Microwave dryer

This patent of utility aims at the construction of microwaves dryer. It is made of modules standing on a conveyor belt and impelled by an air flow whirling in spiral shapes for drying biomass chips, sawdust, grass, grains and corns, among others. It is composed of different modules working at a different electricity power, varying from 3KW to 12KW each. The modules stand on a conveyor belt.

The microwaves dryer also comprises a system which generates a ventilation capable of shaking the product and whirl it round in a revolutionary way, a spiral thanks to a spiral shape, so that all the parts of the wood are dried uniformly and efficiently, without getting carbonized and consequently without emitting the corresponding steam which arises from carbonization. This method grants a major capacity of production per hour if compared with common rotative dryers which are used for burning wood or fuel oil but they produce high temperature thus causing a difficult control of the combustion and a non-uniform product in terms of moisture contents. Besides causing a loss of biomass when it burns, the method also causes pollution because of the gas and steam emitted during carbonization.

This microwaves drying process is quite different from the combustion process since the material containing moisture crosses the tunnel of the resounding cavity and causes an absorption of the generated micro waves, forming a bipolar effect in which water and organic material start to interact and exchange electrons intensively

under a frequency of 2,450,000 Hz oscillations which cause an immediate heating of water in each particles of the biomass and draws out the inner moisture transformed into steam and potentializes the chips because part of the resin of the wood is poured out and stands on the outer pores of the wood, so as to impermeabilize it and prevent it from reabsorbing moisture from the air.

This does not occur with common dryers which work uselessly for hours and days, wasting high quantities of electricity and at the end, even if the biomass comes out with only 8% of moisture, after a few days it raises up again to 25% because the temperature it had to undergo into the dryer attained 800 ⁰ C and expanded the inner pores of the wood causing a higher capacity of moisture absorption when it is taken out of the dryer. The steams of this process are sucked by a system of ducts working through an exhaustion system which condenses volatilized oils and resin.

This condensation system is very important because in addition to avoid pollution it also recuperates the inner substances of the material which are re-utilized for organic manures and fertilizers. These inner substances can only be drawn out safely through a microwaves system.

Another characteristic of this dryer is that it is practical under the logistic point of view because it is not heavy, it is made of light metal plates and it can be easily removed thanks to its small wheels under the dryer. The modules are assembled on a conveyor belt and the drying process is continuous, forming a tunnel of micro radiation which varies its electric power from 3 to 12 KW per module. With the

assemblage of 15 modules wasting 180KW or more, the dryer attains a capacity production of up to 25 tons per hour and it makes it possible to control the desired moisture of wood-chips at a very low cost of electricity. The microwaves benefits are not at all attained by a common furnace which is very big and heavy and it needs to be conveyed by special trucks. Its production capacity is much lower in terms of tons per hour.

The present system has also the advantage of having a sensorial system which controls the moisture of the product from its entrance into the dryer so as to obtain the required dryness. By means of infra-red system and data processing, the power and the velocity of the conveyor belt is regulated for obtaining the required moisture without carbonizing the product or without exceeding the point of dryness.

Among so many advantages, the dryer has also a mechanism which affords the movement of the wood or other products into the dryer towards various directions so that the chips are dried equally on every single side by the electromagnetic waves, consequently undergoing a complete and totally uniform drying process.

Aiming at a better understanding of this invention we annex a few drawings which demonstrate the format of the dryer's modules for which is required a patent:

Figure 1 illustrates a top view of the dryer; Figure 2 illustrates a lateral view of the dryer;

Figure 3 illustrates a lateral view, in traverse section of the dryer;

Figure 4 shows a frontal view; and,

Figure 5 shows a view of the dryer in longitudinal section. According the abovementioned illustrations, this microwaves dryer consists in a structure (1) built with special metal plates painted with epoxy and a protecting material to reflect the microwaves radiation into the resounding cavity (2), forming a coat (3) into which is set a conveyor belt (4) with a velocity reducer commanding e the chains of the conveyor belt.

On the upper side of the structure is located a frequency generator with 2,45 giga hertz (5) with six or more generators installed with independent commands and waves guides (6) directed towards the resounding cavity (2) formed by the inner wall made of special metal, together with the spiral roller (7) and a duct for air flow entrance (8) produced by the blowing turbo, and in the upper part occurs the exit of steams generated in the process through the sucking duct (9) causing a negative pressure into the duct and driving all the steam to the condenser so that this negative pression is generated by the exhaustion system (10) after the steam condensation of the evaporated oil and resin, in order to recuperate them by cooling and washing them in the tower and then drawn to the tank through a duct where the oily substances are drawn out by floatation.

The material to be dried is carried by the conveyor belt 4) and its moisture is checked by a sensorial system (11) which is placed at the entrance of the dryer and its information is transferred to a computer which performs the data processing for controlling the velocity of said conveyor (4) as also the power intensity of each module, in order to obtain the expected moisture content previously scheduled in the system.

The microwaves dryer (1) is constructed with a special system of dissipators for an endless work relating to frequency generation, which is independent and affords to do repairs without stopping the dryer. The safety system of this dryer comprises combustion sensors

(12) so that if the material gets burned they stop automatically the emission of microwaves into the resounding camera and they release carbonic gas for the extinction of fire. This is one more peculiarity which makes the dryer unique since none of the furnaces existing in the market offer this solution because of their format and their high temperature.

Another safety characteristic is the blockage of radiation escape thanks to the use of metal plates painted with a special epoxy and on the accessing places of the biomass is set up pipes with circulating water which captures electromagnetic waves so as to impede the escape of electromagnetic waves either in the entrance and in the exit of the dryer.

The dryer comprises an instrument panel which activates each single generator system of electromagnetic frequency with an independent sensor for showing the inner temperature, the tension, the charging current, the dissipators and coolers for forcing the air. This instrument panel manages several modules at the same time, according to the necessity of the product to be dried.

All the system is operated through a computer which makes the operational control of the process, always based on information of the sensors installed all along the dryer and it commands the drying process, the velocity and the emission of electromagnetic radiations of each module, also adjusting the overall system

automatically for a better yield for optimizing the production capacity and to attain the lowest cost of electricity.

All these peculiar characteristics make the drying process a pioneer and modern Invention of up most importance in the industrial production of dry briquettes and pellets destinated to electricity and thermal generation by power plants which have to replace oil combustion with energetic biomass.

It is to be enhanced that this dryer may be built with various dimensions, materials, parts and additional technical specifications, provided that they stick to the main objectives of our claims.

So the kind of drying process that we are intending to patent is a new solution to any existing drying process and it fits the specific technical purposes of drying without carbonizing; drying to raise biomass calorific power; drying with efficiency just drawing out the necessary resins for impermeabilizing the biomass; drying at low cost for using microwaves system for the dehydration of wood, sawdust, grass, grains, cereals, among others, destinated to the production of briquettes, pellets and wood-chips meant for the generation of electricity into power plants where pollutant fuel has to be replaced by highly calorific biomass.

For all the reasons set out above, this innovating dryer is unique and must be registered as the first invention in this field to be protected from imitations and plagiarism.