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TITLE Practical Development of Low Temperature Waste Heat Recovery Generating System
(Joint Program to Promote Technological Development with the Private Sectors)
in Hitachi Zosen Corporation
ABSTRACT We executed the practical development of generating system for relatively low temperature waste heat recovery by the use of ammonia Rankin cycle. The subjects of waste heat are gases below 200 degrees centigrade or hot water below 100 degrees centigrade, which are discharged from factories, gas turbines, or gas engines etc. This simple cycle system expected to be economical and easy to invest in the equipment.

The demonstration plant was built and the performance of the system was measured. The optimum condition or production costs were also examined. The plant was comprised of a turbine (25kW), a boiler, a condenser, a circulating pump etc. They were set in the ammonia unit of 6m length, 2.7m width, 3.6m height. Hot water was produced by heat exchange from the flue gas, which was extracted from a gas turbine co-generation plant, and supplied to the ammonia unit. Ammonia steam(75 ,3.7Mpa) which was produced by the boiler, drive the turbine, then liquefied by the condenser and returned to the ammonia boiler. Each of the equipments performed better than the planned specification during the operation. The system had worked more than 1500 hour and repeated 173 starts and stops. Slipped ammonia which was included in the purge gas from shielding ring of the turbine shaft was completely resolved by the catalyst. After the operation, we practiced subdivide examinations on the boiler, the condenser and the turbine. The results were free from any corrosion. Consequently we established reliability and safety of the system.

The developed system has a generating capacity of 1 MW when it uses the flue gas on 200, 450000Nm3/hour, for example. The system cost per output power increases as the gas volume decreases. Therefore, it is important to take cost reduction about the issues of compact ammonia boiler, high efficiency turbine and optimum system designing.

Low temperature waste heat recovery system is also effective in the control of CO2 discharge and easy on the environment. We hope it will contribute to the protection from the global warming process.