[Brief translation]
Making effective use of waste heat becomes an issue of industries today. The waste heat with over 120°C has been utilizing in heating process and in driving steam turbine for power generation. However, low temperature waste heat under 120°C has been only discharged into the atmosphere. In such a situation, Fuji Oil Company, Ltd. (FOC), affiliated with AOC Holdings, Inc., succeeded in operating a power plant, which outputs maximum 4,000kW at Sodegaura Refinery. It is expected that the amount of saving energy is equivalent to annually 5,600 kiloliters of crude oil, and the reductive cost becomes 200 million yen.
The reason why waste heat of approximately 110°C can generate power is because of applying ammonia-water mixture for working fluid instead of water using at thermal power plant. To drive the turbine, working fluid needs to be changed to vapor of high temperature and high pressure. Heat with 150°C is required for water of 100°C boiling point under the atmospheric pressure. While, ammonia is evaporated at 50°C under the 3-4 times of atmospheric pressure. Thus, ammonia vapor can become high pressure vapor by using heat with around 100°C. Actually, ammonia is used as working fluid by mixing with water. The ammonia-water mixing makes appropriate temperatures for vaporizing and driving the turbine and for condensing to liquid.
Mr. Inomata, General Manager of Operation Manufacture Department, FOC, said "The plant operation is kept favorable condition. We found there is excessive portion in this plant. We expect the plant has potential to reduce the initial cost in the future."
For commercial base plant using ammonia-water mixture, there are only a few number of examples. If fuel price hike continues in the future, it is expected that the effective investment for the plant will be improved by decreasing the initial cost.