Spiralex® corrugated tubular heat exchangers for thermomechanical pulping of paper
Making paper by means of pulp, made from hemp and linen fibers from battered clothing, fishnet and dust bags, was distributed to Europe in the 13th century. More and more use was made of rags that are central to the manufacture and affordability of lappaper, a factor in the development of printing.
Pulp is a lignocellulose, fibrous material prepared by chemical or mechanical separation of cellulose fibers from wood, fiber plants, waste paper or stairs. Many types of paper are made of wood, with nothing else mixed. This includes newspapers, magazines and even toilet paper. Pulp is one of the most common raw materials worldwide.
Production process of paper
Paper is manufactured by several steps:
- Harvesting trees
- Preparation for “pulping”
- The “pulping”
The pulping process
There are a number of different processes that can be used to separate the wood fiber (the pulp process or “pulping”):
- Mechanical pulp
- Chemical thermo-mechanical pulp
- Thermo-mechanical pulp
- Chemical pulp
- Recycled pulp
- Organosolv pulping
- Alternative pulp methods
Thermo-mechanical pulp is pulp made by processing wood pellets using heat (ie “thermo-“) and mechanical refining (ie “mechanical”). It is a two-stage process in which the strains are first removed from their bark and converted into small chips. These chips have a moisture content of about 25-30 percent and a mechanical force is applied to the wood discs in a crushing or grinding operation, which generates heat and water vapor. The lignin softens, separating the individual fibers. The pulp is then screened and cleaned, and any fiber hulls are reprocessed. This process gives a high fiber yield from the wood (about 95 percent) and since the lignin has not been removed, the fibers are hard and stiff.
In the project, which is described in the appendix, we have supplied various Spiralex® heat exchangers to wash and cool the pulp. The reduction of costs for this process was an important item, which we have amply met.