Vol.2 No.2 2009

53/98

Research paper : A strategy to reduce energy usage in ceramic fabrication (K. Watari et al.)−133−Synthesiology - English edition Vol.2 No.2 (2009) the process control factors of mixing, dispersing, and drying. Only after several experiments, production, and assessment of prototypes, an optimal process condition can be reached. Therefore, ceramic manufacturing requires broad knowledge and experience from material preparation to sintering, in addition to high technological capability in each step. Japanese manufacturing gained high technological capability by repeating the process of extracting issues and then solving them. As a result, the Japanese ceramic products have been leading industrial competitiveness in the world. However, this technological capability may have become a black box of know-how, and no engineering investigations have been conducted. This has prevented technological development of the existing manufacturing process, and increased the distance between the site of production and academic research institutes studying production technology.3 “Valley of death” in energy-saving process technologyIt is thought that there are two “valleys of death” that must be overcome in introducing the energy-saving process technology to the site of production. For realization, there exist the “economic valley of death” concerning costs in comparison to existing technology and the “technological valley of death” concerning the introduction of the technology to the existing manufacturing line.3.1 Economic Valley of DeathThe “economic valley of death” is the increased cost in introducing the new technology. The companies are constantly pressured to reduce cost and are wary about any investment in new equipment. Even if the investment is for a technology that is expected to surpass the conventional yield, the companies are reluctant if it departs from the existing process. Therefore, the new technology must be developed under assumptions that it can be incorporated into the existing process and that the existing equipments can be used. Also, since many of the manufacturing lines are in operation 24 hours, results must be obtainable with little change as possible.3.2 Technological Valley of DeathVarious elemental technologies are suggested for energy saving in the manufacturing process. However, many such technologies have issues of complicating the steps, difficulty of incorporation in the successive process, reduction in workability, and of production of waste and hazardous materials. Also, the effort to achieve energy saving may require substantial changes in raw materials and in the existing manufacturing line. As a result, many developed technologies are not put into practical use at the site of ceramic production.4 Scenario for achieving the objectiveFor the developed technologies to be incorporated effectively at the site of production, it is necessary to overcome the aforementioned two “valleys of death.” To overcome the “valley of death,” it is important to consider the incorporation of developed technology into the existing manufacturing line. In an effort to achieve energy savings of the entire production system, the steps may become complicated and the manufacturing cost tends to rise greatly when several factors are changed. Therefore, we focused on the step that consumes high amount of energy, and clarified the relationship between the process factor and the energy consumed. Based on that result, we investigated elemental technologies that could be incorporated into the existing manufacturing line.4.1 Consumption energy needed in ceramic manufacturingFigure 1 shows the steps of the ceramic manufacturing and the flow of the input and output of the materials. Figure 2 shows the percentage of energy consumed in each step. From the result of Fig. 2, it can be seen that the steps that consume large quantities of energy are debinding, exhaust gas decomposition, and sintering. This is because heat energy is necessary for the removal of the organic binder in the green body, the conversion of exhaust gas to vapor or carbon dioxide, and for the ceramic firing. Moreover, energy efficiency is extremely low. Therefore, to reduce the amount of energy consumed by heat energy, it is necessary to: (1) Fig. 1 Steps of ceramic manufacturing and the flow of resource materials.OutputCO2 etc.ProductExhaustgastreatmentSinteringFuelDebindingFormingInputOutputFuelFuelCO2 etc.CO2 etc.DryingMixing&dispersingSolventBinderAuxiliary agentRaw powderInputInput

※このページを正しく表示するにはFlashPlayer9以上が必要です