Proposal and Characteristics Evaluation of a Power Generation System Utilizing Waste Heat from Factories for Load Leveling Pyong Sik Pak, Member, Takashi Arima, Non-member (Osaka University) In this paper, a new steam turbine power generation system utilizing waste heat from factories is proposed for leveling the electric power load. Hydrogen and oxygen, which are produced by using excess electric power at nighttime with electrolysis of water, are used in the proposed system as fuel and oxidant, respectively. It is assumed that the saturated steam produced by utilizing waste heat from factories is available for the system to use. Changes in power generation characteristics have been estimated by using a simulation model when both the temperature of the saturated temperature and turbine inlet temperature are changed. It has been shown through simulation study that the higher the saturated steam temperature the higher the electric energy saving efficiency and the smaller the generated power at daytime, and that the higher the turbine inlet temperature the larger the generated electric power at daytime and the smaller the electric energy saving efficiency. It has been shown, for example, that 4.78 MW of the net electric power can be produced with the electric energy saving efficiency of 98.8% when turbine inlet temperature is 400 Ž, and temperature and quantity of the saturated steam is 140 Ž and 22.6t/h, respectively. This estimated value 98.8% is higher by 41.1% compared with the electric energy saving efficiency, 70%, of a pumping-up power generation system. Thus, the proposed system can be expected to become one of the high-efficient power generation systems for leveling electric power load. 1248 T. IEE Japan, Vol. 120-B, No. 10, 2000
Table 1. Assumed performance of a water electrol ysis plant. Fig. 1. Structure of a proposed power generation system utilizing waste heat from factories for level ing the electric power load.
Fig. 2. Change in the quantity of the produced saturated steam and the efficiency of waste heat @recovery boiler when the saturated steam temper ature is changed. Table 2, Exhaust gas condition of an ironworks. Table 3. Exogenous variables and parameters used for estimating system characteristics. 1250 T. IEE Japan, Vol. 120-B, No. 10, 2000
Fig. 3. Estimated characteristics of the hydro gen-oxigen-burning power generation system (for 1 t/h of saturated steam quantity).
Table 4. Characteristics of the proposed system when TIT is 400 Ž, and steam temperature is 100 Ž. Table 5. Characteristics of the proposed system when electric energy saving efficiency is maximized (TIT:400 Ž, steam temperature: 180 Ž). Fig. 4. Characteristics of the proposed system. 1252 T. IEE Japan, Vol. 120-B, No. 10, 2000
Fig. 5. Estimated state values of the proposed sys tem when turbine inlet temperature is 400 Ž and saturated steam temperature is 140 Ž.