WO2016105293A2

WO2016105293A2 - A method with respect to the use of microwave oven in the production of ceramic sanitary ware

Info

Publication number: WO2016105293A2
Application number: PCT/TR2015/000363
Authority: WO
Inventors: Nimet Özen; Burhan Tecen; Aybike ÜRKMEZ
Original assignee: ECZACIBAŞI YAPI GEREÇLERİ SANAYİ VE TİCARET ANONİM ŞİRKETİ ANONIM SIRKETi
Priority date: 2014-12-26
Filing date: 2015-12-21
Publication date: 2016-06-30
Also published as: WO2016105293A3

Abstract

The invention relates to a method with respect to performing the drying process, which is performed before the firing process of the semi-finished product taken from the mold, by using microwave oven in the production process of the ceramic sanitary ware. The invention relates to a method developed for the drying process of the semi-finished product taken from the mold. In the method developed within the scope of the invention, the drying process is performed with the use of microwave oven (1) and the way of loading for the ceramic sanitary ware to the microwave oven and the program order in which the microwave oven is required to be operated for the most efficient drying process are determined. Thanks to the invention according to the application, as the production speed is increased, semi-finished product storages are reduced and even eliminated, the period from the molding process of the products to the transfer thereof to the storage is reduced, the energy amount used is reduced, the time spent for supplying the products to the customer is reduced and thus the customer satisfaction is increased.

Description

DESCRIPTION

A METHOD WITH RESPECT TO THE USE OF MICROWAVE OVEN IN THE PRODUCTION OF

CERAMIC SANITARY WARE

Subject of the Invention

The invention relates to a method with respect to performing the drying process, which is performed before the firing process of the semi-finished product taken from the mold, by using microwave oven in the production process of the ceramic sanitary ware.

State of the Art

After the product is taken from the mold, it is subjected to drying stage before the firing process in the production process of the ceramic sanitary ware. Conventionally, heat transfer is provided by conduction, convection and radiation during the drying process. The conventional drying process used currently is performed in the drying ovens from outside the structure toward the inside thereof.

Conventional drying is performed in two stages as the water molecules available in the inner section of the structure rising to the surface by diffusion and being evaporated from the surface. The two most important factors in this process are the speed of diffusion occurring along the cross-section of the structure and the speed of evaporation of the water molecules from the surface. To achieve a proper drying, the speed of evaporation is required to be equal to the speed of diffusion or slightly lower than the speed of diffusion. At the same time, in order to provide a homogeneous drying subsequent to forming of the products according to the complex structure and size of the product, they are first kept in a room temperature for a certain time and then dried in the drying ovens at a certain temperature and for a certain time.

The structure taken from the mold is required to be subjected to the drying process before the firing process in the production of the ceramic sanitary ware. Humidity ratio of the structure taken from the mold is around 19-22 %. It is ensured that this ratio is dropped down to 0.5 % by drying process before the firing process. However, humidity distribution especially in the complex products is not homogeneous. Therefore, cracks occurring due to the stress in the products are observed during the drying process. To provide a homogeneous humidity distribution in the ceramic semi-finished products, the semi-finished products are kept in a room temperature for up to five days before drying according to the model and size of the product, whether it is complex or not, and to the season. Thus, a separate storage area is required for the products kept in the room temperature. After kept in room temperature said semi-finished products enter into the drying ovens where conventional drying is realized. As the grain size distribution of the FFC (Fine fire clay) and vitrified products differ, the time spent by these products in room temperature and in oven are also different from each other. The time spent by the two different structures in the room temperature and in the drying oven varies between about 10 and 15 hours. During this time, the oven temperature starts from 35 °C and rises to 75-100 °C in a way to be at different times according to the product group. Therefore, the drying section is the section where the most time is spent after the product is taken from the mold. Too much time is lost with the drying method used currently as the semi-finished product is kept for a certain time for reducing the humidity ratio before drying and also time of drying in the drying oven where the conventional drying takes place is long. Moreover as the semifinished products are kept for a certain time before entering into the drying oven, a semi-finished product storage is formed. Thereby, the need for a more free space in the production section increases.

The invention according to the application overcomes all the aforementioned problems. Thanks to performing the drying process with microwave oven in the production of ceramic sanitary ware, the semi-finished products can directly be loaded to the microwave oven for drying process without the need for waiting the humidity ratios to reduce after said products are taken from the mold. When the drying process is performed with microwave oven, the oven temperature starts from the room temperature and rises to maximum 50 °C. In this manner, the drying process, which takes days within a total period from the molding process of the product to the glazing process thereof in the state of the art, is reduced to hours. Thus, the production speed increases. Thanks to this method, productivity at a rate of about 85-90 % is achieved. Moreover, energy saving is achieved as the microwave ovens perform the heating process faster than the drying ovens where conventional drying is performed and heat only the product inside the oven.

Moreover thanks to the invention according to the application, as the production speed is increased, semi-finished product storages are reduced and even eliminated, the period from the molding process of the products to the transfer thereof to the storage is reduced, the time spent for supplying the products to the customer is reduced and thus the customer satisfaction is increased.

Object of the Invention

The object of the invention is to develop a new drying method in order to minimize and even eliminate the waiting period of the product in the room temperature for the drying process which is realized for reducing the humidity ratio prior to the firing process of the product taken from the mold in the production of the ceramic sanitary ware in the state of the art and to eliminate the space requirement for keeping the semi-finished product storages in the production area by removing the occurring semi-finished product storage. Another object of the invention is to develop a new drying method in which a drying process can be performed in way to provide obtaining the product by consuming less energy, in a shorter time in the production of the ceramic sanitary ware, and thus increase the production speed, and give less harm to the product. Description of the References:

1: Microwave Oven 2: Carrier plate 3: Stryrofoam-like Tape 4: Sink- and washbasin-like products 5: Water closet

Description of the Figures:

Figure 1: The view which shows placement of the sink- and washbasin-like products into the microwave oven

Figure 2: The view which shows placement of the water closets into the microwave oven Detailed Description of the Invention

In the method developed within the scope of the invention, the drying process prior to the firing process after the product is taken from the mold will be performed using a microwave oven (1) and thereby, the waiting period of the products during the production will be reduced and a more efficient drying process will be provided in the production of the ceramic sanitary ware.

In the conventional drying performed in the present state of the art, the product is heated from the outside toward the inside and therefore, the water molecules disposed in the inner section of the ceramic sanitary ware first rise to the surface by diffusion and then said water molecules rising to the surface are evaporated from the surface. On the contrary, in the method developed within the scope of the invention, the drying process will be performed using microwave oven, wherein microwaves are electromagnetic waves. Microwave beams interact with the material with which they are in contact. Namely, microwave beams can be absorbed by the materials with which they are in contact, can be reflected or pass through these materials. As the ceramic is an insulating material, microwave beams can pass through the ceramics and as the ceramic material has a dielectric property, the heat directly penetrates into the product. The heat increases more rapidly when compared to the conventional heating used in the present state of the art, and the process time and energy cost are reduced.

Thanks to the high-frequency electromagnetic waves in the microwave ovens, polar molecules in ceramics rotate at a certain speed occurring as a result of said frequency. As a result of the polar molecules, which occur millions of times in a second, in the semi-finished ceramic material changing direction, molecular frictional heat occurs and the product is heated. In the drying process performed with microwave oven, rather than surface drying volume drying is performed in ceramic products. Besides, the heat increases more rapidly in microwave ovens compared to the conventional ovens at the same period. Therefore, when microwave ovens are used, time of the heating process is reduced. As the heating process takes a shorter time and the microwaves have an effect only on the materials comprising polar molecule, the energy cost is low. The drying process with microwave depends on many parameters such as frequency, power of microwave, heating speed, temperature, mass, water content, density, and physical geometry.

In the method according to the application, the products taken from the mold are placed onto the carrier plates (2) in the microwave oven for the drying process and transferred on the roller. To decrease the contact surface of the products with the carrier plates (2) and to provide air circulation, styrofoam-like tapes (3) with a width of 1-2 cm are put onto the carrier plates. Products are required to be put onto said plates in certain forms so as to provide a homogeneous drying in the shortest time. Namely, water closets (5) are placed such that the inner sections of the bowls thereof will face the oven wall and sink- and washbasin-like products (4) are placed with 30-45 degree angles with the oven wall.

Microwaves are formed by means of the magnetron disposed inside the microwave ovens. Magnetron converts the electric energy into microwaves. The number of magnetron operated is selected according to the power of the magnetron. When the power of the magnetron is changed or according to the amount of water desired to be removed, the number of magnetron operated may change.

To provide an effective drying, it is monitored whether there is desired temperature and homogeneous humidity distribution in the oven. The graph showing said temperature and homogeneous humidity distribution is given below. Rh °c

m m ffi m tii Pi in iii ii] rt «-l «-l »-l t-l i-l «H r-t »-l rf

Graph 1: The graph showing the temperature and humidity ratio measurement according to time for effective drying of the product in the microwave oven The increase in temperature and decrease in humidity seen in the graph covers the period starting from the operation of the microwave oven until the full performance operation thereof. It is observed that the values are fixed when the oven starts to operate in full capacity.

Thanks to the method developed within the scope of the invention, separate loading and program works are conducted for complex (combination water closet, wall mounted water closet and floor mounted water closet, etc.) vitrified products and FFC (fine fire clay) ceramic sanitary ware, and the semi-finished product storage occurring during keeping the products in the present state of the art for a certain time for providing the homogeneous humidity distribution in ceramic structures during the drying process is removed and the semi-finished ceramic sanitary ware are directly dried in microwave ovens. Thanks to performing the drying process with microwave oven in the production of ceramic sanitary ware, the product can directly be loaded to the microwave oven for drying process without the need for waiting the humidity ratios to reduce after said product is taken from the mold. Thereby, storage area requirement for the semi-finished products is eliminated. Thanks to the use of microwave oven during drying, the total drying time during the transfer of the product from the molding process to the glazing process is reduced. As the longest time is spent for drying in the production of the ceramic sanitary ware, productivity at a rate of 85-90 % is achieved by reduction of this time. Thus, the products are supplied to the customer in a shorter time. Moreover, semi-finished product storage in the production section is eliminated.

Claims

A method with respect to the drying process of the products in the process of production of the sanitary ware products, characterized in that said drying process is performed using a microwave oven (1).

The method as in Claim 1, characterized in comprising the process steps of;

placing styrofoam-like tapes (3) with a width of 1-2 cm onto the carrier plates (2) disposed in the microwave oven (1) in order to decrease the contact of the products with the carrier plates and provide air circulation,

placing the water closets (5) on the carrier plates (2) such that the inner sections of the bowls thereof will face the oven wall, in other words, the inner sections of the bowls thereof will be parallel to the oven wall and placing the sink- and washbasin-like products (4) with 30-45 degree angles with the oven wall so as to provide the semi-finished products taken from the mold to be dried homogeneously in the shortest time, transferring the products on roller by placing the same on said carrier plates (2) in the microwave oven (1),

operating the microwave oven starting the drying process,

ending the drying process.