선박폐열회수(WHRS) 발전용 유기랭킨사이클(ORC)의 용량선정 및 효율향상을 위한 연구

Abstract

Global Warming is a phenomenon that air temperature is gradually increased as the concentration of green house gas such as carbon dioxide, methane, etc. is increased. This is very important phenomenon which maintains the earth at certain temperature. But, gas causing green house effect is recently released too much artificially for a short time, so water temperature and sea level rise and abnormal climatic phenomenon is caused all over the world.

The release of green house gas in the whole world is continuously increased after the Industrial Revolution and particularly and rapidly increased after 1945. For 200 years, CO2 of more than about 2.3 trillion has been released to the air and more than the half is the quantity released from 1974 to the present.

In this situation, one of the technologies which can reduce CO2 generated in ship is WHRS (Marine Waste Heat Recovery System). WHRS means the system generating electric power with organic rankine cycle whose working fluid is Freon or organic media of hydrocarbon which is evaporated at the range of temperature lower than that of water so as to use existing heat source at middle and low temperature, which is released to the air, effectively.

This research which is for the selection of quantity of organic rankine cycle for WHRS generation selected fundamental specifications of closed cycle, regeneration cycle and kalina cycle and analyzed characteristics of cycle, 3 kinds of pure refrigerant and 1 kind of mixture refrigerants by temperature changes of coolant. In addition, as a measure to improve efficiency of WHRS generation cycle, the characteristics of Hysys7.3 program of Aspentech, which is widely used as a process design program of industrial field were compared and analyzed for three measures such as addition of superheater, utilization of solar heat system, using of air cooler's waste heat. And, it analyzed economic feasibility in case when WHRS generation system is applied to full line with the data obtained by this research. And, the conclusions were as follows,

1) As the result of the study on the characteristics of WHRS ORC system by output of main engine by kinds of ship, turbine output of 669.0kW for 13,000TEU container ship, 417.2kW for crude oil ship, 159.3kW for 180k bulk ship could be obtained.

2) As the result of the study on the characteristics of WHRS ORC system by kinds of cycle and coolant, regeneration cycle showed higher cycle efficiency of from 0.75% to 4.41% than closed cycle by working fluid.

3) The quantity of kalina cycle for WHRS generation whose working fluid is compound of ammonia․water was selected and cycle efficiency of 13.5% could be obtained. And, if composition ratio of compound of ammonia․water is changed, cycle output and efficiency were changed by changes of compound characteristics.

4) As the temperature of coolant of central cooling system which is used as collant of WHRS generation was increased, rate of increase range of inquired flux was increased. And, inquired flux was rapidly increased at the temperature of collant at more than 39℃.

5) Output increase of 5.42% could be obtained by overheating working fluid in state of saturated steam from the evaporator in the study on characteristics of system by addition of WHRS generation superheater. And, there was no big change for cycle efficiency by addition of superheater.

6) When using warm water generated by solar heat collecting system in WHRS generation system, improved efficiency of from 2.04% to 4.05% was shown by temperature of warm water.

7) Efficiency improvement of 2.63% was shown when installing preheater using waste heat generated in air cooler of main engine in WHRS generation system and preheating working fluid.

8) If assuming that WHRS generation system is installed and operated in 13,000TEU container ship, oil costs of from $384,915.43 to $331,336.00 was expected to be saved per a year.