ES2360775B1 - COMBINED MICROWAVE AND HOT AIR EQUIPMENT FOR DRYING CONSTRUCTION MATERIALS - Google Patents

Abstract

Combined microwave and hot air equipment for drying building materials. # This invention carries out the drying of laminar or bulk building materials for the removal of moisture and / or curing of resins, enamels or other treatments on high absorption supports of humidity, such as ceramics, porcelain, natural stone, etc ... for an energy and economic saving by means of a conveyor belt of pieces of transparent material or of low microwave absorption (1), which passes through a stage of input and output attenuation filters (2) and a closing chamber (7). In that chamber, a humid air extraction mechanism (4) and a dry air discharge mechanism (5) are incorporated. The latter allows a variable and adjustable volume of air to be introduced in a laminar or turbulent regime as forced convection combined with one or more microwave sources (3) that may contain a diffuser, an isolauncher, and a WR340 type guide.

Description

Combined microwave and hot air equipment for drying building materials. Technical sector

In the manufacturing processes of ceramic tiles, list them, flat ceramic borders, structural ceramics, porcelain, or natural stone, a moisture removal is required at different stages: prior to treatment, during or after it and for the purpose to eliminate the percentage of excess moisture to prepare or dry them during the production process. Said microwave composite equipment combined with hot air generators is preferably intended for monocoction lines, where it improves the mechanical resistance of the piece, increases the apparent density and prevents defects due to excess humidity, such as microcracks or chipping. Prior art

Microwave technology is used conventionally and routinely for heating food and cooking products, both industrially and domestically. As well as, it is also used for sterilization or sanitation of agri-food products, and even in other uses and sectors as diverse as the sintering of materials destined to the aeronautical industry. A very recent application is to include microwave equipment for drying construction materials, as is already known and is used for ceramic products and natural stone in the form of atomized matter or powder in order to reduce its humidity. All more related to the conditioning of the pieces by means of their heating, than for their dehydration, but always applies to static work situations of the treated parts.

Existing dehydration treatments are based on direct heat or infrared radiation systems and forced convection through combustion air. Starting, in general, with initial humidity values on porous materials from 0.5 to 40% humidity.

The use of microwave energy for dehydration has been studied and experienced in recent years and worldwide reaching the conclusion of relevant information about the physical and dielectric properties of ceramic and natural stone materials. Microwaves are electromagnetic radiation with frequencies between 300 MHz and 300 GHz, generally used in radars, telecommunications and material heating. According to certain studies, it is possible to obtain a reliable system with electromagnetic wave radiation treatments at 2.45 GHz - the only frequency authorized for industrial use in most European Union countries - in the use of resins to overcome poor thermal conductivity of the polymer ensure the volumetric heating of the resin. This conclusion is scientifically corroborated in the conclusions of the ARQUIMACON 2008 presentations of the 5th International Conference on Composite Materials in Architecture and Construction (AIMPLAS, Technological Institute of Plastic. Valencia, 2008)

Part of these studies have already been tested and initiated in the marble sector, in Spain, with the research work of UNIVERSIDAD DEMURCIA through the researchers GARCÍA RUIZ in Spanish Patent ES2160542 (2001) on a resin curing process in marbles, and by the Electromagnetism and Matter Group in industrial sectors of the Murcia region both in agri-food processing and in marble. These latest results are compiled in the Spanish patent ES224588Q (2004) of the ASO-CIACIÓN EMPRESARIAL DE INVESTIGACIÓN CENTRO TECNOLÓGICO DEL MÁRMOL Y LA PIEDRA (2004) on a resin polymerization process applied on the marble using microwaves.

Similarly, the investigations disclosed in PCT International Patent WO04030882 by VE-KINIS and GYLLIS (2004) regarding a method and apparatus for thermal conditioning of wet ceramic products.

The first two Spanish patents mentioned refer to procedures or methods of techniques applied to marble, while the international patent also refers to an apparatus intended for ceramic products. All of them do not raise the subsequent problems arising from curing with resins and electromagnetic microwave radiation, in terms of the design of equipment that are technically viable, and economically and energy efficient.

And that, as such, these procedures must be carried out with a qualitative leap to the procedures already disclosed in relation to the con fi guration of media and distribution of elements that make operationally and industrially applicable to curing resins or enamels with microwaves on materials of construction. In addition to solving the problems arising from continuous manufacturing processes or passenger transport lines of manufacturers or transformers of marble and ceramic products, for which there are great demands of technical skill, and economic viability. There is no efficiency, no product quality. Technical problem

In certain manufacturing and treatment processes of laminar construction materials, it is observed that due to an excess of moisture in the piece or tile or in the enamel itself, quality defects that are difficult to correct in line can be caused, and that involve final products low quality

or intended for direct destruction.

In the natural stone and ceramics sector, the technologies traditionally used for heating treatments or conditioning are based on gas burners, normally propane or natural gas that in the form of vertical dryers, or horizontal direct flame type, tubes and / or radiant plates that are very aggressive and harmful. These systems do not guarantee the previous evaporation of surface moisture, and are not suitable for intermediate applications, nor for certain types of building materials.

Another major problem in curing procedures with resins and electromagnetic waves is caused by the effect of wave dispersion when working with wide or open spaces and / or moving, which can frustrate curing operations and lead to unusable products. or deteriorated Therefore, specific and precise designs and con fi gurations are required.

Technical solution

There are several proposals for technical improvements that are likely to constitute our own inventive concept, which we set out below. First, it is a device or device that implements a combined microwave and forced hot air system that accelerates the evaporation of volatile water and solvents. This idea is very important, since the persistence of remains or traces of them have failed to combine non-combined systems, since, by itself, microwave energy only heats.

In the same way, the equipment with said con fi guration of the combined microwave-hot air system is essential for curing water-based resins, where it is necessary to extract the moisture from the different strata. In this, technology combined with hot air makes an important difference.

The same happens when trying to dehydrate laminated or bulk materials, if the water stays out, it ends up being absorbed by capillarity.

In addition, the use of polypropylene as a transport belt means that microwave heat or energy does not accumulate on the transport mat, altering excessively and irregularly the treated products.

Another important aspect, together with the above mentioned of a mixed microwave-hot air system, and of polypropylene means in the transport bands, is the design of the diffusers inside. Its perfect and studied distribution means that the energy is distributed equally, which makes us capable of obtaining a homogeneous result, using the same system with the injected air, which is previously heated to a range of 20-600ºC.

Finally, the technical problem of wave dispersion is solved so that the equipment developed for industrial processes contains a passage system and attenuation filters that reduce and control the dispersion in an effective way - thanks to a design of fi lters tuned to the working frequency in the so-called “wave trap” phenomenon, despite being open structures that do not allow the escape of electromagnetic waves in a certain frequency range. Thus, con fi ning the energy inside the furnace, and thus becoming a continuous and safe and efficient moving process. Advantageous effects

Among the advantages of the invention presented, we can observe several of a fundamentally energetic, productive and economic nature. Among the energy advantages we have found environmental variables such as the reduction of energy consumption by the substitution of traditional energies (industrial gas or fuel burners), the suppression of in fl ammable processes due to leaks or thermal losses due to the use of such fuels, the elimination of emission of CO2 gases when replacing fossil fuels, reasonable and sustainable energy consumption, the use of water-based resins to the detriment of those preparations and formulations that emit in their processing and curing volatile organic compounds highly toxic and pollutants called VOCs, Like styrene.

On a productive level, we appreciate an exhaustive and monitored control of moisture suppression by evaporation of water, and the acceleration of said drying process by the penetration power of the waves on the materials, and by the collision of water molecules contained. We also observe a guarantee in the result of a dried piece that is proportional in a greater exposure to hot air, a shorter exposure time and attack of the waves. As well as, the destruction of defective products is minimized considerably.

All this results in a benefit of the quality of the product, and in accordance with the procedures of technical approval and industrial standardization (UNE RULES and ISO RULES) in the construction sector - especially ceramics and natural stone.

Also, the state of the art achieved manages to bring together in a compact and operational equipment all the advantages already mentioned.

From all this we can deduce with overwhelming logic that, less energy consumption, less lost due to defective parts, high drying speed, and a continuous and passage moving production

or in line of transport they translate, in euros, in a great economic saving for the industrial users.

Description of the fi gures

For a better understanding of the general characteristics mentioned above, a drawing is attached to the present invention which sets forth as specified below:

Figure 1: Profile view of a combined microwave and hot air equipment for drying construction materials formed by a belt for transporting parts (1), attenuation filters (2), one or more microwave sources (3 ), wet air extraction mechanism (4), dry air drive mechanism (6), part or tile (6), chassis or enclosure chamber (7). How to carry out the invention

First, it is necessary to highlight some preliminary notes on the type of elements and techniques used. Thus, the production process that incorporates the invention begins after the detection of the moving tile with the generation and diffusion of microwave waves of non-ionizing radiation generated by electronic equipment that emits a wavelength of 2, 45 Ghz This is done through linear guides whose function is to distribute energy in a linear way that is absorbed more efficiently than open radiation. In the absence of absorbed energy, the reflected energy will increase so that a cooling circuit dissipating the generated energy will be necessary. As an example, if the emitted energy is distributed by the surface within a range of values of 500 w on a surface of 15 x 120 x 2.3 cm3, that is 0.12 w / cm3, up to a value of 6000 w at 15 x 60 x 1 cm3, that is 6.66 w / cm3, we would have a range of power densities between 0.12-6.66 w / cm3, the normal values being between 0.2-5 w / cm3 .

It is essential in this invention the correct location of the guides to maximize the uniformity of the field in the immediate vicinity of the center of the chamber. The power guide itself alters the camera's electric field distribution. The locations and orientation of the waveguides therefore depend on the dimensions of the structure and the shape of the modules, both exterior and interior, depending on the electric and magnetic fields of each mode.

Since each of the multiple magnetrons operate individually, the net power density is the superposition of the individual power densities. To obtain a uniformity of heating in the tiles it is necessary to excite many modes. The most valid option is to use several fixed power magnetrons. Therefore, the positioning and orientation of the guides will determine which modes will be excited in the cavity. The guide of the type referred to as WR340 normally contains the dominant mode TE10: its advantage is that it equally excites TE (electric transverse) and TM (magnetic transverse) modes and protects the magnetron to a certain extent with a minimum wavelength. The main objective is to introduce waves into the chamber through the rectangular and metal waveguides of the so-called WR340 waveguides from the sources at a frequency of 2.45 GHz.

Once the perfect adjustment of uniform powers and balanced distribution has been achieved, it has been necessary to design the attenuation fi lters that manage to avoid leaks in the entrance and exit mouths of the tunnel that con fi gures the chassis or enclosure frame and concentrates the magnetic fields generated. These are fi lters of three categories. The first, modal fi lters based on geometric shapes formed by pillars (round or square) and Jo by flash bounces determined by computer programs of wave reflection simulation design, depending on their dimensions and configuration. The second category of fi lters are the filtering blankets that absorb and prevent the reflection of the waves. And as a third possibility, the fi lters are conduits with circulating water that absorb or attenuate the residual powers. Likewise, a joint combination can be made from one to three categories of filters, depending on the powers, materials or dimensions of the inlet and outlet mouths.

From a general perspective, the operation is based on the effect of molecular friction and, consequently, on the heating caused by microwaves in materials that present a polarity in their molecules. For example, all those materials that contain water. In fact, when materials stand out for more polar characteristics, they have a greater capacity to absorb microwave energy, while apolar materials are usually even harmless or transparent or have low absorption of this energy.

The dimensions of the diffusers and the power of the magnetrons are fundamental design parameters to ensure that all the water in the treated materials receives all the necessary energy equally distributed at an acceptable work rate for the production process. Likewise, the combined incorporation of another complementary system such as forced air with thermal gradients adjusted to the level of temperature range that allows the process -with regulation between 20º and 600ºC-, replaces and avoids the use of fossil fuels and CO2 emission from combustion, facilitating the quality of the resulting product.

Another important factor for the design of the equipment is the power variable, since the microwave power provided determines the economic cost of the installation. If an installation increases its capacity linearly, its price increases exponentially. Therefore, a power limit of the installation that makes the installation profitable must be established. Taking into account that magnetrons of great power are much more expensive, it is preferable to use magnetrons of small or medium power, not only for economic reasons but also to obtain a more prolonged and uniform process.

Finally, the chamber or enclosure as a closed chassis, is formed by a group or set of diffusers where the energy is exchanged with the absorbent materials.

As a conclusion of all the above, we can describe in an operational and functional way the provision of technical means that make up the equipment of the invention and that can be interpreted with Figure 1: A belt for transporting parts (1), which it passes through a stage of input and output attenuation filters (2) and a closing chamber (7). These attenuation fi lters (2) - modal or geometric, filtering blankets, or water pipes, or all of them combined with each other - may be variable depending on the microwave power installed in the enclosure chamber (7), free height, and geometry of the inlet and outlet mouth of such filters. The enclosure chamber (7) is variable in its dimensions depending on the width and thickness of the pieces to be treated (6), the length and exposure time of those pieces, and the sum of the power of the MW sources of diffuser installed.

Inside the enclosure chamber (7), a humid air extraction mechanism (4) and a dry air discharge mechanism (5) are incorporated. The latter allows to introduce a variable air volume that can be adjusted in temperature from the outside, from an ambient temperature up to 600ºC in a laminar or turbulent regime as forced convection combined with one or several microwave sources with diffuser (3).

This microwave source (3), with or without a diffuser, consists of a 2.45 GHz magnetron or microwave emitter with different emission powers that can be incorporated inside or outside an isolauncher or wave attenuator reflected with an insulator, and a flange preferably of the type R26. All of them can be cooled by air and / or water.

In the case of using a diffuser, a WR340 type guide can be incorporated to standardize the electromagnetic waves inside the enclosure chamber (7).

Claims (8)

one.

Combined microwave and hot air equipment for drying laminar or bulk construction materials for the elimination of moisture and / or curing of resins, enamels or other treatments on high moisture absorption supports characterized by a conveyor belt for passing parts of transparent or low microwave absorption material (1), which passes through a stage of input and output attenuation filters (2) and a enclosure chamber (7). Inside said enclosure chamber, a humid air extraction mechanism (4) and a dry air discharge mechanism (5) are incorporated. The latter allows to introduce a variable air volume that can be adjusted in temperature from the outside, from an ambient temperature to a temperature of 600ºC in a laminar or turbulent regime as forced convection combined with one or several microwave sources (3).

2.

Combined microwave and hot air equipment for drying laminar or bulk construction materials for the removal of moisture and / or curing of resins, enamels or other treatments on high moisture absorption supports according to Claim 1 characterized in that one or several sources Microwave (3) contains a diffuser.

3.

Combined microwave and hot air equipment for drying laminar or bulk construction materials for the elimination of moisture and / or curing of resins, enamels or other treatments on high moisture absorption supports according to Claim 1 and 2 characterized in that the microwave source ( 3) incorporates an isolauncher or wave attenuator re fl ected with insulator and / or a flange of type R26.

Four.

Combined microwave and hot air equipment for drying laminar or bulk construction materials for the elimination of moisture and / or curing of resins, enamels or other treatments on high moisture absorption supports according to Claim 1, 2 and 3 characterized in that the microwave source (3), and the isolauncher or wave attenuator re fl ected with insulator are cooled by air and / or water.

5.

Combined microwave and hot air equipment for drying laminar or bulk construction materials for the elimination of moisture and / or curing of resins, enamels or other treatments on high moisture absorption supports according to Claim 2, 3 and 4 characterized in that a guide of the type WR340 will be incorporated, to standardize the electromagnetic waves inside the enclosure chamber (7).

6.

Combined microwave and hot air equipment for drying laminar or bulk construction materials for the removal of moisture and / or curing of resins, enamels or other treatments on high moisture absorption supports according to Claim 1, 2, 3, 4 , and characterized in that the attenuation filters (2) are modal or geometric, filtering blankets, or water pipes, or all or some of them combined with each other.

7.

Combined microwave and hot air equipment for drying laminar or bulk construction materials for the removal of moisture and / or curing of resins, enamels or other treatments on high moisture absorption supports according to Claim 1, 2, 3, 4 , 5 and 6 characterized in that the attenuation filters (2) incorporate a leak measurement system in the outlets as a safety element.

SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 200931081 SPAIN Date of submission of the application: 30.11.2009 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: F26B3 / 34 (2006.01) RELEVANT DOCUMENTS

Category

Documents cited Claims Affected

And

GB 2425164 A (S.M.C. SRL) 10/18/2006, pages 11 to 14; Figures 1 and 2 US 4176267 A (RUEGGEBERG) 11/27/1979, lines 60 to 67, column 2; figures 1-7 1-7

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 04.04.2011

Examiner A. Pérez Igualador Page 1/4

REPORT OF THE STATE OF THE TECHNIQUE Application number: 200931081 Minimum documentation searched (classification system followed by classification symbols) F26B Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC State of the Art Report Page 2/4  WRITTEN OPINION Application number: 200931081 Date of Completion of Written Opinion: 04.04.2011 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 1-7 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-7 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/4  WRITTEN OPINION Application number: 200931081 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

GB 2425164 A (S.M.C. SRL) 18.10.2006

D02

US 4176267 A (RUEGGEBERG) 11/27/1979

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement Document D01 describes an apparatus for drying granular material by means of microwave radiation and convection of driven drying air. The material goes on a conveyor belt that moves along a chamber in which there is installed means to emit microwave radiation. The independent claim 1 claims: - "a conveyor belt of transparent or low microwave absorption material" The conveyor belt of document D01, as can be read on page 12, reflects the radiation it receives and is composed of two layers, one of Kevlar and the other of silicon-based material. Therefore, although it does not absorb the radiation is not transparent to it but reflects it. There is a difference in this between D01 and claim 1. - "with one or several microwave sources" In D01 there are several microwave sources. This technical feature is fully anticipated. - "which passes through a stage of input and output attenuation filters" Attendance filters are not explicitly described in D01. - "and a closing chamber" The apparatus of D01 comprises a chamber, which is in the description and in the drawings with reference 1. - "a humid air extraction mechanism and a humid air discharge mechanism are incorporated" An air circulation system appears on page 8 and in the figures (from D01). - "variable air temperature adjustable, from an ambient temperature to a temperature of 600 º C" On the same page 8 it can be read that the air system is temperature adjustable. - "in laminar or turbulent regime" This technical feature also does not appear explicit in D01. Document D02 refers to a microwave containment system for microwave ovens of the type of which They use a conveyor belt. It is, in this system, to neutralize microwave leaks in the environment of the entrance and exit doors. For this, it has installed radiation absorption units (11) of which they consist in a chamber with resonant elements and absorbent elements. On the other hand, D02 provides that the conveyor belt is made of a material that does not absorb microwave energy, by example a plastic (lines 60 to 65 of column 2). Therefore, the characteristics of claim 1 which were not found in D01 are disclosed in document D02: the use of attenuation filters and the use of a material without microwave absorption for the band conveyor Document D01, considered the most relevant in the state of the art, anticipates the technical characteristics of the claim 1 except the mentioned characteristics. However, these characteristics are disclosed by D02. The person skilled in the art could therefore consider the device as a normal design option to include these features. disclosed by D01, thus anticipating all the technical characteristics of claim 1. Therefore, no inventive activity can be seen in this 1st claim. The object of claims 2 to 7 includes only embodiments and accessory elements to the object of the invention of the independent claim 1. An expert in the field could use them without exercise inventiveness. In conclusion, all claims 1 to 7 lack inventive activity (Articles 4 and 8 of the Patent Law 11/1986). State of the Art Report Page 4/4