The aluminium sheet has a thickness between 6 and 200 μm. This sheet of aluminium is used, at 75%, for the packaging of products and for the manufacture of aluminium foil used in the home; 25% is used for industrial uses (car radiators, thermal insulation for buildings, conduits, aeronautics, cables and in the electronics industry).
The main applications in packaging are:
Interior coating of cardboard packaging for beverages
Bags and cartons to preserve food
Lids for yoghurt pots
Wraps for butter or cheese
Cases for drugs ("blisters"), etc.
The 6 μm aluminium sheet is normally used for packaging laminates, and can keep food fresh for months without refrigeration. It offers an authentic barrier for many fresh foods. It prevents the loss of aromas and protects against light, oxygen, moisture and pollution. It guarantees the quality and the best protection against the deterioration of delicate foods.
To produce most of these products, we start from aluminium foil coils of different thicknesses that are coated with lacquers or resins and, sometimes, lubricated with oils. These resins are polymerized at high temperature in the machines. As a consequence of this treatment, the organic compounds that contain the resins and the lubricants are evaporated. To evacuate these compounds from the interior of the machines that have passed into the gas phase, it is necessary to suck gases from the interior of the machines.
The characteristics of the gases aspirated from the interior of the machines are:
Flow rates: up to 160,000 Nm³/h
Temperature: 100 to 160 ºC
Concentration of organic pollutants: 0.8 to 3.0 g/Nm³ of Total Organic Carbon (T.O.C.)
Due to this concentration of organic compounds in the gases extracted from the machines, it is not possible to emit them into the atmosphere without debugging. It will be necessary, therefore, to install a gas purification system that eliminates organic compounds. Given the magnitude of the flow of gas to be purified and the low concentration of pollutants, it is convenient to carry out the clening by means of a regenerative thermal oxidation system (thermoreactor) because it has the following advantages:
Minimum fuel consumption, since it allows very high heat recovery efficiencies
Very low operating and maintenance costs
High purification efficiency
Long duration of the equipment
High reliability, for being highly tested equipment
Since the lacquer ovens take ambient air and heat it up to the working temperature, one way to take advantage of the heat of the purified gases is to recirculate them from the output of the thermoreactor to the oven, so the energy consumption in the burners of the ovens they will reduce their power until practically null, since the gases that are returned are at a higher temperature than the inside of the oven. In this way, the heat of the oxidation of the contaminants is used to heat the lacquer ovens. This supposes an important saving, due to the high volumes of gases that move.
Thermoreactor for cleaning 160,000 Nm³/h of gases coming from a printing and lacquering aluminium sheet industry.