The secrets of coffee (II)

System for the treatment of smoke

There are regulations to prevent air pollution caused by emissions of fumes in the process of roasting the coffee and various systems to eliminate environmental pollution or reduce emissions to proper limits. We look the most important concepts.


All our roasters of coffee are equipped with this system, which reuses an important part of the combustion gases, improve their performance and encourage a significant energy saving and reduce greatly the increase of smoke into the atmosphere.

The burner of fumes:

With it we clean the gases from the roasting before they are released into the atmosphere. A burner of smoke usually operates at a temperature of 180 degrees C. The non recirculated smoke enters the first level of the burner, revolving in the direction favourable to the cast of the flame, helping its centrifuge to keep, in the second level, the maximum temperature in the same combustion chamber and thus ascend to the third level where the turn is cut to optimize the full section of the pipe exit.

Temperatures vary according to the stages of roasting, the system of natural or with input and depending on the outcome expected as regards smell, particles, opacity and percentages of components. The operating temperature limit is 750 º C

Showers of water:

They clean the cool air that carries away particles and impurities of the coffee loosened during the process. This air is drawn in by sucction by a fan and the suction expansion of the flow of air is caused as water at 3 bars of pressure is sprayed in ambient temperature. The particles are moistened and they are centrifuged to the bottom of the cyclone. The air, free of particles and cooled by the effect of the evaporation of water and by its contact with the wet walls of the cyclone, comes out along the pipe exit. The water is filtered and recycled in closed circuit, avoiding excessive consumption.

Coffee grinders
The grinding operation is the key within the chain followed to develop a good coffee, even though little importante is given to it.

The size of the ground bean should be perceptible to touch and should not be floury.

If it is little or too much ground, the least aromatic and bitterest components will dissolve excessively and the result will be a paste that will hinder the process.

For each use and for each type of machine, there is an adequate degree of grinding coffee. There was a time when it was forbidden to sell packaged ground coffee, to prevent unwanted picarescas, but today it is normal the purchase of ground coffee, so that consumers can avoid the delicate operation of grinding coffee at its axact degree.

The choice of the particle size or size of the ground particles, depends on the type of coffee machine that is going to be used in the preparation of coffee.

In both types of coffee pots, Mocca or fire ones and the filter ones, different types of grinding (from as thick as 650 m. average to the thinnest ones of 430 mu) are allowed. The final result of the same coffee in the same coffee pot will be different if we vary the grinding because of the effect of it or because of the amount of the product (the finer the grain is, the more amount of grains are in the same volumen).
It is important to control the temperature of ground coffee: this must not be over 50 ° C (the best is that temperaturas get not higher than 35 ° C) in order not to taste burned coffee and also we have more loss of gasses and aroma than usual. The engine speed, the condition of mills or rollers and cooling system are elements that must be taken into account in order to preserve the quality of the coffee.

There are two main types of mills: those that use mills and those that use rollers.

Disc grinders:
It grinds through two discs, one fixed and one rotating, trapping and breaking coffee between them. The separation of the discs is scalable, and so which accurate particle size: is obtained from an almost pulverized coffee for the turkish type to granulometries of 0.7 mm or higher.

Discs are moved by special steels of great hardness, and the design and way out are very important.  There is a lot of wear and tear due to the working temperature which expands the discs and also due to the constant friction during the grinding work.

It depends the type of grinding -more wear and tear in the fine grinding than in the ticker one- the grade of roasting.

The quality of these grinders resides mainly in the milling discs, the materials used in its preparation and cooling, which is by air, by focussing on one or both disc. A proper milling prevents a floury grinding, making the product spougy and, as a result, there is an increase in the volume of the package.

This grinding mil lis made with a capacity of up to 600 kg per hour.

Roller grinders:
They are high-volume grinders, from 300 to 4,000 kg per hour, used in the large industries processing ground coffee. They are operated by electro-hydraulic or electro mecanical and they use set or pairs of disc rollers, usually in three steps:

The feeding of the grinder is carried out by vibration with a descending conveyor, to ensure that the bean reaches the first phase with regular flow and regularly in the whole wideness of the roller. Once the coffee has passed along the various overcome the various phases of the grinding, an needles belt extractor carries it to a press to get a uniform density which will help the automatic packaging.

In such mills, the cooling of the rollers is by water. An independent module cools down the water that feeds through closed circuitthe inner part of the rollers and the needles belt.

Comments are closed.