OPTIMIZATION OF THE DRYING STAGE OF SPRAYED SUSPENSIONS CERÁMICA ZANÓN S.A.

THE COMPANY

Cerámica ZANÓN, which began operations in 1980, produces glazed ceramic tile for flooring and other cladding applications. The company is the sole producer of porcellanato, or porcelain stoneware, in Argentina, in addition to being a pioneer in South America in bringing in technology for the manufacture of this product. In 1998 this company's share of the Argentine glazed ceramics market was 25%. It also exported 20% of its production to more than 35 countries, including Brazil, Uruguay, Paraguay, and Bolivia—and, to a lesser extent, Australia, Canada, the Caribbean countries, Chile, Costa Rica, Ecuador, the United States, New Zealand, Peru, and South Africa.

Cerámica ZANÓN currently has a plant with more than 120,000 square meters in the province of Neuquén, with an annual production rate of 13,200,000 square meters of porcelain stoneware, tile cladding, and glazed flooring.

DESCRIPTION OF THE PRODUCTION PROCESS

The production process for ceramic tile usually involves three stages:

THE PROJECT

Cerámica ZANÓN began an energy optimization project for the production process, with support from the Cooperation Program in the Area Of Rational Energy Use (REU), which is being carried out between the European Union and Argentina. Cerámica ZANÓN made a preliminary study to find out which stages of the process required reduction of energy consumption and which actions were necessary for optimizing the processes.

The company implemented energy reduction measures at the spraying stage in the drying process. This stage was chosen because it was the first one in the production sequence, so therefore any improvements in energy consumption or product quality in that area would have an effect on subsequent stages.

The project has been used only for compositions that turn red when they are baked. These measures may be summarized as follows:

Optimized Composition

As a part of the project development, measurements were taken of specific operating parameters in the spraying process, and comparisons were made with parameters considered to be optimum according to international criteria. The results were solids content values of 62% for porous cladding compositions and 64% for stoneware paving material. Optimum values according to international parameters range between 68 and 70%.

Cerámica ZANÓN decided to make use of actions designed to optimize its compositions. It started by decreasing the viscosity of suspensions, which increased the solids content of both products (porous cladding and stoneware paving) in compliance with ranges considered to be optimum. As a result of the changes that were introduced, viscosity for the wall tile composition decreased by 40% and viscosity for the stoneware paving material composition decreased by 30%. This occurred while linear shrinkage and water absorption of tiles remained within the recommended limits. Optimization of composition produces an energy savings ranging from 20 to 25%, in addition to a production increase of 20 to 35%.

Automatic Measurement and Control System for the Humidity of Spray Powder

Cerámica ZANÓN also installed a continuous automatic measurement and control system for the humidity of the spray powder. The increased recording frequency of the status of the humidity produces data automatically every 30 seconds, thereby providing a continuous monitoring of any variations that could arise.

It is important to mention that if humidity values are not kept within a 2% variation over time, stability decreases and the tiles produced may have different sizes. The installation of a system that measures the humidity of the powder spray keeps such variations to a minimum, by changing the temperature of the gases input into the sprayer. Use of this operational control over a relatively short period of time has maintained the humidity of sprayed powder within a variability range of ± 0.4%, with the possibility of reaching ±0.2%. In addition, this provides better knowledge of the behavior of the control system.

DECREASED CO₂ EMISSIONS

To translate the energy savings in reduced CO₂ emissions resulting from the implementation of this project at Cerámica ZANÓN, it was taken into account that the sprayer uses both electric power and heat energy, plus the fact that in Argentina 32% of electric power is generated by conventional thermoelectric processes. Since a decrease in CO₂ emissions may be determined by calculating the heat consumption and electric power consumption requirements of the sprayer, then the overall natural gas consumption of the sprayer becomes known, which amounts to 4.45 x 10⁶ nm³ per year.

Heat consumption by sprayer

Electric power consumption by sprayer

 

Total natural gas consumption by sprayer

 

If an emissions factor of 1.05 cubic meters of CO₂ per cubic meter of natural gas burned in combustion with 10% excess air is used as a basis, and if the energy decrease amounts to 30%, then the result is that the amount of CO₂ emitted before optimization was 4.67 x 10⁶ nm³ of CO₂ per year, whereas emissions after modifications to the process were 3.27 x 10⁶ nm³ of CO₂.

CO₂ emissions before optimization

CO₂ emissions after optimization

The emissions inventory for natural gas use in the Argentine industrial sector in 1994 shows a total of 12,281 x 10³ tons of CO₂ for the entire country. With its project, Cerámica ZANÓN is contributing to a decrease of 1.40 x 10⁶ nm³ of CO₂ annually—that is, 2,755 tons of CO₂ during normal conditions of pressure and temperature.

RESULTS

By implementing the abovementioned actions, the company was able to: