can then be bleached with peroxide for use in higher value-added products. Mechanical pulp consists of a mix of whole fibers and fiber fragments of different sizes. Paper containing a high level of mechanical pulp and a smaller level of chemical pulp is called ‘wood-containing paper'. Mechanical pulp gives the paper a yellowish/grey tone with high opacity and a very smooth surface Mechanical pulping provides a good yield from the pulpwood because it uses the whole of the log except for the bark, but the energy requirement for refining is high and can only be partly compensated by using the bark as fuel.
 
CHEMICAL PULPING
 
For chemical pulp, logs are first chopped into wood chips which are then cooked with chemicals under high pressure. Cooking removes lignin and separates the wood into cellulose fibers. The resulting slurry contains loose but intact fibers which maintain their strength. During the process, approximately half of the wood dissolves into what is called black liquor. The cooked pulp is then washed and screened to achieve a more uniform quality. The black liquor is separated out from the pulp before the bleaching process. The most chemical pulp is made by the sulfate (or Kraft) process, in which caustic soda and sodium sulfate ‘cook' the woodchips. In the unbleached stage, a dark brown but very strong pulp results and this can be bleached to a high brightness if required. The sulfite pulping process is an alternative method best suited for specialty pulp which can be easily bleached, generally with hydrogen peroxide. These pulps fulfill the demand for ‘chlorine-free' products in the hygiene paper sector and also in printing and writing papers. The yield in both chemical processes is much lower than in the manufacture of mechanical pulp, as the lignin is completely dissolved and separated from the fibers. However, the lignin from the sulfate and some sulfite processes can be burnt as a fuel oil substitute. In modern mills, recovery boiler operations and the controlled burning of bark and other residues makes the chemical pulp mill a net energy producer which can often supply power to the grid or steam to local domestic heating plants.
A chemical pulp or paper is called woodfree, although in practice a small percentage of mechanical fiber is usually accepted.
 
TECHNOLOGY AND RESOURCE
 
The processes used to produce pulp and to dry paper are the major energy consumers in the industry. The main production facilities are either pulp mills or integrated paper and pulp mills. Integrated mills have better energy efficiency. Kraft pulping is the most extensively used chemical pulping process. It produces high-quality fibers for higher paper grades. However, it requires large amounts of heat energy and has a low fiber yield. Kraft mills are able to meet most or all of their energy needs from by-products (i.e. black liquor) and they can even be a net exporter of energy. Similarly, sulfite pulping, which is used for specialty papers, has a high energy consumption but can self-generate a large part of a mill's energy needs from by-products. Mechanical pulping produces weaker fibers but it has a high yield, giving it a lower specific final energy demand. Higher efficiencies are enabled by applications such as thermo-mechanical pulping, where heat is recovered at different grades. However, as electricity is the main energy used, this technology may have high primary energy demand and CO2 emissions. Pulp production from recovered fibers requires substantially less energy compared to the virgin pulp (the BAT values for recovered fiber is 0.7-3 GJ/t compared to around 14.3 GJ/t for Kraft pulping).1 It is a promising option for reducing energy consumption and CO2 emissions, with estimates projected to be as high as 35%. However, the availability of recovered paper is sometimes limited and resolving this issue will require changes to other parts of the paper production lifecycle. The amount of energy used by paper machines is generally dependent on the pulp quality and paper grade, and it can show big variations. Integrated mills can achieve higher energy efficiency by eliminating intermediate pulp drying and using better processes.
 
Application of Combined Heat and Power (CHP) can significantly enhance the energy efficiency of pulp and paper industry. The Combined Heat Power potential in the paper and pulp industry is estimated to be in the range of 0.3-0.6 EJ/year. Typically, the introduction of CHP can result in fuel savings of about 10-20% and energy savings of 30% compared to traditional technologies.
 
The IEA believes black-liquor gasification and bio-refinery concepts, advanced paper-drying techniques, increased paper recycling, and carbon capture and storage will play a key role in reducing energy consumption and GHG emissions in industry.
 
Marcep Inc. focus is to deliver initiatives and activities which ensure a competent and safe workforce training for the industry both now and in the future. these are some training which we have conducted successfully.
 
Pulp and Papers Manufacturing Industry | Pulp and Papers Manufacturing Industry In India | Pulp and Papers Training In Mumbai India
 
For any of consultancy or in-house training contact us on 022-62210100 or email us on techsupport@marcepinc.com

Related Industries: