SPRAY AND FILTERS FOR THE PULP AND PAPER INDUSTRY

In the paper manufacturing process there is considerable use of fresh water also coming from open basins (river or lake), because of the high quantity used in the initial stages of production we can offer solutions for the reduction of fresh water consumption without affecting the quality of services.

The filters are used in paper mills for the normal recycling and reuse of water, as well as for purifying the water coming from the external basins wells, rivers or basins.

General features and benefits of these installations:

• The application of these filters allows a remarkable recycle in water.
• They help to prevent the accumulation of pollutants (fibers) in the pipes, reducing the possibility of detachment of the material that is formed inside the pipe that is going to clog spray systems or downstream users.
• Significant water savings with obvious benefits in terms of costs and environmental impact.
• The filters are automatically cleaned when the differential pressure gauge detects a partial blockage of the cartridge, or after a set time, allowing fully automatic operation without the intervention of personnel.
• Filtration is mechanical with scrapers or brushes: the counter-washing is only useful to filter disconnected before a canning filter vacuum, so there are no wastes and additional uses of water.
• The filters mounted after the pumps require a positive pressure very low (5-6 m approx.) .
• Low waste water as the cleaning cycle lasts approximately 8 seconds during which only 4-5 seconds for the exhaust valve remains open. This allows you to download only the contents of the cartridge.
• Low pressure drop (0.2-0.3 bar) thanks to the particular shape of the cartridge, also during the cleaning cycle (in time fully open exhaust valve) the loss of flow to the users came in at approximately 25-30 % depending on the supply pressure.

In some cases the coarser filtration (for example 600 microns) is carried out on a large amount of recycled water with a large-capacity self-cleaning filter.
With some static filters that are added upstream of the users (for example, upstream of spray pipes with small diameter nozzles), filtration is perfected only where necessary.
This type of application turns out to be cheaper.

The filters are positioned to serve low-pressure spray showers in a process of recycling water (cleaning felt).

The static filters of the ALSF series (in aluminum) and ASF (in AISI 316) are positioned just before the spray tube to make further filtration after the automatic filtration.

In the paper mills a large number of spray nozzles are used, below we give you a brief example of the possible applications.

Tramite spazzole, con ugelli tipo C7E, C7C ecc.

The tubes are basically laid out in the following positions (although these may vary for different manufacturers and in relation to plant’s needs):

• Oscillating, needle jet, pressure 10-15 bar on the Dandy Cylinder (for cleaning it). This is the mesh cylinder that compacts and smoothes the surface, as well as applying filigree. This is positioned above the canvas. Here our C7 sprayer nozzles are normally used .
• Oscillating, needle jet, pressure 35-70 bar on the Suction Cylinder (for cleaning it). This is at the end of the canvas, where it pulls and canvas and provides a suction. Here our C7C type nozzles with a ceramic insert can be used, due to the normally high operating pressure.
• Fixed, fan, pressure 2-3 bar, on the canvas head cylinder (at the beginning of the canvas).
• Fixed, fan, pressure 1-2 bar, on the coupling cylinder (above the canvas, the final part on the felt side, where the spray is used for moisturising).
• The nozzles most often used for the tubes referred to above are the C7 for cleaning, with a brush inside the pipe.

The starch is used to increase strength and rigidity of the paper.
It also helps to prevent the spread of ink. The starch is made from corn, potatoes and wheat flour, to which are added chemicals (copper sulphate, , oxidants, etc.).. The application is made by two cylinders and the starch is sprayed with a hose spray nozzle in a fan, as our types MC2 and MC3.

It can treat synthetic glues, anti-mold products or spread a patina on the surface: the patina composed of kaolins (aluminum hydrated silicate) and various carbonates, strongly bonded to each other with starch.

This is a system that uses a roller press to press the sheet of paper between felt faces (which are also in a ring, like the synthetic canvas). Function: To squeeze out water and compact the sheet of paper.
Various oscillating spray showers with needle jets at pressures of 10 to 25 bar are fitted in this area. (This pressure is often laid down by the felt supplier). These are used for cleaning the felt (each piece of felt has its own). They rinse out fibers and deposits, which is essential in terms of the quality of the paper. These pipes are normally fitted before a suction tank, which is used to take residual water away.
The suction tanks (at the entrance) and some rollers are lubricated by means of fixed low pressure (1-3 bar) sprayer pipes, with very low flow rates.
These are fitted with small diameter fan nozzles. They are used to prevent the felt heating up due to rubbing against a fixed edge or turning around a roller.

They are ideal for cleaning felts, wires, fabrics and rolls thanks to the shape of their flow that guarantees high impact performance.
They are usually installed on a tube oscillating at a pressure between 15 and 40 bar for cloth cleaning.
Similar nozzles are used for trimming paper for a possible start after rupture.

Different models of CD3 nozzles are used to wash rolls on which paper slide after drying.

CD4 model is a fix nozzle, flat jet, pressure 5-15 bar, for endpaper pull down in case of broken of paper in felt zone.
It can be used for operations of abatement trim.

The nozzles model MC2 and MC3 are used to wash with clean water in medium to low pressures.
Ideal for use in the paper mills thanks to its compact shape.

Tubes with nozzles for foam abatement can be used in the inflow boxes.

In case of presence of fresh water without filtration, often is used a self cleaning nozzle.
For its cleaning is sufficient reduce pressure (about 1,5 – 2 bar) to avoid the accumulation of dirty inside.
They are available with needle jet for cleaning at high pressure and with flat jet for washing at medium-low pressure or lubrication.

Pneumatic atomizers are used for paper dampening. These nozzles are used to lubricate paper edges at the end of production run, to avoid cockle.
They have a good humidification.
Regulation of capacity and nebulization type permit to obtain a spray that can reduce scraps in production.